Sub-normothermic preservation of donor hearts for transplantation using a novel solution, Somah: A comparative pre-clinical study

BACKGROUND: Hearts preserved ex vivo at extreme hypothermia (4 degrees C) undergo time-dependent irreversible injury. Our studies using a novel solution, Somah, suggest that hearts are viably preserved at 21 degrees C. In this study we evaluate the relative efficacy of Somah for preservation of hearts at 21 degrees C when compared with the clinically used Celsior and University of Wisconsin (UWS) solutions. METHODS: Porcine hearts arrested by cardioplegia at 21 degrees C using Somali, Celsior or UWS solution were stored in the respective solutions at 21 degrees C (n = 5) for 5 hours and then reperfused ex vivo for functional assessment. We assessed development of edema, cardiac tissue high-energy phosphate (HEP; ATP + creatine phosphate) levels and release of cardiac enzymes. Alterations in left ventricular wall thicknesses and functional parameters were examined by 2-dimensional (2D) echocardiography. Changes in myocardial oxygen consumption (MVO2) and lactate utilization were assessed at reperfusion. RESULTS: Heart weights were unaltered during 5-hour storage in all groups. After storage, HEP levels were 28.33 +/- 5.51, 10.20 +/- 2.78 and 5.92 +/- 1.46 nmol/liter per milligram protein (p < 0.001) in the Somali, Celsior and UWS group hearts, respectively. Upon reanimation, 2D echocardiography showed edema in the Celsior and UWS hearts; prompt attainment of physiologic function was associated with rapid establishment of aerobic metabolism not requiring stimulatory interventions in the Somali hearts, but not in the Celsior/UWS hearts. Percent fractional area change, ejection fraction and stroke volume were significantly higher (p < 0.001) in Somali hearts than in Celsior and UWS group hearts. CONCLUSIONS: Increased synthesis of BEP, rapid metabolic switch and optimal function together provide evidence that hearts procured for transplantation are preserved in a superior viable condition at 21 degrees C with Somali, but not with other commonly used clinical preservation solutions. Published by Elsevier Inc.