Diagnosis
Diagnosis of the isolated lesion is difficult, since it does not produce
any symptoms.23,62,63,66 Presentation, therefore, is
usually based on the discovery of associated cardiac anomalies. In
earlier reports, the diagnosis was most often established at
necropsy.7,18,23,37-42,63-66
The chest roentgenogram findings vary according to the associated
anomalies. Association of a curved border in the superior mediastinum on
frontal chest radiographs, or a high aortic arch on the lateral
projections, is suggestive, although not diagnostic.3Diagnosis can usually be made by transthoracic ultrasonography, and is
enhanced by saline contrast transthoracic or transesophageal
echocardiography.11-13,18,19,21-25 The ultrasound
“window” may be of poor quality in cases of thymic hypoplasia or
agenesis.14 Visualization of the frontal section of
the aortic arch allows recognition of the entire course of left
brachiocephalic vein. If the lesion is suspected, then the right
anterior oblique view is used for a left aortic arch, and the left
anterior oblique view for a right aortic arch.12
Using suprasternal views, contrast echocardiography with injection in
left arm vein usually demonstrates the course with greater accuracy.
Doppler recording allows avoidance of confusion with other structures,
particularly the right pulmonary artery or the unusual atrial appendages
as found in left isomerism (Figures 2A and 2B).
Three-dimensional computed tomographic angiocardiography, and magnetic
resonance imaging, are helpful in ascertaining the diagnosis, and in
demonstrating the relationship of the vein to the adjacent structures
(Figures 1A-1F, 3A-3C,
4A-4C).3-5,9,10,14,15,17,22,25,27-29,32-36,43-46,59,69Cardiac catheterization and angiography may still be indicated in
doubtful cases, and for evaluation of associated cardiac
anomalies.13,20,28,48,55,57,74 Computed tomography and
magnetic resonance imaging similarly come into their own for the
assessment of associated lesions.