In vitro and in vivo performance evaluation of a totally implantable electrohydraulic left ventricular assist system

The biolized electrohydraulic left ventricle assist devices were tested in 14 calves with an average survival time of 162 days and as long as 250 days without the use of anticoagulants. In vitro, the system pumped 4.1 L/min at a low 4.8 mmHg fill pressure with a mean afterload of 100 mmHg and rate of 46 bpm. A flow rate of 13.5 L/min was observed at 155 bpm and 110 mmHg afterload. Motor frequency and current increased with increasing flow rate (162 Hz, 0.67 amp at 2.5 L/min; 484 Hz, 2.43 amp at 13.5 L/min). Flow rate did not change significantly with afterload pressure. The complete system was implanted in a 100 kg calf. Synchronization of the blood pump with the natural heart was demonstrated at heart rates of 85 to 167 bpm. The synchronized flow rate varied from 6 to 10.5 L/min despite the considerable heart rate changes and stroke variations. The system hemodynamic performances were acceptable and met NIH requirements.