Vascular Ring and Pulmonary Artery Sling

Persistence of both the right and left embryonic dorsal aortic arches results in the development of a double aortic arch. The ascending aorta gives rise to right and left arches that encircle the trachea and esophagus and rejoin to form the descending thoracic aorta. This acts as a ring and compresses the trachea and esophagus, causing obstructive symptoms (Fig. 17.1). Each arch gives rise to a subclavian artery and a carotid artery. There is no innominate artery in this condition. Surgery is indicated for symptoms related to narrowing of the esophagus and/or trachea.

DOUBLE AORTIC ARCH

Incision

A left posterolateral thoracotomy in the fourth intercostal space is the approach most commonly preferred. A right thoracotomy can be used if the left aortic arch is dominant, which occurs rarely.

Technique

The left lung is retracted anteriorly and inferiorly toward the diaphragm to bring into view the area of the aortic arch and ductus arteriosus or ligamentum. The parietal pleura is incised longitudinally on the anterior surface of the descending aorta and left subclavian artery. The pleural flap containing the vagus nerve and its branches is retracted anteriorly; meticulous dissection is carried out to identify the local anatomy precisely. The surgeon should be aware that pulling the nerve toward the pulmonary artery causes the recurrent nerve to lie along a diagonal course behind the ductus or ligamentum, thereby increasing the risk of injury to the nerve.

The aorta and ductus or ligamentum are then mobilized by sharp dissection. The ductus or ligamentum is divided after ligating both ends.

The smaller (usually left anterior) aortic arch is dissected free and divided between clamps. The ends are then oversewn with 5-0 or 6-0 Prolene suture in two layers (Figs. 17.2 and 17.3).

Adhesions of the Esophagus and Trachea

Both the trachea and the esophagus must be dissected free of any adhesions and fibrous bands to ensure that narrowing of these structures is relieved. This entails freeing up the divided ends of the arch from the surrounding tissues.

Division of Ductus or Ligamentum

The ductus arteriosus or ligamentum must always be doubly ligated and divided. Otherwise, compression of the trachea and esophagus will persist because of the aortic arch
being pulled downward toward the pulmonary artery. It is also important to resect any adjacent scar tissue that could contribute to postoperative tethering or scar.