Interrupted aortic arch (IAA) is an uncommon congenital cardiovascular anomaly where there is a separation between the ascending and descending aorta. It can either be complete or connected by a remnant fibrous band. An accompanying large ventricular septal defect (VSD) and/or patent ductus arteriosus (PDA) is frequently present.

Epidemiology

It may account for ~1.5% of congenital cardiac anomalies. 

Pathology

Faulty embryological development of the aortic arch (thought to occur during the 5^th to 7^th week of intrauterine life).

Classification

According to the Celoria-Patton classification, IAA can be classified into three types according to the location of the anomaly:

• type A: second most common, the interruption occurs distal to the left subclavian arterial origin 

• type B: most common (>50%), the break occurs between the left common carotid and left subclavian arterial origins

• type C: rare, interruption occurs proximal to the left common carotid arterial origin

Each type is divided into three subtypes ⁷:

• subtype 1: normal subclavian artery

• subtype 2: aberrant subclavian artery

• subtype 3: isolated subclavian artery that arises from the ductus arteriosus

Associations

• DiGeorge syndrome ¹

  • found commonly in those with a type B interruption

  • almost always associated if there is a right-sided descending aorta

• truncus arteriosus ⁸

• aortopulmonary septal defect (aortopulmonary window)

• transposition of the great arteries

• double outlet right ventricle

• functional single ventricle 

Radiographic features

Plain radiograph

Plain film features are often non-specific ³:

• the aortic knuckle may be absent

• may show cardiomegaly

Ultrasound

The right ventricle may appear a lot larger than the left, although this is a non-specific finding. The ascending aorta may also appear more vertical than usual. These modalities may not allow differentiation of IAA from severe aortic coarctation with a hypoplastic arch ⁹.

CT

Allows visualization of the interrupted aortic arch and associated anomalies. 

MRI

• non-visualization of the portion of interruption

• great vessels may show a "V" configuration on coronal imaging ²

Treatment and prognosis

If uncorrected, it carries a very poor prognosis with extrauterine survival being as little as a few days. Prostaglandin E₁ may be given to initial management to keep the ductus open. Surgical correction (either single- or multistage) is the definitive treatment.

Differential diagnosis

General differential considerations include:

• short segment severe aortic coarctation