Membrane oxygenation is superior to parabiotic support in blood-reperfused isolated hearts

Isolated heart preparations are often used for myocardial research, but can become complex and difficult when blood is used as the perfusate. We compared the utility and effectiveness of a parabiotic isolated heart system perfused from a support animal to an equivalent system supported by a pediatric membrane oxygenator.

Whole blood reperfused rabbit hearts were supported on a standard Langendorff column by either a parabiotic support animal (n = 10), or an in-line pediatric membrane oxygenator (n = 12). Support animals were mechanically ventilated, and hemodynamically monitored. Perfusate acid-base balance, oxygen, carbon dioxide, bicarbonate, and lactate levels were serially monitored during 120 min of perfusion.

One-hundred percent of experiments supported with an oxygenator completed the evaluation period without instability, while 40% of parabiotic-supported experiments were terminated early because of donor animal hemodynamic instability (P < 0.0001). Parabiotic experiments developed a refractory acidosis (pH at 120 min: parabiotic 7.31 +/- 0.14 versus oxygenator 7.42 +/- 0.4, P = 0.01) related to a progressive rise in lactate (at 120 min: parabiotic 4.0 +/- 2.6 mmol/L versus oxygenator 0.71 +/- 1.3 mmol/L, P < 0.01). Parabiotic experiments demonstrated inferior oxygenation than oxygenator experiments (pO(2) 313 +/- 72 mmHg versus 500 +/- 42 mmHg, P < 0.0001). In this and other experiments, membrane oxygenators have been reused up to 25 times.

Small animal isolated heart experiments perfused with blood are more successful, more efficient, and more cost effective when supported with a membrane oxygenator rather than a support animal. Membrane oxygenators reduce complexity, variability, and animal wastage in isolated heart experiments.