A novel technique for improved lesions in the coronary sinus. comparison of bipolar and unipolar ablation

The stepwise approach to radiofrequency (RF) ablation of atrial fibrillation (AF) can include ablation of the coronary sinus (CS) by RF delivery at the left atrium (LA) and/or within the CS. In both cases, the energy is applied between the tip electrode of a percutaneous catheter and a dispersive electrode on the body surface. We explored the feasibility of using the electrode rings of a diagnostic catheter placed in the CS as dispersive electrode(s) for RF delivery within the LA and compared this technique to an established CS ablation method.Excised pig hearts were superfused with a pulsatile saline flow. Bipolar ablation was performed between a saline-irrigated (20 mL/minute) 4-mm tip electrode placed in the LA adjacent to the CS and 7 electrode rings of a 6F, septapolar, 4-mm nonirrigated electrode placed within the CS adjacent to the LA endocardial electrode. Unipolar ablation was performed between the endocardial electrode and dispersive electrode. A continuous transmural lesion was produced in 6/8 (75%) attempts with bipolar ablation, but in 0/6 (0%) attempts with unipolar ablation. However, the incidence of steam pop tended to be increased with bipolar ablation.Bipolar ablation of the CS appears to be highly effective for creating a transmural LA-CS lesion.