System and Method for Mapping Cardiac Activity

• US 20190320927A1
• Filed: 03/06/2019
• Published: 10/24/2019
• Est. Priority Date: 04/18/2018
• Status: Active Grant

• Current Assignee: St. Jude Medical Cardiology Division Incorporated (Abbott Laboratories Incorporated)
• Original Assignee: St. Jude Medical Cardiology Division Incorporated (Abbott Laboratories Incorporated)
• Inventors: Relan, Jatin Surendra
• Granted Patent: US 11,103,177 B2
• Time in Patent Office: Days
• CPC Class Codes: A61B 5/0245 by using sensing means generating electric signals, i.e. ECG signals
• CPC Class Codes: A61B 5/287 Holders for multiple electrodes, e.g. electrode catheters for electrophysiological study [EPS]
• CPC Class Codes: A61B 5/339 Displays specially adapted therefor
• CPC Class Codes: A61B 5/366 Detecting abnormal QRS complex, e.g. widening
• CPC Class Codes: A61B 5/7253 characterised by using transforms
• CPC Class Codes: A61B 5/726 using Wavelet transforms
• 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

Abstract

QRS activity duration may be indicative of cardiac tissue health. Accordingly, maps of QRS activity duration may be beneficial to practitioners. To this end, an electroanatomical mapping system can receive an electrogram signal and analyze it by transforming it into the wavelet domain, computing an energy function of the resultant scalogram, and computing QRS activity duration using the energy function. A graphical representation of the QRS activity duration can be output, for example on a three-dimensional cardiac model. Areas of diseased substrate can be identified on the output; in some aspects of the disclosure, diseased substrate corresponds to areas where the QRS activity duration exceeds a preset threshold, such as about 70 ms.

Claims

1. A method of mapping cardiac activity, comprising:

receiving an electrogram signal S(t) at a signal processor; and

using the signal processor;

transforming the electrogram signal S(t) into the wavelet domain, thereby computing a scalogram G(f, t);

computing an energy function L(t) of the scalogram G(f, t); and

computing a QRS activity duration for the electrogram signal S(t) using the energy function L(t).

2. The method according to claim 1, wherein transforming the electrogram signal S(t) into the wavelet domain comprises applying a continuous wavelet transformation to the electrogram signal S(t) to compute the scalogram G(f, t).

3. The method according to claim 2, wherein the continuous wavelet transformation utilizes a high time-resolution mother wavelet when a peak-to-peak voltage of the electrogram signal S(t) does not exceed a preset threshold and wherein the continuous wavelet transformation utilizes a high frequency-resolution mother wavelet when the peak-to-peak voltage exceeds the preset threshold.

4. The method according to claim 3, wherein the high time-resolution mother wavelet comprises a Paul wavelet and wherein the high frequency-resolution mother wavelet comprises a Morlet wavelet.

5. The method according to claim 1, wherein computing an energy function L(t) of the scalogram G(f, t) comprises:

detecting a time T^max at which G(f, t) reaches a maximum;

detecting a time T^down prior to T^max at which G(f, t) first drops below a preset noise threshold;

detecting a time T^up after T^max at which G(f, t) first drops below the preset noise threshold; and

computing the energy function L(t) according to an equation

6. The method according to claim 1, wherein computing a QRS activity duration for the electrogram signal S(t) using the energy function L(t) comprises:

computing a pulse wave L^Pulse(t) having a pulse duration according to an equation

7. The method according to claim 1, further comprising generating a graphical representation of a plurality of QRS activity durations for a plurality of electrogram signals S(t) on a three-dimensional cardiac model.

8. The method according to claim 7, further comprising identifying one or more areas of diseased substrate on the three-dimensional cardiac model, wherein the one or more areas of diseased substrate are characterized by QRS activity durations in excess of a preset threshold.

9. A method of mapping cardiac substrate, comprising:

receiving an electrophysiology data point having an associated electrogram signal at an electroanatomical mapping system; and

using the electroanatomical mapping system;

transforming the electrogram signal into the wavelet domain; and

computing a QRS activity duration for the electrogram signal in the wavelet domain.

10. The method according to claim 9, further comprising repeating the receiving, transforming, and computing steps for a plurality of electrophysiology data points, thereby creating a QRS activity duration map.

11. The method according to claim 10, further comprising outputting a graphical representation of the QRS activity duration map on a three-dimensional cardiac model.

12. The method according to claim 9, wherein transforming the electrogram signal into the wavelet domain comprises applying a continuous wavelet transform to the electrogram signal.

13. The method according to claim 12, wherein the continuous wavelet transform utilizes a high time-resolution mother wavelet when a peak-to-peak voltage of the electrogram signal does not exceed a preset threshold and wherein the continuous wavelet transformation utilizes a high frequency-resolution mother wavelet when the peak-to-peak voltage exceeds the preset threshold.

14. The method according to claim 9, further comprising classifying the electrophysiology data point as a diseased substrate point if the computed QRS activity duration exceeds a preset threshold.

15. An electroanatomical mapping system, comprising:

a wavelet transformation processor configured;

to receive an electrophysiology data point having an associated electrogram signal;

to transform the electrogram signal into the wavelet domain; and

to compute a QRS activity duration for the electrogram signal in the wavelet domain; and

a mapping processor configured to generate a QRS activity map from a plurality of QRS activity durations computed by the wavelet transformation processor.

16. The system according to claim 15, wherein the mapping processor is further configured to output a graphical representation of the QRS activity map on a three-dimensional cardiac model.