All concepts, explanations, trials, and studies have been
re-written in plain English and may contain errors. I am
not a doctor
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Fractional Shortening (FS)

Shortening fraction is a measure of left ventricular function,
although it has the limitation of being dependent on left
ventricular loading. For example, a reduction in left
ventricular afterload (as in mitral valve insufficiency,
ventricular septal defect or peripheral vasodilation)
increases ventricular shortening so it increases fractional
shortening - even though heart function is not better.
	Using calculated end-systolic volume index (ESD3/m2)
has been suggested as more accurate because it is less
influenced by preload.

Percent of fractional shortening = 
difference between end-diastolic and end-systolic dimensions
divided by
end-diastolic dimension.

FS or Fractional Shortening in percentage = 
EDD minus ESD divided by EDD times 100, where
EDD = LV End Diastolic Dimension and
ESD = LV End Systolic Dimension

Average FS = 36% ; Range = 34 to 44%.