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, or
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, infections (myocarditis) or toxins (alcohol, some chemotherapy agents). 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 failure).
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.
What are the symptoms of congestive heart failure?
The symptoms of congestive heart failure vary among individuals according to the particular organ systems involved and depending on the degree to which the rest of the body has “compensated” for the heart muscle weakness.
- An early symptom of congestive heart failure is fatigue. While fatigue is a sensitive indicator of possible underlying congestive heart failure, it is obviously a nonspecific symptom that may be caused by many other conditions. The person’s ability to exercise may also diminish. Patients may not even sense this decrease and they may subconsciously reduce their activities to accommodate this limitation.
- As the body becomes overloaded with fluid from congestive heart failure, swelling (edema) of the ankles and legs or abdomen may be noticed. This can be referred to as “right sided heart failure” as failure of the right sided heart chambers to pump venous blood to the lungs to acquire oxygen results in buildup of this fluid in gravity-dependent areas such as in the legs. The most common cause of this is longstanding failure of the left heart, which may lead to secondary failure of the right heart. Right-sided heart failure can also be caused by severe lung disease (referred to as “cor pulmonale”), or by intrinsic disease of the right heart muscle (less common)
- In addition, fluid may accumulate in the lungs, thereby causing shortness of breath, particularly during exercise and when lying flat. In some instances, patients are awakened at night, gasping for air.
- Some may be unable to sleep unless sitting upright.
- The extra fluid in the body may cause increased urination, particularly at night.
- Accumulation of fluid in the liver and intestines may cause nausea, abdominal pain, and decreased appetite.
References : medicinenet