DISCUSSION
Centrifugal activation with widespread breakthrough suggested that the
activation originated from epicardial structures.2,3Considering the location of the breakthrough site, it was likely that
the PACs originated from the Bachmann bundle or its
branches.3 Extensive ablation was deemed necessary to
eliminate these PACs if we targeted the widespread breakthrough.
Therefore, despite the local potentials in the right PV being later than
those in the anterior wall, we performed wide antral circumferential
ablation (WACA) for the right PV to disconnect the PAC origin from the
anterior wall (Fig. 3A). Following the completion of right PV isolation,
PACs were eliminated, and frequent ectopic beats were observed in the
right PV (Fig. 3B). These ectopic beats originated from the antrum of
the right superior PV. Additional ablation targeting these ectopic beats
was performed; however, they were not completely eliminated. To prevent
PV stenosis, further ablation was avoided. The patient was discharged
two days post-procedure without any complications, and no recurrence of
PACs has been observed over a 28-month follow-up period.
In our retrospective analysis of the baseline left atrial map, we
identified a small, blunt prepotential localized to the area associated
with the proximal Bachmann bundle (Fig. 3A). We considered this
prepotential to represent the far-field sensing of the PAC origin within
the proximal Bachmann bundle. In this case, PACs were eliminated during
right PV isolation. This phenomenon can likely be attributed to the
disruption of the electrical connection between the PAC origin and the
distal Bachmann bundle. Additionally, we observed ectopic beats
originating from the antrum of the right superior PV after WACA. The
disruption of the preferential conduction pathway toward the distal
segment of the Bachmann bundle may have unveiled electrical connections
between the proximal segment of the Bachmann bundle and the antrum of
the right superior PV.
It remains uncertain whether our strategy of isolating the PAC origin in
the Bachmann bundle through WACA is applicable to all similar cases, as
ablating epicardial structures such as the Bachmann bundle via
endocardial ablation poses challenges. However, this case provides
critical insights into ablation strategies for PACs originating from
epicardial structures like the Bachmann bundle.