Abstract: A system includes a vagus nerve stimulation (VNS) device configured to deliver a vagus nerve stimulation signal having an ON-period status and an OFF-period status, and a processor and a non-transitory computer readable memory. The memory stores instructions that, when executed by the processor, cause the system to synchronously record a first ECG profile of during the ON-period status and a second ECG profile during the OFF-period status, determine heart rate dynamics from the first and second ECG profiles, the heart rate dynamics including a plurality of R-R intervals in each ECG profile, generate display data configured to be displayed on a display, and transmit the display data to the display. The display data includes the R-R intervals for each of the first and second ECG profiles. The display data further includes a Poincaré plot.