Radiological Imaging of the Neonatal Chest

"12.3.2.2 Congenital Vascular Anomalies (p. 207)

Congenital vascular anomalies such as right aortic arch with aberrant left subclavian artery, double aortic arch, aberrant left pulmonary artery and anomalous pulmonary venous return including scimitar syndrome are known to have a great impact on related extra cardiac systems (Berrocal et al. 2004). Not only cardiologists but also the paediatric radiologists are, therefore, compelled to acquire profound knowledge about normal as well as aberrant vascular anatomy of the mediastinum.

Because this section is focused on ultrasound we ask the kind reader to refer to other articles in this volume for a more detailed insight into the subject. In right aortic arch with aberrant left subclavian artery, a right aortic arch is present together with a right descending aorta (Fig. 12.8), in contrast to the commonly asymptomatic left aortic arch with aberrant right subclavian artery (Fig. 12.9). The aberrant left subclavian artery originates from a Kommerell diverticulum, an enlargement of the take off of the subclavian artery (Moes and Freedom 1993).

The ductus arteriosus is commonly on the left side and extends from this diverticulum to the left pulmonary artery leading to a vascular ring that may cause tracheo- oesophageal compression in cases where the ductus or ligamentum arteriosum is tight (Berdon 2000). The trachea is displaced to the left. Ultrasound evaluation reveals a right aortic arch and a left carotid artery as a solitary vessel. The presence of an aberrant left subclavian artery is then suspected and demonstrated on a slightly oblique transverse scan. The retro-oesophageal Kommerell diverticulum can be con? rmed by delineating the oesophagus.

A double aortic arch shows two arches with the right arch usually being a little larger and slightly higher than the left (Fig. 12.10). The upper descending aorta may be right- or left-sided. Suprasternal sagittal scans demonstrate both arches and their common carotid and subclavian arteries. A clue to diagnosis is that each arch gives rise to only two main vessels. One will notice that the carotid and subclavian arteries are symmetrically arranged on a high transverse scan. With slight clockwise rotation of the transducer the left arch is imaged on the left side of the oesophagus.

Rotation of the transducer in the other direction will reveal the right arch on the right side of the oesophagus. Both arches are displayed in cross-section in a suprasternal coronal plane. The complete vascular ring may be shown on a transsternal axial scan. In anomalous left pulmonary artery also known as pulmonary artery sling, the left pulmonary artery arises from the posterior aspect of the right pulmonary artery and courses behind the trachea and in front of the oesophagus to reach the left lung."