A biolized, compact, low noise, high performance implantable electromechanical ventricular assist system

An implantable electromechanical ventricular assist system (VAS) intended for permanent human use was developed. It consisted of a conically shaped pumping chamber, a polyolefin (Hexsyn) rubber diaphragm attached to a pusher-plate, and a compact actuator with a direct current brushless motor and a planetary rollerscrew. The outer diameter was 97 mm, and the total thickness was 70 mm. This design was chosen to give a stroke volume of 63 ml. The device weighs 620 g, with a total volume of 360 ml. The pump can provide 8 L/min flow against 120 mmHg afterload with a preload of 10 mmHg. The inner surface of the device, including the pumping chamber and diaphragm, was made biocompatible with a dry gelatin coating. To date, two subacute (2 and 6 day) calf studies have been conducted. The pump showed reasonable anatomic fit inside the left thorax, and the entire system functioned satisfactorily in both the fill-empty mode using the Hall effect sensor signals and the conventional fixed rate mode. There were no thromboembolic complications despite no anticoagulation therapy. The system now is being endurance tested greater than 10 weeks (9 million cycles). This VAS is compact, low noise, easy to control, and has excellent biocompatibility.