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.