Neurostimulation and recording of physiological response for the treatment of chronic cardiac dysfunction
Systems and methods are provided for delivering neurostimulation therapies to patients for treating chronic heart failure. A neural fulcrum zone is identified and ongoing neurostimulation therapy is delivered within the neural fulcrum zone. The implanted stimulation device includes a physiological sensor for recording the patient's response to the neurostimulation therapy on an ambulatory basis over extended periods of time.
1. An implantable medical device (IMD), comprising:
an electrode assembly;
a neurostimulator coupled to the electrode assembly, said neurostimulator adapted to deliver a stimulation signal to a patient, said stimulation signal comprising an ON time and an OFF time;
a heart rate sensor configured to acquire a heart rate signal from the patient; and
a control system coupled to the neurostimulator and the heart rate sensor and configured to:
activate the neurostimulator to deliver the stimulation signal;
during the OFF time of the stimulation signal, activate the heart rate sensor to acquire a baseline signal comprising a baseline heart rate;
during the ON time of the stimulation signal, activate the heart rate sensor to acquire a response signal comprising a heart rate response; and
change an intensity of the stimulation signal, based on the baseline signal and the response signal, to cause a transition heart rate response in the patient, the transition heart rate response being between tachycardia and bradycardia and comprising a heart rate change between the baseline heart rate and the heart rate response that is less than a predefined threshold.
2. The IMD of claim 1 , wherein the control system is programmed to periodically record the baseline signals and the response signals for a period of at least one week.
3. The IMD of claim 1 , wherein the control system is programmed to periodically record the baseline signals and the response signals for a period of at least one month.
4. The IMD of claim 1 , wherein the control system is programmed to periodically record the baseline signals and the response signals for a period of at least one year.
5. The IMD of claim 1 , further comprising a communications interface configured to wirelessly transmit recorded baseline signals and response signals to an external computing device.
6. The IMD of claim 1 , wherein the stimulation signals are configured to treat a chronic cardiac dysfunction.
7. The IMD of claim 1 , wherein the control system is programmed to activate the heart rate sensor to acquire the baseline signal after a delay period following completion of the ON time of the stimulation signal.
8. The IMD of claim 1 , wherein the control system is programmed to activate the heart rate sensor to acquire the response signal after a delay period following initiation of the ON time of the stimulation signal.
9. The IMD of claim 1 , wherein the control system is programmed to calculate a baseline signal average of a plurality of OFF times of the stimulation signal and to calculate a response signal average of a plurality of ON times of the stimulation signal.
10. The IMD of claim 1 , wherein the electrode assembly and the neurostimulator are adapted to deliver the stimulation signal to a vagus nerve of the patient.
11. A method of operating an implantable medical device (IMD) comprising a heart rate sensor configured to acquire a heart rate signal from the patient and a neurostimulator coupled to an electrode assembly and adapted to deliver a stimulation signal to a patient, the method comprising:
activating the neurostimulator to deliver the stimulation signal;
during the OFF time of the stimulation signal, activating the heart rate sensor to acquire a baseline signal comprising a baseline heart rate;
during the ON time of the stimulation signal, activating the heart rate sensor to acquire a response signal comprising a heart rate response; and
changing an intensity of the stimulation signal, based on the baseline signal and the response signal, to cause a transition heart rate response in the patient, the transition heart rate response being between tachycardia and bradycardia and comprising a heart rate change between the baseline heart rate and the heart rate response that is less than a predefined threshold.
12. The method of claim 11 , further comprising periodically recording the baseline signals and the response signals for a period of at least one week.
13. The method of claim 11 , further comprising periodically recording the baseline signals and the response signals for a period of at least one month.
14. The method of claim 11 , further comprising periodically recording the baseline signals and the response signals for a period of at least one year.
15. The method of claim 11 , further comprising wirelessly transmitting the recorded baseline signals and response signals to an external computing device.
16. The method of claim 11 , wherein the stimulation signals are configured to treat a chronic cardiac dysfunction.
17. The method of claim 11 , wherein activating the heart rate sensor to acquire the baseline signal comprises activating the heart rate sensor to acquire the baseline signal after a delay period following completion of the ON time of the stimulation signal.
18. The method of claim 11 , wherein activating the heart rate sensor to acquire the response signal comprises activating the heart rate sensor to acquire the response signal after a delay period following initiation of the ON time of the stimulation signal.
19. The method of claim 11 , further comprising:
calculating a baseline signal average of a plurality of OFF times of the stimulation signal; and
calculating a response signal average of a plurality of ON times of the stimulation signal.
20. The method of claim 11 , wherein activating the neurostimulator comprises activating the neurostimulator to deliver the stimulation signal to a vagus nerve of the patient.