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Difficulty: HardDiagnostic Workup and Test Sequencing

A 62-year-old man is brought to the emergency department via ambulance due to the sudden onset of severe, tearing chest pain that radiates to his intrascapular region. His wife reports the pain began abruptly 45 minutes ago while he was watching television. His past medical history is significant for poorly controlled hypertension and tobacco use. On arrival, he appears ashen, diaphoretic, and lethargic. His temperature is 36.8°C (98.2°F), blood pressure is 82/50 mmHg in the right arm and 74/46 mmHg in the left arm, pulse is 122/min, and respirations are 22/min. Physical examination reveals a new early diastolic decrescendo murmur heard best at the right upper sternal border. Radial pulses are diminished bilaterally, more pronounced on the left. An electrocardiogram shows sinus tachycardia with non-specific ST-segment and T-wave changes. A portable bedside chest radiograph reveals a widened mediastinum. Which of the following is the most appropriate next step in the diagnostic workup?

  1. Transesophageal echocardiographyAnswer
  2. B
    Computed tomography angiography of the chest and abdomen
  3. C
    Transthoracic echocardiography
  4. D
    Invasive coronary angiography
  5. E
    Measurement of serum D-dimer level

Answer

Transesophageal echocardiography is the most appropriate next diagnostic step.
The patient's presentation is pathognomonic for an acute Type A aortic dissection. Because he is hemodynamically unstable (hypotensive, tachycardic, and lethargic), he cannot safely be transported to the radiology department. Bedside transesophageal echocardiography (TEE) is the most appropriate next step because it has near 100% sensitivity and specificity for detecting ascending aortic dissections, can identify critical complications requiring immediate surgical intervention (e.g., pericardial tamponade, acute severe aortic regurgitation), and allows the patient to remain in the emergency department resuscitation bay.

Step-by-Step Solution

1
Analyze the clinical presentation and physical examination findings.
The patient has tearing chest pain radiating to the back, asymmetric blood pressures, a new diastolic murmur (aortic regurgitation), and a widened mediastinum on chest radiograph.
These findings are highly specific for an acute Type A (ascending) thoracic aortic dissection.
2
Assess the patient's hemodynamic status.
The patient is in shock, evidenced by hypotension (82/50 mmHg), tachycardia (122/min), diaphoresis, and lethargy.
Hemodynamic stability dictates the choice and location of the subsequent diagnostic imaging modality.
3
Select the appropriate diagnostic test based on the patient's stability.
Bedside transesophageal echocardiography is selected over computed tomography (CT) angiography.
While CT angiography is the gold standard for stable patients, transporting an unstable patient in extremis to the scanner risks death. TEE can be performed rapidly at the bedside and has excellent sensitivity and specificity for identifying the dissection flap, pericardial tamponade, and valvular competence.

Key Concept

In hemodynamically unstable patients with high clinical suspicion for an acute thoracic aortic dissection, bedside transesophageal echocardiography is the diagnostic test of choice to avoid the risks associated with patient transport.
Estimated Time:1m 30s
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Diagnostic Workup and Test Sequencing

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