Myocardial protection during ischemic cardiac arrest. Possible deleterious effects of glucose and mannitol in coronary infusates.

Cardioplegic protective infusates are designed to induce rapid diastolic arrest and also to reduce or delay the onset of ischemic damage. As this study shows, the use of such infusates can greatly improve postischemic recovery of cardiac function. A number of investigators include glucose, insulin, or mannitol in their infusates in an attempt to increase the amount of protection afforded to the ischemic myocardium. Using an isolated, working rat heart model of cardiopulmonary bypass and ischemic cardiac arrest, we have shown that under certain conditions these additives can be deterimental to tissue protection. The deleterious effects of glucose and mannitol are dose dependent and can be modified by the inclusion of insulin in the infusate. The damaging effects of glucose appear to be both osmotic and metabolic in origin and those of mannitol, purely osmotic. The effects of insulin are complex and may affect a number of cellular processes.