Clinical Scenario:
A 7-day-old term male neonate was apparently well after birth but develops poor feeding, tachypnea, lethargy, and progressively worsening peripheral perfusion. On examination, the right brachial pulse is easily palpable, whereas both femoral pulses are markedly weak and delayed. The right arm blood pressure is 78/48 mmHg, while the lower-limb blood pressure is considerably lower. There is mild hepatomegaly and no significant cardiac murmur.
Which of the following is the most likely diagnosis?
A. Critical pulmonary stenosis
B. Coarctation of the aorta
C. Hypoplastic left heart syndrome
D. Interrupted aortic arch
E. Total anomalous pulmonary venous connection
Correct answer & Explanation:
Answer: B. Coarctation of the aorta
Why B is the best answer
The strongest clue is:
Upper-limb pulses preserved + markedly weak/delayed femoral pulses = obstruction to blood flow between the upper- and lower-body arterial circulations.
In severe neonatal coarctation, systemic blood flow to the descending aorta can become duct-dependent. As the ductus arteriosus constricts during the first days of life, perfusion of the lower body deteriorates, producing:
- weak/absent femoral pulses
- radiofemoral delay
- lower blood pressure in the legs
- metabolic acidosis
- renal hypoperfusion
- heart failure/shock
One important exam distinction
Coarctation:
Weak/absent femoral pulses with relatively preserved upper-limb pulses is the classic bedside clue.
Interrupted aortic arch:
Can also cause duct-dependent systemic circulation, but is generally a more severe neonatal lesion and is frequently associated with a VSD and other cardiac anomalies. Clinical differentiation can be difficult, and echocardiography is required for confirmation.
Immediate management
If a neonate is critically ill with suspected duct-dependent systemic blood flow, the immediate treatment is:
→ Start PGE₁ (alprostadil) to maintain/reopen ductal patency.
This should be followed by urgent echocardiographic assessment and definitive intervention.
