Lower Limb Arterial Ultrasound · 2021. 2. 24. · •Most common cause of lower limb claudication...
Transcript of Lower Limb Arterial Ultrasound · 2021. 2. 24. · •Most common cause of lower limb claudication...
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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