Atherosclerosis Complications And Clinical Sequelae

Atherosclerosis: is a slowly progressive disease of arteries, marked by elevated fibrofatty intimal plaques, formed by lipid deposition, smooth muscle cell proliferation and synthesis of extracellular matrix in the intima.

There is usually some form of plaque disruption with:

• Ulceration of luminal surface

• Atheromatous embolism due to material release from ulcerated atheroma

• Thrombosis on damaged endothelial surface; may occlude the vessel, embolise or become organised and incorporated into the original plaque

• Haemorrhage into the plaque with sudden increase in size; due to influx of blood through ruptured endothelium or to rupture of new vessels (vasa vasorum) formed in the plaque

• Calcification is a common and early complication making the wall of the vessel rigid

• Aneurysm formation may follow atrophy and fibrosis of the media which then stretches

Thrombosis on a plaque, haemorrhage into a plaque or atheromatous embolism may all cause severe narrowing or occlusion of an artery giving rise to ischaemia or infarction of the part supplied by the affected artery.

Clinical features:

Atherosclerosis is asymptomatic for decades until it causes disease by the following mechanisms:

• Insidious narrowing of vascular lumens (e.g. gangrene of the lower leg because of stenosing atherosclerosis in the popliteal artery)

• Plaque rupture followed by superimposed thrombus causing sudden occlusion of lumen (e.g. myocardial infarction precipitated by thrombotic occlusion of disrupted coronary arterial atheroma)

• Providing a source of embolic debris, know as atheroembolism (e.g. renal infarction resulting from cholesterol emboli originating in an ulcerated atherosclerotic aortic plaque)

• Weakening the wall of a vessel followed by aneurysm formation and possibly rupture (e.g. an abdominal aortic aneurysm)

Symptomatic atherosclerotic disease most often affects the:

• Heart (infarction)

• Brain (stroke)

• Kidneys (ischaemia)

• Lower extremities (gangrene)

• Small intestine (ischaemia of mesenteric vessels)

It is the complications of atheroma which are responsible for most of the effects.

Category: Pathology Notes