Publications by Nikolaos Stergiopoulos

Machine learning-enabled estimation of cardiac output from peripheral waveforms is independent of blood pressure measurement location in an in silico population

Nikolaos Stergiopoulos, Lydia Aslanidou, Georgios Rovas, Sokratis Anagnostopoulos

Monitoring of cardiac output (CO) is a mainstay of hemodynamic management in the acutely or critically ill patient. Invasive determination of CO using thermodilution, albeit regarded as the gold standard, is cumbersome and bears risks inherent to catheteri ...

2025

Testing an inverse modeling approach with gradient boosting regression for stroke volume estimation using patient thermodilution data

Nikolaos Stergiopoulos, Vasiliki Bikia, Georgios Rovas

Stroke volume (SV) is a major indicator of cardiovascular function, providing essential information about heart performance and blood flow adequacy. Accurate SV measurement is particularly important for assessing patients with heart failure, managing patie ...

FRONTIERS MEDIA SA2025

Evaluation of a novel compliance-matching aortic graft in a swine model

Nikolaos Stergiopoulos, Vasiliki Bikia, Georgios Rovas

The mismatch of elastic properties between the arterial tissue and the vascular grafts, commonly called compliance mismatch, is responsible for many deleterious post-operative complications. Currently, there is an absence of prostheses that conform with th ...

2025

The renin-angiotensin system in healthy human platelets: expressed but inactive

Nikolaos Stergiopoulos, François Cuenot

Platelets play a crucial role in arterial thrombus formation, offering potential for new antiplatelet therapies with reduced bleeding risk. Here, we investigated the role of the renin-angiotensin system (RAS) in human platelets and explored its potential l ...

Informa UK Limited2025

Left atrial wall shear stress correlates with fibrosis in patients with atrial fibrillation

Nikolaos Stergiopoulos, Georgios Rovas

Left atrial wall fibrosis has an important role in atrial fibrillation (AF) because of the abnormal electrophysiological properties of the fibrotic areas. However, the mechanisms behind the development of left atrial fibrosis are not well understood. Here, ...

Springer Science and Business Media LLC2025

Residual-based attention in physics-informed neural networks

Nikolaos Stergiopoulos, Sokratis Anagnostopoulos

Driven by the need for more efficient and seamless integration of physical models and data, physics -informed neural networks (PINNs) have seen a surge of interest in recent years. However, ensuring the reliability of their convergence and accuracy remains ...

Elsevier Science Sa2024

Local Shear Stress and Dyslipidemia Interfere with Actin Cyto-Skeleton and Lysosomal Organization Contributing to Vascular Fragility

Nikolaos Stergiopoulos, Rodrigo Araujo Fraga Da Silva

Shear stress is one of the major hemodynamic forces acting on the endothelium. However, it is not well known how endothelial cells (EC) respond mechanically to these stimuli in vivo. Here we investigated whether changes in biomechanics properties and shear ...

2024

Impact of arterial system alterations due to amputation on arterial stiffness and hemodynamics: a numerical study

Nikolaos Stergiopoulos

Subjects with amputation of the lower limbs are at increased risk of cardiovascular mortality and morbidity. We hypothesize that amputation-induced alterations in the arterial tree negatively impact arterial biomechanics, blood pressure and flow behavior. ...

Nature Research2024

Compliant vascular grafts and methods of use

Nikolaos Stergiopoulos, Georgios Rovas

Compliant vascular grafts for implantation in the vasculature are provided. The compliant vascular grafts are designed to expand longitudinally and radially within a blood vessel, such as an artery, and is expected to be particularly well suited for treati ...

2024

Novel theory and potential applications of central diastolic pressure decay time constant

Nikolaos Stergiopoulos, Patrick Segers, Vasiliki Bikia, Georgios Rovas, Sokratis Anagnostopoulos

Central aortic diastolic pressure decay time constant ( ) is according to the two-element Windkessel model equal to the product of total peripheral resistance (R) times total arterial compliance (C ). As such, it is related to arterial stiffness, which has ...

2024

A new self-adjustable glaucoma valve

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

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

Apparatus for non-invasively computing cardio-vasculature parameters using morphology of uncalibrated pressure wave signal

Nikolaos Stergiopoulos, Vasiliki Bikia, Georgios Rovas

Systems and apparatus are provided for using a non-invasively monitored uncalibrated pressure signal from a patient to compute cardiac output and other cardio-vascular parameters, thereby providing safe, effective, reliable and low cost monitoring of patie ...

2024

Method and apparatus for non-invasively computing cardio-vasculature parameters using morphology of uncorrelated pressure wave signal

Nikolaos Stergiopoulos, Vasiliki Bikia

[0054] Methods are provided for estimating key reliably and accurately predicting cardiac output using a limited set of non-invasively monitored physiologic inputs, and a calibrated one- dimensional arterial tree model, a database of synthetic data generat ...

2024

In Silico Validation of Non-Invasive Arterial Compliance Estimation and Potential Determinants of its Variability

Nikolaos Stergiopoulos, Vasiliki Bikia

Arterial compliance (AC) is an important cardiovascular parameter characterizing mechanical properties of arteries. AC is significantly influenced by arterial wall structure and vasomotion, and it markedly influences cardiac load. A new method, based on a ...

2024

Effect of the structural modification of Candesartan with Zinc on hypertension and left ventricular hypertrophy

Nikolaos Stergiopoulos, Augusto Martins Lima, Valeria Romina Martinez

Hypertension is the most common cause of left ventricular hypertrophy, contributing to heart failure progression. Candesartan (Cand) is an angiotensin receptor antagonist widely used for hypertension treatment. Structural modifications were previously perf ...

ELSEVIER2023

On the similarity between aortic and carotid pressure diastolic decay: a mathematical modelling study

Nikolaos Stergiopoulos, Vasiliki Bikia, Georgios Rovas, Sokratis Anagnostopoulos

Aortic diastolic pressure decay (DPD) has been shown to have considerable pathophysiological relevance in the assessment of vascular health, as it is significantly affected by arterial stiffening. Nonetheless, the aortic pressure waveform is rarely availab ...

Nature Portfolio2023

Design and computational optimization of compliance-matching aortic grafts

Nikolaos Stergiopoulos, Vasiliki Bikia, Georgios Rovas

Introduction: Synthetic vascular grafts have been widely used in clinical practice for aortic replacement surgery. Despite their high rates of surgical success, they remain significantly less compliant than the native aorta, resulting in a phenomenon calle ...

FRONTIERS MEDIA SA2023

In Memoriam of Nico Westerhof (1937-2022)

Nikolaos Stergiopoulos, Patrick Segers

BMC2023

Quantification of the Phenomena Affecting Reflective Arterial Photoplethysmography

Nikolaos Stergiopoulos, Vasiliki Bikia, Georgios Rovas

Photoplethysmography (PPG) is a widely emerging method to assess vascular health in humans. The origins of the signal of reflective PPG on peripheral arteries have not been thoroughly investigated. We aimed to identify and quantify the optical and biomecha ...

MDPI2023

Wet adhesive hydrogels to correct malacic trachea (tracheomalacia) A proof of concept

Dominique Pioletti, Nikolaos Stergiopoulos, Peyman Karami, Ece Uslu, Vijay Kumar Rana, Sokratis Anagnostopoulos

Tracheomalacia (TM) is a condition characterized by a weak tracheal cartilage and/or muscle, resulting in excessive collapse of the airway in the newborns. Current treatments including tracheal reconstruction, tracheoplasty, endo- and extra-luminal stents ...

CELL PRESS2023