Coarctation of the Aorta (CoA)

Why is this topic important?

Coarctation of the Aorta (CoA) is one of the most important congenital heart diseases tested in MRCPCH examinations.

It is particularly important because:

It may present as a neonatal emergency.
It is a duct-dependent congenital heart lesion.
Delayed diagnosis can result in shock, heart failure and death.
The diagnosis may be missed unless femoral pulses are examined carefully.

MRCPCH candidates are expected to:

Recognise the clinical presentation
Understand duct-dependent circulation
Identify radiofemoral delay
Interpret blood pressure differences
Understand management and complications

Definition

Coarctation of the Aorta is a congenital narrowing of the aorta, usually occurring near the insertion of the ductus arteriosus.

This narrowing obstructs blood flow from the heart to the lower part of the body.

Key MRCPCH Facts

Coarctation is a duct-dependent congenital heart lesion.
Weak or absent femoral pulses are a key clinical sign.
Radiofemoral delay is a classic examination finding.
Blood pressure is higher in the arms than the legs.
Closure of the ductus arteriosus may precipitate circulatory collapse.
Prostaglandin E₁ may be lifesaving in neonates.
Echocardiography is the gold standard diagnostic investigation.

Anatomy

Typical Site

Most coarctations occur:

Just Distal to the Origin of the Left Subclavian Artery

Near the insertion of the ductus arteriosus.

This is called:

Juxtaductal Coarctation

and is the commonest form.

Pathophysiology

Normal Circulation

Blood flows freely through the aorta to supply:

Upper limbs
Lower limbs
Abdominal organs

In Coarctation

The narrowed segment obstructs blood flow.

Consequences include:

Proximal to the Coarctation

Higher pressure:

Head
Neck
Upper limbs

Distal to the Coarctation

Reduced blood flow:

Abdomen
Kidneys
Lower limbs

Duct-Dependent Circulation

Neonatal Presentation

Before ductal closure:

The ductus arteriosus may provide blood flow to the lower body.

When the duct closes:

Lower body perfusion falls
Cardiac output decreases
Shock develops

This is one of the most important MRCPCH concepts.

Associated Conditions

Congenital Heart Disease

Common associations:

Bicuspid aortic valve
VSD
PDA
Aortic stenosis

Genetic Syndromes

Particularly associated with:

Turner Syndrome

Every girl with Turner syndrome should be assessed for coarctation.

Clinical Presentation

Presentation depends on age.

Neonatal Presentation

Typically occurs when the duct closes.

Features include:

Cardiovascular Collapse

Poor feeding
Lethargy
Pallor
Poor perfusion
Shock

Heart Failure

Tachypnoea
Respiratory distress
Hepatomegaly

Examination

Weak femoral pulses
Absent femoral pulses
Differential pulses

This is a classic MRCPCH scenario.

Infant Presentation

May present with:

Poor feeding
Failure to thrive
Tachypnoea
Heart failure

Older Child Presentation

May be asymptomatic.

Possible findings:

Hypertension

Particularly upper limb hypertension.

Exercise Symptoms

Leg fatigue
Claudication
Reduced exercise tolerance

Headache

Due to hypertension.

Examination Findings

Pulse Examination

Weak Femoral Pulses

One of the most important findings.

Radiofemoral Delay

Radial pulse felt before femoral pulse.

Classic MRCPCH sign.

Blood Pressure

Upper Limbs

Higher blood pressure.

Lower Limbs

Lower blood pressure.

Normally leg blood pressure is slightly higher than arm blood pressure.

Reversal of this relationship strongly suggests coarctation.

Murmur

May hear:

Ejection systolic murmur
Murmur over back
Associated murmurs from other defects

Differential Diagnosis

Neonatal Collapse

Neonatal sepsis
Hypoplastic left heart syndrome
Critical aortic stenosis
Metabolic disease

Hypertension

Renal disease
Endocrine causes

Investigations

Pulse Oximetry

May be normal.

Normal saturation does not exclude coarctation.

ECG

May show:

Left ventricular hypertrophy

Chest X-Ray

Possible findings:

Cardiomegaly
Pulmonary oedema

Older children may demonstrate:

Rib Notching

Due to collateral circulation.

A classic examination fact.

Echocardiography

Gold Standard Investigation

Demonstrates:

Site of narrowing
Severity
Associated lesions
Ventricular function

Cardiac MRI

Often used in older children and adults.

Management

Neonatal Emergency Management

If duct-dependent coarctation suspected:

Prostaglandin E₁ Infusion

Keeps the ductus arteriosus open.

This may restore systemic blood flow.

This is a very important MRCPCH concept.

Supportive Care

Oxygen if needed
Fluid management
Intensive care support

Definitive Treatment

Surgical Repair

Most common treatment.

Methods include:

End-to-end anastomosis
Extended end-to-end repair

Balloon Angioplasty

Used in selected cases.

Complications

Short-Term

Heart failure
Shock
Death if untreated

Long-Term

Recoarctation
Persistent hypertension
Aortic aneurysm
Stroke
Left ventricular hypertrophy

Common Exam Traps

Trap 1

Always check femoral pulses in every newborn.

Trap 2

Weak femoral pulses suggest coarctation.

Trap 3

Radiofemoral delay is a classic sign.

Trap 4

Upper limb blood pressure is higher than lower limb blood pressure.

Trap 5

Normal oxygen saturation does not exclude coarctation.

Trap 6

Closure of the ductus arteriosus may precipitate shock.

Trap 7

Prostaglandin E₁ can be lifesaving.

Trap 8

Turner syndrome is strongly associated with coarctation.

One Minute Revision

Narrowing of the aorta near the ductus arteriosus.
Duct-dependent congenital heart disease.
Weak femoral pulses.
Radiofemoral delay.
Upper limb hypertension.
Neonates may collapse when duct closes.
Prostaglandin E₁ is lifesaving.
Echocardiography confirms diagnosis.

Suggested References

NICE Guidance
RCPCH Guidance
BNF for Children
Nelson Textbook of Pediatrics
Illustrated Textbook of Paediatrics
Park's Pediatric Cardiology for Practitioners
Moss & Adams' Heart Disease in Infants, Children and Adolescents

Disclaimer

These notes are intended for MRCPCH revision and educational purposes only. They do not replace local, national or institutional guidelines. Clinical decisions should always be based on current guidance, senior advice and individual patient circumstances.

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