Single-Beat Estimation of End-Systolic Elastance Using Bilinearly Approximated Time-Varying Elastance Curve

Abstract

Background-Although left ventricular end-systolic elastance (E es ) has often been used as an index of contractility, technical difficulties in measuring volume and in changing loading conditions have made its clinical application somewhat limited. By approximating the time-varying elastance curve by 2 linear functions (isovolumic contraction phase and ejection phase) and estimating the slope ratio of these, we developed a method to estimate E es on a single-beat basis from pressure values, systolic time intervals, and stroke volume. Methods and Results-In 11 anesthetized dogs, we compared single-beat E es with that obtained with caval occlusion.Although the decrease (but not the increase) in contractility (5.3 to 11.4 mm Hg/mL) and the change in loading conditions (3.7 to 34.0 mm Hg/mL) over wide ranges significantly altered the slope ratio, the estimation of E es was reasonably accurate (yϭ0.97xϩ0.46, rϭ0.929, SEEϭ2.1 mm Hg/mL). Conclusions-E es can be estimated on a single-beat basis from easily obtainable variables by approximating the time-varying elastance curve by a bilinear function.

The cardiovascular physiologic actions of urocortin II: Acute effects in murine heart failure

“…E max (slope of the end-systolic pressure-volume relation), as a specific measure of contractility, and V 0 (the extrapolated ESV at which pressure is zero) were derived from an averaged steady-state pressure-volume loop (n ϭ 7) by using a bilinearly approximated time-varying elastance curve applied to the isovolumic and ejection phases of systole (30). Derived effective arterial elastance (end-systolic pressure͞stroke volume) was used as a variable that quantifies in the aggregate the characteristic impedance, resistive, and stiffness properties of the systemic vasculature (31,32).…”

Hemodynamic Characteristics of Patients with Diastolic Heart Failure and Hypertension

“…The monoexponential-based time constant of isovolumetric fall of LV pressure was calculated with the assumption that pressure decayed to a non-zero asymptote (15). The LV contractile state was assessed by endsystolic elastance (Ees) using a single-beat formula, which is sensitive to changes in contractile state but relatively insensitive to changes in loading conditions (16). Effective arterial elastance (Ea) was calculated as end-systolic pressure divided by stroke volume (17).…”

Noninvasive evaluation of left ventricular elastance according to pressure-volume curves modeling in arterial hypertension

“…In anesthetized dogs, increase in LV elastance during ejection was predominantly constant and non linearity accounted for only 2% of the variance (27).…”

“…In addition, this complex method includes an estimated and average normalized LV elastance at end diastole, calculated from invasive measurements in 18 patients. In order to simplify this technique, Gayat et al (9) proposed an alternative approach based on Shishido work (27). They included an indirect estimation of LV end-diastolic pressure using the Doppler diastolic pulmonary venous flow deceleration time.…”