Ejection Fraction - Explanation of Normal and Abnormal Range
Ejection Fraction (EF) is one of the measurements used by physicians to assess how well a patient's heart is functioning. "Ejection" refers to the amount of blood that is pumped out of the heart's main pumping chamber during each heartbeat. "Fraction" refers to the fact that, even in a healthy heart, some blood always remains within this chamber after each heartbeat. Therefore an ejection fraction is a percentage of the blood within the chamber that is pumped out with every heartbeat. Knowing your ejection fraction can save your life - because there are numerous treatment options.
Do You Know Your Ejection Fraction?
Heart failure occurs when one of the heart's pumping chambers is not pumping well enough to meet the body's needs.
Ejection fraction is an important tool in the diagnosis and monitoring of the heart and certain types of cardiomyopathies. Cardiomyopathy is a condition in which the heart is abnormally enlarged, thickened or stiffened.
An EF of 55 to 75 percent is considered normal. A higher than normal ejection fraction could indicate the presence of certain heart conditions, such as hypertrophic cardiomyopathy.
A low ejection fraction could be a sign that the heart is weakened. A low ejection fraction may result from some kind of cardiomyopathy, a condition in which the heart is abnormally enlarged, thickened or stiffened. Low EF is an important risk factor for sudden cardiac death (SCD), a condition that occurs when the heart stops abruptly (cardiac arrest). Patients with a low EF are significantly more likely to suffer sudden cardiac death within two years than patients with a normal ejection fraction.
Normal Ejection Fraction and Heart Failure
While an ejection fraction is a tool to diagnose systolic heart failure, or heart failure that occurs during the pumping phase of the heart beat, it is possible for a person to have heart failure without having an abnormal ejection fraction.
There are two phases to the heart's pumping motion. First is the filling phase (diastole) in which the heart chamber fills with blood. Second is the emptying phase (systole) in which the blood is pumped out of the chamber to the body. An ejection fraction is a measurement of the amount of blood pumped out during this second, emptying stage.
Heart failure may be caused by problems with the heart's emptying phase, its filling phase or with both phases. Therefore, a person whose heart failure is caused by a problem with the filling phase (diastolic heart failure) could have a normal ejection fraction. Diastolic heart failure is the most common form of heart failure.
An ejection fraction of less than 40 may indicate heat failure, a chronic condition in which at least one heart chamber is not pumping well enough to meet the body's needs. Heart failure leads to congestion of blood vessels and fluid backup and swelling in the lungs, legs and ankles, shortness of breath and fatigue. An ejection fraction lower than 40 percent may indicate damage to the heart muscle (e.g., from a prior heart attack). Typically, this EF level alone is not low enough to lead to heart failure.
How to Measure Your EF
An ejection fraction is most commonly measured during an echocardiogram. This painless and noninvasive test uses high-frequency sound waves (ultrasound) to get a picture of the four heart chambers and the four heart valves.
Ejection fraction can also be measured as part of other diagnostic testing, such as:
- MUGA Scan: A type of radionuclide imaging test that provides clear pictures of blood flow through the heart's chambers and blood vessels.
- Cardiac Catheterization: A test in which a catheter is inserted into a blood vessel and guided all the way to the heart in order to obtain information about the heart and the coronary arteries, increasingly, this test is being replaced by noninvasive methods to measure ejection fraction.
- Nuclear Stress Test: An exercise stress test performed before and after the administration of a radionuclide tracer. It creates images of the heart before, during and after physical exertion. Therefore, an ejection fraction may be obtained at both rest and during exercise. This approach offers a very sensitive way to identify heart pump function.
- Cardiac Magnetic Resonance Imaging (MRI): A test that uses powerful magnets to visualize the heart's structure. This test has very good resolution, but the patient is required to hold their breath during the test, a feat that may be difficult for patients with heart failure Also, because this is newly adapted technology to measuring ejection fraction, it remains an expensive test that requires specialized training.
Signs and Symptoms of Low EF
Knowing the signs and symptoms of your EF is important, as low EF can be an indication of impending heart failure. Those symptoms include:
- Shortness of breath or inability to exercise
- Swelling (edema) of the feet and lower legs
- Fatigue and weakness
- Rapid, forceful, uncomfortable or obviously irregular heartbeat (palpitation)
- Abdominal discomfort such as swelling, pain or nausea
- Mental confusion
Some patients have a very low EF (less or equal to 30) and still show minimal or even no symptoms.
Other signs of heart failure or cardiomyopathy may also accompany a low ejection fraction. These include:
- An abnormal heart murmur (due to a heart valve disorder)
- A crackling sound of fluid in the lungs (rates) due to pulmonary congestion
- A rapid heartbeat (tachycardia) or other abnormal heart rhythms (arrhythmia)
- Hypertrophy or enlargement of the heart
- Liver malfunction
- Congestion of the lungs
- Swollen neck veins due to fluid retention with accompanying weight gain and ankle swelling
California Pacific's Heart and Vascular Center
California Pacific's Heart and Vascular Center is supported by one of the best heart hospital/center networks in the USA, offering quality, comprehensive patient-centered cardiovascular care by a team of top heart surgeons and physicians with leading-edge technology. Serving the entire San Francisco Bay Area, including San Francisco and Marin County, as well as the entire Northern California region, our team has many of the best cardiovascular surgeons and physicians in California and the United States.