Ejection Fraction (EF)
Ejection Fraction (EF)
Ejection fraction (EF) is a key measurement expressed as a percentage that quantifies how much blood the left ventricle of the heart pumps out with each contraction. It is a critical indicator of cardiac function and is widely used to diagnose and monitor heart conditions, especially heart failure.
Definition and Calculation
- EF represents the fraction of blood ejected from the ventricle relative to the total volume of blood in the ventricle at the end of diastole (filling phase).
- It is calculated using the formula: EF=(Stroke Volume (SV)End-Diastolic Volume (EDV))×100\text{EF} = \left(\frac{\text{Stroke Volume (SV)}}{\text{End-Diastolic Volume (EDV)}}\right) \times 100EF=(End-Diastolic Volume (EDV)Stroke Volume (SV))×100 where stroke volume is the amount of blood pumped out per beat, and EDV is the total volume of blood in the ventricle before contraction24.
- EF usually refers to the left ventricular ejection fraction (LVEF), which measures the pumping efficiency of the left ventricle, responsible for delivering oxygen-rich blood to the body. The right ventricular ejection fraction (RVEF) measures pumping to the lungs but is less commonly assessed24.
Normal and Abnormal Values
- A normal EF ranges approximately from 55% to 70%, indicating that more than half of the blood in the left ventricle is pumped out with each heartbeat146.
- An EF below 50% may indicate impaired heart function.
- An EF below 40% is generally considered a sign of heart failure or cardiomyopathy, meaning the heart is not pumping enough blood to meet the body’s needs346.
- EF between 40% and 50% is often termed borderline or mildly reduced6.
- Some patients may have heart failure with preserved ejection fraction (HFpEF), where EF is normal but the heart muscle is stiff and does not fill properly4.
Clinical Importance
- EF is used to diagnose and classify heart failure, guide treatment decisions, and monitor response to therapy14.
- It helps evaluate damage after heart attacks, effects of high blood pressure, cardiomyopathies, valve diseases, and the impact of certain chemotherapies4.
- EF can be measured by various imaging modalities including echocardiography (most common), cardiac MRI (gold standard), nuclear scans, CT, and ventriculography5.
Summary Table
| Parameter | Details |
|---|---|
| Definition | Percentage of blood ejected from the left ventricle with each heartbeat |
| Normal Range | 55% to 70% |
| Borderline Low | 40% to 50% |
| Low EF (Heart Failure) | Below 40% |
| Measurement Methods | Echocardiogram, cardiac MRI, nuclear scans, ventriculography, CT |
| Clinical Use | Diagnosis and management of heart failure, cardiomyopathy, valve disease, post-MI assessment |
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References
- American Heart Association: Ejection Fraction Heart Failure Measurement
https://www.heart.org/en/health-topics/heart-failure/diagnosing-heart-failure/ejection-fraction-heart-failure-measurement - Cleveland Clinic: Ejection Fraction: What It Is, Types and Normal Range
https://my.clevelandclinic.org/health/articles/16950-ejection-fraction - Penn Medicine: Ejection Fraction: What Do the Numbers Mean?
https://www.pennmedicine.org/updates/blogs/heart-and-vascular-blog/2022/april/ejection-fraction-what-the-numbers-mean - WebMD: Ejection Fraction: Definition, Measurement, Causes, and Treatment
https://www.webmd.com/heart-disease/heart-failure/ejection-fraction-percentage-meaning - Wikipedia: Ejection fraction
https://en.wikipedia.org/wiki/Ejection_fraction - Harvard Health Publishing: Measuring ejection fraction
https://www.health.harvard.edu/heart-health/measuring-ejection-fraction
Ejection fraction is a vital clinical measure of how effectively the heart pumps blood, with normal values indicating healthy cardiac function and lower values signaling possible heart failure or other cardiac dysfunctions.
