Posterior his bundle electrogram location in a patient with atrioventricular nodal reentrant tachycardia and structurally normal heart.

Atrioventricular (AV) nodal reentrant tachycardia is the most common form of paroxysmal supraventricular tachycardia in adults, and slow AV nodal pathway ablation has evolved into first-line therapy. Variations in conduction system anatomy are occasionally found at electrophysiological study and may make this ablation procedure very challenging. Here, we present the case of a 69-year-old man with a structurally normal heart and posterior displaced His bundle who underwent successful slow pathway ablation. Demonstration of the characteristic slow pathway recording and His bundle electrogram is strongly recommended prior to radiofrequency energy application in the posterior septal region.