Display signal to assess autonomic response to vagus nerve stimulation treatment
An assessment system is provided for vagus nerve stimulation therapy treatment for congestive heart failure in a subject. The assessment system includes a first interface configured to communicate with a device that delivers a stimulation signal to a vagus nerve of the subject, a second interface configured to capture heart electrical activity of the subject in response to the stimulation signal, and a processor and a non-transitory computer readable memory storing instructions that, when executed by the processor, cause the assessment system to determine and display heart rate dynamics and display a digital ECG signal in real-time in response to the stimulation signal.
1. An assessment system for vagus nerve stimulation therapy treatment for congestive heart failure in a subject, the assessment system comprising:
a first interface configured to communicate with a device that delivers a stimulation signal to a vagus nerve of the subject;
a second interface configured to capture heart electrical activity of the subject in response to the stimulation signal; and
a processor and a non-transitory computer readable memory storing instructions that, when executed by the processor, cause the assessment system to:
segregate the captured heart electrical activity into portions that correspond to at least one ON-period of the stimulation signal and at least one OFF-period of the stimulation signal based on a communication between the first interface and the device that delivers the stimulation signal; and
determine and display real-time heart rate dynamics for each of the at least one ON-period and the at least one OFF-period and display a digital ECG signal in real-time in response to the stimulation signal.
2. The system of claim 1 , wherein the instructions further cause the assessment system to:
determine the real-time heart rate dynamics and display the digital ECG signal for a plurality of cycles of stimulation signal delivery, each cycle defined by an ON-period and an OFF-period of the stimulation signal; and
provide an indication of autonomic engagement of the subject within 20 cycles.
3. The system of claim 2 , wherein the instructions cause the assessment system to provide the indication of the autonomic engagement within 10 cycles.
4. The system of claim 3 , wherein the instructions cause the assessment system to provide the indication of the autonomic engagement within 5 cycles.
5. The system of claim 4 , wherein the instructions cause the assessment system to provide the indication of the autonomic engagement in real-time.
6. The system of claim 1 , wherein the instructions cause the assessment system to:
record an ECG waveform signal from the captured heart electrical activity and synchronize recording of the ECG waveform signal with a timing of the stimulation signal delivery;
generate and display a plurality of QRS complexes from the ECG waveform signal;
identify a differential in the QRS complexes between ON-periods in which the stimulation signal is delivered as compared to OFF-periods in which the stimulation signal is not delivered; and
display the differential as indicating autonomic engagement.
7. The system of claim 6 , wherein the differential is a comparison of R-R intervals of the QRS complexes for the ON-periods as compared to the OFF-periods.
8. The system of claim 1 , wherein the instructions further cause the assessment system to record and display a waveform of the digital ECG signal response in real-time from the heart electrical activity captured by the second interface; and
wherein the displayed real-time heart rate dynamics include at least one of a real-time heart rate, a first average heart rate for ON-periods in which the stimulation signal is delivered, a second average heart rate for OFF-periods in which the stimulation signal is not delivered, or a difference between the second and the first average heart rates.
9. The system of claim 1 , wherein the display of the real-time heart rate dynamics and the digital ECG signal can be archived and played back.
10. The system of claim 1 , wherein the first interface communicates an ON-period during which stimulation is being delivered and an OFF-period during which no stimulation is being delivered; and
wherein the instructions further cause the assessment system to determine and indicate the stimulation signal delivery including the ON- and OFF-periods.
11. The system of claim 1 , wherein the display of the real-time heart rate dynamics and the digital ECG signal is dynamic.
12. The system of claim 11 , wherein a display playback speed can be controlled.
13. A titration assessment system for vagus nerve stimulation therapy treatment in a subject, the titration assessment system comprising:
an ECG cable assembly configured to acquire an ECG signal response in the subject;
a VNS titration assembly configured to deliver a periodic stimulation signal having ON-periods and OFF-periods;
a data acquisition system coupled to the ECG cable assembly and configured to capture the ECG signal response and detect delivery of the stimulation signal; and
a processor and a non-transitory computer readable memory storing instructions that, when executed by the processor, cause the titration assessment system to:
segregate the ECG signal response to the stimulation signal into portions that correspond to at least one ON-period of the ON-periods and at least one OFF-period of the OFF-periods based on the data acquisition system detecting the delivery of the stimulation signal;
process the ECG signal response to determine R-R intervals in the ECG signal response corresponding to the ON-periods and the OFF-periods;
determine and display real-time heart rate dynamics for each of the at least one ON-period and the at least one OFF-period; and
digitally reproduce the ECG signal response for display.
14. The system of claim 13 , wherein the VNS titration assembly includes an implantable stimulation device and a wand configured to wirelessly interface with the implantable stimulation device.
15. The system of claim 14 , wherein the implantable stimulation device includes an implantable cardioverter-defibrillator (ICD).
16. A method of assessing a vagus nerve stimulation treatment for a subject comprising:
segregating an ECG signal response to the vagus nerve stimulation treatment into portions that correspond to at least one ON-period of a stimulation signal and at least one OFF-period of the stimulation signal based on a communication between a first interface and a device that delivers the stimulation signal;
determining and displaying real-time heart rate dynamics in the ECG signal response for a plurality of cycles of stimulation signal delivery, each cycle defined by an ON-period and an OFF-period of the stimulation signal;
digitally displaying the ECG signal response in real-time; and
providing an indication of autonomic engagement of the subject within 20 cycles, the indication of autonomic engagement being based on the real-time heart rate dynamics for the at least one ON-period and the at least one OFF-period.
17. The method of claim 16 , wherein providing the indication of the autonomic engagement comprises providing the indication of the autonomic engagement within 10 cycles.
18. The method of claim 16 , wherein providing the indication of the autonomic engagement comprises providing the indication of the autonomic engagement within 5 cycles.
19. The method of claim 16 , wherein providing the indication of the autonomic engagement comprises providing the indication of the autonomic engagement in real-time.
20. The method of claim 16 , further comprising:
recording an ECG waveform signal from the ECG signal response and synchronizing recording of the ECG waveform signal with a timing of the stimulation signal delivery;
generating and displaying a plurality of QRS complexes from the ECG waveform signal;
identifying a differential in the QRS complexes between the ON-periods as compared to the OFF-periods; and
displaying the differential as indicating autonomic engagement.