Nikolaos Stergiopoulos

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The most effective way to control glaucoma is by lowering intraocular pressure (IOP) in order to prevent the progression of the disease. Glaucoma drainage devices (GDDs) are surgical option reserved for refractory cases and have been designed to address kn ...

Despite many therapeutic advances leading to increasingly effective drug treatments, thrombotic events (such as ischaemic stroke, pulmonary embolism, deep venous thrombosis and acute myocardial infarction) still represent a major worldwide cause of morbidi ...

Acute and long-term (up to 56 days) evolution of geometry, structural properties, vascular smooth muscle (VSM) tone and histomorphometric properties of the rat common carotid arteries under induced hypertension were investigated. Hypertension was induced in 8-week old male Wistar rats by total ligation of the aorta between the two kidneys. Rats were sacrificed 2, 4, 8 and 56 days postsurgery. The arterial wall layers thicken non-uniformly during the adaptation process, the inner layers thicken more in the a

The regulation of cytosolic-free calcium concentration of smooth-muscle and endothelial cells was mainly studied on cultured cells where the cross talk between these two coupled cell types is lost. In the present study, the cytosolic-free calcium concentration in the endothelial and the smooth-muscle cells was examined in an intact arterial wall in vitro. Strips of the main branch of rat mesenteric artery were used. Cytosolic-free calcium concentration [Ca2+]i was estimated by determining the fluorescence r

Although left ventricular end-systolic elastance (E-es) serves as a major index of cardiac contractility, a widely-accepted noninvasive estimation of E-es does not exist. To overcome this limitation, we developed a two-step inverse method that allows for i ...

For the first time, inter-operator dependence of MRI based computational fluid dynamics (CFD) modeling of cerebrospinal fluid (CSF) in the cervical spinal subarachnoid space (SSS) is evaluated. In vivo MRI flow measurements and anatomy MRI images were obta ...

To analyze the effects of decellularization on the biomechanical properties of porcine common carotid arteries, decellularization was performed by a detergent-enzymatic procedure that preserves extracellular matrix scaffold. Internal diameter, external dia ...

The method used for pulse transit time (PTT) estimation critically affects the accuracy and precision of regional pulse wave velocity (PWV) measurements. Several methods of PTT estimation exist, often yielding substantially different PWV values. Since ther ...

This study is concerned with the wave reflection properties of arterial stenoses. Two theoretical models have been developed for deriving the reflection coefficient: a linear model resulting from the linearization of the pressure drop-flow equation and an indirect, quasi-nonlinear model, based on the separation of pressure waves into their forward and backward running components proximal and distal to the stenosis. The linear method gave consistently lower values for the reflection coefficient when compared

Hypertension-induced arterial remodeling has been previously modeled using stress-driven remodeling rate equations in terms of global geometrical adaptation (Rachev A, Stergiopulos N, Meister JJ. Theoretical study of dynamics of arterial wall remodeling in ...

The role of shear stress in atherosclerosis has been well documented. However, its role in restenosis was underexposed. In this paper a novel in vivo measuring technique and several of its applications related to restenosis will be described. The technique consists of a combination of 3D reconstruction of blood vessels and computational fluid dynamics (CFD). The 3D imaging techniques use either of 3D intravascular ultrasound (IVUS) as a stand-alone technique or a fusion of biplane angiography and IVUS (ANGU

Objective To understand the anatomy and physiology of ascending aortic aneurysms in angiotensin II-infused ApoE(-/-) mice. Approach and Results We combined an extensive in vivo imaging protocol (high-frequency ultrasound and contrast-enhanced microcomputed ...

In six dogs and six weight-matched miniature pigs at baseline and after pulmonary embolization, pulmonary arterial compliance was determined using the pulse pressure method (C(PPM)), the three-element windkessel model (C(WK-3)), and the ratio of stroke volume to pulse pressure (SV/PP). C(PPM) was lower in pigs than in dogs at baseline (0.72 +/- 0.23 vs. 1.14 +/- 0.29 ml/mmHg, P < 0.05) and after embolism (0.37 +/- 0.14 vs. 0.54 +/- 0.16 ml/mmHg, P = 0. 07) at matched flow, but not at matched flow and pressu

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 ...

One-dimensional models of the systemic arterial tree are useful tools for studying wave propagation phenomena, however, their formulation for frictional losses is approximate and often based on solutions for developed flow in straight non-tapered arterial ...

Purpose To evaluate the implantability, safety, and intraocular pressure (IOP)–regulating performance of a novel miniaturized passive self-adjustable glaucoma drainage device (eyeValve) in a first-in-human (FIH) feasibility study. Methods Prospective single-arm pilot study in six blind eyes with end-stage glaucoma and uncontrolled IOP. The eyeValve was implanted in a partial-thickness intrascleral pocket and connected to a distal silicone plate (eyePlate) for orbital drainage. No mitomycin C was used

Hemodynamic forces play an active role in vascular pathologies, particularly in relation to the localization of atherosclerotic lesions. It has been established that low shear stress combined with cyclic reversal of flow direction (oscillatory shear stress ...

Aortic aneurysms and dissections are silent and lethal conditions, whose pathogenesis remains incompletely understood. Although angiotensin II (AngII)-infused ApoE-/- mice have been widely used to study aortic aneurysm and dissection, early morphofunctiona ...

Aims:Diminazene aceturate, a putative ACE2 activator, is susceptible to cleavage resulting in the formation of paminobenzamidine (PAB). This study aimed to investigate the effects of PAB in addressing cardiovascular dysfunctions in spontaneously hypertensi ...

The eyeWatch(TM) is a new glaucoma drainage device that includes an adjustable mechanism that can vary the resistance to aqueous humor outflow during the postoperative period to reduce the burden of postoperative intraocular pressure (IOP) management. The ...

Nikolaos Stergiopoulos

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EyeWatch Rescue of Refractory Hypotony After Baerveldt Drainage Device Implantation: Description of a New Technique

The Angiotensin-Converting Enzyme 2/Angiotensin-(1-7)/Mas receptor axis: A potential target for treating thrombotic diseases

Geometrical, functional, and histomorphometric adaptation of rat carotid artery in induced hypertension

Cytosolic-free calcium in smooth-muscle and endothelial cells in an intact arterial wall from rat mesenteric artery in vitro

Estimating Left Ventricular Elastance from Aortic Flow Waveform, Ventricular Ejection Fraction, and Brachial Pressure: An In Silico Study

Inter-operator Reliability of Magnetic Resonance Image-Based Computational Fluid Dynamics Prediction of Cerebrospinal Fluid Motion in the Cervical Spine

Biomechanical properties of decellularized porcine common carotid arteries

Validation of a novel and existing algorithms for the estimation of pulse transit time: advancing the accuracy in pulse wave velocity measurement

On the wave transmission and reflection properties of stenoses

Arterial remodeling in response to hypertension using a constituent-based model

Shear stress, vascular remodeling and neointimal formation

Ascending Aortic Aneurysm in Angiotensin II–Infused Mice: Formation, Progression, and the Role of Focal Dissections

Pulmonary arterial compliance in dogs and pigs: the three-element windkessel model revisited

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

Patient-specific mean pressure drop in the systemic arterial tree, a comparison between 1-D and 3-D models

First-in-human implantation of a self-adjustable glaucoma drainage device (eyeValve): safety and performance in blind eyes

Plaque-prone hemodynamics impair endothelial function in pig carotid arteries

Early Morphofunctional Changes in AngII-Infused Mice Contribute to Regional Onset of Aortic Aneurysm and Dissection

p-Aminobenzamidine attenuates cardiovascular dysfunctions in spontaneously hypertensive rats

MRI after successful eyeWatch(TM) implantation