Vascular: Peripheral Arterial Disease

Question 1

What is PAD?

Answer 1

Significant narrowing of the arteries distal to the arch of the aorta, most often due to atherosclerosis (rarely vasculitis), causing chronic limb ischaemia.

Most commonly affects the lower limbs, although upper limbs and gluteals can also be affected.

Question 2

Why does PAD cause intermittent claudication?

Answer 2

Atheroma in artery causes stenosis… muscle ischaemia… anaerobic metabolism releases lactate, K+ and substance P… pain and intermittent claudication

Question 3

In which vessels do atheromas usually form in PAD?

Answer 3

• superficial femoral artery (80%)
• aorto-iliac arteries (15%)
• calf arteries (5%)

Question 4

Suggest risk factors for PAD.

Answer 4

• smoking (x9)
• diabetes mellitus (x4)
• hypertension (x3)
• increased age
• obesity and physical inactivity
• family history

Question 5

Describe the 4 stages of chronic limb ischaemia.

Answer 5

Stage I: asymptomatic

Stage II: intermittent claudication

Stage III: ischaemic rest pain

Stage IV: ulceration, gangrene

Question 6

What are the features intermittent claudication?

Answer 6

• Walking impairment after fixed distance, e.g. fatigue, aching, cramping or pain in:
  
  • calf (80%)
  • calf, thigh and buttock (18%)
  • bilateral buttocks and thighs (2%)
• relieved by rest
• pain comes on more rapidly when walking uphill
• can occur in both legs, but is often worse in 1 leg

Question 7

What is Leriche’s syndrome?

Answer 7

Bilateral buttock and thigh pain + absent femoral pulses + male impotence.

Caused by aorto-iliac obstruction.

2% of PAD

Question 8

What are the features of ischaemic rest pain?

Answer 8

• severe unremitting pain in foot, esp. at night

- partially relieved by hanging foot out of bed

Question 9

What signs might a limb with PAD show?

Answer 9

• pale, cold, hairless, skin changes
• Buerger’s test +ve (Buerger’s angle <20degrees indicates severe ischaemia)
• ulceration or gangrene (severe PAD)
• weak or absent pulses

Question 10

Name 2 investigations you would perform to confirm PAD diagnosis?

Answer 10

1. arterial duplex USS: measure ABPI to assess blood flow at ankle, determine site of disease, indicate degree of stenosis and length of occlusion
2. MR angiography may be offered prior to revascularisation

Question 11

Which investigations would you perform in a full cardiovascular risk assessment?

Answer 11

1. Bloods
   - FBC: anaemia will aggravate PAD
   - ESR: inflammatory process, e.g. giant cell arteritis
   - UandEs: assess kidney function/CKD
   - lipid levels
   - HbA1c
   - thrombophilia screen and serum homocysteine levels in Pts <50yrs
2. Bedside tests
   - ECG

Question 12

How should a Pt with PAD be managed?

Answer 12

Lifestyle changes:

• smoking cessation
• exercise
• weight reduction in overweight

Pharmacology:

• statins: maintain LDL <1.8 mmol/L
• anti-hypertensives (reduced BP may worsen claudication in short term)
• DM management
• ACEi: reduce cardiovascular morbidity and mortality
• anti-platelets, e.g. aspirin or clopidogrel: reduce vascular death
• Naftidrofuryl oxalate (peripheral vasodilator): treatment of intermittent claudication

Surgery (disabling claudication, critical limb ischaemia, weak/absent femoral pulses):

• endovascular revascularisation
• bypass surgery
• amputation: 1-2% (5% of diabetics)

Question 13

Suggest possible complications of PAD.

Answer 13

1. acute limb ischaemia (thrombosis or embolism) - 5-10%
2. infection and poor healing of tissue (reduced blood supply)
3. ulceration and gangrene

Question 14

What is the prognosis for Pts with intermittent claudication?

Answer 14

• Most continue to have stable claudication
• 10-20% develop worsening symptoms
• 5-20% develop critical limb ischaemia
• amputation eventually required in 1-3%

50% 5yr mortality, 70% 10yr mortality