A newborn's physical assessment reveals absent femoral pulses and increased blood pressure in the upper extremities. This finding is most indicative of which condition?

1. A

   Patent ductus arteriosus

2. B

   Aortic stenosis

3. C

   Coarctation of aorta

4. D

   Ventricular septal defect

Appeared in: NORCET-7 Mains-2024

Explanation

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• Coarctation of the aorta is a congenital narrowing of the aorta, creating an obstruction to blood flow.
• This obstruction leads to increased pressure in the arteries proximal to the defect (supplying the arms and head), causing upper extremity hypertension.
• Simultaneously, blood flow is restricted to the arteries distal to the defect (supplying the legs), resulting in hypotension and weak or absent femoral pulses.
• This pressure and pulse differential between the upper and lower body is the key diagnostic feature of this condition.

Why Other Options Were Wrong

• Option A: Patent ductus arteriosus (PDA) is a connection between the aorta and pulmonary artery. It causes a left-to-right shunt, leading to bounding pulses in all extremities and a 'machinery-like' murmur, not a pressure discrepancy between upper and lower limbs.
• Option B: Aortic stenosis is a narrowing of the aortic valve itself. This obstructs blood flow from the left ventricle to the entire body, resulting in weak and delayed pulses (pulsus parvus et tardus) in all extremities, not a difference between arms and legs.
• Option D: A ventricular septal defect (VSD) is a hole in the wall separating the two ventricles. It causes a left-to-right shunt, typically presenting with a harsh holosystolic murmur and, if large, signs of heart failure. It does not cause a pulse or blood pressure differential between the upper and lower body.

Related Visual

Clinical Relevance

• Nursing practice connection: Use the key finding related to Clinical assessment and identification of acyanotic congenital heart defects in a newborn to guide bedside assessment, documentation, and the next nursing action.
• The four-extremity blood pressure measurement is a critical nursing assessment for all newborns, especially if a heart murmur is detected or perfusion is poor. A significant gradient (upper extremity systolic BP greater than lower extremity) is a red flag for coarctation.
• Failure to diagnose coarctation in the neonatal period can lead to rapid deterioration, shock, and severe acidosis once the ductus arteriosus closes, as it may be the only source of blood flow to the lower body.
• What if? If the newborn had weak pulses in all four extremities and was hypotensive, the differential diagnosis would shift towards conditions causing global low cardiac output, such as critical aortic stenosis, hypoplastic left heart syndrome, or sepsis, rather than coarctation.

How to Approach the Question

• First, identify the key clinical signs presented in the question: 1) absent femoral pulses and 2) increased blood pressure in the upper extremities.
• Recognize this combination as a discrepancy in perfusion between the upper and lower body.
• Consider the pathophysiology of each option. Ask yourself: 'Which of these defects would cause an obstruction that affects the lower body more than the upper body?'
• Analyze the options: PDA, VSD, and Aortic Stenosis affect the entire systemic circulation or create shunts that don't typically cause this specific pressure differential.
• Conclude that a narrowing of the aorta itself (coarctation) after the branches to the arms is the only plausible explanation for the observed signs.
• Select the option that matches this pathophysiological reasoning.

Concept Tested & Keywords

• Concept Tested: Clinical assessment and identification of acyanotic congenital heart defects in a newborn.
• Stem keywords: newborn, physical assessment, absent femoral pulses, increased blood pressure, upper extremities
• Lead-in keywords: most indicative of
• Clinical cues: The combination of absent femoral pulses and high upper extremity BP is a classic, pathognomonic finding.

Question ID

QY1C1T_IgkpX36HKA7D3C

Copy ID

Reference Book

E6 Pathology- ROBBINS & COTRAN PATHOLOGIC BASIS OF DISEASE 10TH Ed pp. 544-546, 541-543

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