Anatomical substrate
The mean distance between the collision site and the breakthrough site
was 24 [19-40] mm. In all 27 ATs, the collision site co-localized
with a low-voltage area, while the breakthrough site co-localized with
an epicardial musculature. The presence of a low-voltage area at the
collision site was: (1) spontaneous in 2 patients (8%) and (2)
iatrogenic in 24 patients (92%). The missing portion of the circuit was
bypassed by: (1) the CS-GCV bundle (Figure 1 ) in 6 ATs (22%);
(2) the VOM bundle (Figure 2 ) in 4 ATs (15%); (3) the Bachmann
bundle (Figure 3 ) in 6 ATs (22%); (4) the septopulmonary
bundle (Figure 4 ) in 4 ATs (15%); (5) the fossa ovalis
(Figure 5 ) in 2 ATs (7%); and (6) a low RA bridge
(Figure 6 ) in 5 ATs (19%). Details for each type of epicardial
bypass are provided in Table 2 .