Ring Char Formation During High-Power, Short-Duration Ablation Using an Irrigated Six-Hole Contact Force Sensing Tip...

During circumferential ablation of the right pulmonary veins (PVs), high-power, short-duration (HPSD) ablation at the anterior wall of the right PVs, corresponding to the left atrial septal side, resulted in an abrupt impedance increase from 120 to 180 Ω, occurring 11 s after RF delivery initiation (A). After an abrupt impedance rise, withdrawal of the ablation catheter from the long sheath revealed a circumferential thrombus adhering directly above the irrigation holes at the catheter tip (B). The catheter tip after thrombus removal is shown in (C), and the ring-shaped thrombus that adhered to the catheter tip is displayed in (D).