The scientific basis for hypocalcemic cardioplegia and reperfusion in cardiac surgery.

The scientific rationale for avoiding the use of calcium-enriched cardioplegic solutions and calcium supplementation during cardioplegic induction and the early phase of reperfusion in open heart surgical procedures is reviewed. The role of the extracellular and intracellular free ionized calcium concentrations during ischemia and reperfusion is explored and the biochemical effects of ischemia on calcium fluxes, adenosine triphosphate levels, and mitochondrial function are discussed. The role of calcium in causing myocardial stunning and the biochemical basis of reperfusion injury are also addressed. Both prolonged ischemia and an increased concentration of Ca2+ during reperfusion have proved to be deleterious. I conclude on the basis of my review that there is no justification for the use of calcium chloride before and during the early phase of reperfusion and that hypocalcemic perfusion is an effective and easily controllable means of myocardial protection.