Pediatric Cardiology • Parent Guide

Coarctation of the Aorta

A narrowing of the body’s main artery — the aorta. It can cause high blood pressure in the arms, weak pulses in the legs, and in newborns, a life-threatening collapse when a critical vessel closes.

📚 Rudolph’s Congenital Diseases of the Heart, 3rd Ed. (Ch. 12) | Moss & Adams, 10th Ed. (Ch. 45)
👨‍⚕️ Pediatric Cardiology

1 in 2500

Live births affected by coarctation of the aorta

50%

Of CoA patients also have a bicuspid aortic valve

5–8%

Of Turner syndrome girls have CoA

20–30%

residual

Hypertension even after successful repair

🫀 What Is Coarctation?

A Narrowing in the Body’s Largest Artery

The aorta is the main artery that carries oxygenated blood from the heart to the entire body. In coarctation (from Latin coarctare — to press together), a segment of the aorta is narrowed — most commonly at the aortic isthmus, just past where the ductus arteriosus attaches, near the left subclavian artery.

This narrowing creates an obstruction: blood pressure is high in the arms and head (above the narrowing), while blood flow to the lower body (legs, kidneys, abdominal organs) is reduced. Over time, this pressure differential strains the heart and, if untreated, leads to serious complications.

💡

Why Does It Happen Near the Ductus?

The narrowing typically occurs at the point where the ductus arteriosus attaches to the aorta. Rudolph (Ch. 12) describes the “posterior shelf” theory — a ridge of ductal tissue extends into the aortic wall. When the ductus closes after birth, this shelf becomes more prominent and the aortic obstruction becomes manifest. This is why coarctation may not be apparent in the womb but reveals itself dramatically in the first days of life when the ductus closes.

Coarctation of the Aorta — Anatomy & Blood Pressure Effect

⬆️ HIGH Blood Pressure (Arms & Head)	⬇️ LOW Blood Pressure (Legs & Abdomen)
Right arm Head Left arm LV pumps against high resistance Hypertension above coarct	Legs & abdomen Weak femoral pulses Delayed radio-femoral pulse Collateral vessels bypass obstruction → Rib Notching on X-ray → “3-Sign” on Chest X-Ray

⬆️ HIGH Blood Pressure (Arms & Head)

⬇️ LOW Blood Pressure (Legs & Abdomen)

Right arm
Head
Left arm

LV pumps against high resistance
Hypertension above coarct

Legs & abdomen
Weak femoral pulses
Delayed radio-femoral pulse

Collateral vessels bypass obstruction
→ Rib Notching on X-ray
→ “3-Sign” on Chest X-Ray

Coarctation creates a pressure gradient: high BP above the narrowing (arms/head) and low BP below (legs/abdomen). Collateral vessels develop over time causing rib notching.

🩺 Two Very Different Presentations

How CoA Presents — It Depends on Age

Coarctation can present in two dramatically different ways depending on whether the ductus arteriosus is still open:

🚨 The Sick Newborn (Ductal-Dependent CoA)

When the ductus closes in the first days of life, blood flow to the lower body suddenly drops. The baby rapidly deteriorates: grey/pale, cold extremities, poor feeding, no femoral pulses, metabolic acidosis, and shock. This is a cardiac emergency.

Treatment: Immediate PGE₁ infusion to reopen the ductus, then urgent surgical repair or balloon dilation.

This is often misdiagnosed as sepsis — a CoA must always be considered in any shocked newborn.

🔵 The Older Child (Incidentally Detected)

Milder coarctation may not cause symptoms in the newborn period. The child grows normally but develops hypertension in the arms, headaches, and leg fatigue or cramps with exercise. A systolic murmur may be heard over the back.

Key diagnostic clue: Upper limb BP significantly higher than lower limb BP, with weak or delayed femoral pulses.

This is an important and underdiagnosed cause of childhood hypertension — always check femoral pulses.

⚠️

CoA and Turner Syndrome

Turner syndrome (45,X — missing one X chromosome) affects girls and is associated with coarctation in 5–8% of cases, as well as bicuspid aortic valve. All girls diagnosed with Turner syndrome should have a cardiac evaluation including echocardiography.

🔍 Diagnosis

Diagnosing Coarctation

Investigation	Findings in CoA	Significance
Blood Pressure (4-limb)	Right arm BP > right leg BP by ≥20 mmHg	Most important clinical test
Femoral Pulses	Weak, absent, or delayed vs. radial pulses (radio-femoral delay)	Hallmark sign
Chest X-Ray	“3-sign” at aortic knuckle; rib notching (3rd–8th ribs) in older children; cardiomegaly in neonates	Supportive
ECG	Right ventricular hypertrophy (neonates); left ventricular hypertrophy (older children/adults)	Supportive
Echocardiogram	Visualises narrowing, measures gradient, assesses bicuspid AV, aortic arch size	Definitive in most cases
MRI / CT Angiography	Precise anatomy, collateral vessels, post-repair assessment	Gold standard anatomy

Coarctation Treatment Pathway

CoA Confirmed
Echo / MRI / CT angiography

▼

🚨 Neonate / Sick

PGE₁ Infusion → Reopen ductus
Stabilise baby

▼

🔴 Surgical Repair
Resection + end-to-end

👦 Older Child

🔵 Balloon Angioplasty ± Stent
OR
🔴 Surgical Resection / patch

▼

Lifelong follow-up
BP monitoring + Echo annually

Treatment depends on age and presentation. Neonates with critical coarctation require PGE₁ and surgery, while older children may be suitable for catheter intervention.

⚠️ Complications

Why Coarctation Must Always Be Treated

Hypertension

Persistent high blood pressure above the narrowing leads to left ventricular hypertrophy, premature atherosclerosis, stroke, and aortic aneurysm. Even after repair, ~20–30% retain hypertension requiring lifelong medication.

Bicuspid Aortic Valve

50% of CoA patients have a bicuspid aortic valve (two leaflets instead of three). This independently requires monitoring for stenosis and regurgitation, and is a risk factor for aortic root dilation and dissection.

Intracranial Aneurysms

The chronic high pressure in the head predisposes to berry aneurysms of the Circle of Willis — which can rupture. Repair of the coarctation reduces but does not eliminate this risk, particularly if hypertension persists.

Restenosis After Repair

The repaired segment can narrow again (restenosis), especially in infants repaired very young. Regular echocardiographic follow-up is essential. Re-intervention with balloon angioplasty and stenting is often successful.

❓ FAQ

Frequently Asked Questions

How is coarctation usually first detected?+

In newborns, it may present as sudden collapse when the ductus closes. In older children, it is often detected during a routine check for high blood pressure, a school sports physical, or when a doctor notices weak leg pulses. A systolic murmur over the back (between the shoulder blades) is another clue. All children should have their blood pressure checked regularly — including in the legs. CoA is one of the most important secondary causes of childhood hypertension.

What is “radio-femoral delay” and why does it matter?+

Radio-femoral delay is when the pulse felt at the wrist (radial pulse) arrives noticeably earlier than the pulse felt at the groin (femoral pulse). Normally both arrive almost simultaneously. In coarctation, the narrowing slows blood flow to the legs, causing a detectable delay. This is a simple bedside finding that should trigger further investigation for CoA. It is one of the most important physical signs in pediatric cardiology.

What surgery is done for coarctation?+

The most common surgical approach is resection with end-to-end anastomosis — the narrowed segment is cut out and the two ends of the aorta are stitched together. In older children with suitable anatomy, balloon angioplasty (stretching the narrowing with a balloon catheter) with or without stent placement is preferred because it avoids open surgery. Patch repair (widening the narrowing with a patch) was formerly common but has a higher risk of late aneurysm formation.

Will my child still have high blood pressure after surgery?+

Repair significantly reduces blood pressure, but about 20–30% of patients still have residual hypertension requiring medication, particularly if repair was done later in childhood or if the hypertension was longstanding. This is why early repair is preferred. Lifelong blood pressure monitoring is essential. Regular echocardiography monitors for restenosis, bicuspid valve disease, and aortic dilation.

Can my child play sports after CoA repair?+

Most children can return to full activity after successful CoA repair, provided there is no significant residual gradient, no resting or exercise-induced hypertension, and no aortic aneurysm (Moss & Adams, Ch. 45). Competitive sports are usually permitted. Your cardiologist will assess this at follow-up appointments with blood pressure measurement and echocardiography.

What is the “3-sign” on a chest X-ray?+

In older children and adults with coarctation, the left border of the aorta on a chest X-ray shows a characteristic indentation at the site of the narrowing, with a dilated aortic segment above and a dilated post-stenotic segment below — this creates a shape that resembles the number “3.” It is a classic radiological sign of coarctation. Rib notching (erosion of the undersides of the ribs by enlarged collateral arteries) is another classic X-ray finding, typically seen in children older than 5–6 years.

🎯 Key Takeaways

Coarctation is a narrowing of the aorta at the isthmus — causing high BP in the arms and reduced flow to the legs.

It presents in two ways: as a collapsed newborn when the ductus closes, or as hypertension/weak femoral pulses in an older child.

50% of patients also have a bicuspid aortic valve — both need lifelong monitoring.

Key signs: radio-femoral delay, upper > lower limb BP, rib notching on X-ray, “3-sign.”

Treatment: PGE₁ stabilisation → surgery (neonates) or balloon/stent (older children). Outcomes are excellent.

Lifelong follow-up is essential — residual hypertension, restenosis, and aortic valve disease all require monitoring.