Using heart rate as the chronotropic metric can overstate the extent of autonomic interactions compared to using heart period, which varies more linearly with autonomic control.
Autonomic control of the heart varies more linearly with heart period than with rate. Relative linearity confers a greater independence of basal autonomic activation and heart period changes. Thus, heart period appears to be more appropriate for characterizing cardiac phenomena such as autonomic interactions that involve significant baseline shifts. Simulated and published empirical data were used to demonstrate the importance of the chronotropic metric for characterizing autonomic interactions. Simulations revealed a significant autonomic interaction when heart rate, but not heart period, was the chronotropic metric. Published heart rate data also show a substantial autonomic interaction, whereas heart period data do not. These findings suggest that the choice of chronotropic metric can overstate the extent of autonomic interactions on cardiac chronotropic function.
Quigley et al. (Sun,) conducted a other in Autonomic control of the heart. Heart period metric vs. Heart rate metric was evaluated on Autonomic interactions. Using heart rate as the chronotropic metric can overstate the extent of autonomic interactions compared to using heart period, which varies more linearly with autonomic control.