Yen-Yu Lu1,2, Shih-Yu Huang2,3, Yung-Kuo Lin4,5,6, Yao-Chang Chen7, Yi-Ann Chen8, Shih-Ann Chen9,10, Yi-Jen Chen4,5,11,12. 1. Division of Cardiology, Sijhih Cathay General Hospital, New Taipei City, Taiwan. 2. School of Medicine, College of Medicine, Fu Jen Catholic University, New Taipei City, Taiwan. 3. Division of Cardiac Electrophysiology, Cardiovascular Center, Cathay General Hospital, Taipei, Taiwan. 4. Taipei Heart Institute, Taipei Medical University, Taipei, Taiwan. 5. Division of Cardiovascular Medicine, Department of Internal Medicine, Wan Fang Hospital, Taipei Medical University, 111 Hsin-Lung Road, Sec. 3, Taipei 116, Taiwan. 6. Division of Cardiology, Department of Internal Medicine, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan. 7. Department of Biomedical Engineering, National Defense Medical Center, Taipei, Taiwan. 8. Division of Nephrology, Sijhih Cathay General Hospital, New Taipei City, Taiwan. 9. National Yang-Ming University, School of Medicine, Taipei, Taiwan. 10. Heart Rhythm Center, Division of Cardiology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan. 11. Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan. 12. Cardiovascular Research Center, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan.
Abstract
AIMS: Ventricular arrhythmia (VA) frequently occurs in fatty infiltrative cardiomyopathy or epicardial adipose tissue (EAT) abundant hearts. Right ventricular outflow tract (RVOT), commonly covered with EAT, is vital for VA genesis. This study explored whether EAT contributes to RVOT arrhythmogenesis. METHODS AND RESULTS: Conventional microelectrodes and whole-cell patch clamp were used to record electrical activity and ionic currents in rabbit RVOT tissue preparation or isolated single cardiomyocytes with or without (control) connected EAT. Epicardial adipose tissue-connected (N = 6) RVOT had more portions of fibrosis than did control (N = 5) RVOT (160.3 ± 23.2 vs. 91.9 ± 13.4 μm2/mm2, P < 0.05). Epicardial adipose tissue-connected RVOT cardiomyocytes (n = 18) had lower negative resting membrane potential (-68 ± 1 vs. -73 ± 2 mV, P < 0.05); smaller action potential (AP) amplitude (108 ± 4 vs. 135 ± 6 mV, P < 0.005); and longer 90%, 50%, and 20% of AP duration repolarization (361 ± 18 vs. 309 ± 9 ms, P < 0.05; 310 ± 17 vs. 256 ± 13 ms, P < 0.05; and 182 ± 19 vs. 114 ± 24 ms, P < 0.05, respectively) than did control (n = 13) RVOT cardiomyocytes. Moreover, compared with control RVOT cardiomyocytes, EAT-connected RVOT cardiomyocytes had larger transient outward potassium currents, similar delayed rectifier potassium currents, smaller L-type calcium currents, and inward rectifier potassium currents. After ajmaline (10 μM, a sodium channel blocker) superfusion, high VA inducibility was observed through rapid pacing in EAT-connected RVOT but not in control RVOT. CONCLUSIONS: Epicardial adipose tissue exerts distinctive electrophysiological effects on RVOT with a propensity towards VA induction, which might play a role in lipotoxicity pathogenesis-related ventricular arrhythmogenesis. Published on behalf of the European Society of Cardiology. All rights reserved.
AIMS: Ventricular arrhythmia (VA) frequently occurs in fatty infiltrative cardiomyopathy or epicardial adipose tissue (EAT) abundant hearts. Right ventricular outflow tract (RVOT), commonly covered with EAT, is vital for VA genesis. This study explored whether EAT contributes to RVOT arrhythmogenesis. METHODS AND RESULTS: Conventional microelectrodes and whole-cell patch clamp were used to record electrical activity and ionic currents in rabbit RVOT tissue preparation or isolated single cardiomyocytes with or without (control) connected EAT. Epicardial adipose tissue-connected (N = 6) RVOT had more portions of fibrosis than did control (N = 5) RVOT (160.3 ± 23.2 vs. 91.9 ± 13.4 μm2/mm2, P < 0.05). Epicardial adipose tissue-connected RVOT cardiomyocytes (n = 18) had lower negative resting membrane potential (-68 ± 1 vs. -73 ± 2 mV, P < 0.05); smaller action potential (AP) amplitude (108 ± 4 vs. 135 ± 6 mV, P < 0.005); and longer 90%, 50%, and 20% of AP duration repolarization (361 ± 18 vs. 309 ± 9 ms, P < 0.05; 310 ± 17 vs. 256 ± 13 ms, P < 0.05; and 182 ± 19 vs. 114 ± 24 ms, P < 0.05, respectively) than did control (n = 13) RVOT cardiomyocytes. Moreover, compared with control RVOT cardiomyocytes, EAT-connected RVOT cardiomyocytes had larger transient outward potassium currents, similar delayed rectifier potassium currents, smaller L-type calcium currents, and inward rectifier potassium currents. After ajmaline (10 μM, a sodium channel blocker) superfusion, high VA inducibility was observed through rapid pacing in EAT-connected RVOT but not in control RVOT. CONCLUSIONS: Epicardial adipose tissue exerts distinctive electrophysiological effects on RVOT with a propensity towards VA induction, which might play a role in lipotoxicity pathogenesis-related ventricular arrhythmogenesis. Published on behalf of the European Society of Cardiology. All rights reserved.