Key result
The site of earliest His activation was located 9.8 ± 2.5 mm proximal to the site of the largest His bundle electrogram, with a mean A/V ratio of 1.01 ± 0.42 vs 0.08 ± 0.06.
Why the study?
Does the site of earliest His activation during retrograde conduction differ from the site of the largest His bundle electrogram during sinus rhythm in patients undergoing electrophysiological study?
Observational (n=15)
Does the site of earliest His activation during retrograde conduction differ from the site of the largest His bundle electrogram during sinus rhythm in patients undergoing electrophysiological study?
The earliest His activation site is located approximately 10 mm proximal to the largest His bundle electrogram site, suggesting that most His potentials actually reflect proximal right bundle activation, which is critical for guiding para-Hisian radiofrequency ablation.
May guide para-Hisian ablation mapping; hypothesis-generating in Level 5 case data and requires prospective validation.
AIMS: The His bundle electrogram is believed to reflect the exact location of the His bundle. However, the distinction between distal His bundle potential and proximal right bundle branch potential is challenging. The aim of this study was to pinpoint the location of the branching point of the His bundle, and to compare that site with the site of recording of the largest His bundle electrogram (LH) during sinus rhythm. METHODS: We hypothesized that the site of earliest His activation (EH) during retrograde conduction via the left bundle branch is the branching point. We studied 15 nonconsecutive patients (mean age = 40 +/- 22 years; eight men). We performed a programmed stimulation from right ventricular apex until retrograde right bundle branch block appeared. At that point we measured (1) the distance between antegrade LH site and retrograde EH site and (2) the atrial-to-ventricular amplitude ratio (A/V ratio) at both sites. RESULTS: EH was recorded at the proximal electrode of the His bundle catheter in all patients. Mean distance between EH and LH was 9.8 +/- 2.5 mm. The mean A/V ratios at the EH site and the LH site were 1.01 +/- 0.42 and 0.08 +/- 0.06, respectively. DISCUSSION: This study showed that the EH site is located approximately 10-mm proximal to the LH site. The mean A/V ratio at the EH site during sinus rhythm is approximately 1.0. These observations suggest that the majority of His potentials reflect proximal right bundle activation. Before delivering radiofrequency energy in the para-Hisian area, attention should be paid to the presence of a His potential and to the A/V ratio, rather to the amplitude of the His electrogram.
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Adachi et al. (2009) reported an observational. Measurement of earliest His activation (EH) site vs. Largest His bundle electrogram (LH) site was evaluated on Distance between antegrade LH site and retrograde EH site, and A/V ratio at both sites. The site of earliest His activation was located 9.8 ± 2.5 mm proximal to the site of the largest His bundle electrogram, with a mean A/V ratio of 1.01 ± 0.42 vs 0.08 ± 0.06.
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