Coarctation of the Aorta (CoA)

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Coarctation of the Aorta (CoA)  

1. Definition

  • Coarctation of the aorta is a narrowing of the aorta, usually at the aortic isthmus (the part just after the left subclavian artery).

  • Rarely, narrowing may occur in the descending thoracic or abdominal aorta.

  • This narrowing obstructs blood flow, leading to increased pressure proximal to the narrowing (upper body) and decreased pressure distal to it (lower body).

2. Epidemiology

  • Occurs in ~3 per 10,000 live births

  • More common in males than females (♂ > ♀)

3. Etiology

Congenital

  • Exact cause is unknown; two main hypotheses:

    1. Hemodynamic theory: underdevelopment of the aorta due to reduced blood flow in utero

    2. Ductal theory: abnormal tissue from the ductus arteriosus extends into the aorta and constricts after birth

  • Associated conditions:

    • Turner syndrome (5–15% of affected females)

    • Bicuspid aortic valve

    • Ventricular septal defect (VSD)

    • Patent ductus arteriosus (PDA)

Acquired

  • Takayasu arteritis

  • Severe atherosclerosis (rare in children)

4. Pathophysiology

  • Narrowing → increased pressure upstream and reduced flow downstream

  • Juxtaductal coarctation is most common (just after ductus arteriosus)

  • In discrete coarctation: LV outflow obstruction → left ventricular hypertrophy and increased collateral blood flow (via intercostal and scapular arteries)

  • In long-segment coarctation: closure of the ductus arteriosus after birth → severe left ventricular overload → hypoperfusion of organs and extremities

    (1) Stenosis distal to the left subclavian artery results in hypertension (↑ BP) in the upper extremities and the head, and hypotension (↓ BP) in the lower extremities and abdomen.


    		(2) If coarctation involves the origin of the left subclavian artery, BP in the right arm and head will be higher than in the left arm, lower extremities, and abdomen.

5. Clinical Features

Neonates

  • Mild CoA may be asymptomatic if PDA is present

  • Critical CoA (PDA-dependent) → shock, organ hypoperfusion, heart failure

Older infants, children, adults

  • Often asymptomatic

  • If present:

    • Differential cyanosis: cyanosis of lower extremities only

    • Brachial-femoral delay: weak femoral pulses

    • BP difference: high BP in upper extremities, low BP in lower extremities

    • Cold feet, leg claudication on exertion

    • Strong apical impulse displaced to left

    • Headache, epistaxis, tinnitus

Auscultation

  • Systolic ejection murmur over left posterior chest

  • Continuous murmur in left infraclavicular or interscapular area (from collateral flow)

6. Diagnostics

Initial Evaluation

  • Blood pressure measurement in upper and lower extremities

  • Pulse oximetry to assess oxygen saturation distal to coarctation

ECG

  • Neonates: signs of RV hypertrophy

  • Older children/adults: LV hypertrophy, or sometimes normal

Chest X-ray

  • Enlarged heart (↑ cardiothoracic ratio)

  • Pulmonary vascular markings

  • “Figure of 3 sign”: aortic indentation at coarctation site with post-stenotic dilatation

  • Rib notching (usually >5 years): collateral vessels cause pressure atrophy of ribs 3–8

Echocardiography

  • Confirms location and severity

  • Detects associated defects (VSD, PDA, bicuspid valve)

Advanced Imaging

  • MRI/CT: anatomical assessment, collateral circulation, and intervention planning

  • Cardiac catheterization: detailed hemodynamics, especially if CAD risk is present

  • Genetic testing: consider Turner syndrome if clinically suspected

7. Treatment

Neonates with Critical Coarctation

  • Prostaglandin E1 infusion (e.g., alprostadil) to keep ductus arteriosus open

  • Provides distal organ perfusion until surgery

Noncritical Coarctation

  • Surgical repair: preferred in neonates and infants

  • Balloon angioplasty: usually in older children/adults

  • Stent placement: in selected adult patients

Medical Management

  • Control hypertension in all patients

  • Supportive care: inotropes, respiratory support if heart failure present

  • Restriction of strenuous physical activity if BP remains high or obstruction persists

8. Complications

  • Secondary hypertension

  • Aortic dissection or rupture

  • Berry aneurysms → cerebral hemorrhage

  • Heart failure

  • Infective endocarditis

  • Re-coarctation after repair

Summary

Coarctation of the aorta is a congenital narrowing that increases upper body pressure and decreases lower body perfusion. It may remain silent until later in life or present as severe neonatal heart failure. Diagnosis relies on blood pressure measurement, imaging (echocardiography, MRI/CT), and sometimes catheterization. Management depends on severity and age, ranging from prostaglandin infusion in neonates to surgical repair or stenting in older patients. Lifelong follow-up is important to monitor hypertension, re-coarctation, and vascular complications.

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