Effects of canine donor heart preservation temperature on posttransplant left ventricular function and myocardial metabolism.

The generally accepted method of preserving donor heart integrity during transfer is to arrest it with cold cardioplegic solution, then store it in a plastic bag immersed in an iced electrolyte solution. Temperatures between 0 degree C and 4 degrees C are maintained by this method until the heart is transplanted. Although profound hyperthermia best inhibits metabolic processes, it may damage the myocardium. Higher myocardial temperatures may be more advantageous and may result in better preservation. The efficacy of this hypothesis has been investigated in a canine model. The hearts of 40 dogs were isolated, arrested with cold cardioplegia, removed from the animal, and stored at different temperature ranges from 0-3 degree C to 12-15 degrees C for 4 hr. After this time period, the hearts were transplanted into a recipient animal in the cervical heterotopic position. The degree and speed of myocardial functional recovery were monitored by measuring end-systolic elastance generated from pressure-diameter loops using sonomicrometry techniques. Myocardial metabolism was studied simultaneously by monitoring coronary flow, O2, glucose, lactate, pyruvate, and free fatty acid uptakes. The results were compared with those from a control group of hearts transplanted immediately after their removal. Our results indicate that donor heart function was significantly depressed 30 min after heterotopic transplantation, but returned to "control" levels after 2 hr when stored between 0 degrees C and 6 degrees C. Myocardial function remained significantly depressed throughout the 2-hr recovery period in hearts stored at higher (6-15 degrees C) temperatures. Hearts stored at all temperatures continued to extract glucose, lactate, and free fatty acids, but produced significantly higher levels of pyruvate at higher storage temperatures, which may be related to the favored use of free fatty acids. In conclusion, donor hearts stored at colder temperatures for 4 hr regain complete left ventricular function faster than hearts stored at higher temperatures. Our experiments support the presently applied methods of donor heart preservation for 4 hr.