Coarctation of the aorta - Congenital heart disease

Coarctation of the aorta

Definition

Localised narrowing of the descending aorta close to the site of the ductus arteriosus.

Pathophysiology

Coarctation of the aorta tends to occur at the site of the ductus/ligamentus arteriosus, which is usually opposite the origin of the left subclavian artery (see Fig. 2.19). The left ventricle hypertrophies to overcome the obstruction and cardiac failure may occur. Upper body hypertension develops with hypotension in the lower body.

In adult patients longstanding narrowing leads to dilation of the intercostal arteries and may cause systemic hypertension due to poor renal perfusion.

Neonatal coarctation is often associated with a patent ductus arteriosus in which the high aortic pressures result in severe left to right shunting and early severe cardiac failure.

Eighty per cent of cases occur in association with a bicuspid aortic valve.

Clinical features

Proximal hypertension may cause headache and dizziness, distal hypotension results in weakness and poor peripheral circulation. On examination the femoral pulses are weak or absent and there is radiofemoral delay. Fourlimb blood pressure measurement will demonstrate the difference between upper and lower body. The flow murmur across the coarctation is best heard at the back.

Investigations

·        Chest X-ray may show left ventricular hypertrophy and rib notching due to dilated intercostal arteries causing erosion.

·        ECG may show left ventricular hypertrophy.

Management

Surgical treatment is used in the majority of cases and is an emergency in coarctation complicated by a patent ductus arteriosus. The chest is opened by left lateral thoracotomy, the stricture is resected and end-to-end anas-tomosis is performed with a graft inserted in the case of long strictures. The repaired portion of the aorta may not grow and thus a ‘restenosis’ may occur, this is often treated by balloon dilatation.

Prognosis

Without treatment 50% of patients die within the first year of life from cardiac failure and complications of hypertension such as intracranial bleeds.