Dynamic Arterial Elastance as a Ventriculo-Arterial Coupling Index: An Experimental Animal Study

Abstract

Dynamic arterial elastance (Ea dyn), the ratio between arterial pulse pressure and stroke volume changes during respiration, has been postulated as an index of the coupling between the left ventricle (LV) and the arterial system. We aimed to confirm this hypothesis using the gold-standard for defining LV contractility, afterload, and evaluating ventricular-arterial (VA) coupling and LV efficiency during different loading and contractile experimental conditions. Twelve Yorkshire healthy female pigs submitted to three consecutive stages with two opposite interventions each: changes in afterload (phenylephrine/nitroprusside), preload (bleeding/fluid bolus), and contractility (esmolol/dobutamine). LV pressure-volume data was obtained with a conductance catheter, and arterial pressures were measured via a fluid-filled catheter in the proximal aorta and the radial artery. End-systolic elastance (Ees), a load-independent index of myocardial contractility, was calculated during an inferior vena cava occlusion. Effective arterial elastance (Ea, an index of LV afterload) was calculated as LV end-systolic pressure/stroke volume. VA coupling was defined as the ratio Ea/Ees. LV efficiency (LV eff) was defined as the ratio between stroke work and the LV pressure-volume area. Ea dyn was calculated as the ratio between the aortic pulse pressure variation (PPV) and conductance-derived stroke volume variation (SVV). A linear mixed model was used for evaluating the relationship between Ees, Ea, VA coupling, LV eff with Ea dyn. Ea dyn was inversely related to VA coupling and directly to LV eff. The higher the Ea dyn , the higher the LV eff and the lower the VA coupling. Thus, Ea dyn , an easily measured parameter at the bedside, may be of clinical relevance for hemodynamic assessment of the unstable patient.

Dynamic Arterial Elastance During Experimental Endotoxic Septic Shock: A Potential Marker of Cardiovascular Efficiency

“…These findings corroborate previous results about the compound nature of Ea dyn and the impact of both cardiac and arterial factors ( Monge Garcia et al, 2020 ). While net changes in Ea, a net measure of LV afterload, were negatively associated with Ea dyn , variations in heart rate did so positively ( Monge Garcia et al, 2017 ; de Courson et al, 2019 ).…”

“…Septic animals also showed a significant decrease in arterial tone, as reflected by an increase in net arterial compliance ( Cherpanath et al, 2014 ). This study, together with our previous observations about the impact of changes in arterial load ( Monge Garcia et al, 2017 ), support the notion that Ea dyn does not represent a real measure of central arterial tone nor an index of the arterial stiffness, and that the concept of Ea dyn as a variable describing LV afterload should be avoided ( Monge Garcia et al, 2020 ).…”

“…Therefore, changes in Osc% and EER were inversely associated with Ea dyn variations. Accordingly, when cardiovascular efficiency increases, so does the Ea dyn ( Monge Garcia et al, 2020 ).…”

“…Although Ea dyn was initially defined as a variable describing central arterial tone, Ea dyn is affected not only by arterial factors but also by the heart rate (HR) and the pattern of blood flow during experimental changes in arterial load conditions ( Monge Garcia et al, 2017 ). Moreover, we have recently demonstrated a significant relationship between Ea dyn , ventriculo-arterial coupling, and LV mechanical efficiency ( Monge Garcia et al, 2020 ). Accordingly, Ea dyn could be considered as a composite index reflecting the interaction between both arterial and cardiac factors and potentially providing valuable information regarding cardiovascular performance and ventriculo-arterial coupling.…”

Fluid expansion improve ventriculo-arterial coupling in preload-dependent patients: a prospective observational study

“…The dynamic arterial elastance can be easely measured with invasive and non-invasive hemodynamic devices [ 29 – 31 ]. Dynamic arterial elastance is a real time indicator of the interaction between the heart and the vascular system that has been challenged as an indicator of V-A coupling [ 32 , 33 ]. Several clinical studies have demonstrated that dynamic arterial elastance is able to predict SV and blood pressure response to FC or norepinephrine, and it can be used to optimize treatment [ 17 , 29 – 32 , 34 ].…”