Recovery of sheep hearts after perfusion preservation or static storage with crystalloid media

These experiments were designed to evaluate the viability of large hearts after preservation by use of procedures that have shown good results with small animal hearts. Efficacy of novel long-term preservation protocols should be documented with a large animal model before such procedures can be adopted for clinical use. We studied the recovery of sheep hearts that were perfusion-preserved in media containing two different substrate mixtures and hearts stored without perfusion either in University of Wisconsin solution modified to maintain tissue adenosine triphosphate content or in Stanford solution.

Six groups of sheep hearts were studied: I, fresh nonpreserved controls; II, hearts perfusion-preserved at 11 degrees C for 24 hours by use of an oxygenated extracellular-type medium with pyruvate + glucose substrate; III, hearts preserved as for II but with aspartate + glutamate + glucose substrate; IV, hearts stored without perfusion at 3 degrees C for 24 hours in University of Wisconsin solution containing 2,3-butanedione monoxime 30 mmol/L, CaCl2 1 mmol/L, and fresh reduced glutathione 3 mmol/L; V, hearts stored without perfusion at 3 degrees C for 4 hours in Stanford solution; VI, hearts preserved as for II but without perfusion. Recovery was measured for 6 hours in a Langendorff model, perfused with an erythrocyte + albumin medium.

Hearts that were perfusion-preserved with both substrate mixtures and hearts stored in modified University of Wisconsin solution recovered function that was not significantly different from control subjects. Hearts stored in Stanford medium did not recover as well as did groups II, III, and IV. Left ventricular pressure and peak rate of left ventricular relaxation of the Stanford group were lower, and left ventricular enddiastolic pressure was higher, than those values for controls (repeated measures analysis of variance; Dunnett's procedure). The group VI hearts did not recover function at all.

The results suggest that large hearts preserved with medium containing either aspartate + glutamate + glucose or pyruvate + glucose have comparable recovery after long-term perfusion preservation. Aspartate + glutamate may offer advantages for clinical use because of their lower production of lactate and better chemical stability compared with pyruvate. Static storage in modified University of Wisconsin solution also produced viable hearts with recovery comparable to perfusion-preserved aspartate + glutamate + glucose hearts. Tests of these preservation media and procedures with large transplanted hearts are warranted.