Back to Annual Meeting Program
Early in vivo results of the Ax-TideTM VAD
Noedir A. G. Stolf1, Alessandro Verona2, Regina Salum2, Rui Barbosa3, Juan Mejia4, Idágene A. Cestari1.
1InCor Heart Institute of the University of São Paulo Medical School, São Paulo, Brazil, 2Studheart Medical Technologies Inc., Fortaleza, Brazil, 3Department of Mechanical Engineering of University of Fortaleza (UNIFOR), Fortaleza, Brazil, 4Heart Transplant and Mechanical Circulatory Assistance Division, Messejana Hospital, Fortaleza, Brazil.
BACKGROUND: There is growing evidence of the use of continuous flow ventricular assist systems to treat severe heart failure patients on a temporary or permanent basis. We evaluated the in vivo performance of a novel miniaturized, fully implantable axial-flow blood pump, the Ax-TideTM VAD. METHODS: The intraventricular pump (20 mm in diameter, 7 cm in length, 86 g in weight) is based on an impeller magnetically coupled to a brushless dc motor sealed in the rear diffuser. The electronic controller powered by lithium-ion batteries is connected to the pump through a 3 mm diameter cable. The titanium pump is coated in diamond-like carbon to improve hemocompatibility and has a sintered microsphere coated shell to favour progressive endocardial overgrowth. A ePTFE vascular graft offloads to the descending thoracic aorta. Six pumps were implanted in 2 calves (70 - 108 Kg) and 4 sheep (48 to 57 kg) under general anesthesia. Blood pressure was measured in the femoral artery and cardiac output measured by thermodilution. A left lateral thoracotomy was performed at the 5th intercostal space to expose the heart. A catheter tip pressure transducer was inserted into the left atrium and the pump outflow graft was sutured to the partially clamped aorta. A sewing cuff was attached to the LV apex with pledgeted 2-0 polyester sutures and the inner myocardium was cored using a cylindrical knife. The Ax-TideTM was inserted into the left ventricle and secured in place. An ultrasonic flow probe was connected to the outflow graft and a second probe was placed around the aorta distal to the graft anastomosis. After deairing, pumping was initiated and pump speed was increased. RESULTS: Maximum average flows were in the range of ~5 to 6 L/min and a reduction of native cardiac output was observed as pump flow increased. Mean arterial blood pressure was maintained within a narrow range with a large increase in diastolic pressure. CONCLUSIONS: This study demonstrates the adequate performance of the Ax-TideTM pump and its applicability in the cardiac assistance arena.
Back to Annual Meeting Program