R. Eugene Zierler, M.D. The D. E. Strandness, Jr. Vascular Laboratory University of Washington Medical Center Division of Vascular Surgery University of Washington, School of Medicine THE “OTHER” DUPLEX CRITERIA: Common Carotid, External Carotid, and Vertebral Arteries
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R. Eugene Zierler, M.D.
The D. E. Strandness, Jr. Vascular LaboratoryUniversity of Washington Medical Center
Division of Vascular SurgeryUniversity of Washington, School of Medicine
THE “OTHER” DUPLEX CRITERIA: Common Carotid, External Carotid,
and Vertebral Arteries
DISCLOSURE INFORMATION
No relevantfinancial or commercial
relationships to declare
R. Eugene Zierler, M.D.
Why Do We Need Them?THE OTHER CAROTID CRITERIA
Carotid criteria have always emphasized the internal carotid
Abnormalities of the common carotid, external carotid, and vertebral arteries can also be clinically significant
Examination of these “other” arteries is required by IAC Vascular Testing IAC Standards and Guidelines
for Vascular Testing 2018 (new content changes highlighted)
General Principles – Normal Flow PatternsTHE OTHER CAROTID CRITERIA
Common Carotid Low resistance
(high diastolic flow) 20% to 30% enters ECA 70% to 80% of flow enters ICA
Internal CarotidLow resistance
External CarotidHigh resistance
VertebralLow resistance
Change from multiphasic to damped monophasic waveform
PSV >182 cm/s for ≥50% area stenosis in the mid-distal CCA on CTA
Common Carotid Artery – Velocity Criteria
What About % area vs. % diameter stenosis?
50% area stenosis is only about 30% diameter stenosis
THE OTHER CAROTID CRITERIA
*Bluth et al. RadioGraphics 1988;8:487
Is 30% diameter stenosis “significant”?
Internal carotid (and most other) velocity criteria refer to % diameter reduction
*
Consistent with right ICA occlusion Right CCA - High resistance Left CCA – Normal flow pattern Right CCA flow pattern takes on
the characteristics of the ECA
LeftCCA
Right CCA
Right ECA
Common Carotid Artery – Interpretation PointsTHE OTHER CAROTID CRITERIA
Compare CCA Flow Patterns
Right Common Carotid
DampenedPSV 28 cm/s
Turbulent
Bidirectional flow
Innominate
Right Vertebral
Common Carotid Artery – Interpretation PointsTHE OTHER CAROTID CRITERIA
Innominate artery stenosis
Cardiac Effects “Pulsus Bisferiens” 52M with bioprosthetic aortic
valve Aortic stenosis/insufficiency Bilateral and symmetricalLeft
CCA
Right CCA
Common Carotid Artery – Interpretation PointsTHE OTHER CAROTID CRITERIA
External Carotid Artery – Interpretation Points No established velocity criteria (that I know of) Occlusive ECA disease is less significant than ICA disease Most important to distinguish between the ICA and ECA Anatomy: ICA posterior/medial; ECA anterior/lateral Anatomy: The ECA has branches Waveform: ICA “low resistance” with monophasic flow
ECA “high resistance” with multiphasic flowTemporal Tap
THE OTHER CAROTID CRITERIA
Bilateral ICA occlusion
Anatomically - look like ECAs The patent arteries have low resistance flow patterns
(ICA vs. “collateralized” ECA) Palpable temporal artery pulses
External Carotid Artery – Interpretation PointsTHE OTHER CAROTID CRITERIA
External Carotid Artery - Plaque 500 carotid duplex scans with
no plaque in the ICA or CCA 64 (12.8%) had plaque in one
or both ECAs Assessed mortality in those
with and without ECA plaque after adjusting for age, sex, BMI, LDL levels, smoking, hypertension, and diabetes
Median follow-up of 4.9 years
THE OTHER CAROTID CRITERIA
Kim et al. Vasc Med 2014;19:351
Plaque was defined as focal wall thickening of at least 50% greater
than adjacent vessel walls or a protruding focal CIMT >1.5 mm
External Carotid Artery - PlaqueTHE OTHER CAROTID CRITERIA
Kim et al. Vasc Med 2014;19:351
Adjusted hazard ratio of 2.60 for all-cause mortality in those with ECA plaque compared to those without ECA plaque (95% CI 1.46 to 4.66)
Presence of plaque isolated to the ECA is an independent predictor of all-cause mortality
May provide important prognostic information for patients having carotid duplex scans
External Carotid Artery – Collateral FlowTHE OTHER CAROTID CRITERIA
Anatomy is variable: Asymmetric (45% left dominant,
30% right dominant, 25% equal)
Variable origin (5% left from aortic arch)
Vertebral Artery – Interpretation Points
Normal low resistance waveform (like the ICA)
THE OTHER CAROTID CRITERIA
Abnormal high resistance waveformDistal stenosis or occlusionHypoplasiaTermination into the PICA
Vertebral Artery – Flow PatternsTHE OTHER CAROTID CRITERIA
Kim et al. J Ultrasound Med 2010;29:1161
Evaluated “high resistance” vertebral artery waveforms 79 duplex exams with correlative imaging 90 high resistance (HR) and 67 low resistance (LR) waveforms
NormalLow Resistance
AbnormalHigh Resistance
Vertebral Artery – Flow PatternsTHE OTHER CAROTID CRITERIA
Kim et al. J Ultrasound Med 2010;29:1161
90 high resistance (HR) and 67 low resistance (LR) waveforms
HR vertebral artery waveform was associated with vertebrobasilar disease or other abnormalities in 46% of cases and a “diminutive” vertebral artery in 35.6%
Vertebral Artery – Velocity Criteria 247 patients with symptoms of posterior circulation ischemia
and both duplex scans and digital subtraction arteriography Recorded PSV at the origin and intervertebral segments Optimal “cutoff” values:
Vertebral Artery – Velocity CriteriaTHE OTHER CAROTID CRITERIA
Koch et al. J Neuroimaging 2009;19:242
Evaluated PSV criteria for vertebral artery stenosis 386 vertebral arteries with duplex scans and arteriography 50-99% stenosis found in 36 (9%) PSV obtained at origin, proximal (V1), and intra-foraminal
creates a pressure gradient between the vertebral artery origins
Reverse flow in the ipsilateral vertebral (“hesitant”, bi-directional, reversed)
THE OTHER CAROTID CRITERIA
Partial Steal
Complete Steal
“Hesitant” Pattern Latent Steal
Vertebral Artery - StealTHE OTHER CAROTID CRITERIA
Labropoulos et al. Ann Surg 2010;252:156
514 (6.5%) of 7,881 patients referred for carotid duplex also had a brachial pressure gradient of >20 mmHg 82% were lower on the left side
Subclavian steal was defined as partial or completereversed flow in one or both vertebral arteries 61% Complete 23% Partial 16% Absent
Presence of complete steal increased with higher brachial pressure gradients
84%
Common Carotid Artery What I use
THE OTHER CAROTID CRITERIA
Diameter Reduction PSV or PSV Ratio B-mode Image
Findings
Normal PSV <≈125 cm/s No evidence of wall thickening or plaque
<50%PSV Ratio <2.0 orPSV <≈250 cm/s
Wall thickening or minimal plaque
≥50%PSV Ratio ≥2.0 or PSV ≥≈250 cm/s
Extensive plaque visualized
Total Occlusion No detectable Doppler flow in the CCA Plaque visualized
PSV thresholds should be considered as approximate (≈) CCA PSV Ratio = (PSV at stenotic site)/(PSV at normal proximal site) PSV Ratio most useful for focal lesions (and may not be valid for diffuse disease) Also look for focal velocity increase and post-stenotic turbulence with damping of
the distal flow waveform to identify a ≥50% stenosis
External Carotid Artery What I use
THE OTHER CAROTID CRITERIA
Diameter Reduction PSV B-mode Image Findings
Normal <≈150 cm/s No evidence of wall thickening or plaque
<50% ≈150 – 200 cm/s Wall thickening or minimal plaque
≥50% ≥≈200 cm/s Extensive plaque visualized
Total OcclusionNo detectable Doppler flow in
the ECAICA clearly identified
Plaque visualized
PSV thresholds should be considered as approximate (≈) Normal ECA Doppler waveform is high resistance with a multiphasic flow pattern Focal velocity increase and post-stenotic turbulence with damping of the distal
flow waveform can be used to identify a ≥50% stenosis
Vertebral ArteryTHE OTHER CAROTID CRITERIA
Diameter Reduction PSV and Doppler Waveform Features B-mode Image Findings
Focal velocity increase with PSV ≥≈200 cm/sec and a post-stenotic flow pattern
Retrograde flow direction (subclavian steal) or a “hesitant” or “to and fro” flow pattern (latent steal)
High resistance flow pattern (distal obstruction)
Extensive plaque visualized
Total Occlusion No detectable Doppler flow in the vertebral arteryAdjacent vertebral vein clearly identified Plaque visualized
Vertebral arteries are often asymmetrical in size, with one (most commonly the left), being larger
PSV thresholds should be considered as approximate (≈) Flow patterns can be affected by collateral flow (ICA occlusion, subclavian steal)
What I use
Flow disturbances with stenosis: Increased PSV and EDV Spectral broadening
SV = sample volume
Spectral broadening
Increased PSV
All three
1983
Narrow frequency
band
Spectral “window”
Increased EDV
General Principles – Abnormal Flow PatternsTHE OTHER CAROTID CRITERIA
Spectral broadening with a small “intimal flap”
Topics for Discussion
General principles Common carotid External carotid Vertebral
THE OTHER CAROTID CRITERIA
For a significant (pressure-reducing) stenosis:1. Normal or high-resistance waveform proximally Depends on intervening branches (collaterals)
2. Focal high velocity jet at the site of stenosis Systolic velocity increases May only be present for 1 or 2 vessel diameters Diastolic velocity increases in severe stenosis
General Principles - StenosisTHE OTHER CAROTID CRITERIA
Vertebral Artery - StealTHE OTHER CAROTID CRITERIA
Labropoulos et al. Ann Surg 2010;252:156
Only 38 (7%) of 514 patients were symptomatic 32 posterior circulation 4 upper extremity 2 cardiac ischemia
Presence of symptoms was more common in patients with higher brachial pressure gradients 0.9% with 20 to 30 mmHg 9% with 30 to 40 mmHg 27% with 40 to 50 mmHg 39% with >50 mmHg