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Difficulty: MediumPediatric Cardiovascular Disorders

During a routine health maintenance visit, a 9-year-old male is evaluated by a new family physician. His parents mention that he frequently stops to rest while playing outdoors with friends, complaining that his legs ache and feel weak. He has no history of significant illnesses and takes no daily medications. His vital signs show a temperature of 36.8°C (98.2°F), a heart rate of 82/min, and a respiratory rate of 18/min. Measurement of his blood pressure yields 146/92 mm Hg in the right upper extremity and 144/90 mm Hg in the left upper extremity. Upon further examination, simultaneous palpation reveals that his femoral pulses are significantly diminished in amplitude and temporally delayed compared to his brachial pulses. Auscultation of the heart demonstrates a regular rhythm without extra heart sounds, but a grade 2/6 systolic ejection murmur is audible over the left interscapular region. Which of the following findings is most likely to be present on further evaluation of this patient?

  1. Erosion of the inferior margins of the posterior ribs on a chest radiographAnswer
  2. B
    A right ventricular predominance with an upturned apex on a chest radiograph
  3. C
    A fixed and widely split second heart sound during the respiratory cycle
  4. D
    Erythema and subsequent desquamation of the skin on the palms and soles
  5. E
    Diffuse ST-segment elevation with PR-segment depression on an electrocardiogram

Answer

Erosion of the inferior margins of the posterior ribs on a chest radiograph
The patient's clinical presentation—upper extremity hypertension, claudication-like leg pain during exertion, and a marked radio-femoral pulse delay—is the classic triad for coarctation of the aorta in an older child. Coarctation is a congenital narrowing of the aorta, most commonly located just distal to the origin of the left subclavian artery. Because blood flow to the lower extremities is obstructed, the body compensates by developing collateral circulation over time. Blood bypasses the narrowed aortic segment by flowing through the internal thoracic (mammary) arteries and into the anterior intercostal arteries, which then anastomose with the posterior intercostal arteries to supply the descending aorta. The increased pressure and continuous, high-volume pulsatile flow through these collateral vessels cause the intercostal arteries to become markedly dilated and tortuous. By 5 to 8 years of age, the constant pulsation of these enlarged arteries erodes the adjacent bone along the costal groove, leading to the classic radiographic finding of inferior rib notching. The systolic murmur heard over the left interscapular region directly reflects turbulent blood flow across the narrowed segment of the aorta.

Step-by-Step Solution

1
Analyze the patient's symptoms and vital signs.
The 9-year-old boy presents with leg claudication, upper extremity hypertension (146/92 mm Hg), and normal heart and respiratory rates.
Identifying the pattern of hypertension in a pediatric patient is critical for narrowing the differential diagnosis.
2
Evaluate the physical examination findings.
There is a significant radio-femoral pulse delay, diminished femoral pulses, and a systolic murmur heard over the left interscapular region.
These specific signs indicate an anatomical obstruction to blood flow distal to the origin of the upper extremity vessels.
3
Synthesize the findings to establish a diagnosis.
The combination of upper extremity hypertension, radio-femoral delay, claudication, and a posterior systolic murmur confirms the diagnosis of coarctation of the aorta.
Coarctation of the aorta is a congenital narrowing of the descending aorta that restricts blood flow to the lower body.
4
Determine the expected downstream clinical or radiological manifestations of this condition in an older child.
To bypass the obstruction, collateral blood flow develops through the internal thoracic and intercostal arteries. The dilated, tortuous intercostal arteries pulsate against the ribs, causing inferior rib notching visible on a chest radiograph.
Rib notching is a classic radiographic sign of established coarctation of the aorta, typically appearing after 5 years of age.

Key Concept

Coarctation of the Aorta Pathophysiology and Manifestations
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Topics

Pediatric Cardiovascular Disorders

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