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Page 8 of 14 Bader et al. Vessel Plus 2020;4:34 I http://dx.doi.org/10.20517/2574-1209.2020.36

A small proportion of patients with circumflex aortic arch may remain asymptomatic or do not present
until much later in life [11,16,43] . Asymptomatic circumflex arch may also present as an incidental finding with
[33]
intracardiac lesion such as VSD . However, the presence of a retroesophageal arch segment may result in
a more severe form of vascular ring and symptoms may be more common in those with an unobstructive
arch than in those with hypoplastic arch.

IMAGING
When presented incidentally, mediastinal widening on plain chest x-ray in circumflex aortic arch
[8]
can be mistaken as a mediastinal mass or an aortic aneurysm . The proximal and distal ends of the
retroesophageal transverse arch may form bilateral “aortic knobs” on chest x-ray resulting in a symmetrical
superior mediastinal widening.

Barium swallow is useful to provide a clear demonstration of posterior oesophageal compression from the
circumflex arch [17,22] . In severe oesophageal compression, there could reflux of the contrast materials into
the nasopharynx . Prior to the advent of CT, suspicious findings on barium study would trigger cardiac
[17]
[17]
catheterization, leading to the diagnosis of circumflex aorta .
Transthoracic echocardiography is the most common initial diagnostic test, which leads to the suspicion
of congenital arch malformation. Echocardiography also further evaluates for any arch obstruction
and intracardiac lesions. As a hypoplastic retroesophageal segment is not easily demonstrated on
echocardiography, a circumflex aorta with right aortic arch, aberrant left subclavian artery, and critical arch
[5]
hypoplasia can be easily mistaken for type B aortic arch interruption .

CT angiogram with 3D reconstruction is the best imaging modality to demonstrate the presence of
retroesophageal transverse arch and confirms the definitive diagnosis of circumflex aortic arch. A CT scan
will also identify compression of the trachea and oesophagus [Figures 6 and 7].

In patients presenting with respiratory symptoms, bronchoscopy is often performed first by the
otolaryngology team. The presence of pulsatile compression will then trigger cross-sectional imaging
and establish the diagnosis of a circumflex arch. The diagnosis can be missed in the absence of pulsatile
compression, which may not be easily evident in cases where there is complete occlusion of the main
[9]
stem bronchus . CT is, therefore, recommended to exclude vascular compression. When the diagnosis of
circumflex aortic arch is established, intra-operative bronchoscopy may help to confirm adequate relief of
vascular compression at the time of surgical repair.

SURGICAL MANAGEMENT
Surgery is indicated for significant symptoms and for any associated significant aortic arch hypoplasia.
The surgical approach and timing of surgery are likely dictated by the severity of symptoms and arch
obstruction. Complications associated with Kommerrell diverticulum, such as progressive aneurysm or
dissection may also trigger for surgical intervention. Surgical management varies in literature, from simple
division of the arterial ligament alone to full anatomical correction such as an aortic uncrossing procedure.

Division of arterial ligament
Without arch hypoplasia or obstruction, division of arterial ligament alone has been used to relieve the
symptoms from vascular ring. Symptomatic improvement had been reported following division, although
long-term data are lacking . Nevertheless, this approach may offer a simple surgical solution associated
[18]
with low surgical morbidity, without needing cardiopulmonary bypass or extensive posterior mediastinal
dissection. Surgery can be approached via a standard posterolateral thoracotomy, or less invasive procedure