IVC interruption is a rare congenital anomaly. A good knowledge of this uncommon anatomical variant is key when performing percutaneous cardiac procedures through vein catheterization.

The standard femoral venous access routinely used for electrophysiological procedures can be technically challenging with this uncommon venous anomaly. Catheters advancement through a well-developed azygos continuation can be attempted as a first approach to reach the right heart. In case of failure, alternatives using an upper approach through the superior vena cava should be considered.

We report the case of a 60 years old female, who underwent catheter ablation of a counterclockwise flutter. During the procedure, she was discovered to have an uncommon anatomical venous pathway from femoral access to the right heart chambers. She was diagnosed to have an interruption of the supra-renal segment of the inferior vena cava with azygos continuation. Radiofrequency ablation of the cavotricuspid isthmus ( Fig. 1 ) was successfully performed through the azygos continuation.

The prevalence of IVC interruption remains unknown in patients undergoing electrophysiological study procedures. Catheter ablation in patients with azygos continuation is technically challenging. The azygos continuation can be used to access the right heart chambers, as in our patient's case, if the IVC-azygos communication is well developed. If the continuation is underdeveloped, alternative access routes such as the internal jugular or the subclavian veins should be sought. Difficulties during ablation include poor catheter maneuverability and stability. Achieving stable lead positioning optimal orientation and consistent tip-tissue contact force is technically challenging with the superior approach compared to femoral vein and IVC access. Besides, the SVC approach must be undertaken with caution due to the risk of complications.

Electrophysiological procedures via femoral access in the presence of IVC interruption are feasible through the azygos continuation. Ablation in these conditions is very challenging, underscoring the need for precise diagnosis of venous anatomy and associated congenital heart disease. Ablation with advanced mapping techniques would be highly beneficial for these patients.