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Dynamic Changes of the S Wave in Lead V6: A Novel Visual Indicator for Left Bundle Branch Capture
Shanshan Zhuo1, Longfu Jiang1, Xiaojie Cai1
1Department of Cardiology, Ningbo No. 2 Hospital, Ningbo, Zhejiang, China.
Background:
During the electrode screwing process in left bundle branch pacing (LBBP), the significance of the S wave in lead V6 remains elusive. In this study we analyzed the change of the S wave in lead V6 under different patterns of capture and explore its mechanisms.
Methods:
Our study included 243 patients with selective LBBP (SLBBP). We used the continuous pacing technique and classified the electrophysiologic characteristics observed during the screwing process into 4 patterns: left ventricular septal pacing (LVSP), nonselective LBBP (NSLBBP) in low output and in lower output, and selective LBBP. The change of the S-wave morphology in lead V6 and R-wave peak time in leads V6 and V1 were evaluated according to these 4 patterns.
Results:
In all 243 cases, the presence of S wave in V6 gradually increased in the 4 patterns as follows: 35.4% in LVSP, 77.0% in NSLBBP low output, 82.7% in NSLBBP lower output, and 97.9% in SLBBP. From the LVSP to the NSLBBP (low output) pattern, there were 60 (69.8%) cases of deepening of the S wave and 101 (64.3%) cases showing a newly emerged S wave. From the NSLBBP lower output to the SLBBP pattern, there were 171 (85.1%) cases with a deepening S wave and 37 (88.1%) cases with a newly emerged S wave. Sensitivity and specificity of the S wave in lead V6 were 97.9% and 100% in SLBBP, respectively.
Conclusions:
The dynamically changing S wave in lead V6 serves as a novel visual indicator of left bundle branch capture.
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