Susceptibility to ischemia and reperfusion arrhythmias in myocardial hypertrophy: due to flow of injury current?
Left ventricle (LV) hypertrophy is associated with an increased risk of sudden death, which may be due in part to a greater vulnerability to severe ventricular arrhythmias. Our objectives were to determine (i) whether pressure overload-induced LV hypertrophy increases susceptibility to ischemia- and/or reperfusion-induced ventricular fibrillation (VF), and (ii) whether any increased susceptibility is mediated by changes intrinsic to the hypertrophied myocardium. LV pressure overload was induced in rats by abdominal aortic constriction (AC), while controls received sham-operations (SH). Three weeks after the operation, LV weight was 44 +/- 3% greater in AC rats than in SH rats although right ventricle (RV) weights were similar. At this time, isolated hearts (n = 12/group) were subjected to dual coronary perfusion. Alter 15 minutes of aerobic perfusion, either the left or right coronary bed (supplying predominantly LV or RV tissue, respectively) was subjected to 7 minutes of zero-flow ischemia and either 5 minutes of reperfusion (reperfusion study) or 40 minutes of sustained ischemia (ischemia study). AC rats exhibited greater susceptibility than SH rats to both ischemia- and reperfusion-induced ventricular fibrillation, but only when the hypertrophied LV was subjected to ischemia. The increased susceptibility to arrhythmias was not entirely due to a larger ischemic zone, indicating that intrinsic changes within hypertrophied myocarium played a role in arrhythmogenesis.
Shimada
Yasuyuki
Y
Cardiovascular Surgery, Saiseikai Suita Hospital Social Welfare Organization, Saiseikai Imperial Gift Foundation, Osaka, Japan.
Avkiran
Metin
M
D000818:Animals; D001145:Arrhythmias, Cardiac / Q000209:etiology*; D009320:Atrial Natriuretic Factor / Q000096:biosynthesis / Q000235:genetics; D001794:Blood Pressure; D003326:Coronary Circulation; D004198:Disease Susceptibility; D006339:Heart Rate; D017379:Hypertrophy, Left Ventricular / Q000150:complications* / Q000503:physiopathology; D008297:Male; D017202:Myocardial Ischemia / Q000150:complications* / Q000473:pathology / Q000503:physiopathology; D015428:Myocardial Reperfusion Injury / Q000150:complications* / Q000503:physiopathology; D012333:RNA, Messenger / Q000096:biosynthesis; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D017725:Ventricular Pressure
D012333:RNA, Messenger; D009320:Atrial Natriuretic Factor