Methods and systems for wavelength mapping cardiac fibrillation and optimizing ablation lesion placement
View Patent ↗A system that executes a process for mapping cardiac fibrillation and optimizing ablation treatments. The process, in some embodiments, includes: positioning a two dimensional electrode array to several locations in a patient's heart and at each location, obtaining a conduction velocity and a cycle length measurement from at least two local signals in response to electrical activity in the cardiac tissue. In some embodiments, a regional wavelength is calculated by multiplying the local conduction velocity with the local minimum cycle length. The system can then create a wavelength distribution map that identifies the location of the drivers in the heart. In certain embodiments, the system uses variability of conduction velocity and cycle length in an area to determine the driver type. In some embodiments, the system calculates average distance of drivers to non-conductive tissue boundaries. The system then selects ablation placements that maximize treatment efficacy while minimizing tissue damage.
1 . A method for mapping cardiac fibrillation in a patient, comprising:
(a) providing a system for measuring cardiac fibrillation, wherein the system comprises:
a two dimensional electrode array positioned at a first location on a patient's heart, wherein the two dimensional electrode array comprises at least a first electrode pair and a second electrode pair, wherein the first electrode pair is configured to detect a first local signal, and wherein the second electrode pair is configured to detect a second local signal,
an ablation electrode, and
a processing unit coupled to the two dimensional array;
(b) registering, via the system, the location of the first electrode pair and the second electrode pair, wherein the first electrode pair and the second electrode pair are separated by a distance;
(c) obtaining, via the system, a first conduction velocity measurement from the first local signal and the second local signal in response to electrical activity in the cardiac tissue, wherein the conduction velocity measurement is determined from a time difference between the first and the second local signals and the distance between the first electrode pair and the second electrode pair;
(d) obtaining, via the system, a first cycle length measurement from the first local signal in response to the electrical activity in the cardiac tissue, wherein the first cycle length measurement is determined by a time difference between a first excitation and a second excitation detected in the first local signal; and
(e) calculating, via the system, a first regional wavelength by multiplying the first conduction velocity measurement obtained in (c) and the first cycle length measurement obtained in (d); and
(f) ablating the cardiac tissue at a driver location identified using the first regional wavelength.
2 . The method of claim 1 , further comprising:
moving the two dimensional electrode array to a second location of the patient's heart to obtain a second conduction velocity measurement and a second cycle length measurement; and
calculating a second regional wavelength by multiplying the second conduction velocity measurement and the second cycle length measurement.
3 . The method of claim 2 , wherein the second location of the patient's heart does not overlap with the first location of the patient's heart.
4 . The method of claim 2 , further comprising:
creating a wavelength distribution map for the patient's heart based on at least the first and the second regional wavelength.
5 . The method of claim 4 , further comprising:
identifying the driver location based on the wavelength distribution map that was created based on at least the first and the second regional wavelength.
6 . The method of claim 1 , wherein the first local signal is obtained by a difference in electrical activity obtained from the first electrode and the second electrode in the first electrode pair.
7 . The method of claim 1 , wherein obtaining the conduction velocity measure further comprises:
identifying a first wave activation time at the first electrode pair, a second wave activation time at the second electrode pair, and a set of additional wave activation times at one or more electrode pairs neighboring the first electrode pair;
determining a first-to-second time interval based on the time difference between the first wave activation time and the second wave activation time;
determining a set of time intervals based on the time difference between the first wave activation time and the set of additional wave activation times at one or more electrode pairs neighboring the first electrode pair;
wherein the first-to-second time interval is the longest comparing to the set of time intervals; and
wherein the vector of the conduction velocity is in the direction from the first electrode pair to the second electrode pair.
8 . The method of claim 1 , wherein the two dimensional array comprises recording electrodes and the ablation electrode.
9 . The method of claim 8 , wherein the two dimensional array is able to both map cardiac fibrillation and perform the ablating step.