RECOVERY OF MYOCARDIAL-FUNCTION AFTER REPETITIVE EPISODES OF REVERSIBLE ISCHEMIA

The question of whether recovery of regional myocardial function after repetitive, reversible ischemia differs from recovery after a single episode of myocardial ischemia remains controversial. Therefore, eight conscious dogs were instrumented with ultrasonic dimension transducer s and left ventricular micromanometers. Each animal underwent (in rand om sequence, 72 h apart) a single 15-min left anterior descending coro nary arterial (LAD) occlusion and two 15-min LAD occlusions separated by 1 h of reperfusion. The preload recruitable work area (PRWA; the ar ea beneath the regional stroke work vs. end-diastolic length relations hip) quantified regional myocardial performance. Repetitive ischemia s ignificantly delayed recovery of PRWA over the first 24 h (P < 0.05). Although postischemic myocardial creep resolved rapidly after single o cclusion, double occlusion prevented recovery of creep during the firs t 4 h of reperfusion. The recovery time course of PRWA paralleled the resolution of myocardial creep, suggesting that creep contributed sign ificantly to delayed functional recovery and that myocardial ''stunnin g'' after repetitive ischemia may result in part from interaction betw een postischemic diastolic properties and systolic dysfunction.