Two Distinct Atrial Breakthroughs During Fast-Slow Atrioventricular Nodal Reentrant Tachycardia

Area of Science:

• Electrophysiology
• Cardiology
• Cardiac Arrhythmias

Background:

• The slow pathway (SP) in atrioventricular nodal reentrant tachycardia (AVNRT) usually presents a single atrial breakthrough site.
• Understanding these pathways is crucial for effective ablation strategies.

Observation:

• A unique case of fast-slow AVNRT was observed with two distinct atrial breakthrough sites during tachycardia.
• The earliest atrial activation site (EAAS) was initially identified at the right inferior septum.

Findings:

• A subsequent breakthrough occurred at the inferolateral wall of the tricuspid annulus, indicating a second activation site.
• Radiofrequency ablation targeting the EAAS successfully redirected the breakthrough to the inferolateral wall.

Implications:

• This case highlights the potential for a single slow pathway to generate multiple atrial breakthrough sites in AVNRT.
• It suggests a need for comprehensive electrophysiological mapping to identify all potential breakthrough sites for successful ablation.