Warm blood cardioplegia: ultrastructural and hemodynamic study.

Forty patients with coronary artery disease were included in this study. Half of them received cold crystalloid and cold blood cardioplegia (group 1), and half received normothermic blood cardioplegia (group 2). In group 1, left ventricular stroke work index was 24 +/- 3 g.m/m2 1 hour after the operation, 29 +/- 8 g.m/m2 12 hours after the operation, and 33 +/- 6 g.m/m2 24 hours after the operation. In group 2, left ventricular stroke work index was 37 +/- 4 g.m/m2 1 hour after the operation, 37 +/- 4 g.m/m2 12 hours after the operation, and 44 +/- 7 g.m/m2 24 hours after the operation. Myocardial oxygen extraction 20 minutes after the termination of cardiopulmonary bypass was 0.28 +/- 0.03 in group 1 and 0.44 +/- 0.08 in group 2. Myocardial lactate extraction at the same time was -0.09 +/- 0.02 in patients receiving cold blood cardioplegia and 0.17 +/- 0.07 in patients receiving normothermic blood cardioplegia. Electron microscopic study revealed no calcium accumulation in the mitochondria in group 2 patients, whereas calcium accumulation was present in the other group.