Systems for mapping local conduction velocity
The local conduction velocity of a cardiac activation wavefront can be computed by collecting a plurality of electrophysiology (“EP”) data points using a multi-electrode catheter, with each EP data point including both position data and local activation time (“LAT”) data. For any EP data point, a neighborhood of EP data points, including the selected EP data point and at least two additional EP data points, can be defined. Planes of position and LATs can then be defined using the positions and LATs, respectively, of the EP data points within the neighborhood. A conduction velocity can be computed from an intersection of the planes of positions and LATs. The resultant plurality of conduction velocities can be output as a graphical representation (e.g., an electrophysiology map), for example by displaying vector icons arranged in a uniform grid over a three-dimensional cardiac model.
1. A system for computing local conduction velocity of a cardiac activation wavefront, comprising:
a conduction velocity processor configured to receive as input a plurality of electrophysiology (“EP”) data points, each comprising position data and local activation time (“LAT”) data, collected using a multi-electrode catheter, and, for a selected EP data point:
define a neighborhood of EP data points including the selected EP data point and at least two additional EP data points from the plurality of EP data points; and
compute a conduction velocity for the selected EP data point using the position data of the neighborhood of EP data points and the LAT data of the neighborhood of EP data points; and
a mapping processor configured to generate a three-dimensional graphical representation of a plurality of conduction velocities computed by the conduction velocity processor, wherein the three-dimensional graphical representation includes a plurality of conduction velocity vector icons arranged in a uniform grid over a three-dimensional model of at least a portion of a heart.
2. The system according to claim 1 , wherein the conduction velocity processor is configured to compute the conduction velocity for the selected EP data point using the position data of the neighborhood of EP data points and the LAT data of the neighborhood of EP data points by:
defining a plane of positions for the neighborhood of EP data points using the position data of the neighborhood of EP data points;
defining a plane of LATs for the neighborhood of EP data points using the LAT data of the neighborhood of EP data points; and
computing the conduction velocity for the selected EP data point according to an intersection between the plane of positions and the plane of LATs.
3. The system according to claim 1 , wherein the LAT data are computed relative to activation at a reference electrode carried by the multi-electrode catheter.
4. The system according to claim 1 , further comprising a consistency index processor configured to compute a conduction velocity consistency index for the selected EP data point, wherein the conduction velocity consistency index indicates a degree of consistency in a direction of a plurality of conduction velocity constituents for the selected EP data point.
5. The system according to claim 4 , wherein the conduction velocity processor is configured to compute the plurality of conduction velocity constituents for the selected EP data point by computing a respective conduction velocity constituent for each of a plurality of activation windows of a time segment.
6. The system according to claim 4 , wherein the conduction velocity consistency index comprises a ratio of an absolute magnitude of the conduction velocity and an average absolute magnitude of the conduction velocity constituents.
7. The system according to claim 4 , wherein the conduction velocity consistency index comprises a ratio of an absolute magnitude of the conduction velocity and an absolute magnitude of an average of the conduction velocity constituents.
8. The system according to claim 4 , wherein the conduction velocity consistency index comprises an average normalized dot product of the conduction velocity constituents and the conduction velocity.