Coarctation of the Aorta
Summary
Coarctation of the Aorta (CoA) is a congenital narrowing of the aortic lumen, typically located at the isthmus (the site of insertion of the ductus arteriosus, just distal to the left subclavian artery). It presents on a spectrum from neonatal cardiogenic shock (duct-dependent circulation) to undiagnosed severe hypertension in adulthood. [1,2]
Key Facts
- Mechanism: Obstruction of Left Ventricular outflow causes pressure overload (Afterload mismatch).
- Associations:
- Bicuspid Aortic Valve: Present in up to 85% of CoA cases.
- Turner Syndrome (45XO): 15-20% of Turner girls have CoA.
- Intracranial Aneurysms: "Berry Aneurysms" in Circle of Willis (Screening MRA required in adults).
Clinical Pearls
The "Duct Dependent" Crash: In severe neonatal CoA, the lower body perfusion is supplied entirely by the Patent Ductus Arteriosus (PDA) (Right-to-Left shunt). As long as the duct is open, the baby looks fine (perhaps slight differential cyanosis). When the duct closes (Days 2-7), the systemic circulation is cut off. The baby presents with grey shock, absent femoral pulses, and severe metabolic acidosis. Prostaglandin E1/E2 is lifesaving.
Rib Notching: In longstanding adult CoA, high-pressure blood bypasses the stenosis via collaterals: Subclavian -> Internal Thoracic -> Intercostal Arteries -> Descending Aorta. These dilated, tortuous intercostal arteries erode the inferior margin of the ribs (3rd to 8th), visible on CXR.
Leg Pressure: In healthy people, BP in the legs is 10-20mmHg higher than arms. In CoA, it is lower.
Demographics
- Incidence: 4 per 10,000 live births (5-8% of all CHD).
- Gender: Male > Female (2:1), except in Turner Syndrome.
Hemodynamics
- Obstruction: Increases Left Ventricular (LV) Afterload -> LV Hypertrophy -> LV Failure.
- Hypoperfusion: Renal hypoperfusion activates RAAS -> Secondary Hypertension -> Further vascular stiffening.
- Collaterals: In chronic cases, extensive collateral networks bypass the obstruction.
Infantile Type (Severe)
Adult Type (Chronic)
- Pulses:
- Radio-Femoral Delay: Palpate R Radial and R Femoral simultaneously.
- Radio-Radial Delay: If coarctation originates proximal to Left Subclavian (rare).
- Blood Pressure: Measure in all 4 limbs. (Gradient >20mmHg is significant).
- Ausculation: Continuous systolic murmur over the back (left interscapular area).
- Face: Turner stigmata (webbed neck, low ears)?
Imaging
- Echocardiogram: First line. Shows "Posterior shelf" and accelerated flow velocity (>2m/s) in descending aorta.
- CXR:
- "3" Sign: Indentation of aorta at the coarctation site looks like the number 3.
- Rib Notching: Inferior surfaces.
- CT/MRI Angiogram: Gold standard for delineating anatomy before intervention. Screening for Berry Aneurysms.
Management Algorithm
SUSPECTED COARCTATION
↓
NEONATE OR CHILD/ADULT?
┌───────────┴───────────┐
NEONATE (Sick) CHILD/ADULT (Stable)
↓ ↓
RESUSCITATION HYPERTENSION CONTROL
- Start PGE1 (Prostin) - Beta-Blockers
- Intubate / Ventilate - MRI Aorta
- Correct Acidosis ↓
↓ INTERVENTION
SURGERY (Elective)
(Urgent) ↓
┌─────────────┴─────────────┐
SURGERY CATHETER
(End-to-end Anastomosis) (Stent / Balloon)
- Preferred for Infants - Preferred for Adults
- No prosthetic material - Avoids Thoracotomy
1. Medical (Neonatal)
- Prostaglandin E1/E2 Infusion: Keeps the duct open. Apnea is a side effect (monitor airway).
- Inotropes: Dopamine/Dobutamine for LV support.
2. Surgical (Resection)
- End-to-end Anastomosis: Excision of the narrowed segment. Gold standard for infants.
- Subclavian Flap: Using the subclavian artery to patch the aorta (Rare now due to arm ischemia).
3. Transcatheter (Stenting)
- Balloon Angioplasty: High rate of elastic recoil (restenosis).
- Stenting: Gold standard for adults/older children. (Covered stents used to reduce aneurysm risk).
- Re-Coarctation: Stenosis recurs.
- Aortic Aneurysm: Tissue at the repair site is abnormal.
- Paradoxical Hypertension: Hypertension persists post-repair in 30-50% (due to reset baroreceptors / vessel stiffness).
- Spinal Cord Ischaemia: Paraplegia (rare, 0.4%) from interruption of spinal arteries during repair.
- Untreated: Mean survival 35 years. Death from Heart Failure, Aortic Rupture, or Stroke.
- Treated: Good survival, but lifelong follow-up required (BP control, aneurysm surveillance).
Key Guidelines
| Guideline | Organisation | Key Recommendations |
|---|---|---|
| Adult CHD | ESC (European) | Intervention if BP Gradient >20mmHg. Stenting preferred in adults. |
| Coarctation | AHA / ACC | Screening for intracranial aneurysms in adults. |
Landmark Evidence
1. COA Stenting
- The COAST trials demonstrated the safety and efficacy of covered stents for CoA, showing superiority over simple balloon angioplasty in reducing aneurysm formation.
What is Coarctation?
It is a birth defect where the main artery leaving the heart (Aorta) is pinched or narrowed, like a kink in a garden hose.
What are the symptoms?
In babies, it can cause sudden collapse. In adults, the heart has to pump hard against the kink, causing very high blood pressure in the arms and head, but low pressure in the legs.
How is it treated?
- Babies: Major surgery to cut out the kink and sew the tube back together.
- Adults: Often treated with "keyhole" surgery through the groin, using a balloon to stretch the narrowing and a metal scaffold (stent) to keep it open.
Will I be cured?
The repair fixes the plumbing, but your blood pressure might stay high because your body is "used to" it. You may need tablets for life.
Primary Sources
- Baumgartner H, et al. 2020 ESC Guidelines for the management of adult congenital heart disease. Eur Heart J. 2021.
- Stout KK, et al. 2018 AHA/ACC Guideline for the Management of Adults With Congenital Heart Disease. Circulation. 2019.
- Torella F, et al. Coarctation of the aorta in adults. Br J Surg. 2002.
Common Exam Questions
- Diagnosis: "Systolic murmur over the back?"
- Answer: Coarctation.
- Sign: "Radio-Radial Delay?"
- Answer: Coarctation occurring between the origin of the Right and Left subclavian arteries (distal to right, proximal to left).
- X-Ray: "Rib notching ribs 3-8?"
- Answer: Collateral flow via intercostals.
- Association: "Female with short stature?"
- Answer: Turner Syndrome. (Check Karyotype).
Viva Points
- Post-Coarctation Syndrome: Abdominal pain and distension post-repair. Caused by sudden restoration of high-pressure flow to the mesenteric arteries -> Arteritis / Gut Ischaemia.
- Why Ribs 3-8?: 1st/2nd intercostals feed from the Supreme Intercostal Artery (from Subclavian, high pressure). Lower ribs feed from distal aorta. Only the middle ribs form the bridge.
Medical Disclaimer: MedVellum content is for educational purposes and clinical reference. Clinical decisions should account for individual patient circumstances. Always consult appropriate specialists.