Long-Term Animal Model of Venovenous Extracorporeal Membrane Oxygenation with Atrial Septal Defect as a Bridge to Lung Transplantation

Abstract

This study evaluated the effectiveness of an atrial septal defect (ASD) with veno-venous extracorporeal membrane oxygenation (vvECMO) as a bridge to transplantation. Sheep (56 ± 3 kg; n = 7) underwent a right sided thoracotomy to create the ASD (diameter = 1 cm) and place instrumentation and a pulmonary artery (PA) occluder. After recovery, animals were placed on ECMO, and the PA was constricted to generate a two-fold rise in right ventricular systolic pressure. Sheep were then maintained for 60 hours on ECMO, and data were collected hourly. Five sheep survived 60 hours. One sheep died due to a circuit clot extending into the RV, and another died presumably due to an arrhythmia. Mean right ventricular pressure (mRVP) was 19±3 mmHg at baseline, averaged 27±7 mmHg over the experiment, but was not statistically significant (p = 0.27) due to one sheep without an increase. Cardiac output (CO) was 6.8±1.2 L/min at baseline, averaged 6.0±1.0 L/min during the experiment, and was statistically unchanged (p = 0.34). Average arterial oxygen saturation and pCO2 over the experiment were 96.8 ± 1.4% and 31.8 ± 3.4 mmHg, respectively. In conclusion, an ASD combined with vvECMO maintains normal systemic hemodynamics and arterial blood gases during a long-term increase in right ventricular afterload.

Use of venous-venous extracorporeal membrane oxygenation in the treatment of postpartum pulmonary hypertension crisis

“…It has been reported that ECMO plays a bridging role before lung transplantation in patients with PH. 13,15,17 However, we believe that the use of VV-ECMO support in patients with PH in the early stage of pulmonary crisis might prevent further deterioration of cardiopulmonary function and thus avoid lung transplantation. There are reports of cases in which VV-ECMO has been used successfully before pulmonary crisis.…”

“…The oxygen saturation of the two groups remained normal, confirming that fully oxygenated blood was shunted from the right atrium to the left. 15 Relevant patients who had VV-ECMO combined with atrial septostomy have maintained normal systemic haemodynamics and normal arterial oxygenation after high-right-ventricular afterload dysfunction. 16 In this VSD patient, using the VV-ECMO configuration significantly improved the systemic oxygenation status.…”

“…The oxygen saturation of the two groups remained normal, confirming that fully oxygenated blood was shunted from the right atrium to the left. 15…”

Venovenous extracorporeal membrane oxygenation in patients with atrial septal defects

“…There have been large animal studies demonstrating the benefit of an ASD for oxygenation in animals with high pulmonary artery pressures undergoing VV-ECMO. 4 This model has been developed as a potential bridge to lung transplantation in patients with severe pulmonary hypertension, with the idea of placing these patients on V-ECMO and creating an atrial septostomy.…”

Percutaneous Transseptal Extracorporeal Membrane Oxygenation to Rescue a Failing Right Ventricle in an Animal Model

“…An atrial septostomy allows high pressure from the right atrium (RA) to decompress into the left atrium (LA). 4 The downside to atrial septostomy is that the blood is deoxygenated, which cannot be tolerated by hypoxic patients with severe lung disease. 4 Also, it has unregulated flow so it can overwhelm a deconditioned LV.…”