Sample records for valves fail closed

  1. Fail-safe bidirectional valve driver

    NASA Technical Reports Server (NTRS)

    Fujimoto, H.

    1974-01-01

    Cross-coupled diodes are added to commonly used bidirectional valve driver circuit to protect circuit and power supply. Circuit may be used in systems requiring fail-safe bidirectional valve operation, particularly in chemical- and petroleum-processing control systems and computer-controlled hydraulic or pneumatic systems.

  2. Fluid check valve has fail-safe feature

    NASA Technical Reports Server (NTRS)

    Gaul, L. C.

    1965-01-01

    Check valve ensures unidirectional fluid flow and, in case of failure, vents the downstream fluid to the atmosphere and gives a positive indication of malfunction. This dual valve consists of a master check valve and a fail-safe valve.

  3. Lightweight Valve Closes Duct Quickly

    NASA Technical Reports Server (NTRS)

    Fournier, Walter L.; Burgy, N. Frank

    1991-01-01

    Expanding balloon serves as lightweight emergency valve to close wide duct. Uninflated balloon stored in housing of duct. Pad resting on burst diaphragm protects balloon from hot gases in duct. Once control system triggers valve, balloon inflates rapidly to block duct. Weighs much less than does conventional butterfly, hot-gas, or poppet valve capable of closing duct of equal diameter.

  4. Transcatheter Mitral Valve Replacement for Native and Failed Bioprosthetic Mitral Valves

    PubMed Central

    Sarkar, Kunal; Reardon, Michael J.; Little, Stephen H.; Barker, Colin M.; Kleiman, Neal S.

    2017-01-01

    Transcatheter mitral valve replacement (TMVR) is a novel approach for treatment of severe mitral regurgitation. A number of TMVR devices are currently undergoing feasibility trials using both transseptal and transapical routes for device delivery. Overall experience worldwide is limited to fewer than 200 cases. At present, the 30-day mortality exceeds 30% and is attributable to both patient- and device-related factors. TMVR has been successfully used to treat patients with degenerative mitral stenosis (DMS) as well as failed mitral bioprosthesis and mitral repair using transcatheter mitral valve-in-valve (TMViV)/valve-in-ring (ViR) repair. These patients are currently treated with devices designed for transcatheter aortic valve replacement. Multicenter registries have been initiated to collect outcomes data on patients currently undergoing TMViV/ViR and TMVR for DMS and have confirmed the feasibility of TMVR in these patients. However, the high periprocedural and 30-day event rates underscore the need for further improvements in device design and multicenter randomized studies to delineate the role of these technologies in patients with mitral valve disease. PMID:29743999

  5. 46 CFR 78.47-38 - Valves and closing appliances.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 3 2010-10-01 2010-10-01 false Valves and closing appliances. 78.47-38 Section 78.47-38... Fire and Emergency Equipment, Etc. § 78.47-38 Valves and closing appliances. (a) All valves and closing appliances, or other mechanisms which may be required to be operated for damage control purposes in case of...

  6. 46 CFR 78.17-5 - Valves and closing appliances.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 3 2010-10-01 2010-10-01 false Valves and closing appliances. 78.17-5 Section 78.17-5..., Drills, and Inspections § 78.17-5 Valves and closing appliances. (a) It shall be the duty of the master to see that all valves, including cross connecting valves where fitted, and other appliances such as...

  7. Fail Save Shut Off Valve for Filtering Systems Employing Candle Filters

    DOEpatents

    VanOsdol, John

    2006-01-03

    The invention relates to an apparatus that acts as a fail save shut off valve. More specifically, the invention relates to a fail save shut off valve that allows fluid flow during normal operational conditions, but prevents the flow of fluids in the event of system failure upstream that causes over-pressurization. The present invention is particularly well suited for use in conjunction with hot gas filtering systems, which utilize ceramic candle filters. Used in such a hot gas system the present invention stops the flow of hot gas and prevents any particulate laden gas from entering the clean side of the system.

  8. Fail save shut off valve for filtering systems employing candle filters

    DOEpatents

    VanOsdol, John [Fairmont, WV

    2006-01-03

    The invention relates to an apparatus that acts as a fail save shut off valve. More specifically, the invention relates to a fail save shut off valve that allows fluid flow during normal operational conditions, but prevents the flow of fluids in the event of system failure upstream that causes over-pressurization. The present invention is particularly well suited for use in conjunction with hot gas filtering systems, which utilize ceramic candle filters. Used in such a hot gas system the present invention stops the flow of hot gas and prevents any particulate laden gas from entering the clean side of the system.

  9. The closing behavior of mechanical aortic heart valve prostheses.

    PubMed

    Lu, Po-Chien; Liu, Jia-Shing; Huang, Ren-Hong; Lo, Chi-Wen; Lai, Ho-Cheng; Hwang, Ned H C

    2004-01-01

    Mechanical artificial heart valves rely on reverse flow to close their leaflets. This mechanism creates regurgitation and water hammer effects that may form cavitations, damage blood cells, and cause thromboembolism. This study analyzes closing mechanisms of monoleaflet (Medtronic Hall 27), bileaflet (Carbo-Medics 27; St. Jude Medical 27; Duromedics 29), and trileaflet valves in a circulatory mock loop, including an aortic root with three sinuses. Downstream flow field velocity was measured via digital particle image velocimetry (DPIV). A high speed camera (PIVCAM 10-30 CCD video camera) tracked leaflet movement at 1000 frames/s. All valves open in 40-50 msec, but monoleaflet and bileaflet valves close in much less time (< 35 msec) than the trileaflet valve (>75 msec). During acceleration phase of systole, the monoleaflet forms a major and minor flow, the bileaflet has three jet flows, and the trileaflet produces a single central flow like physiologic valves. In deceleration phase, the aortic sinus vortices hinder monoleaflet and bileaflet valve closure until reverse flows and high negative transvalvular pressure push the leaflets rapidly for a hard closure. Conversely, the vortices help close the trileaflet valve more softly, probably causing less damage, lessening back flow, and providing a washing effect that may prevent thrombosis formation.

  10. Redundant electronic circuit provides fail-safe control

    NASA Technical Reports Server (NTRS)

    Archer, J. W.

    1970-01-01

    Circuit using dual control amplifiers and dual position demand potentiometers powered from separate sources is used for reliable hydraulic valve controller that prevents closure of valve when control circuits fail, and maintains valve control to close tolerance for more common modes of controller failure.

  11. Non-Pyrotechnic Zero-Leak Normally Closed Valve

    NASA Technical Reports Server (NTRS)

    Gillespie, Rebecca

    2010-01-01

    This valve is designed to create a zero-leak seal in a liquid propulsion system that is a functional replacement for the normally closed pyrovalve. Unlike pyrovalves, Nitinol is actuated by simply heating the material to a certain temperature, called the transition temperature. Like a pyrovalve, before actuation, the upstream and downstream sections are separated from one another and from the external environment by closed welded seals. Also like pyrovalves, after actuation, the propellant or pressurant gas can flow without a significant pressure drop but are still separated from the external environment by a closed welded seal. During manufacture, a Nitinol bar is compressed to 93 percent of its original length and fitted tightly into the valve. During operation, the valve is heated until the Nitinol reaches the transition temperature of 95 C; the Nitinol "remembers" its previous longer shape with a very large recovery force causing it to expand and break the titanium parent metal seal to allow flow. Once open, the valve forever remains open. The first prototype valve was designed for high pressure [5,000 psi (=34.5 MPa)] and low flow, typical requirements for pressurant gas valves in liquid propulsion systems. It is possible to modify the dimensions to make low-pressure models or high-flow models, for use downstream of the propellant tanks. This design is simpler, lower risk, and less expensive than the pyrovalve. Although the valve must be in a thermally controlled state (kept below 80 C) to prevent premature actuation, the pyrovalves and electrically actuated initiators have far more taxing handling requirements.

  12. Surgical revision after percutaneous mitral valve repair by edge-to-edge device: when the strategy fails in the highest risk surgical population.

    PubMed

    Alozie, Anthony; Westphal, Bernd; Kische, Stephan; Kaminski, Alexander; Paranskaya, Liliya; Bozdag-Turan, Ilkay; Ortak, Jasmin; Schubert, Jochen; Steinhoff, Gustav; Ince, Hüseyin

    2014-07-01

    were discharged with excellent valve prosthesis function and followed up to 2 years post-surgery. The current long-term survival rate is 77%. Our series demonstrate that highest risk patients can survive mitral valve surgery after failed multiple edge-to-edge interventional mitral valve repair. As long-term results of the MitraClip therapy are pending, we recommend close meshed follow-up of patients treated with the MitraClip device, especially within the first year of the index procedure as delays in salvage management, interventional or surgical, when the index procedure fails may increase morbidity and mortality. © The Author 2013. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

  13. Genesis of the Mechanical Heart Valves' Ultrasonic Closing Clicks

    NASA Astrophysics Data System (ADS)

    Hasegawa, Jun; Kobayashi, Kenji

    A new in vitro experimental tool was developed to study the mechanism of the ultrasonic closing clicks' genesis of mechanical heart valves. Since the newly developed tester adopted compressed air flow directly instead of the blood analog fluid to drive the mechanical heart valve, it is not possibe to generate any cavitation. Closing clicks were measured with a small accelerometer at the surface of the valve holder made of silicone rubber. Ultrasonic closing clicks as well as audible closing clicks, similar to those measured clinically, could be observed using this setup. Thus, it was confirmed that the ultrasonic closing clicks can be generated without the existence of cavitation. Simultaneous measurements of the valve motion were made with a high-speed video camera, and the analysis of the video frames and clicks showed that higher frequency signal components of more than 50kHz could be generated only at the instant of the closure, which means the collision of the occluder with the housing. Eighteen miniature accelerometers with an area of one square millimeter were developed and stuck on the housing to monitor the distribution of the housing vibrations in detail, and it was found that the vibrations correspond to the ultrasonic closing clicks propagated from the valve stop: the collision point of the occluder with the housing. This fact indicated that the generation of ultrasonic closing clicks are limited to the small area of the collision. From those results, it was concluded that the major origin of the ultrasonic closing clicks' genesis should be the collision of the occluder with the housing.

  14. 46 CFR 154.708 - Cargo boil-off as fuel: Valves.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Cargo Pressure and Temperature Control § 154.708 Cargo boil-off as fuel: Valves. (a) Gas fuel lines to the gas consuming equipment must have two fail-closed automatic valves in series. A third valve, designed to fail...

  15. 46 CFR 154.708 - Cargo boil-off as fuel: Valves.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Cargo Pressure and Temperature Control § 154.708 Cargo boil-off as fuel: Valves. (a) Gas fuel lines to the gas consuming equipment must have two fail-closed automatic valves in series. A third valve, designed to fail...

  16. 46 CFR 154.708 - Cargo boil-off as fuel: Valves.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Cargo Pressure and Temperature Control § 154.708 Cargo boil-off as fuel: Valves. (a) Gas fuel lines to the gas consuming equipment must have two fail-closed automatic valves in series. A third valve, designed to fail...

  17. 46 CFR 154.708 - Cargo boil-off as fuel: Valves.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Cargo Pressure and Temperature Control § 154.708 Cargo boil-off as fuel: Valves. (a) Gas fuel lines to the gas consuming equipment must have two fail-closed automatic valves in series. A third valve, designed to fail...

  18. 46 CFR 154.708 - Cargo boil-off as fuel: Valves.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Cargo Pressure and Temperature Control § 154.708 Cargo boil-off as fuel: Valves. (a) Gas fuel lines to the gas consuming equipment must have two fail-closed automatic valves in series. A third valve, designed to fail...

  19. Transcatheter aortic valve implantation for failing surgical aortic bioprosthetic valve: from concept to clinical application and evaluation (part 2).

    PubMed

    Piazza, Nicolo; Bleiziffer, Sabine; Brockmann, Gernot; Hendrick, Ruge; Deutsch, Marcus-André; Opitz, Anke; Mazzitelli, Domenico; Tassani-Prell, Peter; Schreiber, Christian; Lange, Rüdiger

    2011-07-01

    This study sought to review the acute procedural outcomes of patients who underwent transcatheter aortic valve (TAV)-in-surgical aortic valve (SAV) implantation at the German Heart Center, Munich, and to summarize the existing literature on TAV-in-SAV implantation (n = 47). There are several case reports and small case series describing transcatheter aortic valve implantation for a failing surgical aortic valve bioprosthesis (TAV-in-SAV implantation). From January 2007 to March 2011, 20 out of 556 patients underwent a TAV-in-SAV implantation at the German Heart Center Munich. Baseline characteristics and clinical outcome data were prospectively entered into a dedicated database. The mean patient age was 75 ± 13 years, and the mean logistic European System for Cardiac Operative Risk Evaluation and Society of Thoracic Surgeons' Risk Model scores were 27 ± 13% and 7 ± 4%, respectively. Of the 20 patients, 14 had stented and 6 had stentless surgical bioprostheses. Most cases (12 of 20) were performed via the transapical route using a 23-mm Edwards Sapien prosthesis (Edwards Lifesciences, Irvine, California). Successful implantation of a TAV in a SAV with the patient leaving the catheterization laboratory alive was achieved in 18 of 20 patients. The mean transaortic valve gradient was 20.0 ± 7.5 mm Hg. None-to-trivial, mild, and mild-to-moderate paravalvular aortic regurgitation was observed in 10, 6, and 2 patients, respectively. We experienced 1 intraprocedural death following pre-implant balloon aortic valvuloplasty ("stone heart") and 2 further in-hospital deaths due to myocardial infarction. TAV-in-SAV implantation is a safe and feasible treatment for high-risk patients with failing aortic bioprosthetic valves and should be considered as part of the armamentarium in the treatment of aortic bioprosthetic valve failure. Copyright © 2011 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  20. Repeat transcatheter aortic valve implantation using a latest generation balloon-expandable device for treatment of failing transcatheter heart valves.

    PubMed

    Schaefer, Andreas; Treede, Hendrik; Seiffert, Moritz; Deuschl, Florian; Schofer, Niklas; Schneeberger, Yvonne; Blankenberg, Stefan; Reichenspurner, Hermann; Schaefer, Ulrich; Conradi, Lenard

    2016-01-15

    Paravalvular leakage (PVL) is a known complication of transcatheter aortic valve implantation (TAVI) and is associated with poor outcome. Besides balloon-post-dilatation, valve-in-valve (ViV) procedures can be taken into consideration to control this complication. Herein we present initial experience with use of the latest generation balloon-expandable Edwards Sapien 3® (S3) transcatheter heart valve (THV) for treatment of failing THVs. Between 01/2014 and 12/2014 three patients (two male, age: 71-80 y, log EUROScore I: 11.89 - 32.63) with failing THVs were refered to our institution for further treatment. THV approach with secondary implantation of an S3 was chosen after mutual agreement of the local interdisciplinary heart team at an interval of 533-1119 days from the index procedure. The performed procedures consisted of: S3 in Sapien XT, JenaValve and CoreValve. Successful transfemoral implantation with significant reduction of PVL was achieved in all cases. No intraprocedural complications occurred regarding placement of the S3 with a postprocedural effective orifice area (EOA) of 1.5-2.5 cm(2) and pressure gradients of max/mean 14/6-36/16 mmHg. 30-day mortality was 0%. At the latest follow-up of 90-530 days, all patients are alive and well with satisfactory THV function. Regarding VARC-2 criteria one major bleeding and one TIA was reported. In the instance of moderate or severe aortic regurgitation after TAVI, S3 ViV deployment is an excellent option to reduce residual regurgitation to none or mild. For further assertions concerning functional outcomes long-term results have to be awaited.

  1. Failure investigations of failed valve plug SS410 steel due to cracking

    NASA Astrophysics Data System (ADS)

    Kalyankar, V. D.; Deshmukh, D. D.

    2017-12-01

    Premature and sudden in service failure of a valve plug due to crack formation, applied in power plant has been investigated. The plug was tempered and heat treated, the crack was originated at centre, developed along the axis and propagates radially towards outer surface of plug. The expected life of the component is 10-15 years while, the component had failed just after the installation that is, within 3 months of its service. No corrosion products were observed on the crack interface and on the failed surface; hence, causes of corrosion failure are neglected. This plug of level separator control valve, is welded to the stem by means of plasma-transferred arc welding and as there is no crack observed at the welding zone, the failure due to welding residual stresses are also neglected. The failed component discloses exposed surface of a crack interface that originated from centre and propagates radially. The micro-structural observation, hardness testing, and visual observation are carried out of the specimen prepared from the failed section and base portion. The microstructure from the cracked interface showed severe carbide formation along the grain boundaries. From the microstructural analysis of the failed sample, it is observed that there is a formation of acicular carbides along the grain boundaries due to improper tempering heat treatment.

  2. Normally-Closed Zero-Leak Valve with Magnetostrictive Actuator

    NASA Technical Reports Server (NTRS)

    Ramspacher, Daniel J. (Inventor); Richard, James A. (Inventor)

    2017-01-01

    A non-pyrotechnic, normally-closed, zero-leak valve is a replacement for the pyrovalve used for both in-space and launch vehicle applications. The valve utilizes a magnetostrictive alloy for actuation, rather than pyrotechnic charges. The alloy, such as Terfenol-D, experiences magnetostriction, i.e. a gross elongation, when exposed to a magnetic field. This elongation fractures a parent metal seal, allowing fluid flow through the valve. The required magnetic field is generated by redundant coils that are isolated from the working fluid.

  3. Effect of the sinus of valsalva on the closing motion of bileaflet prosthetic heart valves.

    PubMed

    Ohta, Y; Kikuta, Y; Shimooka, T; Mitamura, Y; Yuhta, T; Dohi, T

    2000-04-01

    Conventional bileaflet prosthetic mechanical heart valves close passively with backflow. Naturally, the valve has problems associated with closure, such as backflow, water hammer effect, and fracture of the leaflet. On the other hand, in the case of the natural aortic valve, the vortex flow in the sinus of Valsalva pushes the leaflet to close, and the valve starts the closing motion earlier than the prosthetic valve as the forward flow decelerates. This closing mechanism is thought to decrease backflow at valve closure. In this study, we propose a new bileaflet mechanical valve resembling a drawbridge in shape, and the prototype valve was designed so that the leaflet closes with the help of the vortex flow in the sinus. The test valve was made of aluminum alloy, and its closing motion was compared to that of the CarboMedics (CM) valve. Both valves were driven by a computer controlled hydraulic mock circulator and were photographed at 648 frames/s by a high speed charge-coupled device (CCD) camera. Each frame of the valve motion image was analyzed with a personal computer, and the opening angles were measured. The flow rate was set as 5.0 L/min. The system was pulsed with 70 bpm, and the systolic/diastolic ratio was 0.3. Glycerin water was used as the circulation fluid at room temperature, and polystyrene particles were used to visualize the streamline. The model of the sinus of Valsalva was made of transparent silicone rubber. As a result, high speed video analysis showed that the test valve started the closing motion 41 ms earlier than the CM valve, and streamline analysis showed that the test valve had a closing mechanism similar to the natural one with the effect of vortex flow. The structure of the test valve was thought to be effective for soft closure and could solve problems associated with closure.

  4. A normally-closed piezoelectric micro-valve with flexible stopper

    NASA Astrophysics Data System (ADS)

    Chen, Song; Lu, Song; Liu, Yong; Wang, Jiantao; Tian, Xiaochao; Liu, Guojun; Yang, Zhigang

    2016-04-01

    In the field of controlled drug delivery system, there are still many problems on those reported micro-valves, such as the small opening height, unsatisfactory particle tolerance and high cost. To solve the above problems, a novel normally-closed piezoelectric micro-valve is presented in this paper. The micro-valve was driven by circular unimorph piezoelectric vibrator and natural rubber membrane with high elasticity was used as the valve stopper. The small axial displacement of piezoelectric vibrator can be converted into a large stroke of valve stopper based on hydraulic amplification mechanism. The experiment indicates that maximum hydraulic amplification ratio is up to 14, and the cut-off pressure of the micro-valve is 39kPa in the case of no working voltage. The presented micro valve has a large flow control range (ranging from 0 to 8.75mL/min).

  5. Redo aortic valve surgery versus transcatheter valve-in-valve implantation for failing surgical bioprosthetic valves: consecutive patients in a single-center setting

    PubMed Central

    Wottke, Michael; Deutsch, Marcus-André; Krane, Markus; Piazza, Nicolo; Lange, Ruediger; Bleiziffer, Sabine

    2015-01-01

    Background Due to a considerable rise in bioprosthetic as opposed to mechanical valve implantations, an increase of patients presenting with failing bioprosthetic surgical valves in need of a reoperation is to be expected. Redo surgery may pose a high-risk procedure. Transcatheter aortic valve-in-valve implantation is an innovative, less-invasive treatment alternative for these patients. However, a comprehensive evaluation of the outcome of consecutive patients after a valve-in-valve TAVI [transcatheter aortic valve-in-surgical aortic valve (TAV-in-SAV)] as compared to a standard reoperation [surgical aortic valve redo-operation (SAV-in-SAV)] has not yet been performed. The goal of this study was to compare postoperative outcomes after TAV-in-SAV and SAV-in-SAV in a single center setting. Methods All SAV-in-SAV and TAV-in-SAV patients from January 2001 to October 2014 were retrospectively reviewed. Patients with previous mechanical or transcatheter valves, active endocarditis and concomitant cardiac procedures were excluded. Patient characteristics, preoperative data, post-procedural complications, and 30-day mortality were collected from a designated database. Mean values ± SD were calculated for all continuous variables. Counts and percentages were calculated for categorical variables. The Chi-square and Fisher exact tests were used to compare categorical variables. Continuous variables were compared using the t-test for independent samples. A 2-sided P value <0.05 was considered statistically significant. Results A total of 102 patients fulfilled the inclusion criteria, 50 patients (49%) underwent a transcatheter valve-in-valve procedure, while 52 patients (51%) underwent redo-surgery. Patients in the TAV-in-SAV group were significantly older, had a higher mean logistic EuroSCORE and exhibited a lower mean left ventricular ejection fraction than patients in the SAV-in-SAV group (78.1±6.7 vs. 66.2±13.1, P<0.001; 27.4±18.7 vs. 14.4±10, P<0.001; and 49.8±13

  6. Worcester 1 Inch Solenoid Actuated Gas Operated SCHe System Valves

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    MISKA, C.R.

    1 inch gas-operated full-port ball valves incorporate a solenoid and limit switches as integral parts of the actuator. These valves are normally open and fail safe to the open position (GOV-1*02 and 1*06 fail closed) to provide a flow path of helium gas to the MCO under helium purge and off-normal conditions when the MCO is isolated.

  7. Worcester 1 Inch Solenoid Actuated Gas Operated SCHe System Valves

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    VAN KATWIJK, C.

    1 inch Gas-operated full-port ball valves incorporate a solenoid and limit switches as integral parts of the actuator. These valves are normally open and fail safe to the open position (GOV-1*02 and 1*06 fail closed) to provide a flow path of helium gas to the MCO under helium purge and off-normal conditions when the MCO is isolated.

  8. Opening and closing characteristics of the aortic valve after valve-sparing procedures using a new aortic root conduit.

    PubMed

    De Paulis, R; De Matteis, G M; Nardi, P; Scaffa, R; Buratta, M M; Chiariello, L

    2001-08-01

    The durability of aortic valve-sparing procedures is negatively affected by increased leaflet stress in the absence of normally shaped sinuses of Valsalva. We compared valve motion after remodeling procedures using a standard conduit and a specifically designed aortic root conduit. Echocardiographic studies of the aortic valve dynamics were performed in 14 patients after remodeling of the aortic root (7 standard conduits, group A; 7 new conduits, group B) and in 7 controls (group C). Opening and closing leaflet velocities and percent of slow closing leaflet displacement were measured. Root distensibility and the pressure strain of the elastic modulus were measured at all root levels. Root distensibility and the pressure strain of the elastic modulus were different in group A and B only at the sinuses (p < 0.001). Opening and closing leaflet velocities were not different among groups. Slow closing leaflet displacement was markedly more evident in group B patients (24.2%+/-1.9% versus 2.5%+/-1.9% in group A, p < 0.001) and similar to controls (22.1%+/-7.9%). The new conduit guarantees dynamic features of the aortic valve leaflets superior to those obtained with standard conduits and more similar to normal subjects.

  9. Evaluation test program, valve, explosive actuated, normally closed Pyronetics model 1400

    NASA Technical Reports Server (NTRS)

    Avalos, E.

    1971-01-01

    Evaluation tests of the explosive actuated normally closed valves used to control and isolate hydrazine flow in the TOPS spacecraft, are presented. The malfunctions, modifications, service life, and reliability of the valve are also outlined.

  10. 46 CFR 35.35-10 - Closing of freeing-ports, scuppers, and sea valves-TB/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Closing of freeing-ports, scuppers, and sea valves-TB... OPERATIONS Cargo Handling § 35.35-10 Closing of freeing-ports, scuppers, and sea valves—TB/ALL. The person in... no circumstances may sea valves be secured by locks, the valves must be closed, and lashed or sealed...

  11. 46 CFR 35.35-10 - Closing of freeing-ports, scuppers, and sea valves-TB/ALL.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Closing of freeing-ports, scuppers, and sea valves-TB... OPERATIONS Cargo Handling § 35.35-10 Closing of freeing-ports, scuppers, and sea valves—TB/ALL. The person in... no circumstances may sea valves be secured by locks, the valves must be closed, and lashed or sealed...

  12. Fast closing valve

    DOEpatents

    Hanson, Clark L.

    1984-01-10

    A valve is provided for protecting the high vacuum of a particle accelera in the event of air leakage, wherein the valve provides an axially symmetrical passage to avoid disturbance of the partical beam during normal operation, and yet enables very rapid and tight closure of the beam-carrying pipe in the event of air leakage. The valve includes a ball member (30) which can rotate between a first position wherein a bore (32) in the member is aligned with the beam pipe, and a second position out of line with the pipe. A seal member (38) is flexibly sealed to the pipe, and has a seal end which can move tightly against the ball member after the bore has rotated out of line with the pipe, to thereby assure that the seal member does not retard rapid rotation of the ball valve member. The ball valve member can be rapidly rotated by a conductive arm (40) fixed to it and which is rotated by the discharge of a capacitor bank through coils (44, 45) located adjacent to the arm.

  13. Surgical results of trabeculectomy and Ahmed valve implantation following a previous failed trabeculectomy in primary congenital glaucoma patients.

    PubMed

    Lee, Naeun; Ma, Kyoung Tak; Bae, Hyoung Won; Hong, Samin; Seong, Gong Je; Hong, Young Jae; Kim, Chan Yun

    2015-04-01

    To compare the surgical results of trabeculectomy and Ahmed glaucoma valve implantation after a previous failed trabeculectomy. A retrospective comparative case series review was performed on 31 eye surgeries in 20 patients with primary congenital glaucoma who underwent trabeculectomy or Ahmed glaucoma valve implantation after a previous failed trabeculectomy with mitomycin C. The preoperative mean intraocular pressure was 25.5 mmHg in the trabeculectomy group and 26.9 mmHg in the Ahmed glaucoma valve implantation group (p = 0.73). The 48-month postoperative mean intraocular pressure was 19.6 mmHg in the trabeculectomy group and 20.2 mmHg in the Ahmed glaucoma valve implantation group (p = 0.95). The 12-month trabeculectomy success rate was 69%, compared with 64% for Ahmed glaucoma valve implantation, and the 48-month success rates were 42% and 36% for trabeculectomy and valve implantation, respectively. The success rates following the entire follow-up period were not significantly different between the two groups (p > 0.05 by log rank test). Postoperative complications occurred in 25% of the trabeculectomy-operated eyes and 9% of the Ahmed-implanted eyes (p = 0.38). There was no significant difference in surgical outcome between the trabeculectomy and Ahmed glaucoma valve implantation groups, neither of which had favorable results. However, the trabeculectomy group demonstrated a higher prevalence of adverse complications such as post-operative endophthalmitis.

  14. Safety and Efficacy of Transcatheter Aortic Valve Replacement in the Treatment of Pure Aortic Regurgitation in Native Valves and Failing Surgical Bioprostheses: Results From an International Registry Study.

    PubMed

    Sawaya, Fadi J; Deutsch, Marcus-André; Seiffert, Moritz; Yoon, Sung-Han; Codner, Pablo; Wickramarachchi, Upul; Latib, Azeem; Petronio, A Sonia; Rodés-Cabau, Josep; Taramasso, Maurizio; Spaziano, Marco; Bosmans, Johan; Biasco, Luigi; Mylotte, Darren; Savontaus, Mikko; Gheeraert, Peter; Chan, Jason; Jørgensen, Troels H; Sievert, Horst; Mocetti, Marco; Lefèvre, Thierry; Maisano, Francesco; Mangieri, Antonio; Hildick-Smith, David; Kornowski, Ran; Makkar, Raj; Bleiziffer, Sabine; Søndergaard, Lars; De Backer, Ole

    2017-05-22

    The aim of this study was to evaluate the use of transcatheter heart valves (THV) for the treatment of noncalcific pure native aortic valve regurgitation (NAVR) and failing bioprosthetic surgical heart valves (SHVs) with pure severe aortic regurgitation (AR). Limited data are available about the "off-label" use of transcatheter aortic valve replacement (TAVR) to treat pure severe AR. The study population consisted of patients with pure severe AR treated by TAVR at 18 different centers. Study endpoints were device success, early safety, and clinical efficacy at 30 days, as defined by Valve Academic Research Consortium 2 criteria. A total of 146 patients were included, 78 patients in the NAVR group and 68 patients in the failing SHV group. In the NAVR group, device success, early safety, and clinical efficacy were 72%, 66%, and 61%, respectively. Device success and clinical efficacy were significantly better with newer generation THVs compared with old-generation THVs (85% vs. 54% and 75% vs. 46%, respectively, p < 0.05); this was mainly due to less second THV implantations and a lower rate of moderate to severe paravalvular regurgitation (10% vs. 24% and 3% vs. 27%, respectively). Independent predictors of 30-day mortality were body mass index <20 kg/m 2 , STS surgical risk score >8%, major vascular or access complication, and moderate to severe AR. In the failing SHV group, device success, early safety, and clinical efficacy were 71%, 90%, and 77%, respectively. TAVR for pure NAVR remains a challenging condition, with old-generation THVs being associated with THV embolization and migration and significant paravalvular regurgitation. Newer generation THVs show more promising outcomes. For those patients with severe AR due to failing SHVs, TAVR is a valuable therapeutic option. Copyright © 2017 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  15. 46 CFR 154.540 - Quick-closing shut-off valves: Emergency shut-down system.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... BULK DANGEROUS CARGOES SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design... emergency shut-down system that: (a) Closes all the valves; (b) Is actuated by a single control in at least two locations remote from the quick-closing valves; (c) Is actuated by a single control in each cargo...

  16. 46 CFR 154.540 - Quick-closing shut-off valves: Emergency shut-down system.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... BULK DANGEROUS CARGOES SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design... emergency shut-down system that: (a) Closes all the valves; (b) Is actuated by a single control in at least two locations remote from the quick-closing valves; (c) Is actuated by a single control in each cargo...

  17. Surgical Results of Trabeculectomy and Ahmed Valve Implantation Following a Previous Failed Trabeculectomy in Primary Congenital Glaucoma Patients

    PubMed Central

    Lee, Naeun; Ma, Kyoung Tak; Bae, Hyoung Won; Hong, Samin; Seong, Gong Je; Hong, Young Jae

    2015-01-01

    Purpose To compare the surgical results of trabeculectomy and Ahmed glaucoma valve implantation after a previous failed trabeculectomy. Methods A retrospective comparative case series review was performed on 31 eye surgeries in 20 patients with primary congenital glaucoma who underwent trabeculectomy or Ahmed glaucoma valve implantation after a previous failed trabeculectomy with mitomycin C. Results The preoperative mean intraocular pressure was 25.5 mmHg in the trabeculectomy group and 26.9 mmHg in the Ahmed glaucoma valve implantation group (p = 0.73). The 48-month postoperative mean intraocular pressure was 19.6 mmHg in the trabeculectomy group and 20.2 mmHg in the Ahmed glaucoma valve implantation group (p = 0.95). The 12-month trabeculectomy success rate was 69%, compared with 64% for Ahmed glaucoma valve implantation, and the 48-month success rates were 42% and 36% for trabeculectomy and valve implantation, respectively. The success rates following the entire follow-up period were not significantly different between the two groups (p > 0.05 by log rank test). Postoperative complications occurred in 25% of the trabeculectomy-operated eyes and 9% of the Ahmed-implanted eyes (p = 0.38). Conclusions There was no significant difference in surgical outcome between the trabeculectomy and Ahmed glaucoma valve implantation groups, neither of which had favorable results. However, the trabeculectomy group demonstrated a higher prevalence of adverse complications such as post-operative endophthalmitis. PMID:25829827

  18. A high performance normally closed solenoid-actuated cold valve.

    PubMed

    Taminiau, I A J; Benningshof, O W B; Jochemsen, R

    2009-08-01

    An electromagnetically driven normally closed valve for liquid helium is presented, which is meant to regulate the input flow to a 1 K pot. An earlier design is modified to be normally closed (not actuated) and tuned for durability and reliability. A new feature is presented which prevents seat deformation at room temperature and provides comfort and durability for intensive use.

  19. Enhanced Component Performance Study: Air-Operated Valves 1998-2014

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Schroeder, John Alton

    2015-11-01

    This report presents a performance evaluation of air-operated valves (AOVs) at U.S. commercial nuclear power plants. The data used in this study are based on the operating experience failure reports from fiscal year 1998 through 2014 for the component reliability as reported in the Institute of Nuclear Power Operations (INPO) Consolidated Events Database (ICES). The AOV failure modes considered are failure-to-open/close, failure to operate or control, and spurious operation. The component reliability estimates and the reliability data are trended for the most recent 10-year period, while yearly estimates for reliability are provided for the entire active period. One statistically significantmore » trend was observed in the AOV data: The frequency of demands per reactor year for valves recording the fail-to-open or fail-to-close failure modes, for high-demand valves (those with greater than twenty demands per year), was found to be decreasing. The decrease was about three percent over the ten year period trended.« less

  20. Transcatheter Aortic Valve-in-Valve Procedure in Patients with Bioprosthetic Structural Valve Deterioration

    PubMed Central

    Reul, Ross M.; Ramchandani, Mahesh K.; Reardon, Michael J.

    2017-01-01

    Surgical aortic valve replacement is the gold standard procedure to treat patients with severe, symptomatic aortic valve stenosis or insufficiency. Bioprosthetic valves are used for surgical aortic valve replacement with a much greater prevalence than mechanical valves. However, bioprosthetic valves may fail over time because of structural valve deterioration; this often requires intervention due to severe bioprosthetic valve stenosis or regurgitation or a combination of both. In select patients, transcatheter aortic valve replacement is an alternative to surgical aortic valve replacement. Transcatheter valve-in-valve (ViV) replacement is performed by implanting a transcatheter heart valve within a failing bioprosthetic valve. The transcatheter ViV operation is a less invasive procedure compared with reoperative surgical aortic valve replacement, but it has been associated with specific complications and requires extensive preoperative work-up and planning by the heart team. Data from experimental studies and analyses of results from clinical procedures have led to strategies to improve outcomes of these procedures. The type, size, and implant position of the transcatheter valve can be optimized for individual patients with knowledge of detailed dimensions of the surgical valve and radiographic and echocardiographic measurements of the patient's anatomy. Understanding the complexities of the ViV procedure can lead surgeons to make choices during the original surgical valve implantation that can make a future ViV operation more technically feasible years before it is required. PMID:29743998

  1. 9. Close view of gate valves (foreground), paddle wheel guard ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    9. Close view of gate valves (foreground), paddle wheel guard (midground), and water wheel (background), facing southeast (downstream) from drum screen cover. - Congdon Canal, Fish Screen, Naches River, Yakima, Yakima County, WA

  2. 46 CFR 153.980 - Isolation of automatic closing valves.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Isolation of automatic closing valves. 153.980 Section 153.980 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SHIPS CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Operations Cargo...

  3. 46 CFR 153.980 - Isolation of automatic closing valves.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Isolation of automatic closing valves. 153.980 Section 153.980 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SHIPS CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Operations Cargo...

  4. 46 CFR 153.980 - Isolation of automatic closing valves.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Isolation of automatic closing valves. 153.980 Section 153.980 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SHIPS CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Operations Cargo...

  5. 46 CFR 153.980 - Isolation of automatic closing valves.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 false Isolation of automatic closing valves. 153.980 Section 153.980 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SHIPS CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Operations Cargo...

  6. 46 CFR 153.980 - Isolation of automatic closing valves.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 5 2013-10-01 2013-10-01 false Isolation of automatic closing valves. 153.980 Section 153.980 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SHIPS CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Operations Cargo...

  7. 49 CFR Appendix A to Part 180 - Internal Self-closing Stop Valve Emergency Closure Test for Liquefied Compressed Gases

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Part 180—Internal Self-closing Stop Valve Emergency Closure Test for Liquefied Compressed Gases 1. In performing this test, all internal self-closing stop valves must be opened. Each emergency discharge control... 49 Transportation 3 2011-10-01 2011-10-01 false Internal Self-closing Stop Valve Emergency Closure...

  8. Worcester 1 Inch Solenoid Actuated Gas Operated SCHe System Valves

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    VAN KATWIJK, C.

    1 inch Gas-operated full-port ball valves incorporate a solenoid and limit switches as integral parts of the actuator. These valves are normally open and fail safe to the open position (GOV-1*02 and 1*06 fall closed) to provide a flow path of helium gas to the MCO under helium purge and off-normal conditions when the MCO is isolated.

  9. Anterior urethral valve associated with posterior urethral valves.

    PubMed

    Kajbafzadeh, A M; Jangouk, P; Ahmadi Yazdi, C

    2005-12-01

    The association of anterior urethral valve (AUV) with posterior urethral valve (PUV) is rare. A 7-month-old infant was presented at a district hospital with episodes of acute pyelonephritis. He was treated medically and a voiding cystourethrogram (VCUG) confirmed bilateral vesico-urethral reflux. The presence of concomitant AUV and PUV was not recognized. He underwent several surgical procedures, which failed. He had reflux recurrence following two antireflux procedures. He had urinary retention after each operation, which was managed by vesicostomy and perineal urethrostomy. At the age of 3.5 years, he was referred to our paediatric urology clinic. Noticing the AUV and PUV in the past VCUG, the valves were fulgurated. Urodynamic study before and 3 months after valve ablation showed a high voiding pressure. VCUG 6 months following ablation showed no reflux, but several uroflowmetric studies showed a staccato and interrupted pattern. Empirical treatment with an alpha-blocker was started. One year after treatment, a repeat VCUG showed no reflux. Uroflowmetry and urodynamic studies returned to normal. The perineal urethrostomy was closed. The child was asymptomatic after 9 months of follow up.

  10. 49 CFR Appendix B to Part 180 - Acceptable Internal Self-closing Stop Valve Leakage Tests for Cargo Tanks Transporting Liquefied...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Acceptable Internal Self-closing Stop Valve... Pt. 180, App. B Appendix B to Part 180—Acceptable Internal Self-closing Stop Valve Leakage Tests for Cargo Tanks Transporting Liquefied Compressed Gases For internal self-closing stop valve leakage testing...

  11. Failing left ventricle to ascending aorta conduit-Hybrid implantation of a melody valve and NuMed covered stent.

    PubMed

    Gössl, Mario; Johnson, Jonathan N; Hagler, Donald J

    2014-04-01

    We present the case of a 36-year-old woman with increasing shortness of breath, a new 3/4 diastolic murmur, and a complex history of LV outflow tract obstruction. She has undergone multiple surgeries including the replacement of her old LV apex to ascending aorta conduit with a 20-mm Gore-Tex tube graft, addition of a 24-mm homograft sutured between the conduit and the LV apex, and insertion of a 21-mm Freestyle porcine valve conduit between the Gore-Tex tube graft and allograft at age 23. The current assessment showed a failing Freestyle conduit prosthesis leading to left heart decompensation. Due to substantial surgical risk, the patient underwent successful implantation of a Melody valve into the Gore-Tex tube and exclusion of the failing Freestyle bioprosthesis with a NuMed CP stent in a hybrid procedure. The case nicely illustrates the collaborative potential of cardiovascular surgeons and interventional cardiologists in the new arena of a hybrid operating room. Complex hybrid procedures like the current one, especially those including percutaneous placements of valves, offer therapeutic options for patients that are otherwise too high risk for conventional open heart surgery. Copyright © 2013 Wiley Periodicals, Inc.

  12. 46 CFR 153.284 - Characteristics of required quick closing valves.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Characteristics of required quick closing valves. 153.284 Section 153.284 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK... and Equipment Piping Systems and Cargo Handling Equipment § 153.284 Characteristics of required quick...

  13. 46 CFR 153.284 - Characteristics of required quick closing valves.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Characteristics of required quick closing valves. 153.284 Section 153.284 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK... and Equipment Piping Systems and Cargo Handling Equipment § 153.284 Characteristics of required quick...

  14. Failing stentless Bioprostheses in patients with carcinoid heart valve disease.

    PubMed

    Schaefer, Andreas; Sill, Bjoern; Schoenebeck, Jeannette; Schneeberger, Yvonne; Reichenspurner, Hermann; Gulbins, Helmut

    2015-03-27

    Carcinoid tumor with consecutive endocardial fibroelastosis of the right heart, known as carcinoid heart valve disease (CHVD) or Hedinger's syndrome, is accompanied by combined right-sided valvular dysfunction with regurgitation and stenosis of the affected valves. Cardiac surgery with replacement of the tricuspid and/or pulmonary valve is an established therapeutic option for patients with Hedinger's syndrome. Little is known about the long term outcome and the choice of prosthesis for the pulmonal position is still a matter of debate. The authors report three cases of pulmonary valve replacement with stentless bioprostheses (Medtronic Freestyle, Medtronic PLC, Minneapolis, MN, USA) due to severe pulmonary valve degeneration in consequence of Hedinger's syndrome. All patients presented with re-stenosis of the pulmonal valve conduit at the height of the anastomoses in a premature fashion. Due to the increased risk for repeat surgical valve replacement, two patients were treated by transcatheter heart valves. We do not recommend the replacement of the pulmonary valve with stentless bioprostheses in patients with CHVD. These valves presented with an extreme premature degeneration and consecutive re-stenosis and heart failure.

  15. Fast valve

    DOEpatents

    Van Dyke, W.J.

    1992-04-07

    A fast valve is disclosed that can close on the order of 7 milliseconds. It is closed by the force of a compressed air spring with the moving parts of the valve designed to be of very light weight and the valve gate being of wedge shaped with O-ring sealed faces to provide sealing contact without metal to metal contact. The combination of the O-ring seal and an air cushion create a soft final movement of the valve closure to prevent the fast air acting valve from having a harsh closing. 4 figs.

  16. Fast valve

    DOEpatents

    Van Dyke, William J.

    1992-01-01

    A fast valve is disclosed that can close on the order of 7 milliseconds. It is closed by the force of a compressed air spring with the moving parts of the valve designed to be of very light weight and the valve gate being of wedge shaped with O-ring sealed faces to provide sealing contact without metal to metal contact. The combination of the O-ring seal and an air cushion create a soft final movement of the valve closure to prevent the fast air acting valve from having a harsh closing.

  17. MANAGEMENT OF FAILED MITRAL VALVE REPLACEMENT. THE DURBAN EXPERIENCE.

    PubMed

    Kistan, D; Booysen, M; Alexander, G; Madiba, T E

    2017-06-01

    Mitral valve replacement is the procedure of choice in patients with severe mitral valve disease. However, these patients are surviving longer and are thus at an increased risk of prosthesis failure or valve-related complications. Study setting: Inkosi Albert Luthuli Central Hospital, a tertiary referral Hospital in Durban. Study population: All patients undergoing redo mechanical mitral valve replacement surgery between January 2005 and December 2014. Study design: Retrospective analysis of patients undergoing redo mitral valve replacement. Patients were identified from theatre record books, their files were electronically accessed and pertinent information extracted onto a data capture sheet. Information documented included demographics, duration to failure, INR, Albumin, HIV status, clinical findings and outcome. The data was stored on an Excel datasheet. Fifty-eight patients were documented (mean age 32 ± 15.81 years; M:F 1:3). Ten patients (17%) were HIV positive (median CD4 count 478). Mean duration between first surgery and redo was 8.8 years. Thirty-five patients (60%) had no co-morbidities. Presenting features at redo surgery were congestive cardiac failure (27), chest pain (11) and palpitations (17). Mean preoperative Ejection Fraction was 51.65 %. Twenty-nine patients (55%) had emergency redo surgery. Twenty-two patients (75%) had acute prosthetic valve thrombosis. Thirty-two patients had tricuspid regurgitation. Original pathology was documented in 23 patients (40%) as Rheumatic valve disease. Prosthetic valve thrombosis was documented in 31 patients (54%). The most commonly used valve was the On-X. Mean presenting INR was 1.96 + 1.2 and mean presenting serum albumin was 36.7 + 7.8 g/l. Forty-one patients (71%) were found to be compliant to Warfarin therapy prior to redo surgery. Mean ICU stay was 6 +9 days. Two patients died postoperatively. Mean followup was 32 + 26.6 months. Twelve patients (20.7%) developed postoperative complications. Patients

  18. Occluder closing behavior: a key factor in mechanical heart valve cavitation.

    PubMed

    Wu, Z J; Wang, Y; Hwang, N H

    1994-04-01

    A laser sweeping technique developed in this laboratory was found to be capable of monitoring the leaflet closing motion with microsecond precision. The leaflet closing velocity was measured inside the last three degrees before impact. Mechanical heart valve (MHV) leaflets were observed to close with a three-phase motion; the approaching phase, the decelerating phase, and the rebound phase, all of which take place within one to two milliseconds. The leaflet closing behavior depends mainly on the leaflet design and the hinge mechanism. Bileaflet and monoleaflet types of mechanical heart valves were tested in the mitral position in a physiologic mock circulatory flow loop, which incorporated a computer-controlled magnetic drive and an adjustable afterload system. The test loop was tuned to produce physiologic ventricular and aortic pressure wave forms at 70-120 beats/min, with the maximum ventricular dp/dt varying between 1500-5600 mmHg/sec. The experiments were conducted by controlling the cardiac output at a constant level between 2.0-9.0 liters/min. The measured time-displacement curve of each tested MHV leaflet and its geometry were taken as the input for computation of the squeeze flow field in the narrow gap space between the approaching leaflet and the valve housing. The results indicated rapid build-up of both the pressure and velocity in the gap field within microsecs before the impact. The pressure build-up in the gap space is apparently responsible for the leaflet deceleration before the impact. When the concurrent water hammer pressure reduction at closure was combined with the high energy squeeze jet ejected from the gap space, there were strong indications of the environment which favors micro cavitation inceptions in certain types of MHV.

  19. Valve in valve transcatheter aortic valve implantation (ViV-TAVI) versus redo-Surgical aortic valve replacement (redo-SAVR): A systematic review and meta-analysis.

    PubMed

    Nalluri, Nikhil; Atti, Varunsiri; Munir, Abdullah B; Karam, Boutros; Patel, Nileshkumar J; Kumar, Varun; Vemula, Praveen; Edla, Sushruth; Asti, Deepak; Paturu, Amrutha; Gayam, Sriramya; Spagnola, Jonathan; Barsoum, Emad; Maniatis, Gregory A; Tamburrino, Frank; Kandov, Ruben; Lafferty, James; Kliger, Chad

    2018-05-20

    Bioprosthetic (BP) valves have been increasingly used for aortic valve replacement over the last decade. Due to their limited durability, patients presenting with failed BP valves are rising. Valve in Valve - Transcatheter Aortic Valve Implantation (ViV-TAVI) emerged as an alternative to the gold standard redo-Surgical Aortic Valve Replacement (redo-SAVR). However, the utility of ViV-TAVI is poorly understood. A systematic electronic search of the scientific literature was done in PubMed, EMBASE, SCOPUS, Google Scholar, and ClinicalTrials.gov. Only studies which compared the safety and efficacy of ViV-TAVI and redo-SAVR head to head in failed BP valves were included. Six observational studies were eligible and included 594 patients, of whom 255 underwent ViV- TAVI and 339 underwent redo-SAVR. There was no significant difference between ViV-TAVI and redo- SAVR for procedural, 30 day and 1 year mortality rates. ViV-TAVI was associated with lower risk of permanent pacemaker implantation (PPI) (OR: 0.43, CI: 0.21-0.89; P = 0.02) and a trend toward increased risk of paravalvular leak (PVL) (OR: 5.45, CI: 0.94-31.58; P = 0.06). There was no significant difference for stroke, major bleeding, vascular complications and postprocedural aortic valvular gradients more than 20 mm-hg. Our results reiterate the safety and feasibility of ViV-TAVI for failed aortic BP valves in patients deemed to be at high risk for surgery. VIV-TAVI was associated with lower risk of permanent pacemaker implantation with a trend toward increased risk of paravalvular leak. © 2018, Wiley Periodicals, Inc.

  20. Development of Long-Lifetime Pulsed Gas Valves for Pulsed Electric Thrusters

    NASA Technical Reports Server (NTRS)

    Burkhardt, Wendel M.; Crapuchettes, John M.; Addona, Brad M.; Polzin, Kurt A.

    2015-01-01

    The design and test results for two types of pulsed gas valves are presented. The valves, a piezo valve and a solenoid actuated valve, must have exceedingly long lifetime to support gas-fed pulsed electric thruster operation for missions of interest. The performance of both valves was tested, with both demonstrating the capability to throttle the gas flow rate while maintaining low leakage levels below 10(exp -3) sccs of He at the beginning of valve lifetime. The piezo valve varies the flow rate by changing the amount that the valve is open, which is a function of applied voltage. This valve demonstrated continuous throttlability from 0-10 mL/s, with opening and closing times of 100 microsecond or less. The solenoid actuated valve flow rate changes as a function of the inlet gas pressure, with demonstrated flow rates in these tests from 2.7-11 mL per second. The valve response time is slower than the piezo valve, opening in 1-2 ms and closing in several ms. The solenoid actuated valve was tested to one million cycles, with the valve performance remaining relatively unchanged throughout the test. Galling of the sliding plunger caused the valve to bind and fail just after one million cycles, but at this point in the test the valve sealing surface leak rate still appeared to be well below the maximum target leak rake of 1×10(exp -3) sccs of He.

  1. A numerical insight into elastomer normally closed micro valve actuation with cohesive interfacial cracking modelling

    NASA Astrophysics Data System (ADS)

    Wang, Dongyang; Ba, Dechun; Hao, Ming; Duan, Qihui; Liu, Kun; Mei, Qi

    2018-05-01

    Pneumatic NC (normally closed) valves are widely used in high density microfluidics systems. To improve actuation reliability, the actuation pressure needs to be reduced. In this work, we utilize 3D FEM (finite element method) modelling to get an insight into the valve actuation process numerically. Specifically, the progressive debonding process at the elastomer interface is simulated with CZM (cohesive zone model) method. To minimize the actuation pressure, the V-shape design has been investigated and compared with a normal straight design. The geometrical effects of valve shape has been elaborated, in terms of valve actuation pressure. Based on our simulated results, we formulate the main concerns for micro valve design and fabrication, which is significant for minimizing actuation pressures and ensuring reliable operation.

  2. Depressurization valve

    DOEpatents

    Skoda, George I.

    1989-01-01

    A depressurization valve for use in relieving completely the pressure in a simplified boiling water reactor is disclosed. The normally closed and sealed valve is provided with a valve body defining a conduit from an outlet of a manifold from the reactor through a valve seat. A closing valve disk is configured for fitting to the valve seat to normally close the valve. The seat below the disk is provided with a radially extending annulus extending a short distance into the aperture defined by the seat. The disk is correspondingly provided with a longitudinally extending annulus that extends downwardly through the aperture defined by the seat towards the high pressure side of the valve body. A ring shaped membrane is endlessly welded to the seat annulus and to the disk annulus. The membrane is conformed over the confronted surface of the seat and disk in a C-sectioned configuration to seal the depressurization valve against the possibility of weeping. The disk is held to the closed position by an elongate stem extending away from the high pressure side of the valve body. The stem has a flange configured integrally to the stem for bias by two springs. The first spring acts from a portion of the housing overlying the disk on the stem flange adjacent the disk. This spring urges the stem and attached disk away from the seat and thus will cause the valve to open at any pressure. A second spring--preferably of the Belleville variety--acts on a latch plate surrounding and freely moving relative to the end of the stem. This second spring overcomes the bias of the first spring and any pressure acting upon the disk. This Belleville spring maintains through its spring force the valve in the closed position. At the same time, the latch plate with its freedom of movement relative to the stem allows the stem to thermally expand during valve temperature excursion. The latch plate in surrounding the stem is limited in its outward movement by a boss attached to the stem at the end of

  3. Depressurization valve

    DOEpatents

    Skoda, G.I.

    1989-03-28

    A depressurization valve for use in relieving completely the pressure in a simplified boiling water reactor is disclosed. The normally closed and sealed valve is provided with a valve body defining a conduit from an outlet of a manifold from the reactor through a valve seat. A closing valve disk is configured for fitting to the valve seat to normally close the valve. The seat below the disk is provided with a radially extending annulus extending a short distance into the aperture defined by the seat. The disk is correspondingly provided with a longitudinally extending annulus that extends downwardly through the aperture defined by the seat towards the high pressure side of the valve body. A ring shaped membrane is endlessly welded to the seat annulus and to the disk annulus. The membrane is conformed over the confronted surface of the seat and disk in a C-sectioned configuration to seal the depressurization valve against the possibility of weeping. The disk is held to the closed position by an elongate stem extending away from the high pressure side of the valve body. The stem has a flange configured integrally to the stem for bias by two springs. The first spring acts from a portion of the housing overlying the disk on the stem flange adjacent the disk. This spring urges the stem and attached disk away from the seat and thus will cause the valve to open at any pressure. A second spring-preferably of the Belleville variety-acts on a latch plate surrounding and freely moving relative to the end of the stem. This second spring overcomes the bias of the first spring and any pressure acting upon the disk. This Belleville spring maintains through its spring force the valve in the closed position. At the same time, the latch plate with its freedom of movement relative to the stem allows the stem to thermally expand during valve temperature excursion.

  4. 49 CFR Appendix B to Part 180 - Acceptable Internal Self-closing Stop Valve Leakage Tests for Cargo Tanks Transporting Liquefied...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Acceptable Internal Self-closing Stop Valve Leakage Tests for Cargo Tanks Transporting Liquefied Compressed Gases B Appendix B to Part 180... Leakage Tests for Cargo Tanks Transporting Liquefied Compressed Gases For internal self-closing stop valve...

  5. 49 CFR Appendix A to Part 180 - Internal Self-closing Stop Valve Emergency Closure Test for Liquefied Compressed Gases

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Test for Liquefied Compressed Gases A Appendix A to Part 180 Transportation Other Regulations Relating... Compressed Gases 1. In performing this test, all internal self-closing stop valves must be opened. Each.... 2. On pump-actuated pressure differential internal valves, the three-way toggle valve handle or its...

  6. 49 CFR Appendix B to Part 180 - Acceptable Internal Self-closing Stop Valve Leakage Tests for Cargo Tanks Transporting Liquefied...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Leakage Tests for Cargo Tanks Transporting Liquefied Compressed Gases B Appendix B to Part 180... Pt. 180, App. B Appendix B to Part 180—Acceptable Internal Self-closing Stop Valve Leakage Tests for.... (b) Internal Self-Closing Stop Valve Test. An operator of a cargo tank that is not equipped with a...

  7. Early Outcomes for Valve-in-valve Transcatheter Aortic Valve Replacement in Degenerative Freestyle Bioprostheses.

    PubMed

    Sang, Stephane Leung Wai; Beute, Tyler; Heiser, John; Berkompas, Duane; Fanning, Justin; Merhi, William

    2017-11-20

    Transcatheter aortic valve replacement (TAVR) is used increasingly to treat bioprosthetic valve failure. A paucity of data exists regarding valve-in-valve (ViV) TAVR in degenerated Freestyle stentless bioprostheses (FSBs). This study sought to evaluate the feasibility and short-term outcomes of ViV TAVR in previously placed FSB. From October 2014 to September 2016, 22 patients at a single institution underwent ViV TAVR with a self-expanding transcatheter valve for a failing FSB. Patient baseline characteristics and clinical outcomes data were collected retrospectively and entered into a dedicated database. The mean patient age was 74 ± 9years, and the mean Society of Thoracic Surgeons' Risk score was 9.0 ± 7.4%. Ten patients presented with acute heart failure requiring urgent intervention. The most common mode of failure of the FSB was regurgitation caused by a flail or malcoapting leaflet. Seventeen (77%) patients had a modified subcoronary implantation, 3 (14%) had a full root replacement, and 2 (9%) had a root inclusion. Device success using a self-expanding transcatheter valve was 95%, all via transfemoral approach. The mean implant depth was 7 ± 3 mm. Thirty-day survival was 100%. No patient had more than mild paravalvular regurgitation at 30days, and the permanent pacemaker rate was 9%. The mean hospital stay after intervention was 5 ± 2days. ViV TAVR using a self-expanding transcatheter valve is safe, feasible, and can be used successfully to treat a failed FSB. Procedural challenges suggest referral to valve centers of excellence. Copyright © 2017 Elsevier Inc. All rights reserved.

  8. Face-Sealing Butterfly Valve

    NASA Technical Reports Server (NTRS)

    Tervo, John N.

    1992-01-01

    Valve plate made to translate as well as rotate. Valve opened and closed by turning shaft and lever. Interactions among lever, spring, valve plate, and face seal cause plate to undergo combination of translation and rotation so valve plate clears seal during parts of opening and closing motions.

  9. Statistical Performance Evaluation Of Soft Seat Pressure Relief Valves

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Harris, Stephen P.; Gross, Robert E.

    2013-03-26

    Risk-based inspection methods enable estimation of the probability of failure on demand for spring-operated pressure relief valves at the United States Department of Energy's Savannah River Site in Aiken, South Carolina. This paper presents a statistical performance evaluation of soft seat spring operated pressure relief valves. These pressure relief valves are typically smaller and of lower cost than hard seat (metal to metal) pressure relief valves and can provide substantial cost savings in fluid service applications (air, gas, liquid, and steam) providing that probability of failure on demand (the probability that the pressure relief valve fails to perform its intendedmore » safety function during a potentially dangerous over pressurization) is at least as good as that for hard seat valves. The research in this paper shows that the proportion of soft seat spring operated pressure relief valves failing is the same or less than that of hard seat valves, and that for failed valves, soft seat valves typically have failure ratios of proof test pressure to set pressure less than that of hard seat valves.« less

  10. Exchange biased and closed-flux pseudo spin-valve materials, device applications, and electrical reliability

    NASA Astrophysics Data System (ADS)

    Bae, Seongtae

    Since giant magnetoresistance (GMR) and tunneling magnetoresistance (TMR) spinvalve effects were developed for the last two decades after discovered, world wide researches on applying these effects for various kinds of solid state active devices has provided a strong impact on challenging new functional micro-magnetoelectronic devices. In particular, recently developed nano-structured magnetic spin-valve thin film materials for spin-electronic devices are now considered as building blocks of state-of-the-art electronic engineering. This research has been concentrated on developing and designing magneto-electronic solid state devices with high thermal and electrical stability using an alpha-Fe 2O3 and NiO oxide anti-ferromagnetic exchange biased GMR bottom spin-valves (BSV), NiFe/Cu/Co and NiFe/Cu/CoFe based closed-flux metallic pseudo spin-valves, and PtMn exchange biased TMR spin-valves. The category covering this research is divided into four main research steps. First is to investigate exchange bias coupling characteristics of alpha-Fe2 O3 and NiO oxide Anti-ferromagnetic materials (AF)/Ferromagnetic (F) layer systems for optimizing exchange biased BSV and to study magnetic properties of various kinds of magnetic thin films including single through multi-layered structures for the fundamental research on NiFe/Cu/Co and NiFe/Cu/CoFe closed-flux metallic pseudo spin-valves. Second is to develop and improve new kinds of BSVs and closed-flux metallic spinvalves by controlling process parameters in terms of crystalline orientation texture of AF and F layers, interfacial surface roughness, grain size (its size distribution), chemical composition, and kinetics of sputtering film growth. Third is to design, to fabricate, and to investigate the magnetic and electrical properties of magneto-electronic devices as well as their applications such as GMR magnetoresistive random access memory (MRAM), GMR read head, TMR read head, and new kinds of GMR solid state devices, which

  11. Fast-Acting Valve

    NASA Technical Reports Server (NTRS)

    Wojciechowski, Bogdan V. (Inventor); Pegg, Robert J. (Inventor)

    2003-01-01

    A fast-acting valve includes an annular valve seat that defines an annular valve orifice between the edges of the annular valve seat, an annular valve plug sized to cover the valve orifice when the valve is closed, and a valve-plug holder for moving the annular valve plug on and off the annular valve seat. The use of an annular orifice reduces the characteristic distance between the edges of the valve seat. Rather than this distance being equal to the diameter of the orifice, as it is for a conventional circular orifice, the characteristic distance equals the distance between the inner and outer radii (for a circular annulus). The reduced characteristic distance greatly reduces the gap required between the annular valve plug and the annular valve seat for the valve to be fully open, thereby greatly reducing the required stroke and corresponding speed and acceleration of the annular valve plug. The use of a valve-plug holder that is under independent control to move the annular valve plug between its open and closed positions is important for achieving controllable fast operation of the valve.

  12. Locking apparatus for gate valves

    DOEpatents

    Fabyan, J.; Williams, C.W.

    A locking apparatus for fluid operated valves having a piston connected to the valve actuator which moves in response to applied pressure within a cylinder housing having a cylinder head, a catch block is secured to the piston, and the cylinder head incorporates a catch pin. Pressure applied to the cylinder to open the valve moves the piston adjacent to the cylinder head where the catch pin automatically engages the catch block preventing further movement of the piston or premature closure of the valve. Application of pressure to the cylinder to close the valve, retracts the catch pin, allowing the valve to close. Included are one or more selector valves, for selecting pressure application to other apparatus depending on the gate valve position, open or closed, protecting such apparatus from damage due to premature closing caused by pressure loss or operational error.

  13. High-risk Trans-Catheter Aortic Valve Replacement in a Failed Freestyle Valve with Low Coronary Height: A Case Report.

    PubMed

    Karimi, Ashkan; Pourafshar, Negiin; Dibu, George; Beaver, Thomas M; Bavry, Anthony A

    2017-06-01

    A 55-year-old male with a history of two prior cardiac surgeries presented with decompensated heart failure due to severe bioprosthetic aortic valve insufficiency. A third operation was viewed prohibitively high risk and valve-in-valve trans-catheter aortic valve replacement was considered. There were however several high-risk features and technically challenging aspects including low coronary ostia height, poor visualization of the aortic sinuses, and difficulty in identification of the coplanar view due to severe aortic insufficiency, and a highly mobile aortic valve mass. After meticulous peri-procedural planning, trans-catheter aortic valve replacement was carried out with a SAPIEN 3 balloon-expandable valve without any complication. Strategies undertaken to navigate the technically challenging aspects of the case are discussed.

  14. Aortic valve surgery - minimally invasive

    MedlinePlus

    ... There are two main types of new valves: Mechanical, made of man-made materials, such as titanium ... Mechanical heart valves do not fail often. However, blood clots can develop on them. If a blood ...

  15. Transcatheter Aortic Valve Replacement for Native Aortic Valve Regurgitation

    PubMed Central

    Spina, Roberto; Anthony, Chris; Muller, David WM

    2015-01-01

    Transcatheter aortic valve replacement with either the balloon-expandable Edwards SAPIEN XT valve, or the self-expandable CoreValve prosthesis has become the established therapeutic modality for severe aortic valve stenosis in patients who are not deemed suitable for surgical intervention due to excessively high operative risk. Native aortic valve regurgitation, defined as primary aortic incompetence not associated with aortic stenosis or failed valve replacement, on the other hand, is still considered a relative contraindication for transcatheter aortic valve therapies, because of the absence of annular or leaflet calcification required for secure anchoring of the transcatheter heart valve. In addition, severe aortic regurgitation often coexists with aortic root or ascending aorta dilatation, the treatment of which mandates operative intervention. For these reasons, transcatheter aortic valve replacement has been only sporadically used to treat pure aortic incompetence, typically on a compassionate basis and in surgically inoperable patients. More recently, however, transcatheter aortic valve replacement for native aortic valve regurgitation has been trialled with newer-generation heart valves, with encouraging results, and new ancillary devices have emerged that are designed to stabilize the annulus–root complex. In this paper we review the clinical context, technical characteristics and outcomes associated with transcatheter treatment of native aortic valve regurgitation. PMID:29588674

  16. Bioprosthetic Valve Fracture During Valve-in-valve TAVR: Bench to Bedside

    PubMed Central

    Saxon, John T; Allen, Keith B; Cohen, David J

    2018-01-01

    Valve-in-valve (VIV) transcatheter aortic valve replacement (TAVR) has been established as a safe and effective means of treating failed surgical bioprosthetic valves (BPVs) in patients at high risk for complications related to reoperation. Patients who undergo VIV TAVR are at risk of patient–prosthesis mismatch, as the transcatheter heart valve (THV) is implanted within the ring of the existing BPV, limiting full expansion and reducing the maximum achievable effective orifice area of the THV. Importantly, patient–prosthesis mismatch and high residual transvalvular gradients are associated with reduced survival following VIV TAVR. Bioprosthetic valve fracture (BVF) is as a novel technique to address this problem. During BPV, a non-compliant valvuloplasty balloon is positioned within the BPV frame, and a highpressure balloon inflation is performed to fracture the surgical sewing ring of the BPV. This allows for further expansion of the BPV as well as the implanted THV, thus increasing the maximum effective orifice area that can be achieved after VIV TAVR. This review focuses on the current evidence base for BVF to facilitate VIV TAVR, including initial bench testing, procedural technique, clinical experience and future directions. PMID:29593832

  17. Bioprosthetic Valve Fracture During Valve-in-valve TAVR: Bench to Bedside.

    PubMed

    Saxon, John T; Allen, Keith B; Cohen, David J; Chhatriwalla, Adnan K

    2018-01-01

    Valve-in-valve (VIV) transcatheter aortic valve replacement (TAVR) has been established as a safe and effective means of treating failed surgical bioprosthetic valves (BPVs) in patients at high risk for complications related to reoperation. Patients who undergo VIV TAVR are at risk of patient-prosthesis mismatch, as the transcatheter heart valve (THV) is implanted within the ring of the existing BPV, limiting full expansion and reducing the maximum achievable effective orifice area of the THV. Importantly, patient-prosthesis mismatch and high residual transvalvular gradients are associated with reduced survival following VIV TAVR. Bioprosthetic valve fracture (BVF) is as a novel technique to address this problem. During BPV, a non-compliant valvuloplasty balloon is positioned within the BPV frame, and a highpressure balloon inflation is performed to fracture the surgical sewing ring of the BPV. This allows for further expansion of the BPV as well as the implanted THV, thus increasing the maximum effective orifice area that can be achieved after VIV TAVR. This review focuses on the current evidence base for BVF to facilitate VIV TAVR, including initial bench testing, procedural technique, clinical experience and future directions.

  18. Fast acting check valve

    NASA Technical Reports Server (NTRS)

    Perkins, Gerald S. (Inventor)

    1979-01-01

    A check valve which closes more rapidly to prevent wearing of the valve seat and of the valve member that seals thereagainst, including a solenoid or other actuator that aids the normal spring to quickly close the valve at approximately the time when downpath fluid flow would stop, the actuator then being deenergized. The control circuit that operates the actuator can include a pair of pressure sensors sensing pressure both upstream and downstream from the valve seat. Where the valve is utilized to control flow to or from a piston pump, energization of the actuator can be controlled by sensing when the pump piston reaches its extreme of travel.

  19. Automatic protective vent has fail-safe feature

    NASA Technical Reports Server (NTRS)

    Dameron, C. E.

    1966-01-01

    Delayed vent valve system in a mechanical backing pump in a vacuum system allows the pneumatic foreline valve to seal before the pump vent opens. The system is designed to be fail-safe and operate even though there is loss of electrical power.

  20. Magnetic Check Valve

    NASA Technical Reports Server (NTRS)

    Morris, Brian G.; Bozeman, Richard J., Jr.

    1994-01-01

    Poppet in proposed check valve restored to closed condition by magnetic attraction instead of spring force. Oscillations suppressed, with consequent reduction of wear. Stationary magnetic disk mounted just upstream of poppet, also containing magnet. Valve body nonmagnetic. Forward pressure or flow would push poppet away from stationary magnetic disk so fluid flows easily around poppet. Stop in valve body prevents poppet from being swept away. When flow stopped or started to reverse, magnetic attraction draws poppet back to disk. Poppet then engages floating O-ring, thereby closing valve and preventing reverse flow. Floating O-ring facilitates sealing at low loads.

  1. Alterations of valve closing behavior in juvenile Catarina scallops (Argopecten ventricosus Sowerby, 1842) exposed to toxic metals.

    PubMed

    Sobrino-Figueroa, A; Cáceres-Martínez, C

    2009-11-01

    We conducted an evaluation of alterations produced in the valve closing speed of juvenile Argopecten ventricosus (Catarina scallop) exposed to the metals cadmium, chromium and lead, because of the connection of this response to the state of health of the mollusk. Bioassays were conducted with 50 juveniles (length 3 +/- 0.5 cm) exposed to 0.02, 0.1, 0.2 mg Cd l(-1); 0.1, 0.5, 1.0 mg Cr l(-1); 0.04, 0.2, 0.4 mg Pb l(-1) and 0.8 and 1.6 mg Cd + Cr + Pb l(-1) for 480 h. The average valve closing speed at the end of the experiment was under 1 s in the control group, from 2 to 3.6 s in the bioassays with cadmium, from 1.4 to 3.4 s with chromium, from 3 to 12 s with lead, and from 12 to 15 s with the metal mixtures. It was found that there are significant differences between the values recorded in assays with metals and the control (P < 0.05). The retardation of valve closing in the organisms exposed to toxic substances is probably caused by damage to the sensory cilia located on the edge of the mantle.

  2. Histopathologic and immunohistochemical features of capsular tissue around failed Ahmed glaucoma valves.

    PubMed

    Mahale, Alka; Fikri, Fatma; Al Hati, Khitam; Al Shahwan, Sami; Al Jadaan, Ibrahim; Al Katan, Hind; Khandekar, Rajiv; Maktabi, Azza; Edward, Deepak P

    2017-01-01

    Impervious encapsulation around Ahmed glaucoma valve (AGV) results in surgical failure raising intraocular pressure (IOP). Dysregulation of extracellular matrix (ECM) molecules and cellular factors might contribute to increased hydraulic resistance to aqueous drainage. Therefore, we examined these molecules in failed AGV capsular tissue. Immunostaining for ECM molecules (collagen I, collagen III, decorin, lumican, chondroitin sulfate, aggrecan and keratan sulfate) and cellular factors (αSMA and TGFβ) was performed on excised capsules from failed AGVs and control tenon's tissue. Staining intensity of ECM molecules was assessed using Image J. Cellular factors were assessed based on positive cell counts. Histopathologically two distinct layers were visible in capsules. The inner layer (proximal to the AGV) showed significant decrease in most ECM molecules compared to outer layer. Furthermore, collagen III (p = 0.004), decorin (p = 0.02), lumican (p = 0.01) and chondroitin sulfate (p = 0.02) was significantly less in inner layer compared to tenon's tissue. Outer layer labelling however was similar to control tenon's for most ECM molecules. Significantly increased cellular expression of αSMA (p = 0.02) and TGFβ (p = 0.008) was detected within capsular tissue compared to controls. Our results suggest profibrotic activity indicated by increased αSMA and TGFβ expression and decreased expression of proteoglycan (decorin and lumican) and glycosaminoglycans (chondroitin sulfate). Additionally, we observed decreased collagen III which might reflect increased myofibroblast contractility when coupled with increased TGFβ and αSMA expression. Together these events lead to tissue dysfunction potentially resulting in hydraulic resistance that may affect aqueous flow through the capsular wall.

  3. Heart Valve Diseases

    MedlinePlus

    Your heart has four valves. Normally, these valves open to let blood flow through or out of your heart, and then shut to keep it from flowing ... close tightly. It's one of the most common heart valve conditions. Sometimes it causes regurgitation. Stenosis - when ...

  4. Excisional Bleb Revision for Management of Failed Ahmed Glaucoma Valve.

    PubMed

    Eslami, Yadollah; Fakhraie, Ghasem; Moghimi, Sasan; Zarei, Reza; Mohammadi, Masoud; Nabavi, Amin; Yaseri, Mehdi; Izadi, Ali

    2017-12-01

    To evaluate the outcome of excisonal bleb revision in patients with failed Ahmed glaucoma valve (AGV). In total, 29 patients with uncontrolled intraocular pressure (IOP) despite of maximal tolerated medical therapy at least 6 months after AGV implantation were enrolled in this prospective interventional case series. Excision of fibrotic tissue around the reservoir with application of mitomycin C 0.02% was performed. IOP, number of glaucoma medications were evaluated at baseline and 1 week and 1, 3, 6, and 12 months postoperatively. Complete and qualified success was defined as IOP≤21 mm Hg with or without glaucoma medications, respectively. Intraoperative and postopervative complications were also recorded. Mean IOP was reduced from 30±4.2 mm Hg at baseline to 19.2±3.1 mm Hg at 12-month follow-up visit (P<0.001). Average number of glaucoma medications was decrease from 3.2±0.5 at baseline to 1.9±0.7 at 12-month follow-up (P<0.001). Qualified and complete success rates at 12-month follow-up were 65.5% and 6.9%, respectively. Younger age and higher number of previous glaucoma surgeries were significantly associated with the failure of excisonal bleb revision. Excisional bleb revision could be considered as a relatively effective alternative option for management of inadequate IOP control after AGV implantation.

  5. Concomitant Transapical Transcatheter Valve Implantations: Edwards Sapien Valve for Severe Mitral Regurgitation in a Patient with Failing Mitral Bioprostheses and JenaValve for the Treatment of Pure Aortic Regurgitation.

    PubMed

    Aydin, Unal; Gul, Mehmet; Aslan, Serkan; Akkaya, Emre; Yildirim, Aydin

    2015-04-28

    Transcatheter valve implantation is a novel interventional technique, which was developed as an  alternative therapy for surgical aortic valve replacement in inoperable patients with severe aortic stenosis. Despite limited experience in using transcatheter valve implantation for mitral and aortic regurgitation, transapical transcatheter aortic valve implantation and valve-in-valve implantation for degenerated mitral valve bioprosthesis can be performed in high-risk patients who are not candidates for conventional replacement surgery. In this case, we present the simultaneous transcatheter valve implantation via transapical approach for both degenerated bioprosthetic mitral valve with severe regurgitation and pure severe aortic regurgitation.

  6. Latching Solenoid-Operated Ball Valve

    NASA Technical Reports Server (NTRS)

    Brudnicki, Myron

    1994-01-01

    Proposed solenoid-operated ball valve latches in open or closed position until energized to change position. Electrical energy consumed only during opening or closing motion. Valve ball contains central channel through which fluid could flow. Made of highly magnetically permeable steel. When appropriate coil(s) energized by brief pulse (or pulses) of electrical current at appropriate polarity, ball rotates clockwise until permanent magnets come to rest against hard stops in housing, and inlet and outlet ports aligned with central channel so fluid flows through valve. Magnets adhere to stops by magnetic attraction, latching valve in open position. To close valve, appropriate coil(s) energized by pulse (or pulses) of appropriate polarity to generate magnetic forces rotating ball counterclockwise until magnets make contact with hard stops, and inlet and outlet ports sealed.

  7. Excess flow shutoff valve

    DOEpatents

    Kiffer, Micah S.; Tentarelli, Stephen Clyde

    2016-02-09

    Excess flow shutoff valve comprising a valve body, a valve plug, a partition, and an activation component where the valve plug, the partition, and activation component are disposed within the valve body. A suitable flow restriction is provided to create a pressure difference between the upstream end of the valve plug and the downstream end of the valve plug when fluid flows through the valve body. The pressure difference exceeds a target pressure difference needed to activate the activation component when fluid flow through the valve body is higher than a desired rate, and thereby closes the valve.

  8. A simple fast pulse gas valve using a dynamic pressure differential as the primary closing mechanism

    NASA Astrophysics Data System (ADS)

    Thomas, J. C.; Hwang, D. Q.; Horton, R. D.; Rogers, J. H.; Raman, R.

    1993-06-01

    In this article we describe a simple fast pulse gas valve developed for use in a plasma discharge experiment. The valve delivers 1017-1019 molecules per pulse varied by changing the voltage on the electromagnetic driver power supply. Valve pulse widths are observed to be less than 300 μs full width at half maximum with a rise time of less than 100 μs resulting in a maximum gas flow rate of ˜1022 molecules per second. An optical transmission technique was used to determine the mechanical opening and closing characteristics of the valve piston. A fast ionization gauge (FIG) was used for diagnosis of the temporal character of the gas pulse while the total gas throughput was determined by measuring the change in pressure per pulse in a small test chamber with a convectron tube gauge. Calibration of the FIG was accomplished by comparing the net change in pressure in a large chamber as measured by the FIG to the net change in pressure in a small test chamber as measured by the convectron tube gauge.

  9. Dual-latching solenoid-actuated valve assembly

    NASA Technical Reports Server (NTRS)

    Brudnicki, Myron J. (Inventor); Yang, Jeff (Inventor)

    1994-01-01

    A tube-type shutoff valve is electrically positioned to its open or closed position by a concentric electromagnetic solenoid. The valve is dual latching in that the armature of the solenoid maintains the sliding tube of the valve in an open or closed position by means of permanent magnets which are effective when current is not supplied to the solenoid. The valve may also be actuated manually.

  10. Downhole surge valve for earth boring apparatus

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lee, D.W.

    1990-05-29

    This patent describes a boring tool assembly having an underground percussion mole boring tool powered by a working fluid, the tool being driven through the earth by a rigid drill string pushed by a drilling frame, and a downhole valve assembly fixed between the downhole end of the drill string and the too, the improved downhole valve assembly. It comprises: a valve spool having an open first end, a closed second end and a peripheral sidewall, an axial bore extending partly through the valve spool from the open first end; a radial passage adjacent the closed second and of themore » valve spool, the radial passage extending radially from the valve spool axial bore through the valve spool peripheral sidewall; an axial groove in the peripheral sidewall of the valve spool; a valve body having a first end, a second end and a peripheral sidewall, an axial bore extending through the valve body, the valve spool extending through the valve body axial bore so that the second end of the valve body is adjacent the closed second end of the valve spool, the valve spool being axially moveable within the valve body axial bore; an axial slot; a free-floating key element; a valve housing; and seal means.« less

  11. Stemless Ball Valve

    NASA Technical Reports Server (NTRS)

    Burgess, Robert K.; Yakos, David; Walthall, Bryan

    2012-01-01

    This invention utilizes a new method of opening and closing a ball valve. Instead of rotating the ball with a perpendicular stem (as is the case with standard ball valves), the ball is rotated around a fixed axis by two guide pins. This innovation eliminates the leak point that is present in all standard ball valves due to the penetration of an actuation stem through the valve body. The VOST (Venturi Off-Set-Technology) valve has been developed for commercial applications. The standard version of the valve consists of an off-set venturi flow path through the valve. This path is split at the narrowest portion of the venturi, allowing the section upstream from the venturi to be rotated. As this rotation takes place, the venturi becomes restricted as one face rotates with respect to the other, eventually closing off the flow path. A spring-loaded seal made of resilient material is embedded in the upstream face of the valve, making a leak-proof seal between the faces; thus a valve is formed. The spring-loaded lip seal is the only seal that can provide a class six, or bubble-tight, seal against the opposite face of the valve. Tearing action of the seal by high-velocity gas on this early design required relocation of the seal to the downstream face of the valve. In the stemless embodiment of this valve, inner and outer magnetic cartridges are employed to transfer mechanical torque from the outside of the valve to the inside without the use of a stem. This eliminates the leak path caused by the valve stems in standard valves because the stems penetrate through the bodies of these valves.

  12. Quickly Removable Valve

    NASA Technical Reports Server (NTRS)

    Robbins, John S.

    1988-01-01

    Unit removed with minimal disturbance. Valve inlet and outlet ports adjacent to each other on same side of valve body. Ports inserted into special manifold on fluid line. Valve body attached to manifold by four bolts or, alternatively, by toggle clamps. Electromechanical actuator moves in direction parallel to fluid line to open and close valve. When necessary to clean valve, removed simply by opening bolts or toggle clamps. No need to move or separate ports of fluid line. Valve useful where disturbance of fluid line detrimental or where fast maintenance essential - in oil and chemical industries, automotive vehicles, aircraft, and powerplants.

  13. Aerodynamic Shutoff Valve

    NASA Technical Reports Server (NTRS)

    Horstman, Raymond H.

    1992-01-01

    Aerodynamic flow achieved by adding fixed fairings to butterfly valve. When valve fully open, fairings align with butterfly and reduce wake. Butterfly free to turn, so valve can be closed, while fairings remain fixed. Design reduces turbulence in flow of air in internal suction system. Valve aids in development of improved porous-surface boundary-layer control system to reduce aerodynamic drag. Applications primarily aerospace. System adapted to boundary-layer control on high-speed land vehicles.

  14. Cryogenic Cam Butterfly Valve

    NASA Technical Reports Server (NTRS)

    McCormack, Kenneth J. (Inventor)

    2016-01-01

    A cryogenic cam butterfly valve has a body that includes an axially extending fluid conduit formed there through. A disc lug is connected to a back side of a valve disc and has a circular bore that receives and is larger than a cam of a cam shaft. The valve disc is rotatable for a quarter turn within the body about a lug axis that is offset from the shaft axis. Actuating the cam shaft in the closing rotational direction first causes the camming side of the cam of the cam shaft to rotate the disc lug and the valve disc a quarter turn from the open position to the closed position. Further actuating causes the camming side of the cam shaft to translate the valve disc into sealed contact with the valve seat. Opening rotational direction of the cam shaft reverses these motions.

  15. Heart valve surgery

    MedlinePlus

    ... with an artificial valve (this is called the Ross Procedure). This procedure may be useful for people ... valve that does not close all the way will allow blood to leak backwards. This is called ...

  16. Survival Prediction in Patients Undergoing Open-Heart Mitral Valve Operation After Previous Failed MitraClip Procedures.

    PubMed

    Geidel, Stephan; Wohlmuth, Peter; Schmoeckel, Michael

    2016-03-01

    The objective of this study was to analyze the results of open heart mitral valve operations for survival prediction in patients with previously unsuccessful MitraClip procedures. Thirty-three consecutive patients who underwent mitral valve surgery in our institution were studied. At a median of 41 days, they had previously undergone one to five futile MitraClip implantations. At the time of their operations, patients were 72.6 ± 10.3 years old, and the calculated risk, using the European System for Cardiac Operative Risk Evaluation (EuroSCORE) II, was a median of 26.5%. Individual outcomes were recorded, and all patients were monitored postoperatively. Thirty-day mortality was 9.1%, and the overall survival at 2.2 years was 60.6%. Seven cardiac-related and six noncardiac deaths occurred. Univariate survival regression models demonstrated a significant influence of the following variables on survival: EuroSCORE II (p = 0.0022), preoperative left ventricular end-diastolic dimension (p = 0.0052), left ventricular ejection fraction (p = 0.0249), coronary artery disease (p = 0.0385), and severe pulmonary hypertension (p = 0.0431). Survivors showed considerable improvements in their New York Heart Association class (p < 0.0001), left ventricular ejection fraction (p = 0.0080), grade of mitral regurgitation (p = 0.0350), and mitral valve area (p = 0.0486). Survival after mitral repair was not superior to survival after replacement. Indications for surgery after failed MitraClip procedures must be considered with the greatest of care. Variables predicting postoperative survival should be taken into account regarding the difficult decision as to whether to operate or not. Our data suggest that replacement of the pretreated mitral valve is probably the more reasonable concept rather than complex repairs. When the EuroSCORE II at the time of surgery exceeds 30%, conservative therapy is advisable. Copyright © 2016 The Society of Thoracic Surgeons. Published by Elsevier Inc

  17. Dual-Latching, Solenoid-Actuated Tube Valve

    NASA Technical Reports Server (NTRS)

    Brudnicki, Myron J.

    1993-01-01

    Tube-type shutoff valve electrically positioned to open or closed state by concentric solenoid. Solenoid dual latching: it holds position until changed electrically or manually. In tube valve, central tube slides axially, closing off flow when held against seat and allowing flow when backed away from seat. Simple to balance pressure on seal between seat and sharp edge of tube. With pressure-balanced seal, only small force needed to hold valve in position, regardless of pressure acting on valve.

  18. Solenoid valve performance characteristics studied

    NASA Technical Reports Server (NTRS)

    Abe, J. T.; Blackburn, S.

    1970-01-01

    Current and voltage waveforms of a solenoid coil are recorded as the valve opens and closes. Analysis of the waveforms with respect to time and the phase of the valve cycle accurately describes valve performance.

  19. Valve and dash-pot assembly

    DOEpatents

    Chang, Shih-Chih

    1986-01-01

    A dash-pot valve comprising a cylinder submerged in the fluid of a housing and having a piston attached to a plunger projecting into the path of closing movement of a pivotal valve member. A vortex chamber in said cylinder is provided with tangentially directed inlets to generate vortex flow upon retraction of said plunger and effect increasing resistance against said piston to progressively retard the closing rate of said valve member toward its seat.

  20. Engine including hydraulically actuated valvetrain and method of valve overlap control

    DOEpatents

    Cowgill, Joel [White Lake, MI

    2012-05-08

    An exhaust valve control method may include displacing an exhaust valve in communication with the combustion chamber of an engine to an open position using a hydraulic exhaust valve actuation system and returning the exhaust valve to a closed position using the hydraulic exhaust valve actuation assembly. During closing, the exhaust valve may be displaced for a first duration from the open position to an intermediate closing position at a first velocity by operating the hydraulic exhaust valve actuation assembly in a first mode. The exhaust valve may be displaced for a second duration greater than the first duration from the intermediate closing position to a fully closed position at a second velocity at least eighty percent less than the first velocity by operating the hydraulic exhaust valve actuation assembly in a second mode.

  1. Microfluidic Valves Made From Polymerized Polyethylene Glycol Diacrylate

    PubMed Central

    Rogers, Chad I.; Oxborrow, Joseph B.; Anderson, Ryan R.; Tsai, Long-Fang; Nordin, Gregory P.; Woolley, Adam T.

    2013-01-01

    Pneumatically actuated, non-elastomeric membrane valves fabricated from polymerized polyethylene glycol diacrylate (poly-PEGDA) have been characterized for temporal response, valve closure, and long-term durability. A ~100 ms valve opening time and a ~20 ms closure time offer valve operation as fast as 8 Hz with potential for further improvement. Comparison of circular and rectangular valve geometries indicates that the surface area for membrane interaction in the valve region is important for valve performance. After initial fabrication, the fluid pressure required to open a closed circular valve is ~50 kPa higher than the control pressure holding the valve closed. However, after ~1000 actuations to reconfigure polymer chains and increase elasticity in the membrane, the fluid pressure required to open a valve becomes the same as the control pressure holding the valve closed. After these initial conditioning actuations, poly-PEGDA valves show considerable robustness with no change in effective operation after 115,000 actuations. Such valves constructed from non-adsorptive poly-PEGDA could also find use as pumps, for application in small volume assays interfaced with biosensors or impedance detection, for example. PMID:24357897

  2. Valve for gas centrifuges

    DOEpatents

    Hahs, Charles A.; Burbage, Charles H.

    1984-01-01

    The invention is a pneumatically operated valve assembly for simultaneously (1) closing gas-transfer lines connected to a gas centrifuge or the like and (2) establishing a recycle path between two of the lines so closed. The valve assembly is especially designed to be compact, fast-acting, reliable, and comparatively inexpensive. It provides large reductions in capital costs for gas-centrifuge cascades.

  3. Electro-Mechanical Coaxial Valve

    NASA Technical Reports Server (NTRS)

    Patterson, Paul R (Inventor)

    2004-01-01

    Coaxial valves usually contain only one moving part. It has not been easy, then, to provide for electric motor actuation. Many actuators being proposed involve designs which lead to bulky packages. The key facing those improving coaxial valves is the provision of suitable linear actuation. The valve herein indudes a valve housing with a flow channel there-through. Arranged in the flow channel is a closing body. In alignment with the closing body is a ball screw actuator which includes a ball nut and a cylindrical screw. The ball nut sounds a threaded portion of the cylindrical screw. The cylindrical screw is provided with a passageway there-through through which fluid flows. The cylindrical screw is disposed in the flow channel to become a control tube adapted to move toward and away from the valve seat. To rotate the ball nut an actuating drive is employed driven by a stepper motor.

  4. Fault Study of Valve Based on Test Analysis and Comparison

    NASA Astrophysics Data System (ADS)

    Cheng, Li; Yang, Wukui; Liang, Tao; Xu, Yu; Chen, Chao

    2017-10-01

    The valve of a certain type of small engine often has the fault phenomenon of abnormal vibration noise and can’t close under the specified pressure, which may cause the engine automatic stop because of valve incomplete close leading to fuel leakage during test and startup on the bench. By test study compared to imported valve with the same use function and test condition valve, and put forward the thinking of improving valve structure, compared no-improved valve to improved valve by adopting Fluent field simulation software. As a result, improved valve can restore close pressure of valve, restrain abnormal vibration noise phenomenon, and effectively compensate compression value of spring because of steel ball contacting position downward with valve casing.

  5. Microblower assisted barometric valve

    DOEpatents

    Rossabi, Joseph; Hyde, Warren K.; Riha, Brian D.; Jackson, Dennis G.; Sappington, Frank

    2005-12-06

    A gas exchange apparatus is provided which provides for both passive fluid flow and blower associated fluid flow through a barometric valve. A battery powered blower is provided which allows for operation of the barometric valve during times when the barometric valve would otherwise be closed, and provides for enhanced volume of gas exchange.

  6. FLUID PRESSURE AND CAM OPERATED VACUUM VALVE

    DOEpatents

    Batzer, T.H.

    1963-11-26

    An ultra-high vacuum valve that is bakable, reusable, and capable of being quickly opened and closed is described. A translationally movable valve gate having an annular ridge is adapted to contact an annular soft metal gasket disposed at the valve seat such that the soft metal gasket extends beyond the annular ridge on all sides. The valve gate is closed, by first laterally aligning the valve gate with the valve seat and then bringing the valve gate and valve seat into seating contact by the translational movement of a ramp-like wedging means that engages similar ramp-like stractures at the base of the valve gate to force the valve gate into essentially pressureless contact with the annular soft metal gasket. This gasket is then pressurized from beneath by a fluid thereby effecting a vacuura tight seal between the gasket and the ridge. (AEC)

  7. Problem: Heart Valve Regurgitation

    MedlinePlus

    ... should be completely closed For example: Watch an animation of mitral valve regurgitation A leaking mitral valve ... Not Alone Popular Articles 1 Understanding Blood Pressure Readings 2 Sodium and Salt 3 Heart Attack Symptoms ...

  8. BAKABLE ULTRA-HIGH VACUUM VALVE

    DOEpatents

    Mark, J.T.; Gantz, I.H.

    1962-07-10

    S>This patent relates to a valve useful in applications involving successively closing and opening a communication between a chamber evacuated to an ultra-high vacuum condition of the order of 10/sup -10/ millimeters of mercury and another chamber or the ambient. The valve is capable of withstanding extended baking at 450 deg C and repeated opening and closing without repiacement of the valve seat (approximately 200 cycle limit). The seal is formed by mutual interdiffusion weld, coerced by a pneumatic actuator. (AEC)

  9. Main Oxidizer Valve Design

    NASA Technical Reports Server (NTRS)

    Addona, Brad; Eddleman, David

    2015-01-01

    A developmental Main Oxidizer Valve (MOV) was designed by NASA-MSFC using additive manufacturing processes. The MOV is a pneumatically actuated poppet valve to control the flow of liquid oxygen to an engine's injector. A compression spring is used to return the valve to the closed state when pneumatic pressure is removed from the valve. The valve internal parts are cylindrical in shape, which lends itself to traditional lathe and milling operations. However, the valve body represents a complicated shape and contains the majority of the mass of the valve. Additive manufacturing techniques were used to produce a part that optimized mass and allowed for design features not practical with traditional machining processes.

  10. Analytical solution and numerical study on water hammer in a pipeline closed with an elastically attached valve

    NASA Astrophysics Data System (ADS)

    Henclik, Sławomir

    2018-03-01

    The influence of dynamic fluid-structure interaction (FSI) onto the course of water hammer (WH) can be significant in non-rigid pipeline systems. The essence of this effect is the dynamic transfer of liquid energy to the pipeline structure and back, which is important for elastic structures and can be negligible for rigid ones. In the paper a special model of such behavior is analyzed. A straight pipeline with a steady flow, fixed to the floor with several rigid supports is assumed. The transient is generated by a quickly closed valve installed at the end of the pipeline. FSI effects are assumed to be present mainly at the valve which is fixed with a spring dash-pot attachment. Analysis of WH runs, especially transient pressure changes, for various stiffness and damping parameters of the spring dash-pot valve attachment is presented in the paper. The solutions are found analytically and numerically. Numerical results have been computed with the use of an own computer program developed on the basis of the four equation model of WH-FSI and the specific boundary conditions formulated at the valve. Analytical solutions have been found with the separation of variables method for slightly simplified assumptions. Damping at the dash-pot is taken into account within the numerical study. The influence of valve attachment parameters onto the WH courses was discovered and it was found the transient amplitudes can be reduced. Such a system, elastically attached shut-off valve in a pipeline or other, equivalent design can be a real solution applicable in practice.

  11. Water hammer caused by closure of turbine safety spherical valves

    NASA Astrophysics Data System (ADS)

    Karadžić, U.; Bergant, A.; Vukoslavčević, P.

    2010-08-01

    This paper investigates water hammer effects caused by closure of spherical valves against the discharge. During the first phase of modernisation of Perućica high-head hydropower plant (HPP), Montenegro, safety spherical valves (inlet turbine valves) have been refurbished on the first two Pelton turbine units. The valve closure is controlled by the valve actuator (hydraulic servomotor). Because the torque acting on the valve body is dependent on flow conditions the valve closing time may vary significantly for different flow velocities (passive valve). For the passive valve the torques acting on the valve body should be considered in the valve model. The valve closing time results from numerical simulation. On the contrary, for the active valve the valve closing time is assumed prior to simulation. The spherical valve boundary condition is incorporated into the method of characteristics (MOC) algorithm. The staggered (diamond) grid in applying the MOC is used in this paper. The passive valve boundary condition is described by the water hammer equations, the valve equation that relates discharge to pressure head drop and the dynamic equation of the valve body motion (torque equation). The active valve boundary condition is described by the first two equations, respectively. Standard quasi-steady friction model is used for estimating friction losses in plant's tunnel and penstocks. Numerical results using both the active and the passive spherical valve models are compared with results of measurements. It has been found that the influence of flow conditions on the spherical valve closing time is minor for the cases considered. Computed and measured results agree reasonably well.

  12. 46 CFR 108.444 - Lockout valves.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... dioxide to discharge in the event of equipment failure during maintenance. (c) The lockout valve design or... extinguishing system, when the valve must be locked in the closed position. (f) Lockout valves added to existing...

  13. Improved valve and dash-pot assembly

    DOEpatents

    Chang, S.C.

    1985-04-23

    A dash-pot valve comprises a cylinder submerged in the fluid of a housing and have a piston attached to a plunger projecting into the path of closing movement of a pivotal valve member. A vortex chamber in said cylinder is provided with targentially directed inlets to generate vortex flow upon retraction of said plunger and effect increasing resistance against said piston to progressively retard the closing rate of said valve member toward its seat.

  14. Valve for controlling solids flow

    DOEpatents

    Feldman, David K.

    1980-01-01

    A fluidized solids control valve is disclosed that is particularly well adapted for use with a flow of coal or char that includes both large particles and fines. The particles may or may not be fluidized at various times during the operation. The valve includes a tubular body that terminates in a valve seat covered by a normally closed closure plate. The valve body at the seat and the closure plate is provided with aligned longitudinal slots that receive a pivotally supported key plate. The key plate is positionable by an operator in inserted, intermediate and retracted positions respecting the longitudinal slot in the valve body. The key plate normally closes the slot within the closure plate but is shaped and aligned obliquely to the longitudinal slot within the valve body to provide progressively increasing slot openings between the inserted and retracted positions. Transfer members are provided between the operator, key plate and closure plate to move the closure plate into an open position only when the key plate is retracted from the longitudinal slot within the valve body.

  15. Remotely operated high pressure valve protects test personnel

    NASA Technical Reports Server (NTRS)

    Howland, B. T.

    1967-01-01

    High pressure valve used in testing certain spacecraft systems is safely opened and closed by a remotely stationed operator. The valve is self-regulating in that if the incoming pressure drops below a desired value the valve will automatically close, warning the operator that the testing pressure has dropped to an undesired level.

  16. Developmental testing resulting in a simplified liquid oxygen check valve for the Space Shuttle Main Propulsion System

    NASA Technical Reports Server (NTRS)

    Aber, Gregory S.; Barrett, Michael J.; Reith, Timothy W.

    1993-01-01

    The coil spring in a Space Shuttle liquid oxygen check valve failed due to cyclic fatigue in September, 1991. The dual-flapper, swing check valve is used to prevent reverse flow to the Space Shuttle Main Engines. Upon inspection of the failed component, the spring tangs were found to be missing and heavy wear was observed on the inner diameter of the spring coils. The fracture surfaces revealed that the metal had been steadily worn away until a simple overload caused the final fracture. A series of flow tests using water and a water/gas mixture was conducted to identify the flow phenomenon which produced the cyclic wear. A Plexiglas outlet housing was utilized to view the flapper behavior under different flow conditions and to aid in high speed photography. The tests revealed that flow instabilities induced two oscillatory flapper responses: a rocking mode and a chattering mode. Initially, attempts were made to reduce the spring-flapper oscillations. However, the final solution to the problem was a springless configuration which satisfied the valve's design requirements and eliminated the oscillations. The springless design relied on the inherent ability of the reverse flow momentum to close the flappers.

  17. 14 CFR 125.137 - Oil valves.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Oil valves. 125.137 Section 125.137....137 Oil valves. (a) Each oil valve must— (1) Comply with § 125.155; (2) Have positive stops or... the valve. (b) The closing of an oil shutoff means must not prevent feathering the propeller, unless...

  18. 14 CFR 125.137 - Oil valves.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Oil valves. 125.137 Section 125.137....137 Oil valves. (a) Each oil valve must— (1) Comply with § 125.155; (2) Have positive stops or... the valve. (b) The closing of an oil shutoff means must not prevent feathering the propeller, unless...

  19. 14 CFR 125.137 - Oil valves.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Oil valves. 125.137 Section 125.137....137 Oil valves. (a) Each oil valve must— (1) Comply with § 125.155; (2) Have positive stops or... the valve. (b) The closing of an oil shutoff means must not prevent feathering the propeller, unless...

  20. 14 CFR 125.137 - Oil valves.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false Oil valves. 125.137 Section 125.137....137 Oil valves. (a) Each oil valve must— (1) Comply with § 125.155; (2) Have positive stops or... the valve. (b) The closing of an oil shutoff means must not prevent feathering the propeller, unless...

  1. 14 CFR 125.137 - Oil valves.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Oil valves. 125.137 Section 125.137....137 Oil valves. (a) Each oil valve must— (1) Comply with § 125.155; (2) Have positive stops or... the valve. (b) The closing of an oil shutoff means must not prevent feathering the propeller, unless...

  2. Programming jammed Codman Hakim programmable valves: study of an explanted valve and successful programming in a patient.

    PubMed

    Wong, Sui-To; Wen, Eleanor; Fong, Dawson

    2013-08-01

    Malfunction of a Codman Hakim programmable valve due to jamming of its programmable component may necessitate shunt revision. The authors report a method for programming jammed Codman Hakim programmable valves by using a Strata II magnet and additional neodymium magnets. The programming method was derived after studying a jammed valve in the laboratory that was explanted from an 10-year-old boy with a history of fourth ventricle ependymoma. Programming the explanted valve with a Codman programmer failed, but rotating a Strata II magnet above the valve resulted in rotation of the spiral cam in the valve. It was found that the Strata II magnet could be used to program the jammed valve by rotating the magnet 90° or multiples of 90° above the valve. The strength of the magnetic field of the Strata II magnet was able to be increased by putting neodymium magnets on it. The programming method was then successfully used in a patient with a jammed Codman Hakim programmable valve. After successful programming using this method, clinical and radiological follow-up of the patient was advised.

  3. Sliding-gate valve

    DOEpatents

    Usnick, George B.; Ward, Gene T.; Blair, Henry O.; Roberts, James W.; Warner, Terry N.

    1979-01-01

    This invention is a novel valve of the slidable-gate type. The valve is designed especially for long-term use with highly abrasive slurries. The sealing surfaces of the gate are shielded by the valve seats when the valve is fully open or closed, and the gate-to-seat clearance is swept with an inflowing purge gas while the gate is in transit. A preferred form of the valve includes an annular valve body containing an annular seat assembly defining a flow channel. The seat assembly comprises a first seat ring which is slidably and sealably mounted in the body, and a second seat ring which is tightly fitted in the body. These rings cooperatively define an annular gap which, together with passages in the valve body, forms a guideway extending normal to the channel. A plate-type gate is mounted for reciprocation in the guideway between positions where a portion of the plate closes the channel and where a circular aperture in the gate is in register with the channel. The valve casing includes opposed chambers which extend outwardly from the body along the axis of the guideway to accommodate the end portions of the gate. The chambers are sealed from atmosphere; when the gate is in transit, purge gas is admitted to the chambers and flows inwardly through the gate-to-seat-ring, clearance, minimizing buildup of process solids therein. A shaft reciprocated by an external actuator extends into one of the sealed chambers through a shaft seal and is coupled to an end of the gate. Means are provided for adjusting the clearance between the first seat ring and the gate while the valve is in service.

  4. Hydraulic engine valve actuation system including independent feedback control

    DOEpatents

    Marriott, Craig D

    2013-06-04

    A hydraulic valve actuation assembly may include a housing, a piston, a supply control valve, a closing control valve, and an opening control valve. The housing may define a first fluid chamber, a second fluid chamber, and a third fluid chamber. The piston may be axially secured to an engine valve and located within the first, second and third fluid chambers. The supply control valve may control a hydraulic fluid supply to the piston. The closing control valve may be located between the supply control valve and the second fluid chamber and may control fluid flow from the second fluid chamber to the supply control valve. The opening control valve may be located between the supply control valve and the second fluid chamber and may control fluid flow from the supply control valve to the second fluid chamber.

  5. Three-dimensional echocardiographic evaluation of an incidental quadricuspid aortic valve.

    PubMed

    Armen, Todd A; Vandse, Rashmi; Bickle, Katherine; Nathan, Nadia

    2008-03-01

    Quadricuspid aortic valve is one of the rare forms of congenital cardiac valvular disease. Its diagnosis is often missed, even with the transthoracic echocardiogram. Many of these patients progress to aortic incompetence later in life requiring surgical intervention. In addition, quadricuspid aortic valve can be associated with other congenital cardiac deformities. Hence early recognition and follow-up is critical in these patients. We report a patient with quadricuspid aortic valve identified on intraoperative transesophageal 3-D echocardiography. This 66-year-old male presented with the features of congestive heart failure. The preoperative transthoracic echocardiogram (TTE) disclosed, moderately severe aortic valve insufficiency along with severe mitral and tricuspid regurgitation, but failed to reveal the quadricuspid anomaly of the aortic valve. Interestingly, this patient had undergone transthoracic echocardiography on two previous occasions during the past seven years for the evaluation of his valvular heart disease, which all failed to document this anomaly. Intraoperatively, transesophageal echocardiography (TEE) displayed an aortic valve composed of three medium and one small cusps. Our patient's case demonstrates the usefulness of transesophageal echocardiography in detection of this uncommon congenital malformation.

  6. Optimised collision avoidance for an ultra-close rendezvous with a failed satellite based on the Gauss pseudospectral method

    NASA Astrophysics Data System (ADS)

    Chu, Xiaoyu; Zhang, Jingrui; Lu, Shan; Zhang, Yao; Sun, Yue

    2016-11-01

    This paper presents a trajectory planning algorithm to optimise the collision avoidance of a chasing spacecraft operating in an ultra-close proximity to a failed satellite. The complex configuration and the tumbling motion of the failed satellite are considered. The two-spacecraft rendezvous dynamics are formulated based on the target body frame, and the collision avoidance constraints are detailed, particularly concerning the uncertainties. An optimisation solution of the approaching problem is generated using the Gauss pseudospectral method. A closed-loop control is used to track the optimised trajectory. Numerical results are provided to demonstrate the effectiveness of the proposed algorithms.

  7. Are anticoagulant independent mechanical valves within reach-fast prototype fabrication and in vitro testing of innovative bi-leaflet valve models.

    PubMed

    Scotten, Lawrence N; Siegel, Rolland

    2015-08-01

    Exploration for causes of prosthetic valve thrombogenicity has frequently focused on forward or post-closure flow detail. In prior laboratory studies, we uncovered high amplitude flow velocities of short duration close to valve closure implying potential for substantial shear stress with subsequent initiation of blood coagulation pathways. This may be relevant to widely accepted clinical disparity between mechanical and tissue valves vis-à-vis thrombogenicity. With a series of prototype bi-leaflet mechanical valves, we attempt reduction of closure related velocities with the objective of identifying a prototype valve with thrombogenic potential similar to our tissue valve control. This iterative design approach may find application in preclinical assessment of valves for anticoagulation independence. Tested valves included: prototype mechanical bi-leaflet BVs (n=56), controls (n=2) and patented early prototype mechanicals (n=2) from other investigators. Pulsatile and quasi-steady flow systems were used for testing. Projected dynamic valve area (PDVA) was measured using previously described novel technology. Flow velocity over the open and closing periods was determined by volumetric flow rate/PDVA. For the closed valve interval, use was made of data obtained from quasi-steady back pressure/flow tests. Performance was ranked by a proposed thrombogenicity potential index (TPI) relative to tissue and mechanical control valves. Optimization of the prototype valve designs lead to a 3-D printed model (BV3D). For the mitral/aortic site, BV3D has lower TPI (1.10/1.47) relative to the control mechanical valve (3.44/3.93) and similar to the control tissue valve (ideal TPI ≤1.0). Using unique technology, rapid prototyping and thrombogenicity ranking, optimization of experimental valves for reduced thrombogenic potential was expedited and simplified. Innovative mechanical valve configurations were identified that merit consideration for further development which may bring

  8. Are anticoagulant independent mechanical valves within reach—fast prototype fabrication and in vitro testing of innovative bi-leaflet valve models

    PubMed Central

    Siegel, Rolland

    2015-01-01

    Background Exploration for causes of prosthetic valve thrombogenicity has frequently focused on forward or post-closure flow detail. In prior laboratory studies, we uncovered high amplitude flow velocities of short duration close to valve closure implying potential for substantial shear stress with subsequent initiation of blood coagulation pathways. This may be relevant to widely accepted clinical disparity between mechanical and tissue valves vis-à-vis thrombogenicity. With a series of prototype bi-leaflet mechanical valves, we attempt reduction of closure related velocities with the objective of identifying a prototype valve with thrombogenic potential similar to our tissue valve control. This iterative design approach may find application in preclinical assessment of valves for anticoagulation independence. Methods Tested valves included: prototype mechanical bi-leaflet BVs (n=56), controls (n=2) and patented early prototype mechanicals (n=2) from other investigators. Pulsatile and quasi-steady flow systems were used for testing. Projected dynamic valve area (PDVA) was measured using previously described novel technology. Flow velocity over the open and closing periods was determined by volumetric flow rate/PDVA. For the closed valve interval, use was made of data obtained from quasi-steady back pressure/flow tests. Performance was ranked by a proposed thrombogenicity potential index (TPI) relative to tissue and mechanical control valves. Results Optimization of the prototype valve designs lead to a 3-D printed model (BV3D). For the mitral/aortic site, BV3D has lower TPI (1.10/1.47) relative to the control mechanical valve (3.44/3.93) and similar to the control tissue valve (ideal TPI ≤1.0). Conclusions Using unique technology, rapid prototyping and thrombogenicity ranking, optimization of experimental valves for reduced thrombogenic potential was expedited and simplified. Innovative mechanical valve configurations were identified that merit consideration

  9. TUBE SHEARING VALVE

    DOEpatents

    Wilner, L.B.

    1960-05-24

    Explosive operated valves can be used to join two or more containers in fluid flow relationship, one such container being a sealed reservoir. The valve is most simply disposed by mounting it on the reservoir so thst a tube extends from the interior of the reservoir through the valve body, terminating at the bottom of the bore in a closed end; other containers may be similarly connected or may be open connected, as desired. The piston of the valve has a cutting edge at its lower end which shears off the closed tube ends and a recess above the cutting edge to provide a flow channel. Intermixing of the fluid being transferred with the explosion gases is prevented by a copper ring at the top of the piston which is force fitted into the bore at the beginning of the stroke. Although designed to avoid backing up of the piston at pressures up to 10,000 psi in the transferred fluid, proper operation is independent of piston position, once the tube ends were sheared.

  10. 46 CFR 95.15-50 - Lockout valves.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... the event of equipment failure during maintenance. (c) The lockout valve design or locking mechanism..., when the valve must be locked in the closed position. (f) Lockout valves added to existing systems must...

  11. Apparatus comprising magnetically actuated valves and uses thereof

    DOEpatents

    Edwards, Thayne L.; Harper, Jason C.

    2016-07-12

    The present invention, in part, relates to an apparatus having a single-use, normally-closed fluidic valve that is initially maintained in the closed position by a valve element bonded to an adhesive coating. The valve is opened using a magnetic force. The valve element includes a magnetic material or metal. In some examples, the valve is opened by bringing a magnet in proximity to the valve element to provide a magnetic force that delaminates the valve element from the adhesive coating. In particular, the apparatus can be useful for on-chip amplification and/or detection of various targets, including biological targets and any amplifiable targets. Such apparatuses and methods are useful for in-field or real-time detection of targets, especially in limited resource settings.

  12. Design and development of a large diameter high pressure fast acting propulsion valve and valve actuator

    NASA Technical Reports Server (NTRS)

    Srinivasan, K. V.

    1986-01-01

    The design and development of a large diameter high pressure quick acting propulsion valve and valve actuator is described. The valve is the heart of a major test facility dedicated to conducting full scale performance tests of aircraft landing systems. The valve opens in less than 300 milliseconds releasing a 46-centimeter- (18-in.-) diameter water jet and closes in 300 milliseconds. The four main components of the valve, i.e., valve body, safety shutter, high speed shutter, and pneumatic-hydraulic actuator, are discussed. This valve is unique and may have other aerospace and industrial applications.

  13. Design and Development of a Large Diameter, High Pressure, Fast Acting Propulsion Valve and Valve Actuator

    NASA Technical Reports Server (NTRS)

    Srinivasan, K. V.

    1986-01-01

    This paper describes the design and development of a large diameter high pressure quick acting propulsion valve and valve actuator. The valve is the heart of a major test facility dedicated to conducting full scale performance tests of aircraft landing gear systems. The valve opens in less than 300 milliseconds releasing a 46 cm (18 in) diameter water jet and closes in 300 milliseconds. The four main components of the valve, i.e., valve body, safety shutter, high speed shutter, and pneumatic-hydraulic actuator, are discussed. This valve is unique and may have other aerospace and industrial applications.

  14. Transcatheter aortic valve-in-valve treatment of degenerative stentless supra-annular Freedom Solo valves: A single centre experience.

    PubMed

    Cockburn, James; Dooley, Maureen; Parker, Jessica; Hill, Andrew; Hutchinson, Nevil; de Belder, Adam; Trivedi, Uday; Hildick-Smith, David

    2017-02-15

    Redo surgery for degenerative bioprosthetic aortic valves is associated with significant morbidity and mortality. Report results of valve-in-valve therapy (ViV-TAVI) in failed supra-annular stentless Freedom Solo (FS) bioprostheses, which are the highest risk for coronary occlusion. Six patients with FS valves (mean age 78.5 years, 50% males). Five had valvular restenosis (peak gradient 87.2 mm Hg, valve area 0.63 cm 2 ), one had severe regurgitation (AR). Median time to failure was 7 years. Patients were high risk (mean STS/Logistic EuroScore 10.6 15.8, respectively). FS valves ranged from 21 to 25 mm. Successful ViV-TAVI was achieved in 4/6 patients (67%). Of the unsuccessful cases, (patient 1 and 2 of series) patient 1 underwent BAV with simultaneous aortography which revealed left main stem occlusion. The procedure was stopped and the patient went forward for repeat surgery. Patient 2 underwent successful ViV-TAVI with a 26-mm CoreValve with a guide catheter in the left main, but on removal coronary obstruction occurred, necessitating valve snaring into the aorta. Among the successful cases, (patients 3, 4, 5, 6) the TAVIs used were CoreValve Evolut R 23 mm (n = 3), and Lotus 23 mm (n = 1). In the successful cases the peak gradient fell from 83.0 to 38.3 mm Hg. No patient was left with >1+ AR. One patient had a stroke on Day 2, with full neurological recovery. Two patients underwent semi-elective pacing for LBBB and PR >280 ms. ViV-TAVI in stentless Freedom Solo valves is high risk. The risk of coronary occlusion is high. The smallest possible prosthesis (1:1 sizing) should be used, and strategies to protect the coronary vessels must be considered. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  15. Method and system for measuring gate valve clearances and seating force

    DOEpatents

    Casada, Donald A.; Haynes, Howard D.; Moyers, John C.; Stewart, Brian K.

    1996-01-01

    Valve clearances and seating force, as well as other valve operational parameters, are determined by measuring valve stem rotation during opening and closing operations of a translatable gate valve. The magnitude of the stem rotation, and the relative difference between the stem rotation on opening and closing provides valuable data on the valve internals in a non-intrusive manner.

  16. Use of endobronchial valve insertion to treat relapsing pneumothorax: a case report and literature review.

    PubMed

    Qi, Fei; Tian, Qing; Chen, Liang'an; Li, Chunyan; Zhang, Shu; Liu, Xingchen; Xiao, Binbin

    2017-07-01

    Backgorund and Aims: Unidirectional endobronchial valves have recently been shown to be beneficial as treatment for persistent air leaks. This report presents a first case of endobronchial valve implantation to treat relapsing pneumothorax in a Chinese patient, and also presents a review of the literature on the use of one-way valve insertion for the treatment of persistent air leaks. The patient did undergo a recent but failed chest tube intervention. By bronchoscopy and using Chartis® system measurements, the upper left lobe (including the left apical bronchus) was closed using a catheter. After the expected decrease in airflow following bronchial occlusion, increased air pressure and decreased spilled air were noted; it was concluded that the pneumothorax was located in the left upper lobe. A Zephyr ® endobronchial valve was placed in the left upper apical bronchus. The health benefits of the procedure were noticed in the following days. Our review suggests that the use of endobronchial valves could be used as an effective, minimally invasive, low-risk intervention for patients with pneumothorax that cannot be treated surgically. © 2015 John Wiley & Sons Ltd.

  17. A shut-off valve for flexible tubing

    NASA Technical Reports Server (NTRS)

    Reyburn, W. W.

    1972-01-01

    Design of light weight valve for flexible tubing is described. Valve is hand operated and provides positive sealing in normally closed position. Diagram is provided to show construction of valve. Principles of operation are explained.

  18. Absence of posterior tricuspid valve leaflet and valve reconstruction

    PubMed Central

    Komoda, Takeshi; Stamm, Christof; Fleck, Eckart; Hetzer, Roland

    2012-01-01

    We report a rare case of the absence of a posterior tricuspid valve leaflet. A male patient, aged 46, suffering from severe tricuspid valve regurgitation (TR) of unknown aetiology and atrial septal aneurysm was referred to our hospital for surgery. On surgical inspection, the posterior tricuspid valve leaflet and its subvalvular apparatus were completely absent and only the valve annulus was seen in the corresponding position. The anterior and septal leaflets were normal. We successfully reconstructed the tricuspid valve as follows: the head of an anterior papillary muscle was approximated to the ventricular septum (Sebening stitch). After the approximation of the centre of the tricuspid annulus of the anterior leaflet to the tricuspid annulus on the opposite side, a sizer of 29 mm in diameter was easily passed through the anterior orifice. The posterior orifice was closed with running sutures (posterior annulorrhaphy after Hetzer). Before these procedures, we attempted to reconstruct the tricuspid valve with a posterior annulorrhaphy alone; however, valve competence was insufficient. A Sebening stitch was necessary to improve the valve competence. Echocardiography showed TR grade 1 at the patient's discharge from hospital and TR grade 1 to 2 at the follow-up, 10 months after the operation. PMID:22419794

  19. Method and system for measuring gate valve clearances and seating force

    DOEpatents

    Casada, D.A.; Haynes, H.D.; Moyers, J.C.; Stewart, B.K.

    1996-01-30

    Valve clearances and seating force, as well as other valve operational parameters, are determined by measuring valve stem rotation during opening and closing operations of a translatable gate valve. The magnitude of the stem rotation, and the relative difference between the stem rotation on opening and closing provides valuable data on the valve internals in a non-intrusive manner. 8 figs.

  20. Whitey SCHe Ball Valves Provide Test Port Isolation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    MISKA, C.R.

    2000-09-15

    These valves are 1/4 inch ball valves fabricated of 316 stainless steel. Packing is TFE (standard). They are used as normally closed isolation valves for test ports in the SCHe System between the gage root valve and the pressure indicator.

  1. 46 CFR 95.15-50 - Lockout valves.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... must make it obvious whether the valve is open or closed. (d) A valve is considered a lockout valve if... be approved by the Commandant as part of the installed system. [USCG-2006-24797, 77 FR 33878, Jun. 7...

  2. 46 CFR 76.15-50 - Lockout valves.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... make it obvious whether the valve is open or closed. (d) A valve is considered a lockout valve if it... approved by the Commandant as part of the installed system. [USCG-2006-24797, 77 FR 33876, Jun. 7, 2012] ...

  3. FLUID MECHANICS OF ARTIFICIAL HEART VALVES

    PubMed Central

    Dasi, Lakshmi P; Simon, Helene A; Sucosky, Philippe; Yoganathan, Ajit P

    2009-01-01

    SUMMARY 1. Artificial heart valves have been in use for over five decades to replace diseased heart valves. Since the first heart valve replacement performed with a caged-ball valve, more than 50 valve designs have been developed, differing principally in valve geometry, number of leaflets and material. To date, all artificial heart valves are plagued with complications associated with haemolysis, coagulation for mechanical heart valves and leaflet tearing for tissue-based valve prosthesis. For mechanical heart valves, these complications are believed to be associated with non-physiological blood flow patterns. 2. In the present review, we provide a bird’s-eye view of fluid mechanics for the major artificial heart valve types and highlight how the engineering approach has shaped this rapidly diversifying area of research. 3. Mechanical heart valve designs have evolved significantly, with the most recent designs providing relatively superior haemodynamics with very low aerodynamic resistance. However, high shearing of blood cells and platelets still pose significant design challenges and patients must undergo life-long anticoagulation therapy. Bioprosthetic or tissue valves do not require anticoagulants due to their distinct similarity to the native valve geometry and haemodynamics, but many of these valves fail structurally within the first 10–15 years of implantation. 4. These shortcomings have directed present and future research in three main directions in attempts to design superior artificial valves: (i) engineering living tissue heart valves; (ii) development of advanced computational tools; and (iii) blood experiments to establish the link between flow and blood damage. PMID:19220329

  4. Fluid mechanics of artificial heart valves.

    PubMed

    Dasi, Lakshmi P; Simon, Helene A; Sucosky, Philippe; Yoganathan, Ajit P

    2009-02-01

    1. Artificial heart valves have been in use for over five decades to replace diseased heart valves. Since the first heart valve replacement performed with a caged-ball valve, more than 50 valve designs have been developed, differing principally in valve geometry, number of leaflets and material. To date, all artificial heart valves are plagued with complications associated with haemolysis, coagulation for mechanical heart valves and leaflet tearing for tissue-based valve prosthesis. For mechanical heart valves, these complications are believed to be associated with non-physiological blood flow patterns. 2. In the present review, we provide a bird's-eye view of fluid mechanics for the major artificial heart valve types and highlight how the engineering approach has shaped this rapidly diversifying area of research. 3. Mechanical heart valve designs have evolved significantly, with the most recent designs providing relatively superior haemodynamics with very low aerodynamic resistance. However, high shearing of blood cells and platelets still pose significant design challenges and patients must undergo life-long anticoagulation therapy. Bioprosthetic or tissue valves do not require anticoagulants due to their distinct similarity to the native valve geometry and haemodynamics, but many of these valves fail structurally within the first 10-15 years of implantation. 4. These shortcomings have directed present and future research in three main directions in attempts to design superior artificial valves: (i) engineering living tissue heart valves; (ii) development of advanced computational tools; and (iii) blood experiments to establish the link between flow and blood damage.

  5. Kelly mud saver valve sub

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Reddoch, J.A.

    1986-12-02

    A mud saver valve is described for preventing drilling mud from escaping from a kelly when a drill string is broken below the kelly, the valve comprising: a tubular valve body having first and second ends, the first end being provided with means for attachment in fluid communicating relationship with the kelly, the second end being provided with means for attachment to the drill string; an annular seat fixed in the interior of the valve body adjacent its first end; a tubular closure member within the valve body. The closure member is provided with a selectively closed seating end formore » seating in valve closing engagement with the annular seat, an open non-seating end in fluid communicating relationship with the drill string, and an annular expansion in the outer diameter of the closure member adjacent the seating end; a top and bottom spacer ring disposed in sliding relationship around the tubular closure member intermediate the annular expansion and the non-seating end of the closure member. The spacer ring and annular expansion cooperatively define an annular chamber around the closure member; and a helical spring disposed around the closure member towards the annular seat.« less

  6. Multi-port valve assembly

    DOEpatents

    Guggenheim, S. Frederic

    1986-01-01

    A multi-port fluid valve apparatus is used to control the flow of fluids through a plurality of valves and includes a web, which preferably is a stainless steel endless belt. The belt has an aperture therethrough and is progressed, under motor drive and control, so that its aperture is moved from one valve mechanism to another. Each of the valve mechanisms comprises a pair of valve blocks which are held in fluid-tight relationship against the belt. Each valve block consists of a block having a bore through which the fluid flows, a first seal surrounding the bore and a second seal surrounding the first seal, with the distance between the first and second seals being greater than the size of the belt aperture. In order to open a valve, the motor progresses the belt aperture to where it is aligned with the two bores of a pair of valve blocks, such alignment permitting a flow of the fluid through the valve. The valve is closed by movement of the belt aperture and its replacement, within the pair of valve blocks, by a solid portion of the belt.

  7. Observation of cavitation in a mechanical heart valve in a total artificial heart.

    PubMed

    Lee, Hwansung; Tsukiya, Tomonori; Homma, Akihiko; Kamimura, Tadayuki; Takewa, Yoshiaki; Nishinaka, Tomohiro; Tatsumi, Eisuke; Taenaka, Yoshiyuki; Takano, Hisateru; Kitamura, Soichiro

    2004-01-01

    Recently, cavitation on the surface of mechanical heart valves has been studied as a cause of fractures occurring in implanted mechanical heart valves. The cause of cavitation in mechanical heart valves was investigated using the 25 mm Medtronic Hall valve and the 23 mm Omnicarbon valve. Closing of these valves in the mitral position was simulated in an electrohydraulic totally artificial heart. Tests were conducted under physiologic pressures at heart rates from 60 to 100 beats per minute with cardiac outputs from 4.8 to 7.7 L/min. The disk closing motion was measured by a laser displacement sensor. A high-speed video camera was used to observe the cavitation bubbles in the mechanical heart valves. The maximum closing velocity of the Omnicarbon valve was faster than that of the Medtronic Hall valve. In both valves, the closing velocity of the leaflet, used as the cavitation threshold, was approximately 1.3-1.5 m/s. In the case of the Medtronic Hall valve, cavitation bubbles were generated by the squeeze flow and by the effects of the venturi and the water hammer. With the Omnicarbon valve, the cavitation bubbles were generated by the squeeze flow and the water hammer. The mechanism leading to the development of cavitation bubbles depended on the valve closing velocity and the valve stop geometry. Most of the cavitation bubbles were observed around the valve stop and were generated by the squeeze flow.

  8. Mechanism of valve failure and efficacy of reintervention through catheterization in patients with bioprosthetic valves in the pulmonary position

    PubMed Central

    Callahan, Ryan; Bergersen, Lisa; Baird, Christopher W; Porras, Diego; Esch, Jesse J; Lock, James E; Marshall, Audrey C

    2017-01-01

    Background: Surgical and transcatheter bioprosthetic valves (BPVs) in the pulmonary position in patients with congenital heart disease may ultimately fail and undergo transcatheter reintervention. Angiographic assessment of the mechanism of BPV failure has not been previously described. Aims: The aim of this study was to determine the mode of BPV failure (stenosis/regurgitation) requiring transcatheter reintervention and to describe the angiographic characteristics of the failed BPVs and report the types and efficacy of reinterventions. Materials and Methods: This is a retrospective single-center review of consecutive patients who previously underwent pulmonary BPV placement (surgical or transcatheter) and subsequently underwent percutaneous reintervention from 2005 to 2014. Results: Fifty-five patients with surgical (41) and transcutaneous pulmonary valve (TPV) (14) implantation of BPVs underwent 66 catheter reinterventions. The surgically implanted valves underwent fifty reinterventions for indications including 16 for stenosis, seven for regurgitation, and 27 for both, predominantly associated with leaflet immobility, calcification, and thickening. Among TPVs, pulmonary stenosis (PS) was the exclusive failure mode, mainly due to loss of stent integrity (10) and endocarditis (4). Following reintervention, there was a reduction of right ventricular outflow tract gradient from 43 ± 16 mmHg to 16 ± 10 mmHg (P < 0.001) and RVp/AO ratio from 0.8 ± 0.2 to 0.5 ± 0.2 (P < 0.001). Reintervention with TPV placement was performed in 45 (82%) patients (34 surgical, 11 transcatheter) with no significant postintervention regurgitation or paravalvular leak. Conclusion: Failing surgically implanted BPVs demonstrate leaflet calcification, thickness, and immobility leading to PS and/or regurgitation while the mechanism of TPV failure in the short- to mid-term is stenosis, mainly from loss of stent integrity. This can be effectively treated with a catheter-based approach

  9. 14 CFR 23.995 - Fuel valves and controls.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Powerplant Fuel System... valve rapidly after it has been closed. (c) Each valve and fuel system control must be supported so that... lines connected to the valve. (d) Each valve and fuel system control must be installed so that gravity...

  10. 14 CFR 23.995 - Fuel valves and controls.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Powerplant Fuel System... valve rapidly after it has been closed. (c) Each valve and fuel system control must be supported so that... lines connected to the valve. (d) Each valve and fuel system control must be installed so that gravity...

  11. 14 CFR 23.995 - Fuel valves and controls.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Powerplant Fuel System... valve rapidly after it has been closed. (c) Each valve and fuel system control must be supported so that... lines connected to the valve. (d) Each valve and fuel system control must be installed so that gravity...

  12. 14 CFR 23.995 - Fuel valves and controls.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Powerplant Fuel System... valve rapidly after it has been closed. (c) Each valve and fuel system control must be supported so that... lines connected to the valve. (d) Each valve and fuel system control must be installed so that gravity...

  13. 14 CFR 23.995 - Fuel valves and controls.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Powerplant Fuel System... valve rapidly after it has been closed. (c) Each valve and fuel system control must be supported so that... lines connected to the valve. (d) Each valve and fuel system control must be installed so that gravity...

  14. Modeling the Mitral Valve

    NASA Astrophysics Data System (ADS)

    Kaiser, Alexander

    2016-11-01

    The mitral valve is one of four valves in the human heart. The valve opens to allow oxygenated blood from the lungs to fill the left ventricle, and closes when the ventricle contracts to prevent backflow. The valve is composed of two fibrous leaflets which hang from a ring. These leaflets are supported like a parachute by a system of strings called chordae tendineae. In this talk, I will describe a new computational model of the mitral valve. To generate geometry, general information comes from classical anatomy texts and the author's dissection of porcine hearts. An MRI image of a human heart is used to locate the tips of the papillary muscles, which anchor the chordae tendineae, in relation to the mitral ring. The initial configurations of the valve leaflets and chordae tendineae are found by solving solving an equilibrium elasticity problem. The valve is then simulated in fluid (blood) using the immersed boundary method over multiple heart cycles in a model valve tester. We aim to identify features and mechanisms that influence or control valve function. Support from National Science Foundation, Graduate Research Fellowship Program, Grant DGE 1342536.

  15. ULTRA HIGH VACUUM VALVE

    DOEpatents

    Fry, W.A.

    1962-05-29

    A valve for high vacuum applications such as the CStellarator where chamber pressures as low as 2 x 10/sup -10/ mm Hg are necessary is designed with a line-of-sight path through the valve for visual inspection of the contents of reactants in such chambers. The valve comprises a turnable resilient metal ball having an aperture therethrough, means for selectively turning the ball to rotate the axis of its line-of-sight path, and soft, deformable opposing orifices that are movable relatively toward said ball to seal with opposite ball surfaces upon said movement of said axis of said line-of-sight path. The valve also includes a bellows seal connected between said orifices and internal actuating means that eliminates the requirement for gasketed turnable valve closing stems. (AEC)

  16. Sequenced drive for rotary valves

    DOEpatents

    Mittell, Larry C.

    1981-01-01

    A sequenced drive for rotary valves which provides the benefits of applying rotary and linear motions to the movable sealing element of the valve. The sequenced drive provides a close approximation of linear motion while engaging or disengaging the movable element with the seat minimizing wear and damage due to scrubbing action. The rotary motion of the drive swings the movable element out of the flowpath thus eliminating obstruction to flow through the valve.

  17. TWO-WAY FREEZE VALVE

    DOEpatents

    Lantz, K.D.; Clark, P.M.

    1960-01-01

    A valve for closing off the flow of radioactive and corrosive gases and liquids or mixtures thereof and forming a leak tight barrier is described. This valve has no mechanical moving parts which would require design to close tolerances and retention of the usual seal tighthess. Instead, there is provided a cavity in which a fusible metal is contained. Heating and cooling are provided to exercise control over the state of the metal. Baffle chambers are utilized to separate the molten fusible metal from the gas or liquid which is being passed through and return the molten metal to its cavity.

  18. Magnetically driven cold valve for 4He

    NASA Astrophysics Data System (ADS)

    Bueno, J.; Blaauwgeers, R.; Partapsing, R.; Taminiau, I.; Jochemsen, R.

    2006-08-01

    We have designed a low temperature valve for liquid helium, which uses a magnetic field gradient and a permanent magnet to close. For closing, it presses a small ruby ball onto a Torlon seat. We present a small valve that is easy to build and easily controlled via two wires. It has a fast response, reliable, and has the advantage that there is no dead volume change on closing and no additional helium line is required to operate.

  19. Pressure control valve. [inflating flexible bladders

    NASA Technical Reports Server (NTRS)

    Lambson, K. H. (Inventor)

    1980-01-01

    A control valve is provided which is adapted to be connected between a pressure source, such as a vacuum pump, and a pressure vessel so as to control the pressure in the vessel. The valve comprises a housing having a longitudinal bore which is connected between the pump and vessel, and a transversely movable valve body which controls the air flow through an air inlet in the housing. The valve body includes cylindrical and conical shaped portions which cooperate with reciprocally shaped portions of the housing to provide flow control. A filter in the air inlet removes foreign matter from the air. The bottom end of the valve body is screwed into the valve housing control knob formed integrally with the valve body and controls translation of the valve body, and the opening and closing of the valve.

  20. Self-compensating solenoid valve

    NASA Technical Reports Server (NTRS)

    Woeller, Fritz H. (Inventor); Matsumoto, Yutaka (Inventor)

    1987-01-01

    A solenoid valve is described in which both an inlet and an outlet of the valve are sealed when the valve is closed. This double seal compensates for leakage at either the inlet or the outlet by making the other seal more effective in response to the leakage and allows the reversal of the flow direction by simply switching the inlet and outlet connections. The solenoid valve has a valve chamber within the valve body. Inlet and outlet tubes extend through a plate into the chamber. A movable core in the chamber extends into the solenoid coil. The distal end of the core has a silicone rubber plug. Other than when the solenoid is energized, the compressed spring biases the core downward so that the surface of the plug is in sealing engagement with the ends of the tubes. A leak at either end increases the pressure in the chamber, resulting in increased sealing force of the plug.

  1. Valve

    DOEpatents

    Cho, Nakwon

    1980-01-01

    A positive acting valve suitable for operation in a corrosive environment is provided. The valve includes a hollow valve body defining an open-ended bore for receiving two, axially aligned, spaced-apart, cylindrical inserts. One insert, designated the seat insert, terminates inside the valve body in an annular face which lies within plane normal to the axis of the two inserts. An elastomeric O-ring seal is disposed in a groove extending about the annular face. The other insert, designated the wedge insert, terminates inside the valve body in at least two surfaces oppositely inclined with respect to each other and with respect to a plane normal to the axis of the two inserts. An elongated reciprocable gate, movable between the two inserts along a path normal to the axis of the two inserts, has a first flat face portion disposed adjacent and parallel to the annular face of the seat insert. The gate has a second face portion opposite to the first face portion provided with at least two oppositely inclined surfaces for mating with respective inclined surfaces of the wedge insert. An opening is provided through the gate which registers with a flow passage through the two inserts when the valve is open. Interaction of the respective inclined surfaces of the gate and wedge insert act to force the first flat face portion of the gate against the O-ring seal in the seat insert at the limits of gate displacement where it reaches its respective fully open and fully closed positions.

  2. Development of Overflow-Prevention Valve with Trigger Mechanism.

    NASA Astrophysics Data System (ADS)

    Ishino, Yuji; Mizuno, Takeshi; Takasaki, Masaya

    2016-09-01

    A new overflow-prevention valve for combustible fluid is developed which uses a trigger mechanism. Loading arms for combustible fluid are used for transferring oil from a tanker to tanks and vice versa. The loading arm has a valve for preventing overflow. Overflow- prevention valves cannot use any electric component to avoid combustion. Therefore, the valve must be constructed only by mechanical parts. The conventional overflow-prevention valve uses fluid and pneumatic forces. It consists of a sensor probe, a cylinder, a main valve for shutting off the fluid and a locking mechanism for holding an open state of the main valve. The proposed overflow-prevention valve uses the pressure due to the height difference between the fluid level of the tank and the sensor probe. However, the force of the cylinder produced by the pressure is too small to release the locking mechanism. Therefore, a trigger mechanism is introduced between the cylinder and the locking mechanism. The trigger mechanism produces sufficient force to release the locking mechanism and close the main valve when the height of fluid exceeds a threshold value. A trigger mechanism is designed and fabricated. The operation necessary for closing the main valve is conformed experimentally.

  3. Hydraulically actuated gas exchange valve assembly and engine using same

    DOEpatents

    Carroll, Thomas S.; Taylor, Gregory O.

    2002-09-03

    An engine comprises a housing that defines a hollow piston cavity that is separated from a gas passage by a valve seat. The housing further defines a biasing hydraulic cavity and a control hydraulic cavity. A gas valve member is also included in the engine and is movable relative to the valve seat between an open position at which the hollow piston cavity is open to the gas passage and a closed position in which the hollow piston cavity is blocked from the gas passage. The gas valve member includes a ring mounted on a valve piece and a retainer positioned between the ring and the valve piece. A closing hydraulic surface is included on the gas valve member and is exposed to liquid pressure in the biasing hydraulic cavity.

  4. Technical pitfalls and tips for the valve-in-valve procedure

    PubMed Central

    2017-01-01

    Transcatheter aortic valve implantation (TAVI) has emerged as a viable treatment modality for patients with severe aortic valve stenosis and multiple co-morbidities. More recent indications include the use of transcatheter heart valves (THV) to treat degenerated bioprosthetic surgical heart valves (SHV), which are failing due to stenosis or regurgitation. Valve-in-valve (VIV) procedures in the aortic position have been performed with a variety of THV devices, although the balloon-expandable SAPIEN valve platform (Edwards Lifesciences Ltd, Irvine, CA, USA) and self-expandable CoreValve platform (Medtronic Inc., MN, USA) have been used in majority of the patients. VIV treatment is appealing as it is less invasive than conventional surgery but optimal patient selection is vital to avoid complications such as malposition, residual high gradients and coronary obstruction. To minimize the risk of complications, thorough procedural planning is critical. The first step is identification of the degenerated SHV, including its model, size, fluoroscopic appearance. Although label size and stent internal diameter (ID) are provided by the manufacturer, it is important to note the true ID. The true ID is the ID of a SHV after the leaflets are mounted and helps determine the optimal size of THV. The second step is to determine the type and size of the THV. Although this is determined in the majority of the cases by user preference, in certain situations one THV may be more suitable than another. As the procedure is performed under fluoroscopy, the third step is to become familiarized with the fluoroscopic appearance of both the SHV and THV. This helps to determine the landmarks for optimal positioning, which in turn determines the gradients and fixation. The fourth step is to assess the risk of coronary obstruction. This is performed with either aortic root angiography or ECG-gated computerised tomography (CT). Finally, the route of approach must be carefully planned. Once these

  5. 40 CFR 264.1056 - Standards: Open-ended valves or lines.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... hazardous waste stream end is closed before the second valve is closed. (c) When a double block and bleed system is being used, the bleed valve or line may remain open during operations that require venting the...

  6. Transcatheter valve underexpansion limits leaflet durability: implications for valve-in-valve procedures

    PubMed Central

    Martin, Caitlin; Sun, Wei

    2016-01-01

    Transcatheter aortic valve (TAV) implantation within a failed bioprosthetic valve is a growing trend for high-risk patients. The non-compliant stent of the previous prosthesis may prevent full expansion of the TAV, which has been shown to distort the leaflet configuration, and has been hypothesized to adversely affect durability. In this study, TAV leaflet fatigue damage under cyclic pressurization in the setting of stent underexpansion by 0 (fully expanded), 1, 2 and 3 mm was simulated using finite element analysis to test this hypothesis. In the 2 and 3 mm underexpanded devices, the TAV leaflets exhibited severe pin-wheeling during valve closure, which increased leaflet stresses dramatically, and resulted in accelerated fatigue damage of the leaflets. The leaflet fatigue damage in the 1 mm underexpanded case was similar to that in the fully expanded case. Clinically a range of 10% to 15% underexpansion is generally considered acceptable; however, it was observed in this study that ≥2 mm (≥9.1%) underexpansion, will significantly impact device durability. Further study is necessary to determine the impact of various deployment conditions, i.e. non-uniform and non-circular deployments and different implantation heights, on differing TAV devices, but it is clear that the normal TAV leaflet configuration must be preserved in order to preserve durability. PMID:27734178

  7. Variable gas leak rate valve

    DOEpatents

    Eernisse, Errol P.; Peterson, Gary D.

    1976-01-01

    A variable gas leak rate valve which utilizes a poled piezoelectric element to control opening and closing of the valve. The gas flow may be around a cylindrical rod with a tubular piezoelectric member encircling the rod for seating thereagainst to block passage of gas and for reopening thereof upon application of suitable electrical fields.

  8. Hydrogen gas relief valve

    DOEpatents

    Whittlesey, Curtis C.

    1985-01-01

    An improved battery stack design for an electrochemical system having at least one cell from which a gas is generated and an electrolyte in communication with the cell is described. The improved battery stack design features means for defining a substantially closed compartment for containing the battery cells and at least a portion of the electrolyte for the system, and means in association with the compartment means for selectively venting gas from the interior of the compartment means in response to the level of the electrolyte within the compartment means. The venting means includes a relief valve having a float member which is actuated in response to the level of the electrolyte within the compartment means. This float member is adapted to close the relief valve when the level of the electrolyte is above a predetermined level and open the relief valve when the level of electrolyte is below this predetermined level.

  9. Microfluidic valve array control system integrating a fluid demultiplexer circuit

    NASA Astrophysics Data System (ADS)

    Kawai, Kentaro; Arima, Kenta; Morita, Mizuho; Shoji, Shuichi

    2015-06-01

    This paper proposes an efficient control method for the large-scale integration of microvalves in microfluidic systems. The proposed method can control 2n individual microvalves with 2n + 2 control lines (where n is an integer). The on-chip valves are closed by applying pressure to a control line, similar to conventional pneumatic microvalves. Another control line closes gate valves between the control line to the on-chip valves and the on-chip valves themselves, to preserve the state of the on-chip valves. The remaining control lines select an activated gate valve. While the addressed gate valve is selected by the other control lines, the corresponding on-chip valve is actuated by applying input pressure to the control line to the on-chip valves. Using this method would substantially reduce the number of world-to-chip connectors and off-chip valve controllers. Experiments conducted using a fabricated 28 microvalve array device, comprising 256 individual on-chip valves controlled with 18 (2   ×   8 + 2) control lines, yielded switching speeds for the selected on-chip valve under 90 ms.

  10. Influence of aortic valve leaflet calcification on dynamic aortic valve motion assessed by cardiac computed tomography.

    PubMed

    Minami, Keisuke; Yoneyama, Kihei; Izumo, Masaki; Suzuki, Kengo; Ogawa, Yasuyoshi; Chikaraishi, Kousuke; Ogawa, Yukihisa; Kobayashi, Yasuyuki; Furukawa, Toshiyuki; Tanabe, Yasuhiro; Akashi, Yoshihiro J

    Computed tomography is the best noninvasive imaging modality for evaluating valve leaflet calcification. To evaluate the association of aortic valve leaflet calcification with instantaneous valve opening and closing using dynamic multidetector computed tomography (MDCT). We retrospectively evaluated 58 consecutive patients who underwent dynamic MDCT imaging. Aortic valve calcification (AVC) was quantified using the Agatston method. The aortic valve area (AVA) tracking curves were derived by planimetry during the cardiac cycle using all 20 phases (5% reconstruction). da/dt in cm 2 /s was calculated as the rate of change of AVA during opening (positive) or closing (negative). Patients were divided into 3 three groups according to Agatston score quartile: no AVC (Q2, Score 0, n = 18), mild AVC (Q3, Score 1-2254, n = 24), and severe AVC (Q4 Score >2254, n = 14). In multivariable linear regression, compared to the non AVC group, the mild and severe AVC groups had lower maximum AVA (by -1.71 cm 2 and -2.25 cm 2 , respectively), lower peak positive da/dt (by -21.88 cm 2 /s and -26.65 cm 2 /s, respectively), and higher peak negative da/dt (by 13.78 cm 2 /s and 18.11 cm 2 /s, respectively) (p < 0.05 for all comparisons). AVA and its opening and closing were influenced by leaflet calcification. The present study demonstrates the ability of dynamic MDCT imaging to assess quantitative aortic valve motion in a clinical setting. Copyright © 2016 Society of Cardiovascular Computed Tomography. Published by Elsevier Inc. All rights reserved.

  11. A Model-Based Prognostics Approach Applied to Pneumatic Valves

    NASA Technical Reports Server (NTRS)

    Daigle, Matthew J.; Goebel, Kai

    2011-01-01

    Within the area of systems health management, the task of prognostics centers on predicting when components will fail. Model-based prognostics exploits domain knowledge of the system, its components, and how they fail by casting the underlying physical phenomena in a physics-based model that is derived from first principles. Uncertainty cannot be avoided in prediction, therefore, algorithms are employed that help in managing these uncertainties. The particle filtering algorithm has become a popular choice for model-based prognostics due to its wide applicability, ease of implementation, and support for uncertainty management. We develop a general model-based prognostics methodology within a robust probabilistic framework using particle filters. As a case study, we consider a pneumatic valve from the Space Shuttle cryogenic refueling system. We develop a detailed physics-based model of the pneumatic valve, and perform comprehensive simulation experiments to illustrate our prognostics approach and evaluate its effectiveness and robustness. The approach is demonstrated using historical pneumatic valve data from the refueling system.

  12. Direct-heating solar-collector dump valve

    NASA Technical Reports Server (NTRS)

    Howikman, T. C.

    1977-01-01

    Five-port ganged valve isolates collector from primary load system pressure and drains collectors, allowing use of direct heating with all its advantages. Valve is opened and closed by same switch that controls pump or by temperature sensor set at O C, while providing direct dump option.

  13. 46 CFR 98.25-40 - Valves, fittings, and accessories.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ..., United States of America Standard 300-pound standard minimum, fitted with suitable soft gasket material... shut-off valves located as close to the tank as possible. (d) Excess flow valves where required by this section shall close automatically at the rated flow of vapor or liquid as specified by the manufacturer...

  14. A Parylene MEMS Electrothermal Valve

    PubMed Central

    Li, Po-Ying; Givrad, Tina K.; Holschneider, Daniel P.; Maarek, Jean-Michel I.; Meng, Ellis

    2011-01-01

    The first microelectromechanical-system normally closed electrothermal valve constructed using Parylene C is described, which enables both low power (in milliwatts) and rapid operation (in milliseconds). This low-power valve is well suited for applications in wirelessly controlled implantable drug-delivery systems. The simple design was analyzed using both theory and modeling and then characterized in benchtop experiments. Operation in air (constant current) and water (current ramping) was demonstrated. Valve-opening powers of 22 mW in air and 33 mW in water were obtained. Following integration of the valve with catheters, our valve was applied in a wirelessly operated microbolus infusion pump, and the in vivo functionality for the appropriateness of use of this pump for future brain mapping applications in small animals was demonstrated. PMID:21350679

  15. Feasibility of Valve-in-Valve Procedure for Degenerated St. Jude Medical Trifecta Bioprosthesis.

    PubMed

    Verhoye, Jean-philippe; Harmouche, Majid; Soulami, Reda Belhaj; Thebault, Christophe; Boulmier, Dominique; Leguerrier, Alain; Anselmi, Amedeo

    2015-07-01

    The valve-in-valve (ViV) procedure is an option for patients with symptomatic structural degeneration of a bioprosthesis and excessive reoperative risk. The risk of coronary obstruction appears to be increased if ViV is performed for certain pericardial prostheses in which the leaflets are mounted outside the stent posts. Herein is described a successful ViV for a degenerated Trifecta aortic bioprosthesis, and the technical considerations for performing a ViV procedure within such types of prosthesis are considered. Emphasis is placed on the importance of preoperative investigations (computed tomography scan-based measurements of coronary ostial height and of sinus of Valsalva diameters), and on the precise deployment of the valve (transapical approach with transesophageal echocardiography control) to minimize the risk of major complications. The presence of a failing Trifecta bioprosthesis should not be considered an absolute contraindication to ViV on the basis of the risk of coronary obstruction.

  16. Aortic Valve Regurgitation

    MedlinePlus

    ... the main artery that leads to the body (aorta) doesn't close properly, which causes some blood ... Other diseases. Other rare conditions can enlarge the aorta and aortic valve and lead to regurgitation, including ...

  17. THERMALLY OPERATED VAPOR VALVE

    DOEpatents

    Dorward, J.G. Jr.

    1959-02-10

    A valve is presented for use in a calutron to supply and control the vapor to be ionized. The invention provides a means readily operable from the exterior of the vacuum tank of the apparatuss without mechanical transmission of forces for the quick and accurate control of the ionizing arc by a corresponding control of gas flow theretos thereby producing an effective way of carefully regulating the operation of the calutron. The invention consists essentially of a tube member extending into the charge bottle of a calutron devices having a poppet type valve closing the lower end of the tube. An electrical heating means is provided in the valve stem to thermally vary the length of the stem to regulate the valve opening to control the flow of material from the charge bottle.

  18. Modeling and control of fuel distribution in a dual-fuel internal combustion engine leveraging late intake valve closings

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kassa, Mateos; Hall, Carrie; Ickes, Andrew

    Advanced internal combustion engines, although generally more efficient than conventional combustion engines, often encounter limitations in multi-cylinder applications due to variations in the combustion process encountered across cylinders and between cycles. This study leverages experimental data from an inline 6-cylinder heavy-duty dual fuel engine equipped with exhaust gas recirculation (EGR), a variable geometry turbocharger, and a fully-flexible variable intake valve actuation system to study cylinder-to-cylinder variations in power production and the underlying uneven fuel distribution that causes these variations. The engine is operated with late intake valve closure timings in a dual-fuel combustion mode in which a high reactivity fuelmore » is directly injected into the cylinders and a low reactivity fuel is port injected into the cylinders. Both dual fuel implementation and late intake valve closing (IVC) timings have been shown to improve thermal efficiency. However, experimental data from this study reveal that when late IVC timings are used on a multi-cylinder dual fuel engine a significant variation in IMEP across cylinders results and as such, leads to efficiency losses. The difference in IMEP between the different cylinders ranges from 9% at an IVC of 570°ATDC to 38% at an IVC of 610°ATDC and indicates an increasingly uneven fuel distribution. These experimental observations along with engine simulation models developed using GT-Power have been used to better understand the distribution of the port injected fuel across cylinders under various operating conditions on such dual fuel engines. This study revealed that the fuel distribution across cylinders in this dual fuel application is significantly affected by changes in the effective compression ratio as determined by the intake valve close timing as well as the design of the intake system (specifically the length of the intake runners). Late intake valve closures allow a portion of the

  19. Incorporation of prefabricated screw, pneumatic, and solenoid valves into microfluidic devices.

    PubMed

    Hulme, S Elizabeth; Shevkoplyas, Sergey S; Whitesides, George M

    2009-01-07

    This paper describes a method for prefabricating screw, pneumatic, and solenoid valves and embedding them in microfluidic devices. This method of prefabrication and embedding is simple, requires no advanced fabrication, and is compatible with soft lithography. Because prefabrication allows many identical valves to be made at one time, the performance across different valves made in the same manner is reproducible. In addition, the performance of a single valve is reproducible over many cycles of opening and closing: an embedded solenoid valve opened and closed a microfluidic channel more than 100,000 times with no apparent deterioration in its function. It was possible to combine all three types of prefabricated valves in a single microfluidic device to control chemical gradients in a microfluidic channel temporally and spatially.

  20. Increasing the reliability of solution exchanges by monitoring solenoid valve actuation.

    PubMed

    Auzmendi, Jerónimo Andrés; Moffatt, Luciano

    2010-01-15

    Solenoid valves are a core component of most solution perfusion systems used in neuroscience research. As they open and close, they control the flow of solution through each perfusion line, thereby modulating the timing and sequence of chemical stimulation. The valves feature a ferromagnetic plunger that moves due to the magnetization of the solenoid and returns to its initial position with the aid of a spring. The delays between the time of voltage application or removal and the actual opening or closing of the valve are difficult to predict beforehand and have to be measured experimentally. Here we propose a simple method for monitoring whether and when the solenoid valve opens and closes. The proposed method detects the movement of the plunger as it generates a measurable signal on the solenoid that surrounds it. Using this plunger signal, we detected the opening and closing of diaphragm and pinch solenoid valves with a systematic error of less than 2ms. After this systematic error is subtracted, the trial-to-trial error was below 0.2ms.

  1. 14 CFR 29.1025 - Oil valves.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Oil valves. 29.1025 Section 29.1025... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant Oil System § 29.1025 Oil valves. (a) Each oil shutoff must meet the requirements of § 29.1189. (b) The closing of oil shutoffs may not prevent autorotation...

  2. 14 CFR 29.1025 - Oil valves.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Oil valves. 29.1025 Section 29.1025... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant Oil System § 29.1025 Oil valves. (a) Each oil shutoff must meet the requirements of § 29.1189. (b) The closing of oil shutoffs may not prevent autorotation...

  3. 14 CFR 29.1025 - Oil valves.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Oil valves. 29.1025 Section 29.1025... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant Oil System § 29.1025 Oil valves. (a) Each oil shutoff must meet the requirements of § 29.1189. (b) The closing of oil shutoffs may not prevent autorotation...

  4. 14 CFR 29.1025 - Oil valves.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Oil valves. 29.1025 Section 29.1025... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant Oil System § 29.1025 Oil valves. (a) Each oil shutoff must meet the requirements of § 29.1189. (b) The closing of oil shutoffs may not prevent autorotation...

  5. 14 CFR 29.1025 - Oil valves.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Oil valves. 29.1025 Section 29.1025... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant Oil System § 29.1025 Oil valves. (a) Each oil shutoff must meet the requirements of § 29.1189. (b) The closing of oil shutoffs may not prevent autorotation...

  6. Percutaneous Valvuloplasty for Bioprosthetic Tricuspid Valve Stenosis

    PubMed Central

    Malhotra, Rohit; Sharma, Anjali; Kakouros, Nikolaos

    2017-01-01

    Percutaneous transcatheter tricuspid balloon valvuloplasty (PTTBV) is an accepted treatment option for symptomatic severe native tricuspid valve stenosis, although surgical tricuspid valve replacement remains the treatment of choice. There have been few reports of successful PTTBV for bioprosthetic tricuspid valve stenosis. We present case reports of 3 patients from our hospital experience. Two of the 3 cases were successful, with lasting clinical improvement, whereas the 3rd patient failed to show a reduction in valve gradient. We describe the standard technique used for PTTBV. We present results from a literature review that identified 16 previously reported cases of PTTBV for bioprosthetic severe tricuspid stenosis, with overall favorable results. We conclude that PTTBV should perhaps be considered for a select patient population in which symptomatic improvement and hemodynamic stability are desired immediately, and particularly for patients who are inoperable or at high surgical risk. PMID:28265212

  7. Valve malfunction detection apparatus

    NASA Astrophysics Data System (ADS)

    Burley, Richard K.

    1993-07-01

    A detection system is provided for sensing a malfunction of a valve having an outlet connected to an end of a first pipe through which pressurized fluid may be flowed in a downstream direction away from the valve. The system includes a bypass pipe connected at its opposite ends to the first pipe and operative to bypass a portion of the fluid flow therethrough around a predetermined section thereof. A housing is interiorly divided by a flexible diaphragm into first and second opposite chambers which are respectively communicated with the first pipe section and the bypass pipe, the diaphragm being spring-biased toward the second chamber. The diaphragm housing cooperates with check valves and orifices connected in the two pipes to create and maintain a negative pressure in the first pipe section in response to closure of the valve during pressurized flow through the first pipe. A pressure switch senses the negative pressure and transmits a signal indicative thereof to a computer. Upon cessation of the signal while the valve is still closed, the computer responsively generates a signal indicating that the valve, or another portion of the detection system, is leaking.

  8. Valve malfunction detection apparatus

    NASA Technical Reports Server (NTRS)

    Burley, Richard K. (Inventor)

    1993-01-01

    A detection system is provided for sensing a malfunction of a valve having an outlet connected to an end of a first pipe through which pressurized fluid may be flowed in a downstream direction away from the valve. The system includes a bypass pipe connected at its opposite ends to the first pipe and operative to bypass a portion of the fluid flow therethrough around a predetermined section thereof. A housing is interiorly divided by a flexible diaphragm into first and second opposite chambers which are respectively communicated with the first pipe section and the bypass pipe, the diaphragm being spring-biased toward the second chamber. The diaphragm housing cooperates with check valves and orifices connected in the two pipes to create and maintain a negative pressure in the first pipe section in response to closure of the valve during pressurized flow through the first pipe. A pressure switch senses the negative pressure and transmits a signal indicative thereof to a computer. Upon cessation of the signal while the valve is still closed, the computer responsively generates a signal indicating that the valve, or another portion of the detection system, is leaking.

  9. 14 CFR 25.1025 - Oil valves.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Oil valves. 25.1025 Section 25.1025... STANDARDS: TRANSPORT CATEGORY AIRPLANES Powerplant Oil System § 25.1025 Oil valves. (a) Each oil shutoff must meet the requirements of § 25.1189. (b) The closing of oil shutoff means may not prevent propeller...

  10. 14 CFR 25.1025 - Oil valves.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Oil valves. 25.1025 Section 25.1025... STANDARDS: TRANSPORT CATEGORY AIRPLANES Powerplant Oil System § 25.1025 Oil valves. (a) Each oil shutoff must meet the requirements of § 25.1189. (b) The closing of oil shutoff means may not prevent propeller...

  11. 14 CFR 25.1025 - Oil valves.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Oil valves. 25.1025 Section 25.1025... STANDARDS: TRANSPORT CATEGORY AIRPLANES Powerplant Oil System § 25.1025 Oil valves. (a) Each oil shutoff must meet the requirements of § 25.1189. (b) The closing of oil shutoff means may not prevent propeller...

  12. 14 CFR 25.1025 - Oil valves.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Oil valves. 25.1025 Section 25.1025... STANDARDS: TRANSPORT CATEGORY AIRPLANES Powerplant Oil System § 25.1025 Oil valves. (a) Each oil shutoff must meet the requirements of § 25.1189. (b) The closing of oil shutoff means may not prevent propeller...

  13. 14 CFR 25.1025 - Oil valves.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Oil valves. 25.1025 Section 25.1025... STANDARDS: TRANSPORT CATEGORY AIRPLANES Powerplant Oil System § 25.1025 Oil valves. (a) Each oil shutoff must meet the requirements of § 25.1189. (b) The closing of oil shutoff means may not prevent propeller...

  14. Outcomes of Ahmed Valve Implant Following a Failed Initial Trabeculotomy and Trabeculectomy in Refractory Primary Congenital Glaucoma

    PubMed Central

    Dave, Paaraj; Senthil, Sirisha; Choudhari, Nikhil; Sekhar, Garudadri Chandra

    2015-01-01

    Purpose: The aim was to report the outcome of Ahmed glaucoma valve (AGV) (New World Medical, Inc., Rancho Cucamonga, CA, USA) implantation as a surgical intervention following an initial failed combined trabeculotomy + trabeculectomy (trab + trab) in refractory primary congenital glaucoma (RPCG). Materials and Methods: Retrospective chart review of 11 eyes of 8 patients who underwent implantation of AGV (model FP8) for RPCG between 2009 and 2011. Prior trab + trab had failed in all the eyes. Success was defined as an intraocular pressure (IOP) >5 and ≤ 18 mmHg during examination under anesthesia with or without medications and without serious complications or additional glaucoma surgery. Results: The mean age at AGV implantation was 15.4 ± 4.9 months. The mean preoperative IOP was 28 ± 5.7 mmHg which reduced to 13.6 ± 3.4 mmHg postoperatively at the last follow-up (P < 0.0001). The number of topical antiglaucoma medications reduced from a mean of 2.6 ± 0.5 to 1.6 ± 0.9 postoperatively (P = 0.009). The definition of qualified success was met in 10 (90%) eyes. One eye developed a shallow anterior chamber with choroidal detachment at 1-week, which resolved spontaneously with medications. None of the eyes developed a hypertensive phase. One eye had a long tube resulting in tube corneal touch that required trimming of the tube. One eye developed tube retraction, which was treated with a tube extender. The mean follow-up was 17.9 ± 9.3 (6.2-35.4) months. Conclusion: Managing RPCG remains a challenge. AGV implant was successful in a significant proportion of cases. PMID:25624676

  15. Mechanisms of mechanical heart valve cavitation: investigation using a tilting disk valve model.

    PubMed

    He, Z; Xi, B; Zhu, K; Hwang, N H

    2001-09-01

    The induction of mechanical heart valve (MHV) cavitation was investigated using a 27 mm Medtronic Hall (MH27) tilting disk valve. The MH27 valve was mounted in the mitral position of a simulating pulse flow system, and stroboscopic lighting used to visualize cavitation bubbles on the occluder inflow surface at the instant of valve closure. MHV cavitation was monitored using a digital camera with 0.04 mm/pixel resolution sufficient to render the tiny bubbles clearly visible on the computer monitor screen. Cavitation on MH27 valve was classified as five types according to the time, site and shape of the cavitation bubbles. Valve cavitation occurred at the instant of occluder impact with the valve seat at closing. The impact motion was subdivided into three temporal phases: (i) squeezing flow; (ii) elastic collision; and (iii) leaflet rebound. MHV cavitation caused by vortices was found to be initiated by the squeezing jet and/or by the transvalvular leakage jets. By using a tension wave which swept across the occluder surface immediately upon elastic impact, nuclei in the vortex core were expanded to form cavitation bubbles. Analysis of the shape and location of the cavitation bubbles permitted a better understanding of MHV cavitation mechanisms, based on the fluid dynamics of jet vortex and tension wave propagations.

  16. Incorporation of prefabricated screw, pneumatic, and solenoid valves into microfluidic devices

    PubMed Central

    Hulme, S. Elizabeth; Shevkoplyas, Sergey S.

    2011-01-01

    This paper describes a method for prefabricating screw, pneumatic, and solenoid valves and embedding them in microfluidic devices. This method of prefabrication and embedding is simple, requires no advanced fabrication, and is compatible with soft lithography. Because prefabrication allows many identical valves to be made at one time, the performance across different valves made in the same manner is reproducible. In addition, the performance of a single valve is reproducible over many cycles of opening and closing: an embedded solenoid valve opened and closed a microfluidic channel more than 100,000 times with no apparent deterioration in its function. It was possible to combine all three types of prefabricated valves in a single microfluidic device to control chemical gradients in a microfluidic channel temporally and spatially. PMID:19209338

  17. Anatomic characteristics of bileaflet mitral valve prolapse--Barlow disease--in patients undergoing mitral valve repair.

    PubMed

    Rostagno, Carlo; Droandi, Ginevra; Rossi, Alessandra; Bevilacqua, Sergio; Romagnoli, Stefano; Montesi, Gian Franco; Stefàno, Pier Luigi

    2014-01-01

    Barlow disease is a still challenging pathology for the surgeon. Aim of the present study is to report anatomic abnormalities of mitral valve in patients undergoing mitral valve repair. Between January 1st, 2007, and December 31st, 2010, 85 consecutive patients (54 men and 31 women, mean age 59 +/- 14 years--range: 28-85 years) with the features of a Barlow mitral valve disease underwent mitral repair Forty seven percent of patients were in New York Heart Association functional class III or IV. Preoperative transesophageal echocardiography was compared with anatomical findings at the moment of surgery. Transthoracic echocardiography diagnosis of Barlow disease according to the criteria described by Carpentier was confirmed at anatomical inspection. Annular calcifications were found in 28 patients while 7 patients presented single or multiple clefts. A flail posterior mitral leaflet was detected in 32 subjects, while a flail anterior leaflet in 8. Elongation of chordae tendineae was demonstrated in 45 patients and chordal rupture in 31. All patients showed at trans esophageal echocardiography the typical features of Barlow disease. Seventy-seven (90.6%) patients had severe mitral valve regurgitation, in the remaining 9.4% it was moderate to severe. Transesophageal echocardiography failed to identify clefts in 2/7 and chordal rupture in 4/31. bileaflet prolapse > 2 mm, billowing valve with excess tissue and thickened leaflets > or = 3 mm, and severe annular dilatation, are characteristics of Barlow disease, however the identification of the associated and complex abnormalities of mitral valve is necessary to obtain optimal valve repair.

  18. 49 CFR 236.383 - Valve locks, valves, and valve magnets.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Valve locks, valves, and valve magnets. 236.383... Inspection and Tests § 236.383 Valve locks, valves, and valve magnets. Valve locks on valves of the non-cut-off type shall be tested at least once every three months, and valves and valve magnets shall be...

  19. Valve stem and packing assembly

    DOEpatents

    Wordin, John J.

    1991-01-01

    A valve stem and packing assembly is provided in which a rotatable valve stem includes a first tractrix surface for sliding contact with a stem packing and also includes a second tractrix surface for sliding contact with a bonnet. Force is applied by means of a spring, gland flange, and gland on the stem packing so the stem packing seals to the valve stem and bonnet. This configuration serves to create and maintain a reliable seal between the stem packing and the valve stem. The bonnet includes a second complementary tractrix surface for contacting the second sliding tractrix surface, the combination serving as a journal bearing for the entire valve stem and packing assembly. The journal bearing so configured is known as a Schiele's pivot. The Schiele's pivot also serves to maintain proper alignment of the valve stem with respect to the bonnet. Vertical wear between the surfaces of the Schiele's pivot is uniform at all points of contact between the second sliding tractrix surface and the second complementary tractrix surface of a bonnet. The valve stem is connected to a valve plug by means of a slip joint. The valve is opened and closed by rotating the valve stem. The slip joint compensates for wear on the Schiele's pivot and on the valve plug. A ledge is provided on the valve bonnet for the retaining nut to bear against. The ledge prevents overtightening of the retaining nut and the resulting excessive friction between stem and stem packing.

  20. Valve stem and packing assembly

    DOEpatents

    Wordin, J.J.

    1991-09-03

    A valve stem and packing assembly is provided in which a rotatable valve stem includes a first tractrix surface for sliding contact with a stem packing and also includes a second tractrix surface for sliding contact with a bonnet. Force is applied by means of a spring, gland flange, and gland on the stem packing so the stem packing seals to the valve stem and bonnet. This configuration serves to create and maintain a reliable seal between the stem packing and the valve stem. The bonnet includes a second complementary tractrix surface for contacting the second sliding tractrix surface, the combination serving as a journal bearing for the entire valve stem and packing assembly. The journal bearing so configured is known as a Schiele's pivot. The Schiele's pivot also serves to maintain proper alignment of the valve stem with respect to the bonnet. Vertical wear between the surfaces of the Schiele's pivot is uniform at all points of contact between the second sliding tractrix surface and the second complementary tractrix surface of a bonnet. The valve stem is connected to a valve plug by means of a slip joint. The valve is opened and closed by rotating the valve stem. The slip joint compensates for wear on the Schiele's pivot and on the valve plug. A ledge is provided on the valve bonnet for the retaining nut to bear against. The ledge prevents over tightening of the retaining nut and the resulting excessive friction between stem and stem packing. 2 figures.

  1. Echoguided closed commissurotomy for mitral valve stenosis in a dog.

    PubMed

    Trehiou-Sechi, Emilie; Behr, Luc; Chetboul, Valérie; Pouchelon, Jean-Louis; Castaignet, Maud; Gouni, Vassiliki; Misbach, Charlotte; Petit, Amandine M P; Borenstein, Nicolas

    2011-09-01

    Surgical treatment of mitral stenosis (MS) usually consists of open mitral commissurotomy (MC) or percutaneous balloon MC, which require a cardiopulmonary bypass or transseptal approach, respectively. We describe here the first surgical management of congenital MS in a dog using a less invasive procedure, a surgical closed MC under direct echo guidance. A 5-year-old female Cairn terrier was referred for ascites, weakness, and marked exercise intolerance for 2 months, which was refractory to medical treatment. Diagnosis of severe MS associated with atrial fibrillation (AF) was confirmed by echo-Doppler examination and electrocardiography. Poor response to medical treatment suggested a corrective procedure on the valve was indicated. However, due to the cost and high mortality rate associated with cardiopulmonary bypass, a hybrid MC was recommended. A standard left intercostal thoracotomy was performed and three balloon valvuloplasty catheters of differing diameters were sequentially inserted through the left atrium under direct echo guidance. Transesophageal echocardiography revealed a 62% reduction in the pressure half-time compared to the pre-procedure. Thirteen months after surgery the dog is still doing well with resolution of ascites and a marked improvement of most echo-Doppler variables. Copyright © 2011 Elsevier B.V. All rights reserved.

  2. Fast-acting valve actuator

    DOEpatents

    Cho, Nakwon

    1980-01-01

    A fast-acting valve actuator utilizes a spring driven pneumatically loaded piston to drive a valve gate. Rapid exhaust of pressurized gas from the pneumatically loaded side of the piston facilitates an extremely rapid piston stroke. A flexible selector diaphragm opens and closes an exhaust port in response to pressure differentials created by energizing and de-energizing a solenoid which controls the pneumatic input to the actuator as well as selectively providing a venting action to one side of the selector diaphragm.

  3. Divided We Fail in LA: Improving Completion and Closing Racial Gaps in the Los Angeles Community College District

    ERIC Educational Resources Information Center

    Moore, Colleen; Shulock, Nancy

    2010-01-01

    A recent report titled "Divided We Fail: Improving Completion and Closing Racial Gaps in California's Community Colleges" shows that student outcomes in the state's community colleges are inadequate to meet the projected demand for college-educated workers in the labor market. The report also documents the serious problem posed by the…

  4. 17. ROSS POWERHOUSE: BUTTERFLY VALVE CONTROLS FOR UNIT 43. THE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    17. ROSS POWERHOUSE: BUTTERFLY VALVE CONTROLS FOR UNIT 43. THE BUTTERFLY VALVE LOCK INDICATES THE BUTTERFLY VALVE IS CLOSED AS UNIT 43 WAS SHUT DOWN FOR REPAIRS, 1989. - Skagit Power Development, Ross Powerhouse, On Skagit River, 10.7 miles upstream from Newhalem, Newhalem, Whatcom County, WA

  5. Closed bore XMR (CBXMR) systems for aortic valve replacement: active magnetic shielding of x-ray tubes.

    PubMed

    Bracken, John A; DeCrescenzo, Giovanni; Komljenovic, Philip; Lillaney, Prasheel V; Fahrig, Rebecca; Rowlands, J A

    2009-05-01

    Hybrid closed bore x-ray/MRI systems are being developed to improve the safety and efficacy of percutaneous aortic valve replacement procedures by harnessing the complementary strengths of the x-ray and MRI modalities in a single interventional suite without requiring patient transfer between two rooms. These systems are composed of an x-ray C-arm in close proximity (approximately 1 m) to an MRI scanner. The MRI magnetic fringe field can cause the electron beam in the x-ray tube to deflect. The deflection causes the x-ray field of view to shift position on the detector receptacle. This could result in unnecessary radiation exposure to the patient and the staff in the cardiac catheterization laboratory. Therefore, the electron beam deflection must be corrected. The authors developed an active magnetic shielding system that can correct for electron beam deflection to within an accuracy of 5% without truncating the field of view or increasing exposure to the patient. This system was able to automatically adjust to different field strengths as the external magnetic field acting on the x-ray tube was changed. Although a small torque was observed on the shielding coils of the active shielding system when they were placed in a magnetic field, this torque will not impact their performance if they are securely mounted on the x-ray tube and the C-arm. The heating of the coils of the shielding system for use in the clinic caused by electric current was found to be slow enough not to require a dedicated cooling system for one percutaneous aortic valve replacement procedure. However, a cooling system will be required if multiple procedures are performed in one session.

  6. Measurements of droplet velocity and size downstream of the moving valves of a four-valve engine with manifold injection, operated under isothermal steady suction conditions

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Posylkin, M.; Taylor, A.M.K.P.; Whitelaw, J.H.

    The four-valve head of a VTEC engine was mounted on an open cylinder and the valves and fuel injection system operated as in the engine with a rotational speed of 1,200 rpm. Local measurements of droplet characteristics were obtained with a phase-Doppler velocimeter and iso-octane injected over 5 ms intervals, corresponding to 36 crank angle degrees, with manifold depression of 20 mbar. The results show that most of the fuel droplets were located close to the liner and on the side of the cylinder adjacent to the exhaust valves. In the plane of the measurement, 10 mm below TDC, themore » liquid flux diminished as the initiation of injection was advanced before opening of the inlet valves. With injection with the inlet valves closed, there were two waves of droplets, one from each of the two valves and separated by 60 deg CA and both with the Sauter mean diameter of about 120 {micro}m. With injection with the inlet valves open, most of the droplets emerged from the main inlet valve and with Sauter mean diameters of about 50 {micro}m, smaller than those of the unconfined spray.« less

  7. Valve for gas centrifuges

    DOEpatents

    Hahs, C.A.; Rurbage, C.H.

    1982-03-17

    The invention is pneumatically operated valve assembly for simulatenously (1) closing gas-transfer lines connected to a gas centrifuge or the like and (2) establishing a recycle path between two on the lines so closed. The value assembly is especially designed to be compact, fast-acting, reliable, and comparatively inexpensive. It provides large reductions in capital costs for gas-centrifuge cascades.

  8. Valved molecular beam skimmer

    NASA Astrophysics Data System (ADS)

    Marceca, Ernesto; Becker, Jörg A.; Hensel, Friedrich

    1997-08-01

    Under routine source conditions, the optimum nozzle-skimmer distance to achieve maximum molecular beam intensities is within the range of a few millimeters. In cases where double skimming is additionally required, the distance between the skimmers should be kept small in order to sample a sufficiently large solid angle of the beam and hence maintain a good enough intensity. These two facts make it normally difficult to isolate the first from the second expansion chamber using a commercial vacuum gate valve due to the lack of remaining space. This note presents the design of a vacuum-tight valve which allows the aperture of a skimmer to be closed by plugging a needle directly against its internal conical wall. The valve can be driven manually or pneumatically from outside the vacuum chamber. The helium conductance of the valve was measured to be better than 1×10-8 mbar×l×s-1 for a helium partial pressure difference of 1 bar.

  9. Fluid-Structure Model of Lymphatic Valve and Vessel

    NASA Astrophysics Data System (ADS)

    Wolf, Ki; Ballard, Matthew; Nepiyushchikh, Zhanna; Razavi, Mohammad; Dixon, Brandon; Alexeev, Alexander

    The lymphatic system is a part of the circulatory system that performs a range of important functions such as transportation of interstitial fluid, fatty acid, and immune cells. The lymphatic vessels are composed of contractile walls to pump lymph against adverse pressure gradient and lymphatic valves that prevent back flow. Despite the importance of lymphatic system, the contribution of mechanical and geometric changes of lymphatic valves and vessels in pathologies of lymphatic dysfunction, such as lymphedema, is not well understood. We developed a coupled fluid-solid computational model to simultaneously simulate a lymphatic vessel, valve, and flow. A lattice Boltzmann model is used to represent the fluid component, while lattice spring model is used for the solid component of the lymphatic vessel, whose mechanical properties are derived experimentally. Behaviors such as lymph flow pattern and lymphatic valve performance against backflow and adverse pressure gradient under varied parameters of lymphatic valve and vessel geometry and mechanical properties are investigated to provide a better insight into the dynamics of lymphatic vessels, valves, and system and give insight into how they might fail in disease. NSF CMMI-1635133.

  10. Prognostics for Ground Support Systems: Case Study on Pneumatic Valves

    NASA Technical Reports Server (NTRS)

    Daigle, Matthew; Goebel, Kai

    2011-01-01

    Prognostics technologies determine the health (or damage) state of a component or sub-system, and make end of life (EOL) and remaining useful life (RUL) predictions. Such information enables system operators to make informed maintenance decisions and streamline operational and mission-level activities. We develop a model-based prognostics methodology for pneumatic valves used in ground support equipment for cryogenic propellant loading operations. These valves are used to control the flow of propellant, so failures may have a significant impact on launch availability. Therefore, correctly predicting when valves will fail enables timely maintenance that avoids launch delays and aborts. The approach utilizes mathematical models describing the underlying physics of valve degradation, and, employing the particle filtering algorithm for joint state-parameter estimation, determines the health state of the valve and the rate of damage progression, from which EOL and RUL predictions are made. We develop a prototype user interface for valve prognostics, and demonstrate the prognostics approach using historical pneumatic valve data from the Space Shuttle refueling system.

  11. Rotary-To-Axial Motion Converter For Valve

    NASA Technical Reports Server (NTRS)

    Reinicke, Robert H.; Mohtar, Rafic

    1991-01-01

    Nearly frictionless mechanism converts rotary motion into axial motion. Designed for use in electronically variable pressure-regulator valve. Changes rotary motion imparted by motor into translation that opens and closes valve poppet. Cables spaced equidistantly around edge of fixed disk support movable disk. As movable disk rotated, cables twist, lifting it. When rotated in opposite direction, cables untwist, lowering it. Spider disk helps to prevent cables from tangling. Requires no lubrication and insensitive to contamination in fluid flowing through valve.

  12. Bioprosthetic Valve Fracture to Facilitate Transcatheter Valve-in-Valve Implantation.

    PubMed

    Allen, Keith B; Chhatriwalla, Adnan K; Cohen, David J; Saxon, John T; Aggarwal, Sanjeev; Hart, Anthony; Baron, Suzanne; Davis, J Russell; Pak, Alex F; Dvir, Danny; Borkon, A Michael

    2017-11-01

    Valve-in-valve transcatheter aortic valve replacement is less effective in small surgical bioprostheses. We evaluated the feasibility of bioprosthetic valve fracture with a high-pressure balloon to facilitate valve-in-valve transcatheter aortic valve replacement. In vitro bench testing on aortic tissue valves was performed on 19-mm and 21-mm Mitroflow (Sorin, Milan, Italy), Magna and Magna Ease (Edwards Lifesciences, Irvine, CA), Trifecta and Biocor Epic (St. Jude Medical, Minneapolis, MN), and Hancock II and Mosaic (Medtronic, Minneapolis, MN). High-pressure balloons Tru Dilation, Atlas Gold, and Dorado (C.R. Bard, Murray Hill, NJ) were used to determine which valves could be fractured and at what pressure fracture occurred. Mitroflow, Magna, Magna Ease, Mosaic, and Biocor Epic surgical valves were successfully fractured using high-pressures balloon 1 mm larger than the labeled valve size whereas Trifecta and Hancock II surgical valves could not be fractured. Only the internal valve frame was fractured, and the sewing cuff was never disrupted. Manufacturer's rated burst pressures for balloons were exceeded, with fracture pressures ranging from 8 to 24 atmospheres depending on the surgical valve. Testing further demonstrated that fracture facilitated the expansion of previously constrained, underexpanded transcatheter valves (both balloon and self-expanding) to the manufacturer's recommended size. Bench testing demonstrates that the frame of most, but not all, bioprosthetic surgical aortic valves can be fractured using high-pressure balloons. The safety of bioprosthetic valve fracture to optimize valve-in-valve transcatheter aortic valve replacement in small surgical valves requires further clinical investigation. Copyright © 2017 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

  13. A repositionable valved stent for endovascular treatment of deteriorated bioprostheses.

    PubMed

    Zegdi, Rachid; Khabbaz, Ziad; Borenstein, Nicolas; Fabiani, Jean-Noël

    2006-10-03

    We report our animal experience of endovascular valve replacement (VR) of failed bioprosthesis (BP) using an original delivery catheter allowing repositioning of the valved stent (VS). Among the different devices designed for percutaneous VR, none has the potential for repositioning of a fully deployed VS. Five sheep underwent, on beating heart, tricuspid VR with a stented BP. Prolapse of 1 leaflet was induced by tearing. For the endovascular tricuspid VR, we used a VS constructed with a nitinol self-expandable stent and a porcine stentless aortic valve. We also used an original delivery catheter, allowing repositioning of the VS through a compression or relaxation mechanism of the stent. Epicardial echocardiography and right ventriculography showed severe tricuspid regurgitation, with a regurgitant jet extending to the inferior vena cava. After surgical exposure to the infrarenal inferior vena cava, the VS was successfully implanted inside the failed BP in all cases. Repositioning of the fully deployed VS was always possible. Echocardiographic and macroscopic studies revealed adequate VS positioning, excellent leaflet opening, and absence of any intraprosthetic or periprosthetic leak. Endovascular VR was easily performed in sheep with failed BP in the tricuspid position. The novel delivery catheter allowed adequate repositioning of our fully deployed VS before its definitive release. One may anticipate that the safety improvement conferred by this new technology will certainly favor the development of percutaneous VR in clinical practice.

  14. Reduction of the suction losses through reed valves in hermetic reciprocating compressors using a magnet coil

    NASA Astrophysics Data System (ADS)

    Hopfgartner, J.; Posch, S.; Zuber, B.; Almbauer, R.; Krischan, K.; Stangl, S.

    2017-08-01

    Reed valves are widely used in hermetic reciprocating compressors and are responsible for a large part of the thermodynamic losses. Especially, the suction valve, which is opened nearly during the whole suction stroke, has a big potential for improvement. Usually, suction valves are opened only by vacuum created by the moving piston and should be closed before the compression stroke starts to avoid a reversed mass-flow through the valve. Therefore, the valves are prestressed, which results on the other hand in a higher flow resistance. In this work, a suction valve is investigated, which is not closed by the preload of the valve but by an electromagnetic coil located in the suction muffler neck. Shortly before the piston reaches its bottom dead centre, voltage is applied to the coil and a magnetic force is generated which pulls the valve shut. Thereby, the flow resistance through the valve can be reduced by changing the preload on the reed valve because it is no longer needed to close the valve. The investigation of this adapted valve and the electromagnetic coil is firstly done by numerical simulations including fluid structure interactions of the reed valves of a reciprocating compressor and secondly by experiments made on a calorimeter test bench.

  15. Intracardiac echocardiography to diagnose pannus formation after aortic valve replacement.

    PubMed

    Yamamoto, Yoshiya; Ohara, Takahiro; Funada, Akira; Takahama, Hiroyuki; Amaki, Makoto; Hasegawa, Takuya; Sugano, Yasuo; Kanzaki, Hideaki; Anzai, Toshihisa

    2016-03-01

    A 66-year-old female, under regular follow-up for 20 years after aortic valve replacement (19-mm Carbomedics), presented dyspnea on effort and hypotension during hemodialysis. A transthoracic echocardiogram showed elevation of transvalvular velocity up to 4 m/s, but the structure around the aortic prosthesis was difficult to observe due to artifacts. Fluoroscopy revealed normal motion of the leaflets of the mechanical valve. Intracardiac echocardiography (ICE) revealed a pannus-like structure in the left ventricular outflow tract. Transesophageal echocardiogram also revealed this structure. ICE can visualize structural abnormalities around a prosthetic valve after cardiac surgery even in patients in whom conventional imaging modalities failed.

  16. Electrical isolation and characteristics of permanent magnet-actuated valves for PDMS microfluidics.

    PubMed

    Chen, Chang-Yu; Chen, Chang-Hung; Tu, Ting-Yuan; Lin, Cheng-Ming; Wo, Andrew M

    2011-02-21

    This paper presents a magnetically driven valve via a permanent magnet pressing a spacer against deformable polydimethylsiloxane (PDMS) to fully close a microchannel. Its ability for electrical isolation, time response, and resistance to backpressure are interrogated. Simulation of the valve closing process was commenced along with experimental verification. Effects of PDMS thickness, and dimension and aspect ratio of microchannels were characterized. Up to 10 GΩ electrical isolation was demonstrated, as well as 50-70 ms valve response and ∼200 kPa resistible pressure. On-demand actuation for arbitrary flow patterns further quantifies its utility. With advantages of simple fabrication, flexible valving location, and no external power requirement, the on/off valve could be leveraged for proof-of-concept microfluidic devices and other applications.

  17. Closed bore XMR (CBXMR) systems for aortic valve replacement: Active magnetic shielding of x-ray tubes

    PubMed Central

    Bracken, John A.; DeCrescenzo, Giovanni; Komljenovic, Philip; Lillaney, Prasheel V.; Fahrig, Rebecca; Rowlands, J. A.

    2009-01-01

    Hybrid closed bore x-ray∕MRI systems are being developed to improve the safety and efficacy of percutaneous aortic valve replacement procedures by harnessing the complementary strengths of the x-ray and MRI modalities in a single interventional suite without requiring patient transfer between two rooms. These systems are composed of an x-ray C-arm in close proximity (≈1 m) to an MRI scanner. The MRI magnetic fringe field can cause the electron beam in the x-ray tube to deflect. The deflection causes the x-ray field of view to shift position on the detector receptacle. This could result in unnecessary radiation exposure to the patient and the staff in the cardiac catheterization laboratory. Therefore, the electron beam deflection must be corrected. The authors developed an active magnetic shielding system that can correct for electron beam deflection to within an accuracy of 5% without truncating the field of view or increasing exposure to the patient. This system was able to automatically adjust to different field strengths as the external magnetic field acting on the x-ray tube was changed. Although a small torque was observed on the shielding coils of the active shielding system when they were placed in a magnetic field, this torque will not impact their performance if they are securely mounted on the x-ray tube and the C-arm. The heating of the coils of the shielding system for use in the clinic caused by electric current was found to be slow enough not to require a dedicated cooling system for one percutaneous aortic valve replacement procedure. However, a cooling system will be required if multiple procedures are performed in one session. PMID:19544789

  18. Thrombogenic potential of transcatheter aortic valve implantation with trivial paravalvular leakage

    PubMed Central

    Siegel, Rolland

    2014-01-01

    Background Significant paravalvular leakage after transcatheter aortic valve implantation (TAVI) correlates with increased morbidity and mortality, but adverse consequences of trivial paravalvular leakage have stimulated few investigations. Using a unique method distinctly different from other diagnostic approaches, we previously reported elevated backflow velocities of short duration (transients) in mechanical valve closure. In this study, similar transients were found in a transcatheter valve paravalvular leakage avatar. Methods Paravalvular leakage rate (zero to 58 mL/second) and aortic valve incompetence (volumetric back flow/forward flow; zero to 32%) were made adjustable using a mock transcatheter aortic valve device and tested in quasi-steady and pulsatile flow test systems. Projected dynamic valve area (PDVA) from the back illuminated mock transcatheter aortic valve device was measured and regional backflow velocities were derived by dividing volumetric flow rate by the PDVA over the open and closing valve phase and the total closed valve area derived from backflow leakage. Results Aortic incompetence from 1-32% generated negative backflow transients from 8 to 267 meters/second, a range not dissimilar to that measured in mechanical valves with zero paravalvular leakage. Optimal paravalvular leakage was identified; not too small generating high backflow transients, not too large considering volume overload and cardiac energy loss caused by defective valve behavior and fluid motion. Conclusions Thrombogenic potential of transcatheter aortic valves with trivial aortic incompetence and high magnitude regional backflow velocity transients was comparable to mechanical valves. This may have relevance to stroke rate, asymptomatic microembolic episodes and indications for anticoagulation therapy after transcatheter valve insertion. PMID:25333018

  19. Electromechanically Actuated Valve for Controlling Flow Rate

    NASA Technical Reports Server (NTRS)

    Patterson, Paul

    2007-01-01

    A proposed valve for controlling the rate of flow of a fluid would include an electric-motor-driven ball-screw mechanism for adjusting the seating element of the valve to any position between fully closed and fully open. The motor would be of a type that can be electronically controlled to rotate to a specified angular position and to rotate at a specified rate, and the ball screw would enable accurate linear positioning of the seating element as a function of angular position of the motor. Hence, the proposed valve would enable fine electronic control of the rate of flow and the rate of change of flow. The uniqueness of this valve lies in a high degree of integration of the actuation mechanism with the flow-control components into a single, relatively compact unit. A notable feature of this integration is that in addition to being a major part of the actuation mechanism, the ball screw would also be a flow-control component: the ball screw would be hollow so as to contain part of the main flow passage, and one end of the ball screw would be the main seating valve element. The relationships among the components of the valve are best understood by reference to the figure, which presents meridional cross sections of the valve in the fully closed and fully open positions. The motor would be supported by a bracket bolted to the valve body. By means of gears or pulleys and a timing belt, motor drive would be transmitted to a sleeve that would rotate on bearings in the valve body. A ball nut inside the sleeve would be made to rotate with the sleeve by use of a key. The ball screw would pass through and engage the ball nut. A key would prevent rotation of the ball screw in the valve body while allowing the ball screw to translate axially when driven by the ball nut. The outer surface of the ball screw would be threaded only in a mid-length region: the end regions of the outer surface of the ball screw would be polished so that they could act as dynamic sealing surfaces

  20. System for remotely servicing a top loading captive ball valve

    DOEpatents

    Berry, Stephen M.; Porter, Matthew L.

    1996-01-01

    An attachment for facilitating servicing of a valve, the valve including: an assembly composed of a valve seat defining a flow path, a flow control member movable relative to the valve seat for blocking or unblocking the valve seat, and a control device including a stem coupled to the flow control member and operable for moving the flow control member relative to the valve seat; a housing for receiving the assembly, the housing having an opening via which the assembly can be removed from, and installed in, the housing, and the housing having a plurality of threaded studs which surround the opening and project away from the housing; a valve housing cover for closing and sealing the opening in the housing, the cover having a first bore for passage of the stem of the control device when the assembly is installed in the housing and a plurality of second bores each located for passage of a respective stud when the cover closes the opening in the housing. A plurality of threaded nuts are engageable with the studs for securing the cover to the housing when the cover closes the opening in the housing, wherein the attachment comprises: a plurality of nut guide devices removable from the housing and each operatively associated with a respective stud for retaining a respective nut and guiding the respective nut into alignment with the respective stud to enable the respective nut to be rotated into engagement with the respective stud; and aligning the nut guide devices with the studs.

  1. Failure Analysis of Space Shuttle Orbiter Valve Poppet

    NASA Technical Reports Server (NTRS)

    Russell, Rick

    2010-01-01

    The poppet failed during STS-126 due to fatigue cracking that most likely was initiated during MDC ground-testing. This failure ultimately led to the discovery that the cracking problem was a generic issue effecting numerous poppets throughout the Shuttle program's history. This presentation has focused on the laboratory analysis of the failed hardware, but this analysis was only one aspect of a comprehensive failure investigation. One critical aspect of the overall investigation was modeling of the fluid flow through this valve to determine the possible sources of cyclic loading. This work has led to the conclusion that the poppets are failing due to flow-induced vibration.

  2. Electrical Textile Valves for Paper Microfluidics.

    PubMed

    Ainla, Alar; Hamedi, Mahiar M; Güder, Firat; Whitesides, George M

    2017-10-01

    This paper describes electrically-activated fluidic valves that operate based on electrowetting through textiles. The valves are fabricated from electrically conductive, insulated, hydrophobic textiles, but the concept can be extended to other porous materials. When the valve is closed, the liquid cannot pass through the hydrophobic textile. Upon application of a potential (in the range of 100-1000 V) between the textile and the liquid, the valve opens and the liquid penetrates the textile. These valves actuate in less than 1 s, require low energy (≈27 µJ per actuation), and work with a variety of aqueous solutions, including those with low surface tension and those containing bioanalytes. They are bistable in function, and are, in a sense, the electrofluidic analog of thyristors. They can be integrated into paper microfluidic devices to make circuits that are capable of controlling liquid, including autonomous fluidic timers and fluidic logic. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Conical Seat Shut-Off Valve

    NASA Technical Reports Server (NTRS)

    Farner, Bruce

    2013-01-01

    A moveable valve for controlling flow of a pressurized working fluid was designed. This valve consists of a hollow, moveable floating piston pressed against a stationary solid seat, and can use the working fluid to seal the valve. This open/closed, novel valve is able to use metal-to-metal seats, without requiring seat sliding action; therefore there are no associated damaging effects. During use, existing standard high-pressure ball valve seats tend to become damaged during rotation of the ball. Additionally, forces acting on the ball and stem create large amounts of friction. The combination of these effects can lead to system failure. In an attempt to reduce damaging effects and seat failures, soft seats in the ball valve have been eliminated; however, the sliding action of the ball across the highly loaded seat still tends to scratch the seat, causing failure. Also, in order to operate, ball valves require the use of large actuators. Positioning the metal-to-metal seats requires more loading, which tends to increase the size of the required actuator, and can also lead to other failures in other areas such as the stem and bearing mechanisms, thus increasing cost and maintenance. This novel non-sliding seat surface valve allows metal-to-metal seats without the damaging effects that can lead to failure, and enables large seating forces without damaging the valve. Additionally, this valve design, even when used with large, high-pressure applications, does not require large conventional valve actuators and the valve stem itself is eliminated. Actuation is achieved with the use of a small, simple solenoid valve. This design also eliminates the need for many seals used with existing ball valve and globe valve designs, which commonly cause failure, too. This, coupled with the elimination of the valve stem and conventional valve actuator, improves valve reliability and seat life. Other mechanical liftoff seats have been designed; however, they have only resulted in

  4. Valve replacement in children: a challenge for a whole life.

    PubMed

    Henaine, Roland; Roubertie, François; Vergnat, Mathieu; Ninet, Jean

    2012-10-01

    Valvular pathology in infants and children poses numerous challenges to the paediatric cardiac surgeon. Without question, valvular repair is the goal of intervention because restoration of valvular anatomy and physiology using native tissue allows for growth and a potentially better long-term outcome. When reconstruction fails or is not feasible, valve replacement becomes inevitable. Which valve for which position is controversial. Homograft and bioprosthetic valves achieve superior haemodynamic results initially but at the cost of accelerated degeneration. Small patient size and the risk of thromboembolism limit the usefulness of mechanical valves, and somatic outgrowth is an universal problem with all available prostheses. The goal of this article is to address valve replacement options for all four valve positions within the paediatric population. We review current literature and our practice to support our preferences. To summarize, a multitude of opinions and surgical experiences exist. Today, the valve choices that seem without controversy are bioprosthetic replacement of the tricuspid valve and Ross or Ross-Konno procedures when necessary for the aortic valve. On the other hand, bioprostheses may be implanted when annular pulmonary diameter is adequate; if not or in case of right ventricular outflow tract discontinuity, it is better to use a pulmonary homograft with the Ross procedure. Otherwise, a valved conduit. Mitral valve replacement remains the most problematic; the mechanical prosthesis must be placed in the annular position, avoiding oversizing. Future advances with tissue-engineered heart valves for all positions and new anticoagulants may change the landscape for valve replacement in the paediatric population. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

  5. Safe-trajectory optimization and tracking control in ultra-close proximity to a failed satellite

    NASA Astrophysics Data System (ADS)

    Zhang, Jingrui; Chu, Xiaoyu; Zhang, Yao; Hu, Quan; Zhai, Guang; Li, Yanyan

    2018-03-01

    This paper presents a trajectory-optimization method for a chaser spacecraft operating in ultra-close proximity to a failed satellite. Based on the combination of active and passive trajectory protection, the constraints in the optimization framework are formulated for collision avoidance and successful docking in the presence of any thruster failure. The constraints are then handled by an adaptive Gauss pseudospectral method, in which the dynamic residuals are used as the metric to determine the distribution of collocation points. A finite-time feedback control is further employed in tracking the optimized trajectory. In particular, the stability and convergence of the controller are proved. Numerical results are given to demonstrate the effectiveness of the proposed methods.

  6. Factors influencing mortality after bioprosthetic valve replacement; a midterm outcome.

    PubMed

    Javadzadegan, Hassan; Javadzadegan, Amir; Mehdizadeh Baghbani, Jafar

    2013-01-01

    Although valve repair is applied routinely nowadays, particularly for mitral regurgitation (MR) or tricuspid regurgitation (TR), valve replacement using prosthetic valves is also common especially in adults. Unfortunately the valve with ideal hemodynamic performance and long-term durability without increasing the risk of bleeding due to long-term anticoagulant therapy has not been introduced. Therefore, patients and physicians must choose either bioprosthetic or mechanical valves. Currently, there is an increasing clinical trend of using bioprosthetic valves instead of mechanical valves even in young patients apparently because of their advantages. Seventy patients undergone valvular replacement using bioprosthetic valves were evaluated by ECG and Echocardiography to assess the rhythm and ejection fracture. Mean follow-up time was 33 months (min 9, max 92). Mortality rate was 25.9% (n=18) within 8 years of follow-up. Statistical analysis showed a significant relation between atrial fibrillation rhythm and mortality (P=0.02). Morbidities occurred in 30 patients (42.8%). Significant statistical relation was found between the morbidities and age over 65 years old (P=0.005). In follow-up period, 4 cases (5.7%) underwent re-operation due to global valve dysfunction. Our study shows that using biprosthetic valve could reduce the risk of morbidity occurrence in patient who needs valve replacement. However, if medical treatments fail, patients should be referred for surgery. This would reduce the risk of mortality because of lower incident of complications such as atrial fibrillation and morbidities due to younger patients' population.

  7. Outcomes following balloon mitral valvuloplasty in pregnant females with mitral stenosis and significant sub valve disease with severe decompensated heart failure.

    PubMed

    Ananthakrishna Pillai, Ajith; Ramasamy, Chandramohan; V, Saranya Gousy; Kottyath, Harichandrakumar

    2018-03-11

    Mitral stenosis may present with decompensated heart failure during pregnancy. Many patients do have advanced sub valve disease and present late with decompensated state. The outcomes of balloon mitral valvuloplasty (BMV) in such advanced sub valve disease with severe heart failure in pregnancy has not been specifically studied till now. A descriptive study looking at the immediate and long-term outcomes of pregnant patients with MS who presented with severe heart failure and sub valve disease who had undergone BMV. Ninety-six patients were studied. The mean gestational age was 23.4 ± 10.9 weeks .Mean SpO2 was 89% at admission,17% were in cardiogenic shock and 33.33 were on mechanical ventilation. The mean Wilkin's score was 9.71 ± 2.1 and sub valve score was 3.3 ± 0.12. BMV was successful in 77 (80.2%) patients and failed in 19. In 5.2% cases, acute severe MR occurred. There were 11 maternal deaths (six in failed and five in success group). A successful obstetric outcome was seen in 71 patients in success (92%) and 11/19 (57%) in failed (P < 0.001). The obstetric outcomes were better in success versus failure group. Anova post hoc analysis showed sustained gradient reductions at 1 and 5 year follow-up (P = 0.03) in success group. BMV offers substantial improvement in clinical outcomes among pregnant patients with MS and heart failure even with severe sub valve disease. The morality rate among failed was high at 31%. The obstetric outcomes were poor after a failed BMV. Outcomes following balloon mitral valvuloplasty in pregnant females with mitral stenosis and significant sub valve disease with severe decompensated heart failure. © 2018, Wiley Periodicals, Inc.

  8. Internal combustion engine with rotary valve assembly having variable intake valve timing

    DOEpatents

    Hansen, Craig N.; Cross, Paul C.

    1995-01-01

    An internal combustion engine has rotary valves associated with movable shutters operable to vary the closing of intake air/fuel port sections to obtain peak volumetric efficiency over the entire range of speed of the engine. The shutters are moved automatically by a control mechanism that is responsive to the RPM of the engine. A foot-operated lever associated with the control mechanism is also used to move the shutters between their open and closed positions.

  9. Stem thrust prediction model for W-K-M double wedge parallel expanding gate valves

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Eldiwany, B.; Alvarez, P.D.; Wolfe, K.

    1996-12-01

    An analytical model for determining the required valve stem thrust during opening and closing strokes of W-K-M parallel expanding gate valves was developed as part of the EPRI Motor-Operated Valve Performance Prediction Methodology (EPRI MOV PPM) Program. The model was validated against measured stem thrust data obtained from in-situ testing of three W-K-M valves. Model predictions show favorable, bounding agreement with the measured data for valves with Stellite 6 hardfacing on the disks and seat rings for water flow in the preferred flow direction (gate downstream). The maximum required thrust to open and to close the valve (excluding wedging andmore » unwedging forces) occurs at a slightly open position and not at the fully closed position. In the nonpreferred flow direction, the model shows that premature wedging can occur during {Delta}P closure strokes even when the coefficients of friction at different sliding surfaces are within the typical range. This paper summarizes the model description and comparison against test data.« less

  10. Sliding-gate valve for use with abrasive materials

    DOEpatents

    Ayers, Jr., William J.; Carter, Charles R.; Griffith, Richard A.; Loomis, Richard B.; Notestein, John E.

    1985-01-01

    The invention is a flow and pressure-sealing valve for use with abrasive solids. The valve embodies special features which provide for long, reliable operating lifetimes in solids-handling service. The valve includes upper and lower transversely slidable gates, contained in separate chambers. The upper gate provides a solids-flow control function, whereas the lower gate provides a pressure-sealing function. The lower gate is supported by means for (a) lifting that gate into sealing engagement with its seat when the gate is in its open and closed positions and (b) lowering the gate out of contact with its seat to permit abrasion-free transit of the gate between its open and closed positions. When closed, the upper gate isolates the lower gate from the solids. Because of this shielding action, the sealing surface of the lower gate is not exposed to solids during transit or when it is being lifted or lowered. The chamber containing the lower gate normally is pressurized slightly, and a sweep gas is directed inwardly across the lower-gate sealing surface during the vertical translation of the gate.

  11. Development of myoelectric control type speaking valve with low flow resistance

    NASA Astrophysics Data System (ADS)

    Ooe, Katsutoshi; Sakurai, Kohei; Mimaki, Shinya

    2015-12-01

    We aimed to develop welfare devices for patients with phonation disorder. One of these devices is the electrical controltype speaking valve system. The conventional speaking valves have one-way valve architecture, they open when the user breathes in, and they close when user breathes out and produce voices. This type is very simple and tough, but some users feel closeness in case of exhalation without phonation. This problem is caused by its mechanism what can not be controlled by user's will. Therefore, we proposed an electrical control-type speaking valve system to resolve this problem. This valve is controlled by neck myoelectric signal of sternohyoid muscle. From our previous report, it was clarified that this valve had better performance about easy-to-breath. Furthermore, we proposed the compact myoelectric control-type speaking valve system. The new-type speaking valve was enough small to attach the human body, and its opening area is larger than that of conventional one. Additionally, we described the improvement of flow channel shape by using of FEM analysis. According to the result of the analysis, it was clarified that the shape-improved speaking valve gets the low flow resistance channel in case of inspiration. In this report, we tried to make the flow resistance lower by the shape of current plates, in case of both inspiration and exhalation. From the result of FEM analysis, our speaking valve could get better flow channel than older one.

  12. Transient Flows in a Pipe System with Pump Shut-Down and the Simultaneous Closing of a Spherical Valve

    NASA Astrophysics Data System (ADS)

    Zhang, Zh.

    2016-11-01

    Because of the limited value of the wave propagation speed in water the propagation of a pressure surge in transient flows can be tracked in the time series. This enables both the pressure head and the flow velocity in pipe flows to be determined as a function of both the coordinate along the pipe and the time. The propagation of the pressure surge includes both wave transmission and reflection. The latter occurs where the flow section is changed. The wave tracking method has been demonstrated as highly accurate and subsequently was applied to much more complex hydraulic systems, in which the pump is shut off and the spherical valve is simultaneously progressively closed. A combined four-quadrant characteristic of the pump and a spherical valve has been worked out, with which the computational procedure for the transient flow in the complex system could be significantly simplified. It has been demonstrated that not only the pressure surge in the hydraulic system but also the rotational speed of the pump could be satisfactorily computed. The computational algorithm has been demonstrated as quite simple, so that all calculations could be performed simply by means of the Microsoft Excel module.

  13. Durability Tests of Ball Valve Prototype with Flowmeter Operation

    NASA Astrophysics Data System (ADS)

    Rogula, J.; Romanik, G.

    2018-02-01

    The results of the investigation of the prototypical ball valve are presented in this article. The innovation of the tested valve is a ball with a built-in measuring orifice. The valve has been subjected to durability tests. Leakage under three temperatures: ambient, -30°C and +100°C was analyzed. Sealing elements of the valve were tested for roughness and deviation of shape before and after the cycles of operation. Ball valve operation means cycles of open/close. It was planned to perform 1000 cycles at each temperature condition accordingly. Tests of the valve were performed under gas pressure equal to 10 MPa. The research was carried out under the Operational Program "Intelligent Development" (POIR 01.01.01-00-0013 / 15 "Development of devices for measurement of media flow on industrial trunk-lines".

  14. Development of a fast valve for mitigating disruptions in tokamaks

    NASA Astrophysics Data System (ADS)

    Savtchkov, A.; Finken, K. H.; Mank, G.

    2002-10-01

    In support of our disruption mitigation profram, a fast gas valve has been constructed and tested on TEXTOR at FZJ Juelich. Its main features have been shown to be: (1) rapid response time: 0.5 ms; (2) amount of injected gas: variable, 2-1000 mbar×l; (3) linear dependence of the number of injected particles on the gas pressure; (4) capability of working in a strong magnetic field; (5) sort of gas: any. The valve has the standard CF 35 flange, commonly used in vacuum engineering. All the components that have contact with vacuum were made of stainless steel, except for the closing aluminum piston. To prevent gas leaking directly from the bottles to the experimental vessel there are also two safety valves, closing the bottles before the shot. The required control equipment includes a high power supply and the combined controller for the safety valves and baratrons, both being able to work with TTL control signals. During tests and experiments on TEXTOR and ASDEX-Upgrade, the valve showed successful operation with three gas types: He, Ne, Ar.

  15. Bioprosthetic Valve Fracture Improves the Hemodynamic Results of Valve-in-Valve Transcatheter Aortic Valve Replacement.

    PubMed

    Chhatriwalla, Adnan K; Allen, Keith B; Saxon, John T; Cohen, David J; Aggarwal, Sanjeev; Hart, Anthony J; Baron, Suzanne J; Dvir, Danny; Borkon, A Michael

    2017-07-01

    Valve-in-valve (VIV) transcatheter aortic valve replacement (TAVR) may be less effective in small surgical valves because of patient/prosthesis mismatch. Bioprosthetic valve fracture (BVF) using a high-pressure balloon can be performed to facilitate VIV TAVR. We report data from 20 consecutive clinical cases in which BVF was successfully performed before or after VIV TAVR by inflation of a high-pressure balloon positioned across the valve ring during rapid ventricular pacing. Hemodynamic measurements and calculation of the valve effective orifice area were performed at baseline, immediately after VIV TAVR, and after BVF. BVF was successfully performed in 20 patients undergoing VIV TAVR with balloon-expandable (n=8) or self-expanding (n=12) transcatheter valves in Mitroflow, Carpentier-Edwards Perimount, Magna and Magna Ease, Biocor Epic and Biocor Epic Supra, and Mosaic surgical valves. Successful fracture was noted fluoroscopically when the waist of the balloon released and by a sudden drop in inflation pressure, often accompanied by an audible snap. BVF resulted in a reduction in the mean transvalvular gradient (from 20.5±7.4 to 6.7±3.7 mm Hg, P <0.001) and an increase in valve effective orifice area (from 1.0±0.4 to 1.8±0.6 cm 2 , P <0.001). No procedural complications were reported. BVF can be performed safely in small surgical valves to facilitate VIV TAVR with either balloon-expandable or self-expanding transcatheter valves and results in reduced residual transvalvular gradients and increased valve effective orifice area. © 2017 American Heart Association, Inc.

  16. Tricuspid valve endocarditis

    PubMed Central

    Hussain, Syed T.; Witten, James; Shrestha, Nabin K.; Blackstone, Eugene H.

    2017-01-01

    Right-sided infective endocarditis (RSIE) is less common than left-sided infective endocarditis (IE), encompassing only 5–10% of cases of IE. Ninety percent of RSIE involves the tricuspid valve (TV). Given the relatively small numbers of TVIE cases operated on at most institutions, the purpose of this review is to highlight and discuss the current understanding of IE involving the TV. RSIE and TVIE are strongly associated with intravenous drug use (IVDU), although pacemaker leads, defibrillator leads and vascular access for dialysis are also major risk factors. Staphylococcus aureus is the predominant causative organism in TVIE. Most patients with TVIE are successfully treated with antibiotics, however, 5–16% of RSIE cases eventually require surgical intervention. Indications and timing for surgery are less clear than for left-sided IE; surgery is primarily considered for failed medical therapy, large vegetations and septic pulmonary embolism, and less often for TV regurgitation and heart failure. Most patients with an infected prosthetic TV will require surgery. Concomitant left-sided IE has its own surgical indications. Earlier surgical intervention may potentially prevent further destruction of leaflet tissue and increase the likelihood of TV repair. Fortunately, TV debridement and repair can be accomplished in most cases, even those with extensive valve destruction, using a variety of techniques. Valve repair is advocated over replacement, particularly in IVDUs patients who are young, non-compliant and have a higher risk of recurrent infection and reoperation with valve replacement. Excising the valve without replacing, it is not advocated; it has been reported previously, but these patients are likely to be symptomatic, particularly in cases with septic pulmonary embolism and increased pulmonary vascular resistance. Patients with concomitant left-sided involvement have worse prognosis than those with RSIE alone, due predominantly to greater likelihood of

  17. Factors Influencing Mortality after Bioprosthetic Valve Replacement; A Midterm Outcome

    PubMed Central

    Javadzadegan, Hassan; Javadzadegan, Amir; Mehdizadeh Baghbani, Jafar

    2013-01-01

    Introduction: Although valve repair is applied routinely nowadays, particularly for mitral regurgitation (MR) or tricuspid regurgitation (TR), valve replacement using prosthetic valves is also common especially in adults. Unfortunately the valve with ideal hemodynamic performance and long-term durability without increasing the risk of bleeding due to long-term anticoagulant therapy has not been introduced. Therefore, patients and physicians must choose either bioprosthetic or mechanical valves. Currently, there is an increasing clinical trend of using bioprosthetic valves instead of mechanical valves even in young patients apparently because of their advantages. Methods: Seventy patients undergone valvular replacement using bioprosthetic valves were evaluated by ECG and Echocardiography to assess the rhythm and ejection fracture. Mean follow-up time was 33 months (min 9, max 92). Results: Mortality rate was 25.9% (n=18) within 8 years of follow-up. Statistical analysis showed a significant relation between atrial fibrillation rhythm and mortality (P=0.02). Morbidities occurred in 30 patients (42.8%). Significant statistical relation was found between the morbidities and age over 65 years old (P=0.005). In follow-up period, 4 cases (5.7%) underwent re-operation due to global valve dysfunction. Conclusion: Our study shows that using biprosthetic valve could reduce the risk of morbidity occurrence in patient who needs valve replacement. However, if medical treatments fail, patients should be referred for surgery. This would reduce the risk of mortality because of lower incident of complications such as atrial fibrillation and morbidities due to younger patients' population. PMID:24404348

  18. System for remotely servicing a top loading captive ball valve

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Berry, S.M.; Porter, M.L.

    1996-06-25

    An attachment for facilitating servicing of a valve is disclosed including: an assembly composed of a valve seat defining a flow path, a flow control member movable relative to the valve seat for blocking or unblocking the valve seat, and a control device including a stem coupled to the flow control member and operable for moving the flow control member relative to the valve seat; a housing for receiving the assembly, the housing having an opening via which the assembly can be removed from, and installed in, the housing, and the housing having a plurality of threaded studs which surroundmore » the opening and project away from the housing; a valve housing cover for closing and sealing the opening in the housing, the cover having a first bore for passage of the stem of the control device when the assembly is installed in the housing and a plurality of second bores each located for passage of a respective stud when the cover closes the opening in the housing. A plurality of threaded nuts are engageable with the studs for securing the cover to the housing when the cover closes the opening in the housing, wherein the attachment comprises: a plurality of nut guide devices removable from the housing and each operatively associated with a respective stud for retaining a respective nut and guiding the respective nut into alignment with the respective stud to enable the respective nut to be rotated into engagement with the respective stud; and aligning the nut guide devices with the studs. 7 figs.« less

  19. System for remotely servicing a top loading captive ball valve

    DOEpatents

    Berry, S.M.; Porter, M.L.

    1996-06-25

    An attachment for facilitating servicing of a valve is disclosed including: an assembly composed of a valve seat defining a flow path, a flow control member movable relative to the valve seat for blocking or unblocking the valve seat, and a control device including a stem coupled to the flow control member and operable for moving the flow control member relative to the valve seat; a housing for receiving the assembly, the housing having an opening via which the assembly can be removed from, and installed in, the housing, and the housing having a plurality of threaded studs which surround the opening and project away from the housing; a valve housing cover for closing and sealing the opening in the housing, the cover having a first bore for passage of the stem of the control device when the assembly is installed in the housing and a plurality of second bores each located for passage of a respective stud when the cover closes the opening in the housing. A plurality of threaded nuts are engageable with the studs for securing the cover to the housing when the cover closes the opening in the housing, wherein the attachment comprises: a plurality of nut guide devices removable from the housing and each operatively associated with a respective stud for retaining a respective nut and guiding the respective nut into alignment with the respective stud to enable the respective nut to be rotated into engagement with the respective stud; and aligning the nut guide devices with the studs. 7 figs.

  20. Outcomes of Heimlich valve drainage in dogs.

    PubMed

    Salci, H; Bayram, A S; Gorgul, O S

    2009-04-01

    Retrospective study of the outcomes of Heimlich valve drainage in dogs. Medical records of the past 3 years were retrospectively reviewed. Heimlich valve drainage was used in 34 dogs (median body weight 30 +/- 5 kg): lobectomy (n = 15), pneumonectomy (n = 9), intrathoracic oesophageal surgery (n = 2), diaphragmatic hernia repair (n = 1), traumatic open pneumothorax (n = 2), bilobectomy (n = 2), ligation of the thoracic duct (n = 1), and chylothorax and pneumothorax (n = 1 each). Evacuation of air and/or fluid from the pleural cavity was performed with the Heimlich valve following thoracostomy tube insertion. During drainage, the dogs were closely monitored for possible respiratory failure. Termination of Heimlich valve drainage was controlled with underwater seal drainage and assessed with thoracic radiography. Negative intrathoracic pressure was provided in 29 dogs without any complications. Post pneumonectomy respiratory syncope and post lobectomy massive hemothorax, which did not originate from the Heimlich valve, were the only postoperative complications. Dysfunction of the valve diaphragm, open pneumothorax and intrathoracic localisation of an acute gastric dilatation-volvulus syndrome caused by a left-sided diaphragmatic hernia following pneumonectomy were the Heimlich valve drainage complications. The Heimlich valve can be used as a continuous drainage device in dogs, but the complications reported here should be considered by veterinary practitioners.

  1. Fault Diagnosis of Internal Combustion Engine Valve Clearance Using the Impact Commencement Detection Method

    PubMed Central

    Jiang, Zhinong; Wang, Zijia; Zhang, Jinjie

    2017-01-01

    Internal combustion engines (ICEs) are widely used in many important fields. The valve train clearance of an ICE usually exceeds the normal value due to wear or faulty adjustment. This work aims at diagnosing the valve clearance fault based on the vibration signals measured on the engine cylinder heads. The non-stationarity of the ICE operating condition makes it difficult to obtain the nominal baseline, which is always an awkward problem for fault diagnosis. This paper overcomes the problem by inspecting the timing of valve closing impacts, of which the referenced baseline can be obtained by referencing design parameters rather than extraction during healthy conditions. To accurately detect the timing of valve closing impact from vibration signals, we carry out a new method to detect and extract the commencement of the impacts. The results of experiments conducted on a twelve-cylinder ICE test rig show that the approach is capable of extracting the commencement of valve closing impact accurately and using only one feature can give a superior monitoring of valve clearance. With the help of this technique, the valve clearance fault becomes detectable even without the comparison to the baseline, and the changing trend of the clearance could be trackable. PMID:29244722

  2. Fault Diagnosis of Internal Combustion Engine Valve Clearance Using the Impact Commencement Detection Method.

    PubMed

    Jiang, Zhinong; Mao, Zhiwei; Wang, Zijia; Zhang, Jinjie

    2017-12-15

    Internal combustion engines (ICEs) are widely used in many important fields. The valve train clearance of an ICE usually exceeds the normal value due to wear or faulty adjustment. This work aims at diagnosing the valve clearance fault based on the vibration signals measured on the engine cylinder heads. The non-stationarity of the ICE operating condition makes it difficult to obtain the nominal baseline, which is always an awkward problem for fault diagnosis. This paper overcomes the problem by inspecting the timing of valve closing impacts, of which the referenced baseline can be obtained by referencing design parameters rather than extraction during healthy conditions. To accurately detect the timing of valve closing impact from vibration signals, we carry out a new method to detect and extract the commencement of the impacts. The results of experiments conducted on a twelve-cylinder ICE test rig show that the approach is capable of extracting the commencement of valve closing impact accurately and using only one feature can give a superior monitoring of valve clearance. With the help of this technique, the valve clearance fault becomes detectable even without the comparison to the baseline, and the changing trend of the clearance could be trackable.

  3. Split Venturi, Axially-Rotated Valve

    DOEpatents

    Walrath, David E.; Lindberg, William R.; Burgess, Robert K.

    2000-08-29

    The present invention provides an axially-rotated valve which permits increased flow rates and lower pressure drop (characterized by a lower loss coefficient) by using an axial eccentric split venturi with two portions where at least one portion is rotatable with respect to the other portion. The axially-rotated valve typically may be designed to avoid flow separation and/or cavitation at full flow under a variety of conditions. Similarly, the valve is designed, in some embodiments, to produce streamlined flow within the valve. A typical cross section of the eccentric split venturi may be non-axisymmetric such as a semicircular cross section which may assist in both throttling capabilities and in maximum flow capacity using the design of the present invention. Such a design can include applications for freeze resistant axially-rotated valves and may be fully-opened and fully-closed in one-half of a complete rotation. An internal wide radius elbow typically connected to a rotatable portion of the eccentric venturi may assist in directing flow with lower friction losses. A valve actuator may actuate in an axial manner yet be uniquely located outside of the axial flow path to further reduce friction losses. A seal may be used between the two portions that may include a peripheral and diametrical seal in the same plane.

  4. Propionibacterium acnes endophthalmitis in Ahmed glaucoma valve.

    PubMed

    Gutiérrez-Díaz, E; Montero-Rodríguez, M; Mencía-Gutiérrez, E; Fernández-González, M C; Pérez-Blázquez, E

    2001-01-01

    To report a case of Propionibacterium acnes endophthalmitis in a patient with an Ahmed glaucoma valve. A nine-year-old boy with bilateral congenital glaucoma, with an Ahmed glaucoma valve implanted in the left eye, had recurrent conjunctival dehiscence and endophthalmitis. Vitreous cultures demonstrated the presence of Propionibacterium acnes. This is the first reported case of Propionibacterium acnes endophthalmitis in an Ahmed glaucoma valve and the second one in a glaucoma drainage device. We strongly recommend using a patch graft to prevent and treat tube exposure. Conjunctival grafts may be useful to close the conjunctiva when there is marked scarring to prevent patch exposure and melting or extrusion.

  5. Fast image-based mitral valve simulation from individualized geometry.

    PubMed

    Villard, Pierre-Frederic; Hammer, Peter E; Perrin, Douglas P; Del Nido, Pedro J; Howe, Robert D

    2018-04-01

    Common surgical procedures on the mitral valve of the heart include modifications to the chordae tendineae. Such interventions are used when there is extensive leaflet prolapse caused by chordae rupture or elongation. Understanding the role of individual chordae tendineae before operating could be helpful to predict whether the mitral valve will be competent at peak systole. Biomechanical modelling and simulation can achieve this goal. We present a method to semi-automatically build a computational model of a mitral valve from micro CT (computed tomography) scans: after manually picking chordae fiducial points, the leaflets are segmented and the boundary conditions as well as the loading conditions are automatically defined. Fast finite element method (FEM) simulation is carried out using Simulation Open Framework Architecture (SOFA) to reproduce leaflet closure at peak systole. We develop three metrics to evaluate simulation results: (i) point-to-surface error with the ground truth reference extracted from the CT image, (ii) coaptation surface area of the leaflets and (iii) an indication of whether the simulated closed leaflets leak. We validate our method on three explanted porcine hearts and show that our model predicts the closed valve surface with point-to-surface error of approximately 1 mm, a reasonable coaptation surface area, and absence of any leak at peak systole (maximum closed pressure). We also evaluate the sensitivity of our model to changes in various parameters (tissue elasticity, mesh accuracy, and the transformation matrix used for CT scan registration). We also measure the influence of the positions of the chordae tendineae on simulation results and show that marginal chordae have a greater influence on the final shape than intermediate chordae. The mitral valve simulation can help the surgeon understand valve behaviour and anticipate the outcome of a procedure. Copyright © 2018 John Wiley & Sons, Ltd.

  6. ELECTROSTRICTION VALVE

    DOEpatents

    Kippenhan, D.O.

    1962-09-25

    An accurately controlled, pulse gas valve is designed capable of delivering output pulses which vary in length from one-tenth millisecond to one second or more, repeated at intervals of a few milliseconds or- more. The pulsed gas valve comprises a column formed of barium titanate discs mounted in stacked relation and electrically connected in parallel, with means for applying voltage across the discs to cause them to expand and effect a mechanical elongation axially of the column. The column is mounted within an enclosure having an inlet port and an outlet port with an internal seat in communication with the outlet port, such that a plug secured to the end of the column will engage the seat of the outlet port to close the outlet port in response to the application of voltage is regulated by a conventional electronic timing circuit connected to the column. (AEC)

  7. Novel Active Combustion Control Valve

    NASA Technical Reports Server (NTRS)

    Caspermeyer, Matt

    2014-01-01

    This project presents an innovative solution for active combustion control. Relative to the state of the art, this concept provides frequency modulation (greater than 1,000 Hz) in combination with high-amplitude modulation (in excess of 30 percent flow) and can be adapted to a large range of fuel injector sizes. Existing valves often have low flow modulation strength. To achieve higher flow modulation requires excessively large valves or too much electrical power to be practical. This active combustion control valve (ACCV) has high-frequency and -amplitude modulation, consumes low electrical power, is closely coupled with the fuel injector for modulation strength, and is practical in size and weight. By mitigating combustion instabilities at higher frequencies than have been previously achieved (approximately 1,000 Hz), this new technology enables gas turbines to run at operating points that produce lower emissions and higher performance.

  8. Non-linear control of a hydraulic piezo-valve using a generalised Prandtl-Ishlinskii hysteresis model

    NASA Astrophysics Data System (ADS)

    Stefanski, Frederik; Minorowicz, Bartosz; Persson, Johan; Plummer, Andrew; Bowen, Chris

    2017-01-01

    The potential to actuate proportional flow control valves using piezoelectric ceramics or other smart materials has been investigated for a number of years. Although performance advantages compared to electromagnetic actuation have been demonstrated, a major obstacle has proven to be ferroelectric hysteresis, which is typically 20% for a piezoelectric actuator. In this paper, a detailed study of valve control methods incorporating hysteresis compensation is made for the first time. Experimental results are obtained from a novel spool valve actuated by a multi-layer piezoelectric ring bender. A generalised Prandtl-Ishlinskii model, fitted to experimental training data from the prototype valve, is used to model hysteresis empirically. This form of model is analytically invertible and is used to compensate for hysteresis in the prototype valve both open loop, and in several configurations of closed loop real time control system. The closed loop control configurations use PID (Proportional Integral Derivative) control with either the inverse hysteresis model in the forward path or in a command feedforward path. Performance is compared to both open and closed loop control without hysteresis compensation via step and frequency response results. Results show a significant improvement in accuracy and dynamic performance using hysteresis compensation in open loop, but where valve position feedback is available for closed loop control the improvements are smaller, and so conventional PID control may well be sufficient. It is concluded that the ability to combine state-of-the-art multi-layer piezoelectric bending actuators with either sophisticated hysteresis compensation or closed loop control provides a route for the creation of a new generation of high performance piezoelectric valves.

  9. Chemical Safety Alert: Shaft Blow-Out Hazard of Check and Butterfly Valves

    EPA Pesticide Factsheets

    Certain types of check and butterfly valves can undergo shaft-disk separation and fail catastrophically, even when operated within their design limits of pressure and temperature, causing toxic/flammable gas releases, fires, and vapor cloud explosions.

  10. Remote fire stack igniter. [with solenoid-controlled valve

    NASA Technical Reports Server (NTRS)

    Ray, W. L. (Inventor)

    1974-01-01

    An igniter is described mounted on a vent stack with an upper, flame cage near the top of the stack to ignite emissions from the stack. The igniter is a tube with a lower, open, flared end having a spark plug near the lower end and a solenoid-controlled valve which supplies propane fuel from a supply tank. Propane from the tank is supplied at the top under control of a second, solenoid-controlled valve. The valve controlling the lower supply is closed after ignition at the flame cage. The igniter is economical, practical, and highly reliable.

  11. Fault detection and diagnosis of diesel engine valve trains

    NASA Astrophysics Data System (ADS)

    Flett, Justin; Bone, Gary M.

    2016-05-01

    This paper presents the development of a fault detection and diagnosis (FDD) system for use with a diesel internal combustion engine (ICE) valve train. A novel feature is generated for each of the valve closing and combustion impacts. Deformed valve spring faults and abnormal valve clearance faults were seeded on a diesel engine instrumented with one accelerometer. Five classification methods were implemented experimentally and compared. The FDD system using the Naïve-Bayes classification method produced the best overall performance, with a lowest detection accuracy (DA) of 99.95% and a lowest classification accuracy (CA) of 99.95% for the spring faults occurring on individual valves. The lowest DA and CA values for multiple faults occurring simultaneously were 99.95% and 92.45%, respectively. The DA and CA results demonstrate the accuracy of our FDD system for diesel ICE valve train fault scenarios not previously addressed in the literature.

  12. The Leipzig experience with robotic valve surgery.

    PubMed

    Autschbach, R; Onnasch, J F; Falk, V; Walther, T; Krüger, M; Schilling, L O; Mohr, F W

    2000-01-01

    The study describes the single-center experience using robot-assisted videoscopic mitral valve surgery and the early results with a remote telemanipulator-assisted approach for mitral valve repair. Out of a series of 230 patients who underwent minimally invasive mitral valve surgery, in 167 patients surgery was performed with the use of robotic assistance. A voice-controlled robotic arm was used for videoscopic guidance in 152 cases. Most recently, a computer-enhanced telemanipulator was used in 15 patients to perform the operation remotely. The mitral valve was repaired in 117 and replaced in all other patients. The voice-controlled robotic arm (AESOP 3000) facilitated videoscopic-assisted mitral valve surgery. The procedure was completed without the need for an additional assistant as "solo surgery." Additional procedures like radiofrequency ablation and tricuspid valve repair were performed in 21 and 4 patients, respectively. Duration of bypass and clamp time was comparable to conventional procedures (107 A 34 and 50 A 16 min, respectively). Hospital mortality was 1.2%. Using the da Vinci telemanipulation system, remote mitral valve repair was successfully performed in 13 of 15 patients. Robotic-assisted less invasive mitral valve surgery has evolved to a reliable technique with reproducible results for primary operations and for reoperations. Robotic assistance has enabled a solo surgery approach. The combination with radiofrequency ablation (Mini Maze) in patients with chronic atrial fibrillation has proven to be beneficial. The use of telemanipulation systems for remote mitral valve surgery is promising, but a number of problems have to be solved before the introduction of a closed chest mitral valve procedure.

  13. Obstructed bi-leaflet prosthetic mitral valve imaging with real-time three-dimensional transesophageal echocardiography.

    PubMed

    Shimbo, Mai; Watanabe, Hiroyuki; Kimura, Shunsuke; Terada, Mai; Iino, Takako; Iino, Kenji; Ito, Hiroshi

    2015-01-01

    Real-time three-dimensional transesophageal echocardiography (RT3D-TEE) can provide unique visualization and better understanding of the relationship among cardiac structures. Here, we report the case of an 85-year-old woman with an obstructed mitral prosthetic valve diagnosed promptly by RT3D-TEE, which clearly showed a leaflet stuck in the closed position. The opening and closing angles of the valve leaflets measured by RT3D-TEE were compatible with those measured by fluoroscopy. Moreover, RT3D-TEE revealed, in the ring of the prosthetic valve, thrombi that were not visible on fluoroscopy. RT3D-TEE might be a valuable diagnostic technique for prosthetic mitral valve thrombosis. © 2014 Wiley Periodicals, Inc.

  14. Torque limited drive for manual valves

    DOEpatents

    Elliott, Philip G.; Underwood, Daniel E.

    1989-06-06

    The present invention is directed to a torque-limiting handwheel device for preventing manual valves from being damaged due to the application of excessive torque during the opening or closing operation of the valves. Torque can only be applied when ridges in the handwheel assembly engage in channels machined in the face of the baseplate. The amount of torque required for disengagement of the ridges from the channels is determined by the force exerted by various Bellville springs and the inclination of the side faces of the channels.

  15. Torque limited drive for manual valves

    DOEpatents

    Elliott, Philip G.; Underwood, Daniel E.

    1989-01-01

    The present invention is directed to a torque-limiting handwheel device for preventing manual valves from being damaged due to the application of excessive torque during the opening or closing operation of the valves. Torque can only be applied when ridges in the handwheel assembly engage in channels machined in the face of the baseplate. The amount of torque required for disengagement of the ridges from the channels is determined by the force exerted by various Bellville springs and the inclination of the side faces of the channels.

  16. A patient-specific aortic valve model based on moving resistive immersed implicit surfaces.

    PubMed

    Fedele, Marco; Faggiano, Elena; Dedè, Luca; Quarteroni, Alfio

    2017-10-01

    In this paper, we propose a full computational framework to simulate the hemodynamics in the aorta including the valve. Closed and open valve surfaces, as well as the lumen aorta, are reconstructed directly from medical images using new ad hoc algorithms, allowing a patient-specific simulation. The fluid dynamics problem that accounts from the movement of the valve is solved by a new 3D-0D fluid-structure interaction model in which the valve surface is implicitly represented through level set functions, yielding, in the Navier-Stokes equations, a resistive penalization term enforcing the blood to adhere to the valve leaflets. The dynamics of the valve between its closed and open position is modeled using a reduced geometric 0D model. At the discrete level, a finite element formulation is used and the SUPG stabilization is extended to include the resistive term in the Navier-Stokes equations. Then, after time discretization, the 3D fluid and 0D valve models are coupled through a staggered approach. This computational framework, applied to a patient-specific geometry and data, allows to simulate the movement of the valve, the sharp pressure jump occurring across the leaflets, and the blood flow pattern inside the aorta.

  17. Transcatheter aortic valve-in-valve implantation of a CoreValve in a JenaValve prosthesis: a case report.

    PubMed

    Lotfi, Shahram; Becker, Michael; Moza, Ajay; Autschbach, Rüdiger; Marx, Nikolaus; Schröder, Jörg

    2017-09-10

    Transcatheter aortic valve implantation has become an accepted treatment modality for inoperable or high-risk surgical patients with symptomatic severe aortic stenosis. We report the case of a 70-year-old white man who was treated for severe symptomatic aortic regurgitation using transcatheter aortic valve implantation from the apical approach. Because of recurrent cardiac decompensation 4 weeks after implantation he underwent the implantation of a left ventricular assist device system. A year later echocardiography showed a severe transvalvular central insufficiency. Our heart team decided to choose a valve-in-valve approach while reducing the flow rate of left ventricular assist device to minimum and pacing with a frequency of 140 beats/minute. There was an excellent result and our patient is doing well with no relevant insufficiency of the aortic valve at 12-month follow-up. This is the first report about a successful treatment of a stenotic JenaValve using a CoreValve Evolut R; the use of a CoreValve Evolut R prosthesis may be an optimal option for valve-in-valve procedures.

  18. Hybrid textile heart valve prosthesis: preliminary in vitro evaluation.

    PubMed

    Vaesken, Antoine; Pidancier, Christian; Chakfe, Nabil; Heim, Frederic

    2016-09-22

    Transcatheter aortic valve implantation (TAVI) is nowadays a popular alternative technique to surgical valve replacement for critical patients. Biological valve tissue has been used in these devices for over a decade now with over 100,000 implantations. However, material degradations due to crimping for catheter insertion purpose have been reported, and with only 6-year follow-up, no information is available about the long-term durability of biological tissue. Moreover, expensive biological tissue harvesting and chemical treatment procedures tend to promote the development of synthetic valve leaflet materials. Textile polyester (PET) material is characterized by outstanding folding and strength properties combined with proven biocompatibility and could therefore be considered as a candidate to replace biological valve leaflets in TAVI devices. Nevertheless, the material should be preferentially partly elastic in order to limit water hammer effects at valve closing time and prevent exaggerated stress from occurring into the stent and the valve. The purpose of the present work is to study in vitro the mechanical as well as the hydrodynamic behavior of a hybrid elastic textile valve device combining non-deformable PET yarn and elastic polyurethane (PU) yarn. The hybrid valve properties are compared with those of a non-elastic textile valve. Testing results show improved hydrodynamic properties with the elastic construction. However, under fatigue conditions, the interaction between PU and PET yarns tends to limit the valve durability.

  19. The challenge of valve-in-valve procedures in degenerated Mitroflow bioprostheses and the advantage of using the JenaValve transcatheter heart valve.

    PubMed

    Conradi, Lenard; Kloth, Benjamin; Seiffert, Moritz; Schirmer, Johannes; Koschyk, Dietmar; Blankenberg, Stefan; Reichenspurner, Hermann; Diemert, Patrick; Treede, Hendrik

    2014-12-01

    Recently, the feasibility of valve-in-valve procedures using current first-generation transcatheter heart valves (THV) in cases of structural valve degeneration has been reported as an alternative to conventional open repeat valve replacement. By design, certain biological valve xenografts carry a high risk of coronary ostia occlusion due to lateral displacement of leaflets after valve-in-valve procedures. In the present report we aimed to prove feasibility and safety of transapical valve-in-valve implantation of the JenaValve THV in two cases of degenerated Mitroflow bioprostheses. We herein report two cases of successful transapical valve-in-valve procedures using a JenaValve THV implanted in Sorin Mitroflow bioprostheses for structural valve degeneration. Both patients were alive and in good clinical condition at 30 days from the procedure. However, increased transvalvular gradients were noted in both cases. Transcatheter valve-in-valve implantation of a JenaValve THV is a valid alternative for patients with degenerated Mitroflow bioprostheses of sufficient size and in the presence of short distances to the coronary ostia who are too ill for conventional repeat open heart surgery. Increased pressure gradients have to be expected and weighed against the disadvantages of other treatment options when planning such a procedure.

  20. Medium-term outcome of Toronto aortic valve replacement: single center experience.

    PubMed

    Li, Wei; Price, Susanna; O'Sullivan, Christine A; Kumar, Pankaj; Jin, Xu Y; Henein, Michael Y; Pepper, John R

    2008-09-26

    Long-term competence of any aortic prosthesis is critical to its clinical durability. Bioprosthetic valves, and in particular the stentless type have been proposed to offer superior haemodynamic profiles with consequent potential for superior left-ventricular mass regression. These benefits however are balanced by the potential longevity of the implanted valve. The aims of this study were to assess medium-term Toronto aortic valve function and its effect on left-ventricular function. Between 1992 and 1996 86 patients underwent Toronto aortic valve replacement for aortic valve disease and were followed up annually. Prospectively collected data was analyzed for all patients where detailed echocardiographic follow-up was available. Echocardiographic studies were analyzed at 2+/-0.6 and 6+/-1.4 years after valve replacement. Data collected included left-ventricular systolic and diastolic dimensions, fractional shortening and left-ventricular mass. In addition, data on aortic valve and root morphology, peak aortic velocities, time velocity integral, stroke volume and the mechanism of valve failure where relevant, were also collected. Complete echocardiographic data were available for eighty-four patients, age 69+/-9 years, 62 male. Additional coronary artery bypass grafting was performed in 38% of patients. Twelve (14%) valves had failed during follow-up, 7 (8%) requiring re-operation. Valve failure was associated with morphologically bicuspid native aortic valve (9/12), and progressive dilatation of the aortic sinuses, sino-tubular junction and ascending aorta (11/12). Left-ventricular mass index remained high (184+/-75 g/m(2)) and did not continue to regress between early and medium-term follow-up (175.8+/-77 g/m(2)). Although more than 90% of implanted Toronto aortic valves remained haemodynamically stable with low gradient at medium-term follow-up, young age and larger aortic dimensions in patients with valve failure suggest better outcome if used in the elderly

  1. A study of waste and delivery valve design modification to the pump performance

    NASA Astrophysics Data System (ADS)

    Harith, M. N.; Bakar, R. A.; Ramasamy, D.; Kardigama, K.; Quanjin, Ma

    2018-04-01

    This paper objective is to share design revolution of waste and delivery valve that contribute to the overall pump performance. In this paper, 3 new designs of waste and delivery valve pump are presented with comprehensive internal flow analysis using computational fluid dynamics (CFD) simulation over 4 cases that have been deeply study for one of the design chosen. 4 cases involving opening and closing both valve or either one. 0.265m height size of customized waste valve with an opening limiter and spring was used to demonstrate cyclic closing and opening valve operation extended up to 0.164m gap. Based on result, this characteristics contribute to 10-20% waste water reduction and enhancement of flow rate height up to 80m. Apart from that this paper also share some of pressure (dynamic, total, static), velocity (x, y, z axis) simulation including the vector flow were under different flow cases.

  2. The Mars Development of a Micro-Isolation Valve

    NASA Technical Reports Server (NTRS)

    Mueller, Juergen; Vargo, Steven; Forgrave, John; Bame, David; Chakraborty, Indrani; Tang, William

    1999-01-01

    A feasibility investigation for a newly proposed microfabricated, normally-closed isolation valve was initiated. The micro-isolation valve is silicon based and relies on the principle of melting a silicon plug, opening an otherwise sealed flow passage. This valve may thus serve a similar role as a conventional pyrovalve and is intended for use in micropropulsion systems onboard future microspacecraft, having wet masses of no more than 10-20 kg, as well as in larger scale propulsion systems having only low flow rate requirements, such as ion propulsion or Hall thruster systems. Two key feasibility issues - melting of the plug and pressure handling capability - were addressed. Thermal finite element modeling showed that valves with plugs having widths between 10 and 50 gm have power requirements of only 10 . 30 Watts to open over a duration of 0.5 ms or less. Valve chips featuring 5 0 micron plugs were burst pressure tested and reached maximum pressure values o f 2900 psig (19.7 Mpa).

  3. Early and mid-term results of autograft rescue by Ross reversal: A one-valve disease need not become a two-valve disease.

    PubMed

    Hussain, Syed T; Majdalany, David S; Dunn, Aaron; Stewart, Robert D; Najm, Hani K; Svensson, Lars G; Houghtaling, Penny L; Blackstone, Eugene H; Pettersson, Gösta B

    2018-02-01

    Risk of reoperation and loss of a second native valve are major drawbacks of the Ross operation. Rather than discarding the failed autograft, it can be placed back into the native pulmonary position by "Ross reversal." We review our early and mid-term results with this operation. From 2006 to 2017, 39 patients underwent reoperation for autograft dysfunction. The autograft was successfully rescued in 35 patients: by Ross reversal in 30, David procedure in 4, and autograft repair in 1. Medical records were reviewed for patient characteristics (mean age was 46 ± 13 years, range 18-67 years, and 23 were male), previous operations, indications for reoperation, hospital outcomes, and echocardiographic findings for the 30 patients undergoing successful Ross reversal. Follow-up was 4.1 ± 3.5 years (range 7 months-11 years). Median interval between the original Ross procedure and Ross reversal was 12 years (range 5-19 years). Eight patients also had absolute indications for replacement of the pulmonary allograft. There was no operative mortality. One patient required reoperation for bleeding. Another had an abdominal aorta injury from use of an endoballoon clamp. There was no other major postoperative morbidity, and median postoperative hospital stay was 7.2 days (range 4-41 days). No patient required reoperation during follow-up. Twenty-four patients had acceptable pulmonary valve function, and 6 had clinically well-tolerated moderate or severe pulmonary regurgitation. Ross reversal can be performed with low morbidity and acceptable pulmonary valve function, reducing patient risk of losing 2 native valves when the autograft fails in the aortic position. Copyright © 2017 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.

  4. 46 CFR 56.20-9 - Valve construction.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... closed. (b) Valves of Class I piping systems (for restrictions in other classes refer to sections on low temperature service), having diameters exceeding 2 inches must have bolted, pressure seal, or breech lock...

  5. The patient inflating valve in anaesthesia and resuscitation breathing systems.

    PubMed

    Fenton, P M; Bell, G

    2013-03-01

    Patient inflating valves combined with self-inflating bags are known to all anaesthetists as resuscitation devices and are familiar as components of draw-over anaesthesia systems. Their variants are also commonplace in transfer and home ventilators. However, the many variations in structure and function have led to difficulties in their optimal use, definition and classification. After reviewing the relevant literature, we defined a patient inflating valve as a one-way valve that closes an exit port to enable lung inflation, also permitting exhalation and spontaneous breathing, the actions being automatic. We present a new classification based on the mechanism of valve opening/closure; namely elastic recoil of a flexible flap/diaphragm, sliding spindle opened by a spring/magnet or a hollow balloon collapsed by external pressure. The evolution of these valves has been driven by the difficulties documented in critical incidents, which we have used along with information from modern International Organization for Standardization standards to identify 13 ideal properties, the top six of which are non-jamming, automatic, no bypass effect, no rebreathing or air entry at patient end, low resistance, robust and easy to service. The Ambu and the Laerdal valves have remained popular due to their simplicity and reliability. Two new alternatives, the Fenton and Diamedica valves, offer the benefits of location away from the patient while retaining a small functional dead space. They also offer the potential for greater use of hybrid continuous flow/draw-over systems that can operate close to atmospheric pressure. The reliable application of positive end-expiratory pressure/continuous positive airway pressure remains a challenge.

  6. Evaluation of mitral valve replacement anchoring in a phantom

    NASA Astrophysics Data System (ADS)

    McLeod, A. Jonathan; Moore, John; Lang, Pencilla; Bainbridge, Dan; Campbell, Gordon; Jones, Doug L.; Guiraudon, Gerard M.; Peters, Terry M.

    2012-02-01

    Conventional mitral valve replacement requires a median sternotomy and cardio-pulmonary bypass with aortic crossclamping and is associated with significant mortality and morbidity which could be reduced by performing the procedure off-pump. Replacing the mitral valve in the closed, off-pump, beating heart requires extensive development and validation of surgical and imaging techniques. Image guidance systems and surgical access for off-pump mitral valve replacement have been previously developed, allowing the prosthetic valve to be safely introduced into the left atrium and inserted into the mitral annulus. The major remaining challenge is to design a method of securely anchoring the prosthetic valve inside the beating heart. The development of anchoring techniques has been hampered by the expense and difficulty in conducting large animal studies. In this paper, we demonstrate how prosthetic valve anchoring may be evaluated in a dynamic phantom. The phantom provides a consistent testing environment where pressure measurements and Doppler ultrasound can be used to monitor and assess the valve anchoring procedures, detecting pararvalvular leak when valve anchoring is inadequate. Minimally invasive anchoring techniques may be directly compared to the current gold standard of valves sutured under direct vision, providing a useful tool for the validation of new surgical instruments.

  7. Safety valve

    DOEpatents

    Bergman, Ulf C.

    1984-01-01

    The safety valve contains a resilient gland to be held between a valve seat and a valve member and is secured to the valve member by a sleeve surrounding the end of the valve member adjacent to the valve seat. The sleeve is movable relative to the valve member through a limited axial distance and a gap exists between said valve member and said sleeve.

  8. Magnetic timing valves for fluid control in paper-based microfluidics.

    PubMed

    Li, Xiao; Zwanenburg, Philip; Liu, Xinyu

    2013-07-07

    Multi-step analytical tests, such as an enzyme-linked immunosorbent assay (ELISA), require delivery of multiple fluids into a reaction zone and counting the incubation time at different steps. This paper presents a new type of paper-based magnetic valves that can count the time and turn on or off a fluidic flow accordingly, enabling timed fluid control in paper-based microfluidics. The timing capability of these valves is realized using a paper timing channel with an ionic resistor, which can detect the event of a solution flowing through the resistor and trigger an electromagnet (through a simple circuit) to open or close a paper cantilever valve. Based on this principle, we developed normally-open and normally-closed valves with a timing period up to 30.3 ± 2.1 min (sufficient for an ELISA on paper-based platforms). Using the normally-open valve, we performed an enzyme-based colorimetric reaction commonly used for signal readout of ELISAs, which requires a timed delivery of an enzyme substrate to a reaction zone. This design adds a new fluid-control component to the tool set for developing paper-based microfluidic devices, and has the potential to improve the user-friendliness of these devices.

  9. Variable Valve Actuation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Jeffrey Gutterman; A. J. Lasley

    2008-08-31

    mechanism it was determined that the single cam design did not have enough flexibility to satisfy three critical OEM requirements simultaneously, (maximum valve lift variation, intake valve opening timing and valve closing duration), and a new approach would be necessary. After numerous internal design reviews including several with the OEM a dual cam design was developed that had the flexibility to meet all motion requirements. The second cam added complexity to the mechanism however the cost was offset by the deletion of the electric motor required in the previous design. New patent applications including detailed drawings and potential valve motion profiles were generated and alternate two cam designs were proposed and evaluated for function, cost, reliability and durability. Hardware was designed and built and testing of sample hardware was successfully completed on an engine test stand. The mechanism developed during the course of this investigation can be applied by Original Equipment Manufacturers, (OEM), to their advanced diesel engines with the ultimate goal of reducing emissions and improving fuel economy. The objectives are: (1) Develop an optimal, cost effective, variable valve actuation (VVA) system for advanced low temperature diesel combustion processes. (2) Design and model alternative mechanical approaches and down-select for optimum design. (3) Build and demonstrate a mechanism capable of application on running engines.« less

  10. Failure and life cycle evaluation of watering valves.

    PubMed

    Gonzalez, David M; Graciano, Sandy J; Karlstad, John; Leblanc, Mathias; Clark, Tom; Holmes, Scott; Reuter, Jon D

    2011-09-01

    Automated watering systems provide a reliable source of ad libitum water to animal cages. Our facility uses an automated water delivery system to support approximately 95% of the housed population (approximately 14,000 mouse cages). Drinking valve failure rates from 2002 through 2006 never exceeded the manufacturer standard of 0.1% total failure, based on monthly cage census and the number of floods. In 2007, we noted an increase in both flooding and cases of clinical dehydration in our mouse population. Using manufacturer's specifications for a water flow rate of 25 to 50 mL/min, we initiated a wide-scale screening of all valves used. During a 4-mo period, approximately 17,000 valves were assessed, of which 2200 failed according to scoring criteria (12.9% overall; 7.2% low flow; 1.6% no flow; 4.1% leaky). Factors leading to valve failures included residual metal shavings, silicone flash, introduced debris or bedding, and (most common) distortion of the autoclave-rated internal diaphragm and O-ring. Further evaluation revealed that despite normal autoclave conditions of heat, pressure, and steam, an extreme negative vacuum pull caused the valves' internal silicone components (diaphragm and O-ring) to become distorted and water-permeable. Normal flow rate often returned after a 'drying out' period, but components then reabsorbed water while on the animal rack or during subsequent autoclave cycles to revert to a variable flow condition. On the basis of our findings, we recalibrated autoclaves and initiated a preventative maintenance program to mitigate the risk of future valve failure.

  11. Surgical Outcome of Ahmed Valve Implantation in Mexican Patients with Neovascular Glaucoma.

    PubMed

    Hernandez-Oteyza, Alejandra; Lazcano-Gomez, Gabriel; Jimenez-Roman, Jesus; Hernandez-Garciadiego, Carlos

    2014-01-01

    To describe clinical results of Ahmed glaucoma valve implantation in Mexican patients with neovascular glaucoma (NVG). We reviewed records of 60 eyes of 60 patients with NVG who underwent Ahmed valve implantation, with a follow-up period of 1 year. We identified successful and failed cases and compared baseline and follow-up characteristics to identify possible differences between both groups. We classified 36 eyes (60%) as successful and 24 (40%) as failed cases. We found a significant difference in success rate in patients who had a hypertensive phase at any time during the follow-up period (OR = 5.15, CI = 1.49-20.15, p = 0.004). Patients in the success group showed a statistically significant decrease in the number of glaucoma medications 1 year after surgery (p <0.0001). We found a statistically significant difference in success rate in patients who had preoperative best corrected visual acuity (BCVA) better than logmar 0.70 (odds ratio 4.31, CI = 1.1-19.3, p = 0.03086). A hypertensive postoperative phase and a preoperative BCVA worse or equal to 20/100 seem to be risk factors for Ahmed valve surgical failure in patients with NVG. How to cite this article: Hernandez-Oteyza A, Lazcano-Gomez G, Jimenez-Roman J, Hernandez-Garciadiego C. Surgical Outcome of Ahmed Valve Implantation in Mexican Patients with Neovascular Glaucoma. J Curr Glaucoma Pract 2014;8(3):86-90.

  12. Fracturing mechanics before valve-in-valve therapy of small aortic bioprosthetic heart valves.

    PubMed

    Johansen, Peter; Engholt, Henrik; Tang, Mariann; Nybo, Rasmus F; Rasmussen, Per D; Nielsen-Kudsk, Jens Erik

    2017-10-13

    Patients with degraded bioprosthetic heart valves (BHV) who are not candidates for valve replacement may benefit from transcatheter valve-in-valve (VIV) therapy. However, in smaller-sized surgical BHV the resultant orifice may become too narrow. To overcome this, the valve frame can be fractured by a high-pressure balloon prior to VIV. However, knowledge on fracture pressures and mechanics are prerequisites. The aim of this study was to identify the fracture pressures needed in BHV, and to describe the fracture mechanics. Commonly used BHV of small sizes were mounted on a high-pressure balloon situated in a biplane fluoroscopic system with a high-speed camera. The instant of fracture was captured along with the balloon pressure. The valves were inspected for material protrusion and later dissected for fracture zone investigation and description. The valves with a polymer frame fractured at a lower pressure (8-10 atm) than those with a metal stent (19-26 atm). None of the fractured valves had elements protruding. VIV procedures in small-sized BHV may be performed after prior fracture of the valve frame by high-pressure balloon dilatation. This study provides tentative guidelines for expected balloon sizes and pressures for valve fracturing.

  13. [Status of aortic valve reconstruction and Ross operation in aortic valve diseases].

    PubMed

    Sievers, Hans H

    2002-08-01

    At first glance the aortic valve is a relative simple valve mechanism connecting the left ventricle and the ascending aorta. Detailed analysis of the different components of the aortic valve including the leaflets and sinuses revealed a complex motion of each part leading to a perfect durable valve mechanism at rest and during exercise. Theoretically, the reconstruction or imitation of these structures in patients with aortic valve disease should lead to optimal results. Prerequisite is the exact knowledge of the important functional characteristics of the aortic valve. The dynamic behavior of the aortic root closely harmonizing with the leaflets not only warrants stress minimizing and valve durability, but also optimizes coronary flow, left ventricular function and aortic impedance. The newly discovered contractile capacity of the leaflets and the root components are important for tuning the dynamics. Isolated reconstruction of the aortic valve such as decalcification, commissurotomy, plication of ring or leaflets of a tricuspid aortic valve and cusp extension are seldom indicated in contrast to the reconstruction of the bicuspid insufficient valve. Proper indication and skilled techniques lead to excellent hemodynamic and clinical intermediate-term result up to 7 years after reconstruction. Latest follow-up revealed a mean aortic insufficiency of 0.7, maximal pressure gradient of 11.4 +/- 8.5 mm Hg with zero hospital or late mortality, reoperation or thromboembolic events in 22 patients. The reconstructive techniques for aortic root aneurysm and/or type A dissection according to David or Yacoub have become routine procedures in the last 10 years. The hemodynamic and clinical results are excellent with low reoperation rate and very low risk of thromboembolism. Generally, a maximal diameter of the root of 5 cm is indicative for performing the operation. In patients with Marfan's syndrome the reconstruction should be advanced even with smaller diameters especially

  14. Stemless ball valve

    NASA Technical Reports Server (NTRS)

    Burgess, Kevin (Inventor); Yakos, David (Inventor); Walthall, Bryan (Inventor)

    2011-01-01

    A stemless ball valve comprising two flanges and a ball with a channel, two axis pins and two travel pins. One end of each axis and travel pin is fixedly attached to the ball, and the other end of each axis pin is lodged into a notch in the first or second flange such that the axis pin is allowed to rotate in the notch. The guide sleeve comprises two channels, and one end of each travel pin is situated within one of the two channels in the guide sleeve. An outer magnetic cartridge causes the inner magnetic cartridge and guide sleeve to rotate, and when the guide sleeve rotates, the travel pins move up and down within the channels in the guide sleeve. The movement of the travel pins within the channels in the guide sleeve causes the ball to rotate, thereby opening and closing the ball valve.

  15. Check valve

    DOEpatents

    Upton, Hubert Allen; Garcia, Pablo

    1999-08-24

    A check valve for use in a GDCS of a nuclear reactor and having a motor driven disk including a rotatable armature for rotating the check valve disk over its entire range of motion is described. In one embodiment, the check valve includes a valve body having a coolant flow channel extending therethrough. The coolant flow channel includes an inlet end and an outlet end. A valve body seat is located on an inner surface of the valve body. The check valve further includes a disk assembly, sometimes referred to as the motor driven disc, having a counterweight and a disk shaped valve. The disk valve includes a disk base having a seat for seating with the valve body seat. The disk assembly further includes a first hinge pin member which extends at least partially through the disk assembly and is engaged to the disk. The disk valve is rotatable relative to the first hinge pin member. The check valve also includes a motor having a stator frame with a stator bore therein. An armature is rotatably positioned within the stator bore and the armature is coupled to the disk valve to cause the disk valve to rotate about its full range of motion.

  16. Check valve

    DOEpatents

    Upton, H.A.; Garcia, P.

    1999-08-24

    A check valve for use in a GDCS of a nuclear reactor and having a motor driven disk including a rotatable armature for rotating the check valve disk over its entire range of motion is described. In one embodiment, the check valve includes a valve body having a coolant flow channel extending therethrough. The coolant flow channel includes an inlet end and an outlet end. A valve body seat is located on an inner surface of the valve body. The check valve further includes a disk assembly, sometimes referred to as the motor driven disc, having a counterweight and a disk shaped valve. The disk valve includes a disk base having a seat for seating with the valve body seat. The disk assembly further includes a first hinge pin member which extends at least partially through the disk assembly and is engaged to the disk. The disk valve is rotatable relative to the first hinge pin member. The check valve also includes a motor having a stator frame with a stator bore therein. An armature is rotatably positioned within the stator bore and the armature is coupled to the disk valve to cause the disk valve to rotate about its full range of motion. 5 figs.

  17. Flow Split Venturi, Axially-Rotated Valve

    DOEpatents

    Walrath, David E.; Lindberg, William R.; Burgess, Robert K.; LaBelle, James

    2000-02-22

    The present invention provides an axially-rotated valve which permits increased flow rates and lower pressure drop (characterized by a lower loss coefficient) by using an axial eccentric split venturi with two portions where at least one portion is rotatable with respect to the other portion. The axially-rotated valve typically may be designed to avoid flow separation and/or cavitation at full flow under a variety of conditions. Similarly, the valve is designed, in some embodiments, to produce streamlined flow within the valve. An axially aligned outlet may also increase the flow efficiency. A typical cross section of the eccentric split venturi may be non-axisymmetric such as a semicircular cross section which may assist in both throttling capabilities and in maximum flow capacity using the design of the present invention. Such a design can include applications for freeze resistant axially-rotated valves and may be fully-opened and fully-closed in one-half of a complete rotation. An internal wide radius elbow typically connected to a rotatable portion of the eccentric venturi may assist in directing flow with lower friction losses. A valve actuator may actuate in an axial manner yet be uniquely located outside of the axial flow path to further reduce friction losses. A seal may be used between the two portions that may include a peripheral and diametrical seal in the same plane. A seal separator may increase the useful life of the seal between the fixed and rotatable portions.

  18. Design and Development of Sequential Rotary Valve

    NASA Technical Reports Server (NTRS)

    D’Orsi, Nicholas; Castillo, Priscilla

    2017-01-01

    Valves are used to regulate the flow of fluids through systems. This rotary valve's main purpose is to fill, pressurize, empty, and vent three smaller tanks with the supply of one larger tank. Many different designs are being taken into consideration, which are each at different stages of development. The furthest along uses three ball valves on a common shaft to open and close their respective ports as the shaft completes one full rotation or cycle. We were tasked with advancing this design to its first test as a plastic model for flow verification, as well as sizing and ordering the necessary O-rings and fasteners. A motor will also be sized to satisfy the torque requirements, and will then be programmed using a Raspberry Pi to rotate the shaft at the calculated speed and dwelling times needed to fill each tank equally. In addition, we have also been advancing designs that use a camshaft and poppets. These are earlier on in their development, currently being sized to replicate the expected flow patterns of the rotary ball valve. Expected outcomes of this valve include bi-directionality, successful sealing under pressure, and accurate cycling.

  19. Micro system comprising 96 micro valves on a titer plate

    NASA Astrophysics Data System (ADS)

    Krabbe, S.; Flitsch, D.; Büchs, J.; Schomburg, W. K.

    2016-10-01

    A system of 96 micro valves has been developed and mounted on top of a 48-well micro titer plate providing two valves for each well controlling its air inlet and outlet. Testing of the valve system showed that all valves are working and are opened and closed reliably. A pneumatic system is switching inlet and outlet valves independently of each other. The geometry of the feed channels ensures an equal air flow through all wells, when the valves are open. Between the micro valves, one optical fibre was inserted through the lid of each well allowing measuring the oxygen partial pressure in the enclosed air volume by fluorescence sensor spots. Escherichia coli bacteria were grown inside the wells and their metabolism was observed by the oxygen partial pressure change due to respiration. In all 48 wells, the same oxygen transfer rate was observed within an averaged standard deviation of 1 mmol/L/h. The oxygen transfer rate differences compared to a macroscopic standard shake flask system were overall compatible within their uncertainties.

  20. Characterization of small microfluidic valves for studies of mechanical properties of bacteria

    DOE PAGES

    Yang, Da; Greer, Clayton M.; Jones, Branndon P.; ...

    2015-09-02

    Lab-on-a-chip platforms present many new opportunities to study bacterial cells and cellular assemblies. Here, the authors describe a new platform that allows us to apply uniaxial stress to individual bacterial cells while observing the cell and its subcellular assemblies using a high resolution optical microscope. The microfluidic chip consists of arrays of miniature pressure actuated valves. By placing a bacterium under one of such valves and partially closing the valve by externally applied pressure, the cell can be deformed. Although large pressure actuated valves used in integrated fluidic circuits have been extensively studied previously, here the authors downsize those microfluidicmore » valves and use flow channels with rectangular cross-sections to maintain the bacteria in contact with cell culture medium during the experiments. The closure of these valves has not been characterized before. First, these valves are modeled using finite element analysis, and then compared the modeling results with the actual closing profiles of the valves, which is determined from absorption measurements. The measurements and modeling show with good agreement that the deflection of valves is a linear function of externally applied pressure and the deflection scales proportionally to the width of the flow channel. In addition to characterizing the valve, the authors show at a proof-of-principle level that it can be used to deform a bacterial cell at considerable magnitude. They found the largest deformations in 5 μm wide channels where the bacterial width and length increase by 1.6 and 1.25 times, respectively. Narrower and broader channels are less optimal for these studies. Finally, the platform presents a promising approach to probe, in a quantitative and systematic way, the mechanical properties of not only bacterial cells but possibly also yeast and other single-celled organisms.« less

  1. Variable reluctance proximity sensors for cryogenic valve position indication

    NASA Technical Reports Server (NTRS)

    Cloyd, R. A.

    1982-01-01

    A test was conducted to determine the performance of a variable reluctance proximity sensor system when installed in a space shuttle external tank vent/relief valve. The sensors were used as position indicators. The valve and sensors were cycled through a series of thermal transients; while the valve was being opened and closed pneumatically, the sensor's performance was being monitored. During these thermal transients, the vent valve was cooled ten times by liquid nitrogen and two times by liquid hydrogen. It was concluded that the sensors were acceptable replacements for the existing mechanical switches. However, the sensors need a mechanical override for the target similar to what is presently used with the mechanical switches. This override could insure contact between sensor and target and eliminate any problems of actuation gap growth caused by thermal gradients.

  2. In-plane cost-effective magnetically actuated valve for microfluidic applications

    NASA Astrophysics Data System (ADS)

    Pugliese, Marco; Ferrara, Francesco; Bramanti, Alessandro Paolo; Gigli, Giuseppe; Maiorano, Vincenzo

    2017-04-01

    We present a new in-plane magnetically actuated microfluidic valve. Its simple design includes a circular area joining two channels lying on the same plane. The area is parted by a septum lying on and adhering to a magneto-active polymeric ‘floor’ membrane, keeping the channels normally separated (valve closed). Under the action of a magnetic field, the membrane collapses, letting the liquid flow below the septum (valve open). The valve was extensively characterized experimentally, and modeled and optimized theoretically. The growing interest in lab on chips, especially for diagnostics and precision medicine, is driving researchers towards smart, efficient and low cost solutions to the management of biological samples. In this context, the valve developed in this work represents a useful building-block for microfluidic applications requiring precise flow control, its main features being easy and rapid manufacturing, biocompatibility and low cost.

  3. Dynamic modeling and simulation of an integral bipropellant propulsion double-valve combined test system

    NASA Astrophysics Data System (ADS)

    Chen, Yang; Wang, Huasheng; Xia, Jixia; Cai, Guobiao; Zhang, Zhenpeng

    2017-04-01

    For the pressure reducing regulator and check valve double-valve combined test system in an integral bipropellant propulsion system, a system model is established with modular models of various typical components. The simulation research is conducted on the whole working process of an experiment of 9 MPa working condition from startup to rated working condition and finally to shutdown. Comparison of simulation results with test data shows: five working conditions including standby, startup, rated pressurization, shutdown and halt and nine stages of the combined test system are comprehensively disclosed; valve-spool opening and closing details of the regulator and two check valves are accurately revealed; the simulation also clarifies two phenomena which test data are unable to clarify, one is the critical opening state in which the check valve spools slightly open and close alternately in their own fully closed positions, the other is the obvious effects of flow-field temperature drop and temperature rise in pipeline network with helium gas flowing. Moreover, simulation results with consideration of component wall heat transfer are closer to the test data than those under the adiabatic-wall condition, and more able to reveal the dynamic characteristics of the system in various working stages.

  4. Validation of Model-Based Prognostics for Pneumatic Valves in a Demonstration Testbed

    DTIC Science & Technology

    2014-10-02

    predict end of life ( EOL ) and remaining useful life (RUL). The approach still follows the general estimation-prediction framework devel- oped in the...atmosphere, with linearly increasing leak area. kA2leak = Cleak (16) We define valve end of life ( EOL ) through open/close time limits of the valves, as in...represents end of life ( EOL ), and ∆kE represents remaining useful life (RUL). For valves, timing requirements are provided that de- fine the maximum

  5. Extrinsic mechanism obstructing the opening of a prosthetic mitral valve: an unusual case of suture entrapment.

    PubMed

    Ozkan, Mehmet; Astarcioglu, Mehmet Ali; Karakoyun, Suleyman; Balkanay, Mehmet

    2012-02-01

    Obstruction to a prosthetic cardiac valve is a well-recognized complication of cardiac valve replacement. Malfunction of the mobile component of a prosthetic valve to open or close correctly may occur in consequence of intrinsic or extrinsic causes (thrombus, vegetation, entrapment of left ventricular myocardium, suture entanglement, and pannus formation) that may result prosthetic valve stenosis and/or insufficiency. In the case we report a 48-year-old female with valve dysfunction occurred early after surgery, as one valve leaflet was only able to partially open due to suture entrapment. © 2011, Wiley Periodicals, Inc.

  6. Monovalve with integrated fuel injector and port control valve, and engine using same

    DOEpatents

    Milam, David M.

    2001-11-06

    An engine includes an engine casing that defines a hollow piston cavity separated from an exhaust passage and an intake passage by a valve seat. A gas exchange valve member is positioned adjacent the valve seat and is moveable between an open position and a closed position. The gas exchange valve member also defines an opening that opens into the hollow piston cavity. A needle valve member is positioned in the gas exchange valve member adjacent a nozzle outlet and is moveable between an inject position and a blocked position. A port control valve member, which has a hydraulic surface, is mounted around the gas exchange valve member and moveable between an intake position and an exhaust position. A pilot valve is moveable between a first position at which the port control hydraulic surface is exposed to a source of high pressure fluid, and a second position at which the port control hydraulic surface is exposed to a source of low pressure fluid.

  7. Modification and performance evaluation of a mono-valve engine

    NASA Astrophysics Data System (ADS)

    Behrens, Justin W.

    A four-stroke engine utilizing one tappet valve for both the intake and exhaust gas exchange processes has been built and evaluated. The engine operates under its own power, but has a reduced power capacity than the conventional 2-valve engine. The reduction in power is traced to higher than expected amounts of exhaust gases flowing back into the intake system. Design changes to the cylinder head will fix the back flow problems, but the future capacity of mono-valve engine technology cannot be estimated. The back flow of exhaust gases increases the exhaust gas recirculation (EGR) rate and deteriorates combustion. Intake pressure data shows the mono-valve engine requires an advanced intake valve closing (IVC) time to prevent back flow of charge air. A single actuation camshaft with advanced IVC was tested in the mono-valve engine, and was found to improve exhaust scavenging at TDC and nearly eliminated all charge air back flow at IVC. The optimum IVC timing is shown to be approximately 30 crank angle degrees after BDC. The mono-valve cylinder head utilizes a rotary valve positioned above the tappet valve. The open spaces inside the rotary valveand between the rotary valve and tappet valve represent a common volume that needs to be reduced in order to reduce the base EGR rate. Multiple rotary valve configurations were tested, and the size of the common volume was found to have no effect on back flow but a direct effect on the EGR rate and engine performance. The position of the rotary valve with respect to crank angle has a direct effect on the scavenging process. Optimum scavenging occurs when the intake port is opened just after TDC.

  8. Integral isolation valve systems for loss of coolant accident protection

    DOEpatents

    Kanuch, David J.; DiFilipo, Paul P.

    2018-03-20

    A nuclear reactor includes a nuclear reactor core comprising fissile material disposed in a reactor pressure vessel having vessel penetrations that exclusively carry flow into the nuclear reactor and at least one vessel penetration that carries flow out of the nuclear reactor. An integral isolation valve (IIV) system includes passive IIVs each comprising a check valve built into a forged flange and not including an actuator, and one or more active IIVs each comprising an active valve built into a forged flange and including an actuator. Each vessel penetration exclusively carrying flow into the nuclear reactor is protected by a passive IIV whose forged flange is directly connected to the vessel penetration. Each vessel penetration carrying flow out of the nuclear reactor is protected by an active IIV whose forged flange is directly connected to the vessel penetration. Each active valve may be a normally closed valve.

  9. Further insights into normal aortic valve function: role of a compliant aortic root on leaflet opening and valve orifice area.

    PubMed

    Sripathi, Vangipuram Canchi; Kumar, Ramarathnam Krishna; Balakrishnan, Komarakshi R

    2004-03-01

    This study aims to find the fundamental differences in the mechanism of opening and closing of a normal aortic valve and a valve with a stiff root, using a dynamic finite element model. A dynamic, finite element model with time varying pressure was used in this study. Shell elements with linear elastic properties for the leaflet and root were used. Two different cases were analyzed: (1) normal leaflets inside a compliant root, and (2) normal leaflets inside a stiff root. A compliant aortic root contributes substantially to the smooth and symmetrical leaflet opening with minimal gradients. In contrast, the leaflet opening inside a stiff root is delayed, asymmetric, and wrinkled. However, this wrinkling is not associated with increased leaflet stresses. In compliant roots, the effective valve orifice area can substantially increase because of increased root pressure and transvalvular gradients. In stiff roots this effect is strikingly absent. A compliant aortic root contributes substantially to smooth and symmetrical leaflet opening with minimal gradients. The compliance also contributes much to the ability of the normal aortic valve to increase its effective valve orifice in response to physiologic demands of exercise. This effect is strikingly absent in stiff roots.

  10. Valve movement response of the freshwater clam Corbicula fluminea following exposure to waterborne arsenic.

    PubMed

    Liao, Chung-Min; Jau, Sheng-Feng; Lin, Chieh-Ming; Jou, Li-John; Liu, Chen-Wuing; Liao, Vivian Hsiu-Chuan; Chang, Fi-John

    2009-07-01

    We developed an inductance-based valvometry technique as a detection system to measure the valve daily activity in freshwater clam Corbicula fluminea in response to waterborne arsenic. Our findings reveal that C. fluminea experiences a valve opening in the absence of arsenic predominantly in the morning hours (03:00-08:00) with a mean daily opening/closing period of 21.32 (95% CI: 20.58-22.05) h. Amplification of daily activity occurred in the presence of arsenic. Behavioral toxicity assays revealed arsenic detection thresholds of 0.60 (95% CI: 0.53-0.66) mg l(-1) and 0.35 (95% CI: 0.30-0.40) mg l(-1) for response times of 60 and 300 min, respectively. The proposed valve daily activity model was linked with response time-specific Hill dose-response functions to predict valve opening/closing behavior in response to arsenic. The predictive capabilities were verified satisfactory with the measurements. Our results implicate a biomonitoring system by valve daily activity in C. fluminea to identify safe water uses in areas with elevated arsenic.

  11. Pediatric Tubular Pulmonary Heart Valve from Decellularized Engineered Tissue Tubes

    PubMed Central

    Reimer, Jay M.; Syedain, Zeeshan H.; Haynie, Bee H.T.; Tranquillo, Robert T.

    2015-01-01

    Pediatric patients account for a small portion of the heart valve replacements performed, but a pediatric pulmonary valve replacement with growth potential remains an unmet clinical need. Herein we report the first tubular heart valve made from two decellularized, engineered tissue tubes attached with absorbable sutures, which can meet this need, in principle. Engineered tissue tubes were fabricated by allowing ovine dermal fibroblasts to replace a sacrificial fibrin gel with an aligned, cell-produced collagenous matrix, which was subsequently decellularized. Previously, these engineered tubes became extensively recellularized following implantation into the sheep femoral artery. Thus, a tubular valve made from these tubes may be amenable to recellularization and, ideally, somatic growth. The suture line pattern generated three equi-spaced “leaflets” in the inner tube, which collapsed inward when exposed to back pressure, per tubular valve design. Valve testing was performed in a pulse duplicator system equipped with a secondary flow loop to allow for root distention. All tissue-engineered valves exhibited full leaflet opening and closing, minimal regurgitation (< 5%), and low systolic pressure gradients (< 2.5 mmHg) under pulmonary conditions. Valve performance was maintained under various trans-root pressure gradients and no tissue damage was evident after 2 million cycles of fatigue testing. PMID:26036175

  12. Failure and Life Cycle Evaluation of Watering Valves

    PubMed Central

    Gonzalez, David M; Graciano, Sandy J; Karlstad, John; Leblanc, Mathias; Clark, Tom; Holmes, Scott; Reuter, Jon D

    2011-01-01

    Automated watering systems provide a reliable source of ad libitum water to animal cages. Our facility uses an automated water delivery system to support approximately 95% of the housed population (approximately 14,000 mouse cages). Drinking valve failure rates from 2002 through 2006 never exceeded the manufacturer standard of 0.1% total failure, based on monthly cage census and the number of floods. In 2007, we noted an increase in both flooding and cases of clinical dehydration in our mouse population. Using manufacturer's specifications for a water flow rate of 25 to 50 mL/min, we initiated a wide-scale screening of all valves used. During a 4-mo period, approximately 17,000 valves were assessed, of which 2200 failed according to scoring criteria (12.9% overall; 7.2% low flow; 1.6% no flow; 4.1% leaky). Factors leading to valve failures included residual metal shavings, silicone flash, introduced debris or bedding, and (most common) distortion of the autoclave-rated internal diaphragm and O-ring. Further evaluation revealed that despite normal autoclave conditions of heat, pressure, and steam, an extreme negative vacuum pull caused the valves’ internal silicone components (diaphragm and O-ring) to become distorted and water-permeable. Normal flow rate often returned after a ‘drying out’ period, but components then reabsorbed water while on the animal rack or during subsequent autoclave cycles to revert to a variable flow condition. On the basis of our findings, we recalibrated autoclaves and initiated a preventative maintenance program to mitigate the risk of future valve failure. PMID:22330720

  13. Single-use thermoplastic microfluidic burst valves enabling on-chip reagent storage

    PubMed Central

    Rahmanian, Omid D.

    2014-01-01

    A simple and reliable method for fabricating single-use normally closed burst valves in thermoplastic microfluidic devices is presented, using a process flow that is readily integrated into established workflows for the fabrication of thermoplastic microfluidics. An experimental study of valve performance reveals the relationships between valve geometry and burst pressure. The technology is demonstrated in a device employing multiple valves engineered to actuate at different inlet pressures that can be generated using integrated screw pumps. On-chip storage and reconstitution of fluorescein salt sealed within defined reagent chambers are demonstrated. By taking advantage of the low gas and water permeability of cyclic olefin copolymer, the robust burst valves allow on-chip hermetic storage of reagents, making the technology well suited for the development of integrated and disposable assays for use at the point of care. PMID:25972774

  14. Wedge gate valves selecting essentials in pipeline systems designing based on permissible operation parameters

    NASA Astrophysics Data System (ADS)

    Zakirnichnaya, M. M.; Kulsharipov, I. M.

    2017-10-01

    Wedge gate valves are widely used at the fuel and energy complex enterprises. The pipeline valves manufacturers indicate the safe operation resource according to the current regulatory and technical documentation. In this case, the resource value of the valve body strength calculation results is taken into consideration as the main structural part. However, it was determined that the wedge gate valves fail before the assigned resource due to the occurrence of conditions under which the wedge breaks in the hooks and, accordingly, the sealing integrity is not ensured. In this regard, it became necessary to assess the conditions under which the resource should be assigned not only to the valve body, but also to take into account the wedge durability. For this purpose, wedge resource calculations were made using the example of ZKL2 250-25 and ZKL2 300-25 valves using the ABAQUS software package FE-SAFE module under the technological parameters influence on the basis of their stressstrain state calculation results. Operating conditions, under which the wedge resource value is lower than the one set by the manufacturer, were determined. A technique for limiting the operating parameters for ensuring the wedge durability during the wedge gate valve assigned resource is proposed.

  15. Transfemoral implantation of an Edwards SAPIEN valve in a tricuspid bioprosthesis without fluoroscopic landmarks.

    PubMed

    Calvert, Patrick A; Himbert, Dominique; Brochet, Eric; Radu, Costin; Iung, Bernard; Hvass, Ulrik; Darondel, Jean-Marc; Depoix, Jean-Pol; Nataf, Patrick; Vahanian, Alec

    2012-03-01

    We describe the first report of an Edwards SAPIEN valve implanted in a tricuspid bioprosthesis from the femoral vein. We highlight the feasibility of this previously avoided approach and the techniques involved. A 61-year-old woman with multiple valve replacements for rheumatic heart disease presented with NHYA IV dyspnoea secondary to a severely stenosed tricuspid bioprosthesis. After failed aggressive medical therapy and surgical turn down, an Edwards SAPIEN XT valve was deployed in the tricuspid bioprosthesis via the right femoral vein. Adaptations to the standard transfemoral transcatheter aortic valve implantation (TAVI) technique included: (1) crossing the tricuspid bioprosthesis with a balloon floatation catheter; (2) temporary pacing wire in the coronary sinus rather than the right ventricle; (3) mounting of the SAPIEN XT valve in the reverse orientation to transfemoral TAVI; and (4) fine positioning of the final valve position pre-deployment by 3D transoesophageal echocardiography (3D TOE) alone due to complete radiolucency of the tricuspid bioprosthesis. The procedure was completed without complication and resulted in significant symptomatic improvement. Deployment of an Edwards SAPIEN valve in a tricuspid bioprosthesis via the femoral vein is feasible and, with careful adaptations to established TAVI techniques, can be performed without complications and with good clinical response.

  16. Solenoid hammer valve developed for quick-opening requirements

    NASA Technical Reports Server (NTRS)

    Wrench, E. H.

    1967-01-01

    Quick-opening lightweight solenoid hammer valve requires a low amount of electrical energy to open, and closes by the restoring action of the mechanical springs. This design should be applicable to many quick-opening requirements in fluid systems.

  17. Study on stair-step liquid triggered capillary valve for microfluidic systems

    NASA Astrophysics Data System (ADS)

    Zhang, Lei; Jones, Ben; Majeed, Bivragh; Nishiyama, Yukari; Okumura, Yasuaki; Stakenborg, Tim

    2018-06-01

    In lab-on-a-chip systems, various microfluidic technologies are being developed to handle fluids at very small quantities, e.g. in the scale of nano- or pico-liter. To achieve autonomous fluid handling at a low cost, passive fluidic control, based on the capillary force between the liquid and microchannel surface, is of the utmost interest in the microsystem. Valves are an essential component for flow control in many microfluidic systems, which enables a sequence of fluidic operations to be performed. In this paper, we present a new passive valve structure for a capillary driven microfluidic device. It is a variation of a capillary trigger valve that is amenable to silicon microfabrication; it will be referred to as a stair-step liquid triggered valve. In this paper, the valve functionality and its dependencies on channel geometry, surface contact angle, and surface roughness are studied both experimentally and with numerical modeling. The effect of the contact angle was explored in experiments on the silicon microfabricated valve structure; a maximal working contact angle, above which the valve fails to be triggered, was demonstrated. The fluidic behavior in the stair-step channel structure was further explored computationally using the finite volume method with the volume-of-fluid approach. Surface roughness due to scalloping of the sidewall during the Bosch etch process was hypothesized to reduce the sidewall contact angle. The reduced contact angle has considerable impacts on the capillary pressure as the liquid vapor interface traverses the stair-step structure of the valve. An improved match in the maximal working contact angle between the experiments and model was obtained when considering this surface roughness effect.

  18. PMMA/PDMS valves and pumps for disposable microfluidics.

    PubMed

    Zhang, Wenhua; Lin, Shuichao; Wang, Chunming; Hu, Jia; Li, Cong; Zhuang, Zhixia; Zhou, Yongliang; Mathies, Richard A; Yang, Chaoyong James

    2009-11-07

    Poly(methyl methacrylate) (PMMA) is gaining in popularity in microfluidic devices because of its low cost, excellent optical transparency, attractive mechanical/chemical properties, and simple fabrication procedures. It has been used to fabricate micromixers, PCR reactors, CE and many other microdevices. Here we present the design, fabrication, characterization and application of pneumatic microvalves and micropumps based on PMMA. Valves and pumps are fabricated by sandwiching a PDMS membrane between PMMA fluidic channel and manifold wafers. Valve closing or opening can be controlled by adjusting the pressure in a displacement chamber on the pneumatic layer via a computer regulated solenoid. The valve provides up to 15.4 microL s(-1) at 60 kPa fluid pressure and seals reliably against forward fluid pressure as high as 60 kPa. A PMMA diaphragm pump can be assembled by simply connecting three valves in series. By varying valve volume or opening time, pumping rates ranging from nL to microL per second can be accurately achieved. The PMMA based valves and pumps were further tested in a disposable automatic nucleic acid extraction microchip to extract DNA from human whole blood. The DNA extraction efficiency was about 25% and the 260 nm/280 nm UV absorption ratio for extracted DNA was 1.72. Because of its advantages of inexpensive, facile fabrication, robust and easy integration, the PMMA valve and pump will find their wide application for fluidic manipulation in portable and disposable microfluidic devices.

  19. Optimal Control of the Valve Based on Traveling Wave Method in the Water Hammer Process

    NASA Astrophysics Data System (ADS)

    Cao, H. Z.; Wang, F.; Feng, J. L.; Tan, H. P.

    2011-09-01

    Valve regulation is an effective method for process control during the water hammer. The principle of d'Alembert traveling wave theory was used in this paper to construct the exact analytical solution of the water hammer, and the optimal speed law of the valve that can reduce the water hammer pressure in the maximum extent was obtained. Combining this law with the valve characteristic curve, the principle corresponding to the valve opening changing with time was obtained, which can be used to guide the process of valve closing and to reduce the water hammer pressure in the maximum extent.

  20. Control Valve

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Moore, Wayne R.

    A control valve includes a first conduit having a first inlet and a first outlet and defining a first passage; a second conduit having a second inlet and a second outlet and defining a second passage, the second conduit extending into the first passage such that the second inlet is located within the first passage; and a valve plate disposed pivotably within the first passage, the valve plate defining a valve plate surface. Pivoting of the valve plate within the first passage varies flow from the first inlet to the first outlet and the valve plate is pivotal between amore » first position and a second position such that in the first position the valve plate substantially prevents fluid communication between the first passage and the second passage and such that in the second position the valve plate permits fluid communication between the first passage and the second passage.« less

  1. Improving Charter School Accountability: The Challenge of Closing Failing Schools

    ERIC Educational Resources Information Center

    Osborne, David

    2012-01-01

    Today some 5,600 charter schools are in operation, with more than two million students. Some critics persist in a fruitless argument that these schools have failed, despite a mountain of evidence to the contrary. But regardless of your opinion about them, charter schools are here to stay. Those concerned about public education should quit debating…

  2. Knitting for heart valve tissue engineering

    PubMed Central

    Ayad, Nadia; Wojciechowska, Dorota; Zielińska, Dorota; Struszczyk, Marcin H.; Latif, Najma; Yacoub, Magdi

    Knitting is a versatile technology which offers a large portfolio of products and solutions of interest in heart valve (HV) tissue engineering (TE). One of the main advantages of knitting is its ability to construct complex shapes and structures by precisely assembling the yarns in the desired position. With this in mind, knitting could be employed to construct a HV scaffold that closely resembles the authentic valve. This has the potential to reproduce the anisotropic structure that is characteristic of the heart valve with the yarns, in particular the 3-layered architecture of the leaflets. These yarns can provide oriented growth of cells lengthwise and consequently enable the deposition of extracellular matrix (ECM) proteins in an oriented manner. This technique, therefore, has a potential to provide a functional knitted scaffold, but to achieve that textile engineers need to gain a basic understanding of structural and mechanical aspects of the heart valve and in addition, tissue engineers must acquire the knowledge of tools and capacities that are essential in knitting technology. The aim of this review is to provide a platform to consolidate these two fields as well as to enable an efficient communication and cooperation among these two research areas. PMID:29043276

  3. Development of Long-Lifetime Pulsed Gas Valves for Pulsed Electric Thrusters

    NASA Technical Reports Server (NTRS)

    Burkhardt, Wendel M.; Crapuchettes, John M.; Addona, Brad M.; Polzin, Kurt A.

    2015-01-01

    It is advantageous for gas-fed pulsed electric thrusters to employ pulsed valves so propellant is only flowing to the device during operation. The propellant utilization of the thruster will be maximized when all the gas injected into the thruster is acted upon by the fields produced by the electrical pulse. Gas that is injected too early will diffuse away from the thruster before the electrical pulse can act to accelerate the propellant. Gas that is injected too late will miss being accelerated by the already-completed electrical pulse. As a consequence, the valve must open quickly and close equally quickly, only remaining open for a short duration. In addition, the valve must have only a small amount of volume between the sealing body and the thruster so the front and back ends of the pulse are as coincident as possible with the valve cycling, with very little latent propellant remaining in the feed lines after the valve is closed. For a real mission of interest, a pulsed thruster can be expected to pulse at least 10(exp 10) - 10(exp 11) times, setting the range for the number of times a valve must open and close. The valves described in this paper have been fabricated and tested for operation in an inductive pulsed plasma thruster (IPPT) for in-space propulsion. In general, an IPPT is an electrodeless space propulsion device where a capacitor is charged to an initial voltage and then discharged, producing a high-current pulse through a coil. The field produced by this pulse ionizes propellant, inductively driving current in a plasma located near the face of the coil. Once the plasma is formed, it can be accelerated and expelled at a high exhaust velocity by the electromagnetic Lorentz body force arising from the interaction of the induced plasma current and the magnetic field produced by the current in the coil. The valve characteristics needed for the IPPT application require a fast-acting valve capable of a minimum of 10(exp 10) valve actuation cycles. Since

  4. Reliability of excess-flow check-valves in turbine lubrication systems

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Dundas, R.E.

    1996-12-31

    Reliability studies on excess-flow check valves installed in a gas turbine lubrication system for prevention of spray fires subsequent to fracture or separation of lube lines were conducted. Fault-tree analyses are presented for the case of failure of a valve to close when called upon by separation of a downstream line, as well as for the case of accidental closure during normal operation, leading to interruption of lubricating oil flow to a bearing. The probabilities of either of these occurrences are evaluated. The results of a statistical analysis of accidental closure of excess-flow check valves in commercial airplanes in themore » period 1986--91 are also given, as well as a summary of reliability studies on the use of these valves in residential gas installations, conducted under the sponsorship of the Gas Research Institute.« less

  5. Nuclear radiation actuated valve

    DOEpatents

    Christiansen, David W.; Schively, Dixon P.

    1985-01-01

    A nuclear radiation actuated valve for a nuclear reactor. The valve has a valve first part (such as a valve rod with piston) and a valve second part (such as a valve tube surrounding the valve rod, with the valve tube having side slots surrounding the piston). Both valve parts have known nuclear radiation swelling characteristics. The valve's first part is positioned to receive nuclear radiation from the nuclear reactor's fuel region. The valve's second part is positioned so that its nuclear radiation induced swelling is different from that of the valve's first part. The valve's second part also is positioned so that the valve's first and second parts create a valve orifice which changes in size due to the different nuclear radiation caused swelling of the valve's first part compared to the valve's second part. The valve may be used in a nuclear reactor's core coolant system.

  6. Dissection of the atrial wall after mitral valve replacement.

    PubMed Central

    Lukács, L; Kassai, I; Lengyel, M

    1996-01-01

    We describe an unusual sequela of mitral valve replacement in a 50-year-old woman who had undergone a closed mitral commissurotomy in 1975. She was admitted to our hospital because of mitral restenosis in November 1993, at which time her mitral valve was replaced with a mechanical prosthesis. On the 8th postoperative day, the patient developed symptoms of heart failure; transesophageal echocardiography revealed dissection and rupture of the left atrial wall. At prompt reoperation, we found an interlayer dissection and rupture of the atrial wall into the left atrium. We repaired the ruptured atrial wall with a prosthetic patch. The postoperative course was uneventful, and postoperative transesophageal echocardiography showed normal prosthetic valve function and no dissection. Images PMID:8680278

  7. Aortic valve repair using a differentiated surgical strategy.

    PubMed

    Langer, Frank; Aicher, Diana; Kissinger, Anke; Wendler, Olaf; Lausberg, Henning; Fries, Roland; Schäfers, Hans-Joachim

    2004-09-14

    Reconstruction of the aortic valve for aortic regurgitation (AR) remains challenging, in part because of not only cusp or root pathology but also a combination of both can be responsible for this valve dysfunction. We have systematically tailored the repair to the individual pathology of cusps and root. Between October 1995 and August 2003, aortic valve repair was performed in 282 of 493 patients undergoing surgery for AR and concomitant disease. Root dilatation was corrected by subcommissural plication (n=59), supracommissural aortic replacement (n=27), root remodeling (n=175), or valve reimplantation within a graft (n=24). Cusp prolapse was corrected by plication of the free margin (n=157) or triangular resection (n =36), cusp defects were closed with a pericardial patch (n=16). Additional procedures were arch replacement (n=114), coronary artery bypass graft (n=60) or mitral repair (n=24). All patients were followed-up (follow-up 99.6% complete), and cumulative follow-up was 8425 patient-months (mean, 33+/-27 months).Results- Eleven patients died in hospital (3.9%). Nine patients underwent reoperation for recurrent AR (3.3%). Actuarial freedom from AR grade > or =II at 5 years was 81% for isolated valve repair, 84% for isolated root replacement, and 94% for combination of both; actuarial freedom from reoperation at 5 years was 93%, 95%, and 98%, respectively. No thromboembolic events occurred, and there was 1 episode of endocarditis 4.5 years postoperatively. Aortic valve repair is feasible even for complex mechanisms of AR with a systematic and individually tailored approach. Operative mortality is low and mid-term durability is encouraging. The incidence of valve-related morbidity is low compared with valve replacement.

  8. Atrioventricular valve repair in patients with functional single-ventricle physiology: impact of ventricular and valve function and morphology on survival and reintervention.

    PubMed

    Honjo, Osami; Atlin, Cori R; Mertens, Luc; Al-Radi, Osman O; Redington, Andrew N; Caldarone, Christopher A; Van Arsdell, Glen S

    2011-08-01

    This study was to determine whether atrioventricular valve repair modifies natural history of single-ventricle patients with atrioventricular valve insufficiency and to identify factors predicting survival and reintervention. Fifty-seven (13.5%) of 422 single-ventricle patients underwent atrioventricular valve repair. Valve morphology, regurgitation mechanism, and ventricular morphology and function were analyzed for effect on survival, transplant, and reintervention with multivariate logistic and Cox regression models. Comparative analysis used case-matched controls. Atrioventricular valve was tricuspid in 67% and common in 28%. Ventricular morphology was right in 83%. Regurgitation mechanisms were prolapse (n = 24, 46%), dysplasia (n = 18, 35%), annular dilatation (n = 8, 15%), and restriction or cleft (n = 2, 4%). Postrepair insufficiency was none or trivial in 14 (26%), mild in 33 (61%), and moderate in 7 (13%). Survival in repair group was lower than in matched controls (78.9% vs 92.7% at 1 year, 68.7% vs 90.6% at 3 years, P = .015). Patients with successful repair and normal ventricular function had equivalent survival to matched controls (P = .36). Independent predictors for death or transplant included increased indexed annular size (P = .05), increased cardiopulmonary bypass time (P = .04), and decreased postrepair ventricular function (P = .01). Ventricular dilation was a time-related factor for all events, including failed repair. Survival was lower in single-ventricle patients operated on for atrioventricular valve insufficiency than in case-matched controls. Patients with little postoperative residual regurgitation and preserved ventricular function had equivalent survival to controls. Lower grade ventricular function and ventricular dilation correlated with death and repair failure, suggesting that timing of intervention may affect outcome. Copyright © 2011 The American Association for Thoracic Surgery. Published by Mosby, Inc. All

  9. Valve thrombosis following transcatheter aortic valve implantation: a systematic review.

    PubMed

    Córdoba-Soriano, Juan G; Puri, Rishi; Amat-Santos, Ignacio; Ribeiro, Henrique B; Abdul-Jawad Altisent, Omar; del Trigo, María; Paradis, Jean-Michel; Dumont, Eric; Urena, Marina; Rodés-Cabau, Josep

    2015-03-01

    Despite the rapid global uptake of transcatheter aortic valve implantation, valve trombosis has yet to be systematically evaluated in this field. The aim of this study was to determine the clinical characteristics, diagnostic criteria, and treatment outcomes of patients diagnosed with valve thrombosis following transcatheter aortic valve implantation through a systematic review of published data. Literature published between 2002 and 2012 on valve thrombosis as a complication of transcatheter aortic valve implantation was identified through a systematic electronic search. A total of 11 publications were identified, describing 16 patients (mean age, 80 [5] years, 65% men). All but 1 patient (94%) received a balloon-expandable valve. All patients received dual antiplatelet therapy immediately following the procedure and continued to take either mono- or dual antiplatelet therapy at the time of valve thrombosis diagnosis. Valve thrombosis was diagnosed at a median of 6 months post-procedure, with progressive dyspnea being the most common symptom. A significant increase in transvalvular gradient (from 10 [4] to 40 [12] mmHg) was the most common echocardiographic feature, in addition to leaflet thickening. Thrombus was not directly visualized with echocardiography. Three patients underwent valve explantation, and the remaining received warfarin, which effectively restored the mean transvalvular gradient to baseline within 2 months. Systemic embolism was not a feature of valve thrombosis post-transcatheter aortic valve implantation. Although a rare, yet likely under-reported complication of post-transcatheter aortic valve implantation, progressive dyspnea coupled with an increasing transvalvular gradient on echocardiography within the months following the intervention likely signifies valve thrombosis. While direct thrombus visualization appears difficult, prompt initiation of oral anticoagulation therapy effectively restores baseline valve function. Copyright © 2014

  10. External stress-corrosion cracking of a 1.22-m-diameter type 316 stainless steel air valve

    NASA Technical Reports Server (NTRS)

    Moore, Thomas J.; Telesman, Jack; Moore, Allan S.; Johnson, Dereck F.; Kuivinen, David E.

    1993-01-01

    An investigation was conducted to determine the cause of the failure of a massive AISI Type 316 stainless steel valve which controlled combustion air to a jet engine test facility. Several through-the-wall cracks were present near welded joints in the valve skirt. The valve had been in outdoor service for 18 years. Samples were taken in the cracked regions for metallographic and chemical analyses. Insulating material and sources of water mist in the vicinity of the failed valve were analyzed for chlorides. A scanning electron microscope was used to determine whether foreign elements were present in a crack. On the basis of the information generated, the failure was characterized as external stress-corrosion cracking. The cracking resulted from a combination of residual tensile stress from welding and the presence of aqueous chlorides. Recommended countermeasures are included.

  11. JenaValve.

    PubMed

    Treede, Hendrik; Rastan, Ardawan; Ferrari, Markus; Ensminger, Stephan; Figulla, Hans-Reiner; Mohr, Friedrich-Wilhelm

    2012-09-01

    The JenaValve is a next-generation TAVI device which consists of a well-proven porcine root valve mounted on a low-profile nitinol stent. Feeler guided positioning and clip fixation on the diseased leaflets allow for anatomically correct implantation of the device without rapid pacing. Safety and efficacy of transapical aortic valve implantation using the JenaValve were evaluated in a multicentre prospective study that showed good short and midterm results. The valve was CE-mark released in Europe in September 2011. A post-market registry ensures on-going and prospective data collection in "real-world" patients. The transfemoral JenaValve delivery system will be evaluated in a first-in-man study in the near future.

  12. Application Of Light Valves For Continuous-Tone Printing

    NASA Astrophysics Data System (ADS)

    Vergona, Albert B.

    1989-07-01

    New opportunities are emerging in the graphic-arts pre-press market stimulated by the need for digitally created images. To meet this need, we have designed a cost-effective three-color digital printer using PLZT light valves. Transparent lead lanthanum zirconate titanate (PLZT) ceramic crystals when used as a linear modulator offer a number of significant benefits. The primary advantage is that the light valve is an efficient modulator of incoherent light providing a broad spectral output ranging from 400nm to well into the infrared region. In addition, light valves offer the advantages of being small, low cost, have a wide dynamic range (>1000 to 1), and can be used with simple optical designs. The characteristics of the PLZT material plays an important role in the performance of the light valve. A number of variables such as ceramic composition, electrode spacing, and ceramic thickness can be altered to affect its quadratic electrooptic behavior. Additionally, the modulator design requires a closed-loop servo to eliminate the errors caused by the device's remanent polarization and nonlinear behavior.

  13. Needle Revision With 5-fluorouracil for the Treatment of Ahmed Glaucoma Valve Filtering Blebs: 5-Fluoruracil Needling Revision can be a Useful and Safe Tool in the Management of Failing Ahmed Glaucoma Valve Filtering Blebs.

    PubMed

    Quaranta, Luciano; Floriani, Irene; Hollander, Lital; Poli, Davide; Katsanos, Andreas; Konstas, Anastasios G P

    2016-04-01

    To determine the outcome of needling with adjunctive 5-fluorouracil (5-FU) in patients with a failing Ahmed glaucoma valve (AGV) implant, and to identify predictors of long-term intraocular pressure (IOP) control. A prospective observational study was performed on consecutive patients with medically uncontrolled primary open-angle glaucoma (POAG) with AGV encapsulation or fibrosis and inadequate IOP control. Bleb needling with 5-FU injection (0.1 mL of 50 mg/mL) was performed at the slit-lamp. Patients were examined 1 week following the needling, and then at months 1, 3, and 6. Subsequent follow-up visits were scheduled at 6-month intervals for at least 2 years. Needling with 5-FU was repeated no more than twice during the first 3 months of the follow-up. Procedure outcome was determined on the basis of the recorded IOP levels. Thirty-six patients with an encapsulated or fibrotic AGV underwent 67procedures (mean 1.86 ± 0.83). Complete success, defined as IOP ≤ 18 mm Hg without medications, was obtained in 25% at 24 months of observation. The cumulative proportion of cases achieving either qualified (ie, IOP ≤ 18 mm Hg with medications) or complete success at 24 months of observation was 72.2%. In a univariate Cox proportional hazards model, age was the only variable that independently influenced the risk of failing 5-FU needling revision. Fourteen eyes (38.8%) had a documented complication. Needling over the plate of an AGV supplemented with 5-FU is an effective and safe choice in a significant proportion of POAG patients with elevated IOP due to encapsulation or fibrosis.

  14. Design and test of a simple fast electromagnetic inductive gas valve for planar pulsed inductive plasma thruster

    NASA Astrophysics Data System (ADS)

    Guo, Dawei; Cheng, Mousen; Li, Xiaokang

    2017-10-01

    In support of our planar pulsed inductive plasma thruster research, a fast electromagnetic inductive valve for a gas propellant injection system has been built and tested. A new and important design feature is the use of a conical diaphragm as the action part, which greatly contributes to the virtue of simplicity for adopting the resultant force of the diaphragm deformation as the closing force. An optical transmission technique is adopted to measure the opening and closing characters of the valve while the gas throughput is determined by measuring the pressure change per pulse in a test chamber with a capacitance manometer. The experimental results revealed that the delay time before the valve reaction is less than 40 μs, and the valve pulse width is no longer than 160 μs full width at half maximum. The valve delivers 0-2.5 mg of argon gas per pulse varied by adjusting the drive voltage and gas pressure.

  15. Design and test of a simple fast electromagnetic inductive gas valve for planar pulsed inductive plasma thruster.

    PubMed

    Guo, Dawei; Cheng, Mousen; Li, Xiaokang

    2017-10-01

    In support of our planar pulsed inductive plasma thruster research, a fast electromagnetic inductive valve for a gas propellant injection system has been built and tested. A new and important design feature is the use of a conical diaphragm as the action part, which greatly contributes to the virtue of simplicity for adopting the resultant force of the diaphragm deformation as the closing force. An optical transmission technique is adopted to measure the opening and closing characters of the valve while the gas throughput is determined by measuring the pressure change per pulse in a test chamber with a capacitance manometer. The experimental results revealed that the delay time before the valve reaction is less than 40 μs, and the valve pulse width is no longer than 160 μs full width at half maximum. The valve delivers 0-2.5 mg of argon gas per pulse varied by adjusting the drive voltage and gas pressure.

  16. The development of a microprocessor-controlled linearly-actuated valve assembly

    NASA Technical Reports Server (NTRS)

    Wall, R. H.

    1984-01-01

    The development of a proportional fluid control valve assembly is presented. This electromechanical system is needed for space applications to replace the current proportional flow controllers. The flow is controlled by a microprocessor system that monitors the control parameters of upstream pressure and requested volumetric flow rate. The microprocessor achieves the proper valve stem displacement by means of a digital linear actuator. A linear displacement sensor is used to measure the valve stem position. This displacement is monitored by the microprocessor system as a feedback signal to close the control loop. With an upstream pressure between 15 and 47 psig, the developed system operates between 779 standard CU cm/sec (SCCS) and 1543 SCCS.

  17. Fluid-structure interaction in the left ventricle of the human heart coupled with mitral valve

    NASA Astrophysics Data System (ADS)

    Meschini, Valentina; de Tullio, Marco Donato; Querzoli, Giorgio; Verzicco, Roberto

    2016-11-01

    In this paper Direct Numerical Simulations (DNS), implemented using a fully fluid-structure interaction model for the left ventricle, the mitral valve and the flowing blood, and laboratory experiments are performed in order to cross validate the results. Moreover a parameter affecting the flow dynamics is the presence of a mitral valve. We model two cases, one with a natural mitral valve and another with a prosthetic mechanical one. Our aim is to understand their different effects on the flow inside the left ventricle in order to better investigate the process of valve replacement. We simulate two situations, one of a healthy left ventricle and another of a failing one. While in the first case the flow reaches the apex of the left ventricle and washout the stagnant fluid with both mechanical and natural valve, in the second case the disturbance generated by the mechanical leaflets destabilizes the mitral jet, thus further decreasing its capability to penetrate the ventricular region and originating heart attack or cardiac pathologies in general.

  18. 46 CFR 154.530 - Valves: Cargo tank MARVS 69 kPa gauge (10 psig) or lower.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Valves: Cargo tank MARVS 69 kPa gauge (10 psig) or lower..., Construction and Equipment Cargo and Process Piping Systems § 154.530 Valves: Cargo tank MARVS 69 kPa gauge (10... a MARVS of 69 kPa gauge (10 psig) or lower must have shut-off valves that— (1) Are located as close...

  19. Impact of Chronic Rheumatic Valve Diseases on Large Vessels.

    PubMed

    Altunbas, Gokhan; Yuce, Murat; Ozer, Hasan O; Davutoglu, Vedat; Ercan, Suleyman; Kizilkan, Nese; Bilici, Muhammet

    2016-01-01

    BACKGROUND AND AIM OF STUDY: Rheumatic valvular heart disease, which remains a common health problem in developing countries, has numerous consequences on the heart chambers and circulation. The study aim was to investigate the effects of chronic rheumatic valve disease on the diameters of the descending aorta (DA) and inferior vena cava (IVC). METHODS: A total of 88 patients with echocardiographically documented rheumatic valvular heart disease and 112 healthy controls were enrolled into the study. All patients underwent detailed echocardiographic examinations, while their height and body weight were recorded and adjusted to their body surface area. RESULTS: The most common involvement was mitral valve disease, followed by aortic valve disease and tricuspid valve disease. The mean diameter of the DA (indexed to BSA) was 1.79 ± 0.49 cm for patients and 1.53 ± 0.41 for controls (p <0.001). The mean diameter of the IVC (indexed to BSA) was 1.69 ± 0.73 for patients and 1.38 ± 0.35 cm for controls (p <0.001). There was a significant positive correlation between mitral valve mean gradient and IVC diameter (p = 0.01, r = 0.18). There were also strong associations between the mitral valve area and the diameters of the DA (p = 0.001, r = -0.239) and IVC (p <0.001, r = -0.246). CONCLUSION: Rheumatic valve disease, especially mitral stenosis, was closely related to remodeling of the great vessels.

  20. Tricuspid valve and percutaneous approach: No longer the forgotten valve!

    PubMed

    Bouleti, Claire; Juliard, Jean-Michel; Himbert, Dominique; Iung, Bernard; Brochet, Eric; Urena, Marina; Dilly, Marie-Pierre; Ou, Phalla; Nataf, Patrick; Vahanian, Alec

    2016-01-01

    Tricuspid valve disease is mainly represented by tricuspid regurgitation (TR), which is a predictor of poor outcome. TR is usually secondary, caused by right ventricle pressure or volume overload, the leading cause being left-sided heart valve diseases. Tricuspid surgery for severe TR is recommended during left valve surgery, and consists of either a valve replacement or, most often, a tricuspid repair with or without prosthetic annuloplasty. When TR persists or worsens after left valvular surgery, redo isolated tricuspid surgery is associated with high mortality. In addition, a sizeable proportion of patients present with tricuspid surgery deterioration over time, and need a reintervention, which is associated with high morbi-mortality rates. In this context, and given the recent major breakthrough in the percutaneous treatment of aortic and mitral valve diseases, the tricuspid valve appears an appealing challenge, although it raises specific issues. The first applications of transcatheter techniques for tricuspid valve disease were valve-in-valve and valve-in-ring implantation for degenerated bioprosthesis or ring annuloplasty. Some concerns remain regarding prosthesis sizing, rapid ventricular pacing and the best approach, but these procedures appear to be safe and effective. More recently, bicuspidization using a transcatheter approach for the treatment of native tricuspid valve has been published, in two patients. Finally, other devices are in preclinical development. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

  1. Solenoid valve, type 1, NASA P/N 20M32258-1 (Carleton P/N 2426-0001-1)

    NASA Technical Reports Server (NTRS)

    Baczkowski, M. L.

    1972-01-01

    The design, development, and evaluation of a solenoid valve assembly are discussed. The valve is a two-way, normally closed configuration for use as a control element in the metabolic analyzer of biomedical experiments during Skylab missions.

  2. Tissue engineering of heart valves: in vitro experiences.

    PubMed

    Sodian, R; Hoerstrup, S P; Sperling, J S; Daebritz, S H; Martin, D P; Schoen, F J; Vacanti, J P; Mayer, J E

    2000-07-01

    Tissue engineering is a new approach, whereby techniques are being developed to transplant autologous cells onto biodegradable scaffolds to ultimately form new functional tissue in vitro and in vivo. Our laboratory has focused on the tissue engineering of heart valves, and we have fabricated a trileaflet heart valve scaffold from a biodegradable polymer, a polyhydroxyalkanoate. In this experiment we evaluated the suitability of this scaffold material as well as in vitro conditioning to create viable tissue for tissue engineering of a trileaflet heart valve. We constructed a biodegradable and biocompatible trileaflet heart valve scaffold from a porous polyhydroxyalkanoate (Meatabolix Inc, Cambridge, MA). The scaffold consisted of a cylindrical stent (1 x 15 x 20 mm inner diameter) and leaflets (0.3 mm thick), which were attached to the stent by thermal processing techniques. The porous heart valve scaffold (pore size 100 to 240 microm) was seeded with vascular cells grown and expanded from an ovine carotid artery and placed into a pulsatile flow bioreactor for 1, 4, and 8 days. Analysis of the engineered tissue included biochemical examination, enviromental scanning electron microscopy, and histology. It was possible to create a trileaflet heart valve scaffold from polyhydroxyalkanoate, which opened and closed synchronously in a pulsatile flow bioreactor. The cells grew into the pores and formed a confluent layer after incubation and pulsatile flow exposure. The cells were mostly viable and formed connective tissue between the inside and the outside of the porous heart valve scaffold. Additionally, we demonstrated cell proliferation (DNA assay) and the capacity to generate collagen as measured by hydroxyproline assay and movat-stained glycosaminoglycans under in vitro pulsatile flow conditions. Polyhydroxyalkanoates can be used to fabricate a porous, biodegradable heart valve scaffold. The cells appear to be viable and extracellular matrix formation was induced

  3. Ultrasound based mitral valve annulus tracking for off-pump beating heart mitral valve repair

    NASA Astrophysics Data System (ADS)

    Li, Feng P.; Rajchl, Martin; Moore, John; Peters, Terry M.

    2014-03-01

    Mitral regurgitation (MR) occurs when the mitral valve cannot close properly during systole. The NeoChordtool aims to repair MR by implanting artificial chordae tendineae on flail leaflets inside the beating heart, without a cardiopulmonary bypass. Image guidance is crucial for such a procedure due to the lack of direct vision of the targets or instruments. While this procedure is currently guided solely by transesophageal echocardiography (TEE), our previous work has demonstrated that guidance safety and efficiency can be significantly improved by employing augmented virtuality to provide virtual presentation of mitral valve annulus (MVA) and tools integrated with real time ultrasound image data. However, real-time mitral annulus tracking remains a challenge. In this paper, we describe an image-based approach to rapidly track MVA points on 2D/biplane TEE images. This approach is composed of two components: an image-based phasing component identifying images at optimal cardiac phases for tracking, and a registration component updating the coordinates of MVA points. Preliminary validation has been performed on porcine data with an average difference between manually and automatically identified MVA points of 2.5mm. Using a parallelized implementation, this approach is able to track the mitral valve at up to 10 images per second.

  4. Two-phase flow patterns of a top heat mode closed loop oscillating heat pipe with check valves (THMCLOHP/CV)

    NASA Astrophysics Data System (ADS)

    Thongdaeng, S.; Bubphachot, B.; Rittidech, S.

    2016-11-01

    This research is aimed at studying the two-phase flow pattern of a top heat mode closed loop oscillating heat pipe with check valves. The working fluids used are ethanol and R141b and R11 coolants with a filling ratio of 50% of the total volume. It is found that the maximum heat flux occurs for the R11 coolant used as the working fluid in the case with the inner diameter of 1.8 mm, inclination angle of -90°, evaporator temperature of 125°C, and evaporator length of 50 mm. The internal flow patterns are found to be slug flow/disperse bubble flow/annular flow, slug flow/disperse bubble flow/churn flow, slug flow/bubble flow/annular flow, slug flow/disperse bubble flow, bubble flow/annular flow, and slug flow/annular flow.

  5. Analysis of hydrodynamic losses for various types of aortic valves

    NASA Astrophysics Data System (ADS)

    Starobin, I. M.; Lupachev, S. P.; Dolgopolov, R. V.; Zaiko, V. M.; Kas'yanov, V. A.; Mungalov, D. D.; Morov, G. V.

    1985-05-01

    The creation of an automated computer-controlled hydraulic stand made it possible to measure the main hydrodynamic parameters of the flow through the investigated HVP and to determine the coefficients of Eq. (2) of fluid flow in the test chamber of the stand. The coefficients found can serve as a criterion of a comparative assessment of the hydrodynamics of HVPs. An analysis of the coefficients showed that the main contribution to pressure losses across ball and disc valves is made by viscous and convective effects. An analysis of inertial losses confirmed the presence of oscillations of the ball closing elements of the AKCh-3-06 valve around the props of the stroke limiters and made it possible to assess them quantitatively. For leaflet valves the contribution of inertial losses to the total pressure losses is more considerable than in the case of disc and ball valves both in the regime of an increase of power of the output and in the regime of a constant power. The mechanical properties of the material of leaflet valves have an effect on the hydrodynamic characteristics. The advantage of the investigated leaflet valves consists not only in that they have smaller total hydraulic losses compared with the other valves, but also in that they provide a high amplitude of pulsations of the blood stream in the case of insufficient contractility of the heart.

  6. Mathematical multi-scale model of the cardiovascular system including mitral valve dynamics. Application to ischemic mitral insufficiency

    PubMed Central

    2011-01-01

    Background Valve dysfunction is a common cardiovascular pathology. Despite significant clinical research, there is little formal study of how valve dysfunction affects overall circulatory dynamics. Validated models would offer the ability to better understand these dynamics and thus optimize diagnosis, as well as surgical and other interventions. Methods A cardiovascular and circulatory system (CVS) model has already been validated in silico, and in several animal model studies. It accounts for valve dynamics using Heaviside functions to simulate a physiologically accurate "open on pressure, close on flow" law. However, it does not consider real-time valve opening dynamics and therefore does not fully capture valve dysfunction, particularly where the dysfunction involves partial closure. This research describes an updated version of this previous closed-loop CVS model that includes the progressive opening of the mitral valve, and is defined over the full cardiac cycle. Results Simulations of the cardiovascular system with healthy mitral valve are performed, and, the global hemodynamic behaviour is studied compared with previously validated results. The error between resulting pressure-volume (PV) loops of already validated CVS model and the new CVS model that includes the progressive opening of the mitral valve is assessed and remains within typical measurement error and variability. Simulations of ischemic mitral insufficiency are also performed. Pressure-Volume loops, transmitral flow evolution and mitral valve aperture area evolution follow reported measurements in shape, amplitude and trends. Conclusions The resulting cardiovascular system model including mitral valve dynamics provides a foundation for clinical validation and the study of valvular dysfunction in vivo. The overall models and results could readily be generalised to other cardiac valves. PMID:21942971

  7. Fixation and mounting of porcine aortic valves for use in mock circuits.

    PubMed

    Schlöglhofer, Thomas; Aigner, Philipp; Stoiber, Martin; Schima, Heinrich

    2013-10-01

    Investigations of the circulatory system in vitro use mock circuits that require valves to mimic the cardiac situation. Whereas mechanical valves increase water hammer effects due to inherent stiffness and do not allow the use of pressure lines or catheters, bioprosthetic valves are expensive and of limited durability in test fluids. Therefore, we developed a cheap, fast, alternative method to mount valves obtained from the slaughterhouse in mock circuits. Porcine aortic roots were obtained from the abattoir and used either in native condition or after fixation. Fixation was performed at a constant retrograde pressure to ensure closed valve position. Fixation time was 4 h in a 0.5%-glutaraldehyde phosphate buffer. The fixed valves were molded into a modular mock circulation connector using a fast curing silicone. Valve functionality was evaluated in a pulsatile setting (cardiac output = 4.7 l/min, heart rate = 80 beats/min) and compared before and after fixation. Leaflet motion was recorded with a high-speed camera and valve insufficiency was quantified by leakage flow under steady pressure application (80 mmHg). Under physiological conditions the aortic valves showed almost equal leaflet motion in native and fixed conditions. However, the leaflets of the native valves showed lower stiffness and more fluttering during systole than the fixed specimens. Under retrograde pressure, fresh and fixed valves showed small leakage flows of <30 ml/min. The new mounting and fixation procedure is a fast method to fabricate low cost biologic valves for the use in mock circuits.

  8. Curved butterfly bileaflet prosthetic cardiac valve

    DOEpatents

    McQueen, David M.; Peskin, Charles S.

    1991-06-25

    An annular valve body having a central passageway for the flow of blood therethrough with two curved leaflets each of which is pivotally supported on an accentric positioned axis in the central passageway for moving between a closed position and an open position. The leaflets are curved in a plane normal to the eccentric axis and positioned with the convex side of the leaflets facing each other when the leaflets are in the open position. Various parameters such as the curvature of the leaflets, the location of the eccentric axis, and the maximum opening angle of the leaflets are optimized according to the following performance criteria: maximize the minimum peak velocity through the valve, maximize the net stroke volume, and minimize the mean forward pressure difference, thereby reducing thrombosis and improving the hemodynamic performance.

  9. [Percutaneously implantable aortic valve: the JenaValve concept evolution].

    PubMed

    Figulla, Hans R; Ferrari, Markus

    2006-10-01

    Due to the increasing incidence of severe aortic stenosis in old and multimorbid patients, the percutaneous implantation of aortic valve-carrying stents has become an alternative to the surgical replacement of aortic valves. Starting in 1995, the authors developed a self-expanding stent which transferred the necessary forces for anchoring up to the aorta ascendens-a conception taken over from CoreValve. The further improvement of this idea over the past 11 years has led to a self-expanding, relatively short stent-valve system that is reliably positioned in the cusps of the old aortic valve and holds the old valve like a paper clip, thus transferring the holding forces physiologically. As compared to conventional systems, the sophisticated insertion catheter requires further chronic animal tests so as to represent a true alternative to the conventional surgical procedure.

  10. Heart sounds as a result of acoustic dipole radiation of heart valves

    NASA Astrophysics Data System (ADS)

    Kasoev, S. G.

    2005-11-01

    Heart sounds are associated with impulses of force acting on heart valves at the moment they close under the action of blood-pressure difference. A unified model for all the valves represents this impulse as an acoustic dipole. The near pressure field of this dipole creates a distribution of the normal velocity on the breast surface with features typical of auscultation practice: a pronounced localization of heart sound audibility areas, an individual area for each of the valves, and a noncoincidence of these areas with the projections of the valves onto the breast surface. In the framework of the dipole theory, the optimum size of the stethoscope’s bell is found and the spectrum of the heart sounds is estimated. The estimates are compared with the measured spectrum.

  11. Outcome of bioprosthetic valve replacement in dogs with tricuspid valve dysplasia.

    PubMed

    Bristow, P; Sargent, J; Luis Fuentes, V; Brockman, D

    2017-04-01

    To describe the short-term and long-term outcome in dogs with tricuspid valve dysplasia undergoing tricuspid valve replacement under cardiopulmonary bypass. Data were collected from the hospital records of all dogs that had undergone tricuspid valve replacement under cardiopulmonary bypass between 2006 and 2012. Dogs were considered candidates for tricuspid valve replacement if they had severe tricuspid valve regurgitation associated with clinical signs of cardiac compromise. Nine dogs of six different breeds were presented. Median age was 13 months (range 7 to 61 months), median weight 26·5 kg (range 9·7 to 59 kg). Eight bovine pericardial valves and one porcine aortic valve were used. One non-fatal intraoperative complication occurred. Complications during hospitalisation occurred in six dogs, four of which were fatal. Of the five dogs discharged, one presented dead due to haemothorax after minor trauma seven days later. The four remaining dogs survived a median of 533 days; all of these dogs received a bovine pericardial valve. Based on our results, tricuspid valve replacement with bovine or porcine prosthetic valves is associated with a high incidence of complications. © 2017 British Small Animal Veterinary Association.

  12. Durability of hand-sewn valves in the right ventricular outlet.

    PubMed

    Nunn, Graham R; Bennetts, Jayme; Onikul, Ella

    2008-08-01

    The objective was to compare the medium- and long-term outcomes for pericardial monocusp valves, polytetrafluoroethylene (Gore-Tex, WL Gore and Associates Inc, Flagstaff, Ariz) 0.1-mm monocusp valves, and bileaflet 0.l-mm polytetrafluoroethylene valves and their efficiency in the right ventricular outlet. We reviewed all hand-sewn right ventricular outlet valves created by the author (Graham R. Nunn) in the setting of repaired tetralogy of Fallot or equivalent right ventricular outlet pathology when the native pulmonary valve could not be preserved. The valves were assessed by serial transthoracic echocardiography and more recently by magnetic resonance imaging angiography for late valve function. The bileaflet polytetrafluoroethylene valves were constructed in a standardized fashion from a semicircle of 0.1-mm polytetrafluoroethylene (the radius of which equaled the length of the outflow tract incision) that gave a lengthened free edge to the leaflets, central fixation of the free edge posteriorly just proximal to the branch pulmonary arteries, and generous augmentation of the outflow tract with polytetrafluoroethylene patch-plasty. The bileaflet configuration shortens the closing time against the posterior wall, and the leaflets are forced to maintain their configuration without prolapse into the right ventricular outlet. The valve can be generously oversized in young children to try to avoid the need for replacement. A total of 54 patients met the selection criteria--22 patients received fresh autologous pericardial monocusps, 7 patients received polytetrafluoroethylene (0.1-mm) monocusps, and 25 patients received bileaflet polytetrafluoroethylene (0.1-mm) outlet valves. The pericardial valves have the longest follow-up, and all valves developed free pulmonary incompetence. Polytetrafluoroethylene monocusps had reliable competence early after surgery but progressed to pulmonary incompetence. The bileaflet polytetrafluoroethylene (0.1-mm) valves have remained

  13. Ball valve extractor

    DOEpatents

    Herndon, Charles; Brown, Roger A.

    2002-01-01

    An apparatus and process for removing a ball valve is provided. The ball valve removal tool provides a handle sliding along the length of a shaft. One end of the shaft is secured within an interior cavity of a ball valve while the opposite end of the shaft defines a stop member. By providing a manual sliding force to the handle, the handle impacts the stop member and transmits the force to the ball valve. The direction of the force is along the shaft of the removal tool and disengages the ball valve from the ball valve housing.

  14. Bellows sealed plug valve

    DOEpatents

    Dukas, Jr., Stephen J.

    1990-01-01

    A bellows sealed plug valve includes a valve body having an inlet passage and an outlet passage, a valve chamber between the inlet and outlet passages. A valve plug has substantially the same shape as the valve chamber and is rotatably disposed therein. A shaft is movable linearly in response to a signal from a valve actuator. A bellows is sealingly disposed between the valve chamber and the valve actuator and means are located between the bellows and the valve plug for converting linear movement of the shaft connected to the valve actuator to rotational movement of the plug. Various means are disclosed including helical thread mechanism, clevis mechanism and rack and pinion mechanism, all for converting linear motion to rotational motion.

  15. Check valve installation in pilot operated relief valve prevents reverse pressurization

    NASA Technical Reports Server (NTRS)

    Oswalt, L.

    1966-01-01

    Two check valves prevent reverse flow through pilot-operated relief valves of differential area piston design. Title valves control pressure flow to ensure that the piston dome pressure is always at least as great as the main relief valve discharge pressure.

  16. Dynamic performance of high speed solenoid valve with parallel coils

    NASA Astrophysics Data System (ADS)

    Kong, Xiaowu; Li, Shizhen

    2014-07-01

    The methods of improving the dynamic performance of high speed on/off solenoid valve include increasing the magnetic force of armature and the slew rate of coil current, decreasing the mass and stroke of moving parts. The increase of magnetic force usually leads to the decrease of current slew rate, which could increase the delay time of the dynamic response of solenoid valve. Using a high voltage to drive coil can solve this contradiction, but a high driving voltage can also lead to more cost and a decrease of safety and reliability. In this paper, a new scheme of parallel coils is investigated, in which the single coil of solenoid is replaced by parallel coils with same ampere turns. Based on the mathematic model of high speed solenoid valve, the theoretical formula for the delay time of solenoid valve is deduced. Both the theoretical analysis and the dynamic simulation show that the effect of dividing a single coil into N parallel sub-coils is close to that of driving the single coil with N times of the original driving voltage as far as the delay time of solenoid valve is concerned. A specific test bench is designed to measure the dynamic performance of high speed on/off solenoid valve. The experimental results also prove that both the delay time and switching time of the solenoid valves can be decreased greatly by adopting the parallel coil scheme. This research presents a simple and practical method to improve the dynamic performance of high speed on/off solenoid valve.

  17. Design of Epoxy based Resin Composites for Automotive Applications: A Case Study on IC Engine Valve Guide

    NASA Astrophysics Data System (ADS)

    Sidhu, J. S.; Lathkar, G. S.; Sharma, S. B.

    2018-01-01

    The present attempt in this project is to reduce the vibrations, temperature due to friction, noise and weight of I C engine valve guide by replacing conventional metal valve guide with composite valve guide. Composite materials have been used in automotive components because of their properties such as low weight, high specific stiffness, corrosion resistance, ability to produce complex shapes, high specific strength and good impact energy absorption etc. The Internal combustion engine valve guides are the parts that support the valves in the cylinder head, besides this it keeps lubricating oil from getting sucked into the combustion chamber past the intake valve stem, it keeps exhaust gases from getting into the crankcase past the exhaust valve stem and it also keeps the valve face in perfect alignment with the valve seat. A valve guide test rig is indigenously fabricated. Valve guides are manufactured using the developed composite material (Resin ARL-136, Hardener AH-126 and 4 vol% WS2), on a CNC lathe. The performance of the developed composite guide under varied conditions of speeds, that is, fixed change in rpm and modulated changes in rpm is assessed. Noise, temperature and vibrations are measured. The experimental data revealed that contribution of composite guide in respect of acceleration, velocity and displacement components of vibration is not substantial. A substantial reduction in noise levels is seen. As far as temperature rise due to friction is concerned maximum components fail at elevated temperatures, with composite guides the temperature generated due to friction at higher speeds is less, a considerable weight reduction is also observed.

  18. Particle image velocimetry study of pulsatile flow in bi-leaflet mechanical heart valves with image compensation method.

    PubMed

    Shi, Yubing; Yeo, Tony Joon Hock; Zhao, Yong; Hwang, Ned H C

    2006-12-01

    Particle Image Velocimetry (PIV) is an important technique in studying blood flow in heart valves. Previous PIV studies of flow around prosthetic heart valves had different research concentrations, and thus never provided the physical flow field pictures in a complete heart cycle, which compromised their pertinence for a better understanding of the valvular mechanism. In this study, a digital PIV (DPIV) investigation was carried out with improved accuracy, to analyse the pulsatile flow field around the bi-leaflet mechanical heart valve (MHV) in a complete heart cycle. For this purpose a pulsatile flow test rig was constructed to provide the necessary in vitro test environment, and the flow field around a St. Jude size 29 bi-leaflet MHV and a similar MHV model were studied under a simulated physiological pressure waveform with flow rate of 5.2 l/min and pulse rate at 72 beats/min. A phase-locking method was applied to gate the dynamic process of valve leaflet motions. A special image-processing program was applied to eliminate optical distortion caused by the difference in refractive indexes between the blood analogue fluid and the test section. Results clearly showed that, due to the presence of the two leaflets, the valvular flow conduit was partitioned into three flow channels. In the opening process, flow in the two side channels was first to develop under the presence of the forward pressure gradient. The flow in the central channel was developed much later at about the mid-stage of the opening process. Forward flows in all three channels were observed at the late stage of the opening process. At the early closing process, a backward flow developed first in the central channel. Under the influence of the reverse pressure gradient, the flow in the central channel first appeared to be disturbed, which was then transformed into backward flow. The backward flow in the central channel was found to be the main driving factor for the leaflet rotation in the valve

  19. Experimentally validated quantitative linear model for the device physics of elastomeric microfluidic valves

    NASA Astrophysics Data System (ADS)

    Kartalov, Emil P.; Scherer, Axel; Quake, Stephen R.; Taylor, Clive R.; Anderson, W. French

    2007-03-01

    A systematic experimental study and theoretical modeling of the device physics of polydimethylsiloxane "pushdown" microfluidic valves are presented. The phase space is charted by 1587 dimension combinations and encompasses 45-295μm lateral dimensions, 16-39μm membrane thickness, and 1-28psi closing pressure. Three linear models are developed and tested against the empirical data, and then combined into a fourth-power-polynomial superposition. The experimentally validated final model offers a useful quantitative prediction for a valve's properties as a function of its dimensions. Typical valves (80-150μm width) are shown to behave like thin springs.

  20. The early and midterm function of decellularized aortic valve allografts.

    PubMed

    da Costa, Francisco D A; Costa, Ana Claudia B A; Prestes, Roberta; Domanski, Ana Carolina; Balbi, Eduardo Mendel; Ferreira, Andreia D A; Lopes, Sergio Veiga

    2010-12-01

    This study evaluates the early and midterm results of decellularized aortic valve allografts (DAVA) as an aortic valve replacement. Between October 2005 and February 2010, 41 patients, 28 of whom were male, with a median age of 34 years (range, 0.1 to 71), had aortic valve replacement with DAVA. Decellularization was obtained with a 0.1% sodium dodecyl sulfate solution. Postoperative evaluation was performed with serial echocardiograms, magnetic resonance imaging, and multislice computed tomography studies to evaluate valve hemodynamics, allograft conduit dimensions, and calcification scores. There were 3 early deaths and 1 late death, with a mean follow-up of 19 months (range, 1 to 53). There was 1 reoperation due to a failed mitral valve repair. By echocardiography in all patients, the median immediate postoperative peak gradient was 7 mm Hg (range, 1 to 26 mm Hg), and at last follow-up it was 4 mm Hg (range, 1 to 16 mm Hg); valvular regurgitation was graded as none or trivial in all but 1 patient, who had a regurgitation graded as mild to moderate. By magnetic resonance imaging (n = 4), mean root dimensions were stable at the annulus (24 mm), sinus of Valsalva (33 mm), and sinotubular junction (28 mm). By computed tomography (n = 22), there was only discrete conduit calcification (median calcium score 63 Hounsfield units [HU]; range, 0 to 894 HU) to 3 years of follow-up. Conduit biopsy in the patient who underwent reoperation demonstrated well-preserved wall structure, absence of calcification, and limited in vivo host repopulation. The early and midterm results with DAVA demonstrated stable structural integrity, low rate of calcification, and adequate hemodynamics. Although longer periods of observation are necessary, DAVA appears to be a promising alternative for aortic valve replacement in selected patients. Copyright © 2010 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

  1. Globe stability during simulated vitrectomy with valved and non-valved trocar cannulas

    PubMed Central

    Abulon, Dina Joy; Charles, Martin; Charles, Daniel E

    2015-01-01

    Purpose To compare the effects of valved and non-valved cannulas on intraocular pressure (IOP), fluid leakage, and vitreous incarceration during simulated vitrectomy. Methods Three-port pars plana incisions were generated in six rubber eyes using 23-, 25-, and 27-gauge valved and non-valved trocar cannulas. The models were filled with air and IOP was measured. Similar procedures were followed for 36 acrylic eyes filled with saline solution. Vitreous incarceration was analyzed in eleven rabbit and twelve porcine cadaver eyes. Results In the air-filled model, IOP loss was 89%–94% when two non-valved cannulas were unoccupied versus 1%–5% when two valved cannulas were unoccupied. In the fluid-filled model, with non-valved cannulas, IOP dropped while fluid leaked from the open ports. With two open ports, the IOP dropped to 20%–30% of set infusion pressure, regardless of infusion pressure and IOP compensation. The IOP was maintained in valved cannulas when one or two ports were left open, regardless of IOP compensation settings. There was no or minimal fluid leakage through open ports at any infusion pressure. Direct microscopic analysis of rabbit eyes showed that vitreous incarceration was significantly greater with 23-gauge non-valved than valved cannulas (P<0.005), and endoscopy of porcine eyes showed that vitreous incarceration was significantly greater with 23-gauge (P<0.05) and 27-gauge (P<0.05) non-valved cannulas. External observation of rabbit eyes showed vitreous prolapse through non-valved, but not valved, cannulas. Conclusion Valved cannulas surpassed non-valved cannulas in maintaining IOP, preventing fluid leakage, and reducing vitreous incarceration during simulated vitrectomy. PMID:26445520

  2. Explosive-actuated valve design concept that eliminates blow-by. [for the TOPS spacecraft trajectory correction propulsion subsystem

    NASA Technical Reports Server (NTRS)

    Hagler, R., Jr.

    1974-01-01

    A method of evaluating the normally open normally closed, explosive actuated valves that were selected for use in the trajectory correction propulsion subsystem of the Thermoelectric Outer Planet Spacecraft (TOPS) program is presented. The design philosophy which determined the requirements for highly reliable valves that could provide the performance capability during long duration (10 year) missions to the outer planets is discussed. The techniques that were used to fabricate the valves and manifold ten valves into an assembly with the capability of five propellant-flow initiation/isolation sequences are described. The test program, which was conducted to verify valve design requirements, is outlined and the more significant results are shown.

  3. Microfluidic sieve valves

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Quake, Stephen R; Marcus, Joshua S; Hansen, Carl L

    2015-01-13

    Sieve valves for use in microfluidic device are provided. The valves are useful for impeding the flow of particles, such as chromatography beads or cells, in a microfluidic channel while allowing liquid solution to pass through the valve. The valves find particular use in making microfluidic chromatography modules.

  4. Successful management of multiple permanent pacemaker complications – infection, 13 year old silent lead perforation and exteriorisation following failed percutaneous extraction, superior vena cava obstruction, tricuspid valve endocarditis, pulmonary embolism and prosthetic tricuspid valve thrombosis

    PubMed Central

    Kaul, Pankaj; Adluri, Krishna; Javangula, Kalyana; Baig, Wasir

    2009-01-01

    A 59 year old man underwent mechanical tricuspid valve replacement and removal of pacemaker generator along with 4 pacemaker leads for pacemaker endocarditis and superior vena cava obstruction after an earlier percutaneous extraction had to be abandoned, 13 years ago, due to cardiac arrest, accompanied by silent, unsuspected right atrial perforation and exteriorisation of lead. Postoperative course was complicated by tricuspid valve thrombosis and secondary pulmonary embolism requiring TPA thrombolysis which was instantly successful. A review of literature of pacemaker endocarditis and tricuspid thrombosis along with the relevant management strategies is presented. We believe this case report is unusual on account of non operative management of right atrial lead perforation following an unsuccessful attempt at percutaneous removal of right sided infected pacemaker leads and the incidental discovery of the perforated lead 13 years later at sternotomy, presentation of pacemaker endocarditis with a massive load of vegetations along the entire pacemaker lead tract in superior vena cava, right atrial endocardium, tricuspid valve and right ventricular endocardium, leading to a functional and structural SVC obstruction, requirement of an unusually large dose of warfarin postoperatively occasioned, in all probability, by antibiotic drug interactions, presentation of tricuspid prosthetic valve thrombosis uniquely as vasovagal syncope and isolated hypoxia and near instantaneous resolution of tricuspid prosthetic valve thrombosis with Alteplase thrombolysis. PMID:19239701

  5. 40 CFR 65.114 - Standards: Open-ended valves or lines.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... closed. (3) When a double block and bleed system is being used, the bleed valve or line may remain open... block and bleed system as specified in paragraph (b) of this section are exempt from the requirements of...

  6. Sequential transcatheter aortic valve implantation due to valve dislodgement - a Portico valve implanted over a CoreValve bioprosthesis.

    PubMed

    Campante Teles, Rui; Costa, Cátia; Almeida, Manuel; Brito, João; Sondergaard, Lars; Neves, José P; Abecasis, João; M Gabriel, Henrique

    2017-03-01

    Transcatheter aortic valve implantation (TAVI) has become an important treatment in high surgical risk patients with severe aortic stenosis (AS), whose complications need to be managed promptly. The authors report the case of an 86-year-old woman presenting with severe symptomatic AS, rejected for surgery due to advanced age and comorbidities. The patient underwent a first TAVI, with implantation of a Medtronic CoreValve ® , which became dislodged and migrated to the ascending aorta. Due to the previous balloon valvuloplasty, the patient's AS became moderate, and her symptoms improved. After several months, she required another intervention, performed with a St. Jude Portico ® repositionable self-expanding transcatheter aortic valve. There was a good clinical response that was maintained at one-year follow-up. The use of a self-expanding transcatheter bioprosthesis with repositioning features is a solution in cases of valve dislocation to avoid suboptimal positioning of a second implant, especially when the two valves have to be positioned overlapping or partially overlapping each other. Copyright © 2017 Sociedade Portuguesa de Cardiologia. Publicado por Elsevier España, S.L.U. All rights reserved.

  7. Problem: Heart Valve Stenosis

    MedlinePlus

    ... valve . Learn about the different types of stenosis: Aortic stenosis Tricuspid stenosis Pulmonary stenosis Mitral stenosis Outlook for ... Disease "Innocent" Heart Murmur Problem: Valve Stenosis - Problem: Aortic Valve Stenosis - Problem: Mitral Valve Stenosis - Problem: Tricuspid Valve Stenosis - ...

  8. Vacuum breaker valve assembly

    DOEpatents

    Thompson, J.L.; Upton, H.A.

    1999-04-27

    Breaker valve assemblies for a simplified boiling water nuclear reactor are described. The breaker valve assembly, in one form, includes a valve body and a breaker valve. The valve body includes an interior chamber, and an inlet passage extends from the chamber and through an inlet opening to facilitate transporting particles from outside of the valve body to the interior chamber. The breaker valve is positioned in the chamber and is configured to substantially seal the inlet opening. Particularly, the breaker valve includes a disk which is sized to cover the inlet opening. The disk is movably coupled to the valve body and is configured to move substantially concentrically with respect to the valve opening between a first position, where the disk completely covers the inlet opening, and a second position, where the disk does not completely cover the inlet opening. 1 fig.

  9. Vacuum breaker valve assembly

    DOEpatents

    Thompson, Jeffrey L.; Upton, Hubert Allen

    1999-04-27

    Breaker valve assemblies for a simplified boiling water nuclear reactor are described. The breaker valve assembly, in one form, includes a valve body and a breaker valve. The valve body includes an interior chamber, and an inlet passage extends from the chamber and through an inlet opening to facilitate transporting particles from outside of the valve body to the interior chamber. The breaker valve is positioned in the chamber and is configured to substantially seal the inlet opening. Particularly, the breaker valve includes a disk which is sized to cover the inlet opening. The disk is movably coupled to the valve body and is configured to move substantially concentrically with respect to the valve opening between a first position, where the disk completely covers the inlet opening, and a second position, where the disk does not completely cover the inlet opening.

  10. Closed bore XMR (CBXMR) systems for aortic valve replacement: Investigation of rotating-anode x-ray tube heat loadability

    PubMed Central

    Bracken, John A.; Lillaney, Prasheel V.; Fahrig, Rebecca; Rowlands, J. A.

    2008-01-01

    In order to improve the safety and efficacy of percutaneous aortic valve replacement procedures, a closed bore hybrid x-ray∕MRI (CBXMR) system is proposed in which an x-ray C-arm will be positioned with its isocenter ≈1 m from the entrance of a clinical MRI scanner. This system will harness the complementary strengths of both modalities to improve clinical outcome. A key component of the CBXMR system will be a rotating anode x-ray tube to produce high-quality x-ray images. There are challenges in positioning an x-ray tube in the magnetic fringe field of the MRI magnet. Here, the effects of an external magnetic field on x-ray tube induction motors of radiography x-ray tubes and the corresponding reduction of x-ray tube heat loadability are investigated. Anode rotation frequency fanode was unaffected when the external magnetic field Bb was parallel to the axis of rotation of the anode but decreased when Bb was perpendicular to the axis of rotation. The experimental fanode values agreed with predicted values to within ±3% over a Bb range of 0–30 mT. The MRI fringe field at the proposed location of the x-ray tube mounted on the C-arm (≈4 mT) reduced fanode by only 1%, so x-ray tube heat loadability will not be compromised when using CBXMR systems for percutaneous aortic valve replacement procedures. Eddy current heating power in the rotor due to an MRI fringe field was found to be two orders of magnitude weaker than the heating power produced on the anode due to a fluoroscopic exposure, so eddy current heating had no effect on x-ray tube heat loadability. PMID:18841857

  11. Zero-leak valve

    NASA Technical Reports Server (NTRS)

    Macglashan, W. F., Jr.

    1980-01-01

    Zero-leakage valve has fluid-sealing diaphragm support and flat sievelike sealing surface. Diaphragm-support valve is easy to fabricate and requires minimum maintenance. Potential applications include isolation valve for waste systems and remote air-actuated valve. Device is also useful in controlling flow of liquid fluorine and corrosive fluids at high pressures.

  12. Rotary pneumatic valve

    DOEpatents

    Hardee, Harry C.

    1991-01-01

    A rotary pneumatic valve which is thrust balanced and the pneumatic pressure developed produces only radial loads on the valve cylinder producing negligible resistance and thus minimal torque on the bearings of the valve. The valve is multiplexed such that at least two complete switching cycles occur for each revolution of the cylinder spindle.

  13. Development and experimental characterization of a pneumatic valve actuated by a dielectric elastomer membrane

    NASA Astrophysics Data System (ADS)

    Hill, Marc; Rizzello, Gianluca; Seelecke, Stefan

    2017-08-01

    Due to their many features including lightweight and low energy consumption, dielectric elastomer (DE) membrane actuators are of interest for a number of industrial applications, such as pumping systems or valve control units. In particular, the use of DEs in valve control units offers advantages over traditional solenoid valves, including lower power requirements and relative simplicity in achieving proportional control. Additionally, DEs generate low thermal dissipation and are capable of virtually silent operation. The contribution of this work is the development of a new valve system based on a circular DE membrane pre-loaded with a linear spring. The valve is designed for pressurized air and operates by actuating a lever mechanism that opens and closes an outlet port. After presenting the operating principle and system design, several experiments are presented to compare actuator force, stroke, and dissipated energy for several pressure differentials and associated volume flows. It is observed that the DE-driven valve achieves a performance similar to a solenoid-based valve, while requiring a significantly lower amount of input energy. In addition, it is shown that DE-membrane valves can be controlled proportionally by simply adjusting the actuator voltage.

  14. Scissor thrust valve actuator

    DOEpatents

    DeWall, Kevin G.; Watkins, John C; Nitzel, Michael E.

    2006-08-29

    Apparatus for actuating a valve includes a support frame and at least one valve driving linkage arm, one end of which is rotatably connected to a valve stem of the valve and the other end of which is rotatably connected to a screw block. A motor connected to the frame is operatively connected to a motor driven shaft which is in threaded screw driving relationship with the screw block. The motor rotates the motor driven shaft which drives translational movement of the screw block which drives rotatable movement of the valve driving linkage arm which drives translational movement of the valve stem. The valve actuator may further include a sensory control element disposed in operative relationship with the valve stem, the sensory control element being adapted to provide control over the position of the valve stem by at least sensing the travel and/or position of the valve stem.

  15. Recellularization of decellularized heart valves: Progress toward the tissue-engineered heart valve

    PubMed Central

    VeDepo, Mitchell C; Detamore, Michael S; Hopkins, Richard A; Converse, Gabriel L

    2017-01-01

    The tissue-engineered heart valve portends a new era in the field of valve replacement. Decellularized heart valves are of great interest as a scaffold for the tissue-engineered heart valve due to their naturally bioactive composition, clinical relevance as a stand-alone implant, and partial recellularization in vivo. However, a significant challenge remains in realizing the tissue-engineered heart valve: assuring consistent recellularization of the entire valve leaflets by phenotypically appropriate cells. Many creative strategies have pursued complete biological valve recellularization; however, identifying the optimal recellularization method, including in situ or in vitro recellularization and chemical and/or mechanical conditioning, has proven difficult. Furthermore, while many studies have focused on individual parameters for increasing valve interstitial recellularization, a general understanding of the interacting dynamics is likely necessary to achieve success. Therefore, the purpose of this review is to explore and compare the various processing strategies used for the decellularization and subsequent recellularization of tissue-engineered heart valves. PMID:28890780

  16. Structural valve deterioration in a starr-edwards mitral caged-disk valve prosthesis.

    PubMed

    Aoyagi, Shigeaki; Tayama, Kei-Ichiro; Okazaki, Teiji; Shintani, Yusuke; Kono, Michitaka; Wada, Kumiko; Kosuga, Ken-Ichi; Mori, Ryusuke; Tanaka, Hiroyuki

    2013-01-01

    The durability of the Starr-Edwards (SE) mitral caged-disk valve, model 6520, is not clearly known, and structural valve deterioration in the SE disk valve is very rare. Replacement of the SE mitral disk valve was performed in 7 patients 23-40 years after implantation. Macroscopic examination of the removed disk valves showed no structural abnormalities in 3 patients, in whom the disk valves were removed at <26 years after implantation. Localized disk wear was found at the sites where the disk abutted the struts of the cage, in disk valves excised >36 years after implantation in 4 patients. Disk fracture, a longitudinal split in the disk along its circumference at the site of incorporation of the titanium ring, was detected in the valves removed 36 and 40 years after implantation, respectively, and many cracks were also observed on the outflow aspect of the disk removed 40 years after implantation. Disk fracture and localized disk wear were found in the SE mitral disk valves implanted >36 years previously. The present results suggest that SE mitral caged-disk valves implanted >20 years previously should be carefully followed up, and that those implanted >30 years previously should be electively replaced with modern prosthetic valves

  17. A review of state-of-the-art numerical methods for simulating flow through mechanical heart valves.

    PubMed

    Sotiropoulos, Fotis; Borazjani, Iman

    2009-03-01

    In nearly half of the heart valve replacement surgeries performed annually, surgeons prefer to implant bileaflet mechanical heart valves (BMHV) because of their durability and long life span. All current BMHV designs, however, are prone to thromboembolic complications and implant recipients need to be on a life-long anticoagulant medication regiment. Non-physiologic flow patterns and turbulence generated by the valve leaflets are believed to be the major culprit for the increased risk of thromboembolism in BMHV implant recipients. In this paper, we review recent advances in developing predictive fluid-structure interaction (FSI) algorithms that can simulate BMHV flows at physiologic conditions and at resolution sufficiently fine to start probing the links between hemodynamics and blood-cell damage. Numerical simulations have provided the first glimpse into the complex hemodynamic environment experienced by blood cells downstream of the valve leaflets and successfully resolved for the first time the experimentally observed explosive transition to a turbulent-like state at the start of the decelerating flow phase. The simulations have also resolved a number of subtle features of experimentally observed valve kinematics, such as the asymmetric opening and closing of the leaflets and the leaflet rebound during closing. The paper also discusses a future research agenda toward developing a powerful patient-specific computational framework for optimizing valve design and implantation in a virtual surgery environment.

  18. A review of state-of-the-art numerical methods for simulating flow through mechanical heart valves

    PubMed Central

    Borazjani, Iman

    2009-01-01

    In nearly half of the heart valve replacement surgeries performed annually, surgeons prefer to implant bileaflet mechanical heart valves (BMHV) because of their durability and long life span. All current BMHV designs, however, are prone to thromboembolic complications and implant recipients need to be on a life-long anticoagulant medication regiment. Non-physiologic flow patterns and turbulence generated by the valve leaflets are believed to be the major culprit for the increased risk of thromboembolism in BMHV implant recipients. In this paper, we review recent advances in developing predictive fluid–structure interaction (FSI) algorithms that can simulate BMHV flows at physiologic conditions and at resolution sufficiently fine to start probing the links between hemodynamics and blood-cell damage. Numerical simulations have provided the first glimpse into the complex hemodynamic environment experienced by blood cells downstream of the valve leaflets and successfully resolved for the first time the experimentally observed explosive transition to a turbulent-like state at the start of the decelerating flow phase. The simulations have also resolved a number of subtle features of experimentally observed valve kinematics, such as the asymmetric opening and closing of the leaflets and the leaflet rebound during closing. The paper also discusses a future research agenda toward developing a powerful patient-specific computational framework for optimizing valve design and implantation in a virtual surgery environment. PMID:19194734

  19. Light valve based on nonimaging optics with potential application in cold climate greenhouses

    NASA Astrophysics Data System (ADS)

    Valerio, Angel A.; Mossman, Michele A.; Whitehead, Lorne A.

    2014-09-01

    We have evaluated a new concept for a variable light valve and thermal insulation system based on nonimaging optics. The system incorporates compound parabolic concentrators and can readily be switched between an open highly light transmissive state and a closed highly thermally insulating state. This variable light valve makes the transition between high thermal insulation and efficient light transmittance practical and may be useful in plant growth environments to provide both adequate sunlight illumination and thermal insulation as needed. We have measured light transmittance values exceeding 80% for the light valve design and achieved thermal insulation values substantially exceeding those of traditional energy efficient windows. The light valve system presented in this paper represents a potential solution for greenhouse food production in locations where greenhouses are not feasible economically due to high heating cost.

  20. Tricuspid regurgitation after successful mitral valve surgery

    PubMed Central

    Katsi, Vasiliki; Raftopoulos, Leonidas; Aggeli, Constantina; Vlasseros, Ioannis; Felekos, Ioannis; Tousoulis, Dimitrios; Stefanadis, Christodoulos; Kallikazaros, Ioannis

    2012-01-01

    The tricuspid valve (TV) is inseparably connected with the mitral valve (MV) in terms of function. Any pathophysiological condition concerning the MV is potentially a threat for the normal function of the TV as well. One of the most challenging cases is functional tricuspid regurgitation (TR) after surgical MV correction. In the past, TR was considered to progressively revert with time after left-sided valve restoration. Nevertheless, more recent studies showed that TR could develop and evolve postoperatively over time, as well as being closely associated with a poorer prognosis in terms of morbidity and mortality. Pressure and volume overload are usually the underlying pathophysiological mechanisms; structural alterations, like tricuspid annulus dilatation, increased leaflet tethering and right ventricular remodelling are almost always present when regurgitation develops. The most important risk factors associated with a higher probability of late TR development involve the elderly, female gender, larger left atrial size, atrial fibrillation, right chamber dilatation, higher pulmonary artery systolic pressures, longer times from the onset of MV disease to surgery, history of rheumatic heart disease, ischaemic heart disease and prosthetic valve malfunction. The time of TR manifestation can be up to 10 years or more after an MV surgery. Echocardiography, including the novel 3D Echo techniques, is crucial in the early diagnosis and prognosis of future TV disease development. Appropriate surgical technique and timing still need to be clarified. PMID:22457188

  1. Aortic valve repair leads to a low incidence of valve-related complications.

    PubMed

    Aicher, Diana; Fries, Roland; Rodionycheva, Svetlana; Schmidt, Kathrin; Langer, Frank; Schäfers, Hans-Joachim

    2010-01-01

    Aortic valve replacement for aortic regurgitation (AR) has been established as a standard treatment but implies prosthesis-related complications. Aortic valve repair is an alternative approach, but its mid- to long-term results still need to be defined. Over a 12-year period, 640 patients underwent aortic valve repair for regurgitation of a unicuspid (n=21), bicuspid (n=205), tricuspid (n=411) or quadricuspid (n=3) aortic valve. The mechanism of regurgitation involved prolapse (n=469) or retraction (n=20) of the cusps, and dilatation of the root (n=323) or combined pathologies. Treatment consisted of cusp repair (n=529), root repair (n=323) or a combination of both (n=208). The patients were followed clinically and echocardiographically; follow-up was complete in 98.5% (cumulative follow-up: 3035 patient years). Hospital mortality was 3.4% in the total patient cohort and 0.8% for isolated aortic valve repair. The incidences of thrombo-embolism (0.2% per patient per year) and endocarditis (0.16%per patient per year) were low. Freedom from re-operation at 5 and 10 years was 88% and 81% in bicuspid and 97% and 93% in tricuspid aortic valves (p=0.0013). At re-operation, 13 out of 36 valves could be re-repaired. Freedom from valve replacement was 95% and 90% in bicuspid and 97% and 94% in tricuspid aortic valves (p=0.36). Freedom from all valve-related complications at 10 years was 88%. Reconstructive surgery of the aortic valve is feasible with low mortality in many individuals with aortic regurgitation. Freedom from valve-related complications after valve repair seems superior compared to available data on standard aortic valve replacement. Copyright 2009 European Association for Cardio-Thoracic Surgery. Published by Elsevier B.V. All rights reserved.

  2. On the effects of leaflet microstructure and constitutive model on the closing behavior of the mitral valve

    PubMed Central

    Lee, Chung-Hao; Rabbah, Jean-Pierre; Yoganathan, Ajit P.; Gorman, Robert C.; Gorman, Joseph H.

    2016-01-01

    Recent long-term studies showed an unsatisfactory recurrence rate of severe mitral regurgitation 3–5 years after surgical repair, suggesting that excessive tissue stresses and the resulting strain-induced tissue failure are potential etiological factors controlling the success of surgical repair for treating mitral valve (MV) diseases. We hypothesized that restoring normal MV tissue stresses in MV repair techniques would ultimately lead to improved repair durability through the restoration of MV normal homeostatic state. Therefore, we developed a micro- and macro- anatomically accurate MV finite element model by incorporating actual fiber microstructural architecture and a realistic structure-based constitutive model. We investigated MV closing behaviors, with extensive in vitro data used for validating the proposed model. Comparative and parametric studies were conducted to identify essential model fidelity and information for achieving desirable accuracy. More importantly, for the first time, the interrelationship between the local fiber ensemble behavior and the organ-level MV closing behavior was investigated using a computational simulation. These novel results indicated not only the appropriate parameter ranges, but also the importance of the microstructural tuning (i.e., straightening and re-orientation) of the collagen/elastin fiber networks at the macroscopic tissue level for facilitating the proper coaptation and natural functioning of the MV apparatus under physiological loading at the organ level. The proposed computational model would serve as a logical first step toward our long-term modeling goal—facilitating simulation-guided design of optimal surgical repair strategies for treating diseased MVs with significantly enhanced durability. PMID:25947879

  3. Computerized system for the follow-up of patients with heart valve replacements.

    PubMed

    Bain, W H; Fyfe, I C; Rodger, R A

    1985-04-01

    A system is described which will accept, store, retrieve and analyze information on large numbers of patients who undergo valve replacement surgery. The purpose of the database is to yield readily available facts concerning the patient's clinical course, prosthetic valve function, length of survival, and incidence of complications. The system uses the Apple Macintosh computer, which is one of the current examples of small, desk-top microprocessors. The software for the input, editing and analysis programs has been written by a professional software writer in close collaboration with a cardiac surgeon. Its content is based on 8 years' experience of computer-based valve follow-up. The system is inexpensive and has proved easy to use in practice.

  4. Wirelessly powered and remotely controlled valve-array for highly multiplexed analytical assay automation on a centrifugal microfluidic platform.

    PubMed

    Torres Delgado, Saraí M; Kinahan, David J; Nirupa Julius, Lourdes Albina; Mallette, Adam; Ardila, David Sáenz; Mishra, Rohit; Miyazaki, Celina M; Korvink, Jan G; Ducrée, Jens; Mager, Dario

    2018-06-30

    In this paper we present a wirelessly powered array of 128 centrifugo-pneumatic valves that can be thermally actuated on demand during spinning. The valves can either be triggered by a predefined protocol, wireless signal transmission via Bluetooth, or in response to a sensor monitoring a parameter like the temperature, or homogeneity of the dispersion. Upon activation of a resistive heater, a low-melting membrane (Parafilm™) is removed to vent an entrapped gas pocket, thus letting the incoming liquid wet an intermediate dissolvable film and thereby open the valve. The proposed system allows up to 12 heaters to be activated in parallel, with a response time below 3 s, potentially resulting in 128 actuated valves in under 30 s. We demonstrate, with three examples of common and standard procedures, how the proposed technology could become a powerful tool for implementing diagnostic assays on Lab-on-a-Disc. First, we implement wireless actuation of 64 valves during rotation in a freely programmable sequence, or upon user input in real time. Then, we show a closed-loop centrifugal flow control sequence for which the state of mixing of reagents, evaluated from stroboscopically recorded images, triggers the opening of the valves. In our last experiment, valving and closed-loop control are used to facilitate centrifugal processing of whole blood. Copyright © 2018 Elsevier B.V. All rights reserved.

  5. Development of an artificial urethral valve using SMA actuators

    NASA Astrophysics Data System (ADS)

    Chonan, S.; Jiang, Z. W.; Tani, J.; Orikasa, S.; Tanahashi, Y.; Takagi, T.; Tanaka, M.; Tanikawa, J.

    1997-08-01

    The development of an artificial urethral valve for the treatment of urinary incontinence which occurs frequently in the aged is described. The prototype urethral valve is assembled in hand-drum form with four thin shape memory alloy (SMA) (nickel - titanium alloy) plates of 0.3 mm thickness. The shape memory effect in two directions is used to replace the urinary canal sphincter muscles and to control the canal opening and closing functions. The characteristic of the SMA is to assume the shape of a circular arc at normal temperatures and a flat shape at higher temperatures. Experiments have been conducted using a canine bladder and urinary canal.

  6. Valve assembly for use with high temperature and high pressure fluids

    DOEpatents

    De Feo, Angelo

    1982-01-01

    The valve assembly for use with high temperature and high pressure fluids has inner and outer spaced shells and a valve actuator support of inner and outer spaced members which are connected at their end portions to the inner and outer shells, respectively, to extend substantially normal to the longitudinal axis of the inner shell. A layer of resilient heat insulating material covers the outer surfaces of the inner shell and the inner actuator support member and is of a thickness to only occupy part of the spaces between the inner and outer shells and inner and outer actuator support members. The remaining portion of the space between the inner and outer shells and the space between the inner and outer members is substantially filled with a body of castable, rigid refractory material. A movable valve member is disposed in the inner shell. A valve actuator assembly is supported in the valve actuator support to extend into the inner shell for connection with the movable valve member for movement of the movable valve member to positions from a fully open to a fully closed position to control flow of fluid through the inner shell. An anchor mneans is disposed adjacent opposite sides of the axis of the valve actuator support and attached to the inner shell so that relative radial movement between the inner and outer shell is permitted by the layer of resilient heat insulating material and relative longitudinal movement of the inner shell to the outer shell is permitted in opposite directions from the anchor means to thereby maintain the functional integrity of the movable valve member by providing an area of the inner shell surrounding the movable valve member longitdinally stationary, but at the same time allowing radial movement.

  7. Percutaneous Closure of 2 Paravalvular Leaks and a Gerbode Defect after Mitral Valve Replacement for Infective Endocarditis.

    PubMed

    Peñalver, Jorge; Shatila, Wassim; Silva, Guilherme V

    2017-04-01

    Surgical valve replacement after infective endocarditis can result in local destructive paravalvular lesions. A 30-year-old woman with infective endocarditis underwent mitral valve replacement that was complicated postoperatively by 2 paravalvular leaks. During percutaneous closure of the leaks, a Gerbode defect was also found and closed. We discuss our patient's case and its relation to others in the relevant medical literature. To our knowledge, we are the first to describe the use of a percutaneous approach to close concomitant paravalvular leaks and a Gerbode defect.

  8. Passively operated spool valve for drain-down freeze protection of thermosyphon water heaters. Final technical report

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    None

    1982-04-30

    The work done to extend the existing drain-down valve technology to provide passive drain-down freeze protection for thermosyphon-based solar water heaters is described. The basic design of the existing valve model is that of a spool valve, employing a cylindrical spool which moves axially in a mating cartridge to open and close o-rings at the two operating extremes (drain and operate) to perform the valving function. Three passive actuators to drive the basic valving mechanism were designed, fabricated, and tested. Two piping configurations used to integrate the spool valve with the thermosyphon system are described, as are the passive actuators.more » The three actuator designs are: photovoltaic driven, refrigerant-based bellows, and heat motor cable-drive designs. Costs are compared for the alternative actuator designs, and operating characteristics were examined for the thermosyphon system, including field tests. The market for the valve for thermosyphon systems is then assessed. (LEW)« less

  9. Force measuring valve assemblies, systems including such valve assemblies and related methods

    DOEpatents

    DeWall, Kevin George [Pocatello, ID; Garcia, Humberto Enrique [Idaho Falls, ID; McKellar, Michael George [Idaho Falls, ID

    2012-04-17

    Methods of evaluating a fluid condition may include stroking a valve member and measuring a force acting on the valve member during the stroke. Methods of evaluating a fluid condition may include measuring a force acting on a valve member in the presence of fluid flow over a period of time and evaluating at least one of the frequency of changes in the measured force over the period of time and the magnitude of the changes in the measured force over the period of time to identify the presence of an anomaly in a fluid flow and, optionally, its estimated location. Methods of evaluating a valve condition may include directing a fluid flow through a valve while stroking a valve member, measuring a force acting on the valve member during the stroke, and comparing the measured force to a reference force. Valve assemblies and related systems are also disclosed.

  10. The effect of lymphatic valve morphology on fluid transport

    NASA Astrophysics Data System (ADS)

    Alexeev, Alexander; Ballard, Matthew; Nepiyushchikh, Zhanna; Dixon, Brandon

    2016-11-01

    The lymphatic vasculature is present in nearly all invertebrate tissue, and is essential in the transport of fluid and particles such as immune cells, antigens, proteins and lipids from the tissue to lymph nodes and to the venous circulation. Lymphatic vessels are made of up a series of contractile units that work together in harmony as "micro hearts" to pump fluid against a pressure gradient. Lymphatic valves are critical to this functionality, as they open and close with the oscillating pressure gradients from contractions, thus allowing flow in only one direction and leading to a net pumping effect. We use a hybrid lattice-Boltzmann lattice spring model which captures fluid-solid interactions through two-way coupling between a viscous fluid and lymphatic valves in a section of a lymphatic vessel to study the dynamics of lymphatic valves and their effect on fluid transport. Further, we investigate the effect of variations in valve geometry and material properties on fluid pumping. This work helps to increase our understanding of the mechanisms of lymphatic fluid transport, which has implications in a variety of pathologies, including cancer metastasis, autoimmunity, atherosclerosis and obesity. Support from NSF CMMI 1635133 is gratefully acknowledged.

  11. Magnetically operated check valve

    NASA Technical Reports Server (NTRS)

    Morris, Brian G. (Inventor); Bozeman, Richard J., Jr. (Inventor)

    1994-01-01

    A magnetically operated check valve is disclosed. The valve is comprised of a valve body and a movable poppet disposed therein. A magnet attracts the poppet to hold the valve shut until the force of fluid flow through the valve overcomes the magnetic attraction and moves the poppet to an unseated, open position. The poppet and magnet are configured and disposed to trap a magnetically attracted particulate and prevent it from flowing to a valve seating region.

  12. Magnetically operated check valve

    NASA Astrophysics Data System (ADS)

    Morris, Brian G.; Bozeman, Richard J., Jr.

    1994-06-01

    A magnetically operated check valve is disclosed. The valve is comprised of a valve body and a movable poppet disposed therein. A magnet attracts the poppet to hold the valve shut until the force of fluid flow through the valve overcomes the magnetic attraction and moves the poppet to an unseated, open position. The poppet and magnet are configured and disposed to trap a magnetically attracted particulate and prevent it from flowing to a valve seating region.

  13. Aortic valve insufficiency in the teenager and young adult: the role of prosthetic valve replacement.

    PubMed

    Bradley, Scott M

    2013-10-01

    The contents of this article were presented in the session "Aortic insufficiency in the teenager" at the congenital parallel symposium of the 2013 Society of Thoracic Surgeons (STS) annual meeting. The accompanying articles detail the approaches of aortic valve repair and the Ross procedure.(1,2) The current article focuses on prosthetic valve replacement. For many young patients requiring aortic valve surgery, either aortic valve repair or a Ross procedure provides a good option. The advantages include avoidance of anticoagulation and potential for growth. In other patients, a prosthetic valve is an appropriate alternative. This article discusses the current state of knowledge regarding mechanical and bioprosthetic valve prostheses and their specific advantages relative to valve repair or a Ross procedure. In current practice, young patients requiring aortic valve surgery frequently undergo valve replacement with a prosthetic valve. In STS adult cardiac database, among patients ≤30 years of age undergoing aortic valve surgery, 34% had placement of a mechanical valve, 51% had placement of a bioprosthetic valve, 9% had aortic valve repair, and 2% had a Ross procedure. In the STS congenital database, among patients 12 to 30 years of age undergoing aortic valve surgery, 21% had placement of a mechanical valve, 18% had placement of a bioprosthetic valve, 30% had aortic valve repair, and 24% had a Ross procedure. In the future, the balance among these options may be altered by design improvements in prosthetic valves, alternatives to warfarin, the development of new patch materials for valve repair, and techniques to avoid Ross autograft failure.

  14. Automatic shutoff valve

    NASA Technical Reports Server (NTRS)

    Hawkins, S. F.; Overbey, C. W.

    1980-01-01

    Cellulose-sponge disk absorbs incoming water and expands with enough force to shut valve. When water recedes, valve opens by squeezing sponge dry to its original size. This direct mechanical action is considered more reliable than solenoid valve.

  15. Sibling cycle piston and valving method

    NASA Technical Reports Server (NTRS)

    Mitchell, Matthew P. (Inventor); Bauwens, Luc (Inventor)

    1990-01-01

    A double-acting, rotating piston reciprocating in a cylinder with the motion of the piston providing the valving action of the Sibling Cycle through the medium of passages between the piston and cylinder wall. The rotating piston contains regenerators ported to the walls of the piston. The piston fits closely in the cylinder at each end of the cylinder except in areas where the wall of the cylinder is relieved to provide passages between the cylinder wall and the piston leading to the expansion and compression spaces, respectively. The piston reciprocates as it rotates. The cylinder and piston together comprise an integral valve that seqentially opens and closes the ports at the ends of the regenerators alternately allowing them to communicate with the expansion space and compression space and blocking that communication. The relieved passages in the cylinder and the ports in the piston are so arranged that each regenerator is sequentially (1) charged with compressed working gas from the compression space; (2) isolated from both expansion and compression spaces; (3) discharged of working gas into the expansion space; and (4) simultaneously charged with working gas from the expansion space while being discharged of working gas into the compression space, in the manner of the Sibling Cycle. In an alterate embodiment, heat exchangers are external to the cylinder and ports in the cylinder wall are alternately closed by the wall of the piston and opened to the expansion and compression spaces through relieved passages in the wall of the reciprocating, rotating piston.

  16. Pump having pistons and valves made of electroactive actuators

    NASA Technical Reports Server (NTRS)

    Bar-Cohen, Yoseph (Inventor)

    1997-01-01

    The present invention provides a pump for inducing a displacement of a fluid from a first medium to a second medium, including a conduit coupled to the first and second media, a transducing material piston defining a pump chamber in the conduit and being transversely displaceable for increasing a volume of the chamber to extract the fluid from the first medium to the chamber and for decreasing the chamber volume to force the fluid from the chamber to the second medium, a first transducing material valve mounted in the conduit between the piston and the first medium and being transversely displaceable from a closed position to an open position to admit the fluid to the chamber, and control means for changing a first field applied to the piston to displace the piston for changing the chamber volume and for changing a second field applied to the first valve to change the position of the first valve.

  17. Transcatheter heart valves for the treatment of aortic stenosis: state-of-the-art.

    PubMed

    Del Valle-Fernández, R; Ruiz, C E

    2008-10-01

    Degenerative aortic stenosis is the most frequent heart valve disease. As an alternative to surgical aortic valve replacement, several companies are working on the development of new prosthesis designed to be deployed by transcatheter approaches. Both transfemoral and transapical techniques are feasible, and initial trials in high-risk patients show good procedural outcomes and mid-term (up to 2 years) functionality. Two first-generation prosthesis (Edwards-SAPIEN and CoreValve Revalving System) are commercially available in Europe, and a number of other second-generation valves (with the capabilities of repositioning and retrievability) are under evaluation. Among them, the Sadra-Lotus Valve, The Direct Flow Medical valve and the Paniagua Heart Valve have published first-in-man results; the JenaValve and AorTx devices have also been temporarily implanted in humans. The development of repositionable and retrievable prosthesis with improved profile is mandatory, and it is the main focus of current projects. Not only technical improvements but also operators specialization and an optimal patient selection are essential to improve these initial Some procedural challenges need to be overcome prior to the expansion of these techniques to lower risk groups, and time is needed for detailed long-term outcomes and risk estimations. Only with a close collaboration among different specialists, basic researchers and the industry will the future development of transcatheter aortic implantation techniques be ensured.

  18. Overflow control valve

    DOEpatents

    Hundal, Rolv; Kessinger, Boyd A.; Parlak, Edward A.

    1984-07-24

    An overflow control valve for use in a liquid sodium coolant pump tank which valve can be extended to create a seal with the pump tank wall or retracted to break the seal thereby accommodating valve removal. An actuating shaft which controls valve disc position also has cams which bear on roller surfaces to force retraction of a sliding cylinder against spring tension to retract the cylinder from sealing contact with the pump tank.

  19. Pump, and earth-testable spacecraft capillary heat transport loop using augmentation pump and check valves

    NASA Technical Reports Server (NTRS)

    Baker, David (Inventor)

    1998-01-01

    A spacecraft includes heat-generating payload equipment, and a heat transport system with a cold plate thermally coupled to the equipment and a capillary-wick evaporator, for evaporating coolant liquid to cool the equipment. The coolant vapor is coupled to a condenser and in a loop back to the evaporator. A heated coolant reservoir is coupled to the loop for pressure control. If the wick is not wetted, heat transfer will not begin or continue. A pair of check valves are coupled in the loop, and the heater is cycled for augmentation pumping of coolant to and from the reservoir. This augmentation pumping, in conjunction with the check valves, wets the wick. The wick liquid storage capacity allows the augmentation pump to provide continuous pulsed liquid flow to assure continuous vapor transport and a continuously operating heat transport system. The check valves are of the ball type to assure maximum reliability. However, any type of check valve can be used, including designs which are preloaded in the closed position. The check valve may use any ball or poppet material which resists corrosion. For optimum performance during testing on Earth, the ball or poppet would have neutral buoyancy or be configured in a closed position when the heat transport system is not operating. The ball may be porous to allow passage of coolant vapor.

  20. Mesofluidic two stage digital valve

    DOEpatents

    Jansen, John F; Love, Lonnie J; Lind, Randall F; Richardson, Bradley S

    2013-12-31

    A mesofluidic scale digital valve system includes a first mesofluidic scale valve having a valve body including a bore, wherein the valve body is configured to cooperate with a solenoid disposed substantially adjacent to the valve body to translate a poppet carried within the bore. The mesofluidic scale digital valve system also includes a second mesofluidic scale valve disposed substantially perpendicular to the first mesofluidic scale valve. The mesofluidic scale digital valve system further includes a control element in communication with the solenoid, wherein the control element is configured to maintain the solenoid in an energized state for a fixed period of time to provide a desired flow rate through an orifice of the second mesofluidic valve.

  1. Optimizing the tensile properties of polyvinyl alcohol hydrogel for the construction of a bioprosthetic heart valve stent.

    PubMed

    Wan, W K; Campbell, G; Zhang, Z F; Hui, A J; Boughner, D R

    2002-01-01

    Although bioprosthetic heart valves offer the benefits of a natural opening and closing, better hemodynamics, and avoidance of life-long anticoagulant therapy, they nevertheless tend to fail in 10-15 years from tears and calcification. Several authors, including the present ones, have identified the rigid stent as a factor contributing to these failures. The ultimate solution is an artificial heart valve that has mechanical properties that allow it to move in conformity with the aortic root during the cardiac cycle, has superior hemodynamics, is nonthrombogenic, will last more than 20 years, and mitigates the need for anticoagulants. We have identified a polymer, polyvinyl alcohol (PVA) hydrogel, that has mechanical properties similar to soft tissue. The purpose of this research is to match the tensile properties of PVA to the porcine aortic root and to fabricate a stent prototype for a bioprosthetic heart valve with the use of the PVA hydrogel. Specimens of 15% w/w PVA were prepared by processing through 1-6 cycles of freezing (-20 degrees C) at 0.2 degrees C/min freeze rate and thawing (+20 degrees C) at different thawing rates (0.2 degrees C/min and 1 degrees C/min), for different holding times (1 and 6 h) at -20 degrees C. Subsequently tensile tests and stress-relaxation tests were conducted on the specimens. The different holding times at -20 degrees C demonstrated no difference in the result. The slower thawing rate improved the tensile properties but did not produce significant changes on the stress-relaxation properties. The nonlinear stress-strain curve for the PVA after the fourth freeze-thaw cycle matched the porcine aortic root within the physiological pressure range. The stress-relaxation curve for PVA also approximated the shape of the aortic root. The complex geometry of an artificial heart valve stent was successfully injection molded. These results, in combination with other preliminary findings for biocompatibility and fatigue behavior, suggest

  2. Can regurgitant flow damage the left atrial endothelium in patients with prosthetic mechanical heart valves?

    PubMed

    Milo, Simcha; Zarandi, Mehrdad; Gutfinger, Chaim; Gharib, Morteza

    2005-05-01

    Previous in-vitro studies of mechanical heart valves (MHVs) in the closed position demonstrated the formation of regurgitant flows, with bubbles and jets forming vortices during each systole. The study aim was to determine whether the regurgitant flow observed in patients with MHVs can damage the left atrial endothelium, due to shear stresses exerted on the endothelial layers. This objective has been accomplished by appropriate in-vitro simulation experiments. In these experiments, leakage flow through several commercial MHVs was investigated. The geometry of the set-up closely resembled that of the left atrial anatomy. Water was forced through the slit of a closed MHV and directed toward the hemispherical cup coated with fluorescent paint. The flow field between the valve and the cup was photographed using high-speed videography, from which local velocities were measured, using digital particle imaging velocimetry. Qualitative damage to the surface of the cup was assessed from the amount of fluorescent paint removed from the cup. The experimental results and calculations indicated that flows through the gaps of the closed valves were sufficient to generate strong vortices, with velocities near the atrial wall in the range of 0.5 to 4.0 m/s, depending on the valve. This led to high shear stresses on the left atrial wall, which far exceeded physiologically acceptable levels. The calculated shear stresses exceeded by orders of magnitude the maximum physiologically tolerated stresses. This suggests that shear stresses associated with regurgitant jets in MHVs may damage the endothelial cells, leading to the activation of the inflammatory reaction, enhanced procoagulation, platelet activation and aggregation, and mechanical cell denudation.

  3. Slow opening valve. [valve design for shuttle portable oxygen system

    NASA Technical Reports Server (NTRS)

    Drapeau, D. F. (Inventor)

    1984-01-01

    A valve control is described having a valve body with an actuator stem and a rotating handle connected to the actuator stem by a differential drive mechanism which, during uniform movement of the handle in one direction, initially opens the valve at a relatively slow rate and, thereafter, complete the valve movement at a substantially faster rate. A series of stop rings are received about the body in frictional abutting relationship and serially rotated by the handle to uniformly resist handle movement independently of the extent of handle movement.

  4. Internal Acoustics of a Pintle Valve with Supercritical Helium Flow

    NASA Technical Reports Server (NTRS)

    Fishbach, Sean R.; Davis, R. Benjamin

    2010-01-01

    Large amplitude flow unsteadiness is a common phenomenon within the high flow rate ducts and valves associated with propulsion systems. Boundary layer noise, shear layers and vortex shedding are a few of the many sources of flow oscillations. The presence of lightly damped acoustic modes can organize and amplify these sources of flow perturbation, causing undesirable loading of internal parts. The present study investigates the self-induced acoustic environment within a pintle valve subject to high Reynolds Number flow of helium gas. Experiments were conducted to measure the internal pressure oscillations of the Ares I Launch Abort System (LAS) Attitude Control Motor (ACM) valve. The AGM consists of a solid propellant gas generator with eight pintle valves attached to the aft end. The pintle valve is designed to deliver variable upstream conditions to an attache( converging diverging nozzle. In order to investigate the full range of operating conditions 28 separate tests were conducted with varying pintle position and upstream pressure. Helium gas was utilized in order to closely mimic the speed of sound of the gas generator exhaust, minimizing required scaling during data analysis. The recordec pressure measurements were interrogated to multiple ends. The development of root mean square (RMS) value! versus Reynolds Number and Pintle position are important to creating bounding unsteady load curves for valve internal parts. Spectral analysis was also performed, helping to identify power spectral densities (PSD) of acoustic natural frequencies and boundary layer noise. An interesting and unexpected result was the identification of an acoustic mode within the valve which does not respond until the valve was over 60% open. Further, the response amplitude around this mode can be as large or larger than those associated with lower frequency modes.

  5. The Technique for CFD-Simulation of Fuel Valve from Pneumatic-Hydraulic System of Liquid-Propellant Rocket Engine

    NASA Astrophysics Data System (ADS)

    Shabliy, L. S.; Malov, D. V.; Bratchinin, D. S.

    2018-01-01

    In the article the description of technique for simulation of valves for pneumatic-hydraulic system of liquid-propellant rocket engine (LPRE) is given. Technique is based on approach of computational hydrodynamics (Computational Fluid Dynamics - CFD). The simulation of a differential valve used in closed circuit LPRE supply pipes of fuel components is performed to show technique abilities. A schematic and operation algorithm of this valve type is described in detail. Also assumptions made in the construction of the geometric model of the hydraulic path of the valve are described in detail. The calculation procedure for determining valve hydraulic characteristics is given. Based on these calculations certain hydraulic characteristics of the valve are given. Some ways of usage of the described simulation technique for research the static and dynamic characteristics of the elements of the pneumatic-hydraulic system of LPRE are proposed.

  6. Lightweight Motorized Valve

    NASA Technical Reports Server (NTRS)

    Gonzalez, R.; Vandewalle, J.

    1986-01-01

    Redesigned actuator assembly weighs 50 percent less. Isolator valve operated by ac motor instead of usual dc solenoid. Valve weighs only 3 lb (1.4 kg). New valve functions with either two-phase or three-phase power. Developed for isolating fluids in propellant tanks, manifolds, and interconnecting lines of Space Shuttle reaction control and orbital maneuvering subsystems, valve suited to applications in which leakage must be kept to minimum at high pressure differences - in petroleum and chemical processing.

  7. Engine Cycle Analysis of Air Breathing Microwave Rocket with Reed Valves

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Fukunari, Masafumi; Komatsu, Reiji; Yamaguchi, Toshikazu

    The Microwave Rocket is a candidate for a low cost launcher system. Pulsed plasma generated by a high power millimeter wave beam drives a blast wave, and a vehicle acquires impulsive thrust by exhausting the blast wave. The thrust generation process of the Microwave Rocket is similar to a pulse detonation engine. In order to enhance the performance of its air refreshment, the air-breathing mechanism using reed valves is under development. Ambient air is taken to the thruster through reed valves. Reed valves are closed while the inside pressure is high enough. After the time when the shock wave exhaustsmore » at the open end, an expansion wave is driven and propagates to the thrust-wall. The reed valve is opened by the negative gauge pressure induced by the expansion wave and its reflection wave. In these processes, the pressure oscillation is important parameter. In this paper, the pressure oscillation in the thruster was calculated by CFD combined with the flux through from reed valves, which is estimated analytically. As a result, the air-breathing performance is evaluated using Partial Filling Rate (PFR), the ratio of thruster length to diameter L/D, and ratio of opening area of reed valves to superficial area {alpha}. An engine cycle and predicted thrust was explained.« less

  8. Cracking a tricuspid perimount bioprosthesis to optimize a second transcatheter sapien valve-in-valve placement.

    PubMed

    Brown, Stephen C; Cools, Bjorn; Gewillig, Marc

    2016-09-01

    Bioprosthetic valves degenerate over time. Transcatheter valve-in-valve procedures have become an attractive alternative to surgery. However, every valve increasingly diminishes the diameter of the valvar orifice. We report a 12-year-old female who had a previous transcatheter tricuspid valve-in-valve procedure; cracking the ring of a Carpentier Edwards Perimount valve by means of an ultrahigh pressure balloon allowed implantation of a further larger percutaneous valve. The advantage of this novel approach permits enlarging the inner valve diameter and may facilitate future interventions and prolong time to surgery. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  9. An air-pressure-free elastomeric valve for integrated nucleic acid analysis by capillary electrophoresis

    NASA Astrophysics Data System (ADS)

    Jung, Wooseok; Barrett, Matthew; Brooks, Carla; Rivera, Andrew; Birdsell, Dawn N.; Wagner, David M.; Zenhausern, Frederic

    2015-12-01

    We present a new elastomeric valve for integrated nucleic acid analysis by capillary electrophoresis. The valve functions include metering to capture a designated volume of biological sample into a polymerase chain reaction (PCR) chamber, sealing to preserve the sample during PCR cycling, and transfer of the PCR-products and on-chip formamide post-processing for the analysis of DNA fragments by capillary gel electrophoresis. This new valve differs from prior art polydimethylsiloxane (PDMS) valves in that the valve is not actuated externally by air-pressure or vacuum so that it simplifies a DNA analysis system by eliminating the need for an air-pressure or vacuum source, and off-cartridge solenoid valves, control circuit boards and software. Instead, the new valve is actuated by a thermal cycling peltier assembly integrated within the hardware instrument that tightly comes in contact with a microfluidic cartridge for thermal activation during PCR, so that it spontaneously closes the valve without an additional actuator system. The valve has bumps in the designated locations so that it has a self-alignment that does not require precise alignment of a valve actuator. Moreover, the thickness of the new valve is around 600 μm with an additional bump height of 400 μm so that it is easy to handle and very feasible to fabricate by injection molding compared to other PDMS valves whose thicknesses are around 30-100 μm. The new valve provided over 95% of metering performance in filling the fixed volume of the PCR chamber, preserved over 97% of the sample volume during PCR, and showed very comparable capillary electrophoresis peak heights to the benchtop assay tube controls with very consistent transfer volume of the PCR-product and on-chip formamide. The new valve can perform a core function for integrated nucleic acid analysis by capillary electrophoresis.

  10. Correlation of two-dimensional echocardiography and pathologic findings in porcine valve dysfunction.

    PubMed

    Forman, M B; Phelan, B K; Robertson, R M; Virmani, R

    1985-02-01

    Two-dimensional echocardiographic findings in porcine valve dysfunction were compared with pathologic findings in 10 patients (12 valves). Three specific echocardiographic findings were identified in patients with regurgitant lesions: prolapse, fracture and flail leaflets. Prolapse was associated pathologically with thinning of the leaflets, longitudinal tears close to the ring margin and acid mucopolysaccharide accumulation. Valve fracture was seen with and without prolapse and was accompanied pathologically by small pinpoint perforations or tears of the leaflet. A flail leaflet was seen with a linear tear of the free margin and was associated with calcific deposits. Mild degrees of fracture seen pathologically were missed on the echocardiographic study in five patients. Thickening or calcification, when present in moderate or severe amounts, was correctly identified by echocardiography. When all abnormal features were considered collectively, two-dimensional echocardiography correctly identified at least one of them in all patients. Therefore, two-dimensional echocardiography may prove useful in assessing the source of valvular regurgitation in patients with bioprosthetic valves.

  11. Structure and function of the tricuspid and bicuspid regurgitant aortic valve: an echocardiographic study.

    PubMed

    Rönnerfalk, Mattias; Tamás, Éva

    2015-07-01

    The emerging new treatment options for aortic valve disease call for more sophisticated diagnostics. We aimed to describe the echocardiographic pathophysiology and characteristics of the purely regurgitant aortic valve in detail. Twenty-nine men, with chronic aortic regurgitation without concomitant heart disease referred for aortic valve intervention, underwent 2D transoesophageal echocardiographic (TEE) examination prior to surgery according to a previously published matrix. Measurements of the aortic valve apparatus in long and short axis view were made in systole and diastole and analysed off-line. The aortic valves were grouped as tricuspid (TAV) or bicuspid (BAV), and classified by regurgitation mechanism. Twenty-four examinations were eligible for analysis of which 13 presented TAV and 11 BAV. The regurgitation mechanism was classified as dilatation of the aorta in 6 cases, as prolapse in 11 cases and as poor cusp tissue quality or quantity in 7 cases. The ventriculo-aortic junction (VAJ) and valve opening were closely related (TAV r = 0.5, BAV r = 0.73) but no correlation was found between the VAJ and the maximal sinus diameter (maxSiD) or the sinotubular junction (STJ). However, the STJ and maxSiD were significantly related (TAV vs BAV: systole r = 0.9, r = 0.8; diastole r = 0.9, r = 0.7), forming an entity. The conjoined BAV cusps were shorter than the anterior cusps when closed (P = 0.002); the inter-commissural distances of the cusps in the BAV group were significantly different (P = 0.001 resp. 0.03) in both systole and diastole. The VAJ was independent of other aortic dimensions and should thereby be considered as a separate entity with influence on valve opening. The detailed 2D TEE measurements of this study add further important information to our knowledge about the function and echocardiographic anatomy of the pathological aortic valve and root either as a stand-alone examination or as a benchmark and complement to 3D echocardiography. This may

  12. Transfemoral aortic valve implantation in severe aortic stenosis patients with prior mitral valve prosthesis

    PubMed Central

    Sarı, Cenk; Baştuğ, Serdal; Kasapkara, Hacı Ahmet; Durmaz, Tahir; Keleş, Telat; Akçay, Murat; Aslan, Abdullah Nabi; Bayram, Nihal Akar; Bozkurt, Engin

    2015-01-01

    Introduction Transcatheter aortic valve implantation for severe symptomatic aortic stenosis in patients with a previous mitral valve prosthesis is technically challenging, and pre-procedural comprehensive assessment of these patients before transcatheter aortic valve implantation is vital for an uncomplicated and successful procedure. Aim We want to share our experience with transcatheter aortic valve implantation in patients with a preexisting functional mitral valve prosthesis and describe a series of important technical and pre-procedural details. Material and methods At our center, 135 patients with symptomatic severe aortic stenosis were treated with transcatheter aortic valve implantation. Six of them with a preexisting mitral valve prosthesis received an Edwards SAPIEN XT valve through the transfemoral route. Results Transcatheter aortic valve implantation was performed successfully in all 6 patients without any deformation of the cobalt-chromium/steel stents of the aortic valve bioprosthesis. Also no distortion or malfunction in the mitral valve prosthesis was observed after the procedure. There were no complications during the hospitalization period. Post-procedural echocardiography revealed no or mild aortic paravalvular regurgitation and normal valve function in all the patients. In addition, serial echocardiographic examination demonstrated that both the stability and function of the aortic and mitral prosthetic valves were normal without any deterioration in the gradients and the degree of the regurgitation at long-term follow-ups. Conclusions Our experience confirms that transcatheter aortic valve implantation is technically feasible in patients with previous mitral valve replacement but comprehensive evaluation of patients by multimodal imaging techniques such as transesophageal echocardiography and multislice computed tomography is mandatory for a successful and safe procedure. PMID:26677380

  13. Kangaroo versus porcine aortic valve tissue--valve geometry morphology, tensile strength and calcification potential.

    PubMed

    Neethling, W M; Papadimitriou, J M; Swarts, E; Hodge, A J

    2000-06-01

    Valve related factors and patient related factors are responsible for calcification of valvular bioprostheses. Recent studies showed different donor and recipient species have different influences on the total calcification rate of bioprostheses. This study was performed to evaluate and compare Kangaroo aortic valve leaflets with porcine aortic valve leaflets. Experimental design. Prospective study. Setting. Cardio-thoracic experimental research of a university department. Glutaraldehyde-fixed Kangaroo and porcine valve leaflets were evaluated in vitro according to valve geometry (internal diameter and leaflet thickness), morphology (light and electron microscopy) and tensile strength. In vivo evaluation consisted of implantation in a rat model for 8 weeks, Von Kossa stain for calcium and atomic absorption spectrophotometry for total extractable calcium content. Kangaroo valves indicated a smaller internal valve diameter as well as a thinner valve leaflet (p<0.01, ANOVA) at corresponding body weight, less proteoglycan spicules in the fibrosa, increased elasticity (p<0.05) and low calcification potential (p<0.01, confidence interval 95%). Kangaroo aortic valve leaflets have different valvular qualities compared to porcine valve tissue. Kangaroo valve leaflets are significantly superior to porcine valve leaflets as far as calcification is concerned. These results are encouraging and suggest further in vivo evaluation in a larger animal model before clinical application can be considered.

  14. What Is Heart Valve Surgery?

    MedlinePlus

    ... working correctly. Most valve replacements involve the aortic Tricuspid valve and mitral valves. The aortic valve separates ... where it shouldn’t. This is called incompetence, insufficiency or regurgitation. • Prolapse — mitral valve flaps don’t ...

  15. What Is Heart Valve Disease?

    MedlinePlus

    ... and replacing it with a man-made or biological valve. Biological valves are made from pig, cow, or human ... the valve. Man-made valves last longer than biological valves and usually don’t have to be ...

  16. 46 CFR 154.532 - Valves: Cargo tank MARVS greater than 69 kPa gauge (10 psig).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Valves: Cargo tank MARVS greater than 69 kPa gauge (10... greater than 69 kPa gauge (10 psig). (a) Except connections for tank safety relief valves and except for... on a cargo tank with a MARVS greater than 69 kPa gauge (10 psig) must have, as close to the tank as...

  17. Valve repair in aortic regurgitation without root dilatation--aortic valve repair.

    PubMed

    Lausberg, H F; Aicher, D; Kissinger, A; Langer, F; Fries, R; Schäfers, H-J

    2006-02-01

    Aortic valve repair was established in the context of aortic root remodeling. Variable results have been reported for isolated valve repair. We analyzed our experience with isolated valve repair and compared the results with those of aortic root remodeling. Between October 1995 and August 2003, isolated repair of the aortic valve was performed in 83 patients (REP), remodeling of the aortic valve in 175 patients (REMO). The demographics of the two groups were comparable (REP: mean age 54.4 +/- 20.7 yrs, male-female ratio 2.1 : 1; REMO: mean age 60.8 +/- 13.6 yrs, male-female ratio 2.4 : 1; p = ns). In both groups the number of bicuspid valves was comparable (REP: 41 %, REMO: 32 %; p = ns). All patients were followed by echocardiography for a cumulative follow-up of 8204 patient months (mean 32 +/- 23 months). Overall in-hospital mortality was 2.4 % in REP and 4.6 % in REMO ( p = 0.62). Systolic gradients were comparable in both groups (REP: 5.8 +/- 2.2, REMO: 6.5 +/- 3.1 mm Hg, p = 0.09). The mean degree of aortic regurgitation 12 months postoperatively was 0.8 +/- 0.7 after REP and 0.7 +/- 0.7 after REMO ( p = 0.29). Freedom from significant regurgitation (> or = II degrees ) after 5 years was 86 % in REP and 89 % in REMO ( p = 0.17). Freedom from re-operation after 5 years was 94.4 % in REP and 98.2 % in REMO ( p = 0.33). Aortic regurgitation without concomitant root dilatation can be treated effectively by aortic valve repair. The functional results are equivalent to those obtained with valve-preserving root replacement. Aortic valve repair appears to be an alternative to valve replacement in aortic regurgitation.

  18. High response speed microfluidic ice valves with enhanced thermal conductivity and a movable refrigeration source

    NASA Astrophysics Data System (ADS)

    Si, Chaorun; Hu, Songtao; Cao, Xiaobao; Wu, Weichao

    2017-01-01

    Due to their ease of fabrication, facile use and low cost, ice valves have great potential for use in microfluidic platforms. For this to be possible, a rapid response speed is key and hence there is still much scope for improvement in current ice valve technology. Therefore, in this study, an ice valve with enhanced thermal conductivity and a movable refrigeration source has been developed. An embedded aluminium cylinder is used to dramatically enhance the heat conduction performance of the microfluidic platform and a movable thermoelectric unit eliminates the thermal inertia, resulting in a faster cooling process. The proposed ice valve achieves very short closing times (0.37 s at 10 μL/min) and also operates at high flow rates (1150 μL/min). Furthermore, the response time of the valve decreased by a factor of 8 when compared to current state of the art technology.

  19. Transapical JenaValve in a patient with mechanical mitral valve prosthesis.

    PubMed

    O' Sullivan, Katie E; Casserly, Ivan; Hurley, John

    2015-04-01

    We report the first case of transcatheter aortic valve replacement implantation using JenaValve™ in a patient with mechanical mitral valve prosthesis. We believe that the design features of this valve may be particularly suited for use in this setting. © 2014 Wiley Periodicals, Inc.

  20. Magnetically operated check valve

    NASA Astrophysics Data System (ADS)

    Morris, Brian G.; Bozeman, Richard J., Jr.

    1993-03-01

    A magnetically operated check valve is disclosed having, in one aspect, a valve body and a movable poppet disposed therein. A magnet attracts the poppet to hold the valve shut until the force of fluid flow through the valve overcomes the magnetic attraction and moves the poppet to an unseated, open position. The poppet and magnet are configured and disposed to trap a magnetically attracted particulate and prevent it from flowing to a valve seating region.

  1. Double-orifice mitral valve associated with bicuspid aortic valve.

    PubMed

    Khani, Mohammad; Rohani, Atoosheh

    2017-06-01

    Double-orifice mitral valve is a rare congenital anomaly that usually does not cause a significant hemodynamic effect. Double-orifice mitral valve and a bicuspid aortic valve were detected in a 54-year-old lady who presented with dyspnea on exertion for one year. This is a rare association. Three-dimensional echocardiography is helpful to determine the type of malformation. The patient had no significant mitral regurgitation or stenosis, but demonstrated moderate aortic stenosis. She is undergoing periodic monitoring.

  2. Shuttle Primary Reaction Control Subsystem Thruster Fuel Valve Pilot Seal Extrusion: A Failure Correlation

    NASA Technical Reports Server (NTRS)

    Waller, Jess; Saulsberry, Regor L.

    2003-01-01

    Pilot operated valves (POVs) are used to control the flow of hypergolic propellants monomethylhydrazine (fuel) and nitrogen tetroxide (oxidizer) to the Shuttle orbiter Primary Reaction Control Subsystem (PRCS) thrusters. The POV incorporates a two-stage design: a solenoid-actuated pilot stage, which in turn controls a pressure-actuated main stage. Isolation of propellant supply from the thruster chamber is accomplished in part by a captive polytetrafluoroethylene (PTFE) pilot seal retained inside a Custom 455.1 stainless steel cavity. Extrusion of the pilot seal restricts the flow of fuel around the pilot poppet, thus impeding or preventing the main valve stage from opening. It can also prevent the main stage from staying open with adequate force margin, particularly if there is gas in the main stage actuation cavity. During thruster operation on-orbit, fuel valve pilot seal extrusion is commonly indicated by low or erratic chamber pressure or failure of the thruster to fire upon command (Fail-Off). During ground turnaround, pilot seal extrusion is commonly indicated by slow gaseous nitrogen (GN2) main valve opening times (greater than 38 ms) or slow water main valve opening response times (greater than 33 ms). Poppet lift tests and visual inspection can also detect pilot seal extrusion during ground servicing; however, direct metrology on the pilot seat assembly provides the most quantitative and accurate means of identifying extrusion. Minimizing PRCS fuel valve pilot seal extrusion has become an important issue in the effort to improve PRCS reliability and reduce associated life cycle costs.

  3. Design of the Electronic Brake Pressure Modulator Using a Direct Adaptive Fuzzy Controller in Commercial Vehicles for the Safety of Braking in Fail

    NASA Astrophysics Data System (ADS)

    Kim, Hunmo

    In the brake systems, it is important to reduce the rear brake pressure in order to secure the safety of the vehicle in braking. So, there was some research that reduced and controlled the rear brake pressure exactly like a L. S. P. V and a E. L. S. P. V. However, the previous research has some weaknesses: the L. S. P. V is a mechanical system and its brake efficiency is lower than the efficiency of E. L. S. P. V. But, the cost of E. L. S. P. V is very higher so its application to the vehicle is very difficult. Additionally, when a fail appears in the circuit which controls the valves, the fail results in some wrong operation of the valves. But, the previous researchers didn't take the effect of fail into account. Hence, the efficiency of them is low and the safety of the vehicle is not confirmed. So, in this paper we develop a new economical pressure modulator that exactly controls brake pressure and confirms the safety of the vehicle in any case using a direct adaptive fuzzy controller.

  4. Tricuspid valve repair for severe tricuspid regurgitation due to pacemaker leads.

    PubMed

    Uehara, Kyokun; Minakata, Kenji; Watanabe, Kentaro; Sakaguchi, Hisashi; Yamazaki, Kazuhiro; Ikeda, Tadashi; Sakata, Ryuzo

    2016-07-01

    Tricuspid valve regurgitation due to pacemaker leads is a well-known complication. Although some reports have suggested that pacemaker leads should be surgically explanted, strongly adhered leads cannot always be removed. The aim of this study was to describe our tricuspid valve repair techniques with pacemaker leads left in situ. Our retrospective study investigated 6 consecutive patients who required tricuspid valve surgery for severe regurgitation induced by pacemaker leads. From the operative findings, we identified 3 patterns of tricuspid valve and pacemaker lead involvement. In 3 patients, the leads were caught in the chordae, in 2 patients, tricuspid regurgitation was caused by lead impingement on the septal leaflet, and in 3 patients, tricuspid valve leaflets had been perforated by the pacemaker leads. During surgery, all leads were left in situ after being separated from the leaflet or valvular apparatus. In addition, suture annuloplasty was performed for annular dilatation in all cases. In one patient, the lead was reaffixed to the annulus after the posterior leaflet was cut back towards the annulus, and the leaflet was then closed. There was one hospital death due to sepsis. The degree of tricuspid regurgitation was trivial in all surviving patients at discharge. During a mean follow-up of 21 months, one patient died from pneumonia 20 months after tricuspid valve repair. In patients undergoing tricuspid valve surgery due to severe tricuspid regurgitation caused by pacemaker leads, the leads can be left in situ after proper repair with annuloplasty. © The Author(s) 2016.

  5. Valve-sparing aortic root replacement in bicuspid aortic valves: a reasonable option?

    PubMed

    Aicher, Diana; Langer, Frank; Kissinger, Anke; Lausberg, Henning; Fries, Roland; Schäfers, Hans-Joachim

    2004-11-01

    Aortic dilatation occurs in many patients with bicuspid aortic valves. We have added root replacement using the remodeling technique originally designed for tricuspid aortic valves to bicuspid aortic valve repair for treatment of the dilated root. We compared the results of remodeling in bicuspid aortic valves with those in tricuspid aortic valves. From October 1995 through January 2004, 60 patients underwent root remodeling for bicuspid aortic valves (group A), and 130 patients underwent root remodeling for tricuspid aortic valves (group B). Correction of cusp prolapse was more often performed in group A (group A, 50/60; group B, 47/130; P < .0001). Transthoracic echocardiography was performed at 1 week, 6 and 12 months, and every year thereafter. Cumulative follow-up was 527 patient-years (mean, 2.9 +/- 2 years). No patient died in group A. Hospital mortality in group B was 5% (5/100; 95% confidence interval,1.6%-11.3%) after elective operations and 10% (3/30; 95% confidence interval, 2.1%-26.5%) after emergency operations. Mean systolic gradients were identical at 1 year (group A, 4.8 +/- 2.1 mm Hg; group B, 4.0 +/- 2 mm Hg) and 5 years (group A, 4.5 +/- 2.3 mm Hg; group B, 3.9 +/- 2.2 mm Hg). Freedom from aortic regurgitation of grade 2 or higher at 5 years was 96% in group A and 83% in group B ( P = .07), and freedom from reoperation at 5 years was 98% in group A and 98% in group B ( P = .73). Valve-sparing aortic replacement with root remodeling can be applied to aortic dilatation and a regurgitant bicuspid aortic valve. Hemodynamic function and valve stability of a repaired bicuspid aortic valve are comparable with those seen in cases of tricuspid anatomy.

  6. Remote actuated valve implant

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    McKnight, Timothy E.; Johnson, Anthony; Moise, Kenneth J.

    Valve implant systems positionable within a flow passage, the systems having an inlet, an outlet, and a remotely activatable valve between the inlet and outlet, with the valves being operable to provide intermittent occlusion of the flow path. A remote field is applied to provide thermal or magnetic activation of the valves.

  7. Valve for fluid control

    DOEpatents

    Oborny, Michael C.; Paul, Phillip H.; Hencken, Kenneth R.; Frye-Mason, Gregory C.; Manginell, Ronald P.

    2001-01-01

    A valve for controlling fluid flows. This valve, which includes both an actuation device and a valve body provides: the ability to incorporate both the actuation device and valve into a unitary structure that can be placed onto a microchip, the ability to generate higher actuation pressures and thus control higher fluid pressures than conventional microvalves, and a device that draws only microwatts of power. An electrokinetic pump that converts electric potential to hydraulic force is used to operate, or actuate, the valve.

  8. Experimental investigations on the fluid-mechanics of an electrospun heart valve by means of particle image velocimetry.

    PubMed

    Del Gaudio, Costantino; Gasbarroni, Pier Luca; Romano, Giovanni Paolo

    2016-12-01

    End-stage failing heart valves are currently replaced by mechanical or biological prostheses. Both types positively contribute to restore the physiological function of native valves, but a number of drawbacks limits the expected performances. In order to improve the outcome, tissue engineering can offer an alternative approach to design and fabricate innovative heart valves capable to support the requested function and to promote the formation of a novel, viable and correctly operating physiological structure. This potential result is particularly critical if referred to the aortic valve, being the one mainly exposed to structural and functional degeneration. In this regard, the here proposed study presents the fabrication and in vitro characterization of a bioresorbable electrospun heart valve prosthesis using the particle image velocimetry technique either in physiological and pathological fluid dynamic conditions. The scaffold was designed to reproduce the aortic valve geometry, also mimicking the fibrous structure of the natural extracellular matrix. To evaluate its performances for possible implantation, the flow fields downstream the valve were accurately investigated and compared. The experimental results showed a correct functionality of the device, supported by the formation of vortex structures at the edge of the three cusps, with Reynolds stress values below the threshold for the risk of hemolysis (which can be comprised in the range 400-4000N/m(2) depending on the exposure period), and a good structural resistance to the mechanical loads generated by the driving pressure difference. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Solid handling valve

    DOEpatents

    Williams, William R.

    1979-01-01

    The present invention is directed to a solids handling valve for use in combination with lock hoppers utilized for conveying pulverized coal to a coal gasifier. The valve comprises a fluid-actuated flow control piston disposed within a housing and provided with a tapered primary seal having a recessed seat on the housing and a radially expandable fluid-actuated secondary seal. The valve seals are highly resistive to corrosion, erosion and abrasion by the solids, liquids, and gases associated with the gasification process so as to minimize valve failure.

  10. VALVE

    DOEpatents

    Arkelyan, A.M.; Rickard, C.L.

    1962-04-17

    A gate valve for controlling the flow of fluid in separate concentric ducts or channels by means of a single valve is described. In one position, the valve sealing discs engage opposed sets of concentric ducts leading to the concentric pipes defining the flow channels to block flow therethrough. In another position, the discs are withdrawn from engagement with the opposed ducts and at the same time a bridging section is interposed therebetween to define concentric paths coextensive with and connecting the opposed ducts to facilitate flow therebetween. A wedge block arrangement is employed with each sealing disc to enable it to engage the ducts. The wedge block arrangement also facilitates unobstructcd withdrawal of the discs out of the intervening space between the sets of ducts. (AEC)

  11. Liquid rocket valve components

    NASA Technical Reports Server (NTRS)

    1973-01-01

    A monograph on valves for use with liquid rocket propellant engines is presented. The configurations of the various types of valves are described and illustrated. Design criteria and recommended practices for the various valves are explained. Tables of data are included to show the chief features of valve components in use on operational vehicles.

  12. Failure Analysis of Fractured Poppet from Space Shuttle Orbiter Flow Control Valve

    NASA Technical Reports Server (NTRS)

    Russell, Richard

    2010-01-01

    This slide presentation reviews the failure analysis of a fractured poppet from a flow control valve (FCV) used on the space shuttle. This presentation has focused on the laboratory analysis of the failed hardware. The use of Scanning electron fractography during the investigation led to the conclusion that the poppet failed due to fatigue cracking that, most likely, occurred under changing loading conditions. The initial investigation led to a more thorough test of poppets that had been retired, this testing led to the conclusion that the thumbnail cracks in the flight hardware had existed for the life of the shuttle program. This led to a program to develop an eddy current technique that was capable of detecting small very tight cracks.

  13. Valve assembly for internal combustion engine

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wakeman, R.J.; Shea, S.F.

    1989-09-05

    This patent describes an improvement in a valve assembly for an internal combustion engine of the type including a valve having a valve stem, a valve guideway for mounting this valve for reciprocal strokes between opened and seated position, and spring means for biasing the valve into the seated position. The improvement comprising a valve spool of greater cross-sectional diameter as compared to the valve stem, and a valve spool guideway within which the valve spool is movable during the strokes of the valve, an upper surface of the valve spool and a portion of the spool guideway collectively establishingmore » a damper chamber which varies in volume during the valve strokes. a feed passage for introducing oil into the damper chamber, and a bleed passage for discharging oil from the damper chamber. The bleed passages each laterally opening into the valve spool guideway.« less

  14. Transcatheter Aortic Valve Implantation: Experience with the CoreValve Device.

    PubMed

    Asgar, Anita W; Bonan, Raoul

    2012-01-01

    The field of transcatheter aortic valve implantation has been rapidly evolving. The Medtronic CoreValve first emerged on the landscape in 2004 with initial first human studies, and it is currently being studied in the Pivotal US trial. This article details the current experience with the self-expanding aortic valve with a focus on clinical results and ongoing challenges. Copyright © 2012 Elsevier Inc. All rights reserved.

  15. Multiple-port valve

    DOEpatents

    Doody, Thomas J.

    1978-08-22

    A multiple-port valve assembly is designed to direct flow from a primary conduit into any one of a plurality of secondary conduits as well as to direct a reverse flow. The valve includes two mating hemispherical sockets that rotatably receive a spherical valve plug. The valve plug is attached to the primary conduit and includes diverging passageways from that conduit to a plurality of ports. Each of the ports is alignable wih one or more of a plurality of secondary conduits fitted into one of the hemispherical sockets. The other hemispherical socket includes a slot for the primary conduit such that the conduit's motion along that slot with rotation of the spherical plug about various axes will position the valve-plug ports in respect to the secondary conduits.

  16. Sensor-integrated polymer actuators for closed-loop drug delivery system

    NASA Astrophysics Data System (ADS)

    Xu, Han; Wang, Chunlei; Kulinsky, Lawrence; Zoval, Jim; Madou, Marc

    2006-03-01

    This work presents manufacturing and testing of a closed-loop drug delivery system where drug release is achieved by an electrochemical actuation of an array of polymeric valves on a set of drug reservoirs. The valves are based on bi-layer structures made of polypyrrole/gold in the shape of a flap that is hinged on one side of a valve seat. Drugs stored in the underlying chambers are released by bending the bi-layer flaps back with a small applied bias. These polymeric valves simultaneously function as both drug release components and biological/chemical sensors responding to a specific biological or environmental stimulus. The sensors may send signals to the control module to realize closed-loop control of the drug release. In this study a glucose sensor has been integrated with the polymeric actuators through immobilization of glucose oxidase(GOx) within polypyrrole(PPy) valves. Sensitivities per unit area of the integrated glucose sensor have been measured and compared before and after the actuation of the sensor/actuator PPy/DBS/GOx film. Other sensing parameters such as linear range and response time were discussed as well. Using an array of these sensor/actuator cells, the amount of released drug, e.g. insulin, can be precisely controlled according to the surrounding glucose concentration detected by the glucose sensor. Activation of these reservoirs can be triggered either by the signal from the sensor, or by the signal from the operator. This approach also serves as the initial step to use the proposed system as an implantable drug delivery platform in the future.

  17. Solenoid Valve With Self-Compensation

    NASA Technical Reports Server (NTRS)

    Woeller, Fritz H.; Matsumoto, Yutaka

    1987-01-01

    New solenoid-operated miniature shutoff valve provides self-compensation of differential pressure forces that cause jamming or insufficient valve closure as in single-seal valves. Dual-seal valve is bidirectional. Valve simultaneously seals both inlet and outlet tubes by pressing single disk of silicone rubber against ends of both.

  18. Ahmed glaucoma valve in children: A review☆

    PubMed Central

    Nassiri, Nariman; Nouri-Mahdavi, Kouros; Coleman, Anne L.

    2011-01-01

    Pediatric glaucoma is potentially a blinding disease. Although goniotomy and trabeculotomy are associated with good early success rates, eventually 20% of these procedures fail and many children will require additional surgery to control the IOP in the long-term. In this review, we reported that adequate IOP control can be achieved with the placement of Ahmed glaucoma valve and can last 5 or more years. However, most patients will need one or more glaucoma medications at some point after surgery. In addition, the implants may be associated with pupillary irregularities, lenticular opacification as well as tube-related complications, particularly in the first year of life, as the globe is enlarging with age. PMID:23960945

  19. High response speed microfluidic ice valves with enhanced thermal conductivity and a movable refrigeration source

    PubMed Central

    Si, Chaorun; Hu, Songtao; Cao, Xiaobao; Wu, Weichao

    2017-01-01

    Due to their ease of fabrication, facile use and low cost, ice valves have great potential for use in microfluidic platforms. For this to be possible, a rapid response speed is key and hence there is still much scope for improvement in current ice valve technology. Therefore, in this study, an ice valve with enhanced thermal conductivity and a movable refrigeration source has been developed. An embedded aluminium cylinder is used to dramatically enhance the heat conduction performance of the microfluidic platform and a movable thermoelectric unit eliminates the thermal inertia, resulting in a faster cooling process. The proposed ice valve achieves very short closing times (0.37 s at 10 μL/min) and also operates at high flow rates (1150 μL/min). Furthermore, the response time of the valve decreased by a factor of 8 when compared to current state of the art technology. PMID:28084447

  20. Study of multiple cycles valves

    NASA Technical Reports Server (NTRS)

    Wichmann, H.

    1973-01-01

    A discussion is presented regarding valves which can be cycled repeatedly and are available from industry for application in the inlet system for the Pioneer Venus Probe mass spectrometer. Both solenoid type and latching type valves are considered. The study is divided into two principal areas: (1) preparation of a valve specification reflecting the requirements of the inlet system cyclic valves for the Pioneer Venus Probe mass spectrometer and the submittal of this specification to potential valve suppliers for their response and proposal; (2) preparation of a design layout of an optimum cyclic valve meeting all of the valve specification requirements.

  1. Mitral valve replacement with the Hancock stabilized glutaraldehyde valve. Clinical and laboratory evaluation.

    PubMed

    Buch, W S; Pipkin, R D; Hancock, W D; Fogarty, T J

    1975-11-01

    From March 1971 through April 1975, one hundred twenty patients underwent mitral valve replacement with a Hancock "stabilized glutaraldehyde process" porcine aortic xenograft. A simultaneous canine experimental series was also carried out. In the clinical series, the early mortality was 8.3%. Actuarial analyses of all patients predicts survival at two years of 81.0% and at four years of 70.0%. The predicted survival for patients without coronary disease or prior prosthetic valve replacement is 87.5% at two years and 77.5% at four years. There were four thromboembolic episodes, a rate of 2.4% per patient-year. None were fatal. No valve failure were noted. Histologic examination and shrink temperature analysis of recovered valves show excellent tissue preservation at 40 months. The data indicate that the Hancock valve is durable, enjoys a low incidence of thromboembolism, and may be the valve of choice for mitral valve replacement.

  2. Anterior mitral valve aneurysm: a rare sequelae of aortic valve endocarditis.

    PubMed

    Janardhanan, Rajesh; Kamal, Muhammad Umar; Riaz, Irbaz Bin; Smith, M Cristy

    2016-03-01

    SummaryIn intravenous drug abusers, infective endocarditis usually involves right-sided valves, with Staphylococcus aureus being the most common etiologic agent. We present a patient who is an intravenous drug abuser with left-sided (aortic valve) endocarditis caused by Enterococcus faecalis who subsequently developed an anterior mitral valve aneurysm, which is an exceedingly rare complication. A systematic literature search was conducted which identified only five reported cases in the literature of mitral valve aneurysmal rupture in the setting of E. faecalis endocarditis. Real-time 3D-transesophageal echocardiography was critical in making an accurate diagnosis leading to timely intervention. Early recognition of a mitral valve aneurysm (MVA) is important because it may rupture and produce catastrophic mitral regurgitation (MR) in an already seriously ill patient requiring emergency surgery, or it may be overlooked at the time of aortic valve replacement (AVR).Real-time 3D-transesophageal echocardiography (RT-3DTEE) is much more advanced and accurate than transthoracic echocardiography for the diagnosis and management of MVA. © 2016 The authors.

  3. Fast acting multiple element valve

    DOEpatents

    Yang, Jefferson Y. S.; Wada, James M.

    1991-01-01

    A plurality of slide valve elements having plural axial-spaced annular parts and an internal slide are inserted into a bulkhead in a fluid conduit from a downstream side of the bulkhead, locked in place by a bayonet coupling and set screw, and project through the bulkhead into the upstream conduit. Pneumatic lines connecting the slide valve element actuator to pilot valves are brought out the throat of the valve element to the downstream side. Pilot valves are radially spaced around the exterior of the valve to permit the pneumatic lines to be made identical, thereby to minimize adverse timing tolerances in operation due to pressure variations. Ring manifolds surround the valve adjacent respective pilot valve arrangements to further reduce adverse timing tolerances due to pressure variations, the manifolds being directly connected to the respective pilot valves. Position sensors are provided the valve element slides to signal the precise time at which a slide reaches or passes through a particular point in its stroke to initiate a calibrated timing function.

  4. Conical seat shut off valve

    NASA Technical Reports Server (NTRS)

    Farner, Bruce R. (Inventor)

    2012-01-01

    A valve includes a housing defining a bore having an inlet and extending along a longitudinal axis. A head is attached to the housing and defines a head passage having an outlet. A piston is disposed within the bore and includes a piston passage extending through the piston along the longitudinal axis. The piston is moveable between a closed position in which a sealing end of the piston abuts a seat of the head to close fluid communication through the piston passage and an open position in which the sealing end of the piston is axially spaced along the longitudinal axis from the seat of the head to permit fluid communication through the piston passage between the inlet and the outlet. The housing defines an equalizing chamber in fluid communication with the head passage for damping movement of the piston.

  5. Fast-acting valve and uses thereof

    DOEpatents

    Meyer, J.A.

    1980-05-16

    A very fast acting valve capable of producing a very well-defined plug of gas suitable for filling a theta pinch vacuum vessel is given. The valve requires no springs, instead being stopped mainly by a nonlinear force. Thus, the valve is not subject to bouncing; and the ratio of the size of the valve housing to the size of the valve stem is smaller than it would be if springs were needed to stop the valve stem. Furthermore, the valve can be used for thousands of valve firings with no apparent valve damage.

  6. Fast-acting valve and uses thereof

    DOEpatents

    Meyer, James A.

    1982-01-01

    A very fast acting valve capable of producing a very well-defined plug of gas suitable for filling a theta pinch vacuum vessel is given. The valve requires no springs, instead being stopped mainly by a nonlinear force. Thus, the valve is not subject to bouncing; and the ratio of the size of the valve housing to the size of the valve stem is smaller than it would be if springs were needed to stop the valve stem. Furthermore, the valve can be used for thousands of valve firings with no apparent valve damage.

  7. The prognosis of infective endocarditis treated with biological valves versus mechanical valves: A meta-analysis.

    PubMed

    Tao, Ende; Wan, Li; Wang, WenJun; Luo, YunLong; Zeng, JinFu; Wu, Xia

    2017-01-01

    Surgery remains the primary form of treatment for infective endocarditis (IE). However, it is not clear what type of prosthetic valve provides a better prognosis. We conducted a meta-analysis to compare the prognosis of infective endocarditis treated with biological valves to cases treated with mechanical valves. Pubmed, Embase and Cochrane databases were searched from January 1960 to November 2016.Randomized controlled trials, retrospective cohorts and prospective studies comparing outcomes between biological valve and mechanical valve management for infective endocarditis were analyzed. The Newcastle-Ottawa Scale(NOS) was used to evaluate the quality of the literature and extracted data, and Stata 12.0 software was used for the meta-analysis. A total of 11 publications were included; 10,754 cases were selected, involving 6776 cases of biological valves and 3,978 cases of mechanical valves. The all-cause mortality risk of the biological valve group was higher than that of the mechanical valve group (HR = 1.22, 95% CI 1.03 to 1.44, P = 0.023), as was early mortality (RR = 1.21, 95% CI 1.02 to 1.43, P = 0.033). The recurrence of endocarditis (HR = 1.75, 95% CI 1.26 to 2.42, P = 0.001), as well as the risk of reoperation (HR = 1.79, 95% CI 1.15 to 2.80, P = 0.010) were more likely to occur in the biological valve group. The incidence of postoperative embolism was less in the biological valve group than in the mechanical valve group, but this difference was not statistically significant (RR = 0.90, 95% CI 0.76 to 1.07, P = 0.245). For patients with prosthetic valve endocarditis (PVE), there was no significant difference in survival rates between the biological valve group and the mechanical valve group (HR = 0.91, 95% CI 0.68 to 1.21, P = 0.520). The results of our meta-analysis suggest that mechanical valves can provide a significantly better prognosis in patients with infective endocarditis. There were significant differences in the clinical features of patients

  8. The prognosis of infective endocarditis treated with biological valves versus mechanical valves: A meta-analysis

    PubMed Central

    Tao, Ende; Wan, Li; Wang, WenJun; Luo, YunLong; Zeng, JinFu; Wu, Xia

    2017-01-01

    Objective Surgery remains the primary form of treatment for infective endocarditis (IE). However, it is not clear what type of prosthetic valve provides a better prognosis. We conducted a meta-analysis to compare the prognosis of infective endocarditis treated with biological valves to cases treated with mechanical valves. Methods Pubmed, Embase and Cochrane databases were searched from January 1960 to November 2016.Randomized controlled trials, retrospective cohorts and prospective studies comparing outcomes between biological valve and mechanical valve management for infective endocarditis were analyzed. The Newcastle-Ottawa Scale(NOS) was used to evaluate the quality of the literature and extracted data, and Stata 12.0 software was used for the meta-analysis. Results A total of 11 publications were included; 10,754 cases were selected, involving 6776 cases of biological valves and 3,978 cases of mechanical valves. The all-cause mortality risk of the biological valve group was higher than that of the mechanical valve group (HR = 1.22, 95% CI 1.03 to 1.44, P = 0.023), as was early mortality (RR = 1.21, 95% CI 1.02 to 1.43, P = 0.033). The recurrence of endocarditis (HR = 1.75, 95% CI 1.26 to 2.42, P = 0.001), as well as the risk of reoperation (HR = 1.79, 95% CI 1.15 to 2.80, P = 0.010) were more likely to occur in the biological valve group. The incidence of postoperative embolism was less in the biological valve group than in the mechanical valve group, but this difference was not statistically significant (RR = 0.90, 95% CI 0.76 to 1.07, P = 0.245). For patients with prosthetic valve endocarditis (PVE), there was no significant difference in survival rates between the biological valve group and the mechanical valve group (HR = 0.91, 95% CI 0.68 to 1.21, P = 0.520). Conclusion The results of our meta-analysis suggest that mechanical valves can provide a significantly better prognosis in patients with infective endocarditis. There were significant differences in

  9. Heart valve surgery - series (image)

    MedlinePlus

    ... heart valves are either natural (biologic) or artificial (mechanical). Natural valves are from human donors (cadavers), modified ... artificial valves will require anticoagulation. The advantage of mechanical valves is that they last longer-thus, the ...

  10. Valve Repair or Replacement

    MedlinePlus

    ... called anticoagulants) for the rest of their lives. Biological valves are made from animal tissue (called a ... for valve replacement (called an autograft). Patients with biological valves usually do not need to take blood- ...

  11. Fluid mechanics of heart valves.

    PubMed

    Yoganathan, Ajit P; He, Zhaoming; Casey Jones, S

    2004-01-01

    Valvular heart disease is a life-threatening disease that afflicts millions of people worldwide and leads to approximately 250,000 valve repairs and/or replacements each year. Malfunction of a native valve impairs its efficient fluid mechanic/hemodynamic performance. Artificial heart valves have been used since 1960 to replace diseased native valves and have saved millions of lives. Unfortunately, despite four decades of use, these devices are less than ideal and lead to many complications. Many of these complications/problems are directly related to the fluid mechanics associated with the various mechanical and bioprosthetic valve designs. This review focuses on the state-of-the-art experimental and computational fluid mechanics of native and prosthetic heart valves in current clinical use. The fluid dynamic performance characteristics of caged-ball, tilting-disc, bileaflet mechanical valves and porcine and pericardial stented and nonstented bioprostheic valves are reviewed. Other issues related to heart valve performance, such as biomaterials, solid mechanics, tissue mechanics, and durability, are not addressed in this review.

  12. Intelligent Flow Control Valve

    NASA Technical Reports Server (NTRS)

    Kelley, Anthony R (Inventor)

    2015-01-01

    The present invention is an intelligent flow control valve which may be inserted into the flow coming out of a pipe and activated to provide a method to stop, measure, and meter flow coming from the open or possibly broken pipe. The intelligent flow control valve may be used to stop the flow while repairs are made. Once repairs have been made, the valve may be removed or used as a control valve to meter the amount of flow from inside the pipe. With the addition of instrumentation, the valve may also be used as a variable area flow meter and flow controller programmed based upon flowing conditions. With robotic additions, the valve may be configured to crawl into a desired pipe location, anchor itself, and activate flow control or metering remotely.

  13. How to Make a Heart Valve: From Embryonic Development to Bioengineering of Living Valve Substitutes

    PubMed Central

    MacGrogan, Donal; Luxán, Guillermo; Driessen-Mol, Anita; Bouten, Carlijn; Baaijens, Frank; de la Pompa, José Luis

    2014-01-01

    Cardiac valve disease is a significant cause of ill health and death worldwide, and valve replacement remains one of the most common cardiac interventions in high-income economies. Despite major advances in surgical treatment, long-term therapy remains inadequate because none of the current valve substitutes have the potential for remodeling, regeneration, and growth of native structures. Valve development is coordinated by a complex interplay of signaling pathways and environmental cues that cause disease when perturbed. Cardiac valves develop from endocardial cushions that become populated by valve precursor mesenchyme formed by an epithelial–mesenchymal transition (EMT). The mesenchymal precursors, subsequently, undergo directed growth, characterized by cellular compartmentalization and layering of a structured extracellular matrix (ECM). Knowledge gained from research into the development of cardiac valves is driving exploration into valve biomechanics and tissue engineering directed at creating novel valve substitutes endowed with native form and function. PMID:25368013

  14. Are prosthetic heart valve fibrin strands negligible? The associations and significance.

    PubMed

    Kiavar, Majid; Sadeghpour, Anita; Bakhshandeh, Hooman; Tayyebi, Parisa; Bassiri, Hossein Ali; Esmaeilzadeh, Maryam; Maleki, Majid; Noohi, Feridoun

    2009-08-01

    Filamentous fibrin strands (FSs) attached to valve prostheses have been well described in patients undergoing transesophageal echocardiography, but the frequency and clinical significance of these strands remain poorly defined. The aims of this study were to determine the frequency of prosthetic valve strands and to assess their significance in relation to clinical cerebral ischemic events (CIEs) and anticoagulant status. Three hundred consecutive patients with 421 prosthetic heart valves were evaluated for the presence of FSs (highly mobile, filamentous masses<1 mm thick). FSs were found in 139 patients (49%) and 147 prostheses (38%) in patients with left-sided prostheses, with a significant association between FSs, CIEs, and anticoagulant status (P<.001). A lower international normalized ratio (<2.5) had a positive association with the occurrence of CIEs. There is a significant association between FSs, CIEs, and patient's anticoagulant status; therefore, aggressive anticoagulation and close follow-up are recommended for these patients.

  15. Lagrangian coherent structures in the left ventricle in the presence of aortic valve regurgitation

    NASA Astrophysics Data System (ADS)

    di Labbio, Giuseppe; Vetel, Jerome; Kadem, Lyes

    2017-11-01

    Aortic valve regurgitation is a rather prevalent condition where the aortic valve improperly closes, allowing filling of the left ventricle of the heart to occur partly from backflow through the aortic valve. Although studies of intraventricular flow are rapidly gaining popularity in the fluid dynamics research community, much attention has been given to the left ventricular vortex and its potential for early detection of disease, particularly in the case of dilated cardiomyopathy. Notably, the subsequent flow in the left ventricle in the presence of aortic valve regurgitation ought to be appreciably disturbed and has yet to be described. Aortic valve regurgitation was simulated in vitro in a double-activation left heart duplicator and the ensuing flow was captured using two-dimensional time-resolved particle image velocimetry. Further insight into the regurgitant flow is obtained by computing attracting and repelling Lagrangian coherent structures. An interesting interplay between the two inflowing jets and their shear layer roll-up is observed for various grades of regurgitation. This study highlights flow features which may find use in further assessing regurgitation severity.

  16. International Heart Valve Bank Survey: A Review of Processing Practices and Activity Outcomes

    PubMed Central

    Albrecht, Helmi; Lim, Yeong Phang; Manning, Linda

    2013-01-01

    A survey of 24 international heart valve banks was conducted to acquire information on heart valve processing techniques used and outcomes achieved. The objective was to provide an overview of heart valve banking activities for tissue bankers, tissue banking associations, and regulatory bodies worldwide. Despite similarities found for basic manufacturing processes, distinct differences in procedural details were also identified. The similarities included (1) use of sterile culture media for procedures, (2) antibiotic decontamination, (3) use of dimethyl sulfoxide (DMSO) as a cryoprotectant, (4) controlled rate freezing for cryopreservation, and (5) storage at ultralow temperatures of below −135°C. Differences in procedures included (1) type of sterile media used, (2) antibiotics combination, (3) temperature and duration used for bioburden reduction, (4) concentration of DMSO used for cryopreservation, and (5) storage duration for released allografts. For most banks, the primary reasons why allografts failed to meet release criteria were positive microbiological culture and abnormal morphology. On average, 85% of allografts meeting release criteria were implanted, with valve size and type being the main reasons why released allografts were not used clinically. The wide variation in percentage of allografts meeting release requirements, despite undergoing validated manufacturing procedures, justifies the need for regular review of important outcomes as cited in this paper, in order to encourage comparison and improvements in the HVBs' processes. PMID:24163756

  17. Long life valve design concepts

    NASA Technical Reports Server (NTRS)

    Jones, J. R.; Hall, A. H., Jr.

    1975-01-01

    Valve concept evaluation, final candidate selection, design, manufacture, and demonstration testing of a pneumatically actuated 10-inch hybrid poppet butterfly shutoff valve are presented. Conclusions and recommendations regarding those valve characteristics and features which would serve to guide in the formulation of future valve procurements are discussed. The pertinent design goals were temperature range of plus 200 to minus 423 F, valve inlet pressure 35 psia, actuation pressure 750 psia, main seal leakage 3 x 0.00001 sccs at 35 psia valve inlet pressure, and a storage and operating life of 10 years. The valve was designed to be compatible with RP-1, propane, LH2, LO2, He, and N2.

  18. The Double-Orifice Valve Technique to Treat Tricuspid Valve Incompetence.

    PubMed

    Hetzer, Roland; Javier, Mariano; Delmo Walter, Eva Maria

    2016-01-01

    A straightforward tricuspid valve (TV) repair technique was used to treat either moderate or severe functional (normal valve with dilated annulus) or for primary/organic (Ebstein's anomaly, leaflet retraction/tethering and chordal malposition/tethering, with annular dilatation) TV incompetence, and its long-term outcome assessed. A double-orifice valve technique was employed in 91 patients (mean age 52.6 ± 23.2 years; median age 56 years; range: 0.6-82 years) with severe tricuspid regurgitation. Among the patients, three had post-transplant iatrogenic chordal rupture, five had infective endocarditis, 11 had mitral valve insufficiency, 23 had Ebstein's anomaly, and 47 had isolated severe TV incompetence. The basic principle was to reduce the distance between the coapting leaflets, wherein the most mobile leaflet could coapt to the opposite leaflet, by creating two orifices, ensuring valve competence. The TV repair was performed through a median sternotomy or right anterior thoracotomy in the fifth intercostal space under cardiopulmonary bypass. The degree and extent of creating a double-valve orifice was determined by considering the minimal body surface area (BSA)-related acceptable TV diameter. Repair was accomplished by passing pledgeted mattress sutures from the middle of the true anterior annulus to a spot on the opposite septal annulus, located approximately two-thirds of the length of the septal annulus to avoid injury to the bundle of His. The annular apposition divides the TV into a larger anterior and a smaller posterior orifices, enabling valve closure, on both sides. In adults, the diameter of the anterior valve orifice should be 23-25 mm, and the posterior orifice 15-18 mm; thus, the total valve orifice area is 5-6 cm2. In children, the total valve orifice should be a standard deviation of 1.7 mm for a BSA of <1. 0m2, and 1.5 mm for a BSA of >1.0m2. During a mean follow up of 8.7 ± 1.34 years (median 10 years; range: 1.5-25.9 years) there have been no

  19. Miniature electrically operated diaphragm valve

    DOEpatents

    Adkins, Douglas R.; Spletzer, Barry L.; Wong, Chungnin C.; Frye-Mason, Gregory C.; Fischer, Gary J.; Hesketh, Peter J.

    2001-01-01

    The present invention provides a miniature electrically operated valve that can stand off significant pressures, that can be inexpensively produced, and that can be made to operate without continuous electrical power. A valve according to the present invention comprises a housing and a beam mounted with the housing. A diaphragm mounted with the housing forms a sealed fluid volume. An electromagnetic energy source, such as an electromagnetic coil, mounts with the housing and when energized urges the beam in one direction. The beam can be urged in the opposing direction by passive means or by reversing the polarity of the electromagnetic energy source or by a second electromagnetic energy source. Two fluid ports mount with the housing. A first fluid port mounts so that, as the beam is urged in one direction or the opposite, the beam urges the diaphragm to move between engaging and substantially sealing the fluid port and disengaging and not substantially sealing the fluid port. A seat can be mounted with the diaphragm to aid in sealing the fluid port. Latching mechanisms such as permanent magnets can be mounted so that the valve remains in the open or closed positions without continuous electrical power input. Fluid can flow through the housing between the two fluid ports when the diaphragm does not seal the first fluid port, but can be prevented from flowing by urging the beam so that the diaphragm seals the first fluid port. Various embodiments accommodate various latching mechanisms, electromagnetic energy sources, number of fluid ports, and diaphragm design considerations.

  20. Towards real-time cardiovascular magnetic resonance guided transarterial CoreValve implantation: in vivo evaluation in swine

    PubMed Central

    2012-01-01

    Background Real-time cardiovascular magnetic resonance (rtCMR) is considered attractive for guiding TAVI. Owing to an unlimited scan plane orientation and an unsurpassed soft-tissue contrast with simultaneous device visualization, rtCMR is presumed to allow safe device navigation and to offer optimal orientation for precise axial positioning. We sought to evaluate the preclinical feasibility of rtCMR-guided transarterial aortic valve implatation (TAVI) using the nitinol-based Medtronic CoreValve bioprosthesis. Methods rtCMR-guided transfemoral (n = 2) and transsubclavian (n = 6) TAVI was performed in 8 swine using the original CoreValve prosthesis and a modified, CMR-compatible delivery catheter without ferromagnetic components. Results rtCMR using TrueFISP sequences provided reliable imaging guidance during TAVI, which was successful in 6 swine. One transfemoral attempt failed due to unsuccessful aortic arch passage and one pericardial tamponade with subsequent death occurred as a result of ventricular perforation by the device tip due to an operating error, this complication being detected without delay by rtCMR. rtCMR allowed for a detailed, simultaneous visualization of the delivery system with the mounted stent-valve and the surrounding anatomy, resulting in improved visualization during navigation through the vasculature, passage of the aortic valve, and during placement and deployment of the stent-valve. Post-interventional success could be confirmed using ECG-triggered time-resolved cine-TrueFISP and flow-sensitive phase-contrast sequences. Intended valve position was confirmed by ex-vivo histology. Conclusions Our study shows that rtCMR-guided TAVI using the commercial CoreValve prosthesis in conjunction with a modified delivery system is feasible in swine, allowing improved procedural guidance including immediate detection of complications and direct functional assessment with reduction of radiation and omission of contrast media. PMID:22453050

  1. Towards real-time cardiovascular magnetic resonance guided transarterial CoreValve implantation: in vivo evaluation in swine.

    PubMed

    Kahlert, Philipp; Parohl, Nina; Albert, Juliane; Schäfer, Lena; Reinhardt, Renate; Kaiser, Gernot M; McDougall, Ian; Decker, Brad; Plicht, Björn; Erbel, Raimund; Eggebrecht, Holger; Ladd, Mark E; Quick, Harald H

    2012-03-27

    Real-time cardiovascular magnetic resonance (rtCMR) is considered attractive for guiding TAVI. Owing to an unlimited scan plane orientation and an unsurpassed soft-tissue contrast with simultaneous device visualization, rtCMR is presumed to allow safe device navigation and to offer optimal orientation for precise axial positioning. We sought to evaluate the preclinical feasibility of rtCMR-guided transarterial aortic valve implatation (TAVI) using the nitinol-based Medtronic CoreValve bioprosthesis. rtCMR-guided transfemoral (n = 2) and transsubclavian (n = 6) TAVI was performed in 8 swine using the original CoreValve prosthesis and a modified, CMR-compatible delivery catheter without ferromagnetic components. rtCMR using TrueFISP sequences provided reliable imaging guidance during TAVI, which was successful in 6 swine. One transfemoral attempt failed due to unsuccessful aortic arch passage and one pericardial tamponade with subsequent death occurred as a result of ventricular perforation by the device tip due to an operating error, this complication being detected without delay by rtCMR. rtCMR allowed for a detailed, simultaneous visualization of the delivery system with the mounted stent-valve and the surrounding anatomy, resulting in improved visualization during navigation through the vasculature, passage of the aortic valve, and during placement and deployment of the stent-valve. Post-interventional success could be confirmed using ECG-triggered time-resolved cine-TrueFISP and flow-sensitive phase-contrast sequences. Intended valve position was confirmed by ex-vivo histology. Our study shows that rtCMR-guided TAVI using the commercial CoreValve prosthesis in conjunction with a modified delivery system is feasible in swine, allowing improved procedural guidance including immediate detection of complications and direct functional assessment with reduction of radiation and omission of contrast media.

  2. 46 CFR 38.10-1 - Valves, fittings, and accessories-TB/ALL.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... outlet connection or the quick-closing valve, even in the event of abnormal displacement of the piping.... Tables shall be readily available for direct determination of volume of liquid in the tanks, with necessary corrections for trim, temperature, and density. (2) An independent high level alarm shall be...

  3. 46 CFR 38.10-1 - Valves, fittings, and accessories-TB/ALL.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... outlet connection or the quick-closing valve, even in the event of abnormal displacement of the piping.... Tables shall be readily available for direct determination of volume of liquid in the tanks, with necessary corrections for trim, temperature, and density. (2) An independent high level alarm shall be...

  4. 46 CFR 38.10-1 - Valves, fittings, and accessories-TB/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... outlet connection or the quick-closing valve, even in the event of abnormal displacement of the piping.... Tables shall be readily available for direct determination of volume of liquid in the tanks, with necessary corrections for trim, temperature, and density. (2) An independent high level alarm shall be...

  5. 46 CFR 38.10-1 - Valves, fittings, and accessories-TB/ALL.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... outlet connection or the quick-closing valve, even in the event of abnormal displacement of the piping.... Tables shall be readily available for direct determination of volume of liquid in the tanks, with necessary corrections for trim, temperature, and density. (2) An independent high level alarm shall be...

  6. 46 CFR 38.10-1 - Valves, fittings, and accessories-TB/ALL.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... outlet connection or the quick-closing valve, even in the event of abnormal displacement of the piping.... Tables shall be readily available for direct determination of volume of liquid in the tanks, with necessary corrections for trim, temperature, and density. (2) An independent high level alarm shall be...

  7. Compact valve actuation mechanism

    NASA Technical Reports Server (NTRS)

    Brogdon, James William (Inventor); Gill, David Keith (Inventor)

    2000-01-01

    A valve actuation device. The device may include a free floating valve bridge movably supported within a cavity in the engine housing. The bridge may be provided with a cavity and an orifice arrangement for pumping gases entrained with lubricating fluid toward the piston stems as the bridge reciprocates back and forth. The device may also include a rocker arm that has a U-shaped cross-sectional shape for receiving at least a portion of the valve bridge, valve stem valve spring and spring retainer therein. The rocker arm may be provided with lubrication passages for directing lubrication to the point wherein it is pivotally affixed to the engine housing.

  8. Improved mitral valve coaptation and reduced mitral valve annular size after percutaneous mitral valve repair (PMVR) using the MitraClip system.

    PubMed

    Patzelt, Johannes; Zhang, Yingying; Magunia, Harry; Ulrich, Miriam; Jorbenadze, Rezo; Droppa, Michal; Zhang, Wenzhong; Lausberg, Henning; Walker, Tobias; Rosenberger, Peter; Seizer, Peter; Gawaz, Meinrad; Langer, Harald F

    2017-08-01

    Improved mitral valve leaflet coaptation with consecutive reduction of mitral regurgitation (MR) is a central goal of percutaneous mitral valve repair (PMVR) with the MitraClip® system. As influences of PMVR on mitral valve geometry have been suggested before, we examined the effect of the procedure on mitral annular size in relation to procedural outcome. Geometry of the mitral valve annulus was evaluated in 183 patients undergoing PMVR using echocardiography before and after the procedure and at follow-up. Mitral valve annular anterior-posterior (ap) diameter decreased from 34.0 ± 4.3 to 31.3 ± 4.9 mm (P < 0.001), and medio-lateral (ml) diameter from 33.2 ± 4.8 to 32.4 ± 4.9 mm (P < 0.001). Accordingly, we observed an increase in MV leaflet coaptation after PMVR. The reduction of mitral valve ap diameter showed a significant inverse correlation with residual MR. Importantly, the reduction of mitral valve ap diameter persisted at follow-up (31.3 ± 4.9 mm post PMVR, 28.4 ± 5.3 mm at follow-up). This study demonstrates mechanical approximation of both mitral valve annulus edges with improved mitral valve annular coaptation by PMVR using the MitraClip® system, which correlates with residual MR in patients with MR. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2017. For permissions, please email: journals.permissions@oup.com.

  9. Valve technology: A compilation

    NASA Technical Reports Server (NTRS)

    1971-01-01

    A technical compilation on the types, applications and modifications to certain valves is presented. Data cover the following: (1) valves that feature automatic response to stimuli (thermal, electrical, fluid pressure, etc.), (2) modified valves changed by redesign of components to increase initial design effectiveness or give the item versatility beyond its basic design capability, and (3) special purpose valves with limited application as presented, but lending themselves to other uses with minor changes.

  10. The Melody® valve and Ensemble® delivery system for transcatheter pulmonary valve replacement

    PubMed Central

    McElhinney, Doff B; Hennesen, Jill T

    2013-01-01

    The Melody® transcatheter pulmonary valve (TPV) is a percutaneous valve system designed for the treatment of obstruction and/or regurgitation of prosthetic conduits placed between the right ventricle and pulmonary arteries in patients with congenital heart disease. In 2000, Melody TPV became the first transcatheter valve implanted in a human; in 2006 it became the first transcatheter valve commercially available anywhere in the world; and in 2010 it was launched as the first commercially available transcatheter valve in the United States. In this review, we present the clinical background against which the Melody valve was developed and implemented, introduce the rationale for and challenges of transcatheter valve technology for this population, outline the history and technical details of its development and use, and summarize currently available data concerning the performance of the device. PMID:23834411

  11. Comparison of acute elastic recoil between the SAPIEN-XT and SAPIEN valves in transfemoral-transcatheter aortic valve replacement.

    PubMed

    Garg, Aatish; Parashar, Akhil; Agarwal, Shikhar; Aksoy, Olcay; Hammadah, Muhammad; Poddar, Kanhaiya Lal; Puri, Rishi; Svensson, Lars G; Krishnaswamy, Amar; Tuzcu, E Murat; Kapadia, Samir R

    2015-02-15

    The SAPIEN-XT is a newer generation balloon-expandable valve created of cobalt chromium frame, as opposed to the stainless steel frame used in the older generation SAPIEN valve. We sought to determine if there was difference in acute recoil between the two valves. All patients who underwent transfemoral-transcatheter aortic valve replacement using the SAPIEN-XT valve at the Cleveland Clinic were included. Recoil was measured using biplane cine-angiographic image analysis of valve deployment. Acute recoil was defined as [(valve diameter at maximal balloon inflation) - (valve diameter after deflation)]/valve diameter at maximal balloon inflation (reported as percentage). Patients undergoing SAPIEN valve implantation were used as the comparison group. Among the 23 mm valves, the mean (standard deviation-SD) acute recoil was 2.77% (1.14) for the SAPIEN valve as compared to 3.75% (1.52) for the SAPIEN XT valve (P = 0.04). Among the 26 mm valves, the mean (SD) acute recoil was 2.85% (1.4) for the SAPIEN valve as compared to 4.32% (1.63) for the SAPIEN XT valve (P = 0.01). Multivariable linear regression analysis demonstrated significantly greater adjusted recoil in the SAPIEN XT valves as compared to the SAPIEN valves by 1.43% [(95% CI: 0.69-2.17), P < 0.001]. However, the residual peak gradient was less for SAPIEN XT compared to SAPIEN valves [18.86 mm Hg versus 23.53 mm Hg (P = 0.01)]. Additionally, no difference in paravalvular leak was noted between the two valve types (P = 0.78). The SAPIEN XT valves had significantly greater acute recoil after deployment compared to the SAPIEN valves. Implications of this difference in acute recoil on valve performance need to be investigated in future studies. © 2014 Wiley Periodicals, Inc.

  12. Self-Rupturing Hermetic Valve

    NASA Technical Reports Server (NTRS)

    Tucker, Curtis E., Jr.; Sherrit, Stewart

    2011-01-01

    For commercial, military, and aerospace applications, low-cost, small, reliable, and lightweight gas and liquid hermetically sealed valves with post initiation on/off capability are highly desirable for pressurized systems. Applications include remote fire suppression, single-use system-pressurization systems, spacecraft propellant systems, and in situ instruments. Current pyrotechnic- activated rupture disk hermetic valves were designed for physically larger systems and are heavy and integrate poorly with portable equipment, aircraft, and small spacecraft and instrument systems. Additionally, current pyrotechnically activated systems impart high g-force shock loads to surrounding components and structures, which increase the risk of damage and can require additional mitigation. The disclosed mechanism addresses the need for producing a hermetically sealed micro-isolation valve for low and high pressure for commercial, aerospace, and spacecraft applications. High-precision electrical discharge machining (EDM) parts allow for the machining of mated parts with gaps less than a thousandth of an inch. These high-precision parts are used to support against pressure and extrusion, a thin hermetically welded diaphragm. This diaphragm ruptures from a pressure differential when the support is removed and/or when the plunger is forced against the diaphragm. With the addition of conventional seals to the plunger and a two-way actuator, a derivative of this design would allow nonhermetic use as an on/off or metering valve after the initial rupturing of the hermetic sealing disk. In addition, in a single-use hermetically sealed isolation valve, the valve can be activated without the use of potential leak-inducing valve body penetrations. One implementation of this technology is a high-pressure, high-flow-rate rupture valve that is self-rupturing, which is advantageous for high-pressure applications such as gas isolation valves. Once initiated, this technology is self

  13. Leaving Moderate Tricuspid Valve Regurgitation Alone at the Time of Pulmonary Valve Replacement: A Worthwhile Approach.

    PubMed

    Kogon, Brian; Mori, Makoto; Alsoufi, Bahaaldin; Kanter, Kirk; Oster, Matt

    2015-06-01

    Pulmonary valve disruption in patients with tetralogy of Fallot and congenital pulmonary stenosis often results in pulmonary insufficiency, right ventricular dilation, and tricuspid valve regurgitation. Management of functional tricuspid regurgitation at the time of subsequent pulmonary valve replacement remains controversial. Our aims were to (1) analyze tricuspid valve function after pulmonary valve replacement through midterm follow-up and (2) determine the benefits, if any, of concomitant tricuspid annuloplasty. Thirty-five patients with tetralogy of Fallot or congenital pulmonary stenosis were analyzed. All patients had been palliated in childhood by disrupting the pulmonary valve, and all patients had at least moderate tricuspid valve regurgitation at the time of subsequent pulmonary valve replacement. Preoperative and serial postoperative echocardiograms were analyzed. Pulmonary and tricuspid regurgitation, along with right ventricular dilation and dysfunction were scored as 0 (none), 1 (mild), 2 (moderate), and 3 (severe). Right ventricular volume and area were also calculated. Comparisons were made between patients who underwent pulmonary valve replacement alone and those who underwent concomitant tricuspid valve annuloplasty. At 1 month after pulmonary valve replacement, there were significant reductions in pulmonary valve regurgitation (mean 3 vs 0.39, p < 0.0001), tricuspid valve regurgitation (mean 2.33 vs 1.3, p < 0.0001), and in right ventricular dilation, volume, and area. There was no difference in the degree of tricuspid regurgitation 1 month postoperatively between patients who underwent concomitant tricuspid annuloplasty and those who underwent pulmonary valve replacement alone (mean 1.31 vs 1.29, p = 0.81). However, at latest follow-up (mean 7.0 ± 2.8 years), the degree of tricuspid regurgitation was significantly higher in the concomitant annuloplasty group (mean 1.87 vs 1.12, p = 0.005). In patients with at least moderate tricuspid valve

  14. Vacuum/compression valving (VCV) using parrafin-wax on a centrifugal microfluidic CD platform.

    PubMed

    Al-Faqheri, Wisam; Ibrahim, Fatimah; Thio, Tzer Hwai Gilbert; Moebius, Jacob; Joseph, Karunan; Arof, Hamzah; Madou, Marc

    2013-01-01

    This paper introduces novel vacuum/compression valves (VCVs) utilizing paraffin wax. A VCV is implemented by sealing the venting channel/hole with wax plugs (for normally-closed valve), or to be sealed by wax (for normally-open valve), and is activated by localized heating on the CD surface. We demonstrate that the VCV provides the advantages of avoiding unnecessary heating of the sample/reagents in the diagnostic process, allowing for vacuum sealing of the CD, and clear separation of the paraffin wax from the sample/reagents in the microfluidic process. As a proof of concept, the microfluidic processes of liquid flow switching and liquid metering is demonstrated with the VCV. Results show that the VCV lowers the required spinning frequency to perform the microfluidic processes with high accuracy and ease of control.

  15. Vacuum/Compression Valving (VCV) Using Parrafin-Wax on a Centrifugal Microfluidic CD Platform

    PubMed Central

    Al-Faqheri, Wisam; Ibrahim, Fatimah; Thio, Tzer Hwai Gilbert; Moebius, Jacob; Joseph, Karunan; Arof, Hamzah; Madou, Marc

    2013-01-01

    This paper introduces novel vacuum/compression valves (VCVs) utilizing paraffin wax. A VCV is implemented by sealing the venting channel/hole with wax plugs (for normally-closed valve), or to be sealed by wax (for normally-open valve), and is activated by localized heating on the CD surface. We demonstrate that the VCV provides the advantages of avoiding unnecessary heating of the sample/reagents in the diagnostic process, allowing for vacuum sealing of the CD, and clear separation of the paraffin wax from the sample/reagents in the microfluidic process. As a proof of concept, the microfluidic processes of liquid flow switching and liquid metering is demonstrated with the VCV. Results show that the VCV lowers the required spinning frequency to perform the microfluidic processes with high accuracy and ease of control. PMID:23505528

  16. Application of color Doppler flow mapping to calculate orifice area of St Jude mitral valve

    NASA Technical Reports Server (NTRS)

    Leung, D. Y.; Wong, J.; Rodriguez, L.; Pu, M.; Vandervoort, P. M.; Thomas, J. D.

    1998-01-01

    BACKGROUND: The effective orifice area (EOA) of a prosthetic valve is superior to transvalvular gradients as a measure of valve function, but measurement of mitral prosthesis EOA has not been reliable. METHODS AND RESULTS: In vitro flow across St Jude valves was calculated by hemispheric proximal isovelocity surface area (PISA) and segment-of-spheroid (SOS) methods. For steady and pulsatile conditions, PISA and SOS flows correlated with true flow, but SOS and not PISA underestimated flow. These principles were then used intraoperatively to calculate cardiac output and EOA of newly implanted St Jude mitral valves in 36 patients. Cardiac output by PISA agreed closely with thermodilution (r=0.91, Delta=-0.05+/-0.55 L/min), but SOS underestimated it (r=0.82, Delta=-1.33+/-0.73 L/min). Doppler EOAs correlated with Gorlin equation estimates (r=0.75 for PISA and r=0.68 for SOS, P<0.001) but were smaller than corresponding in vitro EOA estimates. CONCLUSIONS: Proximal flow convergence methods can calculate forward flow and estimate EOA of St Jude mitral valves, which may improve noninvasive assessment of prosthetic mitral valve obstruction.

  17. Multiple-Step Injection Molding for Fibrin-Based Tissue-Engineered Heart Valves

    PubMed Central

    Weber, Miriam; Gonzalez de Torre, Israel; Moreira, Ricardo; Frese, Julia; Oedekoven, Caroline; Alonso, Matilde; Rodriguez Cabello, Carlos J.

    2015-01-01

    Heart valves are elaborate and highly heterogeneous structures of the circulatory system. Despite the well accepted relationship between the structural and mechanical anisotropy and the optimal function of the valves, most approaches to create tissue-engineered heart valves (TEHVs) do not try to mimic this complexity and rely on one homogenous combination of cells and materials for the whole construct. The aim of this study was to establish an easy and versatile method to introduce spatial diversity into a heart valve fibrin scaffold. We developed a multiple-step injection molding process that enables the fabrication of TEHVs with heterogeneous composition (cell/scaffold material) of wall and leaflets without the need of gluing or suturing components together, with the leaflets firmly connected to the wall. The integrity of the valves and their functionality was proved by either opening/closing cycles in a bioreactor (proof of principle without cells) or with continuous stimulation over 2 weeks. We demonstrated the potential of the method by the two-step molding of the wall and the leaflets containing different cell lines. Immunohistology after stimulation confirmed tissue formation and demonstrated the localization of the different cell types. Furthermore, we showed the proof of principle fabrication of valves using different materials for wall (fibrin) and leaflets (hybrid gel of fibrin/elastin-like recombinamer) and with layered leaflets. The method is easy to implement, does not require special facilities, and can be reproduced in any tissue-engineering lab. While it has been demonstrated here with fibrin, it can easily be extended to other hydrogels. PMID:25654448

  18. Multiple-Step Injection Molding for Fibrin-Based Tissue-Engineered Heart Valves.

    PubMed

    Weber, Miriam; Gonzalez de Torre, Israel; Moreira, Ricardo; Frese, Julia; Oedekoven, Caroline; Alonso, Matilde; Rodriguez Cabello, Carlos J; Jockenhoevel, Stefan; Mela, Petra

    2015-08-01

    Heart valves are elaborate and highly heterogeneous structures of the circulatory system. Despite the well accepted relationship between the structural and mechanical anisotropy and the optimal function of the valves, most approaches to create tissue-engineered heart valves (TEHVs) do not try to mimic this complexity and rely on one homogenous combination of cells and materials for the whole construct. The aim of this study was to establish an easy and versatile method to introduce spatial diversity into a heart valve fibrin scaffold. We developed a multiple-step injection molding process that enables the fabrication of TEHVs with heterogeneous composition (cell/scaffold material) of wall and leaflets without the need of gluing or suturing components together, with the leaflets firmly connected to the wall. The integrity of the valves and their functionality was proved by either opening/closing cycles in a bioreactor (proof of principle without cells) or with continuous stimulation over 2 weeks. We demonstrated the potential of the method by the two-step molding of the wall and the leaflets containing different cell lines. Immunohistology after stimulation confirmed tissue formation and demonstrated the localization of the different cell types. Furthermore, we showed the proof of principle fabrication of valves using different materials for wall (fibrin) and leaflets (hybrid gel of fibrin/elastin-like recombinamer) and with layered leaflets. The method is easy to implement, does not require special facilities, and can be reproduced in any tissue-engineering lab. While it has been demonstrated here with fibrin, it can easily be extended to other hydrogels.

  19. Slide valve apparatus for internal combustion engine

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Taylor, B.A.; McMahan, T.O.

    This patent describes an internal combustion engine including a combustion cylinder having an opening at one end thereof, a piston mounted within the cylinder for coaxial reciprocable movement, a driven crankshaft, and a connecting rod connecting the crankshaft to the cylinder for linear reciprocable movement of the piston in response to the rotary movement of the crankshaft, a valve apparatus comprising: (a) a valve chamber extending longitudinally across and in fluid communication with the opening in the cylinder, (b) an intake valve plate having a longitudinal axis mounted within the valve chamber for slidable, reciprocable, longitudinal movement, (c) an exhaustmore » valve plate having a longitudinal axis mounted within the valve chamber alongside the intake valve plate for slidable, reciprocable, longitudinal movement and parallel to the longitudinal axis of the intake valve plate, (d) each of the valve plates having a plurality of longitudinally spaced valve ports therein, the valve ports comprising movable intake valve ports in the intake valve plate and movable exhaust valve ports in the exhaust valve plate, (e) the valve chamber comprising a planar wall on the opposite side of the valve plates from the cylinder opening and having a plurality of fixed valve ports therethrough. The fixed valve ports being equal in number and substantially equal in size and spacing as the movable intake and exhaust valve ports, whereby the movable intake valve ports are adapted to register with their corresponding fixed valve ports when the intake valve plate is in its intake operative position for opening fluid communication between the cylinder and the corresponding fixed valve ports.« less

  20. Three-dimensional printed trileaflet valve conduits using biological hydrogels and human valve interstitial cells.

    PubMed

    Duan, B; Kapetanovic, E; Hockaday, L A; Butcher, J T

    2014-05-01

    Tissue engineering has great potential to provide a functional de novo living valve replacement, capable of integration with host tissue and growth. Among various valve conduit fabrication techniques, three-dimensional (3-D) bioprinting enables deposition of cells and hydrogels into 3-D constructs with anatomical geometry and heterogeneous mechanical properties. Successful translation of this approach, however, is constrained by the dearth of printable and biocompatible hydrogel materials. Furthermore, it is not known how human valve cells respond to these printed environments. In this study, 3-D printable formulations of hybrid hydrogels are developed, based on methacrylated hyaluronic acid (Me-HA) and methacrylated gelatin (Me-Gel), and used to bioprint heart valve conduits containing encapsulated human aortic valvular interstitial cells (HAVIC). Increasing Me-Gel concentration resulted in lower stiffness and higher viscosity, facilitated cell spreading, and better maintained HAVIC fibroblastic phenotype. Bioprinting accuracy was dependent upon the relative concentrations of Me-Gel and Me-HA, but when optimized enabled the fabrication of a trileaflet valve shape accurate to the original design. HAVIC encapsulated within bioprinted heart valves maintained high viability, and remodeled the initial matrix by depositing collagen and glyosaminoglycans. These findings represent the first rational design of bioprinted trileaflet valve hydrogels that regulate encapsulated human VIC behavior. The use of anatomically accurate living valve scaffolds through bioprinting may accelerate understanding of physiological valve cell interactions and progress towards de novo living valve replacements. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  1. Vct system having closed loop control employing spool valve actuated by a stepper motor

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Quin, S.B. Jr.; Siemon, E.C.

    1993-06-15

    An internal combustion engine is described comprising: a crankshaft, the crankshaft being rotable about an axis; a cam shaft, the cam shaft being rotatable about a second axis, the second axis being parallel to the axis, the cam shaft being subject to torque reversals during the rotation thereof; a vane, the vane having at least one lobe, the vane being attached to the cam shaft, being rotatable with the cam shaft and being non-oscillatable with respect to the cam shaft; a housing, the housing being rotatable with the cam shaft and being oscillatable with respect to the cam shaft, themore » housing having at least one recess, the recess receiving the lobe, the lobe being oscillatable within the recess; rotary movement transmitting means for transmitting rotary movement from the crankshaft to the housing; actuating means for varying the position of the housing relative to the cam shaft in reaction to torque reversals in the cam shaft, the actuating means comprising a stepper motor, a lead screw and a proportional spool valve, the position of the spool valve being controlled by the position of the lead screw driven by the stepper motor, the actuating means also delivering hydraulic fluid to the vane; and processing means for controlling the position of the actuating means.« less

  2. Maladjustment of programmable ventricular shunt valves by inadvertent exposure to a common hospital device.

    PubMed

    Fujimura, R; Lober, R; Kamian, K; Kleiner, L

    2018-01-01

    Programmable ventricular shunt valves are commonly used to treat hydrocephalus. They can be adjusted to allow for varying amounts of cerebrospinal fluid (CSF) flow using an external magnetic programming device, and are susceptible to maladjustment from inadvertent exposure to magnetic fields. We describe the case of a 3-month-old girl treated for hydrocephalus with a programmable Strata TM II valve found at the incorrect setting on multiple occasions during her hospitalization despite frequent reprogramming and surveillance. We found that the Vocera badge, a common hands-free wireless communication system worn by our nursing staff, had a strong enough magnetic field to unintentionally change the shunt setting. The device is worn on the chest bringing it into close proximity to the shunt valve when care providers hold the baby, resulting in the maladjustment. Some commonly used medical devices have a magnetic field strong enough to alter programmable shunt valve settings. Here, we report that the magnetic field from the Vocera hands-free wireless communication system, combined with the worn position, results in shunt maladjustment for the Strata TM II valve. Healthcare facilities using the Vocera badges need to put protocols in place and properly educate staff members to ensure the safety of patients with Strata TM II valves.

  3. Lock For Valve Stem

    NASA Technical Reports Server (NTRS)

    Burley, Richard K.; Guirguis, Kamal S.

    1991-01-01

    Simple, cheap device locks valve stem so its setting cannot be changed by unauthorized people. Device covers valve stem; cover locked in place with standard padlock. Valve lock made of PVC pipe and packing band. Shears, drill or punch, and forming rod only tools needed.

  4. The Art of Saving a Failing School

    ERIC Educational Resources Information Center

    Stein, Les

    2012-01-01

    While the debate continues over whether to close failing schools or attempt fixing them, the author asserts that the solution most often lies in assigning strong leaders to them who will take definite and immediate action. Reviewing his own success turning around schools, he says creating a sense of urgency, unloading poor performing staff, and…

  5. Clinical use of closed-system safety peripheral intravenous cannulas.

    PubMed

    Barton, Andrew

    2018-04-26

    Peripheral intravenous (IV) cannulas are the quickest and most effective way of gaining venous vascular access and administering IV therapy. Closed-system peripheral IV cannulas have been shown to be safe and more reliable than open, non-valved peripheral cannulas in clinical practice. This article introduces the Smiths Medical DeltaVen closed-system peripheral IV cannula and includes three case studies describing its use in clinical practice and associated patient outcomes.

  6. Björk-Shiley convexoconcave valves: susceptibility artifacts at brain MR imaging and mechanical valve fractures.

    PubMed

    van Gorp, Maarten J; van der Graaf, Yolanda; de Mol, Bas A J M; Bakker, Chris J G; Witkamp, Theo D; Ramos, Lino M P; Mali, Willem P T M

    2004-03-01

    To assess the relationship between heart valve history and susceptibility artifacts at magnetic resonance (MR) imaging of the brain in patients with Björk-Shiley convexoconcave (BSCC) valves. MR images of the brain were obtained in 58 patients with prosthetic heart valves: 20 patients had BSCC valve replacements, and 38 had other types of heart valves. Two experienced neuroradiologists determined the presence or absence of susceptibility artifacts in a consensus reading. Artifacts were defined as characteristic black spots that were visible on T2*-weighted gradient-echo MR images. The statuses of the 20 explanted BSCC valves-specifically, whether they were intact or had an outlet strut fracture (OSF) or a single-leg fracture (SLF)-had been determined earlier. Number of artifacts seen at brain MR imaging was correlated with explanted valve status, and differences were analyzed with nonparametric statistical tests. Significantly more patients with BSCC valves (17 [85%] of 20 patients) than patients with other types of prosthetic valves (18 [47%] of 38 patients) had susceptibility artifacts at MR imaging (P =.005). BSCC valve OSFs were associated with a significantly higher number of artifacts than were intact BSCC valves (P =.01). No significant relationship between SLF and number of artifacts was observed. Susceptibility artifacts at brain MR imaging are not restricted to patients with BSCC valves. These artifacts can be seen on images obtained in patients with various other types of fractured and intact prosthetic heart valves. Copyright RSNA, 2004

  7. 9. BUTTERFLY VALVE CONTROL DIABLO POWERHOUSE. BUTTERFLY VALVES WERE MANUFACTURED ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    9. BUTTERFLY VALVE CONTROL DIABLO POWERHOUSE. BUTTERFLY VALVES WERE MANUFACTURED BY THE PELTON WATER WHEEL COMPANY IN 1931, 1989. - Skagit Power Development, Diablo Powerhouse, On Skagit River, 6.1 miles upstream from Newhalem, Newhalem, Whatcom County, WA

  8. Regional Systems of Care to Optimize Outcomes in Patients Undergoing Transcatheter Aortic Valve Replacement.

    PubMed

    Stub, Dion; Lauck, Sandra; Lee, May; Gao, Min; Humphries, Karin; Chan, Albert; Cheung, Anson; Cook, Richard; Della Siega, Anthony; Leipsic, Jonathon; Charania, Jay; Dvir, Danny; Latham, Tim; Polderman, Jopie; Robinson, Simon; Wong, Daniel; Thompson, Christopher R; Wood, David; Ye, Jian; Webb, John

    2015-12-28

    This study sought to describe the development of a multicenter, transcatheter aortic valve replacement program and regional systems of care intended to optimize coordinated, efficient, and appropriate delivery of this new therapy. Transcatheter aortic valve replacement (TAVR) has become an accepted treatment option for patients with severe aortic stenosis who are at high surgical risk. Regional systems of care have led to improvements in outcomes for patients undergoing intervention for myocardial infarction, cardiac arrest, and stroke. We implemented a regional system of care for patients undergoing TAVR in British Columbia, Canada. We describe a prospective observational cohort of 583 patients who underwent TAVR in British Columbia between 2012 and 2014. Regionalization of TAVR care in British Columbia refers to a centrally coordinated, funded, and evaluated program led by a medical director and a multidisciplinary advisory group that oversees planning, access to care, and quality of outcomes at the 4 provincial sites. Risk-stratified case selection for transfemoral TAVR is performed by heart teams at each site on the basis of consensus provincial indications. Referrals for lower volume and more complicated TAVR, including nontransfemoral access and valve-in-valve procedures, are concentrated at a single site. In-hospital and 30-day outcomes are reported. The median age was 83 years (interquartile range [IQR]: 78 to 87 years) and median STS score was 6% (IQR: 4% to 8%). Transfemoral access was performed in 499 (85.6%) cases and nontransfemoral in 84 (14.4%). Transcatheter valve-in-valve procedures in for failed bioprosthetic valves were performed in 43 patients (7.4%). A balloon-expandable valve was inserted in 386 (66.2%) and a self-expanding valve in 189 (32.4%). All-cause 30-day mortality was 3.5%. All-cause in-hospital mortality and disabling stroke occurred in 3.1% and 1.9%, respectively. Median length of stay was 3 days (IQR: 3 to 6 days), with 92.8% of

  9. Pregnancy-induced remodeling of heart valves.

    PubMed

    Pierlot, Caitlin M; Moeller, Andrew D; Lee, J Michael; Wells, Sarah M

    2015-11-01

    Recent studies have demonstrated remodeling of aortic and mitral valves leaflets under the volume loading and cardiac expansion of pregnancy. Those valves' leaflets enlarge with altered collagen fiber architecture, content, and cross-linking and biphasic changes (decreases, then increases) in extensibility during gestation. This study extends our analyses to right-sided valves, with additional compositional measurements for all valves. Valve leaflets were harvested from nonpregnant heifers and pregnant cows. Leaflet structure was characterized by leaflet dimensions, and ECM composition was determined using standard biochemical assays. Histological studies assessed changes in cellular and ECM components. Leaflet mechanical properties were assessed using equibiaxial mechanical testing. Collagen thermal stability and cross-linking were assessed using denaturation and hydrothermal isometric tension tests. Pulmonary and tricuspid leaflet areas increased during pregnancy by 35 and 55%, respectively. Leaflet thickness increased by 20% only in the pulmonary valve and largely in the fibrosa (30% thickening). Collagen crimp length was reduced in both the tricuspid (61%) and pulmonary (42%) valves, with loss of crimped area in the pulmonary valve. Thermomechanics showed decreased collagen thermal stability with surprisingly maintained cross-link maturity. The pulmonary leaflet exhibited the biphasic change in extensibility seen in left side valves, whereas the tricuspid leaflet mechanics remained largely unchanged throughout pregnancy. The tricuspid valve exhibits a remodeling response during pregnancy that is significantly diminished from the other three valves. All valves of the heart remodel in pregnancy in a manner distinct from cardiac pathology, with much similarity valve to valve, but with interesting valve-specific responses in the aortic and tricuspid valves. Copyright © 2015 the American Physiological Society.

  10. Bidirectional piston valve

    DOEpatents

    Fischer, Harry C.

    1977-01-01

    This invention is a reversing valve having an inlet, an outlet, and an inlet-outlet port. The valve is designed to respond to the introduction of relatively high-pressure fluid at its inlet or, alternatively, of lower-pressure fluid at its inlet-outlet port. The valve includes an axially slidable assembly which is spring-biased to a position where it isolates the inlet and connects the inlet-outlet port to the outlet. The admission of high-pressure fluid to the inlet displaces the slidable assembly to a position where the outlet is isolated and the inlet is connected to the inlet-outlet port. The valve is designed to minimize pressure drops and leakage. It is of a reliable and comparatively simple design.

  11. Transcatheter aortic valve implantation in patients with bicuspid aortic valve stenosis.

    PubMed

    Wijesinghe, Namal; Ye, Jian; Rodés-Cabau, Josep; Cheung, Anson; Velianou, James L; Natarajan, Madhu K; Dumont, Eric; Nietlispach, Fabian; Gurvitch, Ronen; Wood, David A; Tay, Edgar; Webb, John G

    2010-11-01

    We evaluated transcatheter aortic valve implantation (TAVI) in high-risk patients with bicuspid aortic valve (BAV) stenosis. TAVI shows promise in the treatment of severe stenosis of triscupid aortic valves, especially in high-risk patients. However, BAV stenosis has been considered a contraindication to TAVI. Eleven patients (age 52 to 90 years) with symptomatic severe BAV stenosis underwent TAVI at 3 Canadian tertiary hospitals between May 2006 and April 2010. All patients were considered high risk for surgical aortic valve replacement. Edwards-SAPIEN transcatheter heart valves (Edwards Lifesciences, Inc., Irvine, California) were used. Transfemoral or transapical access was selected, depending on the adequacy of femoral access. Access was transfemoral in 7 patients and transapical in 4 patients. There were no intraprocedural complications. Significant symptomatic and hemodynamic improvement was observed in 10 of 11 patients. Baseline aortic valve area of 0.65 ± 0.17 cm(2) and mean transaortic pressure gradient of 41 ± 22.4 mm Hg were improved to 1.45 ± 0.3 cm(2) and 13.4 ± 5.7 mm Hg, respectively. Two patients had moderate perivalvular leaks. At the 30-day follow-up there were 2 deaths due to multisystem failure in 2 transapical patients. In 1 patient an undersized, suboptimally positioned, unstable valve required late conversion to open surgery. TAVI in selected high-risk patients with severe BAV stenosis can be successfully performed with acceptable clinical outcomes but will require further evaluation. Copyright © 2010 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  12. Systolic Anterior Motion of the Mitral Valve after Mitral Valve Repair

    PubMed Central

    Sternik, Leonid; Zehr, Kenton J.

    2005-01-01

    Factors predisposing patients to systolic anterior motion of the mitral valve (SAM) with left ventricular outflow tract (LVOT) obstruction after mitral valve repair are the presence of a myxomatous mitral valve with redundant leaflets, a nondilated hyperdynamic left ventricle, and a short distance between the mitral valve coaptation point and the ventricular septum after repair. From December 1999 through March 2000, we used our surgical method in 6 patients with severely myxomatous regurgitant mitral valves who were at risk of developing SAM. Leaflets were markedly redundant in all 6. Left ventricular function was hyperdynamic in 4 patients and normal in 2. Triangular or quadrangular resection of the midportion of the posterior leaflet and posterior band annuloplasty were performed. To prevent SAM and LVOT obstruction, extra, posteriorly directed, mid-posterior-leaflet secondary chordae tendineae, which would otherwise have been resected, were transferred to the underside of the middle of the mid-anterior leaflet with a small piece of associated valve as an anchoring pledget. This kept the redundant anterior leaflet edge, which extended below the coaptation point, away from the LVOT. No post-repair SAM or LVOT obstruction was observed on intraoperative or discharge echocardiography. All patients had no or trivial residual mitral regurgitation. We conclude that extra chordae tendineae, when available, can be used in mitral valve repair to tether the redundant anterior leaflet and thus prevent it from flipping into the LVOT. This will theoretically prevent SAM and LVOT obstruction in patients with risk factors for SAM. PMID:15902821

  13. Update of transcatheter valve treatment

    PubMed Central

    Liu, Xian-bao; Wang, Jian-an

    2013-01-01

    Transcatheter valve implantation or repair has been a very promising approach for the treatment of valvular heart diseases since transcatheter aortic valve implantation (TAVI) was successfully performed in 2002. Great achievements have been made in this field (especially TAVI and transcatheter mitral valve repair—MitraClip system) in recent years. Evidence from clinical trials or registry studies has proved that transcatheter valve treatment for valvular heart diseases is safe and effective in surgical high-risk or inoperable patients. As the evidence accumulates, transcatheter valve treatment might be an alterative surgery for younger patients with surgically low or intermediate risk valvular heart diseases in the near future. In this paper, the updates on transcatheter valve treatment are reviewed. PMID:23897785

  14. Experimental study on the effect of an artificial cardiac valve on the left ventricular flow

    NASA Astrophysics Data System (ADS)

    Wang, JiangSheng; Gao, Qi; Wei, RunJie; Wang, JinJun

    2017-09-01

    The use of artificial valves to replace diseased human heart valves is currently the main solution to address the malfunctioning of these valves. However, the effect of artificial valves on the ventricular flow still needs to be understood in flow physics. The left ventricular flow downstream of a St. Jude Medical (SJM) bileaflet mechanical heart valve (BMHV), which is a widely implanted mechanical bileaflet valve, is investigated with time-resolved particle image velocimetry in the current work. A tilting-disk valve is installed on the aortic orifice to guarantee unidirectional flow. Several post-processing tools are applied to provide combined analyses of the physics involved in the ventricular flow. The triple jet pattern that is closely related to the characteristics of the bileaflet valve is discussed in detail from both Eulerian and Lagrangian views. The effects of large-scale vortices on the transportation of blood are revealed by the combined analysis of the tracking of Lagrangian coherent structures, the Eulerian monitoring of the shear stresses, and virtual dye visualization. It is found that the utilization of the SJM BMHV complicates the ventricular flow and could reduce the efficiency of blood transportation. In addition, the kinematics of the bileaflets is presented to explore the effects of flow structures on their motion. These combined analyses could elucidate the properties of SJM BMHV. Furthermore, they could provide new insights into the understanding of other complex blood flows.

  15. [Dopplerography of the large hepatic veins in the diagnosis of tricuspid valve insufficiency].

    PubMed

    Korytnikov, K I; Martyniuk, A D; Pustovit, L K

    1991-01-01

    During pulse dopplerography of the large hepatic veins in patients with tricuspid valve failure, the differences in the shape of the spectrum of Doppler's frequencies were revealed as dependent on cardiac rhythm. In sinus rhythm, the curve of the systolic flow is recordable beneath the baseline, in atrial fibrillation, over the baseline. In scanning of the large hepatic veins in patients with tricuspid valve failure, the shape of the curves of the spectrum of Doppler's frequencies coincides with the shape of the curves of liver pulsation. Tricuspid valve failure in sinus rhythm leads to a decrease of the maximum velocity of the systolic flow in the hepatic veins. There is a close correlation between the maximum velocity of the systolic flow of tricuspid regurgitation and the maximum velocity of the systolic flow in the large hepatic veins. Pulse dopplerography of the large hepatic veins is a safe enough method of the diagnosis of tricuspid valve failure and can be used in difficult cases when analysing the tricuspid blood flow from standard projections.

  16. "Bail out" procedures for malpositioning of aortic valve prosthesis (CoreValve).

    PubMed

    Vavouranakis, Manolis; Vrachatis, Dimitrios A; Toutouzas, Konstantinos P; Chrysohoou, Christina; Stefanadis, Christodoulos

    2010-11-05

    Two techniques for correcting malpositioning occurring during percutaneous aortic valve replacement (PAVR) with the CoreValve ReValving™ System are described in this article. The "Removing and Reinserting Technique" was used in 2 patients, in whom the prosthesis was positioned too high. The "Snare Technique" was used in 1 patient, in whom the prosthesis was implanted too low. In all patients the aortic valve prosthesis was successfully re-implanted. Copyright © 2009 Elsevier Ireland Ltd. All rights reserved.

  17. Passively actuated valve

    DOEpatents

    Modro, S. Michael; Ougouag, Abderrafi M.

    2005-09-20

    A passively actuated valve for isolating a high pressure zone from a low pressure zone and discontinuing the isolation when the pressure in the high pressure zone drops below a preset threshold. If the pressure in the high pressure zone drops below the preset threshold, the valve opens and allows flow from the high pressure zone to the low pressure zone. The valve remains open allowing pressure equalization and back-flow should a pressure inversion between the two pressure zone occur.

  18. "Ring pledget": a new concept for secure apex closure during transapical aortic valve implantation.

    PubMed

    Astarci, Parla; Glineur, David; Kefer, Joelle; Renkin, Jean; Vanoverschelde, Jean-Louis; El Khoury, Gebrine

    2010-03-01

    Transapical aortic valve implantation requires puncture of the left ventricle apex and insertion of a 32-French delivery sheath. A critical step in the procedure consists of secure closure of the ventricular apex. We describe 2 cases of apical rupture of 42 transapical aortic valve implantations. Furthermore, we describe the use of a newly designed single circular Teflon pledget that can help to avoid this complication. This pledget provides a more secure and uniform shrinkage of the entire apex to close the defect left by the delivery sheath.

  19. Mitral Valve Prolapse

    MedlinePlus

    ... valve syndrome . What happens during MVP? Watch an animation of mitral valve prolapse When the heart pumps ( ... our brochures Popular Articles 1 Understanding Blood Pressure Readings 2 Sodium and Salt 3 Heart Attack Symptoms ...

  20. Intraluminal valves: development, function and disease

    PubMed Central

    Geng, Xin; Cha, Boksik; Mahamud, Md. Riaj

    2017-01-01

    ABSTRACT The circulatory system consists of the heart, blood vessels and lymphatic vessels, which function in parallel to provide nutrients and remove waste from the body. Vascular function depends on valves, which regulate unidirectional fluid flow against gravitational and pressure gradients. Severe valve disorders can cause mortality and some are associated with severe morbidity. Although cardiac valve defects can be treated by valve replacement surgery, no treatment is currently available for valve disorders of the veins and lymphatics. Thus, a better understanding of valves, their development and the progression of valve disease is warranted. In the past decade, molecules that are important for vascular function in humans have been identified, with mouse studies also providing new insights into valve formation and function. Intriguing similarities have recently emerged between the different types of valves concerning their molecular identity, architecture and development. Shear stress generated by fluid flow has also been shown to regulate endothelial cell identity in valves. Here, we review our current understanding of valve development with an emphasis on its mechanobiology and significance to human health, and highlight unanswered questions and translational opportunities. PMID:29125824

  1. A finite element model on effects of impact load and cavitation on fatigue crack propagation in mechanical bileaflet aortic heart valve.

    PubMed

    Mohammadi, H; Klassen, R J; Wan, W-K

    2008-10-01

    Pyrolytic carbon mechanical heart valves (MHVs) are widely used to replace dysfunctional and failed heart valves. As the human heart beats around 40 million times per year, fatigue is the prime mechanism of mechanical failure. In this study, a finite element approach is implemented to develop a model for fatigue analysis of MHVs due to the impact force between the leaflet and the stent and cavitation in the aortic position. A two-step method to predict crack propagation in the leaflets of MHVs has been developed. Stress intensity factors (SIFs) are computed at a small initiated crack located on the leaflet edge (the worst case) using the boundary element method (BEM). Static analysis of the crack is performed to analyse the stress distribution around the front crack zone when the crack is opened; this is followed by a dynamic crack analysis to consider crack propagation using the finite element approach. Two factors are taken into account in the calculation of the SIFs: first, the effect of microjet formation due to cavitation in the vicinity of leaflets, resulting in water hammer pressure; second, the effect of the impact force between the leaflet and the stent of the MHVs, both in the closing phase. The critical initial crack length, the SIFs, the water hammer pressure, and the maximum jet velocity due to cavitation have been calculated. With an initial crack length of 35 microm, the fatigue life of the heart valve is greater than 60 years (i.e. about 2.2 x 10(9) cycles) and, with an initial crack length of 170 microm, the fatigue life of the heart valve would be around 2.5 years (i.e. about 9.1 x 10(7) cycles). For an initial crack length greater than 170 microm, there is catastrophic failure and fatigue cracking no longer occurs. A finite element model of fatigue analysis using Patran command language (PCL custom code) in MSC software can be used to evaluate the useful lifespan of MHVs. Similar methodologies can be extended to other medical devices under cyclic

  2. Valve gape behaviour of mussels (Mytilus edulis) exposed to dispersed crude oil as an environmental monitoring endpoint.

    PubMed

    Redmond, Kirsten J; Berry, Mark; Pampanin, Daniela M; Andersen, Odd Ketil

    2017-04-15

    Environmental monitoring requires cost-effective and efficient methods for detecting potential effects of pollution, and valve gape behaviour has been used with this purpose for a range of contaminants in freshwater and marine bivalves. The current study investigated the use of a new method for measuring valve behaviour responses in mussels (Mytilus edulis) exposed to dispersed crude oil (DCO). Results confirmed that valve gape is a sensitive parameter; at the high DCO concentration (0.25mgL -1 ) the mean valve gape was reduced from 49 to 31%, and mussels increased shell movement (measured as distance travelled) or spent more time closed to avoid contact with the oil. At the low DCO concentration (0.015mgL -1 ) the distance travelled parameter was the most sensitive endpoint. Results also demonstrated that valve gape behaviour is a valid endpoint when monitoring mussels for exposure to DCO. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Space Vehicle Valve System

    NASA Technical Reports Server (NTRS)

    Kelley, Anthony R. (Inventor); Lindner, Jeffrey L. (Inventor)

    2014-01-01

    The present invention is a space vehicle valve system which controls the internal pressure of a space vehicle and the flow rate of purged gases at a given internal pressure and aperture site. A plurality of quasi-unique variable dimension peaked valve structures cover the purge apertures on a space vehicle. Interchangeable sheet guards configured to cover valve apertures on the peaked valve structure contain a pressure-activated surface on the inner surface. Sheet guards move outwardly from the peaked valve structure when in structural contact with a purge gas stream flowing through the apertures on the space vehicle. Changing the properties of the sheet guards changes the response of the sheet guards at a given internal pressure, providing control of the flow rate at a given aperture site.

  4. All metal valve structure for gas systems

    DOEpatents

    Baker, Ray W.; Pawlak, Donald A.; Ramey, Alford J.

    1984-11-13

    A valve assembly with a resilient metal seat member is disclosed for providing a gas-tight seal in a gas handling system. The valve assembly also includes a valve element for sealing against the valve seat member; and an actuating means for operating the valve element. The valve seat member is a one-piece stainless steel ring having a central valve port and peripheral mounting flange, and an annular corrugation in between. A groove between the first and second ridges serves as a flexure zone during operation of the valve member and thus provides the seating pressure between the inner ridge or valve seat and the valve element. The outer annular ridge has a diameter less than said valve element to limit the seating motion of the valve element, preventing non-elastic deformation of the seat member.

  5. All-metal valve structure for gas systems

    DOEpatents

    Baker, R.W.; Pawlak, D.A.; Ramey, A.J.

    1982-06-10

    A valve assembly with a resilient metal seat member is disclosed for providing a gas-tight seal in a gas handling system. The valve assembly also includes a valve element for sealing against the valve seat member; and an actuating means for operating the valve element. The valve seat member is a one-piece stainless steel ring having a central valve port and peripheral mounting flange, and an annular corrugation in between. A groove between the first and second ridges serves as a flexure zone during operation of the valve member and thus provides the seating pressure between the inner ridge or valve seat and the valve element. The outer annular ridge has a diameter less than said valve element to limit the seating motion of the valve element, preventing non-elastic deformation of the seat member.

  6. Liquid rocket valve assemblies

    NASA Technical Reports Server (NTRS)

    1973-01-01

    The design and operating characteristics of valve assemblies used in liquid propellant rocket engines are discussed. The subjects considered are as follows: (1) valve selection parameters, (2) major design aspects, (3) design integration of valve subassemblies, and (4) assembly of components and functional tests. Information is provided on engine, stage, and spacecraft checkout procedures.

  7. Aerosol penetration through respirator exhalation valves.

    PubMed

    Bellin, P; Hinds, W C

    1990-10-01

    Exhalation valves are a critical component of industrial respirators. They are designed to permit minimal inward leakage of air contaminants during inhalation and provide low resistance during exhalation. Under normal conditions, penetration of aerosol through exhalation valves is minimal. The exhalation valve is, however, a vulnerable component of a respirator and under actual working conditions may become dirty or damaged to the point of causing significant leakage. Aerosol penetration was measured for normal exhalation valves and valves compromised by paint or fine copper wires on the valve seat. Penetration increased with increasing wire diameter. A wire 250 microns in diameter allowed greater than 1% penetration into the mask cavity. Dirt or paint accumulated on the exhalation valve allowed a similar level of penetration. Work rate had little effect on observed penetration. Penetration decreased significantly with increasing aerosol particle size. The amount of material on the valve or valve seat necessary for significant (greater than 0.5%) inward leakage in a half-mask respirator could be readily observed by careful inspection of the exhalation valve and its seat in good lighting conditions.

  8. Spool-Valve Pressure-Difference Regulator

    NASA Technical Reports Server (NTRS)

    Grasso, A. P.

    1983-01-01

    Valves maintain preset pressure difference between gas flows. Two spool valves connected by shaft move back and forth in response to changes in pressure in oxygen and hydrogen chambers. Spool-valve assembly acts to restore pressures to preset difference. By eliminating diaphragms, pressure exerted directly on external end of spool valve; however, forces and therefore sensitivity of assembly are reduced.

  9. Percutaneous closure of acute aorto-right ventricular fistula following transcatheter bicuspid aortic valve replacement.

    PubMed

    Nakamura, Kenta; Passeri, Jonathan J; Inglessis-Azuaje, Ignacio

    2017-07-01

    We report a case of acute aorto-right ventricular fistula following transcatheter bicuspid aortic valve replacement and subsequent percutaneous closure. The diagnosis and treatment of this rare complication is illustrated through multi-modality imaging. We hypothesize that the patient's heavily calcified bicuspid aortic valve anatomy led to asymmetric deployment of the transcatheter aortic valve replacement (TAVR) prosthesis, traumatizing the right sinus of Valsalva at the distal edge of the TAVR stent and ultimately fistulized to the right ventricle. The patient acutely decompensated with heart failure five days after TAVR and underwent emergent intervention. The aorto-right ventricular fistula was closed using an 18-mm septal occluder device with marked clinical recovery. Transcatheter closure is a viable treatment option for acute aorto-right ventricular fistula. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  10. Valve-in-valve using an Edwards Sapien XT into a JenaValve in a patient with a low originating left coronary artery and a heavily calcified aorta.

    PubMed

    Fujita, Buntaro; Scholtz, Smita; Ensminger, Stephan

    2016-04-01

    Coronary obstruction during transcatheter aortic valve implantation is a potentially life-threatening complication. Most of the widely used transcatheter heart valves require a certain distance between the basal aortic annular plane and the origins of the coronary arteries. We report the case of a successful valve-in-valve procedure with an Edwards SAPIEN XT valve into a JenaValve as a bail-out procedure in a patient with a low originating left coronary artery and a heavily calcified aorta. © 2015 Wiley Periodicals, Inc.

  11. Infective endocarditis causing mitral valve stenosis - a rare but deadly complication: a case report.

    PubMed

    Hart, Michael A; Shroff, Gautam R

    2017-02-17

    Infective endocarditis rarely causes mitral valve stenosis. When present, it has the potential to cause severe hemodynamic decompensation and death. There are only 15 reported cases in the literature of mitral prosthetic valve bacterial endocarditis causing stenosis by obstruction. This case is even more unusual due to the mechanism by which functional mitral stenosis occurred. We report a case of a 23-year-old white woman with a history of intravenous drug abuse who presented with acute heart failure. Transthoracic echocardiography failed to show valvular vegetation, but high clinical suspicion led to transesophageal imaging that demonstrated infiltrative prosthetic valve endocarditis causing severe mitral stenosis. Despite extensive efforts from a multidisciplinary team, she died as a result of her critical illness. The discussion of this case highlights endocarditis physiology, the notable absence of stenosis in modified Duke criteria, and the utility of transesophageal echocardiography in clinching a diagnosis. It advances our knowledge of how endocarditis manifests, and serves as a valuable lesson for clinicians treating similar patients who present with stenosis but no regurgitation on transthoracic imaging, as a decision to forego a transesophageal echocardiography could cause this serious complication of endocarditis to be missed.

  12. Bioprinting a cardiac valve.

    PubMed

    Jana, Soumen; Lerman, Amir

    2015-12-01

    Heart valve tissue engineering could be a possible solution for the limitations of mechanical and biological prostheses, which are commonly used for heart valve replacement. In tissue engineering, cells are seeded into a 3-dimensional platform, termed the scaffold, to make the engineered tissue construct. However, mimicking the mechanical and spatial heterogeneity of a heart valve structure in a fabricated scaffold with uniform cell distribution is daunting when approached conventionally. Bioprinting is an emerging technique that can produce biological products containing matrix and cells, together or separately with morphological, structural and mechanical diversity. This advance increases the possibility of fabricating the structure of a heart valve in vitro and using it as a functional tissue construct for implantation. This review describes the use of bioprinting technology in heart valve tissue engineering. Copyright © 2015 Elsevier Inc. All rights reserved.

  13. Fluid Dynamic Characterization of a Polymeric Heart Valve Prototype (Poli-Valve) tested under Continuous and Pulsatile Flow Conditions

    PubMed Central

    De Gaetano, Francesco; Serrani, Marta; Bagnoli, Paola; Brubert, Jacob; Stasiak, Joanna; Moggridge, Geoff D.; Costantino, Maria Laura

    2016-01-01

    Introduction Only mechanical and biological heart valve prostheses are currently commercially available. The former show longer durability but require anticoagulant therapy, the latter display better fluid dynamic behaviour but do not have adequate durability. New Polymeric Heart Valves (PHVs) could potentially combine the haemodynamic properties of biological valves with the durability of mechanical valves. This work presents a hydrodynamic evaluation of two groups of newly developed supra-annular tri-leaflet prosthetic heart valves made from styrenic block copolymers (SBC): Poli-Valves. Methods Two types of Poli-Valves made of SBC differing in polystyrene fraction content were tested under continuous and pulsatile flow conditions as prescribed by ISO 5840 Standard. An ad - hoc designed pulse duplicator allowed the valve prototypes to be tested at different flow rates and frequencies. Pressure and flow were recorded; pressure drops, effective orifice area (EOA), and regurgitant volume were computed to assess the valve’s behaviour. Results Both types Poli-Valves met the minimum requirements in terms of regurgitation and EOA as specified by ISO 5840 Standard. Results were compared with five mechanical heart valves (MHVs) and five tissue heart valves (THVs), currently available on the market. Conclusion Based on these results, polymeric heart valves based on styrenic block copolymers, as Poli-Valves are, can be considered as promising alternative for heart valve replacement in near future. PMID:26689146

  14. Fluid dynamic characterization of a polymeric heart valve prototype (Poli-Valve) tested under continuous and pulsatile flow conditions.

    PubMed

    De Gaetano, Francesco; Serrani, Marta; Bagnoli, Paola; Brubert, Jacob; Stasiak, Joanna; Moggridge, Geoff D; Costantino, Maria Laura

    2015-11-01

    Only mechanical and biological heart valve prostheses are currently commercially available. The former show longer durability but require anticoagulant therapy; the latter display better fluid dynamic behavior but do not have adequate durability. New Polymeric Heart Valves (PHVs) could potentially combine the hemodynamic properties of biological valves with the durability of mechanical valves. This work presents a hydrodynamic evaluation of 2 groups of newly developed supra-annular, trileaflet prosthetic heart valves made from styrenic block copolymers (SBC): Poli-Valves. 2 types of Poli-Valves made of SBC and differing in polystyrene fraction content were tested under continuous and pulsatile flow conditions as prescribed by ISO 5840 Standard. A pulse duplicator designed ad hoc allowed the valve prototypes to be tested at different flow rates and frequencies. Pressure and flow were recorded; pressure drops, effective orifice area (EOA), and regurgitant volume were computed to assess the behavior of the valve. Both types of Poli-Valves met the minimum requirements in terms of regurgitation and EOA as specified by the ISO 5840 Standard. Results were compared with 5 mechanical heart valves (MHVs) and 5 tissue heart valves (THVs), currently available on the market. Based on these results, PHVs based on styrenic block copolymers, as are Poli-Valves, can be considered a promising alternative for heart valve replacement in the near future.

  15. Low energy high pressure miniature screw valve

    DOEpatents

    Fischer, Gary J [Sandia Park, NM; Spletzer, Barry L [Albuquerque, NM

    2006-12-12

    A low energy high pressure screw valve having a valve body having an upper portion and a lower portion, said lower portion of said valve body defining an inlet flow passage and an outlet flow passage traversing said valve body to a valve seat, said upper portion of said valve body defining a cavity at said valve seat, a diaphragm restricting flow between said upper portion of said valve body and said lower portion, said diaphragm capable of engaging said valve seat to restrict fluid communication between said inlet passage and said outlet passage, a plunger within said cavity supporting said diaphragm, said plunger being capable of engaging said diaphragm with said valve seat at said inlet and outlet fluid passages, said plunger being in point contact with a drive screw having threads engaged with opposing threads within said upper portion of said valve body such engagement allowing motion of said drive screw within said valve body.

  16. Mitral valve surgery - minimally invasive

    MedlinePlus

    ... flow. Your valve has developed an infection (infectious endocarditis). You have severe mitral valve prolapse that is ... function. Damage to your heart valve from infection (endocarditis). A minimally invasive procedure has many benefits. There ...

  17. 49 CFR 195.116 - Valves.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... PIPELINE Design Requirements § 195.116 Valves. Each valve installed in a pipeline system must comply with the following: (a) The valve must be of a sound engineering design. (b) Materials subject to the...

  18. 100. INTERIOR OF SKID 9A: VENT VALVE AND RELIEF VALVE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    100. INTERIOR OF SKID 9A: VENT VALVE AND RELIEF VALVE FOR RAPID-LOAD LIQUID OXYGEN TANK - Vandenberg Air Force Base, Space Launch Complex 3, Launch Pad 3 East, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

  19. Thermostatic Valves Containing Silicone-Oil Actuators

    NASA Technical Reports Server (NTRS)

    Bhandari, Pradeep; Birur, Gajanana C.; Bame, David P.; Karlmann, Paul B.; Prina, Mauro; Young, William; Fisher, Richard

    2009-01-01

    Flow-splitting and flow-mixing thermally actuated spool valves have been developed for controlling flows of a heat-transfer fluid in a temperature-regulation system aboard the Mars Science Laboratory (MSL) rover. Valves like these could also be useful in terrestrial temperature-regulation systems, including automobile air-conditioning systems and general refrigeration systems. These valves are required to provide smoother actuation over a wider temperature range than the flow-splitting, thermally actuated spool valves used in the Mars Explorer Rover (MER). Also, whereas the MER valves are unstable (tending to oscillate) in certain transition temperature ranges, these valves are required not to oscillate. The MER valves are actuated by thermal expansion of a wax against spring-loaded piston rods (as in common automotive thermostats). The MSL valves contain similar actuators that utilize thermal expansion of a silicone oil, because silicone-oil actuators were found to afford greater and more nearly linear displacements, needed for smoother actuation, over the required wider temperature range. The MSL valves also feature improved spool designs that reflect greater understanding of fluid dynamics, consideration of pressure drops in valves, and a requirement for balancing of pressures in different flow branches.

  20. Automated Temperature Control with Adjusting Outlet Valve of Fuel in the Process of Cooking Palm Sugar

    NASA Astrophysics Data System (ADS)

    Aripin, H.; Hiron, Nurul; Priatna, Edvin; Busaeri, Nundang; Andang, Asep; Suhartono; Sabchevski, Svilen

    2018-04-01

    In this paper, a real-time temperature control system for coconut sugar cooking is presented. It is based on a thermocouple temperature sensor. The temperature in the closed evaporator is used as a control variable of the DC servo control system for opening and closing of a valve embedded in a gas burner. The output power level, which is necessary in order to reach the target temperature is controlled by the microcontroller ATMega328P. A circuit module for control of the valve and temperature sensors as well as software for data acquisition have been implemented. The test results show that the system properly stabilizes the temperature in the closed evaporator for coconut sugar cooking in the range from room temperature to 110°C. A set point can be reached and held with an accuracy of ±0.75°C at a temperature of 110°C for 60 minutes.