Attempt to control an artificial heart system using sympathetic nervous signals

Changes in skin sympathetic nerve activity (SSNA), which accelerates the constriction of peripheral blood vessels, were measured microneurographically from the median nerve of a subject, and were used for controlling the driving parameters of a pneumatically-driven artificial heart (AH) system. The number of SSNA pulses per second was calculated using a pulse counter, and the driving parameters (pulse rate, positive pressure, and vacuum pressure) of the artificial heart system were altered in accordance with the algorithm for changes in the number of SSNA pulses by means of batch processing. After that, the driving parameters and the pump output of the AH system and the arterial pressure of the mock circulatory system which was connected with the AH pump were compared with the SSNA, digital arterial pressure, and skin blood flow of the subject. The increase/decrease in the number of SSNA pulses essentially matched the changes in digital blood pressure and skin blood flow; in such cases, it was possible to alter the AH pump output and the arterial pressure of the mock circulatory system similar to the change in the actual hemodynamic data of the subject. The authors are currently planning to utilize cardiac nerve activity instead of SSNA.