Insulin (GIK) improves myocardial metabolism in patients during blood cardioplegia

The aim of this study was to test the hypothesis that abnormalities of myoc ardial substrate metabolism during blood cardioplegic aortic cross-clamping and early reperfusion are attenuated further by insulin(GIK) than by alpha -ketoglutarate enrichment of blood cardioplegia alone. Twenty-eight males ( 47 to 78 years) undergoing coronary artery bypass grafting (CABG) participa ted in a prospective, controlled, randomized study. All patients had cc-ket oglutarate-enriched blood cardioplegia. Insulin(GIK) was infused in 13 pati ents during aortic cross-clamping. Insulin(GIK) prevented lactate release d uring cardioplegia (1.5 +/- 15 vs -44 +/- 14 mu mol/min, p = 0.04), and a s ignificant extraction of lactate was induced shortly after declamping the a orta (15 +/- 3 vs 2 +/- 1%, p = 0.001). Free fatty acid uptake was reduced after cardioplegic cross-clamping (5.7 +/- 1.6 vs 16.0 +/- 3.8 mu mol/min, p = 0.02). More positive/less negative levels of alanine, aspartate, glutam ine, glycine, ornithine, taurine and tyrosine were found in all the insulin -treated patients. We conclude that insulin(GIK) attenuates abnormalities o f myocardial substrate metabolism during blood cardioplegic aortic cross-cl amping and early reperfusion further than is obtained with alpha-ketoglutar ate enrichment of blood cardioplegia alone.