System and method for reconstructing cardiac activation information

Patent metadata

Field	Value
Publication number	US-9668666-B2
Application number	US-201514944096-A
Country	US
Kind code	B2
Filing date	Nov 17, 2015
Priority date	May 2, 2011
Publication date	Jun 6, 2017
Grant date	Jun 6, 2017

Abstract

In a system and method for reconstructing cardiac activation information, an analysis cardiac signal and a reference cardiac signal are accessed and processed to determine a first point of change in the analysis cardiac signal at which a derivative of the analysis cardiac signal diverges with respect to a derivative of the reference cardiac signal. The signals are processed to determine a second point of change in the analysis cardiac signal at which a different derivative of the analysis cardiac signal with respect to a different derivative of the reference cardiac signal. An activation onset time is assigned in the analysis cardiac signal at a point based on a mathematical association of the first point of change and the second point of change to define cardiac activation indicating a beat in the analysis cardiac signal.

First claim

The invention claimed is:

1. A method of reconstructing cardiac activation information, the method comprising:
accessing, by a computing device, an analysis cardiac signal and a reference cardiac signal obtained from a patient;
processing, by the computing device, the analysis cardiac signal and the reference cardiac signal to determine a first point of change in the analysis cardiac signal at which a derivative of the analysis cardiac signal diverges with respect to a derivative of the reference cardiac signal, the derivative of the analysis cardiac signal and the derivative of the reference cardiac signal being one of zero, first, and second order derivative;
processing, by the computing device, the analysis cardiac signal and the reference cardiac signal to determine a second point of change in the analysis cardiac signal at which a different derivative of the analysis cardiac signal diverges with respect to a different derivative of the reference cardiac signal, the different derivative of the analysis cardiac signal and the different derivative of the reference cardiac signal being a different one of zero, first, and second order derivative; and
assigning an activation onset time in the analysis cardiac signal at a point based on a mathematical association of the first point of change and the second point of change to define cardiac activation indicating a beat in the analysis cardiac signal.

2. The method of claim 1 , wherein the mathematical association is an average of the first point of change and the second point of change representing a majority from reference cardiac signals processed in relation to the analysis cardiac signal.

3. The method of claim 2 , wherein the first point of change and the second point of change are within a predetermined time interval of each other.

4. The method of claim 2 , wherein the predetermined time interval is ±5 ms.

5. The method of claim 1 , wherein the mathematical association is an average of the first point of change and the second point of change representing a plurality from reference cardiac signals processed in relation to the analysis cardiac signal.

6. The method of claim 5 , wherein the first point of change and the second point of change are within a predetermined time interval of each other.

7. The method of claim 6 , wherein the predetermined time interval is ±5 ms.

8. The method of claim 1 , wherein the mathematical association is a selection of one of the first point of change and the second point of change.

9. The method of claim 8 , wherein the selection comprises:
computing a first difference value of the first point of change minus a first threshold that is associated with the first point of change;
computing a second difference value of the second point of change minus a second threshold that is associated with the second point of change; and
selecting one of the first point of change and the second point of change based on a highest difference value among the first difference value and the second difference value.

10. The method of claim 8 , wherein the selection is based on a highest order derivative that is above an associated threshold.

11. The method of claim 1 , wherein the first point of change and the second point of change are determined at about the same time point for the analysis cardiac signal and the reference cardiac signal.

12. The method of claim 1 , wherein the first point of change and the second point of change are determined from one or more of slope, amplitude, timing and shape for the analysis cardiac signal and the reference cardiac signal.

13. The method of claim 1 , wherein determination of the first point of change comprises:
forming a composite cardiac signal from the analysis cardiac signal and the reference cardiac signal;
determining ratio values at a plurality of points in the analysis cardiac signal, each ratio value representing a difference between the derivative of the reference cardiac signal and a derivative of the composite cardiac signal to a difference between the derivative of the analysis cardiac signal and the derivative of the composite cardiac signal, the derivative of the composite cardiac signal being one of zero, first and second order derivative; and
selecting as the first point of change in the analysis cardiac signal a point having a largest ratio value from the determined ratio values.

14. The method of claim 1 , wherein determination of the second point of change comprises:
forming a composite cardiac signal from the analysis cardiac signal and the reference cardiac signal;
determining ratio values at a plurality of points in the analysis cardiac signal, each ratio value representing a difference between the different derivative of the reference cardiac signal and a derivative of the composite cardiac signal to a difference between the different derivative of the analysis cardiac signal and the derivative of the composite cardiac signal, the derivative of the composite cardiac signal being one of zero, first and second order derivative; and
selecting as the second point of change in the analysis cardiac signal a point having a largest ratio value from the determined ratio values.

15. The method of claim 1 , wherein the first point of change and the second point of change at or below a noise level are associated with one or more signals from a heart, respiratory system, gastrointestinal tract, neurological system and electronic interference.

16. The method of claim 1 , further comprising performing processing and assigning to define multiple cardiac activations indicating beats in the analysis cardiac signal.

17. The method of claim 1 , further comprising iteratively selecting the analysis cardiac signal and the reference cardiac signal from a plurality of cardiac signals.

18. The method of claim 1 , further comprising:
iteratively selecting pairs of cardiac signals from a plurality of cardiac signals, each pair having an analysis cardiac signal and different reference cardiac signal;
performing processing and assigning for each of the pairs to define multiple cardiac activations associated indicating beats for the analysis cardiac signal in each of the pairs; and
reconstructing a cardiac activation pattern based on assigned activation onset times of cardiac activations from the plurality of cardiac signals to indicate a source of a cardiac rhythm disorder.

19. A system to reconstruct cardiac activation information comprising:
at least one computing device configured to:
access an analysis cardiac signal and a reference cardiac signal obtained from a patient;
process the analysis cardiac signal and the reference cardiac signal to determine a first point of change in the analysis cardiac signal at which a derivative of the analysis cardiac signal diverges with respect to a derivative of the reference cardiac signal, the derivative of the analysis cardiac signal and the derivative of the reference cardiac signal being one of zero, first, and second order derivative;
process the analysis cardiac signal and the reference cardiac signal to determine a second point of change in the analysis cardiac signal at which a different derivative of the analysis cardiac signal diverges with respect to a different derivative of the reference cardiac signal, the different derivative of the analysis cardiac signal and the different derivative of the reference cardiac signal being a different one of zero, first and second order derivative; and
assign an activation onset time in the analysis cardiac signal at a point based o

Assignees

• Univ California
• Topera Inc
• Us Veterans Affairs

Inventors

• Narayan Sanjiv
• Briggs Carey Robert
• Sehra Ruchir

Classifications

• A61B5/0036

  including treatment, e.g., using an implantable medical device, ablating, ventilating · CPC title

• A61B2562/046

  in a matrix array · CPC title

• A61B5/7282 Primary

  Event detection, e.g. detecting unique waveforms indicative of a medical condition (cough events A61B5/0823; seizures A61B5/4094; sleep apnoea A61B5/4818) · CPC title

• A61B5/7239

  using differentiation including higher order derivatives · CPC title

• A61B5/7278

  Artificial waveform generation or derivation, e.g. synthesizing signals from measured signals · CPC title