System and method for focal source identification

Patent metadata

Field	Value
Publication number	US-10111598-B2
Application number	US-201515126634-A
Country	US
Kind code	B2
Filing date	Mar 31, 2015
Priority date	Mar 31, 2014
Publication date	Oct 30, 2018
Grant date	Oct 30, 2018

Abstract

Various embodiments are described herein for a system, method, and device for identifying focal source locations of electrophysiological activity in an organ. The system, method and device may also be used to guide catheter ablation of the organ. An electrogram signal can be obtained from a location in the organ, and it can be determined if the electrogram is periodic and, if so, the corresponding periodicity cycle length. A plurality of peaks associated with the cycle length can be identified. The location can be identified as a focal source location when the periodicity cycle length and the plurality of peaks have focal source characteristics. Methods are also described for identifying a direction of wave propagation and identifying multiple periodicities within an electrogram signal.

First claim

The invention claimed is:

1. A method of identifying one or more focal source locations of electrophysiological activity for a heart using intracardiac electrograms of the heart, the method comprising:
receiving, by a processor, a first electrical signal set obtained from a first location of the heart, the electrical signal set comprising electrophysiological signals acquired at the first location of the heart, wherein the electrical signal set comprises a unipolar electrogram and a bipolar electrogram;
determining, by the processor, that the first electrical signal set is periodic;
identifying, by the processor, a periodicity cycle length of the first electrical signal set when the first electrical signal set is periodic;
automatically identifying, by the processor, a plurality of peaks in the bipolar electrogram of the first electrical signal set that are associated with the identified periodicity cycle length;
for a given peak in the identified plurality of peaks, analyzing a peak morphology by:
automatically identifying, by the processor, a unipolar electrogram portion in the unipolar electrogram corresponding to the given peak; and
analyzing the identified unipolar electrogram portion to identify the peak morphology of the given peak;

identifying, by the processor, the first location in the heart as a first focal source location of the one or more focal source locations when the identified periodicity cycle length and the identified plurality of peaks have focal source characteristics, wherein the focal source characteristics comprise at least a threshold percentage of peak morphologies in the first electrical signal set associated with the identified plurality of peaks having a QS morphology;
determining, by the processor, an anatomic location of the first focal source location within the heart using anatomic mapping data from an electroanatomic mapping system;
generating, by the processor, a 3D image of the heart that includes a tag identifying the anatomic location of the first focal source location within the 3D image using the electroanatomic mapping system; and
displaying the 3D image of the heart including the tag to guide ablation of the first focal source location in the heart that corresponds to the tag shown in the 3D image.

2. The method as defined in claim 1 , wherein the focal source characteristics comprise at least one of:
the identified plurality of peaks being stable;
and
the identified periodicity cycle length being less than a periodicity cycle length threshold.

3. The method as defined in claim 2 , wherein determining that the identified plurality of peaks is stable comprises:
determining that a number of consecutive peaks in the plurality of peaks are spaced apart by a stable distance substantially equal to the periodicity cycle length; and
determining that the number of consecutive peaks is larger than a consecutive peak threshold.

4. The method as defined in claim 1 , wherein identifying the periodicity cycle length comprises:
identifying a plurality of potential cycle lengths;
determining a plurality of correlation values corresponding to the plurality of potential cycle lengths; and
identifying the periodicity cycle length as the potential cycle length having an optimal correlation value.

5. The method as defined in claim 4 , wherein determining a given correlation value for a corresponding potential cycle length comprises:
identifying a first signal portion of the first electrical signal set;
generating a second signal portion from the first electrical signal set by applying a circular shift to the first signal portion, the shift being the potential cycle length; and
determining the correlation value between the first signal portion and the second signal portion.

6. The method as defined in claim 4 , wherein determining a given correlation value for a corresponding potential cycle length comprises determining a cost value of the corresponding potential cycle length.

7. The method as defined in claim 4 , wherein determining that the first electrical signal set is periodic further comprises determining that the optimal correlation value differs from a mean correlation value by more than a threshold correlation value.

8. The method as defined in claim 7 , wherein the threshold correlation value is a predefined amount based on a standard deviation of the plurality of correlation values.

9. The method as defined in claim 1 , wherein identifying the plurality of peaks in the first electrical signal set comprises:
identifying a plurality of potential peaks in the first electrical signal set;
determining a plurality of potential peak distances, each potential peak distance corresponding to a distance in the first electrical signal set between two of the potential peaks;
determining a plurality of potential peak costs, each potential peak cost corresponding to one of the potential peak distances;
identifying a plurality of subsets of potential peaks from the plurality of potential peaks;
determining the peak cost measure for each subset of potential peaks; and
identifying the plurality of peaks based on the subset of potential peaks having a lowest peak cost measure.

10. The method as defined in claim 9 , wherein identifying the plurality of potential peaks in the first electrical signal comprises:
identifying a peak threshold; and
identifying the plurality of potential peaks in the first electrical signal set by finding peaks in the first electrical signal set having an amplitude that is larger than the peak threshold.

11. The method as defined in claim 9 , wherein each of the potential peak costs is determined based on a difference between the corresponding potential peak distance and the identified periodicity cycle length.

12. The method as defined in claim 9 , wherein the peak cost measure is determined based on a sum of the potential peak costs corresponding to the peaks in the subset of potential peaks.

13. The method as defined in claim 9 , wherein identifying the plurality of peaks based on the subset of potential peaks having the lowest peak cost measure comprises:
identifying a pruned subset of peaks by removing each of the peaks in the subset of potential peaks that are not within a peak threshold distance of an adjacent peak; and
identifying the plurality of peaks as the pruned subset of peaks.

14. The method as defined in claim 13 , wherein the peak threshold distance is determined based on the identified periodicity cycle length.

15. The method as defined in claim 1 , wherein the percentage of peak morphologies is such that the expected morphology is found for a majority of the identified unipolar electrogram portions.

16. The method as defined in claim 1 , further comprising:
receiving, by the processor, a plurality of additional electrical signal sets, each of the additional electrical signal sets being obtained from different locations in the heart;
determining, by the processor, that a given additional electrical signal set is periodic;
identifying, by the processor, an additional periodicity cycle length for the given additional electrical signal set;
identifying, by the processor, a plurality of additional peaks in the given additional electrical signal set that are associated with the identified additional periodicity cycle length; and
identifying, by the processor, an additional location in the heart corresponding to the given additional electrical signal as an additional focal source location when the additional identified periodicity cycle length and the identified plurality of additional peaks hav

Assignees

• Univ Health Network

Inventors

• Chauhan Vijay Singh
• Gizurarson Sigfus
• Dalvi Rupin Haily

Classifications

• G16H50/20

  for computer-aided diagnosis, e.g. based on medical expert systems · CPC title

• A61B2505/05

  Surgical care · CPC title

• A61B5/748

  Selection of a region of interest, e.g. using a graphics tablet · CPC title

• A61B5/743

  Displaying an image simultaneously with additional graphical information, e.g. symbols, charts, function plots · CPC title

• A61B18/1492

  having a flexible, catheter-like structure, e.g. for heart ablation (A61B18/1477 takes precedence) · CPC title