A 19-year-old man is found to have a blood pressure of 168/98 mmHg in both arms during a college health check. Popliteal blood pressure is 126/76 mmHg, femoral pulses are weakly felt, and there is radiofemoral delay. Which single investigation is most likely to establish the diagnosis?
- A Renal artery Doppler ultrasonography
- B Transthoracic echocardiography ✓
- C Plasma free metanephrines
- D Overnight dexamethasone suppression test
Correct answer: B. Transthoracic echocardiography
Explanation
Upper extremity hypertension with an arm-to-leg gradient, weak femoral pulses and radiofemoral delay is the classic presentation of aortic coarctation. Transthoracic echocardiography demonstrates the juxtaductal narrowing and collateral flow and is the recommended first-line test. Plasma metanephrines would screen for pheochromocytoma, which causes paroxysmal systemic hypertension but never produces a differential between arm and leg pressures or delayed femoral pulses.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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