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Introduction: Measurement of hemodynamic parameters constitutes an important tool in the management of patients with cirrhosis. In recent years, non-invasive measurements have gain attention, due to the potential complications associated to invasive procedures. Objective: To characterize the hemodynamic alterations of cirrhosis in young and adult subjects, through a three element windkessel (WK3e)...
Abdominal aortic aneurysm (AAA) is a pathological dilation of the abdominal aorta, generally distal to the renal arteries. In relation to this, minimally invasive endovascular aortic repair has become a common technique, and great efforts have been made to characterize surgical outcome in terms of endograft displacement, leakages, aneurysm sac enlargement or other post-operative complication. Recently,...
Cardiovascular diseases are the main cause of mortality. Many times healthcare professionals tend to segregate patient populations in different kind of risks: low, intermediate and high depending on standard clinical variables such as age, systolic blood pressure (SBP), smoking and diabetes. Normally one of the most used factors for risk stratification is low density lipoprotein (LDL) as well as Framingham...
Introduction: The interest on computational simulations of biomedical models has increased in the last years. Nevertheless, the viscous properties of vessel all are usually neglected. Materials and Methods: A 1D model of blood flow and its interaction with the arterial wall was implemented. Non-viscous modeling and the addition of a wall-viscosity term were considered. The goodness of fit in each...
Introduction: In recent years, peripheral arterial tonometry (PAT, a non-invasive and reproducible technique) has gained considerable interest. In this sense, arterial capacity to react to vasoactive stimulus (induced by reactive hyperemia) is known as vascular reactivity (VR). Objective: Post ischemic beat to beat VR characterization was performed based on PAT measurements. Methods: Systolic Blood...
Application of 1D modelling to arterial networks description provides a computational low cost alternative, compared to 2D/3D simulations. However, wall viscosity is usually neglected in numerical solutions. A simplified 1D tapered model was implemented, considering the vascular path between central (aortic, cBP) and peripheral (radial, rBP) arterial blood pressures. Simulated rBP was generated using...
Development of electrospun scaffolds for tissue engineering vascular grafts requires the integration of well differentiated and complementary disciplines. The aim of present work is to describe a cooperative experience in biomedical research developed between academic institutions of Argentina and Uruguay. Electrospinning technique, high resolution ultrasound in-vitro measurements and signal processing...
To quantify fluid-structure interactions in arterial walls, from a biomechanical standpoint, a complete characterization of blood flow, shear stress in the interface between blood and endothelium, wall elasticity and wall stresses distribution are needed.
Flow-mediated dilatation (FMD) is the most accepted technique for the evaluation of endothelial function. However, it has been show a great inter-subject variability limiting its clinical use. Carotid-radial pulse wave velocity (PWVcr) was proposed as an alternative tool for the evaluation of endothelial function. At the present, there is no doubt that PWVcr reduces its values in response to reactive...
Atherosclerotic plaque complication is a major cause of vascular accidents. Although a variety of factors have been proposed as key factors in these process, the mechanism that contribute to this problem remain to be characterized. Previously we demonstrated that changes in arterial wall viscous and elastic properties and/or in the filtering function (FF) could be part of the arterial wall alterations...
Although a variety of factors have been proposed as key factors of the atherosclerotic plaque vulnerability, the mechanisms that contribute to this problem are not yet fully characterized. In previous works we demonstrated that changes in arterial wall viscosity and elasticity and/or in the filtering function (FF) could be in the basis of arterial wall alterations. If these properties are altered...
The early detection of biomechanical modifications in the arterial wall could be used as a predictor factor for various diseases, for example hypertension or atherosclerosis. In this work a transient elastography technique is used for the in vitro evaluation of the arterial wall elasticity. The obtained Young modulus is compared with the one obtained by a more classical approach: pressure-diameter...
This study uses linear and nonlinear viscoelastic models to describe the dynamic distention of the aorta induced by time-varying arterial blood pressure. We employ an inverse mathematical modeling approach on a four-parameter (linear) Kelvin viscoelastic model and two five-parameter nonlinear viscoelastic models (arctangent and sigmoid) to infer vascular biomechanical properties under in vivo and...
The analysis of carotid-radial pulse wave velocity (PWVcr) changes in response to forearm transient ischemia (TI) has been proposed as an alternative approach to evaluate endothelial function. Consider flow mediated dilatation tests, PWVcr changes are characterized after 5 minutes of TI. It is unknown if lower TI times could be used and if different TI times would result in different PWVcr responses...
The value of mean arterial pressure (MBP) is of clinical importance, and is required for peripheral resistance calculation as well as for central blood pressure calibration procedures. MBP is usually estimated at the upper arm using systolic and diastolic sphygmomanometers pressure values, as 33% of pulse pressure (PP) above diastolic pressure. In a previous work, we proposed to use 38%. The aim of...
This paper is intended to mention some organizations detailing the type of activities being carried out and the action strategies; to analyze the situation in our country and, finally, to publicize our proposal to this problem. Capitalizing the experience gained in other parts of the world by different entities in order to promote the engineering humanitarian in our country, democratizing access to...
In several clinical and experimental circumstances, it is widely necessary to characterize the bio-mechanical changes induced by atherosclerosis to the arterial wall. In this context, the purpose of this paper is twofold. Firstly, to propose a low cost ultrasound setup to improve artery radii determination in elasticity experiments, based on two transducers using a single channel ultrasound hardware...
Atherosclerotic plaques form at specific sites of the arterial tree, an observation that has led to the "geometric risk factor" hypothesis for atherogenesis. It is accepted that the location of atherosclerotic plaques is correlated with sites subjected to low abnormal values of wall shear stress (WSS), which is in turn determined by the specific geometry of the arterial segment. In particular,...
There is a pressing need to obtain adequate vascular substitutes for arterial by-pass or reconstruction. Since the performance of venous and commercially prosthetic grafts is not ideal and the availability of autologous arteries is limited, the use of cryopreserved arteries has emerged as a very attractive alternative. In this sense, the development of an inter-continental network for cryopreserved...
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