Fehmi Keçe

Biophysical parameters and Micro-Embolic Signals 109 4 4.1 Introduction Asymptomatic cerebral emboli (ACE) on magnetic resonance imaging after atrial fibrillation (AF) ablation are of concern. Emboli formation may be diagnosed by recording micro- embolic signals (MES) with transcranial Doppler ultrasonography during ablation. A high incidence of ACE has been reported following ablation with the first generation non- irrigated multi-electrode ablation catheter (PVAC) and was attributed to temperature overshoot, electrode interaction, and poor electrode-tissue contact (1,2). Therefore, three major design changes were incorporated in the second generation PVAC-Gold: gold- electrodes to prevent temperature overshoot, removal of the 10 th electrode to prevent electrode interaction, and a 20° angle between the catheter ring and shaft to improve contact. Despite these advances, we found ACE/cerebral infarctions in 23% of paroxysmal AF patients using PVAC-Gold compared with in 6% of patients using a Thermocool catheter in a recent randomized trial (3). Of importance, the median number of micro-embolic signals (MES) was significantly higher with PVAC-Gold compared with Thermocool. In this study biophysical parameters of PVAC-Gold applications associated with MES are analyzed to gain insight into the potential mechanism of MES generation using the redesigned catheter.