Fig. 2
From: A case of infra-nodal Wenckebach conduction block with alternating bundle branch block
a. Atrial programmed stimulation S1S2 500/300 ms showed HV interval prolongation (H2V2 80 ms) with conducted narrow QRS complex. b. Left panel: AES S1S2 500/240 ms showed pronounced HV interval prolongation (H2V2 130 ms) with LBBB pattern. Right panel: Diagrammatic representation of 2 possible mechanisms in pronounced HV interval prolongation with LBB aberrancy in response to atrial premature impulses. c. Decrement of 10 ms of S1S2 500/230 ms resulted in sudden increasing AH interval (A2H2 137 ms) with shortening HV interval (H2V2 58 ms). d. Atrial programmed stimulation S1S2S3 600/300/290 ms demonstrated a conduction with infra-nodal block. The duration intervals are in milliseconds. AES indicates atrial extra-stimulus