chapter 12: duplex ultrasound of lower extremity arteries

signs and symptoms of chronic arterial insufficiency

• intermittent claudication

• rest pain

• nonhealing ulcers; gangrene

• trophies changes (hair loss, nail thickening,skin changes)

signs and symptoms of acute arterial insufficiency

• pallor

• pulselessness

• paralysis

• paresthesia (pins & needles)

• intense pain

• coolness

supine

most common position is — with knee slightly flexed and thigh abduction

lateral decubitus

— position may be used to evaluate:

• popliteal artery

• tibioperoneal trunk

• peroneal artery

curvilinear 5-2 MHz and/or phased array 3-2 MHz transducers

useful for aortoiliac scanning and deeper lower extremity vessels in heavier limbs

linear 7-4 MHz transducer

useful for the majority of lower extremity vessels

high-resolution, linear 18-7 MHz transducer

may allow better visualization of more superficial vessels, especially near ankle and foot

anterior tibial artery

the only vessel that we don’t scan on the venous side

PFA

only needs to be evaluated in its proximal segment

SFA

should be evaluated throughout its entire length in the thigh

popliteal artery

SFA becomes — as it passes through the adductor canal

PA (popliteal artery)

is examined through the popliteal fossa

• multiple small branches present including gastrocnemius arteries

sural arteries

the gastrocnemius is also known as the

anterior tibial origin

can be seen in popliteal fossa then remainder can be followed with an anterolateral approach

posterior tibial & popliteal artery

can be followed with a medial approach

peroneal

may also be examined with a posterolateral approach

spectral doppler

used as primary tool to categorize disease

when disease is present (stenosis)

velocities and waveforms should be recorded proximal to the stenosis, in the stenosis, and distal to the stenosis

1.5

if there is a bulge in a vessel and it is — times bigger than the proximal portion of the artery then it is an aneurysm

pitfalls of ultrasound

• calcified vessels

• extremely low flow

• uncooperative patients

• swelling and/or depth of vessels may limit visualization

• exam length in complicated cases

normal arterial walls

are smooth and uniform

atherosclerotic plaquing

can be described as

• homogeneous or heterogeneous

• smooth or irregular

aneurysmal disease

• can be bilateral and multilevel

• aneurysm is present if the diameter of a vessel is 1.5 times bigger than the adjacent, more proximal segment

• presence or absence of thrombus should be documented (embolic risk)

abnormal color findings

• aliasing

• reduced flow channel

• color bruit

normal findings of spectral analysis

• PSV that does not increase

• normal, high resistance spectral waveform

  • sharp upstroke

  • rapid deceleration

  • reflected wave with retrograde flow in early diastole

  • brief wave of antegrade flow in mid to late diastole

abnormal findings of spectral analysis

• focal velocity increases

50%

PSV velocity ratio >2 = > — stenosis

• velocity doubles

70%

PSV velocity ratio >3 = > — stenosis

• velocity triples

distal to a hemodynamically significant stenosis (starts to affect the down flow)

the spectral waveform can be expected to have

• more low resistance characteristics (flow throughout diastole)

• delay rise to peak systole (tardus parvus)

decreased distal resistance (arteriovenous fistula, trauma, cellulitis, post exercise)

• antegrade flow can be expected throughout diastole

• sharp systolic upstroke will be preserved

proximal to an occlusion or near occlusion

spectral waveform will display

• very high resistance pattern

• antegrade flow component only during systole

• no flow during diastole

contrast arteriography

still considered the gold standard for diagnosis of arterial stenosis

contrast arteriogaphy can be used when duplex imaging is limited, such as

• severe arterial calcification

• severe edema or morbid obesity

• extremely limited run-off

• extensive skin wounds

• extremely low flow

limitations of arteriography

• delineates patent arterial lumen only

• misses thrombosed popliteal aneurysms

• fails to visualize outflow and inflow in very low-flow situations

• requires potentially nephrotoxic agents

• requires use of ionizing radiations

• delays prompt treatment

ultrasound image of the popliteal artery with the gastrocnemius artery

ultrasound image of the origin of the anterior tibial artery (ATA) off the popliteal artery w/ the tibioperoneal trunk

ultrasound image of the posterior tibial artery (PTA) and peroneal arteries arising off the tibioperoneal trunk

an ultrasound image of an artery w/ atherosclerotic plaque

ultrasound image of a color-flow image identifying flow abnormalities associated with hypoechoic arterial plaque

a doppler waveform taken proximal to a stenosis

what does image A represent

a doppler waveform taken at the area of maximum velocity shift within a stenosis

what does image B represent

a doppler waveform distal to a stenosis documenting poststenotic turbulence

what does this image represent

color doppler image of an occluded superficial femoral artery with acute thrombus overlying severe chronic arterial disease

ultrasound image of a very low velocity vessel

color doppler image of a distal PTA with segmental heavy calcifications creating shadows obscuring the arterial lumen

power doppler image of a severely diseased behind knee popliteal artery with very irregular ulcerated plaque surface w/ high embolization potential

power doppler image of a small behind the knee popliteal artery aneurysm (13.1mm) w/ near-wall mural thrombus

normal multiphasic waveform taken from SFA

an abnormal waveform illustrating constant forward flow throughout the cardiac cycle in addition to a delayed upstroke . distal to high-grade stenosis or occlusion

waveform dusiplaying a normal systolic upstroke with constant forward flow through diastole

an abnormal high resitance waveform with only antegrade flow through systole . this is observed proximal to a near occlusion or occlusion