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.