Your heart contracts and relaxes about 100,000 times a day. As the heart relaxes between beats, the ventricles fill with blood. When it contracts, it pushes out most of that blood.
Ejection fraction refers to the percentage or amount of blood in the hearts left ventricle (the lower chamber) that is pumped out with each contraction.
Even a healthy heart chamber doesnt expel its full contents at every beat. Instead, a normal ejection fraction lies somewhere between 55% to 70%. A low or reduced ejection fraction is considered to be any ejection fraction below 40%.