CATHETER ABLATION FOR SUCCESSFUL MANAGEMENT OF LEFT POSTERIOR FASCICULAR TACHYCARDIA - AN APPROACH GUIDED BY RECORDING OF FASCICULAR POTENTIALS

Objective-To assess whether catheter ablation of fascicular tachycardi a can be facilitated by the recording of sharp deflections arising fro m the mid-septum-inferior apical septum of the left ventricle. Patient s and methods-Seven consecutive patients (mean age 29 (range 16-43) ye ars) with ventricular tachycardia originating from the left posterior fascicle underwent electrophysiology study and detailed mapping of end ocardial activation. Selection of ablation sites in the last five pati ents was based on the recording, during left posterior fascicular tach ycardia and sinus rhythm, of a discrete potential preceding the earlie st ventricular electrogram, which was thought to represent conduction through the posterior fascicle. Results-Patients were treated with low energy direct current or radiofrequency current ablation. The median fluoroscopy and procedure times were 23 (range 6-42) min and 110 (rang e 50-176) min, respectively. In a follow up period of 4 to 16 months, six patients were asymptomatic and one had minor symptoms. No patient had any change in intraventricular conduction. Similar potentials were also recorded from the left posterobasal septum in three of eight pat ients who underwent catheter ablation of left free wall accessory path ways. Conclusion-Fascicular potentials can be reproducibly recorded in left posterior fascicular tachycardia and may serve as a reliable mar ker for successful ablation procedures. The relation of these potentia ls with the substrate of the tachycardia, however, remains obscure.