Cold and warm myocardial protection techniques

Abstract

Cold cardioplegia techniques are effective and reliable in most circumstances requiring cardiac operations. The cold oxygenated crystalloid technique used in our institution provides superior exposure of distal anastomoses and excellent protection when the heart is metabolically intact at the onset of the cross-clamp interval. If the heart is metabolically compromised before the cross-clamp interval, blood cardioplegia techniques appear to have a distinct advantage in the restoration of this compromised muscle. The clinical results from Toronto and our own experimental studies strongly suggest that continuous aerobic cardioplegic techniques are superior to intermittent cold blood techniques in the resuscitation of ischemic myocardium. As normothermic cardiopulmonary bypass and normothermic cardioplegic techniques were introduced in our institution, an increased rate of adverse neurologic outcomes was observed. Modification of the warm blood technique to allow mildly hypothermic, or tepid, cardiopulmonary bypass and cardioplegia temperatures along with prevention of hyperglycemia has reduced the stoke rate with continuous aerobic cardioplegia techniques to the level observed with our other methods of myocardial protection. Tepid continuous aerobic cardioplegia may be the superior technique available in 1994 for the resuscitation of ischemic or metabolically compromised myocardium during the performance of cardiac operations.