DEFINITION OF ATHEROMA
Atheroma is a fatty plaque/ emboli originating inside arteries. Atheroma is a medical term for the build-up of material that adheres to arteries. Routes most commonly involved are-
- HEART
- BRAIN
- KIDNEYS
- SMALL INTESTINE
- LOWER LIMB
The plague/ material comprises fat, cholesterol, proteins, calcium, connective tissue, inflammatory cells, and other substances circulating in the body. There may be multiple small emboli or one or more large ones.
Emboli may break off, travel in the bloodstream, and lodge in small arteries distal to the clot, causing slight infractions. Atheromas grow over time and may lead to coronary artery disease, heart attack, or heart stroke.
PATHOLOGICAL CHANGES IN ATHEROMA
Atheromatous plaques are patchy changes that develop in the tunica intima of large and medium-sized arteries. They consist of accumulations of cholesterol and other lipid compounds, excess smooth muscle, and fat-filled monocytes (foam cells). The plaque is covered with a fibrous cap.
As plaques develop they speed along the artery wall foaming swellings that protrude into the lumen. Eventually, the whole thickness of the wall and long sections of the vessel may be affected. Plaques may rupture, exposing subintimal materials to the blood. This may cause thrombosis and vasospasm and will compromise blood flow.
CAUSES OF IT heart disease
PREDISPOSING FACTORS IN ATHEROSCLEROSIS
- Heredity- family history
- Obesity
- Gender- males are more susceptible than females.
- Diet- high in refined carbohydrates saturated fats and cholesterol.
- Increasing age
- Smoking cigarettes
- diabetes mellitus
- Excessive emotional stress
- Hypertension
- Sedentary lifestyle
- Hyperlipidemia
- Excessive alcohol consumption
- Physical inactivity
The origin of atheromatous plaques is uncertain. Fatty streaks present in the artery walls of infants are usually absorbed despite their incomplete absorption and may be the origin of atheromatous plaques in later life.
Atherosclerosis is considered a disease of older people because it is usually in these age groups that clinical signs appear. However, plaques start to form in childhood in developed countries.
The incidence of atheroma is widespread in developed countries. Wh atheromatous plaques develop is not clearly understood, but the predisposing factors appear to exert their effects over a long period. This may mean that the development of atheroma can be delayed or even arrested by a change in lifestyle.
EFFECTS
Atheromatous plaques may cause partial or complete obstruction of an artery. The blockage may be complicated by clot information. The consequences of this depend on the site and size of the artery involved and the extent of collateral circulation. Commonly the arteries affected are those in the heart, abdomen, and pelvis.
1- NARROWING OF AN ARTERY
The tissue distal to the narrow point becomes ischemic. The cells may receive enough blood to meet their minimum lacks, but not enough to cope with a boost in metabolic rate, ex – when muscle activity is increased. This causes acute cramp-like ischemic pain. Cardiac muscle and skeletal muscles of the lower limb are most commonly affected. Ischemic pain In the heart is called angina pectoris, and in the lower limbs, intermittent claudication.
2- OCCLUSION OF AN ARTERY
When an artery is completely blocked, the tissues it supplies rapidly undergo degeneration and die from ischemia, which leads to an infarction. If a major artery supplying a large amount of tissue is affected, the consequences are likely to be more severe than if the obstruction occurs in a central vessel. If the tissue is well provided with collateral circulation (such as the circulus arteries provide in the brain), tissue damage is less than if there are few collateral vessels ( which may be the case In the heart ).
When a coronary artery is occluded myocardial infarction occurs. Occlusion of arteries in the brain causes cerebral ischemia and this leads to cerebral infarction (stroke).
COMPLICATIONS OF ATHEROMA
1- THROMBOSIS AND INFARCTION
If the fibrous cap overlying a plaque breaks down, platelets are activated by the damaged cells, and a blood clot forms, blocking the artery and causing ischemia and infarction. Emboli may break off, travel in the bloodstream, and lodge in small arteries distal to the clot, causing small infarcts.
2- HAEMORRHAGE
Plaques may become calcified, making the artery brittle, rigid, and unresponsive to rises in blood pressure. They may rupture, causing hemorrhage.
3- ANEURYSM
When the arterial wall is weakened by the spread of the plaque between the layers of tissue, a local dilation (aneurysm) may develop. This may lead to thrombosis and embolism, and embolism or the aneurysm may rupture causing severe hemorrhage. The most common sites affected by atheroma are the aorta and pelvic arteries.
TREATMENTS FOR THE ATHEROMA
Treatment is by prevention, but some symptoms may be ameliorated by drug therapy (ex-angina by glyceryl trinitrate) or by surgical bypass of the arterial obstruction.