A Completely Implanted Left Ventricular Assist Device: Chronic In Vivo Testing

A completely implantable left ventricular assist device (LVAD) designed for permanent circulatory support has recently been tested in animals without the use of percutaneous leads, using transcutaneous energy transmission and wireless telemetry. The LVAD consists of a brushless DC motor and rollerscrew energy converter, a pusher plate actuated blood pump with a seamless segmented polyure-thane blood sac, Bjork-Shiley Delrin disk monostrut valves, an implanted compliance chamber, an implanted electronic controller and battery, and a transcutaneous energy transmission system. The blood pump/energy converter assembly weighs 565 g and displaces 295 cc. The dynamic stroke volume is 60 ml, and the maximum output is 9 L/min. Pump output is automatically controlled to maintain full stroke volume as preload varies. Hall effect sensors for detecting rotary position of the motor are the only sensors used. Six bovine implants were performed, with durations of 84, 208, 244,130, 70 (ongoing), and 15 (ongoing) days. Four animals used two-way telemetry, whereas the remaining two used one-way (outgoing) telemetry. These first chronic in vivo tests with the Penn State completely implanted LVAD system have demonstrated that it is a feasible solution to long-term ventricular support.