= End-diastolic volume
{title2=$V_{\mathrm{ED}}$}
\b[End-diastolic volume] is the volume of <blood> in a specified ventricle at the end of filling, before the subsequent ejection. It is the starting volume in the usual volumetric <stroke volume> calculation and the denominator of <ejection fraction>:
$$
\mathrm{SV}=V_{\rm ED}-V_{\rm ES},\qquad
\mathrm{EF}=\frac{V_{\rm ED}-V_{\rm ES}}{V_{\rm ED}}.
$$
The <right ventricle> and <left ventricle> each have their own <end-diastolic volume>. The chamber, phase and measurement convention must be identified before two values are compared.
For a constructed example, a chamber filling to 120 mL and ending ejection at 50 mL has a <stroke volume> of 70 mL and <ejection fraction> about $58.3\%$. Another chamber filling to 180 mL and ending at 110 mL has the same 70 mL <stroke volume>, but <ejection fraction> about $38.9\%$. Equal ejected volumes do not imply equal relative emptying.
The quantity can be obtained from time-resolved images by choosing the filling phase and identifying the complete cavity. A primary right-ventricular <magnetic resonance imaging> study generated volumes from cine images with three-dimensional modelling; its reference analysis also considered age, sex and body size.<Reference right ventricular systolic and diastolic function normalized to age, gender and body surface area from steady-state free precession cardiovascular magnetic resonance by Alicia M. Maceira and others>[Abstract, Methods and results]{ref} These factors help explain why an isolated volume should not be treated as a universal reference value.
For a simple sum-of-slices model, $V_{\rm ED}\simeq\sum_i A_i\Delta z_i$, where $A_i$ is the measured cavity area in a slice and $\Delta z_i$ its represented thickness. Omitting a slice with area 10 cm$^2$ and represented thickness 0.8 cm omits about 8 mL. This example connects <image segmentation> and coverage to a concrete volume error; it does not require a spherical ventricle.
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