Figure 3. 7-year old patient referred after two failed cryoablations and frequent episodes of tachycardia despite bi-therapy with antiarrhythmics drugs. During the electrophysiology study, a bidirectional antero-septal accessory pathway with easily inducible orthodromic tachycardia was identified. After meticulous mapping of the septal region and identification of the earliest signals in the His region and unsuccessful ablation at close proximity of this site, aortic root mapping was performed. The earliest ventricular signal on the ablation catheter was identified in the right coronary cusp. Aortic root angiogram was performed and a distance of 10mm was measured between the right coronary artery orifice and the target site. A radiofrequency ablation was performed using an energy of 20 Watts with temperature of 50°C, with immediate and definitive termination of the accessory pathway conduction within 4 seconds. The left and right panels show the electro-anatomical reconstruction of the right ventricle, right outflow tract, tricuspid annulus (brown dots), and aortic root with an activation map of the accessory pathway earliest signals on the ventricular insertion (red area). The yellow dots show the areas where His potentials were recorded; the red dots show the successful ablation site located 7.9 mm from the site where mechanical AV block was induced with high contact force (> 20 grams) at the tip of the ablation catheter (blue dots). Within the non-coronary cusp (NCC brown dot) we identified large atrial electrograms. The middle panel shows the surface ECG and intracardiac EGMs recorded on the successful ablation site in the right coronary cusp (RCC) during sinus rhythm, with a clear sharp accessory pathway signal on the distal ablation catheter.
Figure 4. Repeated ablation of a bidirectional accessory pathway within the neck of a diverticulum of the coronary sinus in a 9-year-old patient presenting with pre-excited atrial fibrillation.