Fig. 4

The proportion of passively-activated segments at each pulmonary vein (PV) segment. The left side represents the right PV, and the right side represents the left PV. We divided the PV from posterosuperior to anterosuperior into segments 1–8 (R1-8, L1-8), with the carina as zone 9, further divided into superior and inferior. The presented values indicate the ratio of passively-activated segments in each segment (number of passively-activated segments/60). The areas with a higher ratio of passively-activated segments are depicted in red, while lower ratios are shown in purple