Search Results
Results 401 - 450 of 1833
< 4 5 6 7 8 9 10 11 12 13 14 >
Gordeuk Victor R - - 2011
While in adults with sickle cell disease an elevation of tricuspid regurgitation velocity is associated with increased mortality, the importance of this finding in children has not been established. The role of intravascular hemolysis in the development of this complication is controversial. We conducted a prospective, longitudinal, multi-center study of ...
Bech-Hanssen Odd - - 2011
aortic valve replacement (AVR) in patients with aortic stenosis reduces the left ventricular (LV) pressure and the LV mass. However, residual LV hypertrophy at follow-up is a common finding with negative prognostic impact. In the present study, we investigate the contribution of the prosthesis (size, type, and gradients) and the ...
Min Sun-Yang - - 2010
We sought to demonstrate geometric changes in the tricuspid valve (TV) apparatus after tricuspid annuloplasty (TAP) and to identify predictors of residual tricuspid regurgitation (TR) in patients with functional TR using real-time three-dimensional echocardiography (RT3DE). RT3DE and two-dimensional colour Doppler echocardiography were performed in 59 consecutive patients before and 4.7 ...
Agarwal Manju - - 2010
A model for interactions between forestry biomass, wildlife population and industrialization pressure is proposed and analysed. Here, the functional responses are assumed to be ratio-dependent type. The effect of forestry biomass depletion in a forested habitat caused by industrialization pressure on the survival of the forestry biomass dependent wildlife species ...
Yamazawa Hirokuni - - 2010
The Doppler echocardiography derived peak instantaneous systolic pressure gradient (peak instantaneous Doppler PG), the mean PG (mean Doppler PG) and the aortic valvular area are the accepted standard for determining the prognosis and optimal timing of intervention because of good agreement between Doppler-derived and catheter-measured PGs in adult patients with ...
Tuzun Egemen - - 2011
As the use of left ventricular assist devices (LVADs) to treat end-stage heart failure has become more widespread, leaflet fusion-with resul-tant aortic regurgitation-has been observed more frequently. To quantitatively assess the effects of nonpulsatile flow on aortic valve function, we tested a continuous-flow LVAD in a mock circulatory system (MCS) ...
Sakamoto Yoshimasa - - 2010
BACKGROUND: The objective of this study was to reassess the validity of defining patient-prosthesis mismatch (PPM) in the aortic position on the basis of an indexed effective orifice area (iEOA) less than 0.85 cm(2)/m(2). METHODS: From June 1996 to March 2008, 342 patients underwent aortic valve replacement with a Carpentier-Edwards ...
Poglajen Gregor - - 2010
Functional mitral regurgitation (FMR) in patients with ischemic or nonischemic cardiomyopathy has been related to several overlapping factors. In vivo, these factors are very difficult to study independently of dynamic processes, such as ventricular wall motion or annular contraction. We developed an ex vivo left ventricular model that allows independent ...
Bahlmann Edda - - 2010
OBJECTIVES: The aim of this analysis was to assess the diagnostic importance of pressure recovery in evaluation of aortic stenosis (AS) severity. BACKGROUND: Although pressure recovery has previously been demonstrated to be particularly important in assessment of AS severity in groups of patients with moderate AS or small aortic roots, ...
Hirabayashi Go - - 2010
With spontaneous ventilation, sufficient exhaust resistance at the adjustable pressure-limiting (APL) valve when fully opened ensures that the reservoir bag fills and adequately supplies gas to patients. A lack of exhaust resistance with the APL valve fully open caused inadequate gas supply to patients with four types of anesthesia machines: ...
Perez-Diaz Jose-Luis - - 2010
A pure mechanical anisotropic model of a tree trunk has been developed based on the 3D finite element method. It simulates the microscopic structure of vessels in the trunk of a European beech (Fagus sylvatica) in order to study and analyse its mechanical behaviour with different configurations of pressures in ...
Roberge Raymond J - - 2010
OBJECTIVE: To assess the physiological impact of the N95 filtering facepiece respirator (FFR) on healthcare workers. METHODS: Ten healthcare workers each conducted multiple 1-hour treadmill walking sessions, at 1.7 miles/h, and at 2.5 miles/h, while wearing FFR with exhalation valve, FFR without exhalation valve, and without FFR (control session). We ...
Shkolnikov Viktor V Department of Mechanical Engineering, Stanford University, Stanford, CA 94305, - - 2010
We present a design for a miniature self-priming peristaltic pump actuated with a single linear actuator, and which can be manufactured using conventional materials and methods. The pump is tolerant of bubbles and particles and can pump liquids, foams, and gases. We explore designs actuated by a motor (in depth) ...
Matsumoto Toshifumi - - 2010
When a patient with a ventriculoperitoneal shunt (VPS) undergoes laparoscopic surgery, there is the concern about possible problems with the shunt due to increased intra-abdominal pressure. We conducted a simplified reflux experiment on VPS valves to demonstrate safety. Each of five different VPS valves was connected via tubes to a ...
Li Kewei - - 2010
Percutaneous aortic valve (PAV) replacement is currently being investigated as an endovascular alternative to conventional open-chest valve surgery for patients with severe aortic stenosis. The results of multi-center clinical trials of PAV devices have been encouraging. However, there are serious adverse events associated with this procedure. Furthermore, long-term durability and ...
Schleicher Martina - - 2010
Long-term function of biological heart valve prostheses (BHV) is limited by structural deterioration leading to failure with associated arterial hypertension. The objective of this work was development of an easy to handle real-time pulse reactor for evaluation of biological and tissue engineered heart valves under different pressures and long-term conditions. ...
Dall'osto David R - - 2010
Pressure signals measured by two four-element vertical line arrays, centered at depths 25 and 50 m, during an experiment off the New Jersey coast in Summer 2006 (SW06, depth 80 m) are combined to determine the pressure gradient of the received signal. The pressure gradient is converted to an estimate ...
Marston Timothy M - - 2010
Grazing illumination of a target close to a flat interface as well as evanescent wave illumination of a buried target can produce significant vertical acoustic pressure gradients at a target. A prior experiment [Espana et al., J. Acoust. Soc. Am. 126, 2187 (2009)] demonstrated the selective coupling to a mode ...
Dénes Mónika M Gottsegen György Hungarian Institute of Cardiology, H-1096 Budapest, Hungary. - - 2010
Both systolic and diastolic tissue Doppler (TD) velocities have an important diagnostic and prognostic role in cardiology. We aimed to compare TD velocities between two different echocardiography systems. Thirty-one consecutive patients (mean age: 65.2 +/- 17.5 years; 12 males) were enrolled. Systolic (Sa), early (Ea), and late (Aa) diastolic velocities ...
Ishikawa Takamichi - - 2010
This report presents the case of an 8-year-old male with biventricular hypertrophic obstructive cardiomyopathy who achieved a successful reduction of the pressure gradients by treatment with cibenzoline. Ultrasound echocardiography showed marked intraventricular septal hypertrophy and left midventricular and right ventricular outflow obstructions. A cardiac catheterization revealed left midventricular and right ...
Aihara Yasuo - - 2010
OBJECTIVE: Programmable shunt valve systems have improved the management of patients with hydrocephalus. However, associated problems such as over-drainage and slit-like ventricles, even in patients with anti-siphon devices installed, still remain unresolved. METHODS: We conceived a novel tandem shunt valve system to overcome the problems with existing shunt valve systems. ...
Verdonck Pascal - - 2010
A fluid is a medium which deforms, or undergoes motion, continuously under the action of a shearing stress and includes liquids and gases. Applying biofluid mechanics to the cardiovascular system requires knowledge of anatomy and geometry, pressure data and blood flow, volume and velocity measurements. A good example is the ...
Kreutzer Guillermo O - - 2010
The first atriopulmonary anastomosis (APA) with neither a valve in the inferior vena cava (IVC) nor an Glenn shunt was performed in 1971. A fenestration was intentionally left in the atrial septum. In a second patient, the APA incorporated the patient's own pulmonary valve, which had been removed from the ...
Hjerrild Britta E - - 2010
BACKGROUND: To investigate aortic dimensions in women with Turner syndrome (TS) in relation to aortic valve morphology, blood pressure, karyotype, and clinical characteristics. METHODS AND RESULTS: A cross sectional study of 102 women with TS (mean age 37.7; 18-62 years) examined by cardiovascular magnetic resonance (CMR- successful in 95), echocardiography, ...
SzymaƄski Piotr P Department of Adult Congenital Heart Diseases, Institute of Cardiology, Warszawa, Poland. - - 2010
The development of significant tricuspid regurgitation (TR) is associated with an unfavorable clinical outcome in patients with systemic right ventricles. Increased knowledge about the factors contributing to its presence would help prevent its progression. This was a retrospective analysis of the factors predictive of significant TR in 60 patients with ...
Khodarahmi Iman I Medical Imaging Lab., Department of Electrical and Computer Engineering, University of Louisville, KY 40292, USA. - - 2010
Pressure gradient across a Gaussian-shaped 87% area stenosis phantom was estimated by solving the pressure Poisson equation (PPE) for a steady flow mimicking the blood flow through the human iliac artery. The velocity field needed to solve the pressure equation was obtained using particle image velocimetry (PIV). A steady flow ...
Yong Gerald - - 2009
BACKGROUND: During hemodynamic assessment prior to antegrade balloon aortic valvuloplasty (BAV), unanticipated transmitral valve pressure gradients (MVG) were noted frequently. AIM: To determine the prevalence and significance of a significant MVG in patients with aortic stenosis and no previously diagnosed mitral valve stenosis. METHOD: Retrospective chart review of patients with ...
Yap Choon Hwai - - 2010
Calcific aortic valve (AV) disease has a high prevalence in the United States, and hypertension is correlated to early onset of the disease. The cause of the disease is poorly understood, although biological and remodeling responses to mechanical forces, such as membrane tension, have been hypothesized to play a role. ...
Sekar Priya - - 2009
Aortic arch recoarctation is responsible for significant morbidity and mortality after the Norwood Stage I procedure. Cuff blood pressure (BP) gradients and echocardiographic Doppler gradients are routinely used as noninvasive screening tests for early detection, but accuracy has not been systematically tested. We sought to evaluate the ability of cuff ...
Attaran R R - - 2009
BACKGROUND: Pulmonary arterial pressure measurement is an integral part of the pre-heart transplant evaluation. In the clinical arena, the correlation and agreement between pulmonary artery systolic pressure (PASP) measured by Doppler echocardiography versus catheterization in pre-heart transplant patients has not been studied. METHODS: Data on all patients evaluated for heart ...
Anavekar Nandan S - - 2009
The 2D echocardiographic examination of the heart provides insight into structure and function, providing a precise anatomical display of the cardiovascular anatomy with high temporal resolution. Prior to advances in 2D imaging, Doppler echocardiography had been the mainstay of cardiovascular noninvasive assessment. Doppler echocardiography, remains an integral part of the ...
Kim Jitae - - 2009
An automated, pre-programmed, multiplexed hydraulic valve actuator is described. The valve is membrane-based and normally open. In contrast to the membrane-based pneumatic valve, the hydraulic valve uses hydraulic liquid to exert the control pressure. The line pressure is controlled with a roller moving over a prefabricated topology. Multiple rollers, each ...
Chen Chien-Fu - - 2009
A facile method enabling the integration of elastomeric valves into rigid thermoplastic microfluidic chips is described. The valves employ discrete plugs of elastomeric polydimethylsiloxane (PDMS) integrated into the thermoplastic substrate and actuated using a threaded stainless steel needle. The fabrication process takes advantage of poly(ethylene glycol) (PEG) as a sacrificial ...
Jaschke Paul R - - 2009
A procedure for modification of the valve stem of a 40 K French pressure cell is described. The modification should be done by a machinist and requires a metalworking lathe. After modification of the valve stem, a torlon 4203 plastic ball is used between the valve stem and valve seat ...
Lin Tsung-Hsien - - 2009
OBJECTIVES: We previously found the association between mitral chordae tendinae ruptures (MCTR) and hypertension. Tissue inhibitor of metalloproteinase-2 (TIMP2), which expresses differently under pressure loads, could trigger a signal cascade instigating cardiac fibrosis, possibly predisposing to MCTR. We aimed to elucidate the relationship between the TIMP2 and hypertension and the ...
Hamlington Peter E - - 2009
A new fundamentally based formulation of nonlocal effects in the rapid pressure-strain correlation in turbulent flows has been obtained. The resulting explicit form for the rapid pressure-strain correlation accounts for nonlocal effects produced by spatial variations in the mean-flow velocity gradients and is derived through Taylor expansion of the mean ...
Parameswaran Anoop C - - 2009
Studies have shown very good correlation between Doppler-derived gradients and gradients obtained by cardiac catheterization (cath) in aortic stenosis (AS). However, the phenomenon of pressure recovery may lead to significant overestimation of aortic valve (AV) gradients by Doppler echocardiography (echo). We hypothesized that echo-derived gradients will be higher in mild-moderate ...
Kim Kyoung-Hun - - 2009
There is no definite adjustment protocol for patients shunted with programmable valves. Therefore, we attempted to find an appropriate method to adjust the valve, initial valve-opening pressure, adjustment scale, adjustment time interval, and final valve-opening pressure of a programmable valve. Seventy patients with hydrocephalus of various etiologies were shunted with ...
Solis Jorge J Division of Cardiology, Massachusetts General Hospital, Boston, MA 02114, - - 2009
Cardiac resynchronization therapy (CRT) has been shown to reduce functional mitral regurgitation (MR). It has been proposed that the mechanism of MR reduction relates to geometric change or, alternatively, changes in left ventricular (LV) contractile function. Normal mitral valve (MV) function relies on a balance between tethering and closing forces ...
Saraiva Roberto M - - 2009
BACKGROUND: Left atrial (LA) volume is a prognostic index in chronic mitral regurgitation (MR). However, little is known about LA function in this setting. We hypothesized that LA dysfunction is related to pulmonary hypertension in chronic MR. METHODS: Seventy-one patients with organic chronic MR who underwent real-time 3-dimensional transthoracic echocardiography ...
Fritz Brad G - - 2010
Vertical hydraulic gradient is commonly measured in rivers, lakes, and streams for studies of groundwater-surface water interaction. While a number of methods with subtle differences have been applied, these methods can generally be separated into two categories; measuring surface water elevation and pressure in the subsurface separately or making direct ...
Ben-Dor Itsik - - 2009
The aim of this study was to assess the change in coronary flow in patients who underwent percutaneous aortic valve replacement (PAVR) for severe aortic stenosis. The left main coronary artery was visualized using transesophageal echocardiography in 17 patients who underwent PAVR. The peak systolic and diastolic velocities of coronary ...
Kim H J - - 2009
Aortic flow and pressure result from the interactions between the heart and arterial system. In this work, we considered these interactions by utilizing a lumped parameter heart model as an inflow boundary condition for three-dimensional finite element simulations of aortic blood flow and vessel wall dynamics. The ventricular pressure-volume behavior ...
Lee Hwansung - - 2009
Our group is currently developing a pneumatic ventricular assist device (PVAD), and in previous studies, we reported the mechanical heart valve (MHV) cavitation intensity at the inlet valve in the PVAD only. In this study, we investigated the effect of the running conditions on the cavitation intensity both for the ...
Seker Erkin - - 2009
An analytical solution is presented for the nonlinear pressure-flow relationship of deformable passive valves, which are formed by bonding a deformable film over etched channels separated by a weir. A fluidic pathway connecting the channels is opened when the upstream pressure creates a tunnel along a predefined narrow strip where ...
Krishnamurthy Gaurav G Department of Cardiothoracic Surgery, Stanford University School of Medicine, Stanford, CA, - - 2009
Excised anterior mitral leaflets exhibit anisotropic, non-linear material behavior with pre-transitional stiffness ranging from 0.06 to 0.09 N/mm(2) and post-transitional stiffness from 2 to 9 N/mm(2). We used inverse finite element (FE) analysis to test, for the first time, whether the anterior mitral leaflet (AML), in vivo, exhibits similar non-linear ...
Ishikawa T - - 2009
BACKGROUND: Mitral valve regurgitation (MR) causes increased left atrial pressure (LAP) and is associated with occurrence of clinical signs. It will be useful to understand diurnal variations of LAP for the management of MR. HYPOTHESIS: Circulatory parameters and diurnal rhythm are linked to clinical signs in cardiac diseases. LAP also ...
Chiavegato David - - 2009
Pulmonary hypertension has been associated with mitral insufficiency caused by chronic degenerative valve disease in dogs. Our aim was to search for associations between left atrial to aortic root ratio, end-systolic and end-diastolic volume indices, and changes in the right ventricular to right atrial pressure gradient as estimated by the ...
Lo Ronalee - - 2009
An implantable manually-actuated drug delivery device, consisting of a refillable drug reservoir, flexible cannula, check valve, and suture tabs, was investigated as a new approach for delivering pharmaceuticals to treat chronic ocular diseases. Devices are fabricated by molding and bonding three structured layers of polydimethylsiloxane. A 30 gauge non-coring needle ...
Glover G W - - 2009
BACKGROUND: There are few data describing the performance of the Whisperflow continuous positive airway pressure (CPAP) generator. METHODS: (i) (a) A static test of 11 Whisperflow devices examining maximum flow generation with no load and with 2.5, 5, 7.5, 10, 15, and 20 cm H2O valve loading, at varying Fi(O2). ...
< 4 5 6 7 8 9 10 11 12 13 14 >