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

Focal High-velocity jet Post-stenotic turbulence

A stenosis acts like a filter

Tardus-parvus pattern Pre-stenotic Post-stenotic Stenotic

General Principles - StenosisTHE OTHER CAROTID CRITERIA

A B C

Common Carotid Artery – Velocity Criteria 62 patients with 115 arteries CCA PSV ≥150 cm/s and CTA Better agreement for % area vs.

% diameter stenosis on CTA CTA area stenosis:

<50% 76 (66%)50-59% 8 (7%)60-69% 8 (7%)70-79% 9 (8%)80-89 3 (3%)90-99 5 (4%)Occluded 6 (5%)

115

THE OTHER CAROTID CRITERIA

Slovutt et al. J Vasc Surg 2010;51:65

Sensitivity 76%Specificity 89%

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

Occluded left CCA

Retrograde flow in the ECA supplies the ICA

Common Carotid

External CarotidInternal Carotid

Vertebral Artery – Interpretation Points Key waveform features: Velocity Direction Resistance

Usually scan the V2 (intra-foraminal) segment

THE 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:

THE OTHER CAROTID CRITERIA

Hua et al. AJR 2009;193:1434

Diameter Reduction Cutoff (cm/s) Sensitivity

(%)Specificity

(%) Accuracy (%)

<50% ≥85 92.0 96.7 94.550-69% ≥140 96.1 96.4 96.270-99% ≥210 86.2 90.8 88.7

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

(V2) segments PSV threshold of

114 cm/s identified >50% vertebral artery stenosis

Sensitivity 70% Specificity 90%

*PSV vertebral artery origin

*

Vertebral Artery - Steal Subclavian Steal Subclavian artery stenosis/occlusion

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

NormalPSV <≈100 cm/sec , Antegrade flow directionLow resistance flow pattern, Uniform velocities throughout

the vessel segments evaluated

No evidence of wall thickening or plaque

<50%Focal velocity increase with PSV ≈100-200 cm/secAntegrade flow direction, Low resistance flow pattern

Wall thickening or minimal plaque

≥50% or other Abnormal 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

3. Dampened waveform (tardus-parvus) distally Post-stenotic turbulence (spectral broadening)

Velocity may decrease in a very tight 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