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Difficulty: MediumInterpreting Imaging Results

A 62-year-old man presents to the emergency department complaining of sudden-onset, severe, tearing pain between his shoulder blades that began 1 hour ago. He has a history of poorly controlled hypertension. His temperature is 37.1°C (98.8°F), blood pressure is 185/110 mm Hg in the right arm and 180/108 mm Hg in the left arm, heart rate is 112/min, and respiratory rate is 20/min. Physical examination reveals normal heart sounds with no murmurs, clear lungs, and equal pulses in all four extremities. An electrocardiogram reveals sinus tachycardia without ST-segment changes. A contrast-enhanced computed tomography (CT) scan of the chest is performed. The scan demonstrates an intimal flap separating a true and false lumen, which begins just distal to the origin of the left subclavian artery and extends into the descending thoracic aorta. The ascending aorta and aortic arch appear completely normal. Based on the interpretation of these imaging findings, which of the following is the most appropriate next step in management?

  1. Administration of intravenous labetalolAnswer
  2. B
    Urgent open surgical repair of the aorta
  3. C
    Administration of intravenous heparin
  4. D
    Transesophageal echocardiography
  5. E
    Discharge home with oral antihypertensives and outpatient follow-up

Answer

Administration of intravenous labetalol
The correct answer is the administration of intravenous labetalol because the patient has an acute Stanford Type B aortic dissection. The CT scan is crucial here: the intimal flap begins distal to the left subclavian artery, sparing the ascending aorta. For uncomplicated Type B dissections, medical management with intravenous beta-blockers is the standard of care to rapidly decrease left ventricular dP/dt (shear stress) and lower blood pressure.

Step-by-Step Solution

1
Analyze the clinical presentation
The patient has sudden, severe tearing back pain with severe hypertension.
This is a classic presentation for an acute aortic dissection.
2
Interpret the imaging findings provided in the vignette
The CT scan shows an intimal flap in the descending thoracic aorta, beginning distal to the left subclavian artery, with a normal ascending aorta and arch.
This anatomically classifies the dissection based on the Stanford system.
3
Classify the condition and determine the indicated management
The findings define a Stanford Type B aortic dissection. The management is medical, prioritizing strict heart rate and blood pressure control.
Type B dissections are managed medically unless complications (e.g., malperfusion, rupture) arise, whereas Type A dissections require surgical intervention. Intravenous beta-blockers (like labetalol) reduce shear stress on the aortic wall.

Key Concept

Interpretation of CT imaging to differentiate Stanford Type A versus Type B aortic dissection dictates the primary management strategy (surgical versus medical).
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Interpreting Imaging Results

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