Radiofrequency catheter ablation of idiopathic left ventricular outflow tract tachycardia: utility of intracardiac echocardiography.

ABSTRACT

INTRODUCTION: The site of origin of idiopathic ventricular tachycardia (VT) arising from the left ventricular outflow tract (LVOT) may be closely related to the aortic valve leaflets, and radiofrequency (RF) delivery potentially can damage them. Intracardiac echocardiography (ICE) can identify accurately the ablation electrode and anatomic landmarks, and contact with the endocardium can be easily assessed. The aim of this study was to define the utility and the accuracy of ICE in guiding RF ablation of idiopathic VT of the LVOT. METHODS AND RESULTS: Five consecutive patients (all men; mean age 20.4 years, range 16 to 25) symptomatic for idiopathic VT underwent RF ablation. A 9-French, in-sheath catheter with a 9-MHz ultrasound transducer was inserted through the femoral vein and positioned in the His-bundle region or right ventricular outflow tract to provide a clear view of the aortic root. Local earliest ventricular activation during tachycardia and pace mapping were used to identify the ablation site. Idiopathic VT was ablated successfully in all patients using a median of two RF pulses, delivered during tachycardia. High-resolution images of the aortic valve and ablation electrode were achievable in all cases. Direct vision of ablation electrode-endocardial contact in the outflow tract was assessed easily in all patients. CONCLUSION: Idiopathic VT of the LVOT can be treated successfully with RF ablation. ICE can accurately guide catheter ablation and identify anatomic landmarks, endocardial contact, and ablation electrode movement.