The Heart

What Is Heart Disease?

The human heart is built for amazing endurance -- billions of beats in an average lifetime. But like any other part of the body, it is vulnerable to breakdowns. Heart problems vary widely in their nature and severity. They may be transient or chronic, slow-developing or sudden, inconvenient or deadly.

Some types of heart disease, closely linked to diet and lifestyle choices, are preventable; others are due to genetic inheritance, infections, or other uncontrollable factors. Two of every five Americans will ultimately die of heart disease. The daily toll is approximately 2,500 people. Fortunately, the death rate is declining steadily (by about 40% since 1960), thanks largely to improved medical care and widespread public education about risk factors.

The following is a list of the most common types of heart disease:

Coronary Artery Disease

Coronary artery disease, the most common of all heart problems, is characterized by blockages in the coronary arteries that result in a reduction in blood flow to the heart muscle, depriving it of vital oxygen. Usually, the disease stems from atherosclerosis, a condition sometimes called hardening of the arteries.

Severe coronary artery disease can lead to heart failure. Coronary heart disease can also result in painful episodes of angina (chest pain due to coronary disease) or a heart attack or, in the worst case, sudden death.

There are many things that can put a person at higher risk of developing coronary disease:

• Family history
• Gender -- Men are more apt to be affected than women.
• Genetics
• Age -- For both men and women, the likelihood of heart disease increases significantly after the age of 65. The risk rises sharply in women after menopause.
• Abnormal cholesterol levels -- high blood levels of "bad" (LDL cholesterol) or low levels of "good" (HDL cholesterol)
• High blood pressure (hypertension)
• Smoking
• Obesity
• Sedentary lifestyle
• Stress

Heart Arrhythmias

• Arrhythmias are disturbances in the heart's normal beating pattern. The irregularities occur in many forms, each with its own potential causes and treatments. Serious arrhythmias are a frequent consequence of other heart diseases but may also occur independently.

Heart Failure

• The term heart failure does not mean that the heart has "failed" or stopped working. Rather, it means that the heart does not pump blood as well as it should. Heart failure is usually caused by coronary artery disease, but it can also be caused by thyroid disease, high blood pressure, or heart muscle disease (cardiomyopathy) among other conditions.

Heart Valve Disease

The heart has four valves (the pulmonary, mitral, tricuspid and aortic) that open and close to direct blood flow between the heart's four chambers, the lungs and connected blood vessels. A defective valve may fail either to open properly, obstructing blood flow (stenosis or obstruction), or to close properly (regurgitation or insufficiency), allowing blood leakage. Congenital heart disease and various infections, including rheumatic fever, are among the causes of valve disorders.

Endocarditis is an inflammatory condition that affects heart valves. This disease is an infection or inflammation of the endocardium, the innermost layer of heart tissue that lines the chambers and valves. It is usually caused by bacterial infection, with the staphylococcus and streptococcus bacteria. Bacteria may enter the blood and take root in the heart during illness, after surgery, or as a result of intravenous drug use. Endocarditis tends to strike people with pre-existing valve problems. The disease can be fatal if left untreated, but it can generally be cured with antibiotics. If heart valves are seriously damaged as a result of endocarditis, valve replacement surgery may be needed.

Rheumatic heart disease, another type of heart disease affecting valves, was very common earlier in this century but is now largely preventable with antibiotic treatment, although it still occurs. The disease stems from damage to the heart muscle and valves caused by rheumatic fever, which itself is associated with strep throat and scarlet fever. Symptoms of rheumatic heart disease are usually delayed for many years after infection.

Pericardial Disease

• Any disease of the pericardium, the sac surrounding the heart, is called a pericardial disease. One of the more common is a condition called pericarditis. It is usually caused by viral infection, diseases such as lupus or rheumatoid arthritis, or trauma to the pericardium. Pericarditis often follows open-heart surgery.

Cardiomyopathy (Heart Muscle Disease)

• Diseases of the heart muscle, or myocardium, are collectively referred to as cardiomyopathies. When diseased, the myocardium becomes abnormally stretched, thickened or stiff. Among the many potential causes of cardiomyopathy are genetic heart conditions, reactions to certain drugs or toxins such as alcohol and viral infections. Sometimes, chemotherapy for cancer causes cardiomyopathy. Often, the precise cause of cardiomyopathy is unknown. In any event, either the heart muscle becomes too weak to pump efficiently or stiffening prevents adequate filling of the heart.
• When cardiomyopathy progresses to the point of causing serious arrhythmias or heart failure, the outlook for long-term survival is poor. Sudden death is another outcome associated with some cardiomyopathies, including idiopathic (meaning a disease with no known cause) hypertrophic subaortic stenosis, which has claimed the lives of a few prominent young athletes.
• If cardiomyopathy can be detected and treated early enough, either with drugs or with transplant surgery, symptoms can often be controlled and heart failure averted for many years.

Congenital Heart Disease

• Should anything go wrong in the formation of the heart during prenatal development, a baby will be born with one or more congenital heart defects. Such defects are quite common, occurring in about seven of every 1,000 babies.
• The exact causes of defects are generally hard to pin down; genes and environmental factors inside the mother's body may both contribute. Chromosome abnormalities, including the one that causes Down syndrome, have been linked to many congenital heart defects. Infections contracted during pregnancy by the mother, such as rubella, may also result in congenital heart defects for the child. Congenital heart defects range widely in their effects. Some are apparent immediately, but others do not produce noticeable symptoms until adulthood.
• Among the most common types are septal defects, or holes in septum, which is the wall dividing the left and right sides of the heart. If a septal defect is big enough to cause problems, it can be patched surgically. Another frequently seen defect is pulmonary stenosis, a condition in which one of the four heart valves -- the pulmonary valve -- is so narrow that blood flow to the lungs is restricted. With surgery, the valve can be pried open or replaced. In some babies, a small fetal blood vessel known as the ductus arteriosus fails to close at birth as it should. This condition, known as patent ductus arteriosus, allows some blood that is headed for the body via the aorta to leak back into the pulmonary artery, placing the heart under added strain. This problem can also be corrected surgically or sometimes with medication.
• Some so-called blue babies are born with a combination of four heart defects, which basically results in oxygen-poor blood flow to body tissues. The excess of poorly-oxygenated blood gives the baby a bluish tinge. Unless treated, most people with this condition would not survive to middle age. However, surgery successfully corrects the condition 90% of the time.