Monday, October 26, 2009

Monday October 26, 2009
Going back to basics


Q: Explain Ejection fraction (Ef)?

Answer: By definition, the volume of blood within a ventricle immediately before a contraction is known as the end-diastolic volume. Similarly, the volume of blood left in a ventricle at the end of contraction is end-systolic volume. The difference between end-diastolic and end-systolic volumes is the stroke volume, the volume of blood ejected with each beat. Ejection fraction (Ef) is the fraction of the end-diastolic volume that is ejected with each beat; that is, it is stroke volume (SV) divided by end-diastolic volume (EDV):


Ef = SV/EDV
OR
Ef = EDV-ESV/EDV


In a healthy 70-kg (154-lb) man, the SV is approximately 70 ml (left ventricular ESV is 50 ml and the left ventricular EDV is 120 ml) giving an ejection fraction of 70/120, or 0.58 (58%)