Carotid duplex

Capabilities/limits

• Localizing disease and surface characteristics

• %DR

Doppler angle must…

be parallel to flow

IMT

Intima-media thickness

Predictor for disease

Intimal thickening

>0.9mm

Acute thrombosis appearance

• anechoic or hypoechoic

• large caliper

Chronic thrombosis appearance

• Decreased vessel size

• hypo to echogenic

• thumping pattern, piston like horizontal motion

Normal ICA waveform

Low resistance

Normal ECA waveform

High resistance

Normal CCA waveform

Mixed between the I and E

%DR is determined by what?

EDV

Reasons for overestimating stenosis

• High cardiac output: bilat and throughout

• Decrease in blood viscosity: bilat and throughout

• Tortuous vessels

• Compensatory flow changes

Underestimating stenosis

• Prox stenosis

• Poor CO

• CHF

Indirect indications of presence of disease

Abnormally high resistance, absent diastolic

String sign on power doppler

Near total occlusion

Dampened tardus parvus

Proximal disease if unilateral

Poor CO if bilateral

Oscillating or helical pattern

Brain death

Subclavian steal

Proximal subclavian/brachiocephalic obstruction or occlusion causing a steal of blood from the vertebrals

Subclavian steal symptoms

May have VBI symptoms with UE ischemia symptoms and a brachial pressure with a >20 mmHg difference

When there is a >20 mmHg difference of the brachials, which side has the disease?

The lower side is on the side of disease (MC on left)

Subclavian steal findings

Retrograde flow in the vertebral artery

Indicates occlusion of the prox sub/innominate

Pre-steal (stenosis of innominate/subclavian)

Bidirectional vertebral flow

Takayasu arteritis

• Usually younger women

• Larger vessels (may be CCA)

• “Pulseless” disease

• Finding: donut vessel

Temporal arteritis

• Inflammation of superficial temporal a

• Headaches

• Findings: “halo” inside vessels

Carotid endarterectomy- acute defects

• Stricture of the suture line

• Intimal flaps

• Platelet aggregation

• Residual plaque

6-24 months after endart what are we looking for?

Intimal hyperplasia

Immediately after an endart what are we looking for?

Thrombosis/dissections

Post-stenting

Stented vessels have a higher velocity so can’t use the same criteria!

Up to 225 cm/s is WN