No abstract

In order to analyze the origin of the rhythmical fluctuations in the cardiovascular system, an artificial heart, which does not have rhythmical periodicities such as altering heart rate and cardiac function, was utilized in chronic animal experiments with adult goats. Two pneumatically actuated ventricular assist devices were implanted as a total biventricular bypass under general anesthesia, and then the natural heart was electrically fibrillated to constitute the biventricular bypass type of complete prosthetic circulation model. All hemodynamic data were recorded under awake conditions and were calculated in the computer system by spectral analysis methods. In the power spectrum of the arterial blood pressure of the animal with the artificial heart, the Mayer wave peak and respiratory wave peak were clearly observed, and spectral analysis including the coherence function suggests that the Mayer waves originated from the peripheral vascular resistance and the respiratory waves probably originated from the periodicities of the pulmonary circulation. These fluctuations in the circulatory system influenced the arterial baroreflex system and transfer to the sympathetic outflow through the central baroreflex system, which suggests that rhythmical fluctuations in hemodynamic parameters originate at least in part from these vascular periodicities.

No abstract

Aiming at a totally implantable ventricular assist device (VAD), a vibrating flow pump (VFP) was developed in Tohoku University. A transcutaneous energy transmission system (TETS) using an amorphous fiber was developed for the totally implantable VAD system. The VFP works with a higher frequency than the natural heart of a biological system, a frequency of 10-50 Hz. In this research, animal experiments on left heart bypass were performed with healthy goats. Blood from the apex of the left ventricle was received and was sent to the aorta so that an adequate supporting effect of the left heart was provided. In particular, the depression effect of the left ventricle was obvious. As a result, sufficient artificial heart flow was provided. For a totally implantable type VAD, left heart bypass of almost 100% may become necessary in some situations. Therefore, apex approaches of left heart bypass may be desirable. From an anatomical consideration, an apex of the heart is suitable for the VFP of this totally implantable type. In the left heart bypass for which the apex of the heart was used, an almost 100% bypass was possible. This is a requirement that is important when waiting for recovery of sufficient cardiac function. It is also important that left heart circulation is maintained fully by an artificial heart of the complete implantation type. The VFP was considered to be useful as a totally implantable type artificial heart from the results.