A 52-year-old man presents to the emergency department with acute onset chest pain radiating to the back, severe hypertension (180/110 mmHg), and a blood pressure differential of 20 mmHg between the two arms. Chest X-ray shows a widened mediastinum. What is the most appropriate immediate next step in management?

Explanation

## Clinical Context A widened mediastinum on chest X-ray in a patient with acute severe chest pain radiating to the back, hypertension, and blood pressure differential between arms is a classic presentation of **acute aortic dissection**. The mediastinum contains the thoracic aorta and its branches; dissection causes mediastinal widening and is a life-threatening emergency. ## Why CTA Chest Is the Best Next Step **Key Point:** CT angiography (CTA) is the gold-standard imaging modality for suspected acute aortic dissection because it: - Has high sensitivity (>95%) and specificity (>95%) for detecting dissection flaps - Can be performed rapidly (within minutes) in the emergency setting - Allows assessment of dissection extent, involvement of branch vessels, and complications (tamponade, aortic rupture) - Guides urgent surgical or endovascular intervention **High-Yield:** The mediastinum is divided into superior, anterior, middle, and posterior compartments. The thoracic aorta (ascending, arch, and descending portions) occupies the superior and posterior mediastinum. Dissection of the aorta is a surgical emergency requiring immediate imaging and intervention. **Clinical Pearl:** Blood pressure differential ≥20 mmHg between arms and pulse deficits are highly specific for aortic dissection and warrant emergent CTA. ## Management Algorithm ```mermaid flowchart TD A["Acute chest pain + widened mediastinum + BP differential"]:::outcome --> B{"Aortic dissection suspected?"}:::decision B -->|Yes| C["Stat CTA chest with IV contrast"]:::action C --> D{"Dissection confirmed?"}:::decision D -->|Type A| E["Emergent cardiothoracic surgery"]:::urgent D -->|Type B| F["Medical management + endovascular repair if indicated"]:::action B -->|No| G["Consider other diagnoses: MI, PE, pulmonary rupture"]:::outcome ``` ## Why Other Options Are Incorrect - **Echocardiography:** While useful for assessing cardiac complications of dissection (aortic regurgitation, pericardial effusion), it is not the primary diagnostic tool and delays definitive imaging. - **Chest MRI:** Excellent for detailed imaging but takes 30–60 minutes; contraindicated in unstable patients and those with metallic implants. CTA is faster and more practical in acute settings. - **Antithrombotic therapy + observation:** Dangerous; anticoagulation in acute aortic dissection can precipitate rupture and tamponade. Imaging must precede any anticoagulation.