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Lower Limb Arterial Ultrasound

Claire O’Reilly

Objectives

• Anatomy

• Risk factors

• Clinical Indications -signs and symptoms

• Pathology

• Scan technique

• What we are looking for

• Documentation

• Cases

Anatomy

https://www.ultrasoundpaedia.com/normal-leg-arteries/

Risk factors• Age

• Sex M>F

• Smoking

• Diabetes

• Family history

• High cholesterol

• Hyperlipidaemia

• Hypertension

• Lack of physical activity

• Overweight/ obesity

Clinical Indications

• Hip, buttock, thigh, calf claudication

• Rest pain

• Calf/muscle wasting

• Elevation pallor and dependant rubor – arterioles and capillaries no longer constrict under hydrostatic pressure

• Reduced peripheral pulses – cold/numb

• Acute ischaemia

• Abdominal aortic aneurysm/Popliteal artery aneurysm - bruits

• Ischaemic ulceration and gangrene

• Embolic event to more distal vessels

• Disease monitoring

• Monitoring of intervention – angioplasty, stents, bypass grafts

Pathology

• Atherosclerotic• Stenosis/occlusion

• Aneurysm

• Embolism

• Non- atherosclerotic• Popliteal artery entrapment

• Giant cell arteritis

• Antiphospholipid antibody syndrome

• Polycystic Adventitial disease

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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

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

https://princetonlongevitycenter.com/understanding_heart_attacks/

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.

• Dissection - rare• Iatrogenic - catheterisation

• Spontaneous

Scanning- Getting 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

Scanning- positioning

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

Scanning – Distal Aorta

• Distal Aorta• Supine

• Arms by side

• Sustained compression

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Scanning - Iliacs

CIA, EIA, IIA• Sustained compression• Lateral window• 45° sponge

Scanning – Femoral artery

Scanning – popliteal artery

• Patient positioned on side with contralateral leg anterior

• Examine popliteal art and tibio-peroneal trunk

• Posterior window

Scanning – Calf arteries

Scanning - pitfalls

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.

Lower PRF and wall filters, leg in dependant pos. To increase dist. blood flow

What we look for

• Assess from distal aorta- ankle

• Locate and quantify arterial disease• B-mode, color and spectral

• Document on worksheet any

velocity increases, narrowing

or occlusion.

• Highlight limitations

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Interpretation

• B-mode• Anatomy• Plaque/ calcification

• Colour Doppler• Calibre• Aliasing

• Spectral Doppler• PSV• Waveform

Normal

Stenosis - B-mode and Colour Doppler Stenosis - Spectral

At stenosis

↑ PSV

Spectral broadening

Distal to a stenosis or occlusion

Distal to stenosis or occlusion ↓ PSV, monophasic flow

Drop in pressure across lesion

Damped

Diagnosing Stenoses – Velocity Criteria

Ratio 2:1-4:1 50-75% or PSV > 200cm/s Ratio >4:1 >75% or PSV > 400cm/s

Pre-stenosis At Stenosis

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Recognising Occlusion

At Occlusion

No flow

Possibly collaterals

Distal reconstitution

Documentation

• Relate findings to clinical picture

• Relevant information

• What do they want to know?

• How will this change management?

• Schematic of the legDocument velocitiesDescribe waveformsDraw stenosis / measure locationGrade stenosisQuality statementsDescribe limitations

Summary

• Know the anatomy and pathology

• History • Talk to patient

• Think about the clinical question

• 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

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Findings

• 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 Dacron bypass graft

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? Stenosis Stenosis in the adductor canal

Case 3 - 4689333

• 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 with triphasic 3 vessel run off in the calfAnkle – 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

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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