Determination of phrenic nerve stimulation threshold

• US 8,958,876 B2
• Filed: 02/28/2013
• Issued: 02/17/2015
• Est. Priority Date: 03/27/2012
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Dong, Yanting, Saha, Sunipa, Rockweiler, Holly
• Primary Examiner(s): Koharski, Christopher D
• Assistant Examiner(s): CAREY, MICHAEL JAMES
• Application Number:
  US13/781,042
• Publication Number:
  US 20130261688A1
• Time in Patent Office: 719 Days
• Field of Search: 600/510, 607/11, 607/17, 607/28
• US Class Current: 607/28
• 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 5/4029 for evaluating the peripheral nervous systems A61B5/24 takes precedence
• CPC Class Codes: A61B 5/7264 Classification of physiological signals or data, e.g. using neural networks, statistical classifiers, expert systems or fuzzy systems neural networks per se G06N3/00; expert systems per se G06N5/00
• CPC Class Codes: A61B 5/7282 Event detection, e.g. detecting unique waveforms indicative of a medical condition A61B5/4094, A61B5/4818, A61B5/349, A61B5/0823 take precedence
• CPC Class Codes: A61N 1/36542 controlled by body motion, e.g. acceleration
• CPC Class Codes: A61N 1/371 Capture, i.e. successful stimulation
• CPC Class Codes: G16H 50/20 for computer-aided diagnosis, e.g. based on medical expert systems

Abstract

In an example of a method, the method includes testing for phrenic nerve stimulation (PS) threshold. If PS beats are detected at the pacing output level, analyzing the detected PS beats using criteria to determine if the pacing output level can be declared to be the PS threshold. If the pacing output level cannot be declared to be the PS threshold based on the analysis of the PS beat at the pacing output level, performing a PS beat confirmation procedure. The PS beat confirmation procedure may include delivering additional cardiac paces at the pacing output level to generate additional PS beats, and analyzing the detected PS beats using other criteria to determine if the pacing output level can be confirmed as the PS threshold.

Claims

1. A method, comprising:

testing for phrenic nerve stimulation (PS) threshold, including;

pacing a heart with cardiac paces at a pacing output level;

sensing a physiological signal for use in detecting PS beats, wherein the PS beats are cardiac paces that induce phrenic nerve stimulation; and

monitoring for PS beats in the sensed physiological signal to detect if the pacing output level causes PS beats;

if PS beats are detected at the pacing output level, analyzing the detected PS beats using criteria to determine if the pacing output level can be declared to be the PS threshold; and

if the pacing output level cannot be declared to be the PS threshold based on the analysis of the PS beat at the pacing output level, performing a PS beat confirmation procedure including;

delivering additional cardiac paces at the pacing output level to generate additional PS beats; and

analyzing the detected PS beats using other criteria to determine if the pacing output level can be confirmed as the PS threshold.

2. The method of claim 1, wherein testing for phrenic nerve stimulation threshold includes performing a step-up test, the step-up test including if PS beats are not detected at the pacing output level, increasing the pacing output level and retesting for the phrenic nerve stimulation threshold at the increased pacing output level.

3. The method of claim 2, wherein in performing the step-up test, analyzing the detected PS beats using criteria to determine if the pacing output level can be declared to be the PS threshold includes determining if a number of detected PS beats is greater than a defined number to declare the pacing threshold to be the PS threshold.

4. The method of claim 2, wherein in performing the step-up test, analyzing the detected PS beats using criteria to determine if the pacing output level can be declared to be the PS threshold includes determining if a ratio of an amplitude of the PS beats to a baseline output level exceed a defined number to declare the pacing threshold to be the PS threshold.

5. The method of claim 2, wherein in performing the step-up test, analyzing the detected PS beats using criteria to determine if the pacing output level can be declared to be the PS threshold includes:

determining if a number of detected PS beats is greater than a defined number to declare the pacing threshold to be the PS threshold; and

determining if a ratio of an amplitude of the PS beats to a baseline output level exceed a defined number to declare the pacing threshold to be the PS threshold.

6. The method of claim 2, wherein increasing the paced output level includes dynamically adjusting an interval for increasing the pacing output level based on the analysis of the PS beats.

7. The method of claim 2, wherein if the pacing output level cannot be declared to be the PS threshold based on the analysis of the detected PS beats using the other criteria, performing a second PS beat confirmation procedure including:

increasing the pacing output level, and delivering additional cardiac paces at the increased pacing output level to generate additional PS beats; and

analyzing the detected PS beats at the increased pacing output level using criteria to determine if the pacing output level can be confirmed as the PS threshold.

8. The method of claim 2, wherein if the pacing output level cannot be declared to be the PS threshold based on the analysis of the detected PS beats using the other criteria, performing a second PS beat confirmation procedure including:

delivering additional cardiac paces at the pacing output level to generate additional PS beats; and

analyzing the detected PS beats using different criteria to determine if the pacing output level can be confirmed as the PS threshold.

9. The method of claim 8, further comprising:

decreasing the pacing output level if the pacing output level cannot be confirmed as the PS threshold using the different criteria;

delivering additional cardiac paces at the decreased pacing output level to generate additional PS beats; and

comparing the detected PS beats at the decreased pacing output level for characteristics similar to the detected PS beats previously analyzed using the different criteria.

10. The method of claim 1, wherein testing for phrenic nerve stimulation threshold includes performing a step-down test, the step-down test including decreasing the pacing output level if the detected PS beats indicate that the pacing output level is higher than the PS threshold.

11. The method of claim 10, wherein in performing the step-down test, analyzing the detected PS beats using criteria to determine if the pacing output level can be declared to be the PS threshold includes determining if a number of detected PS beats is less than a defined number to declare the pacing threshold to be the PS threshold.

12. The method of claim 10, wherein in performing the step-down test, analyzing the detected PS beats using criteria to determine if the pacing output level can be declared to be the PS threshold includes determining if a ratio of an amplitude of the PS beats to a baseline output level is less than a defined number to declare the pacing threshold to be the PS threshold.

13. The method of claim 10, wherein in performing the step-down test, analyzing the detected PS beats using criteria to determine if the pacing output level can be declared to be the PS threshold includes:

determining if a number of detected PS beats is less than a defined number to declare the pacing threshold to be the PS threshold; and

determining if a ratio of an amplitude of the PS beats to a baseline output level is less than a defined number to declare the pacing threshold to be the PS threshold.

14. The method of claim 1, wherein the method is performed by using an implantable medical device in an ambulatory patient away from a clinical setting.

15. The method of claim 1, wherein the method is performed in a clinical setting.

16. The method of claim 1, wherein if the pacing output level cannot be declared to be the PS threshold based on the analysis of the detected PS beats using the other criteria, changing the pacing output level, delivering additional cardiac paces at the changed pacing output level, and analyzing the sensed physiological signal at the changed pacing output level using criteria to determine if the pacing output level can be confirmed as the PS threshold.

17. The method of claim 16, wherein analyzing the sensed physiological signal at the changed pacing output level includes comparing:

a number of detected PS beats to a defined number, or

a ratio of an amplitude of detected PS beats to a baseline output to a defined ratio.

18. A system, comprising:

a cardiac pulse generator configured to generate cardiac paces to pace the heart;

a sensor configured to sense a physiological signal for use in detecting pace-induced phrenic nerve stimulation, wherein the pace-induced phrenic nerve stimulation is phrenic nerve stimulation induced by electrical cardiac pace signals;

a phrenic nerve stimulation detector configured to analyze the sensed physiological signal to detect PS beats, wherein the PS beats are cardiac paces that induce phrenic nerve stimulation;

a controller configured to test for phrenic nerve stimulation (PS) threshold, wherein the controller is configured to;

control the cardiac pulse generator to deliver cardiac paces at a pacing output level;

use the phrenic nerve stimulation detector to detect if the pacing output level causes PS beats;

analyze the detected PS beats, if PS beats are detected at the pacing output level, using criteria to determine if the pacing output level can be declared to be the PS threshold; and

perform a PS beat confirmation procedure, if the pacing output level cannot be declared to be the PS threshold based on the analysis of the PS beat at the pacing output level, that includes delivering additional cardiac paces at the pacing output level to generate additional PS beats, and analyzing the detected PS beats using other criteria to determine if the pacing output level can be confirmed as the PS threshold.

19. The system of claim 18, wherein:

the controller is configured to perform a step-up test, the step-up test including increasing the pacing output level and retesting for the phrenic nerve stimulation threshold at the increased pacing output level if PS beats are not detected at the pacing output level;

or

the controller is configured to perform a step-down test, the step-down including decreasing the pacing output level if the detected PS beats indicate that the pacing output level is higher than the PS threshold.

20. A method, comprising:

testing for phrenic nerve stimulation (PS) threshold, including;

pacing a heart with cardiac paces at a pacing output level;

sensing a physiological signal tier use in detecting PS beats, wherein the PS beats are cardiac paces that induce phrenic nerve stimulation; and

monitoring for PS beats in the sensed physiological signal to detect if the pacing output level causes PS beats;

if PS beats are detected at the pacing output level, analyzing the detected PS beats using criteria to determine if the pacing output level can be declared to be the PS threshold; and

if the pacing output level cannot be declared to be the PS threshold based on the analysis of the PS beat at the pacing output level, performing a PS beat confirmation procedure including;

changing the pacing output level;

delivering additional cardiac paces at the changed pacing output level; and

analyzing the sensed physiological signal at the changed pacing output level using criteria to determine if the pacing output level can be confirmed as the PS threshold.