PRECONDITIONING DURING WARM BLOOD CARDIOPLEGIA

Objective: Preconditioning describes the cardioprotective effects of m ultiple brief episodes of warm ischemia. The purpose of the study was to determine whether warm ischemia, during the intermittent delivery o f warm blood cardioplegia, would induce preconditioning during cardiop legia arrest. Methods: Dogs, 15, were randomized to a preconditioning protocol or to serve as controls. The control group received 60 min of continuous warm blood cardioplegia (WBC) followed by 30 min of warm a rrested ischemia. The preconditioned group were arrested with WBC and then underwent three consecutive cycles consisting of 10 min of warm i schemia followed by 10 min of reperfusion. Reperfusion was provided by a continuous infusion of WBC. The preconditioning protocol was follow ed by 30 min of warm arrested ischemia. Myocardial functional recovery was assessed before cardiopulmonary bypass and cardioplegia arrest an d again 30, 60 and 90 min after the arrest. Pressure-volume loops were used to measure the maximum elastance of the left ventricle (E-max), diastolic compliance, and used to calculate preload recruitable stroke work area. Results: Myocardial functional recovery was better preserv ed after 30 min of warm arrested ischemia in those animals that had be en preconditioned. Conclusion: Preconditioning may be induced when war m blood cardioplegia is delivered intermittently during cardioplegia a rrest. (C) 1997 Elsevier Science B.V.