How to calculate ejection fraction
Ejection fraction (EF) is an essential parameter in cardiac assessment, as it provides insight into the heart’s pumping efficiency. Calculating EF accurately is crucial for diagnosing heart diseases and monitoring treatment efficacy. In this article, we will discuss how to calculate ejection fraction and elaborate on the different imaging techniques used in its evaluation.
1. Definition of Ejection Fraction
Ejection fraction is the percentage of blood ejected from a filled ventricle during each heartbeat. It can be expressed as:
EF = (End-Diastolic Volume – End-Systolic Volume) / End-Diastolic Volume
– End-Diastolic Volume (EDV) is the total volume of blood in the ventricle at the end of diastole.
– End-Systolic Volume (ESV) is the remaining volume of blood in the ventricle after contraction (systole).
2. Imaging Techniques for EF Calculation
Various imaging modalities can be used to obtain values for EDV and ESV, which are then utilized to compute EF. These include:
a. Echocardiography: A non-invasive, commonly used imaging method that uses ultrasound waves to produce real-time images of the heart chambers and valves.
b. Cardiac Magnetic Resonance Imaging (MRI): A non-invasive imaging technique that uses magnetic fields and radio waves to create detailed images of cardiac structures.
c. Radionuclide Ventriculography or Multiple-Gated Acquisition (MUGA) Scan: A nuclear imaging test that utilizes small amounts of radioactive material to track blood flow through the heart and calculate EF.
d. Cardiac Computed Tomography (CT): A non-invasive scan that employs X-rays to create detailed cross-sectional images of the heart and blood vessels.
3. Steps for Calculating Ejection Fraction
The following steps outline the calculation of EF based on the imaging technique chosen:
a. Collect data: Obtain EDV and ESV values from the chosen imaging modality.
b. Calculate the difference: Subtract ESV from EDV.
c. Divide the result: Divide the result by EDV.
d. Convert to percentage: Multiply the final outcome by 100 to express it in percentage.
Understanding how to calculate ejection fraction is crucial for cardiovascular assessment. Multiple imaging techniques are available to determine EDV and ESV, each with its advantages and limitations. The choice of modality depends on patient factors, clinical context, and resource availability. Consult with a healthcare professional to determine the most appropriate method for your specific case and accurately calculate EF.