A Computational Application of Ejection Fraction Measurement to Estimate End-Systolic Elastance

Background: We apply ejection fraction (EF) as a fundamental constant to predict end-systolic volume (ESV) and end-systolic pressure (ESP) trends of the end-systolic pressure volume relationship (ESPVR). Methods: As described previously (1), ejection fraction (EF) predicts [ ESV i , ESP i ] data based on end-diastolic volume (EDV i ) of beat i during ESPVR measurement. ESV i = EDV i x (1- EF) ESP i = K conduit x EDV i x EF + DBP Constant K conduit is the effective, beat–synchronized elastic modulus of the arterial load, and constant DBP is diastolic arterial blood pressure. When differentiated, ESP and ESP equations formulate the following expression of ESPVR slope during a one-beat perturbation from steady state. ESPVR Beat 1 : α slope = K conduit x EF / (1-EF) Slope α is therefore the ESPVR curve’s expected tangent when functioning near natural preload. As EDV adjustment proceeds beyond beat 1 , ESPVR data gradually forms a curved pattern with different slopes through the pressure-volume diagram; this curve generally trends towards volume V= 0 as the chamber pressure is fully relaxed to P=0. Starting from this equilibrium [V=0, P= 0], a Bezier curve's construction ending at the steady-state end-systolic sample [ESV, ESP] can therefore apply α slope as a Bezier end-point slope constraint to estimate ESPVR. Results: Applying Bezier construction to 36 studied pressure-volume loop datasets (2), we approximate end-systolic elastance (Ees) of ESPVR with a similarly computed linear regression slope through Bezier curve points. Within the upper 50% of each ESPVR pressure range, computed end-systolic elastance (Ees’) exhibits a robust and unity-proportioned correlation to direct Ees measurement. Ees’ =.98 x Ees -.01 mmHg/mL (R 2 =.97) Conclusion: In addition to indicating the contractile mechanism elastance magnitude, natural range ESPVR data reflects the outcome of arterial load coupling to characteristic ejection fraction functionality maintained during preload adjustment. 1. Marcus, E., A Study of Mechanisms Influencing Left-Ventricle End-Systolic Pressure Volume Relationship Measures, in COMPARATIVE PHYSIOLOGY: From Organisms to Omics in an Uncertain World, A.P. Society, Editor. 2022, American Physiology Society: San Diego 2. Marcus, E., Ejection Fraction is Maintained during Preload Adjustment, Proceedings of the American Physiology Society Annual Summit, A.P. Society, Editor. 2025, American Physiology Society: Baltimore. Mr. Marcus is a salary-supported Principal Research Software Engineer This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.