51
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Kasapkara HA, Şentürk A, Bilen E, Ayhan H, Karaduman BD, Turinay ZŞ, Güney MC, Durmaz T, Keleş T, Bozkurt E. Evaluation of QT dispersion and T-peak to T-end interval in patients with early-stage sarcoidosis. Rev Port Cardiol 2017; 36:919-924. [DOI: 10.1016/j.repc.2017.05.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Revised: 02/26/2017] [Accepted: 05/08/2017] [Indexed: 10/18/2022] Open
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Watson SA, Scigliano M, Bardi I, Ascione R, Terracciano CM, Perbellini F. Preparation of viable adult ventricular myocardial slices from large and small mammals. Nat Protoc 2017; 12:2623-2639. [PMID: 29189769 DOI: 10.1038/nprot.2017.139] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
This protocol describes the preparation of highly viable adult ventricular myocardial slices from the hearts of small and large mammals, including rodents, pigs, dogs and humans. Adult ventricular myocardial slices are 100- to 400-μm-thick slices of living myocardium that retain the native multicellularity, architecture and physiology of the heart. This protocol provides a list of the equipment and reagents required alongside a detailed description of the methodology for heart explantation, tissue preparation, slicing with a vibratome and handling of myocardial slices. Supplementary videos are included to visually demonstrate these steps. A number of critical steps are addressed that must be followed in order to prepare highly viable myocardial slices. These include identification of myocardial fiber direction and fiber alignment within the tissue block, careful temperature control, use of an excitation-contraction uncoupler, optimal vibratome settings and correct handling of myocardial slices. Many aspects of cardiac structure and function can be studied using myocardial slices in vitro. Typical results obtained with hearts from a small mammal (rat) and a large mammal (human) with heart failure are shown, demonstrating myocardial slice viability, maximum contractility, Ca2+ handling and structure. This protocol can be completed in ∼4 h.
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Affiliation(s)
- Samuel A Watson
- Division of Cardiovascular Sciences, Myocardial Function, National Heart and Lung Institute, Imperial College London, London, UK
| | - Martina Scigliano
- Division of Cardiovascular Sciences, Myocardial Function, National Heart and Lung Institute, Imperial College London, London, UK
| | - Ifigeneia Bardi
- Division of Cardiovascular Sciences, Myocardial Function, National Heart and Lung Institute, Imperial College London, London, UK
| | - Raimondo Ascione
- Translational Biomedical Research Centre, University of Bristol, Bristol, UK
| | - Cesare M Terracciano
- Division of Cardiovascular Sciences, Myocardial Function, National Heart and Lung Institute, Imperial College London, London, UK
| | - Filippo Perbellini
- Division of Cardiovascular Sciences, Myocardial Function, National Heart and Lung Institute, Imperial College London, London, UK
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53
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Kirthi Priya P, Reddy MR. Simulation study of the ionic mechanisms underlying Torsade de Pointes in a 2D cardiac tissue. Comput Biol Med 2017; 89:293-303. [PMID: 28858645 DOI: 10.1016/j.compbiomed.2017.08.017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2017] [Revised: 08/18/2017] [Accepted: 08/19/2017] [Indexed: 10/19/2022]
Abstract
BACKGROUND To understand the ionic mechanism behind the genesis of Torsade de Pointes (TdP) occurring with long QT syndrome 2 (LQTS2) in a remodelled transmural tissue. METHODS The TP06 model is used to simulate the electrical activity of cells in a 2D transmural ventricular model. LQTS2 is realised by reducing the potassium current (IKr) to 0.5 in each cell. Each cell of the tissue is remodelled by increasing the conductance of calcium current (GCaL). The above two factors make the cells prone to early after depolarizations (EADs) development. The rise in GCaL that can develop a sustained TdP at normal pacing rate is determined from this study. A look at the calcium dynamics, sodium-calcium exchanger current (INaCa) and slow delayed rectifier potassium current (IKs) distribution maps of the tissue helps us in analysing the mechanism of TdP generation. RESULTS A TdP type pattern at normal pacing rate is generated when GCaL is more than 3.5 times the control parameter. From the M-cell island, an adequate number of cells spontaneously release calcium from their sarcoplasmic reticulum leading to increased intracellular calcium and inward sodium current through the sodium calcium exchanger current (INaCa). These contribute to the development of EADs which create a depolarising wavefront that triggers TdP in the tissue. When GCaL is less than 3.5 times the control value, premature ventricular complexes (PVC) occur interspersed between normal beats. CONCLUSION Normal pacing rates can induce a multi focal TdP when sufficient number of M-cells simultaneously undergo spontaneous calcium release (SCR) events.
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Affiliation(s)
- Ponnuraj Kirthi Priya
- Biomedical Engineering Group, Department of Applied Mechanics, Indian Institute of Technology Madras, Chennai 600036, India.
| | - M Ramasubba Reddy
- Biomedical Engineering Group, Department of Applied Mechanics, Indian Institute of Technology Madras, Chennai 600036, India.
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54
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Kienast R, Handler M, Stöger M, Baumgarten D, Hanser F, Baumgartner C. Modeling hypothermia induced effects for the heterogeneous ventricular tissue from cellular level to the impact on the ECG. PLoS One 2017; 12:e0182979. [PMID: 28813535 PMCID: PMC5558962 DOI: 10.1371/journal.pone.0182979] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 07/27/2017] [Indexed: 11/18/2022] Open
Abstract
Hypothermia has a profound impact on the electrophysiological mechanisms of the heart. Experimental investigations provide a better understanding of electrophysiological alterations associated with cooling. However, there is a lack of computer models suitable for simulating the effects of hypothermia in cardio-electrophysiology. In this work, we propose a model that describes the cooling-induced electrophysiological alterations in ventricular tissue in a temperature range from 27°C to 37°C. To model the electrophysiological conditions in a 3D left ventricular tissue block it was essential to consider the following anatomical and physiological parameters in the model: the different cell types (endocardial, M, epicardial), the heterogeneous conductivities in longitudinal, transversal and transmural direction depending on the prevailing temperature, the distinct fiber orientations and the transmural repolarization sequences. Cooling-induced alterations on the morphology of the action potential (AP) of single myocardial cells thereby are described by an extension of the selected Bueno-Orovio model for human ventricular tissue using Q10 temperature coefficients. To evaluate alterations on tissue level, the corresponding pseudo electrocardiogram (pECG) was calculated. Simulations show that cooling-induced AP and pECG-related parameters, i.e. AP duration, morphology of the notch of epicardial AP, maximum AP upstroke velocity, AP rise time, QT interval, QRS duration and J wave formation are in good accordance with literature and our experimental data. The proposed model enables us to further enhance our knowledge of cooling-induced electrophysiological alterations from cellular to tissue level in the heart and may help to better understand electrophysiological mechanisms, e.g. in arrhythmias, during hypothermia.
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Affiliation(s)
- Roland Kienast
- Institute of Electrical and Biomedical Engineering, UMIT–University for Health Sciences, Medical Informatics and Technology, Hall, Tyrol, Austria
- * E-mail:
| | - Michael Handler
- Institute of Electrical and Biomedical Engineering, UMIT–University for Health Sciences, Medical Informatics and Technology, Hall, Tyrol, Austria
| | - Markus Stöger
- Institute of Electrical and Biomedical Engineering, UMIT–University for Health Sciences, Medical Informatics and Technology, Hall, Tyrol, Austria
| | - Daniel Baumgarten
- Institute of Electrical and Biomedical Engineering, UMIT–University for Health Sciences, Medical Informatics and Technology, Hall, Tyrol, Austria
- Institute of Biomedical Engineering and Informatics, Technische Universität Ilmenau, Ilmenau, Germany
| | - Friedrich Hanser
- Institute of Electrical and Biomedical Engineering, UMIT–University for Health Sciences, Medical Informatics and Technology, Hall, Tyrol, Austria
| | - Christian Baumgartner
- Institute of Electrical and Biomedical Engineering, UMIT–University for Health Sciences, Medical Informatics and Technology, Hall, Tyrol, Austria
- Institute of Health Care Engineering with European Testing Center of Medical Devices, Graz University of Technology, Graz, Austria
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55
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Zhang X, Liu ZQ, Singh D, Wehner GJ, Powell DK, Campbell KS, Fornwalt BK, Wenk JF. Regional quantification of myocardial mechanics in rat using 3D cine DENSE cardiovascular magnetic resonance. NMR IN BIOMEDICINE 2017; 30:10.1002/nbm.3733. [PMID: 28481037 PMCID: PMC10539034 DOI: 10.1002/nbm.3733] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 03/23/2017] [Accepted: 03/24/2017] [Indexed: 06/07/2023]
Abstract
Rat models have assumed an increasingly important role in cardiac research. However, a detailed profile of regional cardiac mechanics, such as strains and torsion, is lacking for rats. We hypothesized that healthy rat left ventricles (LVs) exhibit regional differences in cardiac mechanics, which are part of normal function. In this study, images of the LV were obtained with 3D cine displacement encoding with stimulated echoes (DENSE) cardiovascular magnetic resonance in 10 healthy rats. To evaluate regional cardiac mechanics, the LV was divided into basal, mid-ventricular, and apical regions. The myocardium at the mid-LV was further partitioned into four wall segments (i.e. septal, inferior, lateral, and anterior) and three transmural layers (i.e. sub-endocardium, mid-myocardium, and sub-epicardium). The six Lagrangian strain components (i.e. Err , Ecc , Ell , Ecl , Erl , and Ecr ) were computed from the 3D displacement field and averaged within each region of interest. Torsion was quantified using the circumferential-longitudinal shear angle. While peak systolic Ecl differed between the mid-ventricle and apex, the other five components of peak systolic strain were similar across the base, mid-ventricle, and apex. In the mid-LV myocardium, Ecc decreased gradually from the sub-endocardial to the sub-epicardial layer. Ell demonstrated significant differences between the four wall segments, with the largest magnitude in the inferior segment. Err was uniform among the four wall segments. Ecl varied along the transmural direction and among wall segments, whereas Erl differed only among the wall segments. Erc was not associated with significant variations. Torsion also varied along the transmural direction and among wall segments. These results provide fundamental insights into the regional contractile function of healthy rat hearts, and form the foundation for future studies on regional changes induced by disease or treatments.
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Affiliation(s)
- Xiaoyan Zhang
- Department of Mechanical Engineering, University of Kentucky, Lexington, KY, USA
| | - Zhan-Qiu Liu
- Department of Mechanical Engineering, University of Kentucky, Lexington, KY, USA
| | - Dara Singh
- Department of Mechanical Engineering, University of Kentucky, Lexington, KY, USA
| | - Gregory J. Wehner
- Department of Biomedical Engineering, University of Kentucky, Lexington, KY, USA
| | - David K. Powell
- Department of Anatomy and Neurobiology, University of Kentucky, Lexington, KY, USA
| | | | - Brandon K. Fornwalt
- Department of Biomedical Engineering, University of Kentucky, Lexington, KY, USA
- Department of Physiology, University of Kentucky, Lexington, KY, USA
- Institute for Advanced Application, Geisinger Health System, Danville, PA
| | - Jonathan F. Wenk
- Department of Mechanical Engineering, University of Kentucky, Lexington, KY, USA
- Department of Surgery, University of Kentucky, Lexington, KY, USA
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Salgado AA, Barbosa PRB, Ferreira AG, Reis CADSS, Terra C. Prognostic Value of a New Marker of Ventricular Repolarization in Cirrhotic Patients. Arq Bras Cardiol 2017; 107:523-531. [PMID: 28558079 PMCID: PMC5210456 DOI: 10.5935/abc.20160181] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2016] [Accepted: 06/08/2016] [Indexed: 01/06/2023] Open
Abstract
Background There is still debate about the relationship between changes in ventricular
repolarization on the surface electrocardiogram and cirrhosis severity. Objective To study the relationship between variables related to ventricular
repolarization and the clinical severity of the cirrhotic disease. Methods We selected 79 individuals with hepatic cirrhosis, classified according to
the Child-Pugh-Turcotte criteria (Child A, B, and C). We measured the QT and
corrected QT (QTc) intervals, and the interval between the peak and the end
of the T wave (TpTe), and we identified their minimum, maximum, and mean
values in the 12-lead electrocardiogram. We also calculated the dispersion
of the QT (DQT) and QTc (DQTc) intervals. Results In 12 months of clinical follow-up, nine subjects underwent hepatic
transplantation (Child A: 0 [0%]; Child B: 6 [23.1%]; Child C: 3 [18.8%]; p
= 0.04) and 12 died (Child A: 3 [12.0%]; Child B: 4 [15.4%]; Child C: 5
[31.3%]; p = 0.002). No significant differences were observed between the
cirrhotic groups related to the minimum, maximum, and mean values for the
QT, QTc, TpTe, DQT, and DQTc intervals. A minimum TpTe interval ≤ 50
ms was a predictor for the composite endpoints of death or liver
transplantation with a sensitivity of 90% and a specificity of 57% (p =
0.005). In the Cox multivariate analysis, the Child groups and a minimum
TpTe of ≤ 50 ms were independent predictors of the composite
endpoints. Conclusion The intervals QT, QTc, DQT, DQTc, and TpTe have similar distributions between
different severity stages in cirrhotic disease. The TpTe interval proved to
be a prognostic marker in subjects with cirrhosis, regardless of disease
severity (NCT01433848).
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Affiliation(s)
- Angelo Antunes Salgado
- Hospital Universitário Pedro Ernesto, Universidade Estadual do Rio de Janeiro, RJ, Brazil
| | | | | | | | - Carlos Terra
- Hospital Universitário Pedro Ernesto, Universidade Estadual do Rio de Janeiro, RJ, Brazil
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57
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Shaabani S, Sadeghian S, Hosseinsabet A. Evaluation of left ventricular longitudinal deformation in patients with and without ST segment depression during supraventricular tachycardia. JOURNAL OF CLINICAL ULTRASOUND : JCU 2017; 45:343-349. [PMID: 28369988 DOI: 10.1002/jcu.22473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2016] [Revised: 01/16/2017] [Accepted: 02/05/2017] [Indexed: 06/07/2023]
Abstract
BACKGROUND The cumulative effect of repeated demand ischemia on left ventricular (LV) systolic function has been previously demonstrated. We evaluated the longitudinal deformation of LV myocardial fibers at systole and diastole using two-dimensional speckle-tracking echocardiography (2DSTE) in patients with and without ST-segment depression during supraventricular tachycardia. METHODS We recruited 104 consecutive patients, who were admitted to our hospital for the ablation of atrioventricular nodal reentrant tachycardia or atrioventricular reentrant tachycardia. The patients were thereafter evaluated by transthoracic echocardiography and 2DSTE, and longitudinal systolic strain and strain rate as well as early and late diastolic strain rates were measured. RESULTS We found no statistically significant differences in longitudinal systolic strain and strain rate as well as in early and late diastolic strain rates between the two study groups. CONCLUSIONS The longitudinal deformation properties of LV muscle fibers were not different between patients with and without ST-segment depression during supraventricular tachycardia. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound 45:343-349, 2017.
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Affiliation(s)
- Sonia Shaabani
- Cardiology Department, Tehran Heart Center, Tehran University of Medical Sciences, Tehran, I.R. Iran
| | - Saeed Sadeghian
- Cardiology Department, Tehran Heart Center, Tehran University of Medical Sciences, Tehran, I.R. Iran
| | - Ali Hosseinsabet
- Cardiology Department, Tehran Heart Center, Tehran University of Medical Sciences, Tehran, I.R. Iran
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58
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Osadchii OE. Role of abnormal repolarization in the mechanism of cardiac arrhythmia. Acta Physiol (Oxf) 2017; 220 Suppl 712:1-71. [PMID: 28707396 DOI: 10.1111/apha.12902] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
In cardiac patients, life-threatening tachyarrhythmia is often precipitated by abnormal changes in ventricular repolarization and refractoriness. Repolarization abnormalities typically evolve as a consequence of impaired function of outward K+ currents in cardiac myocytes, which may be caused by genetic defects or result from various acquired pathophysiological conditions, including electrical remodelling in cardiac disease, ion channel modulation by clinically used pharmacological agents, and systemic electrolyte disorders seen in heart failure, such as hypokalaemia. Cardiac electrical instability attributed to abnormal repolarization relies on the complex interplay between a provocative arrhythmic trigger and vulnerable arrhythmic substrate, with a central role played by the excessive prolongation of ventricular action potential duration, impaired intracellular Ca2+ handling, and slowed impulse conduction. This review outlines the electrical activity of ventricular myocytes in normal conditions and cardiac disease, describes classical electrophysiological mechanisms of cardiac arrhythmia, and provides an update on repolarization-related surrogates currently used to assess arrhythmic propensity, including spatial dispersion of repolarization, activation-repolarization coupling, electrical restitution, TRIaD (triangulation, reverse use dependence, instability, and dispersion), and the electromechanical window. This is followed by a discussion of the mechanisms that account for the dependence of arrhythmic vulnerability on the location of the ventricular pacing site. Finally, the review clarifies the electrophysiological basis for cardiac arrhythmia produced by hypokalaemia, and gives insight into the clinical importance and pathophysiology of drug-induced arrhythmia, with particular focus on class Ia (quinidine, procainamide) and Ic (flecainide) Na+ channel blockers, and class III antiarrhythmic agents that block the delayed rectifier K+ channel (dofetilide).
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Affiliation(s)
- O. E. Osadchii
- Department of Health Science and Technology; University of Aalborg; Aalborg Denmark
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59
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Lee MY. T wave. INTERNATIONAL JOURNAL OF ARRHYTHMIA 2017. [DOI: 10.18501/arrhythmia.2017.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
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60
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Chiamvimonvat N, Chen-Izu Y, Clancy CE, Deschenes I, Dobrev D, Heijman J, Izu L, Qu Z, Ripplinger CM, Vandenberg JI, Weiss JN, Koren G, Banyasz T, Grandi E, Sanguinetti MC, Bers DM, Nerbonne JM. Potassium currents in the heart: functional roles in repolarization, arrhythmia and therapeutics. J Physiol 2017; 595:2229-2252. [PMID: 27808412 DOI: 10.1113/jp272883] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 10/11/2016] [Indexed: 12/19/2022] Open
Abstract
This is the second of the two White Papers from the fourth UC Davis Cardiovascular Symposium Systems Approach to Understanding Cardiac Excitation-Contraction Coupling and Arrhythmias (3-4 March 2016), a biennial event that brings together leading experts in different fields of cardiovascular research. The theme of the 2016 symposium was 'K+ channels and regulation', and the objectives of the conference were severalfold: (1) to identify current knowledge gaps; (2) to understand what may go wrong in the diseased heart and why; (3) to identify possible novel therapeutic targets; and (4) to further the development of systems biology approaches to decipher the molecular mechanisms and treatment of cardiac arrhythmias. The sessions of the Symposium focusing on the functional roles of the cardiac K+ channel in health and disease, as well as K+ channels as therapeutic targets, were contributed by Ye Chen-Izu, Gideon Koren, James Weiss, David Paterson, David Christini, Dobromir Dobrev, Jordi Heijman, Thomas O'Hara, Crystal Ripplinger, Zhilin Qu, Jamie Vandenberg, Colleen Clancy, Isabelle Deschenes, Leighton Izu, Tamas Banyasz, Andras Varro, Heike Wulff, Eleonora Grandi, Michael Sanguinetti, Donald Bers, Jeanne Nerbonne and Nipavan Chiamvimonvat as speakers and panel discussants. This article summarizes state-of-the-art knowledge and controversies on the functional roles of cardiac K+ channels in normal and diseased heart. We endeavour to integrate current knowledge at multiple scales, from the single cell to the whole organ levels, and from both experimental and computational studies.
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Affiliation(s)
- Nipavan Chiamvimonvat
- Department of Internal Medicine, University of California, Davis, Genome and Biomedical Science Facility, Rm 6315, Davis, CA, 95616, USA.,Department of Veterans Affairs, Northern California Health Care System, Mather, CA, 95655, USA
| | - Ye Chen-Izu
- Department of Internal Medicine, University of California, Davis, Genome and Biomedical Science Facility, Rm 6315, Davis, CA, 95616, USA.,Department of Pharmacology, University of California, Davis, Genome and Biomedical Science Facility, Rm 3503, Davis, CA, 95616, USA.,Department of Biomedical Engineering, University of California, Davis, Genome and Biomedical Science Facility, Rm 2303, Davis, CA, 95616, USA
| | - Colleen E Clancy
- Department of Pharmacology, University of California, Davis, Genome and Biomedical Science Facility, Rm 3503, Davis, CA, 95616, USA
| | - Isabelle Deschenes
- Department of Physiology and Biophysics, and Biomedical Engineering, Case Western Reserve University, Cleveland, OH, 44109, USA.,Heart and Vascular Research Center, MetroHealth Medical Center, Cleveland, OH, 44109, USA
| | - Dobromir Dobrev
- Institute of Pharmacology, West German Heart and Vascular Center, University Duisburg-Essen, Hufelandstrasse 55, 45122, Essen, Germany
| | - Jordi Heijman
- Department of Cardiology, Cardiovascular Research Institute Maastricht, Faculty of Health, Medicine, and Life Sciences, Maastricht University, Maastricht, The Netherlands
| | - Leighton Izu
- Department of Pharmacology, University of California, Davis, Genome and Biomedical Science Facility, Rm 3503, Davis, CA, 95616, USA
| | - Zhilin Qu
- Division of Cardiology, Cardiovascular Research Laboratory, David Geffen School of Medicine at UCLA, 3645 MRL, Los Angeles, CA, 90095, USA
| | - Crystal M Ripplinger
- Department of Pharmacology, University of California, Davis, Genome and Biomedical Science Facility, Rm 3503, Davis, CA, 95616, USA
| | - Jamie I Vandenberg
- Victor Chang Cardiac Research Institute, 405 Liverpool Street, Darlinghurst, NSW, 2010, Australia
| | - James N Weiss
- Division of Cardiology, Cardiovascular Research Laboratory, David Geffen School of Medicine at UCLA, 3645 MRL, Los Angeles, CA, 90095, USA
| | - Gideon Koren
- Cardiovascular Research Center, Rhode Island Hospital and the Cardiovascular Institute, The Warren Alpert Medical School of Brown University, Providence, RI, 02903, USA
| | - Tamas Banyasz
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Eleonora Grandi
- Department of Pharmacology, University of California, Davis, Genome and Biomedical Science Facility, Rm 3503, Davis, CA, 95616, USA
| | - Michael C Sanguinetti
- Department of Internal Medicine, University of Utah, Nora Eccles Harrison Cardiovascular Research & Training Institute, Salt Lake City, UT, 84112, USA
| | - Donald M Bers
- Department of Pharmacology, University of California, Davis, Genome and Biomedical Science Facility, Rm 3503, Davis, CA, 95616, USA
| | - Jeanne M Nerbonne
- Departments of Developmental Biology and Internal Medicine, Cardiovascular Division, Washington University Medical School, St Louis, MO, 63110, USA
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Abstract
Cardiac arrhythmias can follow disruption of the normal cellular electrophysiological processes underlying excitable activity and their tissue propagation as coherent wavefronts from the primary sinoatrial node pacemaker, through the atria, conducting structures and ventricular myocardium. These physiological events are driven by interacting, voltage-dependent, processes of activation, inactivation, and recovery in the ion channels present in cardiomyocyte membranes. Generation and conduction of these events are further modulated by intracellular Ca2+ homeostasis, and metabolic and structural change. This review describes experimental studies on murine models for known clinical arrhythmic conditions in which these mechanisms were modified by genetic, physiological, or pharmacological manipulation. These exemplars yielded molecular, physiological, and structural phenotypes often directly translatable to their corresponding clinical conditions, which could be investigated at the molecular, cellular, tissue, organ, and whole animal levels. Arrhythmogenesis could be explored during normal pacing activity, regular stimulation, following imposed extra-stimuli, or during progressively incremented steady pacing frequencies. Arrhythmic substrate was identified with temporal and spatial functional heterogeneities predisposing to reentrant excitation phenomena. These could arise from abnormalities in cardiac pacing function, tissue electrical connectivity, and cellular excitation and recovery. Triggering events during or following recovery from action potential excitation could thereby lead to sustained arrhythmia. These surface membrane processes were modified by alterations in cellular Ca2+ homeostasis and energetics, as well as cellular and tissue structural change. Study of murine systems thus offers major insights into both our understanding of normal cardiac activity and its propagation, and their relationship to mechanisms generating clinical arrhythmias.
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Affiliation(s)
- Christopher L-H Huang
- Physiological Laboratory and the Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
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62
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Krzesiak A, Delpech N, Sebille S, Cognard C, Chatelier A. Structural, Contractile and Electrophysiological Adaptations of Cardiomyocytes to Chronic Exercise. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 999:75-90. [PMID: 29022258 DOI: 10.1007/978-981-10-4307-9_5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Cardiac beneficial effects of chronic exercise is well admitted. These effects mainly studied at the organ and organism integrated levels find their origin in cardiomyocyte adaptation. This chapter try to highlight the main trends of the data related to the different parameters subject to such adaptations. This is addressed through cardiomyocytes size and structure, calcium and contractile properties, and finally electrophysiological alterations induced by training as they transpire from the literature. Despite the clarifications needed to decipher healthy cardiomyocyte remodeling, this overview clearly show that cardiac cell plasticity ensure the cardiac adaptation to exercise training and offers an interesting mean of action to counteract physiological disturbances induced by cardiac pathologies.
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Affiliation(s)
- A Krzesiak
- Equipe Transferts Ioniques et Rythmicité Cardiaque (TIRC), Lab. Signalisation et Transports Ioniques Membranaires (STIM), ERL CNRS/Université de Poitiers n°7368, Faculté des Sciences Fondamentales et Appliquées, Pôle Biologie Santé Bât B36/B37, 1 rue Georges Bonnet TSA 51106, 86073, Poitiers Cedex 9, France.,Laboratoire Mobilité, Vieillissement & Exercice (MOVE) - EA 6314, Faculté des Sciences du Sport Bât C6, 8, allée Jean Monnet, TSA 31113, 86073, Poitiers Cedex 9, France
| | - N Delpech
- Laboratoire Mobilité, Vieillissement & Exercice (MOVE) - EA 6314, Faculté des Sciences du Sport Bât C6, 8, allée Jean Monnet, TSA 31113, 86073, Poitiers Cedex 9, France
| | - S Sebille
- Equipe Transferts Ioniques et Rythmicité Cardiaque (TIRC), Lab. Signalisation et Transports Ioniques Membranaires (STIM), ERL CNRS/Université de Poitiers n°7368, Faculté des Sciences Fondamentales et Appliquées, Pôle Biologie Santé Bât B36/B37, 1 rue Georges Bonnet TSA 51106, 86073, Poitiers Cedex 9, France
| | - C Cognard
- Equipe Transferts Ioniques et Rythmicité Cardiaque (TIRC), Lab. Signalisation et Transports Ioniques Membranaires (STIM), ERL CNRS/Université de Poitiers n°7368, Faculté des Sciences Fondamentales et Appliquées, Pôle Biologie Santé Bât B36/B37, 1 rue Georges Bonnet TSA 51106, 86073, Poitiers Cedex 9, France
| | - A Chatelier
- Equipe Transferts Ioniques et Rythmicité Cardiaque (TIRC), Lab. Signalisation et Transports Ioniques Membranaires (STIM), ERL CNRS/Université de Poitiers n°7368, Faculté des Sciences Fondamentales et Appliquées, Pôle Biologie Santé Bât B36/B37, 1 rue Georges Bonnet TSA 51106, 86073, Poitiers Cedex 9, France.
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63
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LASHEEN NN, MOHAMED GF. Possible Mechanisms of Cardiac Contractile Dysfunction and Electrical Changes in Ammonium Chloride Induced Chronic Metabolic Acidosis in Wistar Rats. Physiol Res 2016; 65:927-940. [DOI: 10.33549/physiolres.933171] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Metabolic acidosis could occur due to either endogenous acids accumulation or bicarbonate loss from the gastrointestinal tract or commonly from the kidney. This study aimed to investigate the possible underlying mechanism(s) of chronic acidosis-induced cardiac contractile and electrical changes in rats. Twenty four adult Wistar rats, of both sexes, were randomly divided into control group and chronic metabolic acidosis group, which received orally 0.28 M NH4Cl in the drinking water for 2 weeks. At the end of experimental period, systolic and diastolic blood pressure values were measured. On the day of sacrifice, rats were anesthetized by i.p. pentobarbitone (40 mg/kg b.w.), transthoracic echocardiography and ECG were performed. Blood samples were obtained from abdominal aorta for complete blood count and determination of pH, bicarbonate, chloride, sodium, potassium, troponin I, CK-MB, IL-6, renin and aldosterone levels. Hearts from both groups were studied for cardiac tissue IL-6 and aldosterone in addition to histopathological examination. Compared to control group, chronic metabolic acidosis group showed anemia, significant systolic and diastolic hypotension accompanied by significant reduction of ejection fraction and fraction of shortening, significant bradycardia, prolonged QTc interval and higher widened T wave as well as significantly elevated plasma levels of renin, aldosterone, troponin I, CK-MB and IL-6, and cardiac tissue aldosterone and IL-6. The left ventricular wall of the acidosis group showed degenerated myocytes with fibrosis and apoptosis. Thus, chronic metabolic acidosis induced negative inotropic and chronotropic effects and cardiomyopathy, possibly by elevated aldosterone and IL-6 levels released from the cardiac tissue.
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Affiliation(s)
- N. N. LASHEEN
- Department of Physiology, Faculty of Medicine, Ain Shams University, Cairo, Egypt
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64
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Hanley CM, Kowey PR. Back to the basics. Heart Rhythm 2016; 14:455-456. [PMID: 27915057 DOI: 10.1016/j.hrthm.2016.11.035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Indexed: 12/01/2022]
Affiliation(s)
- Colleen M Hanley
- Lankenau Heart Institute, Lankenau Medical Center, Wynnewood, Pennsylvania
| | - Peter R Kowey
- Lankenau Heart Institute, Lankenau Medical Center, Wynnewood, Pennsylvania; Lankenau Institute for Medical Research, Lankenau Medical Center, Wynnewood, Pennsylvania.
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65
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Carruth ED, McCulloch AD, Omens JH. Transmural gradients of myocardial structure and mechanics: Implications for fiber stress and strain in pressure overload. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2016; 122:215-226. [PMID: 27845176 DOI: 10.1016/j.pbiomolbio.2016.11.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Although a truly complete understanding of whole heart activation, contraction, and deformation is well beyond our current reach, a significant amount of effort has been devoted to discovering and understanding the mechanisms by which myocardial structure determines cardiac function to better treat patients with cardiac disease. Several experimental studies have shown that transmural fiber strain is relatively uniform in both diastole and systole, in contrast to predictions from traditional mechanical theory. Similarly, mathematical models have largely predicted uniform fiber stress across the wall. The development of this uniform pattern of fiber stress and strain during filling and ejection is due to heterogeneous transmural distributions of several myocardial structures. This review summarizes these transmural gradients, their contributions to fiber mechanics, and the potential functional effects of their remodeling during pressure overload hypertrophy.
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Affiliation(s)
- Eric D Carruth
- Department of Bioengineering, University of California San Diego, La Jolla, CA, USA.
| | - Andrew D McCulloch
- Department of Bioengineering, University of California San Diego, La Jolla, CA, USA.
| | - Jeffrey H Omens
- Department of Bioengineering, University of California San Diego, La Jolla, CA, USA; Department of Medicine, University of California San Diego, La Jolla, CA, USA.
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66
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Mugnai G, Benfari G, Fede A, Rossi A, Chierchia GB, Vassanelli F, Menegatti G, Ribichini FL. Tpeak-to-Tend/QT is an independent predictor of early ventricular arrhythmias and arrhythmic death in anterior ST elevation myocardial infarction patients. EUROPEAN HEART JOURNAL-ACUTE CARDIOVASCULAR CARE 2016; 5:473-480. [DOI: 10.1177/2048872615598616] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2014] [Accepted: 07/12/2015] [Indexed: 11/17/2022]
Affiliation(s)
- Giacomo Mugnai
- Department of Cardiology, University Hospital of Verona, Italy
| | | | - Alfredo Fede
- Department of Cardiology, University Hospital of Verona, Italy
| | - Andrea Rossi
- Department of Cardiology, University Hospital of Verona, Italy
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67
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Pelechas E, Tsigaridas N, Kyrama S, Trogganis S, Kardamis C. Electrocardiographic Manifestations in three Psychiatric patients with Hypothermia - Case Report. Hellenic J Cardiol 2016; 57:S1109-9666(16)30149-X. [PMID: 27780666 DOI: 10.1016/j.hjc.2015.06.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2014] [Accepted: 06/26/2015] [Indexed: 11/30/2022] Open
Abstract
Hypothermia occurs when the core body temperature falls below 35°C, which, in severe cases, can lead to electrocardiographic changes. Several conditions that occur in the psychiatric population increase the risk of hypothermia. This risk can be further increased by the use of several classes of medications such as antipsychotics, beta-adrenergic antagonists and benzodiazepines. We report on three psychiatric patients who were admitted for hypothermia and developed electrocardiographic manifestations (sinus bradycardia, QT prolongation and Osborn waves), which completely resolved after treatment.
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Affiliation(s)
- Eleftherios Pelechas
- Accident and Emergency Department, Scarborough General Hospital, United Kingdom.
| | | | - Sofia Kyrama
- Department of Cardiology, General Hospital of Arta, Greece
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68
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Chen XM, Ji CC, Cheng YJ, Liu LJ, Zhu WQ, Huang Y, Chen WY, Wu SH. The Role of the Ratio of J-Point Elevation Magnitude and R-Wave Amplitude on the Same ECG Lead in the Risk Stratification of Subjects With Early Repolarization Pattern. Clin Cardiol 2016; 39:678-683. [PMID: 27599368 DOI: 10.1002/clc.22587] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Revised: 07/28/2016] [Accepted: 07/31/2016] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Just as high-risk populations for cardiac arrest exist in patients with Brugada syndrome or long QT syndrome, high-risk and low-risk populations for cardiac arrest also exist in patients with early repolarization pattern (ERP). HYPOTHESIS Electrocardiographic (ECG) characteristics can aid the risk stratification of patients with ERP. METHODS Electrocardiographic parameters such as magnitude of J-point elevation and J/R ratio were measured. The magnitude of J-point elevation, leads with J points elevated, J/R ratio, morphology of the ST segment, and QT/QTc interval were used in comparative analysis in 2 groups: 57 patients with ERP and cardiac arrest (cardiac arrest group) and 100 patients with ERP but without cardiac arrest (control group). RESULTS There was no statistical difference in clinical characteristics of the 2 groups. The J/R ratio in the cardiac arrest group was significantly higher than in the control group (26.8% ± 18.1% vs 16.3% ± 10.3%, respectively; P < 0.001) and the proportion of horizontal/descending ST segments (70.2%) was significantly higher than in the control group (29.0%), but the proportion of ascending/upsloping ST segments (29.8%) was significantly lower than in the control group (71.0%; P < 0.001). Multivariate logistic regression revealed that higher J/R ratio and horizontal/descending ST segment were independently associated with increased risk of cardiac arrest in patients with ERP. CONCLUSIONS In patients with ERP and cardiac arrest, J/R ratios were relatively higher and mostly with horizontal/descending ST segments, suggesting that J/R ratio and ST-segment morphology may be used as indicators for risk stratification in patients with ERP.
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Affiliation(s)
- Xu-Miao Chen
- Department of Cardiology, the First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China
| | - Cheng-Cheng Ji
- Department of Cardiology, the First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China
| | - Yun-Jiu Cheng
- Department of Cardiology, the First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China
| | - Li-Juan Liu
- Department of Cardiology, the First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China
| | - Wei-Qi Zhu
- Department of Cardiology, the First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China
| | - Ying Huang
- Department of Cardiology, the First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China
| | - Wei-Ying Chen
- Department of Cardiology, the First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China
| | - Su-Hua Wu
- Department of Cardiology, the First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China
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69
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Alonso S, Bär M, Echebarria B. Nonlinear physics of electrical wave propagation in the heart: a review. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2016; 79:096601. [PMID: 27517161 DOI: 10.1088/0034-4885/79/9/096601] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The beating of the heart is a synchronized contraction of muscle cells (myocytes) that is triggered by a periodic sequence of electrical waves (action potentials) originating in the sino-atrial node and propagating over the atria and the ventricles. Cardiac arrhythmias like atrial and ventricular fibrillation (AF,VF) or ventricular tachycardia (VT) are caused by disruptions and instabilities of these electrical excitations, that lead to the emergence of rotating waves (VT) and turbulent wave patterns (AF,VF). Numerous simulation and experimental studies during the last 20 years have addressed these topics. In this review we focus on the nonlinear dynamics of wave propagation in the heart with an emphasis on the theory of pulses, spirals and scroll waves and their instabilities in excitable media with applications to cardiac modeling. After an introduction into electrophysiological models for action potential propagation, the modeling and analysis of spatiotemporal alternans, spiral and scroll meandering, spiral breakup and scroll wave instabilities like negative line tension and sproing are reviewed in depth and discussed with emphasis on their impact for cardiac arrhythmias.
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Affiliation(s)
- Sergio Alonso
- Physikalisch-Technische Bundesanstalt, Abbestr. 2-12 10587, Berlin, Germany. Department of Physics, Universitat Politècnica de Catalunya, Av. Dr. Marañón 44, E-08028 Barcelona, Spain
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70
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Srinivasan NT, Orini M, Simon RB, Providência R, Khan FZ, Segal OR, Babu GG, Bradley R, Rowland E, Ahsan S, Chow AW, Lowe MD, Taggart P, Lambiase PD. Ventricular stimulus site influences dynamic dispersion of repolarization in the intact human heart. Am J Physiol Heart Circ Physiol 2016; 311:H545-54. [PMID: 27371682 PMCID: PMC5142177 DOI: 10.1152/ajpheart.00159.2016] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Accepted: 06/29/2016] [Indexed: 12/18/2022]
Abstract
Spatial variation of restitution in relation to varying stimulus site is poorly defined in the intact human heart. Repolarization gradients were shown to be dependent on site of activation with epicardial stimulation promoting significant transmural gradients. Steep restitution slopes were predominant in the normal ventricle. The spatial variation in restitution properties in relation to varying stimulus site is poorly defined. This study aimed to investigate the effect of varying stimulus site on apicobasal and transmural activation time (AT), action potential duration (APD) and repolarization time (RT) during restitution studies in the intact human heart. Ten patients with structurally normal hearts, undergoing clinical electrophysiology studies, were enrolled. Decapolar catheters were placed apex to base in the endocardial right ventricle (RVendo) and left ventricle (LVendo), and an LV branch of the coronary sinus (LVepi) for transmural recording. S1–S2 restitution protocols were performed pacing RVendo apex, LVendo base, and LVepi base. Overall, 725 restitution curves were analyzed, 74% of slopes had a maximum slope of activation recovery interval (ARI) restitution (Smax) > 1 (P < 0.001); mean Smax = 1.76. APD was shorter in the LVepi compared with LVendo, regardless of pacing site (30-ms difference during RVendo pacing, 25-ms during LVendo, and 48-ms during LVepi; 50th quantile, P < 0.01). Basal LVepi pacing resulted in a significant transmural gradient of RT (77 ms, 50th quantile: P < 0.01), due to loss of negative transmural AT-APD coupling (mean slope 0.63 ± 0.3). No significant transmural gradient in RT was demonstrated during endocardial RV or LV pacing, with preserved negative transmural AT-APD coupling (mean slope −1.36 ± 1.9 and −0.71 ± 0.4, respectively). Steep ARI restitution slopes predominate in the normal ventricle and dynamic ARI; RT gradients exist that are modulated by the site of activation. Epicardial stimulation to initiate ventricular activation promotes significant transmural gradients of repolarization that could be proarrhythmic.
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Affiliation(s)
- Neil T Srinivasan
- Department of Cardiac Electrophysiology, The Barts Heart Center, St Bartholomew's Hospital, London, United Kingdom; and Institute of Cardiovascular Science, University College London, London, United Kingdom
| | - Michele Orini
- Department of Cardiac Electrophysiology, The Barts Heart Center, St Bartholomew's Hospital, London, United Kingdom; and Institute of Cardiovascular Science, University College London, London, United Kingdom
| | - Ron B Simon
- Department of Cardiac Electrophysiology, The Barts Heart Center, St Bartholomew's Hospital, London, United Kingdom; and
| | - Rui Providência
- Department of Cardiac Electrophysiology, The Barts Heart Center, St Bartholomew's Hospital, London, United Kingdom; and
| | - Fakhar Z Khan
- Department of Cardiac Electrophysiology, The Barts Heart Center, St Bartholomew's Hospital, London, United Kingdom; and
| | - Oliver R Segal
- Department of Cardiac Electrophysiology, The Barts Heart Center, St Bartholomew's Hospital, London, United Kingdom; and
| | - Girish G Babu
- Department of Cardiac Electrophysiology, The Barts Heart Center, St Bartholomew's Hospital, London, United Kingdom; and
| | - Richard Bradley
- Department of Cardiac Electrophysiology, The Barts Heart Center, St Bartholomew's Hospital, London, United Kingdom; and
| | - Edward Rowland
- Department of Cardiac Electrophysiology, The Barts Heart Center, St Bartholomew's Hospital, London, United Kingdom; and
| | - Syed Ahsan
- Department of Cardiac Electrophysiology, The Barts Heart Center, St Bartholomew's Hospital, London, United Kingdom; and
| | - Anthony W Chow
- Department of Cardiac Electrophysiology, The Barts Heart Center, St Bartholomew's Hospital, London, United Kingdom; and
| | - Martin D Lowe
- Department of Cardiac Electrophysiology, The Barts Heart Center, St Bartholomew's Hospital, London, United Kingdom; and
| | - Peter Taggart
- Institute of Cardiovascular Science, University College London, London, United Kingdom
| | - Pier D Lambiase
- Department of Cardiac Electrophysiology, The Barts Heart Center, St Bartholomew's Hospital, London, United Kingdom; and Institute of Cardiovascular Science, University College London, London, United Kingdom
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71
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Habecker BA, Anderson ME, Birren SJ, Fukuda K, Herring N, Hoover DB, Kanazawa H, Paterson DJ, Ripplinger CM. Molecular and cellular neurocardiology: development, and cellular and molecular adaptations to heart disease. J Physiol 2016; 594:3853-75. [PMID: 27060296 DOI: 10.1113/jp271840] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 03/15/2016] [Indexed: 12/12/2022] Open
Abstract
The nervous system and cardiovascular system develop in concert and are functionally interconnected in both health and disease. This white paper focuses on the cellular and molecular mechanisms that underlie neural-cardiac interactions during development, during normal physiological function in the mature system, and during pathological remodelling in cardiovascular disease. The content on each subject was contributed by experts, and we hope that this will provide a useful resource for newcomers to neurocardiology as well as aficionados.
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Affiliation(s)
- Beth A Habecker
- Department of Physiology and Pharmacology, Department of Medicine Division of Cardiovascular Medicine and Knight Cardiovascular Institute, Oregon Health and Science University, Portland, OR, 97239, USA
| | - Mark E Anderson
- Johns Hopkins Department of Medicine, Johns Hopkins School of Medicine, Baltimore, MD, 21287, USA
| | - Susan J Birren
- Department of Biology, Volen Center for Complex Systems, Brandeis University, Waltham, MA, 02453, USA
| | - Keiichi Fukuda
- Department of Cardiology, Keio University School of Medicine, 35-Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan
| | - Neil Herring
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
| | - Donald B Hoover
- Department of Biomedical Sciences, Center of Excellence in Inflammation, Infectious Disease and Immunity, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN, 37614, USA
| | - Hideaki Kanazawa
- Department of Cardiology, Keio University School of Medicine, 35-Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan
| | - David J Paterson
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
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Gardner RT, Ripplinger CM, Myles RC, Habecker BA. Molecular Mechanisms of Sympathetic Remodeling and Arrhythmias. Circ Arrhythm Electrophysiol 2016; 9:e001359. [PMID: 26810594 DOI: 10.1161/circep.115.001359] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Ryan T Gardner
- From the Department of Physiology and Pharmacology and Knight Cardiovascular Institute, Oregon Health and Science University, Portland (R.T.G., B.A.H.); Department of Pharmacology, School of Medicine, University of California, Davis (C.M.R.); and Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, United Kingdom (R.C.M.)
| | - Crystal M Ripplinger
- From the Department of Physiology and Pharmacology and Knight Cardiovascular Institute, Oregon Health and Science University, Portland (R.T.G., B.A.H.); Department of Pharmacology, School of Medicine, University of California, Davis (C.M.R.); and Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, United Kingdom (R.C.M.)
| | - Rachel C Myles
- From the Department of Physiology and Pharmacology and Knight Cardiovascular Institute, Oregon Health and Science University, Portland (R.T.G., B.A.H.); Department of Pharmacology, School of Medicine, University of California, Davis (C.M.R.); and Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, United Kingdom (R.C.M.)
| | - Beth A Habecker
- From the Department of Physiology and Pharmacology and Knight Cardiovascular Institute, Oregon Health and Science University, Portland (R.T.G., B.A.H.); Department of Pharmacology, School of Medicine, University of California, Davis (C.M.R.); and Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, United Kingdom (R.C.M.).
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Krummen DE, Ho G, Villongco CT, Hayase J, Schricker AA. Ventricular fibrillation: triggers, mechanisms and therapies. Future Cardiol 2016; 12:373-90. [PMID: 27120223 DOI: 10.2217/fca-2016-0001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Ventricular fibrillation (VF) is a common, life-threatening arrhythmia responsible for significant morbidity and mortality. Due to challenges in safely mapping VF, a comprehensive understanding of its mechanisms remains elusive. Recent findings have provided new insights into mechanisms that sustain early VF. Notably, the central role of electrical rotors and catheter-based ablation of VF rotor substrate have been recently reported. In this article, we will review data regarding four stages of VF: initiation, transition, maintenance and evolution. We will discuss the particular mechanisms for each stage and therapies targeting these mechanisms. We also examine inherited arrhythmia syndromes, including the mechanisms and therapies specific to each. We hope that the overview of VF outlined in this work will assist other investigators in designing future therapies to interrupt this life-threatening arrhythmia.
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Affiliation(s)
- David E Krummen
- Department of Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA.,Department of Medicine, VA San Diego Healthcare System, 3350 La Jolla Village Drive, San Diego, CA 92161, USA
| | - Gordon Ho
- Department of Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA.,Department of Medicine, VA San Diego Healthcare System, 3350 La Jolla Village Drive, San Diego, CA 92161, USA
| | - Christopher T Villongco
- Department of Bioengineering, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Justin Hayase
- Department of Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA.,Department of Medicine, VA San Diego Healthcare System, 3350 La Jolla Village Drive, San Diego, CA 92161, USA
| | - Amir A Schricker
- Department of Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA.,Department of Medicine, VA San Diego Healthcare System, 3350 La Jolla Village Drive, San Diego, CA 92161, USA
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74
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Diesel Exhaust Worsens Cardiac Conduction Instability in Dobutamine-Challenged Wistar–Kyoto and Spontaneously Hypertensive Rats. Cardiovasc Toxicol 2016; 17:120-129. [DOI: 10.1007/s12012-016-9363-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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75
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Madhvani RV, Angelini M, Xie Y, Pantazis A, Suriany S, Borgstrom NP, Garfinkel A, Qu Z, Weiss JN, Olcese R. Targeting the late component of the cardiac L-type Ca2+ current to suppress early afterdepolarizations. ACTA ACUST UNITED AC 2016; 145:395-404. [PMID: 25918358 PMCID: PMC4411259 DOI: 10.1085/jgp.201411288] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Early afterdepolarizations (EADs) associated with prolongation of the cardiac action potential (AP) can create heterogeneity of repolarization and premature extrasystoles, triggering focal and reentrant arrhythmias. Because the L-type Ca(2+) current (ICa,L) plays a key role in both AP prolongation and EAD formation, L-type Ca(2+) channels (LTCCs) represent a promising therapeutic target to normalize AP duration (APD) and suppress EADs and their arrhythmogenic consequences. We used the dynamic-clamp technique to systematically explore how the biophysical properties of LTCCs could be modified to normalize APD and suppress EADs without impairing excitation-contraction coupling. Isolated rabbit ventricular myocytes were first exposed to H2O2 or moderate hypokalemia to induce EADs, after which their endogenous ICa,L was replaced by a virtual ICa,L with tunable parameters, in dynamic-clamp mode. We probed the sensitivity of EADs to changes in the (a) amplitude of the noninactivating pedestal current; (b) slope of voltage-dependent activation; (c) slope of voltage-dependent inactivation; (d) time constant of voltage-dependent activation; and (e) time constant of voltage-dependent inactivation. We found that reducing the amplitude of the noninactivating pedestal component of ICa,L effectively suppressed both H2O2- and hypokalemia-induced EADs and restored APD. These results, together with our previous work, demonstrate the potential of this hybrid experimental-computational approach to guide drug discovery or gene therapy strategies by identifying and targeting selective properties of LTCC.
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Affiliation(s)
- Roshni V Madhvani
- Division of Molecular Medicine, Department of Anesthesiology, Department of Medicine (Cardiology), Department of Physiology, Department of Integrative Biology and Physiology, Cardiovascular Research Laboratory, and Brain Research Institute, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA 90095
| | - Marina Angelini
- Division of Molecular Medicine, Department of Anesthesiology, Department of Medicine (Cardiology), Department of Physiology, Department of Integrative Biology and Physiology, Cardiovascular Research Laboratory, and Brain Research Institute, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA 90095
| | - Yuanfang Xie
- Department of Pharmacology, University of California, Davis, Davis, CA 95616
| | - Antonios Pantazis
- Division of Molecular Medicine, Department of Anesthesiology, Department of Medicine (Cardiology), Department of Physiology, Department of Integrative Biology and Physiology, Cardiovascular Research Laboratory, and Brain Research Institute, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA 90095
| | - Silvie Suriany
- Division of Molecular Medicine, Department of Anesthesiology, Department of Medicine (Cardiology), Department of Physiology, Department of Integrative Biology and Physiology, Cardiovascular Research Laboratory, and Brain Research Institute, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA 90095
| | - Nils P Borgstrom
- Division of Molecular Medicine, Department of Anesthesiology, Department of Medicine (Cardiology), Department of Physiology, Department of Integrative Biology and Physiology, Cardiovascular Research Laboratory, and Brain Research Institute, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA 90095
| | - Alan Garfinkel
- Division of Molecular Medicine, Department of Anesthesiology, Department of Medicine (Cardiology), Department of Physiology, Department of Integrative Biology and Physiology, Cardiovascular Research Laboratory, and Brain Research Institute, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA 90095 Division of Molecular Medicine, Department of Anesthesiology, Department of Medicine (Cardiology), Department of Physiology, Department of Integrative Biology and Physiology, Cardiovascular Research Laboratory, and Brain Research Institute, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA 90095 Division of Molecular Medicine, Department of Anesthesiology, Department of Medicine (Cardiology), Department of Physiology, Department of Integrative Biology and Physiology, Cardiovascular Research Laboratory, and Brain Research Institute, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA 90095
| | - Zhilin Qu
- Division of Molecular Medicine, Department of Anesthesiology, Department of Medicine (Cardiology), Department of Physiology, Department of Integrative Biology and Physiology, Cardiovascular Research Laboratory, and Brain Research Institute, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA 90095 Division of Molecular Medicine, Department of Anesthesiology, Department of Medicine (Cardiology), Department of Physiology, Department of Integrative Biology and Physiology, Cardiovascular Research Laboratory, and Brain Research Institute, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA 90095
| | - James N Weiss
- Division of Molecular Medicine, Department of Anesthesiology, Department of Medicine (Cardiology), Department of Physiology, Department of Integrative Biology and Physiology, Cardiovascular Research Laboratory, and Brain Research Institute, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA 90095 Division of Molecular Medicine, Department of Anesthesiology, Department of Medicine (Cardiology), Department of Physiology, Department of Integrative Biology and Physiology, Cardiovascular Research Laboratory, and Brain Research Institute, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA 90095 Division of Molecular Medicine, Department of Anesthesiology, Department of Medicine (Cardiology), Department of Physiology, Department of Integrative Biology and Physiology, Cardiovascular Research Laboratory, and Brain Research Institute, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA 90095
| | - Riccardo Olcese
- Division of Molecular Medicine, Department of Anesthesiology, Department of Medicine (Cardiology), Department of Physiology, Department of Integrative Biology and Physiology, Cardiovascular Research Laboratory, and Brain Research Institute, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA 90095 Division of Molecular Medicine, Department of Anesthesiology, Department of Medicine (Cardiology), Department of Physiology, Department of Integrative Biology and Physiology, Cardiovascular Research Laboratory, and Brain Research Institute, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA 90095 Division of Molecular Medicine, Department of Anesthesiology, Department of Medicine (Cardiology), Department of Physiology, Department of Integrative Biology and Physiology, Cardiovascular Research Laboratory, and Brain Research Institute, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA 90095 Division of Molecular Medicine, Department of Anesthesiology, Department of Medicine (Cardiology), Department of Physiology, Department of Integrative Biology and Physiology, Cardiovascular Research Laboratory, and Brain Research Institute, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA 90095
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Antzelevitch C, Patocskai B. Brugada Syndrome: Clinical, Genetic, Molecular, Cellular, and Ionic Aspects. Curr Probl Cardiol 2016; 41:7-57. [PMID: 26671757 PMCID: PMC4737702 DOI: 10.1016/j.cpcardiol.2015.06.002] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Brugada syndrome (BrS) is an inherited cardiac arrhythmia syndrome first described as a new clinical entity in 1992. Electrocardiographically characterized by distinct coved type ST segment elevation in the right-precordial leads, the syndrome is associated with a high risk for sudden cardiac death in young adults, and less frequently in infants and children. The electrocardiographic manifestations of BrS are often concealed and may be unmasked or aggravated by sodium channel blockers, a febrile state, vagotonic agents, as well as by tricyclic and tetracyclic antidepressants. An implantable cardioverter defibrillator is the most widely accepted approach to therapy. Pharmacologic therapy is designed to produce an inward shift in the balance of currents active during the early phases of the right ventricular action potential (AP) and can be used to abort electrical storms or as an adjunct or alternative to device therapy when use of an implantable cardioverter defibrillator is not possible. Isoproterenol, cilostazol, and milrinone boost calcium channel current and drugs like quinidine, bepridil, and the Chinese herb extract Wenxin Keli inhibit the transient outward current, acting to diminish the AP notch and thus to suppress the substrate and trigger for ventricular tachycardia or fibrillation. Radiofrequency ablation of the right ventricular outflow tract epicardium of patients with BrS has recently been shown to reduce arrhythmia vulnerability and the electrocardiographic manifestation of the disease, presumably by destroying the cells with more prominent AP notch. This review provides an overview of the clinical, genetic, molecular, and cellular aspects of BrS as well as the approach to therapy.
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Affiliation(s)
| | - Bence Patocskai
- Masonic Medical Research Laboratory, Utica, NY 13501
- Department of Pharmacology & Pharmacotherapy, University of Szeged, Szeged, Hungary
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77
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A Computational Study of the Factors Influencing the PVC-Triggering Ability of a Cluster of Early Afterdepolarization-Capable Myocytes. PLoS One 2015; 10:e0144979. [PMID: 26675670 PMCID: PMC4682961 DOI: 10.1371/journal.pone.0144979] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Accepted: 11/25/2015] [Indexed: 12/02/2022] Open
Abstract
Premature ventricular complexes (PVCs), which are abnormal impulse propagations in cardiac tissue, can develop because of various reasons including early afterdepolarizations (EADs). We show how a cluster of EAD-generating cells (EAD clump) can lead to PVCs in a model of cardiac tissue, and also investigate the factors that assist such clumps in triggering PVCs. In particular, we study, through computer simulations, the effects of the following factors on the PVC-triggering ability of an EAD clump: (1) the repolarization reserve (RR) of the EAD cells; (2) the size of the EAD clump; (3) the coupling strength between the EAD cells in the clump; and (4) the presence of fibroblasts in the EAD clump. We find that, although a low value of RR is necessary to generate EADs and hence PVCs, a very low value of RR leads to low-amplitude EAD oscillations that decay with time and do not lead to PVCs. We demonstrate that a certain threshold size of the EAD clump, or a reduction in the coupling strength between the EAD cells, in the clump, is required to trigger PVCs. We illustrate how randomly distributed inexcitable obstacles, which we use to model collagen deposits, affect PVC-triggering by an EAD clump. We show that the gap-junctional coupling of fibroblasts with myocytes can either assist or impede the PVC-triggering ability of an EAD clump, depending on the resting membrane potential of the fibroblasts and the coupling strength between the myocyte and fibroblasts. We also find that the triggering of PVCs by an EAD clump depends sensitively on factors like the pacing cycle length and the distribution pattern of the fibroblasts.
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78
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Holmes JW, Laksman Z, Gepstein L. Making better scar: Emerging approaches for modifying mechanical and electrical properties following infarction and ablation. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2015; 120:134-48. [PMID: 26615948 DOI: 10.1016/j.pbiomolbio.2015.11.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Revised: 11/13/2015] [Accepted: 11/20/2015] [Indexed: 12/31/2022]
Abstract
Following myocardial infarction (MI), damaged myocytes are replaced by collagenous scar tissue, which serves an important mechanical function - maintaining integrity of the heart wall against enormous mechanical forces - but also disrupts electrical function as structural and electrical remodeling in the infarct and borderzone predispose to re-entry and ventricular tachycardia. Novel emerging regenerative approaches aim to replace this scar tissue with viable myocytes. Yet an alternative strategy of therapeutically modifying selected scar properties may also prove important, and in some cases may offer similar benefits with lower risk or regulatory complexity. Here, we review potential goals for such modifications as well as recent proof-of-concept studies employing specific modifications, including gene therapy to locally increase conduction velocity or prolong the refractory period in and around the infarct scar, and modification of scar anisotropy to improve regional mechanics and pump function. Another advantage of scar modification techniques is that they have applications well beyond MI. In particular, ablation treats electrical abnormalities of the heart by intentionally generating scar to block aberrant conduction pathways. Yet in diseases such as atrial fibrillation (AF) where ablation can be extensive, treating the electrical disorder can significantly impair mechanical function. Creating smaller, denser scars that more effectively block conduction, and choosing the location of those lesions by balancing their electrical and mechanical impacts, could significantly improve outcomes for AF patients. We review some recent advances in this area, including the use of computational models to predict the mechanical effects of specific lesion sets and gene therapy for functional ablation. Overall, emerging techniques for modifying scar properties represents a potentially important set of tools for improving patient outcomes across a range of heart diseases, whether used in place of or as an adjunct to regenerative approaches.
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Affiliation(s)
- Jeffrey W Holmes
- Departments of Biomedical Engineering and Medicine, Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, VA, United States.
| | - Zachary Laksman
- Cardiac Electrophysiology, University of British Columbia, Vancouver, BC, Canada
| | - Lior Gepstein
- Departments of Cardiology (Ramban Health Care Campus) and Physiology, The Rappaport Faculty of Medicine and Research Institute, Technion - Israel Institute of Technology, Haifa, Israel
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79
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Baek YS, Park SD, Lee MJ, Kwon SW, Shin SH, Woo SI, Kwan J, Kim DH. Relationship between J Waves and Vagal Activity in Patients Who Do Not Have Structural Heart Disease. Ann Noninvasive Electrocardiol 2015; 20:464-73. [PMID: 26417868 DOI: 10.1111/anec.12302] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
BACKGROUND J waves are associated with increased vagal activity in patients with idiopathic ventricular fibrillation in several studies to date. However, the relationship between J waves and autonomic nervous activity in patients without structural heart disease remains under investigation. We investigated whether the presence of a J wave on the surface electrocardiogram (ECG) was related to increased vagal activity in patients without structural heart disease. METHODS This retrospective study included 684 patients without structural heart disease who had undergone Holter ECG and surface ECG monitoring. Based on the presence of J waves on the surface ECG, patients were divided into two groups: those with J waves (group 1) and those without J waves (group 2). We compared heart rate variability (HRV), reflecting autonomic nervous activity, using 24-h Holter ECG between the groups. RESULTS J waves were present in 92 (13.4%) patients. Heart rate (HR) in group 1 was significantly lesser than that in group 2 (P = 0.031). The ratio of low-frequency (LF) components to high-frequency (HF) components (LF/HF) in group 1 was significantly lower than that in group 2 (P = 0.001). The square root of the mean squared differences of successive NN intervals in group 1 was also significantly higher than that in group 2 (P = 0.047). In a multivariate regression analysis, male sex, HR, and LF/HF ratio remained independent determinants for the presence of J waves (P = 0.039, P = 0.036, and P < 0.001, respectively). CONCLUSION In patients without structural heart disease, the presence of a J wave was associated with a slow HR, male sex, and increased vagal activity, independently.
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Affiliation(s)
- Yong-Soo Baek
- Division of Cardiology, Inha University Hospital, Incheon, South Korea
| | - Sang-Don Park
- Division of Cardiology, Inha University Hospital, Incheon, South Korea
| | - Man-Jong Lee
- Division of Cardiology, Inha University Hospital, Incheon, South Korea
| | - Sung-Woo Kwon
- Division of Cardiology, Inha University Hospital, Incheon, South Korea
| | - Sung-Hee Shin
- Division of Cardiology, Inha University Hospital, Incheon, South Korea
| | - Sung-Il Woo
- Division of Cardiology, Inha University Hospital, Incheon, South Korea
| | - Jun Kwan
- Division of Cardiology, Inha University Hospital, Incheon, South Korea
| | - Dae-Hyeok Kim
- Division of Cardiology, Inha University Hospital, Incheon, South Korea
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80
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The Osborn wave: what have we learned? Herz 2015; 41:48-56. [DOI: 10.1007/s00059-015-4338-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2015] [Revised: 06/22/2015] [Accepted: 06/29/2015] [Indexed: 11/28/2022]
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81
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Tan VH, Duff H, Gerull B, Sumner G. Early repolarization syndrome: A case report focusing on dynamic electrocardiographic changes before ventricular arrhythmias and genetic analysis. HeartRhythm Case Rep 2015; 1:213-216. [PMID: 28491551 PMCID: PMC5419330 DOI: 10.1016/j.hrcr.2015.03.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Affiliation(s)
- Vern Hsen Tan
- Department of Cardiac Sciences, Libin Cardiovascular Institute of Alberta, University of Calgary, Alberta, Canada
- Cardiology Department, Changi General Hospital, Singapore
| | - Henry Duff
- Department of Cardiac Sciences, Libin Cardiovascular Institute of Alberta, University of Calgary, Alberta, Canada
- Cardiology Department, Changi General Hospital, Singapore
| | - Brenda Gerull
- Department of Cardiac Sciences, Libin Cardiovascular Institute of Alberta, University of Calgary, Alberta, Canada
| | - Glen Sumner
- Department of Cardiac Sciences, Libin Cardiovascular Institute of Alberta, University of Calgary, Alberta, Canada
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82
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Prolonged right ventricular ejection delay identifies high risk patients and gender differences in Brugada syndrome. Int J Cardiol 2015; 191:90-6. [DOI: 10.1016/j.ijcard.2015.04.243] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2014] [Revised: 04/06/2015] [Accepted: 04/30/2015] [Indexed: 01/21/2023]
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Abstract
Optimal cardiac function depends on proper timing of excitation and contraction in various regions of the heart, as well as on appropriate heart rate. This is accomplished via specialized electrical properties of various components of the system, including the sinoatrial node, atria, atrioventricular node, His-Purkinje system, and ventricles. Here we review the major regionally determined electrical properties of these cardiac regions and present the available data regarding the molecular and ionic bases of regional cardiac function and dysfunction. Understanding these differences is of fundamental importance for the investigation of arrhythmia mechanisms and pharmacotherapy.
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Affiliation(s)
- Daniel C Bartos
- Department of Pharmacology, University of California Davis, Davis, California, USA
| | - Eleonora Grandi
- Department of Pharmacology, University of California Davis, Davis, California, USA
| | - Crystal M Ripplinger
- Department of Pharmacology, University of California Davis, Davis, California, USA
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84
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Joukar S, Asadipour H. Evaluation of Melissa officinalis (Lemon Balm) Effects on Heart Electrical System. Res Cardiovasc Med 2015; 4:e27013. [PMID: 26396973 PMCID: PMC4576163 DOI: 10.5812/cardiovascmed.4(2)2015.27013] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Revised: 03/05/2015] [Accepted: 03/11/2015] [Indexed: 11/19/2022] Open
Abstract
Background: Melissa officinalis, an herbal drug, is well known and frequently applied in traditional and modern medicine. Yet, there is inadequate information regarding its effects on electrical properties of the heart. The present study attempted to elucidate the effects of Melissa officinalis aqueous extract on electrocardiogram (ECG) in rat. Objectives: ECG is an easy, fast and valuable tool to evaluate the safety of used materials and drugs on heart electrical and conductivity properties. Many drugs with no cardiovascular indication or any overt cardiovascular effects of therapeutic dosing become cardiotoxic when overdosed (16). On the other hand, there are numerous substances and drugs that can cause ECG changes, even in patients without a history of cardiac disease. Therefore, this study was conducted to elucidate safety and outcome of one-week administration of M. officinalis aqueous extract on blood pressure and ECG parameters of rats. Materials and Methods: Four animal groups received tap water (control group), aqueous extracts of Melissa officinalis 50 (M50), 100 (M100) and 200 (M200) mg/kg/day, respectively and orally for a week. ECG and blood pressure were recorded on the eighth day of experiment. Results: Consumption of Melissa officinalis extract associated with prolonged QRS interval (P < 0.05 for M50 and M100 groups and P < 0.01 for M200 group versus the control group, respectively), prolonged QTc and JT intervals (P < 0.01 for different M groups versus the control group) and prolonged TpTe interval (P < 0.001 when M groups compared with the control group) of ECG. However, different doses of the extract had no significant effect on RR interval, PR interval, amplitudes of ECG waves, heart rate and blood pressure. Conclusions: For the first time, this study revealed that consumption of Melissa officinalis extract is associated with significant ECG alterations in rat. Future studies are necessary to determine potential clinical outcomes.
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Affiliation(s)
- Siyavash Joukar
- Physiology Research Center, Institute of Neuropharmacology, Kerman University of Medical Sciences, Kerman, IR Iran
- Department of Physiology and Pharmacology, School of Medicine, Kerman University of Medical Sciences, Kerman, IR Iran
- Corresponding author: Siyavash Joukar, Physiology Research Center, Institute of Neuropharmacology, Kerman University of Medical Sciences, P. O. Box: 7616914115, Kerman, IR Iran. Tel/Fax: +98-3413220081, E-mail: ,
| | - Haleh Asadipour
- Department of Physiology and Pharmacology, School of Medicine, Kerman University of Medical Sciences, Kerman, IR Iran
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85
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Patocskai B, Antzelevitch C. Novel Therapeutic Strategies for the Management of Ventricular Arrhythmias Associated with the Brugada Syndrome. Expert Opin Orphan Drugs 2015; 3:633-651. [PMID: 27559494 PMCID: PMC4993532 DOI: 10.1517/21678707.2015.1037280] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
INTRODUCTION Brugada syndrome (BrS) is an inherited cardiac arrhythmia syndrome characterized by prominent J waves appearing as distinct coved type ST segment elevation in the right precordial leads of the ECG. It is associated with a high risk for sudden cardiac death. AREAS COVERED We discuss 1) ECG manifestations of BrS which can be unmasked or aggravated by sodium channel blockers, febrile states, vagotonic agents, as well as tricyclic and tetracyclic antidepressants; 2) Genetic basis of BrS; 3) Ionic and cellular mechanisms underlying BrS; 4) Therapy involving devices including an implantable cardioverter defibrillator (ICD); 5) Therapy involving radiofrequency ablation; and 6) Therapy involving pharmacological therapy which is aimed at producing an inward shift in the balance of the currents active during phase 1 of the right ventricular action potential either by boosting calcium channel current (isoproterenol, cilostazol and milrinone) or by inhibition of transient outward current Ito (quinidine, bepridil and the Chinese herb extract Wenxin Keli). EXPERT OPINION This review provides an overview of the clinical and molecular aspects of BrS with a focus on approaches to therapy. Available data suggest that agents capable of inhibiting the transient outward current Ito can exert an ameliorative effect regardless of the underlying cause.
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Affiliation(s)
- Bence Patocskai
- Department of Pharmacology & Pharmacotherapy, University of Szeged, Szeged, Hungary
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86
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Campbell KS, Sorrell VL. Cell- and molecular-level mechanisms contributing to diastolic dysfunction in HFpEF. J Appl Physiol (1985) 2015; 119:1228-32. [PMID: 25911687 DOI: 10.1152/japplphysiol.01168.2014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Accepted: 04/12/2015] [Indexed: 02/08/2023] Open
Abstract
Heart failure with preserved ejection fraction (HFpEF) is the default diagnosis for patients who have symptoms of heart failure, an ejection fraction >0.5, and evidence of diastolic dysfunction. The clinical condition, which was largely unrecognized 30 years ago, is now a major health problem and currently accounts for 50% of all patients with heart failure. Clinical studies show that patients with HFpEF exhibit increased passive stiffness of the ventricles and a slower rate of pressure decline during diastole. This review discusses some of the cell- and molecular-level mechanisms that contribute to these effects and focuses on data obtained using human samples. Collagen cross linking, modulation of protein kinase G-related pathways, Ca(2+) handling, and strain-dependent detachment of cross bridges are highlighted as potential factors that could be modulated to improve ventricular function in patients with HFpEF.
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Affiliation(s)
- Kenneth S Campbell
- Department of Physiology and Center for Muscle Biology, Linda and Jack Gill Heart Institute, University of Kentucky, Lexington, Kentucky; and
| | - Vincent L Sorrell
- Division of Cardiovascular Medicine, Linda and Jack Gill Heart Institute, University of Kentucky, Lexington, Kentucky
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87
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Sossalla S, Wallisch N, Toischer K, Sohns C, Vollmann D, Seegers J, Lüthje L, Maier LS, Zabel M. Effects of ranolazine on torsades de pointes tachycardias in a healthy isolated rabbit heart model. Cardiovasc Ther 2015; 32:170-7. [PMID: 24785406 PMCID: PMC4285941 DOI: 10.1111/1755-5922.12078] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
PURPOSE Torsades de pointes (TdP) tachycardias are triggered, polymorphic ventricular arrhythmias arising from early afterdepolarizations (EADs) and increased dispersion of repolarization. Ranolazine is a new agent which reduces pathologically elevated late INa but also IKr . Aim of this study was to evaluate the effects of ranolazine in a validated isolated Langendorff-perfused rabbit heart model. METHODS TdP was reproducibly induced with d-sotalol (10(-4) mol/L) and low potassium (K) (1.0 mmol/L for 5 min, pacing at CL 1000 ms). In 10 hearts, ECG and 8 epi- and endocardial monophasic action potentials were recorded. Action potential duration (APD) was measured at 90% repolarization and dispersion defined as APD max-min. RESULTS D-sotalol prolonged APD90 and increased dispersion of APD90 , simultaneously causing EADs and induction of TdP. The combination of d-sotalol and two concentrations of ranolazine did not increase dispersion of ventricular APD90 as compared to vehicle. Ranolazine at 5 μmol/L did not cause additional induction of EADs and/or TdP but also did not significantly suppress arrhythmogenic triggers. The higher concentration of ranolazine (10 μmol/L) in combination with d-sotalol caused further prolongation of APD90 , at the same time reduction in APD90 dispersion. In parallel, the incidence of EADs was reduced and an antitorsadogenic effect was seen. CONCLUSIONS In the healthy isolated rabbit heart (where late INa is not elevated), ranolazine does not cause proarrhythmia but exerts antiarrhythmic effects in a dose-dependent manner against d-sotalol/low K-induced TdP. This finding-despite additional APD prolongation-supports the safety of a combined use of both drugs and merits clinical investigation.
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Affiliation(s)
- Samuel Sossalla
- Klinik für Kardiologie und Pneumologie/Herzzentrum, Georg-August-Universität Göttingen, Göttingen, Germany; DZHK (German Center for Cardiovascular Research), Göttingen, Germany
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88
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Shimizu W. Where does heterogeneity exist in ventricular tachyarrhythmias? Heart Rhythm 2015; 12:1304-5. [PMID: 25744614 DOI: 10.1016/j.hrthm.2015.02.034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Indexed: 11/19/2022]
Affiliation(s)
- Wataru Shimizu
- Department of Cardiovascular Medicine, Nippon Medical School, Tokyo, Japan.
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89
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Takahiro T, Kou S, Toshinobu Y, Yuichi H. Accidental hypothermia-induced electrical storm successfully treated with isoproterenol. Heart Rhythm 2015; 12:644-647. [DOI: 10.1016/j.hrthm.2014.11.020] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Indexed: 10/24/2022]
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90
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Kazbanov IV, Clayton RH, Nash MP, Bradley CP, Paterson DJ, Hayward MP, Taggart P, Panfilov AV. Effect of global cardiac ischemia on human ventricular fibrillation: insights from a multi-scale mechanistic model of the human heart. PLoS Comput Biol 2014; 10:e1003891. [PMID: 25375999 PMCID: PMC4222598 DOI: 10.1371/journal.pcbi.1003891] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Accepted: 09/03/2014] [Indexed: 11/18/2022] Open
Abstract
Acute regional ischemia in the heart can lead to cardiac arrhythmias such as ventricular fibrillation (VF), which in turn compromise cardiac output and result in secondary global cardiac ischemia. The secondary ischemia may influence the underlying arrhythmia mechanism. A recent clinical study documents the effect of global cardiac ischaemia on the mechanisms of VF. During 150 seconds of global ischemia the dominant frequency of activation decreased, while after reperfusion it increased rapidly. At the same time the complexity of epicardial excitation, measured as the number of epicardical phase singularity points, remained approximately constant during ischemia. Here we perform numerical studies based on these clinical data and propose explanations for the observed dynamics of the period and complexity of activation patterns. In particular, we study the effects on ischemia in pseudo-1D and 2D cardiac tissue models as well as in an anatomically accurate model of human heart ventricles. We demonstrate that the fall of dominant frequency in VF during secondary ischemia can be explained by an increase in extracellular potassium, while the increase during reperfusion is consistent with washout of potassium and continued activation of the ATP-dependent potassium channels. We also suggest that memory effects are responsible for the observed complexity dynamics. In addition, we present unpublished clinical results of individual patient recordings and propose a way of estimating extracellular potassium and activation of ATP-dependent potassium channels from these measurements.
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Affiliation(s)
- Ivan V Kazbanov
- Department of Physics and Astronomy, Ghent University, Ghent, Belgium
| | - Richard H Clayton
- INSIGNEO Institute for In-Silico Medicine, University of Sheffield, Sheffield, United Kingdom; Department of Computer Science, University of Sheffield, Sheffield, United Kingdom
| | - Martyn P Nash
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand; Department of Engineering Science, University of Auckland, Auckland, New Zealand
| | - Chris P Bradley
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - David J Paterson
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Martin P Hayward
- Departments of Cardiology and Cardiothoracic Surgery, University College Hospital, London, United Kingdom
| | - Peter Taggart
- Departments of Cardiology and Cardiothoracic Surgery, University College Hospital, London, United Kingdom
| | - Alexander V Panfilov
- Department of Physics and Astronomy, Ghent University, Ghent, Belgium; Moscow Institute of Physics and Technology (State University), Dolgoprudny, Moscow Region, Russia
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91
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Alterations of Blood Pressure and ECG following Two-Week Consumption of Berberis integerrima Fruit Extract. INTERNATIONAL SCHOLARLY RESEARCH NOTICES 2014; 2014:209683. [PMID: 27351000 PMCID: PMC4897583 DOI: 10.1155/2014/209683] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Revised: 09/26/2014] [Accepted: 10/02/2014] [Indexed: 11/17/2022]
Abstract
In light of the popularity and also the various nutritional and medicinal properties of Berberis integerrima, this study was conducted to assess the influence of its aqueous extract on hemodynamic and electrocardiogram (ECG) indices of rat. Animals were divided to control (CTL), B50, B100, and B200 groups that orally received tap water, aqueous extracts of B. integerrima fruit 50, 100, and 200 mg/kg/day, respectively, for two weeks and on day 15, data were recorded. Different doses of barberry fruit extract had no significant effect on blood pressure, heart rate, RR interval, P duration, and Q wave amplitude of electrocardiogram. Extract administration was associated with an incremental trend in PR interval that was not statistically significant. Higher doses (100 and 200 mg/kg) of extract significantly increased the QRS interval (P < 0.01 versus CTL and B50 groups) but decreased the QTc interval (P < 0.01 versus CTL group and P < 0.001 versus B50 group), the JT interval, and TpTe interval (P < 0.001 versus CTL and B50 groups). The results suggest that high doses of barberry extract definitely prolong the depolarization phase and shorten the repolarization phase of ventricular muscle and hence induce alteration in heart electrical conductivity.
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92
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Wang Y, Wang W, Li D, Li J, Dai J, Liu Y, Li C, Zhang X, Rong P, Chen Y. The Beneficial Effect of Electro-acupuncture Given at PC6 (Neiguan-point) by the Increase in Cardiac Transient Outward K+ Current Channel Which Depends on the Gene and Protein Expressions in Artificially Induced Myocardial Ischemia Rats. ACUPUNCTURE ELECTRO 2014; 39:259-73. [PMID: 25693308 DOI: 10.3727/036012914x14109544776132] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
This study explored the mechanism of electro-acupuncture (EA) at PC6 to improve the heart function by regulating the cardiac transient outward potassium current (=Ito) channel in myocardial ischemia (MI). Kv1.4 is the main component of the slow Ito (Ito. s) channel. Kv4.2 and Kv4.3
are the main components of the fast Ito (Ito. f) channel. KChIP2 is a compound protein of Ito channel. In this experiment, MI was induced by injecting isoproterenol in rats, and the gene and protein expressions of Kv1.4, Kv4.2, Kv4.3 and KChIP2 were lower [The gene and protein decreased (42.8±4.3)%
and (37.2±4.7)% respectively.] than the control rats significantly (p < 0.05). After MI induction, the MI rats were divided into three groups, including PC6, LU7 (Lieque-point) and Non-acupoint group which were acupunctured at once a day for 7 days respectively. After EA at PC6 and
LU7, the gene and protein expressions showed obvious increased [EA at PC6: the gene and protein increased (50.2±5.4)% and (39.1±5.3)% respectively. EA at LU7: the gene and protein increased (24.6±2.8)% and (22.0±5.5)% respectively] and they are all higher than MI
rats significantly (p < 0.05). EA at PC6 and LU7 showed the same variation, and the effects of EA at PC6 and LU7 were better than Non-acupuncture-point (p < 0.05). The effects of EA at PC6 were significantly better [The gene and protein increased (19.7±2.7)% and (14.1±4.4)%
respectively] than LU7 (p < 0.05). PC6 is an acupoint of the pericardium meridian, and the pericardium meridian which corresponds to adrenal gland according to Omura Y's research, can affect the heart function directly. LU7 belong to the lung meridian, and the lung plays an important factor
in blood circulation according to TCM. So PC6 is more effective than LU7 on heart function regulation. The results suggested that PC6 showed the target effect of meridian specificity on regulating the Kv channel in MI.
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93
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Zhong Y, Cao P, Tong CF, Li X. Effects of ramipril on ventricular arrhythmia after myocardial infarction in rabbits. World J Emerg Med 2014; 5:135-8. [PMID: 25215163 DOI: 10.5847/wjem.j.issn.1920-8642.2014.02.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2013] [Accepted: 01/11/2014] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Ventricular arrhythmia (VA) is one of the most common complications of myocardial infarction (MI), and ventricular tachycardia and fibrillation are the main causes for sudden cardiac death. This study aimed to explore the effect of ramipril on the occurrence of VA and its mechanism after MI in rabbits. METHODS Twenty-four New Zealand rabbits purchased from the Wuhan Laboratory Animal Research Center were divided into three groups: sham-operated (SHAM) group (n=8), MI group (n=8) and MI with ramipril (RAM) group (n=8). Rabbits in the SHAM group received a median sternotomy without ligation of the left ventricular coronary artery. Rabbits in the MI and RAM groups received a median sternotomy followed by ligation of the left coronary artery. The successful anterior MI was confirmed by elevation of the ST segment with more than 0.2 mV in lead II and III. After MI, rabbits in the RAM group were fed with intragastric ramipril (1 mg/kg per day) for 12 weeks. Before and 12 weeks after MI in the three groups, ventricular tachycardia or fibrillation (VT/VF) episodes and MAP in cadiocytes of the epicardium, mid-myocardium and endocardium were recorded by a multichannel physiograph. Student's t test and ANOVA were used for statistical analysis. RESULTS VT/VF episodes were decreased more markedly in the RAM group than in the MI group after 12 weeks (2.6±0.8 vs. 12.4±2.9, P<0.05). Twelve weeks after MI, the duration of repolarization for 90% (APD90) of three-tier ventricular myocytes in the MI group was longer than that before MI (258.2±21.1 vs. 230.1±23.2, 278.0±23.8 vs. 245.8±25.4, 242.6±22.7 vs. 227.0±21.7, P<0.05). However, the APD90 was not significantly different at 12 weeks before and after MI in the RAM group (P>0.05). Moreover, the transmural dispersion of repolarization (TDR) was increased more markedly 12 weeks after MI in the MI group than in the SHAM and RAM groups (36.2±10.2 vs. 18.7±6.2, 24.9±8.7, P<0.05). But the TDR was not significantly different between the RAM and SHAM groups (18.7±6.2 vs. 24.9±8.7, P>0.05). CONCLUSION Ramipril may reduce the incidence of malignant ventricular arrhythmia via improvement of transmembrance repolarization heterogeneity after MI.
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Affiliation(s)
- Ya Zhong
- Department of Geratology, Zhongnan Hospital of Wuhan University, Wuhan 430071, China
| | - Ping Cao
- Department of Geratology, Zhongnan Hospital of Wuhan University, Wuhan 430071, China
| | - Chuan-Feng Tong
- Department of Geratology, Zhongnan Hospital of Wuhan University, Wuhan 430071, China
| | - Xia Li
- Department of Geratology, Zhongnan Hospital of Wuhan University, Wuhan 430071, China
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94
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Sohal M, Duckett SG, Zhuang X, Shi W, Ginks M, Shetty A, Sammut E, Kozerke S, Niederer S, Smith N, Ourselin S, Rinaldi CA, Rueckert D, Carr-White G, Razavi R. A prospective evaluation of cardiovascular magnetic resonance measures of dyssynchrony in the prediction of response to cardiac resynchronization therapy. J Cardiovasc Magn Reson 2014; 16:58. [PMID: 25084814 PMCID: PMC4422256 DOI: 10.1186/s12968-014-0058-0] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Accepted: 07/18/2014] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND Many patients with electrical dyssynchrony who undergo cardiac resynchronization therapy (CRT) do not obtain substantial benefit. Assessing mechanical dyssynchrony may improve patient selection. Results from studies using echocardiographic imaging to measure dyssynchrony have ultimately proved disappointing. We sought to evaluate cardiac motion in patients with heart failure and electrical dyssynchrony using cardiovascular magnetic resonance (CMR). We developed a framework for comparing measures of myocardial mechanics and evaluated how well they predicted response to CRT. METHODS CMR was performed at 1.5 Tesla prior to CRT. Steady-state free precession (SSFP) cine images and complementary modulation of magnetization (CSPAMM) tagged cine images were acquired. Images were processed using a novel framework to extract regional ventricular volume-change, thickening and deformation fields (strain). A systolic dyssynchrony index (SDI) for all parameters within a 16-segment model of the ventricle was computed with high SDI denoting more dyssynchrony. Once identified, the optimal measure was applied to a second patient population to determine its utility as a predictor of CRT response compared to current accepted predictors (QRS duration, LBBB morphology and scar burden). RESULTS Forty-four patients were recruited in the first phase (91% male, 63.3 ± 14.1 years; 80% NYHA class III) with mean QRSd 154 ± 24 ms. Twenty-one out of 44 (48%) patients showed reverse remodelling (RR) with a decrease in end systolic volume (ESV) ≥ 15% at 6 months. Volume-change SDI was the strongest predictor of RR (PR 5.67; 95% CI 1.95-16.5; P = 0.003). SDI derived from myocardial strain was least predictive. Volume-change SDI was applied as a predictor of RR to a second population of 50 patients (70% male, mean age 68.6 ± 12.2 years, 76% NYHA class III) with mean QRSd 146 ± 21 ms. When compared to QRSd, LBBB morphology and scar burden, volume-change SDI was the only statistically significant predictor of RR in this group. CONCLUSION A systolic dyssynchrony index derived from volume-change is a highly reproducible measurement that can be derived from routinely acquired SSFP cine images and predicts RR following CRT whilst an SDI of regional strain does not.
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Affiliation(s)
- Manav Sohal
- Division of Imaging Sciences and Biomedical Engineering, Kings College London, London, UK.
- The Department of Cardiology, Guy's and St Thomas' NHS Foundation Trust, London, UK.
- Division of Imaging Sciences, The Rayne Institute, 4th Floor, Lambeth Wing, St Thomas' Hospital, London, SE1 7EH, UK.
| | - Simon G Duckett
- Division of Imaging Sciences and Biomedical Engineering, Kings College London, London, UK.
| | - Xiahai Zhuang
- Centre for Medical Image Computing, University College London, London, UK.
| | - Wenzhe Shi
- Biomedical Image Analysis Group, Department of Computing, Imperial College London, London, UK.
| | - Matthew Ginks
- Division of Imaging Sciences and Biomedical Engineering, Kings College London, London, UK.
| | - Anoop Shetty
- Division of Imaging Sciences and Biomedical Engineering, Kings College London, London, UK.
- The Department of Cardiology, Guy's and St Thomas' NHS Foundation Trust, London, UK.
| | - Eva Sammut
- Division of Imaging Sciences and Biomedical Engineering, Kings College London, London, UK.
| | - Sebastian Kozerke
- Division of Imaging Sciences and Biomedical Engineering, Kings College London, London, UK.
| | - Steven Niederer
- Division of Imaging Sciences and Biomedical Engineering, Kings College London, London, UK.
| | - Nic Smith
- Division of Imaging Sciences and Biomedical Engineering, Kings College London, London, UK.
| | - Sebastien Ourselin
- Centre for Medical Image Computing, University College London, London, UK.
| | - Christopher Aldo Rinaldi
- Division of Imaging Sciences and Biomedical Engineering, Kings College London, London, UK.
- The Department of Cardiology, Guy's and St Thomas' NHS Foundation Trust, London, UK.
| | - Daniel Rueckert
- Biomedical Image Analysis Group, Department of Computing, Imperial College London, London, UK.
| | - Gerald Carr-White
- The Department of Cardiology, Guy's and St Thomas' NHS Foundation Trust, London, UK.
| | - Reza Razavi
- Division of Imaging Sciences and Biomedical Engineering, Kings College London, London, UK.
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95
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Walton RD, Martinez ME, Bishop MJ, Hocini M, Haïssaguerre M, Plank G, Bernus O, Vigmond EJ. Influence of the Purkinje-muscle junction on transmural repolarization heterogeneity. Cardiovasc Res 2014; 103:629-40. [PMID: 24997066 DOI: 10.1093/cvr/cvu165] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
AIMS To elucidate the properties of the PMJ and myocardium underlying these effects. Transmural heterogeneity of action potential duration (APD) is known to play an important role in arrhythmogenesis. Regions of non-uniformities of APD gradients often overlap considerably with the location of Purkinje-muscle junctions (PMJs). We therefore hypothesized that such junctions are novel sources of local endocardial and transmural heterogeneity of repolarization, and that remodelling due to heart failure modulates this response. METHODS AND RESULTS Spatial gradients of endocardial APD in left ventricular wedge preparations from healthy sheep (n = 5) were correlated with locations of PMJs identified through Purkinje stimulation under optical mapping. APD prolongation was dependent on proximity of the PMJ to the imaged surface, whereby shallow PMJs significantly modulated local APD when stimulating either Purkinje (P = 0.0116) or endocardium (P = 0.0123). In addition, we model a PMJ in 5 × 5× 10 mm transmural tissue wedges using healthy and novel failing human ventricular and Purkinje ionic models. Short distances of the PMJ to cut surfaces (<0.875 mm) revealed that APD maxima were localized to the PMJ in healthy myocardium, whereas APD minima were observed in failing myocardium. Amplitudes and spatial gradients of APD were prominent at functional PMJs and quiescent PMJs. Furthermore, increasing the extent of Purkinje fibre branching or decreasing tissue conductivity augmented local APD prolongation in both failing and non-failing models. CONCLUSIONS The Purkinje network has the potential to influence myocardial AP morphology and rate-dependent behaviour, and furthermore to underlie enhanced transmural APD heterogeneities and spatial gradients of APD in non-failing and failing myocardium.
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Affiliation(s)
- Richard D Walton
- Université de Bordeaux, Centre de Recherche Cardio-Thoracique de Bordeaux U1045, Bordeaux, France Inserm U1045, Centre de Recherche Cardio-Thoracique de Bordeaux, Bordeaux, France L'Institut de Rythmologie et Modélisation Cardiaque LIRYC, Université de Bordeaux, CRCTB U1045, PTIB - Campus Xavier Arnozan, Avenue du Haut Lévêque, 33600 Bordeaux, France
| | - Marine E Martinez
- Université de Bordeaux, Centre de Recherche Cardio-Thoracique de Bordeaux U1045, Bordeaux, France Inserm U1045, Centre de Recherche Cardio-Thoracique de Bordeaux, Bordeaux, France L'Institut de Rythmologie et Modélisation Cardiaque LIRYC, Université de Bordeaux, CRCTB U1045, PTIB - Campus Xavier Arnozan, Avenue du Haut Lévêque, 33600 Bordeaux, France
| | - Martin J Bishop
- Biomedical Engineering Department, Division of Imaging Sciences, King's College London, London, UK
| | - Mélèze Hocini
- Université de Bordeaux, Centre de Recherche Cardio-Thoracique de Bordeaux U1045, Bordeaux, France Inserm U1045, Centre de Recherche Cardio-Thoracique de Bordeaux, Bordeaux, France L'Institut de Rythmologie et Modélisation Cardiaque LIRYC, Université de Bordeaux, CRCTB U1045, PTIB - Campus Xavier Arnozan, Avenue du Haut Lévêque, 33600 Bordeaux, France CHU de Bordeaux, Hôpital du Haut lévêque, Pessac, France
| | - Michel Haïssaguerre
- Université de Bordeaux, Centre de Recherche Cardio-Thoracique de Bordeaux U1045, Bordeaux, France Inserm U1045, Centre de Recherche Cardio-Thoracique de Bordeaux, Bordeaux, France L'Institut de Rythmologie et Modélisation Cardiaque LIRYC, Université de Bordeaux, CRCTB U1045, PTIB - Campus Xavier Arnozan, Avenue du Haut Lévêque, 33600 Bordeaux, France CHU de Bordeaux, Hôpital du Haut lévêque, Pessac, France
| | - Gernot Plank
- Institute of Biophysics, Medical University of Graz, Graz, Austria
| | - Olivier Bernus
- Université de Bordeaux, Centre de Recherche Cardio-Thoracique de Bordeaux U1045, Bordeaux, France Inserm U1045, Centre de Recherche Cardio-Thoracique de Bordeaux, Bordeaux, France L'Institut de Rythmologie et Modélisation Cardiaque LIRYC, Université de Bordeaux, CRCTB U1045, PTIB - Campus Xavier Arnozan, Avenue du Haut Lévêque, 33600 Bordeaux, France
| | - Edward J Vigmond
- L'Institut de Rythmologie et Modélisation Cardiaque LIRYC, Université de Bordeaux, CRCTB U1045, PTIB - Campus Xavier Arnozan, Avenue du Haut Lévêque, 33600 Bordeaux, France L'Institut de Mathématiques de Bordeaux UMR 5251, Université de Bordeaux, Bordeaux, France Department of Electrical and Computer Engineering, University of Calgary, Calgary, Canada
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96
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Chhabra L, Devadoss R, Liti B, Spodick DH. Electrocardiographic changes in hypothermia: a review. Ther Hypothermia Temp Manag 2014; 3:54-62. [PMID: 24837798 DOI: 10.1089/ther.2013.0003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Hypothermia is a common environmental emergency encountered by physicians and is associated with a variety of electrocardiographic (ECG) abnormalities. The classic and well-known ECG manifestations of hypothermia include the presence of J (Osborn) waves, interval (PR, QRS, QT) prolongation, and atrial and ventricular arrhythmias. There are less well defined and known ECG signs of hypothermia, which in fact may simulate findings of acute coronary ischemia, Brugada syndrome, or even pericarditis. Although classical ECG changes seen in hypothermia certainly serve as an important clinical clue for prompt identification and management of this easily curable life-threatening entity, physicians should, however, be able to maintain a high suspicion for recognition and differentiation of less common ECG abnormalities encountered in hypothermia. This article aims to provide a detailed review of all the potential ECG abnormalities that may be encountered in accidental and iatrogenic hypothermia.
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Affiliation(s)
- Lovely Chhabra
- 1 Department of Internal Medicine, Saint Vincent Hospital, University of Massachusetts Medical School , Worcester, Massachusetts
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97
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Molina CE, Johnson DM, Mehel H, Spätjens RLHMG, Mika D, Algalarrondo V, Slimane ZH, Lechêne P, Abi-Gerges N, van der Linde HJ, Leroy J, Volders PGA, Fischmeister R, Vandecasteele G. Interventricular differences in β-adrenergic responses in the canine heart: role of phosphodiesterases. J Am Heart Assoc 2014; 3:e000858. [PMID: 24904016 PMCID: PMC4309082 DOI: 10.1161/jaha.114.000858] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background RV and LV have different embryologic, structural, metabolic, and electrophysiologic characteristics, but whether interventricular differences exist in β‐adrenergic (β‐AR) responsiveness is unknown. In this study, we examine whether β‐AR response and signaling differ in right (RV) versus left (LV) ventricles. Methods and Results Sarcomere shortening, Ca2+ transients, ICa,L and IKs currents were recorded in isolated dog LV and RV midmyocytes. Intracellular [cAMP] and PKA activity were measured by live cell imaging using FRET‐based sensors. Isoproterenol increased sarcomere shortening ≈10‐fold and Ca2+‐transient amplitude ≈2‐fold in LV midmyocytes (LVMs) versus ≈25‐fold and ≈3‐fold in RVMs. FRET imaging using targeted Epac2camps sensors revealed no change in subsarcolemmal [cAMP], but a 2‐fold higher β‐AR stimulation of cytoplasmic [cAMP] in RVMs versus LVMs. Accordingly, β‐AR regulation of ICa,L and IKs were similar between LVMs and RVMs, whereas cytoplasmic PKA activity was increased in RVMs. Both PDE3 and PDE4 contributed to the β‐AR regulation of cytoplasmic [cAMP], and the difference between LVMs and RVMs was abolished by PDE3 inhibition and attenuated by PDE4 inhibition. Finally LV and RV intracavitary pressures were recorded in anesthetized beagle dogs. A bolus injection of isoproterenol increased RV dP/dtmax≈5‐fold versus 3‐fold in LV. Conclusion Canine RV and LV differ in their β‐AR response due to intrinsic differences in myocyte β‐AR downstream signaling. Enhanced β‐AR responsiveness of the RV results from higher cAMP elevation in the cytoplasm, due to a decreased degradation by PDE3 and PDE4 in the RV compared to the LV.
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Affiliation(s)
- Cristina E Molina
- INSERM UMR-S 769, LabEx LERMIT, DHU TORINO, Châtenay-Malabry, France (C.E.M., H.M., D.M., V.A., Z.H.S., P.L., L., R.F., G.V.) Université Paris-Sud, Châtenay-Malabry, France (C.E.M., H.M., D.M., V.A., Z.H.S., P.L., L., R.F., G.V.)
| | - Daniel M Johnson
- Department of Cardiology, Cardiovascular Research Institute Maastricht, Maastricht University Medical Centre, 6202 AZ, Maastricht, The Netherlands (D.M.J., R.G.S., P.A.V.)
| | - Hind Mehel
- INSERM UMR-S 769, LabEx LERMIT, DHU TORINO, Châtenay-Malabry, France (C.E.M., H.M., D.M., V.A., Z.H.S., P.L., L., R.F., G.V.) Université Paris-Sud, Châtenay-Malabry, France (C.E.M., H.M., D.M., V.A., Z.H.S., P.L., L., R.F., G.V.)
| | - Roel L H M G Spätjens
- Department of Cardiology, Cardiovascular Research Institute Maastricht, Maastricht University Medical Centre, 6202 AZ, Maastricht, The Netherlands (D.M.J., R.G.S., P.A.V.)
| | - Delphine Mika
- INSERM UMR-S 769, LabEx LERMIT, DHU TORINO, Châtenay-Malabry, France (C.E.M., H.M., D.M., V.A., Z.H.S., P.L., L., R.F., G.V.) Université Paris-Sud, Châtenay-Malabry, France (C.E.M., H.M., D.M., V.A., Z.H.S., P.L., L., R.F., G.V.)
| | - Vincent Algalarrondo
- INSERM UMR-S 769, LabEx LERMIT, DHU TORINO, Châtenay-Malabry, France (C.E.M., H.M., D.M., V.A., Z.H.S., P.L., L., R.F., G.V.) Université Paris-Sud, Châtenay-Malabry, France (C.E.M., H.M., D.M., V.A., Z.H.S., P.L., L., R.F., G.V.)
| | - Zeineb Haj Slimane
- INSERM UMR-S 769, LabEx LERMIT, DHU TORINO, Châtenay-Malabry, France (C.E.M., H.M., D.M., V.A., Z.H.S., P.L., L., R.F., G.V.) Université Paris-Sud, Châtenay-Malabry, France (C.E.M., H.M., D.M., V.A., Z.H.S., P.L., L., R.F., G.V.)
| | - Patrick Lechêne
- INSERM UMR-S 769, LabEx LERMIT, DHU TORINO, Châtenay-Malabry, France (C.E.M., H.M., D.M., V.A., Z.H.S., P.L., L., R.F., G.V.) Université Paris-Sud, Châtenay-Malabry, France (C.E.M., H.M., D.M., V.A., Z.H.S., P.L., L., R.F., G.V.)
| | - Najah Abi-Gerges
- Department of Translational Safety, DrugSafety and Metabolism, AstraZeneca R&D Innovative Medicines and Early Development, Alderley Park, Macclesfield, SK10 4TG, Cheshire, UK (N.A.G.)
| | - Henk J van der Linde
- Global Safety Research, Preclinical Development & Safety, Discovery Sciences, Janssen Research & Development, Beerse, Belgium (H.J.L.)
| | - Jérôme Leroy
- INSERM UMR-S 769, LabEx LERMIT, DHU TORINO, Châtenay-Malabry, France (C.E.M., H.M., D.M., V.A., Z.H.S., P.L., L., R.F., G.V.) Université Paris-Sud, Châtenay-Malabry, France (C.E.M., H.M., D.M., V.A., Z.H.S., P.L., L., R.F., G.V.)
| | - Paul G A Volders
- Department of Cardiology, Cardiovascular Research Institute Maastricht, Maastricht University Medical Centre, 6202 AZ, Maastricht, The Netherlands (D.M.J., R.G.S., P.A.V.)
| | - Rodolphe Fischmeister
- INSERM UMR-S 769, LabEx LERMIT, DHU TORINO, Châtenay-Malabry, France (C.E.M., H.M., D.M., V.A., Z.H.S., P.L., L., R.F., G.V.) Université Paris-Sud, Châtenay-Malabry, France (C.E.M., H.M., D.M., V.A., Z.H.S., P.L., L., R.F., G.V.)
| | - Grégoire Vandecasteele
- INSERM UMR-S 769, LabEx LERMIT, DHU TORINO, Châtenay-Malabry, France (C.E.M., H.M., D.M., V.A., Z.H.S., P.L., L., R.F., G.V.) Université Paris-Sud, Châtenay-Malabry, France (C.E.M., H.M., D.M., V.A., Z.H.S., P.L., L., R.F., G.V.)
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98
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Rivera S, De La Paz Ricapito M, Conde D, Verdu MB, Roux JF, Paredes FA. The retrograde P-wave theory: explaining ST segment depression in supraventricular tachycardia by retrograde AV node conduction. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2014; 37:1100-5. [PMID: 24697871 DOI: 10.1111/pace.12394] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Revised: 01/26/2010] [Accepted: 02/03/2014] [Indexed: 11/26/2022]
Abstract
BACKGROUND Pseudo ischemic ST segment changes during supraventricular tachycardia (SVT) are not yet fully understood. Our aim was to determine whether venticulo-atrial (VA) conduction during SVT may be a possible mechanism for ST depression (STd) in SVT. METHODS Patients undergoing SVT ablation (2010-2012) were analyzed (n = 72).Typical atrioventricular node reentrant tachycardia (AVNRT) and atrioventricular reentrant tachycardia (AVRT) were included. Those with STd were compared to those without STd. VA interval length, tachycardia cycle length (TCL), and retrograde P-wave activation during SVT were assessed. Retrograde P waves arriving simultaneously with the ST segment (PWST) during SVT were considered, whenever an atrial electrogram (measured from the high right atrium) was "on time" with the ST segment. RESULTS Patients with STd during SVT presented longer VA intervals than those without STd (VA 100 ± 37 ms vs VA 69 ± 22 ms; P = 0.006). No differences in TCL were observed (TCL 333 ± 35 ms vs TCL 360 ± 22 ms; P = 0.1). PWST was observed in 38.5% of patients with AVNRT and STd versus 0% in those without STd. The TCL was similar in both groups (355 ± 25 ms vs 334 ± 18 ms; P = 0.1). In patients with AVRT and STd, PWST was present in 81% of cases versus 0% in those without STd. The TCL was also similar (330 ± 29 ms vs 346 ± 17 ms; P = 0.1). CONCLUSIONS STd during SVT is observed at long VA intervals when the retrograde P wave matches the ST segment, without dependence on the TCL. This suggests that STd is not necessarily rate dependent but a result of a fusion between the ST segment and the P wave.
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Affiliation(s)
- Santiago Rivera
- Division of Cardiology, Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, Canada
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99
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Prognostic value of T peak-to-end interval for risk stratification after acute myocardial infarction. EGYPTIAN JOURNAL OF CRITICAL CARE MEDICINE 2014. [DOI: 10.1016/j.ejccm.2014.09.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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100
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Fereniec M, Stix G, Kania M, Mroczka T, Maniewski R. An analysis of the U-wave and its relation to the T-wave in body surface potential maps for healthy subjects and MI patients. Ann Noninvasive Electrocardiol 2014; 19:145-56. [PMID: 24191849 PMCID: PMC6932608 DOI: 10.1111/anec.12110] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND The aim of this study was to analyze the U-wave morphology and its relation to the T-wave in one group of healthy subjects and in two groups of myocardial infarction (MI) patients-with and without ventricular tachycardia (VT) episodes. The context of the U-wave origin was also discussed and the U-wave as a potential marker of VT was investigated. METHODS The study was carried out on three groups of subjects: 20 healthy subjects, 14 MI patients not at risk of VT, and 22 MI patients at risk of VT. The morphology of the repolarization phase was examined in the high-resolution body surface potential maps recorded from 64 surface ECG leads. The temporal and spatial distributions of several ECG parameters were studied. RESULTS The U-wave was present in almost all the studied subjects. The spatial heterogeneity and smooth change in both the T- and U-wave shapes on the entire torso were observed in all the studied groups. The statistical significance of discrimination between the MI patients without VT and MI patients with VT was observed for QRS interval, QT interval, U-wave integral, and normalized U-wave integral. CONCLUSIONS High-resolution measurement of body surface potentials and an advanced data analysis allow for a detailed description of U-wave morphology and its relation to the T-wave. This might be of value in discriminating intracardiac repolarization effects, mechano-electrical feedback, and arrhythmia risk stratification.
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Affiliation(s)
- Małgorzata Fereniec
- Department of Biophysical Measurements and ImagingNalecz Institute of Biocybernetics and Biomedical EngineeringPolish Academy of SciencesWarsawPoland
| | - Günter Stix
- Department of CardiologyMedical University of ViennaGeneral Hospital of ViennaViennaAustria
| | - Michał Kania
- Department of Biophysical Measurements and ImagingNalecz Institute of Biocybernetics and Biomedical EngineeringPolish Academy of SciencesWarsawPoland
| | - Tomasz Mroczka
- Department of Internal Medicine and CardiologyGeriatric Center WienerwaldViennaAustria
| | - Roman Maniewski
- Department of Biophysical Measurements and ImagingNalecz Institute of Biocybernetics and Biomedical EngineeringPolish Academy of SciencesWarsawPoland
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