Atrial Tachycardia in a Patient with Complex Structural Heart Disease

A 53-year-old male patient with dextrocardia and situs viscera inversus, a congenitally corrected transposition of the great arteries (c-TGA), and atrial septum defect (ASD), secundum type, post patch repair was referred to our laboratory for treatment of frequent episodes of arrhythmia. In the previous fourteen years, the patient had experienced multiple supraventricular tachycardias (SVTs), which were successfully ablated 14, 12, and 2 years prior, respectively. This time in the electrophysiology laboratory, a narrow QRS tachycardia (cycle length=380 msec) was induced by right ventricular and right atrial incremental pacing with concentric activation. A bi-atrial activation map was constructed using a NavX system (St. Jude Medical, St. Paul, MN, USA) via a transseptal procedure to approach the systemic left atrium, which showed a centrifugal activation from a focal origin with mapped cycle length 121 ms (32 % of the tachycardia cycle length) on the systemic high left atrial septum where a large low voltage zone was observed. The bipolar electrograms at the origin of the focal atrial tachycardia (AT) demonstrated fractionated and low-amplitude potentials. Successful ablation was carried out at the AT origin resulting in the non-inducibility of the AT. No recurrence of the tachycardia was observed during one year of follow-up.