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 widespread acceptance because they were either too impractical or complicated to use for remote harvest. We hypothesized that collection and perfusion 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 (40 to 50 kg) were used to perform 16 orthotopic heart transplantations with either continuous perfusion with donor blood (BL, n = 8) or standard hypothermic storage (CON, n = 8). After administration of heparin, hypothermic (4 degrees C) cardioplegic arrest, and donor heart extraction, donor blood (2688 +/- 166 ml) was harvested in the BL group. After filtration for particulate matter, blood perfusion was initiated via 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 myocardial oxygen extraction, lactate release, and acid production. A Millar micromanometer was used to measure left ventricular developed pressures at an end-diastolic pressure of 2 and 10 mm Hg both before and after transplantation.
Results: All pigs (eight of eight) in the BL group were successfully weaned off bypass compared to three of eight in the 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; posttransplantation: 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 release 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 oxygen extraction or acid production during reperfusion.
Conclusions: Perfusion of donor blood improved the ability to wean off bypass after 4 hours of storage. Blood perfusion permitted persistent myocardial metabolism during the ischemic period, which led to improved functional recovery. Harvesting donor blood for subsequent perfusion during prolonged storage may improve the results of orthotopic heart transplantation and allow for more distant procurement of donor organs.