Myocardial protection: an overview.

The goals of myocardial protection during cardiac surgery are not only to facilitate the operation by providing a quiet bloodless field, thereby facilitating the precision of the operation, but also to avoid iatrogenic injury induced by cardiopulmonary bypass itself or by surgically imposed ischemia. In addition, myocardial protective strategies are geared to preventing reperfusion injury upon resolution of the coronary occlusion and the ultimate release of the aortic cross clamp. Cardioplegia plays a very important role in myocardial protection strategies. Acting as a selective perfusion agent, cardioplegia solutions can alter or inhibit ischemic injury by virtue of hypothermia and asystole. In addition, cardioplegia can be used to avoid reperfusion injury by altering the conditions of its delivery and the composition of the solution using various adjunctive agents and pharmacologic therapies for which cardioplegia solutions serve as a vector. Future strategies, particularly for off-pump surgical procedures, may incorporate systemic delivery of therapeutic agents to the heart directly either in conjunction with or without cardioplegia.