Successful radiofrequency ablation of junctional ectopic tachycardia in an adult patient

Figure 1. A: Twelve-lead electrocardiogram showing a narrow QRS complex tachycardia at 280 beats/min with a rightward cardiac axis. Atrial activity is hard to discern, but with pharmacologic slowing of the ventricular rate to 180 beats/min (B, lead II rhythm strip), dissociated sinus P waves were apparent (arrows).

Figure 2. A: Surface electrocardiogram (ECG) and intracardiac electrograms during tachycardia with a cycle length (CL) of 504 ms. Catheters were placed at the His bundle region (His), coronary sinus (CS), and right ventricular apex (RV). Atrioventricular dissociation is apparent, with independent atrial activity visible on the surface ECG and on the CS catheter. Premature ventricular beats timed to His refractoriness (arrow) had no effect on the tachycardia CL, nor did paced or spontaneous (asterisk) atrial beats occurring at the time of septal refractoriness. B: Ventricular overdrive pacing during tachycardia with a CL of 480 ms. His activation (H) was accelerated to the pacing CL (460 ms), without conduction to the atrium. On cessation of pacing there was a VHHV response.

Figure 3. A: Catheter position at the site of successful ablation in the right anterior oblique (RAO) and left anterior oblique (LAO) fluoroscopic views. B: Electroanatomic map of the timing of local potentials in RAO view, with position of the coronary sinus catheter (orange), right ventricular apical catheter (red), and ablation catheter (blue). Earliest activation is indicated on the map in white. The blue lesion marks the site where catheter pressure would terminate the tachycardia. The red lesion shows the site of successful ablation, with additional ablation lesions shown in brown. “TA” indicates the plane of the tricuspid annulus based on balanced atrial and ventricular electrogram amplitude. C: Signals at the site of successful ablation. A small sharp potential was evident on the ablation catheter, 76 ms ahead of QRS onset. Abl. = ablation catheter; CS = coronary sinus catheter; prox. = proximal; RV = right ventricular apical catheter.