Modified reperfusate after long-term preservation of the heart

Warm (30 degrees C) blood cardioplegia (K = 22 mEq/L) with glutamate (26 mmol/L) as a reperfusate was compared with unmodified blood reperfusion after prolonged hypothermic storage of the isolated canine heart. After cardioplegic arrest, three groups of hearts (n = 5 each) were excised and stored at 2 degrees C. In groups 1 and 2, reperfusion with unmodified blood was undertaken after six and 24 hours of storage, respectively, and in group 3, reperfusion with modified warm blood cardioplegia containing glutamate was administered after 24 hours of storage. After reperfusion, no significant difference in left ventricular developed pressure was noted between groups 1 (110 +/- 15 mm Hg), 2 (127 +/- 14 mm Hg), and 3 (98 +/- 13 mm Hg). Similarly, no difference in maximum rate of rise of left ventricular pressure was noted between groups 1 (1,456 +/- 171 mm Hg/s), 2 (1,905 +/- 395 mm Hg/s), and 3 (1,450 +/- 291 mm Hg/s). Group 3 (modified reperfusate) had improved diastolic compliance compared with group 2 (0.776 mm Hg/mL versus 1.395 mm Hg/mL; p less than 0.02). We conclude that our modified reperfusate improves diastolic function after 24 hours of hypothermic storage, but does not result in improved systolic function.