URR Lower Extrem Arterial Disease

Question 1

what is arteriosclerosis

Answer 1

-intimal thickening, calcification and loss of wall elasticity
-“hardening of the arteries”
-most common sites in legs

Question 2

most common sites for arteriosclerosis?

Answer 2

1 SFA in adductor canal

#2 CFA bifurcation
#3 calf vessels and other vessel origins

Question 2

what is atherosclerosis obliterans?

Answer 2

-atherosclerotic changes produce progressive obstruction
-most common cause of arterial occlusive disease
-accumulation of lipids in intima which causes narrowing
-usually affects extrems in a diffuse manner but increased incidence in pop and calf arteries
-focal stenosis and diffuse stenosis can coexist
-symptoms of moderate disease usually exacerbated w/ exercise and relieved w/ resting in dependent position

Question 3

arteritis

Answer 3

-inflammation of the artery walls causing flow stasis w/ thrombus formation
-usually affects peroneal arteries, posterior and anterior tibial arteries and smaller distal arteries/capillaries

Question 4

thromboangiitis

Answer 4

refers to diffuse inflammation of the intimal wall layer

Question 5

what is kawasaki disease?

Answer 5

-affects small to medium arteries
-coronary arteries are commonly affected; causes dilatation and potential aneurysm formation
-usually seen in peds patients age 2-5 years old
-more common in the Japanese population

Question 6

buerger disease/ thromboangiitis obliterans

Answer 6

-occlusive disease of small to medium size arteries caused by inflammation of arterial wall and surrounding connective tissue
-digital, plantar, tibial, peroneal, radial, and ulnar arteries
-always associated with heavy smoking
-most common in men, age 20-30
-associated with collagen disease, such as lupus
-acute onset in plantar or palmar arteries then moves centrally
-always bilateral but one side can be affected more significantly than the other
-most patients have at lease 3 out of 4 extrems affected
-ischemic rest pain and distal ulcers are common
-associated with in step claudication
-evaluated by doppler and PPG techniques

Question 7

takayasu arteritis

Answer 7

-presents as hypertrophic areas of inflamed tissue usually found in the Ao and its branches
-associated with supravalvular stenosis and aortic coarctation
-90% cases involve the CCAs
-can also affect the renal As
-most commonly seen in young females (20-40 yrs)
-most common in Asia and India than the US
-symptoms include absence of peripheral pulse, asymmetric brachial blood pressures, amaurosis fugax, hemiparesis, diplopia, vertigo and upper extrem claudication

Question 8

takayasu arteritis sonographic appearance?

Answer 8

-presents similar to stenosis
-clinical exam important for differentiation from atherosclerotic disease
-increased PSV and diastolic flow
-2D appearance shows more diffuse involvement and more homogeneous thickening of the vessel walls than seen with atheroma formation

Question 9

giant cell arteritis

Answer 9

-usually presents in the cranial arteritis (temporal arteritis), but can be seen in the extrems
-usually seen in patients 70-80 years of age
-more common in women
-blood tests performed (to measure the erythrocyte sedimentation rate, to measure C-reactive protein)
-temporal arteritis with headaches and tenderness over the artery
-asymmetric brachial blood pressures seen in patients with arteritis in extrems
-other symptoms include pain and or stiffness in the neck, jaw claudication, and visual disturbances
-biopsy is the best method for diagnosis
-treated with corticosteroids like prednisone

Question 10

giant cell arteritis sonographic appearance?

Answer 10

-causes diffuse or focal thickening of the muscle layer
-may see increased vascularity in the wall of the inflamed segment
-halo sign = a ring of thickened vessel wall tissue surrounding the vessel
-doppler findings

Question 11

-focal dilation of the arterial wall
-caused by a breakdown of the media and adventitia is most commonly affected
-leads to decreased flow velocity and stasis of flow in the areas of flow separation
-thrombus can form in the areas of stagnant flow

Answer 11

aneurysm

Question 12

pop aneurysms are usually

Answer 12

bilateral
-> 60% of patients with a pop aneurysm also have a AAA

Question 13

when is surgical repair recommended for aneurysms?

Answer 13

-if the extrem exceeds 2.5 - 3 cm in diameter
-if aneurysms in the ao that exceed 5.5 cm in diameter

Question 14

sonographic appearance of aneurysm?

Answer 14

-increased arterial diameter
-AAA > 3 cm diameter
-pop artery aneurysm > 1 cm diameter
-color has low velocity, turbulent, swirling flow, yin/yang sign
-doppler eval will demonstrate low velocity, low resistance flow

Question 15

what is embolization?

Answer 15

-obstruction of a vessel by a foreign substance such as plaque or thrombus
-most arterial emboli are from a cardiac source
-atrial fibrillation is the most common cardiac abnormality associated with embolization
-embolic material lodges in distal artery causing ischemia/necrosis
-an air bubble can also be harmful embolism
-other causes include thrombus in aneurysm, arteritis, ulcerated atherosclerotic lesions, some angioplasty procedures

Question 16

what is blue toe syndrome?

Answer 16

-discoloration of the digits caused by acute ischemia
-caused by small pieces of plaque or thrombus breaking loose from a more proximal site
-commonly seen in patients with AAA after a recent angiography procedure

Question 17

what is a pseudoaneurysm?

Answer 17

-blood escapes through all 3 layers of the arterial wall into surrounding tissues and is encapsulated within the tissues
-a connection is made through a neck or stalk
-typically caused by trauma or invasive procedures (cardiac cath, cangioplasty)
-groin is most common for pseudoaneurysm
-primary symptoms are palpable, pulsatile mass, and a bruit
-anticoagulation therapy should be discontinued to aide in closure

Question 18

how is pseudoaneurysm treated?

Answer 18

-compression or thrombin injection
-treatment selected based on size of the pseudoaneurysm and the diameter of the neck
-smaller ones can clot spontaneously

Question 19

contraindications for US guided compression therapy for pseudoaneurysm?

Answer 19

-patient unable to tolerate the procedure due to pain
-infection at the puncture site and surrounding tissues
-diameter > 4 cm
-stalk diameter > 5 cm
-present for more than 1 month
-patients on anticoagulant therapy

Question 20

contraindications for thrombin injections?

Answer 20

-small diameter
-indefinable neck/stalk location
-associated AVF
-current anticoagulant therapy

Question 21

what does a pseudoaneurysm look like?

Answer 21

-rounded anechoic structure adjacent to main artery
-measure size of body of the aneurysm in 2 planes
-measured diameter of the neck at the widest point
-color shows connection between artery and structure, turbulent flow, yin/yang sign
-doppler has high resistance to and fro flow in the stalk and low resistance to and fro flow in the body
-compression applied to close the stalk and stop the flow
-compression done in 10 one minute intervals with reevaluation of flow and color after each
-larger stalk pseudo can take longer than an hour of compression before treatment works
-should use PPG or toe pressures to monitor for changes

Question 22

what is thrombin?

Answer 22

clotting agent injected into pseudoaneurysm to close the opening and clot the blood that has escaped; requires sterile field
-thrombin more effective in treatment for larger stalk pseudo
-all types of treatments are less effective on pseudos with large stalks

Question 23

what is a traumatic AV fistula?

Answer 23

-if femoral A and vein are both punctured during the procedure, the resulting needle tract can provide a lumen for flow from high pressure arterial system into the low pressure venous system
-groin puncture can cause AV fistula between the femoral vessels
-can be complication of an invasive procedure, most commonly right heart cath

Question 24

what happens to flow in traumatic AV fistula?

Answer 24

-increased diastolic flow in the artery just prox to the arterial puncture site
-flow decreases in velocity and pulsatility as it enters the venous puncture site into the vein
-venous flow prox to an AV fistula becomes pulsatile and turbulent due to the inflow of arterial flow distally
-arterial flow prox to AV fistula will be low resistance; pressure will decrease in artery distal to traumatic fistula

Question 25

what happens to resistance with large diameter and small diameter fistulas?

Answer 25

-larger diameter and shorter fistulas offer less resistance to the arterial flow
-small diameter fistulas offer less resistance to the arterial flow

Question 26

-intimal layer tears and allows flow between the intima and media layers into a blind pocket (false lumen)
-remaining lumen (true lumen) is decreased in size due to flap and flow beneath
-causes weakened vessel wall, risk of vessel rupture
-thrombosis can occur in the false lumen causing stenosis/occlusion in the vessel leading to distal ischemia
-immediate surgical intervention required

Answer 26

dissection

Question 27

what does a dissection look like?

Answer 27

-linear echogenicity seen in the lumen of the vessel, separating it into two channels
-color flow demonstrates two lumens, both with turbulence
-bidirectional flow seen in vessel lumen
-echogenic thrombus may accumulate in the false lumen leading to stenosis of the true lumen

Question 28

what is popliteal entrapment?

Answer 28

-compression of the artery by the medial head of the gastrocnemius muscle
-commonly found in runners and athletes
-most common cause of unilateral claudication in young patients
-can cause numbness and paresthesia of the foot
-about 30% of cases are bilateral

Question 29

how to look for popliteal entrapment?

Answer 29

PPG eval can be used to assess the arterial pulse with flexion/extension of the foot
-patient decub with affected side up
-put sensor on great toe
-record baseline at rest
-patient hyperextend leg and flex and hold the foot (point toes)
-pulse diminishes when calf contracts

PW or CW
-patient decub with affected side up
-obtain resting 2D images with measurments of the diameter of the pop A in trans
-get doppler waveform of pop A at the level of the gastroc muscle
-patient hyperextend leg and flex and hold the foot (point toes)
-repeat diameter measurements and obtain doppler in same location
-vessel diameter will be reduced and waveform will demonstrate reduced or absent flow

Question 30

what is compartment syndrome?

Answer 30

-increased pressure in an osteofascial compartment that prevents blood flow in and out of tissues
-can lead to muscle and nerve damage and probs with blood flow
-can be considered critical finding to prevent muscle/ nerve damage
-most commonly acute onset and associated with broken leg or arm
-symptoms include paresthesia, localized muscle weakness, pain when stretching calf muscles, drop foot
-acute compartment syndrome is medical emergency, it is usually caused by a severe injury; w/o intervention, it can lead to permanent muscle damage
-chronic compartment syndrome, also known as exertional compartment syndrome, is usually NOT a medical emergency; usually related to athletic exertion; stopping the exertion usually clears up the problem
-anterior compartment syndrome: treated with a fasciotomy which is a procedure where the fascia is cut to relieve tension or pressure

Question 31

risk factors for acute compartment syndrome

Answer 31

-broken bone
-large bruise
-re-established blood flow after surgical intervention
-crushing injuries
-anabolic steroid use
-constricting bandages and casts

Question 32

Symptoms of compartment syndrome

Answer 32

-acute onset of persistent deep ache in an arm or leg
-pain that seems greater than expected for the severity of the injury
-numbness, pins and needles, or electricity like pain in the limb
-swelling and edema
-skin and muscle tightening

Question 33

what does compartment syndrome look like?

Answer 33

hematoma but within space between muscles/structures

Question 34

what is an adventitial cyst?

Answer 34

-rare condition
-collection of mucinous material within the adventitial wall layer of the affected vessel
-predominantly artery most commonly affected
-most common in young to middle aged men
-there is usually no other systemic vascular disease
-can cause lower extrem pain
-usually presents as multiple anechoic or hypoechoic areas within the wall
-no blood flow is detected in the areas
-can cause compression and narrowing of the vessel lumen (scimitar sign)
-can be treated by US guided cyst aspiration
-differential diagnosis includes: aneurysm, atherosclerotic disease, compartment syndrome, muscle/tear strain