Prevention of ischemia-reperfusion injury by metabolic substrate—Mechanisms and surgical implications

Summary Background Despite new insights into mechanisms contributing to ischemia-reperfusion injury, new therapeutic interventions to reduce ischemia-reperfusion injury have thus far not been available for routine clinical use. In order to restore sufficient postischemic contractile function, such a therapy would be of great value in conjunction with reperfusion therapy for acute myocardial infarction and after cardiac surgery. This paper examines whether metabolic disturbances and energy depletion contribute to ischemia-reperfusion injury and whether metabolic interventions could alleviate ischemia-reperfusion injury. Methods Experimental and clinical studies are reviewed for evidence of a beneficial effect of metabolic interventions, in particular of increased glycolytic substrate, on ischemia-reperfusion injury. Results During ischemia, metabolism of the myocardium shifts to a preferential use of carbohydrates. Increased glycolytic substrate i.e. glucose-insulin-potassium infusion as metabolic support for ischemic myocardium is beneficial in reducing ischemia-reperfusion injury by increasing energy production via anaerobic glycolysis, decreasing circulating free fatty acids and intracellular free fatty acid accumulation, maintaining ion homeostasis, reducing cellular edema, and scavenging free radicals. During reperfusion, glucose-insulin-potassium, apart from increasing glycolysis and decreasing free fatty acid metabolism, provides substrate for replenishment of the citric acid cycle, which is important for optimal energy transfer. Conclusions During ischemia, glucose-insulin-potassium preserves energy reserves and maintains cell viability. During reperfusion, glucose-insulin-potassium improves energy transfer and increases contractile function. Experimental and clinical studies have proven glucose-insulin-potassium to be a safe and effective intervention to reduce ischemia-reperfusion injury.