Prolonged preservation of the blood-perfused canine heart with glycolysis-promoting solution

Abstract

Background. Prolonged ischemia and inadequate myocardial preservation remain significant perioperative risk factors in cardiac transplantation. Long-term preservation techniques that have been effective in small rodent hearts have not been as effective in larger animal models or in clinical studies. We developed a cardioplegia solution formulated to promote high-energy phosphate production from glycolysis and determined its efficacy in a blood perfused canine heart model subjected to 24 hours of ischemia. Methods. Hearts harvested from adult dogs (n = 6 per group) were flushed with a histidine-buffered cardioplegia solution containing glucose or University of Wisconsin solution. The hearts were maintained at 4°C for 24 hours then reperfused with autologous blood. After reperfusion, left ventricular pressures were measured with an intracavitary balloon at varying balloon volumes and compared with control nonischemic hearts. Predicted stroke volume and ejection fraction were calculated at an end-systolic pressure of 70 mm Hg and end-diastolic pressure of 15 mm Hg. Results. Developed pressure was better preserved in the hearts that received histidine-buffered solution (93 ± 9 versus 38 ± 7 mm Hg, p < 0.05), along with a higher end-diastolic volume at 15 mm Hg (31 ± 3 versus 22 ± 2 mL histidine-buffered versus University of Wisconsin solutions, respectively, p < 0.05). Stroke volume and ejection fraction were also higher in the histidine group (17 ± 2.5 versus 2.3 ± 1.2 mL and 50% ± 3.5% versus 9% ± 4.5%, respectively) in the presence of dobutamine. Conclusions. The highly buffered glycolysis-promoting cardioplegia solution provided effective preservation of the blood perfused canine heart with superior recovery of pump performance after 24 hours of hypothermic ischemia compared with University of Wisconsin solution in this model.