Discrepancies in Carotid Stenosis Diagnosis

Critical Waveform Abnormalities

The presence of universal monophasic flow patterns in internal carotid arteries, carotid bifurcations, and mid common carotid arteries indicates hemodynamically significant proximal disease or cardiac dysfunction, according to the American Heart Association 1
Normal carotid arteries should demonstrate multiphasic (triphasic) waveforms, particularly in the common carotid and external carotid arteries, as recommended by the American College of Cardiology 1

Monophasic waveforms suggest severe proximal stenosis (aortic arch or innominate/subclavian disease) causing dampened flow distally, with a strength of evidence level of II, according to the American Heart Association 2, 3
Diffuse atherosclerotic disease more extensive than focal stenosis measurements suggest is indicated by monophasic waveforms, with a moderate level of evidence, according to the American College of Cardiology 2

A PSV of 167 cm/s at distal ICA suggests 50-69% stenosis by velocity criteria, with a high level of evidence, according to the Society of Radiologists in Ultrasound 2, 3
An ICA/CCA ratio of 1.81 is below the threshold of 2.0 for even 50% stenosis, indicating less than 50% stenosis, with a moderate level of evidence, according to the American Institute of Ultrasound in Medicine 2, 3

Contralateral disease can elevate velocities in the less-diseased artery through compensatory flow, with a low level of evidence, according to the American Heart Association 3
Cardiac output abnormalities may reduce all velocities, causing underestimation of stenosis severity, with a moderate level of evidence, according to the American College of Cardiology 3

The American Heart Association emphasizes that every vascular laboratory should have quality assurance programs comparing ultrasound findings with other imaging modalities, with a high level of evidence 5, 3
Correlation with additional imaging (CTA or MRA) is necessary to resolve discrepancies, with a moderate level of evidence, according to the American College of Radiology 2, 5

Arch vessel imaging (CTA or MRA) is recommended to identify proximal stenoses affecting all cervical vessels, with a high level of evidence, according to the American Heart Association 2, 5
Repeat duplex with cardiac gating is recommended if cardiac dysfunction is confirmed, with a moderate level of evidence, according to the American Institute of Ultrasound in Medicine 3

Hypertension, 2009

Circulation, 2011