PACEMAKER WITH VAGAL SURGE MONITORING AND RESPONSE

• US 20110106197A1
• Filed: 02/22/2010
• Published: 05/05/2011
• Est. Priority Date: 10/30/2009
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Arcot-Krishnamurthy, Shantha, Mokelke, Eric A., Shuros, Allan C.
• Granted Patent: US 8,412,326 B2
• Time in Patent Office: Days
• US Class Current: 607/17
• CPC Class Codes: A61N 1/3627 for treating a mechanical deficiency of the heart, e.g. congestive heart failure or cardiomyopathy
• CPC Class Codes: A61N 1/36514 controlled by a physiological quantity other than heart potential, e.g. blood pressure controlled by two or more physical parameters A61N1/36585
• CPC Class Codes: A61N 1/36585 controlled by two or more physical parameters

Abstract

A pacemaker initiates and times a monitoring interval in response to an event such as a therapy delivery to a patient. The monitoring interval is specified to include a duration of an anticipated acute response to the event, such as vagal surge. One or more physiological parameters indicative of the acute response are detected during the monitoring interval for analyzing therapeutic effect of the event. In various embodiments, one or more pacing parameters are adjusted for a response interval specified to include the duration of the anticipated acute response to allow for the analysis and maximization of the therapeutic effect. In various embodiments, the event includes a session of pacing therapy delivered according to an intermittent cardiac stress augmentation pacing protocol, and the therapeutic effect is analyzed to adjust that protocol.

Claims

1. A system for pacing a heart, comprising:

a monitoring circuit including;

a monitoring timer configured to initiate and time a monitoring interval including an anticipated duration of vagal surge resulting from a specified type event;

a sensing circuit configured to sense one or more physiological signals each indicative of a level of the vagal surge, the one or more physiological signals including at least a cardiac signal; and

a detection circuit configured to detect one or more parameters each indicative of the level of the vagal surge using the sensed one or more physiological signals, the one or more parameters including at least an intrinsic heart rate;

a pacing output circuit configured to deliver pacing pulses; and

a pacing control circuit coupled to the monitoring circuit and the pacing output circuit, the pacing control circuit configured to control the delivery of the pacing pulses using pacing parameters and including;

a response timer configured to initiate and time a response interval following the specified type event, the response interval including the anticipated duration of the vagal surge; and

a parameter adjustment module configured to adjust one or more pacing parameters of the pacing parameters to allow the heart to beat at the intrinsic heart rate during the response interval.

2. The system of claim 1, wherein the response timer is configured to initiate the response interval upon expiration of a delay interval starting at an end of the specified type event, and the parameter adjustment module is configured to lower a lower rate limit (LRL) of the pacing parameters by a specified margin below the detected intrinsic heart rate during the response interval.

3. The system of claim 1, comprising a therapy device configured to perform delivery of a therapy, and wherein the specified type event comprises the delivery of the therapy, and the monitoring timer is configured to initiate the monitoring interval in response to the delivery of the therapy.

4. The system of claim 3, wherein the response timer is configured to initiate the response interval upon expiration of a delay interval starting at an end of the delivery of the therapy.

5. The system of claim 3, comprising:

a first implantable medical device including the monitoring circuit, the pacing circuit, and the pacing control circuit; and

a second implantable or non-implantable medical device including the therapy device.

6. The system of claim 3, comprising an implantable medical device including the monitoring circuit, the pacing circuit, the pacing control circuit, and the therapy device.

7. The system of claim 6, wherein the therapy device is configured to deliver a neurostimulation therapy.

8. The system of claim 6, wherein the therapy device comprises the pacing circuit and the pacing control circuit, and the pacing control circuit comprises:

a memory circuit;

an intermittent cardiac stress augmentation pacing protocol stored in the memory circuit, the intermittent cardiac stress augmentation pacing protocol specifying stress augmentation pacing sessions each being the specified type event and including alternating non-pacing and pacing periods, the non-pacing periods each having a non-pacing duration during which no pacing pulse is timed to be delivered, the pacing periods each having a specified pacing duration during which a plurality of the pacing pulses is timed to be delivered using pacing parameters selected to augment cardiac stress to the level effective in slowing or stopping progression of the cardiac disorder; and

a pacing protocol execution module configured to control the delivery of the pacing pulses by executing the intermittent cardiac stress augmentation pacing protocol.

9. The system of claim 6, wherein the detection circuit is configured to produce a pre-event value of each of the one or more parameters before the specified type event, a post-event value of the each of the one or more parameters after the specified event during the monitoring interval, and a change value of each of the one or more parameters, the change value being a difference between the post-event value and the pre-event value of the each of the one or more parameters.

10. The system of claim 9, wherein the sensing circuit is configured to sense the cardiac signal and one or more of a signal indicative of respiration, a pulmonary artery pressure (PAP) signal, and a signal indicative of heart sounds, and the detection circuit is configured to detect the intrinsic heart rate and one or more of an atrioventricular (AV) interval, a short-term heart rate variability (HRV) indicative of heart rate turbulence (HRT), a minute ventilation, a PAP, or rate of change in the PAP (dPAP/dt), and a heart sound parameter.

11. A method for operating a system for pacing a heart, comprising:

sensing a cardiac signal from the heart;

delivering pacing pulses to the heart;

controlling the delivery of the pacing pulses using pacing parameters;

initiating a monitoring interval in response to a specified type event, the monitoring interval including an anticipated duration of vagal surge resulting from the specified type event;

detecting an intrinsic heart rate from the cardiac signal during the monitoring interval;

initiating a response interval in response to the specified type event, the response interval including the anticipated duration of the vagal surge; and

adjusting one or more pacing parameters of the pacing parameters to allow the heart to beat at the intrinsic heart rate during the response interval.

12. The method of claim 11, comprising delivering a therapy, and wherein the specified type event comprises the delivery of the therapy, and initiating the monitoring interval comprises initiating the monitoring interval in response to the delivery of the therapy.

13. The method of claim 12, comprising programming the monitoring interval and the response time to terminate simultaneously at approximately 2 to 3 hours following an end of the delivery of the therapy.

14. The method of claim 12, wherein initiating the response interval comprises initiating the response interval upon expiration of a delay interval starting at an end of the delivery of the therapy, and comprising programming the delay interval to a time interval between approximately 0 and 10 minutes.

15. The method of claim 11, comprising:

sensing the cardiac signal and one or more additional physiological signals each indicative of a level of the vagal surge; and

detecting the intrinsic heart rate and one or more additional parameters each indicative of the level of the vagal surge.

16. The method of claim 11, comprising producing a pre-event value of the intrinsic heart rate before the specified type event, a post-event value of the intrinsic heart rate after the specified type event during the monitoring interval, and a change value of the intrinsic heart rate, the change value being a difference between the post-event value and the pre-event value.

17. The method of claim 11, wherein adjusting the one or more pacing parameters comprises lowering a lower rate limit (LRL) to a value below the detected intrinsic heart rate by a specified margin during the response interval if the lowered LRL exceeds a specified minimum.

18. The method of claim 17, wherein lowering the LRL comprises lowering the LRL to a value below the detected intrinsic heart rate by approximately 15 beats per minute.

19. The method of claim 11, comprising delivering an intermittent cardiac stress augmentation pacing therapy including stress augmentation pacing sessions each being the specified type event and including alternating non-pacing and pacing periods, the non-pacing periods each having a non-pacing duration during which no pacing pulse is timed to be delivered, the pacing periods each having a specified pacing duration during which a plurality of the pacing pulses is timed to be delivered using pacing parameters selected to augment cardiac stress to the level effective in slowing or stopping progression of a cardiac disorder.

20. The method of claim 11, comprising delivering an intermittent cardiac stress augmentation pacing therapy including stress augmentation pacing sessions each being the specified type event and including alternating first and second pacing periods, the first pacing periods each having a first pacing duration during which a plurality of the pacing pulses is timed to be delivered according to a first pacing mode, the second pacing periods each having a second pacing duration during which a plurality of the pacing pulses is timed to be delivered according to a second pacing mode including pacing parameters selected to augment cardiac stress to the level effective in slowing or stopping progression of a cardiac disorder.

21. A system for pacing a heart, comprising:

a monitoring circuit including;

a monitoring timer configured to initiate and time a monitoring interval including an anticipated duration of an acute response to a stress augmentation pacing session of a plurality of stress augmentation pacing sessions;

a sensing circuit configured to sense one or more physiological signals each indicative of a level of the acute response; and

a detection circuit configured to detect the acute response using the one or more physiological signals sensed during the monitoring interval and produce an acute response signal after expiration of the monitoring interval, the acute response signal indicative of a status of the acute response;

a pacing output circuit configured to deliver pacing pulses; and

a pacing control circuit including;

a memory circuit;

an intermittent cardiac stress augmentation pacing protocol stored in the memory circuit, the intermittent cardiac stress augmentation pacing protocol specifying the plurality of stress augmentation pacing sessions and a stress augmentation pacing mode including pacing parameters selected to augment cardiac stress to a level effective in slowing or stopping progression of a cardiac disorder;

a pacing protocol execution module configured to control the delivery of the pacing pulses by executing the intermittent cardiac stress augmentation pacing protocol; and

a stress augmentation pacing adjustment module configured to adjust the intermittent cardiac stress augmentation pacing protocol using the acute response signal.

22. The system of claim 21, wherein the detection circuit comprises:

a parameter producer configured to produce one or more parameters each indicative of the level of the acute response using the sensed one or more physiological signals; and

an acute response detector configured to detect the acute response by comparing the one or more parameters to one or more thresholds and produce the acute response signal using an outcome of the comparing.

23. The system of claim 22, wherein the monitoring timer is configured to initiate and time the monitoring interval including an anticipated duration of vagal surge resulting from the stress augmentation pacing session, the sensing circuit is configured to sense at least a cardiac signal, and the parameter producer is configured to produce at least an intrinsic heart rate using the cardiac signal.

24. The system of claim 23, wherein the pacing control circuit comprises a chronic pacing adjustment module including:

a response timer configured to initiate and time a response interval following the stress augmentation pacing session, the response interval including the anticipated duration of the vagal surge; and

a parameter adjustment module configured to adjust one or more pacing parameters to allow the heart to beat at the intrinsic heart rate during the response interval.

25. The system of claim 23, wherein the sensing circuit is configured to sense the cardiac signal and one or more of a signal indicative of respiration, a pulmonary artery pressure (PAP) signal, and a signal indicative of heart sounds, and the parameter producer is configured to produce the intrinsic heart rate and one or more of an atrioventricular (AV) interval, a short-term heart rate variability (HRV) indicative of heart rate turbulence (HRT), a minute ventilation, a PAP, or rate of change in the PAP (dPAP/dt), and a heart sound parameter.

26. The system of claim 23, wherein the stress augmentation pacing adjustment module comprises a mode selection module to select a stress augmentation pacing mode from a plurality of stress augmentation pacing modes using the acute response signals produced for first stress augmentation pacing sessions of the plurality of stress augmentation sessions, the first stress augmentation pacing sessions each associated with one stress augmentation pacing mode of the plurality of stress augmentation pacing modes.

27. The system of claim 23, wherein the acute response detector is configured to declare one of presence and absence of the acute response using the outcome of the comparing and produce the acute response signal to indicate the presence or absence of the acute response, and the stress augmentation pacing adjustment module comprises a response assurance module configured to adjust one or more parameters of the intermittent cardiac stress augmentation pacing protocol to augment the cardiac stress to a higher level in response to the acute response signal indicating the absence of the acute response.

28. The system of claim 27, wherein the response assurance module is configured to suspend the execution of the intermittent cardiac stress augmentation pacing protocol for a specified period in response to the acute response signal indicating the absence of the acute response.

29. The system of claim 23, wherein the acute response detector is configured to declare one of presence and absence of the acute response using the outcome of the comparing, detect a duration of the acute response being a time interval during which the presence of the acute response is declared, and produce the acute response signal to indicate the duration of the acute response, and the stress augmentation pacing adjustment module comprises a session frequency module configured to set a session frequency based on the detected duration of the acute response, the session frequency being a frequency at which the stress augmentation pacing sessions are delivered.

30. The system of claim 23, wherein the acute response detector is configured to declare one of presence and absence of the acute response using the outcome of the comparing, detect a duration of the acute response being a time interval during which the presence of the acute response is declared, and produce the acute response signal to indicate a level and the duration of the acute response, and the stress augmentation pacing adjustment module comprises a dose reduction module to reduce one or more of a level to which the cardiac stress is augmented during each stress augmentation pacing session of the plurality of stress augmentation pacing sessions and a duration of the each stress augmentation pacing session using the acute response signal.

31. A method for operating a system for pacing a heart, comprising:

delivering pacing pulses;

controlling the delivery of the pacing pulse by executing an intermittent cardiac stress augmentation pacing protocol specifying a plurality of stress augmentation pacing sessions and a stress augmentation pacing mode including pacing parameters selected to augment cardiac stress to a level effective in slowing or stopping progression of a cardiac disorder;

timing a monitoring interval including an anticipated duration of an acute response to a stress augmentation pacing session of the plurality of stress augmentation pacing sessions;

sensing one or more physiological signals each indicative of a level of the acute response;

detecting the acute response using the one or more physiological signals sensed during the monitoring interval;

producing an acute response signal after expiration of the monitoring interval, the acute response signal indicative of a status of the acute response for the stress augmentation pacing session; and

adjusting the intermittent cardiac stress augmentation pacing protocol using the acute response signal.

32. The method of claim 31, wherein detecting the acute response comprises producing one or more parameters each indicative of the level of the acute response using the sensed one or more physiological signals, and producing the acute response signal comprises comparing the one or more parameters to one or more thresholds and producing the acute response signal using an outcome of the comparing.

33. The method of claim 32, wherein timing the monitoring interval comprises timing a time interval including an anticipated duration of vagal surge resulting from the stress augmentation pacing session, sensing the one or more physiological signals comprises sensing a cardiac signal, and producing the one or more parameters comprises detecting an intrinsic heart rate.

34. The method of claim 33, comprising:

timing a response interval following the stress augmentation pacing session, the response interval including the anticipated duration of the vagal surge; and

adjusting one or more pacing parameters controlling the delivery of the pacing pulses to allow the heart to beat at the intrinsic heart rate during the response interval.

35. The method of claim 32, wherein adjusting the intermittent cardiac stress augmentation pacing protocol comprises selecting a stress augmentation pacing mode from a plurality of stress augmentation pacing modes using the acute response signals produced for first stress augmentation pacing sessions of the plurality of stress augmentation pacing sessions, the first stress augmentation pacing sessions each associated with a mode of the plurality of stress augmentation pacing modes.

36. The method of claim 32, wherein producing the acute response signal comprises:

declaring one of presence and absence of the acute response using the outcome of the comparing the one or more parameters to the one or more thresholds; and

producing the acute response signal to indicate the presence or absence of the acute response,

and wherein adjusting the intermittent cardiac stress augmentation pacing protocol comprises adjusting parameters of the intermittent cardiac stress augmentation pacing protocol in response to the acute response signal indicating the absence of the acute response.

37. The method of claim 36, wherein adjusting the parameters of the intermittent cardiac stress augmentation pacing protocol comprises one or more of:

adjusting the parameters to augment the cardiac stress to an increased level;

changing the stress augmentation pacing mode to a different stress augmentation pacing mode; and

changing timing parameters of the parameters for one or more of different delivery time and duration of the stress augmentation sessions.

38. The method of claim 37, wherein adjusting the parameters of the intermittent cardiac stress augmentation pacing protocol comprises suspending the execution of the intermittent cardiac stress augmentation pacing protocol for a specified period in response to the acute response signal indicating the absence of the acute response following the adjusting the parameters of the intermittent cardiac stress augmentation pacing protocol.

39. The method of claim 32, wherein producing the acute response signal comprises:

declaring one of presence and absence of the acute response using the outcome of the comparing the one or more parameters to the one or more thresholds;

detecting a duration of the acute response being a time interval during which the presence of the acute response is declared; and

producing the acute response signal to indicate the duration of the acute response,

and wherein adjusting the intermittent cardiac stress augmentation pacing protocol comprises recommending a session frequency based on the detected duration of the acute response, the session frequency being a frequency at which the stress augmentation pacing sessions are delivered.

40. The method of claim 32, wherein producing the acute response signal comprises:

declaring one of presence and absence of the acute response using the outcome of the comparing the one or more parameters to the one or more thresholds;

detecting a duration of the acute response being a time interval during which the presence of the acute response is declared; and

producing the acute response signal to indicate the duration of the acute response,

and wherein adjusting the intermittent cardiac stress augmentation pacing protocol comprises reducing one or more of a level to which the cardiac stress is augmented during each stress augmentation pacing session of the plurality of stress augmentation pacing sessions and a duration of the each stress augmentation pacing session using the acute response signal.