The ejection fraction (EF) is the measure of the percentage of blood that is ejected from the main pumping chamber of the heart (the left ventricle) with each beat. A heart does not pump all of the available blood out each time it beats. A normal heart pumps out or ejects only about 50 to 65 percent of the blood inside. If the heart is damaged, the ejection fraction frequently falls below 40 percent. However, you can have a normal ejection fraction and still have heart failure.
This may be related to diastolic heart failure. Although the ejection fraction is a useful number in some situations, it is not the whole story by any means. People with EFs of 40 percent can be severely disabled, while those with EFs of 15 percent may hardly have any symptoms at all. Measuring the ejection fraction may be useful for the cardiologist following the course of the problem in some people.
Traditionally, the ejection fraction was measured by injecting the left ventricle with dye during a cardiac catheterization. After the injection, physicians watched the flow of the dye using an X-ray monitor. During this procedure, called a ventriculogram, physicians were able to measure the amount of dye that was pumped out of the left ventricle during a heartbeat. From this measure, the ejection fraction was established.
Today, the ejection fraction is mostly measured using sound waves during an echocardiogram.An echocardiogram is a safer and faster way of establishing the ejection fraction. Because an echocardiogram does not require the expertise, time, and special laboratory of a cardiac catheterization, ejection fractions can be measured frequently and can help doctors gauge the effectiveness of treatment.