Topic 6 - Lower Limb Arterial Disease

Question 1

List the main arteries supplying the lower limbs

Answer 1

Aortic bifurcation
Common Femoral artery
Profunda Femoris (Deep Femoral)
Superficial Femoral Artery
Popliteal Artery
Anterior tibial artery
Posterior Tibial artery
Peroneal artery

Question 2

What does the aorta bifurcate to become?

Answer 2

• divides into the left and right common iliac arteries.
• The right common iliac artery then passes ventral to its vein and divides into the external and internal iliac artery at the level of the sacro-iliac joint.
• The internal iliac artery passes deep to pelvis
• the external iliac passes along the psoas muscle to the mid point of the inguinal ligament to become the common femoral artery.

Question 3

Describe the femoral artery

Answer 3

• begins just above the inguinal ligament
• continues along the femoral sheath before bifurcating into the superficial femoral and profunda femoris arteries.
• It is located at the midpoint of the inguinal ligament.

Question 4

Describe the profunda artery

Answer 4

• main branch of the femoral artery
• usually consists of a single branch
• lies deep and slightly lateral to the superficial femoral artery
• before passing deep into the thigh and branching extensively it may continue for some length as a definable arterial segment deep to the femoral vein.

Question 5

Describe the superficial femoral artery?

Answer 5

• Begins at the bifurcation of the common femoral artery
• runs a straight course from the base of the femoral triangle to the tip of the femoral triangle at the adductor hiatus, which is about 10cm or 1hand’s width above the knee joint

Question 6

Describe the popliteal artery

Answer 6

• begins in the lower thigh at the adductor hiatus
• finishes below the knee
• it bifurcates below the knee at the lower border of the popliteus muscle into the anterior tibial artery and tibio-peroneal trunk (about 2.5cm below the tibial tuberosity).

Question 7

Describe the anterior tibial artery

Answer 7

• begins at the bifurcation of the popliteal artery at the level of the tibial tuberosity
• runs anteriorly to the interosseous membrane where it courses distally on the membrane to the dorsal surface of the foot to become the Dorsalis Paedis Artery (DPA)

Question 8

Describe the posterior tibial artery

Answer 8

• strictly begins at the bifurcation of the popliteal artery but it is often considered to begin at the bifurcation of the tibio-peroneal trunk about 2.5cm below the tibial tuberosity and courses posterior to the tibia to the lower border of the medial malleolus.

Question 9

Describe the peroneal artery

Answer 9

• begins as a branch of the posterior tibial artery about 2.5cm below the tibial tuberosity
• is commonly considered to branch from the tibio-peroneal trunk.
• The peroneal artery runs along the fibula and lies in close proximity to the shadow caused by the fibula.
• The peroneal and posterior tibial arteries can be distinguished from a postero-medial view of the calf with the peroneal laying closest to the shadow of the fibula and the posterior tibial, laying in the muscular tissue

Question 10

What are important observations to assess the patient ischaemia?

Answer 10

• Presence of pedal pulses (posterior tibial and dorsalis paedis) and femoral pulse
• Trophic changes in the feet: Thickened toe nails, dry and hairless skin or the presence of gangrene and cyanosis.
• A history of claudication.
The approximate distance walked before pain commences and where in the leg it is located.
Intermittent claudication is an important clinical feature to identify in patients with exercise related leg pain.

Question 11

Briefly describe the signs of chronic ischaemia?

Answer 11

• Usually the results of atherosclerosis.
• Worsens over time
• Progressing claudication and critical limb ischaemia

Question 12

Briefly define acute ischaemia?

Answer 12

not just a recent and severe onset of claudication or diffuse leg pain. Acute ischemia is defined by the presence of six features which include:
•	Pulselessness
•	Pallor
•	Paraesthesia
•	Paralysis
•	Poikilothermia (Cold)
•	Pain
These features may be present in varying degrees and there is usually a rapid and severe onset of symptoms.

Question 13

What are the main symptoms and their main cause of chronic ischaemia?

Answer 13

Claudication
Critical ischaemia
Caused by atherscleoris
Aneurysm

Question 14

What is the most common cause of lower limb ischaemia?

Answer 14

• Atherosclerosis

Question 15

How can atherosclerosis cause lower limb ischaemia?

Answer 15

• can result in either stenosis or occlusion of any one or more of the lower limb arteries
• may cause extensive lengths of stenosis or multiple stenotic focal lesions.
and aneurysms

Question 16

What is claudication?

Answer 16

• pain which is experienced during exercise due to loss of blood pressure.
• Intermittent Claudication is ischemic pain experienced during exercise which is relieved once the patient stops exercising

Question 17

How is claudication usually described by patients?

Answer 17

• usually described as cramping, tiredness, tightness, aching or pain and only occurs after exercise has begun and does not occur due to prolonged standing or sitting.
• Claudication is often experienced in the calf, but thigh and buttock claudication can occur with more proximal arterial disease.

Question 18

What are some causes of claudication?

Answer 18

• usually associated with atherosclerosis
• may be caused by spinal canal stenosis or by some less common arterial conditions such as entrapment syndrome, adventitial cysts or other conditions which cause stenosis of the arterial supply to the leg

Question 19

What is critical limb ischaemia?

Answer 19

• occurs when the level of ischemia causes tissue loss in the extremity
• usually associated with extensive ischemic changes and often with severe claudication and rest pain.

Question 20

What is rest pain?

Answer 20

• Rest Pain refers specifically to ischemic pain when there is insufficient pressure to adequately supply the leg while at rest (while supine).
• Rest pain usually occurs in the toes and foot but may at times be experienced in the region of the ankle

Question 21

What are the characteristic features of rest pain?

Answer 21

• The characteristic features of rest pain are usually experienced while supine and relieved by hanging the leg over the side of the bed.
• This relief is thought to be due to the increase in hydrostatic pressure which is enough to provide sufficient pressure to perfuse the tissues.
• Rest pain will be associated with trophic changes in the foot since it results from a severe degree of arterial compromise.

Question 22

Where are aneurysms in the lower limb usually located?

Answer 22

the common femoral and popliteal arteries.
• Aneurysms of the popliteal artery are the most common (after aortic aneurysms), with common femoral artery aneurysms coexisting with about 40% of popliteal aneurysms.

Question 23

What is a true aneurysm?

Answer 23

the arterial wall weakens and dilates as it increases in diameter.

Question 24

How can aneurysm cause acute ischaemia?

Answer 24

• Mural thrombus may also form in the lumen of an aneurysm and release emboli, which can occlude the distal arteries.

Question 25

What is a false aneurysm or pseudoaneurysm?

Answer 25

a collection of arterial blood which ‘leaks’ from an artery and is constrained by the adventitia and fibrous tissue adjacent to its source artery.

Question 26

What causes a false aneurysm?

Answer 26

often result from leakage from a needle puncture which does not seal, but may occur with other causes of trauma of the arterial wall.

Question 27

What are some risks of a false aneurysm?

Answer 27

• A false aneurysm may rupture, thrombose its feeding artery or embolise mural thrombus to occlude the distal arteries.

Question 28

What are two causes of acute ischaemia?

Answer 28

embolization and thrombosis

Question 29

How can lower leg emboli occur?

Answer 29

• from a proximal source such as the heart, an arterial aneurysm, atherosclerotic ulcer, graft, interventional procedure (Iatrogenic) or from a source which cannot be identified (Paradoxical).

Question 30

How can acute thrombosis occur?

Answer 30

• of an atherosclerotic artery or bypass graft may also cause acute ischemia.
• In an artery, the sudden formation of thrombus can be associated with an ulcerated or ruptured plaque
• while a graft may form thrombus associated with a stenosis or from residual valves or fibrous bands.

Question 31

Why is acute thrombosis sometimes difficult to identify?

Answer 31

not all occlusive thromboses produce the symptoms of acute occlusion and most patients occlude an artery with continuing symptoms of chronic ischemia.

Question 32

What are some causes of AV fistula/malformation

Answer 32

Klippel Trenaunay syndrome
Parkes Webber syndrome
A-V fistula from
- trauma
o	erosion of an aneurysm
o	invasion by neoplasm
o	abscess which results in the fistula formation.

Question 33

Describe Klippel Trenaunay syndrome and its relationship to AVM

Answer 33

• Patients have capillary and venous malformations that can cause limb swelling and varicose veins.
• The venous and capillary malformations do not disturb the blood flow to the leg and these patients usually have a good prognosis.

Question 34

Describe parkes webber syndrome and its relationship to AVM

Answer 34

• also shows capillary malformation with arterial malformations and may also develop varicose veins.
• The arterial involvement in this syndrome is associated with greater morbidity from increased limb length, ulceration and pain.
• The heart may also enlarge with the increased cardiac output associated with the degree of malformation present.

Question 35

Describe AV fistulas and their relationship with AVM

Answer 35

• considered to be different from vascular malformations
• fistula formation mostly occurring due to trauma or a related pathology such as
o erosion of an aneurysm
o invasion by neoplasm
o abscess which results in the fistula formation.
• Traumatic formation of AV fistula in the lower limb is usually iatrogenic and results from catheter needle insertion or tributaries of the saphenous vein remaining un-ligated in an in-situ bypass graft
• Biopsy is another cause of fistula formation but not usually in the legs.

Question 36

What are the main causes of non atherosclerotic diseases of the lower limb?

Answer 36

• Inflammatory disease
• Non inflammatory disease
• Inherited vascular conditions
• Congenital and developmental vascular conditions

Question 37

What is Burgers disease?

Answer 37

• (Thrombangitis Obliterans)
• its principal affect is in the extremities
• mostly the lower limbs.
• inflammatory arteritis which initially affects the small distal arteries

Question 38

What are the symptoms of burgers disease?

Answer 38

• produces severe symptoms such as
o rest pain
o ulceration
o gangrene in the feet or hands.

Question 39

How does burgers disease appear on ultrasound?

Answer 39

• The disease progresses proximally with tortuosity and segmental occlusion being visible with relatively normal appearing artery segments between.
• Imaging is used to demonstrate the distribution of arteries affected but the disease is primarily diagnosed and managed clinically.

Question 40

What is fibromuscular dysplasia?

Answer 40

• non inflammatory disease of the arteries
• may affect the arteries of the lower limbs
• more commonly identified in the internal carotid and/or renal arteries.

Question 41

What is Marfans syndrome?

Answer 41

• inherited syndrome where patients may form aneurysmal dilatation

Question 42

What is Ehlers Danlos syndrome?

Answer 42

• produce arteries that are fragile and may haemorrhage with a high degree of fatality.

Question 43

What is Pseudoxanthoma elasticum?

Answer 43

• less severe condition which may form non significant stenosis in the mid sized arteries such as the femoral artery.

Question 44

What are some Congenital and developmental vascular conditions ?

Answer 44

• Aortic coarctation
• stricture of the aorta and may occur in the thoracic or abdominal segments.
• Adventitial cystic disease
• an uncommon condition where cyst formation in the adventitia causes a characteristic stenosis or occlusion of the artery to produce symptoms of claudication.
• Popliteal entrapment
• results from a number of abnormal anatomical arrangements of the popliteal artery which may cause it to be externally compressed by the surrounding muscles or fibrous tissue to cause a stenosis during certain phases of limb movement during exercise.

Question 45

What are the common types of intervention to correct atherosclerotic lesions?

Answer 45

Angioplasty and stenting
Bypass graft
Embolectomy
Endarterectomy

Question 46

What are some common lower limb grafts?

Answer 46

o	Femoro-popliteal (Fem-Pop) , Above knee Fem-Pop,
o	Femoro-distal or femoro- tibial,
o	Aorto-bifemoral,
o	aorto-iliac
o	femoral to femoral cross-over

Question 47

What is a proximal or inflow graft?

Answer 47

• Grafts bypassing proximal disease

* such as the aorto-bifemoral or axillo-bifemoral graft

Question 48

What are proximal or inflow grafts made of?

Answer 48

• made of synthetic tube since vein is not considered large enough to cope with the high flow rates
• typically made of Dacron.

Question 49

What graft material is used for above the knee fem pop bypass?

Answer 49

• Synthetic grafts are used for this bypass as they have a higher patency rate than vein.

Question 50

What are Extra anatomic bypass grafts?

Answer 50

• grafts which are positioned outside the normal anatomic region of the arteries being bypassed.
• This usually occurs in the abdominal or thoracic region when the risk of open surgery is too great.

Question 51

What are Extra anatomic bypass grafts made of and what is their path?

Answer 51

• synthetic (usually Dacron) and are typically passed subcutaneously to their destination artery.

Question 52

What are common extra anatomic bypass grafts?

Answer 52

• The most common of these grafts are the axillo-bifemoral graft and the femoral-femoral cross-over graft

Question 53

What are distal bypasses usually made of?

Answer 53

• Grafts from arteries above the knee to the popliteal or tibial arteries are usually constructed of vein
• harvested from the patient at the time of surgery.
• Although not all grafts below the knee are vein grafts, they are preferred because of their higher patency rates.

Question 54

When are synthetic grafts used distally?

Answer 54

• A synthetic graft may be used if there is no suitable vein available or if the length of graft is too long and these are usually made of Poly Tetra Fluro Ethylene (PTFE).

Question 55

What is the the most common bypass graft?

Answer 55

• The femoro-popliteal graft below the knee

Question 56

How is a femoro-popliteal graft below the knee constructed?

Answer 56

• The vein is anastomosed to the common or superficial femoral artery and passed through the adductor canal to be anastomosed below the knee.

Question 57

What are the two bypass methods used for a a femoro-popliteal graft below the knee?

Answer 57

• Two distinct bypass methods are used
o insitu graft
o reversed graft.

Question 58

Describe the differences between the insitu and reversed graft

Answer 58

• The insitu graft mobilises the proximal and distal ends of the vein to anastomose to their respective arteries
• the reversed graft involves removing the vein and turning it around before placing it back in the leg and forming the anastomoses.
• Both grafts are commonly performed and have a good record for long term patency.

Question 59

Which veins are most commonly harvested for grafts?

Answer 59

the great saphenous vein
but the short saphenous, cephalic and basilic veins can also be harvested to create or extend the length of the graft.
The veins of the lower limb and upper limb are often assessed by ultrasound prior to surgery for size, length and patency.

Question 60

How is an embolus removed from a peripheral artery ?

Answer 60

• using a Fogarty catheter.
• This catheter is a hollow tube with an inflatable balloon on the end.
• The catheter is passed through the embolus and then inflated.
• Withdrawing the catheter with the balloon inflated enables the clot to be removed.

Question 61

Where is endarterectomy used in the leg?

Answer 61

• This can be performed in the common femoral artery and may involve the proximal segment of the superficial femoral or profunda femoris arteries.
• Like the carotid arteries, a long incision is made and the diseased artery is dissected from the remainder of the arterial wall.

Question 62

A patient presents to her general practitioner with pain in the right calf after playing four holes of golf. The pain decreases with rest but returns after playing two more holes. Describe the physical examination her doctor should perform and any diagnostic tests that should be requested.

Answer 62

• Assess pulses, colour, temperature, region of pain, health of skin, duration of pain, any recent injury, or arthritis of knee (Baker’s cyst).
• Treadmill exercise testing would determine if there were arterial causes for calf pain, may proceed to ultrasound Doppler to assess level and extent of arterial disease.

Question 63

List the important information you would need to demonstrate during a lower limb Doppler examination.

Answer 63

• peak systolic velocity (PSV);
• AP diameter;
• aneurysmal dilation;
• level and length of stenosis or occlusion;
• PSV ratio before and at stenosis;
• spectral broadening; and
• collateral vessels.

Question 64

List the information you are required to provide on lower limb Doppler worksheet.

Answer 64

• waveform type - triphasic, biphasic, monophasic;
• plaque drawn at appropriate level;
• description of plaque - calcific, mixed, hypoechoic;
• PSV at predetermined levels and any increase;
• ratios of PSV at stenosis compared with immediately proximal;
• level of stenosis relative to anatomical landmark and length; and
• technical quality - any regions unable to be assessed and reason.

Question 65

If the the waveform in the popliteal artery is low velocity and monophasic what does that indicate?

Answer 65

The preceding disease thus has had a significant haemodynamic effect.