End Systolic State

End Systolic State is the condition of the ventricles at the precise moment ejection concludes and ventricular relaxation is about to begin, characterized by the minimal volume and a specific corresponding pressure remaining within the ventricular chamber after the reduced ejection phase has run its course. It marks the transition point separating the systolic ejection phases from the subsequent diastolic relaxation and filling phases, representing the residual state of the ventricle immediately following contraction.

Position Within the Cardiac Cycle

Conclusion of the Ejection Sequence

The end systolic state represents the outcome of the full ejection sequence, following the substantial volume reduction achieved during rapid ejection and the further, more gradual reduction achieved during reduced ejection, culminating in the smallest ventricular volume reached during the entire cardiac cycle.

Boundary with Isovolumetric Relaxation

The end systolic state exists at the instant immediately preceding closure of the semilunar valves, which occurs as ventricular pressure falls below arterial pressure at the conclusion of ejection, marking the transition from systole into the isovolumetric relaxation phase of diastole.

Key Parameters of the End Systolic State

End Systolic Volume

End systolic volume represents the volume of blood remaining within a ventricle at the conclusion of ejection, reflecting the difference between the end diastolic volume present before contraction and the stroke volume subsequently ejected.

End Systolic Pressure

End systolic pressure represents the intraventricular pressure at this same instant, closely approximating the arterial pressure against which the ventricle has been ejecting, since the semilunar valves remain open until pressures on either side converge and cross.

Determinants of the End Systolic State

Contractility

The intrinsic force-generating capacity of the myocardium directly influences how completely the ventricle empties during ejection, with greater contractility producing a smaller end systolic volume for any given preload and afterload condition.

Afterload

The resistance and pressure present within the arterial circulation that the ventricle must overcome during ejection influences the extent of shortening achieved, with higher afterload generally resulting in a larger end systolic volume as the ventricle ejects against greater opposing pressure.

Representation on the Pressure-Volume Loop

Position at the Loop Boundary

Within the ventricular pressure-volume loop, the end systolic state corresponds to the point of minimal volume along the ejection curve, immediately preceding the vertical fall in pressure at constant volume that characterizes the subsequent isovolumetric relaxation phase.

End Systolic Pressure-Volume Relationship

The set of end systolic points achieved across varying loading conditions, at a constant level of contractility, forms a nearly linear relationship known as the end systolic pressure-volume relationship, whose slope reflects the intrinsic contractile state of the ventricle independent of preload and afterload at any single beat.

Clinical and Physiological Assessment

Afterload Representation

The end systolic state is closely tied to the physiological concept of afterload, since the pressure the ventricle must generate and sustain to complete ejection directly determines the volume remaining when ejection ceases.

Basis for Ejection Fraction Calculation

The end systolic volume, considered together with the preceding end diastolic volume, provides the basis for calculating the proportion of end diastolic volume ejected during systole, a widely used index of overall ventricular pumping performance.

Functional Significance of the Representation

Determinant of Subsequent Diastolic Filling

The end systolic state functions as the starting condition from which ventricular diastole proceeds, defining the residual volume that must be added to during subsequent filling phases in order to reestablish an adequate end diastolic volume for the next contraction.

Integrative Marker of Contractile and Loading Interaction

Because the end systolic state reflects the combined influence of contractility and afterload acting upon the ventricle during ejection, it serves as an integrative representation of how effectively the ventricle has translated its contractile force into forward ejection against the prevailing arterial resistance.