Discussion
TAPVC is a rare congenital heart defect. The incidence rate was 5 to 9 per 100 000 live births. The most common type of TAPVC is supracardiac TAPVC, accounting for approximately half of all TAPVC patients (Figure 3). Patients with TAPVC are usually symptomatic at a very young age, and less than 7% of them with surgical correction can survive into adulthood. The clinical presentation of TAPVC is mainly determined by the degree of pulmonary venous drainage obstruction and the magnitude of the left-to-right shunt (3, 4). Our patient lived with no symptoms until found at her 46-year-old because of palpitations and exertional dyspnea caused by atrial flutter.
In this case, this patient was particularly unusual in that she has been living without symptom until her nearly fifth decade of life without the need of medication. Two factors, the absence of the pulmonary venous obstruction and a large ASD, contribute to the long-time survival for this patient in supracardiac TAPVR. It explains the lack of cyanosis and normal blood pressure in this patient. Cardiac CT provides accurate anatomical delineation of pulmonary venous pathways and their connections (5). According to the CT scan of this patient, no unobstructed pulmonary venous circulation was observed. Cardiac catheterization showed no pulmonary over-circulation and a normal cardiac output. Cardiac CT scan and catheterization showed this patient had no pulmonary venous obstruction and a large ASD.
The classical ‘calabash’ configuration on the chest radiograph is uncommonly observed in supracardiac TAPVR. The SVC and right heart dilation formed right-sided configuration and the dilated innominate vein mainly consist of this left-sided configuration. There is also non-specific appearance of chest radiograph in some patients, and then used as such CT scan and echocardiography for accurate diagnosis of TAPVR. This patient was firstly reported as classical ‘calabash’ appearance on the chest radiograph. And was diagnosed by CT scan and echocardiography. Cardiac CT scan presented venous system enlargement but aortic system disuse atrophy. Cardiac hemodynamic assessment in patient showed no pulmonary hypertension and for further surgical repair.
Surgical repair is immediate need in most cases once the diagnosis of TAPVC is made. The surgical mortality is less than 5% when repair is performed in patients without obstructed pulmonary veins. This patient successfully underwent TAPVC surgical correction and closed ASD. Although surgery results in a normal circulation (the pulmonary veins returning normally to the left atrium), she appeared pulmonary edema because of aortic disuse atrophy and relatively excessive cardiac output. Several factors predict the poor outcomes such as pulmonary venous obstruction before repair, a younger age at repair, pulmonary vein size and univentricular heart (6). However, the long-term outcome after surgical repair of TAPVC is also excellent.