Resection of Kommerell's diverticulum and left subclavian artery transfer does not always relieve symptoms

I read with great interest the article of Backer et al. [1] regarding resection of Kommerell's diverticulum and left subclavian artery (SCA) transfer for recurrent symptoms after vascular ring division. The authors demonstrated that Kommerell's diverticulum could cause recurrent symptoms after simple ligamentum arteriosum division and suggested that patients with a right aortic arch (RAA), retroesophageal left subclavian artery, and ligamentum arteriosum are at risk of compression of the trachea and esophagus from a residual diverticulum. They recommended resection of the Kommerell's diverticulum and re-implantation of the left subclavian artery into the left carotid artery in children with the RAA. The following comments seem to be of interest to the readership.

It is of interest that children with left aortic arch and retroesophageal right subclavian artery are rarely symptomatic. It is this combination that was described by German radiologist Burckhard F. Kommerell [2,3] in 1936. This anomaly is often an accidental finding during investigations for other reasons. It, perhaps, often remains undiagnosed in the general population because of lack of symptoms. Combined with a right ligamentum arteriosum this anomaly may cause compression. In most cases, simple division of the ligamentum is sufficient to relieve symptoms. Upon division of the ligamentum the arch is retracted to the left of the midline relieving the compression.

In situs solitus, lower thoracic and abdominal aorta always descends on the left in patients with either left or right aortic arches. One may speculate that in patients with the left aortic arch, the left descending aorta opposes the traction of the right aberrant SCA, thus, preventing the sling-like effect.

Patients with the RAA may have severe dysphagia and dyspnea even in the absence of the left ligamentum arteriosum, i.e. without vascular ring as such [4]. This demonstrates the sling-like effect of the left SCA pulling the RAA towards the left side.

In RAA, traction of the left SCA is unopposed by the left descending aorta creating a sling-like effect. Thus, the importance of the authors’ recommendation to always divide the aberrant SCA in patients with RAA cannot be overemphasized.

In most cases of RAA, the aorta descends for some distance in the right chest before crossing the midline above the diaphragm and completing its inferior course to the left of the spine. However, on rare occasion, the arch may travel behind the esophagus causing severe compression and descend entirely to the left of the spine. In this case, symptoms could persist after the ligamentum division, resection of Kommerell's diverticulum and division of the left SCA [5]. It would be important to recognize the later type of the RAA and be aware that symptoms could persist in these rare patients after ligamentum division, Kommerell's diverticulum resection and left SCA re-implantation.

In summary, severe esophageal compression by the RAA in the absence of the left ligamentum arteriosum emphasizes the importance of surgical technique recommended by the authors. This technique, however, may fail in rare patients with an unusual form of the RAA.

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