BLOOD-FLOW IN MYOCARDIAL HIBERNATION

Myocardial hibernation is a state of persistently impaired left ventri cular function in patients with coronary artery disease that improves after revascularization. it was thought to be caused by a chronic redu ction in resting myocardial blood flow in a segment subtended by a dis eased coronary artery. However, recent studies using positron emission tomography have demonstrated that absolute myocardial blood flow (mL/ min/g) to hibernating myocardium is within normal limits in most patie nts. The authors hypothesize that hibernating myocardium may be the re sult of repetitive myocardial stunning, that is, the reversible contra ctile dysfunction occurring after an episode of myocardial ischemia de spite the return of blood flow to normal. Myocardial stunning has been demonstrated in humans in different clinical settings, and recent stu dies have provided evidence that repetitive episodes of exercise induc ed ischemia can lead to cumulative and prolonged left ventricular dysf unction akin to that observed in hibernating myocardium.