A 68-year-old man with hypertension and smoking history presents with a 2-week history of transient monocular vision loss in the left eye described as "a curtain coming down." Carotid Doppler ultrasound is performed. The structure marked **D** in the diagram shows an elevated peak systolic velocity of 240 cm/s in the internal carotid artery with an end-diastolic velocity of 110 cm/s and an ICA/CCA PSV ratio of 4.5. According to Society of Radiologists in Ultrasound (SRU) 2003 consensus criteria, what degree of stenosis is indicated by these Doppler parameters, and what is the most appropriate management?

Explanation

## Why Option 1 is correct The Doppler parameters shown at **D** — peak systolic velocity (PSV) > 230 cm/s (240 cm/s here), end-diastolic velocity (EDV) > 100 cm/s (110 cm/s), and ICA/CCA PSV ratio > 4 (4.5) — meet the SRU 2003 consensus criteria for SEVERE (70-99%) carotid stenosis. The patient is SYMPTOMATIC with amaurosis fugax (transient monocular vision loss from retinal artery embolism originating from the carotid plaque), which is a cardinal presentation of hemodynamically significant carotid disease. Per NASCET and ECST trials, symptomatic patients with 70-99% stenosis have a STRONG INDICATION for carotid endarterectomy (CEA) or carotid artery stenting (CAS) within 14 days of symptom onset, with a 50% relative reduction in ipsilateral stroke risk. The timing is critical: early intervention prevents recurrent embolic events. ## Why each distractor is wrong - **Option 2**: Misclassifies the stenosis degree. PSV > 230 cm/s defines SEVERE stenosis (70-99%), not moderate (50-69%, which requires PSV 125-230 cm/s). A symptomatic patient with severe stenosis cannot be managed with medical therapy alone; intervention is mandated. - **Option 3**: Correctly identifies severe stenosis but applies asymptomatic management criteria. This patient is SYMPTOMATIC (amaurosis fugax), not asymptomatic. Symptomatic severe stenosis requires urgent intervention (CEA/CAS within 14 days), not deferral. Deferral and medical therapy alone apply only to asymptomatic patients with > 70% stenosis and life expectancy > 5 years. - **Option 4**: Misclassifies stenosis as moderate and incorrectly states CAS is contraindicated in symptomatic disease. CAS is an acceptable alternative to CEA in symptomatic patients, particularly those at high surgical risk. The CREST trial showed similar 4-year outcomes for CEA vs CAS in symptomatic disease. **High-Yield:** PSV > 230 cm/s + EDV > 100 cm/s + ICA/CCA ratio > 4 = SEVERE (70-99%) stenosis by SRU criteria; symptomatic severe stenosis = CEA/CAS within 14 days (NASCET/ECST evidence); amaurosis fugax = embolic symptom from carotid plaque requiring urgent intervention. [cite: Bailey & Love 28e Ch 53; Harrison 21e Ch 426; Society of Radiologists in Ultrasound 2003 Carotid Duplex Consensus; NASCET, ECST trials]