HYBRID BIPOLAR/UNIPOLAR DETECTION OF ACTIVATION WAVEFRONT

• US 20150208938A1
• Filed: 01/29/2014
• Published: 07/30/2015
• Est. Priority Date: 01/29/2014
• Status: Active Grant

• Current Assignee: Biosense Webster Israel Ltd. (Johnson & Johnson)
• Original Assignee: Biosense Webster Israel Ltd. (Johnson & Johnson)
• Inventors: Houben, Richard P.M., Bar-Tal, Meir, Botzer, Lior
• Granted Patent: US 9,380,953 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: A61B 5/287 Holders for multiple electrodes, e.g. electrode catheters for electrophysiological study [EPS]
• CPC Class Codes: A61B 5/349 Detecting specific parameters of the electrocardiograph cycle
• CPC Class Codes: A61B 5/361 Detecting fibrillation
• CPC Class Codes: A61B 5/363 Detecting tachycardia or bradycardia
• CPC Class Codes: A61B 5/367 Electrophysiological study [EPS], e.g. electrical activation mapping or electro-anatomical mapping
• CPC Class Codes: A61B 5/72 Signal processing specially adapted for physiological signals or for diagnostic purposes character recognition, recognising digital ink, document-oriented image-based pattern recognition G06V30/00; recognition or understanding of postal images G06V30/424
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives
• CPC Class Codes: A61B 5/7246 using correlation, e.g. template matching or determination of similarity

Abstract

A bipolar electrogram and a unipolar electrogram are recorded from electrodes of a probe, and differentiated with respect to time. Peaks are identified in the differentiated bipolar electrogram. An activity window is defined that includes bipolar activity about the peaks. An extreme negative value in the differentiated unipolar electrogram within the activity window is reported as a unipolar activation onset. In one aspect, an annotation is selected from candidate minima in the differentiated unipolar electrogram within the activity window by excluding candidates that fail to correlate with activity in the bipolar electrogram.

Claims

1. A method, comprising the steps of:

inserting a probe into a heart of a living subject, the probe having electrodes;

recording a bipolar electrogram and a unipolar electrogram from a location in the heart with the electrodes;

defining a time interval comprising a window-of-interest;

differentiating the bipolar electrogram and the unipolar electrogram with respect to time to define a differentiated bipolar electrogram and a differentiated unipolar electrogram, respectively;

identifying peaks within the window-of-interest in the differentiated bipolar electrogram;

establishing a bipolar activity window about respective peaks, the bipolar activity window having activity bounds that include activity about the peaks in the bipolar electrogram; and

identifying an extreme negative value (−

dV/dt) in the differentiated unipolar electrogram within the activity bounds, and reporting a time corresponding to the value as a unipolar activation onset.

2. The method according to claim 1, further comprising the steps of:

filtering the unipolar electrogram to remove baseline wander therefrom.

3. The method according to claim 1, wherein identifying an extreme negative value comprises:

defining a slope window in the unipolar electrogram that contains downward sloping intervals;

fitting respective regression lines to the downward sloping intervals;

determining a trend in the slope window, the trend having a slope;

identifying a longest monotonic downward sloping interval contained in each slope window;

making a determination that the longest monotonic downward sloping interval occupies less than 50% of its containing slope window; and

responsive to the determination subtracting the slope of the trend from a slope of the regression line of the longest monotonic downward sloping interval.

4. The method according to claim 1, further comprising the steps of:

iterating the steps of identifying peaks, establishing a bipolar activity window and identifying an extreme negative value using time-reversed versions of the bipolar electrogram and the differentiated unipolar electrogram as the differentiated bipolar electrogram to yield a new extreme negative value; and

reporting a time corresponding to the new extreme negative value as a unipolar activation termination.

5. The method according to claim 1, wherein establishing a bipolar activity window comprises:

defining baseline segments between complexes of the bipolar electrogram;

identifying the complexes by executing a state machine; and

assigning a transition between the baseline segments and the complexes as a boundary of the bipolar activity window.

6. The method according to claim 1, wherein establishing a bipolar activity window comprises:

classifying segments in the bipolar electrogram as being above or below a predefined value; and

identifying a transition from one of the segments to another of the segments as a boundary of the bipolar activity window.

7. A method, comprising the steps of:

inserting a probe into a heart of a living subject, the probe having electrodes;

recording a bipolar electrogram and a unipolar electrogram from a location in the heart with the electrodes;

differentiating the bipolar electrogram and the unipolar electrogram with respect to time to define a differentiated bipolar electrogram and a differentiated unipolar electrogram;

respectively assigning times corresponding to minima in the differentiated unipolar electrogram as candidate annotation points, wherein the minima are less than a predefined negative threshold value;

defining respective time intervals about the minima;

determining that during at least one of the time intervals the bipolar electrogram or the differentiated bipolar electrogram fails to meet a criterion of correlated activity with the differentiated unipolar electrogram;

defining qualified candidate annotation points by excluding candidate annotation points that lie within the at least one time interval;

establishing an annotation as an activation onset time in the unipolar electrogram from among the qualified candidate annotation points; and

reporting the annotation.

8. The method according to claim 7, further comprising the steps of adjusting the bipolar electrogram and the unipolar electrogram to null baseline portions thereof.

9. The method according to claim 8, wherein adjusting comprises filtering the unipolar electrogram with a median filter.

10. The method according to claim 8, wherein adjusting comprises filtering the bipolar electrogram with a median filter.

11. The method according to claim 7, wherein the criterion of correlated activity comprises a variation of amplitude in the bipolar electrogram.

12. The method according to claim 11, wherein the variation of amplitude is at least 0.008 mV.

13. The method according to claim 7, wherein the criterion of correlated activity comprises a failure of a slope of the bipolar electrogram to exceed −

0.008 mV/ms.

14. The method according to claim 7, wherein the criterion of correlated activity comprises a ratio between a slope of the bipolar electrogram and a slope of the unipolar electrogram that exceeds 0.2.

15. The method according to claim 7, wherein the criterion of correlated activity comprises a ratio between an amplitude of the bipolar electrogram and an amplitude of the unipolar electrogram that exceeds a predetermined value.

16. The method according to claim 7, wherein the time intervals have boundaries located ±

2 ms from the candidate annotation points.

17. The method according to claim 7, wherein a slope of the unipolar electrogram at the candidate annotation points does not exceed −

0.01 mV/ms.

18. The method according to claim 7, wherein establishing an annotation comprises the steps of:

determining that a plurality of the qualified candidate annotation points constitute a single activity according to a predetermined single activity criterion;

merging the plurality of the qualified candidate annotation points into a merged candidate annotation; and

selecting one annotation from the merged candidate annotation and others of the qualified candidate annotation points.

19. The method according to claim 18, wherein the single activity criterion comprises a determination that a peak in the differentiated unipolar electrogram lies between two qualified candidate annotation points and a ratio between (1) a difference between the peak and one of the two qualified candidate annotation points and (2) another of the two qualified candidate annotation points exceeds a predefined ratio.

20. An apparatus, comprising:

electrical circuitry for recording signal data from electrodes of a probe when the probe is at a location in a heart of a living subject, the signal data comprising a bipolar electrogram and a unipolar electrogram;

a memory for storing the signal data; and

a display; and

a processor connected to the memory and operative for performing the steps of;

defining a time interval comprising a window-of-interest;

differentiating the bipolar electrogram and the unipolar electrogram with respect to time to define a differentiated bipolar electrogram and a differentiated unipolar electrogram, respectively;

identifying peaks within the window-of-interest in the differentiated bipolar electrogram;

establishing a bipolar activity window about respective peaks, the bipolar activity window having activity bounds and comprising a time interval of activity about the peaks in the bipolar electrogram; and

identifying an extreme negative value (−

dV/dt) in the differentiated unipolar electrogram within the activity bounds, and reporting a time corresponding to the value as a unipolar activation onset on the display.

21. The apparatus according to claim 20, wherein the electrical circuitry further comprises a filter to remove baseline wander from the unipolar electrogram.

22. The apparatus according to claim 20, further wherein identifying an extreme negative value comprises:

defining a slope window in the unipolar electrogram that contains downward sloping intervals;

fitting respective regression lines to the downward sloping intervals;

determining a trend in the slope window, the trend having a slope;

identifying a longest monotonic downward sloping interval contained in each slope window;

making a determination that the longest monotonic downward sloping interval occupies less than 50% of its containing slope window; and

responsive to the determination subtracting the slope of the trend from a slope of the regression line of the longest monotonic downward sloping interval.

23. The apparatus according to claim 22, further comprising the step of adjusting slopes of the regression line by subtracting the slope of the trend therefrom.

24. An apparatus, comprising:

electrical circuitry for recording signal data from electrodes of a probe when the probe is at a location in a heart of a living subject, the signal data comprising a bipolar electrogram and a unipolar electrogram;

a memory for storing the signal data;

a display; and

a processor connected to the memory and operative for performing the steps of;

differentiating the bipolar electrogram and the unipolar electrogram with respect to time to define a differentiated bipolar electrogram and a differentiated unipolar electrogram;

respectively assigning times corresponding to minima in the differentiated unipolar electrogram as candidate annotation points, wherein the minima are less than a predefined negative threshold value;

defining respective time intervals about the minima;

determining that during at least one of the time intervals the bipolar electrogram or the differentiated bipolar electrogram fails to meet a criterion of correlated activity with the differentiated unipolar electrogram;

defining qualified candidate annotation points by excluding candidate annotation points that lie within the at least one time interval;

establishing an annotation as an activation onset time in the unipolar electrogram from among the qualified candidate annotation points; and

reporting the annotation on the display.

25. The apparatus according to claim 24, wherein the electrical circuitry comprises a median filter.