Lower Limb Arterial Ultrasound

Taylor Tirahardjo

Lower Limb Arterial Ultrasound

Learning Objectives

3. RISK FACTORS 1. ANATOMY

7. DOCUMENTATION

2. PATHOLOGY

5. SCAN TECHNIQUE 6. WHAT TO LOOK FOR

4. CLINICAL INDICATIONS

8. CASES

Anatomy

Ao POP V

POP A

PTA

PER A

ATA

Ao

CIA

IIA

EIA

FV

SFACFA

PFA FV

• Popliteal artery entrapment• Giant cell arteritis• Antiphospholipid antibody

syndrome• Polycystic Adventitial

disease

ATHEROSCLEROTIC

NON-ATHEROSCLEROTIC

• Stenosis/occlusion• Aneurysm• Embolism

Pathology

Over time fatty deposits (plaque) made of cholesterol and inflammatory cells also build up at the site and harden and narrow

the artery.

Atherosclerosis

The exact cause is unknown however it is a slow and complex process.

Can begin as early as childhood and progresses more rapidly with age.

Damage to the endothelium – inner lining of the artery.

Blood cells and other substances clump to the injury site.

Atherosclerosis

• Embolic event• If the lining covering the plaque ruptures

then it stimulates blood clot formation.

• With the high velocities in arteries this clot easily flicks off and enters the blood stream – this can then lodge in a new location and block the artery – like brain –stroke.

• Aneurysm • Caused by weakened artery walls.

• Usually atherosclerosis or high blood pressure.

Non-Atherosclerotic

Popliteal artery entrapment

Rare vascular condition in which the abnormally positioned or enlarged calf muscle

presses on the popliteal artery making it harder for blood to get to the lower leg.

Giant cell arteritis

An inflammation of the lining of the arteries

Polycystic Adventitial disease

A rare condition in which muscinouscysts form within the adventitia of

arteries and veins which can lead to lumen narrowing and occlusion.

Antiphospholipid antibody syndrome

Occurs when your immune system mistakenly increases antibodies that

your blood more likely to clot

Risk factors

SMOKINGDIABETESAGE OBESITY MALE

HYPERTENSION FAMILY HISTORY HIGH CHOLESTEROL INACTIVITY HYPERLIPIDAEMIA

ClinicalIndications

Leg or foot wounds that are slow to heal.

Unexplained leg pain or cramping especially during exercise or walking.

Skin problems or discoloration on legs and feet.

Poor nail growth.

ClinicalIndications

Reduced peripheral pulses- cold/numb.

Acute or chronic ischemia.

AAA- ?popliteal aneursym

Embolic event to distal vessels.

Monitoring of disease and intervention-angioplasty, stents, by pass grafts.

ScanningGetting Started

Clear patient history

Transducer• Curvi-linear (C5-1MHz) for aorta and iliacs

• Linear (9-3MHz) for legs

Gel and towel

Triangle sponge for iliacs

ScanningPositioning

POSITIONING

• Make it easy for yourself at the start

• More important than you might think

ERGONOMICS and COMFORT

• For you and the patient

• Bed Height

• Patient close to you

• Sponges available

ScanningDistal Aorta

Supine

Arms by side

Sustained compression

AoIVC

ScanningIliacs

CIA, EIA, IIA

Sustained compression

Lateral window

45° sponge

Ao

CIA

IIA

EIA

ScanningFemoral arteries

CFA, SFA, PFA

Start at groin crease

Turned out leg

Medial window

FV

SFA

CFA

PFA FV

SFA

FV

ScanningPopliteal Artery

POP A, TPT

Patient on side

Posterior window

POP A

TPT

PTA

PER AATA

ScanningCalf Arteries

(medial)PTA, PER A

Patient on side

Medial/DVT window

TPT

PTA

PER A

PTA

PER A

F

T

ScanningCalf Arteries

(lateral)ATA, DPA

Lateral window

ATA

DPA

Segment Problem Solutions

Aorto-Iliac Arteries Gas Graduated probepressure, Pt Position

Aorto-Iliac Arteries Tortuous Arteries Colour

Femoral Popliteal Arteries Calcification Transducer position

Femoral Popliteal Arteries Obese Curved transducer, lower doppler transmit freq

Tibial Arteries Large calf, oedema Start at ankle and work up, curved probe

Tibial Arteries Low flow due to prox. Occl.

Decrease scale and gain.

Scanningpitfalls

What we look for

Assess from distal aorta- ankle

Locate and quantify arterial diseaseB-mode, color and spectral

Document on worksheet any

velocity increases, narrowing

or occlusion.

Highlight limitations

• B-mode• Anatomy• Plaque/ calcification

• Colour Doppler• Calibre• Aliasing

• Spectral Doppler• PSV• Waveform

Interpretation

Normal

Stenosis - B-mode and Colour Doppler

StenosisSpectral

At stenosis

↑ PSV

Spectral broadening

Distal to a stenosis

Distal to stenosis or occlusion

↓ PSV, monophasic flow

Drop in pressure across lesion

Damped

Diagnosing Stenoses

Velocity Criteria

PRE STENSOSIS

AT STENSOSIS

50-75%

>75%

OR

OR

Ratio 2:1-4:1

Ratio >4:1

PSV >200cm/s

PSV > 400cm/s

RecognisingOcclusion

At Occlusion

No flow

Possible collaterals

Distal recanalization

COLLATERALS

If an arterial segment is severely diseased or occluded, there are often alternative pathways that are able to carry blood around the diseased segment.

In some situations, reverse flow is observed in major branches of arteries just distal to an occlusion, where it may help resupply blood to the rest of the leg.

In chronic situations the body may create new pathways to recanalize a distal vessel.

Documentation

• Relate findings to clinical picture

• Relevant information

• What do they want to know?

• How will this change management?

Schematic of the legDocument velocitiesGrade stenosisDraw stenosis/occlusions and measure locationDraw collaterals Draw in stents and bypass if applicableDescribe waveformsDescribe limitations

Summary

• Know the anatomy and pathology

• History

• Good technique

• Manage time

• Document well

Case 1

82 year old lady

Presented to ED

1 month post angioplasty (L) leg

Pain and cold (R) foot

Weak Dorsalis Pedis pulse

FindingsCase 1

• 50-75% stenosis CFA/SFA• Biphasic flow

• Thrombus distal SFA/ Pop A

• Collaterals supply to three calf vessels• Monophasic distal to thrombus

Balloon angioplasty

Case 2

93 year old male (Fit)

Hx of Lt-Rt Fem-Fem bypass graft (2007)

Bilateral mixed venous and arterial ulcers

R>L, worsening, painful

? Arterial insult

Lt- Rt Fem-Fem bypass graft

? Stenosis

Stenosis in the adductor canal

Case 3

18 year old female presented with Achilles and calf pain with exercise

Right > left

Normal MRI and X-rays

Non-smoker

Not diabetic

Normal leg artery ultrasound

3 vessel run off

Triphasic waveforms

Ankle – Brachial Index

• Objective test for presence of PAD

• Ratio of BP from Arm/leg

•Eg Brachial 150, Ankle 110

110/150 = 0.73

• Rest and Exercise

Popliteal Artery Entrapment

Most common cause of lower limb claudication in young athletes

If left untreated it can lead to popliteal artery damage, embolisation and limb

ischaemia

During plantar flexion the gastrocnemius muscle or the plantaris muscle cause

external compression of the popliteal artery

• a) Popliteal artery longitudinal duplex scan in neutral position

• b) Same popliteal longitudinal scan with plantar flexion

• c) Reactive hyperaemic response following resumption of normal position

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