Mathematical Models for Heart Rate Responses to Vagal Nerve Stimulation.

摘要

The control of heart rate in the dog was studied by first eliminating normal nervous control to the heart and then artificially evoking efferent,cardiac nerve impulses by electrical stimulation of the right vagal nerve. Each stimulation was controlled in intensity and in time relative to the heart cycle. The data presented include the measurement of the minimum observable time for a stimulation to affect heart rate,the transient relaxation of heart rate following the cessation of stimulations,and the changexs in system gain which result from the short term past history of stimulations. A mathematical model is presented which predicts the heart period first lengthened by one stimulation. These periods depended upon the intensity and timing of the stimulation and deviated up to 300percent from the autonomous period. A second model descrivbes the temporal sequence of time delays between the input and the output pulse trains of a class of forced relaxation oscillators. Derived analytical results are used to analyze observed synchronization phenomenon between heart rate and the frequency of repetitive vagal nerve stimulations. (NHLI abstract)