Ejection fraction. The left ventricle is a chamber which relaxes to fill with blood and then contracts to pump the blood out. Even in a healthy heart, the left ventricle does not pump all of the blood out with each beat. The ejection fraction is defined by the following formula:
LV diastolic volume - LV systolic volume
LV diastolic volume
(where systolic volume is the fully contracted state and diastolic volume is the fully relaxed state)
The ejection fraction is a useful measure of left ventricular performance. The normal range is 63-77% for males and 55-75% for females (reference: Measurements in Cardiology). If the left ventricle wall is thinned, a decrease in the ejection fraction is seen.
We can use computer programs in the cath lab to calculate the EF, if we do a left ventriculogram, and then trace the end systolic and end diastolic outlines.
Most of the info I found on the web (do a google or yahoo search) talked about calculating it from the measurements taken during the echo.