Bipolar irrigated radiofrequency ablation: A therapeutic option for refractory intramural atrial and ventricular tachycardia circuits

Background Irrigated radiofrequency (RF) ablation can be insufficient to eliminate intramurally located septal atrial flutter (AFL) and ventricular tachycardia (VT) circuits. Bipolar ablation between 2 ablation catheters may be considered for such circuits. Objective To evaluate the utility of bipolar irrigated ablation to terminate arrhythmias resistant to unipolar ablation. Methods In vitro: Bipolar and sequential unipolar RF ablation lesions were placed on porcine ventricular tissue in a saline bath to assess for lesion transmurality. Clinical: 3 patients with atypical septal flutter (AFL), 4 patients with septal VT, and 2 with left ventricle free-wall VT, all of whom failed sequential unipolar RF ablation, underwent bipolar RF ablation using irrigated catheters placed on either surface of the interatria/interventricular septum and left ventricle free-wall, respectively. Results In vitro: Bipolar RF was found to be more likely to achieve transmural lesions (82% vs 33%; P = .001) and could do so in tissues with thicknesses of up to 25 mm. Clinical: All 5 AFLs (3 patients) were successfully terminated with bipolar RF. In follow-up, AFL recurred in 2 of the 3 patients and atrial fibrillation and AFL recurred in 1 of the 3. All 3 thereafter underwent repeat procedures with successful maintenance of sinus rhythm in 2 of the 3 patients (6-month follow-up). In the VT subgroup, 5 of 6 septal VTs and 2 of 3 free-wall VTs were terminated successfully during ablation. In follow-up (12 months), 2 of the 4 patients in the septal bipolar group and 1 of the 2 patients in the free-wall group remained free of VT. Conclusions Bipolar RF can be used to terminate arrhythmias in select patients with tachyarrhythmias.