Ejection fraction is the percentage of blood that is pumped out with each heartbeat. During each heartbeat, the heart contracts and relaxes. The heart never empties all of the blood from the lower chambers, called ventricles. Ejection fraction is usually measured in the left ventricle because it is the heart's main pumping chamber. A normal ejection fraction in a person at rest is typically between 55 and 70 percent. If the heart muscle has been damaged by heart attack, heart muscle disease or heart valve problems, the ejection fraction may be below normal.