A 1-month-old boy presents with failure to thrive. On examination, he shows features of congestive heart failure. The femoral pulses are feeble as compared to the brachial pulses. The most likely clinical diagnosis is?

1. A

   Congenital aortic stenosis

2. B

   Coarctation of aorta

3. C

   Patent ductus arteriosus

4. D

   Congenital aortoiliac disease

Appeared in: JODHPUR AIIMS SNO-2018

Explanation

• Coarctation of the Aorta (CoA) is a congenital narrowing of the aorta, which obstructs blood flow to the lower part of thebody.
• This obstruction leads to higher blood pressure and stronger pulses in the upper extremities (brachial) compared to lower blood pressure and weaker, delayed, or absent pulses in the lower extremities (femoral).
• The increased afterload on the left ventricle causes it to work harder, leading to hypertrophy and eventually congestive heart failure, which explains the infant's failure to thrive and signs of heart failure.
• This classic presentation of differential pulses between the arms and legs is the hallmark of CoA in an infant.

Why Other Options Were Wrong

• Option A: Congenital aortic stenosis involves narrowing of the aortic valve itself. This obstructs outflow from the left ventricle to the entire body, resulting in globally weak pulses (weak in both arms and legs) and signs of low cardiac output.
• Option C: A large Patent Ductus Arteriosus (PDA) creates a left-to-right shunt, leading to pulmonary over-circulation and volume overload. This typically causes bounding, hyperdynamic pulses in all extremities due to a wide pulse pressure, not weak femoral pulses.
• Option D: Congenital aortoiliac disease is extremely rare in infancy. While it would affect lower limb pulses, it does not typically cause the upper limb hypertension seen in CoA and is not a common cause of infantile heart failure in this manner.

Related Visual

Clinical Relevance

• Nursing practice connection: Use the key finding related to Diagnosis of congenital heart defects based on clinical examination findings to guide bedside assessment, documentation, and the next nursing action.
• A four-limb pulse and blood pressure assessment is a critical nursing skill. In any infant or child with unexplained hypertension, poor feeding, or signs of heart failure, checking for a discrepancy between upper and lower extremities is mandatory to rule out CoA.
• Early identification of CoA is vital. Untreated, it leads to severe hypertension, premature coronary artery disease, aortic dissection, and heart failure.
• What if? If the infant had strong brachial pulses but the left brachial pulse was weaker than the right, it would suggest the coarctation is located between the brachiocephalic artery and the left subclavian artery, involving the origin of the left subclavian.

How to Approach the Question

• First, identify the key patient demographics and presenting symptoms: a 1-month-old infant with failure to thrive and CHF.
• Next, search the clinical vignette for the most specific and differentiating sign. In this case, it is 'femoral pulses are feeble as compared to the brachial pulses'.
• Recognize this pulse discrepancy as a classic, pathognomonic finding.
• Correlate this finding with the pathophysiology of the options. The pulse difference is explained by a localized obstruction in the aorta after the arm vessels have branched off.
• Evaluate the options: CoA perfectly matches this pathophysiology. The other options (Aortic Stenosis, PDA) result in global pulse changes (all weak or all bounding), not a differential.
• Conclude that Coarctation of the Aorta is the only diagnosis that explains all the findings, especially the key pulse discrepancy.

Concept Tested & Keywords

• Concept Tested: Diagnosis of congenital heart defects based on clinical examination findings.
• Stem keywords: 1-month-old, failure to thrive, congestive heart failure, femoral pulses, brachial pulses
• Lead-in keywords: most likely clinical diagnosis
• Clinical cues: The discrepancy between upper and lower limb pulses is the pathognomonic sign pointing to the diagnosis.

Question ID

QLEnplH9EAtfbgLU3GC7r3

Copy ID

Reference Book

E6 Pathology- ROBBINS & COTRAN PATHOLOGIC BASIS OF DISEASE 10TH Ed p. 544-546

E6 Nelson Textbook of Pediatrics(2024) — Volume 2 p. 581-583