Coarctation of the Aorta

Essentials of Diagnosis

• Infants may have severe heart failure; children and adults are usually asymptomatic, presenting with hypertension.
  
• Absent or weak femoral pulses.
  
• Systolic pressure higher in upper extremities than in lower extremities; diastolic pressures are similar.
  
• Harsh systolic murmur heard in the back.
  
• ECG shows left ventricular hypertrophy; chest x-ray shows rib notching; echo-Doppler is diagnostic.

General Considerations

Coarctation of the aorta consists of localized narrowing of the aortic arch just distal to the origin of the left subclavian artery. Collateral circulation develops through the intercostal arteries and the branches of the subclavian arteries. Coarctation is one of the causes of secondary hypertension and should be considered in young patients with elevated blood pressure. A bicuspid aortic valve is also present in 25% of cases.

Clinical Findings

A. Symptoms and Signs
If cardiac failure does not occur in infancy, there are usually no symptoms until the hypertension produces left ventricular failure or cerebral hemorrhage; the latter may also occur from associated cerebral aneurysms. Strong arterial pulsations are seen in the neck and suprasternal notch. Hypertension is present in the arms, but the pressure is normal or low in the legs. This difference is exaggerated by exercise. Femoral pulsations are weak and are delayed in comparison with the brachial pulse. Patients with large collaterals may have relatively small gradients but still have severe coarctation. Late systolic ejection murmurs at the base are often heard better posteriorly, especially over the spinous processes. There may be an associated aortic insufficiency murmur due to a bicuspid aortic valve.

B. Electrocardiography and Chest X-Ray
The ECG usually shows left ventricular hypertrophy. Radiography shows scalloping of the ribs due to enlarged collateral intercostal arteries, dilation of the left subclavian artery and poststenotic aortic dilation, and left ventricular enlargement.

C. Diagnostic Studies
Measurement of the gradient across the lesion by catheterization and aortography remain the primary methods of diagnosis. MRI is a useful imaging adjunct, and Doppler ultrasound can also estimate the severity of obstruction.

Prognosis & Treatment

Cardiac failure is common in infancy and in older untreated patients; it is uncommon in late childhood and young adulthood. Most untreated patients with the adult form of coarctation die before age 50 from the complications of hypertension, rupture of the aorta, infective endarteritis, or cerebral hemorrhage (associated in some cases with congenital cerebral aneurysms). Aortic dissection also occurs with increased frequency in coarctation.