Figure 1. LACV measurement
LACV was calculated by dividing left atrial conduction distance by
conduction time. Conduction time was defined as the difference in
activation time between the start (septum) and end of the propagation
wave front (lateral wall) in the left atrium. Conduction distance was
measured manually by tracing the pathway of the propagation wave front
from the start point to the end point in the left atrium. The pathways
of the propagation wave front were classified into anterior and
posterior routes. The anterior route originates at the septum, crosses
the anterior wall toward the appendage, passes over the left atrial
appendage orifice, and finally reaches the lateral mitral annulus, where
superior- and inferior-direction propagation waves collide and
disappear. The posterior route goes toward the superior left atrium
(roof) from the septal propagation origin, then downward on the
posterior wall, turns below the left inferior pulmonary vein, and
reaches the lateral mitral annulus. LACV, left atrial conduction
velocity; LAT, local activation time.