Abstract
Many artificial hearts (AH) have been controlled according to an amount of blood flow in the end diastolic volume. Natural hearts, on the other hand, modify outputs under affection of the nervous systems. The nerves connecting the brain and the heart are promising to contain rich information for the AH control. In this study, we measured vagal nerve signals from a goat with an in-vivo ventricular assist device, applying a pair of hook electrodes in the left vagal nerve. Another pair of hook electrodes was placed on the skin to acquire electrical noises. A Wiener filter was designed to subtract the noises on the skin from the vagal nerve signals. As we estimated a mutual correlation between amplitudes of the processed neural signals and aortal pressures, a correlation peak was found at 200 ms lag of time, suggesting the processed neural signals contain a component to represent aortal pressures. It is reasonable to assume the time delay as a time for the brain to receive aortal pressure information and to generate a control command for the heart. We therefore suppose the component originated from the efferent nerve fibers which would provide an information source for AH control.
