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Results 501 - 550 of 1816
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Lee Hwansung - - 2008
To investigate the characteristics of cavitation intensity, we performed a synchronized analysis of the visual images of cavitation and the pressure signals using a pulsatile device. The pulsatile device employed was a pneumatic ventricular assist device (PVAD) that is currently being developed by our group. A 23-mm Medtronic Hall valve ...
Ozay Batuhan - - 2008
BACKGROUND: The aims of this study were to elucidate the incidence of mitral regurgitation during off-pump coronary artery bypass (OPCAB) surgery to evaluate the relationship of the changes with ventricular function and possible mitral valve regurgitation caused by positioning. METHODS: Included in the study were 60 consecutive patients who underwent ...
Johnson Brandon E - - 2008
Pressure-polishing is a method for shaping glass pipettes for patch-clamp recording. We first developed this method for fabricating pipettes suitable for recording from small (<3 m) neuronal cell bodies. The basic principal is similar to glass-blowing and combines air pressure and heat to modify the shape of patch pipettes prepared ...
Zervides Constantinos - - 2008
It is widely accepted that venous valves play an important role in reducing the pressure applied to the veins under dynamic load conditions, such as the act of standing up. This understanding is, however, qualitative and not quantitative. The purpose of this paper is to quantify the pressure shielding effect ...
Allin David M DM Shunt Evaluation Laboratory & Academic Neurosurgical Unit, Addenbrooke's Hospital, P,O, Box 167, Hills Road, Cambridge CB2 2QQ, UK. - - 2008
The Polaris valve is a newly released hydrocephalus shunt that is designed to drain cerebrospinal fluid (CSF) from the brain ventricles or lumbar CSF space. The aim of this study was to bench test the properties of the Polaris shunt, independently of the manufacturer. The Polaris Valve is a ball-on-spring ...
Prince Martin R - - 2007
Characterization of vascular lesions on the basis of visual estimation of percentage stenosis is a valuable but limited procedure. In this issue, Lum et al (1) describe a fast, noninvasive four-dimensional MR method for accurate determination of pressure gradient maps, which correlate with direct pressure gradient measurements across vascular lesions ...
Abe Yukio - - 2008
Mitral regurgitation, when it arises from functional restriction of mitral leaflet closure, can be relieved by surgical cutting of the mitral tendineae chordae. We hypothesized that high intensity focused ultrasound (HIFU) might be useful as a noninvasive extracorporeal technique for cutting mitral chordae. As a pilot study to test this ...
Cui Wei - - 2007
BACKGROUND: Mean mitral valve pressure gradient (MVPG) is one of the key measures of the severity of mitral stenosis. The method for calculating MVPG, however, is complex and time consuming. The purpose of this study is to establish a new simple method for calculating MVPG. METHODS: Hemodynamic data were analyzed ...
Gur M - - 2008
We aimed to investigate the association between aortic distensibility (AD) and left ventricle myocardial performance index (MPI) in patients with newly diagnosed hypertension (HT). We studied 49 patients with HT and 24 healthy control subjects. AD was calculated from the echocardiographically derived ascending aorta diameters. The MPI was calculated from ...
Domec Jean-Christophe - - 2007
Our goals were to quantify how non-embolism-inducing pressure gradients influence trunk sapwood specific conductivity (k(s)) and to compare the impacts of constant and varying pressure gradients on k(s) with KCl and H2O as the perfusion solutions. We studied six woody species (three conifers and three angiosperms) which varied in pit ...
Kheradvar Arash - - 2007
Several studies have suggested that the mitral annulus displacement and velocity in early diastole can be used as indicators of diastolic performance. The peak velocity of the mitral annulus away from the LV apex during early diastole, which indicates the rate of longitudinal expansion of the LV, is reduced in ...
Timek Tomasz A - - 2007
BACKGROUND: Our prior studies suggest that mitral annular septal-lateral (SL) diameter is the chief determinant of "Alfieri stitch" tension, but hemodynamic parameters may also play a role. We approximated the central edge of the mitral leaflets with a miniature force transducer to measure tension (T) at the leaflet approximation point ...
Seddon P - - 2007
Interrupter resistance (R(int)) is a widely used measure of airway caliber, but concerns remain about repeatability and sensitivity. Some R(int) variability may derive from the linear back-extrapolation algorithm (LBE 30/70) usually used to estimate driving pressure. To investigate whether other methods of estimating driving pressure could improve repeatability and sensitivity, ...
Rhodes Katherine D - - 2007
BACKGROUND AND AIM OF THE STUDY: Pressure recovery is a source of discrepancy between Doppler-derived and catheter aortic valve pressure drops. Pressure recovery occurs where the stenotic jet reattaches to the aortic wall. An equation to predict the jet reattachment location has been developed based on the density and viscosity ...
Jouan Jerome - - 2007
BACKGROUND AND AIM OF THE STUDY: In a previous sono-metric study, changes were described that occurred in the normal tricuspid valve during the cardiac cycle. However, the wealth of data available suggested the need for reporting further findings that should contribute to a better understanding of the dynamics of the ...
Arai Shiori - - 2007
CASE DESCRIPTION: A 5-year-old male German Shepherd Dog was evaluated because of a 5-month history of progressive lethargy, weight loss, and heart failure. CLINICAL FINDINGS: On physical examination, bounding femoral pulses and systolic and diastolic murmurs were detected. Echocardiography revealed severe aortic valve insufficiency (AVI) and a large vegetative lesion ...
Uzun Mehmet - - 2007
INTRODUCTION: Although its accuracy has been documented in many studies, the proximal isovelocity surface area (PISA) method is not used widely for mitral valve area (MVA) measurement. In this study, we prepared a new nomogram and tested its use in MVA assessment. MATERIAL AND METHODS: The study included 23 patients ...
Antonini-Canterin F - - 2008
OBJECTIVE: Left atrial (LA) size is an important predictor of outcome after mitral valve replacement in patients with symptomatic chronic mitral regurgitation (MR). Data on LA remodelling after mitral valve repair (MVr) for chronic non-ischaemic MR are scarce. The aim of this study was to assess changes in LA size ...
Schwarzwald Colin C - - 2007
OBJECTIVE: To assess the feasibility, describe the techniques, and determine the reliability of transthoracic echocardiography for characterization of left atrial (LA) size and LA mechanical function in horses. ANIMALS: 6 healthy adult horses. PROCEDURES: Repeated echocardiographic examinations were performed independently by 2 observers in standing, unsedated horses by use of ...
Nakahara Kuniaki - - 2007
Codman-Hakim programmable valves allow neurosurgeons to adjust the opening pressure to the patient's particular clinical needs. However, the pressure control cam is extremely small, so identification of the pressure indicator and its operation is somewhat difficult when initially setting the opening pressure before implantation. We employed a commercial loupe on ...
Votta Emiliano - - 2007
BACKGROUND: Functional mitral regurgitation (FMR) is the inability of mitral leaflets to coapt due to a combination of functional and geometrical factors. Valve competence is commonly restored by undersized annuloplasty, reducing the native annulus anteroposterior dimension. In case of severe FMR, this solution may be inadequate. The use of rings ...
Bergström Maria - - 2007
BACKGROUND: High intraabdominal pressures during laparoscopy (greater than 15 mm Hg) are dangerous. Pressures developed during translumenal endosurgery when using flexible endoscopes without feed-back regulation are unknown. OBJECTIVE: To measure and control intraabdominal pressures during transgastric endosurgery. DESIGN: In a blinded study, intraabdominal pressures during unregulated transgastric cholecystectomy and tubal ...
Zhang Pei - - 2007
BACKGROUND AND AIM OF THE STUDY: Mechanical heart valve (MHV) cavitation has been widely investigated by negative pressure transient (NPT) measurements. Whilst NPT is believed to be the cause of cavitation as the valve occluder approaches its fully closed position, some valves are also more prone to cavitation initiation. The ...
Shimura Kiyohito - - 2007
A miniature valve that operates between a chip port and a tube fitting was developed. The valve functions by means of a rotor, 3 mm in diameter and 1.5 mm in height, made of Teflon, with a 0.2-mm diameter hole at its center that is co-axial with the tube fitting. ...
Fricker Zachary P - - 2007
A unique, air-based system has been developed and implemented for rapid and accurate determination of pressure drop versus flow rate characteristics of generic catheter lumens; dimensionless scaling parameters can be effectively used to express these characteristics in units of blood flow used in the clinical setting. Theoretical models are compared ...
Blauwet Lori A - - 2007
Few reports have been published on the normal Doppler-derived echocardiographic data for CarboMedics (CarboMedics Inc., Austin, TX) prosthesis function in the mitral position. The purpose of this study was to provide a comprehensive Doppler echocardiographic assessment of normal CarboMedics mitral prosthesis function in a large number of patients. All of ...
Wainwright Peter C - - 2007
Successful prey capture by aquatic suction feeders depends on the ability of the predator to generate a flow of water external to the mouth that overcomes any movements and forces that the prey uses to resist the suction flow. Elucidating the nature and magnitude of these forces is a key ...
Lobo Luis - - 2008
Of 100 Estrela Mountain dogs, 74 were examined to obtain echocardiographic reference values for the breed. The influence of bodyweight, age and sex on different echocardiographic parameters was studied using either analysis of variance or regression analysis. Statistically significant differences were found between sex and heart rate as well as ...
Pan Tingrui - - 2007
In this paper, we present two remotely adjustable check-valves with an electrochemical release mechanism for implantable biomedical microsystems. These valves allow one to vary the opening pressure set-point and flow resistance over a period of time. The first design consists of a micromachined check-valve array using a SU-8 polymer structural ...
Fleming Richard M - - 2007
The use of previous anorectic medications and the combined use of the anorectic medications fenfluramine and phentermine (Fen-Phen) have been associated with varying degrees of valvular regurgitation and pulmonary hypertension. More recent reports have suggested a lower incidence of both than was previously reported. Comparisons of patients with similar body ...
Valsecchi Sergio - - 2007
OBJECTIVE: The Modelflow method computes cardiac output (CO) from arterial pressure (CO-MFao) by simulating a non-linear three-element Windkessel model of aortic input impedance. We present a novel technique to apply the Modelflow method to the left ventricular pressure (Plv) signal, to obtain an estimation of CO (CO-MFlv). METHODS: We extended ...
Lenarczyk Radoslaw - - 2007
We present a case of a 10-year-old boy with hypertrophic cardiomyopathy, intraventricular pressure gradient of 104 mmHg, and indications for prophylactic ICD implantation. Based on intraoperative pressure measurements, the child was implanted with biventricular ICD. During 2.5 months of observation, the patient's functional status improved significantly, as shown by subjective ...
Razzolini Renato R Department of Heart, Lung and Vessels, University of Padova, Padova, Italy. - - 2007
Wide discrepancies are often observed between catheter- and Doppler-derived gradients and valve areas. The study aim was to verify if these measurements could be attenuated in a clinical setting by taking into account pressure recovery. Between 1st January 2000 and 31st March 2005, a total of 259 patients with an ...
Vitarelli Antonio - - 2007
Several studies have reported that patients (pts) with severe aortic stenosis and similar pressure gradients or even similar aortic valve areas may have quite different symptomatic status and clinical outcomes suggesting that other factors might have a significant impact on the pathophysiology of this disease. Our purpose was to assess ...
Flanagan Thomas C - - 2007
Our group has previously demonstrated the synthesis of a completely autologous fibrin-based heart valve structure using the principles of tissue engineering. The present approach aims to guide more mature tissue development in fibrin-based valves based on in vitro conditioning in a custom-designed bioreactor system. Moulded fibrin-based tissue-engineered heart valves seeded ...
Rambod Edmond - - 2007
This study is aimed at refining our understanding of the role of vortex formation at mitral mechanical heart valve (MHV) closure and its association with the high intensity transient signals (HITS) seen in echocardiographic studies with MHV recipients. Previously reported numerical results described a twofold process leading to formation of ...
Tulga Ulus A - - 2007
AIM: The aim of this study was to investigate the differences in cardiac response to stress according to the size of the prosthetic valve in patients who underwent aortic valve replacement (AVR) and to evaluate the relationship between the size of the prosthetic valve and cardiac recovery-remodeling after the operation. ...
Kanno Nobuyuki - - 2007
Pimobendan has a dual mechanism of action: it increases myocardial contractility by increasing calcium sensitization to troponin C and it promotes vasodilation by inhibiting PDEIII. This study examined the effects of pimobendan on cardiac function, hemodynamics, and neurohormonal factors in dogs with mild mitral regurgitation (MR). The dogs were given ...
Saida Yuuto - - 2007
A two-month-old male long coated Chihuahua, which had symptoms including anorexia and decreased growth, was diagnosed with pulmonic valvular stenosis. Echocardiography showed the severe progression of pulmonary arterial velocity (6.29 m/s, Pressure gradient (PG); 158 mmHg). Transventricular pulmonic dilation valvuloplasty (Brock) was conducted, and stenosed valve was dilated by the ...
Navia Jose L - - 2007
OBJECTIVES: We have developed a stentless pericardial mitral valve prosthesis in 2 configurations; the purposes of this acute study in sheep were to assess (1) valve design and implant technique; (2) valve performance; and (3) acute effects on postimplant left ventricular function. METHODS: A stentless bovine pericardial bileaflet valve was ...
Neue Uwe D - - 2007
We have examined the influence of the longitudinal temperature and pressure gradients in columns operated under very high pressures on the coefficients of the van Deemter equation under the idealized condition of complete radial uniformity. These gradients change the diffusion coefficients over the length of the column, and the equation ...
Bozhenkov S A - - 2007
The article presents a detailed investigation of the fast disruption mitigation valve developed at FZJ Juelich. The essence of this study is the novel direct observation of the piston motion by means of a fast framing camera. The piston stroke and the injection duration are shown to strongly depend on ...
Vilela Marcelo L - - 2007
OBJECTIVE: We developed an experimental ex-vivo model to define factors that may influence continence of catheterizable channels by urinary and colonic stomas based on the principle of imbrication of the outlet tube. MATERIALS AND METHODS: From 20 pigs, colon specimens with 25 cm length were obtained and a transverse flap ...
Alpard Scott K - - 2007
INTRODUCTION: Our group has developed a paracorporeal artificial lung (PAL) attached in a pulmonary artery (PA) to PA in series configuration to address profound respiratory failure and serve as a bridge to transplant and/or recovery. We recently designed, developed and converted our passive pre-PAL compliance chamber to an active, synchronized, ...
Garcia Lawrence A - - 2007
BACKGROUND: Catheter-derived pressure gradient (CPG) measurements across vascular lesions are used to determine the hemodynamic significance of a stenosis prior to peripheral vascular intervention. We tested the hypothesis that CPGs overestimate the true translesion gradient during hemodynamic interrogation. METHODS: We evaluated 20 lesions (iliac, subclavian, or renal) in 16 patients ...
Yap Sing-Chien - - 2007
OBJECTIVE: We aimed to compare velocity-encoded cine cardiac magnetic resonance (CMR) with an established echocardiographic method for noninvasive measurement of aortic valve area (AVA) using the continuity equation. METHODS AND RESULTS: Twenty consecutive young adults with stenotic bicuspid aortic valves were examined with CMR and transthoracic echocardiography (TTE). CMR AVA ...
Park Seoung Woo - - 2007
Recently, valve upgrade and/or endoscopic third ventriculostomy, which have the merit of no additional shunting, were introduced for the treatment of slit ventricle syndrome, because lumboperitoneal shunting entails various complications including development of Chiari malformation, shunt malfunction, and infection. However, the safety of valve upgrading is not confirmed, especially in ...
O'Sullivan M Lynne - - 2007
BACKGROUND: Assessment of diastolic function in patients with dilated cardiomyopathy (DCM) has the potential to add valuable information regarding hemodynamics, disease severity, and prognosis. The purpose of this study was to determine transmitral flow (TMF), isovolumic relaxation time (IVRT), pulmonary venous flow (PVF), flow propagation velocity (Vp), and mitral annular ...
Changrue Viboon - - 2007
A laboratory scale microwave vacuum dryer with the ability to record temporal variation of mass and temperature of a drying product was designed and built. The initial study was set up to investigate the effect of the position of a vacuum pressure control valve at two vacuum pressure levels, 6.5 ...
Zannoli Romano - - 2007
Stanford type A aortic dissection often rapidly leads to death from aortic rupture. We considered the possibility of introducing a passive counterpulsating damper into the dissected aorta in order to limit the physical stress associated with ventricular ejection and increase the diastolic aorto-ventricular pressure gradient. We conceived a damping device ...
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