ORIGIN OF THE RHYTHMICAL FLUCTUATIONS IN THE ANIMAL WITHOUT A NATURALHEARTBEAT

In order to analyze the origin of the rhythmical fluctuations in the c ardiovascular system, an artificial heart, which does not have rhythmi cal periodicities such as altering heart rate and cardiac function, wa s utilized in chronic animal experiments with adult goats. Two pneumat ically actuated ventricular assist devices were implanted as a total b iventricular bypass under general anesthesia, and then the natural hea rt was electrically fibrillated to constitute the biventricular bypass type of complete prosthetic circulation model. All hemodynamic data w ere recorded under awake conditions and were calculated in the compute r system by spectral analysis methods. In the power spectrum of the ar terial blood pressure of the animal with the artificial heart, the May er wave peak and respiratory wave peak were clearly observed, and spec tral analysis including the coherence function suggests that the Mayer waves originated from the peripheral vascular resistance and the resp iratory waves probably originated from the periodicities of the pulmon ary circulation. These fluctuations in the circulatory system influenc ed the arterial baroreflex system and transfer to the sympathetic outf low through the central baroreflex system, which suggests that rhythmi cal fluctuations in hemodynamic parameters originate at least in part from these vascular periodicities.