Discussion
LBBP is a developing method of conduction system pacing that offers
several advantages over conventional methods of pacing. However, it can
be associated with direct vascular injury to the septal perforator
arteries (9, 10). Therefore, knowing the distance between the His bundle
and the first septal perforator artery would help guide operators when
performing LBBP insertion.
One study has evaluated the distance from the His bundle to the first
septal perforator in the setting of alcohol septal ablation for
hypertrophic cardiomyopathy (11). Although the methods are not stated in
the paper, it is likely that the authors measured the distance from the
His bundle to the ostium of the septal perforator. LBBP leads are
implanted more inferiorly, along a line connecting the His bundle to the
RV apex, and thus the distance along this line, which is most relevant
to LBBP, has not been described.
In this study, CCTAs that were performed for standard indications were
retrospectively reviewed and this distance was measured. There was
variation in this distance, but it was greater than 1.5 cm in 90% of
patients and greater than 2.0 cm in 84% of patients. Therefore,
operators should aim to implant a LBBP lead less than 1.5 cm from the
His bundle, and if not possible, less than 2.0 cm would have similar
safety profile.
There are several limitations to this study. As this was based on CT
imaging, it is possible that the first septal perforator artery was not
visible because of the resolution of the imaging or timing of contrast.
Since the entire course of the septal perforator was often not visible,
the measurement was made to a line connecting the artery os to the
His-RV apex line at a 90-degree angle. This may not have followed the
actual course of the artery in all cases.