Heart failure is a progressive disorder in which damage to the heart causes weakening of the cardiovascular system. It manifests by fluid congestion or inadequate blood flow to tissues. Heart failure progresses by underlying heart injury or inappropriate responses of the body to heart impairment.

Heart failure may result from one or the sum of many causes. It is a progressive disorder that must be managed in regard to not only the state of the heart, but the condition of the circulation, lungs, neuroendocrine system and other organs as well. Furthermore, when other conditions are present (e.g. kidney impairment, hypertension, vascular disease, or diabetes) it can be more of a problem. Finally, the impact it can have on a patient psychologically and socially are important as well.

Heart failure is a cumulative consequence of all insults to the heart over someone's life. It is estimated that nearly 5 million Americans have heart failure. The prevalence of heart failure approximately DOUBLES with each decade of life. As people live longer, the occurrence of heart failure rises, as well as other conditions that complicate its treatment. Even when symptoms are absent or controlled, impaired heart function implies a reduced duration of survival. Fortunately, many factors that can prevent heart failure and improve outcome are known and can be applied at any stage. 

Fluid Congestion
If the heart becomes less efficient as a pump, the body will try to compensate for it. One way it attempts to do this is by using hormones and nerve signals to increase blood volume (by water retention in the kidneys). A drop in blood flow to the kidneys will also lead to fluid retention. Blood and fluid pressure backed up behind the heart result in excess salt water entering the lungs and other body tissues. However, it is important to note that not all swelling due to fluid retention is a reflection of heart failure.

Clinical symptoms due to fluid congestion:

• shortness of breath
• edema (pooling of fluid in lungs and body)

Reduced Blood Flow to the Body
The heart's inability to pump blood to the muscles and organs isn't always apparent in early stages of heart failure. Often times, it is unmasked only during increases in physical activity. In advanced heart failure, many tissues and organs may not even receive the oxygen they require for functioning at rest.

Clinical symptoms due to poor blood flow to the body:

• difficulty exercising
• fatigue
• dizziness (due to low blood pressure)

The symptoms and physical changes of heart failure have several different classifications based on their location and mechanism.

1. Right Heart Failure - The inability of the right side of the heart to adequately pump venous blood into the pulmonary circulation. This causes a back-up of fluid in the body, resulting in swelling and edema.
2. Left Heart Failure - The inability of the left side of the heart to pump into the systemic circulation. Back-up behind the left ventricle causes accumulation of fluid in the lungs.

1. Forward Heart Failure - The inability of the heart to pump blood at a sufficient rate to meet the oxygen demands of the body at rest or at exercise.
2. Backward Heart Failure - The ability of the heart to pump blood at a sufficient rate ONLY when heart filling pressures are abnormally high.
3. Congestive Heart Failure - Fluid in the lungs or body, resulting from inadequate pumping from the heart and high heart filling and venous pressures.