The development of the heart and lung vessels is a very complex process that occurs early, mostly within the first 8 weeks in pregnancy. Complex rearrangements of the primitive vessels are made resulting in disappearance of some parts of the circulation as the embryo matures. A vascular ring is a congenital defect in which there is an abnormal formation of the aorta – the main artery that delivers blood from the heart to the body – and its associated blood vessels. These blood vessels can encircle and compress the breathing tube (trachea), which connects the nose to the lungs, or the feeding tube (esophagus), which connects the mouth to the stomach, leading to breathing and feeding difficulties.
One part of the ring can involve the collapsed ductus arteriosus (ligamentum arteriosus). This does not carry blood but it can constrain other structures in combination with the aortic abnormalities.
The most common type of vascular ring defect is called the double aortic arch. If a child has excessive problems with breathing or feeding, the defect can be treated with surgery, in which the circle of vessels around the trachea or esophagus is separated apart. Another common variant can occur if there is a right-sided aortic arch (most are left-sided) with an aberrant course of the left arm artery (subclavian artery). A vascular sling may occur if there is an unusual course of the left lung artery, which sweeps behind the trachea rather than in front.
If part of the airways are compressed by these abnormal vascular connections, a baby may have difficulty breathing or may make a lot of noise while breathing. This compression may lead to underdevelopment of some of the airways, making them floppy. If the tube connecting the mouth to the stomach (esophagus) is compressed, this may make it difficult to swallow, particularly solid foods. Patients with vascular rings do not typically have symptoms of congestive heart failure, however. In many patients, there may be no symptoms at all.
Vascular rings/slings do not progress, but their effects on other nearby structures may progress causing increasing difficulty in breathing or swallowing.
Medications are not typically helpful in treating vascular rings/slings.
Corrective treatment, when necessary, involves surgery where the vessels are reimplanted into a more normal position and the ligamentum arteriosus is divided.