A 5.5-month-old girl was admitted with non-specific signs and symptoms like dyspnea at rest, tachypnea, fatigue, low body weight and cyanosis on exertion. Physical examination revealed a barrel-shaped chest; no pathological sounds over the heart or both lung areas were detected. The above mentioned symptoms might suggest a circulatory problem. Echocardiography and computed tomography angiography were performed. These examinations revealed supracardiac type total anomalous pulmonary venous drainage. Echocardiographic signs of pulmonary hypertension and severe right ventricle overload were detected. Detailed analysis of both imaging examinations revealed atypical obstruction of the pulmonary venous return: narrowing of the proximal part of superior vena cava. An urgent surgery was performed, with no complications in the postoperative period. A follow-up echocardiography showed normalization of cardiac function and pulmonary pressure as well as normalization of flow profile within the superior vena cava. The paper presents a non-invasive diagnostic process in the described case, and discusses the causes of late diagnosis.