Publications
Partners
Heart failure means that the heart cannot pump enough blood to meet the needs of the body’s organs and tissues. It is sometimes called “Congestive Cardiac Failure” or CCF, because the failure results in a build-up of fluids in the body, called tissue congestion. This typically affects the lungs, abdomen, liver and lower legs.
The heart has two main pumping chambers or ventricles, which must relax to fill with blood, then contract to pump the blood out to where it is needed. The right ventricle pumps used blood to the lungs to collect oxygen, whilst the left (main) ventricle pumps out oxygen-rich blood arriving from the lungs to the whole body. A normal left ventricle pumps out ± 60% of the blood it receives: this figure is called the Ejection Fraction (EF). When the EF drops to 30-40%, heart failure exists.
Heart failure can affect the left ventricle only, right ventricle only, or both. Most often, the left side is affected, and this can in turn lead to right heart failure. In addition, the ventricles may become stiffened, and thus not relax enough to fill properly – this filling problem is called Diastolic failure – whereas poor pumping function is called Systolic failure. Failure can thus be classified according to which part/s of the heart are affected, and whether it is diastolic or systolic, and the extent of failure can be quantified in terms of the EF.
Heart failure typically occurs slowly, but may happen very suddenly under certain conditions – see under Causes and Associated risk factors.
As heart failure develops, the body tries to increase the pumping efficiency by increasing the heart rate, and by retaining sodium (salt) and water. These compensatory steps may initially be of benefit, but eventually worsen the whole situation by contributing to congestion and reducing the percentage of blood pumped with each heartbeat (ejection fraction).
Reviewed by Dr AG Hall, July 2007.
