Search Results
Results 551 - 600 of 1842
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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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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. ...
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 ...
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 ...
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, ...
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 ...
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 ...
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 ...
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 ...
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 ...
Kartalov Emil P - - 2007
We report on an electrical microfluidic pressure gauge. A polydimethylsiloxane microvalve closes at a characteristic applied pressure determined by the material's properties and the valve's dimensions. Hence, when the same pressure is applied to all valves of a heterogeneous valve array, some valves close while others remain open. The state ...
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 ...
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 ...
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 ...
Afreen F - - 2007
Emergent aquatic macrophytes growing in waterlogged anaerobic sediments overlain by deep water require particularly efficient ventilating systems. In Phragmites australis (Cav.) Trin. ex Steud, pressurized gas flows, generated by humidity-induced diffusion of air into leaf sheaths, enhance oxygen transport to below-ground parts and aid in the removal of respiratory CO2 ...
Yokoyama Y - - 2006
The aim of this study was to validate the flow characteristics of the novel Helmholtz-Institute Aachen Bileaflet (HIA-BL) heart valve prosthesis. The curved leaflets of the HIA-BL valve form a Venturi passage between the leaflets at peak systole. By narrowing the cross section the flow accelerates and the static pressure ...
Sakamoto Hiroaki - - 2006
The application of repair techniques to treat mitral valve incompetence has increased progressively during the past 20 years. Unfortunately, recent reports have demonstrated the longevity of these repairs to be less than previously believed. Most repair failures are stress related. Computational models to optimize valve repair are in development, but ...
Geselschap Jim H - - 2006
PURPOSE: To report the results of in vitro hydrostatic bench testing of a new vein-stent combination to correct deep venous incompetence. METHODS: Twelve valves were constructed from a modified Palmaz stent encased in a segment of great saphenous vein harvested from patients during routine varicose vein surgery. An in vitro ...
Little Stephen H - - 2007
To investigate the impact of blood pressure (BP) on the Doppler echocardiographic (Doppler-echo) evaluation of severity of aortic stenosis (AS). Handgrip exercise or phenylephrine infusion was used to increase BP in 22 patients with AS. Indices of AS severity (mean pressure gradient (DeltaP(mean)), aortic valve area (AVA), valve resistance, percentage ...
Topaloglu Serkan - - 2007
OBJECTIVE: To determine whether plasma level of soluble P-selectin (sP-selectin) increases in rheumatic mitral stenosis (MS) patients with sinus rhythm, who have scheduled for percutaneous mitral balloon valvuloplasty (PMBV), and to examine the effect of PMBV on sP-selectin level. METHODS: Twenty-six patients with MS and sinus rhythm (study group, 20 ...
Su Ho-Ming - - 2007
Diastolic mitral annular motion may terminate earlier in patients with higher left ventricular end-diastolic pressure (LVEDP). It was therefore hypothesized that the time interval measured from the end of the diastolic mitral annular velocity pattern to the onset of QRS (the AQ interval) would be a useful parameter in predicting ...
McGirt Matthew J - - 2007
INTRODUCTION: The use of programmable shunt valves has increased dramatically in the practice of pediatric hydrocephalus. Despite theoretical advantages, it remains unclear if the use of programmable vs set-pressure valves affects shunt outcome. MATERIALS AND METHODS: The clinical and radiological records of all pediatric patients undergoing ventriculoperitoneal (VP), ventriculopleural (VPl), ...
Sato Kimitoshi - - 2006
Although the Codman Hakim programmable valve (CHPV) system is popular, several problems arising from its design have been described. The authors report an additional cause of shunt failure associated with the use of the CHPV system. A 7-year-old girl who had previously undergone placement of a ventriculoperitoneal shunt with the ...
Kato Takayoshi - - 2006
Mediastinitis following ascending aortic replacement is intractable and potentially fatal, and the feature is characterized as having both high mortality and morbidity when its causation pathology is methicillin-resistant Staphylococcus aureus (MRSA). Possible treatments for the condition, which include debridement, irrigation, and healthy tissue transposition, often result in failure. We report ...
Linde Annika - - 2006
This study was conducted to estimate the incidence of aortic stenosis (AS) in a group of Boxers evaluated by auscultation, ECG, blood pressure measurement and Doppler-echocardiography. The Boxer is a breed at significantly increased risk of AS. The prevalence of murmurs and Doppler-echocardiographic findings consistent with AS in this breed ...
Goetz Wolfgang A - - 2006
Systolic descent of the atrioventricular plane toward the relatively stationary left ventricular apex is well described. As the atrioventricular plane includes two separate valvular units, systolic atrioventricular plane displacement should not be homogenous. In 6 sheep, sonomicrometric crystals were implanted at the base of the right coronary sinus, anterolateral and ...
Jimenez Jorge H - - 2006
BACKGROUND: Although edge-to-edge repair is an established adjunctive procedure, there is still debate on its long-term durability and efficacy. METHODS: Fifteen porcine mitral valves were studied in a physiologic left heart simulator with a variable size annulus (dilated = 8.22 cm2, normal = 6.86 cm2, contracted = 5.5 cm2). Mitral ...
Mihalatos Dennis G - - 2006
OBJECTIVES: We defined the effects of the operative (OP) state and phenylephrine challenge on the assessment of mitral regurgitation (MR) severity. METHODS: In all, 57 patients underwent transesophageal echocardiographic assessment of MR severity pre-OP (PREOP) and intra-OP. MR severity was assessed PREOP under conscious sedation and intra-OP with general anesthesia, ...
Asada-Kamiguchi Junko - - 2006
BACKGROUND: Left ventricular aneurysm (LVA) may affect diastolic intraventricular blood flow. Color M-mode (CMM) Doppler flow propagation patterns are abnormal in the presence of apical aneurysms. The aim of this study was to validate the accuracy of CMM echocardiography for assessing the existence and size of LVA and to determine ...
Kadem Lyes - - 2006
BACKGROUND AND AIM OF THE STUDY: In patients with aortic stenosis (AS), it has been reported that the transvalvular pressure gradients (APs) may be reduced or even abolished in the presence of concomitant arterial hypertension, but the mechanisms underlying this phenomenon remain unclear. The study aim was to: (i) examine ...
Tou Sandra P - - 2006
BACKGROUND: Systemic hypertension is likely underdiagnosed in veterinary medicine because systemic blood pressure is rarely measured. Systemic blood pressure can theoretically be estimated by echocardiography. According to the modified Bernoulli equation (PG = 4v(2)), mitral regurgitation (MR) velocity should approximate systolic left ventricular pressure (sLVP), and therefore systolic systemic blood ...
Saito Shunei - - 2006
OBJECTIVE: We have recently reported our isolated and working swine heart model that examines the valve motion precisely by a high-speed digital video camera system. Using this modality, the present study aimed (1) to delineate the motion of the mitral leaflets, chords and annulus throughout the cardiac cycle, and (2) ...
Webb John G - - 2006
OBJECTIVES: We describe the technique of, and our experience with, rapid ventricular burst pacing to facilitate transcatheter heart valve implantation. BACKGROUND: Endovascular therapeutic procedures frequently require the precise placement of implantable devices. The precision of transcatheter device deployment may be hampered by cardiac motion or the effects of intravascular flow. ...
Utsuki Satoshi - - 2006
A 7-year-old girl presented in semicomatose condition. She had received a ventriculoperitoneal shunt using a Codman-Hakim programmable valve. Head computed tomography demonstrated hydrocephalus and head radiography showed that the pressure setting of the shunt valve had changed to 60 mmH(2)O from 40 mmH(2)O. The pressure setting was returned to 40 ...
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