Peripheral arterial disease (PAD)

Question 1

Why does PAD occur?

Answer 1

Due to atherosclerosis causing stenosis of arteries via a multifactorial process involving modifiable and non-modifiable risk factors

Question 2

Pathophysiology of PAD

Answer 2

Oxygen supply/demand imbalance and ischaemia is the basic underlying pathophysiology

Stress induced physiological malfunction
First presentation
- Exercised induced angina
- Intermittent claudication

Structual and functional breakdown

• Ischaemic cardiac failure
• Critical limb ischaemia
• Vascular dementia

Infarcation
Severe cases where tissues are starting to die
- Gangrene

Question 3

Signs and symptoms of PAD

Answer 3

Symptoms:

• Cramping pain in calf, thigh or buttock after walking for given time (claudication distance) and relieved on rest
• Calf claudication = femoral disease
• Buttock caludication = iliac disease
• Ulceration, gangrene
• Foot pain at rest - better hanging foot off bed
• Young heavy smokers are at risk of Buerger’s disease

Signs

• Absent femoral, popliteal or foot pulses
• Cold, white legs
• Atrophic skin
• Punched out ulcers (often painful)
• Postural/dependent colour change
• Capillary filling time >15 seconds in severe ischaemia

Question 4

Common presentations of PAD?

Answer 4

1. Intermittent claudication - chief presentation (10% prevalence) - due to lactic acid formation causing pain while walking
2. Critical leg ischaemia - rest pain, normally nocturnal (relieved by hanging leg off bed)
3. Acute limb ischaemia - sudden cessation of blood supply blocking femoral artery in leg (leg doesn’t have. time to adapt and create collateral vessels and limb will. die if not treated) - commonest cause is thrombosis, followed by trauma.

Question 5

Investigations for PAD?

Answer 5

Investigate the pathophysiology

• Blood glucose - exclude DM
• Lipids
• Vasculitic screen
• BP

Image the vessels

• Colour Duplex Ultrasound* - first line - very good and non invasive (technician dependent)
• CT/MRA - cross sectional imaging for extent and location of stenoses and quality of distal vessels if considering intervention

Question 6

Treatment for PAD?

Answer 6

• Risk factor modification most important (HTN, smoking cessation is vital, BP, high cholesterol)*
• Revascularisation for ‘critical ischaemia’

Risk factor modification

• Aim is to reduce risk of death from MI or stroke and relieve symptoms
• Exercise to point of pain and weight reduction
• Control HTN, DM, hyperlipidaemia
• Antiplatelet therapy - clopidogrel advised as first line

Revascularisation
If conservative measures have failed and PAD is severely affecting the pt QOL or becoming limb-threatening, intervention is required.
- Percutaneous transluminal angioplasty = Balloon and stent - pushes the plaque against the wall of the artery and opens it up
- Surgical reconstruction = Bypass the artery (eg. femoral popliteal artery bypass)

Amputation

• If we cannot increased blood supply or extent of damage is severe
• < 3% of patients with intermittent claudication require amputation within 5 years (increase in diabetes).

Question 7

6 P’s of acute limb ischaemia?

Answer 7

• Pain
• Pallor
• Pulseless
• Paralysis
• Paraesthesia
• Perishing cold