In the presented article, we describe a clinical case of successful interventional treatment of tachycardia in a patient who previously underwent a Senning procedure for transposition of the great arteries. The anatomical reconstruction of the atria following this surgery creates unique conditions for the development and maintenance of macro-reentrant tachycardias, which significantly complicates their diagnosis and treatment. Using a modern three-dimensional navigation system, high-precision activation and voltage mapping of the surgically reconstructed systemic and pulmonary atria was performed. The obtained data allowed detailed visualization of areas of slow conduction and reconstruction of the anatomical contour of the arrhythmogenic circuit. Identification of the critical slow-conduction isthmus was a key step in selecting the therapeutic strategy. Targeted radiofrequency ablation was performed at the identified area, resulting in interruption of the macroreentrant circuit, termination of the tachycardia, and restoration of stable sinus rhythm. The procedure was associated with an immediate clinical effect and no early complications. Special attention in the article is paid to the role of modern navigation technologies, which become crucial in the setting of complex and atypical cardiac anatomy after palliative and radical surgeries. Use of such systems significantly accelerates the localization of arrhythmogenic substrates, increases the accuracy and effectiveness of interventional treatment, and reduces the risk of arrhythmia recurrence. This clinical case demonstrates the high effectiveness of integrating electrophysiological mapping and catheter ablation in the management of complex rhythm disorders in patients after reconstructive cardiac surgery. This experience highlights the promise of a combined approach that incorporates advanced imaging technologies and individualized interventional treatment strategies, opening new possibilities for arrhythmia therapy in patients with congenital heart defects.