Right-Atrial Muscular Ridge as an Isthmus for Macro-Reentrant Atrial Tachycardia in Partial Atrial Standstill.

Authors

Ken Yamazaki, Takahiko Kinjo, Masaomi Kimura, Yuji Ishida, Hirofumi Tomita

Published in

JACC. Case reports. Pages 109429. Jul 23, 2026. Epub Jul 23, 2026.

Abstract

Partial atrial standstill is a rare disorder with extensive atrial electrical silence that can coexist with atrial tachycardia (AT). However, the mechanism of AT in this population remains unclear.
A 54-year-old man was referred for AT and complete atrioventricular block. High-resolution electroanatomic mapping revealed extensive electrically silent areas involving the sinus venarum and right atrial septum, consistent with partial atrial standstill. In contrast, a preserved right atrial muscular ridge (arcuate ridge and crista terminalis) formed the critical isthmus of a macro-reentrant circuit. Ablation of this ridge, followed by cavotricuspid isthmus ablation, terminated the AT. A permanent pacemaker was subsequently implanted. The patient remained free of atrial tachyarrhythmia for 7 years.
Preserved muscular ridges can be key conduction pathways and ablation targets in an extensively scarred atrium.
Muscular ridges can serve as a conduction pathway of macro-reentrant AT in an extensively scarred atrium.

PMID:
42496628
Bibliographic data and abstract were imported from PubMed on 24 Jul 2026.

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