Use of Venovenous Extracorporeal Membrane Oxygenation and an Atrial Septostomy for Pulmonary and Right Ventricular Failure

Background. Right ventricular failure is a major contributor to morbidity and mortality on the lung transplant waiting list. This study was designed to evaluate the effectiveness of an atrial septostomy with venovenous extracorporeal membrane oxygenation (VV-ECMO) as a novel potential bridge to transplantation. Methods. Adult sheep (58 +/- 3 kg; n = 12) underwent a clamshell thoracotomy and instrumentation to measure all relevant pressures and cardiac output (CO). Sheep with tricuspid insufficiency (TI [n = 5]) and without tricuspid insufficiency (OTI [n = 7]) were examined. After creation of a 1-cm atrial septal defect and initiating VV-ECMO, the pulmonary artery (PA) was banded to allow progressive reduction of pulmonary blood flow, and data were collected. Results. The CO in both groups remained unchanged from baseline at all pulmonary blood flow conditions. With TI, the CO was 5.1 +/- 1.2 L/min at baseline versus 5.1 +/- 1.2 L/min with a fully occluded PA (p = 0.99). For OTI, the CO was 4.5 +/- 1.4 L/min at baseline versus 4.5 +/- 1.2 L/min with no pulmonary blood flow (p = 0.99). Furthermore, CO was not affected by the presence of TI (p = 0.76). Mean right ventricular pressures were significantly lower in the TI group (TI = 20.2 +/- 11 mm Hg versus OTI = 29.9 +/- 8.9 mm Hg; p < 0.00001). Right and left atrial mean arterial pressures were not different between both groups (p > 0.5). Lastly, VV-ECMO maintained normal blood gases, with mean O-2 saturations of 99% +/- 4.1% in both groups. Conclusions. Right to left atrial shunting of oxygenated blood with VV-ECMO is capable of maintaining normal systemic hemodynamics and normal arterial blood gases during high right ventricular afterload dysfunction. (Ann Thorac Surg 2011; 91: 144-9) (C) 2011 by The Society of Thoracic Surgeons