Unwanted stimulation detection during cardiac pacing

• US 9,533,159 B2
• Filed: 08/26/2014
• Issued: 01/03/2017
• Est. Priority Date: 08/30/2013
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation), TiJEE Corporation
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Rockweiler, Holly E., Olson, David C., Saha, Sunipa
• Primary Examiner(s): Layno, Carl H
• Assistant Examiner(s): Morales, Jon Eric C
• Application Number:
  US14/469,250
• Publication Number:
  US 20150066102A1
• Time in Patent Office: 861 Days
• Field of Search: 607 27- 28
• US Class Current: 1/1
• CPC Class Codes: A61B 2562/0219 Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
• CPC Class Codes: A61B 5/1107 Measuring contraction of parts of the body, e.g. organ, muscle apparatus for measuring work or force in general G01L
• CPC Class Codes: A61B 5/24 Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
• CPC Class Codes: A61B 5/388 Nerve conduction study, e.g. detecting action potential of peripheral nerves
• CPC Class Codes: A61B 5/726 using Wavelet transforms
• CPC Class Codes: A61N 1/36542 controlled by body motion, e.g. acceleration
• CPC Class Codes: A61N 1/3704 Circuits specially adapted therefor, e.g. for sensitivity control
• CPC Class Codes: A61N 1/371 Capture, i.e. successful stimulation

Abstract

The disclosure relates to systems and methods for cardiac rhythm management. In some cases, a system may include a pulse generator for generating pacing pulses for stimulating a heart of a patient; a memory; and a sensor configured to sense a response to a unwanted stimulation and to produce a corresponding sensor signal. A processing circuit may receive the sensor signal for a time after one or more pacing pulses, and may derive a time-frequency representation of the sensor signal based on the received sensor signal. The processing circuit may use the time-frequency representation of the sensor signal to help identify unwanted stimulation. Once unwanted stimulation is detected, the processing circuit may change the pacing pulses to help reduce or eliminate the unwanted stimulation.

Claims

1. A system for cardiac rhythm management comprising:

a pulse generator for generating pacing pulses for stimulating a heart of a patient;

a memory;

a sensor configured to sense a response to a stimulation of a phrenic nerve of the patient and to produce a sensor signal;

a processing circuit in communication with the memory and the sensor, the processing circuit configured to;

receive the sensor signal;

derive a time-frequency representation of the sensor signal based on the received sensor signal;

determine if the phrenic nerve of the patient has been stimulated by comparing one or more of a frequency characteristic of the time-frequency representation of the sensor signal to a stored frequency band, and a time characteristic of the time-frequency representation of the sensor signal to a time window following a pacing pulse;

store a phrenic nerve stimulation event identifier in the memory if the processing circuit determines that the phrenic nerve of the patient has been stimulated.

2. The system of claim 1, wherein the time-frequency representation of the sensor signal is derived using wavelets.

3. The system of claim 1, wherein the sensor includes one or more of an accelerometer, a minute ventilation sensor, an electrical signal sensor, a pressure sensor, and an acoustic sensor that is configured to sense a measure indicative of a response to a stimulation of the phrenic nerve of the patient.

4. The system of claim 1, wherein the processing circuit determines that the phrenic nerve of the patient has been stimulated if a dominant frequency of the time-frequency representation of the sensor signal is seen to occur within the frequency band and the within the time window following the pacing pulse.

5. The system of claim 1, wherein the processing circuit determines that the phrenic nerve of the patient has been stimulated if a dominant frequency of the time-frequency representation of the sensor signal is seen to occur within the frequency band.

6. The system of claim 1, wherein the time-frequency representation of the sensor signal is derived using Morlet wavelets.

7. The system of claim 1, wherein the time-frequency representation of the sensor signal is derived using a continuous wavelet transform.

8. The system of claim 1, further comprising a filter to filter the received sensor signal.

9. The system of claim 1, wherein the sensor includes an accelerometer that produces a raw acceleration sensor signal, and wherein the sensor includes a filter for filtering the raw acceleration sensor signal before providing the sensor signal.

10. The system of claim 1, wherein generating pacing pulses for stimulating the heart of a patient includes decreasing a pacing pulse energy by a specified amount if phrenic nerve stimulation is detected.

11. The system of claim 10, wherein generating pacing pulses for stimulating the heart of a patient includes performing a capture verification during a subsequent pacing pulse after the pacing pulse energy has been reduced and increasing the pacing pulse energy by a specified amount if no capture was achieved.

12. The system of claim 11, wherein generating pacing pulses for stimulating the heart of a patient includes performing a capture verification during a subsequent pacing pulse after the pacing pulse energy has been reduced and by responding to a lack of capture by one of increasing the pacing pulse energy by a specified amount and altering the selected pacing configuration if no capture was achieved.

13. The system of claim 1, wherein the processing circuit further is configured to generate pacing pulses for stimulating the heart of a patient that are anticipated to both capture the heart and to minimize phrenic nerve stimulation by the generated pacing pulses;

and

determine if capture of the heart has been achieved.

14. A system for cardiac rhythm management comprising:

a pulse generator for generating pacing pulses for stimulating the heart of a patient;

a memory;

a sensor configured to sense a response to a stimulation of a phrenic nerve of the patient and to produce a sensor signal;

a processing circuit in communication with the memory and the sensor, the processing circuit configured to;

receive the sensor signal;

derive a power spectrum based on the received sensor signal;

determine if the phrenic nerve of the patient has been stimulated based, at least in part, on the derived power spectrum; and

store a phrenic nerve stimulation event identifier in the memory if the processing circuit determines that the phrenic nerve of the patient has been stimulated;

generate pacing pulses for stimulating the heart of a patient configured to both capture the heart and to minimize phrenic nerve stimulation by the generated pacing pulses; and

determine if capture of the heart has been achieved.

15. The system of claim 14, wherein the sensor includes one or more of an accelerometer, a minute ventilation sensor, an electrical signal sensor, a pressure sensor, and an acoustic sensor, that is configured to sense an acceleration indicative of a response to a stimulation of the phrenic nerve of the patient.

16. The system of claim 14, further comprising a filter to filter the received sensor signal.

17. The system of claim 14, wherein generating pacing pulses for stimulating the heart of a patient includes decreasing a pacing pulse energy by a specified amount if skeletal muscle contraction has been detected.