Insulin cardioplegia for elective coronary bypass surgery

Background: Improved methods of myocardial preservation are required to red uce the morbidity and mortality of coronary bypass surgery for high-risk su bgroups. Metabolic stimulation with insulin, glucose solutions, or both has been proposed as a method to preserve the ischemic myocardium. We performe d a prospective, double-blind, randomized trial to evaluate the effects of insulin and glucose as cardioplegic activities when used as part of a tepid continuous blood cardioplegic strategy. Methods: We randomized 56 male patients undergoing elective isolated corona ry bypass surgery to 1 of 4 cardioplegic groups containing either 42 or 84 mmol/L glucose with or without 10 IU/L of insulin. Perioperative assessment s of myocardial metabolism and left ventricular function were performed. Results: Insulin-enhanced cardioplegia was associated with beneficial effec ts on both myocardial metabolic and functional recovery after cardioplegic arrest. Insulin's effect was independent of the ambient glucose concentrati on. Conclusions: Cardioplegic formulations containing a 42 mmol/L concentration of glucose and a 10 IU/L concentration of insulin provide significant bene fit to patients undergoing isolated coronary bypass surgery. The clinical e ffect of these formulations will need to be assessed in high-risk subgroups of patients, such as those with unstable angina, recent myocardial infarct ion, or poor left ventricular function.