Left ventricular function: time-varying elastance and left ventricular aortic coupling

Abstract

Many aspects of left ventricular function are explained by considering ventricular pressure–volume characteristics. Contractility is best measured by the slope, Emax, of the end-systolic pressure–volume relationship. Ventricular systole is usefully characterized by a time-varying elastance (ΔP/ΔV). An extended area, the pressure–volume area, subtended by the ventricular pressure–volume loop (useful mechanical work) and the ESPVR (energy expended without mechanical work), is linearly related to myocardial oxygen consumption per beat. For energetically efficient systolic ejection ventricular elastance should be, and is, matched to aortic elastance. Without matching, the fraction of energy expended without mechanical work increases and energy is lost during ejection across the aortic valve. Ventricular function curves, derived from ventricular pressure–volume characteristics, interact with venous return curves to regulate cardiac output. Thus, consideration of ventricular pressure–volume relationships highlight features that allow the heart to efficiently respond to any demand for cardiac output and oxygen delivery.

Nicotinamide mononucleotide requires SIRT3 to improve cardiac function and bioenergetics in a Friedreich’s ataxia cardiomyopathy model

“…Depressed CE is a salient feature of ventricular energetics during HF (34)(35)(36). Strikingly, CE in the FXN-KO was normalized with NMN supplementation ( Figure 4C).…”

“…Restoration of CE required SIRT3, as CE remained depressed in NMN-treated dKO hearts. An additional parameter of energy efficiency in the heart is the ventriculoarterial coupling (VC) ratio, which measures the efficiency of the heart to transfer mechanical energy (ME) from the ventricle to hydraulic energy in the aorta during contraction (34)(35)(36). In failing hearts, decreased systolic contractility ( Figure 3, G-I) contributes to decreased ventricular systolic elastance, which corresponds to an increase in the VC ratio at baseline in the saline-treated FXN-KO and dKO heart failing models ( Figure 4D).…”

Ventricular stroke work and vascular impedance refine the characterization of patients with aortic stenosis

“…As a composite metric, SWLV represents the LV energetic state and incorporates ventricular geometry and its mechanical properties, as well as valvular and vascular impedances (13)(14)(15).…”

“…We applied advanced computational models to calculate left ventricular stroke work (SWLV) and vascular impedance in patients before and after TAVR. SWLV represents the work the LV performs by displacing blood against the impedances of the aortic valve and the vascular system (13)(14)(15). It is a measure of the energetic state of the LV directly influenced by the valvular and vascular compartments and might represent a comprehensive hemodynamic metric of LV energetic state in patients with AS before and after intervention.…”

Detection of Movement toward Randomness by Applying the Block Decomposition Method to a Simple Model of the Circulatory System

“…The PVL can provide valuable information for diagnosis, monitoring and treatment of a particular patient. The area inside PVL is considered to be indicative of myocardial oxygen demand [8], a parameter that cannot be directly assessed but can drastically influence the disease course, outcome and treatment.…”