Coarctation of the aorta(CoA) is described as a congenital condition manifesting as a constricted aortic segment. The localized constriction may form a shelf like structure with an eccentric opening or may be a membranous curtain like structure with a central or eccentric opening. The Coarctation may be discrete, or a long segment of the aorta may be narrowed; the former is more common. CoA is a relatively common congenital heart lesion amounting to 5–8 % of the total and is acyanotic in nature.
The exact cause of CoA is not known. The commonly implicated causes are genetic(such as Turners syndrome) and environmental influences. Coarctation is 7 times more common in whites than Asian persons, with a 2:1 male preponderance. Associated cardiac defects are observed in approximately 50% of patients with Coarctation. The most commonly reported defects are left-sided obstructive or hypoplastic defects and ventricular septal defects. Bicuspid aortic valve is observed in 85% of patients. Also, under developed aortic arch is commonly found in Coarctation associated with intracardiac defects. Extra cardiac anomalies are also reported associated with CoA – aneurysms in the blood vessels of brain and else where, along with aberrant origin of many blood vessels, most commonly those supplying the upper part of body.
Aorta is the great artery receiving the entire output from the left ventricle. It forms an arch, after it leaves the left ventricle, and descends through the chest cavity to the abdominal cavity, where it gives off multiple branches, there by supplying major organs. At the arch of aorta, branches arise which supply the head, neck and the upper limbs. In the fetal life there exist a connection between aorta and the pulmonary artery, which receives the right heart output. This is known as Ductus Arteriosus.
In CoA there is a segment of constriction, most commonly is juxtaductal ie close to the Ductus Arteriosus. Usually the segment of aorta just distal to the constriction undergoes dilatation. This constriction depending on the site results in the symptom complex of CoA. These in early life, depending on severity of obstruction and associated cardiac lesions, patients may present with congestive heart failure, severe acidosis, or decreased blood supply to the lower body. Beyond infancy, patients are usually asymptomatic. They may present with raised blood pressure, headache, nosebleed, leg cramps, muscle weakness, cold feet, or neurologic changes. On examination by a consultant, unequal blood pressures in the two upper limbs – anisosphygmia, and differences in the in pulse between the upper and lower limb may be felt. Investigations can aid in the exact pinpointing of the condition and site. Common investigative modalities used are – Echocardiography, angiography, chest X-ray, electrocardiography. Imaging techniques of MRI and CT scan can be of immense use.
The asymptomatic cases can be followed up without intervention. But the symptomatic cases with raised blood pressure are to undergo surgical correction meanwhile the raised blood pressure has to be effectively lowered. Neonates with severe Coarctation of the aorta should first have their condition stabilized. Patients presenting with less severe Coarctation of the aorta beyond the neonatal period usually show signs of heart failure. These patients should be treated with digoxin and diuretics. CoA is one of those congenital heart diseases which can remain undetected till the adult life. Surgical correction involves:
- Removing the affected segment and replacing it with a tissue or artificial graft.
- Angioplasty: this involves repair of the segment with out removal.
- Catheter-based intervention: is now the preferred therapy, when the anatomy permits and necessary skills are available.
