Comparison of Functional and Metabolic Assessments in Preservation Techniques for Heart Transplantation

Abstract

The present study compares simple hypothermic storage and hypothermic perfusion in a swine model of heart transplantation using metabolic and functional assessments. In both groups the hearts were initially protected with iso-osmolar potassium Tyers' cardioplegia. The donor hearts of group A were placed in simple hypothermic storage for 5 h. The donor hearts of group B were placed onto a perfusion apparatus for 5 h with perfusion pressure maintained at 28 cm of H2O and a myocardial temperature of 8-10 degrees C. The perfustate consisted of Tyers' solution with the addition of 2 mg/L of mannitol, 12.5 mg/L of glucose, 5 units/L of insulin, and 95% oxygen. The ischemic interval within both groups was 6 h, including orthotoipic transplantation. Investigation was conducted at three time periods: prepreservation (T1) in the donor, and postpreservation (T2) and immediately after loading (T3) in the recipient. Following volume loading for the hypothermic perfusion group there was significant improvement of myocardial function (cardiac index, p less than .05; stroke index, p less than .05) with no significant change in systemic vascular resistance, systemic blood pressure, and heart rate. There was also significant improvement in myocardial performance (p less than .05) for the hypothermic perfusion group following volume loading. Results of fatty acid turnover using 15-p-iodo (123I)-phenylpentodecanoic acid indicate significantly greater increase in metabolic rate for the perfusion group than for the hypothermic storage group. (p less than .05). This indicates improved metabolic status of the heart treated with the hypothermic perfusion technique. We conclude that a combination of functional and metabolic assessments is a good method for deduction of ischemic-reperfusion injury. We also conclude that hypothermic perfusion is superior to hypothermic storage for in vitro preservation of hearts for heart transplantation.