Peripheral Arterial Disease (PAD)

Epidemiology of PAD

• Approximately 20% of middle-aged people have Peripheral Arterial Disease (PAD), but only one-quarter of these individuals will have symptoms.

Pathophysiology of PAD

• Most cases of PAD are due to atherosclerosis.
• The risk factors for PAD are similar to those for coronary artery disease, including smoking, diabetes, hyperlipidaemia, and hypertension.
• Plaque rupture is responsible for the most serious manifestations of PAD, often occurring in asymptomatic plaques.

Mechanism of Injury

Haemodynamic

• A 70% reduction in arterial diameter (critical stenosis) is required to reduce flow at rest.
• Less severe stenosis may become critical during exertion (e.g., walking).
• Haemodynamic injury has a relatively benign course due to collateralisation.

Thrombotic

• Occlusion of a long-standing critical stenosis may be asymptomatic due to collateralisation.
• Acute rupture and thrombosis of a non-haemodynamically significant plaque usually has severe consequences.

Atheroembolic

• Symptoms depend on embolic load and size.
• Examples include carotid disease (TIA or stroke) and peripheral arterial disease (blue toe/finger syndrome).

Thromboembolic

• Usually secondary to atrial fibrillation.
• Thromboembolic injury has dramatic consequences due to the large thrombus load, which often occludes a major, previously healthy, non-collateralised artery suddenly and completely.

Clinical Features

• Clinical manifestations depend on the anatomical site.