Importance of substrate enhancement for long-term heart preservation.

These experiments tested the hypothesis that addition of pyruvate to a preservation medium would improve postpreservation cardiac function as quantified in an isolated working heart model after heterotopic transplantation. Four groups of rabbit hearts were studied (n = 5 per group): fresh controls, fresh hearts perfused as isolated working hearts; surgical controls, fresh hearts transplanted heterotopically and reperfused with blood for 75 minutes before being studied as isolated hearts; preserved without pyruvate, hearts perfusion-preserved with oxygenated extracellular-type crystalloid medium; preserved with pyruvate, same same as the group without pyruvate, but medium contained 20 mmol/L pyruvate. After preservation, the hearts in the two preserved groups were transplanted and studied as isolated hearts. Total ex vivo time for the preserved hearts was 24.5 +/- 0.2 hours. During preservation, glucose was not consumed by hearts in either preserved group. Pyruvate was used by the hearts to which it was provided (22.9 +/- 2.7 mumol pyruvate x hour-1 x gm dry weight-1). Performance of transplanted surgical control hearts was not significantly different from that of fresh controls. Function of the pyruvate-preserved hearts was similar to that of the fresh and surgical controls except that left ventricular peak systolic pressure and peak rate of pressure development were lower and that left ventricular end-diastolic pressure was higher for the pyruvate-preserved hearts. The hearts preserved without pyruvate had significantly lower compliance and function compared to the other three groups, which was evident in all indexes of contractility and output. We conclude that hearts preserved with pyruvate-containing crystalloid medium had better postpreservation, posttransplantation function than hearts preserved without pyruvate, although there was slight loss of compliance and decreased contractile function in the pyruvate-preserved hearts compared to controls.