RECOVERY OF CARDIAC ISCHEMIC INSULT AFTER STANDARD HYPOTHERMIC STORAGE VERSUS PRESERVATION WITH PEG-HB

Abstract

INTRODUCTION: Preservation of the heart for transplantation following infusion of cardioplegia and extirpation of a cardiac allograft represents an ischemic insult to the myocardiocytes. This ischemic insult may to a loss of function in the transplanted heart. Hypothermic perfusion preservation with an oxygen hemoglobin carrying solution may avert ischemic injury and lead to improved recovery of cardiac function. The purpose of this study was to compare cardiac function after 8 hrs of continuous hypothermic perfusion with a PEG-Hemoglobin(Hb) solution to hearts preserved by 4 hrs of hypothermic ischemic storage. Non-preserved hearts serve as functional controls. METHODS: The hearts of 28 anesthetized and intubated NZW rabbits were harvested after cold cardioplegic arrest. Group I(n=10) hearts were perfused with a PEG-Hb solution at 20C and 30 mmHg for 8 hours. PO2 was maintained ± 500mm Hg. Group II(n=10) hearts were preserved by cold ischemic storage for 4 hours at 4C. Group III(n=8) were tested immediately after harvest. LV function was measured in the non-working state at 15 min, 1hr, and 2 hrs after transfer to a standard crystalloid Langendorff circuit. RESULTS: Developed LV pressure at 0.5cc LV volume was greater in Group I (75.7±10.3mmHg) than Group II (49.1±5.4mmHg, p = .04) and similar to Group III (69.41±5.1mmHg, p=.6) Maximum-dp/dT at 0.5 cc LV volume was greater in Group I s(−610.6±68.4mmHg/sec) than Group II (−354.8±49.1mmHg/sec, p=.01) and trended toward superiority over Group III(−456.2±44.1mmHg/sec, p=.09). Maximum +dp/dT at 0.5cc LV volume was greater in Group I (964.9±156.6mmHg/sec) than both Group II (428.4±54.9mmHg/sec, p=.004) and Group III(514.6±48.9mmHg/sec, p=.02).FigureCONCLUSIONS: Continuous perfusion preservation of rabbit hearts for 8 hrs with PEG-Hb solution at 30 mmHg and 20 C yields left ventricular function that is superior to 4 hrs of ischemic hypochermic storage. Furthermore, return of cardiac function after perfusion preservation using this PEG-Hb solution may be superior to that obtained in freshly arrested hearts. These data suggest there may occur some recovery of myocardial function during perfusion preservation with this PEG-Hb solution after the ischemic insult of carioplegic arrest. Continuous perfusion preservation using this PEG-Hb solutioon deserves further investigation in large animal transplant models.