 Methods: One hundred consecutive patients indicated for typical atrial flutter ablation will be enrolled into the study. The patients will be randomized into group A ablation with use of ICE and B ablation without ICE. The ablation will be done in both groups by two diagnostic catheters 10-pole positioned in coronary sinus and 20-pole halo catheter positioned in the right atrium and radiofrequency ablation catheter. The end-point of the ablation is the achievment of the bicidrectional block across the CTI. The end-points of the study are 1 the total length of the procedure, 2 the fluoroscopy time and 3 the ablation time. The safety end-point is clinically significant bleeding from the groin due to additional puncture for ICE catheter. 