Development of an implantable small right ventricular assist device

Currently, at least two permanent implantable left ventricular assist devic es (LVADs) are used clinically. Unfortunately, there is no small implantabl e right ventricular assist device (RVAD) available, even though at least 25 -30% of this patient population has right ventricular failure. If a small i mplantable RVAD were available, biventricular assist could support patients with right ventricular failure. A small atraumatic and antithrombogenic RV AD is being developed to meet this clinical need. This small centrifugal bl ood pump, the Gyro PI pump, is 6.5 cm in diameter and 4.6 cm in height and has three unique characteristics to prevent thrombus formation: (1) the dou ble pivot bearing and magnetic coupling system enable this pump to be compl etely sealless; (2) the secondary Vanes at the bottom of the impeller accel erate the blood flow and prevent blood stagnation; and (3) the eccentric in let port enables the top female bearing to be embedded into the top housing and decrease blood cell trauma. The inflow conduit consists of a wire rein forced tube and a hat-shaped tip that is biolized with gelatin to create a thrombus resistant material. This conduit is directly implanted into the ri ght ventricle, and the outflow conduit is anastomosed to the PA. The pump c an be implanted inside the abdominal wall or in the thoracic cavity. Biocom patibility of this pump was proved in two calves by thrombus free implantat ion as an LVAD for 284 days and 200 days. Two RVAD implantations were condu cted, aiming for 1-month system feasibility studies. During the month, the RVADs operated satisfactorily without any thromboembolic incident. No blood clots or abnormal findings were seen inside the pump, nor were there abnor mal findings in the explanted lungs except for small areas of atelectasis. The pump flow was 3.02 +/- 0.38 L/min in calf 1 and 3.75 +/- 1.18 L/min in calf 2. The power requirement was 7.28 +/- 0.43W for calf 1 and 14.52 +/- 3 .93W for calf 2. The PaO2 was 72.0 +/- 3.60 mm Hg (calf 1) and 72.0 +/- 7.6 3 mm Hg (calf 2); PaCO2 was 38.3 +/- 2.17 mm Hg (calf 1) and 34.7 +/- 1.95 mm Hg (calf 2); and SaO(2) was 94.1 +/- 1.37% (calf 1) and 95.0 +/- 1.95% ( calf 2). Cas exchange via the lungs was maintained. These studies indicate that the Gyro PI pump is suitable as a single implantable RVAD, and is a fe asible RVAD as a part of a BiVAD system in terms of pump performance and th rombus resistance.