Reperfusion adequacy and functional recovery

Ischemic myocardium undergoes many physiologic changes, including alterations in contractile function, histologic condition, and oxygen utilization. Reperfusion of ischemic myocardium may reverse some of these changes; however, the level of reperfusion needed for adequate functional recovery, as opposed to myocyte salvage, remains controversial. This study examines the effects of varying levels of reperfusion following ischemia on functional parameters of recovery. Isolated rabbit hearts were subjected to global ischemia at 37 degrees C for 10, 20, or 45 min. The hearts were reperfused at either mean normal baseline pressure (80 mm Hg), one half baseline (40 mm Hg), or one fourth baseline (20 mm Hg). With reperfusion, although all hearts retained the compensatory metabolic ability to upregulate oxygen extraction, reduction of reperfusion pressure resulted in depression of contractility and myocardial oxygen consumption, especially with low-pressure reperfusion. These findings suggest that all levels of reperfusion are not equal for optimal myocardial functional recovery. As minimal reperfusion may result in persistent stunning of myocardium, other means of enhancing reperfusion, such as percutaneous transluminal coronary angioplasty or coronary artery bypass grafting, should be considered.