Radiofrequency Catheter Ablation of Accessory Pahyways in Patients with WPW Syndrome

In this article, we reported two patients with WPW syndrome treated by radiofrequency catheter ablation (RFA). The computerized BARD 24-lab system was used for electrophysiologic study (EPS) and atrial mapping. The catheter ablation was performed using radiofrequency energy delivered as a continuous, unmodulated sine wave at 350 kHz (Model RFG 3D, Radionics) between the distal electrode of the ablation catheter and a large skin electrode position on the chest. Case 1: A 43-year old male patient was admitted due to attacks of supraventricular tachycardia (SVT) resistant to medical treatment. The ECG showed WPW syndrome. The EPS revealed that the patient had orthodromic atrioventricular reentrant tachycardia (AVRT) using the left free wall accessory pathway. Utilizing a steerable quadripolar 4 mm tip electrode ablation catheter (7F, Mansfield), endocardial mapping localized earliest point of retrograde atrial activation to be in the mitral annulus during the orthodromic AVRT and right ventricular pacing. The local ventricular electrogram to delta wave interval was also used to determine the target area of the ablation. Fourteen 10-second 25 W applications of RF energies were unsuccessful. However, during the 15th energy application, the AVRT suddenly returned to sinus rythym and the delta wave disappeared, PR and QRS intervals returned to normal. Thirty minutes after ablation of the accessory pathway, the EPS findings confirmed the absence of conduction through the accessory AV connection. The echocardiogram was normal after the procedure. Case 2: A 36 year old male patient was admitted due to attacks of SVT resistant to medical treatment. The ECG showed WPW syndrome. The EPS revealed that the patient had orthodromic AVRT using the right free wall accessory pathway. Utilizing a streerable quadripolar 4 mm tip electrode ablation catheter (7F, Mansfield), endocardial mapping localized earliest point of retrograde atrial activation to be in the free wall of the right atrium during the orthodromic AVRT and right ventricular pacing. The local ventricular electrogram to delta wave interval was also used to determine the target area of the ablation. Five 10-second 25 W applications of RF energies were unsuccessful. However, during the 6th energy application, the delta wave disappeared, PR and QRS intervals returned to normal. Thirty minutes after ablation of the accessory pathway, the EPS findings confirmed the absence of conduction through the accessory AV connection. The echocardiogram was normal after the procedure. No complication occured in both patients. During the 6 months of follow-up, the patient has not had symptoms of tachycardia, and the 12-lead ECG was normal. We confirmed that the radiofrequency catheter ablation of the accessory pathway may be an effective and safe method in the treatment of patients with WPW syndrome.