Ablation of right ventricular outflow tract tachycardias under guidance of noncontact mapping system

OBJECTIVES
We evaluated the efficiency of noncontact mapping, a new mapping technique, for the catheter ablation of right ventricular outflow tract tachycardias.

STUDY DESIGN
The study included 13 symptomatic patients (4 males, 9 females; mean age 39±15 years) with a structurally normal heart, who had sustained ventricular tachycardia (VT) or nonsustained VT with ventricular premature beats (VPB), all arising from the right ventricular outflow tract. For noncontact mapping-guided (EnSite) ablation, first right ventricular geometry was reconstructed. Then, voltage maps of the right ventricle were obtained during sinus rhythm and tachycardia (or ectopic) beats. Index arrhythmia was induced in the form of sustained VT in three patients, and nonsustained VT or VPB in 10 patients. Radiofrequency was applied to endocardial foci of tachycardia beats using a standard, 4-mm ablation catheter.

RESULTS
The endocardial breakthrough sites of the beats were the posterior septum in seven patients, anterior septum in four patients, and posterior free wall in two patients. A mean of 25 (range 7 to 45) radiofrequency current deliveries were applied to the target sites. The mean procedure time was 190 minutes. Index arrhythmia was eliminated in 10 patients after the procedure. No serious complications occurred during or after the procedure.

CONCLUSION
Our experience with radiofrequency ablation of right ventricular outflow tract tachycardias under noncontact mapping guidance shows that this procedure can be performed efficiently and safely in our country.