Heart failure most commonly develops slowly, following damage to the heart that may be caused by a heart attack, coronary artery disease, chronic high blood pressure, diabetes or other disorders. As a consequence, the heart can no longer carry out its work, and heart failure develops.
A healthy heart has a number of compensatory mechanisms that allow it to temporarily increase its pumping function to meet increased metabolic need (e.g. during exercise). In patients with heart failure, these compensatory mechanisms are continuously being used. It is the continuous use of compensatory mechanisms that causes the death of individual heart muscle cells. When the compensatory mechanisms are continuously used, there is litle reserve for activities, such as exercise.
Heart failure is often not recognized until a more advanced stage, commonly referred to as congestive heart failure, develops. In this stage, fluid may leak into the lungs, feet, legs and, in some cases, the liver or abdominal cavity.
There are two types of heart failure:
Systolic heart failure: decreased ability of the heart to contract and an inability of the heart to pump enough blood into circulation. This is the most common type of heart failure.
Diastolic heart failure: decreased ability of the heart to relax. Blood has difficulty entering the heart's chambers, and excess fluid builds up in different parts of the body.