Flush perfusion using Euro-Collins solution vs cooling by means of extracorporeal circulation in heart-lung preservation

Abstract

Single-flush perfusion using modified Euro-Collins solution and donor cooling by extracorporeal circulation represent two concepts of lung preservation currently in use for on-site heart-lung transplantation. The question of which technique is better for safe clinical application of heart-lung transplantation, including extended periods of ischemia and distant organ procurement, currently remains undetermined. Eighteen mongrel dogs, divided in three groups, underwent left lung, heterotopic heart transplantation, leaving the right lung and heart of the recipient in place. Donor organs were obtained from size-matched dogs. In all groups, myocardial preservation was achieved using 10 ml/kg cold potassium cardioplegia. Following flush perfusion of the lung (Euro-Collins solution, 60 ml/kg), six dogs were immediately transplanted (group I). Using the same preservation, organs were stored for 6 hours at 4 degrees C in group II. In group III, organs were cooled using extracorporeal circulation until reaching a rectal temperature of 16 degrees C, harvested, and thereafter stored as in group II. After transplantation, blood supply of the donor heart was assured by selective drainage of the superior vena cava into the right side of the donor heart. Outflow was obtained by end-to-side anastomosis of donor and recipient aorta. The dogs were kept anesthetized, and both lungs were ventilated selectively with an FiO2 of 0.4 for 20 hours or until death. During the postoperative course, the donor heart pumped about one third of the entire cardiac output in all groups. The lowest pulmonary vascular resistance of the transplanted lung was observed in group III. Oxygenation of the transplanted lung revealed no impairment in group I compared with the pretransplant values. By contrast, groups II and III showed a slight decrease of oxygenation within acceptable limits. We therefore conclude that both methods of cardiopulmonary preservation evaluated may allow for an extended ischemic time of up to 6 hours before heart-lung transplantation. Pulmonary vascular resistance was significantly lower in the group preserved by extracorporeal circulation, possibly reflecting superior preservation of lung function by this method.