Left posteroseptal Mahaim fiber associated with marked longitudinal dissociation.
We report a patient who underwent radiofrequency catheter ablation of a left posteroseptal atrioventricular (AV) Mahaim fiber with a marked longitudinal dissociation. During atrial pacing, Wenckebach-type atrioventricular block over the accessory pathway was observed with progressive preexcitation and no change in polarity of the delta waves. The AV conduction curve was discontinuous, with a distinct "jump-up" in local AV conduction time of 84 ms. The earliest ventricular activation was recorded from the posteroseptal portion of the mitral annulus, and the unipolar electrogram from a distal electrode had a high, steep deflection with uniphasic QS-like activity with 62 ms of local AV conduction time.
Tada
H
H
Division of Cardiology, Gunma Prefectural Cardiovascular Center, Maebashi, Japan.
Nogami
A
A
Naito
S
S
Oshima
S
S
Taniguchi
K
K
Kutsumi
Y
Y
D000328:Adult; D002036:Bundle of His / Q000503:physiopathology / Q000601:surgery; D002304:Cardiac Pacing, Artificial; D017115:Catheter Ablation; D004562:Electrocardiography; D006325:Heart Atria / Q000503:physiopathology; D006352:Heart Ventricles / Q000503:physiopathology; D006801:Humans; D008297:Male; D011227:Pre-Excitation, Mahaim-Type / Q000175:diagnosis* / Q000503:physiopathology / Q000601:surgery