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Feaster TK, Ewoldt JK, Avila A, Casciola M, Narkar A, Chen CS, Blinova K. Nonclinical evaluation of chronic cardiac contractility modulation on 3D human engineered cardiac tissues. J Cardiovasc Electrophysiol 2024; 35:895-905. [PMID: 38433304 DOI: 10.1111/jce.16222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/27/2023] [Revised: 01/29/2024] [Accepted: 02/09/2024] [Indexed: 03/05/2024]
Abstract
INTRODUCTION Cardiac contractility modulation (CCM) is a medical device-based therapy delivering non-excitatory electrical stimulations to the heart to enhance cardiac function in heart failure (HF) patients. The lack of human in vitro tools to assess CCM hinders our understanding of CCM mechanisms of action. Here, we introduce a novel chronic (i.e., 2-day) in vitro CCM assay to evaluate the effects of CCM in a human 3D microphysiological system consisting of engineered cardiac tissues (ECTs). METHODS Cryopreserved human induced pluripotent stem cell-derived cardiomyocytes were used to generate 3D ECTs. The ECTs were cultured, incorporating human primary ventricular cardiac fibroblasts and a fibrin-based gel. Electrical stimulation was applied using two separate pulse generators for the CCM group and control group. Contractile properties and intracellular calcium were measured, and a cardiac gene quantitative PCR screen was conducted. RESULTS Chronic CCM increased contraction amplitude and duration, enhanced intracellular calcium transient amplitude, and altered gene expression related to HF (i.e., natriuretic peptide B, NPPB) and excitation-contraction coupling (i.e., sodium-calcium exchanger, SLC8). CONCLUSION These data represent the first study of chronic CCM in a 3D ECT model, providing a nonclinical tool to assess the effects of cardiac electrophysiology medical device signals complementing in vivo animal studies. The methodology established a standardized 3D ECT-based in vitro testbed for chronic CCM, allowing evaluation of physiological and molecular effects on human cardiac tissues.
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Affiliation(s)
- Tromondae K Feaster
- Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, US Food and Drug Administration, Silver Spring, Maryland, USA
| | - Jourdan K Ewoldt
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts, USA
| | - Anna Avila
- Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, US Food and Drug Administration, Silver Spring, Maryland, USA
| | - Maura Casciola
- Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, US Food and Drug Administration, Silver Spring, Maryland, USA
| | - Akshay Narkar
- Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, US Food and Drug Administration, Silver Spring, Maryland, USA
| | - Christopher S Chen
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts, USA
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, Massachusetts, USA
| | - Ksenia Blinova
- Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, US Food and Drug Administration, Silver Spring, Maryland, USA
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Masarone D, Rao I, Pacileo G. HOPE for a better selection of patients for cardiac contractility modulation. Expert Rev Med Devices 2023; 20:525-528. [PMID: 37209105 DOI: 10.1080/17434440.2023.2217329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 04/26/2023] [Accepted: 05/19/2023] [Indexed: 05/22/2023]
Affiliation(s)
- Daniele Masarone
- Heart Failure Unit, Department of Cardiology, AORN dei Colli Monaldi Hospital, Naples, Italy
| | - Ishu Rao
- Impulse Dynamics, Inc, Marlton, NJ, USA
| | - Giuseppe Pacileo
- Heart Failure Unit, Department of Cardiology, AORN dei Colli Monaldi Hospital, Naples, Italy
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Feaster TK, Feric N, Pallotta I, Narkar A, Casciola M, Graziano MP, Aschar-Sobbi R, Blinova K. Acute effects of cardiac contractility modulation stimulation in conventional 2D and 3D human induced pluripotent stem cell-derived cardiomyocyte models. Front Physiol 2022; 13:1023563. [PMID: 36439258 PMCID: PMC9686332 DOI: 10.3389/fphys.2022.1023563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Accepted: 10/28/2022] [Indexed: 11/11/2022] Open
Abstract
Cardiac contractility modulation (CCM) is a medical device therapy whereby non-excitatory electrical stimulations are delivered to the myocardium during the absolute refractory period to enhance cardiac function. We previously evaluated the effects of the standard CCM pulse parameters in isolated rabbit ventricular cardiomyocytes and 2D human induced pluripotent stem cell-derived cardiomyocyte (hiPSC-CM) monolayers, on flexible substrate. In the present study, we sought to extend these results to human 3D microphysiological systems to develop a robust model to evaluate various clinical CCM pulse parameters in vitro. HiPSC-CMs were studied in conventional 2D monolayer format, on stiff substrate (i.e., glass), and as 3D human engineered cardiac tissues (ECTs). Cardiac contractile properties were evaluated by video (i.e., pixel) and force-based analysis. CCM pulses were assessed at varying electrical ‘doses’ using a commercial pulse generator. A robust CCM contractile response was observed for 3D ECTs. Under comparable conditions, conventional 2D monolayer hiPSC-CMs, on stiff substrate, displayed no contractile response. 3D ECTs displayed enhanced contractile properties including increased contraction amplitude (i.e., force), and accelerated contraction and relaxation slopes under standard acute CCM stimulation. Moreover, 3D ECTs displayed enhanced contractility in a CCM pulse parameter-dependent manner by adjustment of CCM pulse delay, duration, amplitude, and number relative to baseline. The observed acute effects subsided when the CCM stimulation was stopped and gradually returned to baseline. These data represent the first study of CCM in 3D hiPSC-CM models and provide a nonclinical tool to assess various CCM device signals in 3D human cardiac tissues prior to in vivo animal studies. Moreover, this work provides a foundation to evaluate the effects of additional cardiac medical devices in 3D ECTs.
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Affiliation(s)
- Tromondae K. Feaster
- Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, MD, United States
| | - Nicole Feric
- Valo Health Inc, Alexandria Center for Life Sciences, New York, NY, United States
| | - Isabella Pallotta
- Valo Health Inc, Alexandria Center for Life Sciences, New York, NY, United States
| | - Akshay Narkar
- Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, MD, United States
| | - Maura Casciola
- Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, MD, United States
| | - Michael P. Graziano
- Valo Health Inc, Alexandria Center for Life Sciences, New York, NY, United States
| | - Roozbeh Aschar-Sobbi
- Valo Health Inc, Alexandria Center for Life Sciences, New York, NY, United States
| | - Ksenia Blinova
- Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, MD, United States
- *Correspondence: Ksenia Blinova,
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Yücel G, Fastner C, Hetjens S, Toepel M, Schmiel G, Yazdani B, Husain-Syed F, Liebe V, Rudic B, Akin I, Borggrefe M, Kuschyk J. Impact of baseline left ventricular ejection fraction on long-term outcomes in cardiac contractility modulation therapy. Pacing Clin Electrophysiol 2022; 45:639-648. [PMID: 35262210 DOI: 10.1111/pace.14478] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 01/31/2022] [Accepted: 02/20/2022] [Indexed: 11/29/2022]
Abstract
BACKGROUND Cardiac contractility modulation (CCM), being reserved for patients with symptomatic chronic heart failure (HF) and narrow QRS complex under guideline directed medical therapy, can recover initially reduced left ventricular ejection fraction (LVEF); however, the influence of pre-implantation LVEF on long-term outcomes is not fully understood. This study aimed to compare the effects of lower and higher pre-implantation LVEF on long-term outcomes in CCM-therapy. METHODS One-hundred seventy-two patients from our single-centre registry were retrospectively included (2002 - 2019). Follow-up data were collected up to five years after implantation. Patients were divided into Group 1 (baseline LVEF≤ 30%) and Group 2 (≥ 31%). Both groups were compared based on differences in survival, echocardiographic- and clinical parameters including LVEF, tricuspid annular plane systolic excursion (TAPSE), NYHA class or Minnesota living with heart failure questionnaire-score (MLWHFQ). RESULTS 11 % of the patients did have a LVEF ≥ 31%. Mean LVEF±SD for both groups were 21.98±5.4 vs. 35.2±3.7%, respectively. MLWHFQ (47±21.2 vs. 42±21.4) and mean peak oxygen consumption (VO2, 13.6±4.1 vs. 12.7±2.8 ml/kg/min) were comparable between both groups. LVEF-grouping did not influence survival. Lower baseline LVEF resulted in significantly better recovery of echocardiographic parameters such as LVEF and TAPSE. Irrespective from baseline LVEF, both groups showed nearly comparable improvements for clinical parameters like NYHA-class and MLWHFQ. CONCLUSION Long-term biventricular systolic recovery potential in CCM-therapy might be better for pre-implantation LVEF values ≤ 30%, whereas clinical parameters such as NYHA-class can improve irrespective from baseline LVEF. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Gökhan Yücel
- First Department of Medicine, Faculty of Medicine, University Medical Centre Mannheim (UMM), University of Heidelberg, Mannheim, Germany.,Partner Site, Heidelberg-Mannheim, DZHK (German Centre for Cardiovascular Research), Mannheim, Germany
| | - Christian Fastner
- First Department of Medicine, Faculty of Medicine, University Medical Centre Mannheim (UMM), University of Heidelberg, Mannheim, Germany.,Partner Site, Heidelberg-Mannheim, DZHK (German Centre for Cardiovascular Research), Mannheim, Germany
| | - Svetlana Hetjens
- Department of Medical Statistics and Biomathematics, Medical Faculty Mannheim, University Medical Centre Mannheim, Heidelberg University, Mannheim, Germany
| | - Matthias Toepel
- First Department of Medicine, Faculty of Medicine, University Medical Centre Mannheim (UMM), University of Heidelberg, Mannheim, Germany
| | - Gereon Schmiel
- First Department of Medicine, Faculty of Medicine, University Medical Centre Mannheim (UMM), University of Heidelberg, Mannheim, Germany
| | - Babak Yazdani
- Fifth Department of Medicine, Faculty of Medicine, University Medical Centre Mannheim (UMM), University of Heidelberg, Mannheim, Germany
| | - Faeq Husain-Syed
- Department of Internal Medicine II, Division of Nephrology, University Hospital Giessen and Marburg, Justus-Liebig-University Giessen, Giessen, Germany
| | - Volker Liebe
- First Department of Medicine, Faculty of Medicine, University Medical Centre Mannheim (UMM), University of Heidelberg, Mannheim, Germany.,Partner Site, Heidelberg-Mannheim, DZHK (German Centre for Cardiovascular Research), Mannheim, Germany
| | - Boris Rudic
- First Department of Medicine, Faculty of Medicine, University Medical Centre Mannheim (UMM), University of Heidelberg, Mannheim, Germany.,Partner Site, Heidelberg-Mannheim, DZHK (German Centre for Cardiovascular Research), Mannheim, Germany
| | - Ibrahim Akin
- First Department of Medicine, Faculty of Medicine, University Medical Centre Mannheim (UMM), University of Heidelberg, Mannheim, Germany.,Partner Site, Heidelberg-Mannheim, DZHK (German Centre for Cardiovascular Research), Mannheim, Germany
| | - Martin Borggrefe
- First Department of Medicine, Faculty of Medicine, University Medical Centre Mannheim (UMM), University of Heidelberg, Mannheim, Germany.,Partner Site, Heidelberg-Mannheim, DZHK (German Centre for Cardiovascular Research), Mannheim, Germany
| | - Jürgen Kuschyk
- First Department of Medicine, Faculty of Medicine, University Medical Centre Mannheim (UMM), University of Heidelberg, Mannheim, Germany.,Partner Site, Heidelberg-Mannheim, DZHK (German Centre for Cardiovascular Research), Mannheim, Germany
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Feaster TK, Casciola M, Narkar A, Blinova K. Acute effects of cardiac contractility modulation on human induced pluripotent stem cell-derived cardiomyocytes. Physiol Rep 2021; 9:e15085. [PMID: 34729935 PMCID: PMC8564440 DOI: 10.14814/phy2.15085] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Revised: 10/04/2021] [Accepted: 10/08/2021] [Indexed: 12/20/2022] Open
Abstract
Cardiac contractility modulation (CCM) is an intracardiac therapy whereby nonexcitatory electrical simulations are delivered during the absolute refractory period of the cardiac cycle. We previously evaluated the effects of CCM in isolated adult rabbit ventricular cardiomyocytes and found a transient increase in calcium and contractility. In the present study, we sought to extend these results to human cardiomyocytes using human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) to develop a robust model to evaluate CCM in vitro. HiPSC-CMs (iCell Cardiomyocytes2 , Fujifilm Cellular Dynamic, Inc.) were studied in monolayer format plated on flexible substrate. Contractility, calcium handling, and electrophysiology were evaluated by fluorescence- and video-based analysis (CellOPTIQ, Clyde Biosciences). CCM pulses were applied using an A-M Systems 4100 pulse generator. Robust hiPSC-CMs response was observed at 14 V/cm (64 mA) for pacing and 28 V/cm (128 mA, phase amplitude) for CCM. Under these conditions, hiPSC-CMs displayed enhanced contractile properties including increased contraction amplitude and faster contraction kinetics. Likewise, calcium transient amplitude increased, and calcium kinetics were faster. Furthermore, electrophysiological properties were altered resulting in shortened action potential duration (APD). The observed effects subsided when the CCM stimulation was stopped. CCM-induced increase in hiPSC-CMs contractility was significantly more pronounced when extracellular calcium concentration was lowered from 2 mM to 0.5 mM. This study provides a comprehensive characterization of CCM effects on hiPSC-CMs. These data represent the first study of CCM in hiPSC-CMs and provide an in vitro model to assess physiologically relevant mechanisms and evaluate safety and effectiveness of future cardiac electrophysiology medical devices.
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Affiliation(s)
- Tromondae K. Feaster
- Office of Science and Engineering LaboratoriesCenter for Devices and Radiological HealthUS Food and Drug AdministrationSilver SpringMarylandUSA
| | - Maura Casciola
- Office of Science and Engineering LaboratoriesCenter for Devices and Radiological HealthUS Food and Drug AdministrationSilver SpringMarylandUSA
| | - Akshay Narkar
- Office of Science and Engineering LaboratoriesCenter for Devices and Radiological HealthUS Food and Drug AdministrationSilver SpringMarylandUSA
| | - Ksenia Blinova
- Office of Science and Engineering LaboratoriesCenter for Devices and Radiological HealthUS Food and Drug AdministrationSilver SpringMarylandUSA
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Ning B, Zhang F, Song X, Hao Q, Li Y, Li R, Dang Y. Cardiac contractility modulation attenuates structural and electrical remodeling in a chronic heart failure rabbit model. J Int Med Res 2021; 48:300060520962910. [PMID: 33044118 PMCID: PMC7556184 DOI: 10.1177/0300060520962910] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Background Cardiac contractility modulation (CCM) is non-excitatory electrical stimulation for improving cardiac function. This study aimed to evaluate the effects of CCM on structural and electrical remodeling in a rabbit model of chronic heart failure (CHF). Methods Thirty rabbits were randomly divided into the sham, CHF, and CCM groups. The CHF model was induced 12 weeks after trans-aortic constriction by pressure unloading and CCM was delivered to the myocardium for 4 weeks. Corrected QT intervals, the ventricular effective refractory period, and inducibility of ventricular tachycardia were measured by an electrophysiological examination. Connective tissue growth factor, galectin-3, Kv4.3, KCNQ1, KCNH2, and connexin 43 protein levels were measured by western blotting. Results The CHF group had a significantly prolonged corrected QT interval and ventricular effective refractory period, and increased inducibility of ventricular tachycardia. Prominent myocardial fibrosis and increased hydroxyproline content were observed in the CHF group, but these were suppressed in the CCM group. Kv4.3, KCNQ1, KCNH2, and connexin 43 protein levels were significantly lower in the CHF group, but treatment with CCM partially restored their levels. Conclusions CCM attenuates myocardial structural and electrical remodeling during CHF. These findings provide evidence for clinical use of CCM in treating CHF.
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Affiliation(s)
- Bin Ning
- Department of Cardiology, The People's Hospital of Fuyang, Fuyang, Anhui Province, People's Republic of China
| | - Feifei Zhang
- Department of Cardiology, Hebei General Hospital, Shijiazhuang, Hebei Province, People's Republic of China
| | - Xuelian Song
- Department of Cardiology, Hebei General Hospital, Shijiazhuang, Hebei Province, People's Republic of China
| | - Qingqing Hao
- Department of Cardiology, Hebei General Hospital, Shijiazhuang, Hebei Province, People's Republic of China
| | - Yingxiao Li
- Department of Cardiology, Hebei General Hospital, Shijiazhuang, Hebei Province, People's Republic of China
| | - Rong Li
- Department of Cardiology, Hebei General Hospital, Shijiazhuang, Hebei Province, People's Republic of China
| | - Yi Dang
- Department of Cardiology, Hebei General Hospital, Shijiazhuang, Hebei Province, People's Republic of China
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Barnes A, Campbell C, Weiss R, Kahwash R. Cardiac Contractility Modulation in Heart Failure: Mechanisms and Clinical Evidence. CURRENT TREATMENT OPTIONS IN CARDIOVASCULAR MEDICINE 2020. [DOI: 10.1007/s11936-020-00852-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Cardiac contractility modulation for the treatment of heart failure with reduced ejection fraction. Heart Fail Rev 2020; 26:217-226. [PMID: 32852661 DOI: 10.1007/s10741-020-10017-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 08/21/2020] [Indexed: 12/11/2022]
Abstract
There has been a progressive evolution in the management of patients with chronic heart failure and reduced ejection fraction (HFrEF), including cardiac resynchronisation therapy (CRT) in those that fulfil pre-defined criteria. However, there exists a significant proportion with refractory symptoms in whom CRT devices are not clinically indicated or ineffective. Cardiac contractility modulation (CCM) is a novel therapy that incorporates administration of non-excitatory electrical impulses to the interventricular septum during the absolute refractory period. Implantation is analogous to a traditional transvenous pacemaker system, but with the use of two right ventricular leads. Mechanistic studies have shown augmentation of left ventricular contractility and beneficial global effects on reverse remodeling, primarily through alterations in calcium handling. This appears to occur without increasing myocardial oxygen consumption. Data from clinical trials have shown translational improvements in functional capacity and quality of life, though long-term outcome data are lacking. This review explores the rationale, evidence base and limitations of this nascent technology.
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Merchant FM, Sayadi O, Sohn K, Weiss EH, Puppala D, Doddamani R, Singh JP, Heist EK, Owen C, Kulkarni K, Armoundas AA. Real-Time Closed-Loop Suppression of Repolarization Alternans Reduces Arrhythmia Susceptibility In Vivo. Circ Arrhythm Electrophysiol 2020; 13:e008186. [PMID: 32434448 DOI: 10.1161/circep.119.008186] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Repolarization alternans (RA) has been implicated in the pathogenesis of ventricular arrhythmias and sudden cardiac death. METHODS We have developed a real-time, closed-loop system to record and analyze RA from multiple intracardiac leads, and deliver dynamically R-wave triggered pacing stimuli during the absolute refractory period. We have evaluated the ability of this system to control RA and reduce arrhythmia susceptibility, in vivo. RESULTS R-wave triggered pacing can induce RA, the magnitude of which can be modulated by varying the amplitude, pulse width, and size of the pacing vector. Using a swine model (n=9), we demonstrate that to induce a 1 µV change in the alternans voltage on the body surface, coronary sinus and left ventricle leads, requires a delivered charge of 0.04±0.02, 0.05±0.025, and 0.06±0.033 µC, respectively, while to induce a one unit change of the Kscore, requires a delivered charge of 0.93±0.73, 0.32±0.29, and 0.33±0.37 µC, respectively. For all body surface and intracardiac leads, both Δ(alternans voltage) and ΔKscore between baseline and R-wave triggered paced beats increases consistently with an increase in the pacing pulse amplitude, pulse width, and vector spacing. Additionally, we show that the proposed method can be used to suppress spontaneously occurring alternans (n=7), in the presence of myocardial ischemia. Suppression of RA by pacing during the absolute refractory period results in a significant reduction in arrhythmia susceptibility, evidenced by a lower Srank score during programmed ventricular stimulation compared with baseline before ischemia. CONCLUSIONS We have developed and evaluated a novel closed-loop method to dynamically modulate RA in a swine model. Our data suggest that suppression of RA directly reduces arrhythmia susceptibility and reinforces the concept that RA plays a critical role in the pathophysiology of arrhythmogenesis.
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Affiliation(s)
- Faisal M Merchant
- Cardiology Division, Emory University School of Medicine, Atlanta, GA (F.M.M.).,Cardiovascular Research Center (F.M.M., O.S., K.S., E.H.W., D.P., R.D., K.K., A.A.A.), Massachusetts General Hospital, Boston
| | - Omid Sayadi
- Cardiovascular Research Center (F.M.M., O.S., K.S., E.H.W., D.P., R.D., K.K., A.A.A.), Massachusetts General Hospital, Boston
| | - Kwanghyun Sohn
- Cardiovascular Research Center (F.M.M., O.S., K.S., E.H.W., D.P., R.D., K.K., A.A.A.), Massachusetts General Hospital, Boston
| | - Eric H Weiss
- Cardiovascular Research Center (F.M.M., O.S., K.S., E.H.W., D.P., R.D., K.K., A.A.A.), Massachusetts General Hospital, Boston.,Institute for Medical Engineering and Science, Massachusetts Institute of Technology Cambridge (E.H.W., A.A.A.)
| | - Dheeraj Puppala
- Cardiovascular Research Center (F.M.M., O.S., K.S., E.H.W., D.P., R.D., K.K., A.A.A.), Massachusetts General Hospital, Boston
| | - Rajiv Doddamani
- Cardiovascular Research Center (F.M.M., O.S., K.S., E.H.W., D.P., R.D., K.K., A.A.A.), Massachusetts General Hospital, Boston
| | - Jagmeet P Singh
- Cardiology Division, Cardiac Arrhythmia Service (J.P.S., E.K.H.), Massachusetts General Hospital, Boston
| | - E Kevin Heist
- Cardiology Division, Cardiac Arrhythmia Service (J.P.S., E.K.H.), Massachusetts General Hospital, Boston
| | - Chris Owen
- Neurosurgery Division (C.O.), Massachusetts General Hospital, Boston
| | - Kanchan Kulkarni
- Cardiovascular Research Center (F.M.M., O.S., K.S., E.H.W., D.P., R.D., K.K., A.A.A.), Massachusetts General Hospital, Boston
| | - Antonis A Armoundas
- Cardiovascular Research Center (F.M.M., O.S., K.S., E.H.W., D.P., R.D., K.K., A.A.A.), Massachusetts General Hospital, Boston.,Institute for Medical Engineering and Science, Massachusetts Institute of Technology Cambridge (E.H.W., A.A.A.)
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10
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Campbell CM, Kahwash R, Abraham WT. Optimizer Smart in the treatment of moderate-to-severe chronic heart failure. Future Cardiol 2020; 16:13-25. [DOI: 10.2217/fca-2019-0044] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Cardiac contractility modulation, also referred to as CCM™, by the Optimizer Smart device is an innovative intracardiac device-based therapy that has been recently US FDA-approved for the treatment of patients with chronic heart failure, left ventricular ejection fraction (LVEF) between 25 and 45%, QRS <130 ms who remain symptomatic despite optimal medical therapy. Clinical trials demonstrate that CCM therapy is safe and effective in reducing heart failure hospitalization and improving heart failure symptoms, quality of life and functional performance. This novel device-based therapeutic offers benefits to patients who do not otherwise qualify for cardiac resynchronization therapy. CCM expands the indication beyond the traditional LVEF cutoff of 35% to a newer group including patients who fall in midrange LVEF group, up to 45%.
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Affiliation(s)
- Courtney M Campbell
- Department of Internal Medicine, Division of Cardiovascular Medicine, The Ohio State University Wexner Medical Center, 200 Davis Heart & Lung Institute, 473 W 12th Ave, Columbus, OH 43210, USA
| | - Rami Kahwash
- Department of Internal Medicine, Division of Cardiovascular Medicine, The Ohio State University Wexner Medical Center, 200 Davis Heart & Lung Institute, 473 W 12th Ave, Columbus, OH 43210, USA
| | - William T Abraham
- Department of Internal Medicine, Division of Cardiovascular Medicine, The Ohio State University Wexner Medical Center, 200 Davis Heart & Lung Institute, 473 W 12th Ave, Columbus, OH 43210, USA
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Kulkarni K, Merchant FM, Kassab MB, Sana F, Moazzami K, Sayadi O, Singh JP, Heist EK, Armoundas AA. Cardiac Alternans: Mechanisms and Clinical Utility in Arrhythmia Prevention. J Am Heart Assoc 2019; 8:e013750. [PMID: 31617437 PMCID: PMC6898836 DOI: 10.1161/jaha.119.013750] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Kanchan Kulkarni
- Cardiovascular Research CenterMassachusetts General HospitalBostonMA
| | | | - Mohamad B. Kassab
- Cardiovascular Research CenterMassachusetts General HospitalBostonMA
| | - Furrukh Sana
- Cardiovascular Research CenterMassachusetts General HospitalBostonMA
| | - Kasra Moazzami
- Cardiovascular Research CenterMassachusetts General HospitalBostonMA
| | - Omid Sayadi
- Cardiovascular Research CenterMassachusetts General HospitalBostonMA
| | - Jagmeet P. Singh
- Cardiology DivisionCardiac Arrhythmia ServiceMassachusetts General HospitalBostonMA
| | - E. Kevin Heist
- Cardiology DivisionCardiac Arrhythmia ServiceMassachusetts General HospitalBostonMA
| | - Antonis A. Armoundas
- Cardiovascular Research CenterMassachusetts General HospitalBostonMA
- Institute for Medical Engineering and ScienceMassachusetts Institute of TechnologyCambridgeMA
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12
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Cao H, Wang X, Ying S, Huang C. AMPKα2 deficiency enhanced susceptibility to ventricular arrhythmias in mice by the role of β-adrenoceptor signaling. Exp Biol Med (Maywood) 2018; 243:708-714. [PMID: 29597876 DOI: 10.1177/1535370218767389] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
AMP-activated protein kinase-α2 is the main catalytic subunit of the heart, which is mainly located in cardiac myocytes. The effect of AMP-activated protein kinase-α2 on the cardiac electrophysiology is barely studied. From the previous study, it is possible that AMP-activated protein kinase-α2 may have some effect on the electrophysiology of the heart. To prove the hypothesis, we used the AMP-activated protein kinase-α2 knockout (AMPKα2-/-) mice to estimate the electrophysiological characteristics of AMPKα2-/- mice and try to find the mechanism between them. We used AMP-activated protein kinase-α2 gene knockout (AMPKα2-/-) mice and control wild-type mice as the experimental animals. In the experiment, we measured the monophasic action potential duration and test the inducibility to ventricular arrhythmia in isolated mice heart with and without β-adrenoceptor antagonist metoprolol. Meanwhile, plasma concentration of catecholamine was collected. We found that AMPKα2-/- significantly shortened 90% repolarization of monophasic action potential (MAP) (MAPD90) than wild-type (47.4 ± 2.6 ms vs. 55.5 ± 2.4 ms, n = 10, P < 0.05) and were more vulnerable to be induced to ventricular arrhythmias (70% (7/10) vs. 10% (1/10), P < 0.05), accompanied by the higher concentration of catecholamine (epinephrine: 1.75 ± 0.18 nmol/L vs. 0.68 ± 0.10 nmol/L n = 10, P < 0.05; norepinephrine: 9.56 ± 0.71 nmol/L vs. 2.52 ± 0.31 nmol/L n = 10, P < 0.05). The shortening of MAPD90 and increased inducibility to ventricular arrhythmias of AMPKα2-/- could almost be abolished when perfusion with β-adrenoceptor antagonist metoprolol. It indicated that the β-adrenoceptor activation resulting from catecholamine release was mainly responsible for the relating changes of electrophysiology of AMPKα2-/-. It had great clinical significance, as in patients who had problem with AMP-activated protein kinase-α2 gene, we might use β-adrenoceptor antagonists as the prevention of arrhythmias in future. Impact statement As far as we know, this is the first time the role of AMP-activated protein kinase-α2 (AMPKα2) on the cardiac electrophysiology is explored, and we found that the β-adrenoceptor activation resulting from catecholamine release was mainly responsible for the changes of electrophysiology related to the absence of AMPKα2. This has great clinical significance, as in patients who have problems with AMPKα2 gene, we may use β-adrenoceptor antagonists for the prevention of arrhythmias in future.
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Affiliation(s)
- Hong Cao
- 1 Departments of Cardiology, Renmin Hospital of Wuhan University, Wuhan 430060, PR China.,2 Department of Gerontology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, PR China.,3 Cardiovascular Research Institute, Wuhan University, Wuhan 430060, PR China.,4 Hubei Key Laboratory of Cardiology, Wuhan 430060, PR China
| | - Xin Wang
- 1 Departments of Cardiology, Renmin Hospital of Wuhan University, Wuhan 430060, PR China.,3 Cardiovascular Research Institute, Wuhan University, Wuhan 430060, PR China.,4 Hubei Key Laboratory of Cardiology, Wuhan 430060, PR China
| | - Shaozheng Ying
- 1 Departments of Cardiology, Renmin Hospital of Wuhan University, Wuhan 430060, PR China.,3 Cardiovascular Research Institute, Wuhan University, Wuhan 430060, PR China.,4 Hubei Key Laboratory of Cardiology, Wuhan 430060, PR China
| | - Congxin Huang
- 1 Departments of Cardiology, Renmin Hospital of Wuhan University, Wuhan 430060, PR China.,3 Cardiovascular Research Institute, Wuhan University, Wuhan 430060, PR China.,4 Hubei Key Laboratory of Cardiology, Wuhan 430060, PR China
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Coote JH, Chauhan RA. The sympathetic innervation of the heart: Important new insights. Auton Neurosci 2016; 199:17-23. [PMID: 27568995 DOI: 10.1016/j.autneu.2016.08.014] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Revised: 08/19/2016] [Accepted: 08/20/2016] [Indexed: 01/20/2023]
Abstract
Autonomic control of the heart has a significant influence over development of life threatening arrhythmias that can lead to sudden cardiac death. Sympathetic activity is known to be upregulated during these conditions and hence the sympathetic nerves present a target for treatment. However, a better understanding of the anatomy and physiology of cardiac sympathetic nerves is required for the progression of clinical interventions. This review explores the organization of the cardiac sympathetic nerves, from the preganglionic origin to the postganglionic innervations, and provides an overview of literature surrounding anti-arrhythmic therapies including thoracic sympathectomy and dorsal spinal cord stimulation. Several features of the innervation are clear. The cardiac nerves differentially supply the nodal and myocardial tissue of the heart and are dependent on activity generated in spinal neurones in the upper thoracic cord which project to synapse with ganglion cells in the stellate complex on each side. Networks of spinal interneurones determine the pattern of activity. Groups of spinal neurones selectively target specific regions of the heart but whether they exhibit a functional selectivity has still to be elucidated. Electrical or ischemic signals can lead to remodeling of nerves in the heart or ganglia. Surgical and electrical methods are proving to be clinically beneficial in reducing atrial and ventricular arrhythmias, heart failure and severe cardiac pain. This is a rapidly developing area and we need more basic understanding of how these methods work to ensure safety and reduction of side effects.
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Affiliation(s)
- J H Coote
- Cardiovascular Sciences, Glenfield Hospital, University of Leicester, UK; School of Clinical and Experimental Medicine, University of Birmingham, UK.
| | - R A Chauhan
- Cardiovascular Sciences, Glenfield Hospital, University of Leicester, UK
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14
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Ito BR, Covell JW, Curtis GP. Low Intensity Epicardial Pacing During the Absolute Refractory Period Augments Left Ventricular Function Mediated by Local Catecholamine Release. J Cardiovasc Electrophysiol 2016; 27:1102-9. [PMID: 27279561 DOI: 10.1111/jce.13027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 05/17/2016] [Accepted: 05/24/2016] [Indexed: 11/27/2022]
Abstract
BACKGROUND Biventricular epicardial (Epi) pacing can augment left ventricular (LV) function in heart failure. We postulated that these effects might involve catecholamine release from local autonomic nerve activation. To evaluate this hypothesis we applied low intensity Epi electrical stimuli during the absolute refractory period (ARP), thus avoiding altered activation sequence. METHODS Anesthetized pigs (n = 6) were instrumented with an LV pressure (LVP) transducer, left atrial (LA) and LV Epi pacing electrodes, and sonomicrometer segment length (SL) gauges placed proximal and remote to the LV stimulation site. A catheter was placed into the great cardiac vein adjacent to the LV pacing site for norepinephrine (NE) analysis. During LA pacing at constant rate, 3 pulses (0.8 milliseconds, 2-3x threshold) were applied to the LV Epi electrodes during the ARP. An experimental run consisted of baseline, stimulation (10 minutes), and recovery (5 minutes), repeated 3 times before and after β1 - receptor blockade (BB, metoprolol). RESULTS ARP stimulation produced significant increases in cardiac function reflected by elevated LVP, LV, dP/dtmax , and reduced time to LV dP/dtmax . This was accompanied by increased coronary NE levels and increases in LVP versus SL loop area in the remote myocardial segment. In contrast, the proximal segment exhibited early shortening and decreased loop area. BB abolished the changes in SL and LV function despite continued NE release. CONCLUSION These results demonstrate that ARP EPI stimulation induces NE release mediating augmented global LV function. This effect may contribute to the beneficial effect of biventricular Epi pacing in heart failure in some patients.
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Affiliation(s)
- Bruce R Ito
- Donald P. Shiley Bioscience Center, San Diego State University, San Diego, California, USA. .,University of California, San Diego, California, USA.
| | | | - Guy P Curtis
- Scripps Clinic and Research, San Diego and La Jolla, California, USA
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15
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Sims MW, Winter J, Brennan S, Norman RI, André Ng G, Squire IB, Rainbow RD. PKC-mediated toxicity of elevated glucose concentration on cardiomyocyte function. Am J Physiol Heart Circ Physiol 2014; 307:H587-97. [DOI: 10.1152/ajpheart.00894.2013] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
While it is well established that mortality risk after myocardial infarction (MI) increases in proportion to blood glucose concentration at the time of admission, it is unclear whether there is a direct, causal relationship. We investigated potential mechanisms by which increased blood glucose may exert cardiotoxicity. Using a Wistar rat or guinea-pig isolated cardiomyocyte model, we investigated the effects on cardiomyocyte function and electrical stability of alterations in extracellular glucose concentration. Contractile function studies using electric field stimulation (EFS), patch-clamp recording, and Ca2+ imaging were used to determine the effects of increased extracellular glucose concentration on cardiomyocyte function. Increasing glucose from 5 to 20 mM caused prolongation of the action potential and increased both basal Ca2+ and variability of the Ca2+ transient amplitude. Elevated extracellular glucose concentration also attenuated the protection afforded by ischemic preconditioning (IPC), as assessed using a simulated ischemia and reperfusion model. Inhibition of PKCα and β, using Gö6976 or specific inhibitor peptides, attenuated the detrimental effects of glucose and restored the cardioprotected phenotype to IPC cells. Increased glucose concentration did not attenuate the cardioprotective role of PKCε, but rather activation of PKCα and β masked its beneficial effect. Elevated extracellular glucose concentration exerts acute cardiotoxicity mediated via PKCα and β. Inhibition of these PKC isoenzymes abolishes the cardiotoxic effects and restores IPC-mediated cardioprotection. These data support a direct link between hyperglycemia and adverse outcome after MI. Cardiac-specific PKCα and β inhibition may be of clinical benefit in this setting.
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Affiliation(s)
- Mark W. Sims
- Department of Cardiovascular Sciences, University of Leicester, Glenfield General Hospital, Leicester, United Kingdom; and
| | - James Winter
- Department of Cardiovascular Sciences, University of Leicester, Glenfield General Hospital, Leicester, United Kingdom; and
| | - Sean Brennan
- Department of Cardiovascular Sciences, University of Leicester, Glenfield General Hospital, Leicester, United Kingdom; and
| | - Robert I. Norman
- Department of Medical and Social Care Education, University of Leicester, Leicester, United Kingdom
| | - G. André Ng
- Department of Cardiovascular Sciences, University of Leicester, Glenfield General Hospital, Leicester, United Kingdom; and
| | - Iain B. Squire
- Department of Cardiovascular Sciences, University of Leicester, Glenfield General Hospital, Leicester, United Kingdom; and
| | - Richard D. Rainbow
- Department of Cardiovascular Sciences, University of Leicester, Glenfield General Hospital, Leicester, United Kingdom; and
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16
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Blinova K, Stohlman J, Krauthamer V, Knapton A, Bloomquist E, Gray RA. Acute effects of nonexcitatory electrical stimulation during systole in isolated cardiac myocytes and perfused heart. Physiol Rep 2014; 2:2/8/e12106. [PMID: 25096553 PMCID: PMC4246583 DOI: 10.14814/phy2.12106] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Application of electrical field to the heart during the refractory period of the beat has been shown to increase the force of contraction both in animal models and in heart failure patients (cardiac contractility modulation, or CCM). A direct increase in intracellular calcium during CCM has been suggested to be the mechanism behind the positive inotropic effect of CCM. We studied the effect of CCM on isolated rabbit cardiomyocytes and perfused whole rat hearts. The effect of CCM was observed in single cells via fluorescent measurements of intracellular calcium concentration ([Ca2+]i) and cell length (L). Cells were paced once per second throughout these recordings, and CCM stimulation was delivered via biphasic electric fields of 20 ms duration applied during the refractory period. CCM increased the peak amplitude of both [Ca2+]i and L for the first beat during CCM compared to control, but then [Ca2+]i and L decayed to levels lower than the control. During CCM, all contractions had a faster time to peak for both [Ca2+]i and L; after stopping CCM the rise times returned to control levels. In the whole rat heart, the positive inotropic effect of CCM stimulation on left ventricular pressure was completely abolished in the presence of metoprolol, a beta‐1 adrenergic blocker. In summary, the CCM‐induced changes in intracellular calcium handling by cardiomyocytes did not explain the sustained positive inotropic effect in the whole heart and the β‐adrenergic pathway may be involved in the CCM mechanism of action. Cardiac contractility modulation (CCM) is a heart failure therapy which delivers electrical pulses to the heart during refractory period. While there are some promising reports on the therapy's safety and effectiveness in humans, the underlining mechanism remains unknown. We studied the effect of CCM pulses in isolated rabbit cardiomyocytes and isolated rat heart in the presence of beta adrenergic blocker and recorded intracellular calcium transients and contractions. We concluded that the CCM‐induced changes in intracellular calcium handling by cardiomyocytes did not explain the sustained positive iotropic efect in the whole heart and beta‐adrenergic pathway may be involved in the CCM mechanism of action.
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Affiliation(s)
- Ksenia Blinova
- Center for Devices and Radiological Health, US Food and Drug Administration, Silver Spring, Maryland, USA
| | - Jayna Stohlman
- Center for Devices and Radiological Health, US Food and Drug Administration, Silver Spring, Maryland, USA
| | - Victor Krauthamer
- Center for Devices and Radiological Health, US Food and Drug Administration, Silver Spring, Maryland, USA
| | - Alan Knapton
- Center for Drug Evaluation and Research, US Food and Drug Administration, Silver Spring, Maryland, USA
| | - Eric Bloomquist
- Center for Drug Evaluation and Research, US Food and Drug Administration, Silver Spring, Maryland, USA
| | - Richard A Gray
- Center for Devices and Radiological Health, US Food and Drug Administration, Silver Spring, Maryland, USA
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17
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Merchant FM, Sayadi O, Moazzami K, Puppala D, Armoundas AA. T-wave alternans as an arrhythmic risk stratifier: state of the art. Curr Cardiol Rep 2014; 15:398. [PMID: 23881581 DOI: 10.1007/s11886-013-0398-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Microvolt level T-wave alternans (MTWA), a phenomenon of beat-to-beat variability in the repolarization phase of the ventricles, has been closely associated with an increased risk of ventricular tachyarrhythmic events (VTE) and sudden cardiac death (SCD) during medium- and long-term follow-up. Recent observations also suggest that heightened MTWA magnitude may be closely associated with short-term risk of impending VTE. At the subcellular and cellular level, perturbations in calcium transport processes likely play a primary role in the genesis of alternans, which then secondarily lead to alternans of action potential morphology and duration (APD). As such, MTWA may play a role not only in risk stratification but also more fundamentally in the pathogenesis of VTE. In this paper, we outline recent advances in understanding the pathogenesis of MTWA and also the utility of T-wave alternans testing for clinical risk stratification. We also highlight emerging clinical applications for MTWA.
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Affiliation(s)
- Faisal M Merchant
- Cardiology Division, Emory University School of Medicine, Atlanta, GA, USA
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18
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Cardiac contractility modulation increases action potential duration dispersion and decreases ventricular fibrillation threshold via β1-adrenoceptor activation in the crystalloid perfused normal rabbit heart. Int J Cardiol 2014; 172:144-54. [PMID: 24456882 PMCID: PMC3978661 DOI: 10.1016/j.ijcard.2013.12.184] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Revised: 06/19/2013] [Accepted: 12/31/2013] [Indexed: 11/21/2022]
Abstract
BACKGROUND/OBJECTIVES Cardiac contractility modulation (CCM) is a new treatment being developed for heart failure (HF) involving application of electrical current during the absolute refractory period. We have previously shown that CCM increases ventricular force through β1-adrenoceptor activation in the whole heart, a potential pro-arrhythmic mechanism. This study aimed to investigate the effect of CCM on ventricular fibrillation susceptibility. METHODS Experiments were conducted in isolated New Zealand white rabbit hearts (2.0-2.5 kg, n=25). The effects of CCM (± 20 mA, 10 ms phase duration) on the left ventricular basal and apical monophasic action potential duration (MAPD) were assessed during constant pacing (200 bpm). Ventricular fibrillation threshold (VFT) was defined as the minimum current required to induce sustained VF with rapid pacing (30 × 30 ms). Protocols were repeated during perfusion of the β1-adrenoceptor antagonist metoprolol (1.8 μM). In separate hearts, the dynamic and spatial electrophysiological effects of CCM were assessed using optical mapping with di-4-ANEPPS. RESULTS CCM significantly shortened MAPD close to the stimulation site (Basal: 102 ± 5 [CCM] vs. 131 ± 6 [Control] ms, P<0.001). VFT was reduced during CCM (2.6 ± 0.6 [CCM] vs. 6.1 ± 0.8 [Control] mA, P<0.01) and was correlated (r(2)=0.40, P<0.01) with increased MAPD dispersion (26 ± 4 [CCM] vs. 5 ± 1 [Control] ms, P<0.01) (n=8). Optical mapping revealed greater spread of CCM induced MAPD shortening during basal vs. apical stimulation. CCM effects were abolished by metoprolol and exogenous acetylcholine. No evidence for direct electrotonic modulation of APD was found, with APD adaptation occurring secondary to adrenergic stimulation. CONCLUSIONS CCM decreases VFT in a manner associated with increased MAPD dispersion in the crystalloid perfused normal rabbit heart.
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20
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Gui L, Bao Z, Jia Y, Qin X, (Jack) Cheng Z, Zhu J, Chen QH. Ventricular tachyarrhythmias in rats with acute myocardial infarction involves activation of small-conductance Ca2+-activated K+ channels. Am J Physiol Heart Circ Physiol 2013; 304:H118-30. [PMID: 23086994 DOI: 10.1152/ajpheart.00820.2011] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In vitro experiments have shown that the upregulation of small-conductance Ca2+-activated K+ (SK) channels in ventricular epicardial myocytes is responsible for spontaneous ventricular fibrillation (VF) in failing ventricles. However, the role of SK channels in regulating VF has not yet been described in in vivo acute myocardial infarction (AMI) animals. The present study determined the role of SK channels in regulating spontaneous sustained ventricular tachycardia (SVT) and VF, the inducibility of ventricular tachyarrhythmias, and the effect of inhibition of SK channels on spontaneous SVT/VF and electrical ventricular instability in AMI rats. AMI was induced by ligation of the left anterior descending coronary artery in anesthetized rats. Spontaneous SVT/VF was analyzed, and programmed electrical stimulation was performed to evaluate the inducibility of ventricular tachyarrhythmias, ventricular effective refractory period (VERP), and VF threshold (VFT). In AMI, the duration and episodes of spontaneous SVT/VF were increased, and the inducibility of ventricular tachyarrhythmias was elevated. Pretreatment in the AMI group with the SK channel blocker apamin or UCL-1684 significantly reduced SVT/VF and inducibility of ventricular tachyarrhythmias ( P < 0.05). Various doses of apamin (7.5, 22.5, 37.5, and 75.0 μg/kg iv) inhibited SVT/VF and the inducibility of ventricular tachyarrhythmias in a dose-dependent manner. Notably, no effects were observed in sham-operated controls. Additionally, VERP was shortened in AMI animals. Pretreatment in AMI animals with the SK channel blocker significantly prolonged VERP ( P < 0.05). No effects were observed in sham-operated controls. Furthermore, VFT was reduced in AMI animals, and block of SK channels increased VFT in AMI animals, but, again, this was without effect in sham-operated controls. Finally, the monophasic action potential duration at 90% repolarization (MAPD90) was examined in the myocardial infarcted (MI) and nonmyocardial infarcted areas (NMI) of the left ventricular epicardium. Electrophysiology recordings showed that MAPD90 in the MI area was shortened in AMI animals, and pretreatment with SK channel blocker apamin or UCL-1684 significantly prolonged MAPD90 ( P < 0.05) in the MI area but was without effect in the NMI area or in sham-operated controls. We conclude that the activation of SK channels may underlie the mechanisms of spontaneous SVT/VF and suseptibility to ventricular tachyarrhythmias in AMI. Inhibition of SK channels normalized the shortening of MAPD90 in the MI area, which may contribute to the inhibitory effect on spontaneous SVT/VF and inducibility of ventricular tachyarrhythmias in AMI.
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Affiliation(s)
- Le Gui
- Department of Cardiology, Affiliated Hospital of Nantong University, Nantong, Jiangsu, People's Republic of China
- Department of Kinesiology and Integrative Physiology, Michigan Technological University, Houghton, Michigan
| | - Zhiwei Bao
- Department of Cardiology, Affiliated Hospital of Nantong University, Nantong, Jiangsu, People's Republic of China
| | - Yinyu Jia
- Department of Cardiology, Affiliated Hospital of Nantong University, Nantong, Jiangsu, People's Republic of China
| | - Xiaotong Qin
- Department of Cardiology, Affiliated Hospital of Nantong University, Nantong, Jiangsu, People's Republic of China
| | - Zixi (Jack) Cheng
- Biomolecular Science Center, Burnett School of Biomedical Sciences College of Medicine, University of Central Florida, Orlando, Florida; and
| | - Jianhua Zhu
- Department of Cardiology, Affiliated Hospital of Nantong University, Nantong, Jiangsu, People's Republic of China
| | - Qing-Hui Chen
- Department of Kinesiology and Integrative Physiology, Michigan Technological University, Houghton, Michigan
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Armoundas AA, Weiss EH, Sayadi O, Laferriere S, Sajja N, Mela T, Singh JP, Barrett CD, Kevin Heist E, Merchant FM. A novel pacing method to suppress repolarization alternans in vivo: implications for arrhythmia prevention. Heart Rhythm 2012; 10:564-72. [PMID: 23274372 DOI: 10.1016/j.hrthm.2012.12.026] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2012] [Indexed: 10/27/2022]
Abstract
BACKGROUND Repolarization alternans (RA), a pattern of ventricular repolarization that repeats on an every other beat basis, has been closely linked with the substrate associated with ventricular tachycardia/ventricular fibrillation. OBJECTIVE To evaluate a novel method to suppress RA. METHODS We have developed a novel method to dynamically (on R-wave detection) trigger pacing pulses during the absolute refractory period. We have tested the ability of this method to control RA in a structurally normal swine heart in vivo. RESULTS RA induced by triggered pacing can be measured from both intracardiac and body surface leads and the amplitude of R-wave triggered pacing-induced alternans can be locally modulated by varying the amplitude and width of the pacing pulse. We have estimated that to induce a 1 μV change in alternans voltage on the body surface, coronary sinus, and left ventricle leads, a triggered pacing pulse delivered in the right ventricle of 0.04±0.02, 0.05±0.025, and 0.06±0.033 μC, respectively, is required. Similarly, to induce a 1 unit change in Kscore (ratio of alternans peak to noise), a pacing stimulus of 0.93±0.73, 0.32±0.29, and 0.33±0.37 μC, respectively, is required. We have been able to demonstrate that RA can be suppressed by R-wave triggered pacing from a site that is within or across ventricles. Lastly, we have demonstrated that the proposed method can be used to suppress spontaneously occurring alternans in the diseased heart. CONCLUSION We have developed a novel method to suppress RA in vivo.
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Affiliation(s)
- Antonis A Armoundas
- Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, Massachusetts; Division of Cardiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02129, USA.
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