Abstract 18245: Infra-Hisian Complete Heart Block is Often due to Localized Disease in Main His Bundle: Proof of Concept by Electrophysiological Observations during Transient HV Block at the time of Permanent His Bundle Pacing
Introduction: BBB has been shown to be due to longitudinal dissociation in His bundle (HB) in most pts. Pacing at the distal HB can normalize QRS in pts with BBB. In patients with complete heart block (CHB) at infra-His level (HV block), permanent HB pacing (HBP) at sites with HB electrograms, can normalize QRS suggesting the conduction disease is localized in the main HB. It is unclear if this phenomenon is due to recruitment, or capture of distal HB beyond the site of block. We report the electrophysiological observations during transient HV block at the time of permanent HBP.
Results: An 81-yr-old female with left atrial flutter presented for AV node ablation and permanent HBP. Ablation catheter placed at HB region showed 2:1 AV conduction and HV interval of 50 ms (fig A). Medtronic 3830 pacing lead was placed on the HB region where HB egm could be recorded. Once the 3830 lead was fixed, patient developed CHB. Egm from the HBP lead showed HV block with ventricular rhythm at 1300 ms; there was 2:1 AV conduction with HH interval of 520 ms (B). Pacing from HBP lead resulted in normal QRS despite dissociation of His egms (C). HB capture threshold was 1V @ 0.5 ms. Post AV node ablation, HH CL increased from 520 to 1300 ms confirming AV nodal block. Atrial, His (junctional) and ventricular rhythm were all dissociated (D). EGM from HBP lead (fig 2). Narrow complex escape rhythm was noted the next day suggesting recovery of HB conduction.
Conclusion: HB Pacing lead induced HV block could be corrected by pacing at the same location even at low output. If the lesion at the HB is localized, pacing at the site of block can capture the distal his bundle and normalize QRS, confirming earlier observations.
Author Disclosures: P. Vijayaraman: Honoraria; Modest; Medtronic, Boston Scientific. G. Dandamudi: Speakers Bureau; Significant; Bohringer-Ingelheim. Honoraria; Modest; Medtronic. J. Miller: Honoraria; Modest; Medtronic.
- © 2014 by American Heart Association, Inc.