This is a 2D-native electro-anatomic map: instead of a camera view of a 3D chamber, the right and left ventricular free walls are unrolled into a flat sheet — horizontal axis = circumferential position from the septum (0°) around to the opposite free wall (180°), vertical axis = apex-to-base. The RV occupies a narrow wedge near the septal edge (0°–40°); the rest is LV free wall.
Arrival time at every grid node is found with a multi-source Dijkstra shortest-path solve over an 8-connected grid — a discrete numerical eikonal solver, not a closed-form straight-line formula:
t(p) = min over active sources s of the
cheapest grid path from s to p, where each
step costs distance(cm) / local_CV(cm/ms)
Because the wave travels node-to-node through whatever conduction speed occupies each cell, it naturally slows and reroutes around a slow scar patch instead of just being globally derated along a straight line — a real refraction effect a beeline distance/CV formula cannot show.
- Intrinsic LBBB — a single His-bundle source at the septal base; RV-wedge cells conduct at fast His-Purkinje speed (right bundle intact), all other cells at slow myocardial speed (left bundle blocked) — so the wave reaches the RV quickly then must cross cell-to-cell to reach the far lateral wall last.
- RV-only pacing — a single source at the RV apex point, every cell at myocardial speed (no fast conduction system engaged) — the far lateral wall is reached even more slowly, drawn out over the whole grid.
- BiV pacing (CRT) — two sources fire together: RV apex plus an LV lead swept along the free wall. Two wavefronts start near their own free walls and fuse in the middle, sharply cutting the longest single path.
- VV offset — the programmed delay between the two BiV sources; a small negative offset (LV slightly first) often compensates for the LV lead's longer path and shortens total activation time further.
- Scar — a slow patch on the lateral wall; placing the LV lead directly over it forces the wavefront through reduced conduction velocity right at its source, which can undo the benefit of BiV pacing.
The colored sweep replays once per simulated heartbeat: blue = earliest activation, red = latest — exactly the color convention a real electro-anatomic mapping system (CARTO, EnSite) uses.