Improved myocardial and pulmonary preservation by metabolic substrate enhancement in the autoperfused working heart-lung preparation.

The autoperfused working heart-lung (AWHL) preparation may provide successful cardiopulmonary preservation for up to 6 hours before transplantation. To determine whether the addition of metabolic substrate could prolong myocardial and pulmonary preservation in the AWHL model, 20 heart-lung blocks were harvested from calves. The brachiocephalic artery and superior vena cava were cannulated with extracorporeal tubing and connected to an elevated reservoir allowing total perfusion through a normothermic autoperfusion circuit. Eight heart-lung blocks were given dextrose and ribose followed by a continuous dextrose-insulin infusion, whereas the remaining 12 specimens received no additional substrates. Myocardial function was assessed by sonomicrometric techniques and pulmonary preservation evaluated by arterial oxygenation on 100% inspired oxygen, static lung compliance, and serial lung biopsies. The addition of substrate prolonged organ survival from 5 +/- 1 to 12 +/- 3 hours (p less than 0.001) and was associated with preservation of myocardial and pulmonary function. Application of substrate addition to the AWHL model will extend the interval of preservation for both heart and heart-lung transplantation.