IFMBE Proceedings Vol. 14/1 Volume 1 Track 01 99 Comprehensive physiological identification of cardiovascular regulation enables to restore and correct pathological regulation Masaru Sugimachi 1 , Toru Kawada 1 , Toshiaki Shishido 1 , Meihua Li 1 , Can Zheng 1 , Kenji Sunagawa 2 1 Department of Cardiovascular Dynamics, Advanced Medical Engineering Center, National Cardiovascular Center Research Institute, Suita, Japan 2 Department of Cardiovascular Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan Abstract— There is growing evidence that abnormal car- diovascular regulation plays a vital role in the maintenance and progression of heart disease, e.g., heart failure. Correcting these abnormalities is likely to help improve pathophysiology and survival. We have developed a bionic system, an artificial device designed for integration into native human physiologi- cal systems. By communicating with the physiological regula- tory system, especially through the nervous system, bionic systems enables restoration of lost function and correction of abnormal function. Development of bionic systems requires the detailed knowledge of the characteristics of the native system. Native systems have a number of extremely complex factors such as history-dependence, feedback nature, multiplicity and interac- tion of inputs, nonlinearity, and distributed nature. To over- come these, we made use of a "white-noise approach" and succeeded in functionally identifying the native arterial baro- reflex with sufficient precision that one can reproduce a native system artificially. Using the identified characteristics, we developed a bionic baroreflex system and succeeded in stabilizing pressure against hypotensive stimuli even in animals without a functional baro- reflex system. Bionic therapeutic strategy also enabled us to correct the abnormal regulatory function. This correction improved inhibited cardiac remodeling and survival of animals with chronic heart failure. From the physiological point of view, the success of bionic systems implies that the characteristics thus determined reflect the comprehensive natures of the physiological regulatory system, not only the limited aspects of the system. The advan- tage of using "white-noise approach" in determining the total picture of complex systems holds also for cardiovascular regu- latory system in animals. Our findings showed that developed bionic systems can help deepen our understanding of physio- logical systems as well as open up new therapeutic strategies against various diseases. Keywords— Functional replacement, White noise method, Heart failure I. INTRODUCTION There is growing evidence that abnormal cardiovascular regulation plays a vital role in the maintenance and progres- sion of heart disease, e.g., heart failure. Correcting these abnormalities is likely to help improve pathophysiologic processes such as cardiac remodeling and also survival. Besides the current state-of-art therapeutic modalities, such as pharmacological treatments, cardiac transplantation, and artificial heart, development of an additional therapeutic strategy attacking the abnormal cardiovascular regulation seems of great value to help still unsaved patients. II. BIONIC SYSTEM We have developed a bionic system, an artificial device designed for integration into native human physiological systems. By communicating with the physiological regula- tory system, bionic system enables restoration of lost func- tion and correction of abnormal function. This system can be most efficiently materialized by communicating the native neural regulatory system. Because electrical stimula- tion of autonomic nerves is a realizable means to modify cardiovascular regulation, we have developed several bionic systems based on this. III. IDENTIFICATION OF NATIVE SYSTEM In addition to the physical interface with the native sys- tems, we need to explore how to exchange information logi- cally between machine and native systems. In other words, we have to know the encoding rule for the neural stimulation. As the first step, development of bionic systems requires the detailed knowledge of the characteristics of the native system. Native systems have a number of extremely complex factors such as history-dependence, feedback nature, multiplicity and interaction of inputs, nonlinearity, and distributed nature. To over-come these, we made use of a "white-noise approach" and succeeded in functionally identifying the native arterial baroreflex with sufficient precision that one can reproduce a native system artificially [1], [2]. Using the identified characteristics, we developed a bi- onic baroreflex system and succeeded in stabilizing pressure against orthostatic hypotension even in animals without a functional baroreflex system [3]-[5]. Bionic therapeutic