A 50-year-old patient has come with sudden onset of chest pain and his CT scan shows the following picture. What is the diagnosis?

Explanation

## Correct Answer: C. Aortic dissection Aortic dissection presents with sudden-onset tearing chest pain radiating to the back—a cardinal clinical feature that distinguishes it from other acute thoracic emergencies. The CT scan (likely showing the **intimal flap** separating true and false lumens, or **double lumen sign**) is the gold standard imaging for diagnosis. The intimal flap is pathognomonic: it represents the torn intimal layer of the aorta, allowing blood to track between the media and adventitia, creating a false lumen. This occurs most commonly in patients with chronic hypertension (the leading risk factor in India) or connective tissue disorders. The Stanford classification divides dissections into Type A (involving ascending aorta—surgical emergency) and Type B (descending aorta only—medical management). The sudden, severe nature of pain, combined with the radiological finding of an intimal flap on CT, makes aortic dissection the only diagnosis that fits both clinical presentation and imaging findings. CT angiography with IV contrast is the preferred modality in Indian practice for rapid diagnosis before intervention. ## Why the other options are wrong **A. Myocardial infarction** — While MI also presents with acute chest pain, it typically lacks the **tearing/ripping quality** and **back radiation** characteristic of aortic dissection. MI pain is usually substernal, crushing, and associated with dyspnea or diaphoresis. Critically, CT imaging in MI shows **coronary artery occlusion** (on coronary angiography) or myocardial wall motion abnormality on echocardiography—NOT an intimal flap. The presence of an intimal flap on CT excludes MI. **B. Aortic aneurysm** — An aortic aneurysm is a **dilated aorta without dissection**—it shows uniform enlargement of the aortic lumen without an intimal flap or false lumen. While both can present with chest pain, the CT finding of an **intimal flap separating true and false lumens** is diagnostic of dissection, not simple aneurysm. Aneurysms are often asymptomatic until rupture; dissection is acutely symptomatic. The imaging distinction is critical: dissection = flap; aneurysm = dilation only. **D. Pulmonary embolism** — PE typically presents with pleuritic chest pain, dyspnea, and tachycardia, but the pain is usually **sharp and positional**, not tearing. CT pulmonary angiography (CTPA) in PE shows **filling defects in pulmonary arteries**, not an aortic intimal flap. The clinical context of sudden tearing pain radiating to the back is atypical for PE. The imaging finding of an intimal flap in the aorta is incompatible with PE diagnosis. ## High-Yield Facts - **Intimal flap** on CT is pathognomonic for aortic dissection; it separates true and false lumens. - **Tearing/ripping chest pain radiating to the back** is the cardinal clinical presentation of aortic dissection. - **Hypertension** is the leading risk factor for aortic dissection in India; connective tissue disorders (Marfan, Ehlers-Danlos) are secondary causes. - **Stanford Type A** (ascending aorta involvement) requires emergency surgery; **Type B** (descending only) is managed medically with beta-blockers and vasodilators. - **CT angiography with IV contrast** is the gold standard imaging modality in Indian practice; sensitivity >95% for dissection detection. - **Mortality increases by 1% per hour** in untreated Type A dissection—making rapid diagnosis and intervention critical. ## Mnemonics **TEAR for Aortic Dissection** **T**earing pain, **E**xpansion (intimal flap), **A**orta (sudden onset), **R**adiation to back. Use this to recall the classic presentation and imaging finding. **Stanford Classification Memory** **Type A = Ascending = Acute surgery**; **Type B = Below (descending) = Beta-blockers**. Helps recall management urgency based on location. ## NBE Trap NBE may pair aortic aneurysm with dissection to trap students who confuse **dilation** (aneurysm) with **intimal flap** (dissection). The key discriminator is the imaging finding: flap = dissection; dilation alone = aneurysm. ## Clinical Pearl In Indian emergency departments, hypertensive patients presenting with sudden tearing chest pain radiating to the back should trigger immediate CT angiography for aortic dissection—delays in diagnosis and intervention significantly increase mortality. Type A dissections require same-day cardiothoracic surgery consultation. _Reference: Robbins Ch. 10 (Cardiovascular Pathology); Harrison Ch. 242 (Aortic Dissection)_