System identification of neural cardiovascular control mechanisms.

摘要

One of the most important functions of neural cardiovascular regulation is to maintain arterial blood pressure (ABP) within a narrow range in order to protect blood flow to the brain, heart and other vital organs. The autonomic nervous system is primarily responsible for extrinsic cardiovascular regulation over short time scales of seconds to minutes usually through mediation of the arterial and cardiopulmonary baroreflex. When changes in ABP or central venous pressure increase/decrease the stretch of the arterial or cardiopulmonary baroreceptors and afferent signals are transmitted to the brain, the brain responds to keep ABP near its normal operating level by adjusting heart rate (HR), ventricular contractility (VC), total peripheral resistance (TPR) and systemic venous unstressed volume. Improper functioning of the neural cardiovascular control mechanisms could cause numerous diseases such as postural tachycardia syndrome, congestive heart failure and diabetic autonomic neuropathy. Therefore, it is important to be able to quantify neural cardiovascular regulation in order to better understand its functioning in both health and disease and to guide patient therapy.;The research addressed in this dissertation is an effort to quantitatively characterize the neural cardiovascular control mechanisms via system identification and advanced signal processing techniques. We derived specific parasympathetic and sympathetic nervous system indices from identified HR baroreflex impulse response via non-invasive cardio-respiratory variability, developed a model-based technique to estimate the arterial TPR baroreflex impulse response through potentially non-invasive measurements, and investigated the dynamic control mechanisms of VC via the baroreflex and force-frequency relation. Our results, obtained from animal/human experiments and as well as realistic computer simulated data, either correctly predict the known effects after autonomic interventions or provide new insight in the neural cardiovascular regulation.