Overview of Left Ventricular Ejection Fraction
The Left Ventricular Ejection Fraction (LVEF) is a key indicator of how well the left side of your heart is working. It measures the amount of blood that is pumped out of the left chamber of your heart (left ventricle) when it contracts, as a ratio of the total amount of blood in it just before it contracts.
To put it simply, imagine that we fill a water balloon (which represents your heart’s left ventricle) up to its full capacity with water (which represents blood). When we squeeze the balloon, it will squirt out some of the water. The amount of water sprayed out (stroke volume) compared to the total amount of water in the balloon before we squeezed it (end-diastolic volume) would be like the LVEF for your heart.
So, LVEF is just: [amount squirted out / total amount to begin with] x 100.
Experts from the American Society of Echocardiography and the European Association of Cardiovascular Imaging have provided normal ranges for LVEF based on a technique called two-dimensional echocardiography:
For Men:
- Normal: 52% to 72%
- Slightly abnormal: 41% to 51%
- Moderately abnormal: 30% to 40%
- Very abnormal: Less than 30%
For Women:
- Normal: 54% to 74%
- Slightly abnormal: 41% to 53%
- Moderately abnormal: 30% to 40%
- Very abnormal: Less than 30%
The American College of Cardiology has also provided a simple guide for understanding these ranges:
- Much Better Than Average (Hyperdynamic): Over 70%
- Normal: 50% to 70%
- Mild Dysfunction: 40% to 49%
- Moderate Dysfunction: 30% to 39%
- Severe Dysfunction: Less than 30%
Your doctor may use either the actual LVEF number or terms like “moderate dysfunction” to describe how well your heart is working.
Why do People Need Left Ventricular Ejection Fraction
Understanding the percentage of blood your heart pumps out of the left ventricle (the main pumping chamber) with each beat has a major importance when dealing with heart diseases. This is known as the Left Ventricular Ejection Fraction (LVEF). It can help doctors predict health risks in patients suffering from congestive heart failure, heart attacks, and after certain heart procedures.
By evaluating LVEF, doctors can understand the extent of the decrease in the heart’s ability to pump blood, which can guide the treatment for various heart issues.
There are several reasons why your doctor might assess your LVEF. These include:
- To understand the shape and function of the left part of your heart that pumps the blood.
- To examine the overall and specific performance of your left ventricle, either by using description (qualitative) or numbers (quantitative).
- To check up on patients who are showing symptoms that might suggest heart diseases.
- To classify the type of heart failure a patient is suffering from. There are two main types: one where the pumping capacity is preserved and the other where it’s reduced.
- In cases of irregular heart rhythms, to check for structural causes.
- For those who have or are going to experience treatments that might harm the heart.
- Before a particular procedure where low heart pumping function could be a risk or reason not to proceed.
- To diagnose congenital heart disease, which refers to heart problems a patient was born with.
- To evaluate problems related to heart valves.
How is Left Ventricular Ejection Fraction performed
The Left Ventricular Ejection Fraction (LVEF) is a measurement that helps doctors understand how well your heart is pumping out blood. It can be estimated in different ways, either by simply observing it (subjectively) or using more direct and precise measurements (objectively). Doctors prefer to use the latter method because it can be more accurate.
There are several non-invasive (not requiring surgical incision) methods to calculate this. These include echocardiography, which uses sound waves to create images of the heart; Magnetic Resonance Imaging (MRI), which uses magnetic fields and radio waves; Computed Tomography (CT), which uses X-rays; Gated Equilibrium Radionuclide Angiography (also known as MUGA scan), which analyses the motion and function of heart’s chambers; and Gated myocardial perfusion imaging with Single-Photon Emission Computed Tomography (SPECT) or Positron Emission Tomography (PET), which evaluate the blood flow in your heart.
There’s also an invasive method called Left Ventricular Contrast Ventriculography, which involves inserting a catheter into your heart during an invasive operation.
Echocardiography uses various methods and the images generated can be one-dimensional (linear), two-dimensional (area), or three-dimensional (volumetric). One of the commonly used methods is called the “biplane method of disks” also known as modified Simpson’s rule. Here, the inside surface of your heart is traced out and these tracings are divided into a number of disks. This method has the advantage of less requirement for geometric assumptions about the shape of your heart. Another method calculates your heart’s volume from measurements of its width; however, this method is not commonly recommended as it assumes a fixed geometric shape of your heart, which could be inaccurate in certain heart diseases.
Three-dimensional echocardiography is considered the best method as it does not require any assumptions about the heart’s shape. This method uses a special probe to gather data over several heartbeats. It not only gives a detailed understanding of the shape of your heart but also provides a more accurate and less variable result.
MRI, like echocardiography, also uses the Simpson method where the inside of your heart is traced out. This method doesn’t require any ionizing radiation or contrast material (a dye that helps tissues, blood vessels and the like show up more clearly on the scan).
CT can also calculate the LVEF using the same Simpson method, but it requires a contrast material. This material helps in differentiating between blood and the lining of the heart. However, if you are allergic to contrast material or have poor kidney function, this method may not be appropriate for you.
Finally, using nuclear cardiac imaging, LVEF can be measured. Two commonly used methods are SPECT or PET. These methods evaluate the flow of blood into your heart.
Your doctor will choose the most appropriate method based on your specific medical condition and history.
What Else Should I Know About Left Ventricular Ejection Fraction?
The left ventricular ejection fraction (LVEF) plays an important role in predicting heart-related risks and deaths. LVEF is a measurement that shows how much blood your heart is pumping out with each contraction. In medical settings, a low LVEF is often used to decide if a person needs a defibrillator, which is a device that corrects abnormal heart rates and rhythms. Research has shown that patients with a history of heart attacks who have a LVEF less than 30% have experienced significant decreases in sudden heart-related death rates after getting this device.
The LVEF is particularly crucial in managing patients with heart failure. As the percentage of LVEF increases to 45%, the chances of mortality decreases. However, if the LVEF exceeds 45%, there is no further decrease in the rate of death. Even though the LVEF is a key element in predicting a patient’s outcome, it should be considered along with other risk factors. Current guidelines from the American College of Cardiology and the American Heart Association recommend checking LVEF routinely in heart failure patients to help direct treatment plans, although they do not specify a direct relationship between LVEF and prognosis.
Furthermore, LVEF is considered an important factor when monitoring heart function during cancer treatment. Before, during, and after cancer therapy, echocardiography, a test that uses ultrasonic waves to create images of the heart, is used to evaluate patients. If a patient’s LVEF falls below 53% at the start, a discussion with a heart specialist may be suggested to balance the risks and benefits of treatment. If the LVEF decreases by 10% or more, reaching below 53% during cancer treatment, patients may be directed to cardiovascular professionals to review their heart and cancer therapies.
LVEF is also used as a criterion in the management of patients with heart valve diseases. Specifically, those with severe aortic stenosis or chronic severe aortic regurgitation and a LVEF less than 50% may be advised to undergo aortic valve replacement surgery. Mitral valve surgery may be considered for patients with an LVEF of 60% or below.
