Ischemic preconditioning: cardioprotection for cardiac surgery

Traditionally, surgeons have attempted to minimize myocardial ischemic and reperfusion injury during cardiac procedures by optimizing cardioplegic solutions and modifying the conditions of reperfusion. New evidence suggests that in addition to these two strategies, surgeons may be able to induce myocardial resistance to ischemic injury, which permits immediate functional and metabolic recovery after cardiac operations. Although brief episodes of cardiac ischemia may be associated with mechanical and metabolic dysfunction ("stunning"), they have also been shown to protect against damage resulting from a subsequent prolonged ischemic episode. This phenomenon, known as ischemic preconditioning, has been extensively characterized since its original description in 1986. Recent studies in surgical models of cardioplegic arrest and reperfusion have suggested that the preconditioned, arrested heart may have an increased tolerance to prolonged ischemia and improved functional recovery after reperfusion. The development of a pharmacological agent that induces the preconditioning effect may revolutionize cardioprotection for cardiac surgery. We will review the characteristics of preconditioning and data supporting the application of this natural protective capacity to reduce ischemic damage during cardiac procedures.