Veno-venous extracorporeal membrane oxygenation with interatrial shunting: a novel approach to lung transplantation for patients in right ventricular failure.

OBJECTIVE

This study evaluated the effectiveness of an atrial septostomy with veno-venous extracorporeal membrane oxygenation in alleviating high afterload right ventricular dysfunction while providing respiratory support. This technique could be applied as a bridge to lung transplantation.

METHODS

Sheep (56±3 kg) underwent a clamshell thoracotomy and hemodynamic instrumentation, including right ventricular pressure and cardiac output. Sheep with and without tricuspid insufficiency (n=5 each) were examined. While sheep were on extracorporeal membrane oxygenation, right ventricular failure was established by banding the pulmonary artery until cardiac output was 40% to 60% of baseline. An extracardiac atrial shunt was created with modified vascular grafts to examine the effect of shunt flow on hemodynamics. Hemodynamic data were thus collected at baseline, during right ventricular failure, and for 1 hour at 100% (fully open), 70%, 50%, and 30% of baseline shunt flow.

RESULTS

Cardiac output was returned to baseline values (tricuspid insufficiency: 5.2±0.2 L/min, without tricuspid insufficiency: 5.3±1.2 L/min) with 100% shunt flow (tricuspid insufficiency: 4.8±1.1 L/min, without tricuspid insufficiency: 4.8±1.0 L/min; P=.15) but remained significantly lower than baseline at 70% to 30% shunt flow. At 100% shunt flow, tricuspid insufficiency shunt flow was 1.4±0.8 L/min and without tricuspid insufficiency shunt flow was 1.7±0.2 L/min. Right ventricular pressure was significantly elevated over baseline values at all shunt flows (P<.001). In the group without tricuspid insufficiency, all sheep died beginning at the 70% shunt condition, whereas all animals with tricuspid insufficiency survived the entire experiment. Normal arterial blood gases were maintained under all conditions.

CONCLUSIONS

An atrial septostomy accompanied by veno-venous extracorporeal membrane oxygenation is capable of eliminating right ventricular failure while maintaining normal arterial blood gases if sufficient shunt flows are achieved. The presence of tricuspid insufficiency improves the efficacy of the shunt.