Authors: Gibbs Yim, MD AND Nicholas Houska, DO - University of Colorado, Children’s Hospital Colorado
A 5-year-old boy presents with recurrent respiratory infections, chronic cough, and dysphagia. Computed tomography of the lungs confirms a right aortic arch with an aberrant left subclavian artery, consistent with a vascular ring. Which of the following vascular anomalies is MOST likely associated with this lesion?
EXPLANATION
Kommerell’s diverticulum is an aneurysmal dilation at the base of the left subclavian artery (LSA). It is most commonly associated with a right aortic arch and aberrant LSA but may also occur in a double aortic arch. Embryologically, the diverticulum is formed from the distal left fourth aortic arch. The tissue of the diverticulum is abnormally friable. A histopathologic study of resected diverticular tissue demonstrated cystic medial necrosis in more than half of the cases (Luciano et al.).
A right aortic arch with aberrant LSA and left ligamentum arteriosum creates a vascular ring in which the trachea and esophagus are encircled by the pulmonary trunk and aorta anteriorly, the aortic arch to the right, an aberrant (retroesophageal) LSA posteriorly, and ligamentum arteriosum to the left. Right arch with aberrant LSA can present with symptoms of tracheoesophageal compression. When compared with a double aortic arch, a vascular ring due to a right arch with aberrant LSA generally presents later in childhood with less severe symptoms. In comparison with other right arch variants, it is less commonly associated with other congenital cardiac anomalies. If repair of the vascular ring is performed by simple ligation of the ligamentum without resection of the diverticulum, respiratory or esophageal symptoms may recur, then requiring additional surgical intervention. Additionally, the diverticulum is at risk for aneurysmal enlargement, rupture, and dissection. Therefore, primary resection of the Kommerell's diverticulum is often recommended at the time of vascular ring repair. More conservative approaches include observation of the diverticulum, vessel plication, or vessel ligation.
Repair of the vascular ring in a patient with a right aortic arch and aberrant LSA consists of ligation of the ligamentum arteriosum, resection of the Kommerell's diverticulum, and reimplantation of the LSA onto the left common carotid artery. During diverticulum resection and LSA reimplantation, a portion of the descending aorta and the left common carotid artery may be clamped temporarily, which can impair perfusion to the abdominal organs and cerebral circulation, respectively. Intraoperative monitoring may include invasive or non-invasive blood pressure measurements of the right upper extremity, bilateral cerebral near-infrared spectroscopy, and either pulse oximetry or noninvasive blood pressure measurement of the lower extremities. Postoperative chylothorax is a known complication of vascular ring repair.
The correct answer is B. A right aortic arch with aberrant LSA is commonly associated with Kommerell’s diverticulum. While interruption and coarctation of the aorta can be present in patients with a right aortic arch, they are much less common in the absence of a diagnosis of heterotaxy.
REFERENCES
Luciano D, Mitchell J, Fraisse A, Lepidi H, Kreitmann B, Ovaert C. Kommerell diverticulum should be removed in children with vascular ring and aberrant left subclavian artery. Ann Thorac Surg. 2015;100(6):2293-2297.
Worhunsky DJ, Levy BE, Stephens EH, Backer CL. Vascular rings. Semin Pediatr Surg. 2021c;30(6):151128. doi: 10.1016/j.sempedsurg.2021.151128. Epub 2021 Oct 23. PMID: 34930596.
