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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...
Arterial wave speed estimated invasively from pressure (P) and velocity (U) measurements using the P-U loop method, or non-invasively from diameter (D) and U measurements using the lnD-U loop method, assume that during early systole 1) backward-running waves are absent and 2) wave speed is constant. These assumptions also form the basis of a method for correcting time lags between P (or lnD) and U...
Pulse diagnosis, which is one of methods of diagnosis, is an important factor in oriental medicine. However, a problem in diagnosis with the pulse is that there is no objective standard. Therefore, the practitioners pass on the skill and students learn about pulse diagnosis as a method that depends on speech. In this study, the electronic pulse wave reproduction apparatus, which is an objective and...
Coarctation of the aorta is an obstruction of the aorta and is usually associated with other concomitant cardiovascular abnormalities especially with bicuspid aortic valve stenosis. The objectives of this study are, (1) to investigate the effects of coarctation on the hemodynamics in the aorta to gain a better understanding of the cause of certain post-surgical coarctation problems, (2) to develop...
With increasing interest in the effect of postural changes on arterial blood pressure and vascular properties, it is important to understand effects of pressure-dependent arterial compliance. This study investigates effects of pressure-dependent compliance on pulse wave velocity (PWVar), pressure wave shape, and transmission characteristics in an arterial model of the human arm from heart to radial...
Predicting major adverse events following surgery remains a significant problem. Currently, the perioperative period is too often considered a black box, with risk assessment and prediction largely based on static pre-surgical parameters. Here, we review the problem of intraoperative hypotension and outline some of the opportunities for improved monitoring during surgery
Up to now, we have successfully carried out the non-invasive beat-by-beat measurement of blood pressure (BP) in the root of finger, superficial temporal and radial artery based on the volume-compensation technique with reasonable accuracy. The present study concerns with improvement of control method for this beat-by-beat BP measurement. The measurement system mainly consists of a partial pressurization...
In this work we present an initiative to develop a national (Uruguayan) program to evaluate vascular age and to detect pre-clinical atherosclerosis using: gold-standard technologies; complimentary and integrative approaches to asses arterial functional and structural indexes; data bases systems to process, analyze and determine normal and reference values and to identify the most sensitive markers...
A prototype endoscope for observing inner wall of large arteries was specially designed and evaluated through in vitro and in vivo tests. The purpose of this endoscope is to visualize the inner wall of large arteries, e.g., an aorta, without blocking off the blood stream aiming for the use of an assistive technique for endovascular interventions such as stent-graft placement for aortic aneurysm. The...
Carotid-femoral pulse wave velocity (PWV) has emerged as the gold standard for non-invasive evaluation of aortic stiffness. However, the absence of standardized methodologies of study and lack of normal and references values have limited wider implementation of PWV in clinical practice. In this work normal PWV levels were determined in a Uruguayan population and the obtained values were analyzed taking...
Clinically arterial stiffness has shown that it is the most important cause of cardiovascular complications and also an independent risk factor to several cardiovascular diseases. In routine, there are many preferable non-invasive methods, including pressure-sensitive transducers, applanation tonometry, Doppler ultrasound and MRI, to get insight of cardiovascular condition. However, the operation...
The Windkessel model, coupled with the wave propagation theory, was applied to data measured in the ascending aorta of 11 anaesthetised dogs during total aortic occlusion at the thoracic and diaphragm levels. Wave speed and wave intensity were calculated using the measured pressure (P) and velocity (U), and separately using the pressure due to the wave (Pex) and U in the aorta approximately 1 cm distal...
Gender-related difference in cardiovascular diseases is one of the most investigated and still unsolved issues. Finding an explanation to this topic might have important implications for the understanding of the differences between men and women in diseases and possibly lead to the development of gender-specific strategies for its management. Recent studies have proposed that the capacitive or reservoir...
Wave speed is directly related to arterial distensibility and is widely used by clinicians to assess arterial stiffness. The PU-loop method for determining wave speed is based on the water hammer equation for flow in flexible tubes and artery using the method of characteristics. This technique determines wave speed using simultaneous measurements of pressure and velocity at a single point. The method...
The purpose of this study was to describe the changes in high-frequency QRS (HF-QRS) components due to myocardial ischemia provoked by prolonged artery occlusion during percutaneous coronary interventions (PCI). Signal-averaged ECGs from 69 patients were obtained during PCI procedures and comparison of high-frequency components of the QRS at different temporal regions and frequency bandwidth were...
Pulse oximetry utilises the technique of photople-thysmography (PPG) to estimate arterial oxygen saturation values (SpO2). In poorly perfused tissues, SpO2 readings may be compromised due to the poor quality of the PPG signals. In order to investigate further the threshold where pulse oximetry fails to produce accurate SpO2 values, we have developed a custom made multimode finger pulse oximetry probe...
This study elucidates the vascular internal diameter response of coronary arterial circulation in closed-chest rats to evaluate endothelium-dependent and endothelium-independent vasodilatory ability and to investigate disease mechanisms. For this study, we developed an X-ray intravital microscopy system using a microangiography technique and a synchrotron radiation source at SPring-8. An X-ray direct-conversion...
Phase contrast MRI is a powerful tool for blood flow quantification. Conventional cartesian phase contrast sequences require lengthy acquisition on the order of several minutes. Spiral acquisition phase-contrast (PC) MRI is capable of reducing the TR and TE in order to minimize flow dependent artifacts and total imaging time. Despite this, in general, spiral phase contrast sequences suffer from off-resonance...
Simultaneous measurement of pressure and diameter in blood vessels or vascular prosthesis is of great importance in cardiovascular research. Knowledge of diameter changes as response to intravascular pressure is the basis to estimate the biomechanical properties of blood vessel. In this work a new method to quantify arterial diameter based in high resolution ultrasonography is proposed. Measurements...
Coronary artery disease (CAD) is the leading cause of death in the United States. Although progression of CAD can be controlled using drugs and diet, it is usually detected in advanced stages when invasive treatment is required. Current methods to detect CAD are invasive and/or costly, hence not suitable as a regular screening tool to detect CAD in early stages. Currently, we are developing a noninvasive...
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