Atriofascicular Mahaim with Ebstein anomaly: A case report

Area of Science:

• Cardiology
• Pediatric Electrophysiology
• Congenital Heart Disease

Background:

• Atriofascicular Mahaim (AFM) pathways are rare accessory pathways that can cause supraventricular tachycardia.
• Ebstein's anomaly is a congenital heart defect affecting the tricuspid valve, often associated with accessory pathways.
• Differentiating AFM from other accessory pathway syndromes like Wolff-Parkinson-White (WPW) syndrome is crucial for appropriate management.

Purpose of the Study:

• To describe a unique case of concomitant atriofascicular Mahaim pathway and Ebstein's anomaly in a pediatric patient.
• To elucidate the electrophysiological characteristics differentiating AFM from WPW syndrome.
• To highlight the diagnostic challenges and findings in complex congenital heart disease with accessory pathways.

Main Methods:

• Case report of a 7-year-old girl.
• Electrocardiogram (ECG) and Holter monitoring.
• Electrophysiological study (EPS) including His potential recording and His-ventricular interval assessment.

Main Results:

• The patient presented with a left bundle branch block pattern on ECG.
• Holter monitoring revealed PR interval prolongation and QRS morphological changes during sinus tachycardia.
• Electrophysiological study demonstrated retrograde His conduction and faster conduction from Mahaim fiber to His bundle compared to the atrioventricular node.

Conclusions:

• This case highlights the importance of detailed electrophysiological assessment in diagnosing concomitant atriofascicular Mahaim pathway and Ebstein's anomaly.
• The distinct electrophysiological findings aid in differentiating AFM from WPW syndrome.
• Understanding these differences is critical for guiding therapeutic strategies in pediatric patients with complex congenital heart conditions and arrhythmias.