End Systolic Volume Definition

End Systolic Volume Definition is the minimum volume of blood remaining within a ventricle at the close of systole, immediately after ventricular ejection has ended. End-systolic volume (ESV) represents the residual blood that was not expelled during contraction and marks the starting volume from which the ventricle begins refilling during the subsequent diastole.

Physiological Basis

End-systolic volume reflects how completely the ventricle empties during a given contraction.

Residual Blood After Ejection

Ventricular ejection does not empty the ventricle entirely; a residual volume remains once the semilunar valves close at the end of systole, and this residual quantity constitutes the end-systolic volume.

Relationship to Contractile Performance

Because end-systolic volume reflects how much blood is left behind after contraction, it serves as an important indicator of ventricular contractile performance, with a lower end-systolic volume generally reflecting more complete, forceful ejection.

Determinants of End-Systolic Volume

Several physiological factors influence the residual volume remaining at the end of systole.

Contractility

Greater intrinsic contractile strength allows the ventricle to eject a larger fraction of its contents, lowering end-systolic volume; reduced contractility, as in heart failure, tends to raise it.

Afterload

Higher afterload, the resistance the ventricle must overcome during ejection, limits how completely the ventricle can empty, raising end-systolic volume for a given contractile state.

Preload

While preload primarily determines end-diastolic volume, it also influences end-systolic volume indirectly through the Frank–Starling mechanism, since greater initial fiber stretch can enhance contraction and reduce the residual volume.

Role in Determining Stroke Volume and Ejection Fraction

End-systolic volume serves as one of the two boundary values that define stroke volume, and it is central to the calculation of ejection fraction.

Diagrammatic Summary

Clinical Relevance

End-systolic volume is a key parameter in assessing ventricular systolic function, since an elevated end-systolic volume, often accompanying reduced contractility or increased afterload, is a hallmark finding in systolic heart failure and is directly reflected in a reduced ejection fraction.