heart disease, any of several abnormalities of the heart and its function in maintaining blood circulation. Heart disease is the cause of approximately half the deaths in the United States each year. Among the most common causes of heart disease are degenerative changes in the coronary blood vessels, infectious diseases, and congenital heart disease congenital heart disease, any defect in the heart present at birth. There is evidence that some congenital heart defects are inherited, but the cause of most cases is unknown.
..... Click the link for more information. . Congenital defects result from abnormal development of the fetal heart, commonly in the valves or septa. Such defects can be precipitated by environmental conditions in the uterus, such as the presence of the rubella rubella or German measles, acute infectious disease of children and young adults. It is caused by a filterable virus that is spread by droplet spray from the respiratory tract of an infected individual.
..... Click the link for more information. virus, or they can be inherited. Infectious diseases acquired after birth, such as rheumatic fever rheumatic fever (r
..... Click the link for more information. , syphilis syphilis (sĭf`əlĭs), contagious sexually transmitted disease caused by the spirochete Treponema pallidum
..... Click the link for more information. , and endocarditis endocarditis (ĕn'dōkärdī`tĭs)
..... Click the link for more information. , can also damage the valves of the heart. In addition, the heart muscle itself can be affected: hypertensive heart disease (see hypertension hypertension or high blood pressure, elevated blood pressure resulting from an increase in the amount of blood pumped by the heart or from increased resistance to the flow of blood through the small arterial blood vessels (arterioles).
..... Click the link for more information. ) can cause it to enlarge, and it can become inflamed by rheumatic fever. Arteriosclerotic depositions in the coronary arteries result in the narrowing of these vessels, causing insufficient blood flow and oxygen to the heart muscle, a condition known as coronary artery disease coronary artery disease, condition that results when the coronary arteries are narrowed or occluded, most commonly by atherosclerotic deposits of fibrous and fatty tissue.
..... Click the link for more information. . The characteristic radiating chest pain, angina pectoris angina pectoris (ănjī`nə pĕk`tərĭs)
..... Click the link for more information. , is the most prominent symptom of this condition. Coronary arteries already narrowed by arteriosclerosis are made susceptible to blockage by a clot (coronary thrombosis thrombosis (thrŏmbō`sĭs), obstruction of an artery or vein by a blood clot (thrombus).
..... Click the link for more information. ), causing the death of the heart muscle supplied by the affected artery, a life-threatening event called a myocardial infarction myocardial infarction or heart attack is usually caused by a blockage in one of the coronary arteries that supply blood to the heart muscle. The blockage typically occurs when a blood clot (see thrombosis ) lodges in an area already narrowed by arteriosclerosis ; other
..... Click the link for more information. , or heart attack. Hypertensive, coronary, congenital, and other forms of cardiovascular disease, either singly or in combination, can lead to a state in which the heart is unable to expel sufficient blood for the metabolic demands of the body, ultimately resulting in congestive heart failure congestive heart failure, inability of the heart to expel sufficient blood to keep pace with the metabolic demands of the body. In the healthy individual the heart can tolerate large increases of workload for a considerable length of time.
..... Click the link for more information. . Disturbances in the normal heartbeat, called arrhythmias arrhythmia (ārĭth`mēə), disturbance in the rate or rhythm of the heartbeat.
..... Click the link for more information. , can occur by themselves or in conjunction with other heart problems, for example infarction affecting the area of the heart that controls the heartbeat.

heart disease

Any disorder of the heart. Examples include coronary heart disease, congenital heart disease, and pulmonary heart disease, as well as rheumatic heart disease (see rheumatic fever), hypertension, inflammation of the heart muscle (myocarditis) or of its inner or outer membrane (endocarditis, pericarditis), and heart valve disease. Abnormalities of the heart's natural pacemaker or of the nerves that conduct its impulses cause arrhythmias. Some connective tissue diseases (notably systemic lupus erythematosus, rheumatoid arthritis, and scleroderma) can affect the heart. Heart failure may result from many of these disorders.