A 71-year-old man with hypertension, diabetes, and dyslipidaemia presents with a history of transient right-sided weakness and slurred speech. Carotid duplex ultrasound shows a heavily calcified, ulcerated plaque at the left internal carotid artery with marked luminal narrowing and post-stenotic colour-flow aliasing. Spectral Doppler interrogation reveals the measurement marked **C** in the diagram. Which of the following best describes the clinical significance of this finding?
A. Peak systolic velocity >230 cm/s indicates >70% stenosis by NASCET criteria and warrants urgent carotid endarterectomy in symptomatic patients
B. Peak systolic velocity >230 cm/s indicates <50% stenosis and can be managed with medical therapy alone without intervention
C. Peak systolic velocity >230 cm/s indicates occlusion of the internal carotid artery and is a contraindication to endarterectomy
D. Peak systolic velocity >230 cm/s indicates 50-69% stenosis and requires close surveillance with repeat ultrasound every 3 months
Explanation
Why Peak systolic velocity >230 cm/s indicates >70% stenosis by NASCET criteria and warrants urgent carotid endarterectomy in symptomatic patients is right
The Society of Radiologists in Ultrasound Consensus Conference established that a peak systolic velocity (PSV) >230 cm/s in the internal carotid artery (ICA) is the ultrasound criterion for >70% stenosis by NASCET angiographic criteria. In this symptomatic patient with a recent transient ischaemic stroke (TIA) and a PSV of 312 cm/s, this finding indicates haemodynamically significant stenosis that warrants urgent carotid endarterectomy within 2 weeks under best medical therapy, as supported by the NASCET trial and current stroke prevention guidelines. The combination of a PSV >230 cm/s with an elevated ICA-to-CCA ratio (>4) and post-stenotic colour-flow aliasing all confirm severe stenosis.
Why each distractor is wrong
Peak systolic velocity >230 cm/s indicates 50-69% stenosis and requires close surveillance with repeat ultrasound every 3 months: This misrepresents the PSV threshold. A PSV of 130–230 cm/s corresponds to 50–69% stenosis; PSV >230 cm/s indicates >70% stenosis, which requires intervention in symptomatic patients, not surveillance alone.
Peak systolic velocity >230 cm/s indicates <50% stenosis and can be managed with medical therapy alone without intervention: This is incorrect; PSV <130 cm/s indicates <50% stenosis. A PSV >230 cm/s represents severe stenosis and is an indication for endarterectomy in symptomatic patients, not medical management alone.
Peak systolic velocity >230 cm/s indicates occlusion of the internal carotid artery and is a contraindication to endarterectomy: Complete occlusion would show absent or near-absent flow on spectral Doppler, not elevated PSV. A PSV >230 cm/s indicates severe but patent stenosis, which is an indication for endarterectomy in symptomatic patients.
High-YieldNEET PG
PSV >230 cm/s = >70% stenosis by NASCET; symptomatic >70% stenosis requires urgent endarterectomy (NNT ~6 over 2 years to prevent one stroke).
Society of Radiologists in Ultrasound Consensus Conference — Carotid Doppler Criteria
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