Heart failure occurs when the heart muscle does not pump as much blood as the body needs. Failure does not mean that the heart has stopped pumping but rather that it is failing to pump as effectively as it should.

The body might try to compensate for the heart's reduced pumping ability by:

• Holding on to (retaining) salt and water to increase the amount of blood in the bloodstream.
• Increasing the heart rate.
• Increasing the size of the heart.