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Difficulty: EasyFormulating a Differential Diagnosis

A 58-year-old man with a history of poorly controlled hypertension presents to the emergency department with a sudden onset of severe, "tearing" chest pain that radiates to his back between his shoulder blades. He is diaphoretic and visibly anxious. Vital signs show a blood pressure of 190/110 mm Hg in his right arm and 150/90 mm Hg in his left arm, a heart rate of 115/min, and a respiratory rate of 22/min. Cardiac auscultation reveals a new diastolic decrescendo murmur at the right upper sternal border. An electrocardiogram shows sinus tachycardia with no ST-segment or T-wave abnormalities. A chest radiograph demonstrates a widened mediastinum. Which of the following is the most likely diagnosis?

  1. Acute aortic dissectionAnswer
  2. B
    Acute myocardial infarction
  3. C
    Acute pericarditis
  4. D
    Pulmonary embolism
  5. E
    Esophageal perforation

Answer

Acute aortic dissection
The correct answer is acute aortic dissection. This patient presents with the classic triad of a thoracic aortic dissection: sudden onset of tearing chest or back pain, a pulse deficit or blood pressure differential between the upper extremities, and a widened mediastinum on chest radiograph. The new diastolic murmur indicates aortic root involvement leading to acute aortic regurgitation. This is a "must-not-miss" diagnosis that requires immediate surgical or medical intervention depending on the anatomical classification (Stanford Type A vs. Type B).

Step-by-Step Solution

1
Analyze the characteristics of the patient's chest pain.
The pain is sudden, "tearing" in quality, and radiates to the back, which is highly suspicious for a vascular etiology rather than an ischemic or pulmonary one.
Characterizing the chest pain is the first step in differentiating between life-threatening causes of chest pain.
2
Evaluate the physical examination findings.
There is a significant blood pressure discrepancy between the arms (greater than 20 mm Hg systolic difference) and a new diastolic decrescendo murmur.
These findings suggest altered blood flow in the aortic arch branches (subclavian artery compromise) and acute aortic valve regurgitation, pointing to a proximal aortic dissection.
3
Interpret the diagnostic tests in the context of the clinical presentation.
The electrocardiogram is negative for acute ischemia, and the chest radiograph shows a widened mediastinum.
A widened mediastinum confirms the presence of an expanding vascular structure in the chest, definitively making acute aortic dissection the most likely diagnosis.

Key Concept

The classic presentation of acute aortic dissection includes sudden onset tearing chest pain radiating to the back, asymmetric blood pressures, and a widened mediastinum on chest radiograph.
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Topics

Formulating a Differential Diagnosis

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