What is ejection fraction?

Choice A reason: This is not the definition of ejection fraction. The percentage of blood that leaves the heart in a minute is related to the cardiac output, which is the product of the heart rate and the stroke volume. Choice B reason: This is the correct definition of ejection fraction. It is the ratio of the stroke volume (the amount of blood pumped by the left ventricle) to the end-diastolic volume (the amount of blood in the left ventricle at the end of diastole). It is a measure of the efficiency of the heart and reflects the contractility of the cardiac muscle. Choice C reason: This is not the definition of ejection fraction. The amount of blood that leaves the heart with each beat is the stroke volume, which is one of the factors that determine the ejection fraction. Choice D reason: This is not the definition of ejection fraction. The amount of blood that leaves the heart in a minute is the cardiac output, which is influenced by the ejection fraction, but not equivalent to it.