Abstract
A 52-year-old man presented with delta waves on a body surface electrocardiogram,
which suggested the presence of a right-sided accessory pathway (AP). Patients with
right-sided APs generally have an rS pattern in leads V1–2, while he had an rS in
lead V1 but an Rs in lead V2, which could not rule out the possibility of the presence
of a septal AP or fasciculoventricular pathway (FVP). On the other hand, patients
with septal APs or FVPs generally have a QS pattern in lead V1 instead of an rS pattern.
An electrophysiological study demonstrated that the simultaneous presence of a right-sided
posterolateral AP and FVP with incomplete right bundle branch block (ICRBBB) generated
those unusual QRS complexes. The FVP arose distal to the site with ICRBBB, and the
ICRBBB delayed the initiation of the FVP conduction. The delayed QS and Rs waves in
leads V1–2 generated by the FVP conduction with ICRBBB appeared to produce rS and
Rs patterns in leads V1–2, respectively. A radiofrequency application along the posterolateral
tricuspid annulus eliminated the right-sided AP conduction. If the localization of
APs based on the QRS morphology is difficult, multiple APs or an FVP with a conduction
system disturbance should be noted.
Learning objective
Patients with right-sided posterolateral accessory pathways (APs) generally have an
rS pattern in lead V2, while patients with fasciculoventricular pathways (FVPs) generally
have a QS pattern in lead V1. The present case with a suspected right-sided posterolateral
AP had unusual QRS complexes, an rS in lead V1, Rs in lead V2, and monophasic R in
leads V3–6, which were associated with the simultaneous presence of a right-sided
posterolateral AP, FVP, and incomplete right bundle branch block.
Keywords
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Article info
Publication history
Published online: November 15, 2022
Accepted:
October 26,
2022
Received in revised form:
October 1,
2022
Received:
August 18,
2022
Identification
Copyright
© 2022 Japanese College of Cardiology. Published by Elsevier Ltd. All rights reserved. All rights reserved.
