Abstract-In order to develop an artificial heart system capable of being controlled by autonomic nervous signals, we have studied the methods of long-term stable recording of autonomic nervous signals and algorisms to utilize those signals to control an artificial heart system optimally. In this study, we have focused on the feasibility of the control of an artificial heart using the signals recorded from the cardiac sympathetic nerve and other nerves through animal experiments.
INTRODUCTIONThe development of a man-machine interface that can allow information to be sent by the human nervous system to control external equipment is extremely important for the development of the next generation of prosthetic devices, including artificial organs and limbs.On the other hand, with regard to the control method of artificial heart systems, no definitive and reliable method has yet been developed, although several methods have been proposed and tested [1] [2]. No methods have the necessary properties to respond to the variable demands of the living body. Our focus is on a method that uses neural information of the living body to control the artificial heart. With this method, we expect to achieve an artificial heart that can be controlled according to the demands of the natural circulatory center (Figure 1).In order to realize neural prosthetic applications like this one, two essential problems are to be solved. They are:1) how to establish a stable interface with the nervous system, and 2) how to translate the recorded nerve signals to control the artificial devices.The first problem is the development of nerve electrodes. In terms of establishing an intimate and stable interfacing with the nervous system for a long term, the present technology of nerve electrodes is insufficient in many ways. In order to cope with this problem, the authors have been developing regeneration electrodes that have multi-channel recording and stimulating sites. The research is in the animal experimental stage [3].Essentially, the target nerves where neural signals are measured are the cardiac nerves. However, it is difficult to measure the signals at this position because after implantation of the artificial heart, the cardiac nerves are too close to it and it is not possible to get a good S/N proportion. Therefore, we have also studied the use of signals recorded from the cervical autonomic nerve. To utilize the signal from this position, the signal should be properly analyzed. The second problem is related to the analysis of the coding rule of nervous systems. To cope with this problem, it is necessary to investigate how control information is expressed in autonomic nervous systems.
CONTROL OF ARTIFICIAL HEARTS USING AUTONOMIC NERVOUS SIGNALSAs the preliminary step of this research, the authors have already reported an off-line experiment to control an artificial heart system using skin sympathetic nervous signals [4]. In this experiment, we used skin sympathetic nerve activity (SSNA) recorded by microneurography techniques as the paramet...