Purpose or Case Report: The right aortic arch (RAA) is a relatively frequent congenital anomaly, occurring in approximately 0.05% of the general population. It is classified into three types, according to the branching pattern of the aortic arch vessels: a RAA with an aberrant left subclavian artery, an RAA with mirror image branching and RRA with an isolated left subclavian artery.

The RRA with an isolated left subclavian artery is the least common type of the aortic arch anomalies, with a prevalence of 0.8 %. It occurs when the left subclavian artery losses its connection with the aorta, arising from the ipsilateral pulmonary artery through a left ductus arteriosus, which may be either patent or closed. If the ductus arteriosus is patent, a shunt between the pulmonary and the systemic circulation is established which leads to the congenital subclavian steal phenomenon. The latter is clinically manifested by asymmetric pulse, blood pressure meassurement and size between the upper extremities. This phenomenon will not manifest clinically if there are accompanying cardiac anomalies which balance the preassures of the pulmonary and systemic circulation, which occurs in approximately in 60% of cases.
The diagnosis of this anomaly can be established by invasive arteriography or CT angiography, where late retrograde opacification of the left subclavian artery from the left vertebral artery is observed, with no connection with the aortic arch. The treatment of this anomaly is surgical or endovascular in the presence of symptoms of subclavian steal syndrome.

We present a case report of a five year old female patient with history of a right aortic arch and patent ductus arteriosus with clinically significant hemodynamic effect. On physical examination, there was important asymmetry in pulse palpation, blood pressure readings and size of the upper extremities, which motivated invasive angiographic study which confirmed a right aortic arch, a permeable ductus arteriosus with filiform flow, as well as an isolated subclavian artery with steal phenomenon and direct communication with the main pulmonary artery, leading to significant left heart overload. CT angiography of head and neck was consistent with these findings. Surgical management consisted in reimplantation of the left subclavian artery into the left common carotid artery with favorable clinical outcome.
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