Leaping to Diagnosis: The Frog Sign as a Key Clue in AVNRT

TL;DR

The 'frog sign' in heart rhythms helps diagnose AVNRT, a heart condition successfully treated with ablation.

Contribution

The frog sign is identified as a novel and specific diagnostic indicator for AVNRT.

Findings

The frog sign is characterized by prominent cannon A waves in AVNRT.

AVNRT was confirmed via electrophysiological study and treated with radiofrequency ablation.

Abstract

The “frog sign,” characterized by prominent cannon A waves, is a critical diagnostic clue for AV‐nodal reentrant tachycardia (AVNRT). It was confirmed through electrophysiological study and was successfully treated with radiofrequency ablation.

Full text

Case Presentation

1

An elderly female presented with episodes of vertigo and palpitations. A “frog sign” was observed, characterized by prominent cannon A waves in the jugular and subclavian veins due to atrial contraction against a closed tricuspid valve (Video S1). Regularly beating cannon A waves are typically seen in AVNRT, less commonly in other supraventricular arrhythmias, tricuspid regurgitation, ventricular tachycardia, heart block, and pacemaker syndrome [1, 2]. The ECG revealed a regular, narrow‐complex tachycardia without visible P‐waves, raising suspicion for AVNRT. The diagnosis was confirmed by an electrophysiological study, and radiofrequency ablation was performed (Video S1). During follow‐up, no further symptoms were reported.

Author Contributions

Andreas Mussigbrodt: conceptualization, data curation, formal analysis, investigation, methodology, project administration, writing – original draft, writing – review and editing. Maria Herrera Bethencourt: data curation, investigation, methodology, project administration, validation, visualization, writing – original draft, writing – review and editing. Romain Vergier: conceptualization, project administration, supervision, validation. Marinela Blidar: investigation, validation, visualization. Alberto Alfie: investigation, validation, writing – original draft.

Consent

We confirm that written patient consent has been signed and collected.

Conflicts of Interest

The authors declare no conflicts of interest.

Supporting information

Video S1. Frog sign: Regular pulsations of jugular and subclavian veins, a typical sign of AVNRT. ECG shows regular narrow‐complex tachycardia consistent with AVNRT. EP study confirms the diagnosis. 3‐D mapping displays the right atrial anatomy with His bundle (yellow dots) and right and left inferior extensions of the slow pathway as ablation sites (red dots).