Atrial arrhythmia episode detection in a cardiac medical device

Patent metadata

Field	Value
Publication number	US-10213125-B2
Application number	US-201514604468-A
Country	US
Kind code	B2
Filing date	Jan 23, 2015
Priority date	Jan 23, 2015
Publication date	Feb 26, 2019
Grant date	Feb 26, 2019

Abstract

A method and medical device for detecting a cardiac event that includes sensing a cardiac signal, determining RR-intervals in response to the sensed cardiac signal, detecting a cardiac event in response to the RR-intervals, iteratively sensing a predetermined number of P-waves in response to detecting the cardiac event, and confirming the cardiac event in response to the iteratively sensed P-waves.

First claim

We claim:

1. A method of detecting an atrial fibrillation (AF) event in a medical device, comprising:
sensing a cardiac signal;
identifying a plurality of R-waves in the cardiac signal;
determining a plurality of RR-intervals based on the plurality of identified R-waves in the sensed cardiac signal;
detecting the AF event based on at least the plurality of determined RR-intervals;
iteratively sensing a predetermined number of P-waves in response to detecting the AF event;
determining one or more P-wave parameters associated with each of the iteratively sensed predetermined number of P-waves; and
confirming the AF event based on the P-wave parameters of the iteratively sensed predetermined number of P-waves.

2. The method of claim 1 , further comprising :
determining relative changes of the P-waves based on the determined P-wave parameters;
determining whether each of the P-waves match within a match threshold based on the determined relative changes; and
updating a counter in response to each of the P-waves matching within the match threshold, wherein confirming the AF event comprises confirming the AF event in response to the counter exceeding a counter threshold during a predetermined time period.

3. The method of claim 2 , wherein determining relative changes of the P-waves comprises:
determining one or more of:
a width change for each of the P-waves;
an amplitude change for each of the P-waves; or
a magnitude change for each of the P-waves; and

determining the relative changes of the P-waves based on the one or more of the width change the amplitude change or the magnitude change.

4. The method of claim 1 , further comprising:
determining a P-wave window associated with each of identified R-waves; and
adjusting the P-waves within each of the determined P-wave windows;
wherein determining the one or more P-wave parameters comprises determining the one or more parameters associated with each of the adjusted P-waves.

5. The method of claim 4 , further comprising:
determining, for each of the P-waves, a maximum amplitude;
determining, for each of the P-waves, a first minimum baseline point and a second minimum baseline point as a portion of the maximum amplitude;
determining, for each of the P-waves, an area based on a baseline extending between the first minimum baseline point and the second minimum baseline point;
normalizing each of the P-waves based on the area and the baseline; and
confirming the AF event using the normalized P-waves.

6. The method of claim 5 , wherein normalizing the P-waves comprises:
determining a normalized amplitude of each of the P-waves; and
determining a center of the area of each of the normalized P-waves based on a width of the baseline and the normalized amplitude.

7. The method of claim 4 , wherein determining relative changes of the P-waves comprises:
determining one or more of:
a width change for each of the P-waves;
an amplitude change for each of the P-waves; or
a magnitude change for each of the P-waves; and

determining the relative changes of the P-waves based on the one or more of the width change the amplitude change and the magnitude change.

8. The method of claim 1 , wherein iteratively sensing a predetermined number of P-waves in response to detecting the AF event comprises:
determining second RR-intervals in response to the sensed cardiac signal subsequent to detecting the AF event;
determining second P-wave parameters associated with P-waves determined in response to the second RR-interval;
determining relative changes of the second P-waves in response to the determined second P-wave parameters;
determining whether each of the second P-waves match within a match threshold in response to the determined relative changes; and
updating a counter in response to each of the P-waves matching within the match threshold, wherein the AF event is confirmed in response to the counter exceeding a counter threshold during a predetermined time period.

9. The method of claim 1 , further comprising controlling, by the medical device, the delivery of a therapy based on the confirmation of the AF event.

10. A medical device for detecting an AF event, comprising:
a plurality of electrodes sensing a cardiac signal; and
a processor configured to identify a plurality of R-waves in the cardiac signal, determine a plurality of RR-intervals in based on the plurality of identified R-waves the sensed cardiac signal, detect the AF based on at least the plurality of determined RR-intervals, iteratively sense a predetermined number of P-waves in response to detecting the AF event, determine one or more P-wave parameters associated with each of the iteratively sensed predetermined number of P-waves and confirm the AF event based on the P-wave parameters of the iteratively sensed predetermined number of P-waves.

11. The medical device of claim 10 , wherein the processor is further configured to determine relative changes of the P-waves based on the determined P-wave parameters, determine whether each of the P-waves match within a match threshold based on the determined relative changes, and update a counter in response to each of the P-waves matching within the match threshold, wherein the AF event is confirmed in response to the counter exceeding a counter threshold during a predetermined time period.

12. The medical device of claim 11 , wherein the processor is further configured to determine one or more of a width change for each of the P-waves, an amplitude change for each of the P-waves, or a magnitude change for each of the P-waves and determine the relative changes of the P-waves based on the one or more of the width change, the amplitude change, or the magnitude change.

13. The medical device of claim 10 , wherein the processor is further configured to determine a P-wave window associated with each of identified R-waves, adjust the P-waves within each of the determined P-wave windows, and determine the one or more P-wave parameters associated with each of the adjusted P-waves.

14. The medical device of claim 13 , wherein the processor is further configured to determine, for each of the P-waves, a maximum amplitude, determine, for each of the P-waves, a first minimum baseline point and a second minimum baseline point as a portion of the maximum amplitude for each of the P-waves, an area based on a baseline extending between the first minimum baseline point and the second minimum baseline point, normalize each of the P-waves based on the area and the baseline, and confirm the AF event based on the normalized P-wave.

15. The medical device of claim 14 , wherein the processor is further configured to determine a normalized amplitude of each of the P-waves, and determine a center of area of the area of each of the normalized P-waves based on a width of the baseline and the normalized amplitude.

16. The medical device of claim 13 , wherein the processor is further configured to determine one or more of a width change for each of the P-waves, an amplitude change for each of the P-waves, or a magnitude change for each of the P-waves and determine the relative changes of the P-waves based on the one or more of the width change, the amplitude change, or the magnitude change.

17. The medical device of claim 10 , wherein the processor is further configured to determine second RR-intervals in response to the sensed cardiac signal subsequent to detecting the AF event, determine second P-wave parameters associated with P-waves determined in response to the second RR-interval, determine relative changes of the second

Assignees

• Medtronic Inc

Inventors

• Cao Jian
• Degroot Paul J

Classifications

• A61B5/686 Primary

  Permanently implanted devices, e.g. pacemakers, other stimulators, biochips (A61B5/6861 takes precedence) · CPC title

• A61B5/04525

  Human Necessities · mapped topic

• A61B5/0456 Primary

  Human Necessities · mapped topic

• A61B5/046

  Human Necessities · mapped topic

• A61B5/4836

  Diagnosis combined with treatment in closed-loop systems or methods (A61B5/0036 takes precedence) · CPC title