System and method to determine driving sources of heart rhythm disorders
A method and system for determining a source of a cardiac rhythm disorder includes collecting cardiac signals at a plurality of locations during a cardiac arrhythmia and identifying activation times within the cardiac signals. After computing the time-dependent phase of each region of tissue, a level of phase synchrony is determined between each pair of locations to assign a synchronization number for each pair of locations. Using the synchronization number, a spatial synchrony map is generated to identify one or more asynchronous tissue regions surrounded by regions of synchrony in the patient's heart.
1. A method for determining a source of a cardiac rhythm disorder in a patient suspected of having the cardiac rhythm disorder, comprising:
collecting, via a computer processor, a plurality of cardiac signals at a plurality of locations during a cardiac arrhythmia;
identifying activation times within the cardiac signals;
computing time-dependent phase of each region of tissue;
computing a level of phase synchrony between a plurality of pairs of locations within the plurality of locations to assign a synchronization number within a range of numbers corresponding to complete asynchrony and complete synchrony for each pair of locations; and
generating a spatial synchrony map using the synchronization numbers to identify one or more asynchronous tissue regions surrounded by regions of synchrony in the patient's heart.
2. The method of claim 1 , wherein the synchronization number is computed according to the relationship γ ij 2 = cos ψ ij 2 + sin ψ ij 2 , where ψ ij is the cyclic relative phase, ψ ij =(φ i −φ j ) mod 2π.
3. The method of claim 1 , wherein the step of generating comprises computing and comparing local and global distributions of synchronization number.
4. The method of claim 3 , wherein comparison of local and global distributions of synchronization number further comprises quantifying a difference in the distributions.
5. The method of claim 4 , wherein quantifying differences in the distributions comprises using a method selected from the group consisting of Hellinger distance, the Kullback—Leibler divergence, the Bhattacharyya distance, the Kolmogorov-Smirnov test, and the Chi-Square test.
6. The method of claim 4 , further comprising assigning an Asynchronous Index (ASI) to the difference and associating the ASI with a specific location of the plurality of locations.
7. The method of claim 6 , further comprising displaying a map of ASI comprising visually-encoded regions corresponding to the locations.
8. The method of claim 7 , wherein the visually-encoded regions are indicated by a visually-distinguishable scale selected from color, grayscale, and alphanumeric character labels.
9. The method of claim 1 , further comprising, prior to collecting, inducing the cardiac arrhythmia.
10. The method of claim 1 , wherein the range of numbers corresponding to complete asynchrony and complete synchrony is from “0” to “1”.
11. A system for determining a source of a cardiac rhythm disorder in a patient suspected of having the cardiac rhythm disorder, the system comprising:
a computer processor programmed to execute the steps of:
collecting a plurality of cardiac signals at a plurality of locations during a cardiac arrhythmia;
identifying activation times within the cardiac signals;
computing time-dependent phase of each region of tissue;
computing a level of phase synchrony between a plurality of pairs of locations within the plurality of locations to assign a synchronization number within a range of numbers corresponding to complete asynchrony and complete synchrony for each pair of locations; and
generating a spatial synchrony map using the synchronization numbers to identify one or more asynchronous tissue regions surrounded by regions of synchrony in the patient's heart.
12. The system of claim 11 , wherein the synchronization number is computed according to the relationship γ 2 ij = cosψ ij 2 + sinψ ij 2 , is the cyclic relative phase, ψ ij =(φ i −φ j mod 2π
13. The system of claim 11 , wherein the computer processor is further programmed to execute the step of computing and comparing local and global distributions of synchronization number.
14. The system of claim 13 , wherein the computer processor compares local and global distributions of synchronization number by quantifying a difference in the distributions.
15. The system of claim 14 , wherein the computer processor quantifies differences in the distributions using a method selected from the group consisting of Hellinger distance, the Kullback—Leibler divergence, the Bhattacharyya distance, the Kolmogorov-Smirnov test, and the Chi-Square test.
16. The system of claim 14 , wherein the computer processor further assigns an Asynchronous Index (ASI) to the difference and associates the ASI with a specific location of the plurality of locations.
17. The system of claim 16 , further comprising a visual display device, wherein the computer processor causes the visual display device to display a map of ASI comprising visually-encoded regions corresponding to the locations.
18. The system of claim 17 , wherein the visually-encoded regions are indicated by a visually-distinguishable scale selected from color, grayscale, and alphanumeric character labels.
19. The system of claim 11 , further comprising a device for inducing the cardiac arrhythmia.
20. The system of claim 11 , further comprising a sensor array defining a grid corresponding to locations within the patient's heart.
21. The system of claim 11 , wherein the range of numbers corresponding to complete asynchrony and complete synchrony is from “0” to “1”.