QRS alternans during right ventricular pacing while ablating a concealed left sided accessory pathway

• Main Authors: Raghav Bansal, Ramalingam Vadivelu, Eduardo Back Sternick, Yash Lokhandwala
• Format: Article
• Language: English
• Published: Elsevier 2021-09-01
• Series: Indian Pacing and Electrophysiology Journal
• Subjects: QRS alternans; Catheter induced bigeminy; Radiofrequency ablation; Left free wall accessory pathway
• Online Access: http://www.sciencedirect.com/science/article/pii/S0972629221000875
• ISSN: 0972-6292

A 16-year-old boy was referred for an electrophysiological study for documented regular narrow complex tachycardia. A diagnosis of a concealed left lateral accessory pathway was made with an eccentric atrial activation sequence both during tachycardia and right ventricular (RV) pacing. The pathway was mapped at the left posterior mitral vestibule during RV pacing, performed through the distal tip of the His bundle catheter pushed into right ventricular outflow tract. An unusual response to ventricular stimulation with alternation of QRS complex width and morphology was noted. The possible mechanisms are hereby discussed.