A Case of Lown-Ganong-Levine Syndrome: Due to an Accessory Pathway of James Fibers or Enhanced Atrioventricular Nodal Conduction (EAVNC)?

Abstract

Patient: Male, 17Final Diagnosis: Lown-Ganong-Levine syndromeSymptoms: TachycardiaMedication: —Clinical Procedure: Catheter ablationSpecialty: CardiologyObjective:Unknown ethiologyBackground:Lown-Ganong-Levine syndrome, includes a short PR interval, normal QRS complex, and paroxysmal tachycardia. The pathophysiology of this syndrome includes an accessory pathway connecting the atria and the atrioventricular (AV) node (James fiber), or between the atria and the His bundle (Brechenmacher fiber). Similar features are seen in enhanced atrioventricular nodal conduction (EAVNC), with the underlying pathophysiology due to a fast pathway to the AV node, and with the diagnosis requiring specific electrophysiologic criteria.Case Report:A 17-year-old man presented with a history of recurrent narrow-complex and wide-complex tachycardia on electrocardiogram (ECG). An electrophysiologic study showed an unusually short atrial to His (AH) conduction interval and a normal His to ventricle (HV) interval, without a delta wave. Two stable AH intervals coexisted in the same atrial pacing cycle length. In the recovery curve study, this pathway had a flat conduction curve without an AH increase until the last 60 ms, before reaching the effective refractory period. These ECG changes did not respond to an adenosine challenge. When this pathway became intermittent, there was a paradoxical response to adenosine challenge with conduction via a short AH interval, but without conduction block. Catheter ablation of the AV nodal region resulted in a normalized AH interval, decremental conduction properties, and resulted in a positive response to an adenosine challenge.Conclusions:In this case of Lown-Ganong-Levine syndrome, electrophysiologic studies supported the role of the accessory pathway of James fibers.

Broad Electrocardiogram Syndromes Spectrum: From Common Emergencies to Particular Electrical Heart Disorders

“…It has been attributed to the presence of accessory pathways, as well as to congenital atrioventricular node hypoplasia [68]. Although the exact mechanism is not fully known, the two anatomical variants of the bypass tracts are suspected: the presence of the James or Paladino fiber, situated between the sinoatrial and atrioventricular nodes, and the presence of the Brechenmacher fiber, a bypass tract located between the sinoatrial node and His bundle [69]. Current research has not been able to pinpoint an accessory pathway common to all those affected [70].…”