Reversible postischemic ventricular dysfunction: biochemical insights

Myocardial stunning, or reversible postischemic ventricular dysfunction, occurs clinically much more frequently than was originally assumed when this phenomenon was first described in experimental studies. Despite the fact that stunned myocardium may appear histologically normal and have a normal metabolic profile, ventricular contractility is severely impaired. In a number of studies using both global and regional stunning models, we have demonstrated impaired oxygen extraction and abnormal patterns of oxygen consumption. In addition, impaired calcium transport or uptake by the sarcoplasmic reticulum occurs and there is sarcolemmal disruption during stunning despite reversibility of the ischemic injury. Although oxygen free radical production is thought to occur only early during postischemic reflow, the use of oxygen radical scavengers in a model of regional stunning was shown to attenuate the ventricular dysfunction.