Implantation of a Ventricular Assist Device in Animals: Progress and Regress

Two types of ventricular assist device (VAD) were tested in vitro and in vivo. A biventricular bypass type total artificial heart utilizing two pusher-plate pumps was implanted in 11 sheep. Following the implantation, the animal’s heart was fibrillated. They survived for 2–48 days, with an average of 11.3 days. The pump flow ranged from 90 to 100ml/min per kg. Other hemodynamic data and the hematological data were normal, except for a low hemoglobin level. We have been developing an implantable motor-driven VAD in collaboration with the Baylor College of Medicine. This pump provided 81/min output against a mean afterload of 120 mmHg with a filling pressure of 20 mmHg. Nine in vivo studies have been conducted. Three sheep survived for 10–12 h. The pump flow ranged from 0.8 to 2.51/min. From these data, left atrial cannulation may not be sufficient to drain adequate blood flow into the pump.