1
|
Mira Hernandez J, Shen EY, Ko CY, Hourani Z, Spencer ER, Smoliarchuk D, Bossuyt J, Granzier H, Bers DM, Hegyi B. Differential sex-dependent susceptibility to diastolic dysfunction and arrhythmia in cardiomyocytes from obese diabetic HFpEF model. Cardiovasc Res 2024:cvae070. [PMID: 38666446 DOI: 10.1093/cvr/cvae070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Revised: 02/29/2024] [Accepted: 03/17/2024] [Indexed: 06/06/2024] Open
Abstract
AIM Sex-differences in heart failure with preserved ejection fraction (HFpEF) are important, but key mechanisms involved are incompletely understood. While animal models can inform about sex-dependent cellular and molecular changes, many previous preclinical HFpEF models have failed to recapitulate sex-dependent characteristics of human HFpEF. We tested for sex-differences in HFpEF using a two-hit mouse model (leptin receptor-deficient db/db mice plus aldosterone infusion for 4 weeks; db/db+Aldo). METHODS AND RESULTS We performed echocardiography, electrophysiology, intracellular Ca2+ imaging, and protein analysis. Female HFpEF mice exhibited more severe diastolic dysfunction in line with increased titin N2B isoform expression and PEVK element phosphorylation, and reduced troponin-I phosphorylation. Female HFpEF mice had lower BNP levels than males despite similar comorbidity burden (obesity, diabetes) and cardiac hypertrophy in both sexes. Male HFpEF mice were more susceptible to cardiac alternans. Male HFpEF cardiomyocytes (versus female) exhibited higher diastolic [Ca2+], slower Ca2+ transient decay, reduced L-type Ca2+ current, more pronounced enhancement of the late Na+ current, and increased short-term variability of action potential duration (APD). However, male and female HFpEF myocytes showed similar downregulation of inward rectifier and transient outward K+ currents, APD prolongation, and frequency of delayed afterdepolarizations. Inhibition of Ca2+/calmodulin-dependent protein kinase II (CaMKII) reversed all pathological APD changes in HFpEF in both sexes, and empagliflozin pretreatment mimicked these effects of CaMKII inhibition. Vericiguat had only slight benefits, and these effects were larger in HFpEF females. CONCLUSION We conclude that the db/db+Aldo preclinical HFpEF murine model recapitulates key sex-specific mechanisms in HFpEF and provides mechanistic insights into impaired excitation-contraction coupling and sex-dependent differential arrhythmia susceptibility in HFpEF with potential therapeutic implications. In male HFpEF myocytes, altered Ca2+ handling and electrophysiology aligned with diastolic dysfunction and arrhythmias, while worse diastolic dysfunction in females may depend more on altered myofilaments properties.
Collapse
Affiliation(s)
- Juliana Mira Hernandez
- Department of Pharmacology, University of California, Davis, CA, USA
- Research Group Biogenesis, Faculty of Agricultural Sciences, Veterinary Medicine, University of Antioquia, Medellin-Colombia
| | - Erin Y Shen
- Department of Pharmacology, University of California, Davis, CA, USA
| | - Christopher Y Ko
- Department of Pharmacology, University of California, Davis, CA, USA
| | - Zaynab Hourani
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, USA
| | - Emily R Spencer
- Department of Pharmacology, University of California, Davis, CA, USA
| | - Daria Smoliarchuk
- Department of Pharmacology, University of California, Davis, CA, USA
| | - Julie Bossuyt
- Department of Pharmacology, University of California, Davis, CA, USA
| | - Henk Granzier
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, USA
| | - Donald M Bers
- Department of Pharmacology, University of California, Davis, CA, USA
| | - Bence Hegyi
- Department of Pharmacology, University of California, Davis, CA, USA
| |
Collapse
|
2
|
Rhee TM, Ahn HJ, Kim S, Lee SR, Choi EK, Oh S. Predictive Value of Electromechanical Window for Risk of Fatal Ventricular Arrhythmia. J Korean Med Sci 2023; 38:e186. [PMID: 37337809 DOI: 10.3346/jkms.2023.38.e186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Accepted: 02/27/2023] [Indexed: 06/21/2023] Open
Abstract
BACKGROUND As an indicator of electro-mechanical coupling, electromechanical window (EMW) can be used to predict fatal ventricular arrhythmias. We investigated the additive effect of EMW on the prediction of fatal ventricular arrhythmias in high-risk patients. METHODS We included patients who had implantable cardioverter-defibrillator (ICD) implanted for primary or secondary prevention. The event group was defined as those who received an appropriate ICD therapy. We acquired echocardiograms at ICD implantation and follow-up. The EMW was calculated as the difference between the interval from QRS onset to aortic valve closure and QT interval from the electrocardiogram embedded in the continuous wave doppler image. We evaluated the predictive value of EMW for predicting fatal ventricular arrhythmia. RESULTS Of 245 patients (67.2 ± 12.8 years, 63.7% men), the event group was 20.0%. EMW at baseline (EMW-Baseline) and follow-up (EMW-FU) was significantly different between event and control groups. After adjustment, both EMW-Baseline (odds ratio [OR]adjust 1.02 [1.01-1.03], P = 0.004) and EMW-FU (ORadjust 1.06 [1.04-1.07], P < 0.001) remained as significant predictors for fatal arrhythmic events. Adding EMW-Baseline significantly improved the discriminating ability of the multivariable model including clinical variables (area under the curve [AUC] 0.77 [0.70-0.84] vs. AUC 0.72 [0.64-0.80], P = 0.004), while a univariable model using EMW-FU alone showed the best performance among models (AUC 0.87 [0.81-0.94], P = 0.060 against model with clinical variables; P = 0.030 against model with clinical variables and EMW-Baseline). CONCLUSION The EMW could effectively predict severe ventricular arrhythmia in ICD implanted patients. This finding supports the importance of incorporating the electro-mechanical coupling index into the clinical practice for predicting future fatal arrhythmia events.
Collapse
Affiliation(s)
- Tae-Min Rhee
- Department of Internal Medicine, Seoul National University Hospital, Seoul, Korea
| | - Hyo-Jeong Ahn
- Department of Internal Medicine, Seoul National University Hospital, Seoul, Korea
| | - Sunhwa Kim
- Department of Internal Medicine, Seoul National University Hospital, Seoul, Korea
| | - So-Ryoung Lee
- Department of Internal Medicine, Seoul National University Hospital, Seoul, Korea
| | - Eue-Keun Choi
- Department of Internal Medicine, Seoul National University Hospital, Seoul, Korea
| | - Seil Oh
- Department of Internal Medicine, Seoul National University Hospital, Seoul, Korea.
| |
Collapse
|
3
|
Alexander C, Bishop MJ, Gilchrist RJ, Burton FL, Smith GL, Myles RC. Initiation of ventricular arrhythmia in the acquired long QT syndrome. Cardiovasc Res 2023; 119:465-476. [PMID: 35727943 PMCID: PMC10064840 DOI: 10.1093/cvr/cvac103] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 04/25/2022] [Accepted: 06/02/2022] [Indexed: 11/15/2022] Open
Abstract
AIMS Long QT syndrome (LQTS) carries a risk of life-threatening polymorphic ventricular tachycardia (Torsades de Pointes, TdP) and is a major cause of premature sudden cardiac death. TdP is induced by R-on-T premature ventricular complexes (PVCs), thought to be generated by cellular early-afterdepolarisations (EADs). However, EADs in tissue require cellular synchronisation, and their role in TdP induction remains unclear. We aimed to determine the mechanism of TdP induction in rabbit hearts with acquired LQTS (aLQTS). METHODS AND RESULTS Optical mapping of action potentials (APs) and intracellular Ca2+ was performed in Langendorff-perfused rabbit hearts (n = 17). TdP induced by R-on-T PVCs was observed during aLQTS (50% K+/Mg++ & E4031) conditions in all hearts (P < 0.0001 vs. control). Islands of AP prolongation bounded by steep voltage gradients (VGs) were consistently observed before arrhythmia and peak VGs were more closely related to the PVC upstroke than EADs, both temporally (7 ± 5 ms vs. 44 ± 27 ms, P < 0.0001) and spatially (1.0 ± 0.7 vs. 3.6 ± 0.9 mm, P < 0.0001). PVCs were initiated at estimated voltages of ∼ -40 mV and had upstroke dF/dtmax and Vm-Ca2+ dynamics compatible with ICaL activation. Computational simulations demonstrated that PVCs could arise directly from VGs, through electrotonic triggering of ICaL. In experiments and the model, sub-maximal L-type Ca2+ channel (LTCC) block (200 nM nifedipine and 90% gCaL, respectively) abolished both PVCs and TdP in the continued presence of aLQTS. CONCLUSION These data demonstrate that ICaL activation at sites displaying steep VGs generates the PVCs which induce TdP, providing a mechanism and rationale for LTCC blockers as a novel therapeutic approach in LQTS.
Collapse
Affiliation(s)
- Cherry Alexander
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Martin J Bishop
- School of Biomedical Engineering and Imaging Sciences, King’s College London, St Thomas' Hospital, Westminster Bridge Road, London SE1 7EH, UK
| | - Rebecca J Gilchrist
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Francis L Burton
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Godfrey L Smith
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Rachel C Myles
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
| |
Collapse
|
4
|
Haugsten Hansen M, Sadredini M, Hasic A, Anderson ME, Sjaastad I, Korseberg Stokke M. CaMKII and reactive oxygen species contribute to early reperfusion arrhythmias, but oxidation of CaMKIIδ at methionines 281/282 is not a determining factor. J Mol Cell Cardiol 2023; 175:49-61. [PMID: 36528076 DOI: 10.1016/j.yjmcc.2022.12.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Revised: 12/07/2022] [Accepted: 12/12/2022] [Indexed: 12/16/2022]
Abstract
BACKGROUND Available evidence suggest that Ca2+/calmodulin-dependent protein kinase type IIδ (CaMKIIδ) and reactive oxygen species (ROS) are important in early ischemia-reperfusion arrhythmias (IRA). Since ROS can activate CaMKIIδ by oxidation of two methionines at positions 281/282, oxidized-CaMKIIδ (Ox-CaMKIIδ) has been proposed to be important for IRA. However, direct evidence for this is missing. METHODS We exposed Langendorff-perfused hearts and ventricular cardiomyocytes from C57BL/6 mice to global and simulated ischemia, respectively, and recorded arrhythmic events during early reperfusion. Hearts were collected for immunoblotting of key phosphoproteins. We evaluated the effects of beta-adrenoceptor stimulation, inhibition of CaMKII, and reduced ROS levels with isoprenaline, KN93/AIP and N-acetylcysteine (NAC), respectively. We further tested the importance of Ox-CaMKIIδ by using hearts and cardiomyocytes from mice with CaMKIIδ resistant to oxidation of methionines 281 and 282 (MMVV). RESULTS Hearts treated with KN93, AIP or NAC had lower incidence of early IRA, and NAC-treated cardiomyocytes had lower incidence of arrhythmogenic events. However, hearts from MMVV mice had a similar incidence of early IRA to wild type mice (WT), and MMVV and WT cardiomyocytes had a similar frequency of Ca2+ waves and Ca2+ sparks. Immunoblotting confirmed high levels of oxidation in early reperfusion, but revealed no significant differences in the phosphorylation levels of Ca2+-handling proteins in MMVV and WT hearts. CONCLUSIONS Although CaMKII and ROS both contribute to early IRA, hearts from mice with CaMKII resistant to oxidation at methionines 281/282 were not protected from such arrhythmias, suggesting that oxidation at these sites is not a determining factor.
Collapse
Affiliation(s)
- Marie Haugsten Hansen
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway; KG Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
| | - Mani Sadredini
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway; KG Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
| | - Almira Hasic
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway; KG Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
| | - Mark E Anderson
- Division of Cardiology, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Ivar Sjaastad
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway; KG Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
| | - Mathis Korseberg Stokke
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway; KG Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway; Department of Cardiology, Oslo University Hospital Rikshospitalet, Oslo, Norway.
| |
Collapse
|
5
|
Hegyi B, Mira Hernandez J, Ko CY, Hong J, Shen EY, Spencer ER, Smoliarchuk D, Navedo MF, Bers DM, Bossuyt J. Diabetes and Excess Aldosterone Promote Heart Failure With Preserved Ejection Fraction. J Am Heart Assoc 2022; 11:e027164. [PMID: 36416174 PMCID: PMC9851441 DOI: 10.1161/jaha.122.027164] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Background The pathobiology of heart failure with preserved ejection fraction (HFpEF) is still poorly understood, and effective therapies remain limited. Diabetes and mineralocorticoid excess are common and important pathophysiological factors that may synergistically promote HFpEF. The authors aimed to develop a novel animal model of HFpEF that recapitulates key aspects of the complex human phenotype with multiorgan impairments. Methods and Results The authors created a novel HFpEF model combining leptin receptor-deficient db/db mice with a 4-week period of aldosterone infusion. The HFpEF phenotype was assessed using morphometry, echocardiography, Ca2+ handling, and electrophysiology. The sodium-glucose cotransporter-2 inhibitor empagliflozin was then tested for reversing the arrhythmogenic cardiomyocyte phenotype. Continuous aldosterone infusion for 4 weeks in db/db mice induced marked diastolic dysfunction with preserved ejection fraction, cardiac hypertrophy, high levels of B-type natriuretic peptide, and significant extracardiac comorbidities (including severe obesity, diabetes with marked hyperglycemia, pulmonary edema, and vascular dysfunction). Aldosterone or db/db alone induced only a mild diastolic dysfunction without congestion. At the cellular level, cardiomyocyte hypertrophy, prolonged Ca2+ transient decay, and arrhythmogenic action potential remodeling (prolongation, increased short-term variability, delayed afterdepolarizations), and enhanced late Na+ current were observed in aldosterone-treated db/db mice. All of these arrhythmogenic changes were reversed by empagliflozin pretreatment of HFpEF cardiomyocytes. Conclusions The authors conclude that the db/db+aldosterone model may represent a distinct clinical subgroup of HFpEF that has marked hyperglycemia, obesity, and increased arrhythmia risk. This novel HFpEF model can be useful in future therapeutic testing and should provide unique opportunities to better understand disease pathobiology.
Collapse
Affiliation(s)
- Bence Hegyi
- Department of PharmacologyUniversity of CaliforniaDavisCA
| | - Juliana Mira Hernandez
- Department of PharmacologyUniversity of CaliforniaDavisCA
- Research Group in Veterinary Medicine (GIVET), School of Veterinary MedicineUniversity Corporation Lasallista (Unilasallista)CaldasAntioquiaColombia
| | | | - Junyoung Hong
- Department of PharmacologyUniversity of CaliforniaDavisCA
| | - Erin Y. Shen
- Department of PharmacologyUniversity of CaliforniaDavisCA
| | | | | | | | - Donald M. Bers
- Department of PharmacologyUniversity of CaliforniaDavisCA
| | - Julie Bossuyt
- Department of PharmacologyUniversity of CaliforniaDavisCA
| |
Collapse
|
6
|
Alhede C, Higuchi S, Hadjis A, Bibby D, Abraham T, Schiller NB, Gerstenfeld EP. Premature Ventricular Contractions Are Presaged by a Mechanically Abnormal Sinus Beat. JACC Clin Electrophysiol 2022; 8:943-953. [PMID: 35843863 DOI: 10.1016/j.jacep.2022.05.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 04/22/2022] [Accepted: 05/12/2022] [Indexed: 10/17/2022]
Abstract
BACKGROUND Frequent premature ventricular contractions (PVCs) can lead to cardiomyopathy; it is unclear if there are abnormal myocardial mechanics operative in the PVC and non-PVC beats. OBJECTIVES The aim of this study was to investigate regional and global myocardial mechanics, including dyssynchrony, in patients with frequent PVCs. METHODS Fifty-six consecutive patients referred for PVC ablation were prospectively studied. During sinus rhythm (SR) and PVC beats, left ventricular (LV) global longitudinal strain (GLS), LV dyssynchrony (measured as the SD of time to peak GLS), and dyssynergy (measured as maximum regional strain minus minimum regional strain at aortic valve closure) were quantified using 2-dimensional strain echocardiography. GLS, dyssynchrony, and dyssynergy were compared in remote SR, pre-PVC SR, PVC, and post-PVC SR beats. RESULTS In SR beats remote from the PVC, GLS was -17.3% ± 4%, dyssynchrony was 49 ± 14 ms, and dyssynergy was 22% ± 9%. Myocardial mechanics were significantly abnormal during PVCs compared with remote SR beats (GLS -7.7% ± 3% [P < 0.001], dyssynchrony 115 ± 37 milliseconds [P < 0.001], and dyssynergy 26% ± 10% [P < 0.001]). There were significant mechanical abnormalities in the SR beat preceding the PVC, which demonstrated significantly lower LV strain (pre-PVC SR, -13% ± 4%; P < 0.001) and more dyssynchrony (pre-PVC SR, 63 ± 19 milliseconds; P < 0.001) compared with remote SR beats. Dyssynergy was significantly higher for pre-PVC SR and PVC beats compared with remote SR (pre-PVC SR, 25% ± 8% [P < 0.001]; PVC, 26% ± 10% [P < 0.001]). CONCLUSIONS In patients with frequent PVCs, the SR beat preceding the PVC demonstrates significant mechanical abnormalities. This finding suggests that perturbations in cellular physiological processes such as excitation-contraction coupling may underlie the generation of frequent PVCs.
Collapse
Affiliation(s)
- Christina Alhede
- Section of Electrophysiology, University of California-San Francisco, San Francisco, California, USA
| | - Satoshi Higuchi
- Section of Electrophysiology, University of California-San Francisco, San Francisco, California, USA
| | - Alexios Hadjis
- Section of Electrophysiology, University of California-San Francisco, San Francisco, California, USA
| | - Dwight Bibby
- Section of Echocardiography, University of California-San Francisco, San Francisco, California, USA
| | - Theodore Abraham
- Section of Echocardiography, University of California-San Francisco, San Francisco, California, USA
| | - Nelson B Schiller
- Section of Echocardiography, University of California-San Francisco, San Francisco, California, USA
| | - Edward P Gerstenfeld
- Section of Electrophysiology, University of California-San Francisco, San Francisco, California, USA.
| |
Collapse
|
7
|
Kawakami S, Kambayashi R, Takada K, Aimoto M, Nagasawa Y, Takahara A. Role of cardiac α1-adrenoreceptors for the torsadogenic action of IKr blocker nifekalant in the anesthetized atrioventricular block rabbit. J Pharmacol Sci 2022; 150:67-73. [DOI: 10.1016/j.jphs.2022.07.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 06/30/2022] [Accepted: 07/19/2022] [Indexed: 10/16/2022] Open
|
8
|
Klein MG, Krantz MJ, Fatima N, Watters A, Colon-Sanchez D, Geiger RM, Goldstein RE, Solhjoo S, Mehler PS, Flagg TP, Haigney MC. Methadone Blockade of Cardiac Inward Rectifier K + Current Augments Membrane Instability and Amplifies U Waves on Surface ECGs: A Translational Study. J Am Heart Assoc 2022; 11:e023482. [PMID: 35658478 PMCID: PMC9238736 DOI: 10.1161/jaha.121.023482] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Background Methadone is associated with a disproportionate risk of sudden death and ventricular tachyarrhythmia despite only modest inhibition of delayed rectifier K+ current (IKr), the principal mechanism of drug-associated arrhythmia. Congenital defects of inward rectifier K+ current (IK1) have been linked to increased U-wave amplitude on ECG and fatal arrhythmia. We hypothesized that methadone may also be a potent inhibitor of IK1, contributing to delayed repolarization and manifesting on surface ECGs as augmented U-wave integrals. Methods and Results Using a whole-cell voltage clamp, methadone inhibited both recombinant and native IK1 with a half-maximal inhibitory concentration IC50) of 1.5 μmol/L, similar to that observed for IKr block (half-maximal inhibitory concentration of 2.9 μmol/L). Methadone modestly increased the action potential duration at 90% repolarization and slowed terminal repolarization at low concentrations. At higher concentrations, action potential duration at 90% repolarization lengthening was abolished, but its effect on terminal repolarization rose steadily and correlated with increased fluctuations of diastolic membrane potential. In parallel, patient ECGs were analyzed before and after methadone initiation, with 68% of patients having a markedly increased U-wave integral compared with premethadone (lead V3; mean +38%±15%, P=0.016), along with increased QT and TPeak to TEnd intervals, likely reflective of IKr block. Conclusions Methadone is a potent IK1 inhibitor that causes augmentation of U waves on surface ECG. We propose that increased membrane instability resulting from IK1 block may better explain methadone's arrhythmia risk beyond IKr inhibition alone. Drug-induced augmentation of U waves may represent evidence of blockade of multiple repolarizing ion channels, and evaluation of the effect of that agent on IK1 may be warranted.
Collapse
Affiliation(s)
- Michael G Klein
- Cardiology Division Department of Medicine Uniformed Services University Bethesda MD
| | - Mori J Krantz
- Denver Health Medical Center Cardiology Division Denver CO.,Department of Medicine University of Colorado School of Medicine Aurora CO.,Chief Science Advisor Cardiac Safety and Cardiovascular Imaging, Clario Inc. Philadelphia PA
| | - Naheed Fatima
- Department of Anatomy, Physiology & Genetics Uniformed Services University Bethesda MD
| | - Ashlie Watters
- ACUTE at Denver Health Denver CO.,Department of Medicine University of Colorado School of Medicine Aurora CO
| | - Dayan Colon-Sanchez
- Psychiatry Division Outpatient Behavioral Health Services, Denver Health, & University of Colorado School of Medicine Denver CO
| | - Robert M Geiger
- Department of Anatomy, Physiology & Genetics Uniformed Services University Bethesda MD
| | - Robert E Goldstein
- Cardiology Division Department of Medicine Uniformed Services University Bethesda MD
| | - Soroosh Solhjoo
- Cardiology Division Department of Medicine Uniformed Services University Bethesda MD.,Military Cardiovascular Outcomes Research (MiCOR) Bethesda MD
| | - Philip S Mehler
- ACUTE at Denver Health Denver CO.,Department of Medicine University of Colorado School of Medicine Aurora CO
| | - Thomas P Flagg
- Department of Anatomy, Physiology & Genetics Uniformed Services University Bethesda MD
| | - Mark C Haigney
- Cardiology Division Department of Medicine Uniformed Services University Bethesda MD.,Military Cardiovascular Outcomes Research (MiCOR) Bethesda MD
| |
Collapse
|
9
|
Odening KE, van der Linde HJ, Ackerman MJ, Volders PGA, ter Bekke RMA. OUP accepted manuscript. Eur Heart J 2022; 43:3018-3028. [PMID: 35445703 PMCID: PMC9443984 DOI: 10.1093/eurheartj/ehac135] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2021] [Revised: 02/23/2022] [Accepted: 03/03/2022] [Indexed: 11/13/2022] Open
Abstract
An abundance of literature describes physiological and pathological determinants of cardiac performance, building on the principles of excitation–contraction coupling. However, the mutual influencing of excitation–contraction and mechano-electrical feedback in the beating heart, here designated ‘electromechanical reciprocity’, remains poorly recognized clinically, despite the awareness that external and cardiac-internal mechanical stimuli can trigger electrical responses and arrhythmia. This review focuses on electromechanical reciprocity in the long-QT syndrome (LQTS), historically considered a purely electrical disease, but now appreciated as paradigmatic for the understanding of mechano-electrical contributions to arrhythmogenesis in this and other cardiac conditions. Electromechanical dispersion in LQTS is characterized by heterogeneously prolonged ventricular repolarization, besides altered contraction duration and relaxation. Mechanical alterations may deviate from what would be expected from global and regional repolarization abnormalities. Pathological repolarization prolongation outlasts mechanical systole in patients with LQTS, yielding a negative electromechanical window (EMW), which is most pronounced in symptomatic patients. The electromechanical window is a superior and independent arrhythmia-risk predictor compared with the heart rate-corrected QT. A negative EMW implies that the ventricle is deformed—by volume loading during the rapid filling phase—when repolarization is still ongoing. This creates a ‘sensitized’ electromechanical substrate, in which inadvertent electrical or mechanical stimuli such as local after-depolarizations, after-contractions, or dyssynchrony can trigger abnormal impulses. Increased sympathetic-nerve activity and pause-dependent potentiation further exaggerate electromechanical heterogeneities, promoting arrhythmogenesis. Unraveling electromechanical reciprocity advances the understanding of arrhythmia formation in various conditions. Real-time image integration of cardiac electrophysiology and mechanics offers new opportunities to address challenges in arrhythmia management.
Collapse
Affiliation(s)
| | - Henk J van der Linde
- Janssen Research & Development, Division of Janssen Pharmaceutica N.V., Beerse, Belgium
| | - Michael J Ackerman
- Department of Cardiovascular Medicine, Division of Heart Rhythm Services (Windland Smith Rice Genetic Heart Rhythm Clinic), Mayo Clinic, Rochester, MN, USA
- Department of Pediatric and Adolescent Medicine, Division of Pediatric Cardiology, Mayo Clinic, Rochester, MN, USA
- Department of Molecular Pharmacology & Experimental Therapeutics (Windland Smith Rice Sudden Death Genomics Laboratory), Mayo Clinic, Rochester, MN, USA
| | - Paul G A Volders
- Department of Cardiology, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University Medical Center+, P. Debyelaan 25, 6229 HX, Maastricht, The Netherlands
| | | |
Collapse
|
10
|
Hegyi B, Shimkunas R, Jian Z, Izu LT, Bers DM, Chen-Izu Y. Mechanoelectric coupling and arrhythmogenesis in cardiomyocytes contracting under mechanical afterload in a 3D viscoelastic hydrogel. Proc Natl Acad Sci U S A 2021; 118:e2108484118. [PMID: 34326268 PMCID: PMC8346795 DOI: 10.1073/pnas.2108484118] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The heart pumps blood against the mechanical afterload from arterial resistance, and increased afterload may alter cardiac electrophysiology and contribute to life-threatening arrhythmias. However, the cellular and molecular mechanisms underlying mechanoelectric coupling in cardiomyocytes remain unclear. We developed an innovative patch-clamp-in-gel technology to embed cardiomyocytes in a three-dimensional (3D) viscoelastic hydrogel that imposes an afterload during regular myocyte contraction. Here, we investigated how afterload affects action potentials, ionic currents, intracellular Ca2+ transients, and cell contraction of adult rabbit ventricular cardiomyocytes. We found that afterload prolonged action potential duration (APD), increased transient outward K+ current, decreased inward rectifier K+ current, and increased L-type Ca2+ current. Increased Ca2+ entry caused enhanced Ca2+ transients and contractility. Moreover, elevated afterload led to discordant alternans in APD and Ca2+ transient. Ca2+ alternans persisted under action potential clamp, indicating that the alternans was Ca2+ dependent. Furthermore, all these afterload effects were significantly attenuated by inhibiting nitric oxide synthase 1 (NOS1). Taken together, our data reveal a mechano-chemo-electrotransduction (MCET) mechanism that acutely transduces afterload through NOS1-nitric oxide signaling to modulate the action potential, Ca2+ transient, and contractility. The MCET pathway provides a feedback loop in excitation-Ca2+ signaling-contraction coupling, enabling autoregulation of contractility in cardiomyocytes in response to afterload. This MCET mechanism is integral to the individual cardiomyocyte (and thus the heart) to intrinsically enhance its contractility in response to the load against which it has to do work. While this MCET is largely compensatory for physiological load changes, it may also increase susceptibility to arrhythmias under excessive pathological loading.
Collapse
Affiliation(s)
- Bence Hegyi
- Department of Pharmacology, University of California, Davis, CA 95616
| | - Rafael Shimkunas
- Department of Pharmacology, University of California, Davis, CA 95616
- Department of Biomedical Engineering, University of California, Davis, CA 95616
| | - Zhong Jian
- Department of Pharmacology, University of California, Davis, CA 95616
| | - Leighton T Izu
- Department of Pharmacology, University of California, Davis, CA 95616
| | - Donald M Bers
- Department of Pharmacology, University of California, Davis, CA 95616
| | - Ye Chen-Izu
- Department of Pharmacology, University of California, Davis, CA 95616;
- Department of Biomedical Engineering, University of California, Davis, CA 95616
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of California, Davis, CA 95616
| |
Collapse
|
11
|
Yang PC, Giles WR, Belardinelli L, Clancy CE. Mechanisms of flecainide induced negative inotropy: An in silico study. J Mol Cell Cardiol 2021; 158:26-37. [PMID: 34004185 PMCID: PMC8772296 DOI: 10.1016/j.yjmcc.2021.05.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Revised: 05/11/2021] [Accepted: 05/12/2021] [Indexed: 11/27/2022]
Abstract
It is imperative to develop better approaches to predict how antiarrhythmic drugs with multiple interactions and targets may alter the overall electrical and/or mechanical function of the heart. Safety Pharmacology studies have provided new insights into the multi-target effects of many different classes of drugs and have been aided by the addition of robust new in vitro and in silico technology. The primary focus of Safety Pharmacology studies has been to determine the risk profile of drugs and drug candidates by assessing their effects on repolarization of the cardiac action potential. However, for decades experimental and clinical studies have described substantial and potentially detrimental effects of Na+ channel blockers in addition to their well-known conduction slowing effects. One such side effect, associated with administration of some Na+ channel blocking drugs is negative inotropy. This reduces the pumping function of the heart, thereby resulting in hypotension. Flecainide is a well-known example of a Na+ channel blocking drug, that exhibits strong rate-dependent block of INa and may cause negative cardiac inotropy. While the phenomenon of Na+ channel suppression and resulting negative inotropy is well described, the mechanism(s) underlying this effect are not. Here, we set out to use a modeling and simulation approach to reveal plausible mechanisms that could explain the negative inotropic effect of flecainide. We utilized the Grandi-Bers model [1] of the cardiac ventricular myocyte because of its robust descriptions of ion homeostasis in order to characterize and resolve the relative effects of QRS widening, flecainide off-target effects and changes in intracellular Ca2+ and Na+ homeostasis. The results of our investigations and predictions reconcile multiple data sets and illustrate how multiple mechanisms may play a contributing role in the flecainide induced negative cardiac inotropic effect.
Collapse
Affiliation(s)
- Pei-Chi Yang
- Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, United States of America
| | - Wayne R Giles
- Department of Physiology & Pharmacology, University of Calgary, Canada
| | | | - Colleen E Clancy
- Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, United States of America.
| |
Collapse
|
12
|
Taggart P, Pueyo E, Duijvenboden SV, Porter B, Bishop M, Sampedro-Puente DA, Orini M, Hanson B, Rinaldi CA, Gill JS, Lambiase P. Emerging evidence for a mechanistic link between low-frequency oscillation of ventricular repolarization measured from the electrocardiogram T-wave vector and arrhythmia. Europace 2021; 23:1350-1358. [PMID: 33880542 PMCID: PMC8427352 DOI: 10.1093/europace/euab009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Indexed: 11/17/2022] Open
Abstract
Strong recent clinical evidence links the presence of prominent oscillations of ventricular repolarization in the low-frequency range (0.04–0.15 Hz) to the incidence of ventricular arrhythmia and sudden death in post-MI patients and patients with ischaemic and non-ischaemic cardiomyopathy. It has been proposed that these oscillations reflect oscillations of ventricular action potential duration at the sympathetic nerve frequency. Here we review emerging evidence to support that contention and provide insight into possible underlying mechanisms for this association.
Collapse
Affiliation(s)
- Peter Taggart
- Department of Cardiovascular Sciences, University College London, London, UK
| | - Esther Pueyo
- BSICOS Group, 13A, 11S, Aragon, University of Zaragoza, Spain.,CIBER-BBN, Zaragoza, Spain
| | | | - Bradley Porter
- Department of Imaging Sciences and Biomedical Engineering, KCL, London, UK
| | - Martin Bishop
- Department of Imaging Sciences and Biomedical Engineering, KCL, London, UK
| | | | - M Orini
- Department of Cardiovascular Sciences, University College London, London, UK
| | - B Hanson
- UCL Mechanical Engineering, University College London, London, UK
| | | | | | - Pier Lambiase
- Department of Cardiovascular Sciences, University College London, London, UK
| |
Collapse
|
13
|
Tse G, Hao G, Lee S, Zhou J, Zhang Q, Du Y, Liu T, Cheng SH, Wong WT. Measures of repolarization variability predict ventricular arrhythmogenesis in heptanol-treated Langendorff-perfused mouse hearts. Curr Res Physiol 2021; 4:125-134. [PMID: 34746832 PMCID: PMC8562203 DOI: 10.1016/j.crphys.2021.04.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Revised: 04/07/2021] [Accepted: 04/12/2021] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Time-domain and non-linear methods can be used to quantify beat-to-beat repolarization variability but whether measures of repolarization variability can predict ventricular arrhythmogenesis in mice have never been explored. METHODS Left ventricular monophasic action potentials (MAPs) were recorded during constant right ventricular 8 Hz pacing in Langendorff-perfused mouse hearts, in the presence or absence of the gap junction and sodium channel inhibitor heptanol (0.1, 0.5, 1 or 2 mM). RESULTS Under control conditions, mean action potential duration (APD) was 39.4 ± 8.1 ms. Standard deviation (SD) of APDs was 0.3 ± 0.2 ms, coefficient of variation was 0.9 ± 0.8% and the root mean square (RMS) of successive differences in APDs was 0.15 ± 0.14 ms. Poincaré plots of APDn+1 against APDn revealed ellipsoid morphologies with a SD along the line-of-identity (SD2) to SD perpendicular to the line-of-identity (SD1) ratio of 4.6 ± 2.1. Approximate and sample entropy were 0.61 ± 0.12 and 0.76 ± 0.26, respectively. Detrended fluctuation analysis revealed short- and long-term fluctuation slopes of 1.49 ± 0.27 and 0.81 ± 0.36, respectively. Heptanol at 2 mM induced ventricular tachycardia in five out of six hearts. None of the above parameters were altered by heptanol during which reproducible electrical activity was observed (KW-ANOVA, P > 0.05). Contrastingly, SD2/SD1 decreased to 2.03 ± 0.41, approximate and sample entropy increased to 0.82 ± 0.12 and 1.45 ± 0.34, and short-term fluctuation slope decreased to 0.82 ± 0.19 during the 20-s period preceding spontaneous ventricular tachy-arrhythmias (n = 6, KW-ANOVA, P < 0.05). CONCLUSION Measures of repolarization variability, such as SD2/SD1, entropy, and fluctuation slope are altered preceding the occurrence of ventricular arrhythmogenesis in mouse hearts. Changes in these variables may allow detection of impending arrhythmias for early intervention.
Collapse
Affiliation(s)
- Gary Tse
- Tianjin Key Laboratory of Ionic-Molecular Function of Cardiovascular Disease, Department of Cardiology, Tianjin Institute of Cardiology, Second Hospital of Tianjin Medical University, Tianjin, 300211, China
- Cardiovascular Analytics Group, Laboratory of Cardiovascular Physiology, Hong Kong, China
| | - Guoliang Hao
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Sharen Lee
- Cardiovascular Analytics Group, Laboratory of Cardiovascular Physiology, Hong Kong, China
| | - Jiandong Zhou
- School of Data Science, City University of Hong Kong, Hong Kong, China
| | - Qingpeng Zhang
- School of Data Science, City University of Hong Kong, Hong Kong, China
| | - Yimei Du
- Research Center of Ion Channelopathy, Institute of Cardiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Tong Liu
- Tianjin Key Laboratory of Ionic-Molecular Function of Cardiovascular Disease, Department of Cardiology, Tianjin Institute of Cardiology, Second Hospital of Tianjin Medical University, Tianjin, 300211, China
| | - Shuk Han Cheng
- Department of Biomedical Sciences, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong
| | - Wing Tak Wong
- School of Life Sciences, Chinese University of Hong Kong, Hong Kong, China
| |
Collapse
|
14
|
Synková I, Bébarová M, Andršová I, Chmelikova L, Švecová O, Hošek J, Pásek M, Vít P, Valášková I, Gaillyová R, Navrátil R, Novotný T. Long-QT founder variant T309I-Kv7.1 with dominant negative pattern may predispose delayed afterdepolarizations under β-adrenergic stimulation. Sci Rep 2021; 11:3573. [PMID: 33574382 PMCID: PMC7878757 DOI: 10.1038/s41598-021-81670-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 12/30/2020] [Indexed: 11/30/2022] Open
Abstract
The variant c.926C > T (p.T309I) in KCNQ1 gene was identified in 10 putatively unrelated Czech families with long QT syndrome (LQTS). Mutation carriers (24 heterozygous individuals) were more symptomatic compared to their non-affected relatives (17 individuals). The carriers showed a mild LQTS phenotype including a longer QTc interval at rest (466 ± 24 ms vs. 418 ± 20 ms) and after exercise (508 ± 32 ms vs. 417 ± 24 ms), 4 syncopes and 2 aborted cardiac arrests. The same haplotype associated with the c.926C > T variant was identified in all probands. Using the whole cell patch clamp technique and confocal microscopy, a complete loss of channel function was revealed in the homozygous setting, caused by an impaired channel trafficking. Dominant negativity with preserved reactivity to β-adrenergic stimulation was apparent in the heterozygous setting. In simulations on a human ventricular cell model, the dysfunction resulted in delayed afterdepolarizations (DADs) and premature action potentials under β-adrenergic stimulation that could be prevented by a slight inhibition of calcium current. We conclude that the KCNQ1 variant c.926C > T is the first identified LQTS-related founder mutation in Central Europe. The dominant negative channel dysfunction may lead to DADs under β-adrenergic stimulation. Inhibition of calcium current could be possible therapeutic strategy in LQTS1 patients refractory to β-blocker therapy.
Collapse
Affiliation(s)
- Iva Synková
- Department of Medical Genetics, University Hospital Brno and Faculty of Medicine, Masaryk University, Jihlavská 20, 625 00, Brno, Czech Republic.,Department of Experimental Biology, Faculty of Science, Masaryk University, Kotlářská 267/2, 611 37, Brno, Czech Republic
| | - Markéta Bébarová
- Department of Physiology, Faculty of Medicine, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic.
| | - Irena Andršová
- Department of Internal Medicine and Cardiology, University Hospital Brno and Faculty of Medicine, Masaryk University, Jihlavská 20, 625 00, Brno, Czech Republic
| | - Larisa Chmelikova
- Department of Biomedical Engineering, Faculty of Electrical Engineering and Communication, Brno University of Technology, Technická 10, 616 00, Brno, Czech Republic
| | - Olga Švecová
- Department of Physiology, Faculty of Medicine, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
| | - Jan Hošek
- Division of Biologically Active Complexes and Molecular Magnets, Regional Centre of Advanced Technologies and Materials, Faculty of Science, Palacký University in Olomouc, Šlechtitelů 27, 783 71, Olomouc, Czech Republic
| | - Michal Pásek
- Department of Physiology, Faculty of Medicine, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic.,Institute of Thermomechanics, Czech Academy of Sciences, Dolejškova 5, 182 00, Prague, Czech Republic
| | - Pavel Vít
- Department of Paediatrics, University Hospital Brno and Faculty of Medicine, Masaryk University, Černopolní 9, 613 00, Brno, Czech Republic
| | - Iveta Valášková
- Department of Medical Genetics, University Hospital Brno and Faculty of Medicine, Masaryk University, Jihlavská 20, 625 00, Brno, Czech Republic
| | - Renata Gaillyová
- Department of Medical Genetics, University Hospital Brno and Faculty of Medicine, Masaryk University, Jihlavská 20, 625 00, Brno, Czech Republic
| | - Rostislav Navrátil
- Repromeda, Clinic for Reproductive Medicine and Preimplantation Genetic Diagnosis, Biology Park, Studentská 812/6, 625 00, Brno, Czech Republic
| | - Tomáš Novotný
- Department of Internal Medicine and Cardiology, University Hospital Brno and Faculty of Medicine, Masaryk University, Jihlavská 20, 625 00, Brno, Czech Republic
| |
Collapse
|
15
|
Sampedro-Puente DA, Raphel F, Fernandez-Bes J, Laguna P, Lombardi D, Pueyo E. Characterization of Spatio-Temporal Cardiac Action Potential Variability at Baseline and Under β-Adrenergic Stimulation by Combined Unscented Kalman Filter and Double Greedy Dimension Reduction. IEEE J Biomed Health Inform 2021; 25:276-288. [PMID: 32248135 DOI: 10.1109/jbhi.2020.2984647] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
OBJECTIVE Elevated spatio-temporal variability of human ventricular repolarization has been related to increased risk for ventricular arrhythmias and sudden cardiac death, particularly under β-adrenergic stimulation ( β-AS). This work presents a methodology for theoretical characterization of temporal and spatial repolarization variability at baseline conditions and in response to β-AS. For any measured voltage trace, the proposed methodology estimates the parameters and state variables of an underlying human ventricular action potential (AP) model by combining Double Greedy Dimension Reduction (DGDR) with automatic selection of biomarkers and the Unscented Kalman Filter (UKF). Such theoretical characterization can facilitate subsequent characterization of underlying variability mechanisms. MATERIAL AND METHODS Given an AP trace, initial estimates for the ionic conductances in a stochastic version of the baseline human ventricular O'Hara et al. model were obtained by DGDR. Those estimates served to initialize and update model parameter estimates by the UKF method based on formulation of an associated nonlinear state-space representation and joint estimation of model parameters and state variables. Similarly, β-AS-induced phosphorylation levels of cellular substrates were estimated by the DGDR-UKF methodology. Performance was tested by building an experimentally-calibrated population of virtual cells, from which synthetic AP traces were generated for baseline and β-AS conditions. RESULTS The combined DGDR-UKF methodology led to 25% reduction in the error associated with estimation of ionic current conductances at baseline conditions and phosphorylation levels under β-AS with respect to individual DGDR and UKF methods. This improvement was not at the expense of higher computational load, which was diminished by 90% with respect to the individual UKF method. Both temporal and spatial AP variability of repolarization were accurately characterized by the DGDR-UKF methodology. CONCLUSIONS A combined DGDR-UKF methodology is proposed for parameter and state variable estimation of human ventricular cell models from available AP traces at baseline and under β-AS. This methodology improves the estimation performance and reduces the convergence time with respect to individual DGDR and UKF methods and renders a suitable approach for computational characterization of spatio-temporal repolarization variability to be used for ascertainment of variability mechanisms and its relation to arrhythmogenesis.
Collapse
|
16
|
Varró A, Tomek J, Nagy N, Virág L, Passini E, Rodriguez B, Baczkó I. Cardiac transmembrane ion channels and action potentials: cellular physiology and arrhythmogenic behavior. Physiol Rev 2020; 101:1083-1176. [PMID: 33118864 DOI: 10.1152/physrev.00024.2019] [Citation(s) in RCA: 72] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Cardiac arrhythmias are among the leading causes of mortality. They often arise from alterations in the electrophysiological properties of cardiac cells and their underlying ionic mechanisms. It is therefore critical to further unravel the pathophysiology of the ionic basis of human cardiac electrophysiology in health and disease. In the first part of this review, current knowledge on the differences in ion channel expression and properties of the ionic processes that determine the morphology and properties of cardiac action potentials and calcium dynamics from cardiomyocytes in different regions of the heart are described. Then the cellular mechanisms promoting arrhythmias in congenital or acquired conditions of ion channel function (electrical remodeling) are discussed. The focus is on human-relevant findings obtained with clinical, experimental, and computational studies, given that interspecies differences make the extrapolation from animal experiments to human clinical settings difficult. Deepening the understanding of the diverse pathophysiology of human cellular electrophysiology will help in developing novel and effective antiarrhythmic strategies for specific subpopulations and disease conditions.
Collapse
Affiliation(s)
- András Varró
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary.,MTA-SZTE Cardiovascular Pharmacology Research Group, Hungarian Academy of Sciences, Szeged, Hungary
| | - Jakub Tomek
- Department of Computer Science, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Norbert Nagy
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary.,MTA-SZTE Cardiovascular Pharmacology Research Group, Hungarian Academy of Sciences, Szeged, Hungary
| | - László Virág
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Elisa Passini
- Department of Computer Science, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Blanca Rodriguez
- Department of Computer Science, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - István Baczkó
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
| |
Collapse
|
17
|
Sutanto H, Heijman J. Beta-Adrenergic Receptor Stimulation Modulates the Cellular Proarrhythmic Effects of Chloroquine and Azithromycin. Front Physiol 2020; 11:587709. [PMID: 33192602 PMCID: PMC7642988 DOI: 10.3389/fphys.2020.587709] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Accepted: 09/29/2020] [Indexed: 12/11/2022] Open
Abstract
The antimalarial drug, chloroquine (CQ), and antimicrobial drug, azithromycin (AZM), have received significant attention during the COVID-19 pandemic. Both drugs can alter cardiac electrophysiology and have been associated with drug-induced arrhythmias. Meanwhile, sympathetic activation is commonly observed during systemic inflammation and oxidative stress (e.g., in SARS-CoV-2 infection) and may influence the electrophysiological effects of CQ and AZM. Here, we investigated the effect of beta-adrenergic stimulation on proarrhythmic properties of CQ and AZM using detailed in silico models of ventricular electrophysiology. Concentration-dependent alterations in ion-channel function were incorporated into the Heijman canine and O’Hara-Rudy human ventricular cardiomyocyte models. Single and combined drug effects on action-potential (AP) properties were analyzed using a population of 1,000 models accommodating inter-individual variability. Sympathetic stimulation was simulated by increasing pacing rate and experimentally validated isoproterenol (ISO)-induced changes in ion-channel function. In the canine ventricular model at 1 Hz pacing, therapeutic doses of CQ and AZM (5 and 20 μM, respectively) individually prolonged AP duration (APD) by 33 and 13%. Their combination produced synergistic APD prolongation (+161%) with incidence of proarrhythmic early afterdepolarizations in 53.5% of models. Increasing the pacing frequency to 2 Hz shortened APD and together with 1 μM ISO counteracted the drug-induced APD prolongation. No afterdepolarizations occurred following increased rate and simulated application of ISO. Similarly, CQ and AZM individually prolonged APD by 43 and 29% in the human ventricular cardiomyocyte model, while their combination prolonged APD by 76% without causing early afterdepolarizations. Consistently, 1 μM ISO at 2 Hz pacing counteracted the drug-induced APD prolongation. Increasing the ICa,L window current produced afterdepolarizations, which were exacerbated by ISO. In both models, reduced extracellular K+ reduced the repolarization reserve and increased drug effects. In conclusion, CQ- and AZM-induced proarrhythmia is promoted by conditions with reduced repolarization reserve. Sympathetic stimulation limits drug-induced APD prolongation, suggesting the potential importance of heart rate and autonomic status monitoring in particular conditions (e.g., COVID-19).
Collapse
Affiliation(s)
- Henry Sutanto
- Department of Cardiology, Cardiovascular Research Institute Maastricht (CARIM) School for Cardiovascular Diseases, Maastricht University, Maastricht, Netherlands
| | - Jordi Heijman
- Department of Cardiology, Cardiovascular Research Institute Maastricht (CARIM) School for Cardiovascular Diseases, Maastricht University, Maastricht, Netherlands
| |
Collapse
|
18
|
Zandstra T, Kiès P, Man SC, Maan A, Bootsma M, Vliegen H, Egorova A, Holman E, Schalij M, Jongbloed M. QT interval variability and heart rate turbulence are associated with clinical characteristics in congenital heart disease patients with a systemic right ventricle. J Cardiol 2020; 76:514-520. [PMID: 32665161 DOI: 10.1016/j.jjcc.2020.05.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 04/09/2020] [Accepted: 05/20/2020] [Indexed: 10/23/2022]
Abstract
BACKGROUND QT interval variability (QTV) and heart rate turbulence (HRT) are measures of cardiac autonomic function, which, when abnormal, are correlated with ventricular arrhythmias and worse clinical outcome. This study aims to evaluate QTV and HRT in patients with a systemic right ventricle (RV) and to assess correlations with clinical characteristics. METHODS In a retrospective cohort study, QTV and HRT were derived from 24-h Holter registrations of patients with a systemic RV and healthy controls. QTV and HRT were compared between groups. In patients, the association between QTV, HRT, and clinical characteristics was assessed. RESULTS Holter recordings from 40 patients (mean age 40 years, 16 females) and 37 healthy controls (mean age 42 years, 21 females) were analyzed. Groups were comparable in terms of age and sex. QTV was increased in patients compared with controls (p < 0.001), HRT did not differ significantly between the groups. Increased QTV and decreased HRT correlated with medication use, especially of diuretics, and with clinical events, particularly supraventricular arrhythmias. Increased QTV correlated with reduced systemic RV function. Decreased HRT was independently associated with a larger number of past clinical events (estimate -0.33, 95% CI -0.63 to -0.02, p = 0.037). QTV was higher in women in both patients and controls (p = 0.041 and p = 0.034, respectively). CONCLUSIONS QTV and HRT are associated with clinical factors and events in patients with a systemic RV. Further studies are mandatory to confirm their prognostic value.
Collapse
Affiliation(s)
- Tjitske Zandstra
- Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Philippine Kiès
- Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Sum-Che Man
- Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Arie Maan
- Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Marianne Bootsma
- Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Hubert Vliegen
- Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Anastasia Egorova
- Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Eduard Holman
- Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Martin Schalij
- Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Monique Jongbloed
- Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands; Department of Anatomy & Embryology, Leiden University Medical Center, Leiden, The Netherlands.
| |
Collapse
|
19
|
Jelinkova S, Vilotic A, Pribyl J, Aimond F, Salykin A, Acimovic I, Pesl M, Caluori G, Klimovic S, Urban T, Dobrovolna H, Soska V, Skladal P, Lacampagne A, Dvorak P, Meli AC, Rotrekl V. DMD Pluripotent Stem Cell Derived Cardiac Cells Recapitulate in vitro Human Cardiac Pathophysiology. Front Bioeng Biotechnol 2020; 8:535. [PMID: 32656189 PMCID: PMC7325914 DOI: 10.3389/fbioe.2020.00535] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2019] [Accepted: 05/04/2020] [Indexed: 12/17/2022] Open
Abstract
Duchenne muscular dystrophy (DMD) is a severe genetic disorder characterized by the lack of functional dystrophin. DMD is associated with progressive dilated cardiomyopathy, eventually leading to heart failure as the main cause of death in DMD patients. Although several molecular mechanisms leading to the DMD cardiomyocyte (DMD-CM) death were described, mostly in mouse model, no suitable human CM model was until recently available together with proper clarification of the DMD-CM phenotype and delay in cardiac symptoms manifestation. We obtained several independent dystrophin-deficient human pluripotent stem cell (hPSC) lines from DMD patients and CRISPR/Cas9-generated DMD gene mutation. We differentiated DMD-hPSC into cardiac cells (CC) creating a human DMD-CC disease model. We observed that mutation-carrying cells were less prone to differentiate into CCs. DMD-CCs demonstrated an enhanced cell death rate in time. Furthermore, ion channel expression was altered in terms of potassium (Kir2.1 overexpression) and calcium handling (dihydropyridine receptor overexpression). DMD-CCs exhibited increased time of calcium transient rising compared to aged-matched control, suggesting mishandling of calcium release. We observed mechanical impairment (hypocontractility), bradycardia, increased heart rate variability, and blunted β-adrenergic response connected with remodeling of β-adrenergic receptors expression in DMD-CCs. Overall, these results indicated that our DMD-CC models are functionally affected by dystrophin-deficiency associated and recapitulate functional defects and cardiac wasting observed in the disease. It offers an accurate tool to study human cardiomyopathy progression and test therapies in vitro.
Collapse
Affiliation(s)
- Sarka Jelinkova
- Department of Biology, Faculty of Medicine, Masaryk University, Brno, Czechia.,International Clinical Research Center ICRC, St. Anne's University Hospital Brno, Brno, Czechia
| | - Aleksandra Vilotic
- Department of Biology, Faculty of Medicine, Masaryk University, Brno, Czechia
| | - Jan Pribyl
- CEITEC, Masaryk University, Brno, Czechia
| | - Franck Aimond
- PhyMedExp, University of Montpellier, INSERM, CNRS, Montpellier, France
| | - Anton Salykin
- Department of Biology, Faculty of Medicine, Masaryk University, Brno, Czechia
| | - Ivana Acimovic
- Department of Biology, Faculty of Medicine, Masaryk University, Brno, Czechia
| | - Martin Pesl
- Department of Biology, Faculty of Medicine, Masaryk University, Brno, Czechia.,International Clinical Research Center ICRC, St. Anne's University Hospital Brno, Brno, Czechia.,First Department of Internal Medicine-Cardioangiology, Faculty of Medicine, Masaryk University, Brno, Czechia
| | - Guido Caluori
- International Clinical Research Center ICRC, St. Anne's University Hospital Brno, Brno, Czechia.,First Department of Internal Medicine-Cardioangiology, Faculty of Medicine, Masaryk University, Brno, Czechia
| | - Simon Klimovic
- Department of Biochemistry, Faculty of Science, Masaryk University, Brno, Czechia
| | - Tomas Urban
- Department of Biology, Faculty of Medicine, Masaryk University, Brno, Czechia
| | - Hana Dobrovolna
- Department of Clinical Biochemistry, St. Anne's University Hospital of Brno, Brno, Czechia
| | - Vladimir Soska
- Department of Clinical Biochemistry, St. Anne's University Hospital of Brno, Brno, Czechia.,Second Clinic of Internal Medicine, Masaryk University of Brno, Brno, Czechia
| | - Petr Skladal
- First Department of Internal Medicine-Cardioangiology, Faculty of Medicine, Masaryk University, Brno, Czechia.,Department of Biochemistry, Faculty of Science, Masaryk University, Brno, Czechia
| | - Alain Lacampagne
- PhyMedExp, University of Montpellier, INSERM, CNRS, Montpellier, France
| | - Petr Dvorak
- Department of Biology, Faculty of Medicine, Masaryk University, Brno, Czechia.,International Clinical Research Center ICRC, St. Anne's University Hospital Brno, Brno, Czechia
| | - Albano C Meli
- Department of Biology, Faculty of Medicine, Masaryk University, Brno, Czechia.,PhyMedExp, University of Montpellier, INSERM, CNRS, Montpellier, France
| | - Vladimir Rotrekl
- Department of Biology, Faculty of Medicine, Masaryk University, Brno, Czechia.,International Clinical Research Center ICRC, St. Anne's University Hospital Brno, Brno, Czechia
| |
Collapse
|
20
|
Shah D, Prajapati C, Penttinen K, Cherian RM, Koivumäki JT, Alexanova A, Hyttinen J, Aalto-Setälä K. hiPSC-Derived Cardiomyocyte Model of LQT2 Syndrome Derived from Asymptomatic and Symptomatic Mutation Carriers Reproduces Clinical Differences in Aggregates but Not in Single Cells. Cells 2020; 9:cells9051153. [PMID: 32392813 PMCID: PMC7290503 DOI: 10.3390/cells9051153] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 04/29/2020] [Accepted: 05/02/2020] [Indexed: 12/13/2022] Open
Abstract
Mutations in the HERG gene encoding the potassium ion channel HERG, represent one of the most frequent causes of long QT syndrome type-2 (LQT2). The same genetic mutation frequently presents different clinical phenotypes in the family. Our study aimed to model LQT2 and study functional differences between the mutation carriers of variable clinical phenotypes. We derived human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM) from asymptomatic and symptomatic HERG mutation carriers from the same family. When comparing asymptomatic and symptomatic single LQT2 hiPSC-CMs, results from allelic imbalance, potassium current density, and arrhythmicity on adrenaline exposure were similar, but a difference in Ca2+ transients was observed. The major differences were, however, observed at aggregate level with increased susceptibility to arrhythmias on exposure to adrenaline or potassium channel blockers on CM aggregates derived from the symptomatic individual. The effect of this mutation was modeled in-silico which indicated the reactivation of an inward calcium current as one of the main causes of arrhythmia. Our in-vitro hiPSC-CM model recapitulated major phenotype characteristics observed in LQT2 mutation carriers and strong phenotype differences between LQT2 asymptomatic vs. symptomatic were revealed at CM-aggregate level.
Collapse
Affiliation(s)
- Disheet Shah
- Faculty of Medicine and Health Technology and BioMediTech Institute, Tampere University, 33520 Tampere, Finland; (C.P.); (K.P.); (R.M.C.); (J.T.K.); (A.A.); (J.H.); (K.A.-S.)
- Correspondence:
| | - Chandra Prajapati
- Faculty of Medicine and Health Technology and BioMediTech Institute, Tampere University, 33520 Tampere, Finland; (C.P.); (K.P.); (R.M.C.); (J.T.K.); (A.A.); (J.H.); (K.A.-S.)
| | - Kirsi Penttinen
- Faculty of Medicine and Health Technology and BioMediTech Institute, Tampere University, 33520 Tampere, Finland; (C.P.); (K.P.); (R.M.C.); (J.T.K.); (A.A.); (J.H.); (K.A.-S.)
| | - Reeja Maria Cherian
- Faculty of Medicine and Health Technology and BioMediTech Institute, Tampere University, 33520 Tampere, Finland; (C.P.); (K.P.); (R.M.C.); (J.T.K.); (A.A.); (J.H.); (K.A.-S.)
| | - Jussi T. Koivumäki
- Faculty of Medicine and Health Technology and BioMediTech Institute, Tampere University, 33520 Tampere, Finland; (C.P.); (K.P.); (R.M.C.); (J.T.K.); (A.A.); (J.H.); (K.A.-S.)
| | - Anna Alexanova
- Faculty of Medicine and Health Technology and BioMediTech Institute, Tampere University, 33520 Tampere, Finland; (C.P.); (K.P.); (R.M.C.); (J.T.K.); (A.A.); (J.H.); (K.A.-S.)
| | - Jari Hyttinen
- Faculty of Medicine and Health Technology and BioMediTech Institute, Tampere University, 33520 Tampere, Finland; (C.P.); (K.P.); (R.M.C.); (J.T.K.); (A.A.); (J.H.); (K.A.-S.)
| | - Katriina Aalto-Setälä
- Faculty of Medicine and Health Technology and BioMediTech Institute, Tampere University, 33520 Tampere, Finland; (C.P.); (K.P.); (R.M.C.); (J.T.K.); (A.A.); (J.H.); (K.A.-S.)
- Heart Hospital, Tampere University Hospital, 33520 Tampere, Finland
| |
Collapse
|
21
|
Hegyi B, Chen-Izu Y, Izu LT, Rajamani S, Belardinelli L, Bers DM, Bányász T. Balance Between Rapid Delayed Rectifier K + Current and Late Na + Current on Ventricular Repolarization: An Effective Antiarrhythmic Target? Circ Arrhythm Electrophysiol 2020; 13:e008130. [PMID: 32202931 PMCID: PMC7331791 DOI: 10.1161/circep.119.008130] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
BACKGROUND Rapid delayed rectifier K+ current (IKr) and late Na+ current (INaL) significantly shape the cardiac action potential (AP). Changes in their magnitudes can cause either long or short QT syndromes associated with malignant ventricular arrhythmias and sudden cardiac death. METHODS Physiological self AP-clamp was used to measure INaL and IKr during the AP in rabbit and porcine ventricular cardiomyocytes to test our hypothesis that the balance between IKr and INaL affects repolarization stability in health and disease conditions. RESULTS We found comparable amount of net charge carried by IKr and INaL during the physiological AP, suggesting that outward K+ current via IKr and inward Na+ current via INaL are in balance during physiological repolarization. Remarkably, IKr and INaL integrals in each control myocyte were highly correlated in both healthy rabbit and pig myocytes, despite high overall cell-to-cell variability. This close correlation was lost in heart failure myocytes from both species. Pretreatment with E-4031 to block IKr (mimicking long QT syndrome 2) or with sea anemone toxin II to impair Na+ channel inactivation (mimicking long QT syndrome 3) prolonged AP duration (APD); however, using GS-967 to inhibit INaL sufficiently restored APD to control in both cases. Importantly, INaL inhibition significantly reduced the beat-to-beat and short-term variabilities of APD. Moreover, INaL inhibition also restored APD and repolarization stability in heart failure. Conversely, pretreatment with GS-967 shortened APD (mimicking short QT syndrome), and E-4031 reverted APD shortening. Furthermore, the amplitude of AP alternans occurring at high pacing frequency was decreased by INaL inhibition, increased by IKr inhibition, and restored by combined INaL and IKr inhibitions. CONCLUSIONS Our data demonstrate that IKr and INaL are counterbalancing currents during the physiological ventricular AP and their integrals covary in individual myocytes. Targeting these ionic currents to normalize their balance may have significant therapeutic potential in heart diseases with repolarization abnormalities. Visual Overview: A visual overview is available for this article.
Collapse
Affiliation(s)
- Bence Hegyi
- Department of Pharmacology, University of California, Davis
| | - Ye Chen-Izu
- Department of Pharmacology, University of California, Davis
- Department of Biomedical Engineering, University of California, Davis
- Department of Internal Medicine/Cardiology, University of California, Davis
| | | | - Sridharan Rajamani
- Amgen, Inc., South San Francisco, University of Debrecen, Debrecen, Hungary
| | - Luiz Belardinelli
- InCarda Therapeutics, Inc., Newark, CA, University of Debrecen, Debrecen, Hungary
| | - Donald M. Bers
- Department of Pharmacology, University of California, Davis
| | - Tamás Bányász
- Department of Pharmacology, University of California, Davis
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| |
Collapse
|
22
|
Dries E, Amoni M, Vandenberk B, Johnson DM, Gilbert G, Nagaraju CK, Puertas RD, Abdesselem M, Santiago DJ, Roderick HL, Claus P, Willems R, Sipido KR. Altered adrenergic response in myocytes bordering a chronic myocardial infarction underlies in vivo triggered activity and repolarization instability. J Physiol 2020; 598:2875-2895. [PMID: 31900932 PMCID: PMC7496440 DOI: 10.1113/jp278839] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Accepted: 01/01/2020] [Indexed: 01/24/2023] Open
Abstract
Key points Ventricular arrhythmias are a major complication after myocardial infarction (MI), associated with sympathetic activation. The structurally heterogeneous peri‐infarct zone is a known substrate, but the functional role of the myocytes is less well known. Recordings of monophasic action potentials in vivo reveal that the peri‐infarct zone is a source of delayed afterdepolarizations (DADs) and has a high beat‐to‐beat variability of repolarization (BVR) during adrenergic stimulation (isoproterenol, ISO). Myocytes isolated from the peri‐infarct region have more DADs and spontaneous action potentials, with spontaneous Ca2+ release, under ISO. These myocytes also have reduced repolarization reserve and increased BVR. Other properties of post‐MI remodelling are present in both peri‐infarct and remote myocytes. These data highlight the importance of altered myocyte adrenergic responses in the peri‐infarct region as source and substrate of post‐MI arrhythmias.
Abstract Ventricular arrhythmias are a major early complication after myocardial infarction (MI). The heterogeneous peri‐infarct zone forms a substrate for re‐entry while arrhythmia initiation is often associated with sympathetic activation. We studied the mechanisms triggering these post‐MI arrhythmias in vivo and their relation to regional myocyte remodelling. In pigs with chronic MI (6 weeks), in vivo monophasic action potentials were simultaneously recorded in the peri‐infarct and remote regions during adrenergic stimulation with isoproterenol (isoprenaline; ISO). Sham animals served as controls. During infusion of ISO in vivo, the incidence of delayed afterdepolarizations (DADs) and beat‐to‐beat variability of repolarization (BVR) was higher in the peri‐infarct than in the remote region. Myocytes isolated from the peri‐infarct region, in comparison to myocytes from the remote region, had more DADs, associated with spontaneous Ca2+ release, and a higher incidence of spontaneous action potentials (APs) when exposed to ISO (9.99 ± 4.2 vs. 0.16 ± 0.05 APs/min, p = 0.004); these were suppressed by CaMKII inhibition. Peri‐infarct myocytes also had reduced repolarization reserve and increased BVR (26 ± 10 ms vs. 9 ± 7 ms, P < 0.001), correlating with DAD activity. In contrast to these regional distinctions under ISO, alterations in Ca2+ handling at baseline and myocyte hypertrophy were present throughout the left ventricle (LV). Expression of some of the related genes was, however, different between the regions. In conclusion, altered myocyte adrenergic responses in the peri‐infarct but not the remote region provide a source of triggered activity in vivo and of repolarization instability amplifying the substrate for re‐entry. These findings stimulate further exploration of region‐specific therapies targeting myocytes and autonomic modulation. Ventricular arrhythmias are a major complication after myocardial infarction (MI), associated with sympathetic activation. The structurally heterogeneous peri‐infarct zone is a known substrate, but the functional role of the myocytes is less well known. Recordings of monophasic action potentials in vivo reveal that the peri‐infarct zone is a source of delayed afterdepolarizations (DADs) and has a high beat‐to‐beat variability of repolarization (BVR) during adrenergic stimulation (isoproterenol, ISO). Myocytes isolated from the peri‐infarct region have more DADs and spontaneous action potentials, with spontaneous Ca2+ release, under ISO. These myocytes also have reduced repolarization reserve and increased BVR. Other properties of post‐MI remodelling are present in both peri‐infarct and remote myocytes. These data highlight the importance of altered myocyte adrenergic responses in the peri‐infarct region as source and substrate of post‐MI arrhythmias.
Collapse
Affiliation(s)
- Eef Dries
- Experimental Cardiology, University of Leuven, Herestraat 49 box 911, Leuven, Belgium
| | - Matthew Amoni
- Experimental Cardiology, University of Leuven, Herestraat 49 box 911, Leuven, Belgium
| | - Bert Vandenberk
- Experimental Cardiology, University of Leuven, Herestraat 49 box 911, Leuven, Belgium
| | - Daniel M Johnson
- Experimental Cardiology, University of Leuven, Herestraat 49 box 911, Leuven, Belgium.,Institute of Cardiovascular Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Guillaume Gilbert
- Experimental Cardiology, University of Leuven, Herestraat 49 box 911, Leuven, Belgium
| | - Chandan K Nagaraju
- Experimental Cardiology, University of Leuven, Herestraat 49 box 911, Leuven, Belgium
| | - Rosa Doñate Puertas
- Experimental Cardiology, University of Leuven, Herestraat 49 box 911, Leuven, Belgium
| | - Mouna Abdesselem
- Experimental Cardiology, University of Leuven, Herestraat 49 box 911, Leuven, Belgium
| | - Demetrio J Santiago
- Experimental Cardiology, University of Leuven, Herestraat 49 box 911, Leuven, Belgium.,Laboratory of Molecular Cardiology, Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), C. Melchor Fernández Almagro 3, 28029, Madrid, Spain
| | - H Llewelyn Roderick
- Experimental Cardiology, University of Leuven, Herestraat 49 box 911, Leuven, Belgium
| | - Piet Claus
- Experimental Cardiology, University of Leuven, Herestraat 49 box 911, Leuven, Belgium
| | - Rik Willems
- Experimental Cardiology, University of Leuven, Herestraat 49 box 911, Leuven, Belgium
| | - Karin R Sipido
- Experimental Cardiology, University of Leuven, Herestraat 49 box 911, Leuven, Belgium
| |
Collapse
|
23
|
Duijvenboden SV, Porter B, Pueyo E, Sampedro-Puente DA, Fernandez-Bes J, Sidhu B, Gould J, Orini M, Bishop MJ, Hanson B, Lambiase P, Razavi R, Rinaldi CA, Gill JS, Taggart P. Complex Interaction Between Low-Frequency APD Oscillations and Beat-to-Beat APD Variability in Humans Is Governed by the Sympathetic Nervous System. Front Physiol 2020; 10:1582. [PMID: 32038279 PMCID: PMC6987475 DOI: 10.3389/fphys.2019.01582] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Accepted: 12/17/2019] [Indexed: 02/03/2023] Open
Abstract
BACKGROUND Recent clinical, experimental and modeling studies link oscillations of ventricular repolarization in the low frequency (LF) (approx. 0.1 Hz) to arrhythmogenesis. Sympathetic provocation has been shown to enhance both LF oscillations of action potential duration (APD) and beat-to-beat variability (BVR) in humans. We hypothesized that beta-adrenergic blockade would reduce LF oscillations of APD and BVR of APD in humans and that the two processes might be linked. METHODS AND RESULTS Twelve patients with normal ventricles were studied during routine electrophysiological procedures. Activation-recovery intervals (ARI) as a conventional surrogate for APD were recorded from 10 left and 10 right ventricular endocardial sites before and after acute beta-adrenergic adrenergic blockade. Cycle length was maintained constant with right ventricular pacing. Oscillatory behavior of ARI was quantified by spectral analysis and BVR as the short-term variability. Beta-adrenergic blockade reduced LF ARI oscillations (8.6 ± 4.5 ms2 vs. 5.5 ± 3.5 ms2, p = 0.027). A significant correlation was present between the initial control values and reduction seen following beta-adrenergic blockade in LF ARI (r s = 0.62, p = 0.037) such that when initial values are high the effect is greater. A similar relationship was also seen in the beat-to beat variability of ARI (r s = 0.74, p = 0.008). There was a significant correlation between the beta-adrenergic blockade induced reduction in LF power of ARI and the witnessed reduction of beat-to-beat variability of ARI (r s = 0.74, p = 0.01). These clinical results accord with recent computational modeling studies which provide mechanistic insight into the interactions of LF oscillations and beat-to-beat variability of APD at the cellular level. CONCLUSION Beta-adrenergic blockade reduces LF oscillatory behavior of APD (ARI) in humans in vivo. Our results support the importance of LF oscillations in modulating the response of BVR to beta-adrenergic blockers, suggesting that LF oscillations may play role in modulating beta-adrenergic mechanisms underlying BVR.
Collapse
Affiliation(s)
| | - Bradley Porter
- School of Imaging Sciences and Biomedical Engineering, King’s College London, London, United Kingdom
| | - Esther Pueyo
- BSICOS Group, I3A, IIS Aragón, University of Zaragoza, Zaragoza, Spain
- CIBER-BBN, Madrid, Spain
| | | | | | - Baldeep Sidhu
- School of Imaging Sciences and Biomedical Engineering, King’s College London, London, United Kingdom
| | - Justin Gould
- School of Imaging Sciences and Biomedical Engineering, King’s College London, London, United Kingdom
| | - Michele Orini
- Department of Clinical Pharmacology, Queen Mary University of London, London, United Kingdom
| | - Martin J. Bishop
- School of Imaging Sciences and Biomedical Engineering, King’s College London, London, United Kingdom
| | - Ben Hanson
- Department of Mechanical Engineering, University College London, London, United Kingdom
| | - Pier Lambiase
- Institute of Cardiovascular Science, University College London, London, United Kingdom
| | - Reza Razavi
- School of Imaging Sciences and Biomedical Engineering, King’s College London, London, United Kingdom
| | | | | | - Peter Taggart
- Institute of Cardiovascular Science, University College London, London, United Kingdom
| |
Collapse
|
24
|
Sampedro-Puente DA, Fernandez-Bes J, Szentandrássy N, Nánási P, Taggart P, Pueyo E. Time Course of Low-Frequency Oscillatory Behavior in Human Ventricular Repolarization Following Enhanced Sympathetic Activity and Relation to Arrhythmogenesis. Front Physiol 2020; 10:1547. [PMID: 32009971 PMCID: PMC6971219 DOI: 10.3389/fphys.2019.01547] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Accepted: 12/09/2019] [Indexed: 11/21/2022] Open
Abstract
Background and Objectives: Recent studies in humans and dogs have shown that ventricular repolarization exhibits a low-frequency (LF) oscillatory pattern following enhanced sympathetic activity, which has been related to arrhythmic risk. The appearance of LF oscillations in ventricular repolarization is, however, not immediate, but it may take up to some minutes. This study seeks to characterize the time course of the action potential (AP) duration (APD) oscillatory behavior in response to sympathetic provocations, unveil its underlying mechanisms and establish a potential link to arrhythmogenesis under disease conditions. Materials and Methods: A representative set of human ventricular computational models coupling cellular electrophysiology, calcium dynamics, β-adrenergic signaling, and mechanics was built. Sympathetic provocation was modeled via phasic changes in β-adrenergic stimulation (β-AS) and mechanical stretch at Mayer wave frequencies within the 0.03–0.15 Hz band. Results: Our results show that there are large inter-individual differences in the time lapse for the development of LF oscillations in APD following sympathetic provocation, with some cells requiring just a few seconds and other cells needing more than 3 min. Whereas, the oscillatory response to phasic mechanical stretch is almost immediate, the response to β-AS is much more prolonged, in line with experimentally reported evidences, thus being this component the one driving the slow development of APD oscillations following enhanced sympathetic activity. If β-adrenoceptors are priorly stimulated, the time for APD oscillations to become apparent is remarkably reduced, with the oscillation time lapse being an exponential function of the pre-stimulation level. The major mechanism underlying the delay in APD oscillations appearance is related to the slow IKs phosphorylation kinetics, with its relevance being modulated by the IKs conductance of each individual cell. Cells presenting short oscillation time lapses are commonly associated with large APD oscillation magnitudes, which facilitate the occurrence of pro-arrhythmic events under disease conditions involving calcium overload and reduced repolarization reserve. Conclusions: The time course of LF oscillatory behavior of APD in response to increased sympathetic activity presents high inter-individual variability, which is associated with different expression and PKA phosphorylation kinetics of the IKs current. Short time lapses in the development of APD oscillations are associated with large oscillatory magnitudes and pro-arrhythmic risk under disease conditions.
Collapse
Affiliation(s)
| | | | - Norbert Szentandrássy
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.,Department of Dental Physiology and Pharmacology, Faculty of Dentistry, University of Debrecen, Debrecen, Hungary
| | - Péter Nánási
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.,Department of Dental Physiology and Pharmacology, Faculty of Dentistry, University of Debrecen, Debrecen, Hungary
| | - Peter Taggart
- Department of Cardiovascular Sciences, University College London, London, United Kingdom
| | - Esther Pueyo
- BSICOS Group, I3A, IIS Aragón, University of Zaragoza, Zaragoza, Spain.,Center for Biomedical Research in the Network in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Zaragoza, Spain
| |
Collapse
|
25
|
Nánási PP, Szabó Z, Kistamás K, Horváth B, Virág L, Jost N, Bányász T, Almássy J, Varró A. Implication of frequency-dependent protocols in antiarrhythmic and proarrhythmic drug testing. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2019; 157:76-83. [PMID: 31726065 DOI: 10.1016/j.pbiomolbio.2019.11.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 10/30/2019] [Accepted: 11/01/2019] [Indexed: 01/20/2023]
Abstract
It has long been known that the electrophysiological effects of many cardioactive drugs strongly depend on the rate dependent frequency. This was recognized first for class I antiarrhythmic agents: their Vmax suppressive effect was attenuated at long cycle lengths. Later many Ca2+ channel blockers were also found to follow such kinetics. The explanation was provided by the modulated and the guarded receptor theories. Regarding the duration of cardiac action potentials (APD) an opposite frequency-dependence was observed, i.e. the drug-induced changes in APD were proportional with the cycle length of stimulation, therefore it was referred as "reverse rate-dependency". The beat-to-beat, or short term variability of APD (SV) has been recognized as an important proarrhythmic mechanism, its magnitude can be used as an arrhythmia predictor. SV is modulated by several cardioactive agents, however, these drugs modify also APD itself. In order to clear the drug-specific effects on SV from the concomitant unspecific APD-change related ones, the term of "relative variability" was introduced. Relative variability is increased by ion channel blockers that decrease the negative feedback control of APD (i.e. blockers of ICa, IKr and IKs) and also by elevation of cytosolic Ca2+. Cardiac arrhythmias are also often categorized according to the characteristic heart rate (tachy- and bradyarrhythmias). Tachycardia is proarrhythmic primarily due to the concomitant Ca2+ overload causing delayed afterdepolarizations. Early afterdepolarizations (EADs) are complications of the bradycardic heart. What is common in the reverse rate-dependent nature of drug action on APD, increased SV and EAD incidence associated with bradycardia.
Collapse
Affiliation(s)
- Péter P Nánási
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary; Department of Dental Physiology, Faculty of Dentistry, University of Debrecen, Debrecen, Hungary
| | - Zoltán Szabó
- Department of Emergency Medicine, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Kornél Kistamás
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Balázs Horváth
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - László Virág
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary; Department of Pharmacology and Pharmacotherapy, Interdisciplinary Excellence Centre, University of Szeged, Szeged, Hungary
| | - Norbert Jost
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary; Department of Pharmacology and Pharmacotherapy, Interdisciplinary Excellence Centre, University of Szeged, Szeged, Hungary; MTA-SZTE Research Group for Cardiovascular Pharmacology, Szeged, Hungary
| | - Tamás Bányász
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - János Almássy
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - András Varró
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary; Department of Pharmacology and Pharmacotherapy, Interdisciplinary Excellence Centre, University of Szeged, Szeged, Hungary; MTA-SZTE Research Group for Cardiovascular Pharmacology, Szeged, Hungary.
| |
Collapse
|
26
|
Sprenkeler DJ, Beekman JDM, Bossu A, Dunnink A, Vos MA. Pro-Arrhythmic Ventricular Remodeling Is Associated With Increased Respiratory and Low-Frequency Oscillations of Monophasic Action Potential Duration in the Chronic Atrioventricular Block Dog Model. Front Physiol 2019; 10:1095. [PMID: 31507455 PMCID: PMC6716537 DOI: 10.3389/fphys.2019.01095] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Accepted: 08/08/2019] [Indexed: 11/13/2022] Open
Abstract
In addition to beat-to-beat fluctuations, action potential duration (APD) oscillates at (1) a respiratory frequency and (2) a low frequency (LF) (<0.1 Hz), probably caused by bursts of sympathetic nervous system discharge. This study investigates whether ventricular remodeling in the chronic AV block (CAVB) dog alters these oscillations of APD and whether this has consequences for arrhythmogenesis. We performed a retrospective analysis of 39 dog experiments in sinus rhythm (SR), acute AV block (AAVB), and after 2 weeks of chronic AV block. Spectral analysis of left ventricular monophasic action potential duration (LV MAPD) was done to quantify respiratory frequency (RF) power and LF power. Dofetilide (0.025 mg/kg in 5 min) was infused to test for inducibility of Torsade de Pointes (TdP) arrhythmias. RF power was significantly increased at CAVB compared to AAVB and SR (log[RF] of -1.13 ± 1.62 at CAVB vs. log[RF] of -2.82 ± 1.24 and -3.29 ± 1.29 at SR and AAVB, respectively, p < 0.001). LF power was already significantly increased at AAVB and increased even further at CAVB (-3.91 ± 0.70 at SR vs. -2.52 ± 0.85 at AAVB and -1.14 ± 1.62 at CAVB, p < 0.001). In addition, LF power was significantly larger in inducible CAVB dogs (log[LF] -0.6 ± 1.54 in inducible dogs vs. -2.56 ± 0.43 in non-inducible dogs, p < 0.001). In conclusion, ventricular remodeling in the CAVB dog results in augmentation of respiratory and low-frequency (LF) oscillations of LV MAPD. Furthermore, TdP-inducible CAVB dogs show increased LF power.
Collapse
Affiliation(s)
- David Jaap Sprenkeler
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Utrecht, Netherlands
| | - Jet D M Beekman
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Utrecht, Netherlands
| | - Alexandre Bossu
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Utrecht, Netherlands
| | - Albert Dunnink
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Utrecht, Netherlands
| | - Marc A Vos
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Utrecht, Netherlands
| |
Collapse
|
27
|
Sampedro-Puente DA, Fernandez-Bes J, Porter B, van Duijvenboden S, Taggart P, Pueyo E. Mechanisms Underlying Interactions Between Low-Frequency Oscillations and Beat-to-Beat Variability of Celullar Ventricular Repolarization in Response to Sympathetic Stimulation: Implications for Arrhythmogenesis. Front Physiol 2019; 10:916. [PMID: 31427979 PMCID: PMC6687852 DOI: 10.3389/fphys.2019.00916] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2018] [Accepted: 07/04/2019] [Indexed: 12/12/2022] Open
Abstract
Background and Objectives: Enhanced beat-to-beat variability of ventricular repolarization (BVR) has been linked to arrhythmias and sudden cardiac death. Recent experimental studies on human left ventricular epicardial electrograms have shown that BVR closely interacts with low-frequency (LF) oscillations of activation recovery interval during sympathetic provocation. In this work human ventricular computational cell models are developed to reproduce the experimentally observed interactions between BVR and its LF oscillations, to assess underlying mechanisms and to establish a relationship with arrhythmic risk. Materials and Methods: A set of human ventricular action potential (AP) models covering a range of experimental electrophysiological characteristics was constructed. These models incorporated stochasticity in major ionic currents as well as descriptions of β-adrenergic stimulation and mechanical effects to investigate the AP response to enhanced sympathetic activity. Statistical methods based on Automatic Relevance Determination and Canonical Correlation Analysis were developed to unravel individual and common factors contributing to BVR and LF patterning of APD in response to sympathetic provocation. Results: Simulated results reproduced experimental evidences on the interactions between BVR and LF oscillations of AP duration (APD), with replication of the high inter-individual variability observed in both phenomena. ICaL, IKr and IK1 currents were identified as common ionic modulators of the inter-individual differences in BVR and LF oscillatory behavior and were shown to be crucial in determining susceptibility to arrhythmogenic events. Conclusions: The calibrated family of human ventricular cell models proposed in this study allows reproducing experimentally reported interactions between BVR and LF oscillations of APD. Ionic factors involving ICaL, IKr and IK1 currents are found to underlie correlated increments in both phenomena in response to sympathetic provocation. A link to arrhythmogenesis is established for concomitantly elevated levels of BVR and its LF oscillations.
Collapse
Affiliation(s)
| | | | - Bradley Porter
- Department of Imaging Sciences and Biomedical Engineering, Kings College London, London, United Kingdom
| | | | - Peter Taggart
- Department of Cardiovascular Sciences, University College London, London, United Kingdom
| | - Esther Pueyo
- BSICOS Group, I3A, IIS Aragón, University of Zaragoza, Zaragoza, Spain.,CIBER-BBN, Madrid, Spain
| |
Collapse
|
28
|
Modeling of LMNA-Related Dilated Cardiomyopathy Using Human Induced Pluripotent Stem Cells. Cells 2019; 8:cells8060594. [PMID: 31208058 PMCID: PMC6627421 DOI: 10.3390/cells8060594] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 06/12/2019] [Accepted: 06/13/2019] [Indexed: 12/31/2022] Open
Abstract
Dilated cardiomyopathy (DCM) is one of the leading causes of heart failure and heart transplantation. A portion of familial DCM is due to mutations in the LMNA gene encoding the nuclear lamina proteins lamin A and C and without adequate treatment these patients have a poor prognosis. To get better insights into pathobiology behind this disease, we focused on modeling LMNA-related DCM using human induced pluripotent stem cell derived cardiomyocytes (hiPSC-CM). Primary skin fibroblasts from DCM patients carrying the most prevalent Finnish founder mutation (p.S143P) in LMNA were reprogrammed into hiPSCs and further differentiated into cardiomyocytes (CMs). The cellular structure, functionality as well as gene and protein expression were assessed in detail. While mutant hiPSC-CMs presented virtually normal sarcomere structure under normoxia, dramatic sarcomere damage and an increased sensitivity to cellular stress was observed after hypoxia. A detailed electrophysiological evaluation revealed bradyarrhythmia and increased occurrence of arrhythmias in mutant hiPSC-CMs on β-adrenergic stimulation. Mutant hiPSC-CMs also showed increased sensitivity to hypoxia on microelectrode array and altered Ca2+ dynamics. Taken together, p.S143P hiPSC-CM model mimics hallmarks of LMNA-related DCM and provides a useful tool to study the underlying cellular mechanisms of accelerated cardiac degeneration in this disease.
Collapse
|
29
|
Sampedro-Puente DA, Fernandez-Bes J, Virag L, Varro A, Pueyo E. Data-Driven Identification of Stochastic Model Parameters and State Variables: Application to the Study of Cardiac Beat-to-Beat Variability. IEEE J Biomed Health Inform 2019; 24:693-704. [PMID: 31180875 DOI: 10.1109/jbhi.2019.2921881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
OBJECTIVE Enhanced spatiotemporal ventricular repolarization variability has been associated with ventricular arrhythmias and sudden cardiac death, but the involved mechanisms remain elusive. In this paper, a methodology for estimation of parameters and state variables of stochastic human ventricular cell models from input voltage data is proposed for investigation of repolarization variability. METHODS The proposed methodology formulates state-space representations based on developed stochastic cell models and uses the unscented Kalman filter to perform joint parameter and state estimation. Evaluation over synthetic and experimental data is presented. RESULTS Results on synthetically generated data show the ability of the methodology to: first, filter out measurement noise from action potential (AP) traces; second, identify model parameters and state variables from each of those individual AP traces, thus allowing robust characterization of cell-to-cell variability; and, third, replicate statistical population's distributions of input AP-based markers, including dynamic markers quantifying beat-to-beat variability. Application onto experimental data demonstrates the ability of the methodology to match input AP traces while concomitantly inferring the characteristics of underlying stochastic cell models. CONCLUSION A novel methodology is presented for estimation of parameters and hidden variables of stochastic cardiac computational models, with the advantage of providing a one-to-one match between each individual AP trace and a corresponding set of model characteristics. SIGNIFICANCE The proposed methodology can greatly help in the characterization of temporal (beat-to-beat) and spatial (cell-to-cell) variability in human ventricular repolarization and in ascertaining the corresponding underlying mechanisms, particularly in scenarios with limited available experimental data.
Collapse
|
30
|
Porter B, Bishop MJ, Claridge S, Child N, Van Duijvenboden S, Bostock J, Sieniewicz BJ, Gould J, Sidhu B, Hanson B, Chen Z, Rinaldi CA, Taggart P, Gill JS. Left ventricular activation-recovery interval variability predicts spontaneous ventricular tachyarrhythmia in patients with heart failure. Heart Rhythm 2019; 16:702-709. [DOI: 10.1016/j.hrthm.2018.11.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Indexed: 01/01/2023]
|
31
|
Hegyi B, Morotti S, Liu C, Ginsburg KS, Bossuyt J, Belardinelli L, Izu LT, Chen-Izu Y, Bányász T, Grandi E, Bers DM. Enhanced Depolarization Drive in Failing Rabbit Ventricular Myocytes: Calcium-Dependent and β-Adrenergic Effects on Late Sodium, L-Type Calcium, and Sodium-Calcium Exchange Currents. Circ Arrhythm Electrophysiol 2019; 12:e007061. [PMID: 30879336 PMCID: PMC6720130 DOI: 10.1161/circep.118.007061] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
BACKGROUND Heart failure (HF) is characterized by electrophysiological remodeling resulting in increased risk of cardiac arrhythmias. Previous reports suggest that elevated inward ionic currents in HF promote action potential (AP) prolongation, increased short-term variability of AP repolarization, and delayed afterdepolarizations. However, the underlying changes in late Na+ current (INaL), L-type Ca2+ current, and NCX (Na+/Ca2+ exchanger) current are often measured in nonphysiological conditions (square-pulse voltage clamp, slow pacing rates, exogenous Ca2+ buffers). METHODS We measured the major inward currents and their Ca2+- and β-adrenergic dependence under physiological AP clamp in rabbit ventricular myocytes in chronic pressure/volume overload-induced HF (versus age-matched control). RESULTS AP duration and short-term variability of AP repolarization were increased in HF, and importantly, inhibition of INaL decreased both parameters to the control level. INaL was slightly increased in HF versus control even when intracellular Ca2+ was strongly buffered. But under physiological AP clamp with normal Ca2+ cycling, INaL was markedly upregulated in HF versus control (dependent largely on CaMKII [Ca2+/calmodulin-dependent protein kinase II] activity). β-Adrenergic stimulation (often elevated in HF) further enhanced INaL. L-type Ca2+ current was decreased in HF when Ca2+ was buffered, but CaMKII-mediated Ca2+-dependent facilitation upregulated physiological L-type Ca2+ current to the control level. Furthermore, L-type Ca2+ current response to β-adrenergic stimulation was significantly attenuated in HF. Inward NCX current was upregulated at phase 3 of AP in HF when assessed by combining experimental data and computational modeling. CONCLUSIONS Our results suggest that CaMKII-dependent upregulation of INaL in HF significantly contributes to AP prolongation and increased short-term variability of AP repolarization, which may lead to increased arrhythmia propensity, and is further exacerbated by adrenergic stress.
Collapse
Affiliation(s)
- Bence Hegyi
- Department of Pharmacology, University of California Davis, Davis
| | - Stefano Morotti
- Department of Pharmacology, University of California Davis, Davis
| | - Caroline Liu
- Department of Pharmacology, University of California Davis, Davis
| | | | - Julie Bossuyt
- Department of Pharmacology, University of California Davis, Davis
| | | | - Leighton T. Izu
- Department of Pharmacology, University of California Davis, Davis
| | - Ye Chen-Izu
- Department of Pharmacology, University of California Davis, Davis
- Department of Biomedical Engineering, University of California Davis, Davis
- Department of Internal Medicine/Cardiology, University of California Davis, Davis
| | - Tamás Bányász
- Department of Pharmacology, University of California Davis, Davis
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Eleonora Grandi
- Department of Pharmacology, University of California Davis, Davis
| | - Donald M. Bers
- Department of Pharmacology, University of California Davis, Davis
| |
Collapse
|
32
|
Charisopoulou D, Koulaouzidis G, Rydberg A, Michael HY. Exercise worsening of electromechanical disturbances: A predictor of arrhythmia in long QT syndrome. Clin Cardiol 2018; 42:235-240. [PMID: 30537240 PMCID: PMC6712344 DOI: 10.1002/clc.23132] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2018] [Revised: 10/29/2018] [Accepted: 12/06/2018] [Indexed: 01/06/2023] Open
Abstract
Background Electromechanical (EM) coupling heterogeneity is significant in long QT syndrome (LQTS), particularly in symptomatic patients; EM window (EMW) has been proposed as an indicator of interaction and a better predictor of arrhythmia than QTc. Hypothesis To investigate the dynamic response of EMW to exercise in LQTS and its predictive value of arrhythmia. Methods Forty‐seven LQTS carriers (45 ± 15 years, 20 with arrhythmic events), and 35 controls underwent exercise echocardiogram. EMW was measured as the time difference between aortic valve closure on Doppler and the end of QT interval on the superimposed electrocardiogram (ECG). Measurements were obtained at rest, peak exercise (PE) and 4 minutes into recovery. Results Patients did not differ in age, gender, heart rate, or left ventricular ejection fraction but had a negative resting EMW compared with controls (−42 ± 22 vs 17 ± 5 ms, P < 0.0001). EMW became more negative at PE (−89 ± 43 vs 16 ± 7 ms, P = 0.0001) and recovery (−65 ± 39 vs 16 ± 6 ms, P = 0.001) in patients, particularly the symptomatic, but remained unchanged in controls. PE EMW was a stronger predictor of arrhythmic events than QTc (AUC:0.765 vs 0.569, P < 0.001). B‐blockers did not affect EMW at rest but was less negative at PE (BB: −66 ± 21 vs no‐BB: −113 ± 25 ms, P < 0.001). LQT1 patients had worse PE EMW negativity than LQT2. Conclusion LQTS patients have significantly negative EMW, which worsens with exercise. These changes are more pronounced in patients with documented arrhythmic events and decrease with B‐blocker therapy. Thus, EMW assessment during exercise may help improve risk stratification and management of LQTS patients.
Collapse
Affiliation(s)
- Dafni Charisopoulou
- Institute of Public Health and Clinical Medicine, Umea University, Umea, Sweden.,Department of Paediatric Cardiology, Leeds Teaching Hospitals NHS Trust, Leeds, UK
| | - George Koulaouzidis
- Institute of Public Health and Clinical Medicine, Umea University, Umea, Sweden.,Department of Cardiology, Mid Yorkshire Hospitals NHS Trust, Wakefield, UK
| | - Annika Rydberg
- Department of Clinical Sciences, Paediatrics, Umea University, Umea, Sweden
| | - Henein Y Michael
- Institute of Public Health and Clinical Medicine, Umea University, Umea, Sweden.,Molecular and Clinical Sciences Research Institute, St George University London, London, UK.,Brunel University, Middlesex, UK
| |
Collapse
|
33
|
Johnson DM, Antoons G. Arrhythmogenic Mechanisms in Heart Failure: Linking β-Adrenergic Stimulation, Stretch, and Calcium. Front Physiol 2018; 9:1453. [PMID: 30374311 PMCID: PMC6196916 DOI: 10.3389/fphys.2018.01453] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Accepted: 09/25/2018] [Indexed: 12/22/2022] Open
Abstract
Heart failure (HF) is associated with elevated sympathetic tone and mechanical load. Both systems activate signaling transduction pathways that increase cardiac output, but eventually become part of the disease process itself leading to further worsening of cardiac function. These alterations can adversely contribute to electrical instability, at least in part due to the modulation of Ca2+ handling at the level of the single cardiac myocyte. The major aim of this review is to provide a definitive overview of the links and cross talk between β-adrenergic stimulation, mechanical load, and arrhythmogenesis in the setting of HF. We will initially review the role of Ca2+ in the induction of both early and delayed afterdepolarizations, the role that β-adrenergic stimulation plays in the initiation of these and how the propensity for these may be altered in HF. We will then go onto reviewing the current data with regards to the link between mechanical load and afterdepolarizations, the associated mechano-sensitivity of the ryanodine receptor and other stretch activated channels that may be associated with HF-associated arrhythmias. Furthermore, we will discuss how alterations in local Ca2+ microdomains during the remodeling process associated the HF may contribute to the increased disposition for β-adrenergic or stretch induced arrhythmogenic triggers. Finally, the potential mechanisms linking β-adrenergic stimulation and mechanical stretch will be clarified, with the aim of finding common modalities of arrhythmogenesis that could be targeted by novel therapeutic agents in the setting of HF.
Collapse
Affiliation(s)
- Daniel M Johnson
- Department of Cardiothoracic Surgery, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, Netherlands
| | - Gudrun Antoons
- Department of Physiology, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, Netherlands
| |
Collapse
|
34
|
Sprenkeler DJ, Bossu A, Beekman JDM, Schoenmakers M, Vos MA. An Augmented Negative Force-Frequency Relationship and Slowed Mechanical Restitution Are Associated With Increased Susceptibility to Drug-Induced Torsade de Pointes Arrhythmias in the Chronic Atrioventricular Block Dog. Front Physiol 2018; 9:1086. [PMID: 30135660 PMCID: PMC6092493 DOI: 10.3389/fphys.2018.01086] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 07/23/2018] [Indexed: 11/30/2022] Open
Abstract
Introduction: In the chronic AV-block (CAVB) dog model, structural, contractile, and electrical remodeling occur, which predispose the heart to dofetilide-induced Torsade de Pointes (TdP) arrhythmias. Previous studies found a relation between electrical remodeling and inducibility of TdP, while structural remodeling is not a prerequisite for arrhythmogenesis. In this study, we prospectively assessed the relation between in vivo markers of contractile remodeling and TdP inducibility. Methods: In 18 anesthetized dogs, the maximal first derivative of left ventricular pressure (LV dP/dtmax) was assessed at acute AV-block (AAVB) and after 2 weeks of chronic AV-block (CAVB2). Using pacing protocols, three markers of contractile remodeling, i.e., force-frequency relationship (FFR), mechanical restitution (MR), and post-extrasystolic potentiation (PESP) were determined. Infusion of dofetilide (0.025 mg/kg in 5 min) was used to test for TdP inducibility. Results: After infusion of dofetilide, 1/18 dogs and 12/18 were susceptible to TdP-arrhythmias at AAVB and CAVB2, respectively (p = 0.001). The inducible dogs at CAVB2 showed augmented contractility at a CL of 1200 ms (2354 ± 168 mmHg/s in inducible dogs versus 1091 ± 59 mmHg/s in non-inducible dogs, p < 0.001) with a negative FFR, while the non-inducible dogs retained their positive FFR. The time constant (TC) of the MR curve was significantly higher in the inducible dogs (158 ± 7 ms versus 97 ± 8 ms, p < 0.0001). Furthermore, a linear correlation was found between a weighted score of the number and severity of arrhythmias and contractile parameters, i.e., contractility at CL of 1200 ms (r = 0.73, p = 0.002), the slope of the FFR (r = -0.58, p = 0.01) and the TC of MR (r = 0.66, p = 0.003). Thus, more severe arrhythmias were seen in dogs with the most pronounced contractile remodeling. Conclusion: Contractile remodeling is concomitantly observed with susceptibility to dofetilide-induced TdP-arrhythmias. The inducible dogs show augmented contractile remodeling compared to non-inducible dogs, as seen by a negative FFR, higher maximal response of MR and PESP and slowed MR kinetics. These altered contractility parameters could reflect disrupted Ca2+ handling and Ca2+-overload, which predispose the heart to delayed- and early afterdepolarizations that could trigger TdP-arrhythmias.
Collapse
Affiliation(s)
- David J Sprenkeler
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Utrecht, Netherlands
| | - Alexandre Bossu
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Utrecht, Netherlands
| | - Jet D M Beekman
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Utrecht, Netherlands
| | - Marieke Schoenmakers
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Utrecht, Netherlands
| | - Marc A Vos
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Utrecht, Netherlands
| |
Collapse
|
35
|
Porter B, van Duijvenboden S, Bishop MJ, Orini M, Claridge S, Gould J, Sieniewicz BJ, Sidhu B, Razavi R, Rinaldi CA, Gill JS, Taggart P. Beat-to-Beat Variability of Ventricular Action Potential Duration Oscillates at Low Frequency During Sympathetic Provocation in Humans. Front Physiol 2018; 9:147. [PMID: 29670531 PMCID: PMC5893843 DOI: 10.3389/fphys.2018.00147] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Accepted: 02/13/2018] [Indexed: 01/22/2023] Open
Abstract
Background: The temporal pattern of ventricular repolarization is of critical importance in arrhythmogenesis. Enhanced beat-to-beat variability (BBV) of ventricular action potential duration (APD) is pro-arrhythmic and is increased during sympathetic provocation. Since sympathetic nerve activity characteristically exhibits burst patterning in the low frequency range, we hypothesized that physiologically enhanced sympathetic activity may not only increase BBV of left ventricular APD but also impose a low frequency oscillation which further increases repolarization instability in humans. Methods and Results: Heart failure patients with cardiac resynchronization therapy defibrillator devices (n = 11) had activation recovery intervals (ARI, surrogate for APD) recorded from left ventricular epicardial electrodes alongside simultaneous non-invasive blood pressure and respiratory recordings. Fixed cycle length was achieved by right ventricular pacing. Recordings took place during resting conditions and following an autonomic stimulus (Valsalva). The variability of ARI and the normalized variability of ARI showed significant increases post Valsalva when compared to control (p = 0.019 and p = 0.032, respectively). The oscillatory behavior was quantified by spectral analysis. Significant increases in low frequency (LF) power (p = 0.002) and normalized LF power (p = 0.019) of ARI were seen following Valsalva. The Valsalva did not induce changes in conduction variability nor the LF oscillatory behavior of conduction. However, increases in the LF power of ARI were accompanied by increases in the LF power of systolic blood pressure (SBP) and the rate of systolic pressure increase (dP/dtmax). Positive correlations were found between LF-SBP and LF-dP/dtmax (rs = 0.933, p < 0.001), LF-ARI and LF-SBP (rs = 0.681, p = 0.001) and between LF-ARI and LF-dP/dtmax (rs = 0.623, p = 0.004). There was a strong positive correlation between the variability of ARI and LF power of ARI (rs = 0.679, p < 0.001). Conclusions: In heart failure patients, physiological sympathetic provocation induced low frequency oscillation (~0.1 Hz) of left ventricular APD with a strong positive correlation between the LF power of APD and the BBV of APD. These findings may be of importance in mechanisms underlying stability/instability of repolarization and arrhythmogenesis in humans.
Collapse
Affiliation(s)
- Bradley Porter
- Department of Imaging Sciences and Biomedical Engineering, Kings College London, London, United Kingdom
| | | | - Martin J. Bishop
- Department of Imaging Sciences and Biomedical Engineering, Kings College London, London, United Kingdom
| | - Michele Orini
- Guy's and St Thomas' Hospital, London, United Kingdom
| | - Simon Claridge
- Department of Imaging Sciences and Biomedical Engineering, Kings College London, London, United Kingdom
| | - Justin Gould
- Department of Imaging Sciences and Biomedical Engineering, Kings College London, London, United Kingdom
| | - Benjamin J. Sieniewicz
- Department of Imaging Sciences and Biomedical Engineering, Kings College London, London, United Kingdom
| | - Baldeep Sidhu
- Department of Imaging Sciences and Biomedical Engineering, Kings College London, London, United Kingdom
| | - Reza Razavi
- Department of Imaging Sciences and Biomedical Engineering, Kings College London, London, United Kingdom
| | - Christopher A. Rinaldi
- Department of Cardiovascular Sciences, University College London, London, United Kingdom
| | - Jaswinder S. Gill
- Department of Cardiovascular Sciences, University College London, London, United Kingdom
| | - Peter Taggart
- Guy's and St Thomas' Hospital, London, United Kingdom
| |
Collapse
|
36
|
Abstract
Heart failure (HF) following myocardial infarction (MI) is associated with high incidence of cardiac arrhythmias. Development of therapeutic strategy requires detailed understanding of electrophysiological remodeling. However, changes of ionic currents in ischemic HF remain incompletely understood, especially in translational large-animal models. Here, we systematically measure the major ionic currents in ventricular myocytes from the infarct border and remote zones in a porcine model of post-MI HF. We recorded eight ionic currents during the cell's action potential (AP) under physiologically relevant conditions using selfAP-clamp sequential dissection. Compared with healthy controls, HF-remote zone myocytes exhibited increased late Na+ current, Ca2+-activated K+ current, Ca2+-activated Cl- current, decreased rapid delayed rectifier K+ current, and altered Na+/Ca2+ exchange current profile. In HF-border zone myocytes, the above changes also occurred but with additional decrease of L-type Ca2+ current, decrease of inward rectifier K+ current, and Ca2+ release-dependent delayed after-depolarizations. Our data reveal that the changes in any individual current are relatively small, but the integrated impacts shift the balance between the inward and outward currents to shorten AP in the border zone but prolong AP in the remote zone. This differential remodeling in post-MI HF increases the inhomogeneity of AP repolarization, which may enhance the arrhythmogenic substrate. Our comprehensive findings provide a mechanistic framework for understanding why single-channel blockers may fail to suppress arrhythmias, and highlight the need to consider the rich tableau and integration of many ionic currents in designing therapeutic strategies for treating arrhythmias in HF.
Collapse
|
37
|
Hegyi B, Bossuyt J, Ginsburg KS, Mendoza LM, Talken L, Ferrier WT, Pogwizd SM, Izu LT, Chen-Izu Y, Bers DM. Altered Repolarization Reserve in Failing Rabbit Ventricular Myocytes: Calcium and β-Adrenergic Effects on Delayed- and Inward-Rectifier Potassium Currents. Circ Arrhythm Electrophysiol 2018; 11:e005852. [PMID: 29437761 PMCID: PMC5813707 DOI: 10.1161/circep.117.005852] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2017] [Accepted: 12/11/2017] [Indexed: 12/25/2022]
Abstract
BACKGROUND Electrophysiological remodeling and increased susceptibility for cardiac arrhythmias are hallmarks of heart failure (HF). Ventricular action potential duration (APD) is typically prolonged in HF, with reduced repolarization reserve. However, underlying K+ current changes are often measured in nonphysiological conditions (voltage clamp, low pacing rates, cytosolic Ca2+ buffers). METHODS AND RESULTS We measured the major K+ currents (IKr, IKs, and IK1) and their Ca2+- and β-adrenergic dependence in rabbit ventricular myocytes in chronic pressure/volume overload-induced HF (versus age-matched controls). APD was significantly prolonged only at lower pacing rates (0.2-1 Hz) in HF under physiological ionic conditions and temperature. However, when cytosolic Ca2+ was buffered, APD prolongation in HF was also significant at higher pacing rates. Beat-to-beat variability of APD was also significantly increased in HF. Both IKr and IKs were significantly upregulated in HF under action potential clamp, but only when cytosolic Ca2+ was not buffered. CaMKII (Ca2+/calmodulin-dependent protein kinase II) inhibition abolished IKs upregulation in HF, but it did not affect IKr. IKs response to β-adrenergic stimulation was also significantly diminished in HF. IK1 was also decreased in HF regardless of Ca2+ buffering, CaMKII inhibition, or β-adrenergic stimulation. CONCLUSIONS At baseline Ca2+-dependent upregulation of IKr and IKs in HF counterbalances the reduced IK1, maintaining repolarization reserve (especially at higher heart rates) in physiological conditions, unlike conditions of strong cytosolic Ca2+ buffering. However, under β-adrenergic stimulation, reduced IKs responsiveness severely limits integrated repolarizing K+ current and repolarization reserve in HF. This would increase arrhythmia propensity in HF, especially during adrenergic stress.
Collapse
Affiliation(s)
- Bence Hegyi
- From the Department of Pharmacology (B.H., J.B., K.S.G., L.T.I., Y.C.-I., D.M.B.), School of Medicine, Dean's Office (L.T.), Surgical Research Facility, School of Medicine (W.T.F.), Department of Biomedical Engineering (Y.C.-I.), Department of Internal Medicine/Cardiology (Y.C.-I.), University of California, Davis; Echocardiography Laboratory, University of California, Davis Medical Center, Sacramento (L.M.M.); and Department of Medicine, University of Alabama at Birmingham (S.M.P.)
| | - Julie Bossuyt
- From the Department of Pharmacology (B.H., J.B., K.S.G., L.T.I., Y.C.-I., D.M.B.), School of Medicine, Dean's Office (L.T.), Surgical Research Facility, School of Medicine (W.T.F.), Department of Biomedical Engineering (Y.C.-I.), Department of Internal Medicine/Cardiology (Y.C.-I.), University of California, Davis; Echocardiography Laboratory, University of California, Davis Medical Center, Sacramento (L.M.M.); and Department of Medicine, University of Alabama at Birmingham (S.M.P.)
| | - Kenneth S Ginsburg
- From the Department of Pharmacology (B.H., J.B., K.S.G., L.T.I., Y.C.-I., D.M.B.), School of Medicine, Dean's Office (L.T.), Surgical Research Facility, School of Medicine (W.T.F.), Department of Biomedical Engineering (Y.C.-I.), Department of Internal Medicine/Cardiology (Y.C.-I.), University of California, Davis; Echocardiography Laboratory, University of California, Davis Medical Center, Sacramento (L.M.M.); and Department of Medicine, University of Alabama at Birmingham (S.M.P.)
| | - Lynette M Mendoza
- From the Department of Pharmacology (B.H., J.B., K.S.G., L.T.I., Y.C.-I., D.M.B.), School of Medicine, Dean's Office (L.T.), Surgical Research Facility, School of Medicine (W.T.F.), Department of Biomedical Engineering (Y.C.-I.), Department of Internal Medicine/Cardiology (Y.C.-I.), University of California, Davis; Echocardiography Laboratory, University of California, Davis Medical Center, Sacramento (L.M.M.); and Department of Medicine, University of Alabama at Birmingham (S.M.P.)
| | - Linda Talken
- From the Department of Pharmacology (B.H., J.B., K.S.G., L.T.I., Y.C.-I., D.M.B.), School of Medicine, Dean's Office (L.T.), Surgical Research Facility, School of Medicine (W.T.F.), Department of Biomedical Engineering (Y.C.-I.), Department of Internal Medicine/Cardiology (Y.C.-I.), University of California, Davis; Echocardiography Laboratory, University of California, Davis Medical Center, Sacramento (L.M.M.); and Department of Medicine, University of Alabama at Birmingham (S.M.P.)
| | - William T Ferrier
- From the Department of Pharmacology (B.H., J.B., K.S.G., L.T.I., Y.C.-I., D.M.B.), School of Medicine, Dean's Office (L.T.), Surgical Research Facility, School of Medicine (W.T.F.), Department of Biomedical Engineering (Y.C.-I.), Department of Internal Medicine/Cardiology (Y.C.-I.), University of California, Davis; Echocardiography Laboratory, University of California, Davis Medical Center, Sacramento (L.M.M.); and Department of Medicine, University of Alabama at Birmingham (S.M.P.)
| | - Steven M Pogwizd
- From the Department of Pharmacology (B.H., J.B., K.S.G., L.T.I., Y.C.-I., D.M.B.), School of Medicine, Dean's Office (L.T.), Surgical Research Facility, School of Medicine (W.T.F.), Department of Biomedical Engineering (Y.C.-I.), Department of Internal Medicine/Cardiology (Y.C.-I.), University of California, Davis; Echocardiography Laboratory, University of California, Davis Medical Center, Sacramento (L.M.M.); and Department of Medicine, University of Alabama at Birmingham (S.M.P.)
| | - Leighton T Izu
- From the Department of Pharmacology (B.H., J.B., K.S.G., L.T.I., Y.C.-I., D.M.B.), School of Medicine, Dean's Office (L.T.), Surgical Research Facility, School of Medicine (W.T.F.), Department of Biomedical Engineering (Y.C.-I.), Department of Internal Medicine/Cardiology (Y.C.-I.), University of California, Davis; Echocardiography Laboratory, University of California, Davis Medical Center, Sacramento (L.M.M.); and Department of Medicine, University of Alabama at Birmingham (S.M.P.)
| | - Ye Chen-Izu
- From the Department of Pharmacology (B.H., J.B., K.S.G., L.T.I., Y.C.-I., D.M.B.), School of Medicine, Dean's Office (L.T.), Surgical Research Facility, School of Medicine (W.T.F.), Department of Biomedical Engineering (Y.C.-I.), Department of Internal Medicine/Cardiology (Y.C.-I.), University of California, Davis; Echocardiography Laboratory, University of California, Davis Medical Center, Sacramento (L.M.M.); and Department of Medicine, University of Alabama at Birmingham (S.M.P.)
| | - Donald M Bers
- From the Department of Pharmacology (B.H., J.B., K.S.G., L.T.I., Y.C.-I., D.M.B.), School of Medicine, Dean's Office (L.T.), Surgical Research Facility, School of Medicine (W.T.F.), Department of Biomedical Engineering (Y.C.-I.), Department of Internal Medicine/Cardiology (Y.C.-I.), University of California, Davis; Echocardiography Laboratory, University of California, Davis Medical Center, Sacramento (L.M.M.); and Department of Medicine, University of Alabama at Birmingham (S.M.P.).
| |
Collapse
|
38
|
Zaza A, Ronchi C, Malfatto G. Arrhythmias and Heart Rate: Mechanisms and Significance of a Relationship. Arrhythm Electrophysiol Rev 2018; 7:232-237. [PMID: 30588310 DOI: 10.15420/aer.2018.12.3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2018] [Accepted: 05/17/2018] [Indexed: 11/04/2022] Open
Abstract
The occurrence of arrhythmia is often related to basic heart rate. Prognostic significance is associated with such a relationship; furthermore, heart rate modulation may result as an ancillary effect of therapy, or be considered as a therapeutic tool. This review discusses the cellular mechanisms underlying arrhythmia occurrence during tachycardia or bradycardia, considering rate changes per se or as a mirror of autonomic modulation. Besides the influence of steady-state heart rate, dynamic aspects of changes in rate and autonomic balance are considered. The discussion leads to the conclusion that the prognostic significance of arrhythmia relationship with heart rate, and the consequence of heart rate on arrhythmogenesis, may vary according to the substrate present in the specific case and should be considered accordingly.
Collapse
Affiliation(s)
- Antonio Zaza
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi Milano-Bicocca Milan, Italy.,CARIM, Maastricht University Maastricht, the Netherlands
| | - Carlotta Ronchi
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi Milano-Bicocca Milan, Italy
| | | |
Collapse
|
39
|
Walker MA, Gurev V, Rice JJ, Greenstein JL, Winslow RL. Estimating the probabilities of rare arrhythmic events in multiscale computational models of cardiac cells and tissue. PLoS Comput Biol 2017; 13:e1005783. [PMID: 29145393 PMCID: PMC5689829 DOI: 10.1371/journal.pcbi.1005783] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 09/18/2017] [Indexed: 11/24/2022] Open
Abstract
Ectopic heartbeats can trigger reentrant arrhythmias, leading to ventricular fibrillation and sudden cardiac death. Such events have been attributed to perturbed Ca2+ handling in cardiac myocytes leading to spontaneous Ca2+ release and delayed afterdepolarizations (DADs). However, the ways in which perturbation of specific molecular mechanisms alters the probability of ectopic beats is not understood. We present a multiscale model of cardiac tissue incorporating a biophysically detailed three-dimensional model of the ventricular myocyte. This model reproduces realistic Ca2+ waves and DADs driven by stochastic Ca2+ release channel (RyR) gating and is used to study mechanisms of DAD variability. In agreement with previous experimental and modeling studies, key factors influencing the distribution of DAD amplitude and timing include cytosolic and sarcoplasmic reticulum Ca2+ concentrations, inwardly rectifying potassium current (IK1) density, and gap junction conductance. The cardiac tissue model is used to investigate how random RyR gating gives rise to probabilistic triggered activity in a one-dimensional myocyte tissue model. A novel spatial-average filtering method for estimating the probability of extreme (i.e. rare, high-amplitude) stochastic events from a limited set of spontaneous Ca2+ release profiles is presented. These events occur when randomly organized clusters of cells exhibit synchronized, high amplitude Ca2+ release flux. It is shown how reduced IK1 density and gap junction coupling, as observed in heart failure, increase the probability of extreme DADs by multiple orders of magnitude. This method enables prediction of arrhythmia likelihood and its modulation by alterations of other cellular mechanisms.
Collapse
Affiliation(s)
- Mark A. Walker
- Department of Biomedical Engineering and Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD, United States of America
| | - Viatcheslav Gurev
- TJ Watson Research Center, IBM, Yorktown Heights, NY, United States of America
| | - John J. Rice
- TJ Watson Research Center, IBM, Yorktown Heights, NY, United States of America
| | - Joseph L. Greenstein
- Department of Biomedical Engineering and Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD, United States of America
| | - Raimond L. Winslow
- Department of Biomedical Engineering and Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD, United States of America
| |
Collapse
|
40
|
Orini M, Pueyo E, Laguna P, Bailon R. A Time-Varying Nonparametric Methodology for Assessing Changes in QT Variability Unrelated to Heart Rate Variability. IEEE Trans Biomed Eng 2017; 65:1443-1451. [PMID: 28991727 DOI: 10.1109/tbme.2017.2758925] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
OBJECTIVE To propose and test a novel methodology to measure changes in QT interval variability (QTV) unrelated to RR interval variability (RRV) in nonstationary conditions. METHODS Time-frequency coherent and residual spectra representing QTV related (QTVrRRV) and unrelated (QTVuRRV) to RRV, respectively, are estimated using time-frequency Cohen's class distributions. The proposed approach decomposes the nonstationary output spectrum of any two-input one-output model with uncorrelated inputs into two spectra representing the information related and unrelated to one of the two inputs, respectively. An algorithm to correct for the bias of the time-frequency coherence function between QTV and RRV is proposed to provide accurate estimates of both QTVuRRV and QTVrRRV. Two simulation studies were conducted to assess the methodology in challenging nonstationary conditions and data recorded during head-up tilt in 16 healthy volunteers were analyzed. RESULTS In the simulation studies, QTVuRRV changes were tracked with only a minor delay due to the filtering necessary to estimate the nonstationary spectra. The correlation coefficient between theoretical and estimated patterns was even for extremely noisy recordings (signal to noise ratio (SNR) in QTV dB). During head-up tilt, QTVrRRV explained the largest proportion of QTV, whereas QTVuRRV showed higher relative increase than QTV or QTVrRRV in all spectral bands ( for most pairwise comparisons). CONCLUSION The proposed approach accurately tracks changes in QTVuRRV. Head-up tilt induced a slightly greater increase in QTVuRRV than in QTVrRRV. SIGNIFICANCE The proposed index QTVuRRV may represent an indirect measure of intrinsic ventricular repolarization variability, a marker of cardiac instability associated with sympathetic ventricular modulation and sudden cardiac death.
Collapse
|
41
|
Piccini I, Fehrmann E, Frank S, Müller FU, Greber B, Seebohm G. Adrenergic Stress Protection of Human iPS Cell-Derived Cardiomyocytes by Fast K v7.1 Recycling. Front Physiol 2017; 8:705. [PMID: 28959214 PMCID: PMC5603700 DOI: 10.3389/fphys.2017.00705] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Accepted: 08/31/2017] [Indexed: 01/09/2023] Open
Abstract
The fight-or-flight response (FFR), a physiological acute stress reaction, involves positive chronotropic and inotropic effects on heart muscle cells mediated through β-adrenoceptor activation. Increased systolic calcium is required to enable stronger heart contractions whereas elevated potassium currents are to limit the duration of the action potentials and prevent arrhythmia. The latter effect is accomplished by an increased functional activity of the Kv7.1 channel encoded by KCNQ1. Current knowledge, however, does not sufficiently explain the full extent of rapid Kv7.1 activation and may hence be incomplete. Using inducible genetic KCNQ1 complementation in KCNQ1-deficient human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs), we here reinvestigate the functional role of Kv7.1 in adapting human CMs to adrenergic stress. Under baseline conditions, Kv7.1 was barely detectable at the plasma membrane of hiPSC-CMs, yet it fully protected these from adrenergic stress-induced beat-to-beat variability of repolarization and torsade des pointes-like arrhythmia. Furthermore, isoprenaline treatment increased field potential durations specifically in KCNQ1-deficient CMs to cause these adverse macroscopic effects. Mechanistically, we find that the protective action by Kv7.1 resides in a rapid translocation of channel proteins from intracellular stores to the plasma membrane, induced by adrenergic signaling. Gene silencing experiments targeting RAB GTPases, mediators of intracellular vesicle trafficking, showed that fast Kv7.1 recycling under acute stress conditions is RAB4A-dependent.Our data reveal a key mechanism underlying the rapid adaptation of human cardiomyocytes to adrenergic stress. These findings moreover aid to the understanding of disease pathology in long QT syndrome and bear important implications for safety pharmacological screening.
Collapse
Affiliation(s)
- Ilaria Piccini
- Department of Cardiovascular Medicine, Institute of Genetics of Heart Diseases, University of Münster Medical SchoolMünster, Germany.,Human Stem Cell Pluripotency Laboratory, Max Planck Institute for Molecular BiomedicineMünster, Germany
| | - Edda Fehrmann
- Institute of Pharmacology and Toxicology, University of MünsterMünster, Germany
| | - Stefan Frank
- Human Stem Cell Pluripotency Laboratory, Max Planck Institute for Molecular BiomedicineMünster, Germany.,Chemical Genomics Centre of the Max Planck SocietyDortmund, Germany
| | - Frank U Müller
- Institute of Pharmacology and Toxicology, University of MünsterMünster, Germany
| | - Boris Greber
- Human Stem Cell Pluripotency Laboratory, Max Planck Institute for Molecular BiomedicineMünster, Germany.,Chemical Genomics Centre of the Max Planck SocietyDortmund, Germany
| | - Guiscard Seebohm
- Department of Cardiovascular Medicine, Institute of Genetics of Heart Diseases, University of Münster Medical SchoolMünster, Germany
| |
Collapse
|
42
|
Nánási PP, Magyar J, Varró A, Ördög B. Beat-to-beat variability of cardiac action potential duration: underlying mechanism and clinical implications. Can J Physiol Pharmacol 2017; 95:1230-1235. [PMID: 28746810 DOI: 10.1139/cjpp-2016-0597] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Beat-to-beat variability of cardiac action potential duration (short-term variability, SV) is a common feature of various cardiac preparations, including the human heart. Although it is believed to be one of the best arrhythmia predictors, the underlying mechanisms are not fully understood at present. The magnitude of SV is basically determined by the intensity of cell-to-cell coupling in multicellular preparations and by the duration of the action potential (APD). To compensate for the APD-dependent nature of SV, the concept of relative SV (RSV) has been introduced by normalizing the changes of SV to the concomitant changes in APD. RSV is reduced by ICa, IKr, and IKs while increased by INa, suggesting that ion currents involved in the negative feedback regulation of APD tend to keep RSV at a low level. RSV is also influenced by intracellular calcium concentration and tissue redox potential. The clinical implications of APD variability is discussed in detail.
Collapse
Affiliation(s)
- Péter P Nánási
- a Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.,b Department of Dental Physiology and Pharmacology, Faculty of Dentistry, University of Debrecen, Debrecen, Hungary
| | - János Magyar
- a Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - András Varró
- c Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - Balázs Ördög
- c Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| |
Collapse
|
43
|
Porter B, Bishop MJ, Claridge S, Behar J, Sieniewicz BJ, Webb J, Gould J, O'Neill M, Rinaldi CA, Razavi R, Gill JS, Taggart P. Autonomic Modulation in Patients with Heart Failure Increases Beat-to-Beat Variability of Ventricular Action Potential Duration. Front Physiol 2017; 8:328. [PMID: 28611676 PMCID: PMC5447044 DOI: 10.3389/fphys.2017.00328] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 05/05/2017] [Indexed: 12/19/2022] Open
Abstract
Background: Exaggerated beat-to-beat variability of ventricular action potential duration (APD) is linked to arrhythmogenesis. Sympathetic stimulation has been shown to increase QT interval variability, but its effect on ventricular APD in humans has not been determined. Methods and Results: Eleven heart failure patients with implanted bi-ventricular pacing devices had activation–recovery intervals (ARI, surrogate for APD) recorded from LV epicardial electrodes under constant RV pacing. Sympathetic activity was increased using a standard autonomic challenge (Valsalva) and baroreceptor indices were applied to determine changes in sympathetic stimulation. Two Valsalvas were performed for each study and were repeated, both off and on bisoprolol. In addition sympathetic nerve activity (SNA) was measured from skin electrodes on the thorax using a novel validated method. Autonomic modulation significantly increased mean short-term variability in ARI; off bisoprolol mean STV increased from 3.73 ± 1.3 to 5.27 ± 1.04 ms (p = 0.01), on bisoprolol mean STV of ARI increased from 4.15 ± 1.14 to 4.62 ± 1 ms (p = 0.14). Adrenergic indices of the Valsalva demonstrated significantly reduced beta-adrenergic function when on bisoprolol (Δ pressure recovery time, p = 0.04; Δ systolic overshoot in Phase IV, p = 0.05). Corresponding increases in SNA from rest both off (1.4 uV, p < 0.01) and on (0.7 uV, p < 0.01) bisoprolol were also seen. Conclusions: Beat-to-beat variability of ventricular APD increases during brief periods of increased sympathetic activity in patients with heart failure. Bisoprolol reduces, but does not eliminate, these effects. This may be important in the genesis of ventricular arrhythmias in heart failure patients.
Collapse
Affiliation(s)
- Bradley Porter
- Department of Imaging Sciences and Biomedical Engineering, Kings College LondonLondon, United Kingdom
| | - Martin J Bishop
- Department of Imaging Sciences and Biomedical Engineering, Kings College LondonLondon, United Kingdom
| | - Simon Claridge
- Department of Imaging Sciences and Biomedical Engineering, Kings College LondonLondon, United Kingdom
| | - Jonathan Behar
- Department of Imaging Sciences and Biomedical Engineering, Kings College LondonLondon, United Kingdom
| | - Benjamin J Sieniewicz
- Department of Imaging Sciences and Biomedical Engineering, Kings College LondonLondon, United Kingdom
| | - Jessica Webb
- Department of Imaging Sciences and Biomedical Engineering, Kings College LondonLondon, United Kingdom
| | - Justin Gould
- Department of Imaging Sciences and Biomedical Engineering, Kings College LondonLondon, United Kingdom
| | - Mark O'Neill
- Cardiology Department, Guy's and St. Thomas' HospitalLondon, United Kingdom
| | | | - Reza Razavi
- Department of Imaging Sciences and Biomedical Engineering, Kings College LondonLondon, United Kingdom
| | - Jaswinder S Gill
- Cardiology Department, Guy's and St. Thomas' HospitalLondon, United Kingdom
| | - Peter Taggart
- Department of Cardiovascular Sciences, University College LondonLondon, United Kingdom
| |
Collapse
|
44
|
Gewirtz H, Dilsizian V. Myocardial Viability: Survival Mechanisms and Molecular Imaging Targets in Acute and Chronic Ischemia. Circ Res 2017; 120:1197-1212. [PMID: 28360350 DOI: 10.1161/circresaha.116.307898] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Revised: 02/27/2017] [Accepted: 03/02/2017] [Indexed: 12/17/2022]
Abstract
Myocardial responses to acute ischemia/reperfusion and to chronic ischemic conditions have been studied extensively at all levels of organization. These include subcellular (eg, mitochondria in vitro); intact, large animal models (eg, swine with chronic coronary stenosis); as well as human subjects. Investigations in humans have used positron emission tomographic metabolic and myocardial blood flow measurements, assessment of gene expression and anatomic description of myocardium obtained at the time of coronary artery revascularization, ventricular assist device placement, or heart transplantation. A multitude of genetic, molecular, and metabolic pathways have been identified, which may promote either myocyte survival or death or, most interestingly, both. Many of these potential mediators in both acute ischemia/reperfusion and adaptations to chronic ischemic conditions involve the mitochondria, which play a central role in cellular energy production and homeostasis. The present review is focused on operative survival mechanisms and potential myocardial viability molecular imaging targets in acute and chronic ischemia, especially those which impact mitochondrial function.
Collapse
Affiliation(s)
- Henry Gewirtz
- From the Department of Medicine (Cardiology Division), Massachusetts General Hospital, Harvard Medical School, Boston (H.G.); and Department of Diagnostic Radiology and Nuclear Medicine, University of Maryland School of Medicine, Baltimore (V.D.)
| | - Vasken Dilsizian
- From the Department of Medicine (Cardiology Division), Massachusetts General Hospital, Harvard Medical School, Boston (H.G.); and Department of Diagnostic Radiology and Nuclear Medicine, University of Maryland School of Medicine, Baltimore (V.D.).
| |
Collapse
|
45
|
Tissue Specificity: Store-Operated Ca 2+ Entry in Cardiac Myocytes. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 993:363-387. [PMID: 28900924 DOI: 10.1007/978-3-319-57732-6_19] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Calcium (Ca2+) is a key regulator of cardiomyocyte contraction. The Ca2+ channels, pumps, and exchangers responsible for the cyclical cytosolic Ca2+ signals that underlie contraction are well known. In addition to those Ca2+ signaling components responsible for contraction, it has been proposed that cardiomyocytes express channels that promote the influx of Ca2+ from the extracellular milieu to the cytosol in response to depletion of intracellular Ca2+ stores. With non-excitable cells, this store-operated Ca2+ entry (SOCE) is usually easily demonstrated and is essential for prolonging cellular Ca2+ signaling and for refilling depleted Ca2+ stores. The role of SOCE in cardiomyocytes, however, is rather more elusive. While there is published evidence for increased Ca2+ influx into cardiomyocytes following Ca2+ store depletion, it has not been universally observed. Moreover, SOCE appears to be prominent in embryonic cardiomyocytes but declines with postnatal development. In contrast, there is overwhelming evidence that the molecular components of SOCE (e.g., STIM, Orai, and TRPC proteins) are expressed in cardiomyocytes from embryo to adult. Moreover, these proteins have been shown to contribute to disease conditions such as pathological hypertrophy, and reducing their expression can attenuate hypertrophic growth. It is plausible that SOCE might underlie Ca2+ influx into cardiomyocytes and may have important signaling functions perhaps by activating local Ca2+-sensitive processes. However, the STIM, Orai, and TRPC proteins appear to cooperate with multiple protein partners in signaling complexes. It is therefore possible that some of their signaling activities are not mediated by Ca2+ influx signals, but by protein-protein interactions.
Collapse
|
46
|
Němec J. Nonalternans repolarization variability and arrhythmia – the calcium connection. J Electrocardiol 2016; 49:877-882. [DOI: 10.1016/j.jelectrocard.2016.08.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Indexed: 12/19/2022]
|
47
|
Pueyo E, Orini M, Rodríguez JF, Taggart P. Interactive effect of beta-adrenergic stimulation and mechanical stretch on low-frequency oscillations of ventricular action potential duration in humans. J Mol Cell Cardiol 2016; 97:93-105. [DOI: 10.1016/j.yjmcc.2016.05.003] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Revised: 03/21/2016] [Accepted: 05/03/2016] [Indexed: 01/27/2023]
|
48
|
Baumert M, Porta A, Vos MA, Malik M, Couderc JP, Laguna P, Piccirillo G, Smith GL, Tereshchenko LG, Volders PGA. QT interval variability in body surface ECG: measurement, physiological basis, and clinical value: position statement and consensus guidance endorsed by the European Heart Rhythm Association jointly with the ESC Working Group on Cardiac Cellular Electrophysiology. Europace 2016; 18:925-44. [PMID: 26823389 PMCID: PMC4905605 DOI: 10.1093/europace/euv405] [Citation(s) in RCA: 140] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Accepted: 11/05/2015] [Indexed: 12/20/2022] Open
Abstract
This consensus guideline discusses the electrocardiographic phenomenon of beat-to-beat QT interval variability (QTV) on surface electrocardiograms. The text covers measurement principles, physiological basis, and clinical value of QTV. Technical considerations include QT interval measurement and the relation between QTV and heart rate variability. Research frontiers of QTV include understanding of QTV physiology, systematic evaluation of the link between QTV and direct measures of neural activity, modelling of the QTV dependence on the variability of other physiological variables, distinction between QTV and general T wave shape variability, and assessing of the QTV utility for guiding therapy. Increased QTV appears to be a risk marker of arrhythmic and cardiovascular death. It remains to be established whether it can guide therapy alone or in combination with other risk factors. QT interval variability has a possible role in non-invasive assessment of tonic sympathetic activity.
Collapse
Affiliation(s)
- Mathias Baumert
- School of Electrical and Electronic Engineering, The University of Adelaide, Adelaide, SA, Australia
| | - Alberto Porta
- Department of Biomedical Sciences for Health, University of Milan, Milan, Italy Department of Cardiothoracic, Vascular Anesthesia and Intensive Care, IRCCS Policlinico San Donato, Milan, Italy
| | - Marc A Vos
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Marek Malik
- St Paul's Cardiac Electrophysiology, University of London, and National Heart and Lung Institute, Imperial College, Dovehouse Street, London SW3 6LY, UK
| | - Jean-Philippe Couderc
- Heart Research Follow-Up Program, University of Rochester Medical Center, Rochester, NY, USA
| | - Pablo Laguna
- Zaragoza University and CIBER-BBN, Zaragoza, Spain
| | - Gianfranco Piccirillo
- Dipartimento di Scienze Cardiovascolari, Respiratorie, Nefrologiche, Anestesiologiche e Geriatriche, Università 'La Sapienza' Rome, Rome, Italy
| | - Godfrey L Smith
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, UK
| | - Larisa G Tereshchenko
- Oregon Health and Science University, Knight Cardiovascular Institute, Portland, OR, USA
| | - Paul G A Volders
- Department of Cardiology, Cardiovascular Research Institute Maastricht, Maastricht University Medical Centre, Maastricht, The Netherlands
| |
Collapse
|
49
|
Klimas A, Ambrosi CM, Yu J, Williams JC, Bien H, Entcheva E. OptoDyCE as an automated system for high-throughput all-optical dynamic cardiac electrophysiology. Nat Commun 2016; 7:11542. [PMID: 27161419 PMCID: PMC4866323 DOI: 10.1038/ncomms11542] [Citation(s) in RCA: 107] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2015] [Accepted: 04/05/2016] [Indexed: 01/11/2023] Open
Abstract
The improvement of preclinical cardiotoxicity testing, discovery of new ion-channel-targeted drugs, and phenotyping and use of stem cell-derived cardiomyocytes and other biologics all necessitate high-throughput (HT), cellular-level electrophysiological interrogation tools. Optical techniques for actuation and sensing provide instant parallelism, enabling contactless dynamic HT testing of cells and small-tissue constructs, not affordable by other means. Here we show, computationally and experimentally, the limits of all-optical electrophysiology when applied to drug testing, then implement and validate OptoDyCE, a fully automated system for all-optical cardiac electrophysiology. We validate optical actuation by virally introducing optogenetic drivers in rat and human cardiomyocytes or through the modular use of dedicated light-sensitive somatic ‘spark' cells. We show that this automated all-optical approach provides HT means of cellular interrogation, that is, allows for dynamic testing of >600 multicellular samples or compounds per hour, and yields high-content information about the action of a drug over time, space and doses. The efficiency of preclinical drug testing and characterization of cellular function can be improved through the use of optogenetic tools. Here Klimas et al. present and validate OptoDyCE, a fully automated system for all-optical high-throughput cardiac electrophysiology.
Collapse
Affiliation(s)
- Aleksandra Klimas
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York, USA
| | - Christina M Ambrosi
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York, USA
| | - Jinzhu Yu
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York, USA
| | - John C Williams
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York, USA
| | - Harold Bien
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York, USA
| | - Emilia Entcheva
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York, USA
| |
Collapse
|
50
|
Pueyo E, Dangerfield CE, Britton OJ, Virág L, Kistamás K, Szentandrássy N, Jost N, Varró A, Nánási PP, Burrage K, Rodríguez B. Experimentally-Based Computational Investigation into Beat-To-Beat Variability in Ventricular Repolarization and Its Response to Ionic Current Inhibition. PLoS One 2016; 11:e0151461. [PMID: 27019293 PMCID: PMC4809506 DOI: 10.1371/journal.pone.0151461] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2015] [Accepted: 02/29/2016] [Indexed: 11/18/2022] Open
Abstract
Beat-to-beat variability in repolarization (BVR) has been proposed as an arrhythmic risk marker for disease and pharmacological action. The mechanisms are unclear but BVR is thought to be a cell level manifestation of ion channel stochasticity, modulated by cell-to-cell differences in ionic conductances. In this study, we describe the construction of an experimentally-calibrated set of stochastic cardiac cell models that captures both BVR and cell-to-cell differences in BVR displayed in isolated canine action potential measurements using pharmacological agents. Simulated and experimental ranges of BVR are compared in control and under pharmacological inhibition, and the key ionic currents determining BVR under physiological and pharmacological conditions are identified. Results show that the 4-aminopyridine-sensitive transient outward potassium current, Ito1, is a fundamental driver of BVR in control and upon complete inhibition of the slow delayed rectifier potassium current, IKs. In contrast, IKs and the L-type calcium current, ICaL, become the major contributors to BVR upon inhibition of the fast delayed rectifier potassium current, IKr. This highlights both IKs and Ito1 as key contributors to repolarization reserve. Partial correlation analysis identifies the distribution of Ito1 channel numbers as an important independent determinant of the magnitude of BVR and drug-induced change in BVR in control and under pharmacological inhibition of ionic currents. Distributions in the number of IKs and ICaL channels only become independent determinants of the magnitude of BVR upon complete inhibition of IKr. These findings provide quantitative insights into the ionic causes of BVR as a marker for repolarization reserve, both under control condition and pharmacological inhibition.
Collapse
Affiliation(s)
- E. Pueyo
- Biomedical Research Networking Centre on Bioengineering, Biomaterials and Nanomedicine, University of Zaragoza, Zaragoza, Spain
- Biosignal Interpretation and Computational Simulation Group, I3A, IIS, Aragón, University of Zaragoza, Zaragoza, Spain
- * E-mail:
| | - C. E. Dangerfield
- Department of Computer Science, University of Oxford, Oxford, United Kingdom
| | - O. J. Britton
- Department of Computer Science, University of Oxford, Oxford, United Kingdom
| | - L. Virág
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
- MTA-SZTE Research Group of Cardiovascular Pharmacology, Hungarian Academy of Sciences, Szeged, Hungary
| | - K. Kistamás
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - N. Szentandrássy
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
- Department of Dental Physiology and Pharmacology, Faculty of Dentistry, University of Debrecen, Debrecen, Hungary
| | - N. Jost
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
- MTA-SZTE Research Group of Cardiovascular Pharmacology, Hungarian Academy of Sciences, Szeged, Hungary
| | - A. Varró
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
- MTA-SZTE Research Group of Cardiovascular Pharmacology, Hungarian Academy of Sciences, Szeged, Hungary
| | - P. P. Nánási
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
- Department of Dental Physiology and Pharmacology, Faculty of Dentistry, University of Debrecen, Debrecen, Hungary
| | - K. Burrage
- Department of Computer Science, University of Oxford, Oxford, United Kingdom
- School of Mathematical Sciences, Queensland University of Technology, Brisbane, Queensland, Australia
- ARC Centre of Excellence for Mathematical and Statistical Frontiers, Queensland University of Technology, Brisbane, Queensland, Australia
| | - B. Rodríguez
- Department of Computer Science, University of Oxford, Oxford, United Kingdom
| |
Collapse
|