In cardiovascular physiology, ejection fraction (E_f) is the fraction of blood pumped out of a ventricle with each heart beat. The term ejection fraction applies to both the right and left ventricles; one can speak equally of the left ventricular ejection fraction (LVEF) and the right ventricular ejection fraction (RVEF). Without a qualifier, the term ejection fraction refers specifically to that of the left ventricle. A circulatory system (sometimes cardiovascular system) is an organ system that moves substances to and from cells; it can also help stabilize body temperature and pH (part of homeostasis). ... Human blood smear: a - erythrocytes; b - neutrophil; c - eosinophil; d - lymphocyte. ... In the heart, a ventricle is a chamber which collects blood from an atrium (another heart chamber) and pumps it out of the heart. ... Heart rate is a term used to describe the frequency of the cardiac cycle. ...

Calculation

Ejection fraction is calculated by dividing the volume ejected from a ventricle (called the stroke volume, SV) by the volume of blood in the ventricle after filling (end-diastolic volume, EDV): In cardiovascular physiology, stroke volume (SV) is the amount of blood pumped by the left ventricle into the aorta. ... End-diastolic volume is the volume of blood in the ventricles just before systole. ...

Normal values

In a healthy 70-kg man, the SV is approximately 70 ml and the left ventricular EDV is 120 ml, giving an ejection fraction of 70/120, or 58%. Right ventricular volumes being roughly equal to those of the left ventricle, the ejection fraction of the right ventricle is normally equal to that of the left ventricle within narrow limits.

Healthy individuals typically have ejection fractions greater than 55%. However, normal values depend upon the modality being used to calculate the ejection fraction. Damage to the muscle of the heart (myocardium), such as that sustained during myocardial infarction or in cardiomyopathy, impairs the heart's ability to eject blood and therefore reduces ejection fraction. This reduction in the ejection fraction can manifest itself clinically as heart failure. The ejection fraction is one of the most important predictors of prognosis; those with significantly reduced ejection fractions typically have a poorer prognoses. Myocardium is the muscular tissue of the heart. ... A myocardial infarction occurs when an atherosclerotic plaque slowly builds up in the inner lining of a coronary artery and then suddenly ruptures, totally occluding the artery and preventing blood flow downstream. ... Prognosis (older Greek πρόγνωσις, modern Greek πρόγνωση - literally fore-knowing, foreseeing) is a medical term denoting the doctors prediction of how a patients disease will progress, and whether there is chance of recovery. ...

Measurement

Ejection fraction is commonly measured by echocardiography, in which the volumes of the heart's chambers are measured during the cardiac cycle. Ejection fraction can then be obtained by dividing stroke volume by end-diastolic volume as described above. It has been suggested that Transesophageal_echocardiogram be merged into this article or section. ... Cardiac cycle is the term used to describe the sequence of events that occur as a heart works to pump blood through the body. ...

Other methods of measuring ejection fraction include cardiac MRI, fast scan cardiac computed axial tomography (CT) imaging, ventriculography, Gated SPECT, and the MUGA scan. A MUGA scan involves the injection of a radioisotope into the blood and detecting its flow through the left ventricle. The historical gold standard for the measurement of ejection fraction is ventriculography. The mri are a fictional alien species in the Faded Sun Trilogy of C.J. Cherryh. ... CT apparatus in a hospital Computed axial tomography (CAT), computer-assisted tomography, computed tomography, CT, or body section roentgenography is the process of using digital processing to generate a three-dimensional image of the internals of an object from a large series of two-dimensional X-ray images taken around... MUGA scan (Multiple Gated Acquisition scan) is noninvasive test to evaluate the function of the heart. ... A radionuclide is an atom with an unstable nucleus. ... In medicine, a gold standard test is the diagnostic test that is regarded as definitive in determining whether an individual has a disease process. ...

See also

• Cardiac output
• Heart failure

Cardiac output is the volume of blood being pumped by the heart in a minute. ...

References

• Berne, Robert M., Levy, Matthew N. (2001). Cardiovascular Physiology. Philadelphia, PA: Mosby.
• Boron, Walter F., Boulpaep, Emile L. (2005). Medical Physiology: A Cellular and Molecular Approach. Philadelphia, PA: Elsevier/Saunders.