Double accessory pathways in Wolff-Parkinson-White syndrome

Area of Science:

• Electrophysiology
• Cardiology
• Medical Diagnostics

Background:

• Wolff-Parkinson-White (WPW) syndrome is characterized by abnormal electrical conduction in the heart.
• Understanding accessory pathways is crucial for diagnosing and managing WPW syndrome.
• Intracardiac electrophysiological studies provide detailed insights into cardiac conduction abnormalities.

Purpose of the Study:

• To investigate the electrophysiological characteristics of accessory pathways in two patients with WPW syndrome.
• To differentiate between various types of accessory pathways, including Kent, James, and Mahaim bundles.
• To correlate electrophysiological findings with clinical presentation and surface electrocardiogram (ECG) findings.

Main Methods:

• Intracardiac electrophysiological studies involving atrial and ventricular pacing.
• Analysis of His bundle deflection intervals, QRS duration, and P-R (St-V) intervals during pacing.
• Evaluation of A-H and H-V intervals to assess atrioventricular nodal and infra-Hisian conduction.
• Correlation of intracardiac findings with the presence or absence of delta waves on surface ECG.

Main Results:

• Atrial pacing revealed responses consistent with a Kent bundle (accessory pathway connecting atrium to ventricle) in both patients.
• Case 1 showed electrophysiological evidence suggesting an additional James bundle (accessory pathway connecting the atrioventricular node to the His bundle).
• Case 2 exhibited characteristics suggestive of a Mahaim-type bypass (infra-Hisian bypass) with minimal pre-excitation not visible on surface ECG.
• The findings highlight the complexity of accessory pathway anatomy in WPW syndrome.

Conclusions:

• Intracardiac electrophysiological studies are effective in identifying and characterizing diverse accessory pathways in WPW syndrome.
• The study demonstrates the coexistence of multiple accessory pathways and bypass tracts in some patients.
• Accurate identification of accessory pathway types is essential for guiding therapeutic strategies in WPW syndrome.