SURVIVAL FOR UP TO 6 MONTHS IN CALVES SUPPORTED WITH AN IMPLANTABLE AXIAL-FLOW VENTRICULAR ASSIST DEVICE

This paper summarizes the authors' in vivo experience to date with an implantable axial flow blood pump designed for longterm ventricular su pport. This small, valveless pump with blood-lubricated bearings has b een implanted in six calves (83 +/- 6 kg) as a left ventricular assist device (LVAS). The left ventricle and descending thoracic aorta were cannulated by left thoracotomy, and the pump was placed in a subcutane ous pocket below the costal margin. Animals remained hemodynamically s table throughout the course of support during partial left ventricular bypass. Five animals were killed after 15, 27, 52, 57, and 181 days. The longest survivor (181 days) demonstrated normal pump function at t he time death. Pump speed was maintained at 10,100 +/- 100 rpm, with a n average pump flow rate of 4.9 +/- 0.5 L/min under resting physiologi c conditions. Average plasma free hemoglobin was 17.4 +/- 7.5 mg/dl. R enal, hepatic, and hematologic indices remained within physiologic ran ge in all of these animals, except during the immediate postoperative period. Histopathologic analyses of major organs after death revealed small renal cortical infarcts in five of six animals; the remaining or gans were normal. These animal studies support the feasibility of this small implanted axial flow pump for long-term ventricular assistance.