ATHEROMA.
Pathological changes.
Atheromatous plagues are patchy changes that develop in the tunica intima of large and medium-sized arteries. Initial changes show a fatty streak in the artery wall. Mature plagues consist of accumulations of cholesterol and other lipid compounds,excess smooth muscle and fat-filled monocytes(foam cells). The plague is covered with a fibrous cap. As plagues grow they spread along the artery wall forming swellings that protrude into the lumen. Eventually the whole thickness of the wall and long sections of the vessel may be affected. Plagues may rupture,exposing subintimal materials to the blood. This may cause thrombosis and vasospasm and will compromise blood flow.
Arteries most commonly involved are those in the heart,brain,kidneys,small intestine and lower limbs.
CAUSES OF ATHEROMA.
Fatty streaks present in artery walls of infants are usually absorbed but their incomplete absorption may be the origin of atheromatous plaques in later life.
The presence of plaques is considered to be a disease of older people because it is usually in these age groups that clinical signs appear. The predisposing factors are:
- Heredity.
- Obesity.
- Diet.
- Smoking cigarettes.
- Diabetes mellitus.
- Sedentary lifestyle.
Atheromatous plaques may cause partial or complete obstruction of an artery. The blockage may be complicated by clot formation. The consequences of this depend on the site and size of an artery involved and the extent of collateral circulation. Commonly the arteries affected are those in the heart,abdomen and pelvis.
This may cause complications like haemorrhage,aneurysm or thrombosis and infarction.
