In Vivo Testing of a Roller-Screw Type Electric Total Artificial Heart

Work was begun on the development of an electric motor drive total artificial heart at the Pennsylvania State University in 1978. The first systems developed utilized a low-speed high-torque brushless DC motor rotating a triple-track cam mechanism. This mechanism translated a rotary force into a rectilinear motion to actuate alternately the sac type blood pumps located on either end of the motor drive mechanism. The prototype of this system weighed slightly over 1 kg. Implantation of the cam type electric motor driven artificial heart began in 1983 and 222-day calf survival was obtained late in that year [1]. In 1984, work was begun on a roller-screw type electric motor driven artificial heart. The roller-screw device had the advantages of being smaller, lighter, and less expensive to produce. Extensive in vitro testing of the roller-screw device was performed from 1984 through 1986. In mid-1986 implantation of the roller-screw device was begun in calves. Over the next year the device was implanted in six animals with a maximum survival time of greater than 85 days.