Clot Formation during Catheter Ablation for Atrial Fibrillation Using Open Irrigation Tip Catheter

Backgrounds: During Catheter ablation for atrial fibrillation (AF), extensive application of radiofrequency energy can lead to clot formation. The external irrigation for the tip electrode might prevent clot formation, which remains to be clarified. Methods and Results: We retrospectively studied the incidence of the clot formation during ablation for AF in our facility using irrigation Catheter, in which irrigation flow rate was set at 17ml/min (=or<30W) or 30ml/min (>30W) and the RF generator would be automatically switched off when the temperature rose to 43degrees Celsius or at the impedance rise. Out of 331 cases who underwent AF ablation using irrigation Catheter, 20 clot formations in 17 cases (15 males, 59±9y) were observed. The activated clotting time was kept over 300sec by intravenous heparin administration during left atrial Catheterization. All of clot formations were found at the proximal edge of irrigation tip electrode, which developed at 32.2±4.0W, 42.8±2.9degrees Celsius accompanied byimpedance rise with 34.6±24.2ohm. Clot formation was likely to occur around the right pulmonary vein (PV) (65%) than around the left PV (20%). No strokes or thromboembolisms were found after ablation in every patient. Conclusions: Clot formation can occur during AF ablation even using open irrigation tip Catheter.