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, 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 oranemia) 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.
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. Picture of the heart and valves, left and right ventricles, left and right atria.
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.
Many disease processes can impair the pumping efficiency of the heart to cause congestive heart failure.
In the United States, the most common causes of congestive heart failure are:
- coronary artery disease.
- high blood pressure (hypertension).
- longstanding alcohol abuse.
- disorders of the heart valves.
- unknown (idiopathic) causes, such as after recovery from myocarditis.
Less common causes include viral infections of the stiffening of the heart muscle, thyroid disorders, disorders of the heart rhythm, and many others.
It should also be noted that in patients with underlying heart disease, taking certain medications can lead to the development or worsening of congestive heart failure. This is especially true for those drugs that can cause sodium retention or affect the power of the heart muscle.
Examples of such medications are the commonly used nonsteroidal anti-inflammatory drugs (NSAIDs), which include ibuprofen (Motrin and others) and naproxen (Aleve and others) as well as certain steroids, some medication for diabetes (such as rosiglitazone [Avandia] or pioglitazone [Actos]), and some calcium channel blockers.
After congestive heart failure is diagnosed, treatment should be started immediately. Perhaps the most important and yet most neglected aspect of treatment involves lifestyle modifications. Sodium causes an increase in fluid accumulation in the body's tissues. Because the body is often congested with excess fluid, patients become very sensitive to the levels of intake of sodium and water.
Restricting salt and fluid intake is often recommended because of the tendency of fluid to accumulate in the lungs and surrounding tissues. An American "no added salt" diet can still contain 4 to 6 grams (4000 to 6000 milligrams) of sodium per day. In individuals with congestive heart failure, an intake of no more than 2 grams (2000 milligrams) of sodium per day is generally advised. Reading food labels and paying close attention to total sodium intake is very important. Severe restriction of alcohol consumption also is advised.
Likewise, the total amount of fluid consumed must be regulated. Although many people with congestive heart failure take diuretics to aid in the elimination of excess fluid, the action of these medications can be overwhelmed by an excess intake of water and other fluids. The maxim that "drinking eight glasses of water a day is healthy" certainly does not apply to patients with congestive heart failure.
In fact, patients with more advanced cases of congestive heart failure are often advised to limit their total daily fluid intake from all sources to 2 quarts. The above guidelines for sodium and fluid intake may vary depending on the severity of congestive heart failure in any given individual and should be discussed with their physician.
An important tool for monitoring an appropriate fluid balance is the frequent measurement of body weight. An early sign of fluid accumulation is an increase in body weight. This may occur even before shortness of breath or swelling in the legs and other body tissues (edema) is detected.
A weight gain of two to three pounds over two to three days should prompt a call to the physician, who may order an increase in the dose of diuretics or other methods designed to stop the early stages of fluid accumulation before it becomes more severe.
Aerobic exercise, once discouraged for congestive heart failure patients, has been shown to be beneficial in maintaining overall functional capacity, quality of life, and perhaps even improving survival. Each person's body has its own unique ability to compensate for the failing heart.
Given the same degree of heart muscle weakness, individuals may display widely varying degrees of limitation of function. Regular exercise, when tailored to the person's tolerance level, appears to provide significant benefits and should be used only when the individual is compensated and stable.
Addressing potentially reversible factors
Depending on the underlying cause of congestive heart failure, potentially reversible factors should be explored.
- In certain persons whose congestive heart failure is caused by inadequate blood flow to the heart muscle, restoration of the blood flow through coronary artery surgery or catheter procedures (angioplasty, intracoronary stenting) may be considered.
- Congestive heart failure that is due to severe disease of the valves may be alleviated by valve surgery in appropriate patients.
- When congestive heart failure is caused by chronic, uncontrolled high blood pressure (hypertension), aggressive blood pressure control will often improve the condition.
- Heart muscle weakness that is due to longstanding, severe alcohol abuse can improve significantly with abstinence from drinking.
- Congestive heart failure that is caused by other disease states may be similarly partially or completely reversible by appropriate measures.