Method and apparatus for atrial arrhythmia episode detection

Patent metadata

Field	Value
Publication number	US-11517242-B2
Application number	US-201916700087-A
Country	US
Kind code	B2
Filing date	Dec 2, 2019
Priority date	Feb 18, 2015
Publication date	Dec 6, 2022
Grant date	Dec 6, 2022

Abstract

Techniques and devices for implementing the techniques for adjusting atrial arrhythmia detection based on analysis of one or more P-wave sensing windows associated with one or more R-waves. An implantable medical device may determine signal characteristics of the cardiac signal within the P-wave sensing window, determine whether the cardiac signal within the sensing window corresponds to a P-wave based on the determined signal characteristics, determine a signal to noise ratio of the cardiac signal within the sensing window, update the arrhythmia score when the P-wave is identified in the sensing window and the determined signal to noise ratio satisfies a signal to noise threshold.

First claim

The invention claimed is:

1. A medical device comprising:
a plurality of electrodes configured to sense a cardiac signal; and
processing circuitry configured to:
identify one or more pairs of consecutive R-waves within the sensed cardiac signal;
determine, for each pair of consecutive R-waves of the one or more pairs of consecutive R-waves, whether an RR-interval corresponding to the respective pair of consecutive R-waves is greater than an RR-interval threshold;
identify, for each pair of consecutive of R-waves having an RR-interval greater than the RR-interval threshold, a P-wave window corresponding to the respective pair of consecutive R-waves;
determine a characteristic P-wave signal based on the cardiac signal within the one or more identified P-wave windows, wherein the characteristic P-wave signal corresponds to a characteristic P-wave window;
determine one or more signal characteristics for one or both of a baseline portion of the characteristic P-wave window and a P-wave portion of the characteristic P-wave window; and
determine, based on the determined one or more signal characteristics, whether the characteristic P-wave signal is confirmed as including a genuine P-wave.

2. The medical device of claim 1 , wherein the processing circuitry is further configured to:
determine the baseline portion of the characteristic P-wave window;
determine the P-wave portion of the characteristic P-wave window, wherein the baseline portion is prior to the P-wave portion.

3. The medical device of claim 1 , wherein to determine the characteristic P-wave signal, the processing circuitry is configured to determine an average of the cardiac signal within the one or more identified P-wave windows.

4. The medical device of claim 1 , wherein the baseline portion of the characteristic P-wave window extends from a start of the characteristic P-wave window to a midpoint of the characteristic P-wave window, and wherein the P-wave portion of the characteristic P-wave window extends from the midpoint of the characteristic P-wave window to an endpoint of the characteristic P-wave window.

5. The medical device of claim 1 , wherein to determine whether the characteristic P-wave is confirmed as including a genuine P-wave, the processing circuitry is configured to:
determine a second derivative of the characteristic P-wave signal corresponding to the P-wave portion of the characteristic P-wave window;
identify one or more maximum amplitudes in the second derivative of the characteristic P-wave signal corresponding to the P-wave portion of the characteristic P-wave window;
compare each maximum amplitude of the one or more maximum amplitudes to a first threshold;
identify one or more minimum amplitudes in the second derivative of the signal corresponding to the P-wave portion of the characteristic P-wave window;
compare each minimum amplitude of the one or more minimum amplitudes to a second threshold; and
determine that the characteristic P-wave signal is confirmed as including a genuine P-wave when:
a number of the one or more maximum amplitudes greater than or equal to the first threshold is equal to one; or
a number of the one or more minimum amplitudes less than or equal to the second threshold is equal to one.

6. The medical device of claim 5 , wherein the processing circuitry is configured to determine that the characteristic P-wave signal is not confirmed as including a P-wave when:
the number of the one or more maximum amplitudes greater than or equal to the first threshold is not equal to one; and
the number of the one or more minimum amplitudes less than or equal to the second threshold is not equal to one.

7. The medical device of claim 1 , wherein the processing circuitry is further configured to:
determine a first derivative of the characteristic P-wave signal corresponding to the characteristic P-wave window;
determine a second derivative of the characteristic P-wave signal corresponding to the characteristic P-wave window; and
determine, based on the first derivative of the characteristic P-wave signal and the second derivative of the characteristic P-wave signal, whether the characteristic P-wave signal corresponds to an atrial flutter event.

8. The medical device of claim 7 , wherein the processing circuitry is configured to:
determine the baseline portion of the characteristic P-wave window;
determine the P-wave portion of the characteristic P-wave window, wherein the baseline portion is prior to the P-wave portion;
identify one or more maximum amplitudes of the second derivative of the characteristic P-wave signal within the baseline portion of the characteristic P-wave window, wherein each maximum amplitude of the one or more maximum amplitudes is associated with a respective positive going zero crossing of the first derivative of the characteristic P-wave signal;
determine whether each maximum amplitude of the one or more maximum amplitudes within the baseline portion is greater than a first threshold amplitude;
identify one or more minimum amplitudes of the second derivative of the characteristic P-wave signal within the baseline portion of the characteristic P-wave window, wherein each minimum amplitude of the one or more minimum amplitudes is associated with a respective negative going zero crossing of the first derivative of the characteristic P-wave signal;
determine whether each minimum amplitude of the one or more minimum amplitudes within the baseline portion is less than a second threshold amplitude;
identify one or more maximum amplitudes of the second derivative of the characteristic P-wave signal within the P-wave portion of the characteristic P-wave window, wherein each maximum amplitude of the one or more maximum amplitudes is associated with a respective positive going zero crossing of the first derivative of the characteristic P-wave signal;
determine whether each maximum amplitude of the one or more maximum amplitudes within the baseline portion is greater than the first threshold amplitude;
identify one or more minimum amplitudes of the second derivative of the characteristic P-wave signal within the P-wave portion of the characteristic P-wave window, wherein each minimum amplitude of the one or more minimum amplitudes is associated with a respective negative going zero crossing of the first derivative of the characteristic P-wave signal; and
determine whether each minimum amplitude of the one or more minimum amplitudes within the P-wave portion is less than the second threshold amplitude,
wherein to determine whether the characteristic P-wave signal corresponds to an atrial flutter event, the processing circuitry is configured to:
calculate a first sum of a number of the one or more maximum amplitudes within the baseline portion greater than the first threshold amplitude and a number of the one or more maximum amplitudes within the baseline portion greater than the second threshold amplitude;
calculate a second sum of a number of the one or more maximum amplitudes within the P-wave portion greater than the first threshold amplitude and a number of the one or more maximum amplitudes within the P-wave portion greater than the second threshold amplitude;
determine whether the first sum is equal to a first target number of amplitudes; and
determine whether an absolute value of a difference between the first sum and the second sum is less than or equal to a second target number of amplitudes.

9. The medical device of claim 1 , wherein the processing circuitry is further configured to:
determine a first derivative of the characteristic P-wave signal corresponding to the characteristic P-wave window;
determine a second derivative of the characteristic P-wave signal correspondi

Assignees

• Medtronic Inc

Inventors

• Sarkar Shantanu
• Hansen Daniel L
• Neitzell Grant A
• Reiland Jerry D
• Wyszynski Ryan

Classifications

• A61B5/363

  Detecting tachycardia or bradycardia · CPC title

• A61B5/349 Primary

  Detecting specific parameters of the electrocardiograph cycle · CPC title

• A61B5/24

  Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof · CPC title

• A61N1/36592

  controlled by the heart rate variability · CPC title

• A61B5/686

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