The system control of an electrohydraulic total artificial heart (TAH) has been demonstrated. The TAH is a left-right alternately pumped system. Flow imbalance management is accomplished with a small hydraulic chamber in contact with left atrial blood. A two-level control hierarchy is used: (1) the rates of ventricular filling are governed by atrial pressures, and are adjusted on a beat-by- beat basis for the two sides; (2) the beat rate is changed to maintain full stroke at the operating filling rates. High filling pressures result in higher filling and ejection rates and a higher system beat rate, and vice versa. The control responds to atrial pressures and accommodates outflow pressure changes. The flow and beat rate increased from 31/min at 60 beats per min (BPM) to 7.21/min at 120 bpm as left atrial pressure (LAP) was varied from -4 mmHg to +20 mmHg. In vivo fluid loading studies showed beat rate variation of 70 to 96 bpm as LAP was varied from 2 to 8 mmHg with corresponding changes in flow rates.
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