Congestive Heart Failure
Revising Medical Author: Daniel
Kulick, MD, FACC, FSCAI
Revising Medical Editor: Dennis Lee, MD
What is congestive heart failure?
Congestive heart failure (CHF) is a condition in which the heart's function as a pump to deliver oxygen rich blood to the body is inadequate to meet the body's needs.
Congestive heart failure can be caused by 1) diseases that weaken the heart muscle, 2 diseases that cause stiffening of the heart muscles, or 3) diseases that increase oxygen demand by the body tissue beyond the capability of the heart to deliver.
The heart has two atria (right atrium and left atrium) that make up the upper chambers of the heart, and two ventricles (left ventricle and right ventricle) that make up the lower chambers of the heart. The ventricles are muscular chambers that pump blood when the muscles contract (the contraction of the ventricle muscles is called systole). Many diseases can impair the pumping action of the ventricles. For example, the muscles of the ventricles can be weakened by heart attacks or infections (myocarditis). The diminished pumping ability of the ventricles due to muscle weakening is called systolic dysfunction. After each ventricular contraction (systole) the ventricle muscles need to relax to allow blood from the atria to fill the ventricles. This relaxation of the ventricles is called diastole. Diseases such as hemochromatosis can cause stiffening of the heart muscles and impair the ventricles' capacity to relax and fill. This is referred to as diastolic dysfunction. Additionally, in some patients, although the pumping action and filling capacity of the heart may be normal, abnormally high oxygen demand by the body's tissues (for example, in patients with hyperthyroidism) may make it difficult for the heart to supply an adequate blood flow (called high output heart failure).
In some patients one or more of these factors can be present to cause congestive
heart failure. The remainder of this article will focus primarily on congestive
heart failure that is due to heart muscle weakness, systolic dysfunction.
Congestive heart failure can affect many organs of the body. For example, the weakened heart muscles may not be able to supply enough blood to the kidneys, which then begin to lose their normal ability to excrete salt (sodium) and water. This diminished kidney function can cause to body to retain more fluid. The lungs may become congested with fluid (pulmonary edema) and the person's ability to exercise is decreased. Fluid may likewise accumulate in the liver, thereby impairing its ability to rid the body of toxins and produce essential proteins. The intestines may become less efficient in absorbing nutrients and medicines. Over time, untreated
congestive heart failure will affect virtually every organ in the body.
Next: What causes congestive heart failure? »
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Last Editorial Review: 5/7/2007
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