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Preload vs End Diastolic Volume

Are preload and end diastolic volume the same thing? If not, what's the difference?

Thanks :smile:

Hi they are closely related;

preload is determined mainly by venous diameter - venodilatation causes pooling of blood around the viscera, so less is returned to the (mainly) right atrium in the venae cavae, whereas venoconstriction increases venous return. Preload, I would anticipate, has units of pressure or dimensions ML^-2.

EDV is the volume of blood in the heart (more usefully in the ventricles, particularly LV) just before the start of systole and ventricular contraction - it determines the force of contraction of the heart in line with the Frank-Starling Law. The greater the EDV, the greater the force of contraction. Units of EDV are of course of volume (ml) dimensions - L^3.

So subtle difference although v similar.

Hope this helps - thanks.

Mukesh (Specialist biology tutor + ex-medic)