Lesion Formation by Ventricular Septal Ablation With Irrigated Electrodes - Comparison of Bipolar and Sequential Unipolar Ablation -

BACKGROUND: Ablation of ventricular tachycardia originating from the interventricular septum (IVS) is often limited by the presence of re-entrant pathways deep in the IVS. We compared the efficacy of bipolar ablation vs. sequential unipolar ablation in creating a transmural lesion across the porcine IVS. METHODS AND RESULTS: Seventeen excised swine hearts were superfused by pulsatile saline flow. Bipolar ablation (at 30 W, 50 W or 70 W for 120 s) was performed between 2 saline-irrigated (20 ml/min) 4-mm tip electrodes, 1 on the left and 1 on the right side of the IVS. Sequential unipolar ablation (at 30 W, 50 W or 70 W for 120 s) was performed on the left and right sides of the IVS with an irrigated-tip catheter. Bipolar ablation produced a narrower, deeper lesion than did unipolar ablation. A transmural lesion was created by sequential unipolar ablation in 7.7%, 8.3% and 0% of tissue preparations and by bipolar ablation in 50.0%, 46.7% and 71.4% of tissue preparations at 30 W, 50 W and 70 W. CONCLUSIONS: Bipolar ablation of the IVS was highly effective for creating a transmural IVS lesion.