PAD

Question 1

Name the 3 compartments of the arterial supply to the lower limb.

Answer 1

Aortoiliac
Femoropopliteal
Crural

Question 2

Describe the aortoiliac compartment of the lower limb arterial supply

Answer 2

DIAGRAM

Question 3

Describe the femoropopliteal compartment of the lower limb arterial supply

Answer 3

DIAGRAM

Question 4

Describe the crural compartment of the lower limb arterial supply.

Answer 4

DIAGRAM

Question 5

What is the adductor canal?

Answer 5

It is an aponeurotic compartment located in the middle 3rd of the thigh. It runs from the apex of the femoral triangle to an opening in the adductor magnus muscle known as the adductor hiatus.

Question 6

What is the definition of PAD?

Answer 6

PAD comprises those entities that obstruct blood flow to the arteries with the exception of coronary and intracranial vessels.

Question 7

What are the two types of PAD?

Answer 7

Organic and functional

Question 8

Describe organic PAD.

Answer 8

This describes PAD that has resulted from physical damage to the blood vessel structure due to inflammatory changes (chronic), plaques (atherosclerosis/embolism) and tissue damage.

Question 9

Describe functional PAD.

Answer 9

This describes PAD that does not result from physical damage to the blood vessel structure. Instead, it is caused by vasospasm (vessels widen and narrow in response to factors such as temperature) that reduce blood flow due to the narrowing of blood vessels.

Question 10

What are the non-modifiable risk factors of PAD?

Answer 10

Sex (males at higher risk)
Family history
Increasing age

Question 11

What are the modifiable risk factors of PAD?

Answer 11

Hyperlipidaemia (independently associated with PAD)
Hypertension
Smoking ([Erb, 1991]- found that smokers are 3 x more at risk of intermittent claudication)
Type 2 diabetes (higher risk of developing large vessel atherosclerotic occlusive disease)
Obesity
Pro-Thrombotic tendencies

Question 12

What is claudication?

Answer 12

It is pain in the muscle of the leg with ambulation (light exercise).

Question 13

What causes PAD?

Answer 13

Atherogenesis- response to injury hypothesis.

Question 14

What are the three stages of the response to injury hypothesis?

Answer 14

Lesion, progression of lesion and plaque complications.

Question 15

Describe the first stage of atherogenesis

Answer 15

First stage involves the recruitment of mononuclear leucocytes to the intimal layer of the vessel wall through diapedesis  inflammation. This inflammatory process relies on two groups of adhesion molecules; selectins (transient deposition of leucocytes on endothelium) and immunoglobins (responsible for more sustained adherence of leucocytes to the endothelium). Once leucocytes have migrated, they accumulate lipids and present a fatty streak and ongoing accumulation develops a more advanced plaque.

Question 16

Describe the second stage of angiogenesis

Answer 16

Second stage is where after leucocyte adherence, chemoattractant chemokines potentiate migration of cells into the intima. The plaque becomes more fibrous as smooth muscle cells accumulate within the lesion and elaborate extracellular macromolecules (collagen, elastin, prostaglandins) to form a fibrous matrix.

Question 17

Describe the third stage of angiogenesis

Answer 17

Third stage is the formation of a complicated and ‘unstable’ plaque which is initiated by exposure to subintimal thrombogenic substances to the bloodstream. For example, platelets after adherence release a variety of antagonists for example adenosine which allow the platelets to undergo structural changes that form a platelet plug which can build and occlude the vessel ischaemia, turbulence, aneurysms, ruptures etc.

Question 18

What are the two types of open surgery for PAD? Describe the difference.

Answer 18

Endarterectomy- appropriate for localised disease such as the narrowing of the aorta and/or iliac arteries. This surgical procedure removes the atherosclerotic plaque in the lining of the artery constricted by the build-up of deposits. It is carried out by openly separating the plaque from the arterial wall.

Bypass- the great saphenous vein is the conduit of choice for arterial bypass. The vein contains valves which are essential for its normal function of preventing the back flow of blood