CONTINUOUS MONITORING OF AUTONOMIC NERVE INFORMATION FOR THE CONTROL OF AN ARTIFICIAL-HEART

To drive an artificial heart system optimially, information from the a utonomic nervous system may be needed; however, it is very difficult t o monitor autonomic nerve discharges continuously. In this study, we p ropose a new automatic control algorithm for a total artificial heart (TAH) using fluctuations in the circulatory system. It was reported th at fluctuations in hemodynamics reflect ongoing information from the a utonomic nervous system. A Mayer wave at 0.1 Hz was reported to reflec t sympathetic information. We observed fluctuations in vascular resist ance, which can be measured during use of an artificial heart. Four ad ult goats were used for the experiments. Through a left thoracotomy, h emodynamic parameters were measured during chronic animal experiments. All time series data were recorded on magnetic tape. Quantitative ana lysis, statistics, and spectral analysis were carried out on a compute r through an analog-digital (AD) converter. A Mayer wave peak was clea rly recognized in all goats in the spectrum of vascular resistance. A band pass filter was used to convert this information to automatic con trol. Time series curves of the Mayer wave of vascular resistance were provided, and compared with the time series curve of the cardiac outp ut. After a change in the Mayer wave, increase in cardiac output was o bserved. This phenomenon may be interpreted as sympathetic nervous con trol of changes in cardiac output. These results suggest that an artif icial heart may be controlled by the measurement of the Mayer wave of vascular resistance, making it possible to control an artificial heart with neural information.