Method and system to detect noise in cardiac arrhythmic patterns

Patent metadata

Field	Value
Publication number	US-11844630-B2
Application number	US-202218085524-A
Country	US
Kind code	B2
Filing date	Dec 20, 2022
Priority date	May 7, 2018
Publication date	Dec 19, 2023
Grant date	Dec 19, 2023

Abstract

Computer implemented methods and systems for detecting noise in cardiac activity are provided. The method and system obtain a far field cardiac activity (CA) data set that includes far field CA signals for a series of beats, overlay a segment of the CA signals with a noise search window, and identify turns in the segment of the CA signals. The method and system determine whether the turns exhibit a turn characteristic that exceed a turn characteristic threshold, declare the segment of the CA signals as a noise segment based on the determining operation, shift the noise search window to a next segment of the CA signal and repeat the identifying, determining and declaring operations; and modify the CA signals based on the declaring the noise segments.

First claim

What is claimed is:

1. A computer implemented method for verifying or denying a previously detected candidate episode in cardiac activity, the method comprising:
under control of one or more processors configured with specific executable instructions, verifying or denying the candidate episode by:
obtaining a far field cardiac activity (CA) data set that includes far field CA signals for a series of beats;
identifying a noise search window overlaying a segment of the CA signals between a T-wave and subsequent QRS complex;
identifying turns in the segment of the CA segments within the noise search window;
determining a turn characteristic of the identified turns;
declaring the segment of the CA signals as a noise segment based on the turn characteristic of the identified turns in the noise window; and
classifying the candidate episode to be a false arrhythmia detection based on the declaring the noise segment.

2. The method of claim 1 , wherein the identifying the noise search window comprises identifying an R-wave marker in the CA signals and positioning the noise search window to precede the R-wave marker by a predetermined time interval.

3. The method of claim 1 , wherein the identifying the noise search window comprises identifying an R-wave marker and a T-wave marker in the CA signals and positioning the noise search window after the T-wave marker and before the R-wave marker.

4. The method of claim 1 , wherein the identifying turns in the segment of the CA signals comprises determining points in which a first derivative of the CA signals changes sign.

5. The method of claim 1 , further comprising removing the noise segment from the CA signals to form noise-corrected CA signals.

6. The method of claim 5 , further comprising applying an arrhythmia detection process, based on R-R interval variability, to the noise-corrected CA signals.

7. The method of claim 1 , further comprising determining that the turn characteristic of at least some of the turns exceeds a turn characteristic threshold, and the segment of the CA signals is declared as the noise segment in response to determining that the at least some of the turns exhibit the turn characteristic that exceeds the turn characteristic threshold.

8. The method of claim 7 , wherein the turn characteristic includes one or both of a turn amplitude or a turn frequency.

9. The method of claim 8 , further comprising setting a first candidate noise flag to indicate a presence of noise in response to determining that the turn amplitude of the turns in the segment exceeds a turn amplitude threshold, and setting a second candidate noise flag to indicate the presence of noise in response to determining that the turn frequency of the turns in the segment exceeds a turn frequency threshold.

10. The method of claim 1 , wherein the one or more processors are disposed within an implantable cardiac monitor.

11. The method of claim 1 , further comprising determining a turn characteristic of the identified turns, wherein the segment of the CA signals is declared to be the noise segment based on the turn characteristic.

12. A system for verifying or denying a previously detected candidate episode in cardiac activity, the system comprising:
a memory to store specific executable instructions; and
one or more processors configured to execute the specific executable instructions to verify or deny the candidate episode, the one or more processors configured to:
obtain a far field cardiac activity (CA) data set that includes far field CA signals for a series of beats;
identify a noise search window overlaying a segment of the CA signals between a T-wave and subsequent QRS complex;
identify turns in the segment of the CA segments within the noise search window;
determine a turn characteristic of the identified turns;
declare the segment of the CA signals as a noise segment based on the turn characteristic of the identified turns in the noise window; and
classify the candidate episode to be a false arrhythmia detection based on the declaring the noise segment.

13. The system of claim 12 , wherein the one or more processors are configured to identify the noise search window by identifying an R-wave marker and a T-wave marker in the CA signals and positioning the noise search window after the T-wave marker and before the R-wave marker.

14. The system of claim 12 , wherein the one or more processors are configured to identify the turns in the segment of the CA signals by determining points in which a first derivative of the CA signals changes sign.

15. The system of claim 12 , wherein the one or more processors are configured to remove the noise segment from the CA signals to form noise-corrected CA signals.

16. The system of claim 15 , wherein the one or more processors are configured to apply an arrhythmia detection process, based on R-R interval variability, to the noise-corrected CA signals.

17. The system of claim 12 , wherein the one or more processors are configured to determine that the turn characteristic of at least some of the turns exceeds a turn characteristic threshold, and the one or more processors are configured to declare the segment as the noise segment in response to determining that the at least some of the turns exhibit the turn characteristic that exceeds the turn characteristic threshold.

18. The system of claim 17 , wherein the turn characteristic includes both a turn amplitude and a turn frequency.

19. The system of claim 18 , wherein the one or more processors are configured to (i) designate a subset of the turns as substantial turns based on the turn amplitude, (ii) analyze the turn frequency for the substantial turns, and (iii) declare the segment as the noise segment based on the analysis of the turn frequency for the substantial turns.

20. The system of claim 12 , further comprising an implantable cardiac monitor that houses the memory and the one or more processors, the implantable cardiac monitor including one or more sensors to obtain the CA signals.

21. The system of claim 12 , wherein the one or more processors are configured to identify the noise search window by identifying an R-wave marker in the CA signals and positioning the noise search window to precede the R-wave marker by a predetermined time interval.

22. The system of claim 12 , wherein the one or more processors are configured to determine a turn characteristic of the identified turns, wherein the segment of the CA signals is declared to be the noise segment based on the turn characteristic.

Assignees

• Pacesetter Inc

Inventors

• Gill Jong
• Qu Fujian
• Malhotra Neha
• Rosenberg Stuart
• Bornzin Gene A
• Dawoud Fady

Classifications

• A61B5/7217 Primary

  of noise originating from a therapeutic or surgical apparatus, e.g. from a pacemaker · CPC title

• A61B5/352

  Detecting R peaks, e.g. for synchronising diagnostic apparatus; Estimating R-R interval · CPC title

• A61B5/361

  Detecting fibrillation · CPC title

• A61B5/686

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