Blood clot which forms in an artery

Aetiology

Risk factors

Factors that cause damage to endothelium, increase in foamy macrophages and platelet activation:

• Hypertension
• Smoking
• High cholesterol
• Diabetes mellitus

Pathophysiology

Atherosclerosis

• Damage to endothelium causes recruitment of ‘foamy’ macrophages rich in cholesterol, resulting in the formation of cholestrol-rich plaques
• Stable plaques result in stable angina and intermittent claudication
• Unstable plaques result in stroke, unstable angina or myocardial infarction
  • Plaques rupture, platelets are recruited and cause acute thrombosis → sudden onset of symptoms
  • Leads to acute organ ischaemia and infarction

Platelets and arterial thrombosis

1. Plaque ruptures - more likely in the high pressure environment of arteries
2. Exposed endothelium and release of Von Willebrand factor and other proteins to which platelets have receptors → platelet adhesion to the site of injury
3. Platelets become activated - release granules that activate coagulation and recruit other platelets to developing platelet plug (e.g. ADP, thrombin, and thromboxane A2)
4. Platelet aggregation via membrane glycoproteins (GPIIbIIa and fibrinogen)

Clinical features

• As stroke/ACS