8. peripheral arterial duplex imaging and pathology

DMUT 4

what are the risk factors for peripheral arterial pathology/disease

smoking

diabetics >50 years

age >70 years

what are the peripheral arterial pathologies

occlusive disease, pseudoaneurysm, arteriovenous fistula (AVF), aneurysms, and atherosclerosis

occlusive disease can be found with either…

indirect testing or duplex ultrasound

indirect testing is a reliable indicator for the presence of occlusive disease but does not provide…

anatomic info

indirect testing includes…

systolic pressures, ankle/brachial index (ABI), plethysmography/photoplethysmography, exercise testing, and CW doppler analysis

why is duplex ultrasound good for investigating peripheral arterial disease

gives anatomic and physiologic info

grayscale, colour, spectral, power doppler with waveform analysis

what position should LE duplex assessment be done in for patient

supine, with leg slightly bent and externally rotated (like DVT)

what transducer is used in arterial duplex imaging

7-10 MHz linear array transducer

what techniques are used in LE duplex exams

often only one window, increase room temperature (prevent vasoconstriction), and have a doppler angle of 60 (for reproducibility, and optimize images

normal flow velocities table *DNTM

normal arterial flow patterns

triphasic with flow reversal in early diastole

normal arterial flow waveform of SFA

when does loss of flow reversal occur in arterial waveforms

when peripheral resistance decreases, such as in exercise, reactive hyperemia, and limb warming

in laminar flow patterns where is the fastest velocities

centre of the vessel

symptoms of occlusive disease

intermittent claudication

thickened toenails/loss of toe hair

skin changes (discoloured and scaly)

forefoot pain (even at rest) and ulceration

what skin changes can occur in occlusive disease

elevation pallor (pale/white)

dependent rubor (red with foot hanging)

blueness of toes (aneurysmal emboli)

what is an indicator of severe disease and symptom of occlusive disease

forefoot pain (even at rest) and ulceration

claudication

leg discomfort/pain that worsens with activity and improves at rest

affects calf, thigh, and/or buttock

the site of claudication symptoms gives general idea to the

site of disease

in a duplex assessment, the findings of stenosis or occlusion in carotid vessels can be seen such as…

visualization of plaque/narrowing

colour flow disturbance,

waveform changes (proximal, at stenosis, and distal stenosis & velocity changes)

normal flow pattern characteristics

triphasic waveform with no spectral broadening

1-49% diameter reduction flow pattern characteristics

triphasic (reversed flow may be diminished)

minimal-moderate spectral broadening

peak systolic velocities increased <100% relative to adjacent prox segment

proximal and distal waveforms remain normal

50%-99% diameter reduction waveform characteristics

monophasic waveform with LOSS of reversed flow, forward flow throughout cardiac cycle

extensive spectral broadening

peak systolic velocity increased >100% relative to adjacent proximal segment

distal waveform is monophasic with reduced systolic velocity & prolonged acceleration (tardus parvus waveform)

occlusion in vessel flow patterns

no flow detected within imaged arterial segment

preocclusive “thump” may be heard proximal to site of occlusion

distal (collateral) waveforms are monophasic with reduced systolic velocities

what is the most reliable indicator for the presence of a 50% or greater stenosis?

a 2:1 systolic velocity ratio with focal velocity acceleration and post stenotic turbulence

spectral broadening and increased focal velocities on varying stenotic waveforms compared to normal waveform

post stenotic segment US (tardus parvus)

A normal study rules out significant Aorto-iliac disease but not…

minor stenosis

what should be considered if the aorto-iliac segment needs to be scanned for occlusive disease?

thigh PVR waveform

Thigh pressure

CFA doppler waveform

femoral pulse

if there is an abnormal ABI without any detectable disease in the fem-pop or tibial arteries, or abnormal thigh PVRs or waveforms, then what should be scanned?

the aorto-iliac segment, though it is difficult to image these findings indicate need for scanning the A-I segment

what vessel waveform can appear normal distal to a mild iliac stenosis but does not rule out iliac disease?

the CFA waveform

SFA segment on colour

for the SFA segment, what should be evaluated with colour doppler?

the distal CFA and bi of the CFA into the SFA and profunda femoris (PFA)

proximal right SFA

left SFA on US

SFA stenosis on US

spectral tracing of SFA stenosis US

post stenotic turbulence of SFA (mid) US

distal right SFA US

composite SFA occlusion on US

collateral inflow of SFA in TR US

flow entering an artery is usually reconstituted flow and indicates…

more proximal disease

popliteal artery power doppler composite US (proximal to PTA)

the anterior tibial artery is seen to dive what direction on US?

goes off posteriorly

tibio-peroneal trunk US with colour

proximal PTA spectral US

radial & ulnar arteries can be used in what procedure?

CABG - Allan’s test

veins can be harvested for what bypasses?

fem-pop and fem-tibial bypass

duplex is used for

interval F/U post intervention

what are the 3 types of grafts for supra-inguinal bypass

1. bypass diseased distal AO/iliacs (EVAR)

2. bypass single iliac artery

3. bypass entire abdominal aorta

diagram of the 3 types of grafts for supra-inguinal bypass

3 categories for graft failure

1. technical failure (0-30 days post-op)

2. fibrointimal hyperplasia (1month-2years post-op)

   1. progression of atherosclerosis

bypass grafts are preformed to avoid…

amputation, AKA “limb salvage”

Method for examining bypass grafts and stents

obtain ABIs and PVRs

do not perform segmental pressures over bypass

evaluate using grayscale, colour, doppler

assess for stenosis, wall irregularity, aneurysms, pseudoaneurysms, AVF

assess anastomosis for stenosis/defects

neo-intimal hyperplasia

check for hematoma/seroma post-op

obtain PSVs along graft & prox feeding & distal runoff. stenotic regions prox, at and distal

neo-intimal hyperplasia

overgrowth of plaque like material in vessels

in-situ vein graft on US showing intimal hyperplasia

reinforced access graft on US

in situ vein graft stenosis US

in bypass grafts and stents when evaluating for stenosis follow the general rule of these when comparing to pre-stenotic segment

velocity doubling (2:1 ratio)

post-stenotic turbulence

distal tardus parvus

if velocities are less than 40-45cm/s in the graft the patient is at risk for what?

graft thrombosis,

lower extremity aneurysms characteristics

more common in pop a. or SFA

may be bilateral

often asymptomatic with mural thrombus

what can be mistaken for venous thrombus?

mural thrombuswhat

what should be done to distinguish between a mural thrombus and a venous thrombus

ensure visualization of both vessel and use spectral doppler to differentiate between artery and vein

POP A aneurysm mimicking DVT US

spectral doppler confirming arterial waveform for POP A aneurysm

what has a jhigh association with AAA

popliteal artery aneurysms

symptoms of pop a aneurysm

claudication

rest pain

limb ischemia

blue toe

nerve compression

popliteal aneurysm in TR and LONG US

the normal popliteal artery should measure…

5-6mm

popliteal artery aneurysms have a high association with…

AAA

pseudoaneurysm

puncture of arterial wall from procedure that balloons adventitia wall outward

diagram for types of aneurysms compared to normal vessel

what is the most common site for interventional arterial access route (via cardiac catheterization)

femoral artery

a false aneurysm is not confined by

all 3 walls.

includes 1 or 2 of the arterial walls

what artery is most commonly affected with pseudoaneurysms

CFA (iliac and SFA are possible as well)

clinical symptoms of pseudoaneurysms

audible bruit

palpable, pulsating mass

ecchymosis (red & bruised)

complications that can occur from pseudoaneurysms

rupture

thrombosis of adjacent veins (compression can cause venous stasis)

sonogrpahic appearance of a pseudoaneurysm

assess puncture site

contained fluid collection adjacent to normal vessels

variable appearances (echogenic thrombus or swirling low-level echoes)

demonstrate “neck” of pseudoaneurysm (diameter & length)

CD = yin-yang sign

spectral = to-and-fro waveform

what is a differential for pseudoaneurysm

hematomawh

at is the most important thing to measure and assess during a pseudoaneurysm

the neck of the pseudoaneurysm (want to know for treatment)

pseudoaneurysm Yin-yang sign US

to-and-fro on spectral doppler from pseduoaneurysm

thrombus formation in pseudoaneurysm US

a short and wide neck on the pseudoaneurysm is important to document because…

if thrombin is used then it can travel to native artery and occlude it. So documenting it as short and wide means they look for alternative treatment (surgery)

what characteristics are best to have in the pseudoaneurysm neck

long and skinny to treat with thrombin

Treatment for pseudoaneurysm

ultrasound guided/sandbag compression

ultrasound guided thrombin injection

surgical repair (when neck is short and wide)

Ultrasound guided thrombin injection has the potential to thrombose to …

femoral artery (if short and wide neck)

arteriovenous fistulas (AVF)

abnormal connection between adjacent arteries and veins

can be congenital or iatrogenic

iatrogenic causes of AVF

arterial or venous catheterization or intervention

penetrating trauma

AVF sonographic appearance

visualized color jet (shows connection)

high velocity waveform (turbulence, ambiguous arterial/venous patterns)

color bruit (color speckle over tissue)

arterialized venous flow on spectral

color on AVF between CFV & PFA

spectral tracing of CFV & PFA

blue toe syndrome

acute ischemic event

painful cyanotic regions to toes or foot

what causes blue toe syndrome

thrombo-emboli leading to occlusion

buerger’s disease is also called

thromboangitis obliterans

what is bueger’s disease

a fixed occlusive inflammatory process that causes thrombosis of digital arteries (fingers and toes)

bueger’s disease diagram

buerger’s disease is most commonly related to

male population and smokers,

can also occur in occupational trauma

primary Raynaud’s phenomenon

vasospastic disorder without underlying disease. the digital and palmar arteries without obstruction and perfusion to the digits at rest is normal