CORA VALVELESS PULSATILE ROTARY PUMP - NEW DESIGN AND CONTROL

For decades, research for developing a totally implantable artificial ventricle has been carried on. For 4 to 5 years, two devices have been investigated clinically. For many years, we have studied a rotary (bu t not centrifugal) pump that furnishes pulsatile flow without a valve and does not need external venting or a compliance chamber. It is a hy pocycloidal pump based on the principle of the Maillard-Wankel rotary compressor. Currently made of titanium, it is activated by an electric al brushless direct-current motor. The motor-pump unit is totally seal ed and implantable, without noise or vibration. This pump was implante d as a left ventricular assist device in calves. The midterm experimen ts showed good hemodynamic function. The hemolysis was low, but seriou s problems were encountered: blood components collecting on the gear m echanism inside the rotor jammed the pump. We therefore redesigned the pump to seal the gear mechanism. We used a double system to seal the open end of the rotor cavity with components polished to superfine opt ical quality. In addition, we developed a control system based on the study of the predicted shape of the motor current. The new design is n ow underway. We hope to start chronic experiments again in a few month s. If the problem of sealing the bearing could be solved, the Cora ven tricle could be used as permanent totally implantable left ventricular assist device.