Mapping of atrial fibrillation

An apparatus, comprising:

• a probe having a plurality of electrodes and adapted for insertion into a heart of a living subject;
• and
• a processor configured to receive electrical signals from the electrodes and to perform the acts of:
• modeling at least a portion of the heart as a mesh with vertices, each vertex representing a respective electrode, each vertex formed by a plurality of connected triangles, each triangle having a triangle velocity vector, each vertex having a plane normal thereto onto which its triangle velocity vector is projected to generate a projected velocity vector, and each vertex having a vertex velocity vector based on an average of all projected velocity vectors of the connected triangles;
• corresponding locations of respective electrodes of the plurality of electrodes to respective vertices of the mesh;
• recording electrograms from the respective electrodes of the plurality of electrodes concurrently at the respective locations of the corresponding locations of respective electrodes in the heart, the electrograms comprising readings of the electrodes, each reading being from the group consisting of trusted reading, each with a fixed Local Activation Time (LAT) obtained from a respective maximum negative slope, and unreliable readings, each with an adjustable LAT that falls within a respective time window with upper and lower limits derived from a time incidence of peak and valley demarcating a slope on which the adjustable LAT is defined;
• generating an activation map from the trusted and unreliable readings of the group;
• transforming the activation map into a map of electrical propagation waves, comprising:
• segmenting the electrograms into a series of frames filled with the fixed and adjustable LATs based on vertex velocity vectors of corresponding vertices of the mesh;
• for the vertices of the mesh corresponding to electrodes with unreliable readings that fall within respective time windows, determining velocity deviation angles based on their vertex velocity vectors, wherein a velocity deviation angle is defined as an angle between a pair of projected vertex velocity vectors;
• adjusting the LATs of the electrodes with unreliable readings that fall within respective time windows by minimizing the velocity deviation angles;
• reporting adjusted LATs;
• and
• ablating tissue of the heart based on adjusted LATs to modify the electrograms.