What causes congestive heart failure?

The recent death of actress Elizabeth Taylor from congestive heart failure (CHF) has generated a great deal of interest about this condition and its causes. Congestive heart failure is more common than many people realize, currently affecting nearly 5 million Americans, with around 550,000 new cases being diagnosed each year. In fact, for individuals older than 65 years, heart failure is the most common cause of hospitalization.

What happens to the body with heart failure? "Heart failure" does not mean that the heart has stopped working; rather, it means that the heart's pumping power is weaker than normal. To compensate, the main pumping chambers (ventricles) of the heart dilate allowing them to pump more blood. Eventually, the heart muscle thickens (hypertrophy) and the heart rate increases in an effort to maintain normal blood flow. Increased pressure in the heart causes blood to back up into other areas of the body, including the lungs, lower legs and liver. This results in fluid passing from the blood stream into these organs and the extremities. Heart failure also affects the kidney's ability to dispose of sodium and water, further contributing to fluid overload.

What Are the Symptoms of Heart Failure? Symptoms of CHF vary, depending on whether the left or right side of the heart is primarily involved. With left sided heart failure, blood and fluid back up into the lungs causing shortness of breath, difficulty breathing when lying flat, and fatigue. With predominant right sided failure, blood and fluid back up causing swelling in the abdomen (ascites) and in the legs and feet (edema). Sometimes the heart failure affects both chambers of the heart with a blend of these symptoms. Other symptoms of CHF include rapid heartbeat, exercise intolerance, weight gain and persistent cough or wheezing with white or pink-tinged phlegm.

What causes Congestive Heart Failure? The most common reasons for developingCHF are:

• Coronary artery disease and heart attack. The buildup of fatty deposits in the heart's arteries (athlerosclerosis) causes the arteries that supply the heart to become narrowed. With severe narrowing, less blood reaches the heart muscle and the heart becomes starved for oxygen and nutrients. If the blood flow is completely blocked, a heart attack can occur. In a heart attack, a portion of the heart muscle dies, with the development of "scar tissue". This damaged area of heart tissue weakens the heart's ability to pump blood, leading to CHF.
  
  
• High blood pressure. With untreated or poorly controlled hypertension (high blood pressure), the heart has to pump harder than normal to keep blood circulating. In order to compensate for the extra workload, the heart muscle becomes thicker. Over time, the enlarged heart becomes stiff and weak and is unable to pump blood effectively. Uncontrolled high blood pressure increases the risk of developing heart failure by two to three times.
  


• Disease or deformity of the heart valves. Heart valves open and close with each heart beat to keep blood following in the proper direction. When the valves do not function normally, the heart muscle has to pump harder to keep the blood flowing as it should. Heart valve damage can occur due to a heart attack, infection (endocarditis), or can be due to a birth defect. Eventually, the extra workload created by a damaged valve weakens the heart. If the workload becomes too great, heart failure can result.
  


• Heart muscle disease (cardiomyopathy). There are a number of causes for heart muscle disease including infections (e.g. viral myocarditis), alcohol abuse, and the toxic effect of certain medications including chemotherapy drugs.
  


• Congenital heart defects. These are problems affecting the heart's chambers or valves that are present at birth. If the heart and its chambers don't form correctly, the healthy parts have to work harder, which in turn may lead to heart failure.
  


• Abnormal heart rhythms (heart arrhythmias). A common arrhythmia that leads to the development of CHF is atrial fibrillation. The rapid, irregular heartbeat associated with this arrhythmia creates extra work for the heart that can lead to heart failure.
  

To some degree, congestive heart failure is a preventable disease. The best way is through lifestyle measures to avoid the development of coronary heart disease or hypertension. These measures include maintaining a healthy weight, keeping your blood pressure under control, eating a heart-healthy diet, staying physically active, and not smoking. If you already have one of the underlying causes, such as high blood pressure, adequate treatment will reduce the risk that congestive heart failure will develop.

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