Pathologies of the heart and its blood vessels. Almost all cardiovascular disorders eventually progress to serious debilitating stages characterized by heart failure (reduced pumping function), dysrhythmias (abnormal electrical rhythms), and sudden death. Coronary atherosclerosis, a disease causing obstruction of the arteries that supply nutrient blood to heart muscle, is the leading cause of cardiovascular mortality. Hypertension (high blood pressure) is another important cause. Valvular heart disease, cardiomyopathies (disease of heart muscle), and congenital heart disease are less common.
Coronary disease
The coronary arteries carry oxygen and nutrients to the heart muscle. Obstructive disease of these arteries is almost always caused by atherosclerosis, a pathologic process that produces a fatty deposition and thickening of the inner surface of the artery, eventually restricting the flow of blood through the artery. The capacity to deliver blood to the heart muscle is increasingly limited. Heart muscle function declines, and the individual experiences characteristic discomfort in the chest called angina pectoris. Angina pectoris is relieved by rest or medications that improve the balance between myocardial oxygen demands and coronary blood (and oxygen) supply. See also Arteriosclerosis.
Coronary artery disease can be complicated by the abrupt formation of a blood clot (thrombus) at the site of an atherosclerotic plaque. When the artery is incompletely obstructed, unstable angina or angina at rest may develop. This is a dynamic condition that is complicated by spasms of the involved artery. When the artery becomes completely occluded, a myocardial infarction or heart attack results, causing irreversible injury to the heart muscle (myocardium) supplied by the occluded artery. Complications and deaths are directly related to the size of the infarction. See also Infarction.
Several characteristics or risk factors are associated with a high likelihood that coronary disease will develop. They include cigarette smoking, elevated levels of blood cholesterol, hypertension, and a family history of the disease. Other risk factors include diabetes, a lack of exercise, and obesity. By modifying or eliminating these factors, the risk of developing coronary disease can be reduced. See also Cholesterol; Diabetes; Hypertension; Obesity.
Hypertensive heart disease
High blood pressure results in an excessive cardiac work load. The heart responds to the high pressure through a growth process called hypertrophy. As a result, the mass of the heart muscle is increased, and the work requirement of each unit of heart muscle returns toward normal. Unfortunately, this compensatory increase in cardiac mass eventually results in heart failure and other morbid cardiovascular events. Antihypertensive drugs are effective in the treatment of hypertension and its consequences.
Valvular heart disease
Heart valves ensure an efficient forward blood flow through the heart. Disease of these valves can be caused by rheumatic fever or degenerative noninflammatory processes.
Congenital heart disease
About 1% of all newborns have a structural abnormality of the heart or adjacent blood vessels. Such congenital heart disease can be caused by maternal rubella, or it may be inherited, as in Down syndrome. However, the cause of most congenital heart disease is unknown. Defects in the walls between the atria and the ventricles are the most common congenital malformations. A blood shunt between the pulmonary artery and the aorta also causes a recirculation of oxygenated blood through the lungs; this defect occurs when there is an abnormal persistence of the fetal connection between the two vessels. See also Congenital anomalies; Down syndrome.
Cardiomyopathies
Heart muscle disease that is caused by excessive intake of alcohol, some drugs, or infections may cause depression of myocardial function and cardiac enlargement. The resulting dilated cardiomyopathy causes shortness of breath and fatigue. Less commonly, inappropriate growth of the myocardium has occurred in the absence of enlargement of the chamber. This hypertrophic cardiomyopathy causes anginalike chest pain, shortness of breath, and fainting spells.
Heart failure
Congestive heart failure is a clinical syndrome that consists of shortness of breath, fatigue, and retention of fluid. It is caused by failure of the heart as a pump; thus, heart failure can be caused by almost any form of heart disease.
Sudden cardiac death
Most cases of sudden death result from inadequate pumping and low cardiac output during a rapid cardiac dysrhythmia, such as ventricular tachycardia or ventricular fibrillation. See also Heart (vertebrate).
