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Nikolaos Stergiopoulos

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Related publications (229)

Page 3 of 12

Assessment of Stiffness of Large to Small Arteries in Multistage Renal Disease Model: A Numerical Study

Nikolaos Stergiopoulos, Vasiliki Bikia

Arterial stiffness (AS), as assessed via pulse wave velocity (PWV), is a major biomarker for cardiovascular risk assessment in patients with chronic kidney disease (CKD). However, the mechanisms responsible for the changes in PWV in the presence of kidney ...

FRONTIERS MEDIA SA2022

Nonlinear isochrones in murine left ventricular pressure-volume loops: how well does the time-varying elastance concept hold?

Nikolaos Stergiopoulos

The linear time-varying elastance theory is frequently used to describe the change in ventricular stiffness during the cardiac cycle. The concept assumes that all isochrones (i.e., curves that connect pressure-volume data occurring at the same time) are li ...

2005

In vivo evaluation of a novel 'diastole-patching' algorithm for the estimation of pulse transit time: advancing the precision in pulse wave velocity measurement

Nikolaos Stergiopoulos, Orestis Vardoulis

Carotid-to-femoral pulse wave velocity (PWV) is the gold standard for the assessment of aortic stiffness. It is calculated by the ratio of pulse transit time (PTT) between two arterial sites and the distance between them. The precision of PTT estimation de ...

Institute of Physics2015

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

Three- and four-element Windkessel models: assessment of their fitting performance in a large cohort of healthy middle-aged individuals

Nikolaos Stergiopoulos

Lumped-parameter models are used to estimate the global arterial properties by fitting the model to measured (aortic) pressure and flow. Different model configurations coexist, and it is still an open question as to which model optimally reflects the arter ...

2008

Influence of inlet boundary conditions on the local haemodynamics of intracranial aneurysms

Nikolaos Stergiopoulos, Philippe Reymond

Haemodynamics is believed to play an important role in the initiation, growth and rupture of intracranial aneurysms. In this context, computational haemodynamics has been extensively used in an effort to establish correlations between flow variables and cl ...

2009

Dissecting Abdominal Aortic Aneurysm in Angiotensin II-Infused Mice: The Importance of Imaging

Nikolaos Stergiopoulos, Bram Trachet, Alessandra Piersigilli

Introduction. Since the initial publication in 2000, Angiotensin II-infused mice have become one of the most popular models to study abdominal aortic aneurysm in a pre-clinical setting. We recently used phase contrast X-ray based computed tomography to dem ...

2015

RC time constant of single lung equals that of both lungs together: a study in chronic thromboembolic pulmonary hypertension

Nikolaos Stergiopoulos

The product of resistance, R, and compliance, C (RC time), of the entire pulmonary circulation is constant. It is unknown if this constancy holds for individual lungs. We determined R and C in individual lungs in chronic thromboembolic pulmonary hypertensi ...

2009

AI-Based Estimation of End-Systolic Elastance From Arm-Pressure and Systolic Time Intervals

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

Left ventricular end-systolic elastance (Ees) is a major determinant of cardiac systolic function and ventricular-arterial interaction. Previous methods for the Ees estimation require the use of the echocardiographic ejection fraction (EF). However, given ...

2021

Estimation of Left Ventricular End-Systolic Elastance From Brachial Pressure Waveform via Deep Learning

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

Determination of left ventricular (LV) end-systolic elastance (E- es ) is of utmost importance for assessing the cardiac systolic function and hemodynamical state in humans. Yet, the clinical use of E- es is not established due to the invasive nature and h ...

FRONTIERS MEDIA SA2021

A new self-adjustable glaucoma valve

Julien Maxime Gerber, Soroush Rafiei, Nikolaos Stergiopoulos, Stéphane Bigler

Introduction: Glaucoma, the leading cause of irreversible blindness globally, affects more than 70 million people across the world. When initial treatments prove ineffective, especially for cases with high intraocular pressure (IOP), the preferred approach ...

Frontiers Media Sa2024

Cardiovascular morphometry with high-resolution 3D magnetic resonance: First application to left ventricle diastolic dysfunction

Nikolaos Stergiopoulos, Orestis Vardoulis, Davide Piccini

In this study, an image-based morphometry toolset quantifying geometric descriptors of the left ventricle, aorta and their coupling is applied to investigate whether morphological information can differentiate between subjects affected by diastolic dysfunc ...

Elsevier2017

Regulation of arginase pathway in response to wall shear stress

Nikolaos Stergiopoulos, Rafaela Fernandes Da Silva, Paolo Silacci, Veronica Gambillara

Alterations of wall shear stress can predispose the endothelium to the development of atherosclerotic plaques. Ample evidence indicates that arginase expression and/or activity correlates with several risk factors for cardiovascular disease including ather ...

Elsevier2009

Tumescense monitoring system for diagnosing erectile dysfunction and methods of use

Nikolaos Stergiopoulos, Rodrigo Araujo Fraga Da Silva

Systems and methods for monitoring penile tumescence are provided that overcome the drawbacks of previously known systems by providing a wearable formed of a flexible and elastic tube having a plurality of sensors disposed on or embedded within it, the wea ...

2023

Individualization of transfer function in estimation of central aortic pressure from the peripheral pulse is not required in patients at rest

Nikolaos Stergiopoulos

Central aortic pressure gives better insight into ventriculo-arterial coupling and better prognosis of cardiovascular complications than peripheral pressures. Therefore transfer functions (TF), reconstructing aortic pressure from peripheral pressures, are ...

2008

RGD-Functionalized polymer brushes as substrates for the integrin specific adhesion of human umbilical vein endothelial cells

Nikolaos Stergiopoulos, Harm-Anton Klok, Stefano Tugulu, Paolo Silacci

This report demonstrates the feasibility of surface-initiated atom transfer radical polymerization to prepare thin polymer layers ("brushes") that can be functionalized with short peptide ligands and which may be of use as coatings to promote endothelializ ...

2007

Arterial remodeling in response to increased blood flow using a constituent-based model

Nikolaos Stergiopoulos

Previous theoretical models of arterial remodeling in response to changes in blood flow were based on the assumption that material properties of the arterial wall remain unchanged during the remodeling process. According to experimental findings, however, ...

2009

Contribution of the Arterial System and the Heart to Blood Pressure during Normal Aging - A Simulation Study

Nikolaos Stergiopoulos

During aging, systolic blood pressure continuously increases over time, whereas diastolic pressure first increases and then slightly decreases after middle age. These pressure changes are usually explained by changes of the arterial system alone (increase ...

Public Library of Science2016

Diminazene Protects Corpus Cavernosum Against Hypercholesterolemia-Induced Injury

Nikolaos Stergiopoulos, Rafaela Fernandes Da Silva, Mikaël Nils Sturny, Younouss Faye

IntroductionAngiotensin-converting enzyme 2 (ACE2) is a key enzyme of the renin angiotensin system, which breaks down angiotensin II and forms angiotensin-(1-7). In erectile tissues, it has been documented that angiotensin II contributes to the development ...

Wiley-Blackwell2015

A coupled hydrodynamic model of the cardiovascular and cerebrospinal fluid system

Nikolaos Stergiopoulos, Philippe Reymond

Martin BA, Reymond P, Novy J, Baledent O, Stergiopulos N. A coupled hydrodynamic model of the cardiovascular and cerebrospinal fluid system. Am J Physiol Heart Circ Physiol 302: H1492-H1509, 2012. First published January 20, 2012; doi: 10.1152/ajpheart.006 ...

2012