Common Arterial Trunk with Interrupted Aortic Arch

Clinical data: Patient diagnosed with common arterial trunk, submitted to pulmonary artery banding in another center and lost to clinical follow-up. Referred to our center at four years old, extremely cyanotic. Chest radiography: Cardiomegaly; attenuated peripheral vascular markings. Electrocardiography: Right ventricular hypertrophy. Echocardiography: Common arterial trunk, but it was not possible to analyze all the structures. Computed tomography angiography: Van Praagh type A4 common arterial trunk. Extremely hypoplastic right and left pulmonary arteries. Diagnosis: Association of aortic arch interruption type A is uncommon and should be considered. Operation: Debanding of pulmonary arteries allowing for possible future complete repair.


Echocardiography
Situs solitus in levocardia. Normal venoatrial and atrioventricular connections and anormal ventricular arterial connection.
Doppler demonstrated a 15-mm ventricular septal defect with no restrictive flow, and moderate truncal valve insufficiency described as bicuspid.
It was not possible to analyze the main pulmonary artery and its branches, aortic arch, and coronaries, due to echocardiographic window technical difficulty.
For diagnostic confirmation, the patient underwent complementary computed tomography angiography.

Computed Tomography Angiography
Common trunk that trifurcates into banded and very hypoplastic right and left branch pulmonary arteries, ductal continuation to descending aorta, and ascending aorta emerging from common trunk as a side branch. Right and left pulmonary arteries originating from the sides of the common trunk with significant distance between them. Thus, confirming diagnosis of Van Praagh type A4 common arterial trunk (CAT) (Figure 1) [1] .
Right and left pulmonary arteries are stenotic at the origin (coinciding with the surgical bandage), measuring 1 mm on the right side and 2 mm on the left side.

COMMENT Diagnosis
Truncus arteriosus or CAT is defined as a single vessel usually arising from both ventricles originating systemic, pulmonary, and coronary artery circulation. Significant morphological variability is found in the pattern of great arterial branching from the common trunk. The clinical presentation is dependent on morphological variation, degree of truncal valve regurgitation, and relative resistances of the pulmonary and systemic arterial vascular beds [2] .
From an epidemiological point of view, CAT is an uncommon congenital cardiac malformation accounting for approximately 1 to 4% of all congenital heart diseases [2] . The association of CAT with interruption of the aortic arch is found in approximately 11 to 19% of patients [3] . The interruption is classified as type A, B, or C, according to the location of discontinuity [3] . In a clinical study of 70 patients, 10% had interruption of the aortic arch, and only two patients had interruption distal to the left subclavian artery (type A) [4] .
Russel et al. [5] proposed a simplified categorization for CAT, which aimed to assess whether the common trunk itself continued primarily to supply the aortic or pulmonary component. In the setting of pulmonary dominance, the patient also has hypoplastic or interrupted aortic arch.
Type A aortic arch interruption in association with CAT is relatively uncommon, has worse prognosis, and should be taken into consideration [1] . Also, we must consider differential diagnosis of transposition of the great arteries with interventricular communication, hypoplastic left heart syndrome, tetralogy of Fallot with pulmonary valve agenesis, and complex heart diseases without pulmonary stenosis [6] .
Precise diagnosis was confirmed by computed tomography angiography, however, despite correct diagnosis, the patient was referred cyanotic, with extremely hypoplastic pulmonary arteries, thus contraindicating the complete repair.

Operation
After thorough multidisciplinary heart team discussion, the decision was debanding of right and left pulmonary artery branches. It was performed through median sternotomy and diagnosed a CAT with primary supply to the lungs (pulmonary dominance) and an interrupted aortic arch type A (distal to the left subclavian artery).
As shown in angiotomography, the right and left pulmonary branches were extremely hypoplastic. The procedure was concluded as planned, aiming the development of the pulmonary artery branches, and allowing for possible future complete repair ( Figure 2). Immediately after debanding, saturation increased to 88%.
The patient had no postoperative complications and remained hospitalized for five days. She was discharged without complaints and with oxygen saturation of 93%. Currently, the patient is in clinical follow-up without use of medications; future imaging tests will be required for reintervention planning.