A miniature implantable axial flow ventricular assist device.

BACKGROUND Since 1984, in collaboration with NASA engineers, we developed an axial flow pump that is 86 mm long, 22 mm wide, weighs 95 g, produces a flow of 5 to 6 L/min against a 100-mm Hg pressure at about 10,000 rpm, and requires less than 10 W of power. METHODS The pump has been implanted in 9 calves with the inlet cannula inserted into the left ventricle and the outlet cannula, consisting of an albumin-coated Dacron graft, attached by end-to-side anastomosis to the descending thoracic aorta. RESULTS All animals showed normal behavior until they were killed 1 to 3 months after operation. At autopsy, systemic studies of vital organs demonstrated no evidence of thromboembolism; the rpm of the pump was maintained between 9,000 and 10,000; the wattage ranged between 7 and 9; the output between 4 and 5 L/min; the hemoglobin was maintained between 32 and 35 mg/dL; the plasma-free hemoglobin ranged between 0.5 and 3 mg/dL; the BUN ranged between 8 and 14 mg/dL; the creatinine remained less than 1 mg/dL; and bilirubin studies were within normal limits. Bearing wear-tear tests up to about 5 months have been negative. CONCLUSIONS The performance characteristics of the pump implanted in calves up to 90 days are highly gratifying, particularly in terms of pump output of 5 L/min, an index of hemolysis well within normal limits, and absence of thromboembolism.