Determinants of left ventricular ejection fraction and a novel method to improve its assessment of myocardial contractility

Abstract

Background The aim of this study was to quantify the impact of different cardiovascular factors on left ventricular ejection fraction (LVEF) and test a novel LVEF calculation considering these factors. Results 10 pigs were studied. The experimental protocol consisted of sequentially changing afterload, preload and contractility. LV pressure–volume (PV) loops and peripheral arterial pressure were obtained before and after each intervention. LVEF was calculated as stroke volume (SV)/end-diastolic volume (EDV). We studied global cardiac function variables: LV end-systolic elastance (Ees), effective arterial elastance (Ea), end-diastolic volume and heart rate. Diastolic function was evaluated by means of the ventricular relaxation time ( τ ) and ventricular stiffness constant ( β ) obtained from the end-diastolic PV relationship. Ventriculo-arterial coupling (VAC), an index of cardiovascular performance, was calculated as Ea/Ees. LV mechanical efficiency (LVeff) was calculated as the ratio of stroke work to LV pressure–volume area. A linear mixed model was used to determine the impact of cardiac factors (Ees, Ea, EDV and heart rate), VAC and LVeff on LVEF during all experimental conditions. LVEF was mainly related to Ees and Ea. There was a strong relationship between LVEF and both VAC and LVeff ( r 2 = 0.69 and r 2 = 0.94, respectively). The relationship between LVEF and Ees was good ( r 2 = 0.43). Adjusting LVEF to afterload ( ) performed better for estimating Ees ( r 2 = 0.75) and improved the tracking of LV contractility changes, even when a peripheral Ea was used as surrogate (Ea = radial MAP/SV; r 2 = 0.73). Conclusions LVEF was mainly affected by contractility and afterload changes and was strongly related to VAC and LVeff. An adjustment to LVEF that considers the impact of afterload provided a better assessment of LV contractility.

Hyperdynamic Left Ventricular Ejection Fraction in ICU Patients With Sepsis

“…Hypovolemia has also been implicated in HDLVEF development (24), although we found no difference in net fluid balance or IV fluid input between LVEF cohorts. Furthermore, previous studies have demonstrated that large variations in preload did not influence LVEF (14). Impaired LV relaxation may reduce preload, resulting in a compensatory hyperdynamic state.…”

Assessment of left ventricular systolic function by non-invasive pressure-strain loop area in young male strength athletes

“…The above results illustrated that subclinical changes in LV systolic function have occurred in athletes and MW indexes were more sensitive to provide early diagnosis value for LV performance among athletes [ 24 ]. According to the ROC analysis about LVMW parameters, GWE (AUC = 0.733) was considered of being the best predictor of LV systolic function in athletes and superior to GLS (AUC = 0.627) which was principally limited by the defect of being load-dependent and might lead to errors in judging LV performance [ 25 ].…”

Noninvasive estimation of aortic hemodynamics and cardiac contractility using machine learning

“…In addition, cfPWV is a measure of arterial compliance, which is also determinant of stroke volume and thus CO. Finally, EF and E es have been reported to be positively correlated 46 and this further explains the high importance level of EF for predicting E es . The results using different subsets of the input features further verified each feature’s contribution to the predictions of the target output variables.…”