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. 2025 Apr 30;41(3):e70081.
doi: 10.1002/joa3.70081. eCollection 2025 Jun.

Lower loop re-entrant flutter

Anish Bhargav  1 , Ramanathan Velayutham  1 , Raja J Selvaraj  1
Affiliations

Lower loop re-entrant flutter

Anish Bhargav et al. J Arrhythm. .

Abstract

An elderly man with a history of a prior inferior wall myocardial infarction underwent ablation for an atypical right atrial flutter. Electroanatomic mapping revealed diffuse scarring on the anterior, anterolateral, and posterior right atrium, presumably due to atrial infarction from the prior inferior wall myocardial infarction, forcing the activation wavefront through an area of slow conduction across the lower end of the crista terminalis, leading to lower loop reentry in a counterclockwise fashion around the inferior vena cava and a 12-lead ECG showing positive flutter waves in the inferior leads reflecting septal activation in a cranio-caudal direction.

Keywords: Lower loop reentry; counterclockwise flutter; crista terminalis.

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Conflict of interest statement

Authors declare no conflict of interests for this article.

Figures

FIGURE 1
FIGURE 1
Lower loop reentry. Three‐dimensional electroanatomical activation map of the right atrium in inferior views (Panel A) acquired during right atrial flutter along with 12 lead ECG (Panel B). Panel A highlights the reentry circuit, as delineated by the arrows, with the activation wavefront moving in a counterclockwise fashion and encompassing the whole cycle length. Panel B shows 12 lead ECG with positive flutter waves in inferior leads due to septal activation in a cranio‐caudal direction.
FIGURE 2
FIGURE 2
Activation map of the right atrium. Panel A is an RAO view that shows the low voltage area on the anterior, anterolateral, and posterior wall. Panel B is a left lateral view that highlights the cranio‐caudal activation of the atrial septum.
See this image and copyright information in PMC

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