Correct Answer: A. Coarctation of aorta
Coarctation of the aorta (CoA) is a congenital narrowing of the descending thoracic aorta, classically presenting with hypertension in young patients. The chest radiograph shows the pathognomonic "3 sign" (or reversed "E" sign) — a combination of pre-stenotic aortic dilation, the narrowed segment, and post-stenotic dilation. The rib notching visible on the radiograph is caused by intercostal artery enlargement (collateral circulation bypassing the stenosis), which is virtually diagnostic of CoA. The clinical triad of hypertension, chest pain, and leg claudication (cramping) is classic: hypertension develops due to increased peripheral vascular resistance and activation of the renin-angiotensin system proximal to the stenosis; leg claudication occurs because blood flow to the lower extremities is compromised, especially during exercise. In Indian clinical practice, CoA is the most common cause of secondary hypertension in young women presenting with this constellation of findings. The diagnosis is confirmed by echocardiography or CT/MRI angiography showing the narrowed segment and collateral vessels. Early recognition is critical as untreated CoA leads to left ventricular hypertrophy, aortic rupture, and stroke.
Why the other options are wrong
B. Essential hypertension — Essential hypertension is a diagnosis of exclusion and does not explain the acute presentation with chest pain, leg claudication, or the characteristic radiographic findings (rib notching, 3-sign). In a 30-year-old woman with secondary hypertension signs, essential hypertension is premature and misses the underlying structural pathology. This is an NBE trap for students who default to 'essential' without analyzing the clinical context. C. Aortic aneurysm — While aortic aneurysm can cause chest pain and hypertension, it does NOT produce rib notching or the classic 3-sign on chest radiograph. Aneurysm presents with dilation throughout the affected segment, not a focal stenosis. Leg claudication is not typical of aneurysm; instead, acute aortic syndrome presents with sudden, tearing chest pain and hemodynamic collapse. The radiographic findings are incompatible with aneurysm. D. Aorta-arteritis — Takayasu arteritis (aorta-arteritis) can cause aortic narrowing and hypertension, but it typically presents with systemic inflammatory symptoms (fever, malaise, elevated ESR/CRP), affects multiple vessels, and is more common in young women in India. However, the acute presentation with leg claudication and the specific radiographic finding of rib notching due to intercostal collaterals is pathognomonic for CoA, not arteritis. Arteritis would show more diffuse involvement.
High-Yield Facts
- Rib notching on chest X-ray in a hypertensive young patient is virtually diagnostic of coarctation of aorta (due to enlarged intercostal arteries forming collaterals).
- 3-sign (or reversed E-sign) on CXR: pre-stenotic dilation + narrowed segment + post-stenotic dilation is the classic radiographic hallmark of CoA.
- Leg claudication in CoA occurs because blood flow to lower extremities is reduced; symptoms worsen with exercise due to inability to increase distal perfusion.
- Hypertension in CoA is caused by increased peripheral vascular resistance proximal to the stenosis and activation of the renin-angiotensin-aldosterone system.
- Echocardiography or CT/MRI angiography is the gold standard for confirming CoA and assessing the degree of narrowing and collateral circulation.
- Untreated CoA leads to left ventricular hypertrophy, aortic rupture, intracranial aneurysm (berry aneurysm association), and premature stroke.
Mnemonics
CoA Clinical Triad HCP — Hypertension (proximal), Claudication (legs), Chest pain. Remember: upper body hypertension with lower limb underperfusion is the hallmark. CXR Signs of CoA 3-RN — 3-sign (dilation-stenosis-dilation) + Rib Notching (intercostal collaterals). These two radiographic findings together are virtually pathognomonic.
NBE Trap
NBE pairs "hypertension in a young woman" with "essential hypertension" to trap students who skip the radiographic analysis. The key discriminator is the rib notching and 3-sign, which are specific to CoA and absent in primary hypertension.
Clinical Pearl
In Indian clinical practice, a young woman presenting with hypertension and leg claudication should always trigger a chest X-ray review for rib notching — this single finding can prevent years of unnecessary antihypertensive therapy and identify a surgically correctable lesion before complications like aortic rupture or stroke occur.
_Reference: Robbins Ch. 10 (Congenital Heart Disease); Harrison Ch. 236 (Aortic Diseases)_