Influence of long-term oral valsartan on ventricular arrhythmia after myocardial infarction in rabbits / 心血管康复医学杂志

ABSTRACT

Objective: To explore influence of long-term oral valsartan-angiotensin II type 1 receptor blocker on ventricular arrhythmia after myocardial infarction (MI) in rabbits and its possible mechanism. Methods: A total of 24 New Zealand rabbits were randomly divided into sham operation group (n=8), MI group (n=8) and valsartan group (n=8) according to number table. Sham operation group only received thoracotomy without ligation of anterior descending branch of left coronary artery (LAD), while MI group and valsartan group received ligation of anterior descending branch of LAD. Valsartan group received valsartan gavage (10 mg•kg-1•d-1) since the second day after operation, three groups all were fed for 12 weeks. Mono active potential (MAP) of left ventricular myocardial cells of subendocardial myocardium（inner layer myocardium）, subepicardial myocardium（outer layer myocardium）and middle layer myocardium were recorded before MI and 12 weeks after MI, and times of provocative malignant arrhythmias were recorded on 12 weeks after MI in three groups. Results: 1. Ventricular tachycardia or fibrillation (VT/ VF) episodes were markedly decreased in VAL group than that in MI group on 12 weeks after MI [(3.1±0.8) vs. (12.7±1.5), P＜0.05]; 2. After MI 12 w, the action potential duration to 90% repolarization (APD90) of three-layer ventricular myocytes in MI group was prolonged than that before MI [（259.2±22.1）ms,（288.0±25.8）ms,（244.6±22.6）ms vs.（230.1±23.2）ms,（244.2±23.4）ms,（229.0±21.7）ms, P＜0.05 or＜0.01]；but there were no significant difference in APD90 of three layers ventricular myocytes between before and after MI in valsartan group (P>0.05 all); Compared with sham operation group and valsartan group, there was significant prolonged in transmural dispersion of repolarization (TDR) [(18.8±6.2) vs. (23.9±7.7) vs. (37.2±10.2), P0.05). Conclusions: Long-term oral valsartan can significantly reduce malignant ventricular arrhythmia incidence in rabbits after MI, which may be related to improving TDR in rabbits after MI.