When heart failure occurs
In people with heart failure, the heart can't move as much blood as it should with each beat. This causes blood to back up into the lungs and throughout the body. Certain organs don't get enough blood to work normally, which causes the symptoms you feel.
Types of heart failure
Heart failure can happen in two ways. The heart muscle may become weak and enlarged (systolic dysfunction). The weakened muscle doesn't pump enough blood forward when the ventricles contract. Or, the heart muscle may become stiff (diastolic dysfunction). The stiff muscle can't relax between contractions, which keeps the ventricles from filling with enough blood. In either case, less blood travels to the lungs and the rest of the body with each heartbeat. You may have one or both types of heart failure.
What is ejection fraction (EF)?
Ejection fraction (EF) is a measure of the blood that the heart pumps out. A healthy heart ejects at least half the blood from the ventricles with each beat. This means a normal EF is around 50 percent or greater. When you have systolic heart failure, though, more blood stays in the chambers than normal. Your doctor can tell you more.