Metabolic disorders that are characterized by high levels of lipids in the blood. Hyperlipidaemias may be inherited or associated with another disorder, such as hypothyroidism, diabetes mellitus, kidney failure, or Cushing’s syndrome. They may also be a result of use of corticosteroid drugs. Hyperlipidaemias are associated with atherosclerosis and coronary artery disease.The signs depend on the type of hyperlipidaemia and may include fatty nodules in the skin or over joints, and a white line around the rim of the cornea.
Diagnosis depends on blood tests.
Treatment aims to reduce blood lipid levels, usually by a low-fat diet and lipid-lowering drugs.
A wide range of disorders can disrupt the heart’s action.
In general, genetic factors do not play a large part in causing heart disorders, however they do contribute to the hyperlipidaemias that predispose a person to atherosclerosis and coronary artery disease. Structural abnormalities in the heart are among the most common birth defects (see heart disease, congenital).
Infections after birth may result in endocarditis or myocarditis. Tumours arising from the heart tissues are rare. They include noncancerous myxomas and cancerous sarcomas.
The heart muscle may become thin and flabby from lack of protein and calories. Thiamine (vitamin B1) deficiency, common in alcoholics, causes beriberi with congestive heart failure. Alcohol poisoning over many years may cause a type of cardiomyopathy. Obesity is an important factor in heart disease, probably through its effect on other risk factors, such as hypertension, diabetes, and cholesterol.
The coronary arteries may become narrowed due to atherosclerosis, depriving areas of heart muscle of oxygen. The result may be angina pectoris or, eventually, a myocardial infarction.
Some drugs, such as the anticancer drug doxorubicin, tricyclic antidepressants, and even drugs used to treat heart disease, may disturb the heartbeat or damage the heart muscle.
Many common and serious heart disorders may be a complication of an underlying condition, such as cardiomyopathy or a congenital defect. Such disorders include cardiac arrhythmia, some cases of heart block, and heart failure. Cor pulmonale is a failure of the right side of the heart as a consequence of lung disease.... heart, disorders of
Accumulation of cholesterol and other fatty substances (lipids) in the walls of arteries, causing them to narrow. Atherosclerosis can affect arteries in any area of the body and is a major cause of stroke, heart attack (see myocardial infarction), and poor circulation in the legs. The arteries become narrowed when fatty substances, such as cholesterol, that are carried in the blood accumulate on the inside lining of the arteries and form yellow deposits called atheroma. These deposits restrict blood flow through the arteries. In addition, the muscle layer of the artery wall becomes thickened, narrowing the artery even more. Platelets (tiny blood cells responsible for clotting) may collect in clumps on the surface of the deposits and initiate the formation of blood clots. A large clot may completely block the artery, resulting in the organ it supplies being deprived of oxygen.
There are usually no symptoms in the early stages of atherosclerosis. Later, symptoms are caused by reduced or total absence of a blood supply to the organs supplied by the affected arteries. If the coronary arteries, which supply the heart muscle, are partially blocked, symptoms may include the chest pain of angina. If there is complete blockage in a coronary artery, a sudden, often fatal, heart attack may occur. Many strokes are a result of atherosclerosis in the arteries that supply blood to the brain. If atherosclerosis affects the leg arteries, the 1st symptom may be cramping pain when walking due to poor blood flow to the leg muscles. If the condition is associated with an inherited lipid disorder (see hyperlipidaemias), fatty deposits may develop on tendons or under the skin in visible lumps.
The risk of developing atherosclerosis is determined largely by the level of cholesterol in the bloodstream, which depends on dietary and genetic factors. Athersclerosis is most common in Western countries, where most people eat a diet high in fat. Some disorders such as diabetes mellitus can be associated with a high cholesterol level regardless of diet. Blood flow through an artery can be investigated by angiography or Doppler ultrasound scanning.
The best treatment for atherosclerosis is to prevent it from progressing by following a healthy lifestyle. This includes eating a low-fat diet, not smoking, exercising regularly, and maintaining the recommended weight for height. These measures lead to a lower-than-average risk of developing significant atherosclerosis. People found to have high blood cholesterol but who are otherwise in good health will be advised to adopt a low-fat diet. They may also be given drugs that decrease blood cholesterol levels (see lipid-lowering drugs). For people who have had a heart attack, research has shown that there may be a benefit in lowering blood cholesterol levels, even if the level is within the average range for healthy people.
People who have atherosclerosis and are experiencing symptoms of the condition may be prescribed a drug such as aspirin to reduce the risk of blood clots forming on the damaged artery lining.
Surgical treatment such as coronary angioplasty (see angioplasty, balloon) may be recommended for those people thought to be at high risk of severe complications. If blood flow to the heart is severely obstructed, a coronary bypass operation to restore blood flow may be carried out.... atherosclerosis
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