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Concept

Afterload

Publications associées (23)

Compliance-matching vascular grafts with personalization potential

Georgios Rovas

Aortic diseases are characterized by dire prognosis and inadequate diagnosis, owing to their insidious yet lethal nature. Aortopathies, namely aortic aneurysms and dissections, along with certain congenital diseases, might necessitate surgical replacement ...

EPFL2023

The Impact of Left Ventricular Performance and Afterload on the Evaluation of Aortic Valve Stenosis: A 1D Mathematical Modeling Approach

Nikolaos Stergiopoulos

The transaortic valvular pressure gradient (TPG) plays a central role in decision-making for patients suffering from severe aortic stenosis. However, the flow-dependence nature of the TPG makes the diagnosis of aortic stenosis challenging since the markers ...

MDPI2023

Hemodynamic effects of a dielectric elastomer augmented aorta on aortic wave intensity: An in-vivo study

Yves Perriard, Yoan René Cyrille Civet, Thomas Guillaume Martinez, Armando Matthieu Walter, Francesco Clavica, Silje Ekroll Jahren

Dielectric elastomer actuator augmented aorta (DEA) represents a novel approach with high potential for assisting a failing heart. The soft tubular device replaces a section of the aorta and increases its diameter when activated. The hemodynamic interactio ...

2023

Interrelation between cardiac and brain small-vessel disease: a pilot quantitative PET and MRI study

Bénédicte Marie Maréchal, Ricardo Alberto Corredor Jerez

Background: Small-vessel disease (SVD) plays a crucial role in cardiac and brain ischemia, but little is known about potential interrelation between both. We retrospectively evaluated 370 patients, aiming at assessing the interrelation between cardiac and ...

Springernature2023

A comprehensive mathematical model for cardiac perfusion

Alfio Quarteroni, Francesco Regazzoni, Christian Vergara

The aim of this paper is to introduce a new mathematical model that simulates myocardial blood perfusion that accounts for multiscale and multiphysics features. Our model incorporates cardiac electrophysiology, active and passive mechanics, hemodynamics, v ...

Nature Portfolio2023

Arterial Wave Reflection and Aortic Valve Stenosis: Diagnostic Challenges and Prognostic Significance

Nikolaos Stergiopoulos, Vasiliki Bikia, Georgios Rovas, Stamatia Zoi Pagoulatou

IntroductionArterial wave reflection is an important component of the left ventricular afterload, affecting both pressure and flow to the aorta. The aim of the present study was to evaluate the impact of wave reflection on transvalvular pressure gradients ...

FRONTIERS MEDIA SA2022

Acute and Long-Term Effects of Aortic Compliance Decrease on Central Hemodynamics: A Modeling Analysis

Nikolaos Stergiopoulos, Vasiliki Bikia, Georgios Rovas, Stamatia Zoi Pagoulatou

Aortic compliance is an important determinant of cardiac afterload and a contributor to cardiovascular morbidity. In the present study, we sought to provide in silico insights into the acute as well as long-term effects of aortic compliance decrease on cen ...

FRONTIERS MEDIA SA2021

In vivo application and validation of a novel noninvasive method to estimate the end-systolic elastance

Nikolaos Stergiopoulos, Vasiliki Bikia, Georgios Rovas, Stamatia Zoi Pagoulatou

Accurate assessment of the left ventricular (LV) systolic function is indispensable in the clinic. However, estimation of a precise index of cardiac contractility, i.e., the end-systolic elastance (E-es), is invasive and cannot be established as clinical r ...

2021

The effect of the elongation of the proximal aorta on the estimation of the aortic wall distensibility

Nikolaos Stergiopoulos, Vasiliki Bikia, Bram Trachet, Georgios Rovas, Stamatia Zoi Pagoulatou, Mauro Ferraro

The compliance of the proximal aortic wall is a major determinant of cardiac afterload. Aortic compliance is often estimated based on cross-sectional area changes over the pulse pressure, under the assumption of a negligible longitudinal stretch during the ...

2021

Effect of fibre orientation and bulk modulus on the electromechanical modelling of human ventricles

Alfio Quarteroni, Antonello Gerbi

This work concerns the mathematical and numerical modeling of the heart. The aim is to enhance the understanding of the cardiac function in both physiological and pathological conditions. Along this road, a challenge arises from the multi-scale and multi-p ...

2020

Mitochondrial Deacetylase Sirt3 Reduces Vascular Dysfunction and Hypertension While Sirt3 Depletion in Essential Hypertension Is Linked to Vascular Inflammation and Oxidative Stress

Johan Auwerx

Rationale: Hypertension represents a major risk factor for stroke, myocardial infarction, and heart failure and affects 30% of the adult population. Mitochondrial dysfunction contributes to hypertension, but specific mechanisms are unclear. The mitochondri ...

2020

Computational fluid dynamics of blood flow in an idealized left human heart

Alfio Quarteroni, Filippo Menghini

We construct an idealized computational model of the left human heart for the study of the blood flow dynamics in the left atrium and ventricle. We solve the Navier-Stokes equations in the ALE formulation and we prescribe the left heart wall displacement b ...

Wiley2019

Development of Implantable Electrodes Based on Polymer Derived Ceramics

Jonas Grossenbacher

The invention of heart pacemakers in the 50's aims to help patients to overcome heart strokes, which represent the first cause of death worldwide. In Europe and in the USA, more than 3000 pacemakers are implanted every day. Despite the constant evolution o ...

EPFL2015

Helical flows and asymmetry of blood jet in dilated ascending aorta with normally functioning bicuspid valve

Alfio Quarteroni, Christian Vergara, Elena Faggiano

Bicuspid aortic valve (BAV) is associated with aortic dilatation and aneurysm. Several studies evidenced an eccentric systolic flow in ascending aorta associated with increased wall shear stresses (WSS) and the occurrence of an helical systolic flow. This ...

Springer Heidelberg2013

On the Estimation of Total Arterial Compliance from Aortic Pulse Wave Velocity

Nikolaos Stergiopoulos, Orestis Vardoulis

Total arterial compliance (C (T)) is a main determinant of cardiac afterload, left ventricular function and arterio-ventricular coupling. C (T) is physiologically more relevant than regional aortic stiffness. However, direct, in vivo, non-invasive, measure ...

Springer US2012

Ventricle Equilibrium Position in Healthy and Normal Pressure Hydrocephalus Brains Using an Analytical Model

Jean-Marie Drezet, Kamal Shahim

The driving force that causes enlargement of the ventricles remains unclear in case of normal pressure hydrocephalus (NPH). Both healthy and NPH brain conditions are characterized by a low transparenchymal pressure drop, typically 1 mm Hg. The present pape ...

2012

A method for the quantification of the pressure dependent 3D collagen configuration in the arterial adventitia

Nikolaos Stergiopoulos, Jelle Tymen Christiaan Schrauwen

Collagen plays an important role in the response of the arterial wall to mechanical loading and presumably has a load-bearing function preventing overdistension. Collagen configuration is important for understanding this role, in particular in mathematical ...

Elsevier2012

The Effect of Valsartan versus Non-RAAS Treatment on Autoregulation of Cerebral Blood Flow

Jean-Marc Vesin

Background: Cerebral autoregulation (CA) is a protective mechanism which maintains the steadiness of the cerebral blood flow (CBF) through a broad range of systemic blood pressure (BP). Acute hypertension has been shown to reduce the cerebrovascular adapta ...

Karger2012

Bio Simulation of Brain Ventricle Dilation in Normal Pressure Hydrocephalus

Kamal Shahim

Hydrocephalus is a brain disease wherein the ventricles dilate and compress the parenchyma towards the skull. It is primarily characterized by the disruption of the cerebrospinal fluid (CSF) flow within the ventricular system. Normal pressure hydrocephalus ...

EPFL2011

Effects of an aging vascular model on healthy and diseased hearts

Nikolaos Stergiopoulos, Rafaela Fernandes Da Silva, David Jegger

The vitamin D(3) and nicotine (VDN) model is a model of isolated systolic hypertension (ISH) due to arterial calcification raising arterial stiffness and vascular impedance similar to an aged and stiffened arterial tree. We therefore analyzed the impact of ...

2007