Arterial hypertension, myocardial hypertrophy and disorders of cardiac rhythm induced by ligation of the left coronary artery in the rat

Cardiac hypertrophy and hypertension are major elements in sudden cardiac death in patients with coronary artery disease. To investigate in animals the hypothesis that left ventricular hypertrophy (LVH) and/or hypertension increase the incidence of severe ventricular arrhythmias, we have undertaken a 30 min period of coronary artery ligation in anaesthetized spontaneously hypertensive rats (SHR), normotensive (NT) Wistar Kyoto (WKY) and Wistar (W) rats. Mean systolic blood pressure (SBP) was 190 +/- 4 mmHg in SHR vs 123 +/- 5 mmHg in WKY and 116 +/- 4 mmHg in W (p less than 0.001). LVH index was 2.81 +/- 0.04 in SHR vs 196 +/- 0.03 in WKY and 1.65 +/- 0.05 in W (p less than 0.01). Incidence (IVF) and duration (DVF) of ventricular fibrillation were significantly more elevated in SHR than in NT rats. IVF was 100 p. 100 in SHR vs 36 p. 100 in WKY and 27 p. 100 in W (p less than 0.001); DVF was 61 +/- 17 s in SHR vs 6 +/- 6 s in WKY and W (p less than 0.001). In addition the calcium channel blocker nicardipine (N) has been administered orally to SHR either chronically during eight weeks (20 mg/kg-1 per os twice daily) or acutely as a single dose of 20 mg/kg. After long term treatment (LT) with N the LVH index and SBP were significantly reduced when compared to vehicle treated (VT) SHR; whereas a single administration of N (AT) only decreased SBP without affecting LVH.(ABSTRACT TRUNCATED AT 250 WORDS)