BACKGROUND During the past 2 years, the development of a totally implantable biventricular bypass rotary blood pump system has been made. METHODS An extracorporeal gyro centrifugal pump, the CIE3, was miniaturized and developed into the PI601, a totally implantable plastic pump. Two-day anatomic and hemodynamic feasibility studies demonstrated that these two pump systems were easily implantable inside a calf's abdominal wall, directly under the diaphragm. The priming volume of the pump was 20 mL, with sufficient cardiac outputs at approximately 2,000 rpm and requiring less than 10 W of power. Two-week antithrombogenic screening tests also revealed these pump systems to be quite antithrombogenic. In addition, 1-month system reliability studies demonstrated fail-safe reliable performances. CONCLUSIONS Encouraged by these preliminary studies, the PI601 model was converted to the permanently implantable titanium gyro pump PI702 model. The long-term implantations were initiated approximately 3 months ago, and two such long-term LVAD studies are currently underway with no sign of difficulty (October 10, 1997). They were followed 283 days and 72 days, respectively. Both terminated due to functional inflow obstruction. There were no blood clots or emboli at autopsy.