Heart failure is a condition in which the heart has lost ability to pump enough blood to the body's tissues. With too little blood, the organs and other tissues do not receive enough oxygen and nutrients to function properly.

Heart failure happens when disease affects the heart's ability to deliver blood. Often, a person with heart failure may have a buildup of fluid in the tissues, called edema. Heart failure with this kind of fluid buildup is called congestive heart failure. According to the American Heart Association, about 4.9 million Americans are living with congestive heart failure. Ten out of every 1,000 people over age 65 have this condition.

Where edema occurs in the body depends on the part of the heart affected. Heart failure caused by abnormality of the lower left chamber of the heart (left ventricle) means that the ventricle cannot pump blood to the body as...