Lower limb ischaemia is impaired blood flow into the leg. Mild impairment may not cause any symptoms. More significant limitation of blood flow allows enough blood into the leg at rest, but not enough during exercise; this causes intermittent claudication, a painful cramping pain in the muscles on walking. Severely restricted arterial blood flow causes pain at rest and progresses to ulcers and gangrene.
Lower limb ischaemia is classified according to severity (La Fontaine classification)
- Intermittent Claudication
- Rest pain
Atherosclerosis (hardening of the arteries)
accounts for the vast majority of lower limb ischaemia in the west. Presentation of limb ischaemia in a younger adult should prompt a search for causes of accelerated atherosclerosis and consideration of less common causes of lower limb ischaemia. These include:
- Aortic dissection
- Accelerated atherosclerosis (hyperlipidaemia, hyperhomocysteinaemia, AIDS)
- Buerger's Disease (common in male smokers in the middle/far east)
- Popliteal Entrapment (seen in athletes and may progress to permanent arterial damage if untreated)
- Fibromuscular Dysplasia (most commonly affects carotid and renal arteries but can narrow the iliac arteries in young adults)
- Cystic Adventitial Disease (the popliteal artery develops cysts that may connect to the knee joint)
- Persistent Sciatic Artery (associated congenital absence of normal lower limb arteries)
Atherosclerosis, intermittent claudication, critical limb ischaemia, aortic dissection and aortic aneurysms are all discussed in their own sections of the website (see Conditions Treated, Prevented and Cured).