A normal heart ejection fraction refers to the volume of blood pumped out of the heart after each contraction, explains Dr. Martha Grogan, writing for Mayo Clinic. A heart ejection rate of 50 to 55 percent or more is considered normal, while a rate lower than 50 percent is considered abnormal.
When the heart relaxes, two chambers known as ventricles fill with blood, notes Dr. Grogan. When the heart contracts, this blood is pumped out into the rest of the body. However, even the most forceful of contractions cannot empty these heart chambers of all the blood. For this reason, a heart ejection fraction refers to the amount of blood a heart pumps out at each contraction. The heart ejection fraction is only taken at the left ventricle as it is the heart's primary pumping chamber.
For this reason, the measure is referred to as the Left Ventricle Ejection Fraction, or LVEF, notes the Heart Rhythm Society. An LVEF of 36 percent to 49 percent is considered below normal, while an LVEF of 35 percent or less is a sign that the heart's pumping ability is impaired. A low LVEF is a sign of heart failure; the condition is accompanied by symptoms such as swollen feet, fatigue and shortness of breath.