Congestive Heart Failure
Congestive heart failure (CHF) is a condition in which the heart's
function as a pump is inadequate to deliver oxygen rich blood to the
body. Congestive heart failure can be caused by:
- diseases that weaken the heart muscle
- diseases that cause stiffening of the heart muscles
- diseases that increase oxygen demand by the body tissue beyond the
capability of the heart to deliver adequate oxygen-rich blood
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 (iron overload) or amyloidosis can
cause stiffening of the heart muscle and impair the ventricles' capacity
to relax and fill; this is referred to as diastolic dysfunction. The
most common cause of this is longstanding high blood pressure resulting
in a thickened (hypertrophied) heart. 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, with hyperthyroidism or anemia) may make it difficult for the
heart to supply an adequate blood flow (called high output heart
In some individuals 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 the
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.
- Fluid also may accumulate in the extremities, resulting in edema (swelling) of the ankles and feet.
Eventually, untreated, worsening congestive heart failure will affect virtually every organ in the body.