Method of analyzing the relationship of electrical and mechanical events of the heart during left vagal stimulation

Parasympathetic control of electrical conductivity in the heart is mediated through the vagus nerves at the sinoatrial and atrioventricular nodes. To investigate the relationship between electrical to mechanical events influenced by vagal stimulation, the authors developed method to determine the interval between successive peak flows, using Doppler flow measures. This algorithm incorporates the use of a cross correlation scheme to identify the peak flow wave. The QRS complex was identified by a similar cross correlation method. To compare electrical and mechanical events, the authors calculate the time delay between the peak electrical event and the peak flow event. This analysis allows them to determine the variability of R-to-R interval, the peak flow-to-peak flow interval and compare these two time series. The variability in each of these time series is characterized in both time and frequency domains. To test the dynamic aspects of this relationship this analysis was performed with the stimulation of the left vagus nerve turned on and off.