Rapid Review·Cardiovascular
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PATHOLOGY
T2High yieldCoarctation of the Aorta & PPHN
FA P302
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Focus on
The aortic narrowing with upper-limb hypertension, and the newborn whose lungs never opened.
Key takeaways
Coarctation of the aorta
What it is
narrowing of the aorta (a thickened tunica media) near the insertion of the ductus arteriosus, i.e. juxtaductal. Associated with a bicuspid aortic valve, other cardiac defects, and Turner syndrome.Findings
hypertension in the upper extremities with low pressure in the legs, plus cyanosis, claudication, coolness, and weak, delayed lower-limb pulses (brachiofemoral delay). In a neonate it can show as differential cyanosis.Rib notching
with age the intercostal arteries enlarge as collaterals (internal thoracic to intercostal), and the enlarged vessels erode the ribs, producing rib notching on x-ray. The retrograde intercostal flow can also be heard as a continuous murmur in the interscapular area and left infraclavicular region.Complications
heart failure, cerebral hemorrhage from berry aneurysms, aortic rupture, and infective endocarditis.Persistent pulmonary hypertension of the newborn
PPHN
pulmonary vascular resistance stays high after birth, because the pulmonary vasculature developed or adapted abnormally, so blood shunts right to left through the foramen ovale and ductus arteriosus, bypassing the lungs.Risk factors
meconium-stained amniotic fluid aspiration, neonatal pneumonia, and neonatal respiratory distress syndrome.Findings
respiratory distress (tachypnea) and often differential cyanosis. Preductal oxygen saturation exceeds postductal, but the pulses are equal with no delay, which is what separates it from coarctation.| Feature | Coarctation of the aorta | PPHN |
|---|---|---|
| Mechanism | Anatomic narrowing near the ductus | Pulmonary vascular resistance stays high |
| Pulses | Weak and delayed in the legs (brachiofemoral delay) | Equal, with no delay |
| Blood pressure | Raised in the upper extremities | Not differential |
| Risk factors | Turner syndrome, bicuspid aortic valve | Meconium aspiration, neonatal pneumonia, post-term |
| X-ray | Rib notching from collaterals | Non-specific |
A newborn has differential cyanosis. Which single examination finding decides between coarctation and PPHN?
The femoral pulse: weak and delayed in coarctation, strong and equal in PPHN.
How it's tested
Rib notching on chest x-ray means coarctation, because the intercostal arteries have enlarged into collaterals around the narrowing, and that finding takes years to develop so it points to an older child or adult. Mehlman's warning is worth heeding: students expect Turner syndrome in every coarctation vignette, but it appears idiopathically just as often, and the tell may be as subtle as the stem noting that the radial pulses are brisk. Against PPHN, the discriminator is the pulses, which are equal in PPHN and delayed in the legs in coarctation.
Go deeper
First Aid 2026 — CV/Pathology (p.302) · B&B — Coarctation · Mehlman — HY Cardio (coarctation without Turner, rib notching, differential cyanosis)
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