End Diastolic Volume Definition

End Diastolic Volume Definition is the maximum volume of blood contained within a ventricle at the close of diastole, immediately before the onset of ventricular systole. End-diastolic volume (EDV) represents the total filling achieved through the passive and active stages of diastole, rapid filling, diastasis, and atrial systole, and it establishes the starting volume from which ventricular ejection proceeds.

Physiological Basis

End-diastolic volume reflects the cumulative result of ventricular filling across the entirety of diastole.

Completion of Filling

By the time the atrioventricular valves close at the onset of systole, the ventricle has received blood through rapid filling, the slower phase of diastasis, and the final active contribution of atrial systole. The volume present at that closing instant defines the end-diastolic volume.

Relationship to Preload

End-diastolic volume is the physiological correlate of ventricular preload, since it determines the degree of stretch placed on myocardial sarcomeres immediately before contraction begins.

Determinants of End-Diastolic Volume

Several factors influence how much blood accumulates in the ventricle by the end of diastole.

Venous Return

The volume of blood returning to the heart through the venous system directly supplies the atria and, in turn, the ventricles during diastole; increased venous return raises end-diastolic volume.

Diastolic Filling Time

Because filling requires time, the duration of diastole affects how much blood can enter the ventricle; shortened diastole, as occurs with tachycardia, tends to reduce end-diastolic volume.

Ventricular Compliance

The distensibility of the ventricular wall determines how much volume can be accommodated for a given filling pressure; reduced compliance limits end-diastolic volume even when venous return is adequate.

Role in Determining Stroke Volume

End-diastolic volume serves as one of the two boundary values that define stroke volume.

Through the Frank–Starling mechanism, an increase in end-diastolic volume, by stretching myocardial fibers to a more favorable length, enhances the force of the subsequent contraction and increases stroke volume.

Diagrammatic Summary

Clinical Relevance

End-diastolic volume is an important parameter in the assessment of cardiac function, since abnormal elevation, as seen in volume-overloaded or dilated ventricles, or abnormal reduction, as seen in restrictive or hypovolemic states, both signal altered filling dynamics with direct consequences for stroke volume and overall cardiac output.