Antidromic Nodoventricular Reciprocating Tachycardia With Left-Ventricular Insertion: Insights From High-Density Mapping.

We describe the case of a 38-year-old male with a long history of paroxysmal supraventricular tachycardia (PSVT) who was found to have typical slow-fast atrioventricular nodal reentrant tachycardia (AVNRT) and nodoventricular reentrant tachycardia (NVRT). During an electrophysiology study, a wide complex tachycardia with left bundle branch block (LBBB) morphology with V2 transition was induced, exhibiting ventriculo-atrial (VA) dissociation and characteristics suggesting an AV node-ventricle reentrant circuit. Careful mapping and pacing maneuvers supported the diagnosis of a nodoventricular reentrant tachycardia (NVRT) with insertion site in the LV septum by using high-density mapping coexisting with typical AVNRT. The patient was successfully treated with radiofrequency ablation at the slow pathway region, eliminating both arrhythmias. This case highlights the evidence of unusual NV pathway with LV insertion and importance of differentiating AVNRT with aberrancy or concomitant ventricular tachycardia (VT) from an accessory pathway-mediated reentrant tachycardia.