Abstract
In order to evaluate the autonomic response of conscious adult goats under the systemic ventricular assistance, the power spectrum of the heart rate variability was analyzed using the newly developed system. The power spectra were analyzed on the several different conditions; (1) asynchronous mode of different assist volumes and different driving frequencies, (2) synchronous mode of the constant assist volume and different time-delays from R-wave. In the asynchronous mode, the low-peak (Mayer wave) and the high-peak (respiratory arrhythmia) were clearly observed. On the contrary, in the synchronous mode with time-delays of 300, 400 and 500 ms, the low-peak was attenuated. Because this autonomic response under the synchronous assistance is different from that produced by administration of the β-blockade which attenuates the sympathetic activity, the synchronous assistance may influence the response of the sympathetic nervous system to physiological disturbances. In addition, power spectra were processed by means of the maximum entropy method for the automatic control system. Using this method, both the locations and the strengths of spectral peaks could be automatically calculated. It was concluded that the power spectral analysis of the heart rate could be useful as one of the information for the automatic control system of ventricular assist device.
