Ventricular Tachycardia With a Narrow QRS Complex

Figure 1. Patient's Electrocardiograms (A) Electrocardiogram on arrival at the emergency department showing a regular narrow-borderline QRS tachycardia (QRS duration: 120 milliseconds) at 180 beats/min, with positive values in lead II and negative values in lead III, with precordial transition in V2. (B) Electrocardiogram after cardioversion demonstrating atrial fibrillation with ventricular pacing dependence. The paced QRS complex shows an R-wave in lead V1, with a left bundle branch block–like morphology in the remaining precordial leads (QRS duration: 162 milliseconds).

Figure 2. Electroanatomical Mapping of the Left Ventricle During the Second Procedure (A) Activation map and (B) voltage map obtained during ventricular tachycardia (VT) using a retroaortic approach. The activation map identifies a slow conduction channel in the basal posteroseptal region, adjacent to the proximal left bundle branch, whereas the voltage map demonstrates a corresponding low-voltage area. Radiofrequency ablation targeting this region resulted in VT termination and subsequent noninducibility. The aorta (AO) and interventricular septum (IVS) are shown as anatomical landmarks.

Visual Summary. Narrow QRS Ventricular Tachycardia in a Pacemaker-Dependent Patient