Coexistent posteroseptal and right-sided atrioventricular bypass tracts

Area of Science:

• Electrophysiology
• Cardiology
• Medical Diagnostics

Background:

• Posteroseptal accessory pathways are common causes of supraventricular tachycardia.
• Identifying all accessory pathways is critical for successful ablation.
• Atypical electrocardiogram (ECG) findings can indicate complex cardiac conduction abnormalities.

Purpose of the Study:

• To investigate the prevalence of dual atrioventricular (AV) bypass tracts in patients presenting with a posteroseptal accessory pathway.
• To determine the diagnostic utility of ECG in identifying associated right-sided accessory pathways.
• To emphasize the importance of thorough electrophysiologic mapping in patients undergoing ablation for posteroseptal accessory pathways.

Main Methods:

• Complete electrophysiologic studies were performed in twelve patients with a posteroseptal accessory pathway.
• Four patients were identified with a second, right-sided AV bypass tract (anterior, anteromedial, or anterolateral).
• Intraoperative epicardial mapping and catheter-induced retrograde conduction studies confirmed the presence of dual pathways in some cases.

Main Results:

• Four out of twelve patients (33%) with a posteroseptal accessory pathway had an additional right-sided AV bypass tract.
• ECG patterns were atypical in three of these four patients, showing negative or slightly positive delta waves in anterior leads.
• One patient had an intermittently atypical ECG, highlighting the challenge in diagnosing dual pathways based solely on surface ECG.

Conclusions:

• There is a significant association between posteroseptal and right-sided accessory pathways.
• A complete mapping study of the tricuspid annulus is mandatory for patients with posteroseptal accessory pathways undergoing ablation.
• Even seemingly typical ECGs for isolated posteroseptal pathways may mask the presence of dual AV bypass tracts, necessitating comprehensive electrophysiologic evaluation.