Aortic valve prosthesis-patient mismatch and exercise capacity in adult patients with congenital heart disease

NARCIS (Netherlands)

van Slooten, Ymkje J.; van Melle, Joost P.; Freling, Hendrik G.; Bouma, Berto J.; van Dijk, Arie Pj; Jongbloed, Monique Rm; Post, Martijn C.; Sieswerda, Gertjan T.; Huis In 't Veld, Anna; Ebels, Tjark; Voors, Adriaan A.; Pieper, Petronella G.

2016-01-01

To report the prevalence of aortic valve prosthesis-patient mismatch (PPM) in an adult population with congenital heart disease (CHD) and its impact on exercise capacity. Adults with congenital heart disease (ACHD) with a history of aortic valve replacement may outgrow their prosthesis later in

[Directions for reoperation of patients with Björk-Shiley convexo-concave valve prosthesis, based on long-term experience].

Science.gov (United States)

Yamaki, F; Nakano, K; Endo, M; Hashimoto, A; Koyanagi, H

1994-02-01

Although a high incidence of strut fracture of the Björk-Shiley convexo-concave (C-C) valve prosthesis has been reported, it is still controversial whether the prosthesis functioning normally should be replaced electively. To clarify our policy for this issue, we reviewed 28 patients who had undergone mitral valve replacement with a C-C valve prosthesis, and evaluated long-term results according to STS guidelines. The incidence of valve-related complications expressed as % patient-year were; structural deterioration 0.30, nonstructural dysfunction 0.30, thromboembolism 1.20. There were no thrombosed valves, anticoagulant-related hemorrhage or prosthetic valve endocarditis. The actuarial free rate after valve replacement with the C-C at 10 years, constructed by the Kaplan-Meier method, were compared with those with St. Jude Medical (SJM) valve prosthesis. (1) Actuarial survival: 77.9 vs 87.3 (NS), (2) Reoperation-free: 91.6 vs 98.0 (p valve-related complications: 71.2 vs 77.7 (NS). The long-term results with the C-C were compatible to those with a SJM valve prosthesis. However, if a strut fracture occurs, it is very difficult to save the patient's life. The hospital mortality of re-replacement of valve prosthesis during the last 10 years, at our institute, was 2.6%, which is almost equal to the cumulative risk of strut fracture of the C-C valve after 10 years (3.0%).(ABSTRACT TRUNCATED AT 250 WORDS)

[Lessons from a heart valve prosthesis controversy].

Science.gov (United States)

Vandenbroucke, J P; Grobbee, D E

1998-07-18

Two lessons are to be learnt from the Björk-Shiley heart valve prosthesis tragedy. In the first place pharmacoepidemiologic studies are seriously hampered by recent privacy legislation. Individual patients carrying such a prosthesis cannot be traced and advised as to their health risks any more, because their legal autonomy has to be respected. This is clearly not to their advantage. In the second place the atmosphere of marketing and litigation and the increasing dependency of researchers on money from sources with conflicting interests is not conducive to a well-informed and balanced judgement of the epidemiological evidence of safety and efficacy of medical treatments.

Worcester 1 Inch Solenoid-Actuated Gas-Operated VPS System Ball Valve

International Nuclear Information System (INIS)

VAN KATWIJK, C.

2000-01-01

1 inch Gas-operated full-port ball valve incorporates a solenoid and limit switches as integral parts of the actuator. The valve is normally open and fails safe to the closed position. The associated valve position switch is class GS

Patient-prosthesis mismatch and left ventricular remodelling after implantation of Shelhigh SuperStentless aortic valve prostheses.

Science.gov (United States)

Germing, A; Lindstaedt, M; Holt, S; Reber, D; Mügge, A; Laczkovics, A; Fritz, M

2008-08-01

Aortic valve replacement is a standard procedure for the treatment of severe aortic valve stenosis. Due to lower flow velocities stentless valves are associated with a more effective regression of left ventricular hypertrophy in comparison to stented valves. However, mismatch between body surface area and valve size supports unfavourable hemodynamic results. The aim of the study was to analyze hemodynamic parameters by echocardiography after implantation of the Shelhigh SuperStentless bioprosthesis and to analyze the occurrence of patient-prosthesis mismatch and left ventricular remodelling in this specific valve type. A total of 20 patients with severe aortic stenosis underwent implantation of a Shelhigh Super Stentless prosthesis. Clinical and echocardiographic assessment was done prior to, immediate after and six months after surgery. All surgical procedures were successful, no surgery-related complication was documented perioperatively. One patient died after development of multiorgan failure. Echocardiography during the first eight days after surgery showed mean gradients of 16 mmHg, mean valve orifice areas of 1.8 cm(2) and indexed effective orifice areas at 0.95 cm(2)/m(2). Six-months follow-up data were obtained in 19/20 patients. There were no relevant changes in echocardiographic hemodynamic findings at the time of follow-up measurements. Significant regression of left ventricular hypertrophy was shown (P=0.0088). A patient-prosthesis mismatch occurred in one patient (0.54 cm(2)/m(2)). No recurrent symptoms were documented. Patient-prosthesis mismatch after implantation of SuperStentless Shelhigh prosthesis is rare. A significant regression of left ventricular hypertrophy could be shown after six months. Hemodynamic valve function assessed by echocardiography may be predicted early after surgery.

Clinical predictors of prosthesis-patient mismatch after aortic valve replacement for aortic stenosis

Directory of Open Access Journals (Sweden)

Luis M Astudillo

2012-01-01

Full Text Available OBJECTIVE: We sought to ascertain predictors of Patient Prosthesis Mismatch, an independent predictor of mortality, in patients with aortic stenosis using bioprosthetic valves. METHOD: We analyzed 2,107 sequential surgeries. Patient Prosthesis Mismatch was calculated using the effective orifice area of the prosthesis divided by the patient's body surface area. We defined nonsignificant, moderate, and severe Patient Prosthesis Mismatch as effective orifice area indexes of .0.85 cm²/m, 0.85-0.66 cm²/m², and <0.65 cm²/m², respectively. RESULTS: A total of 311 bioprosthetic patients were identified. The incidence of nonsignificant, moderate, and severe Patient Prosthesis Mismatch was 41%, 42, and 16%, respectively. Severe Patient Prosthesis Mismatch was significantly more prevalent in females (82%. In severe Patient Prosthesis Mismatch, the perfusion and the crossclamp times were considerably lower when compared with nonsignificant Patient Prosthesis Mismatch and moderate Patient Prosthesis Mismatch. Patients with severe Patient Prosthesis Mismatch had a significantly higher likelihood of spending time in the intensive care unit and a significantly longer length of stay in the hospital. Body surface area was not different in severe Patient Prosthesis Mismatch when compared with nonsignificant Patient Prosthesis Mismatch. In-hospital mortality in patients with nonsignificant, moderate, and severe Patient Prosthesis Mismatch was 2.3%, 6.1%, and 8%, respectively. Minimally invasive surgery was significantly associated with moderate Patient Prosthesis Mismatch in 49% of the patients, but not with severe Patient Prosthesis Mismatch. CONCLUSION: Severe Patient Prosthesis Mismatch is more common in females, but not in those with minimal available body surface area. Though operative times were shorter in these patients, intensive care unit and hospital lengths of stay were longer. Surgeons and cardiologists should be cognizant of these clinical

Percutaneous implantation of the first repositionable aortic valve prosthesis in a patient with severe aortic stenosis.

Science.gov (United States)

Buellesfeld, Lutz; Gerckens, Ulrich; Grube, Eberhard

2008-04-01

Percutaneous aortic valve replacement is a new less-invasive alternative for high-risk surgical candidates with aortic stenosis. However, the clinical experience is still limited, and the currently available 'first-generation devices' revealed technical shortcomings, such as lack of repositionability and presence of paravalvular leakages. We report the first-in-man experience with the new self-expanding Lotus Valve prosthesis composed of a nitinol frame with implemented bovine pericardial leaflets which is designed to address these issues, being repositionable and covered by a flexible membrane to seal paravalvular gaps. We implanted this prosthesis in a 93-year old patient presenting with severe symptomatic aortic stenosis (valve area: 0.6 cm(2)). Surgical valve replacement had been declined due to comorbidities. We used a retrograde approach for insertion of the 21-French Lotus catheter loaded with the valve prosthesis via surgical cut-down to the external iliac artery. Positioning of the valve was guided by transesophageal echo and supra-aortic angiograms. The prosthesis was successfully inserted and deployed within the calcified native valve. Echocardiography immediately after device deployment showed a significant reduction of the transaortic mean pressure gradient (32 to 9 mmHg; final valve area 1.7 cm(2)) without evidence of residual aortic regurgitation. The postprocedural clinical status improved from NYHA-IV to NYHA-II. These results remained unchanged up to the 3 month follow-up. Successful percutaneous aortic valve replacement can be performed using the new self-expanding and repositionable Lotus valve for treatment of high-risk patients with aortic valve stenosis. Further studies are mandatory to assess device safety and efficacy in larger patient populations. Copyright 2008 Wiley-Liss, Inc.

Patient-prosthesis mismatch and risk of structural valve deterioration in patients undergoing bioprosthetic aortic valve implantation

OpenAIRE

Urso, Stefano

2015-01-01

Tesis doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Medicina, Departamento de Medicina. Fecha de lectura: 15-06-2015 Patient-prosthesis mismatch (PPM) has been identified as a risk factor for mortality after aortic valve replacement. Recently PPM has been also reported to increase the risk of structural valve degeneration (SVD) in patients receiving a bioprosthetic aortic valve. The aim of the present study was to compare the incidence of reoperation because of S...

First report on a human percutaneous transluminal implantation of a self-expanding valve prosthesis for interventional treatment of aortic valve stenosis.

Science.gov (United States)

Grube, Eberhard; Laborde, Jean C; Zickmann, Bernfried; Gerckens, Ulrich; Felderhoff, Thomas; Sauren, Barthel; Bootsveld, Andreas; Buellesfeld, Lutz; Iversen, Stein

2005-12-01

Percutaneous aortic valve replacement is a new technology for the treatment of patients with significant aortic valve stenosis. We present the first report on a human implantation of a self-expanding aortic valve prosthesis, which is composed of three bovine pericardial leaflets inserted within a self-expanding nitinol stent. The 73-year-old woman presented with severe symptomatic aortic valve stenosis (mean transvalvular gradient of 45 mmHg; valve area of 0.7 cm2). Surgical valve replacement had been declined for the patient because of comorbidities, including previous bypass surgery. A retrograde approach via the common iliac artery was used for valve deployment. The contralateral femoral vessels were used for a temporary extracorporal circulation, unloading the left ventricle during the actual stent expansion. Clinical, hemodynamic, and echocardiographic outcomes were assessed serially during the procedure. Clinical and echocardiographic follow-up at day 1, 2, and 14 post procedure was performed to evaluate the short-term outcome. The prosthesis was successfully deployed within the native aortic valve, with accurate and stable positioning and with no impairment of the coronary artery or vein graft blood flow. 2D and doppler echo immediately after device deployment showed a significant reduction in transaortic mean pressure gradient (from 45 to 8 mmHg) without evidence of aortic or mitral valve insufficiency. The clinical status has then significantly improved. These results remained unchanged up to the day 14 follow-up. This case report demonstrates a successful percutaneous implantation of a self-expanding aortic valve prosthesis with remarkable functional and clinical improvements in the acute and short-term outcome. Copyright (c) 2005 Wiley-Liss, Inc.

Functional property of the cardiac valve prosthesis evaluated in vivo by cine-radiography

International Nuclear Information System (INIS)

Murakoshi, Sadaaki

1986-01-01

Functional property of the convexo-concave Bjoerk-Shiley cardiac valve prosthesis implanted in the mitral position of 21 patients was investigated by integrated cine-radiography repeated for a long term after operation. The maximum opening angle of the tilting disc was 58 ± 2 deg, and was not affected by atrial fibrillation nor by tachycardia up to 160 bpm. There was no change in the maximum opening angle of the disc observed during follow-up period. Good correlation between shortning of the disc opening time and increase in pulse rate suggests excellent adaptation of this prosthesis for tachycardia induced by exercise or electric pacing. However, atrial fibrillation causes time delay in disc closure immediately after prolonged R-R interval. Disc rotation alleviating disc wear was observed in all the patients whether it moves slow or quick. Dysfunction of the disc opening can be readily determined not only by measuring the maximum disc opening angle, but also by observing the characteristic movement indicated in this study. It is concluded from these results that clinical apprication for the convexo-concave Bjoerk-Shiley valve prosthesis is appropriate and cine-radiography is an useful non-invasive examination of cardiac valve prosthesis for long follow-up period. (author)

Functional property of the cardiac valve prosthesis evaluated in vivo by cine-radiography

Energy Technology Data Exchange (ETDEWEB)

Murakoshi, Sadaaki

1986-07-01

Functional property of the convexo-concave Bjoerk-Shiley cardiac valve prosthesis implanted in the mitral position of 21 patients was investigated by integrated cine-radiography repeated for a long term after operation. The maximum opening angle of the tilting disc was 58 +- 2 deg, and was not affected by atrial fibrillation nor by tachycardia up to 160 bpm. There was no change in the maximum opening angle of the disc observed during follow-up period. Good correlation between shortning of the disc opening time and increase in pulse rate suggests excellent adaptation of this prosthesis for tachycardia induced by exercise or electric pacing. However, atrial fibrillation causes time delay in disc closure immediately after prolonged R-R interval. Disc rotation alleviating disc wear was observed in all the patients whether it moves slow or quick. Dysfunction of the disc opening can be readily determined not only by measuring the maximum disc opening angle, but also by observing the characteristic movement indicated in this study. It is concluded from these results that clinical apprication for the convexo-concave Bjoerk-Shiley valve prosthesis is appropriate and cine-radiography is an useful non-invasive examination of cardiac valve prosthesis for long follow-up period.

CLINICAL AND FUNCTIONAL ASSESSMENT OF THE BIOLOGICAL PROSTHESIS “ASPIRE” FOR SURGICAL CORRECTION OF MITRAL VALVE DISEASE

Directory of Open Access Journals (Sweden)

S. G. Esin

2015-01-01

Full Text Available Aim: To assess clinical and functional efficacy of implanted biological prosthesis “ASPIRE” (manufactured by Vascutek for correction of mitral valve disease.Materials and methods: From October 2008 to December 2013, biological prostheses “ASPIRE” (Vascutek were implanted to 34 patients with mitral valve disease (mean age 63.59 ± 4.96 years, 79.4% female. From these, 24 patients had mitral stenosis and 10 patients had mitral insufficiency. 73.5% of all patients had heart failure Strazhesko-Vasilenko IIA grade and 85.3% of patients had chronic heart failure NYHA III. Isolated mitral valve replacement was performed only in 8 (23.5% of patients. In 22 (64.7% of cases mitral valve replacement was combined with tricuspid valvuloplasty in various modifications. Duration of cardiopulmonary bypass and of aortic clamping was 88.09 ± 25.95 and 65.68 ± 25.51 minutes, respectively. Before and after surgery all patients underwent echocardiographic assessment and clinical assessment of their general status.Results: In-hospital mortality was 5.88% (n = 2 and was related to multiorgan failure in the early postoperative period. All 32 (94.12% surviving patients improved with decrease or complete disappearance of heart failure. Postoperative complications were typical for cardiac surgery. There were no episodes of embolism, structural dysfunction, thrombosis of the prosthesis and endocarditis of the prosthesis in the early postoperative period. Pressure gradients across prosthetic valves were not high and corresponded to good clinical and hemodynamic results in the early postoperative period.Conclusion: Taking into account good immediate results of mitral valve replacement, as well as no need in lifelong anticoagulation in patients with multiple concomitant disorders, implantation of the biological prosthesis “ASPIRE” (Vascutek could become a procedure of choice for correction of valve abnormalities in patients above 65 years. For more comprehensive

Aortic valve prosthesis-patient mismatch and exercise capacity in adult patients with congenital heart disease.

Science.gov (United States)

van Slooten, Ymkje J; van Melle, Joost P; Freling, Hendrik G; Bouma, Berto J; van Dijk, Arie Pj; Jongbloed, Monique Rm; Post, Martijn C; Sieswerda, Gertjan T; Huis In 't Veld, Anna; Ebels, Tjark; Voors, Adriaan A; Pieper, Petronella G

2016-01-01

To report the prevalence of aortic valve prosthesis-patient mismatch (PPM) in an adult population with congenital heart disease (CHD) and its impact on exercise capacity. Adults with congenital heart disease (ACHD) with a history of aortic valve replacement may outgrow their prosthesis later in life. However, the prevalence and clinical consequences of aortic PPM in ACHD are presently unknown. From the national Dutch Congenital Corvitia (CONCOR) registry, we identified 207 ACHD with an aortic valve prosthesis for this cross-sectional cohort study. Severe PPM was defined as an indexed effective orifice area ≤0.65 cm2/m2 and moderate PPM as an indexed orifice area ≤0.85 cm2/m2 measured using echocardiography. Exercise capacity was reported as percentage of predicted exercise capacity (PPEC). Of the 207 patients, 68% was male, 71% had a mechanical prosthesis and mean age at inclusion was 43.9 years ±11.4. The prevalence of PPM was 42%, comprising 23% severe PPM and 19% moderate PPM. Prevalence of PPM was higher in patients with mechanical prostheses (pHeart Association (NYHA) class remained stable in most patients. PPM showed no significant effect on death or hospitalisation during follow-up (p=0.218). In this study we report a high prevalence (42%) of PPM in ACHD with an aortic valve prosthesis and an independent association of PPM with diminished exercise capacity. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Wear-testing of a temporomandibular joint prosthesis : UHMWPE and PTFE against a metal ball, in water and in serum

NARCIS (Netherlands)

Van Loon, JP; Verkerke, GJ; de Bont, LGM; Liem, RSB

For a temporomandibular joint prosthesis, an estimation of the wear rate was needed, prior to patient application. Therefore, we determined the in vitro wear rate of the ball-socket articulation of this prosthesis, consisting of a metal head and an ultra-high molecular weight polyethylene (UHMWPE)

Prosthesis-patient mismatch after transcatheter aortic valve implantation using the Edwards SAPIEN™ prosthesis.

Science.gov (United States)

Van Linden, Arnaud; Kempfert, Jörg; Blumenstein, Johannes; Rastan, Ardawan; Holzhey, David; Lehmann, Sven; Mohr, Friedrich W; Walther, Thomas

2013-08-01

Prosthesis-patient mismatch (PPM) is defined as a too small effective orifice area (EOA) of the prosthetic valve in relation to the patient's body size and has been documented to be related to adverse outcomes after conventional aortic valve replacement (AVR). Aim of this study was to analyze the incidence of PPM after transcatheter aortic valve implantation (T-AVI) using the Edwards SAPIEN prosthesis and its relation to postoperative outcome. 200 consecutive high-risk patients underwent transapical aortic valve implantation (TA-AVI) between February 2006 and January 2009 and fulfilled 1 year follow-up were included. Severe PPM was defined as indexed EOA (EOAi) <0.65 cm2/m2 and moderate PPM as EOAi = 0.65-0.85 cm2/m2, EOA was calculated from transthoracic echocardiographic (TTE) measurements using the continuity equation. Total 112 patients with sufficient postoperative TTE image quality formed the study group. EOAi increased from 0.3 ± 0.1 cm2/m2 (preoperatively) to 1.1 ± 0.4 cm2/m2 after TA-AVI (p < 0.001). According to the standard definitions, PPM was seen in 38.4% of the patients and 9.8% presented with severe PPM. The occurrence of PPM had neither an effect on clinical outcome in terms of NYHA class nor on survival. Patients with PPM had significantly higher postoperative transprosthetic gradients (mean gradient 10.4 ± 4.1 versus 7.1 ± 3.0 mm Hg, p < 0.001). Based on the in vitro EOA data obtained from pulse duplicator measurements, however, none of the patients was judged to have PPM. Transcatheter AVI provides good antegrade hemodynamic function and EOAi improves significantly. According to standardized evaluations PPM occurs after TA-AVI, but it is not associated with adverse outcomes. Thus use of the continuity equation may not adequately reflect the situation after T-AVI or the current definition of PPM is not suitable for T-AVI prostheses. Georg Thieme Verlag KG Stuttgart · New York.

[Phonomechanocardiography in the evaluation of the functional status of valvular prosthesis].

Science.gov (United States)

Esquivel Avila, J; Molina Zapata, B; Martínez Ríos, M A; Flamand, E

1975-01-01

The FMCG in 22 patients with valvular prosthesis is analyzed and its clinical, hemodynamic and surgical correlation are established (11 from the I.N.C. and 11 from the Hospital Infantil I.M.A.N.). The average age of the patients was 15 years old, 18 had a mitral and six aortic valvulopathy, and they all required a valvular replacement. Of the mitral prosthesis, 14 were Starr-Edwards (13 of ball valve and one of disc), three Lillehei-Kaster and one Börck-Shiley. In 5 patients, the FMCG suspected disfunction that was later corroborated by catheterism in three patients and by surgery in all of them. The important differences of the FMCG between the group with good and the one with bad function were: the aparition of a rumble, a decrease in the amplitud of the closing snap, index of closing snap opering snap of less than one, lenghtening of fases PFVP and IVCP, and shortening of IVDRP. In the patients with auricular fibrilation, after long dyastoles; that would represent an adequate atrial emptying; the closing snap was more intense, the PFVP was lennthened the IVDRP was shortened when the prosthesis was not properly functioning. All the aortic prosthesis were ball valve Starr-Edwards type; in one the FMCG suspected disfunction and the patient had a sudden death outside of the Hospital. The significant differences of the FMCG were the decrease in the intensity of the opening snap, with a Hylen index of less than one, lengthening of the PFVP, IVCP and of the expulsive period (EP). The authors conclude that the FMCG is a good method for an early detection of the disfunctions of valvular prosthesis.

A predictive model for early mortality after surgical treatment of heart valve or prosthesis infective endocarditis. The EndoSCORE.

Science.gov (United States)

Di Mauro, Michele; Dato, Guglielmo Mario Actis; Barili, Fabio; Gelsomino, Sandro; Santè, Pasquale; Corte, Alessandro Della; Carrozza, Antonio; Ratta, Ester Della; Cugola, Diego; Galletti, Lorenzo; Devotini, Roger; Casabona, Riccardo; Santini, Francesco; Salsano, Antonio; Scrofani, Roberto; Antona, Carlo; Botta, Luca; Russo, Claudio; Mancuso, Samuel; Rinaldi, Mauro; De Vincentiis, Carlo; Biondi, Andrea; Beghi, Cesare; Cappabianca, Giangiuseppe; Tarzia, Vincenzo; Gerosa, Gino; De Bonis, Michele; Pozzoli, Alberto; Nicolini, Francesco; Benassi, Filippo; Rosato, Francesco; Grasso, Elena; Livi, Ugolino; Sponga, Sandro; Pacini, Davide; Di Bartolomeo, Roberto; De Martino, Andrea; Bortolotti, Uberto; Onorati, Francesco; Faggian, Giuseppe; Lorusso, Roberto; Vizzardi, Enrico; Di Giammarco, Gabriele; Marinelli, Daniele; Villa, Emmanuel; Troise, Giovanni; Picichè, Marco; Musumeci, Francesco; Paparella, Domenico; Margari, Vito; Tritto, Francesco; Damiani, Girolamo; Scrascia, Giuseppe; Zaccaria, Salvatore; Renzulli, Attilio; Serraino, Giuseppe; Mariscalco, Giovanni; Maselli, Daniele; Foschi, Massimiliano; Parolari, Alessandro; Nappi, Giannantonio

2017-08-15

The aim of this large retrospective study was to provide a logistic risk model along an additive score to predict early mortality after surgical treatment of patients with heart valve or prosthesis infective endocarditis (IE). From 2000 to 2015, 2715 patients with native valve endocarditis (NVE) or prosthesis valve endocarditis (PVE) were operated on in 26 Italian Cardiac Surgery Centers. The relationship between early mortality and covariates was evaluated with logistic mixed effect models. Fixed effects are parameters associated with the entire population or with certain repeatable levels of experimental factors, while random effects are associated with individual experimental units (centers). Early mortality was 11.0% (298/2715); At mixed effect logistic regression the following variables were found associated with early mortality: age class, female gender, LVEF, preoperative shock, COPD, creatinine value above 2mg/dl, presence of abscess, number of treated valve/prosthesis (with respect to one treated valve/prosthesis) and the isolation of Staphylococcus aureus, Fungus spp., Pseudomonas Aeruginosa and other micro-organisms, while Streptococcus spp., Enterococcus spp. and other Staphylococci did not affect early mortality, as well as no micro-organisms isolation. LVEF was found linearly associated with outcomes while non-linear association between mortality and age was tested and the best model was found with a categorization into four classes (AUC=0.851). The following study provides a logistic risk model to predict early mortality in patients with heart valve or prosthesis infective endocarditis undergoing surgical treatment, called "The EndoSCORE". Copyright © 2017. Published by Elsevier B.V.

Incidence and impact of prosthesis-patient mismatch after transcatheter aortic valve implantation.

Science.gov (United States)

Bleiziffer, Sabine; Hettich, Ina; Hutter, Andrea; Wagner, Anke; Deutsch, Marcus-André; Piazza, Nicolo; Lange, Rüdiger

2013-05-01

The study aim was to investigate the incidence of patient-prosthesis mismatch (PPM) with new catheter valves, and its influence on the patients' clinical state. At present, few echocardiographic data are available on the incidence and impact of PPM with the CoreValve and Sapien prostheses for transcatheter aortic valve implantation (TAVI). The reliability of effective orifice area (EOA) measurements was assured by awaiting an interval of six months after TAVI. Of 256 survivors after TAVI, 149 complete echocardiographic data sets were available for the assessment of the indexed EOA (iEOA). In total, 106 CoreValve prostheses and 43 Sapien prostheses were implanted in this high-risk cohort (mean age 81 +/- 6 years, mean logistic EuroSCORE 20 +/- 13%). The overall incidence of PPM (iEOA body surface area were more likely to develop PPM (p = 0.001), while the prosthesis type, native annulus diameter, preoperative EOA, gender and prosthesis size had no influence. The mean aortic gradient was significantly higher in patients with PPM. A reduction in the left ventricular end-diastolic diameter was seen in all patients, without significant differences between groups. There were no differences in postoperative NYHA class or self-assessed health state between patients with or without PPM. PPM was common after TAVI in the presented cohort, presumably because the native calcium masses narrow the outflow area available for blood flow. As expected for low gradients, there was no impairment of left ventricular dimension regression or clinical state of the patients, even if severe PPM was present. Based on the presented data, it is assumed that PPM might be less relevant in TAVI patients.

Complete Transversal Disc Fracture in a Björk-Shiley Delrin Mitral Valve Prosthesis 43 Years After Implantation.

Science.gov (United States)

González-Santos, Jose María; Arnáiz-García, María Elena; Dalmau-Sorlí, María José; Sastre-Rincón, Jose Alfonso; Hernández-Hernández, Jesús; Pérez-Losada, María Elena; Sagredo-Meneses, Víctor; López-Rodríguez, Javier

2016-10-01

A patient who underwent previous implantation of a mitral valve replacement with a Björk-Shiley Delrin (BSD) mitral valve prosthesis during infancy was admitted to our institution 43 years later after an episode of syncope and cardiac arrest. Under extreme hemodynamic instability, a mitral valve prosthetic dysfunction causing massive mitral regurgitation was identified. The patient underwent an emergent cardiac operation, and a complete disc fracture with partial disc migration was found. Exceptional cases of mechanical prosthetic heart valve fracture exist. We report the first case of complete transversal disc rupture of a BSD mitral valve prosthesis after the longest period of implantation ever reported in that position. Copyright © 2016 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

Novel thoughts on patient-prosthesis mismatch in aortic valve replacement: the rationale for the PAR I trial.

Science.gov (United States)

Doenst, Torsten; Amorim, Paulo A; Diab, Mahmoud; Hagendorff, Andreas; Faerber, Gloria; Graff, Jürgen; Rastan, Ardawan; Deutsch, Oliver; Eichinger, Walter

2014-09-01

The hemodynamic performance of prosthetic tissue valves is influenced by valve design and valve-specific sizing strategies. Design determines the actual geometric opening area (GOA) of the prosthetic valve and sizing strategy its actual chosen size. Currently, hemodynamic performance is assessed by determining the effective orifice area (EOA; derived from the continuity equation by relating flow velocities with the area of the left ventricular outflow tract [LVOTA]). The question whether a valve is too small (patient-prosthesis mismatch [PPM]) is currently addressed by relating EOA to body surface area (EOA index [EOAi]). However, this relation may not be appropriate because the EOAi relates flow velocity to patient-specific anatomic parameters twice (i.e., LVOTA and body surface area). This potential confounder may explain the controversies regarding PPM. However, intuitively, leaving a gradient behind after aortic valve replacement cannot be irrelevant. PPM becomes even more relevant with transcatheter valve-in-valve implantation, where a second prosthesis is taking up inner space of a valve that may have already been too small initially. Thus, a reliable method to determine the presence of PPM is needed. The Prosthesis-to-Annulus Relation I (PAR I) trial is a German multicenter study assessing the relation between the prosthetic GOA and the LVOTA as a potentially new parameter for the prediction of hemodynamic outcome. The results may possibly guide future valve size selection and may allow prediction of functionally relevant PPM. Here, we will demonstrate the shortcomings of the currently applied EOAi for the assessment of hemodynamic relevance and present the rationale for the PARI trial, which recently started recruiting patients. Georg Thieme Verlag KG Stuttgart · New York.

Clinical and echocardiographic assessment of the Medtronic Advantage aortic valve prosthesis: the Scandinavian multicentre, prospective study

DEFF Research Database (Denmark)

Haaverstad, Rune; Vitale, Nicola; Karevold, Asbjørn

2006-01-01

OBJECTIVE: The aim of this report is the prospective, multicentre evaluation of clinical results and haemodynamic performance of the Medtronic Advantage aortic valve prosthesis. METHODS: From April 2001 to June 2003, 166 patients (male:female 125:41; mean (SD) age 61.8 (11.8) years) received...... an aortic advantage valve prosthesis. Complete cumulative follow-up was 242.7 patient-years (maximum 3.2; mean 1.6 years). Postoperatively, patients underwent early (within 30 days) and 1 year transthoracic echocardiography. RESULTS: 30 day mortality was 2.4% (n = 4). Kaplan-Meier estimates of freedom from...... echocardiography. CONCLUSIONS: Haemodynamic performance and early clinical results of Medtronic advantage in the aortic position were satisfactory and comparable with those of other bileaflet valves in current clinical use....

Fluid mechanics of heart valves.

Science.gov (United States)

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.

Patient-prosthesis mismatch has no influence on in-hospital mortality after aortic valve replacement.

Science.gov (United States)

Yottasurodom, Chaiwut; Namthaisong, Kriengkrai; Porapakkham, Pramote; Kasemsarn, Choosak; Chotivatanapong, Taweesak; Chaiseri, Pradistchai; Wongdit, Suwannee; Yasotarin, Suwanna

2012-08-01

To analyze the relationship between prosthetic aortic valve orifice and body surface area (Effective Orifice Area Index, EOAI) and in-hospital mortality after aortic valve replacement. A prospective study was conducted between October 2007 to September 2010, 536 patients underwent isolated aortic valve replacement (AVR) was recorded on preoperative, operative and postoperative data. Patient Prosthesis Mismatch (PPM) was classified by Effective Orifice Area Indexed (EOAI) by prosthetic valve area divided by body surface area as mild or no significance if the EOAI is greater than 0.85 cm2/m2, moderate if between 0.65 cm2/m2 and 0.85 cm2/m2, and severe if less than 0.65 cm2/m2. Statistical differences were analyzed by Chi-square and student t-test with p-value less than 0.05 considered significant. There were 304 men, mean age was 60.98 years, mean valve orifice area 1.69 cm2, body surface area 1.60 m2, cross clamp time 1.13 hrs., bypass time 1.67 hrs. Mechanical valves were used in 274 patients (51.2%) and Bioprosthesis were used in 181 patients (48.8%). PPM was found in 33.7%, 6.7% was severe PPM, 27% was moderate PPM and 66.3% has no significant PPM Over all in-hospital mortality was 1.5%. There was no significant difference in hospital mortality between no PPM group, moderate PPM and severe PPM group (1.4% vs. 1.4% vs. 5.4%, p-value = 0.86). In a large aortic valve surgery population, moderate and severe patient prosthesis mismatch occurred in 35.6% of patients but had no influence on in-hospital mortality.

Small valve area index: its influence on early mortality after mitral valve replacement

NARCIS (Netherlands)

Yazdanbakhsh, A. P.; van den Brink, R. B.; Dekker, Egbert; de Mol, B. A.

2000-01-01

OBJECTIVE: To test the hypothesis that mitral valve prosthesis-patient mismatch increases postoperative mortality. METHODS AND RESULTS: The effect of mitral valve prosthesis-patient mismatch on survival in a cohort of consecutive patients after mitral valve replacement with a mechanical prosthesis

Mitral valve replacement in infants and children 5 years of age or younger: Evolution in practice and outcome over three decades with a focus on supra-annular prosthesis implantation

Science.gov (United States)

Tierney, Elif Seda Selamet; Pigula, Frank A.; Berul, Charles I.; Lock, James E.; del Nido, Pedro J.; McElhinney, Doff B.

2014-01-01

Objective Successful mitral valve replacement in young children is limited by the lack of small prosthetic valves. Supra-annular prosthesis implantation can facilitate mitral valve replacement with a larger prosthesis in children with a small annulus, but little is known about its effect on the outcomes of mitral valve replacement in young children. Methods One hundred eighteen children underwent mitral valve replacement at 5 years of age or younger from 1976–2006. Mitral valve replacement was supra-annular in 37 (32%) patients. Results Survival was 74% ± 4% at 1 year and 56% ± 5% at 10 years but improved over time (10-year survival of 83% ± 7% from 1994–2006). Factors associated with worse survival included earlier mitral valve replacement date, age less than 1 year, complete atrioventricular canal, and additional procedures at mitral valve replacement, but not supra-annular mitral valve replacement. As survival improved during our more recent experience, the risks of supra-annular mitral valve replacement became apparent; survival was worse among patients with a supra-annular prosthesis after 1991. A pacemaker was placed in 18 (15%) patients within 1 month of mitral valve replacement and was less likely in patients who had undergone supra-annular mitral valve replacement. Among early survivors, freedom from redo mitral valve replacement was 72% ± 5% at 5 years and 45% ± 7% at 10 years. Twenty-one patients with a supra-annular prosthesis underwent redo mitral valve replacement. The second prosthesis was annular in 15 of these patients and upsized in all but 1, but 5 required pacemaker placement for heart block. Conclusions Supra-annular mitral valve replacement was associated with worse survival than annular mitral valve replacement in our recent experience. Patients with supra-annular mitral valve replacement were less likely to have operative complete heart block but remained at risk when the prosthesis was subsequently replaced. PMID:18954636

An expandable prosthesis with dual cage-and-plate function in a single device for vertebral body replacement: the clinical experience on 14 consecutive cases with vertebral tumors.

Science.gov (United States)

Ramírez, J J; Ramírez, J J; Chiquete, E; Gómez-Limón, E

2011-09-01

The aim of this paper was to test the hypothesis that an expandable prosthesis with dual cage-and-plate function can provide immediate and durable spine stabilization after corpectomy. We designed an expandable vertebral body prosthesis with dual cage-and-plate function in a single device (JR-prosthesis). Anatomical studies were performed to design a titanium-made prosthesis. Cadaver assays were done with a stainless steal device to test fixation and adequacy to the human spine anatomy. Then, 14 patients with vertebral tumors (8 metastatic) underwent corpectomy and vertebral body replacement with the JR-prosthesis. All patients had neurological deficit, severe pain and spine instability (mean follow-up: 25.4 months). Mean pain score before surgery in a visual analog scale improved from 7.6 to 3.0 points after operation (P=0.002). All patients achieved at least one grade of improvement in the Frankel score (P=0.003), excepting the 3 patients with Frankel grade A presurgery. Two patients with renal cell carcinoma died during the following 4 days after surgery (renal failure and massive bleeding), the rest attained a painless and stable spine immediately and maintained for long periods. No significant infections or implant failures were registered. A non-fatal case of inferior vena cava surgical injury was observed (repaired during surgery without further complications). The JR-prosthesis stabilizes the spine immediately after surgery and for the rest of the patients' life. To our knowledge, this is the first report on the clinical experience of any expandable vertebral body prosthesis with dual cage-and-plate function in a single device. These observations await confirmation in different scenarios.

Cost-Effectiveness of Transcatheter Aortic Valve Replacement With a Self-Expanding Prosthesis Versus Surgical Aortic Valve Replacement.

Science.gov (United States)

Reynolds, Matthew R; Lei, Yang; Wang, Kaijun; Chinnakondepalli, Khaja; Vilain, Katherine A; Magnuson, Elizabeth A; Galper, Benjamin Z; Meduri, Christopher U; Arnold, Suzanne V; Baron, Suzanne J; Reardon, Michael J; Adams, David H; Popma, Jeffrey J; Cohen, David J

2016-01-05

Previous studies of the cost-effectiveness of transcatheter aortic valve replacement (TAVR) have been based primarily on a single balloon-expandable system. The goal of this study was to evaluate the cost-effectiveness of TAVR with a self-expanding prosthesis compared with surgical aortic valve replacement (SAVR) for patients with severe aortic stenosis and high surgical risk. We performed a formal economic analysis on the basis of individual, patient-level data from the CoreValve U.S. High Risk Pivotal Trial. Empirical data regarding survival and quality of life over 2 years, and medical resource use and hospital costs through 12 months were used to project life expectancy, quality-adjusted life expectancy, and lifetime medical costs in order to estimate the incremental cost-effectiveness of TAVR versus SAVR from a U.S. Relative to SAVR, TAVR reduced initial length of stay an average of 4.4 days, decreased the need for rehabilitation services at discharge, and resulted in superior 1-month quality of life. Index admission and projected lifetime costs were higher with TAVR than with SAVR (differences $11,260 and $17,849 per patient, respectively), whereas TAVR was projected to provide a lifetime gain of 0.32 quality-adjusted life-years ([QALY]; 0.41 LY) with 3% discounting. Lifetime incremental cost-effectiveness ratios were $55,090 per QALY gained and $43,114 per LY gained. Sensitivity analyses indicated that a reduction in the initial cost of TAVR by ∼$1,650 would lead to an incremental cost-effectiveness ratio <$50,000/QALY gained. In a high-risk clinical trial population, TAVR with a self-expanding prosthesis provided meaningful clinical benefits compared with SAVR, with incremental costs considered acceptable by current U.S. With expected modest reductions in the cost of index TAVR admissions, the value of TAVR compared with SAVR in this patient population would become high. (Safety and Efficacy Study of the Medtronic CoreValve System in the Treatment of

Hemodynamic Evaluation of a Biological and Mechanical Aortic Valve Prosthesis Using Patient-Specific MRI-Based CFD.

Science.gov (United States)

Hellmeier, Florian; Nordmeyer, Sarah; Yevtushenko, Pavlo; Bruening, Jan; Berger, Felix; Kuehne, Titus; Goubergrits, Leonid; Kelm, Marcus

2018-01-01

Modeling different treatment options before a procedure is performed is a promising approach for surgical decision making and patient care in heart valve disease. This study investigated the hemodynamic impact of different prostheses through patient-specific MRI-based CFD simulations. Ten time-resolved MRI data sets with and without velocity encoding were obtained to reconstruct the aorta and set hemodynamic boundary conditions for simulations. Aortic hemodynamics after virtual valve replacement with a biological and mechanical valve prosthesis were investigated. Wall shear stress (WSS), secondary flow degree (SFD), transvalvular pressure drop (TPD), turbulent kinetic energy (TKE), and normalized flow displacement (NFD) were evaluated to characterize valve-induced hemodynamics. The biological prostheses induced significantly higher WSS (medians: 9.3 vs. 8.6 Pa, P = 0.027) and SFD (means: 0.78 vs. 0.49, P = 0.002) in the ascending aorta, TPD (medians: 11.4 vs. 2.7 mm Hg, P = 0.002), TKE (means: 400 vs. 283 cm 2 /s 2 , P = 0.037), and NFD (means: 0.0994 vs. 0.0607, P = 0.020) than the mechanical prostheses. The differences between the prosthesis types showed great inter-patient variability, however. Given this variability, a patient-specific evaluation is warranted. In conclusion, MRI-based CFD offers an opportunity to assess the interactions between prosthesis and patient-specific boundary conditions, which may help in optimizing surgical decision making and providing additional guidance to clinicians. © 2017 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

Rare early prosthesis obstruction after mitral valve replacement: a case report and literature review

Directory of Open Access Journals (Sweden)

Shi Jun

2012-07-01

Full Text Available Abstract As a dreadful complication after the mechanical heart valve replacement, prosthetic valve obstruction caused by pannus formation occurs increasingly with time. The authors here present a case of 42-year-old woman who was urgently admitted to hospital with acute heart failure symptoms due to the mechanical mitral valve failure only 3 months after surgery. Transthoracic and transesophageal echocardiography demonstrated that the bileaflet of the mitral prosthesis were completely immobilized with only a small transvalvular jet remained. During the reoperation, the reason of the prosthetic valve obstruction was attributed to the noncircular pannus ingrowth extending from the atrioventricular side. For a better understanding of the prosthetic valve dysfunction caused by pannus formation, the authors then compile a literature review to briefly discuss the status quo of the clinical characteristics of this uncommon complication.

Impact of prosthesis-patient mismatch on early and late mortality after aortic valve replacement

NARCIS (Netherlands)

Koene, Bart M.; Hamad, Mohamed A. Soliman; Bouma, Wobbe; Mariani, Massimo A.; Peels, Kathinka C.; van Dantzig, Jan-Melle; van Straten, Albert H.

2013-01-01

Background: The influence of prosthesis-patient mismatch (PPM) on survival after aortic valve replacement (AVR) remains controversial. In this study, we sought to determine the effect of PPM on early (30 days) after AVR or AVR combined with coronary artery bypass grafting (AVR with CABG). Methods:

[Extracorporeal ventriculoatrial shunt with the use of one-way ball valve].

Science.gov (United States)

Kubo, Shigeki; Takimoto, Hiroshi; Hosoi, Kazuki; Toyota, Shingo; Takakura, Shuji; Hayashi, Yasuhiro; Ueno, Masato; Morisako, Toshitaka; Karasawa, Jun; Ninaga, Hideo; Yoshimine, Toshiki

2002-04-01

We developed a simple system of an "extracorporeal" ventriculoatrial (VA) shunt using a one-way ball valve (Acty valve II, Kaneka Medix) to release the patient from postoperative constraint during the ventricular drainage. The system is constructed in such a way that the ventricular drainage tube is connected to the central venous catheter via a one-way valve. The CSF is regulated by using the valve and is diverted into the systemic circulation as in the conventional ventriculoatrial shunt. After 2 or 3 weeks of CSF diversion through the extracorporeal VA shunt, a ventriculoperitoneal shunt is placed if hydrocephalus is apparent by temporary occlusion of the system. We applied this system to 4 patients with hydrocephalus, and we found it useful and free from adverse effects. The patient was freed from physical constraint involved in conventional ventricular drainage and an effective program of early rehabilitation was able to be started.

Aortic valve replacement with sutureless prosthesis: better than root enlargement to avoid patient-prosthesis mismatch?

Science.gov (United States)

Beckmann, Erik; Martens, Andreas; Alhadi, Firas; Hoeffler, Klaus; Umminger, Julia; Kaufeld, Tim; Sarikouch, Samir; Koigeldiev, Nurbol; Cebotari, Serghei; Schmitto, Jan Dieter; Haverich, Axel; Shrestha, Malakh

2016-06-01

Aortic valve replacement in patients with a small aortic annulus may result in patient-prosthesis mismatch (PPM). Aortic root enlargement (ARE) can reduce PPM, but leads to extended cardiac ischaemia times. Sutureless valves have the potential to prevent PPM while reducing cardiac ischaemia times. Between January 2007 and December 2011, a total of 128 patients with a small aortic annulus underwent surgery for aortic valve stenosis at our centre. Thirty-six (17% male, n = 6) patients received conventional valve replacement with ARE and 92 (16% male, n = 18) subjects received sutureless valve implantation (Sorin Perceval). We conducted a comparative, retrospective study with follow-up. The sutureless group showed a significantly higher age (79 years) than the ARE patients (62 years, P body surface area was 0.91 ± 0.2 cm(2)/m(2) in ARE patients and 0.83 ± 0.14 cm(2)/m(2) in sutureless patients (P = 0.040). The rate of patients with severe PPM was 6% (n = 2) in ARE patients and 11% (n = 8%) in sutureless patients (not significant, n.s.). The 30-day mortality rates were 2% (n = 2) in sutureless patients and 6% (n = 2) in ARE patients (n.s.). The 1- and 5-year survival rates of the sutureless group were 92 and 54% years, respectively, whereas the 1- and 5-year survival rates of the ARE group were 76% (n.s.). Although the sutureless valve patients received significantly more concomitant procedures, all operation-associated times were significantly shorter. Despite sutureless valve patients being older, the 30-day mortality and survival rates were comparable in the two groups. Since the indexed EOA was only slightly lower and the incidence of severe PPM was not significantly higher in the sutureless valve patients, we conclude that sutureless valve implantation is an alternative to conventional ARE to treat a small aortic annulus and avoid PPM, especially in geriatric patients who benefit from the quick implantation process. © The Author 2016. Published by Oxford

Estimating Wear Of Installed Ball Bearings

Science.gov (United States)

Keba, John E.; Mcvey, Scott E.

1993-01-01

Simple inspection and measurement technique makes possible to estimate wear of balls in ball bearing, without removing bearing from shaft on which installed. To perform measurement, one observes bearing cage while turning shaft by hand to obtain integral number of cage rotations and to measure, to nearest 2 degrees, number of shaft rotations producing cage rotations. Ratio between numbers of cages and shaft rotations depends only on internal geometry of bearing and applied load. Changes in turns ratio reflect changes in internal geometry of bearing provided measurements made with similar bearing loads. By assuming all wear occurs on balls, one computes effective value for this wear from change in turns ratio.

Consequence of patient substitution of nattokinase for warfarin after aortic valve replacement with a mechanical prosthesis.

Science.gov (United States)

Elahi, Maqsood M; Choi, Charles H; Konda, Subbareddy; Shake, Jay G

2015-01-01

This report describes a patient's self-substitution of nattokinase for the vitamin K antagonist warfarin after aortic valve replacement with a mechanical prosthesis. Nattokinase is an enzyme derived from a popular fermented soybean preparation in Japan (natto), which has fibrinolytic properties and is gaining popularity in nontraditional health journals and nonmedical health websites as an over-the-counter thrombolytic. After nearly a year of use of nattokinase without warfarin, the patient developed thrombus on the mechanical valve and underwent successful repeat valve replacement. We believe this is the first documented case of nattokinase being used as a substitute for warfarin after valve replacement, and we strongly discourage its use for this purpose.

Impact of Prosthesis-Patient Mismatch on Long-term Functional Capacity After Mechanical Aortic Valve Replacement

NARCIS (Netherlands)

Petit-Eisenmann, H.; Epailly, E.; Velten, M.; Radojevic, J.; Eisenmann, B.; Kremer, H.; Kindo, M.

2016-01-01

BACKGROUND: The impact of prosthesis-patient mismatch (PPM) after aortic valve replacement (AVR) for aortic stenosis on exercise capacity remains controversial. The aim of this study was to analyze the long-term impact of PPM after mechanical AVR on maximal oxygen uptake (VO2max). METHODS: The study

Heart valve surgery

Science.gov (United States)

... replacement; Valve repair; Heart valve prosthesis; Mechanical valves; Prosthetic valves ... surgery. Your heart valve has been damaged by infection ( endocarditis ). You have received a new heart valve ...

Impact of patient-prosthesis mismatch after transcatheter aortic valve-in-valve implantation in degenerated bioprostheses.

Science.gov (United States)

Seiffert, Moritz; Conradi, Lenard; Baldus, Stephan; Knap, Malgorzata; Schirmer, Johannes; Franzen, Olaf; Koschyk, Dietmar; Meinertz, Thomas; Reichenspurner, Hermann; Treede, Hendrik

2012-03-01

Transcatheter valve-in-valve implantation is evolving as an alternative to reoperative valve replacement in high-risk patients with degenerated bioprostheses. Nevertheless, hemodynamic performance is limited by the previously implanted xenograft. We report our experience with patient-prosthesis mismatch (PPM) after valve-in-valve implantation in the aortic position. Eleven patients (aged 79.3 ± 6.1 years) received transapical implantation of a balloon-expandable pericardial heart valve into a degenerated bioprosthesis (size, 23.9 ± 1.6 mm; range, 21-27 mm) in the aortic position. All patients were considered high risk for surgical valve replacement (logistic European System for Cardiac Operative Risk Evaluation, 31.8% ± 24.1%). Severe PPM was defined as an indexed effective orifice area less than 0.65 cm(2)/m(2), determined by discharge echocardiography. Severe PPM was evident in 5 patients (group 1) and absent in 6 patients (group 2). Mean transvalvular gradients decreased from 29.2 ± 15.4 mm Hg before implantation to 21.2 ± 9.7 mm Hg at discharge (group 1) and from 28.2 ± 9.0 mm Hg before implantation to 15.2 ± 6.5 mm Hg at discharge (group 2). Indexed effective orifice area increased from 0.5 ± 0.1 cm(2)/m(2) to 0.6 ± 0.1 cm(2)/m(2) and from 0.6 ± 0.3 cm(2)/m(2) to 0.8 ± 0.3 cm(2)/m(2). Aortic regurgitation decreased from grade 2.0 ± 1.1 to 0.4 ± 0.5 overall. No differences in New York Heart Association class improvement or survival during follow-up were observed. One patient required reoperation for symptomatic PPM 426 days after implantation. Valve-in-valve implantation can be performed in high-risk surgical patients to avoid reoperation. However, PPM frequently occurs, making adequate patient selection crucial. Small bioprostheses (body surface area less than 1.8 m(2). Larger prostheses seem to carry a lower risk for PPM. Although no delay in clinical improvement was seen at short-term, 1 PPM-related surgical intervention raises concern regarding

CT-angiography-based evaluation of the aortic annulus for prosthesis sizing in transcatheter aortic valve implantation (TAVI-predictive value and optimal thresholds for major anatomic parameters.

Directory of Open Access Journals (Sweden)

Florian Schwarz

Full Text Available BACKGROUND/OBJECTIVES: To evaluate the predictive value of CT-derived measurements of the aortic annulus for prosthesis sizing in transcatheter aortic valve implantation (TAVI and to calculate optimal cutoff values for the selection of various prosthesis sizes. METHODS: The local IRB waived approval for this single-center retrospective analysis. Of 441 consecutive TAVI-patients, 90 were excluded (death within 30 days: 13; more than mild aortic regurgitation: 10; other reasons: 67. In the remaining 351 patients, the CoreValve (Medtronic and the Edwards Sapien XT valve (Edwards Lifesciences were implanted in 235 and 116 patients. Optimal prosthesis size was determined during TAVI by inflation of a balloon catheter at the aortic annulus. All patients had undergone CT-angiography of the heart or body trunk prior to TAVI. Using these datasets, the diameter of the long and short axis as well as the circumference and the area of the aortic annulus were measured. Multi-Class Receiver-Operator-Curve analyses were used to determine the predictive value of all variables and to define optimal cutoff-values. RESULTS: Differences between patients who underwent implantation of the small, medium or large prosthesis were significant for all except the large vs. medium CoreValve (all p's<0.05. Furthermore, mean diameter, annulus area and circumference had equally high predictive value for prosthesis size for both manufacturers (multi-class AUC's: 0.80, 0.88, 0.91, 0.88, 0.88, 0.89. Using the calculated optimal cutoff-values, prosthesis size is predicted correctly in 85% of cases. CONCLUSION: CT-based aortic root measurements permit excellent prediction of the prosthesis size considered optimal during TAVI.

CT-angiography-based evaluation of the aortic annulus for prosthesis sizing in transcatheter aortic valve implantation (TAVI)-predictive value and optimal thresholds for major anatomic parameters.

Science.gov (United States)

Schwarz, Florian; Lange, Philipp; Zinsser, Dominik; Greif, Martin; Boekstegers, Peter; Schmitz, Christoph; Reiser, Maximilian F; Kupatt, Christian; Becker, Hans C

2014-01-01

To evaluate the predictive value of CT-derived measurements of the aortic annulus for prosthesis sizing in transcatheter aortic valve implantation (TAVI) and to calculate optimal cutoff values for the selection of various prosthesis sizes. The local IRB waived approval for this single-center retrospective analysis. Of 441 consecutive TAVI-patients, 90 were excluded (death within 30 days: 13; more than mild aortic regurgitation: 10; other reasons: 67). In the remaining 351 patients, the CoreValve (Medtronic) and the Edwards Sapien XT valve (Edwards Lifesciences) were implanted in 235 and 116 patients. Optimal prosthesis size was determined during TAVI by inflation of a balloon catheter at the aortic annulus. All patients had undergone CT-angiography of the heart or body trunk prior to TAVI. Using these datasets, the diameter of the long and short axis as well as the circumference and the area of the aortic annulus were measured. Multi-Class Receiver-Operator-Curve analyses were used to determine the predictive value of all variables and to define optimal cutoff-values. Differences between patients who underwent implantation of the small, medium or large prosthesis were significant for all except the large vs. medium CoreValve (all p'sprosthesis size for both manufacturers (multi-class AUC's: 0.80, 0.88, 0.91, 0.88, 0.88, 0.89). Using the calculated optimal cutoff-values, prosthesis size is predicted correctly in 85% of cases. CT-based aortic root measurements permit excellent prediction of the prosthesis size considered optimal during TAVI.

Impact of aortic prosthesis-patient mismatch on left ventricular mass regression.

Science.gov (United States)

Alassal, Mohamed A; Ibrahim, Bedir M; Elsadeck, Nabil

2014-06-01

Prostheses used for aortic valve replacement may be small in relation to body size, causing prosthesis-patient mismatch and delaying left ventricular mass regression. This study examined the effect of prosthesis-patient mismatch on regression of left ventricular mass after aortic valve replacement. We prospectively studied 96 patients undergoing aortic valve replacement between 2007 and 2012. Mean and peak gradients and indexed effective orifice area were measured by transthoracic echocardiography at 3 and 6 months postoperatively. Patient-prosthesis mismatch was defined as indexed effective orifice area ≤0.85 cm(2)·m(-2). Moderate prosthesis-patient mismatch was present in 25% of patients. There were no significant differences in demographic and operative data between patients with and without prosthesis-patient mismatch. Left ventricular dimensions, posterior wall thickness, transvalvular gradients, and left ventricular mass decreased significantly after aortic valve replacement in both groups. The interventricular septal diameter and left ventricular mass index regression, and left ventricular ejection fraction were better in patients without prosthesis-patient mismatch. There was a significant positive correlation between the postoperative indexed effective orifice area of each valve prosthesis and the rate of left ventricular mass regression. Prosthesis-patient mismatch leads to higher transprosthetic gradients and impaired left ventricular mass regression. A small-sized valve prosthesis does not necessarily result in prosthesis-patient mismatch, and may be perfectly adequate in patient with small body size. © The Author(s) 2013 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Impact of valve prosthesis-patient mismatch estimated by echocardiographic-determined effective orifice area on long-term outcome after aortic valve replacement.

Science.gov (United States)

Florath, Ines; Albert, Alexander; Rosendahl, Ulrich; Ennker, Ina Carolin; Ennker, Jrgen

2008-06-01

The impact of valve prosthesis-patient mismatch on long-term outcome after aortic valve replacement estimated by various variables such as projected indexed effective orifice area and internal geometric orifice area obtained from in vivo or in vitro published data is still controversial. The effective orifice area was measured by echocardiography in 533 patients. The mean age of the patients was 71 +/- 9 years; mean follow-up time was 4.7 +/- 2.2 years. The impact of severe (indexed effective orifice area regression. Severe mismatch (hazard ratio: 1.9 [1.08-3.21]) was a significant predictor of survival time after adjustment for age, left ventricular ejection fraction, atrial fibrillation, New York Heart Association class, serum creatinine, and hemoglobin level. The 5- and 7-year survival rates were 71% +/- 4% and 54% +/- 8% for patients with severe mismatch and 83% +/- 4% and 80% +/- 8% for patients with mild mismatch, respectively. The correlation between projected and measured indexed effective orifice area was of medium strength (r = 0.49), and the frequency of observed mismatch depended linearly on the projected indexed effective orifice area. Although projected indexed effective orifice area and indexed internal geometric orifice area were significant predictors of severe mismatch, the sensitivity and specificity for severe prosthesis-patient mismatch were only 75% and 52%, using an optimal threshold of projected indexed effective orifice area defined by the Youden index. Severe prosthesis-patient mismatch estimated by effective orifice area measured within 10 days was an independent risk factor of survival time. Projected indexed effective orifice area determined at surgery does not sufficiently predict mismatch.

Experimental substantiation of the design of a prosthetic heart valve for «valve-in-valve» implantation

Directory of Open Access Journals (Sweden)

K. Yu. Klyshnikov

2017-01-01

Full Text Available The aim of the study was to perform a series of in vitro tests of a prototype of the developing heart valve prosthesis to evaluate its functional characteristics. Materials and methods. In this work we have used the frames and full prototypes of the prosthesis, consisting of a stent-like stainless steel support frame with mounted biological leaflets and cover. The authors evaluated the calculated and experimental forces necessary for the displacement of the sutureless implanted prosthesis using the test machine under uniaxial tension. The risk of defects and damages to the supporting framework as a result of implantation was evaluated by scanning electron microscopy. The hydrodynamic characteristics of the prosthesis were investigated under physiological conditions and «valvein-valve» implantation. Evaluation of the ergonomics and applicability of the proposed construction on the cadaver heart model of cattle was carried out. Results. As a result of the forces assessment, it was found that the force required to shear the prosthesis was 3.12 ± 0.37 N, while the calculated value was 1.7 N, which is significantly lower than the obtained value. The comparison of the images obtained with small and large magnifications demonstrated the absence of critical surface defects. Additional analysis under the super-large magnifications also did not reveal problem areas. During the hydrodynamic study, it was shown that the average transplant gradient increased slightly from 2.8–3.4 to 3.2–4.5 mm Hg for the initial prosthesis and the «valve-in-valve» complex, respectively. The decrease of the effective orifice area was 6–9% relative to the initial one. Evaluation of the implantation technique demonstrated the consistency of the approach: the use of the developed holder in combination with the balloon implantation system made it possible to position the prosthesis throughout the procedure. Conclusion. The series of tests demonstrates the consistency

Fabrication of a Customized Ball Abutment to Correct a Nonparallel Implant Abutment for a Mandibular Implant-Supported Removable Partial Prosthesis: A Case Report

Directory of Open Access Journals (Sweden)

Hossein Dasht

2017-12-01

Full Text Available Introduction: While using an implant-supported removable partial prosthesis, the implant abutments should be parallel to one another along the path of insertion. If the implants and their attachments are placed vertically on a similar occlusal plane, not only is the retention improved, the prosthesis will also be maintained for a longer period. Case Report: A 65-year-old male patient referred to the School of Dentistry in Mashhad, Iran with complaints of discomfort with the removable partial dentures for his lower mandible. Due to the lack of parallelism in the supporting implants, prefabricated ball abutment could not be used. As a result, a customized ball abutment was fabricated in order to correct the non-parallelism of the implants. Conclusion: Using UCLA abutments could be a cost-efficient approach for the correction of misaligned implant abutments in implant-supported overdentures.

Transcatheter aortic valve implantation in patients with a mitral prosthesis; single center experience and review of literature.

Science.gov (United States)

Asil, Serkan; Şahiner, Levent; Özer, Necla; Kaya, E Barış; Evranos, Banu; Canpolat, Uğur; Yorgun, Hikmet; Karagöz, Heves; Aytemir, Kudret

2016-10-15

Following the encouraging results of several registries and trials, transcatheter aortic valve implantation (TAVI) has been recognized as a valid option in patients with severe aortic stenosis deemed at high or prohibitive risk for surgical treatment. Good procedural success and good clinical outcomes have been showed and very limited data exist on TAVI in the setting of a preexisting mitral prosthesis regarding the technique, potential complications, and outcomes. Here, we report six cases of transfemoral TAVI with a self-expanding bioprosthesis (CoreValve; Medtronic, Inc) in patients who had previously undergone mitral valve replacement. Preprocedural, intraprocedural ve postprocedural outcome and data were analyzed and a brief literature review is also presented. Our experiences show that transfemoral CoreValve implantation can be performed successfully in patients with mechanical and bioprosthetic mitral valves. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Sutureless implantation of the perceval s aortic valve prosthesis through right anterior minithoracotomy.

Science.gov (United States)

Gilmanov, Daniyar; Miceli, Antonio; Bevilacqua, Stefano; Farneti, Pierandrea; Solinas, Marco; Ferrarini, Matteo; Glauber, Mattia

2013-12-01

Many new, less invasive strategies are proposed for aortic valve operation in elderly patients. Rapid deployment sutureless aortic valve prosthesis has been recently introduced. We analyzed our experience with a sutureless valve implanted through a minimally invasive approach. A retrospective observational study with prospectively registered data was conducted on 137 patients undergoing aortic valve replacement through a right anterior minithoracotomy. Between April 2011 and January 2013, 137 consecutive patients underwent aortic valve replacement with a recently introduced, rapid deployment, sutureless pericardial valve in minithoracotomy access (47 men; mean age, 76.6 ± 7.1 years). There were 35 obese patients with a body mass index of more than 30 kg/m(2). Mean logistic EuroSCORE I was 10.0; 74 (54%) patients were in New York Heart Association functional class III and IV. In all, 19 (13.9%), 45 (32.8%), and 73 (53.3%) patients received 21-, 23-, and 25-mm valve prostheses, respectively. The mean aortic cross-clamp and cardiopulmonary bypass times were 59.3 ± 19 min and 92.3 ± 27 min, respectively. No operative mortality occurred. Median stay in the intensive care unit was 1 day, with assisted ventilation necessary for a median of 6 hours. Three cases of postoperative ischemic stroke were observed (1 patient with a previous history of an ischemic cerebral event). Median hospital length of stay was 6 days. A sutureless valve for minimally invasive aortic valve replacement is a feasible, effective, and safe tool. Ultimately amplifying indications for less invasive aortic valve replacement in a high surgical risk subset of patients, it can become a valid alternative for transcatheter aortic valve implantation. Copyright © 2013 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

Heart valve replacement with the Sorin tilting-disc prosthesis. A 10-year experience.

Science.gov (United States)

Milano, A; Bortolotti, U; Mazzucco, A; Mossuto, E; Testolin, L; Thiene, G; Gallucci, V

1992-02-01

From 1978 to 1988, 697 patients with a mean age of 48 +/- 11 years (range 5 to 75 years) received a Sorin tilting-disc prosthesis; 358 had had aortic valve replacement, 247 mitral valve replacement, and 92 mitral and aortic valve replacement. Operative mortality rates were 7.8%, 11.3%, and 10.8%, respectively, in the three groups. Cumulative duration of follow-up is 1650 patient-years for aortic valve replacement (maximum follow-up 11.4 years), 963 patient-years for mitral valve replacement (maximum follow-up 9.9 years) and 328 patient-years for mitral and aortic valve replacement (maximum follow-up 9.4 years). Actuarial survival at 9 years is 72% +/- 4% after mitral valve replacement, 70% +/- 3% after aortic valve replacement, and 50% +/- 12% after mitral and aortic valve replacement, and actuarial freedom from valve-related deaths is 97% +/- 2% after mitral valve replacement, 92% +/- 2% after aortic valve replacement, and 62% +/- 15% after mitral and aortic valve replacement. Thromboembolic events occurred in 21 patients with aortic valve replacement (1.3% +/- 0.2%/pt-yr), in 12 with mitral valve replacement (1.2% +/- 0.3% pt-yr), and in seven with mitral and aortic valve replacement (2.1% +/- 0.8%), with one case of prosthetic thrombosis in each group; actuarial freedom from thromboembolism at 9 years is 92% +/- 3% after mitral valve replacement, 91% +/- 3% after aortic valve replacement, and 74% +/- 16% after mitral and aortic valve replacement. Anticoagulant-related hemorrhage was observed in 15 patients after aortic valve replacement (0.9% +/- 0.2%/pt-yr), in 9 after mitral valve replacement (0.9% +/- 0.3%/pt-yr), and in 6 with mitral and aortic valve replacement (0.9% +/- 0.5%/pt-yr); actuarial freedom from this complication at 9 years is 94% +/- 2% after aortic valve replacement, 91% +/- 4% after mitral valve replacement, and 68% +/- 16% after mitral and aortic valve replacement. Actuarial freedom from reoperation at 9 years is 97% +/- 2% after mitral and

[History, present and future of biomaterials used for artificial heart valves].

Science.gov (United States)

Kostrzewa, Benita; Rybak, Zbigniew

2013-01-01

Artificial heart valves can be classified into mechanical and biological. We have three types of mechanical heart valves: caged ball, tilting disc and bileaflet. Mechanical heart valves are made from various materials. They may be produced from metals, ceramics and polymers, e.g.: stainless steel, titanium, silicone, pyrolytic carbon. Biological valves are made from synthetic components (e.g.: PTFE, Dacron) and materials of biological origin (e.g.: cow pericardium, pig heart valve). We have also identified transcatheter aortic valve implantation (TAVI). TAVI may be produced from metals, ceramics and polymers (e.g.: stainless steel, titanium, Dacron) and biological material (e.g.: pig heart valve). This paper describes advantages and disadvantages of different types of artificial heart valves. The lifespan of mechanical valves is 20-30 years and they can be used for patients of any age. Mechanical valves have also disadvantages--anticoagulants are required to prevent thrombosis. Biological valves are made from natural materials, so they do not require prolonged anticoagulation. Their lifetime is 10-15 years, so they are offered to patients over 40 years. Another problem is the occurrence of calcification.

Aortic valve replacement and prosthesis-patient mismatch in the era of trans-catheter aortic valve implantation.

Science.gov (United States)

Morita, Shigeki

2016-08-01

The treatment strategy for aortic stenosis (AS) has been changing due to newly developed valvular prostheses and trans-catheter aortic valve implantation (TAVI). To determine the role of new modalities for AS with a small aortic root, papers using the concept of prosthesis-patient mismatch (PPM) were reviewed. First, to determine the cut-off value of the indexed effective orifice area (IEOA) for defining PPM, the studies of surgical aortic valve replacement (SAVR) with a follow-up longer than 5 years and a patient number larger than 500 were reviewed. Second, the papers comparing TAVI and SAVR were reviewed. Furthermore, the prevalence of PPM was reviewed, with the addition of papers on aortic root enlargement, sutureless AVR, and aortic valve reconstruction with autologous pericardium. The results of the long-term survival after aortic valve replacement (AVR) have indicated that an IEOA less than 0.65 cm(2)/m(2) should be avoided in all cases, whereas the indications for patients with an IEOA between 065 and 0.85 cm(2)/m(2) should be determined by considering multiple factors. A large body size and younger age have a significantly negative influence on the long-term survival. In Asian population, the prevalence of PPM was low, despite the fact that the size of the aortic annulus was small. The IEOA after TAVI was larger than after surgical AVR in population-matched studies. To evaluate the role of TAVI and other modalities for a small aortic root, studies with a longer follow-up and larger volume are thus warranted.

Reoperation for non-structural valvular dysfunction caused by pannus ingrowth in aortic valve prosthesis.

Science.gov (United States)

Oh, Se Jin; Park, Samina; Kim, Jun Sung; Kim, Kyung-Hwan; Kim, Ki Bong; Ahn, Hyuk

2013-07-01

The authors' clinical experience is presented of non-structural valvular dysfunction of the prosthetic aortic valve caused by pannus ingrowth during the late postoperative period after previous heart valve surgery. Between January 1999 and April 2012, at the authors' institution, a total of 33 patients underwent reoperation for increased mean pressure gradient of the prosthetic aortic valve. All patients were shown to have pannus ingrowth. The mean interval from the previous operation was 16.7 +/- 4.3 years, and the most common etiology for the previous aortic valve replacement (AVR) was rheumatic valve disease. The mean effective orifice area index (EOAI) of the previous prosthetic valve was 0.97 +/- 0.11 cm2/m2, and the mean pressure gradient on the aortic prosthesis before reoperation was 39.1 +/- 10.7 mmHg. Two patients (6.1%) died in-hospital, and late death occurred in six patients (18.2%). At the first operation, 30 patients underwent mitral or tricuspid valve surgery as a concomitant procedure. Among these operations, mitral valve replacement (MVR) was combined in 24 of all 26 patients with rheumatic valve disease. Four patients underwent pannus removal only while the prosthetic aortic valve was left in place. The mean EOAI after reoperation was significantly increased to 1.16 +/- 0.16 cm2/m2 (p pannus ingrowth was shown in patients with a small EOAI of the prosthetic aortic valve and combined MVR for rheumatic disease. As reoperation for pannus overgrowth showed good clinical outcomes, an aggressive resection of pannus and repeated AVR should be considered in symptomatic patients to avoid the complications of other cardiac diseases.

Strategy to avoid patient-prosthesis mismatch: aortic root enlargement.

Science.gov (United States)

Srivastava, Dharmendra Kumar; Sanki, Prokash; Bhattacharya, Subhankar; Siddique, Javed Veqar

2014-02-01

The choice of a valve with an effective orifice area matching the body surface area and providing efficient hemodynamics is an important factor affecting mortality and morbidity in patients undergoing aortic valve replacement. Our preventative strategy was to implant a larger prosthetic valve by aortic root enlargement using the Nunez procedure in 17 patients between February 2010 and January 2011. The decision to enlarge the aortic root was taken when the 19-mm sizer could not be negotiated easily through the aortic root, or on the basis of body surface area of the patient or type of prosthesis available. Postoperative reductions in peak and mean pressure gradients across aortic valve of 12.8-16.5 and 10.2-12.6 mm Hg, respectively, were observed. Postoperative effective orifice areas of the aortic valves were 1.1-1.5 cm(2). By upsizing the aortic valve, we were able to eliminate patient-prosthesis mismatch in 5 patients, and reduce severe patient-prosthesis mismatch to moderate in 11. Aortic root enlargement is a safe procedure. Therefore, cardiac surgeons should not be reluctant to enlarge the aortic root with an autologous pericardial patch to permit implantation of an adequate size of aortic valve prosthesis, with minimal additional aortic crossclamp time and no added cost.

Double Valve Replacement (Mitral and Aortic for Rheumatic Heart Disease: A 20-year experience with 300 patients.

Directory of Open Access Journals (Sweden)

Prashant Mishra

2016-09-01

Full Text Available Introduction: Rheumatic heart disease still remains one of the leading causes of congestive heart failure and death owing to valvular pathologies, in developing countries. Valve replacement still remains the treatment of choice in such patients.The aim of this study wasto analyze the postoperative outcome of  double valve replacement (Mitral and Aortic in patients of rheumatic heart disease. Materials and Methods: Between 1988 and 2008, 300 patients of rheumatic heart disease underwent double (Mitral and Aortic valve replacement with Starr Edwards valve or St Jude mechanical valve prosthesis were implanted. These patients were studied retrospectively for preoperative data and postoperative outcome including causes of early and late deaths and the data was analyzed statistically. Results: The 30-day hospital death rate was 11.3% andlate death occurred in 11.6%. Anticoagulant regimen was followed to maintain the target pro-thrombin time at 1.5 times the control value. The actuarial survival (exclusive of hospital mortality was 92.4%, 84.6%, and 84.4%, per year at 5, 10, and 20 years, respectively Conclusions: In view of the acknowledged advantageof superior durability, increased thromboresistance in our patient population, and its cost effectiveness the Starr-Edwards ball valve or St. Jude valve is the mechanical prosthesis of choice for advanced combined valvular disease. The low-intensity anticoagulant regimen has offered suffcient protection against thromboembolism as well as hemorrhage.

Wispy Prosthesis: A Novel Method in Denture Weight Reduction.

Science.gov (United States)

Anne, Gopinadh; Budeti, Sreedevi; Anche, Sampath Kumar; Zakkula, Srujana; Atla, Jyothi; Jyothula, Ravi Rakesh Dev; Appana, Krishna Chaitanya; Peddinti, Vijaya Kumar

2016-04-01

Stability and retention of the denture becomes at stake with the increase in weight of the denture prosthesis. As a consequence, different materials and methods have been introduced to overcome these issues but denture weight reduction still remains to be a cumbersome and strenuous procedure. To introduce a novel technique for the fabrication of denture prosthesis where in the weight of the denture will not affect the retention and stability of the denture. Four groups with a sample size of 10 each, were included where in one group was control and other three were study groups. The control group samples were made completely solid and the study group samples were packed with materials like bean balls, cellulose balls and polyacrylic fibers. The weight of all the samples of each study group was measured and compared with the control group. The observations were analyzed statistically by paired t-test. It was observed that the bean balls group produced a weight reduction of 31.3%, cellulose balls group 27.4% and polyacrylic fibers group 24.5% when compared to that of the control group. This novel technique will eliminate the problems that were associated in creating hollowness and at the same time will reduce the weight of the prosthesis and among all the study groups, bean balls group were found to reduce maximum weight of the prosthesis.

Mitral valve-sparing procedures and prosthetic heart valve failure: A case report

Science.gov (United States)

Khan, Nasir A; Butany, Jagdish; Leong, Shaun W; Rao, Vivek; Cusimano, Robert J; Ross, Heather J

2009-01-01

Prosthetic heart valve dysfunction due to thrombus or pannus formation can be a life-threatening complication. The present report describes a 47-year-old woman who developed valvular cardiomyopathy after chorda-sparing mitral valve replacement, and subsequently underwent heart transplantation for progressive heart failure. The explanted mitral valve prosthesis showed significant thrombus and pannus leading to reduced leaflet mobility and valvular stenosis. The present report illustrates the role of the subvalvular apparatus and pannus in prosthesis dysfunction. PMID:19279993

Impact of obesity on long-term survival after aortic valve replacement with a small prosthesis.

Science.gov (United States)

Wang, Biao; Yang, Hongyang; Wang, Tao; Zhang, Xiquan; Zhu, Wenjie; Cao, Guangqing; Wu, Shuming

2013-07-01

Although many studies have evaluated the impact of obesity on various medical treatments, it is not known whether obesity is related to late mortality with implantation of small aortic prostheses. This study evaluated the effect of obesity on the late survival of patients after aortic valve replacement (AVR) with implantation of a small aortic prosthesis (size ≤ 21 mm). From January 1998 to December 2008, 307 patients in our institution who underwent primary AVR with smaller prostheses survived 30 days after surgery. Patients were categorized as normal weight if body mass index (BMI) was prosthesis. Obesity or/and overweight may also affect the NYHA classification, even in the longer term. EOAI should be improved where possible, as it may reduce late mortality and improve quality of life in obese or overweight patients.

Reducing Prosthesis-Patient Mismatch With Edwards Magna Prosthesis for Aortic Valve Replacement.

Science.gov (United States)

Kume, Yuta; Fujita, Tomoyuki; Fukushima, Satsuki; Hata, Hiroki; Shimahara, Yusuke; Matsumoto, Yorihiko; Yamashita, Kizuku; Kobayashi, Junjiro

2017-03-24

Prosthesis-patient mismatch (PPM) is associated with increased mid-term and long-term mortality rates after aortic valve replacement (AVR). This study aimed to evaluate the efficacy of the Carpentier-Edwards Perimount Magna and Magna Ease (CEPMs) aortic bioprostheses to reduce the incidence of PPM.Methods and Results:Altogether, 282 consecutive patients (113 women, mean age 69.9±9.9 years) underwent AVR with a CEPMs between 2008 and 2015. They were divided into 3 groups based on the risk of PPM as a result of their body surface area and aortic annular diameter (BSA/AnnD ratio): low-risk (LR) group: 0.64±0.05 m 2 /cm (n=94); medium-risk (MR) group: 0.73±0.02 m 2 /cm (n=94); high-risk (HR) group: 0.83±0.05 m 2 /cm (n=94). The 30-day mortality rate was 0.4%. The 5-year actuarial survival rates were 93.2%, 92.3%, and 94.8% for groups LR, MR, and HR, respectively. No explants as a result of structural valve deterioration occurred. No patients showed severe PPM, defined as a measured effective orifice area index (EOAI) <0.65 cm 2 /m 2 . Although there were significant (P<0.05) differences in EOAI (0.98±0.2, 0.90±0.21, and 0.88±0.1 cm 2 /m 2 among the LR, MR, and HR groups, respectively), the corresponding transvalvular mean pressure gradients (13.0±5.5, 12.3±4.0, 12.7±5.3 mmHg) and regression rates of the left ventricular mass (29.8%, 28.7%, 28.9%) were similar among groups. CEPMs provide low surgical risk and reduce the risks of PPM, even in HR patients, with excellent hemodynamics.

Percutaneous closure of paravalvular leaks after transcatheter aortic valve implantation with Edwards SAPIEN prosthesis: a report of two cases.

Science.gov (United States)

Estévez-Loureiro, Rodrigo; Salgado-Fernández, Jorge; Vázquez-González, Nicolás

2013-02-01

Significant periprosthetic aortic regurgitation after transcatheter aortic valve implantation with Edwards SAPIEN prosthesis has become a major concern of this technique given its association with impaired survival. We report the successful closure of such defects using vascular occlusion devices with significant improvement in clinical status of patients.

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

Science.gov (United States)

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.

Comparative study between CardiaMed valves (freely floating valve leaflets versus St. Jude Medical (fixed valve leaflets in mitral valve replacement surgery

Directory of Open Access Journals (Sweden)

Mostafa Ahmed

2017-09-01

Conclusions: CardiaMed freely floating leaflet prostheses showed good hemodynamic characteristics. The prosthesis adequately corrects hemodynamics and is safe and no worse than the St. Jude Medical valve in the mitral valve position.

Recurrent infarctions due to a dome-shaped pannus above the mitral valve prosthesis.

Science.gov (United States)

Kasahara, Hirofumi; Inoue, Yoshito; Suzuki, Satoru

2016-01-01

This report describes a unique case of a 56-year-old female who suffered from recurrent stroke after double mechanical valve replacement. During the four years after the surgery, she remained in normal sinus rhythm, received adequate anticoagulation therapy, and no apparent left atrial thrombus was detected. She underwent redo surgery to prevent further stroke after fourth instance of cerebral infarction. Intraoperative findings revealed a 'dome-shaped' pannus formation covering the sewing ring of the mitral prosthesis circumferentially, probably leading to clot formation and repeated infarctions. She has been stroke free for three years after pannus resection.

Infective endocarditis following percutaneous pulmonary valve replacement

DEFF Research Database (Denmark)

Cheung, Gary; Vejlstrup, Niels; Ihlemann, Nikolaj

2013-01-01

Infective endocarditis (IE) following percutaneous pulmonary valve replacement (PPVR) with the Melody valve is rarely reported. Furthermore, there are challenges in this diagnosis; especially echocardiographic evidence of vegetation within the prosthesis may be difficult.......Infective endocarditis (IE) following percutaneous pulmonary valve replacement (PPVR) with the Melody valve is rarely reported. Furthermore, there are challenges in this diagnosis; especially echocardiographic evidence of vegetation within the prosthesis may be difficult....

Vent-induced prosthetic leaflet thrombosis treated by open-heart valve-in-valve implantation.

Science.gov (United States)

Stamm, Christof; Pasic, Miralem; Buz, Semih; Hetzer, Roland

2015-09-01

A patient required emergency mitral valve replacement and extracorporeal membrane oxygenation (ECMO) support for acute biventricular failure. The left ventricular (LV) vent inserted via the left upper pulmonary vein induced thrombotic immobilization of a prosthetic valve leaflet, with significant intra-prosthesis regurgitation after ECMO explantation. Therefore, the left atrium was opened on the beating heart during conventional extracorporeal circulation, all prosthesis leaflets were excised and a 29-mm expandable Edwards Sapien prosthesis was inserted within the scaffold of the original prosthesis under direct vision. This case illustrates the benefits and potential problems of LV venting on ECMO support, and a rapid and safe way of replacing the prosthesis leaflets in a critical situation. © The Author 2015. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

Consequence of patient substitution of nattokinase for warfarin after aortic valve replacement with a mechanical prosthesis

OpenAIRE

Elahi, Maqsood M.; Choi, Charles H.; Konda, Subbareddy; Shake, Jay G.

2015-01-01

This report describes a patient's self-substitution of nattokinase for the vitamin K antagonist warfarin after aortic valve replacement with a mechanical prosthesis. Nattokinase is an enzyme derived from a popular fermented soybean preparation in Japan (natto), which has fibrinolytic properties and is gaining popularity in nontraditional health journals and nonmedical health websites as an over-the-counter thrombolytic. After nearly a year of use of nattokinase without warfarin, the patient d...

Multidetector CT predictors of prosthesis-patient mismatch in transcatheter aortic valve replacement.

Science.gov (United States)

Freeman, Melanie; Webb, John G; Willson, Alexander B; Wheeler, Miriam; Blanke, Philipp; Moss, Robert R; Thompson, Christopher R; Munt, Brad; Norgaard, Bjarne L; Yang, Tae-Hyun; Min, James K; Poulsen, Steen; Hansson, Nicolaj C; Binder, Ronald K; Toggweiler, Stefan; Hague, Cameron; Wood, David A; Pibarot, Philippe; Leipsic, Jonathon

2013-01-01

Prosthesis-patient mismatch (PPM) is a predictor of mortality after aortic valve replacement (AVR). We examined whether accurate 3-dimensional annular sizing with multidetector CT (MDCT) is predictive of PPM after transcatheter AVR (TAVR). One hundred twenty-eight patients underwent MDCT then TAVR. Moderate PPM was defined as an indexed effective orifice area ≤0.85 cm²/m² and severe ≤0.65 cm²/m². MDCT annular measurements (area, short and long axis) were compared with the size of the selected transcatheter heart valve (THV) to obtain (1) the difference between prosthesis size and CT-measured mean annular diameter and (2) the percentage of undersizing or oversizing (calculated as 100 × [MDCT annular area--THV nominal area]/THV nominal area). In addition, the MDCT annular area was indexed to body surface area. These measures were evaluated as potential PPM predictors. We found that 42.2% of patients had moderate PPM and 9.4% had severe PPM. Procedural characteristics and in-hospital outcomes were similar between patients with or without PPM. THV undersizing of the mean aortic annulus diameter was not predictive of PPM (odds ratio [OR], 0.84; 95% CI, 0.65-1.07; P = .16; area under the receiver-operating characteristic curve [AUC], 0.58). THV undersizing of annular area was not predictive of PPM (OR, 0.96; 95% CI, 0.80-1.16; P = .69; AUC, 0.52). Indexed MDCT annular area was, however, predictive of PPM (OR, 0.24; 95% CI, 0.10-0.59; P < .001; AUC, 0.66). PPM is frequent after TAVR. Appropriate annular oversizing does not reduce the rate or severity of PPM. Patient annulus size mismatch, identified by indexed MDCT annular area, is a significant predictor of PPM. Copyright © 2013 Society of Cardiovascular Computed Tomography. Published by Elsevier Inc. All rights reserved.

Five-year results after valve replacement with the Björk-Shiley 70 degrees convexo-concave prosthesis.

Science.gov (United States)

Koldsland, S; Svennevig, J L; Abdelnoor, M; Aas, H; Semb, G

1992-01-01

In the 18 months up to July 1983, 120 Björk-Shiley convexo-concave prostheses with 70 degrees opening angle were implanted in 47 women and 61 men aged 19-78 (mean 58.6) years. The prosthetic valves were aortic in 65 cases, mitral in 23 and both aortic and mitral in 20 cases. Emergency operation was required in ten cases, and concomitant surgery was performed in 43 (39.8%). The early mortality was 5.5%. A follow-up study, comprising 498 patient years, revealed 73.1% 5-year survival. There were three mechanical failures of prosthesis, in one of which re-replacement was successful. Elective prosthesis replacement was performed in four other cases judged to be at high risk of strut fracture.

Doppler derived gradient of ST Jude Mechanical Prosthesis, early postoperative assessment

International Nuclear Information System (INIS)

Shaikh, A.H.; Hanif, B.; Adil, A.; Hashimi, S.; Qazi, H.A.; Mujtaba, I.

2010-01-01

Objective: To determine the doppler derived mean gradients of St Jude mechanical prosthesis in early postoperative period in patients undergoing valve replacement at a tertiary care cardiac centre. Methods: Medical records of 190 consecutive patients who underwent 233 mitral, aortic or dual (mitral and aortic) valve replacement by St Jude bileaflet mechanical prosthesis at Tabba Heart Institute, between March 2006 to December 2008 were reviewed. Doppler derived mean gradients were assessed predischarge and recorded. Results: There were 98 (51.5%) males and 92 (48.5%) females in the study cohort. The mean age was 40 +- 14 years. Of the total, 101 (53%) had mitral, 46 (24.2%) had aortic and 43 (22.6%) patients had dual valve replacement. Doppler derived mean gradient was assessed across 144 mitral and 89 aortic St Jude mechanical prosthesis. Doppler derived mean gradient for St Jude mitral prosthesis was 3.5 mm Hg and for St Jude aortic prosthesis was 10.2 mm Hg. Conclusions: The study determines baseline gradients across mitral and aortic St Jude mechanical prosthesis in our population. These can be used as reference gradients to assess St Jude prosthetic valve function in patients who did not have early postoperative doppler assessment. (author)

Developments in mechanical heart valve prosthesis

Indian Academy of Sciences (India)

Artificial heart valves are engineered devices used for replacing diseased or damaged natural valves of the heart. Most commonly used for replacement are mechanical heart valves and biological valves. This paper briefly outlines the evolution, designs employed, materials being used,. and important factors that affect the ...

Effect of Patient-Prosthesis Mismatch in Aortic Position on Late-Onset Tricuspid Regurgitation and Clinical Outcomes after Double Valve Replacement.

Science.gov (United States)

Lee, Seung Hyun; Youn, Young Nam; Chang, Byung Chul; Joo, Hyun Chel; Lee, Sak; Yoo, Kyung Jong

2017-09-01

Significant late-onset tricuspid regurgitation (TR) is unfortunately common after double valve replacement (DVR); however, its underlying factors remain undefined. We evaluated the effect of aortic patient-prosthesis mismatch (PPM) on late-onset TR and clinical outcomes after DVR. Of the 2392 consecutive patients who underwent aortic valve replacement between January 1990 and May 2014 at our institution, we retrospectively studied 462 patients who underwent DVR (excluding concomitant tricuspid valvular annuloplasty or replacement). Survival and freedom from grade >3 TR were compared between PPM (n=152) and non-PPM (n=310) groups using the Kaplan-Meier method. Although the overall survival rates were similar between the two groups at 5 and 10 years (95%, 91% vs. 96%, 93%, p=0.412), grade >3 TR-free survival was significantly lower in the PPM group (98%, 91% vs. 99%, 95%, p=0.014). Small body-surface area, atrial fibrillation, PPM, and subaortic pannus were risk factors for TR progression. However, aortic prosthesis size and trans-valvular pressure gradient were not significant factors for either TR progression or overall survival. Aortic PPM in DVR, regardless of mitral prosthesis size, was associated with late TR progression, but was not significantly correlated with overall survival. Therefore, we recommend careful echocardiographic follow-up for the early detection of TR progression in patients with aortic PPM in DVR. © Copyright: Yonsei University College of Medicine 2017

Direct right ventricular puncture for hemodynamic evaluation of a mechanical tricuspid valve prosthesis: a new indication for an old procedure.

Science.gov (United States)

Gibson, M A; Carell, E S

1997-11-01

The advent of transvenous right heart catheterization has relegated direct transthoracic right ventricular puncture largely to the role of "interesting historical footnote." However, in the case of a right ventricle that is "protected" by a mechanical tricuspid valve prosthesis, direct right ventricular puncture represents a reasonable alternative for obtaining accurate hemodynamic information.

Basaloid Squamous Cell Carcinoma: An Unusual Ball-Valve Laryngeal Obstruction

Directory of Open Access Journals (Sweden)

Sien Hui Tan

2015-05-01

Full Text Available Introduction: A rare case of basaloid squamous cell carcinoma (BSCC of the larynx, which has not been previously reported, is described. Case Report: A 60-year-old man was presented to the Otolaryngology Department with progressive dyspnoea and dysphagia to solids for over a period of 1 week. Direct laryngoscopy revealed a tumour at the laryngeal aspect of the epiglottis, which prolapsed into the laryngeal inlet each time the patient inspired. This resulted in an inspiratory stridor despite adequate glottic opening and normal mobility of the vocal cords.   Conclusion:  Therefore, in cases where a ball-valve lesion causes intermittent life-threatening airway obstruction, BSCC of the larynx, though rare, must be considered as a differential diagnosis.

Hemodynamic and clinical impact of prosthesis-patient mismatch after transcatheter aortic valve implantation.

Science.gov (United States)

Ewe, See Hooi; Muratori, Manuela; Delgado, Victoria; Pepi, Mauro; Tamborini, Gloria; Fusini, Laura; Klautz, Robert J M; Gripari, Paola; Bax, Jeroen J; Fusari, Melissa; Schalij, Martin J; Marsan, Nina Ajmone

2011-10-25

This study examined the mid-term hemodynamic and clinical impact of prosthesis-patient mismatch (PPM) in patients undergoing transcatheter aortic valve implantation (TAVI) with balloon-expandable valves. PPM can be observed after aortic valve surgery. However, little is known about the incidence of PPM in patients undergoing TAVI. Echocardiography and clinical assessment were performed in 165 patients at baseline, before hospital discharge, and at 6 months after TAVI. PPM was defined as an indexed effective orifice area ≤0.85 cm(2)/m(2). Thirty patients (18.2%) showed PPM before hospital discharge. At baseline, patients with PPM had a larger body surface area (1.84 ± 0.18 m(2) vs. 1.73 ± 0.18 m(2), p = 0.003) and a greater severity of aortic stenosis (indexed valve area 0.35 ± 0.09 cm(2)/m(2) vs. 0.40 ± 0.10 cm(2)/m(2), p = 0.005) than patients without PPM. Patients with PPM demonstrated a slower and smaller reduction in mean transaortic gradient, limited left ventricular (LV) mass regression, and left atrial volume reduction over 6 months compared with patients without PPM. LV filling pressure, measured by E/e', tended to remain elevated in patients with PPM. Importantly, a higher proportion of patients with PPM did not improve in New York Heart Association functional class compared with patients without PPM (36.7% vs. 1.5%, p < 0.001), although major adverse valve-related and cardiovascular events did not differ between the 2 groups. PPM may be observed after TAVI and when present may be accompanied by less favorable changes in transvalvular hemodynamics, limited LV mass regression, persistent elevated LV filling pressure, and less improvement in clinical functional status. Copyright © 2011 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Can Perceval sutureless valve reduce the rate of patient-prosthesis mismatch?†.

Science.gov (United States)

Belluschi, Igor; Moriggia, Stefano; Giacomini, Andrea; Del Forno, Benedetto; Di Sanzo, Stefania; Blasio, Andrea; Scafuri, Antonio; Alfieri, Ottavio

2017-06-01

The aim of this study is to compare the theoretical incidence of patient-prosthesis mismatch (PPM) in patients undergoing a sutureless or a sutured aortic valve replacement using an exact statistical matching. Between May 2012 and March 2016, 65 patients with severe symptomatic aortic stenosis underwent a sutureless aortic valve replacement with the Perceval bioprosthesis in 2 centres. Moreover, 177 aortic valve replacements with conventional sutured bioprosthesis were performed between August 2003 and September 2015. Perceval and sutured patients were 1:1 exactly matched for sex and body surface area (BSA), resulting in 62 couples (sutureless: BSA 1.77 ± 0.16 m 2 , female 62.9% vs sutured: BSA 1.77 ± 0.15 m 2 , female 62.9%). After matching, the indexed effective orifice area was 1.50 ± 0.18 cm 2 /m 2 and 0.81 ± 0.19 cm 2 /m 2 in the sutureless and the sutured group, respectively ( P  < 0.001). No PPM occurred in patients who received a Perceval bioprosthesis ( n  = 62). In the sutured group ( n  = 62), 38 patients (61.3%) developed a PPM, which was moderate in 41.9% ( n  = 26) and severe in 19.4% ( n  = 12) ( P  < 0.001). The indexed effective orifice area of the sutureless group was significantly larger than in the sutured one. The incidence of PPM with the conventional sutured biprosthesis was 61.3%, while it decreases to 0% in the sutureless group. No PPM was reported in the sutureless valve group. Therefore, the Perceval sutureless valve provides larger effective orifice areas compared to the sutured conventional bioprosthesis and could be considered as a good option to reduce the risk of a PPM. © The Author 2017. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

Choice of valve prosthesis in a rare clinical condition: aortic stenosis due to alkaptonuria.

Science.gov (United States)

Thakur, Sameer; Markman, Phuong; Cullen, Hugh

2013-10-01

Alkaptonuria is a rare inherited disorder of tyrosine metabolism, which results in deposition of homogentisic acid in the connective tissues. The accumulation of homogentisic acid in connective tissue causes the syndrome known as ochronosis, which is typically manifested by skin pigmentation, degenerative arthropathy and discolouration of urine. Cardiovascular involvement is a much less common complication of alkaptonuria but poses a greater risk to the patient's health. We present the case of a 65 year-old man with aortic stenosis and a previous diagnosis of alkaptonuria who underwent successful aortic valve replacement with a mechanical prosthesis. Crown Copyright © 2013. Published by Elsevier B.V. All rights reserved.

Dosimetric evaluation in mammary glands radiotherapy using expansive prosthesis with magnetic valve; Avaliacao dosimetrica de tratamentos de radioterapia de mama usando proteses expansivas com valvula magnetica

Energy Technology Data Exchange (ETDEWEB)

Lizar, J.C.; Pavoni, J.F.; Baffa, O. [Universidade de Sao Paulo (USP), Ribeirao Preto (Brazil); Krutman, Y. [Rabin Medical Center (RMC), (Israel)

2016-07-01

This work aims to verify the influence on dose distribution that the expansive prosthesis (SILIMED/470), containing a magnetic valve, generates in radiotherapy postoperative treatment of patients who have undergone mastectomy. (author)

Aortic annulus eccentricity before and after transcatheter aortic valve implantation: Comparison of balloon-expandable and self-expanding prostheses

International Nuclear Information System (INIS)

Schuhbaeck, Annika; Weingartner, Christina; Arnold, Martin; Schmid, Jasmin; Pflederer, Tobias; Marwan, Mohamed; Rixe, Johannes; Nef, Holger; Schneider, Christian; Lell, Michael; Uder, Michael; Ensminger, Stephan; Feyrer, Richard; Weyand, Michael; Achenbach, Stephan

2015-01-01

Highlights: • Post-implant geometry of catheter-based aortic valve prostheses is influenced by aortic valve calcification. • Balloon-expandable prostheses are more circular as compared to self-expanding prostheses. • The impact of post-implant geometry on valve function needs to be investigated. - Abstract: Introduction: The geometry of the aortic annulus and implanted transcatheter aortic valve prosthesis might influence valve function. We investigated the influence of valve type and aortic valve calcification on post-implant geometry of catheter-based aortic valve prostheses. Methods: Eighty consecutive patients with severe aortic valve stenosis (mean age 82 ± 6 years) underwent computed tomography before and after TAVI. Aortic annulus diameters were determined. Influence of prosthesis type and degree of aortic valve calcification on post-implant eccentricity were analysed. Results: Aortic annulus eccentricity was reduced in patients after TAVI (0.21 ± 0.06 vs. 0.08 ± 0.06, p < 0.0001). Post-TAVI eccentricity was significantly lower in 65 patients following implantation of a balloon-expandable prosthesis as compared to 15 patients who received a self-expanding prosthesis (0.06 ± 0.05 vs. 0.15 ± 0.07, p < 0.0001), even though the extent of aortic valve calcification was not different. After TAVI, patients with a higher calcium amount retained a significantly higher eccentricity compared to patients with lower amounts of calcium. Conclusions: Patients undergoing TAVI with a balloon-expandable prosthesis show a more circular shape of the implanted prosthesis as compared to patients with a self-expanding prosthesis. Eccentricity of the deployed prosthesis is affected by the extent of aortic valve calcification

Self-contained inflatable penile prosthesis: magnetic resonance appearance

International Nuclear Information System (INIS)

Levin, M.F.; Munk, P.L.; Vellet, A.D.; Chin, J.L.

1994-01-01

The appearance of an inflatable penile prosthesis, visualized on a short tau inversion recovery sequence, is reported, in a patient who had magnetic resonance imaging for pelvic pain subsequent to radical cystoprostatectomy for bladder carcinoma. With suppression of adjacent fat signal, the prosthesis is well delineated from adjacent structures. The fluid-containing cylinders of the prosthesis are of very bright signal intensity, with the relief valve assembly of low signal intensity. 5 refs., 2 figs

Aortic valve replacement

DEFF Research Database (Denmark)

Kapetanakis, Emmanouil I; Athanasiou, Thanos; Mestres, Carlos A

2008-01-01

mortality were collected. Group analysis by patient geographic distribution and by annular diameter of the prosthesis utilized was conducted. Patients with a manufacturer's labeled prosthesis size > or = 21 mm were assigned to the 'large' aortic size subset, while those with a prosthesis size ... differences in the distribution of either gender or BSA. In the multivariable model, south European patients were seven times more likely to receive a smaller-sized aortic valve (OR = 6.5, 95% CI = 4.82-8.83, p

A 29-Year-Old Harken Disk Mitral Valve

Science.gov (United States)

Hsi, David H.; Ryan, Gerald F.; Taft, Janice; Arnone, Thomas J.

2003-01-01

An 81-year-old woman was evaluated for prosthetic mitral valve function. She had received a Harken disk mitral valve 29 years earlier due to severe mitral valve disease. This particular valve prosthesis is known for premature disk edge wear and erosion. The patient's 2-dimensional Doppler echocardiogram showed the distinctive appearance of a disk mitral valve prosthesis. Color Doppler in diastole showed a unique crown appearance, with initial flow acceleration around the disk followed by convergence to laminar flow in the left ventricle. Cineradiographic imaging revealed normal valve function and minimal disk erosion. We believe this to be the longest reported follow-up of a surviving patient with a rare Harken disk valve. We present images with unique echocardiographic and cineangiographic features. (Tex Heart Inst J 2003;30:319–21) PMID:14677746

Prosthesis-patient mismatch after transcatheter aortic valve implantation with the Medtronic-Corevalve bioprosthesis.

Science.gov (United States)

Jilaihawi, Hasan; Chin, Derek; Spyt, Tomasz; Jeilan, Mohamed; Vasa-Nicotera, Mariuca; Bence, Johan; Logtens, Elaine; Kovac, Jan

2010-04-01

Prosthesis-patient mismatch (P-PM) is an important determinant of morbidity and mortality following open aortic valve replacement. The aims of this study were to report its incidence and determinants following transcatheter aortic valve implantation (TAVI) with the Corevalve bioprosthesis, which have-thus far-not been described. Patients with severe calcific aortic stenosis received TAVI with the Corevalve bioprosthesis via transfemoral route. Following TAVI, moderate P-PM was defined as indexed aortic valve effective orifice area (AVAi) Clinical, echocardiographic, and procedural factors relating to P-PM were studied. Optimal device position was defined on fluoroscopy as final position of the proximal aspect of the Corevalve stent frame 5-10 mm below the native aortic annulus. Between January 2007 and January 2009, 50 consecutive patients underwent TAVI in a single centre with the Corevalve bioprosthesis. Mean age was 82.8 years (SD 5.9; 70-93) and 48% were male. P-PM occurred in 16 of 50 cases (32%). Optimal position was achieved in 50% of cases. P-PM was unrelated to age, annulus size, LVOT size, Corevalve size, aortic angulation, ejection fraction, and sex. It was inversely correlated to optimal position (Spearman rho r = -0.34, P = 0.015). Those with optimal positioning had a 16% incidence of P-PM relative to 48% of those with suboptimal positioning (Pearson chi(2) P = 0.015). The incidence of P-PM following TAVI with the Corevalve bioprosthesis is compared favourably with that seen after AVR with conventional open stented bioprostheses and its occurrence is influenced by device positioning.

A Study of the Interaction between Batting Cage Baseballs and Pitching Machine

Directory of Open Access Journals (Sweden)

Patrick Drane

2018-02-01

Full Text Available Batting cage pitching machines are widely used across the sports of baseball and softball for training and recreation purposes. The balls are specifically designed for the machines and for the environment to ensure high durability and typically do not have seams. Polymeric foam balls are widely used in these automated pitching machines for batting practice in a cage environment and are similar in weight and size compared with the regulation balls used in leagues. The primary objective of this paper is to characterize the polymeric balls and their interaction with the pitching machine. The paper will present measured ball properties and measured relationships between various pitching machine parameters such as wheel speed, and the ratio of wheel speeds on the ball exit velocity and rotation. This paper will also characterize some of the effects of wear on the baseballs and wheels from their prolonged use.

Pannus Formation Leads to Valve Malfunction in the Tricuspid Position 19 Years after Triple Valve Replacement.

Science.gov (United States)

Alskaf, Ebraham; McConkey, Hannah; Laskar, Nabila; Kardos, Attila

2016-06-20

The Medtronic ATS Open Pivot mechanical valve has been successfully used in heart valve surgery for more than two decades. We present the case of a patient who, 19 years following a tricuspid valve replacement with an ATS prosthesis as part of a triple valve operation following infective endocarditis, developed severe tricuspid regurgitation due to pannus formation.

Models for dynamic analysis of backup ball bearings of an AMB-system

Science.gov (United States)

Halminen, Oskari; Aceituno, Javier F.; Escalona, José L.; Sopanen, Jussi; Mikkola, Aki

2017-10-01

Two detailed models of backup bearing are introduced for dynamic analysis of the dropdown event of a rotor supported by an active magnetic bearing (AMB). The proposed two-dimensional models of the backup bearings are based on a multibody approach. All parts of the bearing are modeled as rigid bodies with geometrical surfaces and the bodies interact with each other through contact forces. The first model describes a backup bearing without a cage, and the second model describes a backup bearing with a cage. The introduced models, which incorporate a realistic elastic contact model, are compared with previously presented simplified models through parametric study. In order to ensure the durability of backup bearings in challenging applications where ball bearings with an oversized bore are necessary, analysis of the forces affecting the bearing's cage and balls is required, and the models introduced in this work assist in this task as they enable optimal properties for the bearing's cage and balls to be found.

Prosthesis-patient mismatch

Directory of Open Access Journals (Sweden)

Philippe Pibarot

2011-04-01

Full Text Available Prosthesis-patient mismatch (PPM is present when the effective orifice area of the inserted prosthetic valve is too small in relation to body size. Its main hemodynamic consequence is to generate higher than expected gradients through normally functioning prosthetic valves. The purpose of this review is to present an update on the present state of knowledge with regards to diagnosis, prognosis and prevention of PPM. PPM is a frequent occurrence (20%–70% of aortic valve replacements that has been shown to be associated with worse hemodynamics, less regression of left ventricular hypertrophy, more cardiac events, and lower survival. Moreover, as opposed to most other risk factors, PPM can largely be prevented by using a prospective strategy at the time of operation.

Dysfunction of an On-X Heart Valve by Pannus.

Science.gov (United States)

Abad, Cipriano; Urso, Stefano; Gomez, Elsa; De la Vega, Maria

2016-09-01

A 68-year-old woman with a history of previous double-valve replacement with On-X mechanical heart valves presented with clinical, echocardiographic and cardiac catheterization signs of obstruction of the On-X tricuspid heart valve prosthesis. The patient was successfully reoperated, but at surgery the valve was seen to be invaded by an abnormal overgrowth of pannus that blocked one of the leaflets. A small amount of non-obstructive fresh thrombus was also observed. The valve was successfully replaced with a biological heart valve prosthesis. The patient was discharged home, and is doing well four months after the operation, when echocardiography demonstrated normal function in the tricuspid valve. The present case represents the first ever report of pannus formation and subsequent dysfunction in an On-X heart valve, and also the first case of tricuspid valve malfunction and obstruction using this type of heart valve substitute.

Valve-sparing aortic root replacement†.

Science.gov (United States)

Koolbergen, David R; Manshanden, Johan S J; Bouma, Berto J; Blom, Nico A; Mulder, Barbara J M; de Mol, Bas A J M; Hazekamp, Mark G

2015-02-01

To evaluate our results of valve-sparing aortic root replacement and associated (multiple) valve repair. From September 2003 to September 2013, 97 patients had valve-sparing aortic root replacement procedures. Patient records and preoperative, postoperative and recent echocardiograms were reviewed. Median age was 40.3 (range: 13.4-68.6) years and 67 (69.1%) were male. Seven (7.2%) patients were younger than 18 years, the youngest being 13.4 years. Fifty-four (55.7%) had Marfan syndrome, 2 (2.1%) other fibrous tissue diseases, 15 (15.5%) bicuspid aortic valve and 3 (3.1%) had earlier Fallot repair. The reimplantation technique was used in all, with a straight vascular prosthesis in 11 (26-34 mm) and the Valsalva prosthesis in 86 (26-32 mm). Concomitant aortic valve repair was performed in 43 (44.3%), mitral valve repair in 10 (10.3%), tricuspid valve repair in 5 (5.2%) and aortic arch replacement in 3 (3.1%). Mean follow-up was 4.2 ± 2.4 years. Follow-up was complete in all. One 14-year old patient died 1.3 years post-surgery presumably of ventricular arrhythmia. One patient underwent reoperation for aneurysm of the proximal right coronary artery after 4.9 years and 4 patients required aortic valve replacement, 3 of which because of endocarditis after 0.1, 0.8 and 1.3 years and 1 because of cusp prolapse after 3.8 years. No thrombo-embolic complications occurred. Mortality, root reoperation and aortic regurgitation were absent in 88.0 ± 0.5% at 5-year follow-up. Results of valve-sparing root replacement are good, even in association with a high incidence of concomitant valve repair. Valve-sparing aortic root replacement can be performed at a very young age as long as an adult size prosthesis can be implanted. © The Author 2014. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

Management of long span partially edentulous maxilla with fixed removable denture prosthesis.

Science.gov (United States)

Jeyavalan, Mahilan I; Narasimman, M; Venkatakrishnan, C J; Philip, Jacob M

2012-07-01

Restoration of a long span partially edentulous maxilla with tooth supported prosthesis is challenging because of inherent anatomic limitations and unfavourable biomechanics present after the loss of teeth. A tooth supported fixed-removable prosthesis is a treatment option for restoration of such long span partially edentulous maxillary arches. This prosthesis meets the requirements for esthetics, phonetics, comfort, and hygiene, as well as favourable biomechanical stress distribution to the remaining natural tooth abutments. This article presents a procedure for fabrication of a fixed-removable prosthesis that has cement-retained custom cast bar metal substructure and a ball attachment retained removable superstructure prosthesis.

Afebrile Pannus-Induced Blood Culture-Negative Mechanical Valve Endocarditis.

Science.gov (United States)

Matsukuma, Seiji; Eishi, Kiyoyuki; Tanigawa, Kazuyoshi; Miura, Takashi; Matsumaru, Ichiro; Hisatomi, Kazuki; Tsuneto, Akira

2016-12-01

The diagnosis of prosthetic valve endocarditis may be challenging in patients with an atypical clinical presentation. Virtually all infections associated with mechanical prosthetic valves are localized to the prosthesis-tissue junction at the sewing ring and are accompanied by tissue destruction around the prosthesis. Because the orifice of the mechanical prosthetic valve is made of metal and pyrolytic carbon, which do not enable the adherence of microorganisms, any vegetation originating from the interior of the valve orifice is usually rare. Here we present a rare case of pannus-induced mechanical prosthetic valve endocarditis that was difficult to diagnose. Copyright © 2016 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

Attachment-retained gingival prosthesis for implant-supported fixed dental prosthesis in the maxilla: a clinical report.

Science.gov (United States)

Aparecida de Mattias Sartori, Ivete; Uhlendorf, Yuri; Padovan, Luiz Eduardo Marques; Junior, Paulo Domingos Ribeiro; Melo, Ana Cláudia Moreira; Tiossi, Rodrigo

2014-12-01

The rehabilitation of edentulous maxillae is a complex procedure due to the involvement of esthetic and functional requirements. A trial maxillary denture can be used to identify the need for adequate upper lip support when replacing removable complete dentures by implant-fixed dental prostheses. This clinical report describes the outcome of the rehabilitation of an edentulous atrophic maxilla with unfavorable maxillomandibular relationship and deficient upper lip support. A trial denture was fabricated and used to diagnose the need for a prosthesis capable of restoring the upper lip support. The reduced upper lip support was also confirmed by a lateral cephalogram. The patient was rehabilitated by an implant-fixed dental prosthesis associated with an attachment-retained gingival prosthesis. The case presented shows that when loss of upper lip support is detected and the patient does not wish to undergo further surgical reconstruction procedure, the retention of a gingival prosthesis using a ball attachment is a satisfactory treatment option. © 2014 by the American College of Prosthodontists.

Patient-prosthesis mismatch after transapical aortic valve implantation: incidence and impact on survival.

Science.gov (United States)

Kukucka, Marian; Pasic, Miralem; Dreysse, Stephan; Mladenow, Alexander; Habazettl, Helmut; Hetzer, Roland; Unbehaun, Axel

2013-02-01

Transcatheter aortic valve implantation (TAVI) has become an important therapeutic option for high-risk patients with severe aortic valve stenosis. Patient-prosthesis mismatch (P-PM) is an important determinant of morbidity and mortality after open aortic valve replacement. The objective of our study was to evaluate P-PM incidence and its impact on survival in a large cohort of patients treated with TAVI. We retrospectively analyzed transesophageal echocardiographic data of 278 consecutive patients (Society of Thoracic Surgeons score 18.5 ± 15.3, age 80 ± 8 years) who underwent transapical TAVI with Edwards Sapien valves between April 2008 and March 2011. Effective orifice area was calculated using the continuity equation and indexed with body surface area (iEOA). P-PM was stratified as severe (iEOA < 0.65 cm(2)/cm(2)) and moderate (iEOA, 0.65-0.85 cm(2)/m(2)). Midterm survival (up to 30 months) was analyzed by Kaplan-Meier curves and log-rank tests. There was no P-PM in 181 (65.1%) patients; moderate P-PM was found in 76 (27.3%) patients and severe P-PM in 21 (7.6%). Thirty-day survival was 96.0%, 97.3%, and 90.5%. The 3-month survival was 91%, 90%, and 66%, respectively (P = .0013). Combination of severe P-PM with peak pressure gradients greater than 10 mm Hg further reduced the 3-month survival to 48%. Additionally, mean survival time in patients with an ejection fraction less than 50% was significantly shorter than in patients with an ejection fraction greater than 50% (20.8 ± 1.5 vs 24.1 ± 0.8 months; P = .027). P-PM is found in patients undergoing transapical TAVI. Severe mismatch is accompanied by high early mortality, especially when combined with increased pressure gradients. Copyright © 2013 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

Management of long span partially edentulous maxilla with fixed removable denture prosthesis

Directory of Open Access Journals (Sweden)

Mahilan I Jeyavalan

2012-01-01

Full Text Available Restoration of a long span partially edentulous maxilla with tooth supported prosthesis is challenging because of inherent anatomic limitations and unfavourable biomechanics present after the loss of teeth. A tooth supported fixed-removable prosthesis is a treatment option for restoration of such long span partially edentulous maxillary arches. This prosthesis meets the requirements for esthetics, phonetics, comfort, and hygiene, as well as favourable biomechanical stress distribution to the remaining natural tooth abutments. This article presents a procedure for fabrication of a fixed-removable prosthesis that has cement-retained custom cast bar metal substructure and a ball attachment retained removable superstructure prosthesis.

Prosthesis-patient mismatch due to small ring annuloplasty in patients with degenerative mitral insufficiency.

Science.gov (United States)

Kawamoto, Naonori; Fujita, Tomoyuki; Hata, Hiroki; Shimahara, Yusuke; Sato, Shunsuke; Kobayashi, Junjiro

2016-08-01

Avoidance of prosthesis-patient mismatch (PPM) is important when selecting a mitral valve prosthesis. This study investigated the effect of PPM after small ring mitral valve annuloplasty on postoperative hemodynamics and the clinical course. This study retrospectively reviewed 227 patients with symptomatic severe mitral insufficiency (MI) who underwent mitral valve repair for degenerative MI using an Edwards ring or band (size: 26-32mm) between 2003 and 2012. Echocardiography was performed postoperatively and at follow-up to evaluate cardiac function, including residual MI, mean transmitral pressure gradient, left atrial diameter (LAD), and tricuspid regurgitant pressure gradient (TRPG). There were no operative deaths. Actuarial freedom from major adverse cardiac events was 91% at 10 years. The postoperative MI grade was not significantly different between different sizes of prosthesis (26mm, 0.67±0.8; 28mm, 0.73±0.9; 30mm, 0.85±0.9; 32mm, 0.3±0.6). LAD and TRPG were significantly lower for each size of prosthesis at follow-up (all pbody surface area received a significantly smaller prosthesis (pprosthesis than in patients with a larger size of prosthesis. Thirty-three patients had a follow-up transmitral pressure gradient ≥5mmHg. The follow-up LAD was larger in patients with a transmitral pressure gradient prosthesis. However, use of a smaller prosthesis may result in a higher mean transmitral pressure gradient, and may inhibit reverse remodeling of the left atrium. Therefore, PPM should be avoided. Copyright © 2015 Japanese College of Cardiology. Published by Elsevier Ltd. All rights reserved.

Transcatheter valve-in-valve implantation due to severe aortic regurgitation in a degenerated aortic homograft

DEFF Research Database (Denmark)

Olsen, Lene Kjaer; Engstrøm, Thomas; Søndergaard, Lars

2009-01-01

Transcatheter aortic valve implantation (TAVI) in severe aortic stenosis has proven to be a feasible and effective treatment modality for inoperable patients. Until now, neither aortic regurgitation nor degenerated bioprostheses has been an indication for TAVI. However, this article reports...... a successful valve-in-valve implantation of a CoreValve aortic valve prosthesis through the right subclavian artery in a case of severe aortic regurgitation within a degenerated aortic homograft. The case exemplifies the possibilities of expanding the indications for TAVI, as well as other vascular access...

Elective removal of convexo-concave Björk-Shiley valves.

Science.gov (United States)

Rajesh, P B; Smith, G H; Lawford, P V; Black, M M

1994-08-01

Replacement has been an accepted method for treating advanced cardiac valvular disease for more than 25 years. However, the perfect prosthesis has yet to be developed, judging by the number of devices available. A prosthesis that initially appears promising may cause problems in due course, and indeed some devices have been modified or withdrawn from clinical use. A notable example of a prosthetic valve that has give problems is the Björk-Shiley convexo-concave prosthesis, some models of which have undergone mechanical failure due to strut fracture. We report the elective removal of such a valve and the subsequent examination of the prosthesis. The results of this examination suggest that a policy of elective removal is justified.

Predictors and Outcomes of Prosthesis-Patient Mismatch After Aortic Valve Replacement.

Science.gov (United States)

Dayan, Victor; Vignolo, Gustavo; Soca, Gerardo; Paganini, Juan Jose; Brusich, Daniel; Pibarot, Philippe

2016-08-01

This study sought to evaluate predictors of prosthesis-patient mismatch (PPM) and its association with the risk of perioperative and overall mortality. PPM is associated with increased mid- and long-term mortality after surgical aortic valve replacement. Conflicting results have been reported with regard to its association with perioperative mortality. Databases were searched for studies published between 1965 and 2014. Main outcomes of interest were perioperative mortality and overall mortality. The search yielded 382 studies for inclusion. Of these, 58 articles were analyzed and their data extracted. The total number of patients included was 40,381 (39,568 surgical aortic valve replacement and 813 transcatheter aortic valve replacement). Perioperative (odds ratio: 1.54; 95% confidence interval: 1.25 to 1.91) and overall (i.e., perioperative and post-operative) mortality (hazard ratio: 1.26; 95% confidence interval: 1.16 to 1.36) was increased in patients with PPM. The impact of PPM on mortality was higher in those studies in which the mean age of the patients was body mass index (>28 kg/m(2)) compared with those with lower index. Predictors of PPM were older age, female sex, hypertension, diabetes, renal failure, larger body surface area, larger body mass index, and the utilization of a bioprosthesis. PPM increases perioperative and overall mortality proportionally to its severity. The identification of predictors for PPM may be useful to identify patients who are at higher risk for PPM. The findings of this study support the implementation of strategies to prevent PPM especially in patients <70 years of age and/or with concomitant coronary artery bypass graft. Copyright © 2016 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Aortic valve replacement: is there an implant size variation across Europe?

Science.gov (United States)

Kapetanakis, Emmanouil I; Athanasiou, Thanos; Mestres, Carlos A; Nashef, Samer A M; Aagaard, Jan; Moritz, Anton; Van Ingen, Gerrit; Chronidou, Fany; Palatianos, George; Alivizatos, Peter A; Stavridis, George T

2008-03-01

Prompted by anecdotal evidence and observations by surgeons, an investigation was undertaken into the potential differences in implanted aortic valve prosthesis sizes, during aortic valve replacement (AVR) procedures, between northern and southern European countries. A multi-institutional, non-randomized, retrospective analysis was conducted among 2,932 patients who underwent AVR surgery at seven tertiary cardiac surgery centers throughout Europe. Demographic and perioperative variables including valve size and type, body surface area (BSA) and early mortality were collected. Group analysis by patient geographic distribution and by annular diameter of the prosthesis utilized was conducted. Patients with a manufacturer's labeled prosthesis size > or = 21 mm were assigned to the 'large' aortic size subset, while those with a prosthesis size < 21 mm were assigned to the 'small' aortic size subset. Effective orifice area indices were calculated for all patients to assess the geographic distribution of patient-prosthesis mismatch. Univariable and multivariable logistic regression analyses adjusting for possible confounding variables were performed. Prostheses with diameter < 21 mm were implanted at almost twice the rate in southern Europe compared to the north (56.4% versus 26.7%, p < 0.01). The mean valve size was also smaller in southern compared to northern European patients (21.6 +/- 2.1 mm versus 23.4 +/- 2.2 mm, p < 0.01). There were no regional differences in the distribution of either gender or BSA. In the multivariable model, south European patients were seven times more likely to receive a smaller-sized aortic valve (OR = 6.5, 95% CI = 4.82-8.83, p < 0.01), and thus the odds of developing patient-prosthesis mismatch were increased two-fold in southern European patients (OR = 1.9, 95% CI = 1.25-2.80, p = 0.02). However, neither geographic distribution nor valve size were significantly associated with operative mortality. The study results demonstrated

Heavy gas valves

Energy Technology Data Exchange (ETDEWEB)

Steier, L [Vereinigte Armaturen Gesellschaft m.b.H., Mannheim (Germany, F.R.)

1979-01-01

Heavy gas valves must comply with special requirements. Apart from absolute safety in operation there are stringent requirements for material, sealing and ease of operation even in the most difficult conditions. Ball valves and single plate pipe gate valves lateral sealing rings have a dual, double sided sealing effect according to the GROVE sealing system. Single plate gate valves with lateral protective plates are suitable preferably for highly contaminated media. Soft sealing gate valves made of cast iron are used for low pressure applications.

Design and Characterization of a Quasi-Passive Pneumatic Foot-Ankle Prosthesis.

Science.gov (United States)

Lee, Jeffrey D; Mooney, Luke M; Rouse, Elliott J

2017-07-01

The majority of commercially available passive prosthetic feet are not capable of providing joint mechanics that match that of the intact human ankle. Due to their cantilever design, their stiffness characteristics contrast with what has been observed in the biological ankle, namely, an increase in stiffness during the stance phase of walking. In this paper, we introduce the design and control of a pneumatic foot-ankle prosthesis that attempts to provide biomimetic mechanics. The prosthesis is comprised of a pneumatic cylinder in series with a fiberglass leaf spring, and a solenoid valve to control the flow of air between the two sides of the cylinder. The solenoid valve acts as a mechanical clutch, enabling resetting of the ankle's equilibrium position. By adjusting the pressure inside the cylinder, the prosthesis can be customized to provide a range of ankle mechanics. A mechanical testing machine is used to compare the torque-angle curve of the pneumatic prosthesis with a low-profile passive prosthetic foot. Finally, data are presented of one transtibial amputee walking with the prosthesis at 1.2 m/s. The testing shows that the pneumatic prosthesis is capable of providing an appropriate range of motion as well a maximum torque of 94 Nm, while returning approximately 11.5 J of energy.

241-AN-A valve pit manifold valves and position indication acceptance test procedure

Energy Technology Data Exchange (ETDEWEB)

VANDYKE, D.W.

1999-08-25

This document describes the method used to test design criteria for gear actuated ball valves installed in 241-AN-A Valve Pit located at 200E Tank Farms. The purpose of this procedure is to demonstrate the following: Equipment is properly installed, labeled, and documented on As-Built drawings; New Manifold Valves in the 241-AN-A Valve Pit are fully operable using the handwheel of the valve operators; New valve position indicators on the valve operators will show correct valve positions; New valve position switches will function properly; and New valve locking devices function properly.

Prosthesis-patient mismatch after transcatheter aortic valve implantation: impact of 2D-transthoracic echocardiography versus 3D-transesophageal echocardiography.

Science.gov (United States)

da Silva, Cristina; Sahlen, Anders; Winter, Reidar; Bäck, Magnus; Rück, Andreas; Settergren, Magnus; Manouras, Aristomenis; Shahgaldi, Kambiz

2014-12-01

To investigate the role of 2D-transthoracic echocardiography (2D-TTE) and 3D-transesophageal echocardiography (3D-TEE) in the determination of aortic annulus size prior transcatheter aortic valve implantation (TAVI) and its' impact on the prevalence of patient prosthesis mismatch (PPM). Echocardiography plays an important role in measuring aortic annulus dimension in patients undergoing TAVI. This has great importance since it determines both eligibility for TAVI and selection of prosthesis type and size, and can be potentially important in preventing an inadequate ratio between the prosthetic valvular orifice and the patient's body surface area, concept known as prosthesis-patient mismatch (PPM). A total of 45 patients were studied pre-TAVI: 20 underwent 3D-TEE (men/women 12/8, age 84.8 ± 5.6) and 25 2D-TTE (men/women 9/16, age 84.4 ± 5.4) in order to measure aortic annulus diameter. The presence of PPM was assessed before hospital discharge and after a mean period of 3 months. Moderate PPM was defined as indexed aortic valve area (AVAi) ≤ 0.85 cm(2)/m(2) and severe PPM as AVAi 3D-TEE and 2D-TTE respectively p value = n.s) and severe PPM occurred in 10 % of the patients who underwent 3D-TEE and in 20 % in those with 2D-TTE (p value = n.s). The echocardiographic evaluation 3 months post-TAVI showed 25 % moderate PPM in the 3D-TEE group compared with 24 % in the 2D-TTE group (p value = n.s) and no cases of severe PPM in the 3DTEE group comparing to 20 % in the 2D-TTE group (p = 0.032). Our results indicate a higher incidence of severe PPM in patients who performed 2DTTE compared to those performing 3DTEE prior TAVI. This suggests that the 3D technique should replace the 2DTTE analysis when investigating the aortic annulus diameter in patients undergoing TAVI.

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

Science.gov (United States)

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 valve effective orifice area (from 1.0±0.4 to 1.8±0.6 cm 2 , P 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.

Door valve for fuel handling path

International Nuclear Information System (INIS)

Makishima, Katsuhiko.

1969-01-01

A door valve is provided which seals cover gas from a liquid metal cooled reactor without leakage therefrom. A threaded shaft is screwed into a heavy box press which is packed with lead. The shaft is adapted to be rotated by an electric motor or a manually operated wheel which is disposed outside of the door valve. A valve plate is suspended from the box press by four guide wheels mounted thereon. The guide wheels are fitted into inclined guide grooves formed at the valve plate and into grooved formed in the inner wall of a valve casing. A locking ball is provided at each side of the valve plate. In operation the shaft rotates and travels to permit the box press and the valve plate to move into the door valve casing, thus releasing the locking balls. The valve plate does not contact the bottom of the casing. When the box press reaches the home position, the valve plate is carried on the valve opening, and the box press presses the valve plate to increase the tightness. The valve plate does not suffer wear as it does not slide over other parts. (Yamaguchi, T.)

Recurrent pannus formation causing prosthetic aortic valve dysfunction: Is excision without valve re-replacement applicable?

OpenAIRE

Darwazah Ahmad K

2012-01-01

Abstract Prosthetic valve dysfunction at aortic position is commonly caused by pannus formation. The exact etiology is not known. It arises from ventricular aspect of the prosthesis encroaching its leaflets causing stenosis or it may remain localized causing left ventricular outflow tract obstruction without affecting valve function. The difference in location entails different approaches in management. Such a pathology requires surgical excision of the pannus with or without valve re-replace...

Severe wear behaviour of alumina balls sliding against diamond ...

Indian Academy of Sciences (India)

study, alumina ball was chosen as the counter body material to show better performance of the ... Tribology is a relatively new science that considers ... The science is applied in ... for example, in hip prosthesis, instead of existing alumina.

Rigorous patient-prosthesis matching of Perimount Magna aortic bioprosthesis.

Science.gov (United States)

Nakamura, Hiromasa; Yamaguchi, Hiroki; Takagaki, Masami; Kadowaki, Tasuku; Nakao, Tatsuya; Amano, Atsushi

2015-03-01

Severe patient-prosthesis mismatch, defined as effective orifice area index ≤0.65 cm(2) m(-2), has demonstrated poor long-term survival after aortic valve replacement. Reported rates of severe mismatch involving the Perimount Magna aortic bioprosthesis range from 4% to 20% in patients with a small annulus. Between June 2008 and August 2011, 251 patients (mean age 70.5 ± 10.2 years; mean body surface area 1.55 ± 0.19 m(2)) underwent aortic valve replacement with a Perimount Magna bioprosthesis, with or without concomitant procedures. We performed our procedure with rigorous patient-prosthesis matching to implant a valve appropriately sized to each patient, and carried out annular enlargement when a 19-mm valve did not fit. The bioprosthetic performance was evaluated by transthoracic echocardiography predischarge and at 1 and 2 years after surgery. Overall hospital mortality was 1.6%. Only 5 (2.0%) patients required annular enlargement. The mean follow-up period was 19.1 ± 10.7 months with a 98.4% completion rate. Predischarge data showed a mean effective orifice area index of 1.21 ± 0.20 cm(2) m(-2). Moderate mismatch, defined as effective orifice area index ≤0.85 cm(2) m(-2), developed in 4 (1.6%) patients. None developed severe mismatch. Data at 1 and 2 years showed only two cases of moderate mismatch; neither was severe. Rigorous patient-prosthesis matching maximized the performance of the Perimount Magna, and no severe mismatch resulted in this Japanese population of aortic valve replacement patients. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Maximizing prosthetic valve size with the Top Hat supra-annular aortic valve

DEFF Research Database (Denmark)

Aagaard, Jan; Geha, Alexander S.

2007-01-01

BACKGROUND AND AIM OF THE STUDY: The CarboMedics Top Hat supra-annular aortic valve allows a one-size (and often two-size) increase over the standard intra-annular valve. This advantage should minimize the risk of patient-prosthesis mismatch, where the effective prosthetic valve orifice area....... This study evaluates the authors' clinical experience with Top Hat supra-annular aortic valve size selection, and the technical aspects of implantation. METHODS: Between January 1999 and October 2005, a total of 251 consecutive patients underwent 252 aortic valve replacements with Top Hat supra...... required unplanned coronary bypass, and 30-day mortality was 2.0% (5/251), indicating a good safety profile for the valves implanted in this series. CONCLUSION: The general distribution of implant sizes in the US indicates that cardiac surgeons may be under-sizing the Top Hat supra-annular aortic valve...

Comparison of magnetic resonance imaging and Laser Doppler Anemometry velocity measurements downstream of replacement heart valves: implications for in vivo assessment of prosthetic valve function.

Science.gov (United States)

Fontaine, A A; Heinrich, R S; Walker, P G; Pedersen, E M; Scheidegger, M B; Boesiger, P; Walton, S P; Yoganathan, A P

1996-01-01

The non-invasive, in-vivo assessment of prosthetic valve function is compromised by the lack of accurate measurements of the transvalvular flow fields or hemodynamics by current techniques. Short echo time magnetic resonance imaging (MRI) may provide a method for the non-invasive, in vivo assessment of prosthetic valve function by accurately measuring changes in the transvalvular flow fields associated with normal and dysfunctional prosthetic valves. The objectives of these in vitro experiments were to investigate the potential for using MRI as a tool to measure the complex flow fields distal to replacement heart valves, and to assess the accuracy of MRI velocity measurements by comparison with Laser Doppler Anemometry (LDA), a gold standard. The velocity fields downstream of tilting disc, bileaflet, ball and cage, and pericardial tissue valves were measured using both three-component LDA and MRI phase velocity encoding under a steady flow rate of 22.8 l/min, simulating peak systolic flow. The valves were tested under normal and stenotic conditions to assess the MRI capabilities under a wide range of local flow conditions, velocities and turbulence levels. A new short echo time MRI technique (FAcE), which allowed velocity measurements in stenotic jets with high turbulence, was tested. Good overall agreement was obtained between the MRI velocity measurements and the LDA data. The MRI velocity measurements adequately reproduced the spatial structure of the flow fields. In most cases peak velocities were accurately measured to within 15%. The results indicate that the FAcE MRI method has the potential to be used as a diagnostic tool to assess prosthetic valve function.

Transcatheter aortic valve prosthesis surgically replaced 4 months after implantation

DEFF Research Database (Denmark)

Thyregod, Hans Gustav; Lund, Jens Teglgaard; Engstrøm, Thomas

2010-01-01

Transcatheter aortic valve implantation is a new and rapidly evolving treatment option for high-risk surgical patients with degenerative aortic valve stenosis. Long-term results with these new valve prostheses are lacking, and potential valve dysfunction and failure would require valve replacemen...

Impact of prosthesis-patient mismatch on the regression of secondary mitral regurgitation after isolated aortic valve replacement with a bioprosthetic valve in patients with severe aortic stenosis.

Science.gov (United States)

Angeloni, Emiliano; Melina, Giovanni; Pibarot, Philippe; Benedetto, Umberto; Refice, Simone; Ciavarella, Giuseppino M; Roscitano, Antonino; Sinatra, Riccardo; Pepper, John R

2012-01-01

Secondary mitral regurgitation (SMR) is generally reduced after isolated aortic valve replacement (AVR), but there is important interindividual variability in the magnitude of this reduction. Prosthesis-patient mismatch (PPM) may hinder normalization of left ventricular geometry and pressure overload following AVR, therefore we aimed to investigate the relationship between PPM and regression of SMR following AVR for aortic valve stenosis. A total of 419 patients with AS who underwent isolated AVR at 2 institutions and presenting moderate SMR (mitral regurgitant volume 30 to 45 mL/beat) not considered for surgical correction were included in this study. Clinical and echocardiographic follow-up were completed at a median follow-up time of 37 months. PPM was defined as an indexed effective orifice area ≤0.85 cm(2)/m(2) and was found in 170/419 patients (40.6%). There were no significant differences in baseline and operative characteristics between patients with or without PPM. Patients with PPM had less regression of SMR following AVR compared with those with no PPM (change in mitral regurgitant volume: -11±4 versus -17±5 mL, respectively; Pregression model, which showed indexed effective orifice area (Pregression of SMR following AVR. This unfavorable effect was associated with worse functional capacity. These findings emphasize the importance of operative strategies aiming to prevent PPM in patients with aortic valve stenosis and concomitant SMR.

Pannus-related prosthetic valve dysfunction. Case report.

Science.gov (United States)

Moldovan, Maria-Sînziana; Bedeleanu, Daniela; Kovacs, Emese; Ciumărnean, Lorena; Molnar, Adrian

2016-01-01

Pannus-related prosthetic valve dysfunction, a complication of mechanical prosthetic valve replacement, is rare, with a slowly progressive evolution, but it can be acute, severe, requiring surgical reintervention. We present the case of a patient with a mechanical single disc aortic prosthesis, with moderate prosthesis-patient mismatch, minor pannus found on previous ultrasound examinations, who presented to our service with angina pain with a duration of 1 hour, subsequently interpreted as non-ST segment elevation myocardial infarction (NSTEMI) syndrome. Coronarography showed normal epicardial coronary arteries, an ample movement of the prosthetic disc, without evidence of coronary thromboembolism, and Gated Single-Photon Emission Computerized Tomography (SPECT) with Technetium (Tc)-99m detected no perfusion defects. Transthoracic echocardiography (TTE) evidenced a dysfunctional prosthesis due to a subvalvular mass; transesophageal echocardiography (TOE) showed the interference of this mass, with a pannus appearance, with the closure of the prosthetic disc. Under conditions of repeated angina episodes, under anticoagulant treatment, surgery was performed, with the intraoperative confirmation of pannus and its removal. Postoperative evolution was favorable. This case reflects the diagnostic and therapeutic management problems of pannus-related prosthetic valve dysfunction.

Replica sizing strategy for aortic valve replacement improves haemodynamic outcome of the epic supra valve.

Science.gov (United States)

Gonzalez-Lopez, David; Faerber, Gloria; Diab, Mahmoud; Amorim, Paulo; Zeynalov, Natig; Doenst, Torsten

2017-10-01

Current sizing strategies suggest valve selection based on annulus diameter despite supra-annular placement of biological prostheses potentially allowing placement of a larger size. We assessed the frequency of selecting a larger prosthesis if prosthesis size was selected using a replica (upsizing) and evaluated its impact on haemodynamics. We analysed all discharge echocardiograms between June 2012 and June 2014, where a replica sizer was used for isolated aortic valve replacement (Epic Supra: 266 patients, Trifecta: 49 patients). Upsizing was possible in 71% of the Epic Supra valves (by 1 size: 168, by 2 sizes: 20) and in 59% of the Trifectas (by 1 size: 26, by 2 sizes: 3). Patients for whom upsizing was possible had the lowest pressure gradients within their annulus size groups. The difference was significant in annulus diameters of 21-22 or 25-26 mm (Epic Supra) and 23-24 mm (Trifecta). Trifecta gradients were the lowest. However, the ability to upsize the Epic Supra by 2 sizes eliminated the differences between Epic Supra and Trifecta. Upsizing did not cause intraoperative complications. Using replica sizers for aortic prosthesis size selection allows the implantation of bigger prostheses than recommended in most cases and reduces postoperative gradients, specifically for Epic Supra. © The Author 2017. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

Biological aortic valve replacement: advantages and optimal indications of stentless compared to stented valve substitutes. A review.

Science.gov (United States)

Tavakoli, Reza; Danial, Pichoy; Oudjana, Ahmed Hamid; Jamshidi, Peiman; Gassmann, Max; Leprince, Pascal; Lebreton, Guillaume

2018-05-01

Controversy still surrounds the optimal biological valve substitute for aortic valve replacement. In light of the current literature, we review advantages and optimal indications of stentless compared to stented aortic bio-prostheses. Recent meta-analyses, prospective randomized controlled trials and retrospective studies comparing the most frequently used stentless and stented aortic bio-prostheses were analyzed. In the present review, the types and implantation techniques of the bio-prosthesis that are seldom taken into account by most studies and reviews were integrated in the interpretation of the relevant reports. For stentless aortic root bio-prostheses, full-root vs. sub-coronary implantation offered better early transvalvular gradients, effective orifice area and left ventricular mass regression as well as late freedom from structural valve deterioration in retrospective studies. Early mortality and morbidity did not differ between the stentless and stented aortic bio-prostheses. Early transvalvular gradients, effective orifice area and regression of left ventricular hypertrophy were significantly better for stentless, especially as full-root, compared to stented bio-prostheses. The long-term valve-related survival for stentless aortic root and Toronto SPV bio-prosthesis was as good as that for stented pericardial aortic bio-prostheses. For full-root configuration this survival advantage was statistically significant. There seems to be not one but different ideal biological valve substitutes for different subgroups of patients. In patients with small aortic root or exposed to prosthesis-patient mismatch full-root implantation of stentless bio-prostheses may better meet functional needs of individual patients. Longer follow-ups on newer generation of stented bio-prostheses are needed for comparison of their hemodynamic performance with stentless counterparts especially in full-root configuration.

Aortic Annular Enlargement during Aortic Valve Replacement

Directory of Open Access Journals (Sweden)

Selman Dumani

2016-09-01

Full Text Available In the surgery of aortic valve replacement is always attempted, as much as possible, to implant the larger prosthesis with the mains goals to enhance the potential benefits, to minimise transvalvular gradient, decrease left ventricular size and avoid the phenomenon of patient-prosthesis mismatch. Implantation of an ideal prosthesis often it is not possible, due to a small aortic annulus. A variety of aortic annulus enlargement techniques is reported to avoid patient-prosthesis mismatch. We present the case that has submitted four three times open heart surgery. We used Manouguian technique to enlarge aortic anulus with excellent results during the fourth time of surgery.

Laser Doppler anemometry measurements of steady flow through two bi-leaflet prosthetic heart valves

Directory of Open Access Journals (Sweden)

Ovandir Bazan

2013-12-01

Full Text Available INTRODUCTION: In vitro hydrodynamic characterization of prosthetic heart valves provides important information regarding their operation, especially if performed by noninvasive techniques of anemometry. Once velocity profiles for each valve are provided, it is possible to compare them in terms of hydrodynamic performance. In this first experimental study using laser doppler anemometry with mechanical valves, the simulations were performed at a steady flow workbench. OBJECTIVE: To compare unidimensional velocity profiles at the central plane of two bi-leaflet aortic prosthesis from St. Jude (AGN 21 - 751 and 21 AJ - 501 models exposed to a steady flow regime, on four distinct sections, three downstream and one upstream. METHODS: To provide similar conditions for the flow through each prosthesis by a steady flow workbench (water, flow rate of 17L/min. and, for the same sections and sweeps, to obtain the velocity profiles of each heart valve by unidimensional measurements. RESULTS: It was found that higher velocities correspond to the prosthesis with smaller inner diameter and instabilities of flow are larger as the section of interest is closer to the valve. Regions of recirculation, stagnation of flow, low pressure, and flow peak velocities were also found. CONCLUSIONS: Considering the hydrodynamic aspect and for every section measured, it could be concluded that the prosthesis model AGN 21 - 751 (RegentTM is superior to the 21 AJ - 501 model (Master Series. Based on the results, future studies can choose to focus on specific regions of the these valves.

Transapical aortic valve implantation in Rouen: four years' experience with the Edwards transcatheter prosthesis.

Science.gov (United States)

Litzler, Pierre-Yves; Borz, Bogdan; Smail, Hassiba; Baste, Jean-Marc; Nafeh-Bizet, Catherine; Gay, Arnaud; Tron, Christophe; Godin, Matthieu; Caudron, Jerome; Hauville, Camille; Dacher, Jean-Nicolas; Cribier, Alain; Eltchaninoff, Hélène; Bessou, Jean-Paul

2012-03-01

The first French transapical transcatheter aortic valve implantation (TAVI) was performed in July 2007 in our department. To report 4-year outcomes of transapical implantation with the Edwards transcatheter bioprosthesis. We prospectively evaluated consecutive patients who underwent transapical implantation with an Edwards transcatheter bioprosthesis between July 2007 and October 2011. Patients were not suitable for conventional surgery (due to severe comorbidities) or transfemoral implantation (due to poor femoral access). Among 61 patients (59.0% men), mean logistic EuroSCORE was 27.5 ± 14.9% and mean age was 81.0 ± 6.8 years. Successful valve implantation was achieved in 59/61 patients (96.7%) of patients. The other two patients required conversion to conventional surgery due to prosthesis embolization and died. Six additional patients died in the postoperative period. Causes of perioperative death were two septic shocks (one of peritonitis), two multi-organ failure, one ventricular fibrillation and one respiratory insufficiency. Intraprocedural stroke was not observed in any patient. The actuarial survival rates at 1, 2 and 4 years were 73.8%, 67.2% and 41.0%. During this 4-year period, four patients died of cardiovascular events, but no impairment of transprosthesis gradient was observed. Our series of 61 patients who underwent transapical implantation of the Edwards transcatheter bioprosthesis shows satisfactory results, similar to other reports, considering the high level of severity of patients referred for this method. Transapical access is a reliable alternative method for patients that cannot benefit from a transfemoral approach. Copyright © 2012. Published by Elsevier Masson SAS.

An Underreported Consequence of Obesity in Pregnancy: Patient-Prosthesis Mismatch

OpenAIRE

Hartman, William R.; Arendt, Katherine W.; Rehfeldt, Kent H.

2012-01-01

As the rate of obesity increases in childbearing-aged women, so too will the complications of obesity in pregnancy. An uncommon and likely underreported complication occurs in obese women who have received prepregnancy cardiac valve replacement with a prosthesis that is inadequately sized for body habitus, a condition referred to as patient-prosthesis mismatch (PPM). The physiologic changes of pregnancy as well as the increased weight gain combine to exacerbate PPM. We report a case of PPM th...

Transcatheter aortic-valve replacement with a self-expanding prosthesis.

Science.gov (United States)

Adams, David H; Popma, Jeffrey J; Reardon, Michael J; Yakubov, Steven J; Coselli, Joseph S; Deeb, G Michael; Gleason, Thomas G; Buchbinder, Maurice; Hermiller, James; Kleiman, Neal S; Chetcuti, Stan; Heiser, John; Merhi, William; Zorn, George; Tadros, Peter; Robinson, Newell; Petrossian, George; Hughes, G Chad; Harrison, J Kevin; Conte, John; Maini, Brijeshwar; Mumtaz, Mubashir; Chenoweth, Sharla; Oh, Jae K

2014-05-08

We compared transcatheter aortic-valve replacement (TAVR), using a self-expanding transcatheter aortic-valve bioprosthesis, with surgical aortic-valve replacement in patients with severe aortic stenosis and an increased risk of death during surgery. We recruited patients with severe aortic stenosis who were at increased surgical risk as determined by the heart team at each study center. Risk assessment included the Society of Thoracic Surgeons Predictor Risk of Mortality estimate and consideration of other key risk factors. Eligible patients were randomly assigned in a 1:1 ratio to TAVR with the self-expanding transcatheter valve (TAVR group) or to surgical aortic-valve replacement (surgical group). The primary end point was the rate of death from any cause at 1 year, evaluated with the use of both noninferiority and superiority testing. A total of 795 patients underwent randomization at 45 centers in the United States. In the as-treated analysis, the rate of death from any cause at 1 year was significantly lower in the TAVR group than in the surgical group (14.2% vs. 19.1%), with an absolute reduction in risk of 4.9 percentage points (upper boundary of the 95% confidence interval, -0.4; P<0.001 for noninferiority; P = 0.04 for superiority). The results were similar in the intention-to-treat analysis. In a hierarchical testing procedure, TAVR was noninferior with respect to echocardiographic indexes of valve stenosis, functional status, and quality of life. Exploratory analyses suggested a reduction in the rate of major adverse cardiovascular and cerebrovascular events and no increase in the risk of stroke. In patients with severe aortic stenosis who are at increased surgical risk, TAVR with a self-expanding transcatheter aortic-valve bioprosthesis was associated with a significantly higher rate of survival at 1 year than surgical aortic-valve replacement. (Funded by Medtronic; U.S. CoreValve High Risk Study ClinicalTrials.gov number, NCT01240902.).

A 29-year-old Harken disk mitral valve: long-term follow-up by echocardiographic and cineradiographic imaging.

Science.gov (United States)

Hsi, David H; Ryan, Gerald F; Taft, Janice; Arnone, Thomas J

2003-01-01

An 81-year-old woman was evaluated for prosthetic mitral valve function. She had received a Harken disk mitral valve 29 years earlier due to severe mitral valve disease. This particular valve prosthesis is known for premature disk edge wear and erosion. The patients 2-dimensional Doppler echocardiogram showed the distinctive appearance of a disk mitral valve prosthesis. Color Doppler in diastole showed a unique crown appearance, with initial flow acceleration around the disk followed by convergence to laminar flow in the left ventricle. Cineradiographic imaging revealed normal valve function and minimal disk erosion. We believe this to be the longest reported follow-up of a surviving patient with a rare Harken disk valve. We present images with unique echocardiographic and cineangiographic features.

Intermittent acute aortic valve regurgitation: A case report of a prosthetic valve dysfunction

NARCIS (Netherlands)

S.E. Karagiannis (Stefanos); G. Karatasakis (George); K. Spargias (Konstantinos); L. Louka; D. Poldermans (Don); D.V. Cokkinos (Dennis)

2008-01-01

textabstractComplications of any mechanical prosthesis include thrombus or pannus formation. In our case report we demonstrate that prosthetic aortic valve regurgitation due to pannus formation may be intermittent and non-cyclic in pattern and therefore not obvious at the time of original clinical

Bar versus ball attachments for implant-supported overdentures in complete edentulism: A systematic review.

Science.gov (United States)

Anas El-Wegoud, Marwah; Fayyad, Ahmed; Kaddah, Amal; Nabhan, Ashraf

2018-04-01

Implant-supported overdenture is one of the most predictable treatment options used in complete edentulism. However, differences have been reported between bar and ball attachments used to retain overdentures in terms of patient satisfaction and prosthesis retention. The purpose of this study is to compare the effectiveness of bar and ball attachments for conventionally loaded implant-supported overdentures in completely edentulous patients to improve patient satisfaction and prosthesis retention. We conducted the review according to the Cochrane methods and following MECIR standards. We searched Cochrane Oral Health Group Trial register, Cochrane Central Register of Controlled Trials, MEDLINE, and the WHO ICTRP (March 31, 2017). Two review authors assessed trials for inclusion and risk of bias, extracted data, and checked for accuracy. We have expressed results as risk ratio or mean differences, together with their 95% confidence intervals. We included 10 trials (465 participants). After 5 y, one trial reported higher patient satisfaction when bar attachment was used (MD 1.30, 95% CI 0.20-2.40), and reported no difference between both systems in prosthesis retention (MD -0.90, 95% CI -1.90 to 0.10). Two trials reported no implant failures after 1 and 5 y in both attachments. Downgrading of evidence was based on the unclear risk of bias of included studies and the wide CI crossing the line of no effect. There is insufficient evidence to support bar or ball attachment to be used with implant-supported overdentures in completely edentulous patients to improve patient satisfaction and prosthesis retention (PROSPERO 2014:CRD42014014594). © 2017 Wiley Periodicals, Inc.

Impact of patient-prosthesis mismatch following aortic valve replacement on short-term survival: a retrospective single center analysis of 632 consecutive patients with isolated stented biological aortic valve replacement.

Science.gov (United States)

Hoffmann, Grischa; Ogbamicael, Selam Abraham; Jochens, Arne; Frank, Derk; Lutter, Georg; Cremer, Jochen; Petzina, Rainer

2014-09-01

The impact of patient-prosthesis mismatch (PPM) after aortic valve replacement (AVR) on short-term and long-term mortality remains controversial. The objective of this study was to evaluate the incidence and severity of PPM and its impact on short-term survival in a large cohort of patients treated with isolated stented biological AVR in a single institution. We analyzed retrospectively data of 632 consecutive patients with aortic stenosis undergoing isolated stented biological AVR between January 2007 and February 2012 at our institution. PPM was defined as an indexed effective orifice area ≤ 0.85 cm(2)/m(2). Statistical analyses were performed to identify influencing variables on valve size implanted. Of the 632 patients investigated, 46% were females and mean age was 71.9 ± 10.4 years. PPM was observed in 93.8% (593 of 632 patients). In 71% of the patients, moderate (0.65-0.85 cm(2)/m(2)) PPM was present and in 22.8% severe (body mass index, and body surface area as simultaneous predictors of the valve size implanted (R(2)= 0.39). PPM had no discernable impact on short-term survival, although it was present in 93.8% of our patients following isolated stented biological AVR. Georg Thieme Verlag KG Stuttgart · New York.

Developments in mechanical heart valve prosthesis

Indian Academy of Sciences (India)

M. Senthilkumar (Newgen Imaging) 1461 1996 Oct 15 13:05:22

BHUVANESHWAR. Biomedical Technology Wing, Sree Chitra Tirunal Institute for Medical Sciences. & Technology ... affect the performance of mechanical heart valves. The clinical performance of ... those who cannot be put under anticoagulant therapy, like women who may still wish to bear children, or hemolytic patients.

Prosthesis-patient mismatch in bovine pericardial aortic valves: evaluation using 3 different modalities and associated medium-term outcomes.

Science.gov (United States)

Chacko, Satish Jacob; Ansari, Asimul H; McCarthy, Patrick M; Malaisrie, S Chris; Andrei, Adin-Cristian; Li, Zhi; Lee, Richard; McGee, Edwin; Bonow, Robert O; Puthumana, Jyothy J

2013-09-01

The prevalence of prosthesis-patient mismatch (PPM) and its impact on survival after aortic valve replacement have not been clearly defined. Historically, the presence of PPM was identified from postoperative echocardiograms or preoperative manufacturer-provided charts, resulting in wide discrepancies. The 2009 American Society of Echocardiography (ASE) guidelines proposed an algorithmic approach to calculate PPM. This study compared PPM prevalence and its impact on survival using 3 modalities: (1) the ASE guidelines-suggested algorithm (ASE PPM); (2) the manufacturer-provided charts (M PPM); and (3) the echocardiographically measured, body surface area-indexed, effective orifice area (EOAi PPM) measurement. A total of 614 patients underwent aortic valve replacement with bovine pericardial valves from 2004 to 2009 and had normal preoperative systolic function. EOAi PPM was severe if EOAi was ≤ 0.60 cm(2)/m(2), moderate if EOAi was 0.60 to 0.85 cm(2)/m(2), and absent (none) if EOAi was ≥ 0.85 cm(2)/m(2). ASE PPM was severe in 22 (3.6%), moderate in 6 (1%), and absent (none) in 586 (95.4%). ASE PPM was similar to manufacturer-provided PPM (P=1.00). ASE PPM differed significantly from EOAi PPM (P<0.001), which identified severe mismatch in 170 (29.7%), moderate in 191 (33.4%), and absent (none) in 211 patients (36.9%). Irrespective of the PPM classification method, PPM did not adversely affect midterm survival (average follow-up, 4.1 ± 1.8 years; median, 3.9 years; range, 0.01-8 years). There were no reoperations for PPM. In patients with normal systolic function undergoing bovine pericardial aortic valve replacement, the prevalence of PPM using the algorithmic-ASE approach was low and correlated well with manufacturer-provided PPM. Independent of the method of PPM assessment, PPM was not associated with medium-term mortality.

[Minor strut fracture of the Björk-Shiley mitral valve].

Science.gov (United States)

Sugita, T; Yasuda, R; Watarida, S; Onoe, M; Tabata, R; Mori, A

1990-06-01

In May, 1982, a 49-year-old man underwent mitral valve replacement (MVR) in our hospital with a 31 mm Björk-Shiley prosthesis for mitral regurgitation. He had been doing well until his episode of palpitation and dyspnea of sudden onset, and was transferred to our ICU with severe cardiogenic shock in Aug, 1986. Chest X-ray film revealed pulmonary edema and breakage of the valve with migration of the disc and the minor strut of the prosthesis. He was operated upon 5 hours after the onset of his complaints. The minor strut was removed from the left upper pulmonary vein and mitral valve re-replacement was done with a 29 mm Björk-Shiley Monostrut valve. The disc which had dislocated into the abdominal aorta was also recovered on the twenty-third post operative day. His postoperative course was uneventful. Immediate diagnosis and subsequent re-operation is absolute indication for rescue from acute cardiac failure due to mechanical failure of any prosthetic valve.

Radial Force: An Underestimated Parameter in Oversizing Transcatheter Aortic Valve Replacement Prostheses: In Vitro Analysis with Five Commercialized Valves.

Science.gov (United States)

Egron, Sandrine; Fujita, Buntaro; Gullón, Lucía; Désirée, Pott; Schmitz-Rode, Thomas; Ensminger, Stephan; Steinseifer, Ulrich

2017-09-05

The goal is to inform in depth on transcatheter aortic valve replacement (TAVR) prosthesis mechanical behavior, depending on frame type, design, and size, and how it crucially impacts the oversizing issue in clinical use, and ultimately the procedure outcome. Transcatheter aortic valve replacement is an established therapy for high-risk patients suffering from aortic stenosis, and the indication for TAVR is progressively expanding to intermediate-risk patients. Choosing the optimal oversizing degree is crucial to safely anchor the TAVR valve-which involves limiting the risks for embolism, aortic regurgitation, conductance disturbance, or annulus rupture-and to increase the valve prosthesis performance. The radial force (RF) profiles of five TAVR prostheses were measured in vitro: the CoreValve 23 and 26 (Medtronic, MN), the Acurate neo S (Symetis, Switzerland), and the SAPIEN XT 23 and 26 (Edwards Lifesciences, CA). Measurements were run with the RX Machine equipment (Machine Solutions Inc., AZ), which is used in ISO standard tests for intravascular stents. Test protocols were adapted for TAVR prostheses. With the prostheses RF profiles' results, mechanical behavior differences could be described and discussed in terms of oversizing strategy and clinical impact for all five valves. Besides, crossing the prostheses' RF profiles with their recommended size windows made the assessment of borderline size cases possible and helped analyze the risks when accurate measurement of patient aortic annulus proves difficult. The prostheses' RF profiles bring new support in clinical decision-making for valve type and size in patients.

Recurrent pannus formation causing prosthetic aortic valve dysfunction: is excision without valve re-replacement applicable?

Science.gov (United States)

Darwazah, Ahmad K

2012-06-29

Prosthetic valve dysfunction at aortic position is commonly caused by pannus formation. The exact etiology is not known. It arises from ventricular aspect of the prosthesis encroaching its leaflets causing stenosis or it may remain localized causing left ventricular outflow tract obstruction without affecting valve function.The difference in location entails different approaches in management. Such a pathology requires surgical excision of the pannus with or without valve re-replacement.A recurrent pannus was observed in a female patient who needed repeated surgical intervention to excise a localized pannus without re-replacement of a well functioning prosthetic valve.Management of our case presents several questions, whether recurrence of pannus is caused by sparing the prosthetic valve, is it simply an exaggeration of an inflammatory healing process in certain individuals or is it ideal to re-replace the valve despite a well preserved function.

Failure and life cycle evaluation of watering valves.

Science.gov (United States)

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.

Early postoperative dislocation of the anterior Maverick lumbar disc prosthesis: report of 2 cases.

Science.gov (United States)

Gragnaniello, Cristian; Seex, Kevin A; Eisermann, Lukas G; Claydon, Matthew H; Malham, Gregory M

2013-08-01

The authors report on 2 cases of anterior dislocation of the Maverick lumbar disc prosthesis, both occurring in the early postoperative period. These cases developed after experience with more than 50 uneventful cases and were therefore thought to be unrelated to the surgeon's learning curve. No similar complications have been previously reported. The anterior Maverick device has a ball-and-socket design made of cobalt-chromium-molybdenum metal plates covered with hydroxyapatite. The superior and inferior endplates have keels to resist translation forces. The patient in Case 1 was a 52-year-old man with severe L4-5 discogenic pain; and in Case 2, a 42-year-old woman with disabling L4-5 and L5-S1 discogenic back pain. Both patients were without medical comorbidities and were nonsmokers with no risk factors for osteoporosis. Both had undergone uneventful retroperitoneal approaches performed by a vascular access surgeon. Computed tomography studies on postoperative Day 2 confirmed excellent prosthesis placement. Initial recoveries were uneventful. Two weeks postoperatively, after stretching (extension or hyperextension) in bed at home, each patient suffered the sudden onset of severe abdominal pain with anterior dislocation of the Maverick prosthesis. The patients were returned to the operating room and underwent surgery performed by the same spinal and vascular surgeons. Removal of the Maverick prosthesis and anterior interbody fusion with a separate cage and plate were performed. Both patients had recovered well with good clinical and radiological recovery at the 6- and 12-month follow-ups. Possible causes of the anterior dislocation of the Maverick prosthesis include the following: 1) surgeon error: In both cases the keel cuts were neat, and early postoperative CT confirmed good placement of the prosthesis; 2) equipment problem: The keel cuts may have been too large because the cutters were worn, which led to an inadequate press fit of the implants; 3) prosthesis

Worchester Solenoid Actuated Gas Operated MCO Isolation Valves

International Nuclear Information System (INIS)

VAN KATWIJK, C.

2000-01-01

These valves are 1 inch gas-operated full-port ball valves incorporating a solenoid and limit switches as integral parts of the actuator that are used in process streams within the CVDF hood. The valves fail closed (on loss of pressure or electrical) to prevent MCO vent drain to either reduce air in-leakage or loss of He. The valves have couplings for transverse actuator mounting

Worcester Solenoid-Actuated Gas Operated MCO Isolation Valves

International Nuclear Information System (INIS)

VAN KATWIJK, C.

2000-01-01

These valves are 1 inch gas-operated full-port ball valves incorporating a solenoid and limit switches as Integral parts of the actuator that are used in different process streams within the CVDF hood. The valves fail closed (on loss of pressure or electrical) for MCO isolation to either reduce air in leakage or loss of He. All valves have coupling for transverse actuator mounting

Research on vibration properties of auxiliary bearing cage used in HTR-10 GT project

International Nuclear Information System (INIS)

Qin Qingquan; Yang Guojun; Shi Zhengang; Yu Suyuan

2009-01-01

Auxiliary Bearings (ABs) is one of the most important parts in Active Magnetic Bearing (AMB) system, which was used in HTR-10 GT project. This paper uses finite element method to analyze the centrifugal stress and free vibration properties of the cage according to its work condition. And different geometric parameters of the cage that has effects on its vibration performance are discussed. The results show that the highest centrifugal stress is in the middle of the cage side sill. The low odder vibration modes of the cage can be induced when the auxiliary bearings are working. Proper geometric parameters and ball pocket number can enhance the performance of the cage. (authors)

Failure analysis of the ball bearings of dental air turbine handpieces.

Science.gov (United States)

Wei, M; Dyson, J E; Darvell, B W

2013-12-01

The aim of this study was to identify the nature and causes of deterioration and failure in dental handpiece ball bearings and thus provide guidance for clinical handling for service longevity. The bearings of 36 turbine assemblies were dismantled for visual inspection, documented using a digital camera, and examined using scanning electron microscopy, as appropriate. For the metal parts of the ball bearing assembly, defects observed were mainly wear arising from the running load and corrosion. This was in the form of scratches and discoloured circumferential bands on the balls, and dull or worn surfaces extending around the circumference of the raceways. Cage damage including cracking, fracture, surface rubbing and distortion occurred, in varying degrees, in every failed turbine. Dental ball bearing failure modes have been identified. Cumulative effects of damage from corrosion and mechanical factors lead to handpiece deterioration. The cage was found to be very vulnerable to damage, and this may be the key limitation on bearing lifetime. Autoclaving may contribute to that, as it does to corrosion in the absence of adequate lubrication, but this seems to be minor in comparison to the effects of abuse. There is no justification for failing to observe usage and sterilization instructions. © 2013 Australian Dental Association.

Recurrent pannus formation causing prosthetic aortic valve dysfunction: Is excision without valve re-replacement applicable?

Directory of Open Access Journals (Sweden)

Darwazah Ahmad K

2012-06-01

Full Text Available Abstract Prosthetic valve dysfunction at aortic position is commonly caused by pannus formation. The exact etiology is not known. It arises from ventricular aspect of the prosthesis encroaching its leaflets causing stenosis or it may remain localized causing left ventricular outflow tract obstruction without affecting valve function. The difference in location entails different approaches in management. Such a pathology requires surgical excision of the pannus with or without valve re-replacement. A recurrent pannus was observed in a female patient who needed repeated surgical intervention to excise a localized pannus without re-replacement of a well functioning prosthetic valve. Management of our case presents several questions, whether recurrence of pannus is caused by sparing the prosthetic valve, is it simply an exaggeration of an inflammatory healing process in certain individuals or is it ideal to re-replace the valve despite a well preserved function.

The radiology of prosthetic heart valves

International Nuclear Information System (INIS)

Steiner, R.M.; Flicker, S.

1985-01-01

The development of prosthetic heart valves in the late 1950s ushered in a new era in the treatment of heart disease. The radiologist has an important role to play preoperatively in the diagnosis of valvular heart disease. Radiology is valuable in identification of the implanted prosthetic valve and recognition of complications associated with valve implantation. Radiologists must be familiar with the imaging techniques best suited to evaluate the function of the valve prosthesis in question. In this chapter the authors discuss the radiographic approach to the evaluation of the status of patients for valve replacement and the imaging problems peculiar to the types of valves in current use. The relative value of plain-film radiography, fluoroscopy, videorecording and cinerecording, and aortography is addressed, as well as the potential value of magnetic resonance imaging and subsecond dynamic computed tomography

Regression in left ventricular mass after aortic valve replacement for chronic aortic regurgitation is unrelated to prosthetic valve size.

Science.gov (United States)

Brown, Morgan L; Schaff, Hartzell V; Suri, Rakesh M; Li, Zhuo; Sundt, Thoralf M; Dearani, Joseph A; Enriquez-Sarano, Maurice

2011-08-01

We examined the role of prosthesis-patient mismatch on left ventricular mass regression after aortic valve replacement for chronic aortic valve regurgitation. We selected patients who had complete preoperative and follow-up echocardiograms with measurement of left ventricular mass. Patients were excluded who had moderate or greater aortic valve stenosis, concomitant coronary artery bypass grafting, or mitral valve procedures. Patients' mean age was 55 ± 17 years; 21% were female. The mean preoperative indexed left ventricular mass was 150 ± 45 g/m(2). Patients with mildly (n = 44; mean indexed mass, 126 ± 15 g/m(2)), moderately (n = 31; mean indexed mass, 168 ± 11 g/m(2)), or severely (n = 15; mean indexed mass, 241 ± 34 g/m(2)) increased preoperative indexed left ventricular mass, were similar, except for lower ejection fractions, larger end-diastolic dimensions, and larger ventricular wall thicknesses in the severely enlarged group (P regression was unrelated to labeled valve size, prosthesis-patient mismatch, or measured indexed effective aortic valve area. A greater preoperative indexed left ventricular mass (P regression. Despite having greater left ventricular mass regression, patients with severe preoperative indexed left ventricular mass did not return to normal values (mean, 142 ± 25 g/m(2)). Left ventricular mass regression after aortic valve replacement for chronic aortic regurgitation is unrelated to indexed prosthetic valve area. Although incomplete, regression is greatest in patients with the largest preoperative indexed left ventricular mass. Copyright © 2011 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

Aorta-atria-septum combined incision for aortic valve re-replacement

Science.gov (United States)

Xu, Yiwei; Ye, Xiaofeng; Li, Zhaolong

2018-01-01

This case report illustrates a patient who underwent supra-annular mechanical aortic valve replacement then suffered from prosthesis dysfunction, increasing pressure gradient with aortic valve. She was successfully underwent aortic valve re-replacement, sub-annular pannus removing and aortic annulus enlargement procedures through combined cardiac incision passing through aortic root, right atrium (RA), and upper atrial septum. This incision provides optimal visual operative field and simplifies dissection. PMID:29850170

[Pannus Formation Six-years after Aortic and Mitral Valve Replacement with Tissue Valves;Report of a Case].

Science.gov (United States)

Nakamura, Makoto; Muraoka, Arata; Aizawa, Kei; Akutsu, Hirohiko; Kurumisawa, Soki; Misawa, Yoshio

2015-07-01

A 77-year-old man presented with exertional dyspnea. He had undergone aortic and mitral valve replacement with tissue valves 6-years earlier. The patient's hemoglobin level was 9.8 g/dl and serum aspartate aminotransferase (70 mU/ml) and lactate dehydrogenase (1,112 mU/ml) were elevated. Echocardiography revealed stenosis of the prosthetic valve in the aortic position with peak flow velocity of 3.8 m/second and massive mitral regurgitation. The patient underwent repeat valve replacement. Pannus formation around both implanted valves was observed. The aortic valve orifice was narrowed by the pannus, and one cusp of the prosthesis in the mitral position was fixed and caused the regurgitation, but they were free from cusp laceration or calcification. The patient's postoperative course was uneventful, and he continues to do well 14 months after surgery.

Leaflet escape in a new bileaflet mechanical valve: TRI technologies.

Science.gov (United States)

Bottio, Tomaso; Casarotto, Dino; Thiene, Gaetano; Caprili, Luca; Angelini, Annalisa; Gerosa, Gino

2003-05-13

Leaflet escape is a mode of structural valve failure for mechanical prostheses. This complication previously has been reported for both monoleaflet and bileaflet valve models. We report 2 leaflet escape occurrences observed in 2 patients who underwent valve replacement with a TRI Technologies valve prosthesis. At the University of Padua, between November 2000 and February 2002, 36 TRI Technologies valve prostheses (26 aortic and 10 mitral) were implanted in 34 patients (12 women and 22 men) with a mean age of 59.9+/-10.3 years (range, 30 to 75 years). There were 5 deaths: 3 in hospital, 1 early after discharge, and 1 late. Two patients experienced a catastrophic prosthetic leaflet escape; the first patient was a 52-year-old man who died 10 days after aortic valve and ascending aorta replacement, and the second was a 58-year-old man who underwent a successful emergency reoperation 20 months after mitral valve replacement. Examination of the explanted prostheses showed in both cases a leaflet escape caused by a leaflet's pivoting system fracture. Prophylactic replacement was then successfully accomplished so far in 12 patients, without evidence of structural valve failure in any of them. Among other significant postoperative complications, we observed 3 major thromboembolisms, 1 hemorrhage, and 1 paravalvular leak. These catastrophes prompted us to interrupt the implantation program, and they cast a shadow on the durability of the TRI Technologies valve prosthesis because of its high risk of structural failure.

Vertical pump with free floating check valve

International Nuclear Information System (INIS)

Lindsay, M.

1980-01-01

A vertical pump is described which has a bottom discharge with a free floating check valve disposed in the outlet plenum thereof. The free floating check valve comprises a spherical member with a hemispherical cage-like member attached thereto which is capable of allowing forward or reverse flow under appropriate conditions while preventing reverse flow under inappropriate conditions

Implante valve-in-valve transcateter em posição aórtica: uma mudança de seleção? Transcatheter aortic valve-in-valve implantation: a selection change?

Directory of Open Access Journals (Sweden)

Diego Felipe Gaia

2012-09-01

. Minimally invasive transcatheter aortic "valve-in-valve" implant appears to be an alternative, reducing morbidity and mortality. The objective is to evaluate aortic valve-in-valve procedure using Braile Inovare prosthesis. METHODS: The Braile Inovare prosthesis, transcatheter, expandable balloon, was used in 14 cases. Average EuroSCORE was 42.9%. All patients had double aortic bioprosthesis dysfunction. Procedures were performed in a surgical hybrid environment under echocardiographic and fluoroscopic guidance. Using left minithoracotomy prostheses were implanted through the ventricular apex under high-frequency ventricular pacing. Serial clinical and echocardiographic controls were performed. Follow-up ranged 1-30 months. RESULTS: Correct prosthetic deployment was obtained in all cases. There was no conversion. There was no operative mortality. The 30-day mortality was 14.3% (two cases. Ejection fraction increased significantly after the 7th postoperative day. Aortic gradient significantly reduced. The residual aortic regurgitation was not present. There were no vascular complications or complete atrioventricular block. CONCLUSION: The transcatheter "valve-in-valve" procedure for bioprosthesis dysfunction is safe with low morbidity. This possibility may change prosthesis choice during the first aortic valve replacement, favoring bioprostheses.

A novel polymeric prosthetic heart valve: design, manufacture, and testing

OpenAIRE

Brubert, Jacob

2016-01-01

In this thesis a flexible leaflet polymeric prosthetic aortic heart valve was designed, manufactured, and tested. The prosthesis was designed with the aim of overcoming the need for anticoagulant therapy, which is required for current mechanical prostheses; while also having lifelong durability, which current bioprosthetic heart valves are not able to achieve. Inspired by the anisotropic architecture of collagen in the natural valve, a shortlist of polystyrene based block copolymers (BCPs), w...

Towards real-time cardiovascular magnetic resonance-guided transarterial aortic valve implantation: In vitro evaluation and modification of existing devices

Directory of Open Access Journals (Sweden)

Ladd Mark E

2010-10-01

Full Text Available Abstract Background Cardiovascular magnetic resonance (CMR is considered an attractive alternative for guiding transarterial aortic valve implantation (TAVI featuring unlimited scan plane orientation and unsurpassed soft-tissue contrast with simultaneous device visualization. We sought to evaluate the CMR characteristics of both currently commercially available transcatheter heart valves (Edwards SAPIEN™, Medtronic CoreValve® including their dedicated delivery devices and of a custom-built, CMR-compatible delivery device for the Medtronic CoreValve® prosthesis as an initial step towards real-time CMR-guided TAVI. Methods The devices were systematically examined in phantom models on a 1.5-Tesla scanner using high-resolution T1-weighted 3D FLASH, real-time TrueFISP and flow-sensitive phase-contrast sequences. Images were analyzed for device visualization quality, device-related susceptibility artifacts, and radiofrequency signal shielding. Results CMR revealed major susceptibility artifacts for the two commercial delivery devices caused by considerable metal braiding and precluding in vivo application. The stainless steel-based Edwards SAPIEN™ prosthesis was also regarded not suitable for CMR-guided TAVI due to susceptibility artifacts exceeding the valve's dimensions and hindering an exact placement. In contrast, the nitinol-based Medtronic CoreValve® prosthesis was excellently visualized with delineation even of small details and, thus, regarded suitable for CMR-guided TAVI, particularly since reengineering of its delivery device toward CMR-compatibility resulted in artifact elimination and excellent visualization during catheter movement and valve deployment on real-time TrueFISP imaging. Reliable flow measurements could be performed for both stent-valves after deployment using phase-contrast sequences. Conclusions The present study shows that the Medtronic CoreValve® prosthesis is potentially suited for real-time CMR-guided placement

Fiber heart valve prosthesis: influence of the fabric construction parameters on the valve fatigue performances.

Science.gov (United States)

Vaesken, Antoine; Heim, Frederic; Chakfe, Nabil

2014-12-01

Transcatheter aortic valve replacement (TAVR) has become today a largely considered alternative technique to surgical valve replacement in patients who are not operable or patients with high risk for open chest surgery. However, the biological valve tissue used in the devices implanted clinically appears to be fragile material when folded for low diameter catheter insertion purpose and released in calcified environment with irregular geometry. Textile polyester material is characterized by outstanding folding and strength properties combined with proven biocompatibility. It could thereof be considered to replace biological valve leaflets in the TAVR procedure. The textile construction parameters must however be tuned to obtain a material compatible with the valve requested durability. In that context, one issue to be addressed is the friction effect that occurs between filaments and between yarns within a fabric under flexure loading. This phenomenon could be critical for the resistance of the material on the long term. The purpose of the present work is to assess the fatigue performances of textile valve prototypes made from different fabric constructions (monofilament, multifilament, calendered mutifilament) under accelerated cyclic loading. The goal is to identify, which construction is the best suited to long term fatigue stress. Results show that calendered multifilament and monofilament fabric constructions undergo strong ruptures already from 40 Mio cycles, while non calendered multifilament appears more durable. The rupture patterns observed point out that durability is directly related to the flexure stiffness level of the fibrous elements in the construction. Copyright © 2014 Elsevier Ltd. All rights reserved.

Evaluation Of Factors Influencing On Causes Of Prosthetic Valve Re-operation And Early Postoperative Survival Tehran Emam hospital (1991-2001

Directory of Open Access Journals (Sweden)

Rahmani Reaza

2003-06-01

Full Text Available Prosthetic valve re-operation has greater mortality and morbidity than primary valve replacement. By recognition of factors influencing on causes of redo operation and preoperative survival, one can select appropriate prosthesis at primary valve replacement and when operation performed at appropriate time, surgical risk can be reduced."nMethods and Materials: Two hundred patients that underwent prosthetic valve re-operation from October 1991 through November 2001 were included in this study. There were 68 men and 132 women with the mean age of 42:tl 1.8 years. Structural failure was the commonest cause of bio-prosthesis replacement (93%. Valve thrombosis was the common cause of mechanical valve replacement (32%. Age younger Than 50 (P= 0.01 and interval after the first implantation more than 10 years (P= 0.01 affected bio-prosthesis degeneration."nResults: Atrial fibrillation (P<0.01, Older age especially more than 40 (P<0.05 and mitral position (P<0.01 affected mechanical valve thrombosis. Cross clamp time (P= 0.005, Tricuspid insufficiency (P = 0.001, NYHA IV (P = 0.005 and emergent operation (P= 0.001 were independent determinants of hospital mortality."nConclusion: In conclusion, in patients with more than 10-years life expectancy and age younger than 50, mechanical valve can be selected for primary valve replacement. If operation performed before patients reach deteriorated condition, preoperative survival would be excellent.

Patient-prosthesis mismatch in patients treated with transcatheter aortic valve implantation – predictors, incidence and impact on clinical efficacy. A preliminary study

Directory of Open Access Journals (Sweden)

Karol Zbroński

2017-11-01

Full Text Available Introduction : Patient-prosthesis mismatch (PPM is relatively frequent after surgical aortic valve replacement (SAVR and negatively impacts prognosis. Aim : We sought to determine the frequency and clinical effects of PPM after transcatheter aortic valve implantation (TAVI. Material and methods : Overall, 238 patients who underwent TAVI were screened. Moderate PPM was defined as indexed effective orifice area (EOAi between 0.65 and 0.85 cm2/m2, and severe PPM as < 0.65 cm2/m2. All-cause mortality and the Valve Academic Research Consortium 2 (VARC-2 defined composite of clinical efficacy at 1 year were the primary endpoints. Results : Finally, 201 patients were included (mean age: 79.6 ±7.4 years, 52% females. The femoral artery served as the delivery route in 79% and most of the prostheses were self-expanding (68%. Any PPM was present in 48 (24% subjects, and only 7 (3.5% had severe PPM. Body surface area (BSA independently predicted any PPM (OR = 16.9, p 20 mm Hg. Conclusions : Severe PPM after TAVI is rare, can be predicted by larger BSA and does not seem to affect mid-term mortality or composite clinical outcome. Larger studies are needed to find different independent predictors of PPM and elucidate its impact in terms of device durability and long-term clinical efficacy.

Echocardiographic evaluation of heart valve prosthetic dysfunction

Directory of Open Access Journals (Sweden)

Yuriy Ivaniv

2018-02-01

Full Text Available Patients with replaced heart valve submitted to echocardiographic examination may have symptoms related either to valvular malfunction or ventricular dysfunction from different causes. Clinical examination is not reliable in a prosthetic valve evaluation and the main information regarding its function could be obtained using different cardiac ultrasound modalities. This review provides a description of echocardiographic and Doppler techniques useful in evaluation of prosthetic heart valves. For the interpretation of echocardiography there is a need in special knowledge of prosthesis types and possible reasons of prosthetic function deterioration. Echocardiography allows to reveal valve thrombosis, pannus formation, vegetation and such complications of infective endocarditis as valve ring abscess or dehiscence. Transthoracic echocardiography requires different section plane angles and unconventional views. Transesophageal echocardiography is more often used than in native valve examination due to better visualization of prosthetic valve structure and function. Three-dimensional echocardiography could provide more detailed visual information especially in the assessment of paravalvular regurgitation or valve obstruction.

Wear-resistant ball bearings for space applications

Science.gov (United States)

Boving, H.; Hintermann, H. E.; Hanni, W.; Bondivenne, E.; Boeto, M.; Conde, E.

1977-01-01

Ball bearings consisting of steel parts of which the rings are coated with hard, wear resistant, chemical vapor deposited TiC are described. Experiments conducted in ultrahigh vacuum, using cages of various materials with self-lubricating properties, show that such bearings are suitable for space applications. The results of laboratory tests on the ESA Meteosat Radiometer Focalizing mechanism, which contains six coated bearings, are summarized.

Transcatheter mitral valve implantation via transapical approach

DEFF Research Database (Denmark)

Sondergaard, Lars; Brooks, Matthew; Ihlemann, Nikolaj

2015-01-01

bypass surgery (n = 2), severe pulmonary hypertension (n = 1) and moderate to severe chronic renal failure (n = 3). A CardiAQ mitral valve was implanted using fluoroscopy and transoesophageal (TEE) guidance via a standard transapical approach. RESULTS: Accurate prosthesis positioning and deployment...

Challenges in developing a reseeded, tissue-engineered aortic valve prosthesis.

Science.gov (United States)

Hof, Alexander; Raschke, Silja; Baier, Karina; Nehrenheim, Laura; Selig, Jessica Isabel; Schomaker, Markus; Lichtenberg, Artur; Meyer, Heiko; Akhyari, Payam

2016-09-01

Biological heart valve prostheses are characterized by a limited durability due to the degenerative processes after implantation. Tissue engineering may provide new approaches in the development of optimized valvular grafts. While re-endothelialization of decellularized heart valves has already been successfully implemented, interstitial repopulation still remains an unaccomplished objective although it is essential for valvular functionality and regeneration potential. The aim of this study was to compare different concepts for an improved in vitro interstitial repopulation of decellularized heart valves. A novel 3D heart valve model has been developed to investigate the cell behaviour of valvular interstitial cells (VIC) in their physiological environment and to evaluate the potential of in vitro repopulation of acellular heart valves. Ovine aortic heart valves were decellularized by detergent solutions and additionally treated with trypsin or laser perforation. Subsequently, the decellularized extracellular matrices (dECM) were reseeded with ovine VIC using reseeding devices to provide a repopulation of the matrix on a defined area under controlled conditions. After an initial attachment of the VIC, reseeded dECM were transferred into a transwell system to improve the nutrient supply inside the valvular matrix. Cell migration and expression of cell markers were analysed histologically. The results were compared with VIC cultivation in a biological scaffold. VIC did not migrate into the matrix of untreated dECM and reseeding in laser perforated dECM showed inconsistent results. However, trypsinization increased the susceptibility of the valvular cusps to VIC penetration and repopulation of superficial areas. Additionally, the cultivation of reseeded dECM in a transwell system significantly increased the total number of cells repopulating the valvular matrix and their mean migration distance, representing the best repopulation results. Immunohistological analysis

Identification of critical zones in the flow through prosthetic heart valves

Science.gov (United States)

Lopez, A.; Ledesma, R.; Zenit, R.; Pulos, G.

2008-11-01

The hemodynamic properties of prosthetic heart valves can cause blood damage and platelet activation due to the non- physiological flow patterns. Blood recirculation and elevated shear stresses are believed to be responsible for these complications. The objective of this study is to identify and quantify the conditions for which recirculation and high stress zones appear. We have performed a comparative study between a mechanical monoleaflet and biological valve. In order to generate the flow conditions to test the prosthesis, we have built a hydraulic circuit which reproduces the human systemic circulation, on the basis of the Windkessel model. This model is based on an electrical analogy which consists of an arterial resistance and compliance. Using PIV 3D- Stereo measurements, taken downstream from the prosthetic heart valves, we have reconstructed the full phase-averaged tridimensional velocity field. Preliminary results show that critical zones are more prominent in mechanical prosthesis, indicating that valves made with bio-materials are less likely to produce blood trauma. This is in accordance with what is generally found in the literature.

Conduction Abnormalities and Pacemaker Implantations After SAPIEN 3 Vs SAPIEN XT Prosthesis Aortic Valve Implantation.

Science.gov (United States)

Husser, Oliver; Kessler, Thorsten; Burgdorf, Christof; Templin, Christian; Pellegrini, Costanza; Schneider, Simon; Kasel, Albert Markus; Kastrati, Adnan; Schunkert, Heribert; Hengstenberg, Christian

2016-02-01

Transcatheter aortic valve implantation is increasingly used in patients with aortic stenosis. Post-procedural intraventricular conduction abnormalities and permanent pacemaker implantations remain a serious concern. Recently, the Edwards SAPIEN 3 prosthesis has replaced the SAPIEN XT. We sought to determine the incidences of new-onset intraventricular conduction abnormalities and permanent pacemaker implantations by comparing the 2 devices. We analyzed the last consecutive 103 patients undergoing transcatheter aortic valve implantation with SAPIEN XT before SAPIEN 3 was used in the next 105 patients. To analyze permanent pacemaker implantations and new-onset intraventricular conduction abnormalities, patients with these conditions at baseline were excluded. Electrocardiograms were recorded at baseline, after the procedure, and before discharge. SAPIEN 3 was associated with higher device success (100% vs 92%; P=.005) and less paravalvular leakage (0% vs 7%; Ppacemaker implantations was 12.6% (23 of 183) with no difference between the 2 groups (SAPIEN 3: 12.5% [12 of 96] vs SAPIEN XT: 12.6% [11 of 87]; P=.99). SAPIEN 3 was associated with a higher rate of new-onset intraventricular conduction abnormalities (49% vs 27%; P=.007) due to a higher rate of fascicular blocks (17% vs 5%; P=.021). There was no statistically significant difference in transient (29% [20 of 69] vs persistent 19% [12 of 64]; P=.168) left bundle branch blocks (28% [19 of 69] vs 17% [11 of 64]; P=.154) when SAPIEN 3 was compared with SAPIEN XT. We found a trend toward a higher rate of new-onset intraventricular conduction abnormalities with SAPIEN 3 compared with SAPIEN XT, although this did not result in a higher permanent pacemaker implantation rate. Copyright © 2015 Sociedad Española de Cardiología. Published by Elsevier España, S.L.U. All rights reserved.

A systematic study of ball passing frequencies based on dynamic modeling of rolling ball bearings with localized surface defects

Science.gov (United States)

Niu, Linkai; Cao, Hongrui; He, Zhengjia; Li, Yamin

2015-11-01

Ball passing frequencies (BPFs) are very important features for condition monitoring and fault diagnosis of rolling ball bearings. The ball passing frequency on outer raceway (BPFO) and the ball passing frequency on inner raceway (BPFI) are usually calculated by two well-known kinematics equations. In this paper, a systematic study of BPFs of rolling ball bearings is carried out. A novel method for accurately calculating BPFs based on a complete dynamic model of rolling ball bearings with localized surface defects is proposed. In the used dynamic model, three-dimensional motions, relative slippage, cage effects and localized surface defects are all considered. Moreover, localized surface defects are modeled accurately with consideration of the finite size of the ball, the additional clearance due to material absence, and changes of contact force directions. The reasonability of the proposed method for the prediction of dynamic behaviors of actual ball bearings with localized surface defects and for the calculation of BPFs is discussed by investigating the motion characteristics of a ball when it rolls through a defect. Parametric investigation shows that the shaft speed, external loads, the friction coefficient, raceway groove curvature factors, the initial contact angle, and defect sizes have great effects on BPFs. For a loaded ball bearing, the combination of rolling and sliding in contact region occurs, and the BPFs calculated by simple kinematical relationships are inaccurate, especially for high speed, low external load, and large initial contact angle conditions where severe skidding occurs. The hypothesis that the percentage variation of the spacing between impulses in a defective ball bearing was about 1-2% reported in previous investigations can be satisfied only for the conditions where the skidding effect in a bearing is slight. Finally, the proposed method is verified with two experiments.

Successful Management of Prosthetic Valve Brucella Endocarditis with Antibiotherapy Alone

Directory of Open Access Journals (Sweden)

José Pedro Fonseca

2018-01-01

Full Text Available Objectives: To report a case of mechanical aortic prosthesis Brucella endocarditis successfully treated with antibiotics alone. Materials and methods: We describe a clinical case and present a review of the literature. Results: A 60-year-old female farmer with a mechanical aortic prosthetic valve presented with low back pain and fever. She was diagnosed with prosthetic valve Brucella mellitensis endocarditis and was cured with antibiotic therapy alone. Few cases of successfully treated prosthetic valve Brucella endocarditis without surgery have been reported. Conclusion: Prosthetic valve Brucella endocarditis usually requires surgical valve replacement. However, selected patients may be successfully treated with antibiotic therapy alone.

Nonlinear dynamic model for skidding behavior of angular contact ball bearings

Science.gov (United States)

Han, Qinkai; Chu, Fulei

2015-10-01

A three-dimensional nonlinear dynamic model is proposed to predict the skidding behavior of angular contact ball bearings under combined load condition. The centrifugal and gyroscopic effects induced by ball rotation and revolution, Hertz contact between the ball and inner/outer races, discontinuous contact between the ball and cage and elastohydrodynamic lubrication are considered in the model. Through comparisons with the tested results of the reference, the dynamic model is verified. Based upon these, variations of ball slipping speed with time and space are discussed for the bearing under combined load condition. It is shown that radial load leads to the fluctuations in the slipping velocity of the ball contacting with inner/outer races, especially for the ball in load-decreasing regions. Adding the radial load would significantly increase the amplitude and range of slipping velocity, indicating that the skidding becomes more serious. As the ball still withstands contact load in the load-decreasing region, large slipping velocity would increase the temperature of both bearing and lubricant oil, intensify the wear and then might shorten the bearing service life. Therefore, the radial load should be considered carefully in the design and monitoring of rotating machinery.

Echocardiographic Assessment of Heart Valve Prostheses

Science.gov (United States)

Sordelli, Chiara; Severino, Sergio; Ascione, Luigi; Coppolino, Pasquale; Caso, Pio

2014-01-01

Patients submitted to valve replacement with mechanical or biological prosthesis, may present symptoms related either to valvular malfunction or ventricular dysfunction from other causes. Because a clinical examination is not sufficient to evaluate a prosthetic valve, several diagnostic methods have been proposed to assess the functional status of a prosthetic valve. This review provides an overview of echocardiographic and Doppler techniques useful in evaluation of prosthetic heart valves. Compared to native valves, echocardiographic evaluation of prosthetic valves is certainly more complex, both for the examination and the interpretation. Echocardiography also allows discriminating between intra- and/or peri-prosthetic regurgitation, present in the majority of mechanical valves. Transthoracic echocardiography (TTE) requires different angles of the probe with unconventional views. Transesophageal echocardiography (TEE) is the method of choice in presence of technical difficulties. Three-dimensional (3D)-TEE seems to be superior to 2D-TEE, especially in the assessment of paravalvular leak regurgitation (PVL) that it provides improved localization and analysis of the PVL size and shape. PMID:28465917

Clinical and ultrasound results after aortic valve replacement: intermediate-term follow-up with the St. Jude Medical prosthesis.

Science.gov (United States)

Montalescot, G; Thomas, D; Drobinski, G; Evans, J I; Vicaut, E; Chatellier, G; Whyte, R I; Busquet, P; Bejean-Lebuisson, A; Grosgogeat, Y

1989-07-01

Mortality, morbidity, quality of life, and left ventricular (LV) function were evaluated in 49 patients after aortic valve replacement with the St. Jude prosthesis. Total follow-up was 2577 patient-months; survivors were followed-up for 4 to 7 years by clinical examination and echocardiography. The actuarial survival rate at 6 years was 79.6%, and there were no valve-related deaths. The linearized rates for thromboembolism and hemorrhage were 0.93% and 3.26% per patient-year, respectively. In 34% of the survivors the quality of life was poor. In the first three postoperative months, patients with aortic stenosis (n = 12) had a significant decrease in the muscle cross-sectional area (p less than 0.01) and patients with aortic regurgitation (n = 11) had decreases in both LV end-diastolic diameter (p less than 0.05) and cross-sectional area (p less than 0.001). All of these results were maintained at 5 years without modification of LV systolic function. Despite the good overall results, six patients deteriorated and had major LV dilatation. Multivariate logistic regression analysis identified two independent preoperative variables associated with a poor outcome defined as death of LV dysfunction (p less than 0.05): age and end-diastolic diameter. Thus meticulous follow-up showed a high incidence of hemorrhage and a poor quality of life in many of the survivors. It was concluded that in high-risk patients (age and end-diastolic diameter) surgery should probably be considered earlier.

Space Shuttle OMS engine valve technology. [Orbital Maneuvering System

Science.gov (United States)

Wichmann, H.

1974-01-01

Valve technology program to determine shutoff valve concepts suitable for the Orbital Maneuvering System (OMS) engine of the Space Shuttle. The tradeoff studies selected the electric torque motor operated dual poppet and ball valves as the most desirable valve concepts for the OMS Engine Shutoff Valve. A prototype of one of these concepts was built and subjected to a design verification program. A number of unique features were designed to include the required contamination insensitivity, operating fluid compatibility, decontamination capability, minimum maintenance requirement and long service life capability.

Artificial aortic valve dysfunction due to pannus and thrombus - different methods of cardiac surgical management.

Science.gov (United States)

Ostrowski, Stanisław; Marcinkiewicz, Anna; Kośmider, Anna; Walczak, Andrzej; Zwoliński, Radosław; Jaszewski, Ryszard

2015-09-01

Approximately 60 000 prosthetic valves are implanted annually in the USA. The risk of prosthesis dysfunction ranges from 0.1% to 4% per year. Prosthesis valve dysfunction is usually caused by a thrombus obstructing the prosthetic discs. However, 10% of prosthetic valves are dysfunctional due to pannus formation, and 12% of prostheses are damaged by both fibrinous and thrombotic components. The authors present two patients with dysfunctional aortic prostheses who were referred for cardiac surgery. Different surgical solutions were used in the treatment of each case. The first patient was a 71-year-old woman whose medical history included arterial hypertension, stable coronary artery disease, diabetes mellitus, chronic obstructive pulmonary disease (COPD), and hypercholesterolemia; she had previously undergone left-sided mastectomy and radiotherapy. The patient was admitted to the Cardiac Surgery Department due to aortic prosthesis dysfunction. Transthoracic echocardiography revealed complete obstruction of one disc and a severe reduction in the mobility of the second. The mean transvalvular gradient was very high. During the operation, pannus covering the discs' surface was found. A biological aortic prosthesis was reimplanted without complications. The second patient was an 87-year-old woman with arterial hypertension, persistent atrial fibrillation, and COPD, whose past medical history included gastric ulcer disease and ischemic stroke. As in the case of the first patient, she was admitted due to valvular prosthesis dysfunction. Preoperative transthoracic echocardiography revealed an obstruction of the posterior prosthetic disc and significant aortic regurgitation. Transesophageal echocardiography and fluoroscopy confirmed the prosthetic dysfunction. During the operation, a thrombus growing around a minor pannus was found. The thrombus and pannus were removed, and normal functionality of the prosthetic valve was restored. Precise and modern diagnostic methods

System for remotely servicing a top loading captive ball valve

International Nuclear Information System (INIS)

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

1996-01-01

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 se 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

Association of aortic valve calcification severity with the degree of aortic regurgitation after transcatheter aortic valve implantation.

Science.gov (United States)

Koos, Ralf; Mahnken, Andreas Horst; Dohmen, Guido; Brehmer, Kathrin; Günther, Rolf W; Autschbach, Rüdiger; Marx, Nikolaus; Hoffmann, Rainer

2011-07-15

This study sought to examine a possible relationship between the severity of aortic valve calcification (AVC), the distribution of AVC and the degree of aortic valve regurgitation (AR) after transcatheter aortic valve implantation (TAVI) for severe aortic stenosis (AS). 57 patients (22 men, 81 ± 5 years) with symptomatic AS and with a logistic EuroSCORE of 24 ± 12 were included. 38 patients (67%) received a third (18F)-generation CoreValve® aortic valve prosthesis, in 19 patients (33%) an Edwards SAPIEN™ prosthesis was implanted. Prior to TAVI dual-source computed tomography for assessment of AVC was performed. To determine the distribution of AVC the percentage of the calcium load of the most severely calcified cusp was calculated. After TAVI the degree of AR was determined by angiography and echocardiography. The severity of AR after TAVI was related to the severity and distribution of AVC. There was no association between the distribution of AVC and the degree of paravalvular AR after TAVI as assessed by angiography (r = -0.02, p = 0.88). Agatston AVC scores were significantly higher in patients with AR grade ≥ 3 (5055 ± 1753, n = 3) than in patients with AR grade AVC scores > 3000 were associated with a relevant paravalvular AR and showed a trend for increased need for second manoeuvres. There was a significant correlation between the severity of AVC and the degree of AR after AVR (r = 0.50, p AVC have an increased risk for a relevant AR after TAVI as well as a trend for increased need for additional procedures. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

Optimal results of aortic valve replacement with small mechanical valves (< 19 mm).

Science.gov (United States)

Kato, Yasuyuki; Hattori, Koji; Motoki, Manabu; Takahashi, Yosuke; Kotani, Shinsuke; Nishimura, Shinsuke; Shibata, Toshihiko

2013-07-01

Controversy exists regarding the optimal operative method or type of prosthesis for patients with a small aortic root. The aim of this retrospective study was to investigate the early and mid-term outcomes of standard aortic valve replacement (AVR) using 16 mm or 18 mm ATS Advanced Performance (AP) or 17 mm St. Jude Medical (SJM) Regent valves for a small aortic root. Between April 2003 and August 2009, 78 patients (age range: 50-86 years; 86% aged > or = 65 years) underwent AVR with 16 mm or 18 mm ATS AP valves (16AP group: n = 21, 18AP group: n = 32), or a 17 mm SJM Regent valve (17Regent group: n = 25). Fifty-six patients (72%) had a body surface area (BSA) of regression was similar among the groups (-30%, -25% and -28% in the 16AP, 17Regent and 18AP groups, respectively; p = 0.844). The early and mid-term results of AVR with 16 mm or 18 mm ATS AP valves, or with a 17 mm SJM Regent valve, were satisfactory. Therefore, standard AVR using these small mechanical prostheses, which avoids the need to enlarge the annulus or to conduct stentless bioprosthesis implantation, might represent an acceptable method, especially in elderly patients with a small aortic root.

The diagnosis value of the cinefluoroscopy in the evaluation of the OMNI Science prosthesis

International Nuclear Information System (INIS)

Carvalho, A.C.C.; Cardoso, A.; Martinez Filho, E.E.

1982-01-01

The authors present their experience with cinefluoroscopy, performed with a six inch image intensifier, in 19 patients who had received an Omni Science prosthesis; this valve has a radiopaque disc which is imputed to be easily seen during fluoroscopy. To determine the sensitivity and specificity of the method, 16 asymptomatic patients and three who had clinical suspicion of valve malfunction were analysed. In the asymptomatic patients we were able to clearly visualize the disc, without exception; in the three patients with valvular thrombosis, we were not able to find the disc in two cases and in the third its excursion was evidently impaired. We conclude that fluorescopy is an important nonivasive tool in the third its excursion was evidently impaired. We conclude that fluoroscopy is an important noninnvasive tool in the assessment of this type of prosthesis. (author) [pt

A new self-administered questionnaire to determine patient experience with voice prostheses (Blom-singer valves

Directory of Open Access Journals (Sweden)

Kazi R

2005-01-01

Full Text Available Aim: To obtain information about valved speech and related issues in patients who have undergone total laryngectomy with the help of a new structured questionnaire on voice prosthesis. Settings and Design: A questionnaire-based pilot study set at a tertiary referral head and neck cancer unit. Materials and Methods: Twenty-five patients using voice prostheses, who showed no signs of recurrence after having undergone total laryngectomy were interviewed with the help of a questionnaire that assessed issues such as voice quality, valve maintenance, leakage, quality of life, humidification and hands-free system over the preceding seven days. The data was analyzed using non-parametric tests (Mann-Whitney and Spearman rank. Results: Twenty-five patients (16 males with a median age of 65 years (IQ range: 59-70 years had been using the prosthesis for a median of 6 years (IQ range: 5-10 years. The majority of the patients (n=20 were fully informed about their valve size and diameter and most were able to remove and replace their own prosthesis. Fourteen patients (60% had leakage-related issues. Women were less satisfied with their voice quality as compared to men. Overall, there appeared to be an improvement in quality of life with the use of the voice prosthesis. Conclusions: The subjects were fairly well informed about their valve and experienced a high level of satisfaction with their voice. This questionnaire serves as a valuable tool for monitoring voice rehabilitation in patients who have undergone laryngectomy.

Chemical and structural composition study through transmission and reflection electron microscopy and X-ray microanalysis of damaged duramater cardiac valves

International Nuclear Information System (INIS)

Verginelli, G.; Didio, L.J.A.; Puig, L.B.; Allen, D.J.; Highinson, G.H.; Zerbini, E.J.

1982-01-01

Ten malfunctioning durameter aortic prosthesis, excised surgically after 44 to 54 months of implantation were studied through transmission and reflection electron microscopy and X-ray microanalysis. Duramater extracted at necropsy but not used for valve prosthesis and duramater aortic prosthesis not implanted in patients were used as controls. It was concluded that homologous duramater valves present subcellular changes following implantation, with degenerating and proliferating areas which could correspond either to normal adaptation or consequence of degeneration - rebuilding which begins with implantation; it is also emphazised the need for ultramicroscopic studies in evaluating biological tissues and establishing its applicability in cardiac surgery. (M.A.C.) [pt

Control of dental prosthesis system with microcontroller.

Science.gov (United States)

Kapidere, M; Müldür, S; Güler, I

2000-04-01

In this study, a microcontroller-based electronic circuit was designed and implemented for dental prosthesis curing system. Heater, compressor and valve were controlled by 8-bit PIC16C64 microcontroller which is programmed using MPASM package. The temperature and time were controlled automatically by preset values which were inputted from keyboard while the pressure was kept constant. Calibration was controlled and the working range was tested. The test results showed that the system provided a good performance.

OMS engine shutoff valve and actuation system design and evaluation. [for space shuttles

Science.gov (United States)

Wichmann, H.

1974-01-01

Shutoff valve and actuation system concepts that are most suitable for the Orbital Maneuvering Systems engine application were determined. Emphasis was placed on the ten year and 100 mission life requirement, propellant and propellant residue compatibility and weight. It was found that poppet or ball valves utilizing electric or electropneumatic actuation were most applicable. Preliminary design layouts of a number of valve and actuation concepts were prepared and analyzed to make the optimum concept selection. Pneumatic actuation systems were required to feature their own pneumatic supply so that for the quad redundant valve, it was necessary to include two pneumatic supply systems, one for each of the series legs of the quad redundant package. The requirement for the pneumatic package placed heavy reliability, weight, and maintenance penalties upon electropneumatic actuation systems. The two valve and actuation systems concepts selected featured electric torque motor operation and a poppet as well as a ball valve concept with a retractable seal.

Reimplantation valve-sparing aortic root replacement in Marfan syndrome using the Valsalva conduit: an intercontinental multicenter study.

Science.gov (United States)

Settepani, Fabrizio; Szeto, Wilson Y; Pacini, Davide; De Paulis, Ruggero; Chiariello, Luigi; Di Bartolomeo, Roberto; Gallotti, Roberto; Bavaria, Joseph E

2007-02-01

Introduced by DePaulis in 2000, the Gelweave Valsalva graft (Sulzer Vascutek, Refrewshire, Scotland) is a modified Dacron conduit (DuPont, Wilmington, DE), with prefashioned sinuses of Valsalva. The aim of this study was to evaluate the mid-term results of the reimplantation valve-sparing aortic root replacement using the Gelweave Valsalva prosthesis in Marfan syndrome patients. A retrospective review was performed of 35 patients with Marfan syndrome in four centers who underwent the reimplantation valve-sparing aortic root replacement using the Gelweave Valsalva prosthesis. The patients were predominantly men, with a mean age of 36.5 +/- 12.6 years (range, 14 to 62 years). Two patients presented with acute type A dissections and underwent emergent operations. Elective hemiarch reconstruction using hypothermic circulatory arrest was required in 11 patients. Aortic valve cusp repair was performed in 2 patients. There were no operative or hospital deaths, and no patients died during follow-up. The mean follow-up was 19 months (range, 1 to 60 months). Significant (>2+) aortic insufficiency (AI), requiring aortic valve replacement, developed in 3 patients during follow-up that requiring aortic valve replacement. The 5-year freedom from reoperation owing to structural valve deterioration was 88.9% +/- 8.1%. There were no episodes of clinically significant thromboembolism. Reimplantation valve-sparing aortic root replacement with the Gelweave Valsalva prosthesis in Marfan patients provides satisfactory mid-term results, thus encouraging further use of this type of repair. However, long-term results are needed in order to define the durability of this technique.

A high-precision instrument for analyzing nonlinear dynamic behavior of bearing cage

Energy Technology Data Exchange (ETDEWEB)

Yang, Z., E-mail: zhaohui@nwpu.edu.cn; Yu, T. [School of Aeronautics, Northwestern Polytechnical University, Xi’an 710072 (China); Chen, H. [Xi’an Aerospace Propulsion Institute, Xi’an 710100 (China); Li, B. [State Key Laboratory for Manufacturing and Systems Engineering, Xi’an Jiaotong University, Xi’an 710054 (China)

2016-08-15

The high-precision ball bearing is fundamental to the performance of complex mechanical systems. As the speed increases, the cage behavior becomes a key factor in influencing the bearing performance, especially life and reliability. This paper develops a high-precision instrument for analyzing nonlinear dynamic behavior of the bearing cage. The trajectory of the rotational center and non-repetitive run-out (NRRO) of the cage are used to evaluate the instability of cage motion. This instrument applied an aerostatic spindle to support and spin test the bearing to decrease the influence of system error. Then, a high-speed camera is used to capture images when the bearing works at high speeds. A 3D trajectory tracking software TEMA Motion is used to track the spot which marked the cage surface. Finally, by developing the MATLAB program, a Lissajous’ figure was used to evaluate the nonlinear dynamic behavior of the cage with different speeds. The trajectory of rotational center and NRRO of the cage with various speeds are analyzed. The results can be used to predict the initial failure and optimize cage structural parameters. In addition, the repeatability precision of instrument is also validated. In the future, the motorized spindle will be applied to increase testing speed and image processing algorithms will be developed to analyze the trajectory of the cage.

A high-precision instrument for analyzing nonlinear dynamic behavior of bearing cage

International Nuclear Information System (INIS)

Yang, Z.; Yu, T.; Chen, H.; Li, B.

2016-01-01

The high-precision ball bearing is fundamental to the performance of complex mechanical systems. As the speed increases, the cage behavior becomes a key factor in influencing the bearing performance, especially life and reliability. This paper develops a high-precision instrument for analyzing nonlinear dynamic behavior of the bearing cage. The trajectory of the rotational center and non-repetitive run-out (NRRO) of the cage are used to evaluate the instability of cage motion. This instrument applied an aerostatic spindle to support and spin test the bearing to decrease the influence of system error. Then, a high-speed camera is used to capture images when the bearing works at high speeds. A 3D trajectory tracking software TEMA Motion is used to track the spot which marked the cage surface. Finally, by developing the MATLAB program, a Lissajous’ figure was used to evaluate the nonlinear dynamic behavior of the cage with different speeds. The trajectory of rotational center and NRRO of the cage with various speeds are analyzed. The results can be used to predict the initial failure and optimize cage structural parameters. In addition, the repeatability precision of instrument is also validated. In the future, the motorized spindle will be applied to increase testing speed and image processing algorithms will be developed to analyze the trajectory of the cage.

Textile for heart valve prostheses: fabric long-term durability testing.

Science.gov (United States)

Heim, Frederic; Durand, Bernard; Chakfe, Nabil

2010-01-01

The rapid developments and success in percutaneous vascular surgery over the last two decades with the now common stent grafts implantation, make the noninvasive surgery technique today attractive even for heart valve replacement. Less traumatic for the patient and also less time consuming, percutaneous heart valve replacement is however at its beginning and restricted to end of life patients. The noninvasive procedure expects from the heart valve prosthesis material to be resistant and adapted to folding requirements of the implantation process (catheter). Polyester fabric could be a suited material for heart valve implanted percutaneously. Highly flexible and resistant, polyester fabric proved to be well adapted to the dynamic behavior of a valve and polyester (Dacron) is also widely used for vascular grafts implantation and shows good biocompatibility and durability. However, today there's no data available on long-term durability of fabric used as heart valve material. The purpose of this work is to study the long term behavior of a microdenier polyester fabric construction under combined in vitro flexure and tension fatigue stress. In the novel in vitro testing technique presented, a fabric specimen was subjected to combined flexural and tensile fatigue generated by fluid flow under physiological pressure conditions. The results obtained show how flexural properties change with fatigue time, which reflects directly on the suitability of a fabric in such devices. It was also observed that these fabric structural changes directly influence the in vitro behavior of the textile heart valve prosthesis. (c) 2009 Wiley Periodicals, Inc.

Sickle cell anemia and mitral valve replacement. Case report.

Science.gov (United States)

Bomfim, V; Ribeiro, A; Gouvea, F; Pereira, J; Björk, V

1989-01-01

An 8-year-old black boy with sickle cell disease and severe hemolytic anemia crisis (95% hemoglobin S) also had mitral incompetence due to rheumatic valve disease. A 27 mm monostrut Björk-Shiley valve prosthesis was implanted after partial exchange transfusions had reduced the hemoglobin S to less than 40%. High-flow normothermic perfusion was used during extracorporeal circulation, with care taken to avoid hypoxia and acidosis. Postoperative recovery was uneventful.

Artificial aortic valve dysfunction due to pannus and thrombus – different methods of cardiac surgical management

Science.gov (United States)

Marcinkiewicz, Anna; Kośmider, Anna; Walczak, Andrzej; Zwoliński, Radosław; Jaszewski, Ryszard

2015-01-01

Introduction Approximately 60 000 prosthetic valves are implanted annually in the USA. The risk of prosthesis dysfunction ranges from 0.1% to 4% per year. Prosthesis valve dysfunction is usually caused by a thrombus obstructing the prosthetic discs. However, 10% of prosthetic valves are dysfunctional due to pannus formation, and 12% of prostheses are damaged by both fibrinous and thrombotic components. The authors present two patients with dysfunctional aortic prostheses who were referred for cardiac surgery. Different surgical solutions were used in the treatment of each case. Case study 1 The first patient was a 71-year-old woman whose medical history included arterial hypertension, stable coronary artery disease, diabetes mellitus, chronic obstructive pulmonary disease (COPD), and hypercholesterolemia; she had previously undergone left-sided mastectomy and radiotherapy. The patient was admitted to the Cardiac Surgery Department due to aortic prosthesis dysfunction. Transthoracic echocardiography revealed complete obstruction of one disc and a severe reduction in the mobility of the second. The mean transvalvular gradient was very high. During the operation, pannus covering the discs’ surface was found. A biological aortic prosthesis was reimplanted without complications. Case study 2 The second patient was an 87-year-old woman with arterial hypertension, persistent atrial fibrillation, and COPD, whose past medical history included gastric ulcer disease and ischemic stroke. As in the case of the first patient, she was admitted due to valvular prosthesis dysfunction. Preoperative transthoracic echocardiography revealed an obstruction of the posterior prosthetic disc and significant aortic regurgitation. Transesophageal echocardiography and fluoroscopy confirmed the prosthetic dysfunction. During the operation, a thrombus growing around a minor pannus was found. The thrombus and pannus were removed, and normal functionality of the prosthetic valve was restored

Service life investigations of ball bearings at 1200C in a helium atmosphere

International Nuclear Information System (INIS)

Haas, H.

1984-04-01

The generally known rules for the layout of ball bearings do not yield in the case the bearings run in an helium atmosphere contaminated with impurities in the range of microbars. Therefore the layout of bearings put into action in helium has to be supported by tests carried out in a similar environment and for similar loads. With the aim to support the selection of lubricants and the design of the bearings in regard to the economical point of view, the basic principles of tribology in helium have been compiled and forty ball bearings have been tested at 90 0 C and 120 0 C in helium. The applied loads comply with the usual values in machine construction. The tests show as result that ball bearings suitable for the different fields of applications in helium can be produced by simply exchanging the cages of standardized bearings. Reliable 10 7 revolutions have been obtained for different materials, also for cages made out of soft metals such as lead bronze, suitable in a radiation environment. In addition lubricants have been tested in order to find out the limits of suitability. (orig.) [de

Isolated mitral valve replacement with the Kay-Shiley disc. valve. Acturial analysis of the long term results.

Science.gov (United States)

Wellons, H A; Strauch, R S; Nolan, S P; Muller, W H

1975-11-01

During a five-year period the Kay-Shiley (K and T series) prosthesis was used for 83 isolated mitral valve replacements. There were 14 early deaths, for a 17.28 per cent mortality rate. Survival determined by the actuarial method revealed a 6 year cumulative survival rate of 39.8 per cent. Thromboembolism was a significant problem in this series, with 33 patients experiencing a total of 55 embolic events. This represented a rate of 24.7 emboli per 1,000 patient months at risk. From our experience, it is concluded that the Kay-Shiley prosthesis is associated with a high incidence of thromboembolism and late death.

Design and production of a hermetic bayonet isolation valve

International Nuclear Information System (INIS)

Fuerst, J.

1993-05-01

Fermilab is upgrading the Tevatron for lower temperature/higher beam energy operation. Portions of the satellite refrigeration system will operate below atmospheric pressure after the upgrade is complete. Contamination must be prevented by hermetically sealing the subatmospheric helium to air interfaces. Bayonet connections in the low pressure flow path require a reliable, leak tight isolation valve instead of the standard quarter turn ball valve. Design, development, and production of a new valve are described

Percutaneous transfemoral-transseptal implantation of a second-generation CardiAQ™ mitral valve bioprosthesis

DEFF Research Database (Denmark)

Ussia, Gian Paolo; Quadri, Arshad; Cammalleri, Valeria

2016-01-01

echocardiography and fluoroscopy were utilised for device positioning and deployment. The mitral valve prosthesis was implanted with mild mitral regurgitation. The postoperative course was uneventful and at 30-day follow-up the patient is in NYHA Class I, with good function of the mitral valve bioprosthesis....... CONCLUSIONS: This procedure shows that percutaneous transfemoral transcatheter mitral valve implantation is feasible, safe and successful. Further experience is needed to render this procedure clinically available....

Gamma Ray Sterilization of Starr-Edwards Heart Valve Prostheses

Energy Technology Data Exchange (ETDEWEB)

Gibbons, J. R. P.; Alladine, M. F. [London Chest Hospital, London (United Kingdom)

1967-09-15

Starr-Edwards valves have normally been sterilized by exposure to ethylene oxide or by autoclaving. Patients having a prosthetic valve replacement are known to have a higher incidence of endocarditis in comparison with patients in which no prosthesis has been used. Ethylene oxide will only sterilize the surface of the valve and autoclaving has caused distortion of the polytetrafluorethylene ring. Work has been done on the effect of gamma radiation on the components of these valve prostheses and is given in detail. The bacteriological efficiency, at a total absorbed dose of 2. 5 Mrad, has been established. Thirty valves treated by this method have now been inserted and twelve patients have been examined post-operatively for a period of one to two years. All valves are working normally and there has been no evidence of blood-borne infection or malfunction of the valve. (author)

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

Science.gov (United States)

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.

Pannus-Related Mechanical Valve Dysfunction Leading to Hemodynamic Shock

Directory of Open Access Journals (Sweden)

Manabu Shiraishi

2012-02-01

Full Text Available Mechanical prosthetic valve dysfunction caused by pannus formation is rare. Pannus restricts movement of prosthetic valve leaflets, resulting in severe aortic regurgitation. We describe the case of a 77-year-old woman who presented to the emergency room with increasing dyspnea, ischemia, and shock secondary to mechanical aortic valve dysfunction. Transesophageal echocardiography showed a blockade of the leaflets of the mechanical aortic valve, with severe aortic regurgitation. She underwent emergent cardiac surgery for aortic valve replacement. Pannus formation should be considered as a potential cause of acute severe aortic regurgitation in a patient with a small-sized mechanical aortic prosthesis in the supra-annular position. On a pathological exam, extensive pannus was found on the ventricular side of the prosthetic valve, extending from the ring into the central orifice. [Arch Clin Exp Surg 2012; 1(1.000: 50-53

Should the automatic exposure control system of CT be disabled when scanning patients with endoaortic stents or mechanical heart valves? A phantom study.

Science.gov (United States)

Di Leo, Giovanni; Spadavecchia, Chiara; Zanardo, Moreno; Secchi, Francesco; Veronese, Ivan; Cantone, Marie Claire; Sardanelli, Francesco

2017-07-01

To estimate the impact of endoaortic stents/mechanical heart valves on the output of an automatic exposure control (AEC) system and CT radiation dose. In this phantom study, seven stents and two valves were scanned with varying tube voltage (80/100/120 kVp), AEC activation (enabled/disabled) and prosthesis (present/absent), for a total of 540 scans. For each prosthesis, the dose-length product (DLP) was compared between scans with the AEC enabled and disabled. Percentage confidence levels for differences due to the prosthesis were calculated. Differences between results with the AEC enabled and disabled were not statistically significant (p ≥ 0.059). In the comparison with and without the prosthesis, DLP was unchanged at 80 kVp and 100 kVp, while a slight increase was observed at 120 kVp. The radiation dose varied from 1.8 mGy to 2.4 mGy without the prosthesis and from 1.8 mGy to 2.5 mGy with the prosthesis (confidence level 37-100%). The effect of the prosthesis on the AEC system was negligible and not clinically relevant. Therefore, disabling the AEC system when scanning these patients is not likely to provide a benefit. • CT-AEC system is not impaired in patients with endoaortic prostheses/heart valves. • Negligible differences may be observed only at 120 kVp. • Disabling the AEC system in these patients is not recommended.

Subvalvular pannus and thrombosis in a mitral valve prosthesis.

Science.gov (United States)

Kim, Gun Ha; Yang, Dong Hyun; Kang, Joon-Won; Kim, Dae-Hee; Jung, Sung-Ho; Lim, Tae-Hwan

2016-01-01

A 69-year-old female underwent cardiac CT to evaluate prosthetic valve (PHV) dysfunction detected on echocardiography. A CT coronal and en face views of the mitral annular plane showed a low-density, mass-like lesion on the left atrial side of the PHV and a high-density, plate-like lesion on the left ventricular side of PHV. A repeat of the mitral valve replacement was performed, and preoperative CT findings of both the thrombus on the left atrial side and pannus formation on the LV side were confirmed in the operative findings. Copyright © 2016 Society of Cardiovascular Computed Tomography. Published by Elsevier Inc. All rights reserved.

Left ventricular mass regression is independent of gradient drop and effective orifice area after aortic valve replacement with a porcine bioprosthesis.

Science.gov (United States)

Sádaba, Justo Rafael; Herregods, Marie-Christine; Bogaert, Jan; Harringer, Wolfgang; Gerosa, Gino

2012-11-01

The question of whether left ventricular mass (LVM) regression following aortic valve replacement (AVR) is affected by the prosthesis indexed effective orifice area (IEOA) and transprosthetic gradient has not been fully elucidated. Data from a prospective, core-laboratory-reviewed echocardiography and magnetic resonance imaging (MRI) study was used to determine if the degree of LVM regression following AVR with two types of porcine bioprosthesis in patients suffering from predominant aortic valve stenosis (AS) was related to the prosthesis IEOA and transprosthetic gradient. Over a two-year period, 149 patients enrolled at eight centers received either an Epic or an Epic Supra aortic bioprosthesis (St. Jude Medical, MN, USA). Preoperative valve dysfunction was pure AS in 54 patients (36%) and mixed valve disease (primarily stenosis) in 95 patients (64%). LVM was determined preoperatively and at six months postoperatively, using MRI. The prosthesis IEOA and transprosthetic gradient were calculated at six months by means of echocardiography. Data were available for 111 patients at both enrolment and six months postoperatively. The LVM at enrolment and at follow up was 154.96 +/- 42.50 g and 114.83 +/- 29.20 g, respectively (p regression methods, showed LVM regression to be independent of the mean systolic pressure gradient, peak systolic pressure and prosthesis IEOA at six months (p = 0.53, 0.43, and 0.15, respectively). At six months after AVR with a porcine bioprosthesis to treat AS, there was a significant LVM regression that was independent of the prosthesis IEOA and the mean systolic pressure gradient and peak systolic pressure.

Glovebox pressure relief and check valve

Energy Technology Data Exchange (ETDEWEB)

Blaedel, K.L.

1986-03-17

This device is a combined pressure relief valve and check valve providing overpressure protection and preventing back flow into an inert atmosphere enclosure. The pressure relief is embodied by a submerged vent line in a mercury reservior, the releif pressure being a function of the submerged depth. The pressure relief can be vented into an exhaust system and the relieving pressure is only slightly influenced by the varying pressure in the exhaust system. The check valve is embodied by a ball which floats on the mercury column and contacts a seat whenever vacuum exists within the glovebox enclosure. Alternatively, the check valve is embodied by a vertical column of mercury, the maximum back pressure being a function of the height of the column of mercury.

Glovebox pressure relief and check valve

International Nuclear Information System (INIS)

Blaedel, K.L.

1986-01-01

This device is a combined pressure relief valve and check valve providing overpressure protection and preventing back flow into an inert atmosphere enclosure. The pressure relief is embodied by a submerged vent line in a mercury reservior, the releif pressure being a function of the submerged depth. The pressure relief can be vented into an exhaust system and the relieving pressure is only slightly influenced by the varying pressure in the exhaust system. The check valve is embodied by a ball which floats on the mercury column and contacts a seat whenever vacuum exists within the glovebox enclosure. Alternatively, the check valve is embodied by a vertical column of mercury, the maximum back pressure being a function of the height of the column of mercury

Actuation and system design and evaluation OMS engine shutoff valve, Volume 1. [space shuttles

Science.gov (United States)

Dunn, V. B.

1975-01-01

A technology program was conducted to identify and verify the optimum valve and actuation system concept for the Space Shuttle Orbit Maneuvering System engine. Of major importance to the valve and actuation system selection was the ten-year, 100-mission, 10,000-cycle life requirement, while maintaining high reliability, low leakage, and low weight. Valve and actuation system concepts were comparatively evaluated against past valve failure reports and potential failure modes due to the shuttle mission profile to aid in the selection of the most optimum concept for design, manufacture and verification testing. Two valve concepts were considered during the preliminary design stage; i.e., the moving seat and lifting ball. Two actuation systems were manufactured and tested. Test results demonstrate the viability of a lifting ball concept as well as the applicability of an ac motor actuation system to best meet the requirements of the shuttle mission.

Benefits and medium-term outcome of the Sorin Pericarbon Freedom stentless aortic prosthesis in cases of acute bacterial endocarditis.

Science.gov (United States)

Stefanelli, Guglielmo; Pirro, Fabrizio; Meli, Marco; Trevisan, Davide; Telesca, Mariassunta; Campisano, Barbara; Mussini, Cristina; Barbieri, Andrea

2016-10-01

The aim of this study is to evaluate the ease of use and the advantages of Sorin Pericarbon Freedom (SPF) stentless valve in cases of acute bacterial endocarditis and to check the intermediate-term results after the implant of SPF with respect to resistance to infection, valve deterioration and durability. Between June 2003 and February 2015, 26 patients with active aortic valve bacterial endocarditis underwent aortic valve replacement with SPF pericardial stentless aortic prosthesis. The mean age was 57 ± 18 years; 73% of the patients were in preoperative NYHA class III and VI. Mean Logistic EuroSCORE was 14.2 ± 12.7. Endocarditis occurred in 18 patients with native valves, and in 9 patients with prosthetic valves (4 mechanical aortic valve prostheses; 5 aortic bioprostheses). Aortic root abscesses were observed in 16 cases (61.5%). Surgery was emergent in 3 cases (11.5%). Redo surgery was performed in 9 cases (35%). Cumulative follow-up was 126.8 patient-years (mean 4.9 ± 3.3 years). Operative hospital mortality was 0% for all patients. Residual mean prosthetic gradient at discharge was 9.4 ± 3.6 mmHg. Neither residual aortic incompetence nor residual abscess cavity was observed at discharge. Mean ejection fraction at discharge was 54 ± 8% (Min; Max: 35%; 65%). A total of 4 patients died at follow-up, all for non-cardiac causes. One patient was lost to follow-up. Two patients (8%) underwent non-valve-related reoperation with 0% mortality. Residual mean gradient at follow-up was 7.2 ± 2.1 mmHg. Three patients (17%) presented with mild/moderate aortic incompetence and 89% of patients were in NYHA Class I-II at follow-up. At 9 years, actuarial freedom from valve-related reoperation and from structural valve deterioration was 100%. The SPF aortic prosthesis is a true pericardial stentless prosthesis suitable for the treatment of acute bacterial endocarditis. Intermediate-time results in terms of freedom from reoperation, structural valve deterioration and

Actuation and Control of a Micro Electrohydraulic Digital Servo Valve

Energy Technology Data Exchange (ETDEWEB)

Yu, Z Q; Hu, M J; Pei, X; Ruan, J [MOE Key Laboratory of Mechanical Manufacture and Automation Zhejiang University of Technology, 310014 (China)

2006-10-15

Structure of the micro digital servo valve is given. A micro stepper motor is used as electrical-to-mechanical interface of the valve. A special mechanical device is designed to convert the rotation of the stepper motor into the linear motion of the spool. This moving conversion device functions through an eccentric ball head rigidly connected to the axis of the stepper motor and plugged into a slot at the central spool land. While the stepper motor rotates, the eccentric ball head will actuate the spool to make a linear motion. Unlike conventional servo or proportional valves, in which the spool is forced to central position by a spring force, when the current supply is switched off, the digital valve has a program to control the spool to its central position each time the electrical power supply is switched on or off. The two end screws are used to adjust the position of the sleeve to sustain a mechanical central position coincided with electrical central position given by the stepper motor after initialization. The adjustment has to be carried once before the first time the servo valve is put into service. This paper presents theoretical analysis and experimental study of dynamic characteristics of the proposed micro digital servo valve. Experimental results demonstrated that the valve takes the advantage of high accuracy and fast response.

Actuation and Control of a Micro Electrohydraulic Digital Servo Valve

International Nuclear Information System (INIS)

Yu, Z Q; Hu, M J; Pei, X; Ruan, J

2006-01-01

Structure of the micro digital servo valve is given. A micro stepper motor is used as electrical-to-mechanical interface of the valve. A special mechanical device is designed to convert the rotation of the stepper motor into the linear motion of the spool. This moving conversion device functions through an eccentric ball head rigidly connected to the axis of the stepper motor and plugged into a slot at the central spool land. While the stepper motor rotates, the eccentric ball head will actuate the spool to make a linear motion. Unlike conventional servo or proportional valves, in which the spool is forced to central position by a spring force, when the current supply is switched off, the digital valve has a program to control the spool to its central position each time the electrical power supply is switched on or off. The two end screws are used to adjust the position of the sleeve to sustain a mechanical central position coincided with electrical central position given by the stepper motor after initialization. The adjustment has to be carried once before the first time the servo valve is put into service. This paper presents theoretical analysis and experimental study of dynamic characteristics of the proposed micro digital servo valve. Experimental results demonstrated that the valve takes the advantage of high accuracy and fast response

Troca valvar aórtica com diferentes próteses: existem diferenças nos resultados da fase hospitalar? Aortic valve replacement with different types of prosthesis: are there differences in the outcomes during hospital phase?

Directory of Open Access Journals (Sweden)

Gibran Roder Feguri

2008-12-01

Full Text Available OBJETIVOS: Analisar dados intra-operatórios e possíveis diferenças na evolução clínica da fase hospitalar de pós-operatório da troca valvar aórtica com diferentes próteses. MÉTODOS: Análise de 60 pacientes, divididos em três grupos: os submetidos a troca valvar por prótese biológica (20; por prótese mecânica (20; e finalmente, por valva homóloga (20. A média da idade foi de 51,1 anos; 60% eram do sexo masculino e 40% do feminino; 86,7% estavam em NYHA II ou III; 63,3% eram hipertensos, 18,3% diabéticos; a etiologia valvar foi degenerativa em 39%, reumática em 36% e endocardite em 15%. RESULTADOS: A mortalidade hospitalar foi de 5%; não houve diferenças entre os grupos na incidência de choque séptico ou cardiogênico, insuficiência renal aguda, arritmias no centro cirúrgico e na unidade de terapia intensiva (UTI, assim como para o tempo de internação na UTI e tempo de ventilação mecânica. Houve diferença estatística nos tempos de circulação extracorpórea (P=0,02 e pinçamento aórtico (POBJECTIVE: To analyze intraoperative data and possible differences in clinical evolution during postoperative hospital phase for aortic valve replacement surgery using different types of prosthesis. METHODS: Analysis of 60 patients divided into three groups. Valve replacement with bioprosthesis (20, mechanical prosthesis (20 and homologous valve (20. The mean age was 51.1, 60% were male and 40% female patients; 86.7 % were in NYHA II or III; 63.3% presented arterial hypertension and 18.3% had diabetes. Aetiology of valve disease was degenerative for 39%, rheumatic for 36% and endocardits for 15%. RESULTS: The hospital mortality was 5%; there were no differences in the incidence of septical or cardiogenic shock, acute renal failure, rhythms disorders during surgery or intensive care, neither for total time in intensive care and mechanical ventilation. However, there was statistical differences as regards the cardiopulmonary

Development of linear flow rate control system for eccentric butter-fly valve

International Nuclear Information System (INIS)

Kwak, K. K.; Cho, S. W.; Park, J. S.; Cho, J. H.; Song, I. T.; Kim, J. G.; Kwon, S. J.; Kim, I. J.; Park, W. K.

1999-12-01

Butter-fly valves are advantageous over gate, globe, plug, and ball valves in a variety of installations, particularly in the large sizes. The purpose of this project development of linear flow rate control system for eccentric butter-fly valve (intelligent butter-fly valve system). The intelligent butter-fly valve system consist of a valve body, micro controller. The micro controller consist of torque control system, pressure censor, worm and worm gear and communication line etc. The characteristics of intelligent butter-fly valve system as follows: Linear flow rate control function. Digital remote control function. guard function. Self-checking function. (author)

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

Science.gov (United States)

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.

Prosthetic tricuspid valve dysfunction assessed by three-dimensional transthoracic and transesophageal echocardiography.

Science.gov (United States)

Yuasa, Toshinori; Takasaki, Kunitsugu; Mizukami, Naoko; Ueya, Nami; Kubota, Kayoko; Horizoe, Yoshihisa; Chaen, Hideto; Kuwahara, Eiji; Kisanuki, Akira; Hamasaki, Shuichi

2013-09-01

A 39-year-old male who had undergone tricuspid valve replacement for severe tricuspid regurgitation was admitted with palpitation and general edema. Two-dimensional (2D) echocardiography showed tricuspid prosthetic valve dysfunction. Additional three-dimensional (3D) transthoracic and transesophageal echocardiography (TEE) could clearly demonstrate the disabilities of the mechanical tricuspid valve. Particularly, 3D TEE demonstrated a mass located on the right ventricular side of the tricuspid prosthesis, which may have caused the stuck disk. This observation was confirmed by intra-operative findings.

MECHANICAL HEART-VALVE PROSTHESES - SOUND LEVEL AND RELATED COMPLAINTS

NARCIS (Netherlands)

LAURENS, RRP; WIT, HP; EBELS, T

In a randomised study, we investigated the sound production of mechanical heart valve prostheses and the complaints related to this sound. The CarboMedics, Bjork-Shiley monostrut and StJude Medical prostheses were compared. A-weighted levels of the pulse-like sound produced by the prosthesis were

The use of valves in the SAGD process

Energy Technology Data Exchange (ETDEWEB)

Romano, Michael A. [Global Marketing, Oil and Gas, Tyco Valves and Controls (United States)

2011-07-01

Steam-assisted gravity drainage (SAGD) is a developing technology, the aim of which is to increase production of bitumen while minimizing its environmental footprint. Valves must meet the process conditions of the operations, which depend on weel depth: deeper reservoirs of bitumen require higher steam injection pressure. A wide range of valves is used throughout the SAGD process. In the water softening plant, butterfly and process lined valves are used. HP gate valves are used for isolation, globe valves for vents/drains/bypasses, along with ARC valves for steam and booster pump projection with steam traps on injection lines in steam injection. Isolation valves are used throughout the low pressure process including ball, gate and triple-offset valves. Pressure management is carried out on all pressure vessels and lines. Control and choke valves are installed on well pads and production. Instrumentation, actuation and controls are installed throughout. In the ideal situation, suppliers and process engineers would work together in the early stages of a project.

Fairchild Stratos Division's Type II prototype lockhopper valve: METC Prototype Test Valve No. F-1 prototype lockhopper valve-testing and development project. Static test report

Energy Technology Data Exchange (ETDEWEB)

Goff, D. R.; Cutright, R. L.; Griffith, R. A.; Loomis, R. B.; Maxfield, D. A.; Moritz, R. S.

1981-10-01

METC Prototype Test Valve No. F-1 is a hybrid design, based on a segmented ball termed a visor valve, developed and manufactured by Fairchild Stratos Division under contract to the Department of Energy. The valve uses a visor arm that rotates into position and then translates to seal. This valve conditionally completed static testing at METC with clean gas to pressures of 1600 psig and internal valve temperatures to 600/sup 0/F. External leakage was excessive due to leakage through the stuffing box, purge fittings, external bolts, and other assemblies. The stuffing box was repacked several times and redesigned midway through the testing, but external leakage was still excessive. Internal leakage through the seats, except for a few anomalies, was very low throughout the 2409 cycles of testing. As shown by the low internal leakage, the visor valve concept appears to have potential for lock-hopper valve applications. The problems that are present with METC Prototype Test Valve No. F-1 are in the seals, which are equivalent to the shaft and bonnet seals in standard valve designs. The operating conditions at these seals are well within the capabilities of available seal designs and materials. Further engineering and minor modifications should be able to resolve the problems identified during static testing.

Short-term and mid-term results with the Sorin Freedom Solo aortic valve.

Science.gov (United States)

Ustunsoy, Hasim; Yasim, Alptekin; Deniz, Hayati; Gokaslan, Gokhan; Ozcaliskan, Ozerdem

2013-03-01

The study aim was to present the short- and mid-term results for patients who underwent aortic valve replacement (AVR) with the Sorin Freedom Solo third-generation stentless prosthetic valve. AVR with a Sorin Freedom Solo valve was performed in 14 patients between March 2006 and March 2011. Patients aged > or = 60 years (male:female ratio 6:8; mean age 73.28 +/- 5.42 years) who required AVR with the Sorin Freedom Solo valve according to the surgeon's choice were included in the study. The valvular prosthesis was implanted in the supra-annular position, using a single suture line. Eight patients underwent an isolated AVR; combined interventions were carried out in the other patients due to concomitant cardiac disease. One patient died during the immediate perioperative period, and two more during the follow up, from non-cardiac causes. The mean maximum transvalvular gradient of patients with aortic stenosis was 88.1 +/- 20.2 mmHg, and this fell to 26.4 +/- 7.6 mmHg during the early postoperative period. The mean gradient at one year of follow up was further decreased to 19.4 +/- 5.3 mmHg. The left ventricular end-diastolic and end-systolic diameters were also significantly reduced, from 4.8 +/- 0.9 to 4.3 +/- 0.6 cm and from 3.2 +/- 0.6 to 2.8 +/- 5.3 cm, respectively. The average left ventricular ejection fraction was 60.2 +/- 4.9% preoperatively, and 63.2 +/- 2.1% at one year after surgery (p = NS). No paravalvular leakage, endocarditis, prosthesis failure or neurologic events were reported among patients. The Sorin Freedom Solo stentless valve has provided good early and intermediate-term results. Implantation of the prosthesis is straightforward, with low rates of morbidity and mortality. However, these data require further support from larger patient series and long-term follow up.

Initial experience with xenograft bioconduit for the treatment of complex prosthetic valve endocarditis.

Science.gov (United States)

Roubelakis, Apostolos; Karangelis, Dimos; Sadeque, Syed; Yanagawa, Bobby; Modi, Amit; Barlow, Clifford W; Livesey, Steven A; Ohri, Sunil K

2017-07-01

The treatment of complex prosthetic valve endocarditis (PVE) with aortic root abscess remains a surgical challenge. Several studies support the use of biological tissues to minimize the risk of recurrent infection. We present our initial surgical experience with the use of an aortic xenograft conduit for aortic valve and root replacement. Between October 2013 and August 2015, 15 xenograft bioconduits were implanted for complex PVE with abscess (13.3% female). In 6 patients, concomitant procedures were performed: coronary bypass (n=1), mitral valve replacement (n=5) and tricuspid annuloplasty (n=1). The mean age at operation was 60.3±15.5 years. The mean Logistic European system for cardiac operating risk evaluation (EuroSCORE) was 46.6±23.6. The median follow-up time was 607±328 days (range: 172-1074 days). There were two in-hospital deaths (14.3% mortality), two strokes (14.3%) and seven patients required permanent pacemaker insertion for conduction abnormalities (46.7%). The mean length of hospital stay was 26 days. At pre-discharge echocardiography, the conduit mean gradient was 9.3±3.3mmHg and there was either none (n=6), trace (n=6) or mild aortic insufficiency (n=1). There was no incidence of mid-term death, prosthesis-related complications or recurrent endocarditis. Xenograft bioconduits may be safe and effective for aortic valve and root replacement for complex PVE with aortic root abscess. Although excess early mortality reflects the complexity of the patient population, there was good valve hemodynamics, with no incidence of recurrent endocarditis or prosthesis failure in the mid-term. Our data support the continued use and evaluation of this biological prosthesis in this high-risk patient cohort.

Noninvasive radioisotopic technique for detection of platelet deposition in mitral valve prostheses and quantitation of visceral microembolism in dogs

International Nuclear Information System (INIS)

Dewanjee, M.K.; Fuster, V.; Rao, S.A.; Forshaw, P.L.; Kaye, M.P.

1983-01-01

A noninvasive technique has been developed in the dog model for imaging, with a gamma camera, the platelet deposition on Bjoerk-Shiley mitral valve prostheses early postoperatively. At 25 hours after implantation of the prosthesis and 24 hours after intravenous administration of 400 to 500 microCi of platelets labeled with indium-111, the platelet deposition in the sewing ring and perivalvular cardiac tissue can be clearly delineated in a scintiphotograph. An in vitro technique was also developed for quantitation of visceral microemboli in brain, lungs, kidneys, and other tissues. Biodistribution of the labeled platelets was quantitated, and the tissue/blood radioactivity ratio was determined in 22 dogs in four groups: unoperated normal dogs, sham-operated dogs, prosthesis-implanted dogs, and prosthesis-implanted dogs treated with dipyridamole before and aspirin and dipyridamole immediately after operation. Fifteen to 20% of total platelets were consumed as a consequence of the surgical procedure. On quantitation, we found that platelet deposition on the components of the prostheses was significantly reduced in prosthesis-implanted animals treated with dipyridamole and aspirin when compared with prosthesis-implanted, untreated dogs. All prosthesis-implanted animals considered together had a twofold to fourfold increase in tissue/blood radioactivity ratio in comparison with unoperated and sham-operated animals, an indication that the viscera work as filters and trap platelet microemboli that are presumably produced in the region of the mitral valve prostheses. In the dog model, indium-111-labeled platelets thus provide a sensitive marker for noninvasive imaging of platelet deposition on mechanical mitral valve prostheses, in vitro evaluation of platelet microembolism in viscera, in vitro quantitation of surgical consumption of platelets, and evaluation of platelet-inhibitor drugs

Dysfunction of mechanical heart valve prosthesis: experience with surgical management in 48 patients

Science.gov (United States)

Ma, Wei-Guo; Hou, Bin; Abdurusul, Adiljan; Gong, Ding-Xu; Tang, Yue; Chang, Qian; Xu, Jian-Ping

2015-01-01

Background Dysfunction of mechanical heart valve prostheses is an unusual but potentially lethal complication after mechanical prosthetic valve replacement. We seek to report our experience with mechanical valve dysfunction regarding etiology, surgical techniques and early outcomes. Methods Clinical data of 48 patients with mechanical valve dysfunction surgically treated between October 1996 and June 2011 were analyzed. Results Mean age was 43.7±10.9 years and 34 were female (70.8%). The median interval from primary valve implantation to dysfunction was 44.5 months (range, 1 hour to 20 years). There were 21 emergent and 27 elective reoperations. The etiology was thrombosis in 19 cases (39.6%), pannus in 12 (25%), thrombosis and pannus in 11 (22.9%), improper disc orientation in 2 (4.1%), missing leaflet in 1 (2.1%), excessively long knot end in 1 (2.1%), endogenous factor in 1 (2.1%) and unidentified in 1 (2.1%). Surgical procedure was mechanical valve replacement in 37 cases (77.1%), bioprosthetic valve replacement in 7 (14.9%), disc rotation in 2 (4.2%) and excision of excessive knot end in 1 (2.1%). Early deaths occurred in 7 patients (14.6%), due to low cardiac output in 3 (6.3%), multi-organ failure in 2 (4.2%) and refractory ventricular fibrillation in 2 (4.2%). Complications occurred in 10 patients (20.8%). Conclusions Surgical management of mechanical valve dysfunction is associated with significant mortality and morbidity. Earlier identification and prompt reoperation are vital to achieving better clinical outcomes. The high incidence of thrombosis in this series highlights the need for adequate anticoagulation and regular follow-up after mechanical valve replacement. PMID:26793354

Gate valve and motor-operator research findings

International Nuclear Information System (INIS)

Steele, R. Jr.; DeWall, K.G.; Watkins, J.C.; Russell, M.J.; Bramwell, D.

1995-09-01

This report provides an update on the valve research being sponsored by the US Nuclear Regulatory Commission (NRC) and conducted at the Idaho National Engineering Laboratory (INEL). The research addresses the need to provide assurance that motor-operated valves can perform their intended safety function, usually to open or close against specified (design basis) flow and pressure loads. This report describes several important developments: Two methods for estimating or bounding the design basis stem factor (in rising-stem valves), using data from tests less severe than design basis tests; a new correlation for evaluating the opening responses of gate valves and for predicting opening requirements; an extrapolation method that uses the results of a best effort flow test to estimate the design basis closing requirements of a gate valve that exhibits atypical responses (peak force occurs before flow isolation); and the extension of the original INEL closing correlation to include low- flow and low-pressure loads. The report also includes a general approach, presented in step-by-step format, for determining operating margins for rising-stem valves (gate valves and globe valves) as well as quarter-turn valves (ball valves and butterfly valves)

Depth of valve implantation, conduction disturbances and pacemaker implantation with CoreValve and CoreValve Accutrak system for Transcatheter Aortic Valve Implantation, a multi-center study.

Science.gov (United States)

Lenders, Guy D; Collas, Valérie; Hernandez, José Maria; Legrand, Victor; Danenberg, Haim D; den Heijer, Peter; Rodrigus, Inez E; Paelinck, Bernard P; Vrints, Christiaan J; Bosmans, Johan M

2014-10-20

Transcatheter Aortic Valve Implantation (TAVI) is now considered an indispensable treatment strategy in high operative risk patients with severe, symptomatic aortic stenosis. However, conduction disturbances and the need for Permanent Pacemaker (PPM) implantation after TAVI with the CoreValve prosthesis still remain frequent. We aimed to evaluate the implantation depth, the incidence and predictors of new conduction disturbances, and the need for PPM implantation within the first month after TAVI, using the new Accutrak CoreValve delivery system (ACV), compared to the previous generation CoreValve (non-ACV). In 5 experienced TAVI-centers, a total of 120 consecutive non-ACV and 112 consecutive ACV patients were included (n=232). The mean depth of valve implantation (DVI) was 8.4±4.0 mm in the non-ACV group and 7.1±4.0 mm in the ACV group (p=0.034). The combined incidence of new PPM implantation and new LBBB was 71.2% in the non-ACV group compared to 50.5% in the ACV group (p=0.014). DVI (p=0.002), first degree AV block (p=0.018) and RBBB (p<0.001) were independent predictors of PPM implantation. DVI (p<0.001) and pre-existing first degree AV-block (p=0.021) were identified as significant predictors of new LBBB. DVI is an independent predictor of TAVI-related conduction disturbances and can be reduced by using the newer CoreValve Accutrak delivery system, resulting in a significantly lower incidence of new LBBB and new PPM implantation. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Delayed Presentation of a Giant Ascending Aortic Aneurysm following Aortic Valve Replacement

Directory of Open Access Journals (Sweden)

Tugrul Göncü

2009-01-01

Full Text Available Giant ascending aortic aneurysm formation following aortic valve replacement is rare. A 28-year-old man who underwent aortic valve replacement with a prosthetic valve for aortic regurgitation secondary to congenital bicuspid aortic valve about 10 years ago was diagnosed with a giant ascending aortic aneurysm about 16 cm in diameter in follow-up. The aneurysm was resected leaving the functional old mechanical prosthesis in place and implanted a 34-mm Hemashield woven graft, associated with the left and right coronary artery button implantation. Histological findings of the aortic aneurysm wall showed cystic medial necrosis. The postoperative course was uneventful and postoperative examination demonstrated good surgical results.

Comparison of polyetheretherketone (PEEK cage and cervical disc prostheses used in anterior cervical microscopic discectomy operations

Directory of Open Access Journals (Sweden)

Bahadir Alkan

2017-03-01

Conclusion: It was shown that in the cervical disc prosthesis group (Group A in the early and later postoperative period, intervertebral disk heights were preserved by a statistically significant amount compared to the PEEK cage group (Group B. However, this scenario did not create any significant difference in the clinical evaluation results. [Arch Clin Exp Surg 2017; 6(1.000: 1-8

Colombian experience with transcatheter aortic valve implantation of medtronic CoreValve.

Science.gov (United States)

Dager, Antonio E; Nuis, Rutger-Jan; Caicedo, Bernardo; Fonseca, Jaime A; Arana, Camilo; Cruz, Lidsa; Benitez, Luis M; Nader, Carlos A; Duenas, Eduardo; de Marchena, Eduardo J; O'Neill, William W; de Jaegere, Peter P

2012-01-01

At our institutions, increasing numbers of aortic stenosis patients were not candidates for surgical aortic valve replacement. Accordingly, we initiated the Cali Colombian Transcatheter Aortic Valve Implantation (TAVI) program. From March 2008 through January 2011, 53 consecutive patients (mean age, 79 ± 6 yr; men, 58%) underwent TAVI with the Medtronic CoreValve System, and data were prospectively collected. Our study's endpoints conformed with Valve Academic Research Consortium recommendations. We report our clinical results.Predicted mortality rates were 25% (interquartile range, 17%-34%) according to logistic EuroSCORE and 6% (interquartile range, 3%-8%) according to the Society of Thoracic Surgeons score. The 30-day mortality rate was 9% (3 intraprocedural deaths, 5 total). The combined 30-day safety endpoint was 30% (major vascular sequelae, 23%; life-threatening bleeding, 12%; myocardial infarction, 4%; major stroke, 4%; and acute kidney injury [stage 3], 2%). Eight patients (15%) required post-implantation balloon dilation and 2 (4%) required valve-in-valve implantation, for a technical device success rate of 77%. Mean peak transvalvular gradient decreased from 74 ± 29 to 17 ± 8 mmHg and mean transvalvular gradient from 40 ± 17 to 8 ± 4 mmHg (both P=0.001). Moderate or severe aortic regurgitation decreased from 32% to 18% (P=0.12) and mitral regurgitation from 32% to 13% (P=0.002). The 1-year survival rate was 81%.We found that TAVI with the CoreValve prosthesis was safe and feasible, with sustained long-term results, for treating aortic stenosis in patients at excessive surgical risk; nonetheless, serious adverse events occurred in 30% of the patients.

Fracture and embolization of a Björk-Shiley disc. Fatal failure of a prosthetic mitral valve.

Science.gov (United States)

Norenberg, D D; Evans, R W; Gundersen, A E; Abellera, R M

1977-12-01

A case of fracture of the disc occluder of a Bjork-Shiley mitral prosthesis with embolization of the disc fragments to distal aorta is presented. The possibility of valve dysfunction and the diagnostic value of echocardiography should be considered whenever acute heart failure occurs in a patient with an artificial valve.

Intracardiac echocardiography to diagnose pannus formation after aortic valve replacement.

Science.gov (United States)

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.

Mechanical valve at pulmonary site in adult TOF & absent pulmonary valve

Directory of Open Access Journals (Sweden)

Aayush Goyal

2017-09-01

Full Text Available Absent pulmonary valve syndrome (APVS is a rare congenital heart disease. Tetralogy of Fallot (TOF with APVS is a rare variation of TOF. These patients are commonly cyanotic at birth. Respiratory complaints predominate due to airway compression by dilated pulmonary arteries. Commonest age of presentation is infancy with anecdotal adult case-reports. Surgical treatment requires establishing unobstructed competent right ventricular outflow tract (RVOT often with monocusp or conduits. We present a novel technique of rendering RVOT competent by implanting a tilting disc mechanical prosthesis in a rare adult TOF with APVS.

Worcester 1 Inch Solenoid-Actuated Gas Operated SCHe System Valves

International Nuclear Information System (INIS)

VAN KATWIJK, C.

2000-01-01

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

Should the automatic exposure control system of CT be disabled when scanning patients with endoaortic stents or mechanical heart valves? A phantom study

Energy Technology Data Exchange (ETDEWEB)

Di Leo, Giovanni; Zanardo, Moreno; Secchi, Francesco [IRCCS Policlinico San Donato, Radiology Unit, San Donato Milanese (Italy); Spadavecchia, Chiara [Universita degli Studi di Milano, Dipartimento di Fisica, Milano (Italy); Veronese, Ivan [Universita degli Studi di Milano, Dipartimento di Fisica, Milano (Italy); Istituto Nazionale di Fisica Nucleare, Sezione di Milano (Italy); Cantone, Marie Claire [Istituto Nazionale di Fisica Nucleare, Sezione di Milano (Italy); Universita degli Studi di Milano, Dipartimento di Scienze Biomediche, Chirurgiche ed Odontoiatriche, Milano (Italy); Sardanelli, Francesco [IRCCS Policlinico San Donato, Radiology Unit, San Donato Milanese (Italy); Universita degli Studi di Milano, Department of Biomedical Science for Health, San Donato Milanese (Italy)

2017-07-15

To estimate the impact of endoaortic stents/mechanical heart valves on the output of an automatic exposure control (AEC) system and CT radiation dose. In this phantom study, seven stents and two valves were scanned with varying tube voltage (80/100/120 kVp), AEC activation (enabled/disabled) and prosthesis (present/absent), for a total of 540 scans. For each prosthesis, the dose-length product (DLP) was compared between scans with the AEC enabled and disabled. Percentage confidence levels for differences due to the prosthesis were calculated. Differences between results with the AEC enabled and disabled were not statistically significant (p ≥ 0.059). In the comparison with and without the prosthesis, DLP was unchanged at 80 kVp and 100 kVp, while a slight increase was observed at 120 kVp. The radiation dose varied from 1.8 mGy to 2.4 mGy without the prosthesis and from 1.8 mGy to 2.5 mGy with the prosthesis (confidence level 37-100%). The effect of the prosthesis on the AEC system was negligible and not clinically relevant. Therefore, disabling the AEC system when scanning these patients is not likely to provide a benefit. (orig.)

Should the automatic exposure control system of CT be disabled when scanning patients with endoaortic stents or mechanical heart valves? A phantom study

International Nuclear Information System (INIS)

Di Leo, Giovanni; Zanardo, Moreno; Secchi, Francesco; Spadavecchia, Chiara; Veronese, Ivan; Cantone, Marie Claire; Sardanelli, Francesco

2017-01-01

To estimate the impact of endoaortic stents/mechanical heart valves on the output of an automatic exposure control (AEC) system and CT radiation dose. In this phantom study, seven stents and two valves were scanned with varying tube voltage (80/100/120 kVp), AEC activation (enabled/disabled) and prosthesis (present/absent), for a total of 540 scans. For each prosthesis, the dose-length product (DLP) was compared between scans with the AEC enabled and disabled. Percentage confidence levels for differences due to the prosthesis were calculated. Differences between results with the AEC enabled and disabled were not statistically significant (p ≥ 0.059). In the comparison with and without the prosthesis, DLP was unchanged at 80 kVp and 100 kVp, while a slight increase was observed at 120 kVp. The radiation dose varied from 1.8 mGy to 2.4 mGy without the prosthesis and from 1.8 mGy to 2.5 mGy with the prosthesis (confidence level 37-100%). The effect of the prosthesis on the AEC system was negligible and not clinically relevant. Therefore, disabling the AEC system when scanning these patients is not likely to provide a benefit. (orig.)

Botulinum neurotoxin for management of intractable central leakage through a voice prosthesis in surgical voice restoration.

Science.gov (United States)

Mullan, G P J; Lee, M T; Clarke, P M

2006-09-01

Rehabilitation of voice and speech after total laryngectomy has become established practice in recent years. A voice prosthesis is placed within a surgically produced fistula between the trachea and upper oesophagus and acts as a one way valve, allowing passage of pulmonary air from the trachea into the oesophagus and preventing aspiration of food and fluid from the oesophagus into the trachea. Persistent leakage through or around these prostheses is a recognized complication, the aetiology of which can vary widely, from mechanical issues with the prostheses themselves to anatomical and physiological issues associated with the reconstructed pharynx. We report a new technique of using Dysport in the management of intractable central leakage due to premature and forceful closure of the upper oesophageal sphincter during swallowing. This resulted in the pooling of fluids around the posterior flange of the prosthesis. This, along with the increased pressure from the muscle contraction, led to central leakage, as identified on videofluoroscopy. An injection of Dysport paralysed the upper oesophageal sphincter, preventing pooling of fluids around the prosthesis and the forcing open of the valve. The effect was to eliminate the leakage, and the patient did not require further injections over the following 22 months.

Aortic Regurgitation in Patients Undergoing Transcatheter Aortic Valve Replacement With the Self-Expanding CoreValve Versus the Balloon-Expandable SAPIEN XT Valve.

Science.gov (United States)

Kiramijyan, Sarkis; Magalhaes, Marco A; Koifman, Edward; Didier, Romain; Escarcega, Ricardo O; Baker, Nevin C; Negi, Smita I; Minha, Sa'ar; Torguson, Rebecca; Jiaxiang, Gai; Asch, Federico M; Wang, Zuyue; Okubagzi, Petros; Gaglia, Michael A; Ben-Dor, Itsik; Satler, Lowell F; Pichard, Augusto D; Waksman, Ron

2016-05-01

The incidence of aortic regurgitation (AR) after transcatheter aortic valve replacement (TAVR) in a self-expanding and a balloon-expandable system is controversial. This study aimed to examine the incidence and severity of post-TAVR AR with the CoreValve (CV) versus the Edwards XT Valve (XT). Baseline, procedural, and postprocedural inhospital outcomes were compared. The primary end point was the incidence of post-TAVR AR of any severity, assessed with a transthoracic echocardiogram, in the CV versus XT groups. A multivariate logistic regression analysis was completed to evaluate for correlates of the primary end point. The secondary end points included the change in severity of AR at 30-day and 1-year follow-up. A total of 223 consecutive patients (53% men, mean age 82 years) who had transfemoral TAVR with either a CV (n = 119) or XT (n = 104) were evaluated. The rates of post-TAVR AR in the groups were similar, and there was no evidence of more-than-moderate AR in either group. There were significant differences in the rates of intraprocedural balloon postdilation with the CV (17.1%) versus XT valve (5.8%; p = 0.009) and in the rates of intraprocedural implantation of a second valve-in-valve prosthesis with the CV (9.9%) versus XT valve (2.2%; p = 0.036). There were no significant differences in inhospital safety outcomes between the 2 groups. In conclusion, the incidence of post-TAVR AR is similar between the CV and the XT valve when performed by experienced operators using optimal intraprocedural strategies, as deemed appropriate, to mitigate the severity of AR. Copyright © 2016 Elsevier Inc. All rights reserved.

Therapeutical attitudes in tooth supported overdentures with ball attachements. Case report

OpenAIRE

??ncu, AM; Melescanu Imre, M; Preoteasa, CT; Preoteasa, E

2014-01-01

Tooth supported overdenture with ball attachments has a number of advantages in prosthetics, but presents some difficulties as well, which sometimes make impossible the use of these anchoring systems; these difficulties should be well known. In this regard we present a suggestive case. It is the case of a patient, aged 57, who came for treatment, suffering from subtotal maxillary and mandibular edentulism (present 11 and 21, respectively 33 and 43), previously having an overdenture prosthesis...

Minimal access surgery for mitral valve endocarditis.

Science.gov (United States)

Barbero, Cristina; Marchetto, Giovanni; Ricci, Davide; Mancuso, Samuel; Boffini, Massimo; Cecchi, Enrico; De Rosa, Francesco Giuseppe; Rinaldi, Mauro

2017-08-01

Minimal access mitral valve surgery (MVS) has already proved to be feasible and effective with low perioperative mortality and excellent long-term outcomes. However, experience in more complex valve diseases such as infective endocarditis (IE) still remains limited. The aim of this retrospective study was to evaluate early and long-term results of minimal access MVS for IE. Data were entered into a dedicated database. Analysis was performed retrospectively for the 8-year period between January 2007 and April 2015. During the study period, 35 consecutive patients underwent minimal access MVS for IE at our department. Twenty-four had diagnosis of native MV endocarditis (68.6%) and 11 of mitral prosthesis endocarditis (31.4%).Thirty patients underwent early MVS (85.7%), and 5 patients were operated after the completion of antibiotic treatment (14.3%). Seven patients underwent MV repair (20%), 17 patients underwent MV replacement (48.6%), and 11 patients underwent mitral prosthesis replacement (31.4%). Thirty-day mortality was 11.4% (4 patients). No neurological or vascular complications were reported. One patient underwent reoperation for prosthesis IE relapse after 37 days. Overall actuarial survival rate at 1 and 5 years was 83%; freedom from MV reoperation and/or recurrence of IE at 1 and 5 years was 97%. Minimally invasive MVS for IE is feasible and associated with good early and long-term results. Preoperative accurate patient selection and transoesophageal echocardiography evaluation is mandatory for surgical planning. © The Author 2017. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

Fracture of the delivery balloon shaft during balloon-expandable prosthesis alignment during implantation of an Edwards SAPIEN 3.

Science.gov (United States)

Arai, Takahide; Hovasse, Thomas; Chevalier, Bernard

2018-04-01

The expandable sheath was designed with a lower profile in order to reduce the incidence of vascular complications of transcatheter aortic valve implantation using transfemoral approach. However, once the prosthesis has crossed the sheath, it could be difficult to retrieve it from the body. This is the first case of successful bail-out in an instance of delivery balloon shaft malfunction subsequent to the crossing of an expandable sheath during implantation of an Edwards SAPIEN 3 prosthesis. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Leaflet embolisation from Duromedics valves: a report of two cases.

Science.gov (United States)

Kumar, N; Balasundaram, S; Rickard, M; al Halees, Z; Duran, C M

1991-12-01

Embolization of parts of mechanical valves has been reported since the inception of prosthetic valve implantation. We report here two cases of embolization of one hemileaflet of a Duromedic bileaflet prosthesis in the mitral position due to a pivot fracture. Both presented with moderately severe mitral regurgitation and pulmonary edema and were successfully managed by replacement of the malfunctioning prostheses. The embolised disc was located in the left common iliac artery by abdominal ultrasound and removed by an inguinal, retroperitoneal approach with low morbidity. Both patients left hospital and are doing well to-date.

The optimal management of anti-thrombotic therapy after valve replacement: certainties and uncertainties.

Science.gov (United States)

Iung, Bernard; Rodés-Cabau, Josep

2014-11-07

Anti-thrombotic therapy after valve replacement encompasses a number of different situations. Long-term anticoagulation of mechanical prostheses uses vitamin K antagonists with a target international normalized ratio adapted to the characteristics of the prosthesis and the patient. The association of low-dose aspirin is systematic in the American guidelines and more restrictive in the European guidelines. Early heparin therapy is frequently used early after mechanical valve replacement, although there are no precise recommendations regarding timing, type, and dose of drug. Direct oral anticoagulants are presently contraindicated in patients with mechanical prosthesis. The main advantage of bioprostheses is the absence of long-term anticoagulant therapy. Early anticoagulation is indicated after valve replacement for mitral bioprostheses, whereas aspirin is now favoured early after bioprosthetic valve replacement in the aortic position. Early dual antiplatelet therapy is indicated after transcatheter aortic valve implantation, followed by single antiplatelet therapy. However, this relies on low levels of evidence and optimization of anti-thrombotic therapy is warranted in these high-risk patients. Although guidelines are consistent in most instances, discrepancies and the low-level of evidence of certain recommendations highlight the need for further controlled trials, in particular with regard to the combination of antiplatelet therapy with oral anticoagulant and the early post-operative anti-thrombotic therapy following the procedure. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2014. For permissions please email: journals.permissions@oup.com.

Red flag in the emergency department: fracture and primary failure of a prosthetic valve.

Science.gov (United States)

Ozsarac, Murat; Karcioglu, Ozgur; Ayrik, Cuneyt; Bozkurt, Seyran; Turkcuer, Ibrahim; Gumrukcu, Serhat

2005-07-01

This case report concerns a patient with fracture and primary dysfunction of a prosthetic valve. A 40-year-old man presented to the Emergency Department with a chief complaint of breakthrough pleuritic back pain and shortness of breath. Past surgical history was significant only for an aortic valve replacement and mitral valve replacement performed 16 years prior. The transthoracic echocardiography raised suspicion of prosthesis malposition. The patient was taken to the operating room by cardiothoracic surgeons for valve replacement. Operative findings revealed that a prosthetic valve leaflet in the mitral position had broken off. Primary prosthetic valve failure should not be overlooked in the differential diagnosis of patients with valve replacement and a rapidly deteriorating clinical course. Emergency echocardiography is a guide to convenient diagnosis and management. Early surgical consultation and early reparative surgery might prevent unnecessary morbidity and mortality.

Perceval S aortic valve implantation in an achondroplastic Dwarf.

Science.gov (United States)

Baikoussis, Nikolaos G; Argiriou, Michalis; Argiriou, Orestis; Dedeilias, Panagiotis

2016-01-01

Despite cardiovascular disease in patients with dwarfism is not rare; there is a lack of reports referring to cardiac interventions in such patients. Dwarfism may be due to achondroplasia or hormonal growth disorders. We present a 58-year-old woman with episodes of dyspnea for several months. She underwent on transthoracic echocardiography, and she diagnosed with severe aortic valve stenosis. She referred to our department for surgical treatment of this finding. In accordance of her anthropometric characteristics and her very small aortic annulus, we had the dilemma of prosthesis selection. We decided to implant a stentless valve to optimize her effective orifice area. Our aim is to present the successful Perceval S valve implantation and the descriptions of the problems coming across in operating on these special patients. To our knowledge, this is the first case patient in which a Perceval S valve is implanted according to the international bibliography.

Potential problems will drillstring safety valves

Energy Technology Data Exchange (ETDEWEB)

NONE

1996-06-01

In the paper titled ``New generation drill string safety valves,`` presented at the IADC Well Control Conference for Europe, Aberdeen, May 22--24, 1996, documented limitations of presently available drillstring safety valves commonly used as kelly valves and stabbing valves were presented, and industry efforts to develop solutions to these problems were described. Authors of the paper are B.A. Tarr and R.A. Sukup (Mobil E and P Technology Center, Dallas), Dr. R. Luy (ITE, Clausthal, Germany), G. Rabby (Hi-Kalibre, Edmonton, Alberta) and J. Mertsch (ITAG, Celle, Germany). In 1995, the Task Group developed a draft of a new spec, and a DSSV testing program was initiated as a joint industry project, with the Gas Research Institute (GRI) as the major sponsor. Two manufacturers, Hi-Kalibre and ITAG, agreed to build new valves for the testing program. Hi-Kalibre, Edmonton, Alberta, supplied an already-commercial twin floating ball valve for November 1995 testing. This product is being used by Tesco in its portable top drive system. ITAG of Germany supplied a radically improved DSSV design, which was tested in December, and was to be retested in May following modifications.

Tackling the Issue of High Postoperative Pacemaker Implantation Rates in Sutureless Aortic Valve Replacement: Should Balloon Inflation be Removed from the Implantation Method of the Perceval Prosthesis?

Science.gov (United States)

Charles Blouin, Mathieu; Bouhout, Ismail; Demers, Philippe; Carrier, Michel; Perrault, Louis; Lamarche, Yoan; El-Hamamsy, Ismail; Bouchard, Denis

2017-05-01

Sutureless aortic valve replacement (AVR) is an emerging alternative to standard AVR in elderly and high-risk patients. This procedure is associated with a high rate of postoperative permanent pacemaker implantation (PPI). The study aim was to assess the impact on the rate of PPI of implanting the Perceval prosthesis without using balloon inflation. A total of 159 patients who underwent sutureless AVR using the Perceval prosthesis was included. Balloon inflation was used in 132 patients (Balloon group) and not used in the remaining 27 (No-Balloon group). Clinical, echocardiographic and electrocardiographic outcomes were assessed. There was no significant difference in PPI rate between the two groups (26% for Balloon group versus 22% in No-Balloon group; p = 0.700). Balloon inflation had no significant impact on the incidence of paravalvular leaks (p = 0.839), or on the need to return to cardiopulmonary bypass (CPB) intraoperatively due to paravalvular leak or unsatisfactory deployment (p >0.999). Mean and peak transaortic pressure gradients were similar between the two groups (p = 0.417 and p = 0.522, respectively). Cross-clamp and CPB times were shorter in the No-Balloon group (49.6 ± 15.9 min versus 61.1 ± 25.6 min and 64.1 ± 26.3 min versus 79.6 ± 35.4 min, respectively; p = 0.027 and p = 0.012, respectively). The two groups had similar postoperative PPI rates. Implanting the Perceval prosthesis without balloon inflation is safe and had no impact on paravalvular leaks, intraoperative complications or hemodynamic results. Reductions in aortic cross-clamp time and CPB time were observed when the balloon was not used.

Investigation on Aerodynamic Noise Evaluation and Attenuation In a Globe Valve using CFD Analysis

Directory of Open Access Journals (Sweden)

S K Sreekala

2016-03-01

Full Text Available Noise pollution will soon become the third greatest menace to the human environment after air and water pollution. Since noise is a by-product of energy conversion, there will be increasing noise as the demand for energy for transportation, power, food, and chemicals increases. In the field of control equipment, noise produced by valves has become a focal point of attention .In this paper aerodynamic noise evaluation of a globe valve was carried out  using a three dimensional Computational Fluid Dynamic technique(CFD. The results obtained from numerical analysis are compared with the experimental measurements and are found   to be in good agreement. Reduction in sound pressure level was achieved by doubling the number of flow passages in the cage at full open condition and at the same operating conditions. Hence sound attenuation is established by changing the cage configuration with no change in total area of flow passage in the cage

Effect of the prosthesis-patient mismatch on long-term clinical outcomes after isolated aortic valve replacement for aortic stenosis: a prospective observational study.

Science.gov (United States)

Hong, Soonchang; Yi, Gijong; Youn, Young-Nam; Lee, Sak; Yoo, Kyung-Jong; Chang, Byung-Chul

2013-11-01

The effect of prosthesis-patient mismatch (PPM) on clinical outcomes after aortic valve replacement remains controversial. We evaluated effect of PPM on long-term clinical outcomes after isolated aortic valve replacement in patients with predominant aortic stenosis. We analyzed data from patients with predominant aortic stenosis who underwent isolated aortic valve replacement between January 1995 and July 2010. The indexed effective orifice area, obtained by dividing the in vivo effective orifice area by the patient's body surface area, was used to define PPM as clinically nonsignificant (group I, 224 patients), mild (group II, 52 patients), moderate (group III, 39 patients), and severe (group IV, 36 patients). Early survival was not significantly different among the groups, but overall survival was decreased gradually in group IV. Overall survival at 12 years was lower in group IV than in group I (92.8% ± 2.7% vs 67.0 ± 10.1, respectively; P = .001). Cardiac-related-death-free survival at 12 years was lower in patients with severe PPM. Left ventricular mass index decreased during the follow-up period in all groups. But left ventricular mass index was less decreased in group IV compared with groups I, II, and III. Age, severe PPM, and ejection fraction <40%, and New York Heart Association Functional Class IV were independent risk factors of overall survival on multivariate analysis. Severe PPM was an independent risk factor for cardiac-related death. Severe PPM showed an adverse effect on long-term survival, and was an independent risk factor for cardiac-related death. In addition, patients with severe PPM showed less decreasing left ventricular mass index during follow-up. Copyright © 2013 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

Flail Tricuspid Valve in an Adult Patient with Congenitally Corrected Transposition of the Great Arteries.

Science.gov (United States)

Meloni, Luigi; Abbruzzese, Piero A.; Pirisi, Raimondo; Cherchi, Angelo

1997-01-01

We describe a case of a 50-year-old woman with congenitally corrected transposition of the great vessels, in whom severe left-sided tricuspid (systemic atrioventricular) valve insufficiency was the only associated anomaly. The tricuspid valve was dysplastic and abnormally oriented toward the interventricular septum, without the downward displacement of Ebstein's anomaly. The mechanism of atrioventricular regurgitation was unusual in that it consisted of the rupture of chordae tendineae of both the anterior and septal leaflets. The left-sided tricuspid valve was replaced with a St. Jude prosthesis and the postoperative course was uneventful.

Methodology for Check Valve Selection to Maintain the Integrity of Pipeline against the Check Valve Slam for the KIJANG Research Reactor

Energy Technology Data Exchange (ETDEWEB)

Kim, Dayong; Yoon, Hyungi; Seo, Kyoungwoo; Kim, Seonhoon [KAERI, Daejeon (Korea, Republic of)

2016-05-15

The check valve slam results in a water hammer and unexpected system pressure rise in the pipeline. Sometimes, the pressure rise by check valve slam in the pipeline exceeds the design pressure and then it causes the rupture of pipeline. Therefore, check valve slam significantly influences on the integrity of pipe. Especially, this it is most likely to occur by check valve installed in the discharge of pump when one pump trips among the two or more running in parallel pump system. This study focuses on the check valve selection to maintain the integrity of PCS pipeline against the check valve slam. If design head for KJRR PCS pipeline is higher than the sum of static head and 11 m, any type check valves can be installed at the discharge of pump. However, if design head for KJRR PCS pipeline is lower than the sum of static head and 11 m, installation of swing and ball check on the discharge of pump must be avoid to prevent the rupture of PCS pipeline.

Methodology for Check Valve Selection to Maintain the Integrity of Pipeline against the Check Valve Slam for the KIJANG Research Reactor

International Nuclear Information System (INIS)

Kim, Dayong; Yoon, Hyungi; Seo, Kyoungwoo; Kim, Seonhoon

2016-01-01

The check valve slam results in a water hammer and unexpected system pressure rise in the pipeline. Sometimes, the pressure rise by check valve slam in the pipeline exceeds the design pressure and then it causes the rupture of pipeline. Therefore, check valve slam significantly influences on the integrity of pipe. Especially, this it is most likely to occur by check valve installed in the discharge of pump when one pump trips among the two or more running in parallel pump system. This study focuses on the check valve selection to maintain the integrity of PCS pipeline against the check valve slam. If design head for KJRR PCS pipeline is higher than the sum of static head and 11 m, any type check valves can be installed at the discharge of pump. However, if design head for KJRR PCS pipeline is lower than the sum of static head and 11 m, installation of swing and ball check on the discharge of pump must be avoid to prevent the rupture of PCS pipeline

Aortic Valve Predilatation with a Small Balloon, without Rapid Pacing, prior to Transfemoral Transcatheter Aortic Valve Replacement

Directory of Open Access Journals (Sweden)

Anupama Shivaraju

2018-01-01

Full Text Available Objectives. The aim of this study is to assess the feasibility and clinical outcome of transcatheter aortic valve replacement (TAVR using aortic valve predilatation (AVPD with a small, nonocclusive balloon. Background. Balloon aortic valvuloplasty (BAV under rapid pacing is generally performed in TAVR to ensure the passage and sufficient deployment of the prosthesis in the stenotic AV. BAV may cause serious complications, such as left ventricular stunning or cerebrovascular embolism. Methods. A cohort of 50 consecutive patients with severe aortic stenosis underwent transfemoral TAVR with the Edwards Sapien 3-heart valve. All patients underwent AVPD with a small, nonocclusive balloon (12 × 60 or 14 × 60 mm without rapid pacing. Procedural data and clinical outcomes were analyzed. Results. The mean age of the cohort was 81±6 years and the mean logistic EuroSCORE (European System for Cardiac Operative Risk Evaluation was 13±9. Crossing the AV and prosthesis implantation was successful in all cases. The postprocedural mean AV gradient was 12±5 mmHg. There were no cases of aortic regurgitation ≥ grade 2. No periprocedural stroke occurred. One patient (2% with chronic atrial fibrillation displayed a transient Wernicke aphasia occurring more than 24 hours after TAVR. Mortality was 0% at 30 days after procedure. Conclusion. In TAVR, AVPD with a small, nonocclusive balloon can be safely performed. By avoiding rapid pacing, this technique may be a valid alternative to traditional BAV. Whether or not the use of APVD without rapid pacing translates into less periprocedural complications needs to be assessed in future studies.

[Sudden and fatal malfunction of a Björk-Shiley prosthesis in mitral position due to rupture of the ventricular bracket and disk embolization].

Science.gov (United States)

Casarotto, D; Motta, A; Fabbri, A; Pugliese, P; Muneretto, C; Zanini, M; Sheiban, I

1985-04-01

Mechanical complications of prosthetic valves are increasing. The following report describes a case of fracture of a Björk-Shiley mitral prosthetic strut with dislogment of the valve occluder into the thoracic aorta. At the reoperation a new prosthesis was implanted but the patient died of acute heart failure. The diagnosis of valve disfunction must be made non invasively, because the time required for cardiac catherization usually constitutes a lethal delay. The only hope for survival is prompt surgical treatment.

Magnetic resonance imaging in patients with heart valve prostheses

International Nuclear Information System (INIS)

Bachmann, R.; Juengehuelsing, M.; Schicha, H.; Deutsch, H.J.; Sechtem, U.; Hilger, H.H.

1991-01-01

Artifical valve prostheses are often regarded as a contraindication for magnetic resonance imaging (MRI), although preliminary in vitro studies suggested, that patients with these metallic implants might safely undergo MR examination. This study reports on the experience with a group of 89 patients with 100 heart valve prostheses who were examined by spin-echo MR and gradient-echo MR. MR examination was performed in all patients without complications. The spin-echo sequence showed advantages in the depiction of anatomical structures like paravalvular abcesses. Anatomical structures adjacent to the artificial valve were clearly visivle and the metal components of the valves showes no or only small artifacts. Artifacts were accentuated when using gradient-echo sequences. Gradient-echo sequences provided valuable information regarding the presence of valvular insufficiency. Physiological valvular regurgitation was easy to differentiate from pathological paravalvular or transvalvular regurgitation. These results demonstrate that patients with artificial valve prostheses can be imaged by MR without risk and that prosthesis-induced artifacts do no interfere with image interpretation. (orig.) [de

Perceval S aortic valve implantation in an achondroplastic Dwarf

Directory of Open Access Journals (Sweden)

Nikolaos G Baikoussis

2016-01-01

Full Text Available Despite cardiovascular disease in patients with dwarfism is not rare; there is a lack of reports referring to cardiac interventions in such patients. Dwarfism may be due to achondroplasia or hormonal growth disorders. We present a 58-year-old woman with episodes of dyspnea for several months. She underwent on transthoracic echocardiography, and she diagnosed with severe aortic valve stenosis. She referred to our department for surgical treatment of this finding. In accordance of her anthropometric characteristics and her very small aortic annulus, we had the dilemma of prosthesis selection. We decided to implant a stentless valve to optimize her effective orifice area. Our aim is to present the successful Perceval S valve implantation and the descriptions of the problems coming across in operating on these special patients. To our knowledge, this is the first case patient in which a Perceval S valve is implanted according to the international bibliography.

Use of multidetector-row computed tomography scan to detect pannus formation in prosthetic mechanical aortic valves.

Science.gov (United States)

Aladmawi, Mohamed A; Pragliola, Claudio; Vriz, Olga; Galzerano, Domenico

2017-04-01

Obstruction of a mechanical aortic valve by pannus formation at the subvalvular level is a major long-term complication of aortic valve replacement (AVR). In fact, pannus is sometime difficult to differentiate from patient-prosthesis mismatch or valve thrombosis. In most cases cine-angiography and echocardiography, either transthoracic or transesophageal, cannot correctly visualize the complication when the leaflets show a normal mobility. Recent technological refinements made this difficult diagnosis possible by ECG-gated computed tomography (CT) scan which shows adequate images in 90% of the cases and can differentiate pannus from fresh and organized thrombus.

Turbulence downstream of subcoronary stentless and stented aortic valves.

Science.gov (United States)

Funder, Jonas Amstrup; Frost, Markus Winther; Wierup, Per; Klaaborg, Kaj-Erik; Hjortdal, Vibeke; Nygaard, Hans; Hasenkam, J Michael

2011-08-11

Regions of turbulence downstream of bioprosthetic heart valves may cause damage to blood components, vessel wall as well as to aortic valve leaflets. Stentless aortic heart valves are known to posses several hemodynamic benefits such as larger effective orifice areas, lower aortic transvalvular pressure difference and faster left ventricular mass regression compared with their stented counterpart. Whether this is reflected by diminished turbulence formation, remains to be shown. We implanted either stented pericardial valve prostheses (Mitroflow), stentless valve prostheses (Solo or Toronto SPV) in pigs or they preserved their native valves. Following surgery, blood velocity was measured in the cross sectional area downstream of the valves using 10MHz ultrasonic probes connected to a dedicated pulsed Doppler equipment. As a measure of turbulence, Reynolds normal stress (RNS) was calculated at two different blood pressures (baseline and 50% increase). We found no difference in maximum RNS measurements between any of the investigated valve groups. The native valve had significantly lower mean RNS values than the Mitroflow (p=0.004), Toronto SPV (p=0.008) and Solo valve (p=0.02). There were no statistically significant differences between the artificial valve groups (p=0.3). The mean RNS was significantly larger when increasing blood pressure (p=0.0006). We, thus, found no advantages for the stentless aortic valves compared with stented prosthesis in terms of lower maximum or mean RNS values. Native valves have a significantly lower mean RNS value than all investigated bioprostheses. Copyright © 2011 Elsevier Ltd. All rights reserved.

Three-dimensional flow structures past a bio-prosthetic valve in an in-vitro model of the aortic root

OpenAIRE

Hasler, David; Obrist, Dominik

2018-01-01

The flow field past a prosthetic aortic valve comprises many details that indicate whether the prosthesis is functioning well or not. It is, however, not yet fully understood how an optimal flow scenario would look, i.e. which subtleties of the fluid dynamics in place are essential regarding the durability and compatibility of a prosthetic valve. In this study, we measured and analyzed the 3D flow field in the vicinity of a bio-prosthetic heart valve in function of the aortic root size. The m...

Towards real-time cardiovascular magnetic resonance guided transarterial CoreValve implantation: in vivo evaluation in swine

Science.gov (United States)

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

Towards real-time cardiovascular magnetic resonance guided transarterial CoreValve implantation: in vivo evaluation in swine.

Science.gov (United States)

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.

Towards real-time cardiovascular magnetic resonance guided transarterial CoreValve implantation: in vivo evaluation in swine

Directory of Open Access Journals (Sweden)

Kahlert Philipp

2012-03-01

Full Text Available Abstract 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.

Tomographic PIV behind a prosthetic heart valve

Science.gov (United States)

Hasler, D.; Landolt, A.; Obrist, D.

2016-05-01

The instantaneous three-dimensional velocity field past a bioprosthetic heart valve was measured using tomographic particle image velocimetry. Two digital cameras were used together with a mirror setup to record PIV images from four different angles. Measurements were conducted in a transparent silicone phantom with a simplified geometry of the aortic root. The refraction indices of the silicone phantom and the working fluid were matched to minimize optical distortion from the flow field to the cameras. The silicone phantom of the aorta was integrated in a flow loop driven by a piston pump. Measurements were conducted for steady and pulsatile flow conditions. Results of the instantaneous, ensemble and phase-averaged flow field are presented. The three-dimensional velocity field reveals a flow topology, which can be related to features of the aortic valve prosthesis.

Platypnea-Orthodeoxia Syndrome after Transcatheter Aortic Valve Implantation

Directory of Open Access Journals (Sweden)

Andrew K. Roy

2016-01-01

Full Text Available Progressive dyspnea and hypoxaemia in the subacute phase after transcatheter aortic valve implantation (TAVI are uncommon and warrant immediate assessment of valve and prosthesis leaflet function to exclude thrombosis, as well as investigation for other causes related to the procedure, such as left ventricular dysfunction, pulmonary embolism, and respiratory sepsis. In this case, we report the observation of a patient presenting two weeks after TAVI with arterial hypoxaemia in an upright position, relieved by lying flat, and coupled with an intracardiac shunt detected on echocardiography in the absence of pulmonary hypertension, raising the suspicion of Platypnea-Orthodeoxia Syndrome (POS. Invasive intracardiac haemodynamic assessment showed a significant right-to-left shunt (Qp/Qs = 0.74, which confirmed the diagnosis, with subsequent closure of the intracardiac defect resulting in immediate relief of symptoms and hypoxaemia. To our knowledge, this is the first reported case of an interatrial defect and shunt causing Platypnea-Orthodeoxia Syndrome after transcatheter aortic valve implantation, resolved by percutaneous device closure.

A study on the noise characteristics of polymer ball bearings under various lubrication conditions

Science.gov (United States)

Dinç, S. K.; Temiz, V.; Kamburoǧlu, E.

2013-12-01

Polymer bearings are generally praised by the manufacturers for running silently. However such statements never go beyond qualitative assumptions. Therefore, studying polymer ball bearing noise would have been meaningful solely on the perspective of silent running machinery. On the other hand, the service life of a polymer ball bearing is unpredictable and there's no preventive maintenance practice that provides data regarding the condition of a polymer ball bearing. In this study, we assume that an investigation of their noise characteristics could also reveal clues concerning their performances. The main objective of this study is to determine the noise characteristics of polymer ball bearings lubricated with different lubricant greases of varying viscosity grades through experimental means. Sound pressure level measurements of SKF brand polymer bearings with polypropylene rings, polypropylene cage and glass balls were made with a 1/2 inch microphone in 1/3-octave bands, at frequencies up to 12.5 kHz, under various radial loads and rotational speeds. The bearings were mounted on a shaft driven by an AC motor with stepless speed control, adjustable between 0 - 1400 rpm. The ball bearings were running inside an acoustic chamber designed for the insulation of environmental noise and the noise of the motor at target frequencies. The resulting sound pressure level spectra were evaluated and the effects of the lubrication conditions on the noise of the ball bearing and possible diagnostic insight that could be gained through studying bearing noise characteristics were discussed.

Ball Screw Actuator Including a Compliant Ball Screw Stop

Science.gov (United States)

Wingett, Paul T. (Inventor); Hanlon, Casey (Inventor)

2017-01-01

An actuator includes a ball nut, a ball screw, and a ball screw stop. The ball nut is adapted to receive an input torque and in response rotates and supplies a drive force. The ball screw extends through the ball nut and has a first end and a second end. The ball screw receives the drive force from the ball nut and in response selectively translates between a retract position and a extend position. The ball screw stop is mounted on the ball screw proximate the first end to translate therewith. The ball screw stop engages the ball nut when the ball screw is in the extend position, translates, with compliance, a predetermined distance toward the first end upon engaging the ball nut, and prevents further rotation of the ball screw upon translating the predetermined distance.

Prediction of optimal deployment projection for transcatheter aortic valve replacement: angiographic 3-dimensional reconstruction of the aortic root versus multidetector computed tomography.

Science.gov (United States)

Binder, Ronald K; Leipsic, Jonathon; Wood, David; Moore, Teri; Toggweiler, Stefan; Willson, Alex; Gurvitch, Ronen; Freeman, Melanie; Webb, John G

2012-04-01

Identifying the optimal fluoroscopic projection of the aortic valve is important for successful transcatheter aortic valve replacement (TAVR). Various imaging modalities, including multidetector computed tomography (MDCT), have been proposed for prediction of the optimal deployment projection. We evaluated a method that provides 3-dimensional angiographic reconstructions (3DA) of the aortic root for prediction of the optimal deployment angle and compared it with MDCT. Forty patients undergoing transfemoral TAVR at St Paul's Hospital, Vancouver, Canada, were evaluated. All underwent preimplant 3DA and 68% underwent preimplant MDCT. Three-dimensional angiographic reconstructions were generated from images of a C-arm rotational aortic root angiogram during breath-hold, rapid ventricular pacing, and injection of 32 mL contrast medium at 8 mL/s. Two independent operators prospectively predicted perpendicular valve projections. The implant angle was chosen at the discretion of the physician performing TAVR. The angles from 3DA, from MDCT, the implant angle, and the postdeployment perpendicular prosthesis view were compared. The shortest distance from the postdeployment perpendicular prosthesis projection to the regression line of predicted perpendicular projections was calculated. All but 1 patient had adequate image quality for reproducible angle predictions. There was a significant correlation between 3DA and MDCT for prediction of perpendicular valve projections (r=0.682, Pregression line of predicted angles to the postdeployment prosthesis view was 5.1±4.6° for 3DA and 7.9±4.9° for MDCT (P=0.01). Three-dimensional angiographic reconstructions and MDCT are safe, practical, and accurate imaging modalities for identifying the optimal perpendicular valve deployment projection during TAVR.

The Blom-Singer tracheostoma valve as a valuable addition in the rehabilitation of the laryngectomized patient

NARCIS (Netherlands)

F.J.A. van den Hoogen; C.A. Meeuwis (Cees); M.J. Oudes (M.); P.A. Janssen (Patrick); H. Manni (Hans)

1996-01-01

textabstractProsthesis-assisted tracheo-esophageal speech has proven its value in post-laryngectomy voice rehabilitation, although manual occlusion of the tracheostoma during speech is necessary. In contrast a tracheostoma valve enables hands-free speech. We have now had experience with 30 patients

CMR assessment after a transapical-transcatheter aortic valve implantation

International Nuclear Information System (INIS)

Biere, Loïc; Pinaud, Frédéric; Delépine, Stéphane; Grall, Sylvain; Viot, Nathalie; Mateus, Victor; Rouleau, Frédéric; Corbeau, Jean-Jacques; Prunier, Fabrice

2014-01-01

Aims: To describe the time course of myocardial scarring after transapical-transcatheter aortic valve implantation (TA-TAVI) with the Edwards SAPIEN XT™ and the Edwards SAPIEN™ prosthesis in a 3-month follow-up study using cardiac magnetic resonance imaging (CMR). Methods: In 20 TA-TAVI patients, CMR was performed at discharge and 3 months (3M). Cine-MRI was used for left ventricular (LV) functional assessment, and late gadolinium enhancement (LGE) imaging was employed for detecting the presence of myocardial scarring. Special attention was given to any artifacts caused by the prosthesis, which were consequently defined using a three-grade artifact scale. Results: We systematically reported the presence of small LGE hyperintensity relating to the apical segment, with no variation found between discharge and 3 M (2.8 ± 1.6 g vs. 2.35 ± 1.1 g). LV ejection fraction, end-diastolic, and end-systolic volumes did not significantly vary. A small area of apical akinesia was observed, with no improvement at follow-up. Whereas the Edwards SAPIEN XT™ prosthesis and the Edwards SAPIEN™ prosthesis are both constituted by metallic stenting structure, the Edwards SAPIEN™ was responsible for a larger signal void, thus potentially limiting the diagnostic performance of CMR. Conclusions: CMR may be performed safely in the context of TA-TAVI. The presence of a very small apical infarction correlating with focal akinesia was observed. As expected, the Edwards SAPIEN XT™ prosthesis was shown to be particularly suitable for CMR assessment

Therapeutical attitudes in tooth supported overdentures with ball attachements. Case report.

Science.gov (United States)

Țâncu, A M; Melescanu Imre, M; Preoteasa, C T; Preoteasa, E

2014-01-01

Tooth supported overdenture with ball attachments has a number of advantages in prosthetics, but presents some difficulties as well, which sometimes make impossible the use of these anchoring systems; these difficulties should be well known. In this regard we present a suggestive case. It is the case of a patient, aged 57, who came for treatment, suffering from subtotal maxillary and mandibular edentulism (present 11 and 21, respectively 33 and 43), previously having an overdenture prosthesis on natural teeth, with special systems - ball attachment type, dissatisfied with the treatment (due to repeated fractures and functional intolerance to dentures). Clinical examination revealed an increase of the vertical dimension of occlusion and reduced prosthetic space at a correct, functional DVO value, aspects that were explaining the patient's reported complaints. As a therapeutic approach, having into consideration the balance conditions that were favorable for complete dentures and the large ball attachments volume, which did not allow keeping them at a functional DVO at any of the jaws, and the relatively young age of the patient, it was decided to remove the ball attachments and to keep the teeth for a simple overdenture, both to the maxillar and the mandible, over coronary reduced teeth, enough to allow the denture thickness at a functional DVO. Good end result of prosthetics, with stable, functional dentures, which were well tolerated and offered satisfaction to the patient, have led to an increased quality of life.

Therapeutical attitudes in tooth supported overdentures with ball attachements. Case report

Science.gov (United States)

Țâncu, AM; Melescanu Imre, M; Preoteasa, CT; Preoteasa, E

2014-01-01

Tooth supported overdenture with ball attachments has a number of advantages in prosthetics, but presents some difficulties as well, which sometimes make impossible the use of these anchoring systems; these difficulties should be well known. In this regard we present a suggestive case. It is the case of a patient, aged 57, who came for treatment, suffering from subtotal maxillary and mandibular edentulism (present 11 and 21, respectively 33 and 43), previously having an overdenture prosthesis on natural teeth, with special systems – ball attachment type, dissatisfied with the treatment (due to repeated fractures and functional intolerance to dentures). Clinical examination revealed an increase of the vertical dimension of occlusion and reduced prosthetic space at a correct, functional DVO value, aspects that were explaining the patient’s reported complaints. As a therapeutic approach, having into consideration the balance conditions that were favorable for complete dentures and the large ball attachments volume, which did not allow keeping them at a functional DVO at any of the jaws, and the relatively young age of the patient, it was decided to remove the ball attachments and to keep the teeth for a simple overdenture, both to the maxillar and the mandible, over coronary reduced teeth, enough to allow the denture thickness at a functional DVO. Good end result of prosthetics, with stable, functional dentures, which were well tolerated and offered satisfaction to the patient, have led to an increased quality of life. PMID:27057258

盘阀在Shell煤气化中的应用%Application of Disk Valve at Shell Coal Gasification

Institute of Scientific and Technical Information of China (English)

付荣申; 安铁夫

2012-01-01

Shell煤气化（SCGP）技术中采用进口球阀作为锁煤、锁渣、锁灰阀（锁斗阀）及平衡阀，存在易卡死、易磨损、寿命短等缺点，不能长周期运行，直接影响了整个煤气化装置的可靠性及经济效益。锁斗阀和平衡阀的另一种选择——盘阀，在以往煤气化项目中作为进口球阀的备阀被局部应用，取得了令人满意的效果。详细阐述了盘阀的工作原理、结构及特点，介绍了盘阀在甲醇项目中的具体应用情况。%Due to the disadvantage of easily blocked off, easy abrasion, short life and etc. of the adopted ball valve as lock coal valve, lock cinder valve and lock ash valve (lock hopper valve) and balance valve in SCGP, the valve can't work for a long time, and directly impact the reliability and economic benefit of whole coal gasification set. Disk valve is another choice instead of lock hopper valve and balance valve. Disk valves were used as the spare valve of ball valve in coal gasification projects in the past with positive result. The working principle, structure and characteristic of disk valve are expatiated in detail, and the application of disk valve at Methanol project is further disclosed.

Impact of Prosthesis-Patient Mismatch on Long-term Functional Capacity After Mechanical Aortic Valve Replacement.

Science.gov (United States)

Petit-Eisenmann, Hélène; Epailly, Eric; Velten, Michel; Radojevic, Jelena; Eisenmann, Bernard; Kremer, Hélène; Kindo, Michel

2016-12-01

The impact of prosthesis-patient mismatch (PPM) after aortic valve replacement (AVR) for aortic stenosis on exercise capacity remains controversial. The aim of this study was to analyze the long-term impact of PPM after mechanical AVR on maximal oxygen uptake (VO 2max ). The study included 75 patients who had undergone isolated mechanical AVR for aortic stenosis with normal left ventricular (LV) function between 1994 and 2012. Their functional capacity was evaluated on average 4.6 years after AVR by exercise testing, including measurement of their VO 2max , and by determining their New York Heart Association functional class and Short Form-36 score. Two groups were defined by measuring the patients' indexed effective orifice area (iEOA) by transthoracic echocardiography: a PPM group (iEOA < 0.85 cm 2 /m 2 ) and a no-PPM group (iEOA ≥ 0.85 cm 2 /m 2 ). PPM was present in 37.0% of the patients. The percentage of the predicted VO 2max achieved was significantly lower in the PPM group (86.7 ± 19.5% vs 97.5 ± 23.0% in the no-PPM group; P = 0.04). Compared with the no-PPM group, the PPM group contained fewer patients in New York Heart Association functional class I and their mean Short Form-36 physical component summary score was significantly lower. The mean transvalvular gradient was significantly higher in the PPM group than in the no-PPM group (P < 0.001). Systolic and diastolic function and LV mass had normalized in both groups. PPM is associated in the long term with moderate but significant impairment of functional capacity, despite optimal LV reverse remodelling and normalization of LV systolic and diastolic function. Copyright © 2016 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.

Mitral valve stenosis caused by abnormal pannus extension over the prosthetic ring and leaflets after Duran ring mitral annuloplasty.

Science.gov (United States)

Yunoki, Junji; Minato, Naoki; Katayama, Yuji; Sato, Hisashi

2009-01-01

We treated a 61-year-old woman with mitral stenosis caused by pannus formation after Duran ring annuloplasty. Pannus overgrowth on the ring with extension onto both leaflets narrowed the mitral orifice and severely restricted the mobility of the valve leaflets. Mitral valve replacement with a St. Jude Medical mechanical heart valve prosthesis was successfully performed, and the postoperative course was uneventful. Patients undergoing Duran ring annuloplasty should be followed up with the consideration of possible mitral stenosis caused by pannus extension, as the cause for pannus formation remains unclear.

Late complications in patients with Björk-Shiley and St. Jude Medical heart valve replacement.

Science.gov (United States)

Horstkotte, D; Körfer, R; Seipel, L; Bircks, W; Loogen, F

1983-09-01

Valve-related complications after Björk-Shiley mitral valve implantation (n = 475), aortic valve implantation (n = 424), or mitral-aortic valve implantation (n = 119) were compared with those after St. Jude Medical mitral valve replacement (n = 173), aortic valve replacement (n = 152), or mitral-aortic valve replacement (n = 69). All patients were placed on anticoagulant therapy with phenprocoumon early after operation. All patients had a comparable follow-up time of approximately 23 months, which showed that cumulative thromboembolic rates were significantly higher after St. Jude valve implantation than after Björk-Shiley valve implantation. Reoperations were necessary because of valve thrombosis (0.46%), perivalvular leakage (2.2%), or prosthetic valve endocarditis with perivalvular regurgitation (0.46%). One Björk-Shiley mitral valve prosthesis had to be replaced because of fracture of the outlet strut. Without significant intergroup differences, hemorrhage due to anticoagulant treatment was the most frequent complication. Thromboembolic complications were significantly more frequent after Björk-Shiley mitral, aortic, and double valve replacements than after St. Jude valve implantation. This may lead to consideration of changes in the prophylaxis of thrombus formations in the St. Jude valve, especially in aortic valve replacements, in patients with sinus rhythm.

Alternative causes of bioreaction to prosthetic heart valves: three cases with pannus formation.

Science.gov (United States)

Karakoyun, Süleyman; Gürsoy, Ozan Mustafa; Kalçık, Macit; Coban Kökten, Sermin; Ozkan, Mehmet

2014-01-01

Pannus formation is an infrequent but serious complication of prosthetic heart valve surgery. The cause of pannus is recognized as a bioreaction to the prostheses; histological investigations have shown that pannus comprises collagen and elastic tissues containing endothelial cells, chronic inflammatory cells, and myofibroblasts. However, the detailed mechanism of its formation has not been fully demonstrated. We aimed to evaluate the potential role of vascular endothelial growth factor (VEGF) and matrix metalloproteinase-2 (MMP-2) in the pathogenesis of pannus formation in three patients with mechanical prosthetic heart valves. Pannus specimens removed from the prostheses were fixed in 10% neutral-buffered formalin for 24 hours after surgical removal and paraffin-embedded using standard procedures. Serial sections were cut at 4 µm for immunohistochemistry analysis. Hematoxylin and eosin (HE) was used in the histological analysis. VEGF and MMP-2 were studied in the immunohistochemistry analysis. Three patients with mechanical prosthetic obstruction due to pannus overgrowth underwent redo valve surgery. In the first and second patients, the mitral prosthesis was explanted along with the pannus overgrowth. The third patient had both aortic and mitral prostheses; the aortic prosthesis was explanted with obstructive pannus formation, whereas the mitral valve was spared with excision of the nonobstructive pannus. The immunohistochemical study demonstrated the expressions of MMP-2 and VEGF in all of the pannus specimens acquired from these cases. VEGF and MMP-2 may play a role in the mechanism of pannus formation as the elements of the chronic active inflammatory process.

Electric Field Distribution and Switching Impulse Discharge under Shield Ball Surface Scratch Defect in an UHVDC Hall

Directory of Open Access Journals (Sweden)

Jianghai Geng

2018-05-01

Full Text Available The dimension and surface state of shielding fittings in ultra high voltage direct current (UHVDC converter station valve halls have a great influence on their surface electric field and switching impulse characteristics, which are important parameters confirming the air gap distance in the valve hall. The characteristics of impulse discharge under different lengths, dent degrees and burrs around the scratches of Φ1.3 m shield balls with a 2 m sphere-plane gap length were tested, in the UHVDC testing base of the Hebei Electric Power Research Institute. The discharge characteristics under the influence of the surface scratches of the shield ball were obtained. The results demonstrate that the discharge voltage of sphere-plane gap decreases obviously when there are unpolished scratches on the surface of the shield ball. However, when the scratches are polished, the discharge voltage has no significant impact. At the same time, a 1:1 full-scale impulse test model was established based on the finite element method. The electric field intensity and the space electric field distribution of the shield ball were obtained under the influence of scratches with or without burrs. The results of the simulation show that when the surface of the shield ball is smooth, the electric field distribution around it is even. The electric field intensity on the surface of the shield ball increases obviously when there are burrs around the scratches. When there is no burr around the scratches, the length and depth of the scratches have no obvious effect on its electric field distribution. Meanwhile, calculation results are consistent with test results. The results can provide an important basis for the design and optimization of shielding fittings, and technical support for its localization.

Degenerative processes in bioprosthetic mitral valves in juvenile pigs

Directory of Open Access Journals (Sweden)

Pedersen Torben B

2011-05-01

Full Text Available Abstract Background Glutaraldehyde-treated bioprosthetic heart valves are commonly used for replacement of diseased heart valves. However, calcification and wear limit their durability, and the development of new and improved bioprosthetic valve designs is needed and must be evaluated in a reliable animal model. We studied glutaraldehyde-treated valves 6 months after implantation to evaluate bioprosthetic valve complications in the mitral position in juvenile pigs. Materials The study material comprised eight, 5-month old, 60-kg pigs. All pigs received a size 27, glutaraldehyde-treated, stented, Carpentier-Edwards S.A.V. mitral valve prosthesis. After six months, echocardiography was performed, and the valves explanted for gross examination, high resolution X-ray, and histological evaluation. Results Five pigs survived the follow-up period. Preexplant echocardiography revealed a median peak and mean velocity of 1.61 m/s (range: 1.17-2.00 and 1.20 (SD = ±0.25, respectively, and a median peak and mean pressure difference of 10.42 mmHg (range: 5.83-16.55 and 6.51 mmHg (SD = ±2.57, respectively. Gross examination showed minor thrombotic depositions at two commissures in two valves and at all three commissures in three valves. High resolution X-ray imaging revealed different degrees of calcification in all explanted valves, primarily in the commissural and belly areas. In all valves, histological evaluation demonstrated various degrees of fibrous sheath formation, limited immunological infiltration, and no overgrowth of host endothelium. Conclusions Bioprosthetic glutaraldehyde-treated mitral valves can be implanted into the mitral position in pigs and function after 6 months. Echocardiographic data, calcification, and histological examinations were comparable to results obtained in sheep models and human demonstrating the suitability of the porcine model.

Infusion of the solid coal using pressure independent valves to regulate flow

Energy Technology Data Exchange (ETDEWEB)

Goretz, H G; Betting, K

1979-01-01

In order to improve infusion into the solid coal, attempts were made to effect this through several holes using a single pump; however, the regulation of the quantity of water directed into each hole by a ball-valve tap connected to the injection pump was shown to lack precision - gives the causes of this defect. Satisfactory regulation was obtained by means of pressure- independent flow valves which operate on the principle of hydrodynamic pressure balance; describes method of operation. Underground tests proved satisfactory even with large pressure variations. The problem of dirt penetration during down times was eliminated by installing a check valve. The system proves economical to run.

Early beneficial effect of preservation of papillo-annular continuity in mitral valve replacement on left ventricular function.

Science.gov (United States)

Dilip, D; Chandra, A; Rajashekhar, D; Padmanabhan, M

2001-05-01

Impairment of left ventricular (LV) function after mitral valve replacement (MVR) has been the most important factor to determine morbidity and mortality. With this in mind, LV performance in the postoperative period was assessed with and without preservation of papillo-annular continuity in MVR. Between March 1994 and August 1998, a total of 383 valve prostheses (202 MVR, 65 AVR, 58 MVR+AVR) were implanted in 325 patients, 177 of whom underwent MVR with Starr Edwards ball cage prostheses (the study group). Of these 177 patients, 105 had MVR with preservation of the posterior mitral leaflet (group I), and 72 had conventional MVR (group II). Predominant lesions were mitral stenosis in 81, mitral regurgitation in 42, and mixed mitral lesion (MS/MR) in 54. Concomitant tricuspid valve annuloplasty was performed in 13, and atrial septal defect repair in five. Sixteen patients underwent MVR for mitral restenosis. In-vivo performance of the prostheses and LV function was evaluated by M-mode and Doppler echocardiography. At 3-6 months clinical improvement was seen in NYHA class, with reduction in cardiothoracic ratio among patients with preserved papillo-annular continuity, irrespective of lesion type. Significant reductions (p versus 44.64 +/- 8.54 postop.; p versus 41.21 +/- 7.16 postop.; p versus 28.81 +/- 5.79 postop.; p versus 64.47 +/- 7.93; p <0.05). Further analysis of data in group I patients showed significant reductions in left atrial dimensions, LVESD and peak gradient, along with improved ejection fraction compared with conventional (group II) patients. Deterioration in LV function in patients undergoing conventional MVR indicates chordal resection as a putative mechanism. This study supports the concept that maintenance of continuity between the mitral annulus and papillary muscles has a beneficial effect on postoperative LV function, and is particularly important in patients with mitral stenosis with depressed preoperative LV systolic function.

Aperture Valve for the Mars Organic Molecule Analyzer (MOMA)

Science.gov (United States)

Hakun, Claef F.; Engler, Charles D.; Barber, Willie E.; Canham, John S.

2014-01-01

NASA's participation in the multi-nation ExoMars 2018 Rover mission includes a critical astrobiology Mass Spectrometer Instrument on the Rover called the Mars Organic Molecule Analyzer (MOMA). The Aperture Valve is a critical electromechanical valve used by the Mass Spectrometer to facilitate the transfer of ions from Martian soil to the Mass Spectrometer for analysis. The MOMA Aperture Valve development program will be discussed in terms of the Initial valve design and subsequent improvements that resulted from prototype testing. The Initial Aperture Valve concept seemed promising, based on calculations and perceived merits. However, performance results of this design were disappointing, due to delamination of TiN and DLC coatings applied to the Titanium base metals, causing debris from the coatings to seize the valve. While peer reviews and design trade studies are important forums to vet a concept design, results from testing should not be underestimated.Despite the lack of development progress to meet requirements, valuable information from weakness discovered in the Initial Valve design was used to develop a second, more robust Aperture valve. Based on a check-ball design, the ETU flight valve design resulted in significantly less surface area to create the seal. Moreover, PVD coatings were eliminated in favor of hardened, nonmagnetic corrosion resistant alloys. Test results were impressive, with the valve achieving five orders of magnitude better sealing leak rate over end of life requirements. Cycle life was equally impressive, achieving 280,000 cycles without failure.

Architecture of clathrin fullerene cages reflects a geometric constraint--the head-to-tail exclusion rule--and a preference for asymmetry.

Science.gov (United States)

Schein, Stan

2009-03-27

Fullerene cages have n trivalent vertices, 12 pentagonal faces, and (n-20)/2 hexagonal faces. The smallest cage in which all of the pentagons are surrounded by hexagons and thus isolated from each other has 60 vertices and is shaped like a soccer ball. The protein clathrin self-assembles into fullerene cages of a variety of sizes and shapes, including smaller ones with adjacent pentagons as well as larger ones, but the variety is limited. To explain the range of clathrin architecture and how these fullerene cages self-assemble, we proposed a hypothesis, the "head-to-tail exclusion rule" (the "Rule"). Of the 5769 small clathrin cage isomers with n< or =60 vertices and adjacent pentagons, the Rule permits just 15, three identified in 1976 and 12 others. A "weak version" of the Rule permits another 99. Based on cryo-electron tomography, Cheng et al. reported six raw clathrin fullerene cages. One was among the three identified in 1976. Here, (1) we identify the remaining five. (2) Four are new and are among the 12 others permitted by the Rule. (3) One, also new, is among the 99 weak version cages. (4) Of particular note, none of the remaining 5565 excluded cages has been identified. These findings provide powerful experimental confirmation of the Rule and the principle on which it is based. (5) Surprisingly, the newly identified clathrin cages are among the least symmetric of those permitted. (6) By devising a method for counting assembly paths, (7) we show that asymmetric cages can be assembled by larger numbers of paths, thus providing a kinetic explanation for the prevalence of asymmetric cages. (8) Finally, we show that operation during cage growth of the Rule greatly increases the likelihood of producing a closed fullerene cage, specifically one of those permitted, but efficient assembly still appears to require internal remodeling.

Design and Operating Characteristics of High-Speed, Small-Bore, Angular-Contact Ball Bearings

Science.gov (United States)

Pinel, Stanley I.; Signer, Hans R.; Zaretsky, Erwin V.

1998-01-01

The computer program SHABERTH was used to analyze 35-mm-bore, angular-contact ball bearings designed and manufactured for high-speed turbomachinery applications. Parametric tests of the bearings were conducted on a high-speed, high-temperature bearing tester and were compared with the computer predictions. Four bearing and cage designs were studied. The bearings were lubricated either by jet lubrication or through the split inner ring with and without outer-ring cooling. The predicted bearing life decreased with increasing speed because of increased operating contact stresses caused by changes in contact angle and centrifugal load. For thrust loads only, the difference in calculated life for the 24 deg. and 30 deg. contact-angle bearings was insignificant. However, for combined loading, the 24 deg. contact-angle bearing gave longer life. For split-inner-ring bearings, optimal operating conditions were obtained with a 24 deg. contact angle and an inner-ring, land-guided cage, using outer-ring cooling in conjunction with low lubricant flow rates. Lower temperature and power losses were obtained with a single-outer-ring, land-guided cage for the 24 deg. contact-angle bearing having a relieved inner ring and partially relieved outer ring. Inner-ring temperatures were independent of lubrication mode and cage design. In comparison with measured values, reasonably good engineering correlation was obtained using the computer program SHABERTH for predicted bearing power loss and for inner- and outer-ring temperatures. The Parker formula for XCAV (used in SHABERTH, a measure of oil volume in the bearing cavity) may need to be refined to reflect bearing lubrication mode, cage design, and location of cage-controlling land.

Aortic valve replacement with 17-mm St. Jude Medical prostheses for a small aortic root in elderly patients.

Science.gov (United States)

Takaseya, Tohru; Kawara, Takemi; Tokunaga, Shigehiko; Kohno, Michitaka; Oishi, Yasuhisa; Morita, Shigeki

2007-06-01

There are few reports about the optimal prosthesis for elderly patients who have small aortic roots with an aortic annular size of less than 19 mm. From October 2004 to October 2006, 11 women aged 70 years or older (mean age, 74.9 +/- 3.5 years) underwent aortic valve replacement with a 17-mm Regent prosthesis (St. Jude Medical, St. Paul, MN), with the size determined using the manufacturer's sizer. Clinical status and the results of preoperative and postoperative echocardiography were evaluated. The patients had a mean body surface area of 1.33 +/- 0.13 m2. Preoperative average New York Heart Association (NYHA) functional class was 2.5 +/- 0.7. Preoperative echocardiography showed a mean indexed effective orifice area of 0.33 +/- 0.14 cm2/m2 and a left ventricular mass index of 175 +/- 63 g/m2. Seven patients underwent associated procedures. Postoperative ventilation time was 14 +/- 5.6 hours, and the intensive care unit stay was 1.0 +/- 0.4 days. No patients died perioperatively. The NYHA functional class improved to class I in 9 patients. No obstruction of valve opening was observed. A significant increase in the mean indexed effective orifice area (0.87 +/- 0.10 cm2/m2) and regression of left ventricular mass index were found (114 +/- 46 cm2/m2) on postoperative echocardiography. Aortic valve replacement in elderly patients with small aortic roots (less than 19 mm) using a 17-mm Regent prosthesis showed satisfactory clinical and hemodynamic results.

Furnished cage system and hen well-being: Comparative effects of furnished cages and battery cages on behavioral exhibitions in White Leghorn chickens.

Science.gov (United States)

Pohle, K; Cheng, H-W

2009-08-01

The battery cage system is being banned in the European Union before or by 2012, and the furnished cage system will be the only cage system allowed after 2012. This study was conducted to examine the different effects of caging systems, furnished cages vs. battery cages, on bird behaviors. One hundred ninety-two 1-d-old non-beak-trimmed Hy-Line W-36 White Leghorn chicks were reared using standard management practices in raised wire cages. At 19 wk of age, the birds were randomly assigned into battery cages or furnished cages. The battery cages were commercial wire cages containing 6 birds per cage, providing 645 cm(2) of floor space per birds. The furnished cages had wire floors and solid metal walls, with perches, a dustbathing area, scratch pads, and a nestbox area with a concealment curtain. Based on the company recommendations, 10 birds were housed per cage, providing a stocking density of 610 cm(2) of floor space per bird. Behavioral observations were conducted using the Noldus Observer software package. The birds were observed at 5-min intervals for the entire light period. The birds housed in battery cages had higher posture and behavioral transitions and increased time spent walking and performing exploratory behavior (P birds housed in furnished cages had higher levels of preening (P birds. These results may suggest that furnished cages may be a favorable alternative system for housing birds by allowing them to perform certain natural behaviors.

Non-cardiac surgery in patients with prosthetic heart valves: a 12 years experience

International Nuclear Information System (INIS)

Akhtar, R.P.; Khan, J.S.; Abid, A.R.; Gardezi, S.J.R.

2007-01-01

To study patients with mechanical heart valves undergoing non-cardiac surgery and their anticoagulation management during these procedures. Patients with mechanical heart valves undergoing non-cardiac surgical operation during this period, were included. Their anticoagulation was monitored and anticoagulation related complications were recorded. In this study, 507 consecutive patients with a mechanical heart valve replacement were followed-up. Forty two (8.28%) patients underwent non-cardiac surgical operations of which 24 (57.1%) were for abdominal and non-abdominal surgeries, 5 (20.8%) were emergency and 19 (79.2%) were planned. There were 18 (42.9%) caesarean sections for pregnancies. Among the 24 procedures, there were 7(29.1%) laparotomies, 7(29.1%) hernia repairs, 2 (8.3%) cholecystectomies, 2 (8.3%) hysterectomies, 1(4.1%) craniotomy, 1(4.1%) spinal surgery for neuroblastoma, 1(4.1%) ankle fracture and 1(4.1%) carbuncle. No untoward valve or anticoagulation related complication was seen during this period. Patients with mechanical valve prosthesis on life-long anticoagulation, if managed properly, can undergo any type of noncardiac surgical operation with minimal risk. (author)

The tightness of the globe valves in the exploitations practice of the gas pipe-lines

International Nuclear Information System (INIS)

Pietrak, T.; Rudzki, Z.; Surmacz, W.

2006-01-01

Technological units of the Transit Gas Pipeline (i.e. Compressor Stations, Valve Stations, Stations or National Network Service Installations) have been fitted with Ball Valves as shut-off devices (block valves). Internal tightness of the valves' seat becomes major factor in securing proper service conditions during normal pipeline operation as well as for isolating of pipeline sections in emergency situations (loss of pipeline integrity or uncontrolled gas escape). Internal tightness of the valves is being inspected during scheduled maintenance of the pipeline units. Any leak revealed during inspection is being repaired, following instructions provided in the Manufacturer's Valve Manual. After a time, some cases have been identified, when repair of the revealed leak was found to be difficult, despite close following of the repair manuals. The paper presents analysis of the issue and corrective actions taken accordingly. (authors)

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

Science.gov (United States)

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.

Platelet thrombosis in cardiac-valve prostheses

International Nuclear Information System (INIS)

Dewanjee, M.K.

1989-01-01

The contribution of platelets and clotting factors in thrombosis on cardiovascular prostheses had been quantified with several tracers. Thrombus formation in vivo could be measured semiquantitatively in animal models and patients with indium-111, Technetium-99m labeled platelets, iodine-123, iodine-131 labeled fibrinogen, and In-111 and Tc-99m labeled antibody to the fibrinogen-receptor on the platelet- membrane, or fibrin. The early studies demonstrated that certain platelet-inhibitors, e.g. sulfinpyrazone, aspirin or aspirin- persantine increased platelet survival time with mechanical valves implanted in the baboon model and patients. Thrombus localization by imaging is possible for large thrombus on thrombogenic surface of prosthesis in the acute phase. The majority of thrombus was found in the sewing ring (Dacron) in the acute phase in both the mechanical and tissue valves. The amount of retained thrombus in both mechanical and tissue valves in our one-day study in the dog model was similar (< 1% if injected In-111 platelets = 5 billion platelets). As the fibrous ingrowth covered the sewing ring, the thrombus formation decreased significantly. Only a small amount of thrombus was found on the leaflets at one month in both the dog and calf models. 38 refs., 9 figs., 5 tabs

Platelet thrombosis in cardiac-valve prostheses

Energy Technology Data Exchange (ETDEWEB)

Dewanjee, M.K.

1989-01-01

The contribution of platelets and clotting factors in thrombosis on cardiovascular prostheses had been quantified with several tracers. Thrombus formation in vivo could be measured semiquantitatively in animal models and patients with indium-111, Technetium-99m labeled platelets, iodine-123, iodine-131 labeled fibrinogen, and In-111 and Tc-99m labeled antibody to the fibrinogen-receptor on the platelet- membrane, or fibrin. The early studies demonstrated that certain platelet-inhibitors, e.g. sulfinpyrazone, aspirin or aspirin- persantine increased platelet survival time with mechanical valves implanted in the baboon model and patients. Thrombus localization by imaging is possible for large thrombus on thrombogenic surface of prosthesis in the acute phase. The majority of thrombus was found in the sewing ring (Dacron) in the acute phase in both the mechanical and tissue valves. The amount of retained thrombus in both mechanical and tissue valves in our one-day study in the dog model was similar (< 1% if injected In-111 platelets = 5 billion platelets). As the fibrous ingrowth covered the sewing ring, the thrombus formation decreased significantly. Only a small amount of thrombus was found on the leaflets at one month in both the dog and calf models. 38 refs., 9 figs., 5 tabs.

Limitations of multimodality imaging in the diagnosis of pannus formation in prosthetic aortic valve and review of the literature.

Science.gov (United States)

Soumoulou, Juan Bautista; Cianciulli, Tomás Francisco; Zappi, Andrea; Cozzarin, Alberto; Saccheri, María Cristina; Lax, Jorge Alberto; Guidoin, Robert; Zhang, Ze

2015-04-26

Pannus formation is a rare complication and occurs almost exclusively in mechanical prosthetic valves. It consists of fibrous tissue that covers the surface of the prosthesis either concentrically or eccentrically, resulting in valve dysfunction. The pathophysiology seems to be associated to a chronic inflammatory process that explains the late and insidious clinical presentation. This diagnosis should be considered in patients with high transvalvular gradients on transthoracic echo, and workup should be completed with fluoroscopy and transesophageal echocardiography. Treatment is always surgical and recurrence is rare. We present a case of pannus formation in a prosthetic aortic valve and a review of the literature regarding this disorder.

Conduction disorders in the setting of transcatheter aortic valve implantation: a clinical perspective.

Science.gov (United States)

Fraccaro, Chiara; Napodano, Massimo; Tarantini, Giuseppe

2013-06-01

The presence of periprocedural conduction disorders (CDs) and the need for permanent pacemaker (PPM) after transcatheter aortic valve implantation (TAVI) are frequent findings in clinical practice. Notwithstanding, robust information on the prognostic and therapeutic implications of these complications are lacking. The newly occurrence of CD after TAVI seems related to the trauma of the conduction system during procedure. On the contrary, major predictors for PPM implantation after TAVI seem to be the use of CoreValve prosthesis (Medtronic, Minneapolis, MN) and the presence of CD before TAVI. An accurate pre-TAVI screening, careful valve implantation, as well as post-TAVI monitoring must be pursued to prevent avoidable PPM implantation. The aim of this report is to analyze the available data on this field and to propose some practical clinical tips to prevent or to manage these complications. Copyright © 2013 Wiley Periodicals, Inc.

Robotic lower limb prosthesis design through simultaneous computer optimizations of human and prosthesis costs

Science.gov (United States)

Handford, Matthew L.; Srinivasan, Manoj

2016-02-01

Robotic lower limb prostheses can improve the quality of life for amputees. Development of such devices, currently dominated by long prototyping periods, could be sped up by predictive simulations. In contrast to some amputee simulations which track experimentally determined non-amputee walking kinematics, here, we explicitly model the human-prosthesis interaction to produce a prediction of the user’s walking kinematics. We obtain simulations of an amputee using an ankle-foot prosthesis by simultaneously optimizing human movements and prosthesis actuation, minimizing a weighted sum of human metabolic and prosthesis costs. The resulting Pareto optimal solutions predict that increasing prosthesis energy cost, decreasing prosthesis mass, and allowing asymmetric gaits all decrease human metabolic rate for a given speed and alter human kinematics. The metabolic rates increase monotonically with speed. Remarkably, by performing an analogous optimization for a non-amputee human, we predict that an amputee walking with an appropriately optimized robotic prosthesis can have a lower metabolic cost - even lower than assuming that the non-amputee’s ankle torques are cost-free.

SLPMC- New Self Lubricating Polymer Matrix Composites for Journal and Ball Bearing Applications in Space

Science.gov (United States)

Merstallinger, A.; Macho, C.; Brodowski-Hanemann, G.; Bieringer, H.; Pambaguian, L.; Palladino, M.; Buttery, M.

2015-09-01

The paper is surveying the results of the ESA-project “SLPMC” covering the development of a self- lubricating polymer composite based on PTFE for use in bearings. The two targets of this project were to investigate lubrication mechanisms in PTFE-based composites under tribological conditions relevant to space applications (air, dry nitrogen, vacuum). And secondly, to develop a new composite to fulfil future needs by space applications. Hence, in the frame of this project several new composites based on PTFE-matrix with different kind of fillers were defined, manufactured and tested on material level. From the most promising variants bushes for journal bearings and cages for ball bearings were machined. Ball bearing tests were done in high vacuum up to 10 million revolutions.This paper summarises the main results from the project on material level focusing on tribological results derived by pin-on-disc tests. The influences of parameters like load, speed, atmosphere and temperature are discussed and compared to other already known materials. The paper also reports the findings from final ball bearing and plain bearing tests.

Molecular marriage through partner preferences in covalent cage formation and cage-to-cage transformation.

Science.gov (United States)

Acharyya, Koushik; Mukherjee, Sandip; Mukherjee, Partha Sarathi

2013-01-16

Unprecedented self-sorting of three-dimensional purely organic cages driven by dynamic covalent bonds is described. Four different cages were first synthesized by condensation of two triamines and two dialdehydes separately. When a mixture of all the components was allowed to react, only two cages were formed, which suggests a high-fidelity self-recognition. The issue of the preference of one triamine for a particular dialdehyde was further probed by transforming a non-preferred combination to either of the two preferred combinations by reacting it with the appropriate triamine or dialdehyde.

Fabrication of a Customized Ball Abutment to Correct a Nonparallel Implant Abutment for a Mandibular Implant-Supported Removable Partial Prosthesis: A Case Report

OpenAIRE

Hossein Dasht; Mohammadreza Nakhaei; Nafiseh teimouri

2017-01-01

Introduction: While using an implant-supported removable partial prosthesis, the implant abutments should be parallel to one another along the path of insertion. If the implants and their attachments are placed vertically on a similar occlusal plane, not only is the retention improved, the prosthesis will also be maintained for a longer period. Case Report: A 65-year-old male patient referred to the School of Dentistry in Mashhad, Iran with complaints of discomfort with the removable partial ...

Prevalence of pannus formation after aortic valve replacement: clinical aspects and surgical management.

Science.gov (United States)

Sakamoto, Yoshimasa; Hashimoto, Kazuhiro; Okuyama, Hiroshi; Ishii, Shinichi; Shingo, Taguchi; Kagawa, Hiroshi

2006-01-01

Pannus formation after aortic valve replacement is not common, but obstruction due to chronic pannus is one of the most serious complications of valve replacement. The causes of pannus formation are still unknown and effective preventive methods have not been fully elucidated. We reviewed our clinical experience of all patients who underwent reoperation for prosthetic aortic valve obstruction due to pannus formation between 1973 and 2004. We compared the initial 18-year period of surgery, when the Björk-Shiley tilting-disk valve was used, and the subsequent 13-year period of surgery, when the St. Jude Medical valve was used. Seven of a total of 390 patients (1.8%) required reoperation for prosthetic aortic valve obstruction due to pannus formation. All seven patients were women; four patients underwent resection of the pannus and three patients needed replacement of the valve. The frequency of pannus formation in the early group was 2.4% (6/253), whereas it was 0.73% (1/137) in the late group (P Pannus was localized at the minor orifice of the Björk-Shiley valve in the early group and turbulent transvalvular blood flow was considered to be one of the important factors triggering its growth. We also consider that small bileaflet valves have the possibility of promoting pannus formation and that the implantation of a larger prosthesis can contribute to reducing the occurrence of pannus.

Ball clay

Science.gov (United States)

Virta, R.L.

2001-01-01

Part of the 2000 annual review of the industrial minerals sector. A general overview of the ball clay industry is provided. In 2000, sales of ball clay reached record levels, with sanitary ware and tile applications accounting for the largest sales. Ball clay production, consumption, prices, foreign trade, and industry news are summarized. The outlook for the ball clay industry is also outlined.

Triple leaflet perforation due to endocarditis in aortic valve complicated by pneumonia and exacerbation of chronic obstructive pulmonary disease

Directory of Open Access Journals (Sweden)

Elton Soydan

2015-09-01

Full Text Available Valve perforation complicating infective endocarditis has been for decades a bad sign leading to severe valve destruction, intractable heart failure and even death if surgical therapy is not administered in time. Here we present a 57 years old male patient inadvertently diagnosed with pneumonia and chronic obstructive pulmonary disease exacerbation in another hospital. After 20 days of broad spectrum antibiotics and bronchodilator therapy no improvement was achieved. During examination a severe aortic regurgitation was recognized. Immediately after, patient was transferred to our hospital for aortic valve surgery evaluation. Transthorasic echocardiography (TTE showed a severe aortic regurgitation and vegetation like echogenicity over the noncoronary leaflet. An aortic valve replacement surgical therapy was decided. During the aortic valve excision underneath the vegetations, multiple small perforations in all the three leaflets were noticed. The destructed valve was excised and a mechanical aortic prosthesis (St Jude No: 23, MN, USA was successfully replaced. After 14 days of treatment patient was healthily discharged.

Low pacemaker incidence with continuous-sutured valves: a retrospective analysis.

Science.gov (United States)

Niclauss, Lars; Delay, Dominique; Pfister, Raymond; Colombier, Sebastien; Kirsch, Matthias; Prêtre, René

2017-06-01

Background Permanent pacemaker implantation after surgical aortic valve replacement depends on patient selection and risk factors for conduction disorders. We aimed to identify risk criteria and obtain a selected group comparable to patients assigned to transcatheter aortic valve implantation. Methods Isolated sutured aortic valve replacements in 994 patients treated from 2007 to 2015 were reviewed. Demographics, hospital stay, preexisting conduction disorders, surgical technique, and etiology in patients with and without permanent pacemaker implantation were compared. Reported outcomes after transcatheter aortic valve implantation were compared with those of a subgroup including only degenerative valve disease and first redo. Results The incidence of permanent pacemaker implantation was 2.9%. Longer hospital stay ( p = 0.01), preexisting rhythm disorders ( p pacemaker implantation. Although prostheses were sutured with continuous monofilament in the majority of cases (86%), interrupted pledgetted sutures were used more often in the pacemaker group ( p = 0.002). In the subgroup analysis, the incidence of permanent pacemaker implantation was 2%; preexisting rhythm disorders and the suture technique were still major risk factors. Conclusion Permanent pacemaker implantation depends on etiology, preexisting rhythm disorders, and suture technique, and the 2% incidence compares favorably with the reported 5- to 10-fold higher incidence after transcatheter aortic valve implantation. Cost analysis should take this into account. Often dismissed as minor complication, permanent pacemaker implantation increases the risks of endocarditis, impaired myocardial recovery, and higher mortality if associated with prosthesis regurgitation.

Percutaneous implantation of the CoreValve aortic valve prosthesis in patients at high risk or rejected for surgical valve replacement: Clinical evaluation and feasibility of the procedure in the first 30 patients in the AMC-UvA

NARCIS (Netherlands)

Baan, J.; Yong, Z. Y.; Koch, K. T.; Henriques, J. P. S.; Bouma, B. J.; de Hert, S. G.; van der Meulen, J.; Tijssen, J. G. P.; Piek, J. J.; de Mol, B. A. J. M.

2010-01-01

Objective. To report the feasibility, safety and efficacy of percutaneous aortic valve implantation (PAVI) with the CoreValve self-expanding aortic valve bioprosthesis in elderly patients with aortic valve stenosis who are rejected for surgery or have a high surgical risk.Methods. PAVI using the

Prosthetic valve endocarditis caused by Staphylococcus capitis: report of 4 cases

Directory of Open Access Journals (Sweden)

Wada Yuko

2011-10-01

Full Text Available Abstract Although Staphylococcus capitis is considered to be a rare causative organism for prosthetic valve endocarditis, we report 4 such cases that were encountered at our hospital over the past 2 years. Case 1 was a 79-year-old woman who underwent aortic valve replacement with a bioprosthetic valve and presented with fever 24 days later. Transesophageal echocardiography revealed an annular abscess in the aorto-mitral continuity and mild perivalvular regurgitation. We performed emergency surgery 5 days after the diagnosis of prosthetic valve endocarditis was made. Case 2 was a 79-year-old woman presenting with fever 40 days after aortic valve replacement with a bioprosthesis. Transesophageal echocardiography showed vegetation on the valve, and she underwent urgent surgery 2 days after prosthetic valve endocarditis was diagnosed. In case 3, a 76-year-old man presented with fever 53 days after aortic valve replacement with a bioprosthesis. Vegetation on the prosthetic leaflet could be seen by transesophageal echocardiography. He underwent emergency surgery 2 days after the diagnosis of prosthetic valve endocarditis was made. Case 4 was a 68-year-old woman who collapsed at her home 106 days after aortic and mitral valve replacement with bioprosthetic valves. Percutaneous cardiopulmonary support was started immediately after massive mitral regurgitation due to prosthetic valve detachment was revealed by transesophageal echocardiography. She was transferred to our hospital by helicopter and received surgery immediately on arrival. In all cases, we re-implanted another bioprosthesis after removal of the infected valve and annular debridement. All patients recovered without severe complications after 2 months of antibiotic treatment, and none experienced re-infection during 163 to 630 days of observation. Since the time interval between diagnosis of prosthetic valve endocarditis and valve re-replacement ranged from 0 to 5 days, early surgical removal

The Angelchik prosthesis

International Nuclear Information System (INIS)

Fargnoli, R.; Bozza, A.; Magnoli, A.; Villari, N.; Pernice, L.M.; Andreoli, F.; Lombardi, P.

1989-01-01

The Angelchik prosthesis is used in the surgical treatment of gastroesophageal reflux. Operated patients are preliminary examined with imaging techniques, but manometric and acidometric techniques are also used. Although the conventional esophagogram still maintains its diagnostic significance, Computed Tomography (CT) has become the first-choice imaging modality. CT allows the correct evaluation of both the state of the prosthesis and its relationship to the esophagus and gastric fundus. The possible postoperative complications following an incorrect placement of the prosthesis can be accurately diagnosed too. The authors report their experience in the study of 5 patients examined with both conventional radiology and CT

Left ventricular mass regression after porcine versus bovine aortic valve replacement: a randomized comparison.

Science.gov (United States)

Suri, Rakesh M; Zehr, Kenton J; Sundt, Thoralf M; Dearani, Joseph A; Daly, Richard C; Oh, Jae K; Schaff, Hartzell V

2009-10-01

It is unclear whether small differences in transprosthetic gradient between porcine and bovine biologic aortic valves translate into improved regression of left ventricular (LV) hypertrophy after aortic valve replacement. We investigated transprosthetic gradient, aortic valve orifice area, and LV mass in patients randomized to aortic valve replacement with either the Medtronic Mosaic (MM) porcine or an Edwards Perimount (EP) bovine pericardial bioprosthesis. One hundred fifty-two patients with aortic valve disease were randomly assigned to receive either the MM (n = 76) or an EP prosthesis. There were 89 men (59%), and the mean age was 76 years. Echocardiograms from preoperative, postoperative, predismissal, and 1-year time points were analyzed. Baseline characteristics and preoperative echocardiograms were similar between the two groups. The median implant size was 23 mm for both. There were no early deaths, and 10 patients (7%) died after dismissal. One hundred seven of 137 patients (78%) had a 1-year echocardiogram, and none required aortic valve reoperation. The mean aortic valve gradient at dismissal was 19.4 mm Hg (MM) versus13.5 mm Hg (EP; p regression of LV mass index (MM, -32.4 g/m(2) versus EP, -27.0 g/m(2); p = 0.40). Greater preoperative LV mass index was the sole independent predictor of greater LV mass regression after surgery (p regression of LV mass during the first year after aortic valve replacement.

CAGEd-oPOSSUM: motif enrichment analysis from CAGE-derived TSSs.

Science.gov (United States)

Arenillas, David J; Forrest, Alistair R R; Kawaji, Hideya; Lassmann, Timo; Wasserman, Wyeth W; Mathelier, Anthony

2016-09-15

With the emergence of large-scale Cap Analysis of Gene Expression (CAGE) datasets from individual labs and the FANTOM consortium, one can now analyze the cis-regulatory regions associated with gene transcription at an unprecedented level of refinement. By coupling transcription factor binding site (TFBS) enrichment analysis with CAGE-derived genomic regions, CAGEd-oPOSSUM can identify TFs that act as key regulators of genes involved in specific mammalian cell and tissue types. The webtool allows for the analysis of CAGE-derived transcription start sites (TSSs) either provided by the user or selected from ∼1300 mammalian samples from the FANTOM5 project with pre-computed TFBS predicted with JASPAR TF binding profiles. The tool helps power insights into the regulation of genes through the study of the specific usage of TSSs within specific cell types and/or under specific conditions. The CAGEd-oPOSUM web tool is implemented in Perl, MySQL and Apache and is available at http://cagedop.cmmt.ubc.ca/CAGEd_oPOSSUM CONTACTS: anthony.mathelier@ncmm.uio.no or wyeth@cmmt.ubc.ca Supplementary data are available at Bioinformatics online. © The Author 2016. Published by Oxford University Press.

MANAGEMENT OF FAILED MITRAL VALVE REPLACEMENT. THE DURBAN EXPERIENCE.

Science.gov (United States)

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

Mycobacterium goodii endocarditis following mitral valve ring annuloplasty.

Science.gov (United States)

Parikh, Rohan B; Grant, Matthew

2017-03-21

Mycobacterium goodii is an infrequent human pathogen which has been implicated in prosthesis related infections and penetrating injuries. It is often initially misidentified as a gram-positive rod by clinical microbiologic laboratories and should be considered in the differential diagnosis. We describe here the second reported case of M. goodii endocarditis. Species level identification was performed by 16S rDNA (ribosomal deoxyribonucleic acid) gene sequencing. The patient was successfully treated with mitral valve replacement and a prolonged combination of ciprofloxacin and trimethoprim/sulfamethoxazole. Confirmation of the diagnosis utilizing molecular techniques and drug susceptibility testing allowed for successful treatment of this prosthetic infection.

Successful thrombectomy of a stuck mechanical prosthetic mitral valve guided by perioperative transesophageal echocardiography and cinefluoroscopy

Directory of Open Access Journals (Sweden)

Paulo César Gobert Damasceno Campos

2009-03-01

Full Text Available We describe the case of a 53-year-old man with past history of rheumatic valvular disease who developed acute decompensated heart failure due to thrombosis of his mechanical mitral valve prosthesis. The diagnosis was established after a combined and complementary approach of echocardiography and cinefluoroscopy. Because of the severe heart failure at presentation, the patient was taken to surgery. The intraoperative transesophageal echocardiography was critical to guide a successful thrombectomy procedure. Postoperative pathological findings revealed the presence of thrombus and fibrotic tissue (pannus in the surgical specimens removed from the valve. The success of this case and the treatment choice are supported by the most recent literature data on prosthetic valve thrombosis. We highlight the use of three diagnostic approaches in our patient: echocardiography, cinefluoroscopy and pathology.

The Freedom Solo pericardial stentless valve: Single-center experience, outcomes, and long-term durability.

Science.gov (United States)

Stanger, Olaf; Bleuel, Irina; Gisler, Fabian; Göber, Volkhard; Reineke, Sylvia; Gahl, Brigitta; Aymard, Thierry; Englberger, Lars; Carrel, Thierry; Tevaearai, Hendrik

2015-07-01

To report our institutional experience and long-term results with the Freedom Solo bovine pericardial stentless bioprosthesis (Sorin Group, Saluggia, Italy). Between January 2005 and November 2009, 149 patients (mean age, 73.6 ± 8.7 years; 68 [45.6%] female) underwent isolated (n = 75) or combined (n = 74) aortic valve replacement (AVR) using the Solo in our institution. Follow-up was 100% complete with an average follow-up time of 5.9 ± 2.6 years (maximum, 9.6 years) and a total of 885.3 patient years. Operative (30-day) mortality was 2.7% (1.3% for isolated AVR [n = 1] and 4.0% for combined procedures [n = 3]). All causes of death were not valve-related. Preoperative peak (mean) gradients of 74.2 ± 23.0 mm Hg (48.6 ± 16.3 mm Hg) decreased to 15.6 ± 5.4 mm Hg (8.8 ± 3.0 mm Hg) after AVR, and remained low for up to 9 years. The postoperative effective orifice area was 1.6 ± 0.57 cm(2), 1.90 ± 0.45 cm(2), 2.12 ± 0.48 cm(2), and 2.20 ± 0.66 cm(2) for the valve sizes 21, 23, 25, and 27, respectively, with absence of severe prosthesis-patient mismatch and 0.7% (n = 1) experienced moderate prosthesis-patient mismatch. During follow-up, 26 patients experienced structural valve deterioration (SVD) and 14 patients underwent explantation. Kaplan-Meier estimates for freedom from death, explantation, and SVD at 9 years averaged 0.57 (range, 0.47-0.66), 0.82 (range, 0.69-0.90), and 0.70 (range, 0.57-0.79), respectively. The Freedom Solo stentless aortic valve is safe to implant and shows excellent early and midterm hemodynamic performance. However, SVD was observed in a substantial number of patients after only 5-6 years and the need for explantation increased markedly, suggesting low durability. Copyright © 2015 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.

Noninvasive radioisotopic technique for detection of platelet deposition in mitral valve prosthesis and renal microembolism in dogs

International Nuclear Information System (INIS)

Dewanjee, M.K.; Kaye, M.P.; Fuster, V.; Rao, S.A.

1980-01-01

At 24 hrs after implantation of Bjoerk-Shiley mitral prosthesis in 5 dogs, in vivo images were obtained with a gamma camera after intravenous administration (0.5-0.6 mCi) one hour postoperatively of autologous Indium-111-labeled platelets. The site of platelet deposition in the teflon ring and perivascular damaged cardiac tissue is clearly delineated in the scintiphoto. In vitro biodistribution (mean % +/- SD of injected dose) at 24 hrs after injection of the 5 implanted and 7 normal dogs performed with a gamma counter demonstrated that (45.1 +/- 10.6)% and (0.7 +/- 0.4)% were in blood and kidneys in normal dogs and (28.5 +/- 6.8)%, (1.6 +/- 0.6)%, (0.3 +/- 0.1)%, and (0.2 +/- 0.1)% were in blood, kidneys, teflon rings, and perivascular damaged cardiac tissue, respectively. The strut and pyrolytic carbon-coated disc retained only (0.0033 +/- 0.0004)% and (0.0031 +/- 0.0003)%, respectively. There was a 2.3-fold increase of labeled platelets in kidneys of implanted dogs due to renal trapping of microembolism. Also, three- to fivefold increase in ratios of lung, brain, cardiac, and skeletal muscle to blood indicates that internal organs and whole body work as filter for microembolism generated by cardiovascular surgery and mitral prosthesis. Twenty percent of the administered platelets are consumed in surgical repair of damaged tissue. Indium-111-labeled platelets thus provide a sensitive marker for noninvasive imaging of Bjoerk-Shiley mitral prosthesis, thromboembolism after implantation of prosthetic device, and in vitro quantitation of surgical consumption

Intraoperative echocardiography of a dislodged Björk-Shiley mitral valve disc.

Science.gov (United States)

Tanaka, M; Abe, T; Takeuchi, E; Watanabe, T; Tamaki, S

1991-02-01

The successful management of a patient who suffered an outlet strut fracture of a Björk-Shiley 60-degree convexo-concave mitral valve prosthesis is reported. Emergency operation was life-saving. Preoperative echocardiography assisted in making a prompt diagnosis, and intraoperative echocardiography allowed the detection and removal of the dislodged disc from the left ventricle at the time of the operation. The role of intraoperative echocardiography in the diagnosis of prosthetic strut fracture is emphasized.

Disc dislodgment in Björk Shiley mitral valve prosthesis: two successfully operated cases.

Science.gov (United States)

Dubernet, J; Irarrázaval, M J; Urzúa, J; Maturana, G; Morán, S; Lema, G; Asenjo, F; Fajuri, A

1986-02-01

Two patients with Björk Shiley mitral valve replacement had migration and embolization of the occluding disc. One patient suffered migration of the disc a few hours after surgery and the other had a strut fracture with disc translocation six years after the initial operation. Clinical signs in both cases were pulmonary edema, cardiogenic shock, and absence of prosthetic sounds. Both patients were reoperated on an emergency basis, recovering after a complicated postoperative course. They are on functional Class I, 8 and 1 years later, respectively, with their dislodged discs still in the abdominal aorta. The only hope for survival in these patients is emergency reoperation, once the prosthetic mitral valve dysfunction is confirmed.

Long-term tricuspid valve prosthesis-related complications in patients with congenital heart disease

NARCIS (Netherlands)

van Slooten, Ymkje J.; Freling, Hendrik G.; van Melle, Joost P.; Mulder, Barbara J. M.; Jongbloed, Monique R. M.; Ebels, Tjark; Voors, Adriaan A.; Pieper, Petronella G.

2014-01-01

In patients with acquired valvar disease, morbidity and mortality rates after tricuspid valve replacement (TVR) are high. However, in adult patients with congenital heart disease, though data concerning outcome after TVR are scarce, even poorer results are suggested in patients with Ebstein anomaly.

Long-term tricuspid valve prosthesis-related complications in patients with congenital heart disease

NARCIS (Netherlands)

van Slooten, Ymkje J.; Freling, Hendrik G.; van Melle, Joost P.; Mulder, Barbara J. M.; Jongbloed, Monique R. M.; Ebels, Tjark; Voors, Adriaan A.; Pieper, Petronella G.

OBJECTIVES: In patients with acquired valvar disease, morbidity and mortality rates after tricuspid valve replacement (TVR) are high. However, in adult patients with congenital heart disease, though data concerning outcome after TVR are scarce, even poorer results are suggested in patients with

Ventricular Pacing via the Coronary Sinus in a Patient with a Mechanical Tricuspid Valve Prosthesis

Directory of Open Access Journals (Sweden)

Janice Swampillai, MD

2011-01-01

Full Text Available Implantation of a transvenous endocardial pacing lead in the right ventricle is contra-indicated after mechanical tricuspid valve replacement; therefore a surgical approach to the epicardium is usually required. This case report describes ventricular pacing via a branch of the coronary sinus in a patient with mechanical mitral, aortic and tricuspid valve replacements. In conclusion, this approach is minimally invasive, provides effective ventricular stimulation with low pacing threshold and stable lead position, and is a feasible option when transvenous right ventricular pacing is not possible.

Surgical treatment of aortic valve endocarditis: a 26-year experience

Directory of Open Access Journals (Sweden)

Taylan Adademir

2014-03-01

Full Text Available Objective: We have retrospectively analyzed the results of the operations made for aortic valve endocarditis in a single center in 26 years. Methods: From June 1985 to January 2011, 174 patients were operated for aortic valve endocarditis. One hundred and thirty-eight (79.3% patients were male and the mean age was 39.3±14.4 (9-77 years. Twenty-seven (15.5% patients had prosthetic valve endocarditis. The mean duration of follow-up was 7.3±4.2 years (0.1-18.2 adding up to a total of 1030.8 patient/years. Results: Two hundred and eighty-two procedures were performed. The most frequently performed procedure was aortic valve replacement with mechanical prosthesis (81.6%. In-hospital mortality occurred in 27 (15.5% cases. Postoperatively, 25 (14.4% patients had low cardiac output and 17 (9.8% heart block. The actuarial survival rates for 10 and 15 years were 74.6±3.7% and 61.1±10.3%, respectively. In-hospital mortality was found to be associated with female gender, emergency operation, postoperative renal failure and low cardiac output. The long term mortality was significantly associated with mitral valve involvement. Male gender was found to be a significant risk factor for recurrence in the follow-up. Conclusion: Surgery for aortic valve endocarditis has significant mortality. Emergency operation, female gender, postoperative renal failure and low cardiac output are significant risk factors. Risk for recurrence and need for reoperation is low.

Aortic valve replacement in a patient with severe nickel allergy.

Science.gov (United States)

Lusini, Mario; Barbato, Raffaele; Spadaccio, Cristiano; Chello, Massimo

2011-11-01

Nickel allergy can raise clinical problems in patients undergoing cardiac surgery who require sternal closure with stainless steel wire. We describe the case of a 51-year-old woman with severe nickel allergy who underwent aortic valve replacement with a nickel-free ON-X prosthesis and sternal closure by Fiberwire # 2 suture without complications. Considering its biocompatibility and its mechanical characteristics including optimal strength and knot resistance, this suture might be a viable alternative in patients in which the use of stainless steel wire is contraindicated. © 2011 Wiley Periodicals, Inc.

[Campylobacter fetus subspecies fetus endoaortitis on a Bentall tube prosthesis. Apropos of a case].

Science.gov (United States)

Abassade, P; Crémieux, O; Korach, J M; Templier, F; Morette, C; Wolff, M; Baudouy, P Y; Farge, C

1994-11-01

Campylobacter fetus is a rare cause of endocarditis and endoaortitis: the authors believe this to be the second reported case of infection of an intracardiac prosthesis. The patient was a man who had already undergone replacement of the aortic valve and ascending aorta, and a gastrectomy, which were predisposing factors. The portal of entry was not found. The diagnosis was confirmed by positive blood cultures and transoesophageal echocardiography. The outcome was rapidly fatal despite antibiotic therapy and surgery, because of the seriousness of the lesions (pseudo-aneurysm of the aorta ruptured into the right atrium), the precarity of the terrain and surgical difficulties.

Ball Nut Preload Diagnosis of the Hollow Ball Screw through Support Vector Machine

Directory of Open Access Journals (Sweden)

Yi-Cheng Huang

2018-01-01

Full Text Available This paper studies the diagnostic results of hollow ball screws with different ball nut preload through the support vector machine (SVM process. The method is testified by considering the use of ball screw pretension and different ball nut preload. SVM was used to discriminate the hollow ball screw preload status through the vibration signals and servo motor current signals. Maximum dynamic preloads of 2%, 4%, and 6% ball screws were predesigned, manufactured, and conducted experimentally. Signal patterns with different preload features are separatedby SVM. The irregularity development of the ball screw driving motion current and rolling balls vibration of the ball screw can be discriminated via SVM based on complexity perception. The experimental results successfully show that the prognostic status of ball nut preload can be envisaged by the proposed methodology. The smart reasoning for the health of the ball screw is available based on classification of SVM. This diagnostic method satisfies the purposes of prognostic effectiveness on knowing the ball nut preload status

Valve-sparing aortic root replacement in Marfan syndrome.

Science.gov (United States)

Cameron, Duke E; Vricella, Luca A

2005-01-01

Marfan syndrome is the most common inherited connective tissue disorder, affecting approximately 1 in 10,000 live births. The cardinal features of Marfan syndrome are the abnormalities of the skeleton (tall stature, arachnodactyly, and joint hyperelasticity), eye (lens subluxation), and aorta (root aneurysm with proclivity toward rupture and dissection). Aortic catastrophe accounts for most of the premature mortality among Marfan patients, a risk that climbs steeply during adolescence and results in death of half of Marfan patients by the age of 40 years. Most of the improvement in life expectancy that has been achieved in Marfan syndrome is attributable to early recognition of aortic root aneurysms and prophylactic replacement with composite grafts (mechanical valve prostheses within Dacron conduits) before rupture or dissection occurs. Despite the excellent early and late results with composite grafts, there has been growing interest in operative procedures that replace the sinuses but preserve the aortic valve leaflets, to avoid anticoagulation and minimize the risk of prosthesis-related endocarditis. These procedures are still in evolution and late results are not yet known, but as with mitral repair in the setting of myxomatous disease, valve-sparing procedures in Marfan syndrome have weathered a storm of initial criticism and skepticism and are steadily gaining acceptance.

Having a Ball with Fitness Balls

Science.gov (United States)

McNulty, Betty

2011-01-01

Fitness programs can be greatly enhanced with the addition of fitness balls. They are a fun, challenging, economical, and safe way to incorporate a cardiovascular, strength, and stretching program for all fitness levels in a physical education setting. The use of these balls has become more popular during the last decade, and their benefits and…

The challenge of pelvic discontinuity: cup-cage reconstruction does better than conventional cages in mid-term.

Science.gov (United States)

Abolghasemian, M; Tangsaraporn, S; Drexler, M; Barbuto, R; Backstein, D; Safir, O; Kuzyk, P; Gross, A

2014-02-01

The use of ilioischial cage reconstruction for pelvic discontinuity has been replaced by the Trabecular Metal (Zimmer, Warsaw, Indiana) cup-cage technique in our institution, due to the unsatisfactory outcome of using a cage alone in this situation. We report the outcome of 26 pelvic discontinuities in 24 patients (20 women and four men, mean age 65 years (44 to 84)) treated by the cup-cage technique at a mean follow-up of 82 months (12 to 113) and compared them with a series of 19 pelvic discontinuities in 19 patients (18 women and one man, mean age 70 years (42 to 86)) treated with a cage at a mean follow-up of 69 months (1 to 170). The clinical and radiological outcomes as well as the survivorship of the groups were compared. In all, four of the cup-cage group (15%) and 13 (68%) of the cage group failed due to septic or aseptic loosening. The seven-year survivorship was 87.2% (95% confidence interval (CI) 71 to 103) for the cup-cage group and 49.9% (95% CI 15 to 84) for the cage-alone group (p = 0.009). There were four major complications in the cup-cage group and nine in the cage group. Radiological union of the discontinuity was found in all successful cases in the cup-cage group and three of the successful cage cases. Three hips in the cup-cage group developed early radiological migration of the components, which stabilised with a successful outcome. Cup-cage reconstruction is a reliable technique for treating pelvic discontinuity in mid-term follow-up and is preferred to ilioischial cage reconstruction. If the continuity of the bone graft at the discontinuity site is not disrupted, early migration of the components does not necessarily result in failure.

19 mm sized bileaflet valve prostheses' flow field investigated by bidimensional laser Doppler anemometry (part I: velocity profiles).

Science.gov (United States)

Barbaro, V; Grigioni, M; Daniele, C; D'Avenio, G; Boccanera, G

1997-11-01

The investigation of the flow field downstream of a cardiac valve prosthesis is a well established task. In particular turbulence generation is of interest if damage to blood constituents is to be assessed. Several prosthetic valve flow studies are available in literature but they generally concern large-sized prostheses. The FDA draft guidance requires the study of the maximum Reynolds number conditions for a cardiac valve model to assess the worst case in turbulence by choosing both the minimum valve diameter and a high cardiac output value as protocol set up. Within the framework of a national research project regarding the characterization of cardiovascular endoprostheses, the Laboratory of Biomedical Engineering is currently conducting an in-depth study of turbulence generated downstream of bileaflet cardiac valves. Four models of 19 mm sized bileaflet valve prostheses, namely St Jude Medical HP Edwards Tekna, Sorin Bicarbon, and CarboMedics, were studied in aortic position. The prostheses were selected for the nominal annulus diameter reported by the manufacturers without any assessment of the valve sizing method. The hemodynamic function was investigated using a bidimensional LDA system. Results concern velocity profiles during the peak flow systolic phase, at high cardiac output regime, highlighting the different flow field features downstream of the four small-sized cardiac valves.

Direct transcatheter aortic valve implantation with self-expandable bioprosthesis: Feasibility and safety

Energy Technology Data Exchange (ETDEWEB)

Fiorina, Claudia, E-mail: clafiorina@yahoo.it [Cardiac Catheterization Laboratory, Cardiothoracic Department, Spedali Civili, Brescia (Italy); Maffeo, Diego; Curello, Salvatore [Cardiac Catheterization Laboratory, Cardiothoracic Department, Spedali Civili, Brescia (Italy); Lipartiti, Felicia [Division of Cardiology, Cardiothoracic Department, Spedali Civili, Brescia (Italy); Chizzola, Giuliano [Cardiac Catheterization Laboratory, Cardiothoracic Department, Spedali Civili, Brescia (Italy); D' Aloia, Antonio [Division of Cardiology, Cardiothoracic Department, Spedali Civili, Brescia (Italy); Adamo, Marianna [Cardiac Catheterization Laboratory, Cardiothoracic Department, Spedali Civili, Brescia (Italy); Mastropierro, Rosy [Division of Cardiothoracic Anestesiology, Cardiothoracic Department, Spedali Civili, Brescia (Italy); Gavazzi, Emanuele [Department of Radiology, University of Brescia, Spedali Civili, Brescia (Italy); Ciccarese, Camilla; Chiari, Ermanna [Division of Cardiology, Cardiothoracic Department, Spedali Civili, Brescia (Italy); Ettori, Federica [Cardiac Catheterization Laboratory, Cardiothoracic Department, Spedali Civili, Brescia (Italy)

2014-06-15

Background: Balloon valvuloplasty has been considered a mandatory step of the transcatheter aortic valve implantation (TAVI), although it is not without risk. The aim of this work was to evaluate the feasibility and safety of TAVI performed without pre-dilation (direct TAVI) of the stenosed aortic valve. Material and Methods: Between June 2012 and June 2013, 55 consecutive TAVI performed without pre-dilation at our institution using the self-expandable CoreValve prosthesis (Medtronic, Minneapolis, MN) were analyzed and compared with 45 pre-dilated TAVI performed the previous year. Inclusion criteria were a symptomatic and severe aortic stenosis. Exclusion criteria were defined as presence of pure aortic regurgitation, degenerated surgical bioprosthesis or bicuspid aortic valve and prior procedure of balloon aortic valvuloplasty performed as a bridge to TAVI. Results: High-burden calcification in the device landing zone, assessed by CT scan, was found in most of the patients. The valve size implanted was similar in both groups. Device success was higher in direct TAVI (85% vs. 64%, p = 0.014), mostly driven by a significant lower incidence of paravalvular leak (PVL ≥2; 9% vs. 33%, p = 0.02). Safety combined end point at 30 days was similar in both groups. Conclusion: Compared to TAVI with pre-dilation, direct TAVI is feasible regardless of the presence of bulky calcified aortic valve and the valve size implanted. Device success was higher in direct TAVI, mostly driven by a lower incidence of paravalvular leak. Safety at 30 days was similar in two groups.

Long-term results of heart valve replacement with the Edwards Duromedics bileaflet prosthesis: a prospective ten-year clinical follow-up.

Science.gov (United States)

Podesser, B K; Khuenl-Brady, G; Eigenbauer, E; Roedler, S; Schmiedberger, A; Wolner, E; Moritz, A

1998-05-01

The Edwards Duromedics valve (Baxter Healthcare Corp., Edwards Division, Santa Ana, Calif.) was designed with a self-irrigating hinge mechanism to reduce thromboembolic complications. After good initial clinical results, distribution was suspended in 1988 after reports of valve fracture after 20,000 valves had been implanted. The manufacturer conducted extensive studies to improve the Edwards Duromedics and reintroduced a modified version, which is available as Edwards Tekna. The purpose of the study was the evaluation of long-term results of the original Edwards Duromedics that might be important for the current version, the Edwards Tekna valve. A prospective clinical 10-year follow-up was performed of 508 patients who underwent valve replacement with the Edwards Duromedics valve in the aortic (n = 268), mitral (n = 183), and aortic and mitral (n = 56) position. The perioperative mortality rate was 6.9%; follow-up was 98% complete, comprising 3648 patient-years for a mean follow-up of 86 months (range: 33 to 144 months). The actuarial freedom from complications at the 10-year follow-up and the incidence rate (percent per patient-year) were as follows: late mortality rate, 69.2% +/- 2.4% (3.5% per patient-year); thromboembolism, 90.7% +/- 1.6% (0.96% per patient-year); anticoagulation-related hemorrhage, 87.7% +/- 1.7% (1.34% per patient-year); prosthetic valve endocarditis, 96.7% +/- 0.09% (0.38% per patient-year); valve-related mortality rate, 89.3% +/- 1.6% (1.21% per patient-year); valve failure, 86.2% +/- 1.85% (1.54% per patient-year); and valve-related morbidity and mortality rate, 71.1% +/- 2.3% (3.2% per patient-year). Three leaflet escapes were observed (one lethal, two successful reoperations; 99.1% +/- 0.05% freedom, 0.08% per patient-year). All patients functionally improved (86% in New York Heart Association classes I and II), and incidence of anemia was insignificant. These results confirm that the Edwards Duromedics valve shows excellent performance

Nuclear Medicine in Diagnosis of Prosthetic Valve Endocarditis: An Update

Science.gov (United States)

Musso, Maria; Petrosillo, Nicola

2015-01-01

Over the past decades cardiovascular disease management has been substantially improved by the increasing introduction of medical devices as prosthetic valves. The yearly rate of infective endocarditis (IE) in patient with a prosthetic valve is approximately 3 cases per 1,000 patients. The fatality rate of prosthetic valve endocarditis (PVE) remains stable over the years, in part due to the aging of the population. The diagnostic value of echocardiography in diagnosis is operator-dependent and its sensitivity can decrease in presence of intracardiac devices and valvular prosthesis. The modified Duke criteria are considered the gold standard for diagnosing IE; their sensibility is 80%, but in clinical practice their diagnostic accuracy in PVE is lower, resulting inconclusively in nearly 30% of cases. In the last years, these new imaging modalities have gained an increasing attention because they make it possible to diagnose an IE earlier than the structural alterations occurring. Several studies have been conducted in order to assess the diagnostic accuracy of various nuclear medicine techniques in diagnosis of PVE. We performed a review of the literature to assess the available evidence on the role of nuclear medicine techniques in the diagnosis of PVE. PMID:25695043

Influence of the tilt angle of Percutaneous Aortic Prosthesis on Velocity and Shear Stress Fields

Directory of Open Access Journals (Sweden)

Bruno Alvares de Azevedo Gomes

Full Text Available Abstract Background: Due to the nature of the percutaneous prosthesis deployment process, a variation in its final position is expected. Prosthetic valve placement will define the spatial location of its effective orifice in relation to the aortic annulus. The blood flow pattern in the ascending aorta is related to the aortic remodeling process, and depends on the spatial location of the effective orifice. The hemodynamic effect of small variations in the angle of inclination of the effective orifice has not been studied in detail. Objective: To implement an in vitro simulation to characterize the hydrodynamic blood flow pattern associated with small variations in the effective orifice inclination. Methods: A three-dimensional aortic phantom was constructed, reproducing the anatomy of one patient submitted to percutaneous aortic valve implantation. Flow analysis was performed by use of the Particle Image Velocimetry technique. The flow pattern in the ascending aorta was characterized for six flow rate levels. In addition, six angles of inclination of the effective orifice were assessed. Results: The effective orifice at the -4° and -2° angles directed the main flow towards the anterior wall of the aortic model, inducing asymmetric and high shear stress in that region. However, the effective orifice at the +3° and +5° angles mimics the physiological pattern, centralizing the main flow and promoting a symmetric distribution of shear stress. Conclusion: The measurements performed suggest that small changes in the angle of inclination of the percutaneous prosthesis aid in the generation of a physiological hemodynamic pattern, and can contribute to reduce aortic remodeling.

The Ross procedure offers excellent survival compared with mechanical aortic valve replacement in a real-world setting.

Science.gov (United States)

Andreas, Martin; Wiedemann, Dominik; Seebacher, Gernot; Rath, Claus; Aref, Tandis; Rosenhek, Raphael; Heinze, Georg; Eigenbauer, Ernst; Simon, Paul; Ruetzler, Kurt; Hiesmayr, Joerg-Michael; Moritz, Anton; Laufer, Guenther; Kocher, Alfred

2014-09-01

The ideal prosthesis for young patients requiring aortic valve replacement has not been defined to date. Although the Ross procedure provides excellent survival, its application is still limited. We compared the long-term survival after the Ross procedure with mechanical aortic valve replacement. All consecutive Ross procedures and mechanical aortic valve replacements performed between 1991 and 2008 at a single centre were analysed. Only adult patients between 18 and 50 years of age were included in the study. Survival and valve-related complications were evaluated. Furthermore, survival was compared with the age- and sex-matched Austrian population. A total of 159 Ross patients and 173 mechanical valve patients were included. The cumulative survival for the Ross procedure was significantly better, with survival rates of 96, 94 and 93% at 5, 10 and 15 years, respectively, in comparison to 90, 84 and 75% (P Ross group but was significantly reduced in the mechanical valve group. In a real-world setting, the Ross procedure is associated with a long-term survival benefit in young adults in comparison to mechanical aortic valve replacement. © The Author 2014. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

Thrombocytopenia after aortic valve replacement with freedom solo bioprosthesis: a propensity study.

Science.gov (United States)

Piccardo, Alessandro; Rusinaru, Dan; Petitprez, Benoit; Marticho, Paul; Vaida, Ioana; Tribouilloy, Christophe; Caus, Thierry

2010-05-01

The incidence of postoperative thrombocytopenia after aortic valve replacement with the Freedom Solo bioprosthesis remains unclear. This propensity-matched study was carried out to evaluate the incidence and clinical impact of thrombocytopenia in patients receiving the Freedom Solo bioprosthesis. Patients who underwent aortic valve replacement with a Freedom Solo or Carpentier-Edwards Perimount pericardial prosthesis at our institution between 2006 and 2008 were screened retrospectively. Exclusion criteria included double valve replacement, redo surgery, and active endocarditis. Two hundred six patients were considered eligible for this analysis. Using propensity scores 36 matched pairs of patients with a Freedom Solo or Perimount bioprosthesis were obtained. The primary end point was the occurrence of postoperative thrombocytopenia. Secondary end points were postoperative thromboembolic or hemorrhagic events and 30-day mortality. Before matching, severe thrombocytopenia (Solo bioprosthesis and 1% with a Perimount bioprosthesis (p Solo (p Solo and Perimount bioprostheses, respectively (p Solo implantation. However, this complication was not related to any deleterious events in our study population. Copyright (c) 2010 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

Polyetheretherketone (PEEK) intervertebral cage as a cause of chronic systemic allergy: a case report.

Science.gov (United States)

Maldonado-Naranjo, Andres L; Healy, Andrew T; Kalfas, Iain H

2015-07-01

Polyetheretherketone (PEEK) is an organic polymer thermoplastic with strong mechanical and chemical resistance properties. It has been used in industry to fabricate items for demanding applications such as bearings, piston parts, compressor plate valves, and cable insulation. Since the early 1980s, polyetheretherketone polymers have been increasingly used in orthopedic and spinal surgery applications. Numerous studies and years of clinical experience have confirmed the biocompatibility of this material. The purpose of the study was to report a case of chronic systemic allergy after anterior cervical decompression and fusion (ACDF) and implantation of an intervertebral PEEK cage, with resolution of symptoms after removal of PEEK cage. This study is a case report with clinical evidence for allergy to PEEK. The methods involve clinical findings and review of current literature. After ACDF and implantation of an intervertebral PEEK cage, the patient had developed an angioedema-like picture marked by severe redness, itching, swelling of his tongue, and skin thickening. A skin patch test was positive for PEEK. Removal of the implant resulted in the resolution of his allergy symptoms shortly after surgery. Tissue reactions to PEEK are extremely rare. Herein, we present the first report of a chronic allergic response to interbody PEEK material. Copyright © 2015 Elsevier Inc. All rights reserved.

One-year multicentre outcomes of transapical aortic valve implantation using the SAPIEN XT™ valve: the PREVAIL transapical study.

Science.gov (United States)

Walther, Thomas; Thielmann, Matthias; Kempfert, Joerg; Schroefel, Holger; Wimmer-Greinecker, Gerhard; Treede, Hendrik; Wahlers, Thorsten; Wendler, Olaf

2013-05-01

The study aimed to evaluate 1-year outcomes of the multicentre PREVAIL transapical (TA) study of TA-aortic valve implantation (AVI) in high-risk patients. From September 2009 to August 2010, a total of 150 patients, aged 81.6 ± 5.8 years, 40.7% female, were included at 12 European TA-AVI experienced sites. Patients received 23 (n = 36), 26 (n = 57) and 29 mm (n = 57) second-generation SAPIEN XT™ (Edwards Lifesciences, Irvine, CA, USA) valves. The mean logistic EuroSCORE was 24.3 ± 7.0, and mean Society Thoracic Surgeons score was 7.5 ± 4.4%. Survival was 91.3% at 30 days and 77.9% at 1 year. Subgroup analysis revealed survivals of 91.7/88.9, 86.0/70.2, 96.55/91.2% for patients receiving 23-, 26- and 29-mm valves at 30 days and at 1 year, respectively. Transthoracic echocardiography revealed preserved left ventricular ejection fraction and low gradients. Aortic incompetence was none in 41/48, trace 30/36, mild 22/12 and moderate in 7/4% at discharge and 1 year. Walking distance increased from 221 (postimplant) to 284 m (at 1 year, P = 0.0004). Three patients required reoperation due to increasing aortic incompetence during follow-up. Causes of mortality at 1 year were cardiac (n = 7), stroke (n = 1) and others (n = 5). The European PREVAIL multicentre trial demonstrates good functionality and good outcomes for TA-AVI using the second-generation SAPIEN XT prosthesis and the ASCENDRA-II delivery system. The 29-mm SAPIEN XT valve was successfully introduced and showed excellent results.

Coronary Emboli in a Young Patient with Mechanical Aortic Valve: A Rare Cause of Acute Myocardial Infarction

Directory of Open Access Journals (Sweden)

Arash Gholoobi

2016-03-01

Full Text Available Coronary artery embolism is an uncommon cause of Acute Myocardial Infarction (AMI. Herein, we reported a 24-year-old male who was admitted with acute infero-posterior myocardial infarction and cerebral Transient Ischemic Attack (TIA. He had undergone mechanical Aortic Valve Replacement (AVR surgery 6 years ago. Surprisingly, the patient had decided to stop taking his medication (warfarin 20 days earlier without any medical advice. Coronary angiography revealed a thrombus located at the distal part of the left circumflex artery. Discontinuation of anticoagulant therapy in the presence of mechanical valve prosthesis, clinical evidence of coincidental TIA, and lack of atherosclerotic risk factors were highly suggestive of coronary thromboembolism as the cause of AMI. Overall, this case report emphasized the necessity of continuous education in patients with mechanical heart valves to prevent such undesired events.

Reimplantation valve-sparing aortic root replacement with the Valsalva graft: what have we learnt after 100 cases?

Science.gov (United States)

Settepani, Fabrizio; Bergonzini, Marcello; Barbone, Alessandro; Citterio, Enrico; Basciu, Alessio; Ornaghi, Diego; Gallotti, Roberto; Tarelli, Giuseppe

2009-07-01

Reimplantation valve-sparing aortic root replacement has been increasingly performed with improving perioperative and mid-term results. The success of this operation primarily depends on preserving the highly sophisticated dynamic function of the aortic valve by recreating an anatomical three-dimensional configuration similar to the normal aortic root, thus minimizing the mechanical stress and strain on the cusps. Over the years several techniques have been proposed to reproduce the sinuses of Valsalva. We reviewed our experience with aortic valve reimplantation by means of a modified Dacron graft that incorporates sinuses of Valsalva, in a series of 100 consecutive patients. During a 60-month period, 100 patients with aortic root aneurysm underwent aortic valve reimplantation using the Gelweave Valsalva prosthesis. There were 74 males and the mean age was 60+/-12 years (range 28-83 years). Five patients had the Marfan's syndrome, 15 had a bicuspid aortic valve. Cusp repair was performed in five patients. The mean follow-up time was 28.6 months (range 1-60). Transesophageal echocardiogram was performed at the end of each procedure to assess the aortic valve in terms of competence, dynamic motion and level of coaptation within the graft. There was one hospital death and two late deaths. Overall survival at 60 months was 91.7+/-5.1%. Five patients developed severe aortic incompetence (AI) during follow-up requiring aortic valve replacement (AVR). The 60 months freedom from re-operation due to AI was 90.9+/-4.4%. One patient had moderate AI at latest echocardiographic study. The 60 months freedom from AI>2+ was 91.6+/-7.9%. Cox regression identified cusp's repair as independent risk factor (P=0.001) for late reimplantation failure (AVR or AI>2+). There were no episodes of endocarditis and the majority of the patients (88%) were in New York Heart Association functional class I. The aortic valve reimplantation with the Gelweave Valsalva prosthesis provided satisfactory

Nasal prosthesis rehabilitation: a case report

DEFF Research Database (Denmark)

Jain, Sumeet; Maru, Kavita; Shukla, Jyotsana

2011-01-01

Facial defects resulting from neoplasm, congenital malformation or trauma can be restored with facial prosthesis using different materials and retention methods to achieve life-like look and function. A nasal prosthesis can re-establish esthetic form and anatomic contours for mid-facial defects...... the non-surgical rehabilitation, with polymethyl meth-acrylate resin, nasal prosthesis for a patient who received partial rhinectomy as a result of squamous cell carcinoma of the nose. The prosthesis was made to restore the esthetic appearance of the patient with a mechanical retained design using...

[Revision hip arthroplasty by Waldemar Link custom-made total hip prosthesis].

Science.gov (United States)

Medenica, Ivica; Luković, Milan; Radoicić, Dragan

2010-02-01

The number of patients undergoing hip arthroplasty revision is constantly growing. Especially, complex problem is extensive loss of bone stock and pelvic discontinuity that requires reconstruction. The paper presented a 50-year old patient, who ten years ago underwent a total cement artrhroplasty of the left hip. A year after the primary operation the patient had difficulties in walking without crutches. Problems intensified in the last five years, the patient had severe pain, totally limited movement in the left hip and could not walk at all. Radiographically, we found loose femoral component, massive loss of bone stock of proximal femur, acetabular protrusion and a consequent pelvic discontinuity. Clinically, a completely disfunctional left hip joint was registered (Harris hip score--7.1). We performed total rearthroplasty by a custom-made Waldemar Link total hip prosthesis with acetabular antiprotrusio cage and compensation of bone defects with a graft from the bone bank. A year after the operation, we found clinically an extreme improvement in Harris hip score--87.8. Radiographically, we found stability of implanted components, a complete graft integration and bone bridging across the site of pelvic discontinuity. Pelvic discontinuity and massive loss of proximal femoral bone stock is a challenging and complex entity. Conventional prostheses cannot provide an adequate fixation and stability of the hip. Application of custom-made prosthesis (measured specificaly for a patient) and additional alografting bone defects is a good method in revision surgery after unsuccessful hip arthroplasty with extensive bone defects.

Rescue Implantation of Expandable Cages for Severe Osteolysis and Cage Dislocation in the Lumbosacral Junction.

Science.gov (United States)

Schatlo, Bawarjan; Rohde, Veit; Solomiichuk, Volodymyr; von Eckardstein, Kajetan; Behm, Timo

2017-11-01

Osteolysis and implant loosening are commonly encountered problems after spinal instrumentation. In a patient who had previously undergone a posterior lumbar interbody fusion procedure, fusion did not occur, and a secondary cage dislocation led to an impingement of the L5 nerve root with severe radiculopathy. Revision surgery was performed. Intraoperatively, osteolysis was found to be so severe that conventional cages did not fill the void to allow for sufficient anterior column support. We used expandable transforaminal lumbar interbody fusion cages and implanted them bilaterally to replace the dislodged posterior lumbar interbody fusion cages. Clinical follow-up was uneventful. Imaging performed at 1 year showed satisfactory cage position and fusion. We propose the use of cages with the ability of ventral distraction in similar rescue interventions with cage dislocation and bone resorption. This may prevent a second surgery via a ventral approach. Copyright © 2017 Elsevier Inc. All rights reserved.

The incredible shrinking ball

Energy Technology Data Exchange (ETDEWEB)

Smith, Maurice

2011-12-15

In the oil and gas industry, the implementation of fracture systems using ball and seat technology helped make multistage fracturing possible. However, frac balls can obstruct later production flow by staying in the well. Baker Hughes Inc. developed a technology to solve this problem: IN-Tallic frac balls. The unique feature of these frac balls is that they are made of an electrolytic metallic nanostructured material which is light and strong and which melts away with salt water or brine through a decomposition process governed by electrochemical reactions controlled by nanoscale coatings. These balls need to be kept away from moisture in order to prevent degradation. This technology is more expensive than traditional frac balls but it prevents the need to mill out obstructions created by the balls. The IN-Tallic frac balls are a new technology which provides operators with peace of mind.

Non-cardiac surgery in patients with prosthetic heart valves: a 12 years experience.

Science.gov (United States)

Akhtar, Raja Parvez; Abid, Abdul Rehman; Zafar, Hasnain; Gardezi, Syed Javed Raza; Waheed, Abdul; Khan, Jawad Sajid

2007-10-01

To study patients with mechanical heart valves undergoing non-cardiac surgery and their anticoagulation management during these procedures. It was a cohort study. The study was conducted at the Department of Cardiac Surgery, Punjab Institute of Cardiology, Lahore and Department of Surgery, Services Institute of Medical Sciences, Lahore, from September 1994 to June 2006. Patients with mechanical heart valves undergoing non-cardiac surgical operation during this period, were included. Their anticoagulation was monitored and anticoagulation related complications were recorded. In this study, 507 consecutive patients with a mechanical heart valve replacement were followed-up. Forty two (8.28%) patients underwent non-cardiac surgical operations of which 24 (57.1%) were for abdominal and non-abdominal surgeries, 5 (20.8%) were emergency and 19 (79.2%) were planned. There were 18 (42.9%) caesarean sections for pregnancies. Among the 24 procedures, there were 7(29.1%) laparotomies, 7(29.1%) hernia repairs, 2 (8.3%) cholecystectomies, 2 (8.3%) hysterectomies, 1(4.1%) craniotomy, 1(4.1%) spinal surgery for neuroblastoma, 1(4.1%) ankle fracture and 1(4.1%) carbuncle. No untoward valve or anticoagulation related complication was seen during this period. Patients with mechanical valve prosthesis on life-long anticoagulation, if managed properly, can undergo any type of non-cardiac surgical operation with minimal risk.

PREVAIL TRANSAPICAL: multicentre trial of transcatheter aortic valve implantation using the newly designed bioprosthesis (SAPIEN-XT) and delivery system (ASCENDRA-II).

Science.gov (United States)

Walther, Thomas; Thielmann, Matthias; Kempfert, Joerg; Schroefel, Holger; Wimmer-Greinecker, Gerhard; Treede, Hendrik; Wahlers, Thorsten; Wendler, Olaf

2012-08-01

Transapical (TA) aortic valve implantation (AVI) has evolved as an alternative procedure for high-risk patients. We evaluated the second-generation SAPIEN XT™ prosthesis in a prospective multicentre clinical trial. A total of 150 patients (age: 81.6 ± 5.8 years; 40.7% female) were included. Prosthetic valves (diameter: 23 mm (n = 36), 26 mm (n = 57) and 29 mm (n = 57)) were implanted. The ASCENDRA-II™ modified delivery system was used in the smaller sizes. Mean logistic EuroSCORE was 24.3 ± 7.0%, and mean STS score 7.5 ± 4.4%. All patients gave written informed consent. Off-pump AVI was performed using femoral arterial and venous access wires as a safety net. All but two patients received TA-AVI, as planned. The 29-mm valve showed similar function as the values of two other diameters did. Three patients (2%) required temporary cardiopulmonary bypass support. Postoperative complications included renal failure requiring long-term dialysis in four, bleeding requiring rethoracotomy in four, respiratory complication requiring reintubation in eight and sepsis in four patients, respectively. Thirty-day mortality was 13 (8.7%) for the total cohort and 2/57 (3.5%) for patients receiving the 29-mm valve, respectively. Echocardiography at discharge showed none or trivial aortic incompetence (AI) in 71% and mild-AI in 22% of the patients. Post-implantation AI was predominantly paravalvular and ≥ 2+ in 7% of patients. One patient required reoperation for AI within 30 days. The PREVAIL TA multicentre trial demonstrates good functionality and good outcomes for TA-AVI, using the SAPIEN XT™ prosthesis and its second-generation ASCENDRA-II™ delivery system, as well successful introduction of the 29-mm SAPIEN XT™ valve for the benefit of high-risk elderly patients.

Cost of vitamin K antagonist anticoagulant treatment in patients with metallic prosthetic valve in mitral position.

Science.gov (United States)

Ene, Gabriela; Garcia Raso, Aránzazu; Gonzalez-Dominguez Weber, Almudena; Hidalgo-Vega, Álvaro; Llamas, Pilar

2016-01-01

The initiation of oral anticoagulation therapy after valve replacement surgery requires strict monitoring because these patients are at high risk for the development of thrombotic complications and present an increased risk of bleeding. The aim of this study was to examine the total healthcare costs of oral anticoagulant treatment with vitamin K antagonists in patients with metallic prosthetic valves in the mitral position. Data from clinical records were used in the study including international normalized ratio results, number of medical visits, type of anticoagulant, use of rescue medication and hospital admissions from related complications. The drug cost was calculated based on the official Spanish Ministry of Health price list. Monitoring expenses were included in the cost of the medical supplies used in the procedures. Hospitalization costs were calculated using the diagnosis-related group price for each case. We collected data from 151 patients receiving oral anticoagulation therapy with vitamin K antagonist who were diagnosed with mitral prosthesis (n = 90), mitro-aortic prosthesis (n = 57), and mitral and tricuspid prosthesis (n = 4). The total direct healthcare cost was €15302.59, with a mean total cost per patient per year of €1558.15 (±2774.58) consisting of 44.38 (±42.30) for drug cost, €71.41 (±21.43) for international normalized ratio monitoring, €429.52 (±126.87) for medical visits, €26.31 (±28.38) for rescue medication and €986.53 (±2735.68) for related complications. Most direct healthcare costs associated with the sampled patients arose from the specialist-care monitoring required for treatment. Good monitoring is inversely related to direct healthcare costs.

Comparison of Range of Motion After Total Knee Prosthesis According to Different Type of Prosthesis

Directory of Open Access Journals (Sweden)

Firat Seyfettinoglu

2016-07-01

Full Text Available Aim: The aim of this study is to determine the effectiveness and range of motion of different type of knee prosthesis. Material and Method: This study includes 180 of 225 patients (139 F, 41 M, average age: 65, range of age: 51-82 between April 2005 and September 2007 with the diagnosis of gonarthrosis. All patients underwent to primary total knee arthroplasty. Primary osteoartrhritis is the reason of gonarthrosis. The patients with secondary osteoartrhritis were excluded from the study. All the patients were operated by the same surgical team and rehabilitated after surgery. Patella didnt change any patient. PCL was protected in some of the patients and cut some of patients. Totally seven type prosthesis in 16 subgroup were applied to the patients. All measurement were done by the same surgeon. Average follow up period was 31 months (24-49 months. Results: Patients without subgrouping were tested according to the range of motion before and after surgery to the type of the prosthesis trademark. Range of motion was decreased with the usage of Rotaglide and LCS® type of prosthesis. Range of motion didnt change with the usage of Maxim and Kinemax type. The range of motion increased in the other trademark of prosthesis. Flexion angle was increased statistically significant with nexgen® and scorpio® prosthesis (p

The current status of fluoroscopy and echocardiography in the diagnosis of prosthetic valve thrombosis-a review article.

Science.gov (United States)

Gürsoy, Mustafa Ozan; Kalçik, Macit; Karakoyun, Süleyman; Özkan, Mehmet

2015-01-01

Prosthetic valve thrombosis (PVT) is a potentially life-threatening complication of heart valve replacement. Early diagnosis is crucial for the prevention of significantly morbid and lethal complications. Cinefluoroscopy (CF) and echocardiography have been widely used for diagnosing PVT. In recent years, the role of CF has declined since the introduction of transesophageal echocardiography and the great improvements in ultrasound technology including real time three-dimensional imaging. Nevertheless, both echocardiography and CF provide different kinds of information on prosthesis function, and therefore they are considered as complementary and not alternative. In this review, we aimed to summarize the current status of CF and echocardiography in the diagnosis of PVT. © 2014, Wiley Periodicals, Inc.

Porous organic cages

Science.gov (United States)

Tozawa, Tomokazu; Jones, James T. A.; Swamy, Shashikala I.; Jiang, Shan; Adams, Dave J.; Shakespeare, Stephen; Clowes, Rob; Bradshaw, Darren; Hasell, Tom; Chong, Samantha Y.; Tang, Chiu; Thompson, Stephen; Parker, Julia; Trewin, Abbie; Bacsa, John; Slawin, Alexandra M. Z.; Steiner, Alexander; Cooper, Andrew I.

2009-12-01

Porous materials are important in a wide range of applications including molecular separations and catalysis. We demonstrate that covalently bonded organic cages can assemble into crystalline microporous materials. The porosity is prefabricated and intrinsic to the molecular cage structure, as opposed to being formed by non-covalent self-assembly of non-porous sub-units. The three-dimensional connectivity between the cage windows is controlled by varying the chemical functionality such that either non-porous or permanently porous assemblies can be produced. Surface areas and gas uptakes for the latter exceed comparable molecular solids. One of the cages can be converted by recrystallization to produce either porous or non-porous polymorphs with apparent Brunauer-Emmett-Teller surface areas of 550 and 23m2g-1, respectively. These results suggest design principles for responsive porous organic solids and for the modular construction of extended materials from prefabricated molecular pores.

Cage-based performance capture

CERN Document Server

Savoye, Yann

2014-01-01

Nowadays, highly-detailed animations of live-actor performances are increasingly easier to acquire and 3D Video has reached considerable attentions in visual media production. In this book, we address the problem of extracting or acquiring and then reusing non-rigid parametrization for video-based animations. At first sight, a crucial challenge is to reproduce plausible boneless deformations while preserving global and local captured properties of dynamic surfaces with a limited number of controllable, flexible and reusable parameters. To solve this challenge, we directly rely on a skin-detached dimension reduction thanks to the well-known cage-based paradigm. First, we achieve Scalable Inverse Cage-based Modeling by transposing the inverse kinematics paradigm on surfaces. Thus, we introduce a cage inversion process with user-specified screen-space constraints. Secondly, we convert non-rigid animated surfaces into a sequence of optimal cage parameters via Cage-based Animation Conversion. Building upon this re...

Implant-Retained Auricular Prosthesis: A Case Report

OpenAIRE

Ozturk, A. Nilgun; Usumez, Aslihan; Tosun, Zekeriya

2010-01-01

Extraoral implant retained prosthesis have been proven to be a predictable treatment option for maxillofacial rehabilitation. This case report describes the clinical and laboratory procedures for fabricating an auricular prosthesis. In this case report, an auricular prosthesis was fabricated for a patient who lost the left and right external ear in an electrical burn. Extraoral implants and bar-and-clip retention for the proper connection of the auricular prosthesis to implant were used. This...

Permanent Quadriplegia Following Replacement of Voice Prosthesis.

Science.gov (United States)

Ozturk, Kayhan; Erdur, Omer; Kibar, Ertugrul

2016-11-01

The authors presented a patient with quadriplegia caused by cervical spine abscess following voice prosthesis replacement. The authors present the first reported permanent quadriplegia patient caused by voice prosthesis replacement. The authors wanted to emphasize that life-threatening complications may be faced during the replacement of voice prosthesis. Care should be taken during the replacement of voice prosthesis and if some problems have been faced during the procedure patients must be followed closely.

[Selection of patients for transcatheter aortic valve implantation].

Science.gov (United States)

Tron, Christophe; Godin, Matthieu; Litzler, Pierre-Yves; Bauer, Fabrice; Caudron, Jérome; Dacher, Jean-Nicolas; Borz, Bogdan; Canville, Alexandre; Kurtz, Baptiste; Bessou, Jean-Paul; Cribier, Alain; Eltchaninoff, Hélène

2012-06-01

A good selection of patients is a crucial step before transcatheter aortic valve implantation (TAVI) in order to select the good indications and choose the access route. TAVI should be considered only in patients with symptomatic severe aortic stenosis and either contraindication or high surgical risk. Indication for TAVI should be discussed in a multidisciplinary team meeting. Echocardiography and/or CT scan are mandatory to evaluate the aortic annulus size and select the good prosthesis size. The possibility of transfemoral implantation is evaluated by angiography and CT scan, and based on the arterial diameters, but also on the presence of tortuosities and arterial calcifications. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

Velocity and shear stress distribution downstream of mechanical heart valves in pulsatile flow.

Science.gov (United States)

Giersiepen, M; Krause, U; Knott, E; Reul, H; Rau, G

1989-04-01

Ten mechanical valves (TAD 27 mm): Starr-Edwards Silastic Ball, Björk-Shiley Standard, Björk-Shiley Concave-Convex, Björk-Shiley Monostrut, Hall-Kaster (Medtronic-Hall), OmniCarbon, Bicer Val, Sorin, Saint-Jude Medical and Hemex (Duromedics) are investigated in a comparative in vitro study. The velocity and turbulent shear stress profiles of the valves were determined by Laser Doppler anemometry in two different downstream axes within a model aortic root. Depending on the individual valve design, velocity peaks up to 1.5 m/s and turbulent shear stress peaks up to 150 N/m2 were measured during the systolic phase. These shear stress peaks mainly occurred in areas of flow separation and intense momentum exchange. Directly downstream of the valves (measuring axis 0.55.dAorta) turbulent shear stress peaks occurred at peak systole and during the deceleration phase, while in the second measuring axis (1.5.dAorta) turbulence levels were lower. Shear stress levels were high at the borders of the fluid jets. The results are discussed from a fluid-dynamic point of view.

Laser-assisted fixation of a nitinol stapes prosthesis.

Science.gov (United States)

Schrötzlmair, Florian; Suchan, Fabian; Pongratz, Thomas; Krause, Eike; Müller, Joachim; Sroka, Ronald

2018-02-01

Otosclerosis is an inner ear bone disease characterized by fixation of the stapes and consequently progressive hearing loss. One treatment option is the surgical replacement of the stapes by a prosthesis. When so called "smart materials" like nitinol are used, prosthesis fixation can be performed using a laser without manual crimping on the incus. However, specific laser-prosthesis interactions have not been described yet. The aim of the present study was to elucidate the thermo-mechanical properties of the NiTiBOND® prosthesis as a basis for handling instructions for laser-assisted prosthesis fixation. Closure of the NiTiBOND® prosthesis was induced ex vivo by either a diode laser emitting at λ = 940 nm or a CO 2 laser (λ = 10,600 nm). Total energy for closure was determined. Suitable laser parameters (pulse duration, power per pulse, distance between tip of the laser fiber and prosthesis) were assessed. Specific laser-prosthesis interactions were recorded. Especially the diode laser was found to be an appropriate energy source. A total energy deposit of 60 mJ by pulses in near contact application was found to be sufficient for prosthesis closure ex vivo. Energy should be transmitted through a laser fiber equipollent to the prosthesis band diameter. Specific deformation characteristics due to the zonal prosthesis composition have to be taken into account. NiTiBOND® stapes prosthesis can be closed by very little energy when appropriate energy sources like diode lasers are used, suggesting a relatively safe application in vivo. Lasers Surg. Med. 50:153-157, 2018. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Fluid Structure Interaction simulation of heart prosthesis in patient-specific left-ventricle/aorta anatomies

Science.gov (United States)

Le, Trung; Borazjani, Iman; Sotiropoulos, Fotis

2009-11-01

In order to test and optimize heart valve prosthesis and enable virtual implantation of other biomedical devices it is essential to develop and validate high-resolution FSI-CFD codes for carrying out simulations in patient-specific geometries. We have developed a powerful numerical methodology for carrying out FSI simulations of cardiovascular flows based on the CURVIB approach (Borazjani, L. Ge, and F. Sotiropoulos, Journal of Computational physics, vol. 227, pp. 7587-7620 2008). We have extended our FSI method to overset grids to handle efficiently more complicated geometries e.g. simulating an MHV implanted in an anatomically realistic aorta and left-ventricle. A compliant, anatomic left-ventricle is modeled using prescribed motion in one domain. The mechanical heart valve is placed inside the second domain i.e. the body-fitted curvilinear mesh of the anatomic aorta. The simulations of an MHV with a left-ventricle model underscore the importance of inflow conditions and ventricular compliance for such simulations and demonstrate the potential of our method as a powerful tool for patient-specific simulations.

Fabrication and characterization of DLC coated microdimples on hip prosthesis heads.

Science.gov (United States)

Choudhury, Dipankar; Ay Ching, Hee; Mamat, Azuddin Bin; Cizek, Jan; Abu Osman, Noor Azuan; Vrbka, Martin; Hartl, Martin; Krupka, Ivan

2015-07-01

Diamond like carbon (DLC) is applied as a thin film onto substrates to obtain desired surface properties such as increased hardness and corrosion resistance, and decreased friction and wear rate. Microdimple is an advanced surface modification technique enhancing the tribological performance. In this study, DLC coated microdimples were fabricated on hip prosthesis heads and their mechanical, material and surface properties were characterized. An Electro discharge machining (EDM) oriented microdrilling was utilized to fabricate a defined microdimple array (diameter of 300 µm, depth of 70 µm, and pitch of 900 µm) on stainless steel (SS) hip prosthesis heads. The dimpled surfaces were then coated by hydrogenated amorphous carbon (a-C:H) and tetrahedral amorphous carbon (Ta-C) layers by using a magnetron sputtering technology. A preliminary tribology test was conducted on these fabricated surfaces against a ceramic ball in simulated hip joint conditions. It was found that the fabricated dimples were perpendicular to the spherical surfaces and no cutting-tools wear debris was detected inside the individual dimples. The a-C:H and Ta-C coatings increased the hardness at both the dimple edges and the nondimpled region. The tribology test showed a significant reduction in friction coefficient for coated surfaces regardless of microdimple arrays: the lowest friction coefficient was found for the a-C:H samples (µ = 0.084), followed by Ta-C (µ = 0.119), as compared to the SS surface (µ = 0.248). © 2014 Wiley Periodicals, Inc.

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

Science.gov (United States)

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.

Patients with hip prosthesis: radiotherapy treatment planning considerations

International Nuclear Information System (INIS)

Ganesh, K.M.; Supe, Sanjay S.

2000-01-01

The number of patients with hip prosthesis undergoing radiotherapy for pelvic cancer worldwide is increasing. This might be of importance depending on the materials in the prosthesis and whether any of the treatment fields are involved in the prosthesis. Radiotherapy planning involving the pelvic region of patients having total hip prosthesis has been found to be difficult due to the effect of the prosthesis on the dose distribution. This review is intended to project dosimetric considerations and possible solutions to this uncommon problem

Dolphin underwater bait-balling behaviors in relation to group and prey ball sizes.

Science.gov (United States)

Vaughn-Hirshorn, Robin L; Muzi, Elisa; Richardson, Jessica L; Fox, Gabriella J; Hansen, Lauren N; Salley, Alyce M; Dudzinski, Kathleen M; Würsig, Bernd

2013-09-01

We characterized dusky dolphin (Lagenorhynchus obscurus) feeding behaviors recorded on underwater video, and related behaviors to variation in prey ball sizes, dolphin group sizes, and study site (Argentina versus New Zealand, NZ). Herding behaviors most often involved dolphins swimming around the side or under prey balls, but dolphins in Argentina more often swam under prey balls (48% of passes) than did dolphins in NZ (34% of passes). This result may have been due to differences in group sizes between sites, since groups are larger in Argentina. Additionally, in NZ, group size was positively correlated with proportion of passes that occurred under prey balls (pdolphins in Argentina more often swam through prey balls (8% of attempts) than did dolphins in NZ (4% of attempts). This result may have been due to differences in prey ball sizes between sites, since dolphins fed on larger prey balls in Argentina (>74m(2)) than in NZ (maximum 33m(2)). Additionally, in NZ, dolphins were more likely to swim through prey balls to capture fish when they fed on larger prey balls (p=0.025). Copyright © 2013 Elsevier B.V. All rights reserved.

Golf Ball

Science.gov (United States)

1998-01-01

The Ultra 500 Series golf balls, introduced in 1995 by Wilson Sporting Goods Company, has 500 dimples arranged in a pattern of 60 spherical triangles. The design employs NASA's aerodynamics technology analysis of air loads of the tank and Shuttle orbiter that was performed under the Space Shuttle External Tank program. According to Wilson, this technology provides 'the most symmetrical ball surface available, sustaining initial velocity longer and producing the most stable ball flight for unmatched accuracy and distance.' The dimples are in three sizes, shapes and depths mathematically positioned for the best effect. The selection of dimples and their placement optimizes the interaction of opposing forces of lift and drag. Large dimples reduce air drag, enhance lift, and maintain spin for distance. Small dimples prevent excessive lift that destabilizes the ball flight and the medium size dimples blend the other two.

Caging in high energy reactions

International Nuclear Information System (INIS)

Ache, H.J.

1977-01-01

The concept of caging high energy reactions is considered. It is noted that there is no easy and unambiguous way, short of a complete and very tedious product and mechanistic analysis, which is feasible only for very few systems, to determine the contribution made by caging. It is emphasized that some products resulting from the hot reaction with a certain substrate may be formed via caging while others are not. In research on the mechanism of caging the results of Roots work on the reactions of hot 18 F with the CF 3 CH 3 system seem to provide evidence for caging, with 18 F being the caged moiety, thus proceeding via a radical--radical recombination mechanism. Their work with H 2 S additive also seems to indicate that scavenging via hydrogen abstraction from H 2 S to form does not interfere with the radical--radical recombination consistent with Bunkers molecular approach to explain the cage effects. In other research a series of observations resulting from stereochemical and combined stereochemical density variation techniques seem to favor a caged-complex. It is clear that a more conclusive answer can only be reached by more systematic studies, utilizing the whole range of nuclear reactions such as (n,2n), (n,γ) and E.C. processes in mechanistically well defined systems to elucidate the effect of variations in the recoil energies, by carrying out studies in different solvents or host substances to assess the effect of the physical parameters, such as molecule size and intermolecular interactions on the escape probability or caging efficiencies

Do Lordotic Cages Provide Better Segmental Lordosis Versus Nonlordotic Cages in Lateral Lumbar Interbody Fusion (LLIF)?

Science.gov (United States)

Sembrano, Jonathan N; Horazdovsky, Ryan D; Sharma, Amit K; Yson, Sharon C; Santos, Edward R G; Polly, David W

2017-05-01

A retrospective comparative radiographic review. To evaluate the radiographic changes brought about by lordotic and nonlordotic cages on segmental and regional lumbar sagittal alignment and disk height in lateral lumbar interbody fusion (LLIF). The effects of cage design on operative level segmental lordosis in posterior interbody fusion procedures have been reported. However, there are no studies comparing the effect of sagittal implant geometry in LLIF. This is a comparative radiographic analysis of consecutive LLIF procedures performed with use of lordotic and nonlordotic interbody cages. Forty patients (61 levels) underwent LLIF. Average age was 57 years (range, 30-83 y). Ten-degree lordotic PEEK cages were used at 31 lumbar interbody levels, and nonlordotic cages were used at 30 levels. The following parameters were measured on preoperative and postoperative radiographs: segmental lordosis; anterior and posterior disk heights at operative level; segmental lordosis at supra-level and subjacent level; and overall lumbar (L1-S1) lordosis. Measurement changes for each cage group were compared using paired t test analysis. The use of lordotic cages in LLIF resulted in a significant increase in lordosis at operative levels (2.8 degrees; P=0.01), whereas nonlordotic cages did not (0.6 degrees; P=0.71) when compared with preoperative segmental lordosis. Anterior and posterior disk heights were significantly increased in both groups (Plordosis (lordotic P=0.86 vs. nonlordotic P=0.25). Lordotic cages provided significant increase in operative level segmental lordosis compared with nonlordotic cages although overall lumbar lordosis remained unchanged. Anterior and posterior disk heights were significantly increased by both cages, providing basis for indirect spinal decompression.

Hereditary spherocytosis and elliptocytosis associated with prosthetic heart valve replacement: rheological study of erythrocyte modifications.

Science.gov (United States)

Caprari, Patrizia; Tarzia, Anna; Mojoli, Giorgio; Cianciulli, Paolo; Mannella, Emilio; Martorana, Maria Cristina

2009-04-01

The implantation of a prosthetic heart valve (HVP) in patients with hereditary spherocytosis (HS) and hereditary elliptocytosis (HE) is rare, and the changes in the structure and deformability of erythrocytes that follow implantation in these patients have been poorly described. In the present study, the erythrocytes in HS and HE patients with mechanical HVP were compared to the erythrocytes in patients with only congenital membrane defects, in terms of biochemical modifications and rheological behaviour. Integral and cytoskeletal erythrocyte membrane proteins were studied, and blood viscosity (shear rate/shear stress ratio), aggregation ratio [eta(1 s(-1))/eta(200 s(-1))], and red cell visco-elasticity were determined. Valve replacement with a mechanical prosthesis worsened anaemia and resulted in a change in haemolysis, from sub-clinical to evident. The rheological investigation of erythrocytes from HS patients confirmed the characteristic increased viscosity and aggregation ratio and the decreased deformability. The rheological behaviour of erythrocytes from patients with HVP showed a decrease in viscosity and an increase in elastic modulus. In these patients, the prosthesis seems to have induced traumatic damage to the erythrocyte membrane, leading to fragmentation and lysis, which in turn modified rheological parameters. The biochemical and rheological investigation allowed us to understand the clinical and haematological pictures of the patients and to describe the role played by different factors in haemolytic anaemia.

Minimally invasive redo mitral valve surgery without aortic crossclamp.

Science.gov (United States)

Milani, Rodrigo; Brofman, Paulo Roberto Slud; Oliveira, Sergio; Patrial Neto, Luiz; Rosa, Matheus; Lima, Victor Hugo; Binder, Luis Fernando; Sanches, Aline

2013-01-01

Reoperations of the mitral valve have a higher rate of complications when compared with the first surgery. With the field of video-assisted techniques for the first surgery of mitral valve became routine, reoperation cases began to arouse interest for this less invasive procedures. To assess the results and the technical difficulties in 10 patients undergoing minimally invasive redo mitral valve surgery. Cardiopulmonary bypass was installed through a cannula placed in the femoral vessels and right internal jugular vein, conducted in 28 degrees of temperature in ventricular fibrillation. A right lateral thoracotomy with 5 to 6 cm in the third or fourth intercostal space was done, pericardium was displaced only at the point of atriotomy. The aorta was not clamped. Ten patients with mean age of 56.9 ± 10.5 years, four were in atrial fibrilation rhythm and six in sinusal. Average time between first operation and reoperations was 11 ± 3.43 years. The mean EuroSCORE group was 8.3 ± 1.82. The mean ventricular fibrillation and cardiopulmonary bypass was respectively 70.9 ± 17.66 min and 109.4 ± 25.37 min. The average length of stay was 7.6 ± 1.5 days. There were no deaths in this series. Mitral valve reoperation can be performed through less invasive techniques with good immediate results, low morbidity and mortality. However, this type of surgery requires a longer duration of cardiopulmonary bypass, especially in cases where the patient already has prosthesis. The presence of a minimal aortic insufficiency also makes this procedure technically more challenging.

21 CFR 872.3960 - Mandibular condyle prosthesis.

Science.gov (United States)

2010-04-01

... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3960 Mandibular condyle prosthesis. (a) Identification. A mandibular condyle prosthesis is a device that is intended to be implanted in the human jaw to... requirement for premarket approval for any mandibular condyle prosthesis intended to be implanted in the human...

The M6-C Cervical Disk Prosthesis: First Clinical Experience in 33 Patients.

Science.gov (United States)

Thomas, Sam; Willems, Karel; Van den Daelen, Luc; Linden, Patrick; Ciocci, Maria-Cristina; Bocher, Philippe

2016-05-01

Retrospective study. To determine the short-term clinical succesrate of the M6-C cervical disk prosthesis in primary and secondary surgery. Cervical disk arthroplasty (CDA) provides an alternative to anterior cervical decompression and fusion for the treatment of spondylotic radiculopathy or myelopathy. The prevention of adjacent segment disease (ASD), a possible complication of anterior cervical decompression and fusion, is its most cited--although unproven--benefit. Unlike older arthroplasty devices that rely on a ball-and-socket-type design, the M6-C cervical disk prosthesis represents a new generation of unconstrained implants, developed to achieve better restoration of natural segmental biomechanics. This device should therefore optimize clinical performance of CDA and reduce ASD. All patients had preoperative computed tomography or magnetic resonance imaging and postoperative x-rays. Clinical outcome was assessed using the Neck Disability Index, a Visual Analog Scale, and the SF-36 questionnaire. Patients were asked about overall satisfaction and whether they would have the surgery again. Thirty-three patients were evaluated 17.1 months after surgery, on average. Nine patients had a history of cervical interventions. Results for Neck Disability Index, Visual Analog Scale, and SF-36 were significantly better among patients who had undergone primary surgery. In this group, 87.5% of patients reported a good or excellent result and 91.7% would have the procedure again. In contrast, all 4 device-related complications occurred in the small group of patients who had secondary surgery. The M6-C prosthesis appears to be a valuable addition to the CDA armatorium. It generates very good results in patients undergoing primary surgery, although its use in secondary surgery should be avoided. Longer follow-up is needed to determine to what measure this device can prevent ASD.

Estudo experimental do implante transcateter de prótese valvada autoexpansível na via de saída do ventrículo direito em porcos Transcatheter implantation of self-expandable valved prosthesis in outlet right ventricle an experimental study in pigs

Directory of Open Access Journals (Sweden)

José Cícero Stocco Guilhen

2011-09-01

right heart failure with clinical deterioration. These children require multiple interventions throughout their lives, which impose a high rate of morbidity and mortality. OBJECTIVE: To develop a less invasive technique for implantation of a valved prosthesis through the right ventricle. METHODS: The valved prosthesis consists of an auto expanding metal stent built with nitinol, surrounded with polyester, where the three leaflets of bovine pericardium were mounted. Twelve pigs were used to perform the implants. Echocardiographic control was performed immediately after implantation and one, four, eight and 12 weeks. RESULTS: One animal showed reflux of moderate to severe and three mild reflux. Transvalvular gradients measured before implantation ranged from 3 to 6 mmHg and that soon after the implant was increased, ranging from 7 to 45 mmHg. There was a decrease in these gradients during follow up and in only four of the twelve animals the gradients were above 20 mmHg. Thrombus formation occurred in the prosthesis of six animals, and this was the most frequent complication. CONCLUSION: These findings highlight the need for studies with the use of anticoagulants and antiplatelet, an attempt to reduce this event. The study aims to contribute for the start of the use of prosthetic heart valves that could be implanted through minimally invasive techniques without the use of cardiopulmonary bypass

Frictional performance of ball screw

International Nuclear Information System (INIS)

Nakashima, Katuhiro; Takafuji, Kazuki

1985-01-01

As feed screws, ball screws have become to be adopted in place of trapezoidal threads. The structure of ball screws is complex, but those are the indispensable component of NC machine tools and machining centers, and are frequently used for industrial robots. As the problems in the operation of ball screws, there are damage, life and the performance related to friction. As to the damage and life, though there is the problem of the load distribution on balls, the results of the research on rolling bearings are applied. The friction of ball screws consists of the friction of balls and a spiral groove, the friction of a ball and a ball, the friction in a ball-circulating mechanism and the viscous friction of lubricating oil. It was decided to synthetically examine the frictional performance of ball screws, such as driving torque, the variation of driving torque, efficiency, the formation of oil film and so on, under the working condition of wide range, using the screws with different accuracy and the nuts of various circuit number. The experimental setup and the processing of the experimental data, the driving performance of ball screws and so on are reported. (Kako, I.)

Long-Term Outcome of the Sorin Freedom SOLO Stentless Aortic Valve.

Science.gov (United States)

Christ, Torsten; Claus, Benjamin; Zielinski, Christina; Falk, Volkmar; Grubitzsch, Herko

2016-11-01

The Sorin Freedom SOLO valve is a third-generation stentless aortic valve which shows beneficial hemodynamic performance compared to stented bioprostheses. Long-term results regarding hemodynamics, the durability of the valve, and patient outcome are scarce, and their acquisition was the aim of this single-center study. Between 2005 and 2006, a total of 68 consecutive patients (30 males, 38 females; mean age at surgery 76.1 ± 6.3 years) underwent aortic valve replacement with a Sorin Freedom SOLO prosthesis. Indications were aortic stenosis (n = 50), aortic regurgitation (n = 1) and mixed lesions (n = 17). Associated procedures were performed in 31 patients (45.6%), most of which were coronary artery bypass grafting (68.8 %). The follow up was performed by telephone interviews, and clinical and echocardiographic examinations. Morbidity, mortality and echocardiographic data were analyzed. The total follow up was 501.1 patient-years, with a mean follow up of 7.4 ± 3.4 years (maximum 11.2 years). The follow up was 100% complete. Hospital mortality was 4.4% (n = 3). Actuarial survival at five and 10 years was 76.5 ± 5.1% and 41.5 ± 6.5%, respectively. Reinterventions were performed in eight patients; these included three reoperations due to endocarditis, four transcatheter aortic valve implantations, and one reoperation due to structural valve deterioration (SVD). The overall freedom from valve reintervention due to SVD at five and 10 years was 97.8 ± 2.2% and 82.9 ± 7.5%, respectively. After eight years, echocardiography demonstrated peak and mean transvalvular gradients of 18 ± 11 and 10 ± 7 mmHg, respectively. The overall effective and indexed aortic valve orifice areas were 1.73 ± 0.58 cm2 and 0.92 ± 0.33 cm2/m2, respectively. At long-term follow up the Sorin Freedom SOLO bioprosthesis was associated with favourable hemodynamic results and survival. Freedom from SVD was not superior to that occurring with stented bioprostheses.

Outcomes of interbody fusion cages used in 1 and 2-levels anterior cervical discectomy and fusion: titanium cages versus polyetheretherketone (PEEK) cages.

Science.gov (United States)

Niu, Chi-Chien; Liao, Jen-Chung; Chen, Wen-Jer; Chen, Lih-Huei

2010-07-01

A prospective study was performed in case with cervical spondylosis who underwent anterior cervical discectomy and fusion (ACDF) with titanium or polyetheretherketone (PEEK) cages. To find out which fusion cage yielded better clinical and radiographic results. Although use of autogenous iliac-bone grafts in ACDF for cervical disc diseases remain standard surgical procedure, donor site morbidity and graft collapse or breakage are concerns. Cage technology was developed to prevent these complications. However, there is no comparison regarding the efficacy between titanium and PEEK cage. January 2005 to January 2006, 53 patients who had 1 and 2-levels ACDF with titanium or PEEK cages were evaluated. We measured the rate and amount of interspace collapse, segmental sagittal angulations, and the radiographic fusion success rate. Odom criteria were used to assess the clinical results. The fusion rate was higher in the PEEK group (100% vs. 86.5%, P=0.0335). There was no significant difference between both groups in loss of cervical lordosis (3.2 + or - 2.4 vs. 2.8 + or - 3.4, P=0.166). The mean anterior interspace collapse (1.6 + or - 1.0 mm) in the titanium group was significantly higher than the collapse of the PEEK group (0.5 + or - 0.6 mm) (PPEEK group (PPEEK group achieved an 80% rate of successful clinical outcomes, compared with 75% in the titanium group (P=0.6642). The PEEK cage is superior to the titanium cage in maintaining cervical interspace height and radiographic fusion after 1 and 2-levels anterior cervical decompression procedures.

Expanding indications for valve-sparing aortic root reconstruction: early and midterm results.

Science.gov (United States)

Valo, Johanna; Jokinen, Janne J; Kaarne, Markku; Ihlberg, Leo

2013-02-01

Valve-sparing aortic root reconstruction (VSRR) is an accepted method to treat patients with aortic root dilation. The role of the VSRR is less well defined for patients with bicuspid aortic valve, severe aortic valve insufficiency, congenital heart defects, and type A aortic dissection. We studied the clinical outcome of patients who underwent VSRR for expanded indications. Seventy-eight patients underwent VSRR between the 2005 and 2012. Seventy-two patients (92%) underwent reimplantation and 6 patients (8%) were operated on with the remodeling technique. The mean age was 51 ± 12 years (range 24 to 73). For 71 patients (91%), the operation was elective, and for 7 (9%; all with type A aortic dissection), on an emergency basis. Preoperatively, the degree of aortic insufficiency was graded as 2+ or greater for 27 patients (35%). Connective tissue disorder (Marfan or Loeys-Dietz), bicuspid aortic valve, or congenital heart disease was present in 15 (19%), 15 (19%), and 7 patients (9%), respectively. Concomitant aortic valve leaflet repair was performed for 39 patients (50%). The mean follow-up time was 2.4 ± 1.7 years (range, 0.1 to 7.0). Thirty-day mortality was zero. The rate of postoperative complications was low: stroke 3%, renal failure 3%, prosthesis infection 1%, and low cardiac output syndrome 1%. Survival was 100% at 1 year and 97% at 5 years. Freedom from recurrent aortic valve insufficiency (≥2+) during the follow-up was 94%. The midterm results of VSRR in terms of survival, freedom from recurrent aortic valve insufficiency, and the need for reoperation are excellent, even for high-risk patients. Copyright © 2013 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

Revision hip arthroplasty by Waldemar Link custom-made total hip prosthesis

Directory of Open Access Journals (Sweden)

Medenica Ivica

2010-01-01

Full Text Available Background. The number of patients undergoing hip arthroplasty revision is constantly growing. Especially, complex problem is extensive loss of bone stock and pelvic discontinuity that requires reconstruction. Case report. The paper presented a 50-year old patient, who ten years ago underwent a total cement artrhroplasty of the left hip. A year after the primary operation the patient had difficulties in walking without crutches. Problems intensified in the last five years, the patient had severe pain, totally limited movement in the left hip and could not walk at all. Radiographically, we found loose femoral component, massive loss of bone stock of proximal femur, acetabular protrusion and a consequent pelvic discontinuity. Clinically, a completely disfunctional left hip joint was registered (Harris hip score - 7.1. We performed total rearthroplasty by a custom- made Waldemar Link total hip prosthesis with acetabular antiprotrusio cage and compensation of bone defects with a graft from the bone bank. A year after the operation, we found clinically an extreme improvement in Harris hip score - 87.8. Radiographically, we found stability of implanted components, a complete graft integration and bone bridging across the site of pelvic discontinuity. Conclusion. Pelvic discontinuity and massive loss of proximal femoral bone stock is a challenging and complex entity. Conventional prostheses cannot provide an adequate fixation and stability of the hip. Application of custom-made prosthesis (measured specifically for a patient and additional alografting bone defects is a good method in revision surgery after unsuccessful hip arthroplasty with extensive bone defects.

The Evolution of the Cup-Cage Technique for Major Acetabular Defects: Full and Half Cup-Cage Reconstruction.

Science.gov (United States)

Sculco, Peter K; Ledford, Cameron K; Hanssen, Arlen D; Abdel, Matthew P; Lewallen, David G

2017-07-05

Complex acetabular reconstruction for major bone loss can require advanced methods such as the use of a cup-cage construct. The purpose of this study was to review outcomes after the initial development of the cup-cage technique and the subsequent evolution to the use of a half cup-cage construct. We performed a retrospective, single-center review of 57 patients treated with cup-cage reconstruction for major acetabular bone loss. All patients had major acetabular defects graded as Paprosky Type 2B through 3B, with 34 (60%) having an associated pelvic discontinuity. Thirty patients received a full cup-cage construct and 27, a half cup-cage construct. The mean follow-up was 5 years. Both the full and half cup-cage cohorts demonstrated significantly improved Harris hip score (HHS) values, from 36 to 72 at a minimum of 2 years of follow-up (p cup-cage constructs and 6 (22%) of the half cup-cage constructs. One patient with a full cup-cage construct underwent re-revision of the acetabular component for progressive migration and aseptic loosening. Short-term survivorship free from re-revision for any cause or reoperation was 89% (83% and 96% for full and half cup-cage cohorts, respectively). Both full and half cup-cage constructs demonstrated successful clinical outcomes and survivorship in the treatment of major acetabular defects and pelvic discontinuity. Each method is utilized on the basis of individual intraoperative findings, including the extent and pattern of bone loss, the quality and location of host bone remaining after preparation, and the presence of pelvic discontinuity. Longer-term follow-up is required to understand the durability of these constructs in treating major acetabular defects and pelvic discontinuity. Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Individual ball possession in soccer.

Directory of Open Access Journals (Sweden)

Daniel Link

Full Text Available This paper describes models for detecting individual and team ball possession in soccer based on position data. The types of ball possession are classified as Individual Ball Possession (IBC, Individual Ball Action (IBA, Individual Ball Control (IBC, Team Ball Possession (TBP, Team Ball Control (TBC und Team Playmaking (TPM according to different starting points and endpoints and the type of ball control involved. The machine learning approach used is able to determine how long the ball spends in the sphere of influence of a player based on the distance between the players and the ball together with their direction of motion, speed and the acceleration of the ball. The degree of ball control exhibited during this phase is classified based on the spatio-temporal configuration of the player controlling the ball, the ball itself and opposing players using a Bayesian network. The evaluation and application of this approach uses data from 60 matches in the German Bundesliga season of 2013/14, including 69,667 IBA intervals. The identification rate was F = .88 for IBA and F = .83 for IBP, and the classification rate for IBC was κ = .67. Match analysis showed the following mean values per match: TBP 56:04 ± 5:12 min, TPM 50:01 ± 7:05 min and TBC 17:49 ± 8:13 min. There were 836 ± 424 IBC intervals per match and their number was significantly reduced by -5.1% from the 1st to 2nd half. The analysis of ball possession at the player level indicates shortest accumulated IBC times for the central forwards (0:49 ± 0:43 min and the longest for goalkeepers (1:38 ± 0:58 min, central defenders (1:38 ± 1:09 min and central midfielders (1:27 ± 1:08 min. The results could improve performance analysis in soccer, help to detect match events automatically, and allow discernment of higher value tactical structures, which is based on individual ball possession.

Live 3D TEE demonstrates and guides the management of prosthetic mitral valve obstruction.

Science.gov (United States)

Chahal, Mangeet; Pandya, Utpal; Adlakha, Satjit; Khouri, Samer J

2011-08-01

A 43-year-old woman, with a remote history of rheumatic mitral stenosis and a St. Jude prosthetic mitral valve replacement, presented with shortness of breath and palpitations, shortly after a long flight. On admission, atrial fibrillation with a rapid ventricular response was noted in the setting of a long history of noncompliance with her anticoagulation. Transesophageal echocardiography (TEE) demonstrated multiple laminated thrombi in the left atrial appendage. Live three-dimensional (3D) TEE confirmed this diagnosis and demonstrated an immobile posterior leaflet of the mitral prosthesis, which had direct implications in her management. She successfully underwent surgery for mitral valve replacement, left atrial appendage ligation, and a Maze procedure on the following day. The multiple thrombi within the atrial appendage were confirmed intraoperatively and pannus formation was determined to be the etiology of the leaflet immobility. © 2011, Wiley Periodicals, Inc.

Comparative assessment of hepatic Glisson's capsule and bovine pericardium in heart valve bioprostheses.

Science.gov (United States)

Kagramanov, I I; Kokshenev, I V; Dobrova, N B; Kastava, V T; Serov, R A; Zaets, S B

1998-05-01

The optimal material for heart valve bioprostheses remains disputable. This investigation was initiated to compare the properties of hepatic Glisson's capsule, clinical experience of which in cardiovascular surgery is minimal, with those of bovine pericardium. Hepatic Glisson's capsule was harvested from bull calves and used to create composite pulmonary arterial monocusp grafts and bioprostheses. Comparison of the strength and elastic properties of Glisson's capsule and bovine pericardium, as well as the hydrodynamic characteristics of valves made from these materials, was performed. Late results of operations using these materials were estimated echocardiographically. Although Glisson's capsule tissue is thinner than the bovine pericardium, its elasticity modulus is greater. However, the hydrodynamic characteristics of heart valves made from either tissue are similar. Moreover, valves made from Glisson's capsule have a lower systolic pressure gradient on the prosthesis and a higher effective orifice area. Composite pulmonary arterial xenopericardial grafts with a monocusp of Glisson's capsule were used in 30 patients during tetralogy of Fallot repair. Glisson's capsule was also used for tricuspid valve reconstruction and as a bioprosthesis in six patients with Ebstein's anomaly. At 1-2 years after surgery, the Glisson's capsule tissue remained thin and flexible, with no calcification. Although the hydrodynamic properties of hepatic Glisson's capsule and the bovine pericardium are similar, the capsule tissue is thinner and has a greater elasticity modulos. Thus, Glisson's capsule may be used for bioprosthesis construction both independently and in combination with bovine pericardium.

Cost of vitamin K antagonist anticoagulant treatment in patients with metallic prosthetic valve in mitral position

Directory of Open Access Journals (Sweden)

Gabriela Ene

2016-08-01

Full Text Available Background: The initiation of oral anticoagulation therapy after valve replacement surgery requires strict monitoring because these patients are at high risk for the development of thrombotic complications and present an increased risk of bleeding. Objectives: The aim of this study was to examine the total healthcare costs of oral anticoagulant treatment with vitamin K antagonists in patients with metallic prosthetic valves in the mitral position. Methods: Data from clinical records were used in the study including international normalized ratio results, number of medical visits, type of anticoagulant, use of rescue medication and hospital admissions from related complications. The drug cost was calculated based on the official Spanish Ministry of Health price list. Monitoring expenses were included in the cost of the medical supplies used in the procedures. Hospitalization costs were calculated using the diagnosis-related group price for each case. Results: We collected data from 151 patients receiving oral anticoagulation therapy with vitamin K antagonist who were diagnosed with mitral prosthesis (n = 90, mitro-aortic prosthesis (n = 57, and mitral and tricuspid prosthesis (n = 4. The total direct healthcare cost was €15302.59, with a mean total cost per patient per year of €1558.15 (±2774.58 consisting of 44.38 (±42.30 for drug cost, €71.41 (±21.43 for international normalized ratio monitoring, €429.52 (±126.87 for medical visits, €26.31 (±28.38 for rescue medication and €986.53 (±2735.68 for related complications. Conclusion: Most direct healthcare costs associated with the sampled patients arose from the specialist-care monitoring required for treatment. Good monitoring is inversely related to direct healthcare costs.

Dosimetry of a silicone breast prosthesis

International Nuclear Information System (INIS)

McGinley, P.H.; Powell, W.R.; Bostwick, J.

1980-01-01

Dose measurements were conducted in a phantom which simulates breast tissue and in another phantom which simulates a breast containing a silicone prosthesis. No detectable difference was found when the irradiations were carried out with tangential beams of 60 Co radiation. The degree of backscatter and absorption of radiation by the prosthesis and phantom were also similar. A slight decrease in dose of approximately 8% was found at the interface between the prosthesis and muscle-equivalent material

Development of furnished cages for laying hens.

Science.gov (United States)

Appleby, M C; Walker, A W; Nicol, C J; Lindberg, A C; Freire, R; Hughes, B O; Elson, H A

2002-09-01

1. A 3-year trial was carried out of cages for laying hens, occupying a full laying house. The main cage designs used were 5000 cm2 in area, 50 cm high at the rear and furnished with nests and perches. F cages had a front rollaway nest at the side, lined with artificial turf. FD cages also had a dust bath containing sand over the nest. H cages had two nest hollows at the side, one in front of the other. They were compared with conventional cages 2500 cm2 in area and 38 cm high at the rear. 2. Cages were stocked with from 4 to 8 ISA Brown hens per cage, resulting in varied allowances of area, feeder and perch per bird. No birds were beak trimmed. In F and FD cages two further treatments were applied: nests and dust baths were sometimes fitted with gates to exclude birds from dust baths in the morning and from both at night; elevated food troughs, with a lip 33 cm above the cage floor, were compared with standard troughs. 3. Management of the house was generally highly successful, with temperature control achieved by ventilation. Egg production was above breeders' standards and not significantly affected by cage design. More eggs per bird were collected when there were fewer birds per cage but food consumption also then tended to be higher. 4. The number of downgraded eggs was variable, with some tendency for more in furnished cages. Eggs laid in dust baths were often downgraded. Those laid at the back of the cage were frequently dirty because of accumulation of droppings. H nests were unsuccessful, with less than 50% of eggs laid in the nest hollows. However, up to 93% of eggs were laid in front rollaways, and few of these were downgraded. 5. Feather and foot damage were generally less in furnished than in conventional cages, greater where there were more birds per cage. With an elevated food trough there was less feather damage but more overgrowth of claws. In year 2, mortality was greater in cages with more birds. 6. Pre-laying behaviour was mostly settled in

Prosthetic valve sparing aortic root replacement: an improved technique.

Science.gov (United States)

Leacche, Marzia; Balaguer, Jorge M; Umakanthan, Ramanan; Byrne, John G

2008-10-01

We describe a modified surgical technique to treat patients with a previous history of isolated aortic valve replacement who now require aortic root replacement for an aneurysmal or dissected aorta. This technique consists of replacing the aortic root with a Dacron conduit, leaving intact the previously implanted prosthesis, and re-implanting the coronary arteries in the Dacron graft. Our technique differs from other techniques in that we do not leave behind any aortic tissue remnant and also in that we use a felt strip to obliterate any gap between the old sewing ring and the newly implanted graft. In our opinion, this promotes better hemostasis. We demonstrate that this technique is safe, feasible, and results in acceptable outcomes.

Duocentric® reversed shoulder prosthesis and Personal Fit® templates: innovative strategies to optimize prosthesis positioning and prevent scapular notching.

Science.gov (United States)

Trouilloud, P; Gonzalvez, M; Martz, P; Charles, H; Handelberg, F; Nyffeler, R W; Baulot, E

2014-05-01

We describe our experience with a new system of patient-specific template called Personal Fit(®), which is unique in shoulder surgery and used in combination with Duocentric(®) prosthesis. The reverse prosthesis's concept is the invention of Paul Grammont, developed with Grammont's team of Dijon University as from 1981, which led to the first reversed total shoulder prosthesis called Trumpet in 1985. The Duocentric(®) prosthesis developed in 2001 is the third-generation prosthesis, coming from the Trumpet and the second-generation prosthesis Delta(®) (DePuy). This prosthesis provides a novel solution to the notching problem with an inferior overhang integrated onto the glenoid baseplate. Personal Fit(®) system is based on reconstructing the shoulder joint bones in three dimensions using CT scan data, placing a landmark on the scapula and locating points on the glenoid and humerus. That will be used as a reference for the patient-specific templates. We study the glenoid position planned with Personal Fit(®) software relative to native glenoid position in 30 cases. On average, the difference between the planned retroversion (or anteversion in one case) and native retroversion was 8.6°.

Transcatheter aortic-valve implantation with one single minimal contrast media injection.

Science.gov (United States)

Arrigo, Mattia; Maisano, Francesco; Haueis, Sabine; Binder, Ronald K; Taramasso, Maurizio; Nietlispach, Fabian

2015-06-01

Performing transcatheter aortic valve implantation (TAVI) with the use of minimal contrast in patients at high-risk for acute kidney injury (AKI). Contrast-induced nephropathy (CIN) is a major cause of AKI following TAVI and is associated with increased morbidity and mortality. The amount of contrast media used increases the risk for CIN. Computed tomography was omitted during the screening process. For the procedure transfemoral access was default. The self-expanding CoreValve prosthesis was chosen in all patients to minimize the risk of annular rupture in case of oversizing. Valve sizing was based on echocardiography, aortography, calcification on fluoroscopy, as well as weight and height of the patient. A single contrast injection was performed to confirm correct position of the pigtail catheter at the level of the annulus. The pigtail then served as the marker for the device landing zone. Intraprocedural assessment of the implantation result relied on echocardiography and hemodynamics. Five patients with severe aortic stenosis and at high risk for developing CIN were included. Device success was achieved in all patients and no major complications occurred. The median dose of injected contrast media was 8 ml (4-9). All but one patient had improved renal function after the intervention compared to baseline. Our study shows feasibility of performing TAVI with a single minimal contrast media injection, using a self-expandable valve. This technique has the potential to reduce the incidence of CIN. © 2015 Wiley Periodicals, Inc.

Ball bearing defect models: A study of simulated and experimental fault signatures

Science.gov (United States)

Mishra, C.; Samantaray, A. K.; Chakraborty, G.

2017-07-01

Numerical model based virtual prototype of a system can serve as a tool to generate huge amount of data which replace the dependence on expensive and often difficult to conduct experiments. However, the model must be accurate enough to substitute the experiments. The abstraction level and details considered during model development depend on the purpose for which simulated data should be generated. This article concerns development of simulation models for deep groove ball bearings which are used in a variety of rotating machinery. The purpose of the model is to generate vibration signatures which usually contain features of bearing defects. Three different models with increasing level-of-complexity are considered: a bearing kinematics based planar motion block diagram model developed in MATLAB Simulink which does not explicitly consider cage and traction dynamics, a planar motion model with cage, traction and contact dynamics developed using multi-energy domain bond graph formalism in SYMBOLS software, and a detailed spatial multi-body dynamics model with complex contact and traction mechanics developed using ADAMS software. Experiments are conducted using Spectra Quest machine fault simulator with different prefabricated faulted bearings. The frequency domain characteristics of simulated and experimental vibration signals for different bearing faults are compared and conclusions are drawn regarding usefulness of the developed models.

Experimental investigations on the fluid-mechanics of an electrospun heart valve by means of particle image velocimetry.

Science.gov (United States)

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.

Malrotation of the McGhan Style 510 prosthesis.

NARCIS (Netherlands)

Schots, J.M.; Fechner, M.R.; Hoogbergen, M.M.; Tits, H.W.H.J.

2010-01-01

BACKGROUND: Anatomically shaped cohesive silicone breast implants are frequently used in aesthetic and reconstructive surgery. After successful results with the Style 410 prosthesis, McGhan (Natrelle, Allergan) introduced the Style 510 prosthesis. After using this novel prosthesis, the authors

Finger prosthesis: a boon to handicapped.

Science.gov (United States)

Gupta, Ridhima; Kumar, Lakshya; Rao, Jitendra; Singh, Kamleshwar

2013-08-29

This is a clinical case report of a 52-year-old male patient with four partially missing fingers of the left hand. The article describes the clinical and laboratory procedure of making prosthesis with modern silicone material. A wax pattern was fabricated using the right hand of the patient. A special type of wax was formulated to make the pattern so that it can be easily moulded and carved. Intrinsic and extrinsic staining was also performed to match the adjacent skin colour. The patient was given the finger prosthesis and was asked to use a half glove (sports) to mask the junction between the prosthesis and the normal tissue. It also provides additional retention to the artificial fingers. The patient felt his social acceptance improved after wearing the finger prosthesis.

Outcomes for the Commercial Use of Self-Expanding Prostheses in Transcatheter Aortic Valve Replacement: A Report From the STS/ACC TVT Registry.

Science.gov (United States)

Sorajja, Paul; Kodali, Susheel; Reardon, Michael J; Szeto, Wilson Y; Chetcuti, Stanley J; Hermiller, James; Chenoweth, Sharla; Adams, David H; Popma, Jeffrey J

2017-10-23

The authors sought to compare the outcomes of commercial transcatheter aortic valve replacement (TAVR) with the repositionable Evolut R platform to those observed with the CoreValve device in the Society of Thoracic Surgeons (STS)/American College of Cardiology (ACC) Transcatheter Valve Therapy (TVT) Registry. TAVR continues to evolve, with rapid adoption of iterative changes for commercial practice. Insight into the outcomes of this adoption is needed. Patients in the TVT Registry who had TAVR using a 23-, 26-, or 29-mm self-expanding prosthesis were enrolled. Site-reported events for procedural, in-hospital, and 30-day outcomes were examined. Between January 2014 and April 2016, 9,616 patients underwent TAVR with a self-expanding prosthesis with data entered in the TVT Registry. Compared with patients treated with CoreValve TAVR, those who received Evolut R TAVR had a lower STS-PROM score (8.0 ± 5.4% vs. 8.7 ± 5.3%; p < 0.001), more iliofemoral access (91.6% vs. 89.2%; p < 0.001), and more frequently had conscious sedation (27.4% vs. 12.7%; p < 0.001). With Evolut R TAVR, there was less need for a second prosthesis (2.2% vs. 4.5%; p < 0.001), less device migration (0.2% vs. 0.6%; p = 0.01), a lower incidence of moderate/severe paravalvular regurgitation (post-procedure, 4.4% vs. 6.2%; p < 0.001), and shorter median hospital stay (4.0 vs. 5.0 days; p < 0.001). Patients treated with Evolut R TAVR had greater device success (96.3% vs. 94.9%; p = 0.001). At 30 days, Evolut R patients had both lower mortality (3.7% vs. 5.3%; p < 0.001) and less need for a pacemaker (18.3% vs. 20.1%; p = 0.03). Commercial adoption of the Evolut R platform is associated with significant improvements in acute outcomes for patients undergoing TAVR for aortic stenosis. Copyright © 2017 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Ceramic Rail-Race Ball Bearings

Science.gov (United States)

Balzer, Mark A.; Mungas, Greg S.; Peters, Gregory H.

2010-01-01

Non-lubricated ball bearings featuring rail races have been proposed for use in mechanisms that are required to function in the presence of mineral dust particles in very low-pressure, dry environments with extended life. Like a conventional ball bearing, the proposed bearing would include an inner and an outer ring separated by balls in rolling contact with the races. However, unlike a conventional ball bearing, the balls would not roll in semi-circular or gothic arch race grooves in the rings: instead, the races would be shaped to form two or more rails (see figure). During operation, the motion of the balls would push dust particles into the spaces between the rails where the particles could not generate rolling resistance for the balls

Influence of the Quantity of Aortic Valve Calcium on the Agreement Between Automated 3-Dimensional Transesophageal Echocardiography and Multidetector Row Computed Tomography for Aortic Annulus Sizing.

Science.gov (United States)

Podlesnikar, Tomaz; Prihadi, Edgard A; van Rosendael, Philippe J; Vollema, E Mara; van der Kley, Frank; de Weger, Arend; Ajmone Marsan, Nina; Naji, Franjo; Fras, Zlatko; Bax, Jeroen J; Delgado, Victoria

2018-01-01

Accurate aortic annulus sizing is key for selection of appropriate transcatheter aortic valve implantation (TAVI) prosthesis size. The present study compared novel automated 3-dimensional (3D) transesophageal echocardiography (TEE) software and multidetector row computed tomography (MDCT) for aortic annulus sizing and investigated the influence of the quantity of aortic valve calcium (AVC) on the selection of TAVI prosthesis size. A total of 83 patients with severe aortic stenosis undergoing TAVI were evaluated. Maximal and minimal aortic annulus diameter, perimeter, and area were measured. AVC was assessed with computed tomography. The low and high AVC burden groups were defined according to the median AVC score. Overall, 3D TEE measurements slightly underestimated the aortic annulus dimensions as compared with MDCT (mean differences between maximum, minimum diameter, perimeter, and area: -1.7 mm, 0.5 mm, -2.7 mm, and -13 mm 2 , respectively). The agreement between 3D TEE and MDCT on aortic annulus dimensions was superior among patients with low AVC burden (AVC burden (≥3,025 arbitrary units). The interobserver variability was excellent for both methods. 3D TEE and MDCT led to the same prosthesis size selection in 88%, 95%, and 81% of patients in the total population, the low, and the high AVC burden group, respectively. In conclusion, the novel automated 3D TEE imaging software allows accurate and highly reproducible measurements of the aortic annulus dimensions and shows excellent agreement with MDCT to determine the TAVI prosthesis size, particularly in patients with low AVC burden. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

Three-dimensional prototyping for procedural simulation of transcatheter mitral valve replacement in patients with mitral annular calcification.

Science.gov (United States)

El Sabbagh, Abdallah; Eleid, Mackram F; Matsumoto, Jane M; Anavekar, Nandan S; Al-Hijji, Mohammed A; Said, Sameh M; Nkomo, Vuyisile T; Holmes, David R; Rihal, Charanjit S; Foley, Thomas A

2018-01-23

Three-dimensional (3D) prototyping is a novel technology which can be used to plan and guide complex procedures such as transcatheter mitral valve replacement (TMVR). Eight patients with severe mitral annular calcification (MAC) underwent TMVR. 3D digital models with digital balloon expandable valves were created from pre-procedure CT scans using dedicated software. Five models were printed. These models were used to assess prosthesis sizing, anchoring, expansion, paravalvular gaps, left ventricular outflow tract (LVOT) obstruction, and other potential procedure pitfalls. Results of 3D prototyping were then compared to post procedural imaging to determine how closely the achieved procedural result mirrored the 3D modeled result. 3D prototyping simulated LVOT obstruction in one patient who developed it and in another patient who underwent alcohol septal ablation prior to TMVR. Valve sizing correlated with actual placed valve size in six out of the eight patients and more than mild paravalvular leak (PVL) was simulated in two of the three patients who had it. Patients who had mismatch between their modeled valve size and post-procedural imaging were the ones that had anterior leaflet resection which could have altered valve sizing and PVL simulation. 3D printed model of one of the latter patients allowed modification of anterior leaflet to simulate surgical resection and was able to estimate the size and location of the PVL after inserting a valve stent into the physical model. 3D prototyping in TMVR for severe MAC is feasible for simulating valve sizing, apposition, expansion, PVL, and LVOT obstruction. © 2018 Wiley Periodicals, Inc.

Rotary Valve FY 2016 Highlights

Energy Technology Data Exchange (ETDEWEB)

Fitsos, P. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2016-12-07

The fiscal year started with the Rotary Valve (RV) being reassembled after having crashed in June of 2015. The crash occurred when the RV inner surface contacted the housing. The cause of the crash was never confirmed. No particles were found in the 2.5 thousandths of an inch gap and the filters the helium gas passed through were all clean. There were marks on the bearings that looked like electrostatic discharge as shown below in Figure 1. These marks hadn’t been seen before and there were similar discharge marks on some of the ball bearings. Examples of this were found in a literature search of bearing failures. This leads to a possible cause due to this arcing affecting the rotational accuracy of the bearings driving the RV into the housing.

Effect of a ball skill intervention on children's ball skills and cognitive functions.

Science.gov (United States)

Westendorp, Marieke; Houwen, Suzanne; Hartman, Esther; Mombarg, Remo; Smith, Joanne; Visscher, Chris

2014-02-01

This study examined the effect of a 16-wk ball skill intervention on the ball skills, executive functioning (in terms of problem solving and cognitive flexibility), and in how far improved executive functioning leads to improved reading and mathematics performance of children with learning disorders. Ninety-one children with learning disorders (age 7-11 yr old) were recruited from six classes in a Dutch special-needs primary school. The six classes were assigned randomly either to the intervention or to the control group. The control group received the school's regular physical education lessons. In the intervention group, ball skills were practiced in relative static, simple settings as well as in more dynamic and cognitive demanding settings. Both groups received two 40-min lessons per week. Children's scores on the Test of Gross Motor Development-2 (ball skills), Tower of London (problem solving), Trail Making Test (cognitive flexibility), Dutch Analysis of Individual Word Forms (reading), and the Dutch World in Numbers test (mathematics) at pretest, posttest, and retention test were used to examine intervention effects. The results showed that the intervention group significantly improved their ball skills, whereas the control group did not. No intervention effects were found on the cognitive parameters. However, within the intervention group, a positive relationship (r = 0.41, P = 0.007) was found between the change in ball skill performance and the change in problem solving: the larger children's improvement in ball skills, the larger their improvement in problem solving. The present ball skill intervention is an effective instrument to improve the ball skills of children with learning disorders. Further research is needed to examine the effect of the ball skill intervention on the cognitive parameters in this population.

21 CFR 878.3800 - External aesthetic restoration prosthesis.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false External aesthetic restoration prosthesis. 878... External aesthetic restoration prosthesis. (a) Identification. An external aesthetic restoration prosthesis... (general controls). The device is exempt from the premarket notification procedures in subpart E of part...

Rehabilitation of a Patient with an Intra Oral Prosthesis and an Extra Oral Orbital Prosthesis Retained with Magnets

OpenAIRE

Pattanaik, Seema; Wadkar, Aarti P.

2011-01-01

This clinical case report deals with a rehabilitation of a patient with an extensive maxillary and orbital defect using an intra oral prosthesis obturating the maxillary defect and extra oral orbital prosthesis retained with rare-earth magnets for secondary retention; primary retention was derived by snug fit of the prosthesis to underlying and adjacent tissues. The rehabilitation resulted in improved function, esthetics and comfort to the patient thus enabling him to lead a normal life.

[Experiences with cage combinations for guinea pigs].

Science.gov (United States)

von Zychlinski, J

1989-01-01

Special cage units described in 1982 for guinea pigs have been used either as cages for small groups of breeding animals or for caging of growing animals. By using these cages the following advantages have been noted; the cage size can be adapted to number, age and body weight of the animals; aggression and panic are avoided by corners, walls and tunnels; economic use of breeding males by mating with more females.

Study on the Measurement of Valve Leak Rate Using Acoustic Emission Technology

International Nuclear Information System (INIS)

Lee, Sang-Guk; Park, Jong-Hyuck; Yoo, Keun-Bae; Lee, Sun-Ki; Hong, Sung-Yull

2006-01-01

This study is to estimate the feasibility of acoustic emission(AE) method for the internal leak from the valves. In this study, 4 inch ball water valve leak tests using three different leak path and various leak rates were performed in order to analyze AE properties when leaks arise in valve seat. As a result of leak test for specimens simulated valve seat, we conformed that leak sound amplitude increased in proportion to the increase of leak rate, and leak rates were plotted versus peak acoustic amplitudes recorded within those two narrow frequency bands on each spectrum plot. The resulting plots of leak rate versus peak AE amplitude were the primary basis for determining the feasibility of quantifying leak acoustically. The large amount of data attained also allowed a favorable investigation of the effects of different leak paths, leak rates, pressure differentials and AE sensors on the AE amplitude spectrum. From the experimental results, it was suggested that the AE method for monitoring of leak was feasible. This paper describes quantitative measurements of fluid valve leak rates by the analysis of AE. Experimental apparatus were fabricated to accept a variety of leaking water valves in order to determine what characteristics of AE signal change with leak rate. The data for each valve were generated by varying the leak rate and recording the time averaged amplitude of AE versus frequency. Leak rates were varied by modifying the valve seating surfaces in ways designed to simulate actual defects observed in service. Most of the data analysis involved plotting the leak rate versus signal amplitude at a specific frequency to determine how well the two variables correlate in terms of accuracy, resolution, and repeatability

Study on torsional fretting wear behavior of a ball-on-socket contact configuration simulating an artificial cervical disk

International Nuclear Information System (INIS)

Wang, Song; Wang, Fei; Liao, Zhenhua; Wang, Qingliang; Liu, Yuhong; Liu, Weiqiang

2015-01-01

vitro cervical prosthesis simulations according to the literature. - Highlights: • Ball-on-socket contact configuration is designed to simulate an artificial cervical disk in structure. • The model with C-DLC mixed layer is tested based on in vitro simulation standard. • 3 running regimes (PSR, MR and SR) and 4 stages of T-n torque curves are observed. • The wear mechanism is a mix of surface scratch, adhesive wear and abrasive wear for PE. • The wear region and damage mechanism are different from those in ball-on-flat contact

Study on torsional fretting wear behavior of a ball-on-socket contact configuration simulating an artificial cervical disk

Energy Technology Data Exchange (ETDEWEB)

Wang, Song [State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Wang, Fei [School of Material Science and Engineering, China University of Mining and Technology, Xuzhou 221116 (China); Liao, Zhenhua [Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Biomechanics and Biotechnology Lab, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057 (China); Wang, Qingliang [School of Material Science and Engineering, China University of Mining and Technology, Xuzhou 221116 (China); Liu, Yuhong [State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Liu, Weiqiang, E-mail: weiqliu@hotmail.com [Biomechanics and Biotechnology Lab, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057 (China); State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China)

2015-10-01

vitro cervical prosthesis simulations according to the literature. - Highlights: • Ball-on-socket contact configuration is designed to simulate an artificial cervical disk in structure. • The model with C-DLC mixed layer is tested based on in vitro simulation standard. • 3 running regimes (PSR, MR and SR) and 4 stages of T-n torque curves are observed. • The wear mechanism is a mix of surface scratch, adhesive wear and abrasive wear for PE. • The wear region and damage mechanism are different from those in ball-on-flat contact.

Prosthesis infections after orthopedic joint replacement

DEFF Research Database (Denmark)

Song, Zhijun; Borgwardt, Lotte; Høiby, Niels

2013-01-01

Prosthesis-related infection is a serious complication for patients after orthopedic joint replacement, which is currently difficult to treat with antibiotic therapy. Consequently, in most cases, removal of the infected prosthesis is the only solution to cure the infection. It is, therefore...

Optical and Acoustic Sensor-Based 3D Ball Motion Estimation for Ball Sport Simulators †

Directory of Open Access Journals (Sweden)

Sang-Woo Seo

2018-04-01

Full Text Available Estimation of the motion of ball-shaped objects is essential for the operation of ball sport simulators. In this paper, we propose an estimation system for 3D ball motion, including speed and angle of projection, by using acoustic vector and infrared (IR scanning sensors. Our system is comprised of three steps to estimate a ball motion: sound-based ball firing detection, sound source localization, and IR scanning for motion analysis. First, an impulsive sound classification based on the mel-frequency cepstrum and feed-forward neural network is introduced to detect the ball launch sound. An impulsive sound source localization using a 2D microelectromechanical system (MEMS microphones and delay-and-sum beamforming is presented to estimate the firing position. The time and position of a ball in 3D space is determined from a high-speed infrared scanning method. Our experimental results demonstrate that the estimation of ball motion based on sound allows a wider activity area than similar camera-based methods. Thus, it can be practically applied to various simulations in sports such as soccer and baseball.

The bowling balls

CERN Multimedia

CERN Bulletin

2010-01-01

10 November 1972: CERN’s Bent Stumpe places an order for 12 bowling balls for a total cost of 95 US dollars. Although not evident at first sight, he is buying the heart of some of the first tracking devices to be used in the SPS control room. Today, Bent Stumpe’s device would be called a desktop mouse…   The first order for 4 bowling balls later changed to 12 balls. The bowling balls became the heart of Bent Stumpe's mouse. Almost 40 years ago, the web, Wikipedia and Google did not exist and it was much more difficult to know whether other people in other parts of the world or even in the same laboratory were facing the same problems or developing the same tools. At that time, Bent Stumpe was an electronics engineer, newly recruited to work on developments for the SPS Central Control room. One of the things his supervisor asked him to build as soon as possible was a device to control a pointer on a screen, also called a tracker ball. The heart of the device was the...

Life Estimation of Hip Joint Prosthesis

Science.gov (United States)

Desai, C.; Hirani, H.; Chawla, A.

2015-07-01

Hip joint is one of the largest weight-bearing structures in the human body. In the event of a failure of the natural hip joint, it is replaced with an artificial hip joint, known as hip joint prosthesis. The design of hip joint prosthesis must be such so as to resist fatigue failure of hip joint stem as well as bone cement, and minimize wear caused by sliding present between its head and socket. In the present paper an attempt is made to consider both fatigue and wear effects simultaneously in estimating functional-life of the hip joint prosthesis. The finite element modeling of hip joint prosthesis using HyperMesh™ (version 9) has been reported. The static analysis (load due to the dead weight of the body) and dynamic analysis (load due to walking cycle) have been described. Fatigue life is estimated by using the S-N curve of individual materials. To account for progressive wear of hip joint prosthesis, Archard's wear law, modifications in socket geometry and dynamic analysis have been used in a sequential manner. Using such sequential programming reduction in peak stress has been observed with increase in wear. Finally life is estimated on the basis of socket wear.

The effect of varying degrees of stenosis on the characteristics of turbulent pulsatile flow through heart valves.

Science.gov (United States)

Bluestein, D; Einav, S

1995-08-01

Many problems and complications associated with heart valves are related to the dynamic behavior of the valve and the resultant unsteady flow patterns. An accurate depiction of the spatial and temporal velocity and rms distributions imparts better understanding of flow related valve complications, and may be used as a guideline in valve design. While the generalized correlation between increased turbulence level and the severity of the stenosis is well established, few studies addressed the issue of the intermittent nature of turbulence and its timing in the cardiac cycle, and almost none assessed the effect of a progressive stenosis on the flow characteristics through heart valves. In this experimental work we simulated the type of flow which is present in normal and stenosed valves and conducted a comprehensive investigation of valve hemodynamics, valvular turbulence and morphology under varying degrees of stenosis. The characteristics of valves and stenoses were simulated closely, to achieve the flow conditions that initiate turbulent flow conditions. Laser Doppler anemometry (LDA) measurements were carried out in a pulse duplicator system distal to trileaflet polyurethane prosthetic heart valves, installed at mitral and aortic positions. The effect of the degree of the stenosis was comparatively studied through the structure of the turbulent jets emerging from normal and stenotic heart valves. Maximum turbulence level was achieved during the decelerating phase and correlated to the severity of the stenosis, followed by relaminarization of the flow during the acceleration phase. The intermittent nature of the turbulence emphasized the importance of realizing the timing of the turbulence production and its spatial location for optimizing current valve designs. The plug flow through the normal aortic valve prosthesis was replaced by jet like behavior for a 65% stenosis, with the jet becoming narrower and stronger for a 90% stenosis. The morphology of the velocity

The spinning ball spiral

International Nuclear Information System (INIS)

Dupeux, Guillaume; Le Goff, Anne; Quere, David; Clanet, Christophe

2010-01-01

We discuss the trajectory of a fast revolving solid ball moving in a fluid of comparable density. As the ball slows down owing to drag, its trajectory follows an exponential spiral as long as the rotation speed remains constant: at the characteristic distance L where the ball speed is significantly affected by the drag, the bending of the trajectory increases, surprisingly. Later, the rotation speed decreases, which makes the ball follow a second kind of spiral, also described in the paper. Finally, the use of these highly curved trajectories is shown to be relevant to sports.

Compact Q-balls

Energy Technology Data Exchange (ETDEWEB)

Bazeia, D., E-mail: bazeia@fisica.ufpb.br [Departamento de Física, Universidade Federal da Paraíba, 58051-970 João Pessoa, PB (Brazil); Losano, L.; Marques, M.A. [Departamento de Física, Universidade Federal da Paraíba, 58051-970 João Pessoa, PB (Brazil); Menezes, R. [Departamento de Ciências Exatas, Universidade Federal da Paraíba, 58297-000 Rio Tinto, PB (Brazil); Departamento de Física, Universidade Federal de Campina Grande, 58109-970 Campina Grande, PB (Brazil); Rocha, R. da [Centro de Matemática, Computação e Cognição, Universidade Federal do ABC, 09210-580 Santo André (Brazil)

2016-07-10

In this work we deal with non-topological solutions of the Q-ball type in two space–time dimensions, in models described by a single complex scalar field that engenders global symmetry. The main novelty is the presence of stable Q-balls solutions that live in a compact interval of the real line and appear from a family of models controlled by two distinct parameters. We find analytical solutions and study their charge and energy, and show how to control the parameters to make the Q-balls classically and quantum mechanically stable.

21 CFR 872.3950 - Glenoid fossa prosthesis.

Science.gov (United States)

2010-04-01

...) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3950 Glenoid fossa prosthesis. (a) Identification. A glenoid fossa prosthesis is a device that is intended to be implanted in the temporomandibular...

Feasibility of pig and human-derived aortic valve interstitial cells seeding on fixative-free decellularized animal pericardium.

Science.gov (United States)

Santoro, Rosaria; Consolo, Filippo; Spiccia, Marco; Piola, Marco; Kassem, Samer; Prandi, Francesca; Vinci, Maria Cristina; Forti, Elisa; Polvani, Gianluca; Fiore, Gianfranco Beniamino; Soncini, Monica; Pesce, Maurizio

2016-02-01

Glutaraldehyde-fixed pericardium of animal origin is the elective material for the fabrication of bio-prosthetic valves for surgical replacement of insufficient/stenotic cardiac valves. However, the pericardial tissue employed to this aim undergoes severe calcification due to chronic inflammation resulting from a non-complete immunological compatibility of the animal-derived pericardial tissue resulting from failure to remove animal-derived xeno-antigens. In the mid/long-term, this leads to structural deterioration, mechanical failure, and prosthesis leaflets rupture, with consequent need for re-intervention. In the search for novel procedures to maximize biological compatibility of the pericardial tissue into immunocompetent background, we have recently devised a procedure to decellularize the human pericardium as an alternative to fixation with aldehydes. In the present contribution, we used this procedure to derive sheets of decellularized pig pericardium. The decellularized tissue was first tested for the presence of 1,3 α-galactose (αGal), one of the main xenoantigens involved in prosthetic valve rejection, as well as for mechanical tensile behavior and distensibility, and finally seeded with pig- and human-derived aortic valve interstitial cells. We demonstrate that the decellularization procedure removed the αGAL antigen, maintained the mechanical characteristics of the native pig pericardium, and ensured an efficient surface colonization of the tissue by animal- and human-derived aortic valve interstitial cells. This establishes, for the first time, the feasibility of fixative-free pericardial tissue seeding with valve competent cells for derivation of tissue engineered heart valve leaflets. © 2015 Wiley Periodicals, Inc.

Gamma radiation and its role in bio prosthetic aortic valves implanted in rat hearts

International Nuclear Information System (INIS)

Lamas, Gloria I.; Kairiyama, Eulogia; Navia, Jose

2000-01-01

Porcine heart valves glutaraldehyde fixed are implanted in patients with valvular deterioration. Mineralization may be the major factor in the long-term failure of tissue bio prosthesis. Gamma radiation randomly breaks some glutaraldehyde cross-links. As a consequence of irradiation, the polymeric fibers belonging to the valvular tissue are broken too, leading to sites of collagen fiber disorganisation. It is well known that the collagen fibers may act as a passive nucleator of salts where the calcium phosphate salts precipitate. This salt concentration has been described in association with disintegrated sites of protein fiber, which may favour new sites where the calcium salts would be deposit. The irradiation process is a technique used for sterilization of porcine heart valve. The main objective of this work was to study the effect of different doses of gamma radiation on the calcification process of subcutaneously implanted valves in rats. Small pieces from glutaraldehyde fixed valves, irradiated to different doses with a 60 Co sources were implanted subcutaneously in rats. The calcium was measured by X-ray and atomic absorption spectrophotometry. In our experimental conditions and at the radiation doses used in these tests, the calcium measurements on control and irradiated material were not significantly different. We conclude that, at the employed doses, the gamma radiation does not alter the process. (author) [es

TiN thin film deposition by cathodic cage discharge: effect of cage configuration and active species

International Nuclear Information System (INIS)

De Freitas Daudt, N; Cavalcante Braz, D; Alves Junior, C; Pereira Barbosa, J C; Barbalho Pereira, M

2012-01-01

Plasma cathodic cage technique was developed recently in order to eliminate phenomena such as edge effects and overheating, which occur during conventional nitriding processes. In this work, the effect of plasma active species and cage configurations during thin film deposition of TiN were studied. This compound was chosen because its properties are very sensitive to slight variations in chemical composition and film thickness, becoming a good monitoring tool in fabrication process control. In order to verify the effect of cage geometry on the discharge and characteristics of the grown film, a cage made of titanium was used with different numbers and distribution of holes. Furthermore, different amounts of hydrogen were added to the Ar + N2 plasma atmosphere. Flow rates of Ar and N2 gas were fixed at 4 and 3 sccm, respectively and flow rates of H 2 gas was 0, 1 and 2 sccm. Plasma species, electrical discharge and physical characteristics of the grown film were analyzed by Optical Emission Spectroscopy (OES), Atomic Force Microscopy (AFM), X-Ray Diffraction. It was observed by OES that the luminous intensity associated to Hα species is not proportional to flow rate of H 2 gas. Electrical efficiency of the system, crystal structure and topography of the TiN film are strongly influenced by this behavior. For constant flow rate of H 2 gas, it was found that with more holes at the top of the cage, deposition rate, crystallinity and roughness are higher, if compared to cages with a small number of holes at the top of cage. On the other hand, the opposite behavior was observed when more holes were located at the sidewall of cage.

Mitral valve surgery using right anterolateral thoracotomy: is the aortic cannulation a safety procedure?

Science.gov (United States)

Guedes, Marco Antonio Vieira; Pomerantzeff, Pablo Maria Alberto; Brandão, Carlos Manuel de Almeida; Vieira, Marcelo Luiz Campos; Grinberg, Max; Stolf, Noedir Antonio Groppo

2010-01-01

The right anterolateral thoracotomy is an alternative technique for surgical approach of mitral valve. In these cases, femoral-femoral bypass still has been used, rising occurrence of complications related to femoral cannulation. Describe the technique and results of mitral valve treatment by right anterolateral thoracotomy using aortic cannulation for cardiac pulmonary bypass (CPB). From 1983 e 2008, 100 consecutive female patients, with average age 35 ±13 years, 96 (96%) underwent mitral valve surgical treatment in the Heart Institute of São Paulo. A right anterolateral thoracotomy approach associated with aortic cannulation was used for CPB. Eighty (80%) patients had rheumatic disease and 84 (84%) patients presented functional class III or IV. Were performed 45 (45%) comissurotomies, 38 (38%) valve repairs, 7(7%) mitral valve replacements, seven (7%) recomissurotomies and three (3%) prosthesis replacement. Sparing surgery was performed in 90 (90%) patients. The average CPB and clamp time were 57 ± 27 min e 39 ± 19 min, respectively. There were no in-hospital death, reoperation due to bleeding and convertion to sternotomy. Introperative complications were related to heart harvest (5%), especially in reoperations (3%). The most important complications in postoperative period were related to pulmonary system (11%), followed by atrial fibrilation (10%) but without major systemic repercussions. The mean inhospital length of stay was 8 ± 3 days. Follow-up was 6.038 patients/month. Actuarial survival was 98.0 ± 1.9% and freedom from reoperation was 81.4 ± 7.8% in 180 months. The right anterolateral thoracotomy associated with aortic cannulation in mitral valve surgery is a simple technique, reproducible and safety.

Failed total carpometacarpal joint prosthesis of the thumb

DEFF Research Database (Denmark)

Hansen, Torben Bæk; Homilius, Morten

2010-01-01

Total joint prosthesis in carpometacarpal joint arthritis of the thumb often fails. Loosening of the implant is often treated by resection arthroplasty, and we reviewed 10 patients, mean age 54 years (range 47-63) who were treated by resection arthroplasty after a failed total joint prosthesis. T...... in eight of 10 patients, but the mean Disabilities of the arm, shoulder, and hand (DASH) scores, self-reported pinch-grip-related function, and pain were comparable with our earlier published results with the Elektra carpometacarpal total joint prosthesis.......Total joint prosthesis in carpometacarpal joint arthritis of the thumb often fails. Loosening of the implant is often treated by resection arthroplasty, and we reviewed 10 patients, mean age 54 years (range 47-63) who were treated by resection arthroplasty after a failed total joint prosthesis....... The male:female ratio was 1:4 and the mean duration of observation 32 months (range 6-52). In three patients the revised implant was a MOJE uncemented carpometacarpal joint prosthesis and in seven patients an Elektra uncemented one. At follow-up grip strength was reduced to less than 90% of the other hand...

Stretch due to Penile Prosthesis Reservoir Migration

Directory of Open Access Journals (Sweden)

E. Baten

2016-03-01

Full Text Available A 43-year old patient presented to the emergency department with stretch, due to impossible deflation of the penile prosthesis, 4 years after successful implant. A CT-scan showed migration of the reservoir to the left rectus abdominis muscle. Refilling of the reservoir was inhibited by muscular compression, causing stretch. Removal and replacement of the reservoir was performed, after which the prosthesis was well-functioning again. Migration of the penile prosthesis reservoir is extremely rare but can cause several complications, such as stretch.

Rehabilitation of amputed thumb with a silicone prosthesis

OpenAIRE

Asnani, Pooja; Shivalingappa, Chandu Giriyapura; Mishra, Sunil Kumar; Somkuwar, Kirti; Khan, Faisal

2015-01-01

Creating prosthesis, having realistic skin surface and seamless visual integration with the surrounding tissues, requires both artistic and technical skill. Anatomical design, thin margins, lifelike fingernails and realistic color/contours are essential for patient satisfaction. Prosthesis is especially useful in case of lost body parts, as reconstructive surgery cannot fully restore aesthetics. This case report describes a simple technique for fabricating silicon finger prosthesis for a pati...

Comparison Between Acrylic Cage and Polyetheretherketone (PEEK) Cage in Single-level Anterior Cervical Discectomy and Fusion: A Randomized Clinical Trial.

Science.gov (United States)

Farrokhi, Majid R; Nikoo, Zahra; Gholami, Mehrnaz; Hosseini, Khadijeh

2017-02-01

Prospective, single-blind randomized-controlled clinical study. To compare polyetheretherketone (PEEK) cage with a novel Acrylic cage to find out which fusion cage yielded better clinical outcomes following single-level anterior cervical discectomy and fusion (ACDF). ACDF is considered a standard neurosurgical treatment for degenerative diseases of cervical intervertebral disks. There are many options, including bone grafts, bone cement, and spacers made of titanium, carbon fiber, and synthetic materials, used to restore physiological disk height and enhance spinal fusion, but the ideal device, which would provide immediate structural support and subsequent osteointegration and stability, has not been identified yet. To overcome this, we designed a new, inexpensive Acrylic cage. A total of 64 patients were eligible to participate and were randomly allocated to undergo ACDF either with Acrylic interbody fusion cage filled with bone substitute (n=32) or PEEK cage (n=32). Nurick's grading was used for quantifying the neurological deficit. Clinical and radiologic outcome was assessed preoperatively, immediately after surgery, and subsequently at 2, 6, and 12 months of follow-up using Odom's criteria and dynamic radiographs (flexion-extension) and computed tomography scans, respectively. There was a statistically significant improvement in the clinical outcomes of the Acrylic cage group compared with the PEEK cage group (mean difference: -0.438; 95% confidence interval, -0.807 to -0.068; P=0.016). There was a statistically significant difference in disk space height increase between the 2 groups at the 6- and 12-month follow-up. The Acrylic cage achieved higher fusion rate (good fusion) than the PEEK cage (96.9% vs. 93.8%). Intervertebral angle demonstrated a significant difference among the 2 treated groups throughout the follow-up period. This study suggests that the use of Acrylic cage is associated with good clinical and radiologic outcomes and it can be therefore a

Development and clinical application of a new testicular prosthesis.

Science.gov (United States)

Ning, Ye; Cai, Zhikang; Chen, Huixing; Ping, Ping; Li, Peng; Wang, Zhong; Li, Zheng

2011-11-01

A new type of testicular prosthesis made of silastic with an elliptical shape to mimic a normal testis was developed by our team and submitted for patenting in China. The prosthesis was produced in different sizes to imitate the normal testis of the patient. To investigate the effects and safety of the testicular prosthesis, 20 patients receiving testicular prosthesis implantation were recruited for this study. Follow-up after 6 months revealed no complications in the patients. All the patients answered that they were satisfied with their body image and the position of the implants, 19 patients were satisfied with the size and 16 patients were satisfied with the weight. These results show that the testicular prosthesis used in this study can meet patient's expectations. Patients undergoing orchiectomy should be offered the option to receive a testicular prosthesis implantation. The dimensions and weight of the available prosthetic implants should be further addressed to improve patient satisfaction.

Different techniques in fabrication of ocular prosthesis.

Science.gov (United States)

Cevik, Pinar; Dilber, Erhan; Eraslan, Oguz

2012-11-01

Loss of an eye caused by cancer, trauma, or congenital defect creates a deep psychological impact on an individual's life especially social and professional life. Custom-made prosthesis, compared to stock prosthesis, provides a better fit to the eye socket, better cosmetic results, and less discomfort to the patient in the long term. The main objective of this article was to describe 3 different alternative and practical techniques of fabricating custom-made ocular prosthesis. An impression of anophthalmic socket was made with the addition of cured silicone-based precision impression material in all techniques. A master cast was prepared and duplicated with condensation silicone. A self-cure acrylic resin was polymerized in the silicone model and was fitted into the patient's eye socket. A digital photograph of the patient's iris was made using a digital camera and printed on good-quality photo paper in various shades and sizes in the first and the second techniques. Then the photo paper was coated with PVC so as not to allow any color flowing. The proper iris was then inserted to the acrylic base. The prosthesis was final processed using orthodontic heat polymerizing clear acrylic resin.In the other technique, after the trying-in process with wax pattern, an acrylic base was fabricated using heat polymerizing scleral acrylic resin. The prosthetic iris was fabricated from a transparent contact lens by painting the lens with watercolor paints and attaching it to an acrylic resin with tissue conditioner. The final process was made with heat polymerizing transparent acrylic resin. Custom-made prosthesis allows better esthetic and functional results to the patient in comparison to stock prosthesis. Further follow-up is necessary to check the condition and fit of the ocular prosthesis in such patients.

Ten-year results of the Freedom Solo stentless heart valve: excellent haemodynamics but progressive valve dysfunction in the long term.

Science.gov (United States)

Sponga, Sandro; Barbera, Mila Della; Pavoni, Daisy; Lechiancole, Andrea; Mazzaro, Enzo; Valente, Marialuisa; Nucifora, Gaetano; Thiene, Gaetano; Livi, Ugolino

2017-05-01

Freedom Solo (FS) is a pericardial stentless heart valve showing excellent haemodynamic performance at mid-term. The aim of this study was to evaluate the long-term performance of such bioprostheses. Between December 2004 and November 2009, 109 patients (31 men; mean age 76 ± 6 years) underwent aortic valve replacement with FS. Preoperatively, the mean NYHA class was 2.5 ± 0.7, the mean EuroSCORE II, 2.8 ± 2.5. Mean prosthesis size was 22.7 ± 1.9 mm; concomitant procedures were performed in 65 patients. Structural valve deterioration (SVD) was diagnosed according to the Valve Academic Research Consortium-2 definition. Two patients (1.8%) died within 30 days. Follow-up (72 ± 36 months) was 100% completed. The 1-, 5- and 10-year actuarial survival rates were 89, 73 and 42%, respectively, with 8 valve-related deaths; the actuarial freedom from SVD was 99, 93 and 76%. During 61 ± 39 months of follow-up, echocardiographic findings worsened progressively: At discharge, 3-5 and 7-9 years, the mean gradient was 8 ± 4, 12 ± 11 and 19 ± 19 mmHg ( P  < 0.01); the indexed effective orifice area was 1.0 ± 0.2, 0.9 ± 0.2 and 0.8 ± 0.3 cm 2 /m 2 ( P  < 0.01). Of the 13 patients who developed SVD, it was due to aortic stenosis in 11. SVD was a predictor of cardiovascular mortality at univariate analysis (HR 2.87, 1.12-7.29); 2 explanted prostheses showed massive calcium deposits with mean calcium and phosphorus contents of 234 ± 16 and 116 ± 7 mg/g dry weight, respectively. The FS bioprosthesis shows excellent mid-term clinical and haemodynamic results and offers an alternative to other valves, particularly in the case of a small aortic annulus. Worsening of FS performance was observed at late follow-up because of progressive SVD with stenosis, questioning whether it should be used in patients with a long life expectancy. © The Author 2017. Published by Oxford University Press on behalf of the

Femoral Prosthesis Infection by Rhodotorula mucilaginosa▿

Science.gov (United States)

Savini, Vincenzo; Sozio, Federica; Catavitello, Chiara; Talia, Marzia; Manna, Assunta; Febbo, Fabio; Balbinot, Andrea; Di Bonaventura, Giovanni; Piccolomini, Raffaele; Parruti, Giustino; D'Antonio, Domenico

2008-01-01

This case report is a case history of a femoral prosthesis infection caused by Rhodotorula mucilaginosa in a human immunodeficiency virus patient. Though the pathogenicity of this organism for bone tissue has been previously reported, this is the first reported case of an orthopedic prosthesis infection by this species of the genus Rhodotorula. PMID:18753353

[Late complications following Björk-Shiley and St. Jude Medical heart valve replacement].

Science.gov (United States)

Horstkotte, D; Körfer, R; Budde, T; Haerten, K; Schulte, H D; Bircks, W; Loogen, F

1983-05-01

.2%), or prosthetic valve endocarditis with concomitant perivalvular regurgitation (0.46%). One valve had to be replaced because of fracture of the outlet strut of a BSM prosthesis. Hemorrhage due to the anticoagulant treatment was thus the most frequent complication, without significant intergroup differences, while thromboembolic complications were significantly more frequent after Björk-Shiley mitral, aortic, and double valve replacements than after St. Jude implantation. This may lead to the consideration of a change in the prophylaxis of thrombus formations with the St. Jude valve, especially in aortic valve replacements with sinus rhythm.

Kinematic analysis of a posterior-stabilized knee prosthesis.

Science.gov (United States)

Zhao, Zhi-Xin; Wen, Liang; Qu, Tie-Bing; Hou, Li-Li; Xiang, Dong; Bin, Jia

2015-01-20

The goal of total knee arthroplasty (TKA) is to restore knee kinematics. Knee prosthesis design plays a very important role in successful restoration. Here, kinematics models of normal and prosthetic knees were created and validated using previously published data. Computed tomography and magnetic resonance imaging scans of a healthy, anticorrosive female cadaver were used to establish a model of the entire lower limbs, including the femur, tibia, patella, fibula, distal femur cartilage, and medial and lateral menisci, as well as the anterior cruciate, posterior cruciate, medial collateral, and lateral collateral ligaments. The data from the three-dimensional models of the normal knee joint and a posterior-stabilized (PS) knee prosthesis were imported into finite element analysis software to create the final kinematic model of the TKA prosthesis, which was then validated by comparison with a previous study. The displacement of the medial/lateral femur and the internal rotation angle of the tibia were analyzed during 0-135° flexion. Both the output data trends and the measured values derived from the normal knee's kinematics model were very close to the results reported in a previous in vivo study, suggesting that this model can be used for further analyses. The PS knee prosthesis underwent an abnormal forward displacement compared with the normal knee and has insufficient, or insufficiently aggressive, "rollback" compared with the lateral femur of the normal knee. In addition, a certain degree of reverse rotation occurs during flexion of the PS knee prosthesis. There were still several differences between the kinematics of the PS knee prosthesis and a normal knee, suggesting room for improving the design of the PS knee prosthesis. The abnormal kinematics during early flexion shows that the design of the articular surface played a vital role in improving the kinematics of the PS knee prosthesis.

Kinematic Analysis of a Posterior-stabilized Knee Prosthesis

Directory of Open Access Journals (Sweden)

Zhi-Xin Zhao

2015-01-01

Full Text Available Background: The goal of total knee arthroplasty (TKA is to restore knee kinematics. Knee prosthesis design plays a very important role in successful restoration. Here, kinematics models of normal and prosthetic knees were created and validated using previously published data. Methods: Computed tomography and magnetic resonance imaging scans of a healthy, anticorrosive female cadaver were used to establish a model of the entire lower limbs, including the femur, tibia, patella, fibula, distal femur cartilage, and medial and lateral menisci, as well as the anterior cruciate, posterior cruciate, medial collateral, and lateral collateral ligaments. The data from the three-dimensional models of the normal knee joint and a posterior-stabilized (PS knee prosthesis were imported into finite element analysis software to create the final kinematic model of the TKA prosthesis, which was then validated by comparison with a previous study. The displacement of the medial/lateral femur and the internal rotation angle of the tibia were analyzed during 0-135° flexion. Results: Both the output data trends and the measured values derived from the normal knee′s kinematics model were very close to the results reported in a previous in vivo study, suggesting that this model can be used for further analyses. The PS knee prosthesis underwent an abnormal forward displacement compared with the normal knee and has insufficient, or insufficiently aggressive, "rollback" compared with the lateral femur of the normal knee. In addition, a certain degree of reverse rotation occurs during flexion of the PS knee prosthesis. Conclusions: There were still several differences between the kinematics of the PS knee prosthesis and a normal knee, suggesting room for improving the design of the PS knee prosthesis. The abnormal kinematics during early flexion shows that the design of the articular surface played a vital role in improving the kinematics of the PS knee prosthesis.

Kinematic Analysis of a Posterior-stabilized Knee Prosthesis

Science.gov (United States)

Zhao, Zhi-Xin; Wen, Liang; Qu, Tie-Bing; Hou, Li-Li; Xiang, Dong; Bin, Jia

2015-01-01

Background: The goal of total knee arthroplasty (TKA) is to restore knee kinematics. Knee prosthesis design plays a very important role in successful restoration. Here, kinematics models of normal and prosthetic knees were created and validated using previously published data. Methods: Computed tomography and magnetic resonance imaging scans of a healthy, anticorrosive female cadaver were used to establish a model of the entire lower limbs, including the femur, tibia, patella, fibula, distal femur cartilage, and medial and lateral menisci, as well as the anterior cruciate, posterior cruciate, medial collateral, and lateral collateral ligaments. The data from the three-dimensional models of the normal knee joint and a posterior-stabilized (PS) knee prosthesis were imported into finite element analysis software to create the final kinematic model of the TKA prosthesis, which was then validated by comparison with a previous study. The displacement of the medial/lateral femur and the internal rotation angle of the tibia were analyzed during 0–135° flexion. Results: Both the output data trends and the measured values derived from the normal knee's kinematics model were very close to the results reported in a previous in vivo study, suggesting that this model can be used for further analyses. The PS knee prosthesis underwent an abnormal forward displacement compared with the normal knee and has insufficient, or insufficiently aggressive, “rollback” compared with the lateral femur of the normal knee. In addition, a certain degree of reverse rotation occurs during flexion of the PS knee prosthesis. Conclusions: There were still several differences between the kinematics of the PS knee prosthesis and a normal knee, suggesting room for improving the design of the PS knee prosthesis. The abnormal kinematics during early flexion shows that the design of the articular surface played a vital role in improving the kinematics of the PS knee prosthesis. PMID:25591565

LHC gets the ball rolling

CERN Multimedia

2007-01-01

A technique involving a small ball with a transmitter embedded inside it has been successfully tested in Sector 7-8. The ball is sent through the LHC beam pipes to check the LHC interconnections. The multidisciplinary team responsible for the RF ball project to check the interconnections. From left to right: Rhodri Jones (AB/BI), Eva Calvo (AB/BI), Francesco Bertinelli (AT/MCS), Sonia Bartolome Jimenez (TS/IC), Sylvain Weisz (TS/IC), Paul Cruikshank (AT/VAC), Willemjan Maan (AT/VAC), Alain Poncet (AT/MCS), Marek Gasior (AB/BI). During the tests the ball is inserted very carefully into the vacuum chamber.A game of ping-pong at the LHC? On 13 September a rather unusual test was carried out in Sector 7-8 of the accelerator. A ball just a bit smaller than a ping-pong ball was carefully introduced into one of the accelerator’s two vacuum pipes, where it travelled 800 metres in the space of a few mi...

Prosthetic management of mid-facial defect with magnet-retained silicone prosthesis.

Science.gov (United States)

Buzayan, Muaiyed M

2014-02-01

Mid-facial defect is one of the most disfiguring and impairing defects. A design of prosthesis that is aesthetic and stable can be precious to a patient who has lost part of his face due to surgical excision. Prosthesis can restore the patients' self-esteem and confidence, which affects the patients and their life style. The aim of this case report is to describe a technique of mid-facial silicone prosthesis fabrication. To provide an aesthetic and stable facial prosthesis, the extra-oral prosthesis was fabricated using silicone material, while the intra-oral defect was restored with obturator prosthesis, and then both prostheses were connected and attached to each other using magnets. This clinical report describes the rehabilitation of a large mid-facial defect with a two-piece prosthesis. The silicone facial prosthesis was made hollow and lighter by using an acrylic framework. Two acrylic channels were included within the facial prosthesis to provide the patient with clean and patent airways. A sectional mid-facial prosthesis was made and retained in place by using magnets, which resulted in a significant improvement in the aesthetical and functional outcome without the need for plastic surgery. Silicone prostheses are reliable alternatives to surgery and should be considered in selected cases.

Effects of combined cryopreservation and decellularization on the biomechanical, structural and biochemical properties of porcine pulmonary heart valves.

Science.gov (United States)

Theodoridis, Karolina; Müller, Janina; Ramm, Robert; Findeisen, Katja; Andrée, Birgit; Korossis, Sotirios; Haverich, Axel; Hilfiker, Andres

2016-10-01

Non-fixed, decellularized allogeneic heart valve scaffolds seem to be the best choice for heart valve replacement, their availability, however, is quite limited. Cryopreservation could prolong their shelf-life, allowing for their ideal match to a recipient. In this study, porcine pulmonary valves were decellularized using detergents, either prior or after cryopreservation, and analyzed. Mechanical integrity was analyzed by uniaxial tensile testing, histoarchitecture by histological staining, and composition by DNA, collagen (hydroxyproline) and GAG (chondroitin sulfate) quantification. Residual sodium dodecyl sulfate (SDS) in the scaffold was quantified by applying a methylene blue activation assay (MBAS). Cryopreserved decellularized scaffolds (DC) and scaffolds that were decellularized after cryopreservation (CD) were compared to fresh valves (F), cryopreserved native valves (C), and decellularized only scaffolds (D). The E-modulus and tensile strength of decellularized (D) tissue showed no significant difference compared to DC and CD. The decellularization resulted in an overall reduction of DNA and GAG, with DC containing the lowest amount of GAGs. The DNA content in the valvular wall of the CD group was higher than in the D and DC groups. CD valves showed slightly more residual SDS than DC valves, which might be harmful to recipient cells. In conclusion, cryopreservation after decellularization was shown to be preferable over cryopreservation before decellularization. However, in vivo testing would be necessary to determine whether these differences are significant in biocompatibility or immunogenicity of the scaffolds. Absence of adverse effects on biomechanical stability of acellular heart valve grafts by cryopreservation, neither before nor after decellularization, allows the identification of best matching patients in a less time pressure dictated process, and therefore to an optimized use of a very limited, but best-suited heart valve prosthesis

A novel test cage with an air ventilation system as an alternative to conventional cages for the efficacy testing of mosquito repellents.

Science.gov (United States)

Obermayr, U; Rose, A; Geier, M

2010-11-01

We have developed a novel test cage and improved method for the evaluation of mosquito repellents. The method is compatible with the United States Environmental Protection Agency, 2000 draft OPPTS 810.3700 Product Performance Test Guidelines for Testing of Insect Repellents. The Biogents cages (BG-cages) require fewer test mosquitoes than conventional cages and are more comfortable for the human volunteers. The novel cage allows a section of treated forearm from a volunteer to be exposed to mosquito probing through a window. This design minimizes residual contamination of cage surfaces with repellent. In addition, an air ventilation system supplies conditioned air to the cages after each single test, to flush out and prevent any accumulation of test substances. During biting activity tests, the untreated skin surface does not receive bites because of a screen placed 150 mm above the skin. Compared with the OPPTS 810.3700 method, the BG-cage is smaller (27 liters, compared with 56 liters) and contains 30 rather than hundreds of blood-hungry female mosquitoes. We compared the performance of a proprietary repellent formulation containing 20% KBR3023 with four volunteers on Aedes aegypti (L.) (Diptera: Culicidae) in BG- and conventional cages. Repellent protection time was shorter in tests conducted with conventional cages. The average 95% protection time was 4.5 +/- 0.4 h in conventional cages and 7.5 +/- 0.6 h in the novel BG-cages. The protection times measured in BG-cages were more similar to the protection times determined with these repellents in field tests.

Body image and prosthesis satisfaction in the lower limb amputee.

OpenAIRE

Murray, Craig; Fox, Jezz

2002-01-01

Purpose: This study examines the relationship between prosthesis satisfaction and body image in lower limb prosthesis users, and the gendered variations within these relationships. Method: A total of 44 valid responses were obtained to an Internet survey regarding prosthesis satisfaction, body image, and phantom pain. Spearman Rho correlations were calculated for these three domains. Results: Moderate to high negative correlations were observed between Body Image Disturbance and Prosthesis Sa...

Segmental kyphosis after cervical interbody fusion with stand-alone polyetheretherketone (PEEK) cages: a comparative study on 2 different PEEK cages.

Science.gov (United States)

Kim, Chi Heon; Chung, Chun Kee; Jahng, Tae-Ahn; Park, Sung Bae; Sohn, Seil; Lee, Sungjoon

2015-02-01

Retrospective comparative study. Two polyetheretherketone (PEEK) cages of different designs were compared in terms of the postoperative segmental kyphosis after anterior cervical discectomy and fusion. Segmental kyphosis occasionally occurs after the use of a stand-alone cage for anterior cervical discectomy and fusion. Although PEEK material seems to have less risk of segmental kyphosis compared with other materials, the occurrence of segmental kyphosis for PEEK cages has been reported to be from 0% to 29%. There have been a few reports that addressed the issue of PEEK cage design. A total of 41 consecutive patients who underwent single-level anterior discectomy and fusion with a stand-alone cage were included. Either a round tube-type (Solis; 18 patients, S-group) or a trapezoidal tube-type (MC+; 23 patients, M-group) cage was used. The contact area between the cage and the vertebral body is larger in MC+ than in Solis, and anchoring pins were present in the Solis cage. The effect of the cage type on the segmental angle (SA) (lordosis vs. kyphosis) at postoperative month 24 was analyzed. Preoperatively, segmental lordosis was present in 12/18 S-group and 16/23 M-group patients (P=0.84). The SA was more lordotic than the preoperative angle in both groups just after surgery, with no difference between groups (P=0.39). At 24 months, segmental lordosis was observed in 9/18 S-group and 20/23 M-group patients (P=0.01). The patients in M-group were 7.83 times more likely than patients in S-group (P=0.04; odds ratio, 7.83; 95% confidence interval, 1.09-56.28) not to develop segmental kyphosis. The design of the PEEK cage used may influence the SA, and this association needs to be considered when using stand-alone PEEK cages.

Fabrication of temporary speech bulb prosthesis: A clinical report

OpenAIRE

Kasim Mohamed, K.; Anand Kumar, V.; Devi, N.; Padmanaban, T. V.

2010-01-01

Maxillofacial prosthesis is an art and science which not only replaces the lost structure sometimes it restores the functions also. Pharyngeal obturator is a prosthesis which closes the palatal and pharyngeal defects and improving the speech and other function. The following case report discusses palatopharyngeal insufficiency, impression procedures, fabrication of prosthesis and improvements in speech.

3D printed cardiac phantom for procedural planning of a transcatheter native mitral valve replacement

Science.gov (United States)

Izzo, Richard L.; O'Hara, Ryan P.; Iyer, Vijay; Hansen, Rose; Meess, Karen M.; Nagesh, S. V. Setlur; Rudin, Stephen; Siddiqui, Adnan H.; Springer, Michael; Ionita, Ciprian N.

2016-03-01

3D printing an anatomically accurate, functional flow loop phantom of a patient's cardiac vasculature was used to assist in the surgical planning of one of the first native transcatheter mitral valve replacement (TMVR) procedures. CTA scans were acquired from a patient about to undergo the first minimally-invasive native TMVR procedure at the Gates Vascular Institute in Buffalo, NY. A python scripting library, the Vascular Modeling Toolkit (VMTK), was used to segment the 3D geometry of the patient's cardiac chambers and mitral valve with severe stenosis, calcific in nature. A stereolithographic (STL) mesh was generated and AutoDesk Meshmixer was used to transform the vascular surface into a functioning closed flow loop. A Stratasys Objet 500 Connex3 multi-material printer was used to fabricate the phantom with distinguishable material features of the vasculature and calcified valve. The interventional team performed a mock procedure on the phantom, embedding valve cages in the model and imaging the phantom with a Toshiba Infinix INFX-8000V 5-axis Carm bi-Plane angiography system. Results: After performing the mock-procedure on the cardiac phantom, the cardiologists optimized their transapical surgical approach. The mitral valve stenosis and calcification were clearly visible. The phantom was used to inform the sizing of the valve to be implanted. Conclusion: With advances in image processing and 3D printing technology, it is possible to create realistic patientspecific phantoms which can act as a guide for the interventional team. Using 3D printed phantoms as a valve sizing method shows potential as a more informative technique than typical CTA reconstruction alone.

Femoral hip prosthesis design for Thais using multi-objective shape optimization

International Nuclear Information System (INIS)

Virulsri, Chanyaphan; Tangpornprasert, Pairat; Romtrairat, Parineak

2015-01-01

Highlights: • A multi-objective shape optimization was proposed to design hip prosthesis for Thais. • The prosthesis design was optimized in terms of safety of both cement and prosthesis. • The objective functions used the Soderberg fatigue strength formulations. • Safety factors of the cement and prosthesis are 1.200 and 1.109 respectively. • The newly designed prosthesis also fits well with chosen small-sized Thai femurs. - Abstract: The long-term success of Total Hip Arthroplasty (THA) depends largely on how well the prosthetic components fit the bones. The majority of cemented femoral hip prosthesis failures are due to aseptic loosening, which is possibly caused by cracking of the cement mantle. The strength of cement components is a function of cement mantles having adequate thickness. Since the size and shape of cemented femoral hip prostheses used in Thailand are based on designs for a Caucasian population, they do not properly conform to most Thai patients’ physical requirements. For these reasons, prostheses designed specifically for Thai patients must consider the longevity and functionality of both cement and prosthesis. The objective of this study was to discover a new design for femoral hip prostheses which is not only optimal and safe in terms of both cement and prosthesis, but also fits the selected Thai femur. This study used a small-sized Thai femoral model as a reference model for a new design. Biocompatible stainless steel 316L (SS316L) and polymethylmethacrylate (PMMA) were selected as raw materials for the prosthesis and bone cement respectively. A multi-objective shape optimization program, which is an interface between optimization C program named NSGA-II and a finite element program named ANSYS, was used to optimize longevity of femoral hip prostheses by varying shape parameters at assigned cross-sections of the selected geometry. Maximum walking loads of sixty-kilograms were applied to a finite element model for stress and