Subnormothermic Machine Perfusion of Neonatal and Small-Sized Pediatric Donor Hearts

Donor heart machine perfusion enables avoidance of prolonged cold ischemia, however the optimal temperature is yet to be elucidated. Given that maintenance of temperature beyond ambient levels demands significant energy, we sought to determine the suitability of room-temperature perfusion preservation of neonatal/pediatric-sized (5-20 kg) piglet donor hearts. A custom device was fabricated suitable for this purpose, with continuous readout of perfusion pressure, flow rate, temperature, and oxygen saturation. Oxygen delivery was automated to keep saturation above 90%. The perfusate consisted of a 1:1 mix of donor whole blood and modified Krebs-Henseleit solution with albumin. Donor hearts were procured from 5 kg (n = 5), 10 kg (n = 3), and 20 kg (n = 5) piglets, and perfused for 10 hours. Subsequently, 20 kg piglet hearts were transplanted. Hemodynamic stability and echocardiographic measurement of donor heart function were evaluated posttransplant. Perfusate parameters were stable through the perfusion interval. Temperature was consistently 23.8 ± 1.6°C. pH (7.35 ± 0.09) and pO 2 (102 ± 29 mm Hg) were steady throughout. Glucose (5.9 ± 1.8 mmol/L) and lactate (2.4 ± 1.5 mmol/L) were metabolized by the heart over the course of perfusion. Transplanted hearts displayed durable hemodynamics and good biventricular function. We conclude that neonatal and pediatric hearts can be safely perfused for extended periods at subnormothermic conditions using blood-based perfusate.