Vascular compression syndromes are often collectively referred to as vascular rings and slings, but this characterization does not represent the true diversity of the group of conditions.
Compromise of the trachea and/or esophagus in the upper mediastinum by adjacent vascular structures is a common feature of vascular compression syndromes.
Because of this shared feature, vascular compression syndromes often present with similar clinical pictures of stridor and/or dysphagia and their diagnostic evaluation relies on similar strategies.
The developmental embryology of vascular compression syndromes is quite different, however, and this may influence the presence or absence of associated anomalies and cause treatment strategies to differ dramatically.
Vascular compression syndromes are most easily segregated into 3 main groups:
Anomalies of aortic arch branching (which include the true vascular rings in addition to anomalous origin of the right subclavian artery)
Left pulmonary artery sling
Innominate artery compression syndrome
Vascular rings include a number of anatomic variations of anomalous development of the aortic arch complex, resulting in vascular structures completely encircling both the trachea and the esophagus. Pulmonary artery sling refers to the anomalous origin of the left pulmonary artery (LPA) from the right pulmonary artery that courses between the trachea and esophagus to the left hilum. This is often associated with significant tracheal stenosis or hypoplasia. The innominate compression syndrome refers to tracheal compression by the adjacent, developmentally normal innominate artery. The primary pathology is more likely to be tracheomalacia than malformation or malposition of an artery.
True vascular rings exist when the trachea and esophagus are completely encircled by vascular structures associated with altered development of the aortic arch and its branches. These surrounding vascular structures may include the aorta and its branches as well as the ductus/ligamentum arteriosus, and the pulmonary artery.
The thoracic aorta originally develops from the bilaterally symmetrical fourth aortic arches. By the end of the second month of gestation, components of the arch complex have regressed leaving the “typical” anatomy of a left aortic arch with 3 arch branches (innominate, left common carotid, and left subclavian) and a left-sided ductus arteriosus from the proximal LPA to the aorta in the general vicinity of the left subclavian artery origin (Fig. 73-1). Virtually all vascular rings can be explained by anomalous regression or persistence of different components of the bilateral aortic arch complex.
Depiction of the developmental embryology of the aortic arch in (A) an early stage of development and (B) a later stage after involution of the right aortic arch.
The two most common variants of true vascular rings are persistent double aortic arch and right aortic arch with left ...