Coarctation of the Aorta: High Blood Pressure in a Child That Is Not What It Seems

What it is

Coarctation is a narrowing of the aorta, usually just beyond the vessels that supply the head and arms. The heart must push blood through that narrow segment, so pressure builds upstream — in the arms and head — while the lower body receives blood at reduced pressure.

That single anatomical fact explains the entire clinical picture, and it is why the diagnosis is so often missed: the blood pressure in the arm, which is where everyone measures it, is genuinely high.

How it presents

In newborns — an emergency

Severe coarctation may be survivable before birth only because the ductus arteriosus supplies the lower body. When the duct closes in the first days of life, the lower body loses its supply abruptly.

The baby becomes suddenly unwell: pale or mottled, breathing fast, poorly feeding, with weak or absent femoral pulses and, if untreated, shock and kidney failure. This is a neonatal emergency requiring medication to reopen the duct and urgent surgery.

Newborn pulse oximetry screening and — crucially — feeling the femoral pulses in every newborn examination are what catch these babies before collapse.

In older children and adults — the silent form

Milder narrowing may go unnoticed for years. It is then typically found in one of three ways:

• Hypertension discovered incidentally in a child, teenager or young adult;
• A murmur heard on routine examination;
• Symptoms — headache, nosebleeds, leg fatigue or leg cramps on exercise, and cold feet.

The leg symptoms are the giveaway, and they are rarely connected to the blood pressure reading.

The examination finding that makes the diagnosis

This deserves stating plainly, because it costs nothing and is repeatedly skipped:

In any child or young adult with high blood pressure, feel the femoral pulses and measure the blood pressure in both an arm and a leg.

In coarctation, femoral pulses are weak, delayed compared with the radial pulse, or absent, and leg blood pressure is lower than arm pressure — the reverse of normal. A young patient labelled with "essential hypertension" and started on tablets without this check may be carrying a curable, surgically correctable cause for years.

Associated conditions

Coarctation rarely travels alone. Roughly half of patients have a bicuspid aortic valve, which carries its own long-term risk of stenosis and of aortic dilatation — see our articles on aortic stenosis and aortic aneurysm and dissection. It is also more common in Turner syndrome, and may be accompanied by septal defects or mitral valve abnormality. Brain aneurysms occur more frequently than in the general population.

Diagnosis

Echocardiography shows the narrowing and the pressure gradient across it, and assesses the valve and ventricle. CT or MR angiography defines the anatomy precisely and demonstrates collateral vessels — arteries that have enlarged over years to carry blood around the obstruction. A chest X-ray in an older patient may show rib notching where those enlarged collaterals have eroded the undersides of the ribs.

Treatment

• Surgical repair — the standard for infants and neonates. The narrowed segment is excised and the healthy ends joined, or the aorta is widened with a patch or a flap. Access is through the left side of the chest, without opening the heart.
• Balloon angioplasty with stenting — widely used in older children and adults with suitable anatomy, and the usual first choice for re-narrowing after previous repair.

Why follow-up must continue for life

This is the most under-appreciated part of coarctation, and it is why the condition appears in our article on adult congenital heart disease.

• Hypertension frequently persists or returns even after a technically perfect repair, particularly when repair was late. Many adults need lifelong antihypertensive treatment and are at raised cardiovascular risk.
• Re-coarctation can develop, especially after repair in infancy as the child grows.
• Aneurysm may form at the repair site years later.
• The bicuspid valve, if present, continues its own course and needs monitoring.

A patient repaired at six months old and discharged at ten years old still needs an adult congenital cardiology review — blood pressure alone is not adequate follow-up.

Further reading

MedlinePlus: congenital heart defects and NHS: congenital heart disease.

On this site: aortic surgery and cardiac surgery.

General education, not advice about your own child. A newborn who becomes suddenly pale, breathless or poorly feeding needs emergency assessment.