Adaptive phrenic nerve stimulation detection

• US 9,272,151 B2
• Filed: 07/11/2013
• Issued: 03/01/2016
• Est. Priority Date: 07/12/2012
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Siejko, Krzysztof Z., Saha, Sunipa, McCabe, Aaron R., Rockweiler, Holly
• Primary Examiner(s): Holmes, Rex R
• Application Number:
  US13/939,790
• Publication Number:
  US 20140018872A1
• Time in Patent Office: 964 Days
• US Class Current: 1/1
• CPC Class Codes: A61B 5/24 Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
• CPC Class Codes: A61B 5/389 Electromyography [EMG]
• CPC Class Codes: A61B 5/4041 Evaluating nerves condition
• CPC Class Codes: A61B 5/4836 Diagnosis combined with treatment in closed-loop systems or methods A61B5/0036 takes precedence
• CPC Class Codes: A61B 5/7235 Details of waveform analysis A61B5/349 takes precedence
• CPC Class Codes: A61N 1/3686 configured for selecting the electrode configuration on a lead A61N1/3688 takes precedence
• CPC Class Codes: A61N 1/3706 Pacemaker parameters stimulation threshold A61N1/371
• CPC Class Codes: A61N 1/371 Capture, i.e. successful stimulation

Abstract

An example of a system comprises 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 (PS), a storage, and a phrenic nerve stimulation detector. The storage is configured for use to store patient-specific PS features for PS beats with a desirably large signal-to-noise ratio. The phrenic nerve stimulation detector may be configured to detect PS features for the patient by analyzing a PS beat with a desirably large signal-to-noise ratio induced using a pacing pulse with a large energy output and store patient-specific PS features in the storage, and use the patient-specific PS features stored in the memory to detect PS beats when the heart is paced heart using cardiac pacing pulses with a smaller energy output.

Claims

1. A system, comprising:

a cardiac pulse generator configured to generate cardiac pacing pulses to pace the heart, wherein the cardiac pulse generator is configured to generate cardiac pacing pulses throughout a range of cardiac pacing energy outputs, wherein;

cardiac pacing energy outputs above a myocardial capture threshold capture myocardia for a cardiac tissue stimulation therapy, and

cardiac pacing energy outputs above a pace-induced phrenic nerve stimulation (PS) threshold, which is larger than the myocardial capture threshold, induce PS which is undesirable for the cardiac tissue stimulation therapy;

a sensor configured to sense a physiological signal for use in detecting PS, wherein an amplitude of the physiological signal is dependent on the cardiac pacing energy output such that increasing cardiac pacing energy output increases the amplitude and decreasing cardiac pacing energy output decreases the amplitude;

a storage for storing a patient-specific PS template of patient-specific PS features for use to detect PS beats, wherein the PS beats are cardiac paces that induce PS; and

a phrenic nerve stimulation detector configured to create the patient-specific PS template and use the template to detect PS beats, including;

control the cardiac pulse generator to intentionally deliver a PS beat, including generate cardiac pacing pulses with a large cardiac pacing energy output that is significantly larger than the PS threshold, detect the patient-specific PS features for the patient by analyzing the physiologic signal that results from the intentionally-delivered PS beat, and store the patient-specific PS features for the template in the storage;

control the cardiac pulse generator to decrease the pacing energy output from the large energy output to a smaller cardiac pacing energy output; and

use the patient-specific PS features for the template in the storage to analyze the physiologic signal for detecting PS beats when the heart is paced using cardiac pacing pulses with the smaller cardiac pacing energy output.

2. The system of claim 1, wherein the system is configured to perform a PS threshold test that includes:

pacing the heart using cardiac pacing pulses, including sweeping a pacing energy output according to a protocol; and

using the patient-specific PS template of patient-specific PS features to detect PS beats induced by the cardiac pacing pulses; and

determining the cardiac pacing pulses with a smallest pacing energy output that induce PS beats.

3. The system of claim 2, wherein the protocol includes a fixed or adaptive pacing protocol.

4. The system of claim 2, further comprising a plurality of pacing electrodes, wherein the system is configured to:

select pacing electrodes from the plurality of pacing electrodes to provide a pacing vector;

control a selection of pacing vectors from a plurality of available pacing vectors for use to pace the heart;

create a patient-specific template of PS features for PS beats in the patient for each of the plurality of available pacing vectors for each of the plurality of available pacing vectors, by pacing the heart using a pacing pulse with a large energy output significantly larger than the PS threshold, and analyzing the physiologic signal that results from the large energy output to identify patient-specific PS features;

pace the heart for each of the plurality of available pacing vectors using cardiac pacing pulses by sweeping a pacing energy output according to a protocol, using the PS features to detect PS beats induced by the cardiac pacing pulses, and determining a PS threshold for each of the plurality of available pacing vectors, where in the PS threshold is a smallest pacing energy output that induce PS beats.

5. The system of claim 4, wherein the system is configured to identify at least one of the plurality of available pacing vectors that has a large PS threshold for use to pace the heart.

6. The system of claim 1, wherein the phrenic nerve stimulation detector is configured to use the patient-specific PS features stored in the memory to detect PS beats.

7. The system of claim 1, wherein to detect the patient-specific PS features, the phrenic nerve stimulation detector is configured to screen for PS beats in a timing window and ensemble an average of the largest detected PS beats.

8. The system of claim 1, wherein the patient-specific PS features include peak characteristics and zero crossing characteristics of at least one sensed PS beat signal, wherein to use the patient-specific PS features for the template in the storage to detect PS beats, the phrenic nerve stimulation detector is configured to compare a sensed signal to the peak characteristics and the zero crossing characteristics of the at least one sensed PS beat signal.

9. The system of claim 8, wherein the patient-specific PS features include:

a time from a pace to and an amplitude of a first peak;

a time from the pace to and an amplitude of a second peak;

a time from the pace to a zero crossing between first and second peaks; and

a time from the pace to a zero crossing after the second peak.

10. The system of claim 8, wherein to compare the sensed signal to the peak characteristics and the zero crossing characteristics of the at least one sensed PS beat signal, the phrenic nerve stimulation detector is configured to compare feature vectors between the measured features in the sensed signal and the patient-specific PS features.

11. The system of claim 8, wherein to compare the sensed signal to the peak characteristics and the zero crossing characteristics of the at least one sensed PS beat signal, the phrenic nerve stimulation detector is configured to perform an amplitude-normalized correlation between measured features in the sensed signal and the patient-specific PS features.

12. A method for detecting PS beats in a patient, wherein the PS beats are cardiac paces that induce phrenic nerve stimulation (PS), the method comprising:

creating a patient-specific PS template of PS features, including;

pacing the heart using a pacing pulse with a large cardiac pacing energy output that is significantly greater than a PS threshold to intentionally deliver a PS beat, wherein cardiac pacing energy outputs above the PS threshold induce PS; and

sensing and analyzing a physiological signal that results from the intentionally-delivered PS beat to identify the PS features for the patient-specific template, wherein an amplitude of the physiological signal is dependent on the cardiac pacing energy output such that increasing cardiac pacing energy output increases the amplitude and decreasing cardiac pacing energy output decreases the amplitude;

pacing the heart using cardiac pacing pulses with a smaller energy output; and

using the PS features for the patient-specific template to detect PS beats when the heart is paced with the smaller energy output.

13. The method of claim 12, wherein the PS features include peak characteristics and zero crossing characteristics of at least one sensed PS beat signal.

14. The method of claim 13, wherein the PS features include:

a time from a pace to and an amplitude of a first peak;

a time from the pace to and an amplitude of a second peak;

a time from the pace to a zero crossing between first and second peaks; and

a time from the pace to a zero crossing after the second peak.

15. The method of claim 12, wherein using the PS features for the patient-specific template to detect PS beats includes comparing feature vectors between measured features in a sensed signal and the PS features.

16. The method of claim 12, wherein using the PS features for the patient-specific template to detect PS beats includes performing an amplitude-normalized correlation between measured features in a sensed signal and the PS features.

17. The method of claim 12, wherein creating the patient-specific template includes screening for PS beats in a timing window and ensembling an average of the largest detected PS beats.

18. The method of claim 12, further comprising detecting a PS threshold for PS beats including:

sweeping a pacing energy output according to a protocol to pace the heart using the cardiac pacing pulses; and

determining the cardiac pacing pulses with a smallest pacing energy output that induce PS.

19. The method of claim 18, wherein:

the PS features include peak characteristics and zero crossing characteristics of at least one sensed PS beat signal; and

using the PS features for the patient-specific template to detect PS beats includes;

comparing feature vectors between measured features in a sensed signal and the PS features;

or

performing an amplitude-normalized correlation between measured features in a sensed signal and the PS features.

20. A method for selecting a pacing vector from a plurality of available pacing vectors for use to pace a heart of a patient, comprising:

creating a patient-specific PS template of PS features for PS beats for each of the plurality of available pacing vectors, wherein the PS beats are cardiac paces that induce phrenic nerve stimulation, and creating the patient-specific template includes, for each of the plurality of available pacing vectors, pacing the heart using a pacing pulse with a large cardiac pacing energy output that is significantly greater than a PS threshold to intentionally deliver a PS beat, wherein cardiac pacing energy outputs above the PS threshold induce PS, and sensing and analyzing a physiological signal that results from the intentionally-delivered PS beat to identify the PS features for the patient-specific template;

pacing the heart for each of the plurality of available pacing vectors using cardiac pacing pulses including sweeping a cardiac pacing energy output according to a protocol, using the PS features for the patient-specific template to detect PS beats when the heart is paced with a smaller cardiac energy output than the large cardiac pacing output, and determining the PS threshold for each of the plurality of available pacing vectors; and

identifying at least one of the plurality of available pacing vectors with a large PS threshold for use to pace the heart.