Coarctation of the aorta is one of those “don’t-miss” congenital lesions because the physical exam basically gives you the diagnosis—especially when you know what to feel in the arms vs legs. Here’s a one-page, high-yield cheat sheet you can recall on rounds and on test day.
The One-Liner (burn this in)
Coarctation of the aorta = “Upper body HTN + lower body hypoperfusion” → high arm BP, weak/delayed femoral pulses, and rib notching from collateral vessels.
Where is the narrowing?
Classic location
- Juxtaductal coarctation: near the ductus arteriosus insertion (aortic isthmus), typically distal to the left subclavian artery
Two testable phenotypes
| Type | Relationship to ductus arteriosus | Classic presentation |
|---|---|---|
| Preductal (infantile) | Proximal to ductus | Neonatal shock when PDA closes (duct-dependent systemic flow) |
| Postductal (adult) | Distal to ductus | Upper extremity HTN, radiofemoral delay, rib notching |
Mnemonic + Visual (quick mental sketch)
Mnemonic: “HIGH ARMS, LOW LEGS”
- HIGH pressure in ARMS
- LOW pressure in LEGS
Visual device: “Pinched aorta = traffic jam”
Think of the aorta like a highway:
- Before the pinch (proximal): traffic backs up → HTN in upper extremities
- After the pinch (distal): not enough flow → cool legs, claudication, weak pulses
- Side roads open up (collaterals) → intercostal artery enlargement → rib notching
Core clinical picture (what you should say out loud on exams)
Vitals / BP findings
- Arm BP > leg BP (normally leg systolic is slightly higher than arm)
- Upper extremity HTN (headaches, epistaxis can show up)
Pulse exam
- Weak, delayed femoral pulses (radiofemoral delay)
- Lower extremities: cool, fatigue, claudication (older patients)
Auscultation
- Systolic murmur (often left infraclavicular/back)
- Can have a continuous murmur from collaterals
Imaging & classic associations
Chest X-ray (Step favorite)
- Rib notching (inferior rib erosions) from enlarged intercostal arteries
- “Figure 3 sign” (pre- and post-stenotic dilation around the coarctation)
Echo / MRI
- Echocardiography is common for diagnosis in kids
- MRI/CT angiography for anatomy, severity, planning repair
Pathophysiology in one paragraph
A narrowing near the ductus increases afterload proximal to the lesion → LV works harder → LVH and upper extremity HTN. Distal flow drops → renal hypoperfusion can further drive RAAS and worsen HTN. Over time, collateral circulation (subclavian → internal thoracic → intercostals) enlarges to supply the descending aorta, causing rib notching.
Neonatal emergency version (duct-dependent systemic circulation)
How it presents
When the PDA closes (hours–days after birth):
- Acute hypoperfusion/shock
- Metabolic acidosis
- Poor feeding, lethargy
- Weak/absent femoral pulses
High-yield management
- Prostaglandin E1 (alprostadil) to maintain/reopen PDA
- Buys time for definitive repair
- Stabilize (oxygen/ventilation as needed, correct acidosis, supportive care)
USMLE pearl: “Cyanotic? Think duct-dependent pulmonary flow.”
“Shock + weak femoral pulses after PDA closes? Think coarctation.”
Classic associations (buzzwords that get tested)
Turner syndrome
- Turner (45,XO) → Coarctation of aorta, bicuspid aortic valve
- Often described with webbed neck, shield chest, primary amenorrhea
Bicuspid aortic valve
- Frequently coexists
- Adds risk for:
- Aortic stenosis
- Aortic dilation/dissection (later)
Complications to know (Step 2 style)
- Chronic HTN (even after repair)
- Aortic rupture/dissection
- Infective endocarditis risk (especially with associated valve disease)
- Intracranial berry aneurysms due to longstanding HTN → SAH risk
- Heart failure (LV pressure overload)
Treatment overview (what’s actually done)
Definitive repair options
- Surgical repair (resection with end-to-end anastomosis, etc.)
- Balloon angioplasty ± stenting (more common in older kids/adults depending on anatomy)
After repair
- Monitor for:
- Re-coarctation
- Persistent HTN
- Aortic aneurysm at repair site
Rapid-fire USMLE checkpoints (if you remember nothing else)
- Arm BP > leg BP + radiofemoral delay = coarctation until proven otherwise
- Rib notching = enlarged intercostal collaterals (postductal pattern)
- Neonate decompensates when PDA closes → give PGE1
- Strong association with Turner syndrome and bicuspid aortic valve
- Complication tie-in: berry aneurysms/SAH from chronic HTN