Use of a low-prime circuit for bloodless heart transplantation in xenotransplant of 5-7 kilogram primates.

There is a great effort to decrease blood product use during open-heart surgery in pediatrics. We were presented with a research challenge to accomplish heart xenotransplantation from donor cynomologous monkey (Macaca fascicularis) to recipient olive baboon (Papio anubis) of 5-7 kilograms without benefit of donor or banked blood products. The purpose of this study was to design and implement a practical, low-volume circuit to minimize hemodilution and avoid the use of blood products. A simple circuit was assembled using a low-volume oxygenator with hardshell venous reservoir, an 1/8-inch arterial line, an 1/4-inch venous line, and gravity drainage. Three xenotransplants were performed and evaluated. The mean recipient weights were 6.3 +/- 0.7 kg. Circuit prime volume was 228 +/- 5.8 mL, and bypass time was 85 +/- 6.7 min. Blood flow rates were 585 +/- 113 mL/min with postmembrane arterial line pressures of 344 +/- 81 mmHg, and patient mean arterial pressures (MAP) of 51.4 +/- 16.7 mmHg. Venous saturations were 63.7 +/- 8.0%. The hematocrit prebypass was 37.4 +/- 3.2, bypass 20.7 +/- 0.9, post-MUF 27.8 +/- 3.3, and 7 days postoperative 24.5 +/- 7.5%. Platelet count was 289 +/- 1.1 K/microL, 147 +/- 37.1 K/microL, and 322 +/- 292.7 K/microL prebypass, postbypass, and 7 days postoperative, respectively. Plasma-free hemoglobin prebypass was 7.5 +/- 4.4 mg/dL and postbypass 22.2 +/- 16.5 mg/dL with no noted hematuria during and after the procedure. All patients survived and were successfully weaned from cardiopulmonary bypass (CPB) with same day extubation. A low-prime circuit for bloodless heart surgery is possible. To achieve low reservoir levels, especially without the use of an arterial line filter (ALF), it is necessary to have a full armament of monitoring and alarm devices.