An Ambulatory Pulmonary and Right Heart Assist Device (OxyRVAD) in an Ovine Survival Model

Background: To develop ambulatory total respiratory and right heart assistance for up to 4 weeks as a bridge to lung transplantation, we coupled a compact gas exchange device with a right ventricular assist device (RVAD), a compact rotary blood pump, to create an "OxyRVAD.". Methods: Our ambulatory OxyRVAD includes a portable (4 × 4 × 7-cm) centrifugal pump with heparin saline-purged needle roller bearings and an ultra-low-resistant gas exchange device (BioLung, MC3, Ann Arbor, MI). In 6 anesthetized sheep, the main pulmonary artery (PA) and right atrium (RA) were exposed through a left fourth intercostal thoracotomy. A 12-mm outer diameter vascular graft was anastomosed (end-to-side) to the main PA, and a VAD atrial cannula was placed into RA through the RA appendage. The pump and gas exchange device were interposed in circuit for RA-PA support. Results: All 6 sheep survived OxyRVAD insertion. Four sheep survived the 5-day experiment. One was euthanized at 48 hours owing to pump electrical failure (wiring) and another at 72 hours owing to pump bearing failure (broken heparin purge line). One sheep needed replacement of a BioLung due to internal thrombi. OxyRVAD flow was stable (range, 3.57-4.30 liters/min). Carbon dioxide removal was constant during experiment (range, 88.35 ± 6.12 ml/min at onset to 141.38 ± 5.48 ml/min at the 96th hour). Oxygen transfer decreased from 161.8 ± 8.8 to 79.7 ± 31.4 ml/min at the 96th hour (p = 0.045). Conclusion: Our ambulatory OxyRVAD provided total assistance of right heart and lungs in normal awake sheep for up to 5 days.