Chronic in vivo evaluation of a portable electrohydraulic ventricular assist system with a linear actuator

Chronic experiments of the electrohydraulic ventricular assist system with a linear motor actuator were performed in two goats weighing 54 kg and 56 kg, and the system was used for more than 30 days. The actuator was designed to be fixed on the goat's back with a saddle. The pump was connected between the left atrium and descending aorta and placed paracorporeally on the chest wall. Linear action of an actuator bellows was delivered by silicone oil in a U-shaped polyvinylchloride tube to activate the pump. The maximum output in the 56 kg goat was 5.0 L/min. Goats could stand and sit freely. The first goat with a pusher-plate type pump died on the fifth day because of thromboembolism, but the second goat with a diaphragm type pump survived for 42 days. Blood chemistries remained within normal limits. Pump control was easy in both the duty-control mode and the stroke-control mode. With the automatic negative pressure control (ANPC) to prevent atrial wall sucking, the left atrial pressure was kept within +/- 10 mmHg, although left atrial pressure sometimes went below -80 mmHg without ANPC. Considering reliability, automaticity, and portability, the electrohydraulic ventricular assist system has become another choice for a practical, electrically driven ventricular assist system.