Hyperkalemia in cardioplegic solutions causing increased cholesterol accumulation in vein grafts

Abstract

Hyperkalemic cardioplegic solutions are frequently infused through vein grafts during aorta-coronary bypass operations. Although some reports have suggested the potential for physical damage to grafts by such exposure, the effects of these solutions on graft atherogenesis have not been studied. We evaluated the influence of potassium and colloid content of cardioplegic solutions on graft cholesterol accumulation in our established animal model of graft atherogenesis. Fourteen cephalic vein grafts were interposed bilaterally in the femoral arteries of seven normolipemic stump-tailed macaque monkeys. Before grafting, each vein was distended at 350 torr for 1 minute with autologous blood. Half of each vein was then filled for 30 minutes with either balanced crystalloid solution or with balanced crystalloid plus albumin (5 mg/ml). The other half of the vein was filled with the same solution plus potassium chloride (27 mEq/L). Grafts were harvested at 12 weeks. Cholesterol content was significantly greater (p less than 0.01) in graft segments exposed to hyperkalemia than in their control counterparts. Onconicity had no effect on cholesterol content. In this animal model, prolonged exposure of vein grafts to hyperkalemic cardioplegic solutions caused increased lipid uptake. This finding may presage accelerated atheromatous degeneration.