Successful Radiofrequency Catheter Ablation of Atrioventricular Nodal Reentrant Tachycardia in a Patient with Dextrocardia and Situs Invertus

Experience of radiofrequency catheter ablation (RFCA) in patients with dextrocardia and sinus invertus is limited for its extremely rare incidence. A 21-year-old male with recurrent episodes of supraventricular tachycardia was referred to our hospital for the electrophysiological study (EPS). He had received operation for double outlet right ventricle with ventricular septal defect at his age of 9 months. Twelve lead ECG, echocardiography and computed tomography showed dextrocardia with situs invertus. At EPS, electrode catheters were positioned at the right atrial appendage, His bundle - right ventricular apex and the coronary sinus as completely mirror image. Programmed electrical stimulation induced typical atrioventricular nodal reentrant tachycardia (AVNRT). A 3.5 mm tip sarine-irrigated ablation catheter was required to successful ablation of slow pathway (SP), which was not located at usual Koch's triangle region but at rightward position, and the tachycardia became non-inducible. This suggests SP might have located at the right side of atrial septum, despite completely mirror image. The CARTO-XP (Biosense Webster) was useful for determine the intracardiac orientation. This is a unique case of AVNRT in a patient with mirror-image dextrocardia. We could successfully treated AVNRT by sarine-irrigated RFCA. Exact anatomical evaluation using electro-anatomical mapping is critical in such a case with cardiac anomaly.