216-32: Importance of Proximal His to Right Bundle Activation Sequence for Diagnosis of Complex Tachycardia Circuits
Year: 2016
Type: conference-abstract
Abstract: Introduction: Recording the right-sided proximal His to right bundle (H-RB) activation sequence during tachycardia and in response to V1-V2 pacing can be useful in the diagnosis of certain tachycardias. Assessing the activation sequence from proximal His bundle (large His atrial EGM) to distal RB (absence of atrial EGM) helps to differentiate forms of bundle branch reentry (BBRT) or fascicular tachycardia (FT) from SVT with aberration or concealed nodofascicular tachycardia (NFT). Methods: A closely-coupled multi-electrode catheter (8–10 poles) was used to record the proximal His to distal His and RB potential during sinus rhythm and in tachycardia in 46 patients. The retrograde activation sequence between proximal His-RB was also assessed in response to V1-V2 pacing in these patients and in 12 normal patients without conduction system disease to define normal physiologic response. Results: Three patterns of proximal-His to RB patterns arose upon V1-V2 pacing: Group (1): Simultaneous Prox-His-RB activation (n = 17). Retrograde block in the RBB with V2 results in breakthrough from the LBB to the mid-His region producing simultaneous activation of the proximal and more distal His or RB EGMs. This pattern arose in 3 scenarios: fascicular VT, typical BBRT (LBBB pattern), and in normal patients upon V1-V2 pacing with retrograde RBB block. Group (2): Retrograde RB-His activation (n = 13). Retrograde activation from the distal RB to the proximal His occurs in normal individuals. This pattern was also seen in a case of manifest nodofascicular tachycardia, where the retrograde limb of tachycardia is the RB-prox His bundle as well as in a case of atypical BBRT (RBBB pattern). Group (3): Anterograde Prox-His-RB activation (n = 16). Most SVTs with or without aberration demonstrate this pattern, and in the case of concealed nodofascicular tracts (3 pts), with V2, there is retrograde activation up the NF tract and anterograde conduction from prox-His to distal RB. Junctional tachycardia with origin in superior His region also demonstrates an anterograde prox-His-RB pattern in tachycardia (1 pt). Conclusion: We identified 3 patterns of activation within the region of the proximal His to RB during response to V1-V2 pacing which proved useful in diagnosing complex tachycardias. Simultaneous Prox-His and RB activation is seen with retrograde RBB block and entry into His bundle from LBB (in BBRT or FT). Retrograde RB to His activation occurs in normal individuals as well as in atypical BBRT (RBBB pattern). Anterograde prox-His-RB is seen in most SVTs and in concealed NF tracts.
Source: EP Europace
Authors: Mohan Viswanathan, Nitish Badhwar, David Singh, Raphael Sung, Sarfraz Durrani, Melvin M. Scheinman
Institution: Stanford University
Language: English
Subfield: Cardiology and Cardiovascular Medicine
Field: Medicine
Domain: Health Sciences
Open Access status: bronze
OpenAlex ID: W2597765045