What is heart failure?
The heart's primary function is to pump blood to all parts of the body, bringing nutrients and oxygen to the tissues and removing waste products. When the body is at rest, it needs a certain amount of blood to achieve this function. During exercise or times when greater demands are placed on the body, more blood is required. To meet these variable demands, the heartbeat increases or decreases, and blood vessels dilate to deliver more blood or constrict during times when less blood is required.
When a person is diagnosed with heart failure, it does not mean the heart has stopped working, but rather that it is not working as efficiently as it should. In other words, the term "failure" indicates the heart is not pumping effectively enough to meet the body's needs for oxygen-rich blood, either during exercise or at rest. The term congestive heart failure (CHF) is often synonymous with heart failure but also refers to the state in which decreased heart function is accompanied by a buildup of body fluid in the lungs and elsewhere. Heart failure may be reversible, and people may live for many years after the diagnosis is made.
Whenever possible, the best treatment of congestive heart failure is one of prevention.
Heart failure may occur suddenly, or it may develop gradually. When heart function deteriorates over years, one or more conditions may exist. The strength of muscle contractions may be reduced, and the ability of the heart chambers to fill with blood may be limited by mechanical problems, resulting in less blood to pump out to tissues in the body. Conversely, the pumping chambers may enlarge and fill with too much blood when the heart muscle is not strong enough to pump out all the blood it receives. In addition, as the architecture of the heart changes as it enlarges, regurgitation of the mitral valve may develop, making the heart failure even worse. [See exactly how your heart pumps blood throughout your body inMap of the Human Heart.]
Who develops heart failure?
There are an estimated two million people in the United States with heart failure. The incidence of chronic congestive heart failure—the number of new cases developing in the given population each year—has increased in recent years. This is possibly a result of the overall decline in deaths from coronary (ischemic) heart disease, an improvement attributed to medical advances and the fact that people are living longer.
The most common cause of congestive failure is coronary artery disease—narrowing of the arteries supplying blood to the heart muscle. Although coronary disease often starts at an early age, congestive failure occurs most often in the elderly. Among people more than 70 years old, about 8 out of 1,000 are diagnosed with congestive heart failure each year. The majority of these patients are women, probably because men are more likely to die from coronary artery disease before it progresses to heart failure.
Heart failure is also associated with untreated hypertension, alcohol abuse, and drug abuse (primarily cocaine and amphetamines) at any age. Hyperthyroidism and various abnormalities of the heart valves (particularly aortic and mitral) are among the other disorders that can cause heart failure. In addition, viral infection or inflammation of the heart (myocarditis) or primary heart muscle disease (cardiomyopathy), and in rare instances, extreme vitamin deficiencies, can result in heart failure.
Whenever possible, the best treatment of congestive heart failure is one of prevention. This includes diagnosing and treating high blood pressure and attempting to prevent atherosclerosis. Other important preventive steps include not smoking, using alcohol in moderation if at all, and abstaining from cocaine and other illicit drugs. A prudent diet, regular exercise, and weight control are also important.
When a patient is diagnosed as having heart failure, the first treatment is often restriction of dietary sodium. Drugs may be prescribed as well. Diuretics, available since the 1950s, are often used to help the kidneys get rid of excess water and sodium, thereby reducing blood volume and the heart's workload.
Digitalis, a drug that has been used since the 18th century, is still a component of modern therapy. It is prescribed to strengthen the heart's pumping action. Patients taking both diuretics and digitalis may need to supplement their levels of potassium.
Heart transplants are a last resort
Newer drugs for the treatment of heart failure include vasodilators, which cause the peripheral arteries to dilate, or open up. This reduces the work of the heart by making it easier for blood to flow. Among the newest vasodilators used for heart failure are the angiotensinconverting enzyme (ACE) inhibitors, which may be used, along with diuretics, in patients with mild-to-moderate or severe congestive failure. ACE inhibitors, which include captopril (Capoten) and enalapril (Vasotec), block the production of a substance called angiotensin II, a potent constrictor of blood vessels. If blood vessels are dilated, the amount of work needed for the heart to pump blood forward is decreased.
Other drugs used in the treatment of heart failure include calcium-channel blockers, which dilate blood vessels; beta blockers, which slow the heart (used only in unusual circumstances); and medications that affect various heartbeat irregularities. Most cases, however, respond to diuretics and digitalis, especially when ACE inhibitors are added.
Sometimes, surgery proves effective. When heart failure is due to valvular disease, surgical implantation of an artificial heart valve or valve repair may alleviate the problem. Surgery may also be helpful in correcting congenital heart defects that can lead to heart failure. Coronary artery bypass graft surgery and catheterization using a balloon to flatten fatty deposits (called angioplasty) are among the therarpeutic techniques used to prevent and treat heart failure caused by occluded, or blocked, arteries.
Heart transplants are a last resort in treating severe heart failure caused by diseased heart muscle. Although the success rate of heart transplants has significantly improved, the cost of the operation and shortage of donor organs makes it impractical except as a last resort.