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Difficulty: MediumInterpreting Imaging Results

A 62-year-old man presents to the emergency department with sudden-onset, severe "tearing" chest pain that radiates to his back between the shoulder blades. His medical history is significant for poorly controlled hypertension and hyperlipidemia. On presentation, he is diaphoretic and appears in distress. 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, pulse is 112/min, and respirations are 22/min. Oxygen saturation is 96% on room air. Cardiac examination reveals a regular tachycardia without murmurs, rubs, or gallops. Lungs are clear to auscultation bilaterally. Pulses are symmetric and 2+ in all four extremities. Electrocardiography shows sinus tachycardia with evidence of left ventricular hypertrophy, but no acute ischemic changes. A chest radiograph demonstrates a widened mediastinum. Computed tomography angiography (CTA) of the chest and abdomen is immediately performed. The radiologist reports a double-lumen appearance with an intimal flap originating 2 cm distal to the left subclavian artery and extending into the proximal abdominal aorta. The ascending aorta and aortic arch have a normal caliber and appearance. The false lumen is patent, and both renal arteries and the superior mesenteric artery enhance normally from the true lumen. Which of the following is the most appropriate next step in management?

  1. Intravenous labetalol infusionAnswer
  2. B
    Immediate open surgical aortic replacement
  3. C
    Thoracic endovascular aortic repair
  4. D
    Intravenous heparin infusion
  5. E
    Transesophageal echocardiography

Answer

Intravenous labetalol infusion
The correct answer is intravenous labetalol infusion. The patient's computed tomography angiography (CTA) reveals an aortic dissection originating distal to the left subclavian artery without involvement of the ascending aorta. This anatomical distribution, as interpreted from the imaging results, classifies the condition as a Stanford Type B aortic dissection. The primary initial management for an uncomplicated Type B aortic dissection is aggressive medical therapy to reduce heart rate, blood pressure, and left ventricular contractility, thereby minimizing aortic wall shear stress. An intravenous beta-blocker, such as labetalol or esmolol, is the first-line agent. The CTA also explicitly notes normal enhancement of the renal and superior mesenteric arteries with a patent false lumen, confirming there is no malperfusion syndrome that would necessitate urgent surgical or endovascular intervention.

Step-by-Step Solution

1
Interpret the provided computed tomography angiography (CTA) findings.
The CTA describes an intimal flap originating distal to the left subclavian artery with a normal ascending aorta.
Accurate anatomical localization of the intimal tear is required to correctly classify the aortic dissection.
2
Classify the aortic dissection based on the interpreted imaging.
The findings represent a Stanford Type B aortic dissection.
The Stanford classification dictates management: Type A involves the ascending aorta, while Type B involves only the descending aorta.
3
Determine the most appropriate initial management for the classified condition.
The patient requires immediate medical therapy with an intravenous beta-blocker, such as labetalol.
Medical management is the standard of care for uncomplicated Type B dissections to reduce heart rate, blood pressure, and aortic wall shear stress.

Key Concept

Uncomplicated Stanford Type B aortic dissections, characterized on imaging by involvement of only the descending aorta without malperfusion, are primarily managed with medical therapy (intravenous beta-blockers) rather than surgery.
Estimated Time:1m 30s
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Interpreting Imaging Results

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