Table 1. Optimal Velocity Threshold Criteria for Varying Severity
of ISR After CAS
ISR, % diameter reduction Velocity criteria
≥20 PSV ≥150 cm/s and ICA/CCA ratio ≥2.15
≥50 PSV ≥220 cm/s and ICA/CCA ratio ≥2.7
≥80 PSV ≥340 cm/s and ICA/CCA ratio ≥4.15
A PSV threshold of ≥300 cm/s was used to identify ≥70% stenosis in the Carotid
Revascularization Endarterectomy versus Stenting Trial (CREST).
Adapted from Lal BK, Hobson RW 2nd, Goldstein J, Chakhtoura EY, Duran WN. Carotid artery
stenting : is there a need to revise ultrasound velocity criteria? J Vasc Surg. 2004;39:58-66; and Lal BK,
Hobson RW 2nd, Tofighi B, Kapadia I, Cuadra S, Jamil Z. Duplex ultrasound velocity criteria for the
stented carotid artery. J Vasc Surg. 2007;47:63-73.
Thoracic and Abdominal Aorta
➤ The SVS recommends contrast-enhanced CT scanning at 1 month and
12 months and then annually after thoracic endovascular aortic repair
(TEVAR) for thoracic aortic aneurysm. If the 1-month CT scan detects an
abnormality, a repeated CT scan at 6 months should be considered. (1-B)
➤ The SVS recommends contrast-enhanced CT scanning at 1 month, 6
months, and 12 months and then annually after TEVAR for thoracic aortic
dissection. (1-B)
➤ The SVS recommends contrast-enhanced CT scanning at 1 month and
12 months and then annually after TEVAR for blunt thoracic aortic injury.
If the 1-month CT scan detects an abnormality, a repeated CT scan at
6 months should be considered. Future studies may provide data to
support longer surveillance intervals after TEVAR for traumatic injury
once a stable clinical pattern is established. (1-B)
➤ The SVS recommends CT scanning with or without contrast enhancement at
5-year intervals after open surgical repair for thoracic aortic disease. (1-C)
➤ The SVS recommends contrast-enhanced CT scanning at 1 month and 12
months after endovascular aneurysm repair (EVAR), with consideration of
more frequent imaging if an endoleak or other abnormality of concern is
detected at 1 month. (1-B)
➤ The SVS recommends DUS at 12-month intervals as alternative imaging
surveillance after EVAR if no endoleak or sac enlargement was detected
during the first year. (1-B)
Diagnosis
