Figure 3: A schematic illustration of the findings seen in figures 1 and 2. 3A: Retrograde atrial activation with Pattern A via the accessory pathway and subsequently lateral to septal via the mitral isthmus and then the AV node. 3B. Pattern B occurs due to functional block across the mitral isthmus, and subsequent activation of the LA in a counterclockwise fashion via the roof, atrial septum and into the node. The “concentric” pattern is seen following activation of the CS from this same impulse.
Reference:
1. Dinatale, A., Notarangelo, M. F., Crocamo, A., Gonzi, G., Fioravanti, M., Niccoli, G., & Ardissino, D. (2022). 81 PITFALLS IN LATERAL ACCESSORY PATHWAY ABLATION: THE IMPORTANCE TO RECOGNIZE MITRAL ISTHMUS CONDUCTION BLOCK DURING REDO PROCEDURES. European Heart Journal Supplements , 24 (Supplement_K), suac121.041. https://doi.org/10.1093/eurheartjsupp/suac121.041