DONOR BLOOD PERFUSION IMPROVES MYOCARDIAL RECOVERY AFTER HEART-TRANSPLANTATION

Background: Improved methods of donor heart preservation may allow for prolonged storage and permit remote procurement. Previous attempts to use oxygenated perfusion circuits during storage have not gained wide spread acceptance because they were either too impractical or complica ted to use for remote harvest. We hypothesized that collection and per fusion of donor blood during prolonged storage may improve myocardial recovery. Our aim was to devise a safe, simple, cost-effective system that could be used in any hospital setting. Methods: Yorkshire pigs (4 0 to 50 kg) were used to perform 16 orthotopic heart transplantations with either continuous perfusion with donor blood (BL, n = 8) or stand ard hypothermic storage (CON, n = 8). After administration of heparin, hypothermic (4 degrees C) cardioplegic arrest, and donor heart extrac tion, donor blood (2688 +/- 166 mi) was harvested in the BL group. Aft er filtration for particulate matter, blood perfusion was initiated vi a a standard intravenous transfusion apparatus at room temperature (20 degrees C) and a pressure of 60 mm Hg and maintained during storage. Arterial and coronary sinus blood samples were obtained to examine myo cardial oxygen extraction, lactate release, and acid production. A Mil lar micromanometer was used to measure left ventricular developed pres sures at an end-diastolic pressure of 2 and 10 mm Hg both before and a fter transplantation. Results: All pigs (eight of eight) in the BL gro up were successfully weaned off bypass compared to three of eight in t he CON group (p < 0.01). Developed pressures (at left ventricular end- diastolic pressure = 10 mm Hg) was improved in the BL group (mean +/- SD: baseline: BL: 90 +/- 16 mm Hg vs CON: 83 +/- 12 mm Hg, p = NS; pos ttransplantation: BL: 66 +/- 8 mm Hg vs CON: 35 +/- 29 mm Hg, p < 0.05 ). Similarly, maximum dP/dt was higher in the BL group. Lactate releas e was higher at cross-clamp removal in the BL group (2.4 +/- 0.3 mmol/ L vs 0.7 +/- 0.2 mmol/L, p < 0.01). There were no differences in oxyge n extraction or acid production during reperfusion. Conclusions: Perfu sion of donor blood improved the ability to wean off bypass after 4 ho urs of storage. Blood perfusion permitted persistent myocardial metabo lism during the ischemic period, which led to improved functional reco very. Harvesting donor blood for subsequent perfusion during prolonged storage may improve the results of orthotopic heart transplantation a nd allow for more distant procurement of donor organs.