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.