Introduction: Cavo-tricuspid isthmus (CTI) ablation for CTI dependent typical/reverse typical atrial flutter (AFL) has been established. However there are still some cases that can not be created a standard block line on CTI. CTI anatomical characteristics can influence the result of ablation.
Methods: 17 patients (66.5+/- 7.8 years) who underwent CTI ablation for typical/reverse typical AFL were enrolled. We assessed CTI anatomical morphology by multi-slice computed tomography (MSCT) before CTI ablation. The result of ablation was also assessed.
Results: CTI morphologies were divided by MSCT into four groups (flat: F, concave: C, pouch: P and huge Eustachian ridge: E). 11 patients were contained in group F, 2 in group C, 3 in group P and 1 in group E. CTI bidirectional block was not completed in 1 patient in group F and 2 in group C.
Conclusions: The frequency of anatomical variations of CTI is not low when minor variations are included. Though most of these variations can be ablated normally, anatomical information of MSCT can help to ablate CTI by selecting devices, techniques and strategies in difficult cases.