Aortic coarctation with a large right subclavian artery aneurysm

A 20-year-old male patient without a history of neck trauma or instrumentation, presented with a chronic headache and easy fatigue of 1-year duration. He recently developed a muffled voice. His blood pressure at presentation was 200/130 mmHg. The bilateral femoral and dorsalis pedis pulses were low. Both radial pulses were normal.

An AP chest radiograph shows mediastinal enlargement, local mass effect on the trachea, bilateral lower rib notching of the 3^rd to 7^th posterior ribs, and an enlarged heart. Post-contrast chest computed tomography (CT) shows a severe post-ductal aortic coarctation. There is also a 6.3 x 6 cm well-defined and narrow-necked saccular aneurysm of the proximal right subclavian artery with large in situ thrombosis. A dissection flap was not identified. The right axillary and the left subclavian arteries are normal. The left common carotid and brachiocephalic arteries share the same origin. Axial and reformatted sagittal images clearly show prominent paravertebral collaterals and anterior vertebral scalloping.

An echocardiographic assessment was negative for additional intracardiac anomalies, aortic regurgitation or pulmonary artery lesions. Abdominal sonography was also negative for renal artery and aortic lesions. The patient was managed for high blood pressure and was referred for open vascular surgery.

Coarctation of the aorta is a focal narrowing of the aorta and accounts for 5–8% of all congenital heart diseases [1,2]. 95% occur in the isthmus region, mostly just distal to the ductus arteriosus [1]. Adults usually present with systemic hypertension, headaches, claudication, and, progressively, heart failure. Diminished lower-limb pulses are also common [2].

Aneurysms are a common association of the condition and usually occur as berry aneurysms in 10% of cases. Distal aortic aneurysms follow a turbulent flow pattern. Generally, subclavian artery aneurysms are rare, occurring in less than 1% of all large artery aneurysms. They typically occur in old patients with atherosclerosis and an aberrant right subclavian artery [3]. True aneurysms have thick and smooth walls vs. the irregular thin walls seen in pseudoaneurysms [5]. Patients can be asymptomatic or present with a pulsatile supraclavicular mass, shoulder or upper chest pain, Horner's syndrome, or limb ischemia. Distal emboli or rupture is a feared complication [4,6]. Our patient's muffled voice is secondary to his aneurysm's mass effect on the trachea. Subclavian artery dissection with thrombosis is a possible differential diagnosis, but it would commonly show a flap with longitudinal extension to the aorta [7].

A subclavian aneurysm, together with coarctation of the aorta, is an extremely rare occurrence. Hiller et al. [4] reported one case of left subclavian aneurysm in an adult male with aortic coarctation and conducted a literature search. They only found 7 similar cases from 1965 to 1999. One case involved the bilateral subclavian arteries [6]. They proposed that the subclavian aneurysm was caused by high sheer stress due to elevated blood pressure and turbulent flow resulting from coarctation.

A chest radiograph shows the figure of the “3” sign and rib notching. Echocardiography is useful for assessing the pressure gradient across the coarctation and the cardiac valves, as well as secondary left ventricle changes. CT and MRI (magnetic resonance imaging) non-invasively assess the location and extent of the narrowing, status of collateral vessels, relation to adjacent vessels, associated cardiovascular anomalies, impact on the left ventricle, and complications. MRI is the reference standard for post-treatment qualitative and quantitative imaging [1,2].

Advanced cases of coarctation in adults often require surgical repair [2]. Similarly, subclavian artery aneurysms are aggressively approached due to their high chance of rupture [5]. Techniques for coarctation include open surgical repair and endovascular therapies, each with its advantages and disadvantages [2,5]. In our setup, only open repair is available, and it is planned for our patient.

Written informed patient consent for publication has been obtained.