Neurostimulation and recording of physiological response for the treatment of chronic cardiac dysfunction
View Patent ↗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 in the patient's neural fulcrum zone, 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;
a non-volatile memory;
a control system coupled to the neurostimulator, the physiological sensor, and the non-volatile memory, said control system being programmed to:
monitor a baseline signal acquired by the heart rate sensor, wherein the baseline signal comprises a baseline heart rate during the OFF time periods of the stimulation signal;
monitor a response signal acquired by the heart rate sensor, wherein the response signal comprises a heart rate response during the ON time periods of the stimulation signal; and
record in the non-volatile memory the baseline signals and the response signals on an ambulatory basis;
wherein the neural fulcrum zone corresponds to a stimulation intensity during which a transition heart rate response is detected, said transition heart rate response being between tachycardia and bradycardia and comprising a heart rate change of between about 0% and a decrease of about 5%.
2. The IMD according to 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 according to 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 according to 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 according to claim 1 , further comprising:
a communications interface configured to wirelessly transmit the recorded baseline signals and response signals to an external computing device.
6. The IMD according to claim 1 , wherein the control system is further programmed to activate the neurostimulator to chronically deliver stimulation signals to treat chronic cardiac dysfunction.
7. The IMD according to claim 1 , wherein:
the control system is programmed to monitor the baseline signal during the OFF time periods of the stimulation signal after a delay period following the ON time periods of the stimulation signal.
8. The IMD according to claim 1 , wherein:
the control system is programmed to monitor the response signal during the ON time periods of the stimulation signal after a delay period following initiation of the ON time periods of the stimulation signal.
9. The IMD according to claim 1 , wherein:
the control system is programmed to calculate a baseline signal average of a plurality of OFF time periods of the stimulation signal, and to calculate a response signal average of a plurality of ON time periods of the stimulation signal.
10. The IMD according to 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 non-volatile memory, a heart rate sensor configured to acquire a heart rate signal from the patient, and a neurostimulator coupled to an electrode assembly, said neurostimulator adapted to deliver a stimulation signal to a patient, the method comprising:
activating the neurostimulator to deliver a stimulation signal in a patient's neural fulcrum zone, said stimulation signal comprising an ON time and an OFF time;
monitoring a baseline signal acquired by the heart rate sensor, wherein the monitoring the baseline signal comprises monitoring a baseline heart rate during the OFF time periods of the stimulation signal;
monitoring a response signal acquired by the heart rate sensor, wherein the monitoring the response signal comprises monitoring a heart rate response during the ON time periods of the stimulation signal; and
recording in the non-volatile memory the baseline signals and the response signals on an ambulatory basis;
wherein the neural fulcrum zone corresponds to a stimulation intensity during which a transition heart rate response is detected, said transition heart rate response being between tachycardia and bradycardia and comprising a heart rate change of between about 0% and a decrease of about 5%.
12. The method according to claim 11 , wherein said recording the baseline signals and the response signals on an ambulatory basis comprises periodically recording the baseline signals and the response signals for a period of at least one week.
13. The method according to claim 11 , wherein said recording the baseline signals and the response signals on an ambulatory basis comprises periodically recording the baseline signals and the response signals for a period of at least one month.
14. The method according to claim 11 , wherein said recording the baseline signals and the response signals on an ambulatory basis comprises periodically recording the baseline signals and the response signals for a period of at least one year.
15. The method according to claim 11 , further comprising:
wirelessly transmitting the recorded baseline signals and response signals to an external computing device.
16. The method according to claim 11 , wherein:
said activating the neurostimulator comprises activate the neurostimulator to chronically deliver stimulation signals to treat chronic cardiac dysfunction.
17. The method according to claim 11 , wherein:
said monitoring the baseline signal comprises monitoring the baseline signal during the OFF time periods of the stimulation signal after a delay period following the ON time periods of the stimulation signal.
18. The method according to claim 11 , wherein:
said monitoring the response signal comprises monitoring the response signal during the ON time periods of the stimulation signal after a delay period following initiation of the ON time periods of the stimulation signal.
19. The method according to claim 11 , further comprising:
calculating a baseline signal average of a plurality of OFF time periods of the stimulation signal; and
calculating a response signal average of a plurality of ON time periods of the stimulation signal.
20. The method according to claim 11 , wherein:
said activating the neurostimulator comprises activating the neurostimulator to deliver the stimulation signal to a vagus nerve of the patient.