Science.gov

Sample records for disc mechanical mitral

  1. Mitral disc-valve variance

    PubMed Central

    Berroya, Renato B.; Escano, Fernando B.

    1972-01-01

    This report deals with a rare complication of disc-valve prosthesis in the mitral area. A significant disc poppet and struts destruction of mitral Beall valve prostheses occurred 20 and 17 months after implantation. The resulting valve incompetence in the first case contributed to the death of the patient. The durability of Teflon prosthetic valves appears to be in question and this type of valve probably will be unacceptable if there is an increasing number of disc-valve variance in the future. Images PMID:5017573

  2. DISC VARIANCE OF THE HARKEN MITRAL PROSTHESIS: THE CONTRIBUTION OF ASSOCIATED AORTIC REGURGITATION

    PubMed Central

    Yarnoz, Michael D.; Hueter, David; McCormick, John R.; Black, Harrison; Berger, Robert L.

    1977-01-01

    Four cases of severe mitral regurgitation due to disc variance of the Harken disc prosthesis in the mitral position are described. The valve occluder actually escaped into the left atrium in two patients, and neither survived despite emergency valve replacement. In the other two, disc malfunction was identified by flouroscopy, the prosthesis was replaced, and both patients survived. All four patients had associated aortic regurgitation, which most likely contributed to erosion of the disc edges. It is suggested that patients with the Harken disc prosthesis undergo periodic evaluation to detect abnormal disc motion. Images PMID:15216088

  3. Disc erosion in Models 103 and 104 of Beall mitral valve prostheses

    PubMed Central

    Gómez, Ricardo; Verduras, María José; Lopez-Quintana, Alfonso; Riera, Luis; Zerolo, Ignacio; Martinez-Bordiu, Cristóbal

    1981-01-01

    Three cases of severe disc variance and erosion of the Teflon-disc Beall mitral valve prosthesis (Models 103 and 104) are reported. In two patients, the Beall mitral valves were excised and replaced with two Björk-Shiley mitral valves. The remaining patient did not survive, and at autopsy, the lens was found at the aortic bifurcation level. Because of this potentially lethal complication, careful follow-up of patients with Beall mitral valve prostheses (Models 103 and 104) is recommended. Images PMID:15216211

  4. Disc erosion in Models 103 and 104 of Beall mitral valve prostheses.

    PubMed

    Gómez, Ricardo; Verduras, María José; Lopez-Quintana, Alfonso; Riera, Luis; Zerolo, Ignacio; Martinez-Bordiu, Cristóbal

    1981-06-01

    Three cases of severe disc variance and erosion of the Teflon-disc Beall mitral valve prosthesis (Models 103 and 104) are reported. In two patients, the Beall mitral valves were excised and replaced with two Björk-Shiley mitral valves. The remaining patient did not survive, and at autopsy, the lens was found at the aortic bifurcation level. Because of this potentially lethal complication, careful follow-up of patients with Beall mitral valve prostheses (Models 103 and 104) is recommended.

  5. Mitral valve disease—morphology and mechanisms

    PubMed Central

    Levine, Robert A.; Hagége, Albert A.; Judge, Daniel P.; Padala, Muralidhar; Dal-Bianco, Jacob P.; Aikawa, Elena; Beaudoin, Jonathan; Bischoff, Joyce; Bouatia-Naji, Nabila; Bruneval, Patrick; Butcher, Jonathan T.; Carpentier, Alain; Chaput, Miguel; Chester, Adrian H.; Clusel, Catherine; Delling, Francesca N.; Dietz, Harry C.; Dina, Christian; Durst, Ronen; Fernandez-Friera, Leticia; Handschumacher, Mark D.; Jensen, Morten O.; Jeunemaitre, Xavier P.; Le Marec, Hervé; Le Tourneau, Thierry; Markwald, Roger R.; Mérot, Jean; Messas, Emmanuel; Milan, David P.; Neri, Tui; Norris, Russell A.; Peal, David; Perrocheau, Maelle; Probst, Vincent; Pucéat, Michael; Rosenthal, Nadia; Solis, Jorge; Schott, Jean-Jacques; Schwammenthal, Ehud; Slaugenhaupt, Susan A.; Song, Jae-Kwan; Yacoub, Magdi H.

    2016-01-01

    Mitral valve disease is a frequent cause of heart failure and death. Emerging evidence indicates that the mitral valve is not a passive structure, but—even in adult life—remains dynamic and accessible for treatment. This concept motivates efforts to reduce the clinical progression of mitral valve disease through early detection and modification of underlying mechanisms. Discoveries of genetic mutations causing mitral valve elongation and prolapse have revealed that growth factor signalling and cell migration pathways are regulated by structural molecules in ways that can be modified to limit progression from developmental defects to valve degeneration with clinical complications. Mitral valve enlargement can determine left ventricular outflow tract obstruction in hypertrophic cardiomyopathy, and might be stimulated by potentially modifiable biological valvular–ventricular interactions. Mitral valve plasticity also allows adaptive growth in response to ventricular remodelling. However, adverse cellular and mechanobiological processes create relative leaflet deficiency in the ischaemic setting, leading to mitral regurgitation with increased heart failure and mortality. Our approach, which bridges clinicians and basic scientists, enables the correlation of observed disease with cellular and molecular mechanisms, leading to the discovery of new opportunities for improving the natural history of mitral valve disease. PMID:26483167

  6. Mitral valve disease--morphology and mechanisms.

    PubMed

    Levine, Robert A; Hagége, Albert A; Judge, Daniel P; Padala, Muralidhar; Dal-Bianco, Jacob P; Aikawa, Elena; Beaudoin, Jonathan; Bischoff, Joyce; Bouatia-Naji, Nabila; Bruneval, Patrick; Butcher, Jonathan T; Carpentier, Alain; Chaput, Miguel; Chester, Adrian H; Clusel, Catherine; Delling, Francesca N; Dietz, Harry C; Dina, Christian; Durst, Ronen; Fernandez-Friera, Leticia; Handschumacher, Mark D; Jensen, Morten O; Jeunemaitre, Xavier P; Le Marec, Hervé; Le Tourneau, Thierry; Markwald, Roger R; Mérot, Jean; Messas, Emmanuel; Milan, David P; Neri, Tui; Norris, Russell A; Peal, David; Perrocheau, Maelle; Probst, Vincent; Pucéat, Michael; Rosenthal, Nadia; Solis, Jorge; Schott, Jean-Jacques; Schwammenthal, Ehud; Slaugenhaupt, Susan A; Song, Jae-Kwan; Yacoub, Magdi H

    2015-12-01

    Mitral valve disease is a frequent cause of heart failure and death. Emerging evidence indicates that the mitral valve is not a passive structure, but--even in adult life--remains dynamic and accessible for treatment. This concept motivates efforts to reduce the clinical progression of mitral valve disease through early detection and modification of underlying mechanisms. Discoveries of genetic mutations causing mitral valve elongation and prolapse have revealed that growth factor signalling and cell migration pathways are regulated by structural molecules in ways that can be modified to limit progression from developmental defects to valve degeneration with clinical complications. Mitral valve enlargement can determine left ventricular outflow tract obstruction in hypertrophic cardiomyopathy, and might be stimulated by potentially modifiable biological valvular-ventricular interactions. Mitral valve plasticity also allows adaptive growth in response to ventricular remodelling. However, adverse cellular and mechanobiological processes create relative leaflet deficiency in the ischaemic setting, leading to mitral regurgitation with increased heart failure and mortality. Our approach, which bridges clinicians and basic scientists, enables the correlation of observed disease with cellular and molecular mechanisms, leading to the discovery of new opportunities for improving the natural history of mitral valve disease.

  7. Fracture and embolization of a Lillehei-Kaster mitral valve prosthesis disc: one case successfully operated.

    PubMed

    Pilichowski, P; Gaudin, P; Brichon, P Y; Neron, L; Wolf, J E; Machecourt, J; Latreille, R

    1987-12-01

    We report the fracture of the poppet of a Lillehei-Kaster prosthesis. A 40 years old man was operated upon for endocarditis of the mitral valve. A Lillehei-Kaster tilting disc valve was implanted. Three years later the disc fractured and the two parts escaped in the aorto-iliac axis. Emergency surgical procedure permitted implantation of a Wessex bioprosthesis and removal of the fragments with good results.

  8. Harken Caged-Disc Mitral Valve Replacement, 1969-1975: Analysis of Late Mortality, Thromboembolism, and Valve Failure

    PubMed Central

    Gray, Richard J.; Czer, Lawrence S.C.; Chaux, Aurelio; Sethna, Dhun; Derobertis, Michele; Raymond, Marjorie; Matloff, Jack M.

    1987-01-01

    We evaluated the long-term outcome of mitral valve replacement with a Harken caged-disc prosthesis for up to 11 years (range, 50 to 130 months; mean, 81 months) in 170 patients whose mean age was 55 years. The early (30-day) mortality was 11.2% (19 out of 170 patients). Late follow-up information was obtained for 144 (95%) of the 151 survivors. The actuarial survival was 57% at 5 years and 40% at 10 years. Overall mortality was associated with advanced age, male sex, an ischemic origin for the mitral valve disease, and nonuse of warfarin anticoagulation. Late deaths (n=59) were valve-related in 46%, cardiac but non-valve-related in 44%, and noncardiac in 10% of the cases. One thromboembolic event or more occurred in 41 patients (incidence, 5.7% per patient year), 14 of whom died (24% of the late deaths). All four patients who were not on warfarin, aspirin, or other antithrombotic therapy experienced thromboemboli. This complication was correlated with the nonuse of warfarin-type anticoagulation, with mitral regurgitation, and with late cardiac death. Mechanical prosthetic failure resulted in reoperation or death in 7.6% of the late survivors (1.5% per patient year). In 75 patients with normally functioning prostheses, the disc-to-sewing ring ratio was established by means of cinefluoroscopy (0.93 ± 0.04, mean ± 25D). Because of the high proportion of cardiac valve-related deaths (46%), the high incidence of late mortality due to thromboembolic events (24%), and the 7.6% incidence of reoperation or death resulting from mechanical valve failure, close follow-up with cinefluoroscopy and continued warfarin anticoagulation (alone or in combination with dipyridamole) are essential after mitral valve replacement with the Harken caged-disc prosthesis. (Texas Heart Institute Journal 1987; 14:411-417) Images PMID:15227298

  9. Mechanics of Actuated Disc Cutting

    NASA Astrophysics Data System (ADS)

    Dehkhoda, Sevda; Detournay, Emmanuel

    2017-02-01

    This paper investigates the mechanics of an actuated disc cutter with the objective of determining the average forces acting on the disc as a function of the parameters characterizing its motion. The specific problem considered is that of a disc cutter revolving off-centrically at constant angular velocity around a secondary axis rigidly attached to a cartridge, which is moving at constant velocity and undercutting rock at a constant depth. This model represents an idealization of a technology that has been implemented in a number of hard rock mechanical excavators with the goal of reducing the average thrust force to be provided by the excavation equipment. By assuming perfect conformance of the rock with the actuated disc as well as a prescribed motion of the disc (perfectly rigid machine), the evolution of the contact surface between the disc and the rock during one actuation of the disc can be computed. Coupled with simple cutter/rock interaction models that embody either a ductile or a brittle mode of fragmentation, these kinematical considerations lead to an estimate of the average force on the cartridge and of the partitioning of the energy imparted by the disc to the rock between the actuation mechanism of the disc and the translation of the cartridge on which the actuated disc is attached.

  10. A note on the critical flow to initiate closure of pivoting disc mitral valve prostheses.

    PubMed

    Reif, T H; Huffstutler, M C

    1985-01-01

    Newton's second law of motion for rotating bodies and potential flow theory is used to mathematically model the closing process of a pivoting disc prosthetic heart valve in mitral position. The model predicts closure to be dependent upon disc curvature, eccentricity, mass, diameter, density, opening angle and fluid properties. Experiments using two commercially available prostheses are shown to give good correlation with the theory for large opening angles. Divergence between theory and experiment occur at small opening angles because of the limitation of the potential flow assumption.

  11. Prosthetic Valve Dysfunction 35 Years after Mitral Valve Replacement with a Starr-Edwards Caged-disc Valve.

    PubMed

    Yokokawa, Tetsuro; Ohara, Takahiro; Takashio, Seiji; Sakamoto, Mari; Wada, Yuko; Nakamura, Kenji; Takahama, Hiroyuki; Amaki, Makoto; Hasegawa, Takuya; Sugano, Yasuo; Kanzaki, Hideaki; Yasuda, Satoshi; Ogawa, Hisao; Fujita, Tomoyuki; Kobayashi, Junjiro; Okamoto, Yoko; Matsuyama, Taka-Aki; Ishibashi-Ueda, Hatsue; Anzai, Toshihisa

    2016-01-01

    A 49-year-old man was admitted to our hospital with a chief complaint of dyspnea. He had a history of mitral valve replacement (MVR) with a Starr-Edwards (SE) caged-disc valve at the age of 14. Echocardiography revealed elevated trans-valvular pressure gradient of the mitral prosthetic valve with neither disk motion abnormality nor abnormal structure. Catheterization confirmed an elevation of the mean diastolic gradient of the mitral valve to 12.3 mmHg. Re-MVR was performed, and abnormal tissue attached to the cage of the valve and proliferating beneath the valve was observed. Histologic examination revealed them as fibrinous tissue and mild pannus proliferation, respectively. This rare case report focuses on long-term follow-up and the complication of a SE caged-disc valve. A SE caged-disc valve may become stenotic, only detected with a trans-valvular pressure gradient without any disk motion abnormality or abnormal structure during a prolonged follow-up period.

  12. Novel pathogenetic mechanisms and structural adaptations in ischemic mitral regurgitation.

    PubMed

    Silbiger, Jeffrey J

    2013-10-01

    Ischemic mitral regurgitation (MR) is a common complication of myocardial infarction thought to result from leaflet tethering caused by displacement of the papillary muscles that occurs as the left ventricle remodels. The author explores the possibility that left atrial remodeling may also play a role in the pathogenesis of ischemic MR, through a novel mechanism: atriogenic leaflet tethering. When ischemic MR is hemodynamically significant, the left ventricle compensates by dilating to preserve forward output using the Starling mechanism. Left ventricular dilatation, however, worsens MR by increasing the mitral valve regurgitant orifice, leading to a vicious cycle in which MR begets more MR. The author proposes that several structural adaptations play a role in reducing ischemic MR. In contrast to the compensatory effects of left ventricular enlargement, these may reduce, rather than increase, its severity. The suggested adaptations involve the mitral valve leaflets, the papillary muscles, the mitral annulus, and the left ventricular false tendons. This review describes the potential role each may play in reducing ischemic MR. Therapies that exploit these adaptations are also discussed.

  13. Comparison of animal discs used in disc research to human lumbar disc: torsion mechanics and collagen content.

    PubMed

    Showalter, Brent L; Beckstein, Jesse C; Martin, John T; Beattie, Elizabeth E; Espinoza Orías, Alejandro A; Schaer, Thomas P; Vresilovic, Edward J; Elliott, Dawn M

    2012-07-01

    Experimental measurement and normalization of in vitro disc torsion mechanics and collagen content for several animal species used in intervertebral disc research and comparing these with the human disc. To aid in the selection of appropriate animal models for disc research by measuring torsional mechanical properties and collagen content. There is lack of data and variability in testing protocols for comparing animal and human disc torsion mechanics and collagen content. Intervertebral disc torsion mechanics were measured and normalized by disc height and polar moment of inertia for 11 disc types in 8 mammalian species: the calf, pig, baboon, goat, sheep, rabbit, rat, and mouse lumbar discs, and cow, rat, and mouse caudal discs. Collagen content was measured and normalized by dry weight for the same discs except the rat and the mouse. Collagen fiber stretch in torsion was calculated using an analytical model. Measured torsion parameters varied by several orders of magnitude across the different species. After geometric normalization, only the sheep and pig discs were statistically different from human discs. Fiber stretch was found to be highly dependent on the assumed initial fiber angle. The collagen content of the discs was similar, especially in the outer annulus where only the calf and goat discs were statistically different from human. Disc collagen content did not correlate with torsion mechanics. Disc torsion mechanics are comparable with human lumbar discs in 9 of 11 disc types after normalization by geometry. The normalized torsion mechanics and collagen content of the multiple animal discs presented are useful for selecting and interpreting results for animal disc models. Structural organization of the fiber angle may explain the differences that were noted between species after geometric normalization.

  14. Shear Mechanics of the TMJ Disc

    PubMed Central

    Juran, C.M.; Dolwick, M.F.; McFetridge, P.S.

    2012-01-01

    The temporomandibular joint (TMJ) is a complex hinge and gliding joint that induces significant shear loads onto the fibrocartilage TMJ disc during jaw motion. The purpose of this study was to assess regional variation in the disc’s shear loading characteristics under physiologically relevant loads and to associate those mechanical findings with common clinical observations of disc fatigue and damage. Porcine TMJ discs were compressed between an axially translating bottom platen and a 2.5-cm-diameter indenter within a hydrated testing chamber. Discs were cyclically sheared at 0.5, 1, or 5 Hz to 1, 3, or 5% shear strain. Within the anterior and intermediate regions of the disc when sheared in the anteroposterior direction, both shear and compressive moduli experienced a significant decrease from instantaneous to steady state, while the posterior region’s compressive modulus decreased approximately 5%, and no significant loss of shear modulus was noted. All regions retained their shear modulus within 0.5% of instantaneous values when shear was applied in the mediolateral direction. The results of the disc’s regional shear mechanics suggest an observable and predictable link with the common clinical observation that the posterior region of the disc is most often the zone in which fatigue occurs, which may lead to disc damage and perforation. PMID:23166043

  15. Comparison of Animal Discs Used in Disc Research to Human Lumbar Disc: Torsion Mechanics and Collagen Content

    PubMed Central

    Showalter, Brent L.; Beckstein, Jesse C.; Martin, John T.; Beattie, Elizabeth E.; Orías, Alejandro A. Espinoza; Schaer, Thomas P.; Vresilovic, Edward J.; Elliott, Dawn M.

    2012-01-01

    Study Design Experimental measurement and normalization of in vitro disc torsion mechanics and collagen content for several animal species used in intervertebral disc research and comparing these to the human disc. Objective To aid in the selection of appropriate animal models for disc research by measuring torsional mechanical properties and collagen content. Summary of Background Data There is lack of data and variability in testing protocols for comparing animal and human disc torsion mechanics and collagen content. Methods Intervertebral disc torsion mechanics were measured and normalized by disc height and polar moment of inertia for 11 disc types in 8 mammalian species: the calf, pig, baboon, goat, sheep, rabbit, rat, and mouse lumbar, and cow, rat, and mouse caudal. Collagen content was measured and normalized by dry weight for the same discs except the rat and mouse. Collagen fiber stretch in torsion was calculated using an analytical model. Results Measured torsion parameters varied by several orders of magnitude across the different species. After geometric normalization, only the sheep and pig discs were statistically different from human. Fiber stretch was found to be highly dependent on the assumed initial fiber angle. The collagen content of the discs was similar, especially in the outer annulus where only the calf and goat discs were statistically different from human. Disc collagen content did not correlate with torsion mechanics. Conclusion Disc torsion mechanics are comparable to human lumbar discs in 9 of 11 disc types after normalization by geometry. The normalized torsion mechanics and collagen content of the multiple animal discs presented is useful for selecting and interpreting results for animal models of the disc. Structural composition of the disc, such as initial fiber angle, may explain the differences that were noted between species after geometric normalization. PMID:22333953

  16. Haemodynamic improvement of older, previously replaced mechanical mitral valves by removal of the subvalvular pannus in redo cardiac surgery.

    PubMed

    Kim, Jong Hun; Kim, Tae Youn; Choi, Jong Bum; Kuh, Ja Hong

    2017-01-01

    Patients requiring redo cardiac surgery for diseased heart valves other than mitral valves may show increased pressure gradients and reduced valve areas of previously placed mechanical mitral valves due to subvalvular pannus formation. We treated four women who had mechanical mitral valves inserted greater than or equal to 20 years earlier and who presented with circular pannus that protruded into the lower margin of the valve ring but did not impede leaflet motion. Pannus removal improved the haemodynamic function of the mitral valve.

  17. Mechanics of mitral valve edge-to-edge-repair and MitraClip procedure.

    PubMed

    Bhattacharya, Shamik; He, Zhaoming

    2015-01-01

    The edge-to-edge repair (ETER) technique has been used as a stand-alone procedure, or as a secondary procedure with ring annuloplasty for degenerative, functional mitral regurgitation, or for mitral regurgitation of other kinds of valvular etiologies. The percutaneous MitraClip technique based on ETER has been used in patients who are inoperable or at high surgical risk. However, adverse events such as residual mitral regurgitation, and clip detachment or fracture indicate that the mechanics underlying these procedures is not well understood. Therefore, current studies on mitral valve functionality and mechanics related to the ETER and MitraClip procedures are reviewed to improve the efficacy and safety of both procedures. Extensive in vivo, in vitro, and in silico studies related to ETER and MitraClip procedures along with MitraClip clinical trial results are presented and discussed herein. The ETER suture force and the mitral valve tissue mechanics and hemodynamics of each procedure are discussed. A quantitative understanding of the interplay of mitral valve components and as to biological response to the procedures remains challenging. Based on mitral valve mechanics, ETER or MitraClip therapy can be optimized to enhance repair efficacy and durability.

  18. Percutaneous implantation of CoreValve aortic prostheses in patients with a mechanical mitral valve.

    PubMed

    Bruschi, Giuseppe; De Marco, Federico; Oreglia, Jacopo; Colombo, Paola; Fratto, Pasquale; Lullo, Francesca; Paino, Roberto; Frigerio, Maria; Martinelli, Luigi; Klugmann, Silvio

    2009-11-01

    Concerns exist in the field of transcatheter aortic valve implantation regarding the treatment of patients with mechanical mitral valve for possible interference between the percutaneous aortic valve and the mechanical mitral prosthesis. We report our experience with percutaneous aortic valve implantation in 4 patients with severe aortic stenosis, previously operated on for mitral valve replacement with a mechanical prosthesis. All patients underwent uneventful percutaneous retrograde CoreValve implantation (CoreValve Inc, Irvine, CA). No deformation of the nitinol tubing of the prostheses (ie, neither distortion nor malfunction of the mechanical valve in the mitral position) occurred in any of the patients. All patients are alive and asymptomatic at a mean follow-up of 171 days.

  19. Comparison of dysfunction with mechanical and porcine mitral valve prostheses.

    PubMed

    Magilligan, D J; Oyama, C; Alam, M

    1985-09-01

    We reviewed the incidence of dysfunction of the Smeloff-Cutter mechanical prosthetic valve and the Hancock porcine prosthetic valve in the mitral position. The Smeloff-Cutter valve was implanted from 1966 to 1972; 107 patients were discharged from the hospital and were at risk for dysfunction. Follow-up averaged 10 +/- 0.7 years SD. The Hancock valve was implanted from 1971 through 1984; 473 patients were at risk and follow-up averaged 4.7 +/- 3.4 years SD. Dysfunction of the Smeloff-Cutter valve occurred as thrombosis with incomplete poppet opening in 13 patients. Dysfunction of the Hancock valve occurred as primary tissue failure in 47 patients. At 10 years the freedom from dysfunction of the Smeloff-Cutter valve was 84 +/- 5% SE and that for the Hancock valve was 71 +/- 4% SE (p greater than .06). The mortality associated with dysfunction of the Smeloff-Cutter valve was 46%; mortality associated with dysfunction of the Hancock valve was 15% (p less than .02). At 10 years the Hancock valve had a greater incidence of dysfunction than the Smeloff-Cutter valve but this difference was not statistically significant. The mortality associated with dysfunction of the Smeloff-Cutter valve, however, was three times that associated with dysfunction of the Hancock valve.

  20. Mitral Valve Mechanics Following Posterior Leaflet Patch Augmentation

    PubMed Central

    Rahmani, Azadeh; Rasmussen, Ann Q.; Honge, Jesper L.; Ostli, Bjorn; Levine, Robert A.; Hagège, Albert; Nygaard, Hans; Nielsen, Sten L.; Jensen, Morten O.

    2013-01-01

    Background and aim of the study Attention towards the optimization of mitral valve repair methods is increasing. Patch augmentation is one strategy used to treat functional ischemic mitral regurgitation (FIMR). The study aim was to investigate the force balance changes in specific chordae tendineae emanating from the posterior papillary muscle in a FIMR-simulated valve, following posterior leaflet patch augmentation. Methods Mitral valves were obtained from 12 pigs (body weight 80 kg). An in vitro test set-up simulating the left ventricle was used to hold the valves. The left ventricular pressure was regulated with water to simulate different static pressures during valve closure. A standardized oval pericardial patch (17 × 29 mm) was introduced into the posterior leaflet from mid P2 to the end of the P3 scallop. Dedicated miniature transducers were used to record the forces exerted on the chordae tendineae. Data were acquired before and after 12 mm posterior and 5 mm apical posterior papillary muscle displacement to simulate the effect from one of the main contributors of FIMR, before and after patch augmentation. Results The effect of displacing the posterior papillary muscle induced tethering on the intermediate chordae tendineae to the posterior leaflet, and resulted in a 39.8% force increase (p = 0.014). Posterior leaflet patch augmentation of the FIMR valve induced a 31.1% force decrease (p = 0.007). There was no difference in force between the healthy and the repaired valve simulations (p = 0.773). Conclusion Posterior leaflet patch augmentation significantly reduced the forces exerted on the intermediate chordae tendineae from the posterior papillary muscle following FIMR simulation. As changes in chordal tension lead to a redistribution of the total stress exerted on the valve, patch augmentation may have an adverse long-term influence on mitral valve function and remodeling. PMID:23610985

  1. Effect of collagen fibre orientation on intervertebral disc torsion mechanics.

    PubMed

    Yang, Bo; O'Connell, Grace D

    2017-07-21

    The intervertebral disc is a complex fibro-cartilaginous material, consisting of a pressurized nucleus pulposus surrounded by the annulus fibrosus, which has an angle-ply structure. Disc injury and degeneration are noted by significant changes in tissue structure and function, which significantly alters stress distribution and disc joint stiffness. Differences in fibre orientation are thought to contribute to changes in disc torsion mechanics. Therefore, the objective of this study was to evaluate the effect of collagen fibre orientation on internal disc mechanics under compression combined with axial rotation. We developed and validated a finite element model (FEM) to delineate changes in disc mechanics due to fibre orientation from differences in material properties. FEM simulations were performed with fibres oriented at [Formula: see text] throughout the disc (uniform by region and fibre layer). The initial model was validated by published experimental results for two load conditions, including [Formula: see text] axial compression and [Formula: see text] axial rotation. Once validated, fibre orientation was rotated by [Formula: see text] or [Formula: see text] towards the horizontal plane, resulting in a decrease in disc joint torsional stiffness. Furthermore, we observed that axial rotation caused a sinusoidal change in disc height and radial bulge, which may be beneficial for nutrient transport. In conclusion, including anatomically relevant fibre angles in disc joint FEMs is important for understanding stress distribution throughout the disc and will be important for understanding potential causes for disc injury. Future models will include regional differences in fibre orientation to better represent the fibre architecture of the native disc.

  2. Deterioration of Mechanical Properties of Discs in Chronically Inflamed TMJ

    PubMed Central

    Wang, X.D.; Cui, S.J.; Liu, Y.; Luo, Q.; Du, R.J.; Kou, X.X.; Zhang, J.N.; Zhou, Y.H.; Gan, Y.H.

    2014-01-01

    Temporomandibular joint (TMJ) discs frequently undergo degenerative changes in arthritis. However, the biomechanical properties of pathogenic discs remain to be explored. In this study, we evaluated the effects of chronic inflammation on the biomechanical properties of TMJ discs in rats. Chronic inflammation of TMJs was induced by double intra-articular injections of complete Freund’s adjuvant for 5 weeks, and biomechanical properties and ultrastructure of the discs were examined by mechanical testing, scanning electron microscopy, and transmission electron microscopy. The instantaneous compressive moduli of the anterior and posterior bands of discs in inflamed TMJs were decreased significantly compared with those in the control group. The instantaneous tensile moduli of the discs of inflamed TMJs also showed significant decreases in both the anterior-posterior and mesial-lateral directions. The relaxation moduli of the discs of inflamed TMJs showed nearly the same tendency as the instantaneous moduli. The surfaces of the discs of inflamed TMJs became rough and porous due to the loss of the superficial gel-like stratum, with many collagen fibers exposed and degradation of the sub-superficial collagen fibrils. Our results suggested that chronic inflammation of TMJ could lead to deterioration of mechanical properties and alteration of disc ultrastructure, which might contribute to TMJ disc displacement. PMID:25266714

  3. MECHANICAL DESIGN CRITERIA FOR INTERVERTEBRAL DISC TISSUE ENGINEERING

    PubMed Central

    Nerurkar, Nandan L.; Elliott, Dawn M.; Mauck, Robert L.

    2009-01-01

    Due to the inability of current clinical practices to restore function to degenerated intervertebral discs, the arena of disc tissue engineering has received substantial attention in recent years. Despite tremendous growth and progress in this field, translation to clinical implementation has been hindered by a lack of well-defined functional benchmarks. Because successful replacement of the disc is contingent upon replication of some or all of its complex mechanical behaviour, it is critically important that disc mechanics be well characterized in order to establish discrete functional goals for tissue engineering. In this review, the key functional signatures of the intervertebral disc are discussed and used to propose a series of native tissue benchmarks to guide the development of engineered replacement tissues. These benchmarks include measures of mechanical function under tensile, compressive and shear deformations for the disc and its substructures. In some cases, important functional measures are identified that have yet to be measured in the native tissue. Ultimately, native tissue benchmark values are compared to measurements that have been made on engineered disc tissues, identifying measures where functional equivalence was achieved, and others where there remain opportunities for advancement. Several excellent reviews exist regarding disc composition and structure, as well as recent tissue engineering strategies; therefore this review will remain focused on the functional aspects of disc tissue engineering. PMID:20080239

  4. Mechanisms for mechanical damage in the intervertebral disc annulus fibrosus.

    PubMed

    Iatridis, J C James C; ap Gwynn, Iolo

    2004-08-01

    Intervertebral disc degeneration results in disorganization of the laminate structure of the annulus that may arise from mechanical microfailure. Failure mechanisms in the annulus were investigated using composite lamination theory and other analyses to calculate stresses in annulus layers, interlaminar shear stress, and the region of stress concentration around a fiber break. Scanning electron microscopy (SEM) was used to evaluate failure patterns in the annulus and evaluate novel structural features of the disc tissue. Stress concentrations in the annulus due to an isolated fiber break were localized to approximately 5 microm away from the break, and only considered a likely cause of annulus fibrosus failure (i.e., radial tears in the annulus) under extreme loading conditions or when collagen damage occurs over a relatively large region. Interlaminar shear stresses were calculated to be relatively large, to increase with layer thickness (as reported with degeneration), and were considered to be associated with propagation of circumferential tears in the annulus. SEM analysis of intervertebral disc annulus fibrosus tissue demonstrated a clear laminate structure, delamination, matrix cracking, and fiber failure. Novel structural features noted with SEM also included the presence of small tubules that appear to run along the length of collagen fibers in the annulus and a distinct collagenous structure representative of a pericellular matrix in the nucleus region.

  5. Biomechanical evaluation of the pathophysiologic developmental mechanisms of mitral valve prolapse: effect of valvular morphologic alteration.

    PubMed

    Choi, Ahnryul; McPherson, David D; Kim, Hyunggun

    2016-05-01

    Mitral valve prolapse (MVP) refers to an excessive billowing of the mitral valve (MV) leaflets across the mitral annular plane into the left atrium during the systolic portion of the cardiac cycle. The underlying mechanisms for the development of MVP and mitral regurgitation in association with MV tissue remodeling are still unclear. We performed computational MV simulations to investigate the pathophysiologic developmental mechanisms of MVP. A parametric MV geometry model was utilized for this study. Posterior leaflet enlargement and posterior chordal elongation models were created by adjusting the geometry of the posterior leaflet and chordae, respectively. Dynamic finite element simulations of MV function were performed over the complete cardiac cycle. Computational simulations demonstrated that enlarging posterior leaflet area increased large stress concentration in the posterior leaflets and chordae, and posterior chordal elongation decreased leaflet coaptation. When MVP was accompanied by both posterior leaflet enlargement and chordal elongation simultaneously, the posterior leaflet was exposed to extremely large prolapse with a substantial lack of leaflet coaptation. These data indicate that MVP development is closely related to tissue alterations of the leaflets and chordae. This biomechanical evaluation strategy can help us better understand the pathophysiologic developmental mechanisms of MVP.

  6. Mechanical haemolytic anaemia after valve repair operations for non-rheumatic mitral regurgitation.

    PubMed Central

    Warnes, C; Honey, M; Brooks, N; Davies, J; Gorman, A; Parker, N

    1980-01-01

    Two cases are described in which severe mechanical haemolytic anaemia developed shortly after operation for repair of non-rheumatic mitral regurgitation. One patient had a "floppy" valve and the other cleft mitral leaflets, and both had chordal rupture. In both there was residual regurgitation after repair though in one this was initially only trivial. Clinically manifest haemolysis ceased after replacement of the valve by a frame-mounted xenograft. There are two previously reported cases in which haemolytic anaemia followed an unsuccessful mitral valve repair operation. Subclinical haemolysis or mild haemolytic anaemia may occur with unoperated valve lesions, but hitherto frank haemolytic anaemia has been observed only when turbulent blood flow is associated with the presence of a prosthetic valve or patch of prosthetic fabric. In these four cases, however, polyester or Teflon sutures were the only foreign material, and it is suggested that when these are used for the repair of leaflets, particularly in non-rheumatic mitral valve disease, they may increase the damaging effect of turbulence on circulating red blood cells. PMID:7426198

  7. Molecular Mechanisms of Biological Aging in Intervertebral Discs

    PubMed Central

    Vo, Nam V.; Hartman, Robert A.; Patil, Prashanti R.; Risbud, Makarand V.; Kletsas, Dimitris; Iatridis, James C.; Hoyland, Judith A.; Le Maitre, Christine L.; Sowa, Gwendolyn A.; Kang, James D.

    2016-01-01

    Advanced age is the greatest risk factor for the majority of human ailments, including spine-related chronic disability and back pain, which stem from age-associated intervertebral disc degeneration (IDD). Given the rapid global rise in the aging population, understanding the biology of intervertebral disc aging in order to develop effective therapeutic interventions to combat the adverse effects of aging on disc health is now imperative. Fortunately, recent advances in aging research have begun to shed light on the basic biological process of aging. Here we review some of these insights and organize the complex process of disc aging into three different phases to guide research efforts to understand the biology of disc aging. The objective of this review is to provide an overview of the current knowledge and the recent progress made to elucidate specific molecular mechanisms underlying disc aging. In particular, studies over the last few years have uncovered cellular senescence and genomic instability as important drivers of disc aging. Supporting evidence comes from DNA repair-deficient animal models that show increased disc cellular senescence and accelerated disc aging. Additionally, stress-induced senescent cells have now been well documented to secrete catabolic factors, which can negatively impact the physiology of neighboring cells and ECM. These along with other molecular drivers of aging are reviewed in depth to shed crucial insights into the underlying mechanisms of age-related disc degeneration. We also highlight molecular targets for novel therapies and emerging candidate therapeutics that may mitigate age-associated IDD. PMID:26890203

  8. Left ventricular mechanics in isolated mild mitral stenosis: a three dimensional speckle tracking study.

    PubMed

    Poyraz, Esra; Öz, Tuğba Kemaloğlu; Zeren, Gönül; Güvenç, Tolga Sinan; Dönmez, Cevdet; Can, Fatma; Güvenç, Rengin Çetin; Dayı, Şennur Ünal

    2017-03-11

    In a fraction of patients with mild mitral stenosis, left ventricular systolic function deteriorates despite the lack of hemodynamic load imposed by the dysfunctioning valve. Neither the predisposing factors nor the earlier changes in left ventricular contractility were understood adequately. In the present study we aimed to evaluate left ventricular mechanics using three-dimensional (3D) speckle tracking echocardiography. A total of 31 patients with mild rheumatic mitral stenosis and 27 healthy controls were enrolled to the study. All subjects included to the study underwent echocardiographic examination to collect data for two- and three-dimensional speckle-tracking based stain, twist angle and torsion measurements. Data was analyzed offline with a echocardiographic data analysis software. Patients with rheumatic mild MS had lower global longitudinal (p < 0.001) circumferential (p = 0.02) and radial (p < 0.01) strain compared to controls, despite ejection fraction was similar for both groups [(p = 0.45) for three dimensional and (p = 0.37) for two dimensional measurement]. While the twist angle was not significantly different between groups (p = 0.11), left ventricular torsion was significantly higher in mitral stenosis group (p = 0.03). All strain values had a weak but significant positive correlation with mitral valve area measured with planimetry. Subclinical left ventricular systolic dysfunction develops at an early stage in rheumatic mitral stenosis. Further work is needed to elucidate patients at risk for developing overt systolic dysfunction.

  9. Epicardial catheter ablation of ventricular tachycardia in no entry left ventricle: mechanical aortic and mitral valves.

    PubMed

    Soejima, Kyoko; Nogami, Akihiko; Sekiguchi, Yukio; Harada, Tomoo; Satomi, Kazuhiro; Hirose, Takeshi; Ueda, Akiko; Miwa, Yousuke; Sato, Toshiaki; Nishio, Satoru; Shirai, Yasuhiro; Kowase, Shinya; Murakoshi, Nobuyuki; Kunugi, Shinobu; Murata, Hiroshige; Nitta, Takashi; Aonuma, Kazutaka; Yoshino, Hideaki

    2015-04-01

    In patients with mechanical aortic and mitral valves and left ventricular tachycardia, catheter ablation may be prevented by limited access to the left ventricle. In our series of 6 patients, 2 patients underwent direct surgical ablation and 4 underwent epicardial catheter ablation via a pericardial window. All patients had abnormal low voltage areas with fractionated or delayed isolated potentials on the apical epicardium. Most of the ventricular tachycardias were targeted by pace mapping. Sites with a good pace match or abnormal electrograms were ablated using an irrigated radiofrequency ablation catheter. A microscopic pathological evaluation of the resected tissue from 2 of the open-heart ablation patients revealed dense fibrosis on the epicardium compared with the endocardium, supporting the feasibility of an epicardial ablation for the ventricular tachycardia. Epicardial catheter ablation of ventricular tachycardia is a potentially useful therapy in patients who have mechanical aortic and mitral valves. © 2015 American Heart Association, Inc.

  10. Mechanics of the mitral valve: a critical review, an in vivo parameter identification, and the effect of prestrain.

    PubMed

    Rausch, Manuel K; Famaey, Nele; Shultz, Tyler O'Brien; Bothe, Wolfgang; Miller, D Craig; Kuhl, Ellen

    2013-10-01

    Alterations in mitral valve mechanics are classical indicators of valvular heart disease, such as mitral valve prolapse, mitral regurgitation, and mitral stenosis. Computational modeling is a powerful technique to quantify these alterations, to explore mitral valve physiology and pathology, and to classify the impact of novel treatment strategies. The selection of the appropriate constitutive model and the choice of its material parameters are paramount to the success of these models. However, the in vivo parameters values for these models are unknown. Here, we identify the in vivo material parameters for three common hyperelastic models for mitral valve tissue, an isotropic one and two anisotropic ones, using an inverse finite element approach. We demonstrate that the two anisotropic models provide an excellent fit to the in vivo data, with local displacement errors in the sub-millimeter range. In a complementary sensitivity analysis, we show that the identified parameter values are highly sensitive to prestrain, with some parameters varying up to four orders of magnitude. For the coupled anisotropic model, the stiffness varied from 119,021 kPa at 0 % prestrain via 36 kPa at 30 % prestrain to 9 kPa at 60 % prestrain. These results may, at least in part, explain the discrepancy between previously reported ex vivo and in vivo measurements of mitral leaflet stiffness. We believe that our study provides valuable guidelines for modeling mitral valve mechanics, selecting appropriate constitutive models, and choosing physiologically meaningful parameter values. Future studies will be necessary to experimentally and computationally investigate prestrain, to verify its existence, to quantify its magnitude, and to clarify its role in mitral valve mechanics.

  11. Mechanical dyssynchrony and deformation imaging in patients with functional mitral regurgitation

    PubMed Central

    Rosa, Isabella; Marini, Claudia; Stella, Stefano; Ancona, Francesco; Spartera, Marco; Margonato, Alberto; Agricola, Eustachio

    2016-01-01

    Chronic functional mitral regurgitation (FMR) is a frequent finding of ischemic heart disease and dilated cardiomyopathy (DCM), associated with unfavourable prognosis. Several pathophysiologic mechanisms are involved in FMR, such as annular dilatation and dysfunction, left ventricle (LV) remodeling, dysfunction and dyssynchrony, papillary muscles displacement and dyssynchrony. The best therapeutic choice for FMR is still debated. When optimal medical treatment has already been set, a further option for cardiac resynchronization therapy (CRT) and/or surgical correction should be considered. CRT is able to contrast most of the pathophysiologic determinants of FMR by minimizing LV dyssynchrony through different mechanisms: Increasing closing forces, reducing tethering forces, reshaping annular geometry and function, correcting diastolic MR. Deformation imaging in terms of two-dimensional speckle tracking has been validated for LV dyssynchrony assessment. Radial speckle tracking and three-dimensional strain analysis appear to be the best methods to quantify intraventricular delay and to predict CRT-responders. Speckle-tracking echocardiography in patients with mitral valve regurgitation has been usually proposed for the assessment of LV and left atrial function. However it has also revealed a fundamental role of intraventricular dyssynchrony in determining FMR especially in DCM, rather than in ischemic cardiomyopathy in which MR severity seems to be more related to mitral valve deformation indexes. Furthermore speckle tracking allows the assessment of papillary muscle dyssynchrony. Therefore this technique can help to identify optimal candidates to CRT that will probably demonstrate a reduction in FMR degree and thus will experience a better outcome. PMID:26981211

  12. Mechanical dyssynchrony and deformation imaging in patients with functional mitral regurgitation.

    PubMed

    Rosa, Isabella; Marini, Claudia; Stella, Stefano; Ancona, Francesco; Spartera, Marco; Margonato, Alberto; Agricola, Eustachio

    2016-02-26

    Chronic functional mitral regurgitation (FMR) is a frequent finding of ischemic heart disease and dilated cardiomyopathy (DCM), associated with unfavourable prognosis. Several pathophysiologic mechanisms are involved in FMR, such as annular dilatation and dysfunction, left ventricle (LV) remodeling, dysfunction and dyssynchrony, papillary muscles displacement and dyssynchrony. The best therapeutic choice for FMR is still debated. When optimal medical treatment has already been set, a further option for cardiac resynchronization therapy (CRT) and/or surgical correction should be considered. CRT is able to contrast most of the pathophysiologic determinants of FMR by minimizing LV dyssynchrony through different mechanisms: Increasing closing forces, reducing tethering forces, reshaping annular geometry and function, correcting diastolic MR. Deformation imaging in terms of two-dimensional speckle tracking has been validated for LV dyssynchrony assessment. Radial speckle tracking and three-dimensional strain analysis appear to be the best methods to quantify intraventricular delay and to predict CRT-responders. Speckle-tracking echocardiography in patients with mitral valve regurgitation has been usually proposed for the assessment of LV and left atrial function. However it has also revealed a fundamental role of intraventricular dyssynchrony in determining FMR especially in DCM, rather than in ischemic cardiomyopathy in which MR severity seems to be more related to mitral valve deformation indexes. Furthermore speckle tracking allows the assessment of papillary muscle dyssynchrony. Therefore this technique can help to identify optimal candidates to CRT that will probably demonstrate a reduction in FMR degree and thus will experience a better outcome.

  13. Mechanism of Microbubble Growth at Mitral Mechanical Heart Valve (MHV) Closure

    NASA Astrophysics Data System (ADS)

    Rambod, Edmond; Beizaie, Masoud; Shusser, Michael; Gharib, Morteza

    1999-11-01

    The growth mechanism of microbubbles at mitral MHV closure has been experimentally studied. In the heart, some of the tiny bubbles grow explosively and form larger and persistent bubbles. An experimental set-up was designed to allow the passage of micron-size bubbles through an 80 micron-wide slot, simulating a typical gap between the housing ring and the occluders in MHV. The bubbles were generated using an air-liquid dispenser and were delivered to the system via a 250 micron-diameter hypedermic needle positioned vertically near the slot. A solenoid valve was used to deliver a 10cc volume of liquid in 25ms time through the slot. High-speed imaging was used to study the impact of flow through the slot on bubble growth. The velocity of liquid through the slot was assessed to be in the range of 12-15 m/s. Our observations confirmed the rapid and drastic growth of microbubbles following their passage through the narrow slot, due to pressure drop. Vortices, which were induced by flow separation on the downstream of the slot, caused the grown bubbles to shatter and form more stable bubbles.

  14. Characterizing thermal sweeping: a rapid disc dispersal mechanism

    NASA Astrophysics Data System (ADS)

    Owen, James E.; Hudoba de Badyn, Mathias; Clarke, Cathie J.; Robins, Luke

    2013-12-01

    We consider the properties of protoplanetary discs that are undergoing inside-out clearing by photoevaporation. In particular, we aim to characterize the conditions under which a protoplanetary disc may undergo `thermal sweeping', a rapid (≲104 years) disc destruction mechanism proposed to occur when a clearing disc reaches sufficiently low surface density at its inner edge and where the disc is unstable to runaway penetration by the X-rays. We use a large suite of 1D radiation-hydrodynamic simulations to probe the observable parameter space, which is unfeasible in higher dimensions. These models allow us to determine the surface density at which thermal sweeping will take over the disc's evolution and to evaluate this critical surface density as a function of X-ray luminosity, stellar mass and inner hole radius. We find that this critical surface density scales linearly with X-ray luminosity, increases with inner hole radius and decreases with stellar mass, and we develop an analytic model that reproduces these results. This surface density criterion is then used to determine the evolutionary state of protoplanetary discs at the point that they become unstable to destruction by thermal sweeping. We find that transition discs created by photoevaporation will undergo thermal sweeping when their inner holes reach 20-40 au, implying that transition discs with large holes and no accretion (which were previously a predicted outcome of the later stages of all flavours of the photoevaporation model) will not form. Thermal sweeping thus avoids the production of large numbers of large, non-accreting holes (which are not observed) and implies that the majority of holes created by photoevaporation should still be accreting. We emphasize that the surface density criteria that we have developed apply to all situations where the disc develops an inner hole that is optically thin to X-rays. It thus applies not only to the case of holes originally created by photoevaporation but

  15. Research on anti crack mechanism of bionic coupling brake disc

    NASA Astrophysics Data System (ADS)

    Shi, Lifeng; Yang, Xiao; Zheng, Lingnan; Wu, Can; Ni, Jing

    2017-09-01

    According to the biological function of fatigue resistance possessed by biology, this study designed a Bionic Coupling Brake Disc (BCBD) which can inhibit crack propagation as the result of improving fatigue property. Thermal stress field of brake disc was calculated under emergency working condition, and circumferential and radial stress field which lead to fatigue failure of brake disc were investigated simultaneously. Results showed that the maximum temperature of surface reached 890°C and the maximum residual tensile stress was 207 Mpa when the initial velocity of vehicle was 200 km/h. Based on the theory of elastic plastic fracture mechanics, the crack opening displacement and the crack front J integrals of the BCBD and traditional brake disc (TBD) with pre-cracking were calculated, and the strength of crack front was compared. Results revealed the growth behavior of fatigue crack located on surface of brake disc, and proved the anti fatigue resistance of BCBD was better, and the strength of crack resistance of BCBD was much stronger than that of TBD. This simulation research provided significant references for optimization and manufacturing of BCBD.

  16. Do Turkish patients with lumbar disc herniation know body mechanics?

    PubMed

    Topcu, Sacide Yildizeli

    2017-01-01

    Most common and important cause of the low back pain is lumbar disc herniation. Patients with lumbar disc herniation face with difficulties during daily activities due to the reduction of physical functions. In order to maintain daily activities without pain and discomfort, the patients should be informed about proper positions and body mechanics. The aim of the study was to determine the knowledge and the applications of the patients with lumbar disc herniation about body mechanics. This descriptive study was conducted with 75 patients with lumbar disc herniation in Edirne, Turkey. The population consisted of 75 patients who accepted to participate in the study. In the collection of data the questionnaire, which was developed according to literature by the researcher, was used. Descriptive statistics, student t-test, variance and correlation analysis were used for assessment of the data. The significance level was accepted at 0.05. It was found that 53.3% of the patients experienced awful/very severe pain. and there were some points that the patients have enough information about; mobilisation, standing, carrying the goods, leaning back while sitting, leaning somewhere while standing, getting support from the chair when standing up, avoiding sudden position changes, changing feet frequently while standing. It was detected that a statistical relation between educational level and knowledge about body mechanics exists. This study shows that individuals with lumbar disc herniation have not enough information about body mechanics and they experienced long-term severe pain. Nurses and other health care workers have important role in explaining the importance of body mechanics to the patients and should encourage them to use that in daily life.

  17. A novel left heart simulator for the multi-modality characterization of native mitral valve geometry and fluid mechanics.

    PubMed

    Rabbah, Jean-Pierre; Saikrishnan, Neelakantan; Yoganathan, Ajit P

    2013-02-01

    Numerical models of the mitral valve have been used to elucidate mitral valve function and mechanics. These models have evolved from simple two-dimensional approximations to complex three-dimensional fully coupled fluid structure interaction models. However, to date these models lack direct one-to-one experimental validation. As computational solvers vary considerably, experimental benchmark data are critically important to ensure model accuracy. In this study, a novel left heart simulator was designed specifically for the validation of numerical mitral valve models. Several distinct experimental techniques were collectively performed to resolve mitral valve geometry and hemodynamics. In particular, micro-computed tomography was used to obtain accurate and high-resolution (39 μm voxel) native valvular anatomy, which included the mitral leaflets, chordae tendinae, and papillary muscles. Three-dimensional echocardiography was used to obtain systolic leaflet geometry. Stereoscopic digital particle image velocimetry provided all three components of fluid velocity through the mitral valve, resolved every 25 ms in the cardiac cycle. A strong central filling jet (V ~ 0.6 m/s) was observed during peak systole with minimal out-of-plane velocities. In addition, physiologic hemodynamic boundary conditions were defined and all data were synchronously acquired through a central trigger. Finally, the simulator is a precisely controlled environment, in which flow conditions and geometry can be systematically prescribed and resultant valvular function and hemodynamics assessed. Thus, this work represents the first comprehensive database of high fidelity experimental data, critical for extensive validation of mitral valve fluid structure interaction simulations.

  18. A Novel Left Heart Simulator for the Multi-modality Characterization of Native Mitral Valve Geometry and Fluid Mechanics

    PubMed Central

    Rabbah, Jean-Pierre; Saikrishnan, Neelakantan; Yoganathan, Ajit P.

    2012-01-01

    Numerical models of the mitral valve have been used to elucidate mitral valve function and mechanics. These models have evolved from simple two-dimensional approximations to complex three-dimensional fully coupled fluid structure interaction models. However, to date these models lack direct one-to-one experimental validation. As computational solvers vary considerably, experimental benchmark data are critically important to ensure model accuracy. In this study, a novel left heart simulator was designed specifically for the validation of numerical mitral valve models. Several distinct experimental techniques were collectively performed to resolve mitral valve geometry and hemodynamics. In particular, micro-computed tomography was used to obtain accurate and high-resolution (39 µm voxel) native valvular anatomy, which included the mitral leaflets, chordae tendinae, and papillary muscles. Threedimensional echocardiography was used to obtain systolic leaflet geometry for direct comparison of resultant leaflet kinematics. Stereoscopic digital particle image velocimetry provided all three components of fluid velocity through the mitral valve, resolved every 25 ms in the cardiac cycle. A strong central filling jet was observed during peak systole, with minimal out-of-plane velocities (V~0.6m/s). In addition, physiologic hemodynamic boundary conditions were defined and all data were synchronously acquired through a central trigger. Finally, the simulator is a precisely controlled environment, in which flow conditions and geometry can be systematically prescribed and resultant valvular function and hemodynamics assessed. Thus, these data represent the first comprehensive database of high fidelity experimental data, critical for extensive validation of mitral valve fluid structure interaction simulations. PMID:22965640

  19. Cardiogenic unilateral pulmonary oedema in an infant with severe residual mitral regurgitation.

    PubMed

    Joong, Anna; Lai, Wyman W; Ferris, Anne

    2017-01-01

    An infant with residual severe mitral regurgitation following mitral commissurotomy developed cardiogenic unilateral pulmonary oedema and subsegmental atelectasis that resolved with mechanical mitral valve replacement.

  20. Effects of suture position on left ventricular fluid mechanics under mitral valve edge-to-edge repair.

    PubMed

    Du, Dongxing; Jiang, Song; Wang, Ze; Hu, Yingying; He, Zhaoming

    2014-01-01

    Mitral valve (MV) edge-to-edge repair (ETER) is a surgical procedure for the correction of mitral valve regurgitation by suturing the free edge of the leaflets. The leaflets are often sutured at three different positions: central, lateral and commissural portions. To study the effects of position of suture on left ventricular (LV) fluid mechanics under mitral valve ETER, a parametric model of MV-LV system during diastole was developed. The distribution and development of vortex and atrio-ventricular pressure under different suture position were investigated. Results show that the MV sutured at central and lateral in ETER creates two vortex rings around two jets, compared with single vortex ring around one jet of the MV sutured at commissure. Smaller total orifices lead to a higher pressure difference across the atrio-ventricular leaflets in diastole. The central suture generates smaller wall shear stresses than the lateral suture, while the commissural suture generated the minimum wall shear stresses in ETER.

  1. Prediction of glycosaminoglycan synthesis in intervertebral disc under mechanical loading.

    PubMed

    Gao, Xin; Zhu, Qiaoqiao; Gu, Weiyong

    2016-09-06

    The loss of glycosaminoglycan (GAG) content is a major biochemical change during intervertebral disc (IVD) degeneration. Abnormal mechanical loading is one of the major factors causing disc degeneration. In this study, a multiscale mathematical model was developed to quantify the effect of mechanical loading on GAG synthesis. This model was based on a recently developed cell volume dependent GAG synthesis theory that predicts the variation of GAG synthesis rate of a cell under the influence of mechanical stimuli, and the biphasic theory that describes the deformation of IVD under mechanical loading. The GAG synthesis (at the cell level) was coupled with the mechanical loading (at the tissue level) via a cell-matrix unit approach which established a relationship between the variation of cell dilatation and the local tissue dilatation. This multiscale mathematical model was used to predict the effect of static load (creep load) on GAG synthesis in bovine tail discs. The predicted results are in the range of experimental results. This model was also used to investigate the effect of static (0.2MPa) and diurnal loads (0.1/0.3MPa and 0.15/0.25MPa in 12/12 hours shift with an average of 0.2MPa over a cycle) on GAG synthesis. It was found that static load and diurnal loads have different effects on GAG synthesis in a diurnal cycle, and the diurnal load effects depend on the amplitude of the load. The model is important to understand the effect of mechanical loading at the tissue level on GAG synthesis at the cellular level, as well as to optimize the mechanical loading in growing engineered tissue. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Clinical and necropsy observations early after simultaneous replacement of the mitral and aortic valves.

    PubMed

    Roberts, W C; Sullivan, M F

    1986-11-15

    Clinical and necropsy findings are described in 54 patients, aged 25 to 83 years (mean 53), who died within 60 days of simultaneous replacements of both mitral and aortic valves. The patients were separated into 4 groups on the basis of the presence of stenosis (with or without associated regurgitation) or pure regurgitation of each valve: 30 patients (56%) had combined mitral and aortic valve stenosis; 12 patients (22%) had mitral stenosis and pure aortic regurgitation; 8 patients (15%) had pure regurgitation of both valves; and 4 patients (7%) had pure aortic regurgitation and mitral stenosis. Necropsy examination in the 54 patients disclosed a high frequency (48%) of anatomic evidence of interference to poppet or disc movement in either the mitral or aortic valve position or both. Anatomic evidence of interference to movement of a poppet or disc in the aortic valve position was twice as common as anatomic evidence of interference to poppet or disc movement in the mitral position. Interference to poppet movement is attributable to the prosthesis's being too large for the ascending aorta or left ventricular cavity in which it resided. The ascending aorta is infrequently enlarged in patients with combined mitral and aortic valve dysfunction irrespective of whether the aortic valve is stenotic or purely regurgitant. Likewise, the left ventricular cavity is usually not dilated in patients with combined mitral and aortic valve stenosis, the most common indication for replacement of both left-sided cardiac valves. Of the 54 patients, 12 (22%) had 1 mechanical and 1 bioprosthesis inserted. It is recommended that both substitute valves should be mechanical prostheses or both should be bioprostheses.

  3. Percutaneous Treatment of Herniated Lumbar Discs with Ozone: Investigation of the Mechanisms of Action.

    PubMed

    Murphy, Kieran; Elias, Gavin; Steppan, Jim; Boxley, Chett; Balagurunathan, Kuberan; Victor, Xylophone; Meaders, Thomas; Muto, Mario

    2016-08-01

    To elucidate the mechanism of action of intradiscal oxygen-ozone therapy for herniated intervertebral disc therapy. Ozone's mechanism of action was investigated using 3 approaches: mathematical models of intervertebral disc space to explore the relationship between disc pressure and volume; ozonolysis experiments using glycosaminoglycans (GAGs) from a Chinese hamster ovary cell line that were similar in composition to GAGs found in human nucleus pulposus; and experiments in which live Yucatan miniature pigs received various concentrations of percutaneous, image-guided intradiscal oxygen-ozone treatment and were examined (after sacrifice) with histology and semiquantitative analysis of disc cytokine concentrations. Engineering calculations support observations that a small (6%) disc volume reduction can result in considerable (9.84%) intradiscal pressure reduction. Porcine disc histology and Chinese hamster ovary GAG ozonolysis results showed that administered ozone reacted with and fragmented disc proteoglycans, reducing disc volume through disc dehydration. Cytokine analysis of porcine discs found that each of 4 cytokines measured (interleukin [IL]-1β, IL-6, IL-8, and tumor necrosis factor α) increased in concentration after 2 wt% ozone treatment. Oxygen-ozone therapy breaks down proteoglycan GAGs that maintain disc osmotic pressure, dehydrating the nucleus pulposus and reducing intervertebral disc volume. This is likely a primary mechanism by which ozone relieves nerve root compression and alleviates herniated disc-related pain. Additionally, 2 wt% ozone appears to interact with intradiscal cytokines, generating an antiinflammatory response that may contribute to symptom improvement. Copyright © 2016 SIR. Published by Elsevier Inc. All rights reserved.

  4. Transfemoral implantation of CoreValve Evolut-R aortic prosthesis in patient with prior ball-cage mechanical mitral valve prosthesis.

    PubMed

    Maluenda, Gabriel; Caorsi, Carlos; Baeza, Cristian

    2016-06-01

    Transcatheter aortic valve replacement remains challenge in patients with ball-cage-type mechanical valve in mitral position. Potential under-expansion of the percutaneous valve and interaction between the mitral ball-cage mechanical valve tilted towards the left ventricular outflow tract and the percutaneous valve adds risk during and after implantation. We report a successful implantation of the novel CoreValve Evolut-R self-expanding in a patient with severe aortic stenosis and a mitral Starr-Edwards mechanical valve implanted 28years ago.

  5. Discs of mammalian rod photoreceptors form through the membrane evagination mechanism

    PubMed Central

    Ding, Jin-Dong; Salinas, Raquel Y.

    2015-01-01

    Photoreceptor discs are membrane organelles harboring components of the visual signal transduction pathway. The mechanism by which discs form remains enigmatic and is the subject of a major controversy. Classical studies suggest that discs are formed as serial plasma membrane evaginations, whereas a recent alternative postulates that discs, at least in mammalian rods, are formed through intracellular vesicular fusion. We evaluated these models in mouse rods using methods that distinguish between the intracellular vesicular structures and plasma membrane folds independently of their appearance in electron micrographs. The first differentiated membranes exposed to the extracellular space from intracellular membranes; the second interrogated the orientation of protein molecules in new discs. Both approaches revealed that new discs are plasma membrane evaginations. We further demonstrated that vesiculation and plasma membrane enclosure at the site of new disc formation are artifacts of tissue fixation. These data indicate that all vertebrate photoreceptors use the evolutionary conserved membrane evagination mechanism to build their discs. PMID:26527746

  6. Shock absorption in lumbar disc prosthesis: a preliminary mechanical study.

    PubMed

    LeHuec, J C; Kiaer, T; Friesem, T; Mathews, H; Liu, M; Eisermann, L

    2003-08-01

    Lumbar disc prostheses have been used in treating symptomatic degenerative disc diseases. A few prostheses of the ball-socket design are currently available for clinical use, the joint mechanism being materialized either with a hard polymer core or a metal-to-metal couple. Other prostheses of "shock absorber" design were not available at the time of the study. The objective of this work was to establish whether there was a difference in the shock absorption capacity between a device having an ultra-high-molecular-weight polyethylene center core and a device having a metal-on-metal bearing. Vibration and shock loading were applied to two lumbar total disc prostheses: PRODISC, manufactured by Spine Solutions, and MAVERICK Total Disc Replacement, manufactured by Medtronic Sofamor Danek. The shock absorption capacity of the device was evaluated by comparing the input and the output force measurements. The disc prosthesis was mounted onto a test apparatus. Each side of the device was equipped with a force sensor. The input shock load and the output resulting forces were simultaneously measured and recorded. The loading force pattern included 1). a static preload of 350 N plus an oscillating vibration of 100 N with frequency sweeping from 0 to 100 Hz and 2). a sudden shock load of 250 N applied over a 0.1-second interval. Both input and output signal data were processed and were transformed into their frequency spectrums. The vibration and shock transmissibility of the device, defined as the ratio of the output spectrum over the input spectrum, were calculated in sweeping the frequency from 0 to 100 Hz. The phase deviation was calculated to characterize the shock absorber effects. For both tested devices under vibration and shock loading, the phase angle displacement between the input and the output signals was 10 degrees. Under oscillating vibration loading, both tested devices had a transmission ratio higher than 99.8%. Over the frequency interval 1-100 Hz, the

  7. Bench Models for Assessing the Mechanics of Mitral Valve Repair and Percutaneous Surgery.

    PubMed

    Siefert, Andrew W; Siskey, Ryan L

    2015-06-01

    Rapid preclinical evaluations of mitral valve (MV) mechanics are currently best facilitated by bench models of the left ventricle (LV). This review aims to provide a comprehensive assessment of these models to aid interpretation of their resulting data, inform future experimental evaluations, and further the translation of results to procedure and device development. For this review, two types of experimental bench models were evaluated. Rigid LV models were characterized as fluid-mechanical systems capable of testing explanted MVs under static and or pulsatile left heart hemodynamics. Passive LV models were characterized as explanted hearts whose left side is placed in series with a static or pulsatile flow-loop. In both systems, MV function and mechanics can be quantitatively evaluated. Rigid and passive LV models were characterized and evaluated. The materials and methods involved in their construction, function, quantitative capabilities, and disease modeling were described. The advantages and disadvantages of each model are compared to aid the interpretation of their resulting data and inform future experimental evaluations. Repair and percutaneous studies completed in these models were additionally summarized with perspective on future advances discussed. Bench models of the LV provide excellent platforms for quantifying MV repair mechanics and function. While exceptional work has been reported, more research and development is necessary to improve techniques and devices for repair and percutaneous surgery. Continuing efforts in this field will significantly contribute to the further development of procedures and devices, predictions of long-term performance, and patient safety.

  8. Wide range force feedback for catheter insertion mechanism for use in minimally invasive mitral valve repair surgery

    NASA Astrophysics Data System (ADS)

    Ahmadi, Roozbeh; Sokhanvar, Saeed; Packirisamy, Muthukumaran; Dargahi, Javad

    2009-02-01

    Mitral valve regurgitation (MR) is a condition in which heart's mitral valve does not close tightly, which allows blood to leak back into the left atrium. Restoring the dimension of the mitral-valve annulus by percutaneous intervention surgery is a common choice to treat MR. Currently, this kind of open heart annuloplasty surgery is being performed through sternotomy with cardiomyopathy bypass. In order to reduce trauma to the patient and also to eliminate bypass surgery, robotic assisted minimally invasive surgery (MIS) procedure, which requires small keyhole incisions, has a great potential. To perform this surgery through MIS procedure, an accurate computer controlled catheter with wide-range force feedback capabilities is required. There are three types of tissues at the site of operation: mitral leaflet, mitral annulus and left atrium. The maximum allowable applied force to these three types of tissue is totally different. For instance, leaflet tissue is the most sensitive one with the lowest allowable force capacity. For this application, therefore, a wide-range force sensing is highly required. Most of the sensors that have been developed for use in MIS applications have a limited range of sensing. Therefore, they need to be calibrated for different types of tissue. The present work, reports on the design, modeling and simulation of a novel wide-range optical force sensor for measurement of contact pressure between catheter tip and heart tissue. The proposed sensor offers a wide input range with a high resolution and sensitivity over this range. Using Micro-Electro-Mechanical-Systems (MEMS) technology, this sensor can be microfabricated and integrated with commercially available catheters.

  9. Rat disc torsional mechanics: effect of lumbar and caudal levels and axial compression load.

    PubMed

    Espinoza Orías, Alejandro A; Malhotra, Neil R; Elliott, Dawn M

    2009-03-01

    Rat models with altered loading are used to study disc degeneration and mechano-transduction. Given the prominent role of mechanics in disc function and degeneration, it is critical to measure mechanical behavior to evaluate changes after model interventions. Axial compression mechanics of the rat disc are representative of the human disc when normalized by geometry, and differences between the lumbar and caudal disc have been quantified in axial compression. No study has quantified rat disc torsional mechanics. Compare the torsional mechanical behavior of rat lumbar and caudal discs, determine the contribution of combined axial load on torsional mechanics, and compare the torsional properties of rat discs to human lumbar discs. Cadaveric biomechanical study. Cyclic torsion without compressive load followed by cyclic torsion with a fixed compressive load was applied to rat lumbar and caudal disc levels. The apparent torsional modulus was higher in the lumbar region than in the caudal region: 0.081+/-0.026 (MPa/degrees, mean+/-SD) for lumbar axially loaded; 0.066+/-0.028 for caudal axially loaded; 0.091+/-0.033 for lumbar in pure torsion; and 0.056+/-0.035 for caudal in pure torsion. These values were similar to human disc properties reported in the literature ranging from 0.024 to 0.21 MPa/degrees. Use of the caudal disc as a model may be appropriate if the mechanical focus is within the linear region of the loading regime. These results provide support for use of this animal model in basic science studies with respect to torsional mechanics.

  10. Urgent replacement of a mechanical mitral prosthesis in an anticoagulated patient with Bombay red blood cell phenotype.

    PubMed

    Nairn, Travis K; Giulivi, Antonio; Neurath, Doris; Tokessy, Melanie; Sia, Ying T; Ruel, Marc; Wilkes, Peter R H

    2010-06-01

    Bombay red blood cell phenotype is an extremely rare blood type for which patients can receive only autologous or Bombay phenotype red blood cells. We report a case of urgent repeat sternotomy for replacement of a mechanical mitral prosthesis in a patient with Bombay phenotype anticoagulated with warfarin, to emphasize the transfusion challenges in such patients. A male of Indian descent presented to hospital with New York Heart Association IV symptoms. His medical history revealed previous mitral valve replacement with a mechanical prosthesis in 2005 and Bombay phenotype blood. Preoperative transthoracic echocardiography demonstrated thrombus obstruction of the mitral prosthesis despite anticoagulation with warfarin. Right ventricular systolic pressure was >100 mmHg with 3+ tricuspid regurgitation. The patient's condition was temporized with diuretics, bronchodilators, and bi-level positive airway pressure ventilation while transfusion medicine and cardiac surgery were consulted for urgent surgery. The patient received vitamin K and prothrombin complex concentrate prior to repeat sternotomy and successful mitral prosthesis replacement. After cardiopulmonary bypass, heparinization was corrected with protamine and followed by a second dose of prothrombin complex concentrate and recombinant activated factor VIIa. Postoperatively, the patient received four units of packed red blood cells, two autologous units and two units of Bombay specific red blood cells. Right ventricular pressures stabilized at 40 mmHg following surgery. The patient recovered following several days of inotropic support with milrinone, diuretics, and bronchodilators. Patients with Bombay phenotype red blood cells present as type O, but they are unable to receive red blood cells from any phenotype other than Bombay phenotype. They are able to receive all other blood products, including fresh frozen plasma, cryoprecipitate, platelets, prothrombin complex concentrate, and recombinant activated factor

  11. Role of regional mechanical dyssynchrony as a determinant of functional mitral regurgitation in patients with left ventricular systolic dysfunction.

    PubMed

    Agricola, E; Oppizzi, M; Galderisi, M; Pisani, M; Meris, A; Pappone, C; Margonato, A

    2006-10-01

    To assess regional mechanical dyssynchrony as a determinant of the degree of functional mitral regurgitation (FMR). Tertiary cardiology clinic. 74 consecutive patients with left ventricular (LV) dysfunction (ejection fraction < 40%, mean 32.2 (SD 7.3)%) were evaluated. Effective regurgitant orifice (ERO) area, indices of mitral deformation (systolic valvular tenting, mitral annular contraction) and of global LV function and remodelling (ejection fraction, end systolic volume, sphericity index) and local remodelling (papillary-fibrosa distance, regional wall motion score index), and tissue Doppler-derived dyssynchrony index (DI) (regional DI, defined as the standard deviation of time to peak myocardial systolic contraction of eight LV segments supporting the papillary muscles attachment) were measured. All the assessed variables correlated significantly with ERO. By multivariate analysis, systolic valvular tenting was the strongest independent predictor of ERO (R(2) = 0.77, p = 0.0001), with a minor influence of papillary-fibrosa distance (R(2) = 0.77, p = 0.01) and regional DI (R(2) = 0.77, p = 0.03). Local LV remodelling (regional wall motion score index: R(2) = 0.58, p = 0.001; papillary-fibrosa distance: R(2) = 0.58, p = 0.002) and global remodelling indices (sphericity index: R(2) = 0.58, p = 0.003) were the main determinants of systolic valvular tenting, whereas regional DI did not enter into the model. Regional DI was an independent predictor of ERO (R(2) = 0.56, p = 0.005) in patients with non-ischaemic LV dysfunction but not in patients with ischaemic LV dysfunction when these groups were analysed separately. The degree of FMR is associated mainly with mitral deformation indices. The regional dyssynchrony also has an independent association with ERO but with a minor influence; however, it is not a determinant of FMR in patients with ischaemic LV dysfunction.

  12. Early Clinical Outcome of Mitral Valve Replacement Using a Newly Designed Stentless Mitral Valve for Failure of Initial Mitral Valve Repair.

    PubMed

    Nishida, Hidefumi; Kasegawa, Hitoshi; Kin, Hajime; Takanashi, Shuichiro

    2016-12-21

    Here we report the early outcome of mitral valve replacement using a newly designed stentless mitral valve for failure of initial mitral valve repair. Mitral valve plasty (MVP) for mitral regurgitation is currently a standard technique performed worldwide. However, whether mitral valve repair should be performed for patients with advanced leaflet damage or complicated pathology remains controversial. Mitral valve replacement might be feasible for patients who have undergone failed initial MVP; however, it is not an optimal treatment because of poor valve durability and the need for anticoagulative therapy. We report two cases of successful mitral valve replacement using a newly designed stentless mitral valve made of fresh autologous pericardium, which may have a potential benefit over mitral valve repair or mitral valve replacement with a mechanical or bioprosthetic valve.

  13. Effect of nicotine on spinal disc cells: a cellular mechanism for disc degeneration.

    PubMed

    Akmal, Mohammed; Kesani, Anil; Anand, Bobby; Singh, Abhinav; Wiseman, Mike; Goodship, Allen

    2004-03-01

    Experimental investigation to determine the effect of nicotine on intervertebral spinal disc nucleus pulposus (NP) cells cultured in vitro. OBJECTIVES.: To evaluate the effects of nicotine on cell proliferation, extracellular matrix production, and viability of NP cells in three-dimensional alginate constructs cultured in vitro. Numerous studies confirm that smoking is a strong risk factor for back pain. The most widely accepted explanations for the association between smoking and disc degeneration is malnutrition of spinal disc cells by carboxy-hemoglobin-induced anoxia or vascular disease. Nicotine, a constituent of tobacco smoke, present in most body fluids of smokers is known to have detrimental effects on a variety of tissues. It may also be directly responsible for intervertebral disc (IVD) degeneration by causing cell damage in both the nucleus pulposus and anulus fibrosus. The effect of nicotine on IVD cells has not previously been investigated. Bovine chondrocytic intervertebral disc cells were isolated by sequential digestion of nucleus pulposus and seeded in 2% alginate. The constructs were cultured for 21 days either in growth medium containing freebase nicotine (Sigma) at concentrations found in the serum of smokers (25 nmol/L-300 nmol/L) or in standard nicotine free-medium as controls. Samples were collected at time points 3, 7, 14, and 21 days and a quantitative assay was performed for DNA, glycosaminoglycans (GAG), and hydroxyproline. Samples were also processed for qualitative histologic analysis including immunolocalization of collagen types I and II. There was both a dose- and time-dependent response to nicotine, with constructs cultured in low-nicotine concentration media demonstrating an early increase in DNA, GAG, and collagen content, while constructs cultured in high nicotine concentration media demonstrated a late decrease in these parameters. At 25 nmol/L dose of nicotine, there was a significant increase (P < 0.05) in the above parameters

  14. Star GK Bileaflet Mechanical Valve Prosthesis-Patient Mismatch After Mitral Valve Replacement: A Chinese Multicenter Clinical Study

    PubMed Central

    Cao, Hua; Qiu, Zhihuang; Chen, Liangwan; Chen, Daozhong; Chen, Qiang

    2015-01-01

    Background The aim of this study was to investigate the incidence and immediate and mid-term effects of heart valve prosthesis-patient mismatch (PPM) after mitral valve replacement using the GK bileaflet mechanical valve. Material/Methods A total of 493 cases of mechanical mitral valve replacement were performed in the departments of cardiac surgery in 7 hospitals from January 2000 to January 2008. The patients included 142 men and 351 women ages 21 to 67 (average age, 48.75). The patients were followed for 3 years after surgery. The effective orifice area index (EOAI), ≤1.2 cm2/m2, was detected during the follow-up period and was defined as PPM. The patients were assigned to either the PPM group or the non-PPM group. Finally, the preoperative, perioperative and postoperative indexes of the 2 groups of patients were compared. Results A total of 157 patients had PPM 3 years after surgery. The incidence of PPM was 31.84%. Sixty-three patients in the PPM group received a 25-mm GK bileaflet valve (40.13%), 82 received a 27-mm valve (52.23%), and 12 (7.64%) received a 29-mm valve. There were significant differences in length of intensive care unit stay, duration of ventilator use, length of hospitalization, body surface area, EOAI, mean transmitral pressure gradient, and pulmonary artery pressure between the PPM and non-PPM group (P<0.05). There was a significant difference between preoperative and postoperative pulmonary artery pressures among non-PPM patients (P<0.05); however, there was no statistical difference in preoperative and postoperative pulmonary artery pressures among patients with PPM (P>0.05). Conclusions PPM after mitral valve replacement influences postoperative hemodynamics. Thus, larger-sized GK bileaflet mechanical valves are often used to reduce the risk of PPM. PMID:26313311

  15. Morphofunctional Abnormalities of Mitral Annulus and Arrhythmic Mitral Valve Prolapse

    PubMed Central

    Basso, Cristina; De Lazzari, Manuel; Rizzo, Stefania; Cipriani, Alberto; Giorgi, Benedetta; Lacognata, Carmelo; Rigato, Ilaria; Migliore, Federico; Pilichou, Kalliopi; Cacciavillani, Luisa; Bertaglia, Emanuele; Frigo, Anna Chiara; Bauce, Barbara; Corrado, Domenico; Thiene, Gaetano; Iliceto, Sabino

    2016-01-01

    Background— Arrhythmic mitral valve prolapse (MVP) is characterized by myxomatous leaflets and left ventricular (LV) fibrosis of papillary muscles and inferobasal wall. We searched for morphofunctional abnormalities of the mitral valve that could explain a regional mechanical myocardial stretch. Methods and Results— Thirty-six (27 female patients; median age: 44 years) arrhythmic MVP patients with LV late gadolinium enhancement on cardiac magnetic resonance and no or trivial mitral regurgitation, and 16 (6 female patients; median age: 40 years) MVP patients without LV late gadolinium enhancement were investigated by morphofunctional cardiac magnetic resonance. Mitral annulus disjunction (median: 4.8 versus 1.8 mm; P<0.001), end-systolic mitral annular diameters (median: 41.2 versus 31.5; P=0.004) and end-diastolic mitral annular diameters (median: 35.5 versus 31.5; P=0.042), prevalence of posterior systolic curling (34 [94%] versus 3 [19%]; P<0.001), and basal to mid LV wall thickness ratio >1.5 (22 [61%] versus 4 [25%]; P=0.016) were higher in MVP patients with late gadolinium enhancement than in those without. A linear correlation was found between mitral annulus disjunction and curling (R=0.85). A higher prevalence of auscultatory midsystolic click (26 [72%] versus 6 [38%]; P=0.018) was also noted. Histology of the mitral annulus showed a longer mitral annulus disjunction in 50 sudden death patients with MVP and LV fibrosis than in 20 patients without MVP (median: 3 versus 1.5 mm; P<0.001). Conclusions— Mitral annulus disjunction is a constant feature of arrhythmic MVP with LV fibrosis. The excessive mobility of the leaflets caused by posterior systolic curling accounts for a mechanical stretch of the inferobasal wall and papillary muscles, eventually leading to myocardial hypertrophy and scarring. These mitral annulus abnormalities, together with auscultatory midsystolic click, may identify MVP patients who would need arrhythmic risk stratification. PMID

  16. Morphofunctional Abnormalities of Mitral Annulus and Arrhythmic Mitral Valve Prolapse.

    PubMed

    Perazzolo Marra, Martina; Basso, Cristina; De Lazzari, Manuel; Rizzo, Stefania; Cipriani, Alberto; Giorgi, Benedetta; Lacognata, Carmelo; Rigato, Ilaria; Migliore, Federico; Pilichou, Kalliopi; Cacciavillani, Luisa; Bertaglia, Emanuele; Frigo, Anna Chiara; Bauce, Barbara; Corrado, Domenico; Thiene, Gaetano; Iliceto, Sabino

    2016-08-01

    Arrhythmic mitral valve prolapse (MVP) is characterized by myxomatous leaflets and left ventricular (LV) fibrosis of papillary muscles and inferobasal wall. We searched for morphofunctional abnormalities of the mitral valve that could explain a regional mechanical myocardial stretch. Thirty-six (27 female patients; median age: 44 years) arrhythmic MVP patients with LV late gadolinium enhancement on cardiac magnetic resonance and no or trivial mitral regurgitation, and 16 (6 female patients; median age: 40 years) MVP patients without LV late gadolinium enhancement were investigated by morphofunctional cardiac magnetic resonance. Mitral annulus disjunction (median: 4.8 versus 1.8 mm; P<0.001), end-systolic mitral annular diameters (median: 41.2 versus 31.5; P=0.004) and end-diastolic mitral annular diameters (median: 35.5 versus 31.5; P=0.042), prevalence of posterior systolic curling (34 [94%] versus 3 [19%]; P<0.001), and basal to mid LV wall thickness ratio >1.5 (22 [61%] versus 4 [25%]; P=0.016) were higher in MVP patients with late gadolinium enhancement than in those without. A linear correlation was found between mitral annulus disjunction and curling (R=0.85). A higher prevalence of auscultatory midsystolic click (26 [72%] versus 6 [38%]; P=0.018) was also noted. Histology of the mitral annulus showed a longer mitral annulus disjunction in 50 sudden death patients with MVP and LV fibrosis than in 20 patients without MVP (median: 3 versus 1.5 mm; P<0.001). Mitral annulus disjunction is a constant feature of arrhythmic MVP with LV fibrosis. The excessive mobility of the leaflets caused by posterior systolic curling accounts for a mechanical stretch of the inferobasal wall and papillary muscles, eventually leading to myocardial hypertrophy and scarring. These mitral annulus abnormalities, together with auscultatory midsystolic click, may identify MVP patients who would need arrhythmic risk stratification. © 2016 The Authors.

  17. Predicting recurrent mitral regurgitation after mitral valve repair for severe ischemic mitral regurgitation.

    PubMed

    Kron, Irving L; Hung, Judy; Overbey, Jessica R; Bouchard, Denis; Gelijns, Annetine C; Moskowitz, Alan J; Voisine, Pierre; O'Gara, Patrick T; Argenziano, Michael; Michler, Robert E; Gillinov, Marc; Puskas, John D; Gammie, James S; Mack, Michael J; Smith, Peter K; Sai-Sudhakar, Chittoor; Gardner, Timothy J; Ailawadi, Gorav; Zeng, Xin; O'Sullivan, Karen; Parides, Michael K; Swayze, Roger; Thourani, Vinod; Rose, Eric A; Perrault, Louis P; Acker, Michael A

    2015-03-01

    The Cardiothoracic Surgical Trials Network recently reported no difference in the primary end point of left ventricular end-systolic volume index at 1 year postsurgery in patients randomized to repair (n = 126) or replacement (n = 125) for severe ischemic mitral regurgitation. However, patients undergoing repair experienced significantly more recurrent mitral regurgitation than patients undergoing replacement (32.6% vs 2.3%). We examined whether baseline echocardiographic and clinical characteristics could identify those who will develop moderate/severe recurrent mitral regurgitation or die. Our analysis includes 116 patients who were randomized to and received mitral valve repair. Logistic regression was used to estimate a model-based probability of recurrence or death from baseline factors. Receiver operating characteristic curves were constructed from these estimated probabilities to determine classification cut-points maximizing accuracy of prediction based on sensitivity and specificity. Of the 116 patients, 6 received a replacement before leaving the operating room; all other patients had mild or less mitral regurgitation on intraoperative echocardiogram after repair. During the 2-year follow-up period, 76 patients developed moderate/severe mitral regurgitation or died (53 mitral regurgitation recurrences, 13 mitral regurgitation recurrences and death, and 10 deaths). The mechanism for recurrent mitral regurgitation was largely mitral valve leaflet tethering. Our model (including age, body mass index, sex, race, effective regurgitant orifice area, basal aneurysm/dyskinesis, New York Heart Association class, history of coronary artery bypass grafting, percutaneous coronary intervention, or ventricular arrhythmias) yielded an area under the receiver operating characteristic curve of 0.82. The model demonstrated good discrimination in identifying patients who will survive 2 years without recurrent mitral regurgitation after mitral valve repair. Although our

  18. Mitral stenosis (image)

    MedlinePlus

    Mitral stenosis is a heart valve disorder that narrows or obstructs the mitral valve opening. Narrowing of the mitral ... the body. The main risk factor for mitral stenosis is a history of rheumatic fever but it ...

  19. Mitral mechanical valve without long-term anticoagulation. Eight-year follow-up.

    PubMed

    Björk, V O; Ribeiro, A; Canetti, M; Bomfim, V

    1994-01-01

    In 12 patients with sinus rhythm (including 5 children and 6 young women), mitral valve replacement was performed with a microporous-surfaced valve similar to the Björk-Shiley Monostrut. After the first 3 months, permitting endothelialization of the suture ring to continue over the groove and adjacent metal valve ring, no long-term anticoagulant treatment was given. There was no thromboembolic complication in this group during follow-up for 6-8 years, during which four women gave birth to a total of seven children. In eight other cases, one mitral case with atrial fibrillation, anti-coagulant was not discontinued, and in the remaining aortic cases it was reinstituted. One of them (with atrial fibrillation) had hematuria during inadequate anticoagulant medication, but no thromboembolism. Of five patients with only aortic valve replacement, two had thromboembolic complications, one without residual symptoms and one with slight hand weakness. Another had a transient ischemic attack while on anticoagulant and acetylsalicylic acid was added. Two patients with aortic and mitral valve replacement died, one from heart tamponade and the other from venous thrombosis with pulmonary embolism.

  20. Aging and age related stresses: a senescence mechanism of intervertebral disc degeneration.

    PubMed

    Wang, F; Cai, F; Shi, R; Wang, X-H; Wu, X-T

    2016-03-01

    Intervertebral disc (IVD) degeneration is a complicated process that involves both age-related change and tissue damage caused by multiple stresses. In a degenerative IVD, cellular senescence accumulates and is associated with reduced proliferation, compromised self-repair, increased inflammatory response, and enhanced catabolic metabolism. In this review, we decipher the senescence mechanism of IVD degeneration (IVDD) by interpreting how aging coordinates with age-related, microenvironment-derived stresses in promoting disc cell senescence and accelerating IVDD. After chronic and prolonged replication, cell senescence may occur as a natural part of the disc aging process, but can potentially be accelerated by growth factor deficiency, oxidative accumulation, and inflammatory irritation. While acute disc injury, excessive mechanical overloading, diabetes, and chronic tobacco smoking contribute to the amplification of senescence-inducing stresses, the avascular nature of IVD impairs the immune-clearance of the senescent disc cells, which accumulate in cell clusters, demonstrate inflammatory and catabolic phenotypes, deteriorate disc microenvironment, and accelerate IVDD. Anti-senescence strategies, including telomerase transduction, supply of growth factors, and blocking cell cycle inhibitors, have been shown to be feasible in rescuing disc cells from early senescence, but their efficiency for disc regeneration requires more in vivo validations. Guidelines dedicated to avoiding or alleviating senescence-inducing stresses might decelerate cellular senescence and benefit patients with IVD degenerative diseases. Copyright © 2015 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.

  1. The Relation Between Collagen Fibril Kinematics and Mechanical Properties in the Mitral Valve Anterior Leaflet

    SciTech Connect

    Liao,J.; Yang, L.; Grashow, J.; Sacks, M.

    2007-01-01

    We have recently demonstrated that the mitral valve anterior leaflet (MVAL) exhibited minimal hysteresis, no strain rate sensitivity, stress relaxation but not creep (Grashow et al., 2006, Ann Biomed Eng., 34(2), pp. 315-325; Grashow et al., 2006, Ann Biomed. Eng., 34(10), pp. 1509-1518). However, the underlying structural basis for this unique quasi-elastic mechanical behavior is presently unknown. As collagen is the major structural component of the MVAL, we investigated the relation between collagen fibril kinematics (rotation and stretch) and tissue-level mechanical properties in the MVAL under biaxial loading using small angle X-ray scattering. A novel device was developed and utilized to perform simultaneous measurements of tissue level forces and strain under a planar biaxial loading state. Collagen fibril D-period strain ({epsilon}{sub D}) and the fibrillar angular distribution were measured under equibiaxial tension, creep, and stress relaxation to a peak tension of 90 N/m. Results indicated that, under equibiaxial tension, collagen fibril straining did not initiate until the end of the nonlinear region of the tissue-level stress-strain curve. At higher tissue tension levels, {epsilon}{sub D} increased linearly with increasing tension. Changes in the angular distribution of the collagen fibrils mainly occurred in the tissue toe region. Using {epsilon}{sub D}, the tangent modulus of collagen fibrils was estimated to be 95.5{+-}25.5 MPa, which was {approx}27 times higher than the tissue tensile tangent modulus of 3.58{+-}1.83 MPa. In creep tests performed at 90 N/m equibiaxial tension for 60 min, both tissue strain and D remained constant with no observable changes over the test length. In contrast, in stress relaxation tests performed for 90 min {epsilon}{sub D} was found to rapidly decrease in the first 10 min followed by a slower decay rate for the remainder of the test. Using a single exponential model, the time constant for the reduction in collagen

  2. Sensitivity of notochordal disc cells to mechanical loading: an experimental animal study.

    PubMed

    Guehring, Thorsten; Nerlich, Andreas; Kroeber, Markus; Richter, Wiltrud; Omlor, Georg W

    2010-01-01

    The immature disc nucleus pulposus (NP) consists of notochordal cells (NCs). With maturation NCs disappear in humans, to be replaced by chondrocyte-like mature NP cells (MNPCs); this change in cell phenotype coincidences with early signs of disc degeneration. The reasons for NC disappearance are important to understand disc degeneration, but remain unknown, yet. This study investigated, whether loading induced a change from a notochordal nucleus phenotype to a chondrocyte-like one. An in vivo disc compression model with fixateur externe was used in 36 mature rabbits. Discs were compressed for different time periods (1, 28, 56 days), and compared with uncompressed control discs (56 days without treatment), and discs with sham compression (28 days). Nucleus cell phenotype was determined by histology and immunohistochemistry. NCs, but not MNPCs highly expressed bone-morphogenetic-protein 2 and cytokeratin 8, thus NC and MNPC numbers could be determined. A histologic score was used to detect structural endplate changes after compression (28 days). Control and sham compressed discs contained around 70% NCs and 30% MNPCs, to be decreased to <10% NCs after 28-56 days of loading. NC density fell sharply by >50% after 28-56 days of compression (P < 0.05 vs. controls). Signs of decreased endplate cellularity and increased endplate sclerosis and fibrosis were found after loading. These experiments show that NCs were less resistant to mechanical stress than MNPCs suggesting that increased intradiscal pressures after loading, and limited nutrition through structurally altered endplates could instigate the disappearance of NCs.

  3. The Auriga Project: the properties and formation mechanisms of disc galaxies across cosmic time

    NASA Astrophysics Data System (ADS)

    Grand, Robert J. J.; Gómez, Facundo A.; Marinacci, Federico; Pakmor, Rüdiger; Springel, Volker; Campbell, David J. R.; Frenk, Carlos S.; Jenkins, Adrian; White, Simon D. M.

    2017-05-01

    We introduce a suite of 30 cosmological magneto-hydrodynamical zoom simulations of the formation of galaxies in isolated Milky Way mass dark haloes. These were carried out with the moving mesh code arepo, together with a comprehensive model for galaxy formation physics, including active galactic nuclei (AGN) feedback and magnetic fields, which produces realistic galaxy populations in large cosmological simulations. We demonstrate that our simulations reproduce a wide range of present-day observables, in particular, two-component disc-dominated galaxies with appropriate stellar masses, sizes, rotation curves, star formation rates and metallicities. We investigate the driving mechanisms that set present-day disc sizes/scalelengths, and find that they are related to the angular momentum of halo material. We show that the largest discs are produced by quiescent mergers that inspiral into the galaxy and deposit high-angular momentum material into the pre-existing disc, simultaneously increasing the spin of dark matter and gas in the halo. More violent mergers and strong AGN feedback play roles in limiting disc size by destroying pre-existing discs and by suppressing gas accretion on to the outer disc, respectively. The most important factor that leads to compact discs, however, is simply a low angular momentum for the halo. In these cases, AGN feedback plays an important role in limiting central star formation and the formation of a massive bulge.

  4. The Auriga Project: the properties and formation mechanisms of disc galaxies across cosmic time

    NASA Astrophysics Data System (ADS)

    Grand, Robert J. J.; Gómez, Facundo A.; Marinacci, Federico; Pakmor, Rüdiger; Springel, Volker; Campbell, David J. R.; Frenk, Carlos S.; Jenkins, Adrian; White, Simon D. M.

    2017-01-01

    We introduce a suite of thirty cosmological magneto-hydrodynamical zoom simulations of the formation of galaxies in isolated Milky Way mass dark haloes. These were carried out with the moving mesh code AREPO, together with a comprehensive model for galaxy formation physics, including AGN feedback and magnetic fields, which produces realistic galaxy populations in large cosmological simulations. We demonstrate that our simulations reproduce a wide range of present-day observables, in particular, two component disc dominated galaxies with appropriate stellar masses, sizes, rotation curves, star formation rates and metallicities. We investigate the driving mechanisms that set present-day disc sizes/scale lengths, and find that they are related to the angular momentum of halo material. We show that the largest discs are produced by quiescent mergers that inspiral into the galaxy and deposit high angular momentum material into the pre-existing disc, simultaneously increasing the spin of dark matter and gas in the halo. More violent mergers and strong AGN feedback play roles in limiting disc size by destroying pre-existing discs and by suppressing gas accretion onto the outer disc, respectively. The most important factor that leads to compact discs, however, is simply a low angular momentum for the halo. In these cases, AGN feedback plays an important role in limiting central star formation and the formation of a massive bulge.

  5. Are the Current Doppler Echocardiography Criteria Able to Discriminate Mitral Bileaflet Mechanical Heart Valve Malfunction? An In Vitro Study.

    PubMed

    Evin, Morgane; Guivier-Curien, Carine; Pibarot, Philippe; Kadem, Lyes; Rieu, Régis

    2016-05-01

    Malfunction of bileaflet mechanical heart valves in the mitral position could either be due to patient-prosthesis mismatch (PPM) or leaflet obstruction. The aim of this article is to investigate the validity of current echocardiographic criteria used for diagnosis of mitral prosthesis malfunction, namely maximum velocity, mean transvalvular pressure gradient, effective orifice area, and Doppler velocity index. In vitro testing was performed on a double activation left heart duplicator. Both PPM and leaflet obstruction were investigated on a St. Jude Medical Master. PPM was studied by varying the St. Jude prosthesis size (21, 25, and 29 mm) and stroke volume (70 and 90 mL). Prosthesis leaflet obstruction was studied by partially or totally blocking the movement of one valve leaflet. Mitral flow conditions were altered in terms of E/A ratios (0.5, 1.0, and 1.5) to simulate physiologic panel of diastolic function. Maximum velocity, effective orifice area, and Doppler velocity index are shown to be insufficient to distinguish normal from malfunctioning St. Jude prostheses. Doppler velocity index and effective orifice area were 1.3 ± 0.49 and 1.83 ± 0.43 cm(2) for testing conditions with no malfunction below the 2.2 and 2 cm(2) thresholds (1.19 cm(2) for severe PPM and 1.23 cm(2) for fully blocked leaflet). The mean pressure gradient reached 5 mm Hg thresholds for several conditions of severe PPM only (6.9 mm Hg and mean maximum velocity value: 183.4 cm/s) whereas such value was never attained in the case of leaflet obstruction. In the case of leaflet obstruction, the maximum velocity averaged over the nine pulsed-wave Doppler locations increased by 38% for partial leaflet obstruction and 75% for a fully blocked leaflet when compared with normal conditions. Current echocardiographic criteria might be suboptimal for the detection of bileaflet mechanical heart valve malfunction. Further developments and investigations are required in order

  6. Effect of Mechanical Strain on Solute Diffusion in Human TMJ Discs: An Electrical Conductivity Study

    PubMed Central

    Wright, Gregory J.; Kuo, Jonathan; Shi, Changcheng; Bacro, Thierry H.; Slate, Elizabeth H.; Yao, Hai

    2013-01-01

    This study investigated the effect of mechanical strain on solute diffusion in human TMJ discs (mean cadaver age 77.8) using the electrical conductivity method. The electrical conductivity, as well as small ion diffusivity, of male and female TMJ discs was determined under three compressive strains. In the male group, the average disc electrical conductivity (mean ± sd) at 0% strain was 5.14±0.97 mS/cm, decreased to 4.50±0.91 mS/cm (−12.3%) at 10% strain, and 3.93±0.81 mS/cm (−23.5%) at 20% compressive strain. Correspondingly, the average disc relative ion diffusivity at 0% strain was 0.44±0.08, decreased to 0.40±0.08 (−8.9%) at 10% strain, and 0.36±0.08 (−16.7%) at 20% compressive strain. In the female group, the average disc electrical conductivity at 0% strain was 5.84±0.59 mS/cm, decreased to 5.01±0.50 mS/cm (−14.2%) at 10% strain, and 4.33±0.46 mS/cm (−25.8%) at 20% compressive strain. Correspondingly, the average disc relative ion diffusivity at 0% strain was 0.49±0.05, decreased to 0.43±0.04 (−11.3%) at 10% strain, and 0.39±0.04 (−19.9%) at 20% compressive strain. The results indicated that mechanical strain significantly impeded solute diffusion through the disc. This mechanical strain effect was larger in the female than in the male human TMJ disc. This study may provide new insights into TMJ pathophysiology. PMID:23771300

  7. Comparison of Transesophageal and Transthoracic Echocardiographic Measurements of Mechanism and Severity of Mitral Regurgitation in Ischemic Cardiomyopathy (From the STICH trial)

    PubMed Central

    Grayburn, Paul A.; She, Lilin; Roberts, Brad J.; Golba, Krzysztof S.; Mokrzycki, Krzysztof; Drozdz, Jaroslaw; Cherniavsky, Alexander; Przybylski, Roman; Wrobel, Krzysztof; Asch, Federico M.; Holly, Thomas A.; Haddad, Haissam; Yii, Michael; Maurer, Gerald; Kron, Irving; Schaff, Hartzell; Velazquez, Eric J.; Oh, Jae K.

    2015-01-01

    Mitral regurgitation (MR) is common in ischemic heart disease and contributes to symptoms and mortality. This report compares the results of baseline transesophageal echocardiography (TEE) and transthoracic echocardiography (TTE) imaging of the mechanism and severity of functional MR in patients with ischemic cardiomyopathy in the Surgical Treatment for Ischemic Heart Failure (STICH) trial. Independent core labs measured both TTE and TEE images on 196 STICH patients. Common measurements to both modalities included MR grade, mitral valve tenting height and tenting area, and mitral annular diameter. For each parameter, correlations were assessed using Spearman rank correlation coefficients. A modest correlation (figure) was present between TEE and TTE for overall MR grade (n=176, r=0.52). For mechanism of MR, modest correlations were present for long-axis tenting height (n=152, r=0.35), tenting area (n=128, r=0.27), and long-axis mitral annulus diameter (n=123, r=0.41). For each measurement, there was significant scatter. Potential explanations for the scatter include different orientation of the imaging planes between TEE and TTE, a mean temporal delay of 6 days between TEE and TTE, and statistically significant differences in heart rate and blood pressure and weight between studies. In conclusion, TEE and TTE measurements of MR mechanism and severity correlate only modestly with enough scatter in the data that they are not interchangeable. PMID:26170249

  8. Mechanical Characterization of the Human Lumbar Intervertebral Disc Subjected to Impact Loading Conditions

    NASA Astrophysics Data System (ADS)

    Jamison, David, IV

    Low back pain is a large and costly problem in the United States. Several working populations, such as miners, construction workers, forklift operators, and military personnel, have an increased risk and prevalence of low back pain compared to the general population. This is due to exposure to repeated, transient impact shocks, particularly while operating vehicles or other machinery. These shocks typically do not cause acute injury, but rather lead to pain and injury over time. The major focus in low back pain is often the intervertebral disc, due to its role as the major primary load-bearing component along the spinal column. The formation of a reliable standard for human lumbar disc exposure to repeated transient shock could potentially reduce injury risk for these working populations. The objective of this project, therefore, is to characterize the mechanical response of the lumbar intervertebral disc subjected to sub-traumatic impact loading conditions using both cadaveric and computational models, and to investigate the possible implications of this type of loading environment for low back pain. Axial, compressive impact loading events on Naval high speed boats were simulated in the laboratory and applied to human cadaveric specimen. Disc stiffness was higher and hysteresis was lower than quasi-static loading conditions. This indicates a shift in mechanical response when the disc is under impact loads and this behavior could be contributing to long-term back pain. Interstitial fluid loss and disc height changes were shown to affect disc impact mechanics in a creep study. Neutral zone increased, while energy dissipation and low-strain region stiffness decreased. This suggests that the disc has greater clinical instability during impact loading with progressive creep and fluid loss, indicating that time of day should be considered for working populations subjected to impact loads. A finite element model was developed and validated against cadaver specimen

  9. Pathology and possible mechanisms of nervous system response to disc degeneration.

    PubMed

    Brisby, Helena

    2006-04-01

    Degeneration of the intervertebral disc is clinically considered to be an important source of pain in patients with low-back pain. Disc deterioration and/or degeneration may influence the nervous system by stimulation of nociceptors in the anulus fibrosus, causing nociceptive pain that is often referred to as discogenic pain. The stimulation of the nociceptors may be of mechanical or inflammatory origin. Deterioration of a disc with loss of normal structure and weight-bearing properties may lead to abnormal motions that cause mechanical stimulation. This theory is supported by the fact that patients commonly experience an increase in pain with weight-bearing and certain movements. In addition, an ingrowth of vessels and nerve fibers into deeper layers of the anulus fibrosus has been observed in degenerated discs. A large number of inflammatory and signaling substances, such as tumor necrosis factor and interleukins (interleukin-1beta, interleukin-6, and interleukin-8), may also play a role in the development of back pain. Independent of stimulus of the nociceptors, the pain impulses are conducted through myelinated A delta fibers and unmyelinated C fibers to the dorsal root ganglion and continue by way of the spinothalamic tract to the thalamus and the somatosensory cortex. In response to stimulation of the nociceptors in the disc, the somatosensory system may increase its sensitivity, resulting in a nonfunctional response; that is, normally innocuous stimuli may generate an amplified response (peripheral sensitization). When disc degeneration leads to a disc herniation, the adjacent nervous system structures, such as the nerve roots or the dorsal root ganglion, can be affected, causing neuropathic pain of mechanical or biochemical origin. Disc deterioration also influences other spinal structures, such as facet joints, ligaments, and muscles, which can also become pain generators. Thus, disc degeneration may be responsible for the development of chronic low

  10. Ischemic mitral valve prolapse

    PubMed Central

    Cristiano, Spadaccio; Nenna, Antonio; Chello, Massimo

    2016-01-01

    Ischemic mitral prolapse (IMP) is a pathologic entity encountered in about one-third among the patients undergoing surgery for ischemic mitral regurgitation (IMR). IMP is generally the result of a papillary muscle injury consequent to myocardial, but the recent literature is progressively unveiling a more complex pathogenesis. The mechanisms underlying its development regards the impairment of one or more components of the mitral apparatus, which comprises the annulus, the chordae tendineae, the papillary muscle and the left ventricular wall. IMP is not only a disorder of valvular function, but also entails coexistent aspects of a geometric disturbance of the mitral valve configuration and of the left ventricular function and dimension and a correct understanding of all these aspects is crucial to guide and tailor the correct therapeutic strategy to be adopted. Localization of prolapse, anatomic features of the prolapsed leaflets and the subvalvular apparatus should be carefully evaluated as also constituting the major determinants defining patient’s outcomes. This review will summarize our current understanding of the pathophysiology and clinical evidence on IMP with a particular focus on the surgical treatment. PMID:28149574

  11. Sensitivity of notochordal disc cells to mechanical loading: an experimental animal study

    PubMed Central

    Guehring, Thorsten; Nerlich, Andreas; Kroeber, Markus; Richter, Wiltrud

    2009-01-01

    The immature disc nucleus pulposus (NP) consists of notochordal cells (NCs). With maturation NCs disappear in humans, to be replaced by chondrocyte-like mature NP cells (MNPCs); this change in cell phenotype coincidences with early signs of disc degeneration. The reasons for NC disappearance are important to understand disc degeneration, but remain unknown, yet. This study investigated, whether loading induced a change from a notochordal nucleus phenotype to a chondrocyte-like one. An in vivo disc compression model with fixateur externe was used in 36 mature rabbits. Discs were compressed for different time periods (1, 28, 56 days), and compared with uncompressed control discs (56 days without treatment), and discs with sham compression (28 days). Nucleus cell phenotype was determined by histology and immunohistochemistry. NCs, but not MNPCs highly expressed bone-morphogenetic-protein 2 and cytokeratin 8, thus NC and MNPC numbers could be determined. A histologic score was used to detect structural endplate changes after compression (28 days). Control and sham compressed discs contained around 70% NCs and 30% MNPCs, to be decreased to <10% NCs after 28–56 days of loading. NC density fell sharply by >50% after 28–56 days of compression (P < 0.05 vs. controls). Signs of decreased endplate cellularity and increased endplate sclerosis and fibrosis were found after loading. These experiments show that NCs were less resistant to mechanical stress than MNPCs suggesting that increased intradiscal pressures after loading, and limited nutrition through structurally altered endplates could instigate the disappearance of NCs. PMID:19936803

  12. Assessment of trans-aortic pressure gradient using a coronary pressure wire in patients with mechanical aortic and mitral valve prostheses.

    PubMed

    Kherada, Nisharahmed; Brenes, Juan Carlos; Kini, Annapoorna S; Dangas, George D

    2017-03-15

    Accurate evaluation of trans-aortic valvular pressure gradients is challenging in cases where dual mechanical aortic and mitral valve prostheses are present. Non-invasive Doppler echocardiographic imaging has its limitations due to multiple geometric assumptions. Invasive measurement of trans-valvular gradients with cardiac catheterization can provide further information in patients with two mechanical valves, where simultaneous pressure measurements in the left ventricle and ascending aorta must be obtained. Obtaining access to the left ventricle via the mitral valve after a trans-septal puncture is not feasible in the case of a concomitant mechanical mitral valve, whereas left ventricular apical puncture technique is associated with high procedural risks. Retrograde crossing of a bileaflet mechanical aortic prosthesis with standard catheters is associated with the risk of catheter entrapment and acute valvular regurgitation. In these cases, the assessment of trans-valvular gradients using a 0.014˝ diameter coronary pressure wire technique has been described in a few case reports. We present the case of a 76-year-old female with rheumatic valvular heart disease who underwent mechanical aortic and mitral valve replacement in the past. She presented with decompensated heart failure and echocardiographic findings suggestive of elevated pressure gradient across the mechanical aortic valve prosthesis. The use of a high-fidelity 0.014˝ diameter coronary pressure guidewire resulted in the detection of a normal trans-valvular pressure gradient across the mechanical aortic valve. This avoided a high-risk third redo valve surgery in our patient. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  13. Mechanisms of Functional Mitral Regurgitation in Ischemic Cardiomyopathy Determined by Transesophageal Echocardiography (From the Surgical Treatment for Ischemic Heart Failure [STICH] Trial)

    PubMed Central

    Golba, Krzysztof; Mokrzycki, Krzysztof; Drozdz, Jaroslaw; Cherniavsky, Alexander; Wrobel, Krzysztof; Roberts, Bradley J.; Haddad, Haissam; Maurer, Gerald; Yii, Michael; Asch, Federico M.; Handschumacher, Mark D.; Holly, Thomas A.; Przybylski, Roman; Kron, Irving; Schaff, Hartzell; Aston, Susan; Horton, John; Lee, Kerry L.; Velazquez, Eric J.; Grayburn, Paul A.

    2013-01-01

    The mechanisms underlying functional mitral regurgitation (MR), and the relation between mechanism and severity of MR have not been evaluated in a large multicenter randomized controlled trial. Transesophageal echocardiography (TEE) was performed in 215 patients at 17 centers in the Surgical Treatment of Ischemic Heart Failure (STICH) trial. Both two-dimensional (2D, n=215) and three-dimensional (3D, n=81) TEE were used to assess multiple quantitative measures of the mechanism and severity of MR. By 2D TEE, leaflet tenting area, anterior and posterior leaflet angles, mitral annulus diameter, left ventricular (LV) end-systolic volume index, LV ejection fraction (LVEF), and sphericity index (p<0.05 for all) were significantly different across MR grades. By 3D TEE, mitral annulus area, leaflet tenting area, LV end-systolic volume index, LVEF, and sphericity index (p<0.05 for all) were significantly different across MR grades. A multivariable analysis showed a trend for annulus area (p=0.069) and LV end-systolic volume index (p=0.071) to predict effective regurgitant orifice area (EROA) and for annulus area (p=0.018) and LV end-systolic volume index (p=0.073) to predict vena contracta area. In the STICH trial, multiple quantitative parameters of the mechanism of functional MR are related to MR severity. The mechanism of functional MR in ischemic cardiomyopathy is heterogeneous but no single variable stands out as a strong predictor of quantitative severity of MR. PMID:24035166

  14. Disc Degeneration Assessed by Quantitative T2* (T2 star) Correlated with Functional Lumbar Mechanics

    PubMed Central

    Ellingson, Arin M.; Mehta, Hitesh; Polly, David W.; Ellermann, Jutta; Nuckley, David J.

    2013-01-01

    Study Design Experimental correlation study design to quantify features of disc health, including signal intensity and distinction between the annulus fibrosus (AF) and nucleus pulposus (NP), with T2* magnetic resonance imaging (MRI) and correlate with the functional mechanics in corresponding motion segments. Objective Establish the relationship between disc health assessed by quantitative T2* MRI and functional lumbar mechanics. Summary of Background Data Degeneration leads to altered biochemistry in the disc, affecting the mechanical competence. Clinical routine MRI sequences are not adequate in detecting early changes in degeneration and fails to correlate with pain or improve patient stratification. Quantitative T2* relaxation time mapping probes biochemical features and may offer more sensitivity in assessing disc degeneration. Methods Cadaveric lumbar spines were imaged using quantitative T2* mapping, as well as conventional T2-weighted MRI sequences. Discs were graded by the Pfirrmann scale and features of disc health, including signal intensity (T2* Intensity Area) and distinction between the AF and NP (Transition Zone Slope), were quantified by T2*. Each motion segment was subjected to pure moment bending to determine range of motion (ROM), neutral zone (NZ), and bending stiffness. Results T2* Intensity Area and Transition Zone Slope were significantly correlated with flexion ROM (p=0.015; p=0.002), ratio of NZ/ROM (p=0.010; p=0.028), and stiffness (p=0.044; p=0.026), as well as lateral bending NZ/ROM (p=0.005; p=0.010) and stiffness (p=0.022; p=0.029). T2* Intensity Area was also correlated with LB ROM (p=0.023). Pfirrmann grade was only correlated with lateral bending NZ/ROM (p=0.001) and stiffness (p=0.007). Conclusions T2* mapping is a sensitive quantitative method capable of detecting changes associated with disc degeneration. Features of disc health quantified with T2* predicted altered functional mechanics of the lumbar spine better than

  15. Mechanical Vibrations Reduce the Intervertebral Disc Swelling and Muscle Atrophy from Bed Rest

    NASA Technical Reports Server (NTRS)

    Holguin, Nilsson; Muir, Jesse; Evans, Harlan J.; Qin, Yi-Xian; Rubin, Clinton; Wagshul, Mark; Judex, Stefan

    2007-01-01

    Loss of functional weight bearing, such as experienced during space flight or bed rest (BR), distorts intervertebral disc (IVD) and muscle morphology. IVDs are avascular structures consisting of cells that may derive their nutrition and waste removal from the load induced fluid flow into and out of the disc. A diurnal cycle is produced by forces related to weight bearing and muscular activity, and comprised of a supine and erect posture over a 24 hr period. A diurnal cycle will include a disc volume change of approx. 10-13%. However, in space there are little or no diurnal changes because of the microgravity, which removes the gravitational load and compressive forces to the back muscles. The BR model and the etiology of the disc swelling and muscle atrophy could provide insight into those subjects confined to bed for chronic disease/injury and aging. We hypothesize that extremely low-magnitude, high frequency mechanical vibrations will abate the disc degeneration and muscle loss associated with long-term BR.

  16. Drosophila wing imaginal discs respond to mechanical injury via slow InsP3R-mediated intercellular calcium waves

    NASA Astrophysics Data System (ADS)

    Restrepo, Simon; Basler, Konrad

    2016-08-01

    Calcium signalling is a highly versatile cellular communication system that modulates basic functions such as cell contractility, essential steps of animal development such as fertilization and higher-order processes such as memory. We probed the function of calcium signalling in Drosophila wing imaginal discs through a combination of ex vivo and in vivo imaging and genetic analysis. Here we discover that wing discs display slow, long-range intercellular calcium waves (ICWs) when mechanically stressed in vivo or cultured ex vivo. These slow imaginal disc intercellular calcium waves (SIDICs) are mediated by the inositol-3-phosphate receptor, the endoplasmic reticulum (ER) calcium pump SERCA and the key gap junction component Inx2. The knockdown of genes required for SIDIC formation and propagation negatively affects wing disc recovery after mechanical injury. Our results reveal a role for ICWs in wing disc homoeostasis and highlight the utility of the wing disc as a model for calcium signalling studies.

  17. Drosophila wing imaginal discs respond to mechanical injury via slow InsP3R-mediated intercellular calcium waves

    PubMed Central

    Restrepo, Simon; Basler, Konrad

    2016-01-01

    Calcium signalling is a highly versatile cellular communication system that modulates basic functions such as cell contractility, essential steps of animal development such as fertilization and higher-order processes such as memory. We probed the function of calcium signalling in Drosophila wing imaginal discs through a combination of ex vivo and in vivo imaging and genetic analysis. Here we discover that wing discs display slow, long-range intercellular calcium waves (ICWs) when mechanically stressed in vivo or cultured ex vivo. These slow imaginal disc intercellular calcium waves (SIDICs) are mediated by the inositol-3-phosphate receptor, the endoplasmic reticulum (ER) calcium pump SERCA and the key gap junction component Inx2. The knockdown of genes required for SIDIC formation and propagation negatively affects wing disc recovery after mechanical injury. Our results reveal a role for ICWs in wing disc homoeostasis and highlight the utility of the wing disc as a model for calcium signalling studies. PMID:27503836

  18. Transventricular mitral valve operations.

    PubMed

    Joseph Woo, Y; McCormick, Ryan C

    2011-10-01

    We report transventricular mitral valve operations in 2 patients with severe mitral regurgitation and postinfarction left ventricular rupture and pseudoaneurysm. The first patient had direct papillary muscle involvement necessitating replacement of the mitral valve. The second patient had indirect mitral involvement allowing for placement of an atrial mitral annuloplasty ring via the left ventricle. Both patients showed no mitral valve regurgitation after replacement or repair and had uneventful postoperative recoveries. These cases demonstrate a feasible, alternative, transventricular approach to mitral valve replacement and repair.

  19. Effect of mechanical loading on electrical conductivity in porcine TMJ discs.

    PubMed

    Kuo, J; Wright, G J; Bach, D E; Slate, E H; Yao, H

    2011-10-01

    The objective of this study was to examine the impact of mechanical loading on solute transport in porcine temporomandibular joint (TMJ) discs using the electrical conductivity method. The electrical conductivity, as well as ion diffusivity, of TMJ discs was determined under confined compression with 3 strains in 5 disc regions. The average electrical conductivity over the 5 regions (mean ± SD) at 0% strain was 3.10 ± 0.68 mS/cm, decreased to 2.76 ± 0.58 mS/cm (-11.0%) at 10% strain, and 2.38 ± 0.55 mS/cm (-22.2%) at 20% compressive strain. Correspondingly, the average relative ion diffusivity (mean ± SD) at 0% strain was 0.273 ± 0.055, decreased to 0.253 ± 0.048 (-7.3%) at 10% strain, and 0.231 ± 0.048 (-15.4%) at 20% compressive strain. These results indicated that compressive strain impeded solute transport in the TMJ disc. Furthermore, our results showed that the transport properties of TMJ discs were region-dependent. The electrical conductivity and ion diffusivity in the anterior region were significantly higher than in the posterior region. This regional difference is likely due to the significant differences of tissue hydration between these 2 regions. This study provides important insight into the electrical and solute transport behaviors in TMJ discs under mechanical loading and aids in the understanding of TMJ pathophysiology related to tissue nutrition.

  20. Mitral valve repair for traumatic mitral regurgitation.

    PubMed

    Fujii, Taro; Kogure, Shuhei; Muro, Takashi; Okada, Yukikatsu

    2016-06-01

    Mitral valve injury after blunt chest trauma is a rare clinical condition. We describe a case of mitral valve repair for severe mitral regurgitation due to blunt chest trauma 5 years previously. A 22-year-old man was referred to our hospital for surgical correction of severe mitral regurgitation. Echocardiography demonstrated a partial tear of the anterolateral papillary muscle which lacerated to the apex. The entire anterolateral part of the mitral valve including the anterior commissure and posterior leaflets had prolapsed. Reimplantation of the papillary muscle to the posterior left ventricular wall and ring annuloplasty were successfully performed without residual regurgitation.

  1. Effect of mechanical strain on solute diffusion in human TMJ discs: an electrical conductivity study.

    PubMed

    Wright, Gregory J; Kuo, Jonathan; Shi, Changcheng; Bacro, Thierry R H; Slate, Elizabeth H; Yao, Hai

    2013-11-01

    This study investigated the effect of mechanical strain on solute diffusion in human TMJ discs (mean cadaver age 77.8) using the electrical conductivity method. The electrical conductivity, as well as small ion diffusivity, of male and female TMJ discs was determined under three compressive strains. In the male group, the average disc electrical conductivity (mean ± SD) at 0% strain was 5.14 ± 0.97 mS/cm, decreased to 4.50 ± 0.91 mS/cm (-12.3%) at 10% strain, and 3.93 ± 0.81 mS/cm (-23.5%) at 20% compressive strain. Correspondingly, the average disc relative ion diffusivity at 0% strain was 0.44 ± 0.08, decreased to 0.40 ± 0.08 (-8.9%) at 10% strain, and 0.36 ± 0.08 (-16.7%) at 20% compressive strain. In the female group, the average disc electrical conductivity at 0% strain was 5.84 ± 0.59 mS/cm, decreased to 5.01 ± 0.50 mS/cm (-14.2%) at 10% strain, and 4.33 ± 0.46 mS/cm (-25.8%) at 20% compressive strain. Correspondingly, the average disc relative ion diffusivity at 0% strain was 0.49 ± 0.05, decreased to 0.43 ± 0.04 (-11.3%) at 10% strain, and 0.39 ± 0.04 (-19.9%) at 20% compressive strain. The results indicated that mechanical strain significantly impeded solute diffusion through the disc. This mechanical strain effect was larger in the female than in the male human TMJ disc. This study may provide new insights into TMJ pathophysiology.

  2. The effects of a low international normalized ratio on thromboembolic and bleeding complications in patients with mechanical mitral valve replacement.

    PubMed

    Bal, Ugur; Aydinalp, Alp; Yilmaz, Kerem; Ozcalik, Emre; Hasirci, Senem; Atar, Ilyas; Gultekin, Bahadir; Sezgin, Atilla; Muderrisoglu, Haldun

    2014-05-07

    Mechanical heart valve replacement has an inherent risk of thromboembolic events (TEs). Current guidelines recommend an international normalized ratio (INR) of at least 2.5 after mechanical mitral valve replacement (MVR). This study aimed to evaluate the effects of a low INR (2.0-2.5) on thromboembolic and bleeding complications in patients with mechanical MVR on warfarin therapy. One hundred and thirty-five patients who underwent mechanical MVR were enrolled in this study. The end points of this study were defined as TEs (valve thrombosis, transient ischemic attack, stroke) and bleeding (all minor and major bleeding) complications. Patients were followed up for a mean of 39.6 months and the mean INR of the patients was calculated. After data collection, patients were divided into 3 groups according to their mean INR, as follows: group 1 (n = 34), INR <2.0; group 2 (n = 49), INR 2.0-2.5; and group 3 (n = 52), INR >2.5. A total of 22 events (10 [7.4%] thromboembolic and 12 [8.8%] bleeding events) occurred in the follow-up period. The mean INR was an independent risk factor for the development of TEs. Mean INR and neurological dysfunction were independent risk factors for the development of bleeding events. A statistically significant positive correlation was found between the log mean INR and all bleeding events, and a negative correlation was found between the log mean INR and all TEs. The total number of events was significantly lower in group 2 than in groups 1 and 3 (P = 0.036). This study showed that a target INRs of 2.0-2.5 are acceptable for preventing TEs and safe in terms of bleeding complications in patients with mechanical MVR.

  3. The effects of a low international normalized ratio on thromboembolic and bleeding complications in patients with mechanical mitral valve replacement

    PubMed Central

    2014-01-01

    Background Mechanical heart valve replacement has an inherent risk of thromboembolic events (TEs). Current guidelines recommend an international normalized ratio (INR) of at least 2.5 after mechanical mitral valve replacement (MVR). This study aimed to evaluate the effects of a low INR (2.0–2.5) on thromboembolic and bleeding complications in patients with mechanical MVR on warfarin therapy. Methods One hundred and thirty-five patients who underwent mechanical MVR were enrolled in this study. The end points of this study were defined as TEs (valve thrombosis, transient ischemic attack, stroke) and bleeding (all minor and major bleeding) complications. Patients were followed up for a mean of 39.6 months and the mean INR of the patients was calculated. After data collection, patients were divided into 3 groups according to their mean INR, as follows: group 1 (n = 34), INR <2.0; group 2 (n = 49), INR 2.0–2.5; and group 3 (n = 52), INR >2.5. Results A total of 22 events (10 [7.4%] thromboembolic and 12 [8.8%] bleeding events) occurred in the follow-up period. The mean INR was an independent risk factor for the development of TEs. Mean INR and neurological dysfunction were independent risk factors for the development of bleeding events. A statistically significant positive correlation was found between the log mean INR and all bleeding events, and a negative correlation was found between the log mean INR and all TEs. The total number of events was significantly lower in group 2 than in groups 1 and 3 (P = 0.036). Conclusions This study showed that a target INRs of 2.0–2.5 are acceptable for preventing TEs and safe in terms of bleeding complications in patients with mechanical MVR. PMID:24885719

  4. Enhanced expression of ROCK in left atrial myocytes of mitral regurgitation: a potential mechanism of myolysis.

    PubMed

    Chen, Huang-Chung; Chang, Jen-Ping; Chang, Tzu-Hao; Lin, Yu-Sheng; Huang, Yao-Kuang; Pan, Kuo-Li; Fang, Chih-Yuan; Chen, Chien-Jen; Ho, Wan-Chun; Chen, Mien-Cheng

    2015-05-09

    Severe mitral regurgitation (MR) may cause myolysis in the left atrial myocytes. Myolysis may contribute to atrial enlargement. However, the relationship between Rho-associated kinase (ROCK) and myolysis in the left atrial myocytes of MR patients remain unclear. This study comprised 22 patients with severe MR [12 with atrial fibrillation (AF) and ten in sinus rhythm]. Left atrial appendage tissues were obtained during surgery. Normal left atrial tissues were purchased. Immunofluorescence histochemical and immunoblotting studies were performed. The expression of ROCK2 in the myolytic left atrial myocytes of MR AF patients (p = 0.009) and MR sinus patients (p = 0.011) were significantly higher than that of the normal subjects. Similarly, the expression of ROCK1 in the myolytic left atrial myocytes of MR AF patients was significantly higher than that of the normal subjects (p = 0.010), and the expression of ROCK1 in the myolytic left atrial myocytes of MR sinus patients was higher than that of the normal subjects (p = 0.091). Immunofluorescence study revealed significant co-localization and juxtaposition of ROCK2 and cleaved caspase-3 in the left atrial myocytes both in the MR AF group (Pearson's coefficient = 0.74 ± 0.03) and the MR sinus group (Pearson's coefficient = 0.73 ± 0.02). Similarly, immunofluorescence study revealed significant co-localization and juxtaposition of ROCK1 and cleaved caspase-3 in the left atrial myocytes both in the MR AF group (Pearson's coefficient = 0.65 ± 0.03) and the MR sinus group (Pearson's coefficient = 0.65 ± 0.03). Correlation analysis demonstrated that there was a significant direct relationship between the expression of ROCK2 in the myolytic left atrial myocytes and left atrial diameter in the MR patients (p = 0.041; r = 0.440). Moreover, the ratio of phosphorylated myosin-binding subunit of myosin light chain phosphatase (pMBS)/total MBS of left atrial tissues was significantly higher in the MR AF group (p < 0.04) and the

  5. Role of load history in intervertebral disc mechanics and intradiscal pressure generation.

    PubMed

    Hwang, David; Gabai, Adam S; Yu, Miao; Yew, Alvin G; Hsieh, Adam H

    2012-01-01

    Solid-fluid interactions play an important role in mediating viscoelastic behaviour of biological tissues. In the intervertebral disc, water content is governed by a number of factors, including age, disease and mechanical loads, leading to changes in stiffness characteristics. We hypothesized that zonal stress distributions depend on load history, or the prior stresses experienced by the disc. To investigate these effects, rat caudal motion segments were subjected to compressive creep biomechanical testing in vitro using a protocol that consisted of two phases: a Prestress Phase (varied to represent different histories of load) followed immediately by an Exertion Phase, identical across all Prestress groups. Three analytical models were used to fit the experimental data in order to evaluate load history effects on gross and zonal disc mechanics. Model results indicated that while gross transient response was insensitive to load history, there may be changes in the internal mechanics of the disc. In particular, a fluid transport model suggested that the role of the nucleus pulposus in resisting creep during Exertion depended on Prestress conditions. Separate experiments using similarly defined load history regimens were performed to verify these predictions by measuring intradiscal pressure with a fibre optic sensor. We found that the ability for intradiscal pressure generation was load history-dependent and exhibited even greater sensitivity than predicted by analytical models. A 0.5 MPa Exertion load resulted in 537.2 kPa IDP for low magnitude Prestress compared with 373.7 kPa for high magnitude Prestress. Based on these measurements, we developed a simple model that may describe the pressure-shear environment in the nucleus pulposus. These findings may have important implications on our understanding of how mechanical stress contributes to disc health and disease etiology.

  6. Unusual redo mitral valve replacement for bleeding in Glanzmann thrombasthenia.

    PubMed

    Garcia-Villarreal, Ovidio A; Fernández-Ceseña, Ernesto; Solano-Ricardi, Mercedes; Aguilar-García, Alma L; Vega-Hernández, Raquel; Del Angel-Soto, Gustavo

    2016-01-01

    We report the case of 23-year-old man with mitral valve regurgitation and Glanzmann thrombasthenia, who underwent mechanical mitral valve replacement. Warfarin therapy was devastating, causing bilateral hemothorax, pericardial effusion, gastrointestinal bleeding, and hematuria. Redo mitral valve replacement with a biological prosthesis was required to resolve this critical situation. To our knowledge, this is the first report of mitral valve replacement in Glanzmann thrombasthenia, highlighting the danger of oral anticoagulation in this pathology.

  7. Mechanical testing and modelling of carbon-carbon composites for aircraft disc brakes

    NASA Astrophysics Data System (ADS)

    Bradley, Luke R.

    The objective of this study is to improve the understanding of the stress distributions and failure mechanisms experienced by carbon-carbon composite aircraft brake discs using finite element (FE) analyses. The project has been carried out in association with Dunlop Aerospace as an EPSRC CASE studentship. It therefore focuses on the carbon-carbon composite brake disc material produced by Dunlop Aerospace, although it is envisaged that the approach will have broader applications for modelling and mechanical testing of carbon-carbon composites in general. The disc brake material is a laminated carbon-carbon composite comprised of poly(acrylonitrile) (PAN) derived carbon fibres in a chemical vapour infiltration (CVI) deposited matrix, in which the reinforcement is present in both continuous fibre and chopped fibre forms. To pave the way for the finite element analysis, a comprehensive study of the mechanical properties of the carbon-carbon composite material was carried out. This focused largely, but not entirely, on model composite materials formulated using structural elements of the disc brake material. The strengths and moduli of these materials were measured in tension, compression and shear in several orientations. It was found that the stress-strain behaviour of the materials were linear in directions where there was some continuous fibre reinforcement, but non-linear when this was not the case. In all orientations, some degree of non-linearity was observed in the shear stress-strain response of the materials. However, this non-linearity was generally not large enough to pose a problem for the estimation of elastic moduli. Evidence was found for negative Poisson's ratio behaviour in some orientations of the material in tension. Additionally, the through-thickness properties of the composite, including interlaminar shear strength, were shown to be positively related to bulk density. The in-plane properties were mostly unrelated to bulk density over the range of

  8. Effect of loading rate and hydration on the mechanical properties of the disc.

    PubMed

    Race, A; Broom, N D; Robertson, P

    2000-03-15

    The mechanical response of bovine intervertebral discs to axial compression at different loading rates and hydration levels was quantified. To quantify the effects of hydration and loading rate on the mechanical response of the intervertebral disc to compressive axial load. The disc is known to be viscoelastic, but there are few experimental data showing the effect of loading rate and hydration on its response to compression. Hydration level reduced by creep-loading from a fully hydrated starting point. Four groups were tested: Group A: fully hydrated (n = 5), six loading rates, from 0.3 kPa/sec to 30 MPa/sec; Group B: after 30 minutes of creep (n = 4); and Group C: after 2 hours of creep (n = 4) under a static load of 1 MPa, loading rates 3 MPa/sec, 30 kPa/sec, and 0.3 kPa/sec; Group D: at 5-minute intervals, during an 8-hour period of creep (n = 3) under a static load of 1 MPa, loading rate 3 MPa/sec. Data normalized by disc area and height: nominal stress, strain, and modulus calculated. Group A: Modulus increased with load and rate of loading, with significant differences among the lower three loading rates. The highest three loading rates were significantly different from the lower rates, but not from each other. Group B: At the two higher loading rates, modulus was greater than in group A. At the lowest loading rate the modulus was similar to that in Group A. Group C: At the highest loading rate, the modulus was less than that of Groups A and B. At the lower two loading rates, the modulus was similar to that in Group A. Group D: The modulus increased in the first 30 minutes and decreased in the interval from 60 to 480 minutes. Intervertebral disc compressive mechanical properties are significantly dependent on loading rate and hydration.

  9. Modeling the Mitral Valve

    NASA Astrophysics Data System (ADS)

    Kaiser, Alexander

    2016-11-01

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

  10. Mechanism of parathyroid hormone-mediated suppression of calcification markers in human intervertebral disc cells.

    PubMed

    Madiraju, P; Gawri, R; Wang, H; Antoniou, J; Mwale, F

    2013-05-02

    In degenerative intervertebral discs (IVD), type X collagen (COL X) expression (associated with hypertrophic differentiation) and calcification has been demonstrated. Suppression of COL X expression and calcification during disc degeneration can be therapeutic. In the present study we investigated the potential of human parathyroid hormone 1-34 (PTH) in suppressing indicators of calcification potential (alkaline phosphatase (ALP), Ca(2+), inorganic phosphate (Pi)), and COL X expression. Further, we sought to elucidate the mechanism of PTH action in annulus fibrosus (AF) and nucleus pulposus (NP) cells from human lumbar IVDs with moderate to advanced degeneration. Mitogen activated protein kinase (MAPK) signalling and alterations in the markers of calcification potential were analysed. PTH increased type II collagen (COL II) expression in AF (~200 %) and NP cells (~163 %) and decreased COL X levels both in AF and NP cells (~75 %). These changes in the expression of collagens were preceded by MAPK phosphorylation, which was increased in both AF and NP cells by PTH after 30 min. MAPK signalling inhibitor U0126 and protein kinase-A inhibitor H-89 DCH attenuated PTH stimulated COL II expression in both cell types. PTH decreased ALP activity and increased Ca(2+) release only in NP cells. The present study demonstrates that PTH can potentially retard IVD degeneration by stimulating matrix synthesis and suppressing markers of calcification potential in degenerated disc cells via both MAPK and PKA signalling pathways. Inhibition of further mineral deposition may therefore be a viable therapeutic option for improving the status of degenerating discs.

  11. Novel Annular and Subvalvular Enlargement in Congenital Mitral Valve Replacement.

    PubMed

    Carroll, Nels D; Beers, Kevin M; Maldonado, Elaine M; Calhoon, John H; Husain, S Adil

    2016-09-01

    Reparative procedures are not always feasible in congenitally abnormal mitral valves. Mechanical prosthesis has been accepted as the choice for valve replacement in the pediatric population. This report describes a case of congenital mitral valve disease requiring mitral valve replacement. The infant's mitral valve annulus was not amenable to placement of the smallest available mechanical prosthesis. The approach used here for annular and subvalvular enlargement facilitated implantation of a larger prosthesis for congenital mitral valve replacement. Five-year outcomes in a single patient may indicate broader applicability and avoidance of patient-prosthesis mismatch. Copyright © 2016 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

  12. Aurora on Uranus - A Faraday disc dynamo mechanism

    NASA Astrophysics Data System (ADS)

    Hill, T. W.; Dessler, A. J.; Rassbach, M. E.

    1983-10-01

    A mechanism is proposed whereby the solar wind flowing past the magnetosphere of Uranus causes a Faraday disk dynamo topology to be established and power to be extracted from the kinetic energy of rotation of Uranus. An immediate consequence of this dynamo is the generation of Birkeland currents that flow in and out of the sunlit polar cap with the accompanying production of polar aurora. The power extracted from planetary rotation is calculated as a function of planetary dipole magnetic moment and the ionospheric conductivity of Uranus. For plausible values of ionospheric conductivity, the observed auroral power requires a magnetic moment corresponding to a surface equatorial field of the order of 4 Gauss, slightly larger than the value 1.8 Gauss given by the empirical 'magnetic Bodes law'.

  13. Transcatheter mitral valve repair therapies for primary and secondary mitral regurgitation.

    PubMed

    Al Amri, Ibtihal; van der Kley, Frank; Schalij, Martin J; Ajmone Marsan, Nina; Delgado, Victoria

    2015-03-01

    Mitral regurgitation is one of the most prevalent valvular heart diseases and its prevalence is related to population aging. Elderly patients with age-associated co-morbidities have an increased risk for conventional mitral valve surgery. Transcatheter mitral valve repair has emerged as a feasible and safe alternative in patients with contraindications for surgery or high operative risk. Several transcatheter mitral repair technologies have been developed during the last decade. While the development of some devices was abandoned due to suboptimal results, others demonstrated to be safe and effective and have been included in current practice guidelines. Not all technologies are suitable for all mitral anatomies and regurgitation mechanisms. Therefore, accurate evaluation of mitral valve anatomy and function are pivotal to the success of these therapies. Cardiac imaging plays a central role in selecting patients, guiding the procedure and evaluating the durability of the repair at follow-up.

  14. Left atrial mechanical functions in chronic primary mitral regurgitation patients: a velocity vector imaging-based study

    PubMed Central

    Yurdakul, Selen; Yıldirimtürk, Özlem

    2014-01-01

    Introduction Assessment of the left atrium (LA) mechanical function provides further information on the level of cardiac compensation. We aimed to evaluate LA function using a strain imaging method: velocity vector imaging (VVI) in chronic primary mitral regurgitation (MR). Material and methods We recruited 48 patients with chronic, isolated, moderate to severe MR (54.70 ±15.35 years and 56% male) and 30 age- and sex-matched healthy controls (56.52 ±15.95 years and 56% male). The LA volumes during reservoir (RV), conduit (CV) and contractile phases (AV) were measured. Global strain (S), systolic strain rate (SRs), early diastolic (ESRd) and late diastolic strain rate (LSRd) were calculated. Results LA RV (50 ±18.7 to 37.9 ±5.9; p = 0.0001), CV (43.1 ±29 to 21 ±2.56; p = 0.0001), and AV (17.9 ±13.5 to 10.9 ±1.9; p = 0.006) were increased in MR patients. The LA reservoir phase strain was 16.2 ±8.1% in the MR group and 51.1 ±5.7% in the control group (p = 0.0001). The LA SRs (1.01 ±0.52 s–1 for MR and 2.1 ±0.22 s–1 for controls; p = 0.0001), LA ESRd (0.83 ±0.34 s–1 for MR and 2.26 ±0.17 s–1 for controls; p = 0.0001) and LA LSRd (0.76 ±0.24 s–1 for MR and 2.2 ±0.26 s–1 for controls; p = 0.0001) were impaired in MR patients. Conclusions The LA deformation indices may be used as adjunctive parameters to determine LA dysfunction in chronic primary MR. PMID:25097574

  15. Two-dimensional FSI simulation of closing dynamics of a tilting disc mechanical heart valve

    PubMed Central

    Govindarajan, V.; Udaykumar, H.S.; Herbertson, L. H.; Deutsch, S.; Manning, K. B.; Chandran, K.B.

    2010-01-01

    The fluid dynamics during valve closure resulting in high shear flows and large residence times of particles has been implicated in platelet activation and thrombus formation in mechanical heart valves. Our previous studies with bi-leaflet valves have shown that large shear stresses induced in the gap between the leaflet edge and the valve housing results in relatively high platelet activation levels whereas flow between the leaflets results in shed vortices not conducive to platelet damage. In this study we compare the result of closing dynamics of a tilting disc valve with that of a bi-leaflet valve. The two-dimensional fluid-structure interaction analysis of a tilting disc valve closure mechanics is performed with a fixed grid Cartesian mesh flow solver with local mesh refinement, and a Lagrangian particle dynamic analysis for computation of potential for platelet activation. Throughout the simulation the flow remains in the laminar regime and the flow through the gap width is marked by the development of a shear layer which separates from the leaflet downstream of the valve. Zones of re-circulation are observed in the gap between the leaflet edge and the valve housing on the major orifice region of the tilting disc valve and are seen to be migrating towards the minor orifice region. Jet flow is observed at the minor orifice region and a vortex is formed which sheds in the direction of fluid motion as observed in experiments using PIV measurements. The activation parameter computed for the tilting disc valve, at the time of closure was found to be 2.7 times greater than that of the bi-leaflet mechanical valve and was found to be in the vicinity of the minor orifice region mainly due to the migration of vortical structures from the major to the minor orifice region during the leaflet rebound of the closing phase. PMID:20209095

  16. An Unbiased Analysis of Candidate Mechanisms for the Regulation of Drosophila Wing Disc Growth

    PubMed Central

    Vollmer, Jannik; Iber, Dagmar

    2016-01-01

    The control of organ size presents a fundamental open problem in biology. A declining growth rate is observed in all studied higher animals, and the growth limiting mechanism may therefore be evolutionary conserved. Most studies of organ growth control have been carried out in Drosophila imaginal discs. We have previously shown that the area growth rate in the Drosophila eye primordium declines inversely proportional to the increase in its area, which is consistent with a dilution mechanism for growth control. Here, we show that a dilution mechanism cannot explain growth control in the Drosophila wing disc. We computationally evaluate a range of alternative candidate mechanisms and show that the experimental data can be best explained by a biphasic growth law. However, also logistic growth and an exponentially declining growth rate fit the data very well. The three growth laws correspond to fundamentally different growth mechanisms that we discuss. Since, as we show, a fit to the available experimental growth kinetics is insufficient to define the underlying mechanism of growth control, future experimental studies must focus on the molecular mechanisms to define the mechanism of growth control. PMID:27995964

  17. Mitral Valve Disease

    MedlinePlus

    ... Tricuspid Valve Disease Cardiac Rhythm Disturbances Thoracic Aortic Aneurysm Pediatric and Congenital Heart Disease Heart abnormalities that are ... Transplantation End-stage Lung Disease Adult Lung Transplantation Pediatric Lung ... Aortic Aneurysm Mitral Valve Disease Overview The mitral valve is ...

  18. Degenerative mitral valve regurgitation: best practice revolution

    PubMed Central

    Adams, David H.; Rosenhek, Raphael; Falk, Volkmar

    2010-01-01

    Degenerative mitral valve disease often leads to leaflet prolapse due to chordal elongation or rupture, and resulting in mitral valve regurgitation. Guideline referral for surgical intervention centres primarily on symptoms and ventricular dysfunction. The recommended treatment for degenerative mitral valve disease is mitral valve reconstruction, as opposed to valve replacement with a bioprosthetic or mechanical valve, because valve repair is associated with improved event free survival. Recent studies have documented a significant number of patients are not referred in a timely fashion according to established guidelines, and when they are subjected to surgery, an alarming number of patients continue to undergo mitral valve replacement. The debate around appropriate timing of intervention for asymptomatic severe mitral valve regurgitation has put additional emphasis on targeted surgeon referral and the need to ensure a very high rate of mitral valve repair, particularly in the non-elderly population. Current clinical practice remains suboptimal for many patients, and this review explores the need for a ‘best practice revolution’ in the field of degenerative mitral valve regurgitation. PMID:20624767

  19. Effect of mechanical load and thickness profile on creep in a rotating disc by using Seth's transition theory

    NASA Astrophysics Data System (ADS)

    Thakur, Pankaj; Shahi, Shivdev; Gupta, Nishi; Singh, S. B.

    2017-07-01

    Rotating disc is a common component in turbines, rotors, compressors and other engineering components. In this paper efforts have been made to evaluate creep stresses and strain rate in a rotating disc with respect to changes in mechanical load and thickness profile. Seth's theory of transition has been used in this study. It has been observed that stresses increases with increase in mechanical load and maximum value of strain rate further increases at the internal surface for compressible materials. It is concluded that, rotating disc is likely to fracture by cleavage close to the shaft at the bore.

  20. The three-dimension model for the rock-breaking mechanism of disc cutter and analysis of rock-breaking forces

    NASA Astrophysics Data System (ADS)

    Zhang, Zhao-Huang; Sun, Fei

    2012-06-01

    To study the rock deformation with three-dimensional model under rolling forces of disc cutter, by carrying out the circular-grooving test with disc cutter rolling around on the rock, the rock mechanical behavior under rolling disc cutter is studied, the mechanical model of disc cutter rolling around the groove is established, and the theory of single-point and double-angle variables is proposed. Based on this theory, the physics equations and geometric equations of rock mechanical behavior under disc cutters of tunnel boring machine (TBM) are studied, and then the balance equations of interactive forces between disc cutter and rock are established. Accordingly, formulas about normal force, rolling force and side force of a disc cutter are derived, and their validity is studied by tests. Therefore, a new method and theory is proposed to study rock-breaking mechanism of disc cutters.

  1. Mitral Valve Prolapse

    PubMed Central

    Rosser, Walter W.

    1992-01-01

    The author discusses the pathophysiology of mitral valve prolapse and provides guidelines to identify and treat low-to high-risk mitral valve prolapse. An approach to diagnosing bacterial endocarditis and its prophylaxis are also discussed. The author reviews mitral valve prolapse syndrome and the risk of sudden death.

  2. Björk-Shiley strut fracture and disc escape: literature review and a method of disc retrieval.

    PubMed

    Hendel, P N

    1989-03-01

    Embolization of a prosthetic valve poppet is a rare but life-threatening event. It was reported sporadically before the introduction of the Björk-Shiley 70-degree convexoconcave prosthesis in 1980. Since that time, there have been a large number of reported mechanical failures with disc escape. The rate for the 29-mm to 33-mm mitral valves is estimated as 5.2%. In 29 of 35 patients (including the 2 presented here) in whom the site of disc lodgment could be determined, the disc was in the descending or abdominal aorta. Fifteen of these patients died. Six survivors had the disc removed at the same operation and 6 at a later operation. In 2 patients, the disc was not removed. In 2 patients in whom the disc was not removed initially, it was thought to contribute to postoperative complications. Two more cases of structural failure of the Björk-Shiley convexoconcave prosthesis are presented. A transpericardial approach to the descending aorta on bypass is described. It allows easy removal of the disc and eliminates the need for a second operation.

  3. Spatial and structural dependence of mechanical properties of porcine intervertebral disc.

    PubMed

    Causa, F; Manto, L; Borzacchiello, A; De Santis, R; Netti, P A; Ambrosio, L; Nicolais, L

    2002-12-01

    Structure-function relationship of natural tissues is crucial to design a device mimicking the structures present in human body. For this purpose, to provide guidelines to design an intervertebral disc (IVD) substitute, in this study the influence of the spatial location and structural components on the mechanical properties of porcine IVD was investigated. Local compressive stiffness (LCS) was measured on the overall disc, also constrained between the two adjacent vertebrae: the dependence on the lumbar position was evaluated. The compliance values in the anterior position (A) were higher than both in the central posterior (CP) and in the lateral-posterior (RP, LP) locations. The values of Young's Modulus (74.67+/-6.03 MPa) and compression break load (1.36x10(4)+/-0.09x10(4)N) of the disc were also evaluated by distributed compression test. The NP rheological behavior was typical of weak-gels, with elastic modulus G' always higher than viscous modulus G" all over the frequency range investigated (G' and G" respectively equal to 320 and 85 Pa at 1 Hz) and with the moduli trends were almost parallel to each other.

  4. Dynamics and Mechanical Stability of the Developing Dorsoventral Organizer of the Wing Imaginal Disc

    PubMed Central

    Sagués, Francesc; Casademunt, Jaume

    2011-01-01

    Shaping the primordia during development relies on forces and mechanisms able to control cell segregation. In the imaginal discs of Drosophila the cellular populations that will give rise to the dorsal and ventral parts on the wing blade are segregated and do not intermingle. A cellular population that becomes specified by the boundary of the dorsal and ventral cellular domains, the so-called organizer, controls this process. In this paper we study the dynamics and stability of the dorsal-ventral organizer of the wing imaginal disc of Drosophila as cell proliferation advances. Our approach is based on a vertex model to perform in silico experiments that are fully dynamical and take into account the available experimental data such as: cell packing properties, orientation of the cellular divisions, response upon membrane ablation, and robustness to mechanical perturbations induced by fast growing clones. Our results shed light on the complex interplay between the cytoskeleton mechanics, the cell cycle, the cell growth, and the cellular interactions in order to shape the dorsal-ventral organizer as a robust source of positional information and a lineage controller. Specifically, we elucidate the necessary and sufficient ingredients that enforce its functionality: distinctive mechanical properties, including increased tension, longer cell cycle duration, and a cleavage criterion that satisfies the Hertwig rule. Our results provide novel insights into the developmental mechanisms that drive the dynamics of the DV organizer and set a definition of the so-called Notch fence model in quantitative terms. PMID:21980267

  5. Dynamics and mechanical stability of the developing dorsoventral organizer of the wing imaginal disc.

    PubMed

    Canela-Xandri, Oriol; Sagués, Francesc; Casademunt, Jaume; Buceta, Javier

    2011-09-01

    Shaping the primordia during development relies on forces and mechanisms able to control cell segregation. In the imaginal discs of Drosophila the cellular populations that will give rise to the dorsal and ventral parts on the wing blade are segregated and do not intermingle. A cellular population that becomes specified by the boundary of the dorsal and ventral cellular domains, the so-called organizer, controls this process. In this paper we study the dynamics and stability of the dorsal-ventral organizer of the wing imaginal disc of Drosophila as cell proliferation advances. Our approach is based on a vertex model to perform in silico experiments that are fully dynamical and take into account the available experimental data such as: cell packing properties, orientation of the cellular divisions, response upon membrane ablation, and robustness to mechanical perturbations induced by fast growing clones. Our results shed light on the complex interplay between the cytoskeleton mechanics, the cell cycle, the cell growth, and the cellular interactions in order to shape the dorsal-ventral organizer as a robust source of positional information and a lineage controller. Specifically, we elucidate the necessary and sufficient ingredients that enforce its functionality: distinctive mechanical properties, including increased tension, longer cell cycle duration, and a cleavage criterion that satisfies the Hertwig rule. Our results provide novel insights into the developmental mechanisms that drive the dynamics of the DV organizer and set a definition of the so-called Notch fence model in quantitative terms.

  6. The Impact of Fluid Inertia on In Vivo Estimation of Mitral Valve Leaflet Constitutive Properties and Mechanics.

    PubMed

    Bark, David L; Dasi, Lakshmi P

    2016-05-01

    We examine the influence of the added mass effect (fluid inertia) on mitral valve leaflet stress during isovolumetric phases. To study this effect, oscillating flow is applied to a flexible membrane at various frequencies to control inertia. Resulting membrane strain is calculated through a three-dimensional reconstruction of markers from stereo images. To investigate the effect in vivo, the analysis is repeated on a published dataset for an ovine mitral valve (Journal of Biomechanics 42(16): 2697-2701). The membrane experiment demonstrates that the relationship between pressure and strain must be corrected with a fluid inertia term if the ratio of inertia to pressure differential approaches 1. In the mitral valve, this ratio reaches 0.7 during isovolumetric contraction for an acceleration of 6 m/s(2). Acceleration is reduced by 72% during isovolumetric relaxation. Fluid acceleration also varies along the leaflet during isovolumetric phases, resulting in spatial variations in stress. These results demonstrate that fluid inertia may be the source of the temporally and spatially varying stiffness measurements previously seen through inverse finite element analysis of in vivo data during isovolumetric phases. This study demonstrates that there is a need to account for added mass effects when analyzing in vivo constitutive relationships of heart valves.

  7. Comparison of the occurrence of thromboembolic and bleeding complications in patients with mechanical heart valve prosthesis with one and two leaflets in the mitral position

    PubMed Central

    de Campos, Nelson Leonardo Kerdahi Leite

    2014-01-01

    Introduction Patients with mechanical heart valve prostheses must continuously be treated with oral anticoagulants to prevent thromboembolic events related to prosthetesis. These patients should be continually evaluated for the control of oral anticoagulation. Objective To compare the occurrence of thromboembolic and hemorragic complications in patients with mechanical heart valve prosthesis with one (mono) and two (bi) leaflets in the mitral position in anticoagulant therapy. Methods We studied the 10-year interval, 117 patients with prosthesis in the mitral position, 48 with prosthetic single leaflet and 69 with two leaflets. We evaluated the occurrence of thromboembolic and hemorrhagic major and minor degree under gravity. The results are presented in an actuarial study and the frequency of occurrence of linear events. Results The actuarial survival curves showed that over time, patients with prosthetic heart valve with one leaflet were less free of thromboembolic complications than patients with two leaflet prosthetic valve, while the latter (two leaflet) were less free of hemorrhagic accidents. The linearized frequency of occurrence of thromboembolism were higher in patients with mono leaflet prosthesis. Bleeding rates were higher for patients with bi leaflet prosthetic valve. Conclusion Patients with mono leaflet prosthetic heart valve showed that they are more prone to the occurrence of serious thromboembolic events compared to those with bi leaflet prosthetic valve. Patients with bi leaflet prosthetic valve had more bleeding than patients with mono leaflet prosthetic valve, however this difference was restricted to the bleeding of minor nature. PMID:24896164

  8. Mitral Valve Annuloplasty

    PubMed Central

    Rausch, Manuel K.; Bothe, Wolfgang; Kvitting, John-Peder Escobar; Swanson, Julia C.; Miller, D. Craig; Kuhl, Ellen

    2012-01-01

    Mitral valve annuloplasty is a common surgical technique used in the repair of a leaking valve by implanting an annuloplasty device. To enhance repair durability, these devices are designed to increase leaflet coaptation, while preserving the native annular shape and motion; however, the precise impact of device implantation on annular deformation, strain, and curvature is unknown. Here we quantify how three frequently used devices significantly impair native annular dynamics. In controlled in vivo experiments, we surgically implanted eleven flexible-incomplete, eleven semi-rigid-complete, and twelve rigid-complete devices around the mitral annuli of 34 sheep, each tagged with 16 equally-spaced tantalum markers. We recorded four-dimensional marker coordinates using biplane videofluoroscopy, first with device and then without, which were used to create mathematical models using piecewise cubic splines. Clinical metrics (characteristic anatomical distances) revealed significant global reduction in annular dynamics upon device implantation. Mechanical metrics (strain and curvature fields) explained this reduction via a local loss of anterior dilation and posterior contraction. Overall, all three devices unfavorably reduced annular dynamics. The flexible-incomplete device, however, preserved native annular dynamics to a larger extent than the complete devices. Heterogeneous strain and curvature profiles suggest the need for heterogeneous support, which may spawn more rational design of annuloplasty devices using design concepts of functionally graded materials. PMID:22037916

  9. 1990 Volvo Award in experimental studies. The dependence of intervertebral disc mechanical properties on physiologic conditions.

    PubMed

    Keller, T S; Holm, S H; Hansson, T H; Spengler, D M

    1990-08-01

    In vivo creep-recovery and disc pressure measurements were performed on the lumbar spine of immature and mature swine. The creep-recovery measurements were performed using a custom materials testing apparatus designed to apply static or dynamic loads to the spine of anesthetized animals. A series of three separate experiments were performed to assess the effects of: (I) animal death, (II) graded injury to the disc anulus, and (III) respiratory mechanics on the biomechanical response of the porcine L1-L3 vertebral unit (VU). In Experiments I and II, creep rate, modulus, and viscosity parameters were computed using a three-parameter solid rheological analysis of the displacement-time response recorded during the application of a 300-N load. In Experiment III, the effects of respiratory volume and frequency changes on disc pressure were assessed in the unloaded, statically loaded, and immobilized porcine VU. Our results indicated that the adult VU tended to be stiffer, deform or creep more slowly, and had a significantly higher viscosity than the VU of immature pigs. The results of Experiment I demonstrated that the biomechanical response for the VU was significantly altered by the death of the animal; the VU of the living animal (adolescent or mature) was more compliant and deformed at a faster rate than the VU of the same animal after death. Disc injury produced changes in stiffness, viscosity, and creep rate analogous to that of aging, and on the basis of the graded injuries created in this study, it appears that a small defect in the annulus is just as deleterious as removing a large section of anular material. The results of Experiment III indicated that respiration plays an important role in the normal, in vivo mechanical and nutritional behavior of the porcine VU. Altogether, these results demonstrate that, in the absence of normal physiologic conditions, one may not be able to reliably predict the mechanical response of the lumbar spine, and suggest that

  10. Augmentation improves human cadaveric vertebral body compression mechanics for lumbar total disc replacement.

    PubMed

    Yoder, Jonathon H; Auerbach, Joshua D; Maurer, Philip M; Erbe, Erik M; Entrekin, Dean; Balderston, Richard A; Bertagnoli, Rudolf; Elliott, Dawn M

    2010-04-20

    Cadaveric biomechanical study. To quantify the effects of vertebral body augmentation on biomechanics under axial compression by a total disc replacement (TDR) implant. TDR is a surgical alternative to lumbar spinal fusion to treat degenerative disc disease. Osteoporosis in the adjacent vertebrae to the interposed TDR may lead to implant subsidence or vertebral body fracture. Vertebral augmentation is used to treat osteoporotic compression fracture. This study sought to evaluate whether vertebral augmentation improves biomechanics under TDR axial loading. Forty-five L1-L5 lumbar vertebral body segments with intact posterior elements were used. Peripheral quantitative computed tomography scans were performed to determine bone density, and specimens were block-randomized by bone density into augmentation and control groups. A semiconstrained keeled lumbar disc replacement device was implanted, providing 50% endplate coverage. Vertebral augmentation of 17.6% +/- 0.9% vertebral volume fill with Cortoss was performed on the augmentation group. All segments underwent axial compression at a rate of 0.2 mm/s to 6 mm. The load-displacement response for all specimens was nonlinear. Subfailure mechanical properties with augmentation were significantly different from control; in all cases, the augmented group was 2 times higher than control. At failure, the maximum load and stiffness with augmentation was not significantly different from control. The maximum apparent stress and modulus with augmentation were 2 times and 1.3 times greater than control, respectively. The subfailure stress and apparent modulus with augmentation were moderately correlated with bone density whereas the control subfailure properties were not. The augmented maximum stress was not correlated with bone density, whereas the control was weakly correlated. The maximum apparent modulus was moderately correlated with bone density for both the augmented and the control groups. Augmentation improved the

  11. Augmentation Improves Human Cadaveric Vertebral Body Compression Mechanics For Lumbar Total Disc Replacement

    PubMed Central

    Yoder, Jonathon H.; Auerbach, Joshua D.; Maurer, Philip M.; Erbe, Erik M.; Entrekin, Dean; Balderston, Richard A.; Bertagnoli, Rudolf; Elliott, Dawn M.

    2012-01-01

    Study Design Cadaveric biomechanical study. Objectives Quantify the effects of vertebral body augmentation on biomechanics under axial compression by a total disc replacement (TDR) implant. Summary of Background Data TDR is a surgical alternative to lumbar spinal fusion to treat degenerative disc disease. Osteoporosis in the adjacent vertebrae to the interposed TDR may lead to implant subsidence or vertebral body fracture. Vertebral augmentation is used to treat osteoporotic compression fracture. The study sought to evaluate whether vertebral augmentation improves biomechanics under TDR axial loading. Methods Forty-five L1-L5 lumbar vertebral body segments with intact posterior elements were used. Peripheral quantitative computed tomography scans were performed to determine bone density, block randomizing specimens by bone density into augmentation and control groups. A semi-constrained keeled lumbar disc replacement device was implanted providing 50% endplate coverage. Vertebral augmentation of 17.6 ± 0.9% vertebral volume fill with Cortoss was performed on augmentation group. All segments underwent axial compression at a rate of 0.2 mm/s to 6mm. Results The load-displacement response for all specimens was non-linear. Subfailure mechanical properties with augmentation were significantly different from control; in all cases the augmented group was 2× higher than control. At failure, the maximum load and stiffness with augmentation was not significantly different from control. The maximum apparent stress and modulus with augmentation were 2× and 1.3× greater than control, respectively. The subfailure stress and apparent modulus with augmentation was moderately correlated with bone density while the control subfailure properties were not. The augmented maximum stress was not correlated with bone density, while the control was weakly correlated. The maximum apparent modulus was moderately correlated with bone density for both the augmented and control groups

  12. Comparative Role of Disc Degeneration and Ligament Failure on Functional Mechanics of the Lumbar Spine

    PubMed Central

    Ellingson, Arin M.; Shaw, Miranda N.; Giambini, Hugo; An, Kai-Nan

    2015-01-01

    Understanding spinal kinematics is essential for distinguishing between pathological conditions of spine disorders, which ultimately lead to low back pain. It’s of high importance to understand how changes in mechanical properties affect the response of the lumbar spine, specifically in an effort to differentiate those associated with disc degeneration from ligamentous changes, allowing for more precise treatment strategies. To do this the goals of this study were twofold: 1) develop and validate a finite element (FE) model of the lumbar spine and 2) systematically alter the properties of the intervertebral disc and ligaments to define respective roles in functional mechanics. A three-dimensional non-linear FE model of the lumbar spine (L3-Sacrum) was developed and validated for pure moment bending. Disc degeneration and sequential ligament failure was modeled. Intersegmental range of motion (ROM) and bending stiffness was measured. The prediction of the FE model to moment loading in all three planes of bending showed very good agreement, where global and intersegmental ROM and bending stiffness of the model fell within one standard deviation of the in vitro results. Degeneration decreased ROM for all directions. Stiffness increased for all directions except axial rotation, where it initially increased then decreased for moderate and severe degeneration, respectively. Incremental ligament failure produced increased ROM and decreased stiffness. This effect was much more pronounced for all directions except lateral bending, which is minimally impacted by ligaments. These results indicate that lateral bending may be more apt to detect the subtle changes associated with degeneration, without being masked by associated changes of surrounding stabilizing structures. PMID:26404463

  13. Thermo-Mechanical Behaviour of Turbine Disc Assembly in the Presence of Residual Stresses

    NASA Astrophysics Data System (ADS)

    Maricic, Luke Anthony

    A comprehensive three dimensional coupled thermo-mechanical finite element study is performed on turbine blade attachments in gas turbine engines. The effects of the self-generated centrifugal forces of the disc and the associated blades, thermal loads, and shot peening residual are all considered in this thesis. Three aspects of the work were accordingly examined. The first was concerned with the coupled thermo-mechanical stress analysis and load sharing between the teeth of the fir-tree root. The second was devoted to the development of a complete model incorporating the effect of shot peening residual stresses upon the developed stress state. The effectiveness of shot peening treatment in response to cyclic thermo-mechanical loadings at the contact interface has also been studied. The third was concerned with the validation of some aspects of the developed models analytically using closed form solutions and experimentally using photoelasticity.

  14. Mitral valve repair for ischemic mitral regurgitation.

    PubMed

    Mohebali, Jahan; Chen, Frederick Y

    2015-05-01

    Mitral valve repair for ischemic mitral valve regurgitation remains controversial. In moderate mitral regurgitation (MR), controversy exists whether revascularization alone will be adequate to restore native valve geometry or whether intervention on the valve (repair) should be performed concomitantly. When MR is severe, the need for valve intervention is not disputed. Rather, the controversy is whether repair versus replacement should be undertaken. In contrast to degenerative or myxomatous disease that directly affects leaflet integrity and morphology, ischemic FMR results from a distortion and dilation of native ventricular geometry that normally supports normal leaflet coaptation. To address this, the first and most crucial step in successful valve repair is placement of an undersized, complete remodeling annuloplasty ring to restore the annulus to its native geometry. The following article outlines the steps for repair of ischemic mitral regurgitation.

  15. Robotically assisted mitral valve replacement.

    PubMed

    Gao, Changqing; Yang, Ming; Xiao, Cangsong; Wang, Gang; Wu, Yang; Wang, Jiali; Li, Jiachun

    2012-04-01

    In the present study, we determined the safety and efficacy of robotic mitral valve replacement using robotic technology. From January 2007 through March 2011, more than 400 patients underwent various types of robotic cardiac surgery in our department. Of these, 22 consecutive patients underwent robotically assisted mitral valve replacement. Of the 22 patients with isolated rheumatic mitral valve stenosis (9 men and 13 women), the mean age was 44.7 ± 19.8 years (range, 32-65). Preoperatively, all patients underwent a complete workup, including coronary angiography and transthoracic echocardiography. Of the 22 patients, 15 had concomitant atrial fibrillation. The surgical approach was through 4 right-side chest ports with femoral perfusion. Aortic occlusion was performed with a Chitwood crossclamp, and antegrade cardioplegia was administered directly by way of the anterior chest. Using 3 port incisions in the right side of the chest and a 2.5- to 3.0-cm working port, all the procedures were completed with the da Vinci S robot. All patients underwent successful robotic surgery. Of the 22 patients, 16 received a mechanical valve and 6 a tissue valve. The mean cardiopulmonary bypass time and aortic crossclamp time was 137.1 ± 21.9 minutes (range, 105-168) and 99.3 ± 17.9 minutes (range, 80-133), respectively. No operative deaths, stroke, or other complications occurred, and no incisional conversions were required. After surgery, all the patients were followed up echocardiographically. Robotically assisted mitral valve replacement can be performed safely in patients with isolated mitral valve stenosis, and surgical results are excellent. Copyright © 2012 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

  16. Catalytic mechanism in cyclic voltammetry at disc electrodes: an analytical solution.

    PubMed

    Molina, Angela; González, Joaquín; Laborda, Eduardo; Wang, Yijun; Compton, Richard G

    2011-08-28

    The theory of cyclic voltammetry at disc electrodes and microelectrodes is developed for a system where the electroactive reactant is regenerated in solution using a catalyst. This catalytic process is of wide importance, not least in chemical sensing, and it can be characterized by the resulting peak current which is always larger than that of a simple electrochemical reaction; in contrast the reverse peak is always relatively diminished in size. From the theoretical point of view, the problem involves a complex physical situation with two-dimensional mass transport and non-uniform surface gradients. Because of this complexity, hitherto the treatment of this problem has been tackled mainly by means of numerical methods and so no analytical expression was available for the transient response of the catalytic mechanism in cyclic voltammetry when disc electrodes, the most popular practical geometry, are used. In this work, this gap is filled by presenting an analytical solution for the application of any sequence of potential pulses and, in particular, for cyclic voltammetry. The induction principle is applied to demonstrate mathematically that the superposition principle applies whatever the geometry of the electrode, which enabled us to obtain an analytical equation valid whatever the electrode size and the kinetics of the catalytic reaction. The theoretical results obtained are applied to the experimental study of the electrocatalytic Fenton reaction, determining the rate constant of the reduction of hydrogen peroxide by iron(II).

  17. [Modern mitral valve surgery].

    PubMed

    Bothe, W; Beyersdorf, F

    2016-04-01

    At the beginning of the 20th century, Cutler and Levine performed the first successful surgical treatment of a stenotic mitral valve, which was the only treatable heart valve defect at that time. Mitral valve surgery has evolved significantly since then. The introduction of the heart-lung machine in 1954 not only reduced the surgical risk, but also allowed the treatment of different mitral valve pathologies. Nowadays, mitral valve insufficiency has become the most common underlying pathomechanism of mitral valve disease and can be classified into primary and secondary mitral insufficiency. Primary mitral valve insufficiency is mainly caused by alterations of the valve (leaflets and primary order chords) itself, whereas left ventricular dilatation leading to papillary muscle displacement and leaflet tethering via second order chords is the main underlying pathomechanism for secondary mitral valve regurgitation. Valve reconstruction using the "loop technique" plus annuloplasty is the surgical strategy of choice and normalizes life expectancy in patients with primary mitral regurgitation. In patients with secondary mitral regurgitation, implanting an annuloplasty is not superior to valve replacement and results in high rates of valve re-insufficiency (up to 30 % after 3 months) due to ongoing ventricular dilatation. In order to improve repair results in these patients, we add a novel subvalvular technique (ring-noose-string) to the annuloplasty that aims to prevent ongoing ventricular remodeling and re-insufficiency. In modern mitral surgery, a right lateral thoracotomy is the approach of choice with excellent repair and cosmetic results.

  18. Problem: Mitral Valve Regurgitation

    MedlinePlus

    ... Stroke Vascular Health Peripheral Artery Disease Venous Thromboembolism Aortic Aneurysm More Problem: Mitral Valve Regurgitation Updated:Sep 21,2016 What is mitral valve ... blood flows from the ventricle through the aortic valve — as it should — and some blood flows ...

  19. A rare case of spontaneous rectus sheath haematoma in a patient with mechanical prosthetic aortic and mitral valves.

    PubMed

    Aykan, Ahmet; Oguz, Ali; Yildiz, Mustafa; Özkan, Mehmet

    2012-07-12

    Every year nearly 300 000 patients have heart valve operations and mostly prosthetic valves are inserted. Coumadin is the mainstay of therapy in these individuals but it has many side effects, mostly related to its anticoagulant effect. Rectus sheath haematoma (RSH) is a rare complication of abdominal trauma, surgery and excessive strain, however, anticoagulant agents may predispose to this condition without any precipitating event. Reversal of anticoagulation and resuscitation with fluids and blood products are necessary but anticoagulation is crucial in patients with prosthetic valves, as they have acquired thrombotic diathesis. Herein we report on a case of spontaneous RSH in a patient with prosthetic mitral and aortic valves and a history of prosthetic valve thrombosis. He was successfully managed medically.

  20. Horseshoe thrombus in a patient with mechanical prosthetic mitral valve: A case report and review of literature

    PubMed Central

    Mehra, Sanjay; Movahed, Assad; Espinoza, Carlos; Marcu, Constantin B

    2015-01-01

    Patients with prosthetic cardiac valves are at high risk for thromboembolic complications and need life long anticoagulation with warfarin, which can be associated with variable dose requirements and fluctuating level of systemic anticoagulation and may predispose to thromboembolic and or hemorrhagic complications. Prosthetic cardiac valve thrombosis is associated with high morbidity and mortality. A high index of suspicion is essential for prompt diagnosis. Transthoracic echocardiography, and if required transesophageal echocardiography are the main diagnostic imaging modalities. Medically stable patients can be managed with thrombolytic therapy and anticoagulation, while some patients may require surgical thrombectomy or valve replacement. We present a case report of a patient with prosthetic mitral valve and an unusually large left atrial thrombus with both thromboembolic and hemorrhagic complications. PMID:26380832

  1. Dynamic-mechanical properties of a novel composite intervertebral disc prosthesis.

    PubMed

    Gloria, Antonio; Causa, Filippo; De Santis, Roberto; Netti, Paolo Antonio; Ambrosio, Luigi

    2007-11-01

    Over the past years, a tremendous effort has been made to develop an intervertebral disc (IVD) prosthesis with suitable biological, mechanical and transport properties. However, it has been frequently reported that current prostheses undergo failure mainly due to the mismatch between the mechanical properties of the conventional device and the spine segment to be replaced. The aim of the present work was to develop a poly(2-hydroxyethyl methacrylate)/poly(methyl methacrylate) (PHEMA/PMMA) (80/20 w/w) semi-interpenetrating polymer network (s-IPN) composite hydrogel reinforced with poly(ethylene terephthalate) (PET) fibres, and to investigate the static and dynamic mechanical properties. Filament winding and moulding technologies were employed to obtain the composite IVD prostheses with the unique complex structure that is peculiar to the natural IVD. The compressive properties analysis showed the typical J-shaped stress-strain curve which is displayed by natural IVDs. Compressive modulus varied from 84 to 120 MPa, as a function of the strain rate, and stress was higher than 10 MPa. These values are in the range of those of the natural lumbar IVDs. No failure of the prostheses has occurred during fatigue test performed for ten million cycles in physiological solution. Dynamic mechanical tests have confirmed the composite IVD prostheses exhibited appropriate viscoelastic properties.

  2. Research on Heat-Mechanical Coupling of Ventilated Disc Brakes under the Condition of Emergency Braking

    NASA Astrophysics Data System (ADS)

    Tan, Xuelong; Zhang, Jian; Tang, Wenxian; Zhang, Yang

    Taking the ventilated disc brake in some company as research object, and using UG to build 3D models of brake disc and pad, and making use of ABAQUS/Standard to set up two parts' finite element model, via the decelerated motion of actual simulation brake disc, which gets ventilated disc brake in the case of emergency breaking in time and space distribution of conditions of temperature and stress field, summarizes the distribution of temperature field and stress field, proves complex coupling between temperature, stress, and supplies the direct basis for brake's fatigue life analysis.

  3. [Physiopathology of mitral mechanics in hypertrophic cardiomyopathy. Groupe de travail "Cardiomyopathies et insuffisance cardiaque" de la Société Française de Cardiologie].

    PubMed

    Hagège, A; Desnos, M; Komajda, M; Dubourg, O; Isnard, R; Guicheney, P; Schwartz, K; Lévine, R A

    1994-10-01

    Ventricular hypertrophy, the only indisputable phenotypical marker of hypertrophic cardiomyopathy, is the basis of the physiopathology and treatment of the disease. Mitral valve abnormalities are usually considered to be secondary to the hypertrophy but the genesis of systolic anterior motion by the Venturi effect has been questioned by many clinical and experimental observations. Abnormalities of the mitral valve apparatus may in themselves (elongation of the valves, antero-internal malposition of the mitral papillary muscles and/or hyperlaxicity of antero-internal corhdae tendinae) create systolic anterior motion or subaortic obstruction in the absence of septal hypertrophy and/or increased subaortic flow velocities. Anatomo-clinical studies have confirmed this hypothesis: a high prevalence of mitral valve disease (increased valvular surface and length) has been found in hypertrophic cardiomyopathy. The recognition of these abnormalities is of value from the therapeutic (mitral valvuloplasty) diagnostic (in borderline cases) and genetic (when the primary nature of the abnormalities is confirmed) points of view.

  4. Assessment of mechanical properties of isolated bovine intervertebral discs from multi-parametric magnetic resonance imaging.

    PubMed

    Recuerda, Maximilien; Périé, Delphine; Gilbert, Guillaume; Beaudoin, Gilles

    2012-10-12

    The treatment planning of spine pathologies requires information on the rigidity and permeability of the intervertebral discs (IVDs). Magnetic resonance imaging (MRI) offers great potential as a sensitive and non-invasive technique for describing the mechanical properties of IVDs. However, the literature reported small correlation coefficients between mechanical properties and MRI parameters. Our hypothesis is that the compressive modulus and the permeability of the IVD can be predicted by a linear combination of MRI parameters. Sixty IVDs were harvested from bovine tails, and randomly separated in four groups (in-situ, digested-6h, digested-18h, digested-24h). Multi-parametric MRI acquisitions were used to quantify the relaxation times T1 and T2, the magnetization transfer ratio MTR, the apparent diffusion coefficient ADC and the fractional anisotropy FA. Unconfined compression, confined compression and direct permeability measurements were performed to quantify the compressive moduli and the hydraulic permeabilities. Differences between groups were evaluated from a one way ANOVA. Multi linear regressions were performed between dependent mechanical properties and independent MRI parameters to verify our hypothesis. A principal component analysis was used to convert the set of possibly correlated variables into a set of linearly uncorrelated variables. Agglomerative Hierarchical Clustering was performed on the 3 principal components. Multilinear regressions showed that 45 to 80% of the Young's modulus E, the aggregate modulus in absence of deformation HA0, the radial permeability kr and the axial permeability in absence of deformation k0 can be explained by the MRI parameters within both the nucleus pulposus and the annulus pulposus. The principal component analysis reduced our variables to two principal components with a cumulative variability of 52-65%, which increased to 70-82% when considering the third principal component. The dendograms showed a natural

  5. Caseous Calcification of Mitral Annulus: A Rare Monster Leading to Cerebrovascular Accident.

    PubMed

    Memon, Sarfaraz; Chhabra, Lovely; Krainski, Felix; Parker, Matthew W; Swales, Heather

    2015-10-01

    Caseous calcification of the mitral annulus (CCMA) is a rare variant of mitral annular calcification that maybe easily misdiagnosed or confused with an abscess, a tumor, or infective vegetation. The main pathophysiological mechanism leading to CCMA involves degeneration and calcium deposition on the mitral valve. We present a case of CCMA to help understand this clinical entity.

  6. Role of vortices in cavitation formation in the flow at the closure of a bileaflet mitral mechanical heart valve.

    PubMed

    Li, Chi-Pei; Chen, Sheng-Fu; Lo, Chi-Wen; Lu, Po-Chien

    2012-03-01

    Bubble cavitation occurs in the flow field when local pressure drops below vapor pressure. One hypothesis states that low-pressure regions in vortices created by instantaneous valve closure and occluder rebound promote bubble formation. To quantitatively analyze the role of vortices in cavitation, we applied particle image velocimetry (PIV) to reduce the instantaneous fields into plane flow that contains information about vortex core radius, maximum tangential velocity, circulation strength, and pressure drop. Assuming symmetrical flow along the center of the St. Jude Medical 25-mm valve, flow fields downstream of the closing valve were measured using PIV in the mitral position of a circulatory mock loop. Flow measurements were made during successive time phases immediately following the impact of the occluder with the housing (O/H impact) at valve closing. The velocity profile near the vortex core clearly shows a typical Rankine vortex. The vortex strength reaches maximum immediately after closure and rapidly decreases at about 10 ms, indicating viscous dissipation; vortex strength also intensifies with rising pulse rate. The maximum pressure drop at the vortex center is approximately 20 mmHg, an insignificant drop relative to atmospheric vapor pressures, which implies vortices play a minor role in cavitation formation.

  7. Creep mechanisms of a new Ni-Co-base disc superalloy at an intermediate temperature.

    PubMed

    Yuan, Y; Gu, Y F; Zhong, Z H; Osada, T; Cui, C Y; Tetsui, T; Yokokawa, T; Harada, H

    2012-10-01

    The microstructures of a new Ni-Co-base disc superalloy, TMW-4M3, before and after the creep test at 725 °C/630 MPa have been systematically investigated by transmission electron microscopy (TEM). The crept microstructures were marked as three different deformation stages (I, II and III) corresponding to the gradually increased strain. At stage I, stacking fault (SF) shearing was the main deformation mechanism. The SF was extrinsic and lay on {111} plane. However, deformation microtwinning became the dominant mode at stage II and III. The average spacing of deformation twins decreased from 109 ± 15 nm at stage II to 76 ± 12 nm at stage III, whereas the twin thickness did not change significantly. The influence of stacking fault energy (SFE) of γ matrix on the deformation mechanism is discussed. It is suggested that lower SFE in TMW-4M3 is partly responsible for the enhanced creep resistance. © 2012 The Authors Journal of Microscopy © 2012 Royal Microscopical Society.

  8. Standard transthoracic echocardiography and transesophageal echocardiography views of mitral pathology that every surgeon should know

    PubMed Central

    Tan, Timothy C.

    2015-01-01

    The mitral valve is the most commonly diseased heart valve and the prevalence of mitral valve disease increases proportionally with age. Echocardiography is the primary diagnostic imaging modality used in the assessment of patients with mitral valve disease. It is a noninvasive method which provides accurate anatomic and functional information regarding the mitral valve and can identify the mechanism of mitral valve pathology. This is especially useful as it may guide surgical repair. This is increasingly relevant given the growing trend of patients undergoing mitral valve repair. Collaboration between cardiac surgeons and echocardiographers is critical in the evaluation of mitral valve disease and for identification of complex valvular lesions that require advanced surgical skill to repair. This article will provide an overview of transthoracic and transesophageal assessment of common mitral valve pathology that aims to aid surgical decision making. PMID:26539350

  9. Mitral Valve Prolapse.

    ERIC Educational Resources Information Center

    Bergy, Gordon G.

    1980-01-01

    Mitral valve prolapse is the most common heart disease seen in college and university health services. It underlies most arrhythmia and many chest complaints. Activity and exercise restrictions are usually unnecessary. (Author/CJ)

  10. Mitral Valve Prolapse.

    ERIC Educational Resources Information Center

    Bergy, Gordon G.

    1980-01-01

    Mitral valve prolapse is the most common heart disease seen in college and university health services. It underlies most arrhythmia and many chest complaints. Activity and exercise restrictions are usually unnecessary. (Author/CJ)

  11. [Ischaemic mitral insufficiency].

    PubMed

    Messas, E

    2004-06-01

    Ischaemic mitral insufficiency (IMI) due to regurgitation of an anatomically normal valve, due to dysfunction directly related to myocardial ischaemia, is observed in over 20% of post-infarction patients and is associated with a doubling of the risk of death. The responsibility of ventricular remodelling with displacement of the papillary muscles in the genesis of IMI has been demonstrated experimentally. 3-D echocardiography has improved our understanding of the central role of geometrical changes of the subvalvular apparatus. The inconsistent results of surgery using an undersized mitral annulus have led to the search for alternative techniques. The correction of mitral insufficiency at coronary bypass surgery is a current topic of research. The application of new techniques of mitral valvuloplasty seems more effective and should provide an answer to this problem.

  12. Three-Dimensional Numerical Investigations of the Failure Mechanism of a Rock Disc with a Central or Eccentric Hole

    NASA Astrophysics Data System (ADS)

    Wang, S. Y.; Sloan, S. W.; Tang, C. A.

    2014-11-01

    The diametrical compression of a circular disc (Brazilian test) or cylinder with a small eccentric hole is a simple but important test to determine the tensile strength of rocks. This paper studies the failure mechanism of circular disc with an eccentric hole by a 3D numerical model (RFPA3D). A feature of the code RFPA3D is that it can numerically simulate the evolution of cracks in three-dimensional space, as well as the heterogeneity of the rock mass. First, numerically simulated Brazilian tests are compared with experimental results. Special attention is given to the effect of the thickness to radius ratio on the failure modes and the peak stress of specimens. The effects of the compressive strength to tensile strength ratio ( C/T), the loading arc angle (2 α), and the homogeneity index ( m) are also studied in the numerical simulations. Secondly, the failure process of a rock disc with a central hole is studied. The effects of the ratio of the internal hole radius ( r) to the radius of the rock disc ( R) on the failure mode and the peak stress are investigated. Thirdly, the influence of the vertical and horizontal eccentricity of an internal hole on the initiation and propagation of cracks inside a specimen are simulated. The effect of the radius of the eccentric hole and the homogeneity index ( m) are also investigated.

  13. Expression of the Trp2 allele of COL9A2 is associated with alterations in the mechanical properties of human intervertebral discs.

    PubMed

    Aladin, Darwesh M K; Cheung, Kenneth M C; Chan, Danny; Yee, Anita F Y; Jim, Jeffrey J T; Luk, Keith D K; Lu, William W

    2007-12-01

    Biomechanical study into the association between genetic polymorphism in COL9A2 and mechanical properties of human nucleus pulposus. To examine whether there is an association between genetic polymorphism in a structural gene, and alterations in the mechanical properties of the intervertebral discs that may predispose to disc degeneration. Genetic studies have demonstrated that a polymorphism (Trp2 allele) in COL9A2 coding for alpha2 chain of collagen IX predisposes the individual to disc degeneration. The mechanism of this predisposition is not known. Blood and whole disc samples were retrieved from adolescents and young adults during scoliosis surgery, degenerated discs were retrieved from patients with back pain during anterior spinal fusion. Anulus fibrosus and nucleus pulposus from a set of the scoliosis discs were used to perform immunohistochemistry to demonstrate the presence of collagen IX in the scoliosis discs. For the remaining samples, DNA was extracted from blood to determine the Trp2 status by sequencing. Nondegenerated (Trp2-), nondegenerated (Trp2+), and degenerated (Trp2-) nucleus pulposus samples were tested in confined compression. Swelling pressure and compressive modulus were measured and compared between groups. Positive staining of collagen IX was detected in both anulus fibrosus and nucleus pulposus sections confirming its presence in the scoliosis discs. The mean swelling pressure and compressive modulus values of 6 nondegenerated (Trp2+) samples (swelling pressure = 0.0019 MPa, compressive modulus = 0.97 MPa) were significantly lower (P < 0.05) than those of the 6 nondegenerated (Trp2-) samples (swelling pressure = 0.015 MPa; compressive modulus = 1.89 MPa). This is the first study to demonstrate an association between the Trp2 allele and disc mechanics, thus relating genetic variations and debilitating mechanical alterations that may ultimately result in intervertebral disc degeneration.

  14. Mitral Valve Stenosis after Open Repair Surgery for Non-rheumatic Mitral Valve Regurgitation: A Review.

    PubMed

    Shabsigh, Muhammad; Lawrence, Cassidy; Rosero-Britton, Byron R; Kumar, Nicolas; Kimura, Satoshi; Durda, Michael Andrew; Essandoh, Michael

    2016-01-01

    Mitral stenosis (MS) after mitral valve (MV) repair is a slowly progressive condition, usually detected many years after the index MV surgery. It is defined as a mean transmitral pressure gradient (TMPG) >5 mmHg or a mitral valve area (MVA) <1.5 cm(2). Pannus formation around the mitral annulus or extending to the mitral leaflets is suggested as the main mechanism for developing delayed MS after MV repair. On the other hand, early stenosis is thought to be a direct result of an undersized annuloplasty ring. Furthermore, in MS following ischemic mitral regurgitation (MR) repair, subvalvular tethering is the hypothesized pathophysiology. MS after MV repair has an incidence of 9-54%. Several factors have been associated with a higher risk for developing MS after MV repair, including the use of flexible Duran annuloplasty rings versus rigid Carpentier-Edwards rings, complete annuloplasty rings versus partial bands, small versus large anterior leaflet opening angle, and anterior leaflet tip opening length. Intraoperative echocardiography can measure the anterior leaflet opening angle, the anterior leaflet tip opening dimension, the MVA and the mean TMPG, and may help identify patients at risk for developing MS after MV repair.

  15. Mitral Valve Stenosis after Open Repair Surgery for Non-rheumatic Mitral Valve Regurgitation: A Review

    PubMed Central

    Shabsigh, Muhammad; Lawrence, Cassidy; Rosero-Britton, Byron R.; Kumar, Nicolas; Kimura, Satoshi; Durda, Michael Andrew; Essandoh, Michael

    2016-01-01

    Mitral stenosis (MS) after mitral valve (MV) repair is a slowly progressive condition, usually detected many years after the index MV surgery. It is defined as a mean transmitral pressure gradient (TMPG) >5 mmHg or a mitral valve area (MVA) <1.5 cm2. Pannus formation around the mitral annulus or extending to the mitral leaflets is suggested as the main mechanism for developing delayed MS after MV repair. On the other hand, early stenosis is thought to be a direct result of an undersized annuloplasty ring. Furthermore, in MS following ischemic mitral regurgitation (MR) repair, subvalvular tethering is the hypothesized pathophysiology. MS after MV repair has an incidence of 9–54%. Several factors have been associated with a higher risk for developing MS after MV repair, including the use of flexible Duran annuloplasty rings versus rigid Carpentier–Edwards rings, complete annuloplasty rings versus partial bands, small versus large anterior leaflet opening angle, and anterior leaflet tip opening length. Intraoperative echocardiography can measure the anterior leaflet opening angle, the anterior leaflet tip opening dimension, the MVA and the mean TMPG, and may help identify patients at risk for developing MS after MV repair. PMID:27148540

  16. Percutaneous mitral valve repair for mitral regurgitation.

    PubMed

    Block, Peter C

    2003-02-01

    Mitral regurgitation (MR) associated with, ischemic, and degenerative (prolapse) disease, contributes to left ventricular (LV) dysfunction due to remodeling, and LV dilation, resulting in worsening of MR. Mitral valve (MV) surgical repair has provided improvement in survival, LV function and symptoms, especially when performed early. Surgical repair is complex, due to diverse etiologies and has significant complications. The Society for Thoracic Surgery database shows that operative mortality for a 1st repair is 2% and for re-do repair is 4 times that. Cardiopulmonary bypass and cardiac arrest are required. The attendant morbidity prolongs hospitalization and recovery. Alfieri simplified mitral repair using an edge-to-edge technique which subsequently has been shown to be effective for multiple etiologies of MR. The MV leaflers are typically brought together by a central suture producing a double orifice MV without stenosis. Umana reported that MR decreased from grade 3.6 +/- 0.5 to 0.8 +/- 0.4 (P < 0.0001) and LV ejection fraction increased from 33 +/- 13% to 45 +/- 11% (P = 0.0156). In 121 patients, Maisano reported freedom from re-operation of 95 +/- 4.8% with up to 6 year follow-up. Oz developed a MV "grasper" that is directly placed via a left ventriculotomy and coapts both leaflets which are then fastened by a graduated spiral screw. An in-vitro model using explanted human valves showed significant reduction in MR and in canine studies, animals followed by serial echo had persistent MV coaptation. At 12 weeks the device was endothelialized. These promising results have paved the way for a percutaneous or minimally invasive-off pump mitral repair. Evalve has developed catheter-based technology, which, by apposing the edges of a regurgitant MV, results in edge-to-edge repair. Release of the device is done after echo and fluoroscopic evaluation under normal loading conditions. If the desired effect is not produced the device can be repositioned or retrieved

  17. Surgical Treatment of Congenital Mitral Valve Dysplasia.

    PubMed

    Vida, Vladimiro L; Carrozzini, Massimiliano; Padalino, Massimo; Milanesi, Ornella; Stellin, Giovanni

    2016-05-01

    Congenital mitral valve (MV) dysplasia is a relatively rare and highly complex cardiac disease. We present our results and illustrate the techniques used to repair these valves. Between 1972 and 2014, 100 consecutive patients underwent surgical repair of congenital MV dysplasia at our institution. Predominant MV regurgitation was present in 53 patients (53%) whereas mitral stenosis was prevalent in 47 (47%). There were five early (5%) and eight late deaths (9%). Actuarial survival was 95%, 94%, and 93% at 5, 10, and 20 years, respectively. Sixteen patients (18%) required reintervention due to subsequent MV dysfunction. Actuarial freedom from reintervention for MV dysfunction was 95%, 92%, and 89% at 5, 10, and 20 years, respectively. The mechanism underlying the valve dysfunction in congenital mitral valve dysplasia is multifactorial and requires the application of a variety of surgical techniques for repair. doi: 10.1111/jocs.12743 (J Card Surg 2016;31:352-356). © 2016 Wiley Periodicals, Inc.

  18. Strut fracture in the new Bjørk-Shiley mitral valve prosthesis.

    PubMed

    Brubakk, O; Simonsen, S; Källman, L; Fredriksen, A

    1981-04-01

    The case of a patient with the new type Bjørk-Shiley aortic and mitral valve prosthesis is described. Three months after implant she suffered acute heart failure and died. Post-mortem examination revealed a fractured outlet strut in the mitral valve prosthesis with dislocation of the disc. The fracture was regarded as due to excessive brittleness caused by demonstrated deposition of chromium-tungsten-carbide.

  19. On the mechanism of self gravitating Rossby interfacial waves in proto-stellar accretion discs

    NASA Astrophysics Data System (ADS)

    Yellin-Bergovoy, Ron; Heifetz, Eyal; Umurhan, Orkan M.

    2016-05-01

    The dynamical response of edge waves under the influence of self-gravity is examined in an idealized two-dimensional model of a proto-stellar disc, characterized in steady state as a rotating vertically infinite cylinder of fluid with constant density except for a single density interface at some radius r0. The fluid in basic state is prescribed to rotate with a Keplerian profile $\\Omega_k(r)\\sim r^{-3/2}$ modified by some additional azimuthal sheared flow. A linear analysis shows that there are two azimuthally propagating edge waves, kin to the familiar Rossby waves and surface gravity waves in terrestrial studies, which move opposite to one another with respect to the local basic state rotation rate at the interface. Instability only occurs if the radial pressure gradient is opposite to that of the density jump (unstably stratified) where self-gravity acts as a wave stabilizer irrespective of the stratification of the system. The propagation properties of the waves are discussed in detail in the language of vorticity edge waves. The roles of both Boussinesq and non-Boussinesq effects upon the stability and propagation of these waves with and without the inclusion of self-gravity are then quantified. The dynamics involved with self-gravity non- Boussinesq effect is shown to be a source of vorticity production where there is a jump in the basic state density, in addition, self-gravity also alters the dynamics via the radial main pressure gradient, which is a Boussinesq effect . Further applications of these mechanical insights are presented in the conclusion including the ways in which multiple density jumps or gaps may or may not be stable.

  20. A SECOND CASE OF LATE EMBOLIZATION OF PROSTHETIC MITRAL VALVE OCCLUDER WITH SURVIVAL FOLLOWING REOPERATION

    PubMed Central

    Sabbagh, Adib H.; O'Hare, James E.; Schocket, Lee I.; Pinckley, James N.

    1975-01-01

    A 51-year-old male with acute fulminating pulmonary edema and cardiogenic shock secondary to severe mitral insufficiency from dislodgment of the disc occluder in a Wada-Cutter valve was treated by immediate open heart procedure with a Bjork-Shiley mitral valve replacement. The patient survived and remains well. This is the second patient reported to survive operation and replacement of a malfunctioning prosthetic mitral valve from which the poppet escaped and embolized. The first case was reported by Hughes et al1 in February, 1975. Some striking similarities, as well as differences, in these two cases are discussed. Images PMID:15215920

  1. A SECOND CASE OF LATE EMBOLIZATION OF PROSTHETIC MITRAL VALVE OCCLUDER WITH SURVIVAL FOLLOWING REOPERATION.

    PubMed

    Sabbagh, Adib H.; O'Hare, James E.; Schocket, Lee I.; Pinckley, James N.

    1975-01-01

    A 51-year-old male with acute fulminating pulmonary edema and cardiogenic shock secondary to severe mitral insufficiency from dislodgment of the disc occluder in a Wada-Cutter valve was treated by immediate open heart procedure with a Bjork-Shiley mitral valve replacement. The patient survived and remains well. This is the second patient reported to survive operation and replacement of a malfunctioning prosthetic mitral valve from which the poppet escaped and embolized. The first case was reported by Hughes et al(1) in February, 1975. Some striking similarities, as well as differences, in these two cases are discussed.

  2. Mitral valve prolapse, panic disorder, and chest pain.

    PubMed

    Alpert, M A; Mukerji, V; Sabeti, M; Russell, J L; Beitman, B D

    1991-09-01

    Mitral valve prolapse is a common cardiac disorder that can readily be diagnosed by characteristic auscultatory and echocardiographic criteria. Although many diseases have been associated with mitral valve prolapse, most affected individuals have the primary form of the disorder. Mitral valve prolapse is an inherited condition commonly associated with myxomatous degeneration of the mitral valve and its support structures. Complications of mitral valve prolapse, including cardiac arrhythmias, sudden death, infective endocarditis, severe mitral regurgitation (with or without chordae tendineae rupture), and cerebral ischemic events, occur infrequently considering the wide prevalence of the disorder. Panic disorder is a specific type of anxiety disorder characterized by at least three panic attacks within a 3-week period or one panic attack followed by fear of subsequent panic attacks for at least 1 month. It too is a common condition with a prevalence and age and gender distribution similar to that of mitral valve prolapse. Panic disorder and mitral valve prolapse share many nonspecific symptoms, including chest pain or discomfort, palpitations, dyspnea, effort intolerance, and pre-syncope. Chest pain is the symptom in both conditions that most commonly brings the patient to medical attention. The clinical description of chest pain in patients with mitral valve prolapse is highly variable, possibly reflecting multiple etiologies. Chest pain in panic disorder is usually characterized as atypical angina pectoris and as such bears resemblance to the chest pain commonly described by patients with mitral valve prolapse. Multiple investigative attempts to elucidate the mechanism of chest pain in both conditions have failed to identify a unifying cause. Review of the literature leaves little doubt that mitral valve prolapse and panic disorder frequently co-occur. Given the similarities in their symptomatology, a high rate of co-occurrence is, in fact, entirely predictable

  3. Abnormal Mitral Valve Dimensions in Pediatric Patients with Hypertrophic Cardiomyopathy.

    PubMed

    Schantz, Daryl; Benson, Lee; Windram, Jonathan; Wong, Derek; Dragulescu, Andreea; Yoo, Shi-Joon; Mertens, Luc; Friedberg, Mark; Al Nafisi, Bahiyah; Grosse-Wortmann, Lars

    2016-04-01

    The hearts of patients with hypertrophic cardiomyopathy (HCM) show structural abnormalities other than isolated wall thickening. Recently, adult HCM patients have been found to have longer mitral valve leaflets than control subjects. The aim of the current study was to assess whether children and adolescents with HCM have similar measureable differences in mitral valve leaflet dimensions when compared to a healthy control group. Clinical and echocardiographic data from 46 children with myocardial hypertrophy and a phenotype and/or genotype consistent with sarcomeric HCM were reviewed. Cardiac magnetic resonance imaging studies were evaluated. The anterior and posterior mitral valve leaflet lengths and myocardial structure were compared to 20 healthy controls. The anterior mitral valve was longer in the HCM group than in the control group (28.4 ± 4.9 vs. 25.2 ± 3.6 mm in control patients, p = 0.013) as was the posterior mitral valve leaflet (16.3 ± 3.0 vs. 13.1 ± 2.3 mm for controls <0.0001). There was no correlation between the resting left ventricular outflow tract gradient and anterior mitral valve leaflet length, nor was the anterior mitral valve leaflet longer in those with systolic anterior motion of the mitral valve compared to those without (28.9 ± 6.1 vs. 28.1 ± 4.5 mm, p = 0.61). Children and adolescents with HCM have abnormally long mitral valve leaflets when compared with healthy control subjects. These abnormalities do not appear to result in, or be due to, obstruction to left ventricular outflow. The mechanism of this mitral valve elongation is not clear but appears to be independent of hemodynamic disturbances.

  4. Crystal Structure of MC159 Reveals Molecular Mechanism of DISC Assembly and FLIP Inhibition

    SciTech Connect

    Yang,J.; Wang, L.; Zheng, L.; Wan, F.; Ahmed, M.; Lenardo, M.; Wu, H.

    2005-01-01

    The death-inducing signaling complex (DISC) comprising Fas, Fas-associated death domain (FADD), and caspase-8/10 is assembled via homotypic associations between death domains (DDs) of Fas and FADD and between death effector domains (DEDs) of FADD and caspase-8/10. Caspase-8/10 and FLICE/caspase-8 inhibitory proteins (FLIPs) that inhibit caspase activation at the DISC level contain tandem DEDs. Here, we report the crystal structure of a viral FLIP, MC159, at 1.2 Angstrom resolution. It reveals a noncanonical fold of DED1, a dumbbell-shaped structure with rigidly associated DEDs and a different mode of interaction in the DD superfamily. Whereas the conserved hydrophobic patch of DED1 interacts with DED2, the corresponding region of DED2 mediates caspase-8 recruitment and contributes to DISC assembly. In contrast, MC159 cooperatively assembles with Fas and FADD via an extensive surface that encompasses the conserved charge triad. This interaction apparently competes with FADD self-association and disrupts higher-order oligomerization required for caspase activation in the DISC.

  5. [Functional mitral regurgitation. Physiopathology and impact of medical therapy and surgical techniques for left ventricle reduction].

    PubMed

    Comín, J; Manito, N; Roca, J; Castells, E; Esplugas, E

    1999-07-01

    Functional mitral regurgitation is frequently observed in the setting of left ventricular dyfunction. This finding is a marker of poor outcome in patients with either ischemic or dilated cardiomyopathy. The mechanism accounting for this phenomenon is an altered balance of tethering versus coapting forces acting on the mitral valves in the failing heart. Tethering forces represent an anomalous tension on the mitral valves due to displacement of mitral valve attachments secondary to increased left ventricular chamber sphericity associated with systolic ventricular dysfunction. On the other hand, coapting forces are weak and unable to counteract the abnormal tension acting on the mitral valve, which restricts closure and leads to regurgitation. Vasodilators and inotropic drugs are effective in the management of functional mitral regurgitation. Although partial left ventriculectomy or Batista's procedure is still investigational, this new technique seems to provide an optimal control of functional mitral regurgitation and improve functional capacity and survival of some patients with heart failure.

  6. Acute massive mitral regurgitation from prosthetic valve dysfunction.

    PubMed Central

    Cooper, D K; Sturridge, M F

    1976-01-01

    Two cases of prosthetic valve dysfunction resulting in acute massive mitral regurgitation are reported; emergency operation was successful in both cases. Survival following complete dislodgement of the occluder of a disc valve, as occurred in one case, does not appear to have been reported before. The diffculty in diagnosis of sudden cardiac decompensation in patients with prosthetic valves is stressed, as is the need for urgent operation. Images PMID:973894

  7. Retrograde (atrial) dislodgement of a Cross-Jones mitral valve occluder.

    PubMed

    Schachner, A; Vidne, B; Levy, M J

    1979-01-01

    Fatal atrial dislodgement of a lenticular disc occurred seven years after surgery in a 54-year-old patient, who had had a mitral valve replacement with a Cross-Jones prosthesis, for ruptured chordae tendinae. A marked distortion of the titanium ring reinforced silicone rubber lens disc due to material wear was the cause of this complication. From the literature available to us, atrial dislodgement of a prosthetic mitral occluder has not been previously recorded. We therefore intend to recommend elective replacement of the Cross-Jones prosthesis in all patients who have had their artificial valve functioning for more than five years.

  8. Effect of microstructure on high-temperature mechanical behavior of nickel-base superalloys for turbine disc applications

    NASA Astrophysics Data System (ADS)

    Sharpe, Heather Joan

    2007-05-01

    Engineers constantly seek advancements in the performance of aircraft and power generation engines, including, lower costs and emissions, and improved fuel efficiency. Nickel-base superalloys are the material of choice for turbine discs, which experience some of the highest temperatures and stresses in the engine. Engine performance is proportional to operating temperatures. Consequently, the high-temperature capabilities of disc materials limit the performance of gas-turbine engines. Therefore, any improvements to engine performance necessitate improved alloy performance. In order to take advantage of improvements in high-temperature capabilities through tailoring of alloy microstructure, the overall objectives of this work were to establish relationships between alloy processing and microstructure, and between microstructure and mechanical properties. In addition, the projected aimed to demonstrate the applicability of neural network modeling to the field of Ni-base disc alloy development and behavior. The first phase of this work addressed the issue of how microstructure varies with heat treatment and by what mechanisms these structures are formed. Further it considered how superalloy composition could account for microstructural variations from the same heat treatment. To study this, four next-generation Ni-base disc alloys were subjected to various controlled heat-treatments and the resulting microstructures were then quantified. These quantitative results were correlated to chemistry and processing, including solution temperature, cooling rate, and intermediate hold temperature. A complex interaction of processing steps and chemistry was found to contribute to all features measured; grain size, precipitate distribution, grain boundary serrations. Solution temperature, above a certain threshold, and cooling rate controlled grain size, while cooling rate and intermediate hold temperature controlled precipitate formation and grain boundary serrations. Diffusion

  9. The challenges of managing rheumatic disease of the mitral valve in Jamaica.

    PubMed

    Little, Sherard G

    2014-12-01

    Between January, 2009 and December, 2013, 84 patients were identified who underwent isolated mitral valve surgery in Jamaica at The University Hospital of the West Indies and The Bustamante Hospital for Children. The most common pathology requiring surgery was rheumatic heart disease, accounting for 84% of the procedures performed. The majority of patients had regurgitation of the mitral valve (67%), stenosis of the mitral valve (22%), and mixed mitral valve disease (11%). The most common procedure performed was replacement of the mitral valve (69%), followed by mitral valve repair (29%). Among the patients, one underwent closed mitral commissurotomy. The choice of procedure differed between age groups. In the paediatric population (<18 years of age), the majority of patients underwent repair of the mitral valve (89%). In the adult population (18 years and above), the majority of patients underwent mitral valve replacement (93%). Overall, of all the patients undergoing replacement of the mitral valve, 89% received a mechanical valve prosthesis, whereas 11% received a bioprosthetic valve prosthesis. Of the group of patients who underwent mitral valve repair for rheumatic heart disease, 19% required re-operation. The average time between initial surgery and re-operation was 1.2 years. Rheumatic fever and rheumatic heart disease remain significant public health challenges in Jamaica and other developing countries. Focus must remain on primary and secondary prevention strategies in order to limit the burden of rheumatic valvulopathies. Attention should also be directed towards improving access to surgical treatment for young adults.

  10. Transforaminal epidural steroid injections followed by mechanical diagnosis and therapy to prevent surgery for lumbar disc herniation.

    PubMed

    van Helvoirt, Hans; Apeldoorn, Adri T; Ostelo, Raymond W; Knol, Dirk L; Arts, Mark P; Kamper, Steven J; van Tulder, Maurits W

    2014-07-01

    Prospective cohort study. To report the clinical course of patients with MRI-confirmed lumbar disc herniation-related radicular noncentralizing pain who received transforaminal epidural steroid injections (TESIs) and mechanical diagnosis and therapy (MDT). Noncentralizing symptoms in patients with lumbar disc herniation are associated with poor outcome. Commonly used treatments for these patients include TESIs and MDT. No study has evaluated the outcome of combining both strategies. Consecutive candidates for herniated lumbar disc surgery with noncentralizing chronic pain were eligible. Patients received TESIs followed by MDT. The primary outcomes were pain severity in the leg, disability (Roland-Morris Disability Questionnaire for Sciatica), and global perceived effect (GPE). Outcomes were measured at baseline, discharge, and 12 months. Linear mixed-models and McNemar's tests were used to analyze outcome data. Sixty-nine patients receive TESIs. After TESIs, symptoms were resolved completely in 11 patients (16%). In these patients, symptom resolution was maintained at 12 months. A second subgroup of 32 patients (46%) reported significantly less pain after TESIs and showed centralization with MDT reassessment (significant reductions in leg pain and disability [P < 0.001]) and a satisfaction rate of 90% at 12 months. A third subgroup of 11 patients (16%) reported significantly less pain after TESIs but still showed noncentralization with MDT reassessment (significant reductions in leg pain and disability [P < 0.05] and a satisfaction rate of 50% at 12 months). A fourth subgroup of 15 patients (22%) did not respond on TESIs and received an operative intervention. The results indicate that a course of TESIs followed by MDT may be able to avoid surgery in a substantial proportion of candidates for herniated lumbar disc surgery. Wiley Periodicals, Inc.

  11. Exploring Regulatory Mechanisms of Atrial Myocyte Hypertrophy of Mitral Regurgitation through Gene Expression Profiling Analysis: Role of NFAT in Cardiac Hypertrophy

    PubMed Central

    Chang, Tzu-Hao; Chen, Mien-Cheng; Chang, Jen-Ping; Huang, Hsien-Da; Ho, Wan-Chun; Lin, Yu-Sheng; Pan, Kuo-Li; Huang, Yao-Kuang; Liu, Wen-Hao; Wu, Chia-Chen

    2016-01-01

    Background Left atrial enlargement in mitral regurgitation (MR) predicts a poor prognosis. The regulatory mechanisms of atrial myocyte hypertrophy of MR patients remain unknown. Methods and Results This study comprised 14 patients with MR, 7 patients with aortic valve disease (AVD), and 6 purchased samples from normal subjects (NC). We used microarrays, enrichment analysis and quantitative RT-PCR to study the gene expression profiles in the left atria. Microarray results showed that 112 genes were differentially up-regulated and 132 genes were differentially down-regulated in the left atria between MR patients and NC. Enrichment analysis of differentially expressed genes demonstrated that “NFAT in cardiac hypertrophy” pathway was not only one of the significant associated canonical pathways, but also the only one predicted with a non-zero score of 1.34 (i.e. activated) through Ingenuity Pathway Analysis molecule activity predictor. Ingenuity Pathway Analysis Global Molecular Network analysis exhibited that the highest score network also showed high association with cardiac related pathways and functions. Therefore, 5 NFAT associated genes (PPP3R1, PPP3CB, CAMK1, MEF2C, PLCE1) were studies for validation. The mRNA expressions of PPP3CB and MEF2C were significantly up-regulated, and CAMK1 and PPP3R1 were significantly down-regulated in MR patients compared to NC. Moreover, MR patients had significantly increased mRNA levels of PPP3CB, MEF2C and PLCE1 compared to AVD patients. The atrial myocyte size of MR patients significantly exceeded that of the AVD patients and NC. Conclusions Differentially expressed genes in the “NFAT in cardiac hypertrophy” pathway may play a critical role in the atrial myocyte hypertrophy of MR patients. PMID:27907007

  12. The origin of thick discs

    NASA Astrophysics Data System (ADS)

    Comerón, Sébastien

    2015-03-01

    Thick discs are defined to be disc-like components with a scale height larger than that of the classical discs. They are ubiquitous (Yoachim & Dalcanton 2006; Comerón et al. 2011a), they are made of mostly old and metal-poor stars and are most easily detected in close to edge-on galaxies. Their origin has been considered mysterious and several formation theories have been proposed: • The thick disc being formed secularly by thin disc stars heated by disc overdensities such as giant molecular clouds or spiral arms (Villumsen 1985, ApJ, 290, 75) and by stars moved outwards from their original orbits by radial migration mechanisms (Schönrich & Binney 2009). • The thick disc being formed by the heating of the thin disc by satellites (Quinn et al. 1993) and the tidal stripping of them (Abadi et al. 2003). • The thick disc being formed fast and already thick at high redshift in an highly unstable disc. Inside that thick disc, a thin disc would form afterwards as suggested by Elemgreen & Elmegreen (2006). • The thick disc being formed originally thick at high redshift by the merger of gas-rich protogalactic fragments and a thin disc forming afterwards within it (Brook et al. 2007). The first mechanism is a secular evolution mechanism. The time-scale of the second one is dependent on the merger history of the main galaxy. In the two last mechanisms, the thick disc forms already thick in a short time-scale at high redshift. Recent Milky Way studies, (see, e.g., Bovy et al. 2012), have shown indications that there is no discontinuity between the thin and the thick disc chemical and kinematic properties. Instead, those studies indicate the presence of a monotonic distribution of disc thicknesses. This would suggest a secular origin for the Milky Way thick disc. Studies in external galaxies (Yoachim & Dalcanton 2006; Comerón et al. 2011b), have shown that low-mass disc galaxies have thick disc relative masses much larger than those found in large-mass galaxies

  13. How Is Mitral Valve Prolapse Treated?

    MedlinePlus

    ... page from the NHLBI on Twitter. How Is Mitral Valve Prolapse Treated? Most people who have mitral valve ... all hospitals offer this method. Valve Repair and Valve Replacement In mitral valve surgery, the valve is repaired or replaced. ...

  14. Structure and mechanical function of the inter-lamellar matrix of the annulus fibrosus in the disc.

    PubMed

    Tavakoli, Javad; Elliott, Dawn M; Costi, John J

    2016-08-01

    The inter-lamellar matrix (ILM) has an average thickness of less than 30 µm and lies between adjacent lamellae in the annulus fibrosus (AF). The microstructure and composition of the ILM have been studied in various anatomic regions of the disc; however, their contribution to AF mechanical properties and structural integrity is unknown. It was suggested that the ILM components, mainly elastic fibers and cross-bridges, play a role in providing mechanical integrity of the AF. Therefore, the manner in which they respond to different loadings and stabilize adjacent lamellae structure will influence AF tear formation and subsequent herniation. This review paper summarizes the composition, microstructure, and potential role of the ILM in the progression of disc herniation, clarifies the micromechanical properties of the ILM, and proposes critical areas for future studies. There are a number of unknown characteristics of the ILM, such as its mechanical role, impact on AF integrity, and ultrastructure of elastic fibers at the ILM-lamella boundary. Determining these characteristics will provide important information for tissue engineering, repair strategies, and the development of more-physiological computational models to study the initiation and propagation of AF tears that lead to herniation and degeneration. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1307-1315, 2016.

  15. A global pattern of mechanical stress polarizes cell divisions and cell shape in the growing Drosophila wing disc.

    PubMed

    Legoff, Loïc; Rouault, Hervé; Lecuit, Thomas

    2013-10-01

    Organismal development is under genetic control. Ultimately, mechanical forces shape embryos. If we want to understand the precise regulation of size and shape in animals, we must dissect how forces are distributed in developing tissues, and how they drive cell behavior to shape organs. This has not been addressed fully in the context of growing tissues. As cells grow and divide, they exert a pressure on their neighbors. How these local stresses add up or dissipate as the tissue grows is an unanswered question. We address this issue in the growing wing imaginal disc of Drosophila larvae, the precursor of the adult wing. We used a quantitative approach to analyze the strains and stresses of cells of the wing pouch, and found a global pattern of stress whereby cells in the periphery of the tissue are mechanically stretched and cells in the center are compressed. This pattern has important consequences on cell shape in the wing pouch: cells respond to it by polarizing their acto-myosin cortex, and aligning their divisions with the main axis of cell stretch, thereby polarizing tissue growth. Ectopic perturbations of tissue growth by the Hippo signaling pathway reorganize this pattern in a non-autonomous manner, suggesting a synergy between tissue mechanics and growth control during wing disc morphogenesis.

  16. The use of a novel injectable hydrogel nucleus pulposus replacement in restoring the mechanical properties of cyclically fatigued porcine intervertebral discs.

    PubMed

    Balkovec, Christian; Vernengo, Jennifer; McGill, Stuart M

    2013-06-01

    Repeated flexion and extension of an intervertebral disc has been shown to affect the angular stiffness of spinal motion segments and is a barometer of the mechanical integrity of the disc. A degenerated disc that loses height causes higher levels of stress on the annulus and facet joints which may increase its level of degeneration; restoring disc height may therefore help to slow this degenerative cascade. Previous research has indicated that nucleus implants have the potential to improve the mechanical characteristics of a disc and an implant that is custom-fit to the intervertebral disc yields the best results with respect to decreasing annular degeneration. Two groups of porcine spinal motion segments were exposed to repeated flexion and extension. One group was then injected with a novel hydrogel while the other group was used as a control. Both groups were then exposed to another round of cyclic flexion and extension to examine the effect that the hydrogel had on restoring the original mechanics to the motion segments. Angular stiffness was restored to the group which received the hydrogel injection in addition to a significant improvement in specimen height. No significant changes were seen in the group which did not receive an injection. It would appear that use of the novel injectable hydrogel is able to restore angular stiffness to cyclically fatigued spinal motion segments. It is also important to note that continued repetition of the event causing specimen fatigue after performing hydrogel injection will result in an eventual return to the same fatigued state.

  17. Diastolic Mitral Regurgitation in a Patient With Complex Native Mitral and Aortic Valve Endocarditis: A Rare Phenomenon With Potential Catastrophic Consequences.

    PubMed

    Pulido, Juan N; Lynch, James J; Mauermann, William J; Michelena, Hector I; Rehfeldt, Kent H

    2016-03-01

    Diastolic mitral valve regurgitation is a rare phenomenon described in patients with atrioventricular conduction abnormalities, severe left ventricular systolic or diastolic dysfunction with regional wall motion dyssynchrony, or severe acute aortic valve regurgitation. The presence of diastolic mitral valve regurgitation in acute aortic regurgitation due to endocarditis suggests critical severity requiring urgent surgical valve replacement. We describe a case of diastolic mitral regurgitation in the setting of complex native mitral-aortic valve endocarditis in a patient in normal sinus rhythm and review the etiologic mechanisms of this phenomenon, echocardiographic assessment, and therapeutic implications for hemodynamic management.

  18. Associations between disc space narrowing, anterior osteophytes and disability in chronic mechanical low back pain: a cross sectional study.

    PubMed

    Perera, Romain Shanil; Dissanayake, Poruwalage Harsha; Senarath, Upul; Wijayaratne, Lalith Sirimevan; Karunanayake, Aranjan Lional; Dissanayake, Vajira Harshadeva Weerabaddana

    2017-05-15

    Radiographic features of lumbar disc degeneration (LDD) are common findings in patients with chronic mechanical low back pain; however, its role in disability and intensity of pain is debatable. This study aims to investigate the associations of the x-ray features of LDD and lumbar spondylolisthesis with severity of disability and intensity of pain. A cross-sectional study was conducted on 439 patients with chronic mechanical low back pain who attended the rheumatology clinic, National Hospital of Sri Lanka, Colombo, from May 2012 to May 2014. Severity of disability was measured using Modified Oswestry Disability Index and intensity of pain was assessed using numeric rating scale (0-100). X-ray features of LDD (disc space narrowing, anterior osteophytes and overall LDD) and spondylolisthesis were assessed in lateral recumbent lumbar x-rays (L1/L2 to L5/S1) and graded by a consultant radiologist blinded to clinical data. Generalised linear model with linear response was used to assess the associations of x-ray features of LDD with severity of disability and intensity of pain adjusting for age, gender, body mass index and pain radiating into legs. Mean age was 48.99 ± 11.21 and 323 (73.58%) were females. 87 (19.82%) were obese. Mean severity of disability was 30.95 ± 13.67 and mean intensity of pain was 45.50 ± 20.37. 69 (15.72%), 26 (5.92%) and 85 (19.36%) patients had grade 2 disc space narrowing, anterior osteophytes and overall LDD, respectively. 51 (11.62%) patients had lumbar spondylolisthesis. Grade of disc space narrowing and overall LDD were not associated with severity of disability or intensity of pain. The presence of lumbar spondylolisthesis was associated with severity of disability. Female gender and pain radiating into legs were associated with severity of disability and intensity of pain. Advancing age was associated with x-ray features of LDD and lumbar spondylolisthesis. Lumbar spondylolisthesis is associated with severity of

  19. Early Stabilization of Traumatic Aortic Transection and Mitral Valve Regurgitation

    PubMed Central

    Lambrechts, David L.; Wellens, Francis; Vercoutere, Rik A.; De Geest, Raf

    2003-01-01

    We report a case of life-threatening aortic transection with concomitant mitral papillary muscle rupture and severe lung contusion caused by a failed parachute jump. This blunt thoracic injury was treated by early stabilization with extracorporeal membrane oxygenation followed by successful delayed graft repair of the descending aorta and mitral valve replacement with a mechanical prosthesis. (Tex Heart Inst J 2003;30:65–7) PMID:12638675

  20. Fractured occluder disc: a previously unrecognized complication of the Starr-Edwards disc prosthesis.

    PubMed

    Malouf, J F; Hannoush, H M; Odell, J A

    2001-01-01

    Fracture of the occluder disc of a low-profile Starr-Edwards prosthesis is a hitherto unrecognized complication. We describe a patient who presented with right heart failure and severe pulmonary hypertension 27 years after mitral valve replacement with a model 6520 caged-disc prosthesis. At surgery, there was a longitudinal split in the occluder disc, and organized thrombus was lodged between the split segments. This case offers a unique opportunity to study the long-term effects of wear on the polyethylene poppet and Stellite cage.

  1. The Effect of a Variable Disc Pad Friction Coefficient for the Mechanical Brake System of a Railway Vehicle

    PubMed Central

    Lee, Nam-Jin; Kang, Chul-Goo

    2015-01-01

    A brake hardware-in-the-loop simulation (HILS) system for a railway vehicle is widely applied to estimate and validate braking performance in research studies and field tests. When we develop a simulation model for a full vehicle system, the characteristics of all components are generally properly simplified based on the understanding of each component’s purpose and interaction with other components. The friction coefficient between the brake disc and the pad used in simulations has been conventionally considered constant, and the effect of a variable friction coefficient is ignored with the assumption that the variability affects the performance of the vehicle braking very little. However, the friction coefficient of a disc pad changes significantly within a range due to environmental conditions, and thus, the friction coefficient can affect the performance of the brakes considerably, especially on the wheel slide. In this paper, we apply a variable friction coefficient and analyzed the effects of the variable friction coefficient on a mechanical brake system of a railway vehicle. We introduce a mathematical formula for the variable friction coefficient in which the variable friction is represented by two variables and five parameters. The proposed formula is applied to real-time simulations using a brake HILS system, and the effectiveness of the formula is verified experimentally by testing the mechanical braking performance of the brake HILS system. PMID:26267883

  2. The Effect of a Variable Disc Pad Friction Coefficient for the Mechanical Brake System of a Railway Vehicle.

    PubMed

    Lee, Nam-Jin; Kang, Chul-Goo

    2015-01-01

    A brake hardware-in-the-loop simulation (HILS) system for a railway vehicle is widely applied to estimate and validate braking performance in research studies and field tests. When we develop a simulation model for a full vehicle system, the characteristics of all components are generally properly simplified based on the understanding of each component's purpose and interaction with other components. The friction coefficient between the brake disc and the pad used in simulations has been conventionally considered constant, and the effect of a variable friction coefficient is ignored with the assumption that the variability affects the performance of the vehicle braking very little. However, the friction coefficient of a disc pad changes significantly within a range due to environmental conditions, and thus, the friction coefficient can affect the performance of the brakes considerably, especially on the wheel slide. In this paper, we apply a variable friction coefficient and analyzed the effects of the variable friction coefficient on a mechanical brake system of a railway vehicle. We introduce a mathematical formula for the variable friction coefficient in which the variable friction is represented by two variables and five parameters. The proposed formula is applied to real-time simulations using a brake HILS system, and the effectiveness of the formula is verified experimentally by testing the mechanical braking performance of the brake HILS system.

  3. Pathological mechanism of lumbar disc herniation resulting in neurogenic muscle hypertrophy.

    PubMed

    Walcott, Brian P; Nahed, Brian V; Redjal, Navid; Stein, Thor D; Kahle, Kristopher T; Coumans, Jean-Valery

    2011-12-01

    We present a 33-year-old man with 5-year history of low back pain who presented with an enlarging right calf. The patient underwent an extensive workup including biopsy without diagnosis. The patient's examination was significant for diminished pinprick sensation in the right L5/S1 dermatome. Reflexes were absent in the right ankle. The circumference of the right calf (58 cm) was twice that of the left. MRI revealed a herniated lumbar disc at the L5/S1 level. He then underwent a L5/S1 microdiscectomy. Following this surgery, the patient noted complete resolution of all sensory deficits in his lower extremity. His calf circumference had decreased by 5 cm at 4 months and by a total of 8 cm at his 2-year post-operative visit. Histological examination of the affected muscle demonstrated severe grouped atrophy of both type I and type II fibers. There was also evidence of compensatory fiber hypertrophy as well as fiber splitting. We concluded that the patient suffered from a herniated lumbar disc causing radiculopathy with calf hypertrophy (neurogenic hypertrophy). To our knowledge this is the first report of both grouped atrophy and compensatory hypertrophy of both muscle fiber types seen in this phenomenon.

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

    PubMed Central

    Lukács, L; Kassai, I; Lengyel, M

    1996-01-01

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

  5. [Intraoperative transesophageal echocardiography in patients undergoing robotic mitral valve replacement].

    PubMed

    Wang, Yao; Gao, Changqing; Xiao, Cangsong; Yang, Ming; Wang, Gang; Wang, Jiali; Shen, Yansong

    2012-12-01

    To retrospectively assess the value of intraoperative transesophageal echocardiography (TEE) during robotic mitral valve (MV) replacement. Intraoperative TEE was performed in 21 patients undergoing robotic MV replacement for severe rheumatic mitral stenosis between November 2008 and December 2010. During the procedure, TEE was performed to document the mechanism of rheumatic mitral stenosis (leaflet thickening and calcification, commissural fusion or chordal fusion) before cardiopulmonary bypass (CPB). During the establishment of peripheral CPB, TEE was used to guide the placement of the cannulae in the inferior vena cava (IVC), superior vena cava (SVC), and ascending aorta (AAO). After weaning from CPB, TEE was performed to evaluate the effect of the procedure. Accuracy of TEE was 100% for rheumatic mitral stenosis. All the cannuli in the SVC, IVC and AAO were located in the correct position. In all patients, TEE confirmed successful procedure. TEE is useful in the assessment of robotic MV replacement.

  6. Mitral valve aneurysm associated with aortic valve endocarditis and regurgitation.

    PubMed

    Raval, Amish N; Menkis, Alan H; Boughner, Derek R

    2002-01-01

    Mitral valve aneurysms are rare complications occurring most commonly in association with aortic valve infective endocarditis. [Decroly 1989, Chua 1990, Northridge 1991, Karalis 1992, Roguin 1996, Mollod 1997, Vilacosta 1997, Cai 1999, Vilacosta 1999, Teskey 1999, Chan 2000, Goh 2000, Marcos- Alberca 2000] While the mechanism of the development of this lesion is unclear, complications such as perforation can occur and lead to significant mitral regurgitation. [Decroly 1989, Karalis 1992, Teskey 1999, Vilacosta 1999]; The case of a 69-year-old male with Streptococcus Sanguis aortic valve endocarditis and associated anterior mitral leaflet aneurysm is presented. Following surgery, tissue pathology of the excised lesion revealed myxomatous degeneration and no active endocarditis or inflammatory cells. This may add support to the hypothesis that physical stress due to severe aortic insufficiency and structural weakening, without infection of the anterior mitral leaflet, can lead to the development of this lesion.

  7. A pathoanatomic approach to the management of mitral regurgitation.

    PubMed

    Badhwar, Vinay; Smith, Anson J C; Cavalcante, João L

    2016-02-01

    Mitral regurgitation remains the most common global valvular heart disease. From otherwise unsuspecting healthy patients without overt symptoms to those with recalcitrant heart failure, mitral valve (MV) disease touches millions of patients per year. While MV prolapse without regurgitation remains benign, once regurgitation begins, quantification of severity is related to prognosis. Understanding the mechanism of regurgitation guides appropriate treatment. Current management guidelines emphasize early therapy after careful assessment of both anatomy and severity of mitral regurgitation. The objective of this review is to provide an update on the treatment of MV disease and to offer additional granularity on pathoanatomic decision making that may aid a more precise application of optimal guideline-directed therapy of primary and secondary mitral regurgitation.

  8. Severe mitral regurgitation unmasked after bilateral lung transplantation.

    PubMed

    Udoji, Timothy N; Force, Seth D; Pelaez, Andres

    2013-09-01

    Abstract A 33-year-old female patient with advanced idiopathic pulmonary artery hypertension underwent bilateral lung transplantation. The postsurgical course was complicated by prolonged mechanical ventilation and acute hypoxemia with recurrent episodes of pulmonary edema. An echocardiogram revealed improved right-sided pressures along with a dilated left atrium, a structurally normal mitral valve, and a new posterior-oriented severe mitral regurgitation. The patient's condition improved after treatment with arterial vasodilators and diuretics, and she has remained in World Health Organization functional class I after almost 36 months of follow-up. We hypothesize that cardiac ventricle remodeling and a geometric change in mitral valve apparatus after transplantation led to the hemodynamic changes and recurrent pulmonary edema seen in our patient. Our case is, to our knowledge, the second report of severe valvular regurgitation in a structurally normal mitral valve apparatus in the postoperative period and the first of a patient to be treated without valve replacement.

  9. Echocardiography in evaluation of mitral valve prostheses.

    PubMed

    Watts, E; Nomeir, A M; Barnes, R

    1975-06-01

    Thirty-three patients with mitral valve prostheses were studied with echocardiography in an effort to determine if this technique could be useful in detecting significant abnormalities. Recordings were obtained in the supine position with the transducer directed to record maximum excursion of the prosthesis. Echoes from the struts, poppet and sewing ring were readily recorded. Amplitude of excursion and opening and closing velocities of the poppet were measured. Fifty echocardiographic recordings were obtained from the 33 patients. Of the 33 patients studied, 22 were thought to have "normal" echo tracings while in 11, the tracings were considered "abnormal." Apparent abnormalities consisted of: 1) abnormal diastolic separation between the poppet and strut, 2) increased echoes near the poppet, strut or sewing ring and 3) a combination of both. There was only one instance of suspected "sticking" of the prosthesis. All patients who had "abnormal" studies except one developed complications associated with their prosthesis (90%) compared to only 36% in patients with "normal" tracings. Five patients in each group died. Autopsy studies are described and correlations with the echocardiographic findings are made. In low profile valves reduction in excursion of the disc may be an indication of malfunction. Echocardiography appears to be of value in the assessment of function of mitral valve prostheses.

  10. Percutaneous Transcatheter One-Step Mechanical Aortic Disc Valve Prosthesis Implantation: A Preliminary Feasibility Study in Swine

    SciTech Connect

    Sochman, Jan Peregrin, Jan H.; Rocek, Miloslav; Timmermans, Hans A.; Pavcnik, Dusan; Roesch, Josef

    2006-02-15

    Purpose. To evaluate the feasibility of one-step implantation of a new type of stent-based mechanical aortic disc valve prosthesis (MADVP) above and across the native aortic valve and its short-term function in swine with both functional and dysfunctional native valves. Methods. The MADVP consisted of a folding disc valve made of silicone elastomer attached to either a nitinol Z-stent (Z model) or a nitinol cross-braided stent (SX model). Implantation of 10 MADVPs (6 Z and 4 SX models) was attempted in 10 swine: 4 (2 Z and 2 SX models) with a functional native valve and 6 (4 Z and 2 SX models) with aortic regurgitation induced either by intentional valve injury or by MADVP placement across the native valve. MADVP function was observed for up to 3 hr after implantation. Results. MADVP implantation was successful in 9 swine. One animal died of induced massive regurgitation prior to implantation. Four MADVPs implanted above functioning native valves exhibited good function. In 5 swine with regurgitation, MADVP implantation corrected the induced native valve dysfunction and the device's continuous good function was observed in 4 animals. One MADVP (SX model) placed across native valve gradually migrated into the left ventricle. Conclusion. The tested MADVP can be implanted above and across the native valve in a one-step procedure and can replace the function of the regurgitating native valve. Further technical development and testing are warranted, preferably with a manufactured MADVP.

  11. Percutaneous transcatheter one-step mechanical aortic disc valve prosthesis implantation: a preliminary feasibility study in swine.

    PubMed

    Sochman, Jan; Peregrin, Jan H; Rocek, Miloslav; Timmermans, Hans A; Pavcnik, Dusan; Rösch, Josef

    2006-01-01

    To evaluate the feasibility of one-step implantation of a new type of stent-based mechanical aortic disc valve prosthesis (MADVP) above and across the native aortic valve and its short-term function in swine with both functional and dysfunctional native valves. The MADVP consisted of a folding disc valve made of silicone elastomer attached to either a nitinol Z-stent (Z model) or a nitinol cross-braided stent (SX model). Implantation of 10 MADVPs (6 Z and 4 SX models) was attempted in 10 swine: 4 (2 Z and 2 SX models) with a functional native valve and 6 (4 Z and 2 SX models) with aortic regurgitation induced either by intentional valve injury or by MADVP placement across the native valve. MADVP function was observed for up to 3 hr after implantation. MADVP implantation was successful in 9 swine. One animal died of induced massive regurgitation prior to implantation. Four MADVPs implanted above functioning native valves exhibited good function. In 5 swine with regurgitation, MADVP implantation corrected the induced native valve dysfunction and the device's continuous good function was observed in 4 animals. One MADVP (SX model) placed across native valve gradually migrated into the left ventricle. The tested MADVP can be implanted above and across the native valve in a one-step procedure and can replace the function of the regurgitating native valve. Further technical development and testing are warranted, preferably with a manufactured MADVP.

  12. Experimental study of the boiling mechanism of a liquid film flowing on the surface of a rotating disc

    SciTech Connect

    Kolokotsa, D.; Yanniotis, S.

    2010-11-15

    The boiling mechanism of a liquid film formed on the surface of a smooth horizontal rotating disc was studied using de-ionised water at 2 l/min flow rate, boiling under vacuum at 40 C and 5-10 C wall superheat. Visualization experiments were carried out and video films were taken for rotational speeds from 0 to 1000 rpm. It was observed that nucleate flow boiling prevails in the case of 0 rpm (stationary disc). Nucleate boiling was also observed at 100 and 200 rpm with the number of bubbles and the diameter of the bubbles decreasing as the rotational speed was increasing. At 600 and 1000 rpm rotational speeds, vapor bubbles were not observed. The results of visual observation were in agreement with bubble growth analysis which showed that at heat flux values of 40 kW/m{sup 2}, conditions for bubble growth are favorable at low rotational speeds (<200 rpm) but are unfavorable at high rotational speeds (1000 rpm). (author)

  13. Evaluation of an In Situ Gelable and Injectable Hydrogel Treatment to Preserve Human Disc Mechanical Function Undergoing Physiologic Cyclic Loading Followed by Hydrated Recovery.

    PubMed

    Showalter, Brent L; Elliott, Dawn M; Chen, Weiliam; Malhotra, Neil R

    2015-08-01

    Despite the prevalence of disc degeneration and its contributions to low back problems, many current treatments are palliative only and ultimately fail. To address this, nucleus pulposus replacements are under development. Previous work on an injectable hydrogel nucleus pulposus replacement composed of n-carboxyethyl chitosan, oxidized dextran, and teleostean has shown that it has properties similar to native nucleus pulposus, can restore compressive range of motion in ovine discs, is biocompatible, and promotes cell proliferation. The objective of this study was to determine if the hydrogel implant will be contained and if it will restore mechanics in human discs undergoing physiologic cyclic compressive loading. Fourteen human lumbar spine segments were tested using physiologic cyclic compressive loading while intact, following nucleotomy, and again following treatment of injecting either phosphate buffered saline (PBS) (sham, n = 7) or hydrogel (implant, n = 7). In each compressive test, mechanical parameters were measured immediately before and after 10,000 cycles of compressive loading and following a period of hydrated recovery. The hydrogel implant was not ejected from the disc during 10,000 cycles of physiological compression testing and appeared undamaged when discs were bisected following all mechanical tests. For sham samples, creep during cyclic loading increased (+15%) from creep during nucleotomy testing, while for implant samples creep strain decreased (-3%) toward normal. There was no difference in compressive modulus or compressive strains between implant and sham samples. These findings demonstrate that the implant interdigitates with the nucleus pulposus, preventing its expulsion during 10,000 cycles of compressive loading and preserves disc creep within human L5-S1 discs. This and previous studies provide a solid foundation for continuing to evaluate the efficacy of the hydrogel implant.

  14. The mechanism of disc pallor in experimental optic atrophy. A fluorescein angiographic study.

    PubMed

    Radius, R L; Anderson, D R

    1979-03-01

    Ascending optic atrophy was produced in 13 eyes of owl monkeys (Aotestrivirgatus) by retinal photocoagulation. Color fundus photography and fluorescein angiography were used to study and document the evolution of nerve head abnormalities. The optic nerve heads were also studied histopathologically. Except in certain instances of early transient (relative) filling defects, normal disc fluorescent patterns were preserved, despite clinically apparent optic nerve head pallor. Sectorial defects did not persist into the later phases of the angiogram. These findings may suggest a reduced blood flow, but neither angiographic nor histopathologic studies detected a reduced vascularity in the atrophic optic nerve. Pallor of the optic nerve head seems to result from alterations in the tissue reflectance and translucency following axonal loss and glial reorganization rather than from a decreased microvascular bed.

  15. Lipomatous hamartoma of mitral valve.

    PubMed

    Bhat, Seetharama P S; Gowda, Girish S L; Chikkatur, Raghavendra; Nanjappa, Manjunath C

    2016-01-01

    Primary cardiac tumors are very rare, and tumors arising from cardiac valves are extremely rare. We present a case of lipomatous hamartoma of the mitral valve in a young female. This is the 6th case of lipomatous hamartoma of the mitral valve to be reported. We discuss the operative and histopathological findings.

  16. The Diagnosis of Mitral Stenosis

    PubMed Central

    Munroe, D. S.; Rally, C. R.

    1963-01-01

    The diagnosis of classical mitral stenosis is easy, but many pitfalls lead to over-diagnosis or under-diagnosis. These have been considered in detail and variations in symptoms and signs have been illustrated by case histories. Such variations include: (1) Embolism producing the Leriche syndrome; (2) mitral stenosis with insignificant hemodynamic effect; (3) myxoma masquerading as mitral stenosis; (4) mitral stenosis without apical murmurs, and (5) mitral stenosis with a systolic murmur predominant or alone. In cases of combined mitral and aortic stenosis, the history, radiographic configuration, and incidence of hemoptysis, edema, bronchitis, embolism and atrial fibrillation resemble such findings in cases of isolated mitral stenosis, but the auscultatory signs of the latter may be obscured. The degree of aortic stenosis is difficult to determine in cases of combined stenosis. In the diagnosis of re-stenosis the condition of the valve at the first commissurotomy, the precise procedure performed and the degree of regurgitation produced are of prime importance. Congenital mitral stenosis is rare and is associated with a high incidence of other defects. PMID:13936649

  17. Floppy Mitral Valve (FMV) - Mitral Valve Prolapse (MVP) - Mitral Valvular Regurgitation and FMV/MVP Syndrome.

    PubMed

    Boudoulas, Konstantinos Dean; Pitsis, Antonios A; Boudoulas, Harisios

    2016-01-01

    Mitral valve prolapse (MVP) results from the systolic movement of a portion(s) or segment(s) of the mitral valve leaflet(s) into the left atrium during left ventricular (LV) systole. It should be emphasised that MVP alone, as defined by imaging techniques, may comprise a non-specific finding because it also depends on the LV volume, myocardial contractility and other LV hemodynamics. Thus, a floppy mitral valve (FMV) should be the basis for the diagnosis of MVP. Two types of symptoms may be defined in these patients. In one group, symptoms are directly related to progressive mitral regurgitation and its complications. In the other group, symptoms cannot be explained only by the degree of mitral regurgitation alone; neuroendocrine dysfunction has been implicated for the explanation of symptoms in this group of patients that today is referred as the FMV/MVP syndrome. When significant mitral regurgitation is present in a patient with FMV/MVP, surgical intervention is recommended. In patients with a prohibitive risk for surgery, transcatheter mitral valve repair using a mitraclip device may be considered. Furthermore, transcatheter mitral valve replacement may represent an option in the near future as clinical trials are underway. In this brief review, the current concepts related to FMV/MVP and FMV/MVP syndrome will be discussed.

  18. Mechanism enabling the observation of the formally optically-forbidden 2Ag- and 1Bu- states in resonance-Raman excitation profiles of spheroidene in KBr disc

    NASA Astrophysics Data System (ADS)

    Nagae, Hiroyoshi; Koyama, Yasushi

    2010-07-01

    An expression for the Albrecht A-term resonance-Raman excitation profiles (RREP) of a pigment dispersed in a KBr disc, in such a way that the pigment molecules aggregate in a microcrystal and the microcrystals are dispersed in the KBr disc, is formulated by taking into account the self-absorption of incident and scattered light and the distribution of microcrystals properly. Based on the resultant formula, simulations for the RREPs of spheroidene dispersed in KBr disc were carried out in the spectral region from 12,000 to 24,000 cm -1. Fairly good agreement between the simulations and the observed RREPs was obtained for different concentrations of spheroidene. Mechanisms have been investigated which enable the observation of the formally optically-forbidden (very weakly allowed) 2Ag- and 1Bu- states of spheroidne in RREPs free from the contribution of the optically-allowed 1Bu+ state, and a two-step self-absorption mechanism is proposed.

  19. Transforaminal epidural steroid injections influence Mechanical Diagnosis and Therapy (MDT) pain response classification in candidates for lumbar herniated disc surgery.

    PubMed

    van Helvoirt, Hans; Apeldoorn, Adri T; Knol, Dirk L; Arts, Mark P; Kamper, Steven J; van Tulder, Maurits W; Ostelo, Raymond W

    2016-04-27

    Prospective cohort study. Although lumbar radiculopathy is regarded as a specific diagnosis, the most effective treatment strategy is unclear. Commonly used treatments include transforaminal epidural steroid injections (TESIs) and Mechanical Diagnosis & Therapy (MDT), but no studies have investigated the effectiveness of this combination. MDT differentiates pain centralization (C) from non-centralization (NC), which indicates good vs. poor prognostic validity respectively. The main aims were 1) to determine changes in Mechanical Diagnosis and Therapy (MDT) pain response classifications after transforaminal epidural steroid injections (TESIs) in candidates for lumbar herniated disc surgery and 2) to evaluate differences in short and long term outcomes for patients with different pain response classifications. Candidates for lumbar herniated disc surgery were assessed with a MDT protocol and their pain response classified as centralizing or peripheralizing. For this study,only patients were eligible who showed a peripheralizing pain response at intake. All patients then received TESIs and were reassessed and classified using the MDT protocol, into groups according to pain response (resolved, centralizing, peripheralizing with less pain and peripheralising with severe pain). After receiving targeted treatment based on pain response after TESIs, ranging from advice, MDT or surgery, follow-up assessments were completed at discharge and at 12 months. The primary outcomes were disability (Roland-Morris Disability Questionnaire [RMDQ] for Sciatica), pain severity in leg (visual analogue scale [VAS], 0-100) and global perceived effect (GPE). Linear mixed-models were used to determine between-groups differences in outcome. A total of 77 patients with lumbar disc herniation and peripheralizing symptoms were included. Patients received an average of 2 (SD 0.7) TESIs. After TESIs, 17 patients (22%) were classified as peripheralizing with continuing severe pain.These patients

  20. Crystallization mechanisms and recording characteristics of Si/CuSi bilayer for write-once blu-ray disc

    NASA Astrophysics Data System (ADS)

    Ou, Sin-Liang; Kuo, Po-Cheng; Chen, Sheng-Chi; Tsai, Tsung-Lin; Yeh, Chin-Yen; Chang, Han-Feng; Lee, Chao-Te; Chiang, Donyau

    2011-09-01

    The crystallization mechanisms of Si/CuSi bilayer and its recording characteristics for write-once blu-ray disc (BD-R) were investigated. It was found that Cu3Si phase appeared during the room temperature sputtered deposition. Then, the Si atoms in CuSi layer segregated and crystallized to cubic Si in Cu3Si nucleation sites as the film was annealed at 270 °C. After heating to 500 °C, the grains size of cubic Si phase grew and the hexagonal Si phase was observed. The dynamic tests show that the Si/CuSi bilayer has great feasibility for 1-4× BD-R with the bottom jitter values below 6.5%.

  1. Simulated-physiological loading conditions preserve biological and mechanical properties of caprine lumbar intervertebral discs in ex vivo culture.

    PubMed

    Paul, Cornelis P L; Zuiderbaan, Hendrik A; Zandieh Doulabi, Behrouz; van der Veen, Albert J; van de Ven, Peter M; Smit, Theo H; Helder, Marco N; van Royen, Barend J; Mullender, Margriet G

    2012-01-01

    Low-back pain (LBP) is a common medical complaint and associated with high societal costs. Degeneration of the intervertebral disc (IVD) is assumed to be an important causal factor of LBP. IVDs are continuously mechanically loaded and both positive and negative effects have been attributed to different loading conditions.In order to study mechanical loading effects, degeneration-associated processes and/or potential regenerative therapies in IVDs, it is imperative to maintain the IVDs' structural integrity. While in vivo models provide comprehensive insight in IVD biology, an accompanying organ culture model can focus on a single factor, such as loading and may serve as a prescreening model to reduce life animal testing. In the current study we examined the feasibility of organ culture of caprine lumbar discs, with the hypothesis that a simulated-physiological load will optimally preserve IVD properties.Lumbar caprine IVDs (n = 175) were cultured in a bioreactor up to 21 days either without load, low dynamic load (LDL), or with simulated-physiological load (SPL). IVD stiffness was calculated from measurements of IVD loading and displacement. IVD nucleus, inner- and outer annulus were assessed for cell viability, cell density and gene expression. The extracellular matrix (ECM) was analyzed for water, glycosaminoglycan and total collagen content.IVD biomechanical properties did not change significantly with loading conditions. With SPL, cell viability, cell density and gene expression were preserved up to 21 days. Both unloaded and LDL resulted in decreased cell viability, cell density and significant changes in gene expression, yet no differences in ECM content were observed in any group.In conclusion, simulated-physiological loading preserved the native properties of caprine IVDs during a 21-day culture period. The characterization of caprine IVD response to culture in the LDCS under SPL conditions paves the way for controlled analysis of degeneration- and

  2. Simulated-Physiological Loading Conditions Preserve Biological and Mechanical Properties of Caprine Lumbar Intervertebral Discs in Ex Vivo Culture

    PubMed Central

    Paul, Cornelis P. L.; Zuiderbaan, Hendrik A.; Zandieh Doulabi, Behrouz; van der Veen, Albert J.; van de Ven, Peter M.; Smit, Theo H.; Helder, Marco N.; van Royen, Barend J.; Mullender, Margriet G.

    2012-01-01

    Low-back pain (LBP) is a common medical complaint and associated with high societal costs. Degeneration of the intervertebral disc (IVD) is assumed to be an important causal factor of LBP. IVDs are continuously mechanically loaded and both positive and negative effects have been attributed to different loading conditions. In order to study mechanical loading effects, degeneration-associated processes and/or potential regenerative therapies in IVDs, it is imperative to maintain the IVDs' structural integrity. While in vivo models provide comprehensive insight in IVD biology, an accompanying organ culture model can focus on a single factor, such as loading and may serve as a prescreening model to reduce life animal testing. In the current study we examined the feasibility of organ culture of caprine lumbar discs, with the hypothesis that a simulated-physiological load will optimally preserve IVD properties. Lumbar caprine IVDs (n = 175) were cultured in a bioreactor up to 21 days either without load, low dynamic load (LDL), or with simulated-physiological load (SPL). IVD stiffness was calculated from measurements of IVD loading and displacement. IVD nucleus, inner- and outer annulus were assessed for cell viability, cell density and gene expression. The extracellular matrix (ECM) was analyzed for water, glycosaminoglycan and total collagen content. IVD biomechanical properties did not change significantly with loading conditions. With SPL, cell viability, cell density and gene expression were preserved up to 21 days. Both unloaded and LDL resulted in decreased cell viability, cell density and significant changes in gene expression, yet no differences in ECM content were observed in any group. In conclusion, simulated-physiological loading preserved the native properties of caprine IVDs during a 21-day culture period. The characterization of caprine IVD response to culture in the LDCS under SPL conditions paves the way for controlled analysis of degeneration- and

  3. Quantitation of mitral regurgitation.

    PubMed

    Topilsky, Yan; Grigioni, Francesco; Enriquez-Sarano, Maurice

    2011-01-01

    Mitral regurgitation (MR) is the most frequent valve disease. Nevertheless, evaluation of MR severity is difficult because standard color flow imaging is plagued by considerable pitfalls. Modern surgical indications in asymptomatic patients require precise assessment of MR severity. MR severity assessment is always comprehensive, utilizing all views and methods. Determining trivial/mild MR is usually easy, based on small jet and flow convergence. Specific signs of severe MR (pulmonary venous flow systolic reversal or severe mitral lesion) are useful but insensitive. Quantitative methods, quantitative Doppler (measuring stroke volumes) and flow convergence (aka PISA method), measure the lesion severity as effective regurgitant orifice (ERO) and volume overload as regurgitant volume (RVol). Interpretation of these numbers should be performed in context of specific MR type. In organic MR (intrinsic valve lesions) ERO ≥ 0.40 cm(2) and RVol ≥ 60 mL are associated with poor outcome, while in functional MR ERO ≥ 0.20 cm(2) and RVol ≥ 30 mL mark reduced survival. While MR assessment should always be comprehensive, quantitative assessment of MR provides measures that are strongly predictive of outcome and should be the preferred approach. The ERO and RVol measured by these methods require interpretation in causal context to best predict outcome and determine MR management. Copyright © 2011 Elsevier Inc. All rights reserved.

  4. Quantitation of the mitral tetrahedron in patients with ischemic heart disease using real-time three-dimensional echocardiography to evaluate the geometric determinants of ischemic mitral regurgitation.

    PubMed

    Hsuan, Chin-Feng; Yu, Hsi-Yu; Tseng, Wei-Kung; Lin, Lung-Chun; Hsu, Kwan-Lih; Wu, Chau-Chung

    2013-05-01

    Ischemic mitral regurgitation (IMR) is common in ischemic heart disease and results in poor prognosis. However, the exact mechanism of IMR has not been fully elucidated. Quantitation of the mitral tetrahedron using three-dimentianl (3D) echocardiography is capable of evaluating the geometric determinants and mechanisms of IMR. Forty patients with a history of ST-elevation myocardial infarction at least 6 months earlier were studied. Parameters of mitral deformation and global left ventricular (LV) function and shape were evaluated by 2-dimensional echocardiography. The effective regurgitant orifice (ERO) of IMR was obtained by the quantitative continuous-wave Doppler technique. Three-dimensional (3D) echocardiography was applied to assess the mitral tetrahedron. Mitral valvular tenting area (P < 0.001), mitral annular area (P = 0.032), dilation of the LV in diastole, impairment of the LV ejection fraction, and volume of the spherically shaped LV in systole were greater in patients with an ERO ≥20 mm(2) than in those with an ERO <20 mm(2). In the mitral tetrahedron, only the interpapillary muscle roots distance showed a significant difference (P = 0.004). Multivariate analysis with the logistic regression model showed the systolic mitral tenting area (odds ratio [OR]: 280.49, 95% confidence interval [CI]: 4.59-1.72 × 10(4), P = 0.007) and interpapillary muscle distance (OR: 1.50, 95% CI: 1.03-2.19, P = 0.036) to be independent factors in predicting significant IMR (ERO ≥20 mm(2)). 3D echocardiography can be effectively applied in measuring the mitral tetrahedron and evaluating the mechanism of IMR. Mitral valvular tenting and interpapillary muscle distance are 2 independent factors of significant IMR. © 2013 Wiley Periodicals, Inc.

  5. Early stabilization of traumatic aortic transection and mitral valve regurgitation with extracorporeal membrane oxygenation.

    PubMed

    Lambrechts, David L; Wellens, Francis; Vercoutere, Rik A; De Geest, Raf

    2003-01-01

    We report a case of life-threatening aortic transection with concomitant mitral papillary muscle rupture and severe lung contusion caused by a failed parachute jump. This blunt thoracic injury was treated by early stabilization with extracorporeal membrane oxygenation followed by successful delayed graft repair of the descending aorta and mitral valve replacement with a mechanical prosthesis.

  6. The elastic fibre network of the human lumbar anulus fibrosus: architecture, mechanical function and potential role in the progression of intervertebral disc degeneration

    PubMed Central

    Fazzalari, Nicola L.

    2009-01-01

    Elastic fibres are critical constituents of dynamic biological structures that functionally require elasticity and resilience. The network of elastic fibres in the anulus fibrosus of the intervertebral disc is extensive, however until recently, the majority of histological, biochemical and biomechanical studies have focussed on the roles of other extracellular matrix constituents such as collagens and proteoglycans. The resulting lack of detailed descriptions of elastic fibre network architecture and mechanical function has limited understanding of the potentially important contribution made by elastic fibres to healthy disc function and their possible roles in the progression of disc degeneration. In addition, it has made it difficult to postulate what the consequences of elastic fibre related disorders would be for intervertebral disc behaviour, and to develop treatments accordingly. In this paper, we review recent and historical studies which have examined both the structure and the function of the human lumbar anulus fibrosus elastic fibre network, provide a synergistic discussion in an attempt to clarify its potentially critical contribution both to normal intervertebral disc behaviour and the processes relating to its degeneration, and recommend critical areas for future research. PMID:19263091

  7. Mitral valve surgery - minimally invasive

    MedlinePlus

    ... 2 centimeters) each. The surgeon uses a special computer to control robotic arms during the surgery. A ... heart and mitral valve are displayed on a computer in the operating room. You will need a ...

  8. Mitral Valve Prolapse (For Parents)

    MedlinePlus

    ... Atrial Septal Defect Ventricular Septal Defect Heart and Circulatory System Congenital Heart Defects Getting an EKG (Video) Your Heart & Circulatory System Heart Murmurs Marfan Syndrome Mitral Valve Prolapse EKG ( ...

  9. Mitral Valve Prolapse (For Parents)

    MedlinePlus

    ... be cleared by the doctor to participate in sports. This may involve some additional tests. Although any heart condition can be frightening, mitral valve prolapse likely will not have any effect on your child's everyday life and activities. If ...

  10. Late results of mitral valve repair with glutaraldehyde-treated autologous pericardium.

    PubMed

    Shomura, Yu; Okada, Yukikatsu; Nasu, Michihiro; Koyama, Tadaaki; Yuzaki, Mitsuru; Murashita, Takashi; Fukunaga, Naoto; Konishi, Yasunobu

    2013-06-01

    Mitral valve repair is an established surgical procedure for treating severe organic mitral regurgitation. The mechanisms of mitral regurgitation due to infective endocarditis include rheumatic disease and congenital diseases such as a lack of leaflet tissue, and thus additional material is required to create a functional coaptation surface. We review our experience with 139 patients who underwent mitral valve repair with glutaraldehyde-treated autologous pericardium to treat organic mitral regurgitation between March 1992 and November 2011. Mitral valve disease mainly consisted of infective endocarditis in 51 patients (active, n = 32; healed, n = 19) and rheumatic disease in 47. This procedure was also applied to 12 patients who required reoperation after mitral valve repair for degenerative, congenital, or rheumatic mitral regurgitation. The mean follow-up was 4.5 ± 4.3 years (maximum 19.1). Actuarial survival at 10 years was 84% ± 5%. Eleven reoperations proceeded at a mean of 68 months after surgery. The causes of reoperation were rheumatic disease progression (n = 4), infection (n = 3), patch dehiscence (n = 2), progressive fibrosis of the remaining mitral valve tissue after infective endocarditis (n = 1), and patch tear (n = 1). Mitral valves were replaced in 8 patients and re-repaired in 3 patients. The autologous pericardium was not calcified at the time of reoperation. The rate of freedom from reoperation was 82% ± 7% at 10 years. Mitral valves that might otherwise require replacement can be durably and predictably repaired using glutaraldehyde-treated autologous pericardium. Copyright © 2013 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

  11. Patient-specific mitral leaflet segmentation from 4D ultrasound.

    PubMed

    Schneider, Robert J; Tenenholtz, Neil A; Perrin, Douglas P; Marx, Gerald R; del Nido, Pedro J; Howe, Robert D

    2011-01-01

    Segmenting the mitral valve during closure and throughout a cardiac cycle from four dimensional ultrasound (4DUS) is important for creation and validation of mechanical models and for improved visualization and understanding of mitral valve behavior. Current methods of segmenting the valve from 4DUS either require extensive user interaction and initialization, do not maintain the valve geometry across a cardiac cycle, or are incapable of producing a detailed coaptation line and surface. We present a method of segmenting the mitral valve annulus and leaflets from 4DUS such that a detailed, patient-specific annulus and leaflets are tracked throughout mitral valve closure, resulting in a detailed coaptation region. The method requires only the selection of two frames from a sequence indicating the start and end of valve closure and a single point near a closed valve. The annulus and leaflets are first found through direct segmentation in the appropriate frames and then by tracking the known geometry to the remaining frames. We compared the automatically segmented meshes to expert manual tracings for both a normal and diseased mitral valve, and found an average difference of 0.59 +/- 0.49 mm, which is on the order of the spatial resolution of the ultrasound volumes (0.5-1.0 mm/voxel).

  12. Genetic association analyses highlight biological pathways underlying mitral valve prolapse

    PubMed Central

    Dina, Christian; Bouatia-Naji, Nabila; Tucker, Nathan; Delling, Francesca N.; Toomer, Katelynn; Durst, Ronen; Perrocheau, Maelle; Fernandez-Friera, Leticia; Solis, Jorge; Le Tourneau, Thierry; Chen, Ming-Huei; Probst, Vincent; Bosse, Yohan; Pibarot, Philippe; Zelenika, Diana; Lathrop, Mark; Hercberg, Serge; Roussel, Ronan; Benjamin, Emelia J.; Bonnet, Fabrice; Su Hao, LO; Dolmatova, Elena; Simonet, Floriane; Lecointe, Simon; Kyndt, Florence; Redon, Richard; Le Marec, Hervé; Froguel, Philippe; Ellinor, Patrick T.; Vasan, Ramachandran S.; Bruneval, Patrick; Norris, Russell A.; Milan, David J.; Slaugenhaupt, Susan A.; Levine, Robert A.; Schott, Jean-Jacques; Hagege, Albert A.; Jeunemaitre, Xavier

    2016-01-01

    Non-syndromic mitral valve prolapse (MVP) is a common degenerative cardiac valvulopathy of unknown aetiology that predisposes to mitral regurgitation, heart failure and sudden death1. Previous family and pathophysiological studies suggest a complex pattern of inheritance2–5. We performed a meta-analysis of two genome-wide association studies in 1,442 cases and 2,439 controls. We identified and replicated in 1,422 cases and 6,779 controls six loci and provide functional evidence for candidate genes. We highlight LMCD1 encoding a transcription factor6, for which morpholino knockdown in zebrafish results in atrioventricular (AV) valve regurgitation. A similar zebrafish phenotype was obtained for tensin1 (TNS1), a focal adhesion protein involved in cytoskeleton organization. We also show the expression of tensin1 during valve morphogenesis and describe enlarged posterior mitral leaflets in Tns1−/− mice. This study identifies the first risk loci for MVP and suggests new mechanisms involved in mitral valve regurgitation, the most common indication for mitral valve repair7. PMID:26301497

  13. Genetic association analyses highlight biological pathways underlying mitral valve prolapse.

    PubMed

    Dina, Christian; Bouatia-Naji, Nabila; Tucker, Nathan; Delling, Francesca N; Toomer, Katelynn; Durst, Ronen; Perrocheau, Maelle; Fernandez-Friera, Leticia; Solis, Jorge; Le Tourneau, Thierry; Chen, Ming-Huei; Probst, Vincent; Bosse, Yohan; Pibarot, Philippe; Zelenika, Diana; Lathrop, Mark; Hercberg, Serge; Roussel, Ronan; Benjamin, Emelia J; Bonnet, Fabrice; Lo, Su Hao; Dolmatova, Elena; Simonet, Floriane; Lecointe, Simon; Kyndt, Florence; Redon, Richard; Le Marec, Hervé; Froguel, Philippe; Ellinor, Patrick T; Vasan, Ramachandran S; Bruneval, Patrick; Markwald, Roger R; Norris, Russell A; Milan, David J; Slaugenhaupt, Susan A; Levine, Robert A; Schott, Jean-Jacques; Hagege, Albert A; Jeunemaitre, Xavier

    2015-10-01

    Nonsyndromic mitral valve prolapse (MVP) is a common degenerative cardiac valvulopathy of unknown etiology that predisposes to mitral regurgitation, heart failure and sudden death. Previous family and pathophysiological studies suggest a complex pattern of inheritance. We performed a meta-analysis of 2 genome-wide association studies in 1,412 MVP cases and 2,439 controls. We identified 6 loci, which we replicated in 1,422 cases and 6,779 controls, and provide functional evidence for candidate genes. We highlight LMCD1 (LIM and cysteine-rich domains 1), which encodes a transcription factor and for which morpholino knockdown of the ortholog in zebrafish resulted in atrioventricular valve regurgitation. A similar zebrafish phenotype was obtained with knockdown of the ortholog of TNS1, which encodes tensin 1, a focal adhesion protein involved in cytoskeleton organization. We also showed expression of tensin 1 during valve morphogenesis and describe enlarged posterior mitral leaflets in Tns1(-/-) mice. This study identifies the first risk loci for MVP and suggests new mechanisms involved in mitral valve regurgitation, the most common indication for mitral valve repair.

  14. The high-throughput phenotyping of the viscoelastic behavior of whole mouse intervertebral discs using a novel method of dynamic mechanical testing.

    PubMed

    Liu, Jennifer W; Abraham, Adam C; Tang, Simon Y

    2015-07-16

    Intervertebral disc (IVD) degeneration is highly correlated with lower back pain, and thus understanding the mechanisms of IVD degeneration is critical for the treatment of this disease. Utilizing mouse models to probe the mechanisms of degeneration is especially attractive due to the ease of manipulating mouse models and the availability of transgenics. Yet characterizing the mechanical behavior of mice IVDs remain challenging due to their minute size (approximately 540 μm in height and 1080 μm(2) in cross sectional area). We have thus developed a simple method to dynamically characterize the mechanical properties of intact mouse IVDs. The IVDs were dissected with the endplates intact, and dynamically compressed in the axial direction at 1% and 5% peak strains at 1 Hz. Utilizing this novel approach, we examined the effects of in vitro ribosylation and trypsin digestion for 24 or 72 h on the viscoelastic behavior of the whole murine IVD. Trypsin treatment resulted in a decrease of proteoglycans and loss of disc height, while ribosylation had no effect on structure or proteoglycan composition. The 72 h ribosylation group exhibited a stiffening of the disc, and both treatments significantly reduced viscous behavior of the IVDs, with the effects being more pronounced at 5% strain. Here we demonstrate a novel high-throughput method to mechanically characterize murine IVDs and detect strain-dependent differences in the elastic and the viscous behavior of the treated IVDs due to ribose and trypsin treatments.

  15. Bioinformatics analysis of molecular mechanisms involved in intervertebral disc degeneration induced by TNF-α and IL-1β.

    PubMed

    Xu, Feng; Gao, Feng; Liu, Yadong; Wang, Zhenyu; Zhuang, Xinming; Qu, Zhigang; Ma, Hui; Liu, Yi; Fu, Changfeng; Zhang, Qi; Duan, Xiaoying

    2016-03-01

    The present study aimed to explore the molecular mechanisms associated with intervertebral disc degeneration (IDD) induced by tumor necrosis factor (TNF)‑α and interleukin (IL)‑1β. The microarray dataset no. GSE42611 was downloaded from the Gene Expression Omnibus database. The differentially expressed genes (DEGs) between four experimental nucleus pulposus samples and four control nucleus pulposus samples were analyzed. Subsequently, Gene Ontology (GO) and pathway enrichment analyses of DEGs were performed, followed by protein‑protein interaction (PPI) network construction and prediction of a regulatory network of transcription factor (TFs). Finally, the transcriptional regulatory network was integrated into the PPI network to analyze the network modules. A total of 246 upregulated and 290 downregulated DEGs were identified. The upregulated DEGs were mainly associated with GO terms linked with inflammatory response and apoptotic pathways, while the downregulated DEGs were mainly associated with GO terms linked with cell adhesion and pathways of extracellular matrix ‑ receptor interaction. In the PPI network, IL6, COL1A1, NFKB1 and HIF1A were hub genes, and in addition, NFKB1 and HIF1A were TFs. Pathways of apoptosis and extracellular matrix ‑ receptor interaction may have important roles in IDD progression. IL6, COL1A1 and the TFs NFKB1 and HIF1A may be used as biomarkers for IDD diagnosis and treatment.

  16. Noninvasive diagnostic evaluation of the normal Beall mitral prosthesis.

    PubMed

    Smith, R A; Kerber, R E; Snyder, J W

    1976-01-01

    Phonocardiography and echocardiography were used to examine 20 patients with a normally functioning Beall disc mitral valve prosthesis. Phonocardiographic intervals were: Q-S1 interval 67 +/- 3 msec; A2-OC interval 118 +/- 8 msec. Maximal variation of the Q-S1 interval within one examination was 21 +/- 2 msec, for A2-OC interval it was 31 +/- 5 msec. Echocardiographic disc velocities were: opening velocity 296 +/- 30 mm/sec, closing velocity 414 +/- 44 mm/sec. Maximal variation of the opening velocity was 126 +/- 25 msec; maximal variation of the closing velocity was 334 +/- 57 msec. Abnormal poppet function was suspected in one patient with unusual prolongation and variability of A2-OC interval.

  17. Effect of different light curing methods on mechanical and physical properties of resin-cements polymerized through ceramic discs

    PubMed Central

    CEKIC-NAGAS, Isil; ERGUN, Gulfem

    2011-01-01

    Objective The aim of this study was to compare the polimerization ability of three different light-curing units (quartz tungsten halogen, light-emitting diodes and plasma arc) and their exposure modes (high-intensity and soft-start) by determination of microhardness, water sorption and solubility, and diametral tensile strength of 5 dual-curing resin cements. Material and methods A total of 720 disc-shaped samples (1 mm height and 5 mm diameter) were prepared from different dual-curing resin cements (Duolink, Nexus, Bifix-QM, Panavia F and RelyX Unicem). Photoactivation was performed by using quartz tungsten halogen (high-power and soft-up modes), light-emitting diode (standard and exponential modes) and plasma arc (normal and ramp-curing modes) curing units through ceramic discs. Then the samples (n=8/per group) were stored dry in the dark at 37ºC for 24 h. The Vickers hardness test was performed on the resin cement layer with a microhardness tester (Shimadzu HMV). For sorption and solubility tests; the samples were stored in a desiccator at 37ºC and weighed to a constant mass. The samples were weighed both before and after being immersed in deionized water for different periods of time (24 h and 7 days) and being desiccated. The diametral tensile strength of the samples was tested in a universal testing machine at a crosshead speed of 0.5 mm/min. Data were analyzed statistically by nonparametric Kruskal Wallis and Mann-Whitney U tests at 5% significance level. Results Resin cement and light-curing unit had significant effects (p<0.05) on microhardness, diametral tensile strength, water solubility and sorption. However, no significant differences (p>0.05) were obtained with different modes of LCUs. Conclusion The study indicates that polymerization of resin cements with different light-curing units may result in various polymer structures, and consequently different mechanical and physical properties. PMID:21710093

  18. [Severe mitral regurgitation following resection of a giant atrial myxoma: Case report and literature review].

    PubMed

    Orozco Vinasco, D M; Abello Sánchez, M; Osorio Esquivel, J E

    2013-01-01

    Evaluation of the competence of a mitral valve can often be impossible in the clinical setting of a giant atrial myxoma. A 50-year-old woman with severe mitral regurgitation in the post-bypass period following a myxoma resection was managed with a mitral valve replacement. The absence of mitral insufficiency in the preoperative examination should not be taken as a reliable predictor of normal valve function. So herein, we discuss the role of the intraoperative echocardiographic examination, the underlying mechanisms, and the proposed management of severe mitral regurgitation following the resection of an atrial myxoma. Copyright © 2011 Sociedad Española de Anestesiología, Reanimación y Terapéutica del Dolor. Published by Elsevier España. All rights reserved.

  19. Severe hemolytic anemia after repair of primum septal defect and cleft mitral valve.

    PubMed

    Alehan, D; Doğan, R; Ozkutlu, S; Elshershari, H; Gümrük, F

    2001-01-01

    Two cases are described in which severe mechanical hemolytic anemia developed after surgical repair of primum atrial septal defect (ASD) and cleft mitral valve. In both cases there was residual mitral regurgitation after repair. Moderate mitral regurgitation and collision of the regurgitant jet with the teflon patch used for repair of the primum ASD were detected by color-Doppler echocardiography imaging. Laboratory tests showed normochromic normocytic anemia, increased indirect serum bilirubin, decreased plasma haptoglobin and hemoglobinuria. The peripheral blood smear contained numerous fragmented red cells. Following another surgical correction of the mitral valve (repair or mitral valve replacement), there was no more hemolysis. The two presented cases show that foreign materials in association with localized intracardiac turbulence may cause severe hemolysis.

  20. Mitral valve regurgitation due to annular dilatation caused by a huge and floating left atrial myxoma

    PubMed Central

    Ersoy, Burak; Yeniterzi, Mehmet

    2015-01-01

    We describe a case of mitral valve annular dilatation caused by a huge left atrial myxoma obstructing the mitral valve orifice. A 50-year-old man presenting with palpitation was found to have a huge left atrial myxoma protruding into the left ventricle during diastole, causing severe mitral regurgitation. The diagnosis was made with echocardiogram. Transoesophageal echocardiography revealed a solid mass of 75 × 55 mm. During operation, the myxoma was completely removed from its attachment in the atrium. We preferred to place a mechanical heart valve after an annuloplasty ring because of severely dilated mitral annulus and chordae elongation. The patient had an uneventful recovery. Our case suggests that immediate surgery, careful evaluation of mitral valve annulus preoperatively is recommended. PMID:26702283

  1. Mitral valve regurgitation due to annular dilatation caused by a huge and floating left atrial myxoma.

    PubMed

    Kaya, Mehmet; Ersoy, Burak; Yeniterzi, Mehmet

    2015-09-01

    We describe a case of mitral valve annular dilatation caused by a huge left atrial myxoma obstructing the mitral valve orifice. A 50-year-old man presenting with palpitation was found to have a huge left atrial myxoma protruding into the left ventricle during diastole, causing severe mitral regurgitation. The diagnosis was made with echocardiogram. Transoesophageal echocardiography revealed a solid mass of 75 × 55 mm. During operation, the myxoma was completely removed from its attachment in the atrium. We preferred to place a mechanical heart valve after an annuloplasty ring because of severely dilated mitral annulus and chordae elongation. The patient had an uneventful recovery. Our case suggests that immediate surgery, careful evaluation of mitral valve annulus preoperatively is recommended.

  2. Aortic or Mitral Valve Replacement With the Biocor and Biocor Supra

    ClinicalTrials.gov

    2016-03-09

    Aortic Valve Insufficiency; Aortic Valve Regurgitation; Aortic Valve Stenosis; Aortic Valve Incompetence; Mitral Valve Insufficiency; Mitral Valve Regurgitation; Mitral Valve Stenosis; Mitral Valve Incompetence

  3. Effect of grinding with diamond-disc and -bur on the mechanical behavior of a Y-TZP ceramic.

    PubMed

    Pereira, G K R; Amaral, M; Simoneti, R; Rocha, G C; Cesar, P F; Valandro, L F

    2014-09-01

    This study compared the effects of grinding on the surface micromorphology, phase transformation (t→m), biaxial flexural strength and structural reliability (Weibull analysis) of a Y-TZP (Lava) ceramic using diamond-discs and -burs. 170 discs (15×1.2mm) were produced and divided into 5 groups: without treatment (Ctrl, as-sintered), and ground with 4 different systems: extra-fine (25µm, Xfine) and coarse diamond-bur (181µm, Coarse), 600-grit (25µm, D600) and 120-grit diamond-disc (160µm, D120). Grinding with burs was performed using a contra-angle handpiece (T2-Revo R170, Sirona), while for discs (Allied) a Polishing Machine (Ecomet, Buehler) was employed, both under water-cooling. Micromorphological analysis showed distinct patterns generated by grinding with discs and burs, independent of grit size. There was no statistical difference for characteristic strength values (MPa) between smaller grit sizes (D600 - 1050.08 and Xfine - 1171.33), although they presented higher values compared to Ctrl (917.58). For bigger grit sizes, a significant difference was observed (Coarse - 1136.32>D120 - 727.47). Weibull Modules were statistically similar between the tested groups. Within the limits of this study, from a micromorphological point-of-view, the treatments performed did not generate similar effects, so from a methodological point-of-view, diamond-discs should not be employed to simulate clinical abrasion performed with diamond-burs on Y-TZP ceramics.

  4. Cyanoacrylate medical glue application in intervertebral disc annulus defect repair: Mechanical and biocompatible evaluation.

    PubMed

    Kang, Ran; Li, Haisheng; Lysdahl, Helle; Quang Svend Le, Dang; Chen, Menglin; Xie, Lin; Bünger, Cody

    2017-01-01

    In an attempt to find an ideal closure method during annulus defect repair, we evaluate the use of medical glue by mechanical and biocompatible test. Cyanoacrylate medical glue was applied together with a multilayer microfiber/nanofiber polycaprolactone scaffold and suture in annulus repair. Continuous axial loading and fatigue mechanical test was performed. Furthermore, the in vitro response of mesenchymal stem cell (MSC) to the glue was evaluated by cell viability assay. The in vivo response of annulus tissue to the glue and scaffold was also studied in porcine lumbar spine; histological sections were evaluated after 3 months. Cyanoacrylate glue significantly improved the closure effect in the experimental group with failure load 2825.7 ± 941.6 N, compared to 774.1 ± 281.3 N in the control group without glue application (p < 0.01). The experimental group also withstood the fatigue test. No toxic effect was observed by in vitro cell culture and in vivo implantation. On the basis of this initial evaluation, the use of cyanoacrylate medical glue improves closure effect with no toxicity in annulus defect repair. This method of annulus repair merits further effectiveness study in vivo. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 14-20, 2017.

  5. Beating-heart Mitral Valve Chordal Replacement

    PubMed Central

    Laing, Genevieve; Dupont, Pierre E.

    2011-01-01

    Replacing open-heart surgical procedures with beating-heart interventions substantially decreases the trauma and risk of a procedure. One of the most challenging procedures to perform on the beating heart is valve repair. To address this need, this paper proposes a tool for replacing mitral valve chordae to correct regurgitation. The chordae is secured to the papillary muscle and leaflet using NiTi tissue anchors that also incorporate an internal adjustment mechanism to enable initial adjustment as well as subsequent readjustment of chordae length. Efficacy of the proposed tool for chordae replacement and reduction of regurgitation was demonstrated in an ex-vivo heart simulator. PMID:22254843

  6. [Mitral valve repair with the MitraClip following surgical mitral annuloplasty failure].

    PubMed

    Picard, F; Tadros, V-X; Millán, X; Asgar, A W

    2016-10-28

    Mitral repair using the MitraClip device is on ongoing expansion and has been evaluated in different patterns of mitral regurgitation. Nevertheless, surgical approaches to mitral regurgitation remain the standard of care, at least in absence of contraindication. We report the first Canadian experience of mitral valve repair with the MitraClip following surgical mitral annuloplasty failure. Therapeutic considerations and potential challenges are discussed.

  7. Minimally Invasive Mitral Valve Surgery II

    PubMed Central

    Wolfe, J. Alan; Malaisrie, S. Chris; Farivar, R. Saeid; Khan, Junaid H.; Hargrove, W. Clark; Moront, Michael G.; Ryan, William H.; Ailawadi, Gorav; Agnihotri, Arvind K.; Hummel, Brian W.; Fayers, Trevor M.; Grossi, Eugene A.; Guy, T. Sloane; Lehr, Eric J.; Mehall, John R.; Murphy, Douglas A.; Rodriguez, Evelio; Salemi, Arash; Segurola, Romualdo J.; Shemin, Richard J.; Smith, J. Michael; Smith, Robert L.; Weldner, Paul W.; Lewis, Clifton T. P.; Barnhart, Glenn R.; Goldman, Scott M.

    2016-01-01

    Abstract Techniques for minimally invasive mitral valve repair and replacement continue to evolve. This expert opinion, the second of a 3-part series, outlines current best practices for nonrobotic, minimally invasive mitral valve procedures, and for postoperative care after minimally invasive mitral valve surgery. PMID:27654406

  8. MitraClip Therapy for Mitral Regurgitation: Secondary Mitral Regurgitation.

    PubMed

    Feldman, Ted; Mehta, Arjun; Guerrero, Mayra; Levisay, Justin P; Salinger, Michael H

    2016-01-01

    Therapy for mitral regurgitation (MR) has been synonymous with mitral valve surgery. Operative approaches for degenerative MR repair have been associated with excellent results, with durable long term outcomes. Surgery for functional MR has been less successful. MitraClip has shown promise for functional MR, especiall in patinets who are high risk for surgery. The aggregate of nonrandomized global experience with MitraClip in functional MR has been consistent in showing improvements in symptoms and left ventricular remodeling. It remains to be seen how MitraClip therapy will compare with best medical therapy. The COAPT trial will clarify this question.

  9. Energy dynamics of the intraventricular vortex after mitral valve surgery.

    PubMed

    Nakashima, Kouki; Itatani, Keiichi; Kitamura, Tadashi; Oka, Norihiko; Horai, Tetsuya; Miyazaki, Shohei; Nie, Masaki; Miyaji, Kagami

    2017-04-07

    Mitral valve morphology after mitral valve surgery affects postoperative intraventricular flow patterns and long-term cardiac performance. We visualized ventricular flow by echocardiography vector flow mapping (VFM) to reveal the impact of different mitral valve procedures. Eleven cases of mechanical mitral valve replacement (nine in the anti-anatomical and two in the anatomical position), three bioprosthetic mitral valve replacements, and four mitral valve repairs were evaluated. The mean age at the procedure was 57.4 ± 17.8 year, and the echocardiography VFM in the apical long-axis view was performed 119.9 ± 126.7 months later. Flow energy loss (EL), kinetic pressure (KP), and the flow energy efficiency ratio (EL/KP) were measured. The cases with MVR in the anatomical position and with valve repair had normal vortex directionality ("Clockwise"; N = 6), whereas those with MVR in the anti-anatomical position and with a bioprosthetic mitral valve had the vortex in the opposite direction ("Counterclockwise"; N = 12). During diastole, vortex direction had no effect on EL ("Clockwise": 0.080 ± 0.025 W/m; "Counterclockwise": 0.083 ± 0.048 W/m; P = 0.31) or KP ("Clockwise": 0.117 ± 0.021 N; "Counterclockwise": 0.099 ± 0.057 N; P = 0.023). However, during systole, the EL/KP ratio was significantly higher in the "Counterclockwise" vortex than that in the "Clockwise" vortex (1.056 ± 0.463 vs. 0.617 ± 0.158; P = 0.009). MVP and MVR with a mechanical valve in the anatomical position preserve the physiological vortex, whereas MVR with a mechanical valve in the anti-anatomical position and a bioprosthetic mitral valve generate inefficient vortex flow patterns, resulting in a potential increase in excessive cardiac workload.

  10. Durability of mitral valve repair for mitral regurgitation due to degenerative mitral valve disease.

    PubMed

    David, Tirone E

    2015-09-01

    Degenerative diseases of the mitral valve (MV) are the most common cause of mitral regurgitation in the Western world and the most suitable pathology for MV repair. Several studies have shown excellent long-term durability of MV repair for degenerative diseases. The best follow-up results are obtained with isolated prolapse of the posterior leaflet, however even with isolated prolapse of the anterior leaflet or prolapse of both leaflets the results are gratifying, particularly in young patients. The freedom from reoperation on the MV at 15 years exceeds 90% for isolated prolapse of the posterior leaflet and it is around 70-85% for prolapse of the anterior leaflet or both leaflets. The degree of degenerative change in the MV also plays a role in durability of MV repair. Most studies have used freedom from reoperation to assess durability of the repair but some studies that examined valve function late after surgery suggest that recurrent mitral regurgitation is higher than estimated by freedom from reoperation. We can conclude that MV repair for degenerative mitral regurgitation is associated with low probability of reoperation for up to two decades after surgery. However, almost one-third of the patients develop recurrent moderate or severe mitral regurgitation suggesting that surgery does not arrest the degenerative process.

  11. Durability of mitral valve repair for mitral regurgitation due to degenerative mitral valve disease

    PubMed Central

    2015-01-01

    Degenerative diseases of the mitral valve (MV) are the most common cause of mitral regurgitation in the Western world and the most suitable pathology for MV repair. Several studies have shown excellent long-term durability of MV repair for degenerative diseases. The best follow-up results are obtained with isolated prolapse of the posterior leaflet, however even with isolated prolapse of the anterior leaflet or prolapse of both leaflets the results are gratifying, particularly in young patients. The freedom from reoperation on the MV at 15 years exceeds 90% for isolated prolapse of the posterior leaflet and it is around 70-85% for prolapse of the anterior leaflet or both leaflets. The degree of degenerative change in the MV also plays a role in durability of MV repair. Most studies have used freedom from reoperation to assess durability of the repair but some studies that examined valve function late after surgery suggest that recurrent mitral regurgitation is higher than estimated by freedom from reoperation. We can conclude that MV repair for degenerative mitral regurgitation is associated with low probability of reoperation for up to two decades after surgery. However, almost one-third of the patients develop recurrent moderate or severe mitral regurgitation suggesting that surgery does not arrest the degenerative process. PMID:26539345

  12. Recent developments in percutaneous mitral valve treatment.

    PubMed

    La Canna, Giovanni; Denti, Paolo; Buzzatti, Nicola; Alfieri, Ottavio

    2016-01-01

    In recent years, various percutaneous techniques have been introduced for the treatment of mitral regurgitation (MR), including direct leaflet repair, annuloplasty and left ventricular remodeling. Percutaneous mitral repair targets both primary degenerative and secondary mitral valve regurgitation and may be considered in selected high-surgical-risk patients. The assessment of mitral functional anatomy by echocardiography and computed tomography is crucial when selecting the appropriate repair strategy, according to the regurgitant valve lesion and the surrounding anatomy. The ongoing clinical use of new devices in annuloplasty and percutaneous mitral valve replacement is a promising new scenario in the treatment of MR that goes beyond the conventional surgical approach.

  13. Finite Element Modeling of Mitral Valve Repair

    PubMed Central

    Morgan, Ashley E.; Pantoja, Joe Luis; Weinsaft, Jonathan; Grossi, Eugene; Guccione, Julius M.; Ge, Liang; Ratcliffe, Mark

    2016-01-01

    The mitral valve is a complex structure regulating forward flow of blood between the left atrium and left ventricle (LV). Multiple disease processes can affect its proper function, and when these diseases cause severe mitral regurgitation (MR), optimal treatment is repair of the native valve. The mitral valve (MV) is a dynamic structure with multiple components that have complex interactions. Computational modeling through finite element (FE) analysis is a valuable tool to delineate the biomechanical properties of the mitral valve and understand its diseases and their repairs. In this review, we present an overview of relevant mitral valve diseases, and describe the evolution of FE models of surgical valve repair techniques. PMID:26632260

  14. An acquired Gerbode defect from the left ventricle to the coronary sinus following mitral valve replacement.

    PubMed

    Collis, Richard; Afoke, Jonathan; McGregor, Christopher Ga

    2017-06-01

    We report the management of an acquired Gerbode defect, from the left ventricle to the coronary sinus, following mechanical mitral valve replacement. Following a failed percutaneous closure, surgical patch closure of the defect was performed. © 2017 Wiley Periodicals, Inc.

  15. Aneurysm of the Interatrial Septum and Mitral Valve Proplapse—An Aetiological Association?

    PubMed Central

    Channer, K. S.; Bolton, R.; Rees, J. Russell; Wilde, P.

    1988-01-01

    Mitral valve prolapse is common but aneurysm of the interatrial septum is rare. We report a case in which these two abnormalities of myocardial structure occurred and postulate a common aetiological mechanism. PMID:3256406

  16. Radiofrequency stimulation of intervertebral discs.

    PubMed

    Rosen, Steven; Falco, Frank

    2003-10-01

    The etiology of discogenic pain is poorly understood. The most accepted theory has been that nociceptors in the outer one-third of the annulus fibrosis are responsible for transmitting pain secondary to internal disc disruptions. The concept of "neoneuralization" after disc injury has been disseminated. It has been noted that disc degeneration and injury are associated with ingrowth of neural fibers into the disc annulus. One mechanism of Intradiscal Electrodothermal Therapy (IDET) has been thought to be lesioning of these nociceptors. Five consecutive patients were studied using an intraannular electrode. The Radionics discTRODE was used. It was found impossible to selectively stimulate axial pain fibers using this system. Radicular stimulation was noted in all patients at all levels studied. The implication of these findings concerning the concept of neoneuralization, mechanism of IDET, and possible strategies to decrease discogenic pain are discussed.

  17. Herniated Cervical Disc

    MedlinePlus

    ... center of the disc may start to lose water content, making the disc less effective as a cushion. As a disc deteriorates, the outer layer can also tear. This can allow displacement of the disc's center (called a herniated or ...

  18. Rare Case of Unileaflet Mitral Valve.

    PubMed

    Shah, Jainil; Jain, Tarun; Shah, Sunay; Mawri, Sagger; Ananthasubramaniam, Karthikeyan

    2016-06-01

    Unileaflet mitral valve is the rarest of the congenital mitral valve anomalies and is usually life threatening in infancy due to severe mitral regurgitation (MR). In most asymptomatic individuals, it is mostly due to hypoplastic posterior mitral leaflet. We present a 22-year-old male with palpitations, who was found to have an echocardiogram revealing an elongated anterior mitral valve leaflet with severely hypoplastic posterior mitral valve leaflet appearing as a unileaflet mitral valve without MR. Our case is one of the 11 reported cases in the literature so far. We hereby review those cases and conclude that these patients are likely to be at risk of developing worsening MR later in their lives.

  19. Velocity of closure of Björk-Shiley Convexo-Concave mitral valves: effect of mitral annulus orientation and rate of left ventricular pressure rise.

    PubMed

    Blick, E F; Wieting, D W; Inderbitzen, R; Schreck, S; Stein, P D

    1995-07-01

    The purpose of this study was to determine analytically the hemodynamic factors that affect the closing velocity of the disc of Björk-Shiley convexo-concave (BSCC) prosthetic mitral valves. The motion of the BSCC disk was modelled by Newton's second law written in the form of a second order differential equation which expressed the instantaneous angle of the disc with respect to the valve ring as a function of the instantaneous pressure drop across the mitral valve, delta P(t), and the angle of the pressure gradient vector acting upon the disc during closure. The disc closes in response to the negative pressure drop created by the crossover of left atrial and left ventricular (LV) pressures. The rate of closure depends on the rate of development of the pressure drop across the valve, d delta P/dt, which is largely dependent upon the rate of change of left ventricular pressure during isovolumic contraction, LV dP/dt. The closure rate is also strongly dependent on the initial angle of the pressure drop vector with respect to the disc. The disc was predicted to reach its highest velocity at the moment of impact, based on the Runge-Kutta solution. Modelling suggests that a high LV dP/dt during valve closure or distorted LV geometry, causing the angle between the fully open disc and the pressure drop vector to shift, will cause the valve to have a high velocity at the moment of impact and may produce high impact loads.

  20. CMR predictors of mitral regurgitation in mitral valve prolapse.

    PubMed

    Delling, Francesca N; Kang, Lih Lisa; Yeon, Susan B; Kissinger, Kraig V; Goddu, Beth; Manning, Warren J; Han, Yuchi

    2010-10-01

    We sought to assess the correlation between mitral valve characteristics and severity of mitral regurgitation (MR) in subjects with mitral valve prolapse (MVP) undergoing cardiac magnetic resonance (CMR) imaging. Compared with extensive echocardiographic studies, CMR predictors of MVP-related MR are unknown. The severity of MR at the time of diagnosis has prognostic implication for patients; therefore, the identification of determinants of MR and its progression may be important for risk stratification, follow-up recommendations, and surgical decision making. Seventy-one MVP patients (age 54 ± 11 years, 58% males, left ventricular [LV] ejection fraction 65 ± 5%) underwent cine CMR to assess annular dimensions, maximum systolic anterior and posterior leaflet displacement, papillary muscle (PM) distance to coaptation point and prolapsed leaflets, as well as diastolic anterior and posterior leaflet thickness and length, and LV volumes and mass. Velocity-encoded CMR was used to obtain aortic outflow and to quantify MR volume. Using multiple linear regression analysis including all variables, LV mass (p < 0.001), anterior leaflet length (p = 0.006), and posterior displacement (p = 0.01) were the best determinants of MR volume with a model-adjusted R(2) = 0.6. When the analysis was restricted to valvular characteristics, MR volume correlated with anterior mitral leaflet length (p < 0.001), posterior mitral leaflet displacement (p = 0.003), posterior leaflet thickness (p = 0.008), and the presence of flail (p = 0.005) with a model-adjusted R(2) = 0.5. We also demonstrated acceptable intraobserver and interobserver variability in these measurements. Anterior leaflet length, posterior leaflet displacement, posterior leaflet thickness, and the presence of flail are the best CMR valvular determinants of MVP-related MR. The acceptable intraobserver and interobserver variability of our measurements confirms the role of CMR as an imaging modality for assessment of MVP patients

  1. Color flow imaging of the vena contracta in mitral regurgitation: technical considerations.

    PubMed

    Roberts, Brad J; Grayburn, Paul A

    2003-09-01

    Qualitative grading of mitral regurgitation severity has significant pitfalls secondary to hemodynamic variables, sonographic technique, blood pool entrainment, and the Coanda effect. Volumetric and proximal isovelocity surface area methods can be used to quantitate regurgitant orifice area, regurgitant volume, and regurgitant fraction, but have several limitations and can pose technical challenges. The vena contracta width method provides a rapid and accurate quantitative assessment of mitral regurgitation severity, but is clinically underused. This article is intended to generate an understanding of the flow mechanics of the vena contracta and the sonographic technique required to provide consistent and accurate measurements of vena contracta width in patients with mitral regurgitation.

  2. Coronary fistula associated with double mitral valve disease. A case report.

    PubMed

    Ayala, F; Badui, E; Murillo, H; Almazán, A; Madrid, R; Solorio, S; Verdín, R; Monroy, V

    1996-01-01

    The authors report a case of a 54-year-old white male with a coronary fistula associated with double mitral valve disease. The patient was studied by invasive and non-invasive cardiac methods including coronary angiogram in order to reach the correct diagnosis and to define the successful surgical treatment that included the closure of the fistula, partial resection of the left atrium and insertion of a mechanical mitral valve prosthesis. It is concluded that this case represents a very rare association between coronary fistula and double mitral valve disease.

  3. Nuclear factor-kappa B decoy suppresses nerve injury and improves mechanical allodynia and thermal hyperalgesia in a rat lumbar disc herniation model

    PubMed Central

    Suzuki, Munetaka; Inoue, Gen; Gemba, Takefumi; Watanabe, Tomoko; Ito, Toshinori; Koshi, Takana; Yamauchi, Kazuyo; Yamashita, Masaomi; Orita, Sumihisa; Eguchi, Yawara; Ochiai, Nobuyasu; Kishida, Shunji; Takaso, Masashi; Aoki, Yasuchika; Takahashi, Kazuhisa

    2009-01-01

    Nuclear factor-kappa B (NF-κB) is a gene transcriptional regulator of inflammatory cytokines. We investigated the transduction efficiency of NF-κB decoy to dorsal root ganglion (DRG), as well as the decrease in nerve injury, mechanical allodynia, and thermal hyperalgesia in a rat lumbar disc herniation model. Forty rats were used in this study. NF-κB decoy–fluorescein isothiocyanate (FITC) was injected intrathecally at the L5 level in five rats, and its transduction efficiency into DRG measured. In another 30 rats, mechanical pressure was placed on the DRG at the L5 level and nucleus pulposus harvested from the rat coccygeal disc was transplanted on the DRG. Rats were classified into three groups of ten animals each: a herniation + decoy group, a herniation + oligo group, and a herniation only group. For behavioral testing, mechanical allodynia and thermal hyperalgesia were evaluated. In 15 of the herniation rats, their left L5 DRGs were resected, and the expression of activating transcription factor 3 (ATF-3) and calcitonin gene-related peptide (CGRP) was evaluated immunohistochemically compared to five controls. The total transduction efficiency of NF-κB decoy–FITC in DRG neurons was 10.8% in vivo. The expression of CGRP and ATF-3 was significantly lower in the herniation + decoy group than in the other herniation groups. Mechanical allodynia and thermal hyperalgesia were significantly suppressed in the herniation + decoy group. NF-κB decoy was transduced into DRGs in vivo. NF-κB decoy may be useful as a target for clarifying the mechanism of sciatica caused by lumbar disc herniation. PMID:19308465

  4. Nuclear factor-kappa B decoy suppresses nerve injury and improves mechanical allodynia and thermal hyperalgesia in a rat lumbar disc herniation model.

    PubMed

    Suzuki, Munetaka; Inoue, Gen; Gemba, Takefumi; Watanabe, Tomoko; Ito, Toshinori; Koshi, Takana; Yamauchi, Kazuyo; Yamashita, Masaomi; Orita, Sumihisa; Eguchi, Yawara; Ochiai, Nobuyasu; Kishida, Shunji; Takaso, Masashi; Aoki, Yasuchika; Takahashi, Kazuhisa; Ohtori, Seiji

    2009-07-01

    Nuclear factor-kappa B (NF-kappaB) is a gene transcriptional regulator of inflammatory cytokines. We investigated the transduction efficiency of NF-kappaB decoy to dorsal root ganglion (DRG), as well as the decrease in nerve injury, mechanical allodynia, and thermal hyperalgesia in a rat lumbar disc herniation model. Forty rats were used in this study. NF-kappaB decoy-fluorescein isothiocyanate (FITC) was injected intrathecally at the L5 level in five rats, and its transduction efficiency into DRG measured. In another 30 rats, mechanical pressure was placed on the DRG at the L5 level and nucleus pulposus harvested from the rat coccygeal disc was transplanted on the DRG. Rats were classified into three groups of ten animals each: a herniation + decoy group, a herniation + oligo group, and a herniation only group. For behavioral testing, mechanical allodynia and thermal hyperalgesia were evaluated. In 15 of the herniation rats, their left L5 DRGs were resected, and the expression of activating transcription factor 3 (ATF-3) and calcitonin gene-related peptide (CGRP) was evaluated immunohistochemically compared to five controls. The total transduction efficiency of NF-kappaB decoy-FITC in DRG neurons was 10.8% in vivo. The expression of CGRP and ATF-3 was significantly lower in the herniation + decoy group than in the other herniation groups. Mechanical allodynia and thermal hyperalgesia were significantly suppressed in the herniation + decoy group. NF-kappaB decoy was transduced into DRGs in vivo. NF-kappaB decoy may be useful as a target for clarifying the mechanism of sciatica caused by lumbar disc herniation.

  5. Imaginal disc regeneration takes flight.

    PubMed

    Hariharan, Iswar K; Serras, Florenci

    2017-04-01

    Drosophila imaginal discs, the larval precursors of adult structures such as the wing and leg, are capable of regenerating after damage. During the course of regeneration, discs can sometimes generate structures that are appropriate for a different type of disc, a phenomenon termed transdetermination. Until recently, these phenomena were studied by physically fragmenting discs and then transplanting them into the abdomens of adult female flies. This field has experienced a renaissance following the development of genetic ablation systems that can damage precisely defined regions of the disc without the need for surgery. Together with more traditional approaches, these newer methods have generated many novel insights into wound healing, the mechanisms that drive regenerative growth, plasticity during regeneration and systemic effects of tissue damage and regeneration.

  6. Mitral valve plasty for mitral regurgitation after blunt chest trauma.

    PubMed

    Kumagai, H; Hamanaka, Y; Hirai, S; Mitsui, N; Kobayashi, T

    2001-06-01

    A 21 year-old woman was admitted to our hospital because of chest and back pain after blunt chest trauma. On admission, consciousness was clear and a physical examination showed labored breathing. Her vital signs were stable, but her breathing gradually worsened, and artificial respiration was started. The chest roentgenogram and a subsequent chest computed tomographic scans revealed contusions, hemothorax of the left lung and multiple rib fractures. A transthoracic echocardiography (TTE) revealed normal left ventricular wall motion and mild mitral regurgitation (MR). TTE was carried out repeatedly, and revealed gradually progressive MR and prolapse of the posterior medial leaflet, although there was no congestive heart failure. After her general condition had recovered, surgery was performed. Intraoperative transesophageal echocardiography (TEE) revealed torn chordae at the posterior medial leaflet. The leaflet where the chorda was torn was cut and plicated, and posterior mitral annuloplasty was performed using a prosthetic ring. One month later following discharge, the MR had disappeared on TTE.

  7. Mitral Valve Replacement After Failed Mitral Ring Insertion With or Without Leaflet/Chordal Repair for Pure Mitral Regurgitation.

    PubMed

    Roberts, William C; Moore, Meagan; Ko, Jong Mi; Hamman, Baron L

    2016-06-01

    Mitral repair operations for correction of pure mitral regurgitation (MR) are generally quite successful. Occasionally, however, the reparative procedure incompletely corrects the MR or the MR recurs. From March 1993 to January 2016, twenty nine patients had mitral valve replacement after the initial mitral repair operation, and observations in them were analyzed. All 29 patients at the repair operation had an annular ring inserted and later (<1 year in 6 and >1 year in 21) mitral valve replacement. The cause of the MR before the repair operation appears to have been prolapse in 16 patients (55%), secondary (functional) in 12 (41%) (ischemic in 5), and infective endocarditis which healed in 1 (3%). At the replacement operation the excised anterior mitral leaflet was thickened in all 29 patients. Some degree of stenosis appeared to have been present in 16 of the 29 patients before the replacement operation, although only 10 had an echocardiographic or hemodynamic recording of a transvalvular gradient; at least 11 patients had restricted motion of the posterior mitral leaflet; 10, ring dehiscence; 2, severe hemolysis; and 2, left ventricular outflow obstruction. In conclusion, there are multiple reasons for valve replacement after earlier mitral repair. Uniformly, at the time of the replacement, the mitral leaflets were thickened by fibrous tissue. Measurement of the area enclosed by the 360° rings and study of the excised leaflet suggest that the ring itself may have contributed to the leaflet scarring and development of some transmitral stenosis.

  8. [Valvular surgery for an exercise-induced functional mitral regurgitation in heart failure and preserved ejection fraction: a case study].

    PubMed

    Attari, M; Legrand, M; Philippe, C; Rosak, P

    2013-08-01

    We here report the case of a 67-year-old woman with moderate mitral regurgitation without significant structural abnormalities that get worse during severe recurrent heart failures and preserved ejection fraction with concomitant paroxysmal atrial fibrillation. Atrial fibrillation became permanent and despite a well-controlled cardiac frequency, new heart failure episodes occurred. Exercise doppler echocardiography showed that the mechanism of this mitral regurgitation was a two leaflet mitral tenting. We discuss here the different mechanisms that could induce these kinds of mitral regurgitation with excessive tenting. We emphasize the interest of early detection by exercise doppler echocardiography even when a triggering factor like atrial fibrillation seems to be involved. We also discuss the interest of mitral valve replacement for these patients.

  9. Successful balloon mitral valvotomy in a rare coexistence of Ebstein's anomaly and rheumatic mitral stenosis.

    PubMed

    Sidhu, Navdeep Singh; Kondethimmanahally Rangaiah, Sunil Kumar; Ramesh, Dwarikaprasad; Manjunath, Cholenahally Nanjappa

    2016-05-05

    Co-existence of Ebstein's anomaly of the tricuspid valve with rheumatic mitral stenosis is a very rare occurrence. We report the case of a young man who presented with progressive dyspnoea and was found to have rheumatic mitral stenosis with pulmonary hypertension and Ebstein's anomaly of the tricuspid valve. The patient underwent successful balloon mitral valvotomy resulting in marked improvement of symptoms.

  10. [Left Ventricular Rupture during Both Mitral and Aortic Valve Replacements].

    PubMed

    Kurumisawa, Soki; Aizawa, Kei; Takazawa, Ippei; Sato, Hirotaka; Muraoka, Arata; Ohki, Shinnichi; Saito, Tsutomu; Kawahito, Koji; Misawa, Yoshio

    2015-05-01

    A 73-year-old woman on hemodialysis was transferred to our hospital for surgical treatment of heart valve disease. She required both mitral and aortic valve replacement with mechanical valves, associated with tricuspid annuloplasty. After aortic de-clamping, a massive hemorrhage from the posterior atrioventricular groove was observed. Under repeated cardiac arrest, the left atrium was reopened, the implanted mitral prosthetic valve was removed and a type I left ventricular rupture (Treasure classification) was diagnosed. The lesion was directly repaired with mattress stitches and running sutures, using reinforcement materials such as a glutaraldehyde-treated bovine pericardium. To avoid mechanical stress by the prosthetic valve on the repaired site, a mechanical valve was implanted using a translocation method. The patient suffered from aspiration pneumonia and disuse atrophy for 3 months. However, she was doing well at 1 year post-operation.

  11. [Immediate Results of Mitral Valve Surgery in Asymptomatic Patients With Severe Mitral Regurgitation Due to Degenerative Mitral VaIve Disease].

    PubMed

    Nazarov, V M; Afanasyev, A V; Zheleznev, S I; Bogachev-Prokophiev, A V; Demin, I I; Karaskov, A M

    2015-01-01

    Degenerative mitral valve disease nowadays is the most common cause of mitral insufficiency in developed countries and is associated with high morbidity and mortality. In the last decades repairing the mitral valve has become the operation of choice for treatment of the mitral valve prolapse, enabling to improve the geometry and function of the left ventricle and long-term survival. Nevertheless, the problem of choice of method of management of severe mitral regurgitation in asymptomatic patients with degenerative mitral valve disease remains unsolved. In this article we present immediate results of a prospective comparative study of mitral valve surgery in asymptomatic and symptomatic patients in dependence on NYHA class of heart failure.

  12. A complex transcatheter mitral valve replacement and repair for the treatmemt of refractory severe mitral regurgitation.

    PubMed

    Condado, Jose F; Babaliaros, Vasilis C; Thourani, Vinod H; Jensen, Hanna K; Kim, Dennis W; Kaebnick, Brian W; Block, Peter C; Lerakis, Stamatios

    2017-01-23

    Hybrid transcatheter Mitral Valve-in-Ring and Mitral Valve-in-Valve procedures can be an alternative to traditional surgical valve replacement in patients with high surgical risk. We present a case of a 65-year-old male with recurrent severe mitral regurgitation (MR) that failed two traditional surgical attempts due to severe chest fibrosis. We performed a mitral valve-in ring replacement with a Sapien valve followed by a mitral valve-in-valve replacement with a Melody valve. Patient had a residual paravalvular leak that was closed with a vascular plug. Our case proves that is feasible to treat selected patients with MR using a hybrid transcatheter approach.

  13. Percutaneous Rescue for Critical Mitral Stenosis Late After Mitral Valve Repair.

    PubMed

    Salenger, Rawn; Diao, Xavier; Dawood, Murtaza Y; Herr, Daniel L; Sample, George A; Pichard, Augusto; Gammie, James S

    2016-11-01

    We report a case of catastrophic hemodynamic compromise secondary to pannus ingrowth and severe mitral stenosis occurring years after repair of a nonrheumatic mitral valve. The initial repair included closure of a posterior leaflet cleft and implantation of an annuloplasty ring. We describe a hybrid treatment strategy for this severely compromised patient, which included initial placement of a right ventricular assist device followed by percutaneous balloon mitral valvuloplasty and, eventually, a definitive mitral valve reoperation. This case report reinforces the importance of routine clinical and echocardiographic follow-up for patients after mitral valve repair, and it includes the description of a novel therapeutic approach.

  14. A Remnant Mitral Subvalvular Apparatus Mimicking Aortic Valve Vegetation after Mitral Valve Replacement

    PubMed Central

    Kim, Hyun-Jin; Kim, Kyung-Hee; Choi, Jae-Sung; Kim, Jun-Sung; Kim, Myung-A

    2012-01-01

    Preservation of the subvalvular apparatus has the merits of postoperative outcomes during mitral valve replacement for mitral regurgitation. We performed mitral valve replacement with anterior and posterior leaflet chordal preservation in a 65-year-old woman. On the 2nd postoperative day, routine postoperative trans-thoracic echocardiography showed an unknown aortic subvalvular mobile mass. We report a case of a remnant mitral subvalvular apparatus detected by echocardiography after chordal preserving mitral valve replacement which was confused with postoperative aortic valve vegetation. PMID:22509443

  15. Successful treatment of double-orifice mitral stenosis with percutaneous balloon mitral commissurotomy.

    PubMed

    Patted, Suresh V; Halkati, Prabhu C; Ambar, Sameer S; Sattur, Ameet G

    2012-01-01

    Double-orifice mitral valve (DOMV) is an uncommon congenital anomaly, being present in 0.05% of the general population. The isolated occurrence of this anomaly is very rare and, to our knowledge, no data are currently available on the incidence of an isolated DOMV. A DOMV is characterized by a mitral valve with a single fibrous annulus with 2 orifices opening into the left ventricle (LV). Subvalvular structures, especially the tensor apparatus, invariably show various degrees of abnormality. It can substantially obstruct mitral valve inflow or cause mitral valve incompetence. We present a rare case of nineteen-year-old male who underwent percutaneous mitral balloon commissurotomy in stenotic DOMV.

  16. Ross-Kabbani Operation in an Infant with Mitral Valve Dysplasia

    PubMed Central

    Napoleone, Carlo Pace; Oppido, Guido; Angeli, Emanuela; Giardini, Alessandro; Gargiulo, Gaetano

    2009-01-01

    Background. Mitral valve replacement can be very difficult to obtain in infants because the valve annulus diameter can be smaller than the available prosthesis. Case Report. We describe the case of a 2-month-old female weighing 3.5 kg affected by mitral valve dysplasia leading to severe valve stenosis. Despite full medication, the clinical conditions were critical and surgery was undertaken. The mitral valve was unsuitable for repair and the orifice of mitral anulus was 12 mm, too small for a mechanical prosthesis. Therefore, a Ross-Kabbani operation was undertaken, replacing the mitral valve with the pulmonary autograft and reconstructing the right ventricular outflow tract with an etherograft. Results. The postoperative course was uneventful and the clinical conditions are good at 4-month follow-up. Conclusion. The Ross-Kabbani operation can be an interesting alternative to mitral valve replacement in infants when valve repair is not achievable and there is little space for an intra-annular mechanical prosthesis implant. PMID:20049318

  17. Archival-grade optical disc design and international standards

    NASA Astrophysics Data System (ADS)

    Fujii, Toru; Kojyo, Shinichi; Endo, Akihisa; Kodaira, Takuo; Mori, Fumi; Shimizu, Atsuo

    2015-09-01

    Optical discs currently on the market exhibit large variations in life span among discs, making them unsuitable for certain business applications. To assess and potentially mitigate this problem, we performed accelerated degradation testing under standard ISO conditions, determined the probable disc failure mechanisms, and identified the essential criteria necessary for a stable disc composition. With these criteria as necessary conditions, we analyzed the physical and chemical changes that occur in the disc components, on the basis of which we determined technological measures to reduce these degradation processes. By applying these measures to disc fabrication, we were able to develop highly stable optical discs.

  18. Artificial Disc Replacement

    MedlinePlus

    ... treat this condition, alternatives to disc replacement include fusion, nonoperative care or no treatment. Typically, surgery is ... operative treatment for disc pain has been spinal fusion. This is a surgical procedure in which disc ...

  19. Percutaneous mitral valvotomy in rheumatic mitral stenosis: a new approach.

    PubMed Central

    Commeau, P; Grollier, G; Huret, B; Foucault, J P; Potier, J C

    1987-01-01

    Three patients with rheumatic mitral stenosis were treated with percutaneous mitral valvotomy. A Brockenbrough catheter was advanced transseptally into the left atrium and then into the left ventricle over a long guide wire. An angle wire loop retriever was advanced through a 10 Fr straight catheter via the femoral artery into the left ventricle. The retriever was used to catch the flexible end of the long guide wire. This end of the long guide wire was then drawn out of the right femoral artery by the retriever through the straight catheter. The straight catheter was left in the descending aorta; the Brockenbrough catheter was removed and a 7 Fr balloon catheter was introduced percutaneously over the long guide wire through the femoral vein. This balloon catheter was used for interatrial septal dilatation and right femoral venous dilatation. In two patients this catheter was replaced over the long guide wire with a 9 Fr Schneider-Medintag Grüntzig catheter (3 X 12 mm diameter when inflated) and in the other by a Mansfield (18 mm diameter when inflated). The procedure was well tolerated in these three patients and there were no complications. Haemodynamic function improved, there was appreciable decrease in dyspnoea, and exercise tolerance was increased. This procedure has several advantages: the balloon is more easily positioned through the mitral valve; the stability of the balloon during inflation is improved by traction at both ends of the long guide wire; and there is the option of rapidly exchanging one balloon for a larger one over the long guide wire. This technique seems to be less arrhythmogenic and results in less blood loss because manual compression of the femoral vessels after the procedure is easier. Images Fig 1 Fig 2 Fig 3 Fig 4 Fig 5 PMID:3620253

  20. Robotic Mitral Valve Replacement in Pectus Excavatum.

    PubMed

    Onan, Burak; Bakir, Ihsan

    2016-05-01

    Exposure of the mitral valve can be challenging using conventional sternotomy and thoracotomy incisions in patients with pectus deformity. We report the use of a robotic approach to replace a rheumatic mitral valve in a patient with pectus excavatum. doi: 10.1111/jocs.12740 (J Card Surg 2016;31:306-308). © 2016 Wiley Periodicals, Inc.

  1. Parachute deformity of the mitral valve

    PubMed Central

    Bett, J. H. N.; Stovin, P. G. I.

    1969-01-01

    A case of parachute deformity of the mitral valve, a rare congenital form of mitral stenosis characterized by insertion of the chordae tendineae into a single posterior papillary muscle, is described in an 11-year-old girl. The eleven other cases in the English literature are reviewed. Images PMID:5348334

  2. Minimally Invasive Mitral Valve Surgery I

    PubMed Central

    Ailawadi, Gorav; Agnihotri, Arvind K.; Mehall, John R.; Wolfe, J. Alan; Hummel, Brian W.; Fayers, Trevor M.; Farivar, R. Saeid; Grossi, Eugene A.; Guy, T. Sloane; Hargrove, W. Clark; Khan, Junaid H.; Lehr, Eric J.; Malaisrie, S. Chris; Murphy, Douglas A.; Rodriguez, Evelio; Ryan, William H.; Salemi, Arash; Segurola, Romualdo J.; Shemin, Richard J.; Smith, J. Michael; Smith, Robert L.; Weldner, Paul W.; Goldman, Scott M.; Lewis, Clifton T. P.; Barnhart, Glenn R.

    2016-01-01

    Abstract Widespread adoption of minimally invasive mitral valve repair and replacement may be fostered by practice consensus and standardization. This expert opinion, first of a 3-part series, outlines current best practices in patient evaluation and selection for minimally invasive mitral valve procedures, and discusses preoperative planning for cannulation and myocardial protection. PMID:27654407

  3. Circumplanetary discs around young giant planets: a comparison between core-accretion and disc instability

    NASA Astrophysics Data System (ADS)

    Szulágyi, J.; Mayer, L.; Quinn, T.

    2017-01-01

    Circumplanetary discs can be found around forming giant planets, regardless of whether core accretion or gravitational instability built the planet. We carried out state-of-the-art hydrodynamical simulations of the circumplanetary discs for both formation scenarios, using as similar initial conditions as possible to unveil possible intrinsic differences in the circumplanetary disc mass and temperature between the two formation mechanisms. We found that the circumplanetary discs' mass linearly scales with the circumstellar disc mass. Therefore, in an equally massive protoplanetary disc, the circumplanetary discs formed in the disc instability model can be only a factor of 8 more massive than their core-accretion counterparts. On the other hand, the bulk circumplanetary disc temperature differs by more than an order of magnitude between the two cases. The subdiscs around planets formed by gravitational instability have a characteristic temperature below 100 K, while the core-accretion circumplanetary discs are hot, with temperatures even greater than 1000 K when embedded in massive, optically thick protoplanetary discs. We explain how this difference can be understood as the natural result of the different formation mechanisms. We argue that the different temperatures should persist up to the point when a full-fledged gas giant forms via disc instability; hence, our result provides a convenient criterion for observations to distinguish between the two main formation scenarios by measuring the bulk temperature in the planet vicinity.

  4. Misconceptions and Facts About Mitral Regurgitation.

    PubMed

    Argulian, Edgar; Borer, Jeffrey S; Messerli, Franz H

    2016-09-01

    Mitral regurgitation is a common heart valve disease. It is defined to be primary when it results from the pathology of the mitral valve apparatus itself and secondary when it is caused by distortion of the architecture or function of the left ventricle. Although the diagnosis and management of mitral regurgitation rely heavily on echocardiography, one should bear in mind the caveats and shortcomings of such an approach. Clinical decision making commonly focuses on the indications for surgery, but it is complex and mandates precise assessment of the mitral pathology, symptom status of the patient, and ventricular performance (right and left) among other descriptors. It is important for healthcare providers at all levels to be familiar with the clinical picture, diagnosis, disease course, and management of mitral regurgitation. Copyright © 2016 Elsevier Inc. All rights reserved.

  5. Biomechanics of Disc Degeneration

    PubMed Central

    Palepu, V.; Kodigudla, M.; Goel, V. K.

    2012-01-01

    Disc degeneration and associated disorders are among the most debated topics in the orthopedic literature over the past few decades. These may be attributed to interrelated mechanical, biochemical, and environmental factors. The treatment options vary from conservative approaches to surgery, depending on the severity of degeneration and response to conservative therapies. Spinal fusion is considered to be the “gold standard” in surgical methods till date. However, the association of adjacent level degeneration has led to the evolution of motion preservation technologies like spinal arthroplasty and posterior dynamic stabilization systems. These new technologies are aimed to address pain and preserve motion while maintaining a proper load sharing among various spinal elements. This paper provides an elaborative biomechanical review of the technologies aimed to address the disc degeneration and reiterates the point that biomechanical efficacy followed by long-term clinical success will allow these nonfusion technologies as alternatives to fusion, at least in certain patient population. PMID:22745914

  6. Redundant disc

    NASA Technical Reports Server (NTRS)

    Barack, W. N.; Domas, P. A.; Beekman, S. W. (Inventor)

    1978-01-01

    A rotatable disc is described that consists of parallel plates tightly joined together for rotation about a hub. Each plate is provided with several angularly projecting spaced lands. The lands of each plate are interposed in alternating relationship between the lands of the next adjacent plate. In this manner, circumferential displacement of adjacent sectors in any one plate is prevented in the event that a crack develops. Each plate is redundantly sized so that, in event of structural failure of one plate, the remaining plates support a proportionate share of the load of the failed plate. The plates are prevented from separating laterally through the inclusion of generally radially extending splines which are inserted to interlock cooperating, circumferentially adjacent lands.

  7. In vitro assessment of a combined radiofrequency ablation and cryo-anchoring catheter for treatment of mitral valve prolapse.

    PubMed

    Boronyak, Steven M; Merryman, W David

    2014-03-21

    Percutaneous approaches to mitral valve repair are an attractive alternative to surgical repair or replacement. Radiofrequency ablation has the potential to approximate surgical leaflet resection by using resistive heating to reduce leaflet size, and cryogenic temperatures on a percutaneous catheter can potentially be used to reversibly adhere to moving mitral valve leaflets for reliable application of radiofrequency energy. We tested a combined cryo-anchoring and radiofrequency ablation catheter using excised porcine mitral valves placed in a left heart flow loop capable of reproducing physiologic pressure and flow waveforms. Transmitral flow and pressure were monitored during the cryo-anchoring procedure and compared to baseline flow conditions, and the extent of radiofrequency energy delivery to the mitral valve was assessed post-treatment. Long term durability of radiofrequency ablation treatment was assessed using statically treated leaflets placed in a stretch bioreactor for four weeks. Transmitral flow and pressure waveforms were largely unaltered during cryo-anchoring. Parameter fitting to mechanical data from leaflets treated with radiofrequency ablation and cryo-anchoring revealed significant mechanical differences from untreated leaflets, demonstrating successful ablation of mitral valves in a hemodynamic environment. Picrosirius red staining showed clear differences in morphology and collagen birefringence between treated and untreated leaflets. The durability study indicated that statically treated leaflets did not significantly change size or mechanics over four weeks. A cryo-anchoring and radiofrequency ablation catheter can adhere to and ablate mitral valve leaflets in a physiologic hemodynamic environment, providing a possible percutaneous alternative to surgical leaflet resection of mitral valve tissue.

  8. Pituitary Apoplexy Following Mitral Valvuloplasty

    PubMed Central

    Kim, Young Ha; Son, Dong Wuk; Cha, Seung Heon

    2015-01-01

    Pituitary apoplexy is a rare but potentially life-threatening clinical syndrome caused by the sudden enlargement of a pituitary adenoma secondary to hemorrhage or infarction. Pituitary apoplexy after cardiac surgery is a very rare perioperative complication. Factors associated with open heart surgery that may lead to pituitary apoplexy include hemodynamic instability during cardiopulmonary bypass and systemic heparinization. We report a case of pituitary apoplexy after mitral valvuloplasty with cardiopulmonary bypass. After early pituitary tumor resection and hormonal replacement therapy, the patient made a full recovery. PMID:25932297

  9. Transcatheter mitral valve repair in osteogenesis imperfecta associated mitral valve regurgitation.

    PubMed

    van der Kley, Frank; Delgado, Victoria; Ajmone Marsan, Nina; Schalij, Martin J

    2014-08-01

    Osteogenesis imperfecta is associated with increased prevalence of significant mitral valve regurgitation. Surgical mitral valve repair and replacement are feasible but are associated with increased risk of bleeding and dehiscence of implanted valves may occur more frequently. The present case report describes the outcomes of transcatheter mitral valve repair in a patient with osteogenesis imperfecta. A 60 year-old patient with osteogenesis imperfecta and associated symptomatic moderate to severe mitral regurgitation underwent transthoracic echocardiography which showed a nondilated left ventricle with preserved systolic function and moderate to severe mitral regurgitation. On transoesophageal echocardiography the regurgitant jet originated between the anterolateral scallops of the anterior and posterior leaflets (A1-P1). Considering the comorbidities associated with osteogenesis imperfecta the patient was accepted for transcatheter mitral valve repair using the Mitraclip device (Abbott vascular, Menlo, CA). Under fluoroscopy and 3D transoesophageal echocardiography guidance, a Mitraclip device was implanted between the anterolateral and central scallops with significant reduction of mitral regurgitation. The postoperative evolution was uneventful. At one month follow-up, transthoracic echocardiography showed a stable position of the Mitraclip device with no mitral regurgitation. Transcatheter mitral valve repair is feasible and safe in patients with osteogenesis imperfecta and associated symptomatic significant mitral regurgitation. Copyright © 2014 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier B.V. All rights reserved.

  10. Recurrent stuck mitral valve: eosinophilia an unusual pathology.

    PubMed

    Awasthy, Neeraj; Bhat, Yasser; Radhakrishnan, S; Sharma, Rajesh

    2015-03-01

    Eosinophilia is a very unusual and rare cause of thrombosis of prosthetic mitral valve. We report a 10-year-old male child of recurrent stuck prosthetic mitral valve. The child underwent mitral valve replacement for severe mitral regurgitation secondary to Rheumatic heart disease. He had recurrent prosthetic mitral valve thrombosis, despite desired INR levels. There was associated eosinophilia. The child was treated on the lines of tropical eosinophilia with oral prednisolone and diethylcarbamazine, the eosinophil count dropped significantly with no subsequent episode of stuck mitral valve. We discuss the management of recurrent stuck mitral valve and also eosinophilia as a causative factor for the same.

  11. Mitral prolapse. A heart anomaly in a clinical neuroendocrine context.

    PubMed

    Parlapiano, C; Paoletti, V; Alessandri, N; Campana, E; Giovanniello, T; Pantone, P; Califano, F; Borgia, M C

    2000-06-01

    Mitral valve prolapse was identified as a separate nosological entity by Barlow in 1963. A characteristic of this cardiac anomaly is blood reflux into the left atrium during the systole owing to the lack of adhesion between valve flaps. The presence of symptoms linked to neuroendocrine dysfunctions or to the autonomic nervous system lead to the onset of the pathology known as mitral valve prolapse syndrome (MVPs). It is usually diagnosed by chance in asymptomatic patients during routine tests. MVPs includes complex alterations to the neurovegetative system and a high clinical incidence of neuropsychiatric symptoms, like anxiety and panic attacks. A neuroendocrine mechanism thought to underlie panic attacks was recently proposed based on a biological model. In general, the cardiovascular anomaly manifested by patients with MVPs could be defined in neuroendocrine-constitutional terms.

  12. Surgical treatment of moderate ischemic mitral regurgitation.

    PubMed

    Smith, Peter K; Puskas, John D; Ascheim, Deborah D; Voisine, Pierre; Gelijns, Annetine C; Moskowitz, Alan J; Hung, Judy W; Parides, Michael K; Ailawadi, Gorav; Perrault, Louis P; Acker, Michael A; Argenziano, Michael; Thourani, Vinod; Gammie, James S; Miller, Marissa A; Pagé, Pierre; Overbey, Jessica R; Bagiella, Emilia; Dagenais, François; Blackstone, Eugene H; Kron, Irving L; Goldstein, Daniel J; Rose, Eric A; Moquete, Ellen G; Jeffries, Neal; Gardner, Timothy J; O'Gara, Patrick T; Alexander, John H; Michler, Robert E

    2014-12-04

    Ischemic mitral regurgitation is associated with increased mortality and morbidity. For surgical patients with moderate regurgitation, the benefits of adding mitral-valve repair to coronary-artery bypass grafting (CABG) are uncertain. We randomly assigned 301 patients with moderate ischemic mitral regurgitation to CABG alone or CABG plus mitral-valve repair (combined procedure). The primary end point was the left ventricular end-systolic volume index (LVESVI), a measure of left ventricular remodeling, at 1 year. This end point was assessed with the use of a Wilcoxon rank-sum test in which deaths were categorized as the lowest LVESVI rank. At 1 year, the mean LVESVI among surviving patients was 46.1±22.4 ml per square meter of body-surface area in the CABG-alone group and 49.6±31.5 ml per square meter in the combined-procedure group (mean change from baseline, -9.4 and -9.3 ml per square meter, respectively). The rate of death was 6.7% in the combined-procedure group and 7.3% in the CABG-alone group (hazard ratio with mitral-valve repair, 0.90; 95% confidence interval, 0.38 to 2.12; P=0.81). The rank-based assessment of LVESVI at 1 year (incorporating deaths) showed no significant between-group difference (z score, 0.50; P=0.61). The addition of mitral-valve repair was associated with a longer bypass time (P<0.001), a longer hospital stay after surgery (P=0.002), and more neurologic events (P=0.03). Moderate or severe mitral regurgitation was less common in the combined-procedure group than in the CABG-alone group (11.2% vs. 31.0%, P<0.001). There were no significant between-group differences in major adverse cardiac or cerebrovascular events, deaths, readmissions, functional status, or quality of life at 1 year. In patients with moderate ischemic mitral regurgitation, the addition of mitral-valve repair to CABG did not result in a higher degree of left ventricular reverse remodeling. Mitral-valve repair was associated with a reduced prevalence of moderate or

  13. Proto-planetary disc evolution and dispersal

    NASA Astrophysics Data System (ADS)

    Rosotti, Giovanni Pietro

    2015-05-01

    Planets form from gas and dust discs in orbit around young stars. The timescale for planet formation is constrained by the lifetime of these discs. The properties of the formed planetary systems depend thus on the evolution and final dispersal of the discs, which is the main topic of this thesis. Observations reveal the existence of a class of discs called "transitional", which lack dust in their inner regions. They are thought to be the last stage before the complete disc dispersal, and hence they may provide the key to understanding the mechanisms behind disc evolution. X-ray photoevaporation and planet formation have been studied as possible physical mechanisms responsible for the final dispersal of discs. However up to now, these two phenomena have been studied separately, neglecting any possible feedback or interaction. In this thesis we have investigated what is the interplay between these two processes. We show that the presence of a giant planet in a photo-evaporating disc can significantly shorten its lifetime, by cutting the inner regions from the mass reservoir in the exterior of the disc. This mechanism produces transition discs that for a given mass accretion rate have larger holes than in models considering only X-ray photo-evaporation, constituting a possible route to the formation of accreting transition discs with large holes. These discs are found in observations and still constitute a puzzle for the theory. Inclusion of the phenomenon called "thermal sweeping", a violent instability that can destroy a whole disc in as little as 10 4 years, shows that the outer disc left can be very short-lived (depending on the X-ray luminosity of the star), possibly explaining why very few non accreting transition discs are observed. However the mechanism does not seem to be efficient enough to reconcile with observations. In this thesis we also show that X-ray photo-evaporation naturally explains the observed correlation between stellar masses and accretion

  14. Prosthetic mitral valve thrombosis: can fluoroscopy predict the efficacy of thrombolytic treatment?

    PubMed

    Montorsi, Piero; Cavoretto, Dario; Alimento, Marina; Muratori, Manuela; Pepi, Mauro

    2003-09-09

    Thrombolysis (T) is an effective therapy for prosthetic valve thrombosis (PVT). Debate still exists as to which clinical or noninvasive finding best predict the result of T. The aim of the study was to investigate the role of fluoroscopy (F) to predict efficacy of T in pts with mitral PVT. We evaluated 17 consecutive pts with bileaflet mitral PVT. F criteria for PVT were: abnormal disc motion and calculated opening angle >25 degrees. T was carried out with tissue-type plasminogen activator (tPA; 100 mg over 3 hours followed by heparin infusion for 24 hours) and was considered successful when normalization of leaflet motion and opening angle occurred. Results were evaluated according to symptom duration (<21 days, early PVT; >21 days, late PVT) and to F pattern of PVT (blocked leaflet versus hypomobile leaflet). F showed disc motion alteration in 24 of 34 leaflets: 8 leaflets were blocked, whereas 16 were hypomobile. Early (12.7+/-6.1 days, range 3-21) and late (113+/-114 days, range 28-365) PVT was present in 8 and 7 pts, respectively. Thrombolysis was successful in 20 of 24 leaflets. Blocked leaflet fully recovered only in early PVT (n=4) pts, whereas they remained blocked in late PVT (n=4). On the contrary, in all of the cases with hypomobile leaflet, disc motion normalized regardless duration of symptoms and extent of disc motion reduction. Interestingly, 4 leaflets with late PVT was diagnosed as blocked by trans-thoracic (TTE). F showed a residual disc movement in all: they fully recovered after T. Two pts with late PVT had both leaflets affected (1 blocked +1 hypomobile); although blocked leaflet did not respond to T, the normalization of hypomobile significantly improved clinical condition. F can predict result of T in mitral PVT. PVT with F evidence of hypomobile leaflet always recovers regardless of symptom duration and extent of disc motion reduction, suggesting that the small amount of thrombus needed to interfere with discs motion in bileaflet prostheses

  15. Normal human mitral valve proteome: A preliminary investigation by gel-based and gel-free proteomic approaches.

    PubMed

    Brioschi, Maura; Baetta, Roberta; Ghilardi, Stefania; Gianazza, Erica; Guarino, Anna; Parolari, Alessandro; Polvani, Gianluca; Tremoli, Elena; Banfi, Cristina

    2016-10-01

    The mitral valve is a highly complex structure which regulates blood flow from the left atrium to the left ventricle (LV) avoiding a significant forward gradient during diastole or regurgitation during systole. The integrity of the mitral valve is also essential for the maintenance of normal LV size, geometry, and function. Significant advances in the comprehension of the biological, functional, and mechanical behavior of the mitral valve have recently been made. However, current knowledge of protein components in the normal human mitral valve is still limited and complicated by the low cellularity of this tissue and the presence of high abundant proteins from the extracellular matrix. We employed here an integrated proteomic approach to analyse the protein composition of the normal human mitral valve and reported confident identification of 422 proteins, some of which have not been previously described in this tissue. In particular, we described the ability of pre-MS separation technique based on liquid-phase IEF and SDS-PAGE to identify the largest number of proteins. We also demonstrated that some of these proteins, e.g. αB-Crystallin, septin-11, four-and-a-half LIM domains protein 1, and dermatopontin, are synthesised by interstitial cells isolated from human mitral valves. These initial results provide a valuable basis for future studies aimed at analysing in depth the mitral valve protein composition and at investigating potential pathogenetic molecular mechanisms. Data are available via ProteomeXchange with identifier PXD004397.

  16. Percutaneous repair or surgery for mitral regurgitation.

    PubMed

    Feldman, Ted; Foster, Elyse; Glower, Donald D; Glower, Donald G; Kar, Saibal; Rinaldi, Michael J; Fail, Peter S; Smalling, Richard W; Siegel, Robert; Rose, Geoffrey A; Engeron, Eric; Loghin, Catalin; Trento, Alfredo; Skipper, Eric R; Fudge, Tommy; Letsou, George V; Massaro, Joseph M; Mauri, Laura

    2011-04-14

    Mitral-valve repair can be accomplished with an investigational procedure that involves the percutaneous implantation of a clip that grasps and approximates the edges of the mitral leaflets at the origin of the regurgitant jet. We randomly assigned 279 patients with moderately severe or severe (grade 3+ or 4+) mitral regurgitation in a 2:1 ratio to undergo either percutaneous repair or conventional surgery for repair or replacement of the mitral valve. The primary composite end point for efficacy was freedom from death, from surgery for mitral-valve dysfunction, and from grade 3+ or 4+ mitral regurgitation at 12 months. The primary safety end point was a composite of major adverse events within 30 days. At 12 months, the rates of the primary end point for efficacy were 55% in the percutaneous-repair group and 73% in the surgery group (P=0.007). The respective rates of the components of the primary end point were as follows: death, 6% in each group; surgery for mitral-valve dysfunction, 20% versus 2%; and grade 3+ or 4+ mitral regurgitation, 21% versus 20%. Major adverse events occurred in 15% of patients in the percutaneous-repair group and 48% of patients in the surgery group at 30 days (P<0.001). At 12 months, both groups had improved left ventricular size, New York Heart Association functional class, and quality-of-life measures, as compared with baseline. Although percutaneous repair was less effective at reducing mitral regurgitation than conventional surgery, the procedure was associated with superior safety and similar improvements in clinical outcomes. (Funded by Abbott Vascular; EVEREST II ClinicalTrials.gov number, NCT00209274.).

  17. Development and validation of a bioreactor system for dynamic loading and mechanical characterization of whole human intervertebral discs in organ culture.

    PubMed

    Walter, B A; Illien-Jünger, S; Nasser, P R; Hecht, A C; Iatridis, J C

    2014-06-27

    Intervertebral disc (IVD) degeneration is a common cause of back pain, and attempts to develop therapies are frustrated by lack of model systems that mimic the human condition. Human IVD organ culture models can address this gap, yet current models are limited since vertebral endplates are removed to maintain cell viability, physiological loading is not applied, and mechanical behaviors are not measured. This study aimed to (i) establish a method for isolating human IVDs from autopsy with intact vertebral endplates, and (ii) develop and validate an organ culture loading system for human or bovine IVDs. Human IVDs with intact endplates were isolated from cadavers within 48h of death and cultured for up to 21 days. IVDs remained viable with ~80% cell viability in nucleus and annulus regions. A dynamic loading system was designed and built with the capacity to culture 9 bovine or 6 human IVDs simultaneously while applying simulated physiologic loads (maximum force: 4kN) and measuring IVD mechanical behaviors. The loading system accurately applied dynamic loading regimes (RMS error <2.5N and total harmonic distortion <2.45%), and precisely evaluated mechanical behavior of rubber and bovine IVDs. Bovine IVDs maintained their mechanical behavior and retained >85% viable cells throughout the 3 week culture period. This organ culture loading system can closely mimic physiological conditions and be used to investigate response of living human and bovine IVDs to mechanical and chemical challenges and to screen therapeutic repair techniques.

  18. Development and Validation of a Bioreactor System for Dynamic Loading and Mechanical Characterization of Whole Human Intervertebral Discs in Organ Culture

    PubMed Central

    Walter, BA; Illien-Junger, S; Nasser, P; Hecht, AC; Iatridis, JC

    2014-01-01

    Intervertebral disc (IVD) degeneration is a common cause of back pain, and attempts to develop therapies are frustrated by lack of model systems that mimic the human condition. Human IVD organ culture models can address this gap, yet current models are limited since vertebral endplates are removed to maintain cell viability, physiological loading is not applied, and mechanical behaviors are not measured. This study aimed to (i) establish a method for isolating human IVDs from autopsy with intact vertebral endplates, and (ii) develop and validate an organ culture loading system for human or bovine IVDs. Human IVDs with intact endplates were isolated from cadavers within 48 hours of death and cultured for up to 21 days. IVDs remained viable with ~80% cell viability in nucleus and annulus regions. A dynamic loading system was designed and built with the capacity to culture 9 bovine or 6 human IVDs simultaneously while applying simulated physiologic loads (maximum force: 4kN) and measuring IVD mechanical behaviors. The loading system accurately applied dynamic loading regimes (RMS error <2.5N and total harmonic distortion <2.45%), and precisely evaluated mechanical behavior of rubber and bovine IVDs. Bovine IVDs maintained their mechanical behavior and retained >85% viable cells throughout the 3 week culture period. This organ culture loading system can closely mimic physiological conditions and be used to investigate response of living human and bovine IVDs to mechanical and chemical challenges and to screen therapeutic repair techniques. PMID:24725441

  19. Notochordal cells protect nucleus pulposus cells from degradation and apoptosis: implications for the mechanisms of intervertebral disc degeneration

    PubMed Central

    2011-01-01

    Introduction The relative resistance of non-chondrodystrophic (NCD) canines to degenerative disc disease (DDD) may be due to a combination of anabolic and anti-catabolic factors secreted by notochordal cells within the intervertebral disc (IVD) nucleus pulposus (NP). Factors known to induce DDD include interleukin-1 beta (IL-1ß) and/or Fas-Ligand (Fas-L). Therefore we evaluated the ability of notochordal cell conditioned medium (NCCM) to protect NP cells from IL-1ß and IL-1ß +FasL-mediated cell death and degeneration. Methods We cultured bovine NP cells with IL-1ß or IL-1ß+FasL under hypoxic serum-free conditions (3.5% O2) and treated the cells with either serum-free NCCM or basal medium (Advanced DMEM/F-12). We used flow cytometry to evaluate cell death and real-time (RT-)PCR to determine the gene expression of aggrecan, collagen 2, and link protein, mediators of matrix degradation ADAMTS-4 and MMP3, the matrix protection molecule TIMP1, the cluster of differentiation (CD)44 receptor, the inflammatory cytokine IL-6 and Ank. We then determined the expression of specific apoptotic pathways in bovine NP cells by characterizing the expression of activated caspases-3, -8 and -9 in the presence of IL-1ß+FasL when cultured with NCCM, conditioned medium obtained using bovine NP cells (BCCM), and basal medium all supplemented with 2% FBS. Results NCCM inhibits bovine NP cell death and apoptosis via suppression of activated caspase-9 and caspase-3/7. Furthermore, NCCM protects NP cells from the degradative effects of IL-1ß and IL-1ß+Fas-L by up-regulating the expression of anabolic/matrix protective genes (aggrecan, collagen type 2, CD44, link protein and TIMP-1) and down-regulating matrix degrading genes such as MMP-3. Expression of ADAMTS-4, which encodes a protein for aggrecan remodeling, is increased. NCCM also protects against IL-1+FasL-mediated down-regulation of Ank expression. Furthermore, NP cells treated with NCCM in the presence of IL-1ß+Fas-L down

  20. Challenging mitral valve repair for double-orifice mitral valve with noncompaction of left ventricular myocardium.

    PubMed

    Yamasaki, Manabu; Misumi, Hiroyasu; Abe, Kohei; Kawazoe, Kohei

    2017-02-25

    Double-orifice mitral valve (DOMV) is a relatively rare cardiac anomaly. Although usually associated with various cardiac anomalies, co-presence of DOMV and noncompaction of left ventricular myocardium (NCLVM) is extremely rare. Here, we present a 24-year-old male who underwent mitral valve repair using artificial chordae and annuloplasty at the posterior commissure for severe mitral regurgitation (MR), resulting from flail anterior leaflet of the larger postero-medial orifice and dilatation of left ventricle with NCLVM. One year later, he underwent second mitral valve repair for recurrence of MR. Further endoscopic evaluation of the left ventricle, and reinforcement via artificial ring, enabled us to achieve repair.

  1. Transapical Mitral Valve Replacement for Mixed Native Mitral Stenosis and Regurgitation.

    PubMed

    Bedzra, Edo; Don, Creighton W; Reisman, Mark; Aldea, Gabriel S

    2016-08-01

    A 71-year-old man presented with New York Heart Association (NYHA) class IV heart failure. He had undergone transapical mitral valve replacement for mixed mitral stenosis and mitral regurgitation. At the 1 month follow-up, the patient reported symptom resolution. An echocardiogram revealed a low gradient and no regurgitation. Our case shows that with careful multidisciplinary evaluation, preoperative planning, and patient selection, percutaneous mitral intervention can become an alternative therapy for high-risk patients who cannot undergo conventional surgical therapy.

  2. [Polish nomenclature of lumbar disc disease].

    PubMed

    Radło, Paweł; Smetkowski, Andrzej; Tesiorowski, Maciej

    2014-01-01

    Lumbar disc herniation is one of the most common damage of musculoskeletal system. The incidence of pain of lumbosacral spine is estimated approximately on 60-90% in general population, whereas the incidence of disc herniation in patients experiencing low back pain is about 91%. Despite the high incidence and uncomplicated pathogenesis of disc disease there is a problem with the nomenclature. In the vast majority of cases, the naming confusion stems from ignorance of the etiology of low back pain. Different terminologies: morphological, topographical, Radiological and Clinical are used interchangeably. In addition, diagnosis is presented in a variety of languages: Polish, English and Latin. Moreover, the medical and traditional language are used alternately. The authors found in Polish literature more, than 20 terms to describe lumbar disc herniation. All of these terms in the meaning of the authors are used to determine one pathology--mechanical damage to the intervertebral disc and moving the disc material beyond the anatomical area.

  3. Stabilized Collagen and Elastin-Based Scaffolds for Mitral Valve Tissue Engineering.

    PubMed

    Deborde, Christopher; Simionescu, Dan Teodor; Wright, Cristopher; Liao, Jun; Sierad, Leslie Neil; Simionescu, Agneta

    2016-11-01

    There is a significant clinical need for new approaches to treatment of mitral valve disease. The aim of this study was to develop a tissue-engineered mitral valve scaffold possessing appropriate composition and structure to ensure ideal characteristics of mitral valves, such as large orifice, rapid opening and closure, maintenance of mitral annulus-papillary muscle continuity, in vivo biocompatibility and extended durability. An extracellular matrix-based scaffold was generated, based on the native porcine mitral valve as starting material and a technique for porcine cell removal without causing damage to the matrix components. To stabilize these structures and slow down their degradation, acellular scaffolds were treated with penta-galloyl glucose (PGG), a well-characterized polyphenol with high affinity for collagen and elastin. Biaxial mechanical testing presented similar characteristics for the PGG-treated scaffolds compared to fresh tissues. The extracellular matrix components, crucial for maintaining the valve shape and function, were well preserved in leaflets, and in chordae, as shown by their resistance to collagenase and elastin. When extracted with strong detergents, the PGG-treated scaffolds released a reduced amount of soluble matrix peptides, compared to untreated scaffolds; this correlated with diminished activation of fibroblasts seeded on scaffolds treated with PGG. Cell-seeded scaffolds conditioned for 5 weeks in a valve bioreactor showed good cell viability. Finally, rat subdermal implantation studies showed that PGG-treated mitral valve scaffolds were biocompatible, nonimmunogenic, noninflammatory, and noncalcifying. In conclusion, a biocompatible mitral valve scaffold was developed, which preserved the biochemical composition and structural integrity of the valve, essential for its highly dynamic mechanical demands, and its biologic durability.

  4. The relief of mitral stenosis. An historic step in cardiac surgery.

    PubMed Central

    Khan, M N

    1996-01-01

    Significant progress has been achieved in cardiac surgery in the last 50 years. Mitral valve surgery (especially for the relief of mitral stenosis) has paralleled the innovations and trends of cardiac surgery and often has served as the benchmark of the latest procedures and techniques. A chronological survey of mitral valve surgery is presented, with emphasis on parallels to cardiac surgery in general and with highlights of key figures and events that have conclusively altered the surgeon's approach to and success with cardiac dysfunction. A few surgeons promulgated the idea of cardiac surgery in the late 19th century, but mitral valve surgeries were not performed in earnest until Souttar's and Cutler's initial attempts in the 1920s and were not successful on large groups of patients until Bailey and Harken made independent breakthroughs in the 1940s, finally laying to rest the idea of the "inviolable heart." Cardiopulmonary bypass provided cardiac surgeons with the time to implant mechanical and bioprosthetic valves for palliative benefit to patients. The "perfect" valve has yet to be found, but the Starr-Edwards mechanical valve since its inception in 1961 has been one of the most successful and widely used prosthetic valves. Gradual improvement in surgical technique and growing knowledge of valve function enabled the re-emergence of mitral valve repair in the 1980s as the preferred surgical method of treating mitral stenosis. In the last 10 years, mitral valve balloon dilation has provided a nonsurgical technique for relief of stenosis and represents the broader trend towards interventional techniques. Images PMID:8969024

  5. [Homografts for mitral valve replacement in florid endocarditis--an alternative to prosthetic replacement].

    PubMed

    Gulbins, H; Kreuzer, E; Haushofer, M; Uhlig, A; Reichart, B

    1999-05-01

    Homografts for valve replacement are indicated in acute valve endocarditis. It is assumed that they possess anti-infective properties. Homografts are an established indication in aortic valve replacement. We present our early results with homografts for mitral valve replacement in acute endocarditis. Between July 1996 and March 1998 we used cryopreserved homografts for mitral valve replacement in seven patients. In three cases (age 24, 42, and 34 years) the indication was an acute endocarditis with subsequent severe mitral valve insufficiency. The size of the required homograft was measured preoperatively using transesophageal echocardiography. For implantation the technique described by A. Carpentier was used; for stabilization of the mitral anulus a valvular ring (Physio) was implanted. Follow-up was done every six months including clinical and echocardiographical examinations. After the first postoperative year an Ultrafast-CT was done in addition. One patient had complete mitral valve replacement, in the other two cases the diseased parts of the valve were completely excised and the valve was repaired using a partial homograft. There were no perioperative deaths. In the follow-ups, up to 24 months of uneventful homograft function was documented by echocardiography; no insufficiency > degree I was seen on color Doppler echocardiography. At the last follow-up (mean follow-up 16 months, range 12 to 24 months) the average mitral valve orifice was 2.5 +/- 0.5 cm2, the mean pressure gradient 2.8 +/- 0.8 mm Hg. In Ultrafast-CT no morphological abnormalities of the mitral valves and no dilatation of the left ventricle were seen. There were no signs of a recurrence of the endocarditis in any patient during the follow-up period. Homografts for mitral valve replacement are an interesting alternative to prosthetic valve replacement, especially in younger patients. In cases with acute endocarditis, in which mechanical prosthesis should not be used, a reconstruction or

  6. Mitral Valve Clip for Treatment of Mitral Regurgitation: An Evidence-Based Analysis

    PubMed Central

    Ansari, Mohammed T.; Ahmadzai, Nadera; Coyle, Kathryn; Coyle, Doug; Moher, David

    2015-01-01

    Background Many of the 500,000 North American patients with chronic mitral regurgitation may be poor candidates for mitral valve surgery. Objective The objective of this study was to investigate the comparative effectiveness, harms, and cost-effectiveness of percutaneous mitral valve repair using mitral valve clips in candidates at prohibitive risk for surgery. Data Sources We searched articles in MEDLINE, Embase, and the Cochrane Library published from 1994 to February 2014 for evidence of effectiveness and harms; for economic literature we also searched NHS EED and Tufts CEA registry. Grey literature was also searched. Review Methods Primary studies were sought from existing systematic reviews that had employed reliable search and screening methods. Newer studies were sought by searching the period subsequent to the last search date of the review. Two reviewers screened records and assessed study validity. We used the Cochrane risk of bias tool for randomized, generic assessment for non-randomized studies, and the Phillips checklist for economic studies. Results Ten studies including 1 randomized trial were included. The majority of the direct comparative evidence compared the mitral valve clip repair with surgery in patients not particularly at prohibitive surgical risk. Irrespective of degenerative or functional chronic mitral regurgitation etiology, evidence of effectiveness and harms is inconclusive and of very low quality. Very-low-quality evidence indicates that percutaneous mitral valve clip repair may provide a survival advantage, at least during the first 1 to 2 years, particularly in medically managed chronic functional mitral regurgitation. Because of limitations in the design of studies, the cost-effectiveness of mitral valve clips in patients at prohibitive risk for surgery also could not be established. Limitations Because of serious concerns of risk of bias, indirectness, and imprecision, evidence is of very low quality. Conclusions No meaningful

  7. Regurgitation Hemodynamics Alone Cause Mitral Valve Remodeling Characteristic of Clinical Disease States In Vitro.

    PubMed

    Connell, Patrick S; Azimuddin, Anam F; Kim, Seulgi E; Ramirez, Fernando; Jackson, Matthew S; Little, Stephen H; Grande-Allen, K Jane

    2016-04-01

    Mitral valve regurgitation is a challenging clinical condition that is frequent, highly varied, and poorly understood. While the causes of mitral regurgitation are multifactorial, how the hemodynamics of regurgitation impact valve tissue remodeling is an understudied phenomenon. We employed a pseudo-physiological flow loop capable of long-term organ culture to investigate the early progression of remodeling in living mitral valves placed in conditions resembling mitral valve prolapse (MVP) and functional mitral regurgitation (FMR). Valve geometry was altered to mimic the hemodynamics of controls (no changes from native geometry), MVP (5 mm displacement of papillary muscles towards the annulus), and FMR (5 mm apical, 5 mm lateral papillary muscle displacement, 65% larger annular area). Flow measurements ensured moderate regurgitant fraction for regurgitation groups. After 1-week culture, valve tissues underwent mechanical and compositional analysis. MVP conditioned tissues were less stiff, weaker, and had elevated collagen III and glycosaminoglycans. FMR conditioned tissues were stiffer, more brittle, less extensible, and had more collagen synthesis, remodeling, and crosslinking related enzymes and proteoglycans, including decorin, matrix metalloproteinase-1, and lysyl oxidase. These models replicate clinical findings of MVP (myxomatous remodeling) and FMR (fibrotic remodeling), indicating that valve cells remodel extracellular matrix in response to altered mechanical homeostasis resulting from disease hemodynamics.

  8. Parabolic resection for mitral valve repair.

    PubMed

    Drake, Daniel H; Drake, Charles G; Recchia, Dino

    2010-02-01

    Parabolic resection, named for the shape of the cut edges of the excised tissue, expands on a common 'trick' used by experienced mitral surgeons to preserve tissue and increase the probability of successful repair. Our objective was to describe and clinically analyze this simple modification of conventional resection. Thirty-six patients with mitral regurgitation underwent valve repair using parabolic resection in combination with other techniques. Institution specific mitral data, Society of Thoracic Surgeons data and preoperative, post-cardiopulmonary bypass (PCPB) and postoperative echocardiography data were collected and analyzed. Preoperative echocardiography demonstrated mitral regurgitation ranging from moderate to severe. PCPB transesophageal echocardiography demonstrated no regurgitation or mild regurgitation in all patients. Thirty-day surgical mortality was 2.8%. Serial echocardiograms demonstrated excellent repair stability. One patient (2.9%) with rheumatic disease progressed to moderate regurgitation 33 months following surgery. Echocardiography on all others demonstrated no or mild regurgitation at a mean follow-up of 22.8+/-12.8 months. No patient required mitral reintervention. Longitudinal analysis demonstrated 80% freedom from cardiac death, reintervention and greater than moderate regurgitation at four years following repair. Parabolic resection is a simple technique that can be very useful during complex mitral reconstruction. Early and intermediate echocardiographic studies demonstrate excellent results.

  9. Double-orifice mitral valve treated by percutaneous balloon valvuloplasty.

    PubMed

    Varghese, Thomas George; Revankar, Vinod Raghunath; Papanna, Monica; Srinivasan, Harshini

    2016-07-01

    Double-orifice mitral valve is an rare anomaly characterized by a mitral valve with a single fibrous annulus and 2 orifices that open into the left ventricle. It is often associated with other congenital anomalies, most commonly atrioventricular canal defects, and rarely associated with a stenotic or regurgitant mitral valve. A patient who was diagnosed with congenital double-orifice mitral valve with severe mitral stenosis was treated successfully by percutaneous balloon mitral valvotomy rather than the conventional open surgical approach, demonstrating the utility of percutaneous correction of this anomaly.

  10. Evaluation of a Shape Memory Alloy Reinforced Annuloplasty Band for Minimally Invasive Mitral Valve Repair

    PubMed Central

    Purser, Molly F.; Richards, Andrew L.; Cook, Richard C.; Osborne, Jason A.; Cormier, Denis R.; Buckner, Gregory D.

    2013-01-01

    Purpose An in vitro study using explanted porcine hearts was conducted to evaluate a novel annuloplasty band, reinforced with a two-phase, shape memory alloy, designed specifically for minimally invasive mitral valve repair. Description In its rigid (austenitic) phase, this band provides the same mechanical properties as the commercial semi-rigid bands. In its compliant (martensitic) phase, this band is flexible enough to be introduced through an 8-mm trocar and is easily manipulated within the heart. Evaluation In its rigid phase, the prototype band displayed similar mechanical properties to commercially available semi-rigid rings. Dynamic flow testing demonstrated no statistical differences in the reduction of mitral valve regurgitation. In its flexible phase, the band was easily deployed through an 8-mm trocar, robotically manipulated and sutured into place. Conclusions Experimental results suggest that the shape memory alloy reinforced band could be a viable alternative to flexible and semi-rigid bands in minimally invasive mitral valve repair. PMID:19766827

  11. Mechanical behavior of the human lumbar intervertebral disc with polymeric hydrogel nucleus implant: An experimental and finite element study

    NASA Astrophysics Data System (ADS)

    Joshi, Abhijeet Bhaskar

    The origin of the lower back pain is often the degenerated lumbar intervertebral disc (IVD). We are proposing replacement of the degenerated nucleus by a PVA/PVP polymeric hydrogel implant. We hypothesize that a polymeric hydrogel nucleus implant can restore the normal biomechanics of the denucleated IVD by mimicking the natural load transfer phenomenon as in case of the intact IVD. Lumbar IVDs (n = 15) were harvested from human cadavers. In the first part, specimens were tested in four different conditions for compression: Intact, bone in plug, denucleated and Implanted. Hydrogel nucleus implants were chosen to have line-to-line fit in the created nuclear cavity. In the second part, nucleus implant material (modulus) and geometric (height and diameter) parameters were varied and specimens (n = 9) were tested. Nucleus implants with line-to-line fit significantly restored (88%) the compressive stiffness of the denucleated IVD. The synergistic effect between the implant and the intact annulus resulted in the nonlinear increase in implanted IVD stiffness, where Poisson effect of the hydrogel played major role. Nucleus implant parameters were observed to have a significant effect on the compressive stiffness. All implants with modulus in the tested range restored the compressive stiffness. The undersize implants resulted in incomplete restoration while oversize implants resulted in complete restoration compared to the BI condition. Finite element models (FEM) were developed to simulate the actual test conditions and validated against the experimental results for all conditions. The annulus (defined as hyperelastic, isotropic) mainly determined the nonlinear response of the IVD. Validated FEMs predicted 120--3000 kPa as a feasible range for nucleus implant modulus. FEMs also predicted that overdiameter implant would be more effective than overheight implant in terms of stiffness restoration. Underdiameter implants, initially allowed inward deformation of the annulus and

  12. Effects of controlled dynamic disc distraction on degenerated intervertebral discs: an in vivo study on the rabbit lumbar spine model.

    PubMed

    Kroeber, Markus; Unglaub, Frank; Guehring, Thorsten; Guegring, Thorsten; Nerlich, Andreas; Hadi, Tamer; Lotz, Jeffrey; Carstens, Claus

    2005-01-15

    An in vivo study on the rabbit lumbar spine model. Effects of temporary dynamic distraction on intervertebral discs were studied on the lumbar spine rabbit model to characterize the changes associated with disc distraction and to evaluate feasibility of temporary disc distraction to previously compressed discs in order to stimulate disc regeneration. Studies have shown that accelerated degeneration of the intervertebral disc results from altered mechanical loading conditions. The development of methods for the prevention of disc degeneration and the restoration of disc tissue that has already degenerated are needed. New Zealand white rabbits (n = 32) were used for this study. The rabbits were randomly assigned to one of five groups. In 12 animals, the discs were first loaded for 28 days using a custom-made external loading device to stimulate disc degeneration. After 28 days loading time, the discs in six animals were distracted for 7 days and in six animals for 28 days using the same external device, however, modified as dynamic distraction device. In six animals, the discs were distracted for 28 days without previous loading; and in six animals, the discs were loaded for 28 days and afterwards the loading device removed for 28 days for recovery without distraction. Six animals were sham operated. The external device was situated; however, the discs remained undistracted and they also served as controls. After 28 to 56 days loading and distraction time, the animals were killed and the lumbar spine was harvested for examination. Disc height, disc morphology, cell viability, relative neutral zone, and tangent modulus were measured. After 28 days of loading, the discs demonstrated a significant decrease in disc space. Histologically, disorganization of the architecture of the anulus occurred. The number of dead cells increased significantly in the anulus and cartilage endplate. These changes were reversible after 28 days of distraction. The disc thickness increased

  13. Successful Treatment of Double-Orifice Mitral Stenosis with Percutaneous Balloon Mitral Commissurotomy

    PubMed Central

    Patted, Suresh V.; Halkati, Prabhu C.; Ambar, Sameer S.; Sattur, Ameet G.

    2012-01-01

    Double-orifice mitral valve (DOMV) is an uncommon congenital anomaly, being present in 0.05% of the general population. The isolated occurrence of this anomaly is very rare and, to our knowledge, no data are currently available on the incidence of an isolated DOMV. A DOMV is characterized by a mitral valve with a single fibrous annulus with 2 orifices opening into the left ventricle (LV). Subvalvular structures, especially the tensor apparatus, invariably show various degrees of abnormality. It can substantially obstruct mitral valve inflow or cause mitral valve incompetence. We present a rare case of nineteen-year-old male who underwent percutaneous mitral balloon commissurotomy in stenotic DOMV. PMID:24826244

  14. Nectin-1 spots as a novel adhesion apparatus that tethers mitral cell lateral dendrites in a dendritic meshwork structure of the developing mouse olfactory bulb.

    PubMed

    Inoue, Takahito; Fujiwara, Takeshi; Rikitake, Yoshiyuki; Maruo, Tomohiko; Mandai, Kenji; Kimura, Kazushi; Kayahara, Tetsuro; Wang, Shujie; Itoh, Yu; Sai, Kousyoku; Mori, Masahiro; Mori, Kensaku; Mizoguchi, Akira; Takai, Yoshimi

    2015-08-15

    Mitral cells project lateral dendrites that contact the lateral and primary dendrites of other mitral cells and granule cell dendrites in the external plexiform layer (EPL) of the olfactory bulb. These dendritic structures are critical for odor information processing, but it remains unknown how they are formed. In immunofluorescence microscopy, the immunofluorescence signal for the cell adhesion molecule nectin-1 was concentrated on mitral cell lateral dendrites in the EPL of the developing mouse olfactory bulb. In electron microscopy, the immunogold particles for nectin-1 were symmetrically localized on the plasma membranes at the contacts between mitral cell lateral dendrites, which showed bilateral darkening without dense cytoskeletal undercoats characteristic of puncta adherentia junctions. We named the contacts where the immunogold particles for nectin-1 were symmetrically accumulated "nectin-1 spots." The nectin-1 spots were 0.21 μm in length on average and the distance between the plasma membranes was 20.8 nm on average. In 3D reconstruction of serial sections, clusters of the nectin-1 spots formed a disc-like structure. In the mitral cell lateral dendrites of nectin-1-knockout mice, the immunogold particles for nectin-1 were undetectable and the plasma membrane darkening was electron-microscopically normalized, but the plasma membranes were partly separated from each other. The nectin-1 spots were further identified between mitral cell lateral and primary dendrites and between mitral cell lateral dendrites and granule cell dendritic spine necks. These results indicate that the nectin-1 spots constitute a novel adhesion apparatus that tethers mitral cell dendrites in a dendritic meshwork structure of the developing mouse olfactory bulb.

  15. Emergency mitral valve replacement for acute severe mitral regurgitation following balloon mitral valvotomy: pathophysiology of hemodynamic collapse and peri-operative management issues.

    PubMed

    Bayya, Praveen Reddy; Varma, Praveen Kerala; Raman, Suneel Puthuvassery; Neema, Praveen Kumar

    2014-01-01

    Severe mitral regurgitation (MR) following balloon mitral valvotomy (BMV) needing emergent mitral valve replacement is a rare complication. The unrelieved mitral stenosis is compounded by severe MR leading to acute rise in pulmonary hypertension and right ventricular afterload, decreased coronary perfusion, ischemia and right ventricular failure. Associated septal shift and falling left ventricular preload leads to a vicious cycle of myocardial ischemia and hemodynamic collapse and needs to be addressed emergently before the onset of end organ damage. In this report, we describe the pathophysiology of hemodynamic collapse and peri-operative management issues in a case of mitral valve replacement for acute severe MR following BMV.

  16. Effects of Mitral Annulus Remodeling Following MitraClip Procedure on Reduction of Functional Mitral Regurgitation.

    PubMed

    Hidalgo, Francisco; Mesa, Dolores; Ruiz, Martín; Delgado, Mónica; Rodríguez, Sara; Pardo, Laura; Pan, Manuel; López, Amador; Romero, Miguel A; Suárez de Lezo, José

    2016-11-01

    The percutaneous mitral valve repair procedure (MitraClip) appears to reduce mitral annulus diameter in patients with functional mitral regurgitation, but the relationship between this and regurgitation severity has not been demonstrated. The aim of this study was to determine the effect of mitral annulus remodeling on the reduction of mitral regurgitation in patients with functional etiology. The study included all patients with functional mitral regurgitation treated with MitraClip at our hospital until January 2015. Echocardiogram (iE33 model, Philips) was performed in all patients immediately after device positioning. Changes in the mitral annulus correlated with mitral regurgitation severity, as assessed using the effective regurgitant orifice area. The study included 23 patients (age, 65±14 years; 74% men; left ventricular ejection fraction, 31%±13%; systolic pulmonary artery pressure, 47±10 mmHg). After the procedure, the regurgitant orifice area decreased by 0.30 cm(2)±0.04 cm(2) (P<.0005), from a baseline of 0.49 cm(2)±0.09 cm(2). Anteroposterior diameter decreased by 3.14 mm±1.01 mm (P<.0005) from a baseline of 28.27 mm±4.9 mm, with no changes in the intercommissural diameter (0.50 mm±0.91 mm vs 40.68 mm±4.7 mm; P=.26). A significant association was seen between anteroposterior diameter reduction and regurgitant orifice area reduction (r=.49; P=.020). In patients with functional mitral regurgitation, the MitraClip device produces an immediate reduction in the anteroposterior diameter. This remodeling may be related to the reduction in mitral regurgitation. Copyright © 2016 Sociedad Española de Cardiología. Published by Elsevier España, S.L.U. All rights reserved.

  17. Percutaneous Mitral Valve Repair in Mitral Regurgitation Reduces Cell-Free Hemoglobin and Improves Endothelial Function

    PubMed Central

    Rammos, Christos; Zeus, Tobias; Balzer, Jan; Kubatz, Laura; Hendgen-Cotta, Ulrike B.; Veulemans, Verena; Hellhammer, Katharina; Totzeck, Matthias; Luedike, Peter; Kelm, Malte; Rassaf, Tienush

    2016-01-01

    Background and Objective Endothelial dysfunction is predictive for cardiovascular events and may be caused by decreased bioavailability of nitric oxide (NO). NO is scavenged by cell-free hemoglobin with reduction of bioavailable NO up to 70% subsequently deteriorating vascular function. While patients with mitral regurgitation (MR) suffer from an impaired prognosis, mechanisms relating to coexistent vascular dysfunctions have not been described yet. Therapy of MR using a percutaneous mitral valve repair (PMVR) approach has been shown to lead to significant clinical benefits. We here sought to investigate the role of endothelial function in MR and the potential impact of PMVR. Methods and Results Twenty-seven patients with moderate-to-severe MR treated with the MitraClip® device were enrolled in an open-label single-center observational study. Patients underwent clinical assessment, conventional echocardiography, and determination of endothelial function by measuring flow-mediated dilation (FMD) of the brachial artery using high-resolution ultrasound at baseline and at 3-month follow-up. Patients with MR demonstrated decompartmentalized hemoglobin and reduced endothelial function (cell-free plasma hemoglobin in heme 28.9±3.8 μM, FMD 3.9±0.9%). Three months post-procedure, PMVR improved ejection fraction (from 41±3% to 46±3%, p = 0.03) and NYHA functional class (from 3.0±0.1 to 1.9±1.7, p<0.001). PMVR was associated with a decrease in cell free plasma hemoglobin (22.3±2.4 μM, p = 0.02) and improved endothelial functions (FMD 4.8±1.0%, p<0.0001). Conclusion We demonstrate here that plasma from patients with MR contains significant amounts of cell-free hemoglobin, which is accompanied by endothelial dysfunction. PMVR therapy is associated with an improved hemoglobin decompartmentalization and vascular function. PMID:26986059

  18. Tricuspid regurgitation after successful mitral valve surgery

    PubMed Central

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

    2012-01-01

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

  19. Tricuspid regurgitation after successful mitral valve surgery.

    PubMed

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

    2012-07-01

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

  20. Rapid radiative clearing of protoplanetary discs

    NASA Astrophysics Data System (ADS)

    Haworth, Thomas J.; Clarke, Cathie J.; Owen, James E.

    2016-04-01

    The lack of observed transition discs with inner gas holes of radii greater than ˜50 au implies that protoplanetary discs dispersed from the inside out must remove gas from the outer regions rapidly. We investigate the role of photoevaporation in the final clearing of gas from low mass discs with inner holes. In particular, we study the so-called `thermal sweeping' mechanism which results in rapid clearing of the disc. Thermal sweeping was originally thought to arise when the radial and vertical pressure scalelengths at the X-ray heated inner edge of the disc match. We demonstrate that this criterion is not fundamental. Rather, thermal sweeping occurs when the pressure maximum at the inner edge of the dust heated disc falls below the maximum possible pressure of X-ray heated gas (which depends on the local X-ray flux). We derive new critical peak volume and surface density estimates for rapid radiative clearing which, in general, result in rapid dispersal happening less readily than in previous estimates. This less efficient clearing of discs by X-ray driven thermal sweeping leaves open the issue of what mechanism (e.g. far-ultraviolet heating) can clear gas from the outer disc sufficiently quickly to explain the non-detection of cold gas around weak line T Tauri stars.

  1. Echocardiographic Assessment of Degenerative Mitral Stenosis: A Diagnostic Challenge of an Emerging Cardiac Disease.

    PubMed

    Oktay, Ahmet Afşşin; Gilliland, Yvonne E; Lavie, Carl J; Ramee, Stephen J; Parrino, Patrick E; Bates, Michael; Shah, Sangeeta; Cash, Michael E; Dinshaw, Homeyar; Qamruddin, Salima

    2017-03-01

    Degenerative mitral stenosis (DMS) is characterized by decreased mitral valve (MV) orifice area and increased transmitral pressure gradient due to chronic noninflammatory degeneration and subsequent calcification of the fibrous mitral annulus and the MV leaflets. The "true" prevalence of DMS in the general population is unknown. DMS predominantly affects elderly individuals, many of whom have multiple other comorbidities. Transcatheter MV replacement techniques, although their long-term outcomes are yet to be tested, have been gaining popularity and may emerge as more effective and relatively safer treatment option for patients with DMS. Echocardiography is the primary imaging modality for evaluation of DMS and related hemodynamic abnormalities such as increased transmitral pressure gradient and pulmonary arterial pressure. Classic echocardiographic techniques used for evaluation of mitral stenosis (pressure half time, proximal isovelocity surface area, continuity equation, and MV area planimetry) lack validation for DMS. Direct planimetry with 3-dimensional echocardiography and color flow Doppler is a reasonable technique for determining MV area in DMS. Cardiac computed tomography is an essential tool for planning potential interventions or surgeries for DMS. This article reviews the current concepts on mitral annular calcification and its role in DMS. We then discuss the epidemiology, natural history, differential diagnosis, mechanisms, and echocardiographic assessment of DMS.

  2. Turbine disc sealing assembly

    DOEpatents

    Diakunchak, Ihor S.

    2013-03-05

    A disc seal assembly for use in a turbine engine. The disc seal assembly includes a plurality of outwardly extending sealing flange members that define a plurality of fluid pockets. The sealing flange members define a labyrinth flow path therebetween to limit leakage between a hot gas path and a disc cavity in the turbine engine.

  3. Spontaneous Regression of Herniated Lumbar Disc with New Disc Protrusion in the Adjacent Level

    PubMed Central

    Gürcan, Serkan

    2016-01-01

    Spontaneous regression of herniated lumbar discs was reported occasionally. The mechanisms proposed for regression of disc herniation are still incomplete. This paper describes and discusses a case of spontaneous regression of herniated lumbar discs with a new disc protrusion in the adjacent level. A 41-year-old man was admitted with radiating pain and numbness in the left lower extremity with a left posterolateral disc extrusion at L5-S1 level. He was admitted to hospital with low back pain due to disc herniation caudally immigrating at L4-5 level three years ago. He refused the surgical intervention that was offered and was treated conservatively at that time. He had no neurological deficit and a history of spontaneous regression of the extruded lumbar disc; so, a conservative therapy, including bed rest, physical therapy, nonsteroidal anti-inflammatory drugs, and analgesics, was advised. In conclusion, herniated lumbar disc fragments may regress spontaneously. Reports are prone to advise conservative treatment for extruded or sequestrated lumbar disc herniations. However, these patients should be followed up closely; new herniation at adjacent/different level may occur. Furthermore, it is important to know which herniated disk should be removed and which should be treated conservatively, because disc herniation may cause serious complications as muscle weakness and cauda equine syndrome. PMID:27429818

  4. Influence of Tricuspid Bioprosthetic Mitral Valve Orientation Regarding the Flow Field Inside the Left Ventricle: In Vitro Hydrodynamic Characterization Based on 2D PIV Measurements.

    PubMed

    Bazan, Ovandir; Ortiz, Jayme P; Fukumasu, Newton K; Pacifico, Antonio L; Yanagihara, Jurandir I

    2016-02-01

    The flow patterns of a prosthetic heart valve in the aortic or mitral position can change according to its type and orientation. This work describes the use of 2D particle image velocimetry (PIV) applied to the in vitro flow fields characterization inside the upper part of a left ventricular model at various heart rates and as a function of two orientations of stented tricuspid mitral bioprostheses. In the ventricular model, each mitral bioprosthesis (27 and 31 mm diameter) was installed in two orientations, rotated by 180°, while the aortic bileaflet mechanical valve (27 mm diameter) remained in a fixed orientation. The results (N = 50) showed changes in the intraventricular flow fields according to the mitral bioprostheses positioning. Also, changes in the aortic upstream velocity profiles were noticed as a function of mitral orientations.

  5. Exuberant accessory mitral valve tissue with possible true parachute mitral valve: a case report.

    PubMed

    Nikolic, Aleksandra; Joksimovic, Zoran; Jovovic, Ljiljana

    2012-09-11

    A parachute mitral valve is defined as a unifocal attachment of mitral valve chordae tendineae independent of the number of papillary muscles. Data from the literature suggests that the valve can be distinguished on the basis of morphological features as either a parachute-like asymmetrical mitral valve or a true parachute mitral valve. A parachute-like asymmetrical mitral valve has two papillary muscles; one is elongated and located higher in the left ventricle. A true parachute mitral valve has a single papillary muscle that receives all chordae, as was present in our patient. Patients with parachute mitral valves during childhood have multilevel left-side heart obstructions, with poor outcomes without operative treatment. The finding of a parachute mitral valve in an adult patient is extremely rare, especially as an isolated lesion. In adults, the unifocal attachment of the chordae results in a slightly restricted valve opening and, more frequently, valvular regurgitation. A 40-year-old Caucasian female patient was admitted to a primary care physician due to her recent symptoms of heart palpitation and chest discomfort on effort. Transthoracic echocardiography showed chordae tendineae which were elongated and formed an unusual net shape penetrating into left ventricle cavity. The parasternal short axis view of her left ventricle showed a single papillary muscle positioned on one side in the posteromedial commissure receiving all chordae. Her mitral valve orifice was slightly eccentric and the chordae were converting into a single papillary muscle. Mitral regurgitation was present and it was graded as moderate to severe. Her left atrium was enlarged. There were no signs of mitral stenosis or a subvalvular ring. She did not have a bicuspid aortic valve or coarctation of the ascending aorta. The dimensions and systolic function of her left ventricle were normal. Our patient had a normal body habitus, without signs of heart failure. Her functional status was graded

  6. Exuberant accessory mitral valve tissue with possible true parachute mitral valve: a case report

    PubMed Central

    2012-01-01

    Introduction A parachute mitral valve is defined as a unifocal attachment of mitral valve chordae tendineae independent of the number of papillary muscles. Data from the literature suggests that the valve can be distinguished on the basis of morphological features as either a parachute-like asymmetrical mitral valve or a true parachute mitral valve. A parachute-like asymmetrical mitral valve has two papillary muscles; one is elongated and located higher in the left ventricle. A true parachute mitral valve has a single papillary muscle that receives all chordae, as was present in our patient. Patients with parachute mitral valves during childhood have multilevel left-side heart obstructions, with poor outcomes without operative treatment. The finding of a parachute mitral valve in an adult patient is extremely rare, especially as an isolated lesion. In adults, the unifocal attachment of the chordae results in a slightly restricted valve opening and, more frequently, valvular regurgitation. Case presentation A 40-year-old Caucasian female patient was admitted to a primary care physician due to her recent symptoms of heart palpitation and chest discomfort on effort. Transthoracic echocardiography showed chordae tendineae which were elongated and formed an unusual net shape penetrating into left ventricle cavity. The parasternal short axis view of her left ventricle showed a single papillary muscle positioned on one side in the posteromedial commissure receiving all chordae. Her mitral valve orifice was slightly eccentric and the chordae were converting into a single papillary muscle. Mitral regurgitation was present and it was graded as moderate to severe. Her left atrium was enlarged. There were no signs of mitral stenosis or a subvalvular ring. She did not have a bicuspid aortic valve or coarctation of the ascending aorta. The dimensions and systolic function of her left ventricle were normal. Our patient had a normal body habitus, without signs of heart failure

  7. Rapidly progressing, massive mitral annular calcification. Occurrence in a patient with chronic renal failure.

    PubMed

    Depace, N L; Rohrer, A H; Kotler, M N; Brezin, J H; Parry, W R

    1981-11-01

    Calcification of the mitral annulus developed in a patient while undergoing dialysis. The rapid onset of events corresponded to the onset of end-stage renal failure and uncontrolled secondary hyperparathyroidism. Sequential echocardiograms verified the progression of calcification of the annulus as well as the valve. A new systolic and diastolic murmur and reduced valve orifice on two-dimensional echocardiography suggested acquired nonrheumatic mitral stenosis and insufficiency. We propose that metastatic calcium deposition rather than long-term hypertensive and degenerative effects was the predominant mechanism for massive calcification of the annulus and valve. It is suggested that M-mode echocardiography be used sequentially to follow both the occurrence and progression of calcification of the mitral annulus or valve in patients with chronic renal failure, secondary hyperparathyroidism, or both.

  8. Bioprosthetic mitral valve dysfunction due to native valve preserving procedure.

    PubMed

    Matsuno, Yukihiro; Mori, Yoshio; Umeda, Yukio; Takiya, Hiroshi

    2016-03-01

    Mitral valve replacement with preservation of the mitral leaflets and subvalvular apparatus is considered to maintain left ventricular geometry and function and reduce the risk of myocardial rupture. However, the routine use of this technique may lead to early complications such as left ventricular outflow tract obstruction and even mitral inflow obstruction, requiring reoperation. We describe a rare case of bioprosthetic mitral valve dysfunction caused by a native valve preserving procedure.

  9. Acute severe mitral regurgitation. Pathophysiology, clinical recognition, and management.

    PubMed

    DePace, N L; Nestico, P F; Morganroth, J

    1985-02-01

    Acute severe mitral regurgitation often goes unrecognized as an emergency requiring prompt, lifesaving treatment. Its causes, physical signs, natural history, echocardiographic features, and findings on chest roentgenography, electrocardiography, and nuclear scintigraphic scanning are reviewed. Acute severe mitral insufficiency can be differentiated from chronic severe mitral insufficiency by noninvasive two-dimensional echocardiography. M-mode echocardiography is a valuable tool in evaluating mitral prosthetic paravalvular regurgitation.

  10. Minimally invasive, robotic, and off-pump mitral valve surgery.

    PubMed

    Woo, Y Joseph; Rodriguez, Evelio; Atluri, Pavan; Chitwood, W Randolph

    2006-01-01

    A significant transformation is occurring in the management of mitral valve disease. Earlier surgery is now recommended. Mitral valve repair is the standard of care, and newer methods of reconstructing the mitral valve are developing. Surgery with videoscopic assistance can be effectively performed without sternotomy. Robotics systems are gaining wider adoption. Implantable devices to repair or replace the mitral valve off-pump and percutaneously are emerging.

  11. [Diagnosis and differential therapy of mitral stenosis].

    PubMed

    Fassbender, D; Schmidt, H K; Seggewiss, H; Mannebach, H; Bogunovic, N

    1998-11-01

    Clinical symptoms and diagnostic findings in patients with mitral stenosis are usually determined by the extent of the stenosis. Compared to a normal mitral valve area (MVA) of > 4 cm2, MVA in patients with severe mitral stenosis is usually reduced to < 1.5 cm2. In older patients symptoms are frequently influenced by concomitant diseases (e.g. atrial fibrillation, arterial hypertension or lung disease). An important diagnostic element besides anamnesis, auscultation, ECG and chest X-ray is echocardiography, which is required in order to measure non-invasively and reliably the mitral valve gradient (MVG), the MVA and morphologic changes to the valves, as well as concomitant valvular disease, ventricular functions and, where appropriate, left-atrial thrombi. In addition to the surgical treatment of patients with severe mitral stenosis, which has been an established procedure for 50 years, percutaneous balloon mitral valvuloplasty (MVP) has recently established itself as an alternative option. At the current time, the Inoue technique seems to display the most advantages. Following transseptal puncture, the Inoue balloon is guided transvenously into the left atrium and then into the left ventricle using a special support wire. The balloon is short and soft. Its special unfolding character enables it to be placed securely in the mitral valve without any risk of ventricular perforation (Figure 1). As with surgical commissurotomy, balloon valvuloplasty leads to a separation of fused commissures. This results in a significant reduction of MVG, accompanied by an increase in the MVA (Figure 2). The results and success of MVP are influenced by the morphology of the valves and the changes to the subvalvular apparatus. In randomized studies, the results of surgical commissurotomy were comparable with those of balloon mitral valvulotomy. In our hospital, an increase in MVA from 1.0 to 1.8 cm2 could be achieved in 899 patients (mean age 56 +/- 3 years). In younger patients with

  12. Mitral Valve Prolapse in Persons with Down Syndrome.

    ERIC Educational Resources Information Center

    Pueschel, Siegfried M.; Werner, John Christian

    1994-01-01

    Examination of 36 home-reared young adults with Down's syndrome found that 20 had abnormal echocardiographic findings. Thirteen had mitral valve prolapse, three had mitral valve prolapse and aortic insufficiency, two had only aortic insufficiency, and two had other mitral valve disorders. Theories of pathogenesis and relationship to exercise and…

  13. Right Atrial Clot Formation Early after Percutaneous Mitral Balloon Valvuloplasty

    PubMed Central

    Ateş, Ahmet Hakan; Aksakal, Aytekin; Yücel, Huriye; Atasoy Günaydın, İlksen; Ekbul, Adem; Yaman, Mehmet

    2016-01-01

    Mitral balloon valvuloplasty which has been used for the treatment of rheumatic mitral stenosis (MS) for several decades can cause serious complications. Herein, we presented right atrial clot formation early after percutaneous mitral balloon valvuloplasty which was treated successfully with unfractioned heparin infusion. PMID:28105049

  14. Drosophila Lipophorin Receptors Mediate the Uptake of Neutral Lipids in Oocytes and Imaginal Disc Cells by an Endocytosis-Independent Mechanism

    PubMed Central

    Parra-Peralbo, Esmeralda; Culi, Joaquim

    2011-01-01

    Lipids are constantly shuttled through the body to redistribute energy and metabolites between sites of absorption, storage, and catabolism in a complex homeostatic equilibrium. In Drosophila, lipids are transported through the hemolymph in the form of lipoprotein particles, known as lipophorins. The mechanisms by which cells interact with circulating lipophorins and acquire their lipidic cargo are poorly understood. We have found that lipophorin receptor 1 and 2 (lpr1 and lpr2), two partially redundant genes belonging to the Low Density Lipoprotein Receptor (LDLR) family, are essential for the efficient uptake and accumulation of neutral lipids by oocytes and cells of the imaginal discs. Females lacking the lpr2 gene lay eggs with low lipid content and have reduced fertility, revealing a central role for lpr2 in mediating Drosophila vitellogenesis. lpr1 and lpr2 are transcribed into multiple isoforms. Interestingly, only a subset of these isoforms containing a particular LDLR type A module mediate neutral lipid uptake. Expression of these isoforms induces the extracellular stabilization of lipophorins. Furthermore, our data indicate that endocytosis of the lipophorin receptors is not required to mediate the uptake of neutral lipids. These findings suggest a model where lipophorin receptors promote the extracellular lipolysis of lipophorins. This model is reminiscent of the lipolytic processing of triglyceride-rich lipoproteins that occurs at the mammalian capillary endothelium, suggesting an ancient role for LDLR–like proteins in this process. PMID:21347279

  15. [Interventional mitral valve replacement. Current status].

    PubMed

    Lutter, G; Frank, D

    2016-02-01

    Approximately 30 % of patients suffering from severe valvular heart disease, such as mitral valve regurgitation are non-compliant to the gold standard of minimally invasive surgery, reconstruction or valve replacement. The number of these mostly old patients with severe comorbidities is increasing; therefore, transcatheter interventions have been developed to address an unmet clinical need and may be an alternative therapeutic option to the reference standard. Apart from the successful MitraClip therapy, alternative transcatheter reconstruction technologies are being developed. As with transcatheter aortic valve implantation (TAVI) procedures, the off-pump implantation of a valved stent into the mitral position mainly via a transapical approach will be of great benefit. Recently, the feasibility of transcatheter mitral valved stent implantation in high-risk patients has already been reported.

  16. Acute mitral regurgitation in Takotsubo cardiomyopathy.

    PubMed

    Bouabdallaoui, Nadia; Wang, Zhen; Lecomte, Milena; Ennezat, Pierre V; Blanchard, Didier

    2015-04-01

    Takotsubo cardiomyopathy (TTC) is a well-recognised entity that commonly manifests with chest pain, ST segment abnormalities and transient left ventricular apical ballooning without coronary artery obstructive disease. This syndrome usually portends a favourable outcome. In the rare haemodynamically unstable TTC patients, acute mitral regurgitation (MR) related to systolic anterior motion (SAM) of the mitral valve and left ventricular outflow tract obstruction (LVOTO) is to be considered. Bedside echocardiography is key in recognition of this latter condition as vasodilators, inotropic agents or intra-aortic balloon counter-pulsation worsen the patient's clinical status. We discuss here a case of TTC where nitrate-induced subaortic obstruction and mitral regurgitation led to haemodynamic instability.

  17. Transcatheter mitral valve implantation: a brief review.

    PubMed

    Mylotte, Darren; Piazza, Nicolo

    2015-09-01

    In the last year transcatheter mitral valve implantation (TMVI) has seen a major jump in development. This technique offers the potential to treat a great number of elderly and/or high-risk patients with severe mitral regurgitation (MR). Such patients are declined surgical intervention either because the institutional Heart Team considers the risk of intervention to exceed the potential benefit, or because the patients and their families believe the morbidity of mitral surgery to be excessive. The advent of a less invasive transcatheter treatment could, therefore, potentially appeal to both clinicians and patients alike. In this overview paper, we describe briefly these recent developments in TVMI technologies as an introduction to the dedicated TVMI technical device parade later in this supplement.

  18. Use of three-dimensional transesophageal echocardiography to evaluate mitral valve morphology for risk stratification prior to mitral valvuloplasty.

    PubMed

    Francis, Loren; Finley, Alan; Hessami, Walead

    2017-02-01

    Mitral stenosis is often managed percutaneously with an interventional procedure such as balloon commissurotomy. Although this often results in an increased mitral valve area and improved clinical symptoms, this procedure is not benign and may have serious complications including the development of hemodynamically significant mitral valve regurgitation. Multiple scoring systems have been developed to attempt to risk stratify these patients prior to their procedure.

  19. Transcatheter implantation of the MONARC coronary sinus device for mitral regurgitation: 1-year results from the EVOLUTION phase I study (Clinical Evaluation of the Edwards Lifesciences Percutaneous Mitral Annuloplasty System for the Treatment of Mitral Regurgitation).

    PubMed

    Harnek, Jan; Webb, John G; Kuck, Karl-Heinz; Tschope, Carsten; Vahanian, Alec; Buller, Christopher E; James, Stefan K; Tiefenbacher, Christiane P; Stone, Gregg W

    2011-01-01

    This study sought to assess the safety and efficacy of transcatheter valve annuloplasty in patients with mitral regurgitation (MR). Mitral regurgitation is associated with a worsened prognosis in patients with dilated cardiomyopathy. Surgical mitral annuloplasty reduces the septal-lateral dimension of the mitral annulus resulting in improved leaflet coaptation with a reduction in regurgitation. Percutaneous annuloplasty with the MONARC device (Edwards Lifesciences, Irvine, California) implanted within the coronary sinus is designed to reduce mitral regurgitation through a similar mechanism. A total of 72 patients with MR grade ≥ 2 were enrolled at 8 participating centers in 4 countries. Clinical evaluation and transthoracic echocardiography were performed at baseline and at 3, 6, and 12 months. Multislice cardiac computed tomography and coronary angiography were performed at baseline and 3 months. The MONARC device was implanted in 59 of 72 patients (82%). The primary safety end point (freedom from death, tamponade, or myocardial infarction at 30 days) was met in 91% of patients at 30 days and in 82% at 1 year. Computed tomography imaging documented passage of the great cardiac vein over an obtuse marginal artery in 55% of patients and was associated with angiographic coronary artery compression in 15 patients and myocardial infarction in 2 patients (3.4%). At 12 months, a reduction in MR by ≥ 1 grade was observed in 50.0% of 22 implanted patients with matched echocardiograms and in 85.7% of 7 patients with baseline MR grade ≥ 3. Implantation of the MONARC device in the coronary sinus is feasible and may reduce MR. However, coronary artery compression may occur in patients in whom the great cardiac vein passes over a coronary artery, necessitating strategies in future studies to avoid this occurrence. Copyright © 2011 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  20. Mechanical and Thermal Sensory Testing in Normal Chondrodystrophoid Dogs and Dogs with Spinal Cord Injury caused by Thoracolumbar Intervertebral Disc Herniations.

    PubMed

    Gorney, A M; Blau, S R; Dohse, C S; Griffith, E H; Williams, K D; Lim, J-H; Knazovicky, D; Lascelles, B D X; Olby, N J

    2016-01-01

    Intervertebral disc herniation is a common cause of spinal cord injury (SCI) causing paralysis and sensory loss. Little quantitative information is available on the loss and recovery of sensation in dogs with SCI. To determine whether quantitative sensory testing (QST) can be used to establish thermal and mechanical sensory thresholds in chrondrodystrophoid dogs and compare thresholds among normal dogs and dogs with different grades of SCI. Thirty-three client-owned chondrodystrophoid dogs: 15 normal and 18 SCI dogs. Thermal testing was performed by placing a hot (49°C) and cold (5°C) probe on the dorsal metatarsus and mechanical thresholds were tested using calibrated forceps to apply force to the lateral digit. Stimuli were applied until acknowledged, and response rate, latency, and force applied to response were recorded. Test-retest repeatability was determined by calculating intraclass correlation coefficients. Response rates were compared using logistic regression and thresholds were compared using Kaplan-Meier Survival curves. Testing was feasible with moderate repeatability. Thresholds and response rates were significantly different between normal and SCI dogs for all modalities (P < .001). When dogs were grouped by their clinical grade, each grade was significantly different from normal dogs, and cold stimuli differentiated among all grades. Sensory thresholds can be measured reliably in chondrodystrophoid dogs and are altered by SCI. The differences in sensation among neurologic grades indicate that these techniques can be used to further characterize recovery of SCI dogs. Copyright © 2016 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.

  1. Mitral valve repair over five decades

    PubMed Central

    2015-01-01

    It has become evident that mitral valve (MV) repair is the preferable treatment for the majority of patients presenting with severe mitral regurgitation (MR). This success clearly testifies that the surgical procedure is accessible, reproducible and is carrying excellent long-lasting results. From the pre-extracorporeal circulation’s era to the last percutaneous approaches, a large variety of techniques have been proposed to address the different features of MV diseases. This article aimed at reviewing chronologically the development of these dedicated techniques through their origins and the debates that they generated in the literature. PMID:26309841

  2. Severe mitral regurgitation due to an extraordinary heart defect.

    PubMed

    García-Ropero, Álvaro; Cortés García, Marcelino; Aldamiz Echevarría, Gonzalo; Farré Muncharaz, Jerónimo

    2016-09-01

    A previously non-described cause of mitral regurgitation is presented. An asymptomatic 50-year old male who was casually diagnosed of mitral valve Barlow's disease underwent cardiac surgery due to severe mitral regurgitation. In the operating theatre, a longitudinal fissure of 1.5-2.0 cm length, along the posterior mitral leaflet, was found responsible for the insufficiency. This defect had features of a potential congenital origin and it was successfully repaired with direct suture. Whether it is an atypical mitral cleft, a variation of Barlow's morphology spectrum or a new congenital heart defect remains unclear.

  3. Changes in Mitral Annular Geometry after Aortic Valve Replacement: A Three-Dimensional Transesophageal Echocardiographic Study

    PubMed Central

    Mahmood, Feroze; Warraich, Haider J.; Gorman, Joseph H.; Gorman, Robert C.; Chen, Tzong-Huei; Panzica, Peter; Maslow, Andrew; Khabbaz, Kamal

    2014-01-01

    Background and aim of the study Intraoperative real-time three-dimensional transesophageal echocardiography (RT-3D TEE) was used to examine the geometric changes that occur in the mitral annulus immediately after aortic valve replacement (AVR). Methods A total of 35 patients undergoing elective surgical AVR under cardiopulmonary bypass was enrolled in the study. Intraoperative RT-3D TEE was used prospectively to acquire volumetric echocardiographic datasets immediately before and after AVR. The 3D echocardiographic data were analyzed offline using TomTec® Mitral Valve Assessment software to assess changes in specific mitral annular geometric parameters. Results Datasets were successfully acquired and analyzed for all patients. A significant reduction was noted in the mitral annular area (-16.3%, p <0.001), circumference (-8.9% p <0.001) and the anteroposterior (-6.3%, p = 0.019) and anterolateral-posteromedial (-10.5%, p <0.001) diameters. A greater reduction was noted in the anterior annulus length compared to the posterior annulus length (10.5% versus 62%, p <0.05) after AVR. No significant change was seen in the non-planarity angle, coaptation depth, and closure line length. During the period of data acquisition before and after AVR, no significant change was noted in the central venous pressure or left ventricular end-diastolic diameter. Conclusion The mitral annulus undergoes significant geometric changes immediately after AVR Notably, a 16.3% reduction was observed in the mitral annular area. The anterior annulus underwent a greater reduction in length compared to the posterior annulus, which suggested the existence of a mechanical compression by the prosthetic valve. PMID:23409347

  4. Additional value of biplane transoesophageal imaging in assessment of mitral valve prostheses.

    PubMed Central

    Groundstroem, K; Rittoo, D; Hoffman, P; Bloomfield, P; Sutherland, G R

    1993-01-01

    OBJECTIVES--To determine whether biplane transoesophageal imaging offers advantages in the evaluation of mitral prostheses when compared with standard single transverse plane imaging or the precordial approach in suspected prosthetic dysfunction. DESIGN--Prospective mitral valve prosthesis in situ using precordial and biplane transoesophageal ultrasonography. SETTING--Tertiary cardiac referral centre. SUBJECTS--67 consecutive patients with suspected dysfunction of a mitral valve prosthesis (16 had bioprostheses and 51 mechanical prostheses) who underwent precordial, transverse plane, and biplane transoesophageal echocardiography. Correlative invasive confirmation from surgery or angiography, or both, was available in 44 patients. MAIN OUTCOME MEASURES--Number, type, and site of leak according to the three means of scanning. RESULTS--Transverse plane transoesophageal imaging alone identified all 31 medial/lateral paravalvar leaks but only 24/30 of the anterior/posterior leaks. Combining the information from both imaging planes confirmed that biplane scanning identified all paravalvar leaks. Five of the six patients with prosthetic valve endocarditis, all three with valvar thrombus or obstruction, and all three with mitral annulus rupture were diagnosed from transverse plane imaging alone. Longitudinal plane imaging alone enabled diagnosis of the remaining case of prosthetic endocarditis and a further case of subvalvar pannus formation. CONCLUSIONS--Transverse plane transoesophageal imaging was superior to the longitudinal imaging in identifying medial and lateral lesions around the sewing ring of a mitral valve prosthesis. Longitudinal plane imaging was superior in identifying anterior and posterior lesions. Biplane imaging is therefore an important development in the study of mitral prosthesis function. Images PMID:8398497

  5. Early postpartum mitral valve thrombosis requiring extra corporeal membrane oxygenation before successful valve replacement.

    PubMed

    Halldorsdottir, H; Nordström, J; Brattström, O; Sennström, M M; Sartipy, U; Mattsson, E

    2016-05-01

    Pregnancy is associated with an increased risk of thrombosis in women with mechanical prosthetic heart valves. We present the case of a 29-year-old woman who developed early postpartum mitral valve thrombus after an elective cesarean delivery. The patient had a mechanical mitral valve and was treated with warfarin in the second trimester, which was replaced with high-dose dalteparin during late pregnancy. Elective cesarean delivery was performed under general anesthesia at 37weeks of gestation. The patient was admitted to the intensive care unit for postoperative care and within 30min she developed dyspnea and hypoxia requiring mechanical ventilation. She deteriorated rapidly and developed pulmonary edema, worsening hypoxia and severe acidosis. Urgent extra corporeal membrane oxygenation was initiated. Transesophageal echocardiography revealed a mitral valve thrombus. The patient underwent a successful mitral valve replacement after three days on extra corporeal membrane oxygenation. This case highlights the importance of multidisciplinary care and frequent monitoring of anticoagulation during care of pregnant women with prosthetic heart valves.

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

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

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

  7. [Relationship between mitral valve prolapse and arrhythmogenic right ventricular disease].

    PubMed

    Costa, A M; Maia, I G; Cruz Filho, F; Fagundes, M L; Sá, R; Alves, P

    1996-12-01

    To evaluate some features of ventricular arrhythmias in patients with mitral valve prolapse. We studied 25 patients (female: 19; mean age: 37 +/- 13 years) with ventricular arrhythmias, mitral valve prolapse and normal ventricular function. All patients underwent a 24h Holter and high resolution ECG (HRECG). The Qtc intervals were measured in lead II (normal < 0.44 s). In order to define the possible origin of the ventricular focus, the morphology of the ectopic beats were analysed in leads I, II, aVF, V1 using the following criteria: 1) LBBB morphology with left axis deviation in the frontal plane (FP): origin at the inflow tract of the right ventricle (RV); 2) LBBB morphology with right axis deviation in the FP: origin at the outflow tract of the RV; 3) RBBB morphology with left axis deviation in the FP: origin at the posterior region of the left ventricle (LV). RBBB morphology with right axis deviation in the FP: origin at the anterior region of the LV. Twenty three (92%) patients showed > 720 isolated ventricular ectopic beats/24 h. Paired ventricular response was detected in 18 (72%) patients and non-sustained VT in 15 (60%). HRECG was positive in six (24%) patients and Qtc interval was prolonged in 13 (52%). RV was the site of origin of the ventricular ectopic beats in 85% of the patients (outflow: 85%; inflow: 15%). Only five (20%) patients had arrhythmias from the LV. There was a high incidence of ventricular arrhythmias with a low incidence of positive HRECG tests, suggesting that the mechanisms of the arrhythmias do not correlate with slow intramyocardial conduction. It was noted a strong association between mitral valve prolapse, arrhythmogenic right ventricular disease and Qtc prolongation. It is possible that in some of this patients the finding could represent a global myocardial disease.

  8. Myocardial Infarction Alters Adaptation of the Tethered Mitral Valve

    PubMed Central

    Dal-Bianco, Jacob P.; Aikawa, Elena; Bischoff, Joyce; Guerrero, J. Luis; Hjortnaes, Jesper; Beaudoin, Jonathan; Szymanski, Catherine; Bartko, Philipp E.; Seybolt, Margo M.; Handschumacher, Mark D.; Sullivan, Suzanne; Garcia, Michael L.; Mauskapf, Adam; Titus, James S.; Wylie-Sears, Jill; Irvin, Whitney S.; Chaput, Miguel; Messas, Emmanuel; Hagège, Albert A.; Carpentier, Alain; Levine, Robert A.

    2016-01-01

    BACKGROUND In patients with myocardial infarction (MI), leaflet tethering by displaced papillary muscles induces mitral regurgitation (MR), which doubles mortality. Mitral valves (MVs) are larger in such patients but fibrosis sets in counterproductively. The investigators previously reported that experimental tethering alone increases mitral valve area in association with endothelial-to-mesenchymal transition. OBJECTIVES This study explored the clinically relevant situation of tethering and MI, testing the hypothesis that ischemic milieu modifies MV adaptation. METHODS Twenty-three adult sheep were examined. Under cardiopulmonary bypass, the PM tips in 6 sheep were retracted apically to replicate tethering, short of producing MR (tethered-alone). PM retraction was combined with apical MI created by coronary ligation in another 6 sheep (tethered + MI), and left ventricular (LV) remodeling was limited by external constraint in 5 additional sheep (LV constraint). Six sham-operated sheep were controls. Diastolic MV surface area was quantified by 3-dimensional echocardiography at baseline and after 58 ± 5 days, followed by histopathology and flow cytometry of excised leaflets. RESULTS Tethered + MI leaflets were markedly thicker than tethered-alone valves and sham controls. Leaflet area also increased significantly. EMT, detected as α-smooth muscle actin-positive endothelial cells, significantly exceeded that in tethered-alone and control valves. Transforming growth factor-β, matrix metalloproteinase expression, and cellular proliferation were markedly increased. Uniquely, tethering + MI showed endothelial activation with vascular adhesion molecule expression, neovascularization, and cells positive for CD45, considered a hematopoietic cell marker. Tethered + MI findings were comparable with external ventricular constraint. CONCLUSIONS MI altered leaflet adaptation, including a profibrotic increase in valvular cell activation, CD45-positive cells, and matrix turnover

  9. Cell transplantation in lumbar spine disc degeneration disease.

    PubMed

    Hohaus, C; Ganey, T M; Minkus, Y; Meisel, H J

    2008-12-01

    Low back pain is an extremely common symptom, affecting nearly three-quarters of the population sometime in their life. Given that disc herniation is thought to be an extension of progressive disc degeneration that attends the normal aging process, seeking an effective therapy that staves off disc degeneration has been considered a logical attempt to reduce back pain. The most apparent cellular and biochemical changes attributable to degeneration include a decrease in cell density in the disc that is accompanied by a reduction in synthesis of cartilage-specific extracellular matrix components. With this in mind, one therapeutic strategy would be to replace, regenerate, or augment the intervertebral disc cell population, with a goal of correcting matrix insufficiencies and restoring normal segment biomechanics. Biological restoration through the use of autologous disc chondrocyte transplantation offers a potential to achieve functional integration of disc metabolism and mechanics. We designed an animal study using the dog as our model to investigate this hypothesis by transplantation of autologous disc-derived chondrocytes into degenerated intervertebral discs. As a result we demonstrated that disc cells remained viable after transplantation; transplanted disc cells produced an extracellular matrix that contained components similar to normal intervertebral disc tissue; a statistically significant correlation between transplanting cells and retention of disc height could displayed. Following these results the Euro Disc Randomized Trial was initiated to embrace a representative patient group with persistent symptoms that had not responded to conservative treatment where an indication for surgical treatment was given. In the interim analyses we evaluated that patients who received autologous disc cell transplantation had greater pain reduction at 2 years compared with patients who did not receive cells following their discectomy surgery and discs in patients that

  10. Successful surgical repair of the parachute mitral valve with mitral valve regurgitation.

    PubMed

    Shiraishi, Manabu; Yamaguchi, Atsushi; Adachi, Hideo

    2012-01-01

    A 65-year-old woman with exercise-related dyspnea was admitted to our hospital. Transthoracic echocardiography demonstrated a large anomalous papillary muscle that originated from the posterior wall of the left ventricle and severe mitral valve regurgitation in systole. Cleft suture, 5-0 polytetrafluoroethylene sutures from a single papillary muscle to the anterior commissure leaflet (AC), 5-0 polypropylene sutures between AC and A1, and between A1 and A2, the double-orifice technique, and ring plasty with 32-mm semi-rigid ring was performed. Postoperative echocardiography showed an improvement in severe mitral valve regurgitation. At the 2-month follow-up, the patient was in good health. In the present case, the elderly patient with an isolated parachute mitral valve but without any other cardiac anomaly and presenting with mitral valve regurgitation is extremely rare. This case of mitral valvuloplasty for a parachute mitral valve with a single papillary muscle in an elderly woman has not been reported before.

  11. 3D Printed Modeling of the Mitral Valve for Catheter-Based Structural Interventions.

    PubMed

    Vukicevic, Marija; Puperi, Daniel S; Jane Grande-Allen, K; Little, Stephen H

    2017-02-01

    As catheter-based structural heart interventions become increasingly complex, the ability to effectively model patient-specific valve geometry as well as the potential interaction of an implanted device within that geometry will become increasingly important. Our aim with this investigation was to combine the technologies of high-spatial resolution cardiac imaging, image processing software, and fused multi-material 3D printing, to demonstrate that patient-specific models of the mitral valve apparatus could be created to facilitate functional evaluation of novel trans-catheter mitral valve repair strategies. Clinical 3D transesophageal echocardiography and computed tomography images were acquired for three patients being evaluated for a catheter-based mitral valve repair. Target anatomies were identified, segmented and reconstructed into 3D patient-specific digital models. For each patient, the mitral valve apparatus was digitally reconstructed from a single or fused imaging data set. Using multi-material 3D printing methods, patient-specific anatomic replicas of the mitral valve were created. 3D print materials were selected based on the mechanical testing of elastomeric TangoPlus materials (Stratasys, Eden Prairie, Minnesota, USA) and were compared to freshly harvested porcine leaflet tissue. The effective bending modulus of healthy porcine MV tissue was significantly less than the bending modulus of TangoPlus (p < 0.01). All TangoPlus varieties were less stiff than the maximum tensile elastic modulus of mitral valve tissue (3697.2 ± 385.8 kPa anterior leaflet; 2582.1 ± 374.2 kPa posterior leaflet) (p < 0.01). However, the slopes of the stress-strain toe regions of the mitral valve tissues (532.8 ± 281.9 kPa anterior leaflet; 389.0 ± 156.9 kPa posterior leaflet) were not different than those of the Shore 27, Shore 35, and Shore 27 with Shore 35 blend TangoPlus material (p > 0.95). We have demonstrated that patient-specific mitral valve models can be

  12. Non-rheumatic `subvalvar' mitral regurgitation

    PubMed Central

    Caves, P. K.; Paneth, M.

    1973-01-01

    Thirty-seven patients with non-rheumatic subvalvar mitral regurgitation are reported, representing 16% of all patients with mitral regurgitation submitted to open operation over a five-and-a-half-year period. In 22 older patients with `idiopathic' chordal lesions, the commonest finding was rupture of chordae to the posterior leaflet. The aortic leaflet chordae were most frequently involved following myocardial infarction (7 patients) or bacterial endocarditis (3 patients). Three other younger patients had ruptured chordae and two patients had rupture of the posteromedial papillary muscle following acute myocardial infarction. The mitral valve was repaired in 16 patients with ruptured chordae, of whom only eight obtained a satisfactory late result. In the other 21 patients the valve was replaced with a mounted aortic homograft or a Starr-Edwards prosthesis. It is concluded that mitral valve repair should be reserved for patients with symmetrical rupture of the chordae controlling the centre of the posterior leaflet, as regurgitation may reappear after other forms of repair due to progressive rupture of other abnormal chordae or breakdown of the repair. The early and late mortality in the patients with a definite antecedent myocardial infarction was much higher than in the other groups, and emergency valve replacement soon after rupture of the papillary muscle was unsuccessful in both patients. Images PMID:4731107

  13. Minimally Invasive Mitral Valve Surgery III

    PubMed Central

    Lehr, Eric J.; Guy, T. Sloane; Smith, Robert L.; Grossi, Eugene A.; Shemin, Richard J.; Rodriguez, Evelio; Ailawadi, Gorav; Agnihotri, Arvind K.; Fayers, Trevor M.; Hargrove, W. Clark; Hummel, Brian W.; Khan, Junaid H.; Malaisrie, S. Chris; Mehall, John R.; Murphy, Douglas A.; Ryan, William H.; Salemi, Arash; Segurola, Romualdo J.; Smith, J. Michael; Wolfe, J. Alan; Weldner, Paul W.; Barnhart, Glenn R.; Goldman, Scott M.; Lewis, Clifton T. P.

    2016-01-01

    Abstract Minimally invasive mitral valve operations are increasingly common in the United States, but robotic-assisted approaches have not been widely adopted for a variety of reasons. This expert opinion reviews the state of the art and defines best practices, training, and techniques for developing a successful robotics program. PMID:27662478

  14. Mitral Valve Prolapse in Young Patients.

    ERIC Educational Resources Information Center

    McFaul, Richard C.

    1987-01-01

    A review of research regarding mitral valve prolapse in young children indicates that up to five percent of this population have the condition, with the majority being asymptomatic and requiring reassurance that the condition usually remains mild. Beta-blocking drugs are prescribed for patients with disabling chest pain, dizziness, palpitation, or…

  15. [Mitral valve prolapse and cusp elasticity].

    PubMed

    Curti, H J; Ferreira, M C; Silveira, S A; Sanches, P C; Carvalhal, S

    1994-06-01

    To verify if systolic bulging of floppy mitral cusps can to elastic behavior of their myxomatous collagen tissue. Five hearts with floppy mitral valves obtained from autopsies were distended with air (20 to 250 mmHg) through a catheter connected to the left ventricle. It was observed if some area of the atrial surface of the coapted cusps showed variable bulging according to the variation of air injection pressures. Molding of those surfaces (gypsum) allowed the same kind of analysis by other four researches. It was analyzed the cut surfaces of these radially sectioned molds. Lately, isolated tendinae chords were submitted to repeated tractions and observed if they exhibited elastic behavior. Histological study defined the presence of collagen myxomatous degeneration and quantified the amount of elastic tissue. In no case it was detected elastic bulding of mitral cusps. Cut surfaces of the molds confirmed that no increment of the prominent areas occurred, even in those regions with extensive, histologically confirmed, myxomatous substitution of the native collagen tissue. Increment of the degree of mitral bulging occurring during ventricular systole can not be ascertained to cusp elasticity but probably to papilar muscle traction.

  16. Differential MicroRNA Expression Profile in Myxomatous Mitral Valve Prolapse and Fibroelastic Deficiency Valves

    PubMed Central

    Chen, Yei-Tsung; Wang, Juan; Wee, Abby S. Y.; Yong, Quek-Wei; Tay, Edgar Lik-Wui; Woo, Chin Cheng; Sorokin, Vitaly; Richards, Arthur Mark; Ling, Lieng-Hsi

    2016-01-01

    Myxomatous mitral valve prolapse (MMVP) and fibroelastic deficiency (FED) are two common variants of degenerative mitral valve disease (DMVD), which is a leading cause of mitral regurgitation worldwide. While pathohistological studies have revealed differences in extracellular matrix content in MMVP and FED, the molecular mechanisms underlying these two disease entities remain to be elucidated. By using surgically removed valvular specimens from MMVP and FED patients that were categorized on the basis of echocardiographic, clinical and operative findings, a cluster of microRNAs that expressed differentially were identified. The expressions of has-miR-500, -3174, -17, -1193, -646, -1273e, -4298, -203, -505, and -939 showed significant differences between MMVP and FED after applying Bonferroni correction (p < 0.002174). The possible involvement of microRNAs in the pathogenesis of DMVD were further suggested by the presences of in silico predicted target sites on a number of genes reported to be involved in extracellular matrix homeostasis and marker genes for cellular composition of mitral valves, including decorin (DCN), aggrecan (ACAN), fibromodulin (FMOD), α actin 2 (ACTA2), extracellular matrix protein 2 (ECM2), desmin (DES), endothelial cell specific molecule 1 (ESM1), and platelet/ endothelial cell adhesion molecule 1 (PECAM1), as well as inverse correlations of selected microRNA and mRNA expression in MMVP and FED groups. Our results provide evidence that distinct molecular mechanisms underlie MMVP and FED. Moreover, the microRNAs identified may be targets for the future development of diagnostic biomarkers and therapeutics. PMID:27213335

  17. Differential MicroRNA Expression Profile in Myxomatous Mitral Valve Prolapse and Fibroelastic Deficiency Valves.

    PubMed

    Chen, Yei-Tsung; Wang, Juan; Wee, Abby S Y; Yong, Quek-Wei; Tay, Edgar Lik-Wui; Woo, Chin Cheng; Sorokin, Vitaly; Richards, Arthur Mark; Ling, Lieng-Hsi

    2016-05-18

    Myxomatous mitral valve prolapse (MMVP) and fibroelastic deficiency (FED) are two common variants of degenerative mitral valve disease (DMVD), which is a leading cause of mitral regurgitation worldwide. While pathohistological studies have revealed differences in extracellular matrix content in MMVP and FED, the molecular mechanisms underlying these two disease entities remain to be elucidated. By using surgically removed valvular specimens from MMVP and FED patients that were categorized on the basis of echocardiographic, clinical and operative findings, a cluster of microRNAs that expressed differentially were identified. The expressions of has-miR-500, -3174, -17, -1193, -646, -1273e, -4298, -203, -505, and -939 showed significant differences between MMVP and FED after applying Bonferroni correction (p < 0.002174). The possible involvement of microRNAs in the pathogenesis of DMVD were further suggested by the presences of in silico predicted target sites on a number of genes reported to be involved in extracellular matrix homeostasis and marker genes for cellular composition of mitral valves, including decorin (DCN), aggrecan (ACAN), fibromodulin (FMOD), α actin 2 (ACTA2), extracellular matrix protein 2 (ECM2), desmin (DES), endothelial cell specific molecule 1 (ESM1), and platelet/ endothelial cell adhesion molecule 1 (PECAM1), as well as inverse correlations of selected microRNA and mRNA expression in MMVP and FED groups. Our results provide evidence that distinct molecular mechanisms underlie MMVP and FED. Moreover, the microRNAs identified may be targets for the future development of diagnostic biomarkers and therapeutics.

  18. Management of mitral regurgitation in Marfan syndrome: Outcomes of valve repair versus replacement and comparison with myxomatous mitral valve disease.

    PubMed

    Helder, Meghana R K; Schaff, Hartzell V; Dearani, Joseph A; Li, Zhuo; Stulak, John M; Suri, Rakesh M; Connolly, Heidi M

    2014-09-01

    The study objective was to evaluate patients with Marfan syndrome and mitral valve regurgitation undergoing valve repair or replacement and to compare them with patients undergoing repair for myxomatous mitral valve disease. We reviewed the medical records of consecutive patients with Marfan syndrome treated surgically between March 17, 1960, and September 12, 2011, for mitral regurgitation and performed a subanalysis of those with repairs compared with case-matched patients with myxomatous mitral valve disease who had repairs (March 14, 1995, to July 5, 2013). Of 61 consecutive patients, 40 underwent mitral repair and 21 underwent mitral replacement (mean [standard deviation] age, 40 [18] vs 31 [19] years; P = .09). Concomitant aortic surgery was performed to a similar extent (repair, 45% [18/40] vs replacement, 43% [9/21]; P = .87). Ten-year survival was significantly better in patients with Marfan syndrome with mitral repair than in those with replacement (80% vs 41%; P = .01). Mitral reintervention did not differ between mitral repair and replacement (cumulative risk of reoperation, 27% vs 15%; P = .64). In the matched cohort, 10-year survival after repair was similar for patients with Marfan syndrome and myxomatous mitral disease (84% vs 78%; P = .63), as was cumulative risk of reoperation (17% vs 12%; P = .61). Patients with Marfan syndrome and mitral regurgitation have better survival with repair than with replacement. Survival and risk of reoperation for patients with Marfan syndrome were similar to those for patients with myxomatous mitral disease. These results support the use of mitral valve repair in patients with Marfan syndrome and moderate or more mitral regurgitation, including those having composite replacement of the aortic root. Copyright © 2014 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

  19. [Late ventricular potentials and mitral valve prolapse].

    PubMed

    Babuty, D; Charniot, J C; Delhomme, C; Fauchier, L; Fauchier, J P; Cosnay, P

    1994-03-01

    In order to determine the predictive value for ventricular arrhythmias of ventricular late potentials (LP) in mitral valve prolapse (MVP) the authors performed high amplification signal-averaging ECG (SA) and 24 hours ambulatory ECG (Holter) monitoring in 68 consecutive patients (34 men, 34 women, average age 48 +/- 17.7 years) with echocardiographically diagnosed MVP. Patients with bundle branch block or associated cardiac disease were excluded. Echocardiography showed 26 patients to have floppy mitral valves (38.2%), 50 patients to have posterior deplacement > or = 5 mm of the mitral valves in systole (73.5%) and 35 patients to have mitral regurgitation (51.4%). Holter monitoring showed 17 patients without ventricular extrasystoles (VES), 15 had Lown Grade I, 6 had Lown Grade II, 3 had Lown Grade III, 15 had Lown Grade IV A and 12 had Lown Grade IV B ventricular arrhythmias. Therefore, 30 patients had complex ventricular arrhythmias (> or = Lown Grade III) and 13 patients had spontaneous non-sustained ventricular tachycardia (NSVT) (one patient had NSVT on resting ECG but not on Holter monitoring). Eighteen patients had LP (26.5%). The incidence of complex ventricular arrhythmias was higher in patients with mitral regurgitation (62.8% versus 27.7%; p < 0.005) whereas the incidence of NSVT was not significantly different (25.7% versus 17.1%; p = 0.15). On the other hand, the frequency of complex ventricular arrhythmias was not significantly different in the presence or absence of LP (61.1% versus 40%: NS) whereas the incidence of NSVT was higher in patients with LP (44.4% versus 10%; p < 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

  20. Dipper discs not inclined towards edge-on orbits

    NASA Astrophysics Data System (ADS)

    Ansdell, M.; Gaidos, E.; Williams, J. P.; Kennedy, G.; Wyatt, M. C.; LaCourse, D. M.; Jacobs, T. L.; Mann, A. W.

    2016-10-01

    The so-called dipper stars host circumstellar discs and have optical and infrared light curves that exhibit quasi-periodic or aperiodic dimming events consistent with extinction by transiting dusty structures orbiting in the inner disc. Most of the proposed mechanisms explaining the dips - i.e. occulting disc warps, vortices, and forming planetesimals - assume nearly edge-on viewing geometries. However, our analysis of the three known dippers with publicly available resolved sub-mm data reveals discs with a range of inclinations, most notably the face-on transition disc J1604-2130 (EPIC 204638512). This suggests that nearly edge-on viewing geometries are not a defining characteristic of the dippers and that additional models should be explored. If confirmed by further observations of more dippers, this would point to inner disc processes that regularly produce dusty structures far above the outer disc mid-plane in regions relevant to planet formation.

  1. [Experience of Mitral Valve Replacement Using a Pulmonary Autograft (Ross II Operation) in an Infant;Report of a Case].

    PubMed

    Kawahito, Tomohisa; Egawa, Yoshiyasu; Yoshida, Homare; Shimoe, Yasushi; Onishi, Tatsuya; Miyagi, Yuhichi; Terada, Kazuya; Ohta, Akira

    2015-07-01

    A 24-day-old boy suddenly developed progressive heart failure and was transported to our hospital. Echocardiography showed massive mitral regurgitation due to chordal rupture. Mitral valve repair was performed at 28 days of life, but postoperative valvular function was not satisfactory. A mechanical valve was implanted in the supra-annular position at 37 days of life. Two months after valve replacement, the mechanical valve was suddenly stuck. Emergent redo valve replacement was performed, but the prosthetic valve became stuck again 2 months after the 3rd operation, despite sufficient anti-coagulation therapy. At the 4th operation (6 months after birth), we implanted a pulmonary autograft in the mitral position instead of another mechanical valve in an emergent operation. The right ventricular outflow tract was reconstructed with a valved conduit. A postoperative catheter examination, which was performed 1 year after the Ross II operation, showed mild mitral stenosis with no regurgitation. Previous reports of Ross II operations in infants are rare and long-term results are unknown. However, we advocate that this procedure should be a rescue operation for mitral valve dysfunction in the early period of infants.

  2. Echocardiography of congenital mitral valve disorders: echocardiographic-morphological comparisons.

    PubMed

    Silverman, Norman H

    2014-12-01

    I surveyed our echocardiographic database of the years between 1998 and 2012 for congenital abnormalities of the mitral valve in patients over 14 years. A total of 249 patients with mitral valve abnormalities were identified. Abnormalities included clefts in the mitral valve in 58 patients, double orifice of the mitral valve in 19, mitral stenosis with two papillary muscles in 72, and mitral stenosis with one papillary muscle in 51 patients. Supravalvar rings were found in 35 patients with a single papillary muscle, and mitral stenoses with two papillary muscles were found in 22 patients. Mitral prolapse occurred in 44 patients and mitral valvar straddle in five patients. The patients were evaluated by all modalities of ultrasound available over the course of time. Although some lesions were isolated, there were many lesions in which more than one mitral deformity presented in the same patient. The patients are presented showing anatomical correlation with autopsy specimens, some of which came from the patients in this series, and others matched to show correlative anatomy. These lesions remain rare as a group and continue to have high morbidity and mortality.

  3. Isolated Mitral Cleft in Trisomy 21: An Initially 'Silent' Lesion.

    PubMed

    Thankavel, Poonam P; Ramaciotti, Claudio

    2016-02-01

    Congenital cardiac anomalies are common in trisomy 21, and transthoracic echocardiogram within the first month of life is recommended. While a cleft mitral valve associated with atrioventricular septal defect has been well defined in this population, the prevalence of isolated mitral valve cleft has not been previously reported. The aim of our study was to define the occurrence of isolated mitral cleft in the first echocardiogram of patients with trisomy 21. This retrospective chart review examined echocardiographic data on all Trisomy 21 patients <1 year of age obtained during January 1, 2010, to May 1, 2014, at our institution. Images were reviewed by one of the authors with no knowledge of the official diagnosis. In addition to evaluation for isolated mitral valve cleft, data obtained included presence of additional congenital heart defects and need for surgical intervention. A total of 184 patients (median age 5 days) were identified. Isolated mitral cleft was identified in 12 patients (6.5 %). Four were diagnosed retrospectively (33 %). Only one had mitral regurgitation on initial echocardiogram. Seven required surgery for closure of ventricular septal defects. Isolated mitral cleft is present in an important number of neonates with Trisomy 21. Mitral regurgitation is often absent in the neonatal period and should not be used as a reliable indicator of absence of valve abnormality. Careful attention should be directed toward the mitral valve during the first echocardiogram to exclude an isolated cleft, which can lead to progressive mitral regurgitation.

  4. Mitral valve repair versus replacement in simultaneous aortic and mitral valve surgery

    PubMed Central

    Urban, Marian; Pirk, Jan; Szarszoi, Ondrej; Skalsky, Ivo; Maly, Jiri; Netuka, Ivan

    2013-01-01

    BACKGROUND: Double valve replacement for concomitant aortic and mitral valve disease is associated with substantial morbidity and mortality. Excellent results with valve repair in isolated mitral valve lesions have been reported; therefore, whether its potential benefits would translate into better outcomes in patients with combined mitral-aortic disease was investigated. METHODS: A retrospective observational study was performed involving 341 patients who underwent aortic valve replacement with either mitral valve repair (n=42) or double valve replacement (n=299). Data were analyzed for early mortality, late valve-related complications and survival. RESULTS: The early mortality rate was 11.9% for valve repair and 11.0% for replacement (P=0.797). Survival (± SD) was 67±11% in mitral valve repair with aortic valve replacement and 81±3% in double valve replacement at five years of follow-up (P=0.187). The percentage of patients who did not experience major adverse valve-related events at five years of follow-up was 83±9% in those who underwent mitral valve repair with aortic valve replacement and 89±2% in patients who underwent double valve replacement (P=0.412). Age >70 years (HR 2.4 [95% CI 1.1 to 4.9]; P=0.023) and renal dysfunction (HR 1.9 [95% CI 1.2 to 3.7]; P=0.01) were independent predictors of decreased survival. CONCLUSIONS: In patients with double valve disease, both mitral valve repair and replacement provided comparable early outcomes. There were no significant differences in valve-related reoperations, anticoagulation-related complications or prosthetic valve endocarditis. Patient-related factors appear to be the major determinant of late survival, irrespective of the type of operation. PMID:24294032

  5. Echocardiographic anatomy of the mitral valve in healthy dogs and dogs with myxomatous mitral valve disease.

    PubMed

    Wesselowski, S; Borgarelli, M; Menciotti, G; Abbott, J

    2015-06-01

    To further characterize the echocardiographic anatomy of the canine mitral valve apparatus in normal dogs and in dogs affected by myxomatous mitral valve disease (MMVD). Twenty-two normal dogs and 60 dogs with MMVD were prospectively studied. The length (AMVL), width (AMVW) and area (AMVA) of the anterior mitral valve leaflet were measured in the control group and the affected group, as were the diameters of the mitral valve annulus in diastole (MVAd) and systole (MVAs). The dogs with MMVD were staged based on American College of Veterinary Internal Medicine (ACVIM) guidelines and separated into groups B1 and B2/C. All measurements were indexed to body weight based on empirically defined allometric relationships. There was a statistically significant relationship between all log10 transformed mitral valve dimensions and body weight. The AMVL, AMVW, AMVA, MVAd and MVAs were all significantly greater in the B2/C group compared to the B1 and control groups. The AMVW was also significantly greater in the B1 group compared to the control group. Interobserver % coefficient of variation (% CV) was <10% for AMVL, AMVA, MVAd and MVAs, but was 29.6% for AMVW. Intraobserver % CV was <10.4% for all measurements. Measurements of the anterior mitral valve leaflet and the mitral valve annulus in the dog can be indexed to body weight based on allometric relationships. Preliminary reference intervals have been proposed over a range of body sizes. Relative to normal dogs, AMVL, AMVW, AMVA, MVAd and MVAs are greater in patients with advanced MMVD. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Cardiac pathology after valve replacement by disc prosthesis. A study of 61 necropsy patients.

    PubMed

    Roberts, W C; Fishbein, M C; Golden, A

    1975-05-01

    Clinical and necropsy observations are described in 61 patients who had one or more cardiac valves replaced with a discoid prosthesis of the Hufnagel type. The most common (31 percent) cause of death among the 45 patients who died early (less than 65 days after operation) appeared to be prosthetic disproportion; that is, the prothesis was too big for the aorta or ventricular cavity into which it was inserted so that inadequate space was present between the margins of the disc and the endocardium of ventricle or intima of aorta. Prosthetic thrombosis occurred in only 3 of the 45 patients who died early, but poppet movement appeared considerably altered in each. In contrast, thrombi were observed on a prosthesis in 14 of the 16 patients who died late (4 to 47 months [average 21] postoperatively), but in none did the thrombi appear of sufficient size to alter poppet function. Escessive bleeding occurred in 11 (24 percent) of the 45 early deaths and was primarily related to the insertion of a patch in the root of the aorta. Uncorrected valvular disease either by itself or by its ability to alter function of the prosthesis appeared responsible for death in 6 (13 percent) of the 45 patients who died early and in 2 (6 percent) of the 16 who died late. Insertion of a mitral poppet disc in a patient with uncorrected aortic regurgitation, even of mild degree, may be hazardous because the aortic regurgitant jet stream may interfere with proper function of the mitral disc. Likewise, insertion of a poppet disc only in the aortic valve position in a patient with combined aortic and mitral regurgitation may considerably increase the degree of mitral incompetence because the aortic prosthesis is intrinsically obstructive. Disc wear or variance was observed in all but one prosthesis in place for more than 1 year. Although hemolytic anemia of significant degree was not observed in any of the 16 patients who died late, the occurrence of renal hemosiderosis in 13 of the 16 patients

  7. Intradiscal pressure measurements in normal discs, compressed discs and compressed discs treated with axial posterior disc distraction: an experimental study on the rabbit lumbar spine model.

    PubMed

    Guehring, Thorsten; Unglaub, Frank; Lorenz, Helga; Omlor, Georg; Wilke, Hans-Joachim; Kroeber, Markus W

    2006-05-01

    Intervertebral disc (IVD) pressure measurement is an appropriate method for characterizing spinal loading conditions. However, there is no human or animal model that provides sufficient IVD pressure data. The aim of our study was to establish physiological pressure values in the rabbit lumbar spine and to determine whether temporary external disc compression and distraction were associated with pressure changes. Measurements were done using a microstructure-based fibreoptic sensor. Data were collected in five control rabbits (N, measurement lying prone at segment L3/4 at day 28), five rabbits with 28 days of axial compression (C, measurement at day 28) and three rabbits with 28 days of axial compression and following 28 days of axial distraction (D, measurement at day 56). Disc compression and distraction was verified by disc height in lateral radiographs. The controls (N) showed a level-related range between 0.25 MPa-0.45 MPa. The IVD pressure was highest at level L3/4 (0.42 MPa; range 0.38-0.45) with a decrease in both cranial and caudal adjacent segments. The result for C was a significant decrease in IVD pressure (0.31 MPa) when compared with controls (P=0.009). D showed slightly higher median IVD pressure (0.32 MPa) compared to C, but significantly lower levels when compared with N (P=0.037). Our results indicate a high range of physiological IVD pressure at different levels of the lumbar rabbit spine. Temporary disc compression reduces pressure when compared with controls. These data support the hypothesis that temporary external compression leads to moderate disc degeneration as a result of degradation of water-binding disc matrix or affected active pumping mechanisms of nutrients into the disc. A stabilization of IVD pressure in discs treated with temporary distraction was observed.

  8. Chemical separation of disc components using RAVE

    NASA Astrophysics Data System (ADS)

    Wojno, Jennifer; Kordopatis, Georges; Steinmetz, Matthias; McMillan, Paul; Matijevič, Gal; Binney, James; Wyse, Rosemary F. G.; Boeche, Corrado; Just, Andreas; Grebel, Eva K.; Siebert, Arnaud; Bienaymé, Olivier; Gibson, Brad K.; Zwitter, Tomaž; Bland-Hawthorn, Joss; Navarro, Julio F.; Parker, Quentin A.; Reid, Warren; Seabroke, George; Watson, Fred

    2016-10-01

    We present evidence from the RAdial Velocity Experiment (RAVE) survey of chemically separated, kinematically distinct disc components in the solar neighbourhood. We apply probabilistic chemical selection criteria to separate our sample into α-low (`thin disc') and α-high (`thick disc') sequences. Using newly derived distances, which will be utilized in the upcoming RAVE DR5, we explore the kinematic trends as a function of metallicity for each of the disc components. For our α-low disc, we find a negative trend in the mean rotational velocity (Vφ) as a function of iron abundance ([Fe/H]). We measure a positive gradient ∂Vφ/∂[Fe/H] for the α-high disc, consistent with results from high-resolution surveys. We also find differences between the α-low and α-high discs in all three components of velocity dispersion. We discuss the implications of an α-low, metal-rich population originating from the inner Galaxy, where the orbits of these stars have been significantly altered by radial mixing mechanisms in order to bring them into the solar neighbourhood. The probabilistic separation we propose can be extended to other data sets for which the accuracy in [α/Fe] is not sufficient to disentangle the chemical disc components a priori. For such data sets which will also have significant overlap with Gaia DR1, we can therefore make full use of the improved parallax and proper motion data as it becomes available to investigate kinematic trends in these chemical disc components.

  9. Biomechanical and biochemical outcomes of porcine temporomandibular joint disc deformation

    PubMed Central

    Matuska, Andrea M.; Muller, Stephen; Dolwick, M. Franklin; McFetridge, Peter S.

    2016-01-01

    Objective The structure-function relationship in the healthy temporomandibular joint (TMJ) disc has been well established, however the changes in dysfunctional joints has yet to be systematically evaluated. Due to the poor understanding of the etiology of temporomandibular disorders (TMDs) this study evaluated naturally occurring degenerative remodeling in aged female porcine temporomandibular joint (TMJ) discs in order to gain insight into the progression and effects on possible treatment strategies of TMDs. Design Surface and regional biomechanical and biochemical properties of discal tissues were determined in grossly deformed (≥ Wilkes Stage 3) and morphologically normal (≤ Wilkes Stage 2) TMJ discs. Results Compared to normal disc structure the deformed discs lacked a smooth biconcave shape and characteristic ECM organization. Reduction in tensile biomechanical integrity and increased compressive stiffness and cellularity was found in deformed discs. Regionally, the posterior and intermediate zones of the disc were most frequently affected along with the inferior surface. Conclusions The frequency of degeneration observed on the inferior surface of the disc (predominantly posterior), suggests that a disruption in the disc-condyle relationship likely contributes to the progression of joint dysfunction more than the temporodiscal relationship. As such, the inferior joint space may be an important consideration in early clinical diagnosis and treatment of TMDs, as it is overlooked in techniques performed in the upper joint space, including arthroscopy and arthrocentesis. Furthermore, permanent damage to the disc mechanical properties would limit the ability to successfully reposition deformed discs, highlighting the importance of emerging therapies such as tissue engineering. PMID:26774186

  10. Modeling and optimization of an elastic arthroplastic disc for a degenerated disc

    NASA Astrophysics Data System (ADS)

    Ghouchani, Azadeh; Ravari, Mohammad; Mahmoudi, Farid

    2011-10-01

    A three-dimensional finite element model (FEM) of the L3-L4 motion segment using ABAQUS v 6.9 has been developed. The model took into account the material nonlinearities and is imposed different loading conditions. In this study, we validated the model by comparison of its predictions with several sets of experimental data. Disc deformation under compression and segmental rotational motions under moment loads for the normal disc model agreed well with the corresponding in vivo studies. By linking ABAQUS with MATLAB 2010.a, we determined the optimal Young s modulus as well as the Poisson's ratio for the artificial disc under different physiologic loading conditions. The results of the present study confirmed that a well-designed elastic arthroplastic disc preferably has an annulus modulus of 19.1 MPa and 1.24 MPa for nucleus section and Poisson ratio of 0.41 and 0.47 respectively. Elastic artificial disc with such properties can then achieve the goal of restoring the disc height and mechanical function of intact disc under different loading conditions and so can reduce low back pain which is mostly caused due to disc degeneration.

  11. Mitral annulus morphologic and functional analysis using real time tridimensional echocardiography in patients submitted to unsupported mitral valve repair

    PubMed Central

    Guedes, Marco Antônio Vieira; Pomerantzeff, Pablo Maria Alberto; Brandão, Carlos Manuel de Almeida; Vieira, Marcelo Luiz Campos; Tarasoutchi, Flávio; Spinola, Pablo da Cunha; Jatene, Fábio Biscegli

    2015-01-01

    Introduction Mitral valve repair is the treatment of choice to correct mitral insufficiency, although the literature related to mitral valve annulus behavior after mitral repair without use of prosthetic rings is scarce. Objective To analyze mitral annulus morphology and function using real time tridimensional echocardiography in individuals submitted to mitral valve repair with Double Teflon technique. Methods Fourteen patients with mitral valve insufficiency secondary to mixomatous degeneration that were submitted to mitral valve repair with the Double Teflon technique were included. Thirteen patients were in FC III/IV. Patients were evaluated in preoperative period, immediate postoperative period, 6 months and 1 year after mitral repair. Statistical analysis was made by repeated measures ANOVA test and was considered statistically significant P<0.05. Results There were no deaths, reoperation due to valve dysfunction, thromboembolism or endocarditis during the study. Posterior mitral annulus demonstrated a significant reduction in immediate postoperative period (P<0.001), remaining stable during the study, and presents a mean of reduction of 25.8% comparing with preoperative period. There was a significant reduction in anteroposterior and mediolateral diameters in the immediate postoperative period (P<0.001), although there was a significant increase in mediolateral diameter between immediate postoperative period and 1 year. There was no difference in mitral internal area variation over the cardiac cycle during the study. Conclusion Segmentar annuloplasty reduced the posterior component of mitral annulus, which remained stable in a 1-year-period. The variation in mitral annulus area during cardiac cycle remained stable during the study. PMID:26313723

  12. Asymptotic Model of Fluid-Tissue Interaction for Mitral Valve Dynamics.

    PubMed

    Domenichini, Federico; Pedrizzetti, Gianni

    2015-06-01

    The vortex formation process inside the left ventricle is intrinsically connected to the dynamics of the mitral leaflets while they interact with the flow crossing the valve during diastole. The description of the dynamics of a natural mitral valve still represents a challenging issue, especially because its material properties are not measurable in vivo. Medical imaging can provide some indications about the geometry of the valve, but not about its mechanical properties. In this work, we introduce a parametric model of the mitral valve geometry, whose motion is described in the asymptotic limit under the assumption that it moves with the flow, without any additional resistance other than that given by its shape, and without the need to specify its material properties. The mitral valve model is coupled with a simple description of the left ventricle geometry, and their dynamics is solved numerically together with the equations ruling the blood flow. The intra-ventricular flow is analyzed in its relationship with the valvular motion. It is found that the initial valve opening anticipates the peak velocity of the Early filling wave with little influence of the specific geometry; while subsequent closure and re-opening are more dependent on the intraventricular vortex dynamics and thus on the leaflets' geometry itself. The limitations and potential applications of the proposed model are discussed.

  13. Infective endocarditis causing mitral valve stenosis - a rare but deadly complication: a case report.

    PubMed

    Hart, Michael A; Shroff, Gautam R

    2017-02-17

    Infective endocarditis rarely causes mitral valve stenosis. When present, it has the potential to cause severe hemodynamic decompensation and death. There are only 15 reported cases in the literature of mitral prosthetic valve bacterial endocarditis causing stenosis by obstruction. This case is even more unusual due to the mechanism by which functional mitral stenosis occurred. We report a case of a 23-year-old white woman with a history of intravenous drug abuse who presented with acute heart failure. Transthoracic echocardiography failed to show valvular vegetation, but high clinical suspicion led to transesophageal imaging that demonstrated infiltrative prosthetic valve endocarditis causing severe mitral stenosis. Despite extensive efforts from a multidisciplinary team, she died as a result of her critical illness. The discussion of this case highlights endocarditis physiology, the notable absence of stenosis in modified Duke criteria, and the utility of transesophageal echocardiography in clinching a diagnosis. It advances our knowledge of how endocarditis manifests, and serves as a valuable lesson for clinicians treating similar patients who present with stenosis but no regurgitation on transthoracic imaging, as a decision to forego a transesophageal echocardiography could cause this serious complication of endocarditis to be missed.

  14. TexMi: Development of Tissue-Engineered Textile-Reinforced Mitral Valve Prosthesis

    PubMed Central

    Moreira, Ricardo; Gesche, Valentine N.; Hurtado-Aguilar, Luis G.; Schmitz-Rode, Thomas; Frese, Julia

    2014-01-01

    Mitral valve regurgitation together with aortic stenosis is the most common valvular heart disease in Europe and North America. Mechanical and biological prostheses available for mitral valve replacement have significant limitations such as the need of a long-term anticoagulation therapy and failure by calcifications. Both types are unable to remodel, self-repair, and adapt to the changing hemodynamic conditions. Moreover, they are mostly designed for the aortic position and do not reproduce the native annular-ventricular continuity, resulting in suboptimal hemodynamics, limited durability, and gradually decreasing ventricular pumping efficiency. A tissue-engineered heart valve specifically designed for the mitral position has the potential to overcome the limitations of the commercially available substitutes. For this purpose, we developed the TexMi, a living textile-reinforced mitral valve, which recapitulates the key elements of the native one: annulus, asymmetric leaflets (anterior and posterior), and chordae tendineae to maintain the native annular-ventricular continuity. The tissue-engineered valve is based on a composite scaffold consisting of the fibrin gel as a cell carrier and a textile tubular structure with the twofold task of defining the gross three-dimensional (3D) geometry of the valve and conferring mechanical stability. The TexMi valves were molded with ovine umbilical vein cells and stimulated under dynamic conditions for 21 days in a custom-made bioreactor. Histological and immunohistological stainings showed remarkable tissue development with abundant aligned collagen fibers and elastin deposition. No cell-mediated tissue contraction occurred. This study presents the proof-of-principle for the realization of a tissue-engineered mitral valve with a simple and reliable injection molding process readily adaptable to the patient's anatomy and pathological situation by producing a patient-specific rapid prototyped mold. PMID:24665896

  15. Diffuse Alveolar Hemorrhage due to Acute Mitral Valve Regurgitation

    PubMed Central

    Marak, Creticus P.; Joy, Parijat S.; Gupta, Pragya; Guddati, Achuta K.

    2013-01-01

    Diffuse alveolar hemorrhage (DAH) can be caused by several etiologies including vasculitis, drug exposure, anticoagulants, infections, mitral valve stenosis, and regurgitation. Chronic mitral valve regurgitation (MR) has been well documented as an etiological factor for DAH, but there have been only a few cases which have reported acute mitral valve regurgitation as an etiology of DAH. Acute mitral valve regurgitation can be a life-threatening condition and often requires urgent intervention. In rare cases, acute mitral regurgitation may result in a regurgitant jet which is directed towards the right upper pulmonary vein and may specifically cause right-sided pulmonary edema and right-sided DAH. Surgical repair of the mitral valve results in rapid resolution of DAH. Acute MR should be considered as a possible etiology in patients presenting with unilateral pulmonary edema, hemoptysis, and DAH. PMID:24383034

  16. Mitral valve repair for ischemic mitral regurgitation: lessons from the Cardiothoracic Surgical Trials Network randomized study.

    PubMed

    Mihos, Christos G; Santana, Orlando

    2016-01-01

    Approximately 30% to 50% of patients will develop ischemic mitral regurgitation (MR) after a myocardial infarction, which is a result of progressive left ventricular remodeling and dysfunction of the subvalvular apparatus, and portends a poor long-term prognosis. Surgical treatment is centered on mitral valve repair utilizing a restrictive annuloplasty, or valve replacement with preservation of the subvalvular apparatus. In the recent Cardiothoracic Surgical Trials Network (CSTN) study, patients with severe ischemic MR were randomized to mitral valve repair with a restrictive annuloplasty versus chordal-sparing valve replacement, and concomitant coronary artery bypass grafting, if indicated. At 2-year follow-up, mitral valve repair was associated with a significantly higher incidence of moderate or greater recurrent MR and heart failure, with no difference in the indices of left ventricular reverse remodeling, as compared with valve replacement. The current appraisal aims to provide insight into the CSTN trial results, and discusses the evidence supporting a pathophysiologic-guided repair strategy incorporating combined annuloplasty and subvalvular repair techniques to optimize the outcomes of mitral valve repair in ischemic MR.

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

  18. Acute pericarditis as a complication of percutaneous mitral balloon valvulotomy.

    PubMed

    Turhan, Hasan; Basar, Nurcan; Yasar, Ayse Saatci; Erbay, Ali Riza; Atak, Ramazan

    2006-01-01

    During the past two decades, percutaneous mitral balloon valvulotomy (PMBV) has been frequently used, with high success and low complication rates, in the treatment of patients with moderate to severe rheumatic mitral stenosis. The case is reported of a patient with severe rheumatic mitral stenosis who developed acute pericarditis two days after successful PMBV. To the best of the authors' knowledge, this is the first such case to be reported.

  19. En face view of the mitral valve: definition and acquisition.

    PubMed

    Mahmood, Feroze; Warraich, Haider Javed; Shahul, Sajid; Qazi, Aisha; Swaminathan, Madhav; Mackensen, G Burkhard; Panzica, Peter; Maslow, Andrew

    2012-10-01

    A 3-dimensional echocardiographic view of the mitral valve, called the "en face" or "surgical view," presents a view of the mitral valve similar to that seen by the surgeon from a left atrial perspective. Although the anatomical landmarks of this view are well defined, no comprehensive echocardiographic definition has been presented. After reviewing the literature, we provide a definition of the left atrial and left ventricular en face views of the mitral valve. Techniques used to acquire this view are also discussed.

  20. Finite element analysis to model complex mitral valve repair.

    PubMed

    Labrosse, Michel; Mesana, Thierry; Baxter, Ian; Chan, Vincent

    2016-01-01

    Although finite element analysis has been used to model simple mitral repair, it has not been used to model complex repair. A virtual mitral valve model was successful in simulating normal and abnormal valve function. Models were then developed to simulate an edge-to-edge repair and repair employing quadrangular resection. Stress contour plots demonstrated increased stresses along the mitral annulus, corresponding to the annuloplasty. The role of finite element analysis in guiding clinical practice remains undetermined.

  1. Mitral Valve Prolapse or, What to Ignore in Cardiology

    PubMed Central

    Fallen, Ernest L.

    1981-01-01

    The presence of an isolated midsystolic click and/or late systolic murmur in an otherwise healthy young individual is a totally benign entity and represents a normal variation of mitral valve motion and function. There exists a very small subset of patients with mitral prolapse easily identified by certain clinical characteristics, who have distinct pathologic changes in their mitral valve leaflets and supporting structures. (Can Fam Physician 1981; 27:631-634). PMID:21289711

  2. Evolution of the concept and practice of mitral valve repair

    PubMed Central

    Tchantchaleishvili, Vakhtang; Rajab, Taufiek K.

    2015-01-01

    The first successful mitral valve repair was performed by Elliot Cutler at Brigham and Women’s Hospital in 1923. Subsequent evolution in the surgical techniques as well as multi-disciplinary cooperation between cardiac surgeons, cardiologists and cardiac anesthesiologists has resulted in excellent outcomes. In spite of this, the etiology of mitral valve pathology ultimately determines the outcome of mitral valve repair. PMID:26309840

  3. Acute aortic and mitral valve regurgitation following blunt chest trauma.

    PubMed

    Bernabeu, Eduardo; Mestres, Carlos A; Loma-Osorio, Pablo; Josa, Miguel

    2004-03-01

    Traumatic rupture of intracardiac structures is an uncommon phenomenon although there are a number of reports with regards to rupture of the tricuspid, mitral and aortic valves. We report the case of a 25-year-old patient who presented with acute aortic and mitral valve regurgitation of traumatic origin. Both lesions were seen separated by 2 weeks. Pathophysiology is reviewed. The combination of both aortic and mitral lesions following blunt chest trauma is almost exceptional.

  4. Effects of unisegmental disc compression on adjacent segments: an in vivo animal model.

    PubMed

    Unglaub, Frank; Guehring, Thorsten; Lorenz, Helga; Carstens, Claus; Kroeber, Markus W

    2005-12-01

    It is controversial whether fusion of discs in the spine leads to increased degeneration on the remaining discs or whether the degenerative changes are merely a part of the inevitable natural history process. To determine the effects of unisegmental compression and subsequent recovery on adjacent segments, we studied histology, radiology and intradiscal pressure using an in vivo rabbit model. Fifteen New Zealand rabbits were divided in to three groups of five. In the first group, the intervertebral disc L4-L5 of the lumbar spine was axially loaded for 28 days with an external loading device. In the second group, the intervertebral disc was compressed for 28 days and allowed to recover for an equal amount of time, with the loading device removed. Five animals underwent a sham operation, in which the external loading device was situated, but their discs remained unloaded for 28 days. The intradiscal pressure was determined in the loaded discs as well as in the cranial and caudal adjacent discs. Lateral radiographs were taken from each subjected intervertebral disc with adjacent vertebral bodies and the cranial and caudal adjacent segments. The compressed discs showed lower intradiscal pressure in comparison with the control group, which remained unloaded. In the cranial and caudal discs adjacent to the loaded discs the average intradiscal pressure was similar to the unloaded controls. The loaded discs demonstrated a significant decrease in disc space. No discs adjacent to the loaded discs changed in height. The lamellar architecture of the inner, middle, and outer annulus became more disorganized in the loaded discs. The nucleus pulposus showed increase of mucoid degeneration and increased cell death. Intervertebral discs from the control group and the adjacent discs to the compressed discs maintained their normal morphology. This study shows that mechanical loading of discs in the spine can cause rapid degeneration. Adjacent discs, however, did not change in terms

  5. Holographic optical disc

    NASA Astrophysics Data System (ADS)

    Zhou, Gan; An, Xin; Pu, Allen; Psaltis, Demetri; Mok, Fai H.

    1999-11-01

    The holographic disc is a high capacity, disk-based data storage device that can provide the performance for next generation mass data storage needs. With a projected capacity approaching 1 terabit on a single 12 cm platter, the holographic disc has the potential to become a highly efficient storage hardware for data warehousing applications. The high readout rate of holographic disc makes it especially suitable for generating multiple, high bandwidth data streams such as required for network server computers. Multimedia applications such as interactive video and HDTV can also potentially benefit from the high capacity and fast data access of holographic memory.

  6. Mitral and tricuspid valve surgery for Coffin-Lowry syndrome.

    PubMed

    Yoshida, Takeshi; Ohashi, Takeki; Furui, Masato; Kageyama, Souichirou; Kodani, Noriko; Kobayashi, Yutaka; Hirai, Yasutaka; Sakakura, Reo

    2015-05-01

    Coffin-Lowry syndrome is a rare X-linked disorder characterized by craniofacial and skeletal abnormalities, mental retardation, short stature, and hypotonia. An 18-year-old man with morphologic features characteristic of Coffin-Lowry syndrome was referred to our institution for valve disease surgery for worsening cardiac failure. Echocardiography showed severe mitral valve regurgitation associated with tricuspid valve regurgitation. Mitral valve implantation with a biological valve and tricuspid annular plication with a ring was performed. The ascending aorta was hypoplastic. Both the mitral papillary muscle originating near the mitral annulus and the chordae were shortened. The patient's postoperative course was uneventful and his cardiac failure improved.

  7. Chimney technique for mitral valve replacement in children.

    PubMed

    González Rocafort, Álvaro; Aroca, Ángel; Polo, Luz; Rey, Juvenal; Villagrá, Fernando

    2013-11-01

    Severe mitral stenosis is unusual in children, but it represents an important challenge for surgeons because of the scarcity of solutions. Several mitral percutaneous and surgical valvuloplasties are performed repetitively to delay mitral valve replacement. Most of the time these procedures show discouraging results. When mitral valve replacement is performed, the annulus may not be large enough to fit a substitute. We present, to our best knowledge, a new technique to implant a large prosthesis in a small annulus without negatively affecting the opening of the leaflets.

  8. Robotic-assisted mitral valve repair: surgical technique.

    PubMed

    Algarni, Khaled D; Suri, Rakesh M; Daly, Richard C

    2014-01-01

    Robotic-assisted mitral valve repair represents the least invasive surgical approach currently available for anatomical mitral valve repair in patients with myxomatous mitral valve disease. Standard mitral valve repair techniques utilized during conventional sternotomy/right thoracotomy are exactly replicated with the robotic instrumentation through 1-2 cm port-like incisions with superior 3D visualization. This is performed on cardiopulmonary bypass by peripheral cannulation of the femoral vessels/right internal jugular vein. The ascending aorta is occluded with a transthoracic aortic cross-clamp. Antegrade cardioplegia is delivered centrally into the aortic root through a cardioplegia vent catheter. By replicating conventional mitral valve repair done via an open sternotomy approach, the quality of mitral valve repair is ensured while providing the patients with advantages of less invasive surgery including shorter hospital stay, rapid recovery and return to normal activities, less blood transfusion, superior cosmesis and complete elimination of sternotomy-related morbidities such as deep sternal wound infection and sternal dehiscence. We reviewed the first consecutive 200 patients undergoing robotic mitral valve repair at Mayo Clinic Rochester between 24 January 2008 and 28 January 2011. Successful mitral valve repair was completed in all patients. There were no early (30-day) deaths. One patient suffered a stroke (0.5%). One patient required reoperation for bleeding (0.5%). Two patients (1%) required reoperation for recurrent mitral regurgitation. Twelve patients (6%) required transfusion of allogeneic blood products. We have noted a significant reduction in operative times and resource utilization over time.

  9. Transcatheter Mitral Valve Repair Therapies: Evolution, Status and Challenges.

    PubMed

    Espiritu, Daniella; Onohara, Daisuke; Kalra, Kanika; Sarin, Eric L; Padala, Muralidhar

    2017-02-01

    Mitral regurgitation is a common cardiac valve lesion, developing from primary lesions of the mitral valve or secondary to cardiomyopathies. Moderate or higher severity of mitral regurgitation imposes significant volume overload on the left ventricle, causing permanent structural and functional deterioration of the myocardium and heart failure. Timely correction of regurgitation is essential to preserve cardiac function, but surgical mitral valve repair is often delayed due to the risks of open heart surgery. Since correction of mitral regurgitation can provide symptomatic relief and halt progressive cardiac dysfunction, transcatheter mitral valve repair technologies are emerging as alternative therapies. In this approach, the mitral valve is repaired either with sutures or implants that are delivered to the native valve on catheters introduced into the cardiovascular system under image guidance, through small vascular or ventricular ports. Several transcatheter mitral valve technologies are in development, but limited clinical success has been achieved. In this review, we present a historical perspective of mitral valve repair, review the transcatheter technologies emerging from surgical concepts, the challenges they face in achieving successful clinical application, and the increasing rigor of safety and durability standards for new transcatheter valve technologies.

  10. [Totally robotic mitral valve surgery in 60 cases].

    PubMed

    Yang, Ming; Gao, Chang-qing; Wang, Gang; Wang, Jia-li; Xiao, Cang-song; Wu, Yang

    2011-10-01

    To evaluate the safety and efficacy of robotic mitral valve surgery using da Vinci S system. We conducted a retrospective review of 60 robotic mitral surgeries from March 2007 to December 2010. Of the 60 patients, 44 underwent mitral valve repair and 16 received mitral valve replacement. The surgical approach was through 4 right chest ports with femoral and internal jugular vein cannulations. Transesophageal echocardiography was used intraoperatively to estimate the surgical results. None of the cases required a conversion to a median sternotomy. The mean cardiopulmonary bypass and cardiac arrest time was 132.2∓29.6 min and 88.1∓22.3 min for robotic mitral valve repair, and was 137.1∓21.9 min and 99.3∓17.4 min for robotic mitral valve replacement. Echocardiographic follow-up of all the patients revealed 3 cases of slight regurgitation in mitral valve repair group. In selected patients with mitral valve disease, robotic mitral surgery can be performed safely.

  11. Peri-procedural imaging for transcatheter mitral valve replacement

    PubMed Central

    Natarajan, Navin; Patel, Parag; Bartel, Thomas; Kapadia, Samir; Navia, Jose; Stewart, William; Tuzcu, E. Murat

    2016-01-01

    Mitral regurgitation (MR) has a high prevalence in older patient populations of industrialized nations. Common etiologies are structural, degenerative MR and functional MR secondary to myocardial remodeling. Because of co-morbidities and associated high surgical risk, open surgical mitral repair/replacement is deferred in a significant percentage of patients. For these patients transcatheter repair/replacement are emerging as treatment options. Because of the lack of direct visualization, pre- and intra-procedural imaging is critical for these procedures. In this review, we summarize mitral valve anatomy, trans-catheter mitral valve replacement (TMVR) options, and imaging in the context of TMVR. PMID:27054104

  12. Effect of the mitral valve on diastolic flow patterns

    SciTech Connect

    Seo, Jung Hee; Vedula, Vijay; Mittal, Rajat; Abraham, Theodore; Dawoud, Fady; Luo, Hongchang; Lardo, Albert C.

    2014-12-15

    The leaflets of the mitral valve interact with the mitral jet and significantly impact diastolic flow patterns, but the effect of mitral valve morphology and kinematics on diastolic flow and its implications for left ventricular function have not been clearly delineated. In the present study, we employ computational hemodynamic simulations to understand the effect of mitral valve leaflets on diastolic flow. A computational model of the left ventricle is constructed based on a high-resolution contrast computed-tomography scan, and a physiological inspired model of the mitral valve leaflets is synthesized from morphological and echocardiographic data. Simulations are performed with a diode type valve model as well as the physiological mitral valve model in order to delineate the effect of mitral-valve leaflets on the intraventricular flow. The study suggests that a normal physiological mitral valve promotes the formation of a circulatory (or “looped”) flow pattern in the ventricle. The mitral valve leaflets also increase the strength of the apical flow, thereby enhancing apical washout and mixing of ventricular blood. The implications of these findings on ventricular function as well as ventricular flow models are discussed.

  13. Mitral Regurgitation after Percutaneous Balloon Mitral Valvotomy in Patients with Rheumatic Mitral Stenosis: A Single-Center Study

    PubMed Central

    Aslanabadi, Naser; Toufan, Mehrnoush; Salehi, Rezvaneyeh; Alizadehasl, Azin; Ghaffari, Samad; Sohrabi, Bahram; Separham, Ahmad; Manafi, Ataolaah; Mehdizadeh, Mohammad Bagher; Habibzadeh, Afshin

    2014-01-01

    Abstract Background: Percutaneous balloon mitral valvotomy (BMV) is the gold standard treatment for rheumatic mitral stenosis (MS) in that it causes significant changes in mitral valve area (MVA) and improves leaflet mobility. Development of or increase in mitral regurgitation (MR) is common after BMV. This study evaluated MR severity and its changes after BMV in Iranian patients. Methods: We prospectively evaluated consecutive patients with severe rheumatic MS undergoing BMV using the Inoue balloon technique between February 2010 and January 2013 in Madani Heart Center, Tabriz, Iran. New York Heart Association (NYHA) functional class and echocardiographic and catheterization data, including MVA, mitral valve mean and peak gradient (MVPG and MVMG), left atrial (LA) pressure, pulmonary artery systolic pressure (PAPs), and MR severity before and after BMV, were evaluated. Results: Totally, 105 patients (80% female) at a mean age of 45.81 ± 13.37 years were enrolled. NYHA class was significantly improved after BMV: 55.2% of the patients were in NYHA functional class III before BMV compared to 36.2% after the procedure (p value < 0.001). MVA significantly increased (mean area = 0.64 ± 0.29 cm2 before BMV vs. 1.90 ± 0.22 cm2 after BMV; p value < 0.001) and PAPs, LA pressure, MVPG, and MVMG significantly decreased. MR severity did not change in 82 (78.1%) patients, but it increased in 18 (17.1%) and decreased in 5 (4.8%) patients. Patients with increased MR had a significantly higher calcification score (2.03 ± 0.53 vs.1.50 ± 0.51; p value < 0.001) and lower MVA before BMV (0.81 ± 0.23 vs.0.94 ± 0.18; p value = 0.010). There were no major complications. Conclusion: In our study, BMV had excellent immediate hemodynamic and clinical results inasmuch as MR severity increased only in some patients and, interestingly, decreased in a few. Our results, underscore BMV efficacy in severe MS. The echocardiographic calcification score was useful for identifying patients

  14. Mitral regurgitation after percutaneous balloon mitral valvotomy in patients with rheumatic mitral stenosis: a single-center study.

    PubMed

    Aslanabadi, Naser; Toufan, Mehrnoush; Salehi, Rezvaneyeh; Alizadehasl, Azin; Ghaffari, Samad; Sohrabi, Bahram; Separham, Ahmad; Manafi, Ataolaah; Mehdizadeh, Mohammad Bagher; Habibzadeh, Afshin

    2014-01-01

    Percutaneous balloon mitral valvotomy (BMV) is the gold standard treatment for rheumatic mitral stenosis (MS) in that it causes significant changes in mitral valve area (MVA) and improves leaflet mobility. Development of or increase in mitral regurgitation (MR) is common after BMV. This study evaluated MR severity and its changes after BMV in Iranian patients. We prospectively evaluated consecutive patients with severe rheumatic MS undergoing BMV using the Inoue balloon technique between February 2010 and January 2013 in Madani Heart Center, Tabriz, Iran. New York Heart Association (NYHA) functional class and echocardiographic and catheterization data, including MVA, mitral valve mean and peak gradient (MVPG and MVMG), left atrial (LA) pressure, pulmonary artery systolic pressure (PAPs), and MR severity before and after BMV, were evaluated. Totally, 105 patients (80% female) at a mean age of 45.81 ± 13.37 years were enrolled. NYHA class was significantly improved after BMV: 55.2% of the patients were in NYHA functional class III before BMV compared to 36.2% after the procedure (p value < 0.001). MVA significantly increased (mean area = 0.64 ± 0.29 cm(2) before BMV vs. 1.90 ± 0.22 cm(2) after BMV; p value < 0.001) and PAPs, LA pressure, MVPG, and MVMG significantly decreased. MR severity did not change in 82 (78.1%) patients, but it increased in 18 (17.1%) and decreased in 5 (4.8%) patients. Patients with increased MR had a significantly higher calcification score (2.03 ± 0.53 vs.1.50 ± 0.51; p value < 0.001) and lower MVA before BMV (0.81 ± 0.23 vs.0.94 ± 0.18; p value = 0.010). There were no major complications. In our study, BMV had excellent immediate hemodynamic and clinical results inasmuch as MR severity increased only in some patients and, interestingly, decreased in a few. Our results, underscore BMV efficacy in severe MS. The echocardiographic calcification score was useful for identifying patients likely to have MR development or MR increase after

  15. Staphylococcus caprae native mitral valve infective endocarditis

    PubMed Central

    Poyner, Jennifer; Olson, Ewan; Henriksen, Peter; Koch, Oliver

    2016-01-01

    Introduction: Staphylococcus caprae is a rare cause of infective endocarditis. Here, we report a case involving the native mitral valve in the absence of an implantable cardiac electronic device. Case presentation: A 76-year-old man presented with a 2 week history of confusion and pyrexia. His past medical history included an open reduction and internal fixation of a humeral fracture 17 years previously, which remained non-united despite further revision 4 years later. There was no history of immunocompromise or farm-animal contact. Two sets of blood culture bottles, more than 12 h apart, were positive for S. caprae. Trans-thoracic echocardiography revealed a 1×1.2 cm vegetation on the mitral valve, with moderate mitral regurgitation. Due to ongoing confusion, he had a magnetic resonance imaging brain scan, which showed a subacute small vessel infarct consistent with a thromboembolic source. A humeral SPECT-CT (single-photon emission computerized tomography-computerized tomography) scan showed no clear evidence of acute osteomyelitis. Surgical vegetectomy and mitral-valve repair were considered to reduce the risk of further systemic embolism and progressive valve infection. However, the potential risks of surgery to this patient led to a decision to pursue a cure with antibiotic therapy alone. He remained well 3 months after discharge, with repeat echocardiography demonstrating a reduction in the size of the vegetation (0.9 cm). Conclusion: Management of this infection was challenging due to its rarity and its unclear progression, complicated by the dilemma surrounding surgical intervention in a patient with a complex medical background. PMID:28348787

  16. New in vivo animal model to create intervertebral disc degeneration and to investigate the effects of therapeutic strategies to stimulate disc regeneration.

    PubMed

    Kroeber, Markus W; Unglaub, Frank; Wang, Haili; Schmid, Carsten; Thomsen, Marc; Nerlich, Andreas; Richter, Wiltrud

    2002-12-01

    A new rabbit model was developed that produces disc degeneration through the application of controlled and quantified axial mechanical load. To characterize the changes associated with disc degeneration, and to evaluate the feasibility of local transfer of agents to the compressed discs to stimulate disc regeneration. Studies have shown that accelerated degeneration of the intervertebral disc results from altered mechanical loading conditions. The development of methods for the prevention of disc degeneration and the restoration of disc tissue that has already degenerated is needed. New Zealand white rabbits (n = 33) were used for this study. The discs in five animals remained unloaded and served as controls, whereas in 28 animals the discs were axially compressed using a custom-made external loading device. After 1 (n = 7), 14 (n = 7), and 28 (n = 7) days of dynamic loading, or 28 (n = 7) days of loading followed by 28 days of unloaded recovery time, the animals were killed and the lumbar spine was harvested for tissue preparation. Disc height, disc morphology, cell viability, disc stiffness, and load to failure were measured. Recombinant adenovirus encoding for two different marker genes (Ad-Luciferase and Ad-LacZ) was injected into the discs in loaded specimens and the gene expression was measured. The unloaded intervertebral discs of the rabbits consisted of a layered anulus fibrosus, a cartilaginous endplate, and a nucleus pulposus comparable with those of humans. After 14 and 28 days of loading, the discs demonstrated a significant decrease in disc space. Histologically, disorganization of the architecture of the anulus occurred. The number of dead cells increased significantly in the anulus and cartilage endplate. These changes were not reversible after 28 days of unloading. The stiffness and the load to failure did not change significantly in the discs after 28 days of loading, as compared with the unloaded control discs. Adenovirus-mediated gene transfer

  17. Preservation versus non-preservation of mitral valve apparatus during mitral valve replacement: a meta-analysis of 3835 patients

    PubMed Central

    Sá, Michel Pompeu Barros de Oliveira; Ferraz, Paulo Ernando; Escobar, Rodrigo Renda; Martins, Wendell Santos; de Araújo e Sá, Frederico Browne Correia; Lustosa, Pablo César; Vasconcelos, Frederico Pires; Lima, Ricardo Carvalho

    2012-01-01

    Resection of the chordopapillary apparatus during mitral valve replacement has been associated with a negative impact on survival. Mitral valve replacement with the preservation of the mitral valve apparatus has been associated with better outcomes, but surgeons remain refractory to its use. To determine if there is any real difference in preservation vs non-preservation of mitral valve apparatus during mitral valve replacement in terms of outcomes, we performed a systematic review and meta-analysis using MEDLINE, EMBASE, CENTRAL/CCTR, SciELO, LILACS, Google Scholar and reference lists of relevant articles to search for clinical studies that compared outcomes (30-day mortality, postoperative low cardiac output syndrome or 5-year mortality) between preservation vs non-preservation during mitral valve replacement from 1966 to 2011. The principal summary measures were odds ratios (ORs) with 95% confidence interval and P-values (that will be considered statistically significant when <0.05). The ORs were combined across studies using a weighted DerSimonian–Laird random-effects model. The meta-analysis was completed using the software Comprehensive Meta-Analysis version 2 (Biostat Inc., Englewood, NJ, USA). Twenty studies (3 randomized and 17 non-randomized) were identified and included a total of 3835 patients (1918 for mitral valve replacement preservation and 1917 for mitral valve replacement non-preservation). There was significant difference between mitral valve replacement preservation and mitral valve replacement non-preservation groups in the risk of 30-day mortality (OR 0.418, P <0.001), postoperative low cardiac output syndrome (OR 0.299, P <0.001) or 5-year mortality (OR 0.380, P <0.001). No publication bias or important heterogeneity of effects on any outcome was observed. In conclusion, we found evidence that argues in favour of the preservation of mitral valve apparatus during mitral valve replacement. PMID:23027596

  18. Nonresectional Single-Suture Leaflet Remodeling for Degenerative Mitral Regurgitation Facilitates Minimally Invasive Mitral Valve Repair

    PubMed Central

    MacArthur, John W.; Cohen, Jeffrey E.; Goldstone, Andrew B.; Fairman, Alexander S.; Edwards, Bryan B.; Hornick, Matthew A.; Atluri, Pavan; Woo, Y. Joseph

    2014-01-01

    Background Both leaflet resection and neochordal construction are effective mitral repair techniques, but they may become incrementally time-consuming when using minimally invasive approaches. We have used a single-suture leaflet-remodeling technique of inverting the prolapsed or flail segment tissue into the left ventricle. This repair is straightforward, expeditious, and facilitates a minimally invasive approach. Methods Ninety-nine patients with degenerative mitral regurgitation (MR) underwent a minimally invasive single-suture repair of the mitral valve from May 2007 through December 2012. Preoperative and perioperative echocardiograms as well as patient outcomes were analyzed and compared with those obtained from patients undergoing minimally invasive mitral valve repair using quadrangular resection at the same institution during the same period. Results All 99 patients had a successful mitral repair through a sternal-sparing minimally invasive approach. Ninety-one of the 99 patients had zero MR on postoperative echocardiogram, and 8 of 99 had trace to mild MR. Patients in the nonresectional group had significantly shorter cardiopulmonary bypass and cross-clamp times compared with the quadrangular resection group (115.8 ± 41.7 minutes versus 144.9 ± 38.2 minutes; p < 0.001; 76.2 ± 28.1 minutes versus 112.6 ± 33.5 minutes; p < 0.001, respectively). The mean length of stay was 7.5 ± 3 days. All patients were discharged alive and free from clinical symptoms of MR. There have been no reoperations for recurrent MR on subsequent average follow-up of 1 year. Conclusions An effective, highly efficient, and thus far durable single-suture mitral leaflet-remodeling technique facilitates minimally invasive repair of degenerative MR. PMID:23932318

  19. Fluid–Structure Interaction Analysis of Papillary Muscle Forces Using a Comprehensive Mitral Valve Model with 3D Chordal Structure

    SciTech Connect

    Toma, Milan; Jensen, Morten Ø.; Einstein, Daniel R.; Yoganathan, Ajit P.; Cochran, Richard P.; Kunzelman, Karyn S.

    2015-07-17

    Numerical models of native heart valves are being used to study valve biomechanics to aid design and development of repair procedures and replacement devices. These models have evolved from simple two-dimensional approximations to complex three-dimensional, fully coupled fluid-structure interaction (FSI) systems. Such simulations are useful for predicting the mechanical and hemodynamic loading on implanted valve devices. A current challenge for improving the accuracy of these predictions is choosing and implementing modeling boundary conditions. In order to address this challenge, we are utilizing an advanced in-vitro system to validate FSI conditions for the mitral valve system. Explanted ovine mitral valves were mounted in an in vitro setup, and structural data for the mitral valve was acquired with *CT. Experimental data from the in-vitro ovine mitral valve system were used to validate the computational model. As the valve closes, the hemodynamic data, high speed lea et dynamics, and force vectors from the in-vitro system were compared to the results of the FSI simulation computational model. The total force of 2.6 N per papillary muscle is matched by the computational model. In vitro and in vivo force measurements are important in validating and adjusting material parameters in computational models. The simulations can then be used to answer questions that are otherwise not possible to investigate experimentally. This work is important to maximize the validity of computational models of not just the mitral valve, but any biomechanical aspect using computational simulation in designing medical devices.

  20. Robotic Transcatheter Mitral Valve Replacement Using the Sapien XT in the Setting of Severe Mitral Annular Calcification.

    PubMed

    Koeckert, Michael S; Loulmet, Didier F; Williams, Mathew R; Neuburger, Peter J; Grossi, Eugene A

    2016-05-01

    We describe the use of the Sapien XT, placed in the mitral position using a totally endoscopic robotic approach in a 76-year-old man with extensive circumferential mitral calcifications and severe stenosis. The patient was at high risk for traditional open surgery and a large mitral valve annulus prevented safe transcatheter deployment due to size mismatch. Our novel approach offered a minimally invasive technique for native mitral valve replacement in a high-risk patient with anatomical constraints prohibitive to conventional approaches. doi: 10.1111/jocs.12737 (J Card Surg 2016;31:303-305). © 2016 Wiley Periodicals, Inc.

  1. Artificial Disc Replacement

    MedlinePlus

    ... also disc replacements designed for use in the cervical spine (the neck). These devices have only been used ... of your spine increases the risk of significant injury during this type of spinal surgery. Back pain ...

  2. [A case of death due to mitral regurgitation caused by traumatic mitral valve injury].

    PubMed

    Iwasaki, Y; Kojima, T; Yasui, W; Nagasawa, N; Yashiki, M

    1996-06-01

    A 51-year-old male, who had been driving a motor bicycle, was involved in a traffic accident with a trailer, and he died immediately after the accident. According to the external examination of the victim, no fatal injuries were found. The medico-legal autopsy revealed a rupture of the left side of the pericardium, and a tear of the posterior leaflet of the mitral valve. There were no injuries of the papillary muscles and chordae. The cause of death was due to traumatic mitral regurgitation.

  3. Impact of mitral valve geometry on hemodynamic efficacy of surgical repair in secondary mitral regurgitation.

    PubMed

    Padala, Muralidhar; Gyoneva, Lazarina I; Thourani, Vinod H; Yoganathan, Ajit P

    2014-01-01

    Mitral valve geometry is significantly altered secondary to left ventricular remodeling in non-ischemic and ischemic dilated cardiomyopathies. Since the extent of remodeling and asymmetry of dilatation of the ventricle differ significantly between individual patients, the valve geometry and tethering also differ. The study aim was to determine if mitral valve geometry has an impact on the efficacy of surgical repairs to eliminate regurgitation and restore valve closure in a validated experimental model. Porcine mitral valves (n = 8) were studied in a pulsatile heart simulator, in which the mitral valve geometry can be precisely altered and controlled throughout the experiment. Baseline hemodynamics for each valve were measured (Control), and the valves were tethered in two distinct ways: annular dilatation with 7 mm apical papillary muscle (PM) displacement (Tether 1, symmetric), and annular dilatation with 7 mm apical, 7 mm posterior and 7 mm lateral PM displacement (Tether 2, asymmetric). Mitral annuloplasty was performed on each valve (Annular Repair), succeeded by anterior leaflet secondary chordal cutting (Sub-annular Repair). The efficacy of each repair in the setting of a given valve geometry was quantified by measuring the changes in mitral regurgitation (MR), leaflet coaptation length, tethering height and area. At baseline, none of the valves was regurgitant. Significant leaflet tethering was measured in Tether 2 over Tether 1, but both groups were significantly higher compared to baseline (60.9 +/- 31 mm2 for Control versus 129.7 +/- 28.4 mm2 for Tether 1 versus 186.4 +/- 36.3 mm2 for Tether 2). Consequently, the MR fraction was higher in Tether 2 group (23.0 +/- 5.7%) than in Tether 1 (10.5 +/- 5.5%). Mitral annuloplasty reduced MR in both groups, but remnant regurgitation after the repair was higher in Tether 2. After chordal cutting a similar trend was observed with trace regurgitation in Tether 1 group at 3.6 +/- 2.8%, in comparison to 18.6 +/- 4

  4. Thermal analysis of disc brakes using finite element method

    NASA Astrophysics Data System (ADS)

    Jaenudin, Jamari, J.; Tauviqirrahman, M.

    2017-01-01

    Disc brakes are components of a vehicle that serve to slow or stop the rotation of the wheel. This paper discusses the phenomenon of heat distribution on the brake disc during braking. Heat distribution on the brake disc is caused by kinetic energy changing into mechanical energy. Energy changes occur during the braking process due to friction between the surface of the disc and a disc pad. The temperature resulting from this friction rises high. This thermal analysis on brake discs is aimed to evaluate the performance of an electric car in the braking process. The aim of this study is to analyze the thermal behavior of the brake discs using the Finite Element Method (FEM) through examining the heat distribution on the brake disc using 3-D modeling. Results obtained from the FEM reflect the effects of high heat due to the friction between the disc pad with the disc rotor. Results of the simulation study are used to identify the effect of the heat distribution that occurred during the braking process.

  5. Myxomatous mitral valve disease in dogs: Does size matter?

    PubMed Central

    Parker, Heidi G.; Kilroy-Glynn, Paul

    2012-01-01

    Myxomatous mitral valve disease (MMVD) is the most commonly diagnosed cardiovascular disease in the dog accounting for more than 70% of all cardiovascular disease in dogs. As are most canine diseases with genetic underpinnings, risk of MMVD is greatly increased in a subset of breeds. What is uncommon is that the vast majority of the breeds at elevated risk for MMVD are small or toy breeds with average adult weights under 9 kg. These breeds appear to have little in common other than their diminutive size. In the following review we propose a number of mechanisms by which relatively unrelated small breeds may have developed a predisposition for chronic valvular disorders. Although factors such as age are key in the expression of MMVD, taking a comprehensive look at the commonalities, as well as the differences, between the susceptible breeds may assist in finding the causal variants responsible for MMVD and translating them to improved treatments for both dogs and humans. PMID:22356836

  6. Prosthetic mitral valve thrombosis in pregnancy: from thrombolysis to anticoagulation.

    PubMed

    Cardoso, Gonçalo; Aguiar, Carlos; Andrade, Maria João; Patrício, Lino; Freire, Isabel; Serrano, Fátima; Anjos, Rui; Mendes, Miguel

    2015-01-01

    Pregnant women with mechanical prosthetic heart valves are at increased risk for valve thrombosis. Management decisions for this life-threatening complication are complex. Open-heart surgery has a very high risk of maternal mortality and fetal loss. Bleeding and embolic risks associated with thrombolytic agents, the limited efficacy of thrombolysis in certain subgroups, and a lack of experience in the setting of pregnancy raise important concerns. We report a case of mitral prosthetic valve thrombosis in early pregnancy, which was successfully treated with streptokinase. Ten years later, the same patient had an uneventful pregnancy, throughout which acenocoumarol was maintained. With this case we review the prevention (with oral anticoagulant therapy) and treatment of prosthetic valve thrombosis during pregnancy, which is important for both obstetrician and cardiologist. Copyright © 2014 Sociedade Portuguesa de Cardiologia. Published by Elsevier España. All rights reserved.

  7. Echocardiographic evaluation of mitral stenosis using diastolic posterior left ventricular wall motion.

    PubMed

    Wise, J R

    1980-05-01

    The slope of the posterior left ventricular wall motion in diastole (LVDS) was determined by echocardiography in 25 normal subjects and 21 patients with mitral stenosis. Patients with mitral stenosis had reduced LVDS that was related to the degree of mitral stenosis determined by calculated mitral valve area (r = 0.92). The mitral valve area correlated more closely with the LVDS than with the left atrial emptying index derived from the posterior aortic wall motion. Three patients with mitral stenosis had an increased LVDS after mitral valvotomy or mitral valve replacement. One patient with a stenotic mitral valve prosthesis had reduced LVDS. The results of this study suggest that analysis of the LVDS would be useful in predicting the severity of mitral stenosis and may be beneficial in evaluating patients with suspected prosthetic mitral valve malfunction.

  8. Bryan total disc arthroplasty: a replacement disc for cervical disc disease

    PubMed Central

    Wenger, Markus; Markwalder, Thomas-Marc

    2010-01-01

    Total disc arthroplasty is a new option in the treatment of cervical degenerative disc disease. Several types of cervical disc prostheses currently challenge the gold-standard discectomy and fusion procedures. This review describes the Bryan Cervical Disc System and presents the Bryan prosthesis, its indications, surgical technique, complications, and outcomes, as given in the literature. PMID:22915917

  9. Effect of noxious electrical stimulation of the peroneal nerve on stretch reflex activity of the hamstring muscle in rats: possible implications of neuronal mechanisms in the development of tight hamstrings in lumbar disc herniation.

    PubMed

    Hirayama, Jiro; Yamagata, Masatsune; Takahashi, Kazuhisa; Moriya, Hideshige

    2005-05-01

    The effect of noxious electrical stimulation of the peroneal nerve on the stretch reflex electromyogram activity of the hamstring muscle (semitendinous) was studied. To verify the following hypothetical mechanisms underlying tight hamstrings in lumbar disc herniation: stretch reflex muscle activity of hamstrings is increased by painful inputs from an injured spinal nerve root and the increased stretch reflex muscle activity is maintained by central sensitization. It is reported that stretch reflex activity of the trunk muscles is induced by noxious stimulation of the sciatic nerve and maintained by central sensitization. In spinalized rats (transected spinal cord), the peroneal nerve was stimulated electrically as a conditioning stimulus. Stretch reflex electromyogram activity of the semitendinous muscle was recorded before and after the conditioning stimulus. Even after electrical stimulation was terminated, an increased stretch reflex activity of the hamstring muscle was observed. It is likely that a central sensitization mechanism at the spinal cord level was involved in the increased reflex activity. Central sensitization may play a part in the neuronal mechanisms of tight hamstrings in lumbar disc herniation.

  10. [Biology and mechanobiology of the intervertebral disc].

    PubMed

    González Martínez, Emilio; García-Cosamalón, José; Cosamalón-Gan, Iván; Esteban Blanco, Marta; García-Suarez, Olivia; Vega, José A

    2017-01-24

    The intervertebral disc (IVD) is noted for its low cell content, and being the largest avascular structure of human body. The low amount of cells in the disc have to adapt to an anaerobic metabolism with low oxygen pressure and acidic pH. Apart from surviving in an adverse microenvironment, they are exposed to a high level of mechanical stress. The biological adaptation of cells to acidosis and hyperosmolarity conditions are regulated by mechanoproteins, which are responsible for converting a mechanical signal into a cellular response, thus modifying its gene expression. Mechanobiology helps us to better understand the pathophysiology of IVD and its potential biological repair.

  11. Clinical and morphologic observations after simultaneous replacement of the tricuspid, mitral and aortic valves.

    PubMed

    Sullivan, M F; Roberts, W C

    1986-10-01

    Clinical and morphologic observations are described in 12 patients who underwent simultaneous replacement of the tricuspid, mitral and aortic valves. All 12 patients had mitral stenosis, 10 aortic valve stenosis and 2 pure aortic valve regurgitation; 5 had tricuspid valve stenosis and 7 pure tricuspid valve regurgitation. Of the 10 patients who died within 60 days of triple valve replacement, 7 had the low cardiac output syndrome, which in 4, and possibly 5, of the 7 was attributed to prosthetic aortic valve stenosis. In none of the 12 patients was the ascending aorta dilated, and in the 4 (possibly 5) patients with low cardiac output, the space between the surface of the caged poppet (4 patients) or margins of the tilting disc (1 patient) in the aortic valve position and the aortic endothelium appeared inadequate to allow unobstructed flow despite small-sized prostheses in all but 1 patient. Thus, aortic valve replacement in the setting of triple valve dysfunction is hazardous or potentially so. The relative small sizes of the hearts in these patients also make valve replacement more difficult (and hazardous) compared to hearts with larger ventricles and aortas.

  12. [Research advances in animal models of intervertebral disc degeneration].

    PubMed

    Zhang, Wenli; Liu, Hao; Li, Tanzhu

    2007-11-01

    To review the research advances in animal models of human disc degeneration. The relative articles in recent years were extensively reviewed. Studies both at home and abroad were analyzed and classified. The advantages and disadvantages of each method were compared. Studies were classified as either experimentally induced models or spontaneous models. The induced models were subdivided as mechanical (alteration of forces on the normal disc), structural (injury or chemical alteration) and genetically induced models. Spontaneous models included those animals that naturally developed degenerative disc disease. Animal model of intervertebral disc degeneration is an important path for revealing the pathogenesis of human disc degeneration, and play an important role in testing novel interventions. With recent advances in the relevance of animal models and humans, it has a great prospect in study of human disc degeneration.

  13. Chemical derivatization of compact disc polycarbonate surfaces for SNPs detection.

    PubMed

    Bañuls, María-José; García-Piñón, Francisco; Puchades, Rosa; Maquieira, Angel

    2008-03-01

    Compact discs have been proposed as an efficient analytical platform, with potential to develop high-throughput affinity assays for genomics, proteomics, clinics, and health monitoring. Chemical derivatization of CD surfaces is one of the keys to developing highly efficient microarraying-based assays on discs. Approaches for mild chemical modification of polycarbonate (PC) disc surface based on nitration, reduction, and chloromethylation reactions have been developed. Derivatized surfaces as amino and thiol are obtained for PC, maintaining unchanged the mechanical and optical properties of the discs. Studies of covalent attachment of oligonucleotide probes (5' Cy5-labeled, 3' NH 2-ended) on the modified surfaces have been performed to develop microarraying assays based on hybridization of cDNA strands and single nucleotide polymorphism discrimination (SNPs). A demonstration of the applicability to the compact disc audio/video technology for its use as analytical system is performed, including the employment of a commercial CD player to read the results on disc.

  14. Disc in Flames: Roles of TNF-α and IL-1β in Intervertebral Disc Degeneration

    PubMed Central

    Johnson, Zariel I.; Schoepflin, Zachary R.; Choi, Hyowon; Shapiro, Irving M.; Risbud, Makarand V.

    2016-01-01

    The intervertebral disc is an important mechanical structure that allows range of motion of the spinal column. Degeneration of the intervertebral disc, incited by aging, traumatic insult, genetic predisposition, or other factors, is often defined by functional and structural changes in the tissue, including excessive breakdown of the extracellular matrix, increased disc cell senescence and death, and compromised biomechanical function of the tissue. Intervertebral disc degeneration is strongly correlated with low back pain, which is a highly prevalent and costly condition, significantly contributing to loss in productivity and health care costs. Disc degeneration is a chronic, progressive condition, and current therapies are limited and often focused on symptomatic pain relief rather than curtailing the progression of the disease. Inflammatory processes, exacerbated by cytokines TNF-α and IL-1β are believed to be key mediators of disc degeneration and low back pain. In this review, we describe the contributions of TNF-α and IL-1β to changes seen during disc degeneration at the cellular and tissue level, new evidence suggesting a link between infection of the spine and low back pain, and the emerging therapeutic modalities aimed at combating these processes. PMID:26388614

  15. Fluid-structure interaction and structural analyses using a comprehensive mitral valve model with 3D chordal structure.

    PubMed

    Toma, Milan; Einstein, Daniel R; Bloodworth, Charles H; Cochran, Richard P; Yoganathan, Ajit P; Kunzelman, Karyn S

    2016-06-25

    Over the years, three-dimensional models of the mitral valve have generally been organized around a simplified anatomy. Leaflets have been typically modeled as membranes, tethered to discrete chordae typically modeled as one-dimensional, non-linear cables. Yet, recent, high-resolution medical images have revealed that there is no clear boundary between the chordae and the leaflets. In fact, the mitral valve has been revealed to be more of a webbed structure whose architecture is continuous with the chordae and their extensions into the leaflets. Such detailed images can serve as the basis of anatomically accurate, subject-specific models, wherein the entire valve is modeled with solid elements that more faithfully represent the chordae, the leaflets, and the transition between the two. These models have the potential to enhance our understanding of mitral valve mechanics and to re-examine the role of the mitral valve chordae, which heretofore have been considered to be 'invisible' to the fluid and to be of secondary importance to the leaflets. However, these new models also require a rethinking of modeling assumptions. In this study, we examine the conventional practice of loading the leaflets only and not the chordae in order to study the structural response of the mitral valve apparatus. Specifically, we demonstrate that fully resolved 3D models of the mitral valve require a fluid-structure interaction analysis to correctly load the valve even in the case of quasi-static mechanics. While a fluid-structure interaction mode is still more computationally expensive than a structural-only model, we also show that advances in GPU computing have made such models tractable. Copyright © 2016 John Wiley & Sons, Ltd.

  16. Functional Mitral Regurgitation: Appraising the Evidence Behind Recommended Treatment Strategies.

    PubMed

    Samad, Zainab; Velazquez, Eric J

    2016-12-01

    Functional mitral regurgitation (MR) is the most common type of MR encountered in clinical practice. Because the disease arises from the ventricular aspect of the mitral valve apparatus, treatment therapies are less defined and outcomes are poor. In this review, the state of evidence for medical and surgical therapy in functional MR is appraised. Future directions for research in this area are also defined.

  17. Single-Suture Neochorda-Folding Plasty for Mitral Regurgitation

    PubMed Central

    Park, Jong Myung; Je, Hyung Gon; Lee, Sang Kwon

    2016-01-01

    The single-suture neochorda-folding plasty technique is a modification of existing mitral valve repair techniques. In the authors’ experience, its simplicity, reliability, and versatility make it a useful technique for mitral valve repair, especially when a minimally invasive approach is used. PMID:26889453

  18. Myxomatous Mitral Valve with Prolapse and Flail Scallop

    PubMed Central

    Fan, Jerry; Timbrook, Alexa; Said, Sarmad; Babar, Kamran; Teleb, Mohamed; Mukherjee, Debabrata; Abbas, Aamer

    2016-01-01

    Summary Background Myxomatous mitral valve with prolapse are classically seen with abnormal leaflet apposition during contraction of the heart. Hemodynamic disorders can result from eccentric mitral regurgitation usually caused by chordae tendinae rupture or papillary muscle dysfunction. Echocardiography is the gold standard for evaluation of leaflet flail and prolapse due to high sensitivity and specificity. Though most mitral valve prolapse are asymptomatic those that cause severe regurgitation need emergent surgical intervention to prevent disease progression. Case Report We report a 54 year old Hispanic male who presented with progressively worsening dyspnea and palpitations. Initial evaluation was significant for atrial fibrillation on electrocardiogram with subsequent echocardiography revealing myxomatous mitral valve with prolapse. Following surgical repair of the mitral valve, the dyspnea and palpitations resolved. Conclusions Mitral valve prolapse is a common valvular abnormality but the pathogenic cause of myxomatous valves has not been elucidated. Several theories describe multiple superfamilies of proteins to be involved in the process. Proper identification of these severe mitral regurgitation due to these disease valves will help relieve symptomatic mitral valve prolapse patients. PMID:27279924

  19. Echocardiography in Transcatheter Aortic Valve Implantation and Mitral Valve Clip

    PubMed Central

    Luo, Huai

    2012-01-01

    Transcatheter aortic valve implantation and transcatheter mitral valve repair (MitraClip) procedures have been performed worldwide. In this paper, we review the use of two-dimensional and three-dimensional transesophageal echo for guiding transcatheter aortic valve replacement and mitral valve repair. PMID:23019387

  20. Temporomandibular joint loads in subjects with and without disc displacement

    PubMed Central

    Iwasaki, Laura R.; Crosby, Michael J.; Gonzalez, Yoly; McCall, Willard D.; Marx, David B.; Ohrbach, Richard; Nickel, Jeffrey C.

    2009-01-01

    The likelihood of development of degenerative joint disease (DJD) of the temporomandibular joint (TMJ) is related to the integrity of the TMJ disc. Predilection for mechanical failure of the TMJ disc may reflect inter-individual differences in TMJ loads. Nine females and eight males in each of normal TMJ disc position and bilateral disc displacement diagnostic groups consented to participate in our study. Disc position was determined by bilateral magnetic resonance images of the joints. Three-dimensional (3D) anatomical geometry of each subject was used in a validated computer-assisted numerical model to calculate ipsilateral and contralateral TMJ loads for a range of biting positions (incisor, canine, molar) and angles (1–13). Each TMJ load was a resultant vector at the anterosuperior-most mediolateral midpoint on the condyle and characterized in terms of magnitude and 3D orientation. Analysis of variance (ANOVA) was used to test for effects of biting position and angle on TMJ loads. Mean TMJ loads in subjects with disc displacement were 9.5–69% higher than in subjects with normal disc position. During canine biting, TMJ loads in subjects with disc displacement were 43% (ipsilateral condyle,p=0.029) and 49% (contralateral condyle,p=0.015) higher on average than in subjects with normal disc position. Biting angle effects showed that laterally directed forces on the dentition produced ipsilateral joint loads, which on average were 69% higher (p=0.002) compared to individuals with normal TMJ disc position. The data reported here describe large differences in TMJ loads between individuals with disc displacement and normal disc position. The results support future investigations of inter-individual differences in joint mechanics as a variable in the development of DJD of the TMJ. PMID:20890385

  1. Changes in gene expression and protein distribution at different stages of mechanically induced disc degeneration--an in vivo study on the New Zealand white rabbit.

    PubMed

    Omlor, Georg W; Lorenz, Helga; Engelleiter, Karl; Richter, Wiltrud; Carstens, Claus; Kroeber, Markus W; Guehring, Thorsten

    2006-03-01

    The objective of the study was to improve the biological understanding of degenerative disc disease using a rabbit model in which different stages of disc degeneration are induced by variation of the duration of loading with an external compression-device applying 2.4 MPa. Gene expression and protein distribution were analyzed in controls and after 1, 28, and 56 days of hyperphysiologic loading. To evaluate extracellular matrix genes, quantitative real-time reverse-transcriptase polymerase chain reaction was applied for collagen I, collagen II, biglycan, decorin, fibromodulin, fibronectin, aggrecan, and osteonectin. As representatives of catabolic, anticatabolic, and anabolic factors, matrix metalloproteinase-13 (MMP-13), tissue inhibitor of matrix metalloproteinase-1 (TIMP-1), and bone morphogenetic protein-2 (BMP-2) were chosen. To evaluate protein distribution, immunohistochemistry was performed for collagen I, collagen II, and BMP-2/4. Matrix gene expression was characterized by two major developments: collagen I and II, biglycan, and decorin showed early elevation followed by later downregulation to control levels, whereas fibromodulin, fibronectin, aggrecan, and osteonectin showed continuous upregulation or remained at similar levels. Induction of MMP-13 gene expression was found in degenerated discs. TIMP-1 and BMP-2 were elevated immediately after hyperphysiologic loading and presented highest levels in the 56-day group. Immunohistochemistry showed less collagen II and BMP-2/4 positive cells after compression. In conclusion, elevated matrix gene expression represents an early cellular response to hyperphysiologic loading. As degeneration progresses, some matrix genes increase upregulation, whereas others start downregulation. Continuous upregulation of catabolic, anticatabolic, and anabolic factors indicates their important role in the degeneration process. Copyright 2005 Orthopaedic Research Society.

  2. Mitral-valve repair versus replacement for severe ischemic mitral regurgitation.

    PubMed

    Acker, Michael A; Parides, Michael K; Perrault, Louis P; Moskowitz, Alan J; Gelijns, Annetine C; Voisine, Pierre; Smith, Peter K; Hung, Judy W; Blackstone, Eugene H; Puskas, John D; Argenziano, Michael; Gammie, James S; Mack, Michael; Ascheim, Deborah D; Bagiella, Emilia; Moquete, Ellen G; Ferguson, T Bruce; Horvath, Keith A; Geller, Nancy L; Miller, Marissa A; Woo, Y Joseph; D'Alessandro, David A; Ailawadi, Gorav; Dagenais, Francois; Gardner, Timothy J; O'Gara, Patrick T; Michler, Robert E; Kron, Irving L

    2014-01-02

    Ischemic mitral regurgitation is associated with a substantial risk of death. Practice guidelines recommend surgery for patients with a severe form of this condition but acknowledge that the supporting evidence for repair or replacement is limited. We randomly assigned 251 patients with severe ischemic mitral regurgitation to undergo either mitral-valve repair or chordal-sparing replacement in order to evaluate efficacy and safety. The primary end point was the left ventricular end-systolic volume index (LVESVI) at 12 months, as assessed with the use of a Wilcoxon rank-sum test in which deaths were categorized below the lowest LVESVI rank. At 12 months, the mean LVESVI among surviving patients was 54.6±25.0 ml per square meter of body-surface area in the repair group and 60.7±31.5 ml per square meter in the replacement group (mean change from baseline, -6.6 and -6.8 ml per square meter, respectively). The rate of death was 14.3% in the repair group and 17.6% in the replacement group (hazard ratio with repair, 0.79; 95% confidence interval, 0.42 to 1.47; P=0.45 by the log-rank test). There was no significant between-group difference in LVESVI after adjustment for death (z score, 1.33; P=0.18). The rate of moderate or severe recurrence of mitral regurgitation at 12 months was higher in the repair group than in the replacement group (32.6% vs. 2.3%, P<0.001). There were no significant between-group differences in the rate of a composite of major adverse cardiac or cerebrovascular events, in functional status, or in quality of life at 12 months. We observed no significant difference in left ventricular reverse remodeling or survival at 12 months between patients who underwent mitral-valve repair and those who underwent mitral-valve replacement. Replacement provided a more durable correction of mitral regurgitation, but there was no significant between-group difference in clinical outcomes. (Funded by the National Institutes of Health and the Canadian Institutes of

  3. A Rare Case of Mitral Valve Prolapse in Endomyocardial Fibrosis.

    PubMed

    Xavier, Joseph; Haranal, Maruti Yamanappa; Reddy, Shashidhar Ranga; Suryaprakash, Sharadaprasad

    2016-09-01

    Mitral valve prolapse in endomyocardial fibrosis (EMF) is an unusual entity. Literature search reveals only 1 report of mitral valve prolapse assosiated with EMF. A 32-year-old woman, of African origin, who presented with features of right heart failure, was diagnosed to have mitral valve prolapse of rheumatic origin with severe mitral regurgitation and severe pulmonary hypertension (PAH). Intraoperative findings lead to the diagnosis of EMF. We report this rare case of mitral valve prolapse in EMF, in a geographical area where rheumatic heart disease is endemic, to showcase how a rare manifestation of EMF can be misdiagnosed as that of rheumatic heart disease. Copyright © 2016 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

  4. Multiple purpose simulator using a natural porcine mitral valve.

    PubMed

    Arita, Makoto; Tono, Sumihiro; Kasegawa, Hitoshi; Umezu, Mitsuo

    2004-12-01

    An in vitro pulsatile simulator with a porcine mitral valve was developed in order to simulate physiologic and diseased mitral valve conditions. Evaluation of these conditions was conducted from a hydrodynamic and annulus behavior point of view. We found it possible to simulate mild "mitral valve prolapse" and to obtain quantitative data related to the condition. The diseased condition produced a 40% greater regurgitant volume than that observed under the normal condition (p < 0.0001). Regarding the leakage volume, the diseased condition exhibited about 2.6 times more leakage than the normal condition. The mitral valve simulator proposed in this study is considered fairly stable with respect to both hemodynamics and the behavior of the annulus, and it is an adequate simulator for modeling various types of normal and diseased mitral valve conditions.

  5. Percutaneous mitral valve repair with MitraClip.

    PubMed

    Cilingiroğlu, Mehmet; Salinger, Michael

    2012-03-01

    Over the last decade, several technologies have been developed for percutaneous repair of the mitral valve for patients with severe mitral regurgitation (MR) and at high-risk for the traditional open-heart mitral valve repair or replacement. Among them, MitraClip has emerged as the only clinically safe and effective method for percutaneous mitral valve repair. It is adapted from the surgical technique that was initially described by Dr. Alfieri and his group by placement of a suture approximating the edges of the mitral leaflets at the origin of the MR jet, leading to creation of so-called bow-tie or double orifice with significant reduction in the MR jet. Here, we review the details of the technology, its procedural perspective as well as currently available data for its safety and effectiveness on a case-based report.

  6. Congenital mitral valve lesions : Correlation between morphology and imaging

    PubMed Central

    Remenyi, Bo; Gentles, Tom L

    2012-01-01

    Congenital malformations of the mitral valve are often complex and affect multiple segments of the valve apparatus. They may occur in isolation or in association with other congenital heart defects. The majority of mitral valve malformations are not simply classified, and descriptive terms with historical significance (parachute, mitral, or arcade) often lack the specificity that cardiac surgeons demand as part of preoperative echocardiographic morphological assessment. This paper examines the strengths and limitations of commonly used descriptions and classification systems of congenitally malformed mitral valves. It correlates pathological, surgical, and echocardiographic findings. Finally, it makes recommendations for the systematic evaluation of the congenitally malformed mitral valve using segmental echocardiographic analysis to assist precise communication and optimal surgical management. PMID:22529594

  7. Comparison of viscoelastic properties of suture versus porcine mitral valve chordae tendineae.

    PubMed

    Cochran, R P; Kunzelman, K S

    1991-12-01

    Recent reports have advocated the use of polytetrafluoroethylene (PTFE) suture for replacement or reinforcement of ruptured or elongated mitral valve chordae tendineae. The mechanical properties of PTFE (Gore-Tex) and other sutures were determined and compared to those of porcine mitral valve chordae. The results were analyzed to assess how closely chordal mechanical function may be simulated by synthetic suture materials. Chordae tendineae and suture samples were tested in uniaxial tension using an INSTRON Model 1000 at strain rates of 5 and 10 mm/min. The stress (g/mm2) was plotted versus strain, and the elastic modulus determined as the slope of the curve. Chordae tendineae exhibited a nonlinear viscoelastic stress/strain behavior. The elastic modulus of both suture types tested was significantly higher than that of the chordae. However, the PTFE suture did exhibit some viscoelastic characteristics (hysteresis and creep) that begin to approach the chordal behavior. Chordal viscoelastic behavior results from the inherent composite structure (collagen, elastin, endothelium, water, and ground substance). As yet, no synthetic materials are able to imitate this behavior with the appropriate tensile strength and fatigue resistant characteristics. At present, PTFE appears to be the best synthetic alternative for chordal replacement, due to its limited viscoelastic capabilities. Nevertheless, the need to more nearly approximate the mechanical behavior of mitral valve chordae tendineae with synthetic material warrants further investigation.

  8. [Impact of mitral annuloplasty combined with surgical revascularization in ischemic mitral regurgitation].

    PubMed

    Tribak, M; Konaté, M; Ould Hbib, B; Konan, P; Mahfoudi, L; Hassani, A El; Daouda, A; Lachhab, F; Bendagha, N; Soufiani, A; Fila, J; Maghraoui, S; Bensouda, A; Marmade, L; Moughil, S

    2017-08-08

    Ischemic Mitral Regurgitation (IMR) is a serious complication of coronary artery disease and is associated with a poor prognosis. The optimal surgical treatment of IMR involves controversies in its indications and modalities. To determine whether mitral annuloplasty associated with surgical revascularization improved short and mid terms outcomes compared with revascularization alone in patients with IMR. Between January 2007 and January 2011, 81 patients operated on Department of Cardiovascular Surgery "B" were included in this study divided into 3 groups. Group 1: 28 patients with IMR had mitral valve surgery associated with surgical revascularization. Group 2: 26 patients with IMR had surgical revascularization without mitral valve surgery. Group 3: 27 patients without IMR had isolated revascularization. Clinical end-points were operative mortality, late mortality, postoperative functional status (NYHA), and the Effective Regurgitant Orifice (ERO) at last follow-up. The mean follow-up was 5 years for groups 1 and 2 and 4 years for group 3. There was no difference between the 3 groups regarding age, sex, cardiovascular risk factors, and extension of coronary artery disease. The Left Ventricle End Diastolic Diameter (LVEDD) and the Left Ventricle Ejection Fraction (LVEF) were slightly different. Late and operative mortality were higher in group 2 compared to groups 1 and 3. Postoperative functional status (NYHA) improved both in groups 1 and 2. In group 1, there was a decrease in ERO. Mitral annuloplasty combined to revascularization improves symptoms, postoperative ERO and short- and mid-term survival compared with revascularization alone. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  9. Parachute mitral valve: morphologic descriptors, associated lesions, and outcomes after biventricular repair.

    PubMed

    Marino, Bradley S; Kruge, Lydia E; Cho, Catherine J; Tomlinson, Ryan S; Shera, David; Weinberg, Paul M; Gaynor, J William; Rychik, Jack

    2009-02-01

    In "true" parachute mitral valve, mitral valve chordae insert into one papillary muscle. In parachute-like asymmetric mitral valve, most or all chordal attachments are to one papillary muscle. This study compared morphologic features, associated lesions, and palliation strategies of the two parachute mitral valve and dominant papillary muscle types and examined interventions and midterm outcomes in patients with biventricular circulation. Echocardiography and autopsy databases were reviewed to identify patients with "true" parachute mitral valve or parachute-like asymmetric mitral valve from January 1987 to January 2006. Predictors of palliation strategy in the entire cohort, mitral stenosis on initial echocardiogram, and mortality in the biventricular cohort were determined with logistic regression. Eighty-six patients with "true" parachute mitral valve (n = 49) or parachute-like asymmetric mitral valve (n = 37) were identified. Chordal attachments to the posteromedial papillary muscle were more common (73%). The presence "true" parachute mitral valve (P = .008), hypoplastic left ventricle (P < .001), and two or more left-sided obstructive lesions (P = .002) predicted univentricular palliation. Among 49 patients maintaining biventricular circulation at follow-up, 8 died median follow-up 6.4 years (7 days-17.8 years). Multivariate analysis revealed that "true" parachute mitral valve was associated with mitral stenosis on initial echocardiogram (P = .03), and "true" parachute mitral valve (P = .04) and conotruncal anomalies (P = .0003) were associated with mortality. Progressive mitral stenosis was found in 11 patients; 2 underwent mitral valve interventions, and 1 died. Nearly two thirds of this parachute mitral valve cohort underwent biventricular palliation. Some progression of mitral stenosis occurred, although mitral valve intervention was rare. "True" parachute mitral valve was associated with mitral stenosis on initial echocardiogram. "True" parachute mitral

  10. [Ventricular and myocardial function in mitral regurgitation (author's transl)].

    PubMed

    Dübbers, H W; Neuhaus, K L; Spiller, P; Tebbe, U

    1979-07-01

    Left ventricular and myocardial performance were analyzed in 9 patients with chronic volume overload by mitral regurgitation from biplane cineventriculograms, simultaneous pressure recordings and cardiac output (thermodilution method) determinations. In spite of a considerable regurgitant fraction (49 +/- 17% of total stroke volume) cardiac index on the average is normal (CI = 3.3 +/- 0.7 l . min-1). The main compensatory mechanism to maintain cardiac ouput in hypertorphy (WED = 1.1 +/- 0.2 cm; LVMI = 216 +/- 62 g . m-2; LVMI/EDVI = 1.3 +/- 0.3 g . ml-1) and dilatation (EDVI = 163 +/- 37 ml . m-2). An increase of preload is of minor importance (PLVED = 15 +/- 7 mmHg; sigma ED = (40 +/- 19) x 10(3) dyn . cm-2). Left ventricular enlargement and wall mass are related to the degree of clinical heart failure (NYHA). Enddiastolic volume on the average is more increased than total stroke volume (89 +/- 31 ml . m-2). Ejection fraction (EF = 54 +/- 7%) was depressed despite a normal afterload (sigma tej = (171 +/- 37 x 10(3) dyn. cm-2; sigma max = (247 +/- 48 x 10(3) dyn . cm-2). The reduced ejection fraction and diminished myocardial power are related to an impairment of myocardial function (VMW . sigma tej = (83 +/- 39) x 10(3) dyn . cm-2 . s-1; VMW . sigma tej/ln sigma ED = 7.9 +/- 3.6 x 10(3) dyn . cm-2 . s-1). In comparable degrees of heart failure myocardial function is more compromised in patients with mitral than with aortic regurgitation.

  11. Porcine mitral valve interstitial cells in culture.

    PubMed

    Lester, W; Rosenthal, A; Granton, B; Gotlieb, A I

    1988-11-01

    There are connective tissue cells present within the interstitium of the heart valves. This study was designed to isolate and characterize mitral valve interstitial cells from the anterior leaflet of the mitral valve. Explants obtained from the distal part of the leaflet, having been scraped free of surface endocardial cells, were incubated in medium 199 supplemented with 10% fetal bovine serum. Cells grew out of the explant after 3 to 5 days and by 3 weeks these cells were harvested and passaged. Passages 1 to 22 were characterized in several explant sets. The cells showed a growth pattern reminiscent of fibroblasts. Growth was dependent on serum concentration. Cytoskeletal localization of actin and myosin showed prominent stress fibers. Ultrastructural studies showed many elongated cells with prominent stress fibers and some gap junctions and few adherens junctions. There were as well cells with fewer stress fibers containing prominent Golgi complex and dilated endoplasmic reticulum. In the multilayered superconfluent cultures, the former cells tended to be on the substratum of the dish or surface of the multilayered culture, whereas the latter was generally located within the layer of cells. Extracellular matrix was prominent in superconfluent cultures, often within the layers as well. Labeling of the cells with antibody HHF 35 (Tsukada T, Tippens D, Gordon D, Ross R, Gown AM: Am J Pathol 126:51, 1987), which recognizes smooth muscle cell actin, showed prominent staining of the elongated stress fiber-containing cells and much less in the secretory type cells. These studies show that interstitial mitral valve cells can be grown in culture and that either two different cell types or one cell type with two phenotypic expressions is present in culture.

  12. Structures induced by companions in galactic discs

    NASA Astrophysics Data System (ADS)

    Kyziropoulos, P. E.; Efthymiopoulos, C.; Gravvanis, G. A.; Patsis, P. A.

    2016-12-01

    Using N-body simulations, we study the structures induced on a galactic disc by repeated flybys of a companion in decaying eccentric orbit around the disc. Our system is composed of a stellar disc, bulge and live dark matter halo, and we study the system's dynamical response to a sequence of a companion's flybys, when we vary (i) the disc's temperature (parametrized by Toomre's Q-parameter) and (ii) the companion's mass and initial orbit. We use a new 3D Cartesian grid code: MAIN (Mesh-adaptive Approximate Inverse N-body solver). The main features of MAIN are reviewed, with emphasis on the use of a new Symmetric Factored Approximate Sparse Inverse matrix in conjunction with the multigrid method that allows the efficient solution of Poisson's equation in three space variables. We find that (i) companions need to be assigned initial masses in a rather narrow window of values in order to produce significant and more long-standing non-axisymmetric structures (bars and spirals) in the main galaxy's disc by the repeated flyby mechanism. (ii) A crucial phenomenon is the antagonism between companion-excited and self-excited modes on the disc. Values of Q > 1.5 are needed in order to allow for the growth of the companion-excited modes to prevail over the growth of the disc's self-excited modes. (iii) We give evidence that the companion-induced spiral structure is best represented by a density wave with pattern speed nearly constant in a region extending from the inner Lindblad resonance to a radius close to, but inside, corotation.

  13. Multi-Scale Biomechanical Remodeling in Aging and Genetic Mutant Murine Mitral Valve Leaflets: Insights into Marfan Syndrome

    PubMed Central

    Gould, Russell A.; Sinha, Ravi; Aziz, Hamza; Rouf, Rosanne; Dietz, Harry C.; Judge, Daniel P.; Butcher, Jonathan

    2012-01-01

    Mitral valve degeneration is a key component of the pathophysiology of Marfan syndrome. The biomechanical consequences of aging and genetic mutation in mitral valves are poorly understood because of limited tools to study this in mouse models. Our aim was to determine the global biomechanical and local cell-matrix deformation relationships in the aging and Marfan related Fbn1 mutated murine mitral valve. To conduct this investigation, a novel stretching apparatus and gripping method was implemented to directly quantify both global tissue biomechanics and local cellular deformation and matrix fiber realignment in murine mitral valves. Excised mitral valve leaflets from wild-type and Fbn1 mutant mice from 2 weeks to 10 months in age were tested in circumferential orientation under continuous laser optical imaging. Mouse mitral valves stiffen with age, correlating with increases in collagen fraction and matrix fiber alignment. Fbn1 mutation resulted in significantly more compliant valves (modulus 1.34±0.12 vs. 2.51±0.31 MPa, respectively, P<.01) at 4 months, corresponding with an increase in proportion of GAGs and decrease in elastin fraction. Local cellular deformation and fiber alignment change linearly with global tissue stretch, and these slopes become more extreme with aging. In comparison, Fbn1 mutated valves have decoupled cellular deformation and fiber alignment with tissue stretch. Taken together, quantitative understanding of multi-scale murine planar tissue biomechanics is essential for establishing consequences of aging and genetic mutations. Decoupling of local cell-matrix deformation kinematics with global tissue stretch may be an important mechanism of normal and pathological biomechanical remodeling in valves. PMID:22984535

  14. Kozai-Lidov disc instability

    NASA Astrophysics Data System (ADS)

    Lubow, Stephen H.; Ogilvie, Gordon I.

    2017-08-01

    Recent results by Martin et al. showed in 3D smoothed particle hydrodynamics simulations that tilted discs in binary systems can be unstable to the development of global, damped Kozai-Lidov (KL) oscillations in which the discs exchange tilt for eccentricity. We investigate the linear stability of KL modes for tilted inviscid discs under the approximations that the disc eccentricity is small and the disc remains flat. By using 1D equations, we are able to probe regimes of large ratios of outer to inner disc edge radii that are realistic for binary systems of hundreds of astronomical unit separations and are not easily probed by multidimensional simulations. For order unity binary mass ratios, KL instability is possible for a window of disc aspect ratios H/r in the outer parts of a disc that roughly scale as (nb/n)2 ≲ H/r ≲ nb/n, for binary orbital frequency nb and orbital frequency n at the disc outer edge. We present a framework for understanding the zones of instability based on the determination of branches of marginally unstable modes. In general, multiple growing eccentric KL modes can be present in a disc. Coplanar apsidal-nodal precession resonances delineate instability branches. We determine the range of tilt angles for unstable modes as a function of disc aspect ratio. Unlike the KL instability for free particles that involves a critical (minimum) tilt angle, disc instability is possible for any non-zero tilt angle depending on the disc aspect ratio.

  15. The Galactic stellar disc

    NASA Astrophysics Data System (ADS)

    Feltzing, S.; Bensby, T.

    2008-12-01

    The study of the Milky Way stellar discs in the context of galaxy formation is discussed. In particular, we explore the properties of the Milky Way disc using a new sample of about 550 dwarf stars for which we have recently obtained elemental abundances and ages based on high-resolution spectroscopy. For all the stars we also have full kinematic information as well as information about their stellar orbits. We confirm results from previous studies that the thin and the thick discs have distinct abundance patterns. But we also explore a larger range of orbital parameters than what has been possible in our previous studies. Several new results are presented. We find that stars that reach high above the Galactic plane and have eccentric orbits show remarkably tight abundance trends. This implies that these stars formed out of well-mixed gas that had been homogenized over large volumes. We find some evidence that suggest that the event that most likely caused the heating of this stellar population happened a few billion years ago. Through a simple, kinematic exploration of stars with super-solar [Fe/H], we show that the solar neighbourhood contains metal-rich, high velocity stars that are very likely associated with the thick disc. Additionally, the HR1614 moving group and the Hercules and Arcturus stellar streams are discussed and it is concluded that, probably, a large fraction of the groups and streams so far identified in the disc are the result of evolution and interactions within the stellar disc rather than being dissolved stellar clusters or engulfed dwarf galaxies. This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile. Also based on observations collected at the Nordic Optical Telescope on La Palma, Spain, and at the European Southern Observatories on La Silla and Paranal, Chile, Proposals no. 65.L-0019(B), 67.B-0108(B), 69.B-0277.

  16. Finite element modeling of mitral leaflet tissue using a layered shell approximation

    PubMed Central

    Ratcliffe, Mark B.; Guccione, Julius M.

    2012-01-01

    The current study presents a finite element model of mitral leaflet tissue, which incorporates the anisotropic material response and approximates the layered structure. First, continuum mechanics and the theory of layered composites are used to develop an analytical representation of membrane stress in the leaflet material. This is done with an existing anisotropic constitutive law from literature. Then, the concept is implemented in a finite element (FE) model by overlapping and merging two layers of transversely isotropic membrane elements in LS-DYNA, which homogenizes the response. The FE model is then used to simulate various biaxial extension tests and out-of-plane pressure loading. Both the analytical and FE model show good agreement with experimental biaxial extension data, and show good mutual agreement. This confirms that the layered composite approximation presented in the current study is able to capture the exponential stiffening seen in both the circumferential and radial directions of mitral leaflets. PMID:22971896

  17. Simulation Based Design and Evaluation of a Transcatheter Mitral Heart Valve Frame

    PubMed Central

    Young, Melissa; Erdemir, Ahmet; Stucke, Samantha; Klatte, Ryan; Davis, Brian; Navia, Jose L.

    2013-01-01

    In certain populations, open heart surgery to replace a diseased mitral valve is not an option, leaving percutaneous delivery a viable alternative. However, a surgical transcatheter based delivery of a metallic support frame incorporating a tissue derived valve puts considerable constraints on device specifications. Expansion to a large diameter from the catheter diameter without mechanical fracture involves advanced device design and appropriate material processing and selection. In this study, a new frame concept is presented with a desirable feature that incorporates wings that protrude during expansion to establish adequate fixation. Expansion characteristics of the design in relation to annulus fixation were quantified through finite element analysis predictions of the frame wing span and angles. Computational modeling and simulation was used to identify many favorable design features for the transcatheter mitral valve frame and obtain desired expansion diameters (35–45mm), acceptable radial stiffness (2.7N/mm), and ensure limited risk of failure based on predicted plastic deformations. PMID:23372624

  18. [Mitral valve replacement for four times with three kinds of prosthetic valve dysfunction].

    PubMed

    Kojima, Nozomi; Ito, Satoshi; Sakano, Yasuhito; Konishi, Hiroaki; Misawa, Yoshio

    2011-03-01

    There are 2 major types of prosthetic valve replacement complications; structural valvular deterioration and nonstructural dysfunction. Nonstructural dysfunction includes valve thrombosis, paravalvular leak, prosthetic valve endocarditis and bleeding event. Primary tissue failure is the most common reason for mitral valve replacement (MVR) with tissue valves, and paravalvular leak is also a common factor of MVR in repeated MVR cases. We report a case of a woman who has undergone MVR for four times. She underwent the 1st MVR with a tissue valve 19 years ago because of mitral valve regurgitation. Nine years after the initial operation, structural valvular deterioration developed and she underwent the 2nd MVR with a mechanical prosthesis. Two years after the 2nd operation, she underwent the 3rd MVR because of repeated prosthetic valve thrombosis. Paravalvular leak was recognized 8 years after the 3rd operation and she underwent the 4th MVR. Her postoperative course was uneventful.

  19. Libman-Sacks Endocarditis with Unusual Large Size Vegetation Involving the Mitral Valve.

    PubMed

    Bani Hani, Amjad; Abu-Abeeleh, Mahmoud; Al Kharabsheh, Murad M; Qabba'ah, Lubaba

    2016-12-21

    Antiphospholipid syndrome (APS) is an autoimmune hypercoagulable disorder characterized by thrombophilia, vascular thrombosis, and recurrent abortions associated with persistent antiphospholipid antibodies. APS may exist in its primary form, or more commonly is found to be associated with variety of rheumatic disorders, such as systemic lupus erythematosus. Cardiac involvement is not an uncommon complication in primary antiphospholipid patients. Libman-Sacks lesions are typically small, sessile, and wart-like, varying in size from 1-4 mm. Here we present an unusual case of a 37 year-old pregnant woman who suffered from heart failure associated with primary antiphospholipid syndrome and Libman-Sacks endocarditis, with large vegetations involving the mitral valve. The patient underwent mitral valve replacement with a mechanical prosthesis.

  20. Generating large misalignments in gapped and binary discs

    NASA Astrophysics Data System (ADS)

    Owen, James E.; Lai, Dong

    2017-08-01

    Many protostellar gapped and binary discs show misalignments between their inner and outer discs; in some cases, ∼70° misalignments have been observed. Here, we show that these misalignments can be generated through a secular resonance between the nodal precession of the inner disc and the precession of the gap-opening (stellar or massive planetary) companion. An evolving protostellar system may naturally cross this resonance during its lifetime due to disc dissipation and/or companion migration. If resonance crossing occurs on the right time-scale, of the order of a few million years, characteristic for young protostellar systems, the inner and outer discs can become highly misaligned, with misalignments ≳ 60° typical. When the primary star has a mass of order a solar mass, generating a significant misalignment typically requires the companion to have a mass of ∼0.01-0.1 M⊙ and an orbital separation of tens of astronomical units. The recently observed companion in the cavity of the gapped, highly misaligned system HD 142527 satisfies these requirements, indicating that a previous resonance crossing event misaligned the inner and outer discs. Our scenario for HD 142527's misaligned discs predicts that the companion's orbital plane is aligned with the outer disc's; this prediction should be testable with future observations as the companion's orbit is mapped out. Misalignments observed in several other gapped disc systems could be generated by the same secular resonance mechanism.

  1. Orbital evolution of eccentric planets in radiative discs

    NASA Astrophysics Data System (ADS)

    Bitsch, B.; Kley, W.

    2010-11-01

    Context. With an average eccentricity of about 0.29, the eccentricity distribution of extrasolar planets is markedly different from the solar system. Among other scenarios considered, it has been proposed that eccentricity may grow through planet-disc interaction. Recently, it has been noticed that the thermodynamical state of the disc can significantly influence the migration properties of growing protoplanets. However, the evolution of planetary eccentricity in radiative discs has not been considered yet. Aims: In this paper we study the evolution of planets on eccentric orbits that are embedded in a three-dimensional viscous disc and analyse the disc's effect on the orbital evolution of the planet. Methods: We use the three-dimensional hydrodynamical code NIRVANA that includes full tensor viscosity and implicit radiation transport in the flux-limited diffusion approximation. The code uses the FARGO-algorithm to speed up the simulations. First we measure the torque and power exerted on the planet by the disc for fixed orbits, and then we let the planet start with initial eccentricity and evolve it in the disc. Results: For locally isothermal discs we confirm previous results and find eccentricity damping and inward migration for planetary cores. For low eccentricity (e ⪉ 2 H/r) the damping is exponential, while for higher e it follows dot{e} ∝ e-2. In the case of radiative discs, the planets experience an inward migration as long as its eccentricity lies above a certain threshold. After the damping of eccentricity cores with masses below 33 MEarth begin to migrate outward in radiative discs, while higher mass cores always migrate inward. For all planetary masses studied (up to 200 MEarth) we find eccentricity damping. Conclusions: In viscous discs the orbital eccentricity of embedded planets is damped during the evolution independent of the mass. Hence, planet-disc interaction does not seem to be a viable mechanism to explain the observed high eccentricity of

  2. [Surgical techniques in mitral valve diseases. Reconstruction and/or replacement].

    PubMed

    Noack, T; Mohr, F-W

    2016-02-01

    Mitral valve (MV) disease is one of the most common heart valve diseases. The surgical and interventional treatment for MV disease requires a multidisciplinary approach. For primary mitral valve regurgitation (MVR) surgical MV repair is the treatment of choice, which can be performed with an excellent outcome and long-term survival in reference centers. The surgical technique used for MV repair depends on the pathological mechanism, the morphological dimensions of the MV, the operative risk and the expertise of the cardiac surgeon. The surgical and interventional treatment of secondary MVVR is the subject of on-going discussions. In patients with moderate secondary MVR undergoing coronary artery bypass grafting, concomitant MV repair should be performed. In the presence of severe secondary MR with risk factors for failure of MV repair, patients should consider having MV replacement. In the rare cases of patients presenting with mitral valve stenosis (MVS) MV repair can be considered in young patients and who are most often treated with MV replacement. The choice between biological or mechanical MV replacement depends on the pathophysiology, the comorbidities, the amount of anticoagulation necessary and the age of the patient. New percutaneous techniques for MV replacement offer new treatment options for reoperation in high-risk patients.

  3. Is minimally invasive thoracoscopic surgery the new benchmark for treating mitral valve disease?

    PubMed Central

    Goldstone, Andrew B.

    2016-01-01

    The treatment of mitral valve disease remains dynamic; surgeons and patients must now choose between many different surgical options when addressing mitral regurgitation and mitral stenosis. Notably, advances in imaging and surgical instrumentation allow surgeons to perform less invasive mitral valve surgery that spares the sternum. With favorable long-term data now emerging, we compare the benefits and risks of thoracoscopic mitral valve surgery with that through conventional sternotomy or surgery that is robot-assisted. PMID:27942489

  4. Design concepts in lumbar total disc arthroplasty

    PubMed Central

    Bellini, Chiara M.; Zweig, Thomas; Ferguson, Stephen; Raimondi, Manuela T.; Lamartina, Claudio; Brayda-Bruno, Marco; Fornari, Maurizio

    2008-01-01

    The implantation of lumbar disc prostheses based on different design concepts is widely accepted. This paper reviews currently available literature studies on the biomechanics of TDA in the lumbar spine, and is targeted at the evaluation of possible relationships between the aims of TDA and the geometrical, mechanical and material properties of the various available disc prostheses. Both theoretical and experimental studies were analyzed, by a PUBMED search (performed in February 2007, revised in January 2008), focusing on single level TDA. Both semi-constrained and unconstrained lumbar discs seem to be able to restore nearly physiological IAR locations and ROM values. However, both increased and decreased ROM was stated in some papers, unrelated to the clinical outcome. Segmental lordosis alterations after TDA were reported in most cases, for both constrained and unconstrained disc prostheses. An increase in the load through the facet joints was documented, for both semi-constrained and unconstrained artificial discs, but with some contrasting results. Semi-constrained devices may be able to share a greater part of the load, thus protecting the surrounding biological structure from overloading and possible early degeneration, but may be more susceptible to wear. The next level of development will be the biomechanical integration of compression across the motion segment. All these findings need to be supported by long-term clinical outcome studies. PMID:18946684

  5. Repeat mitral valve replacement: 30-years' experience.

    PubMed

    Expósito, Víctor; García-Camarero, Tamara; Bernal, José M; Arnáiz, Elena; Sarralde, Aurelio; García, Iván; Berrazueta, José R; Revuelta, José M

    2009-08-01

    Prosthetic heart valve dysfunction is an acquired condition that carries a significant risk of emergency surgery. However, the long-term natural history of the condition is not well understood. Between 1974 and 2006, 1535 isolated mitral valve replacements were performed at our hospital (in-hospital mortality 5%). In total, 369 patients needed a second operation (in-hospital mortality 8.1%), while 80 (age 59.8+/-11.4 years) needed a third. The reasons for the third intervention were structural deterioration (67.5%), paravalvular leak (20%) and endocarditis (6.3%). Some 15 patients died in hospital (18.8%). After a mean follow-up period of 17.8 years, 21 patients needed another intervention (i.e., a fourth intervention). The actuarial reoperation-free rate at 20 years was 40.1+/-13.8%. The late mortality rate was 58.5% (18-year survival rate 15.4+/-5.4%). Indications for repeat mitral valve replacement must be judged on an individual basis given the high risk associated with surgery.

  6. Mitral Apparatus Assessment by Delayed Enhancement CMR – Relative Impact of Infarct Distribution on Mitral Regurgitation

    PubMed Central

    Chinitz, Jason S.; Chen, Debbie; Goyal, Parag; Wilson, Sean; Islam, Fahmida; Nguyen, Thanh; Wang, Yi; Hurtado-Rua, Sandra; Simprini, Lauren; Cham, Matthew; Levine, Robert A.; Devereux, Richard B.; Weinsaft, Jonathan W.

    2014-01-01

    Objectives To assess patterns and functional consequences of mitral apparatus infarction after acute MI (AMI). Background The mitral apparatus contains two myocardial components – papillary muscles and the adjacent LV wall. Delayed-enhancement CMR (DE-CMR) enables in-vivo study of inter-relationships and potential contributions of LV wall and papillary muscle infarction (PMI) to mitral regurgitation (MR). Methods Multimodality imaging was performed: CMR was used to assess mitral geometry and infarct pattern, including 3D DE-CMR for PMI. Echocardiography (echo) was used to measure MR. Imaging occurred 27±8 days post-AMI (CMR, echo within 1 day). Results 153 patients with first AMI were studied. PMI was present in 30% (n=46; 72% posteromedial, 39% anterolateral). When stratified by angiographic culprit vessel, PMI occurred in 65% of patients with left circumflex, 48% with right coronary, and only 14% of patients with left anterior descending infarctions (p<0.001). Patients with PMI had more advanced remodeling as measured by LV size and mitral annular diameter (p<0.05). Increased extent of PMI was accompanied by a stepwise increase in mean infarct transmurality within regional LV segments underlying each papillary muscle (p<0.001). Prevalence of lateral wall infarction was 3.0 fold higher among patients with, compared to those without, PMI (65% vs. 22%, p<0.001). Infarct distribution also impacted MR, with greater MR among patients with lateral wall infarction (p=0.002). Conversely, MR severity did not differ based on presence (p=0.19) or extent (p=0.12) of PMI, or by angiographic culprit vessel. In multivariable analysis, lateral wall infarct size (OR=1.20[CI=1.05–1.39], p=0.01) was independently associated with substantial (≥moderate) MR even after controlling for mitral annular (OR=1.22[1.04–1.43], p=0.01) and LV end-diastolic diameter (OR=1.11 [0.99–1.23], p=0.056). Conclusions PMI is common post-AMI, affecting nearly one-third of patients. PMI extent

  7. The debris disc around HIP 17439

    NASA Astrophysics Data System (ADS)

    Schüppler, Christian; Löhne, Torsten; Krivov, Alexander

    2013-07-01

    In the framework of the Herschel Open Time Key Programme DUNES the debris disc around the K2 V star HIP 17439 was observed. In PACS images the disc emission is spatially clearly extended. A simultaneous analysis of photometric observations and radial brightness profiles from the resolved images provides valuable hints for the disc structure. In an analytical model we adopted power laws for the size and radial distribution of the circumstellar dust and tested two different scenarios: (1) a broad dust ring with a radial extent of about 200AU, (2) two independent dust rings separated by a gap of several tens of AU. Both models fit the spectral energy distribution and the radial profiles quite well. In case (1) the parameters found are consistent with dust stemming from an outer planetesimal belt at ~140AU and strong transport mechanisms that drag the particles inward. Model (2) would imply two planetesimal belts, producing a narrow inner and wider outer distribution of dust.

  8. Mitral Valve Surgery: Current Minimally Invasive and Transcatheter Options.

    PubMed

    Ramlawi, Basel; Gammie, James S

    2016-01-01

    The mitral valve is a highly complex structure, the competency and function of which relies on the harmonious action of its component parts. Minimally invasive cardiac surgery (MICS) for mitral valve repair or replacement (MVR/r) has been performed successfully with incremental improvements in techniques over the past decade. These minimally invasive procedures, while attractive to patients and referring physicians, should meet the same high bar for optimal clinical outcomes and long-term durability of valve repair as traditional sternotomy procedures. The majority of MICS MVR/r procedures are performed via a right minithoracotomy approach with direct or camera-assisted visualization, with a minority of centers performing robotic MVR/r. Outcomes with MICS MVR/r have been shown to have similar morbidity and mortality rates as traditional sternotomy MV procedures but with the advantage of reduced transfusions, postoperative atrial fibrillation, and time to recovery. More recently, transcatheter mitral valve repair and replacement (TMVR/r) has become a reality. Percutaneous MV repair technology is currently FDA approved for patients with nonsurgical high-risk degenerative mitral regurgitation. Other TMVR/r technology is at various levels of preclinical and clinical investigation, although these devices are proving to be more challenging compared to transcatheter aortic valve replacement (TAVR) due to the significantly more complex mitral anatomy and the greater heterogeneity of mitral disease requiring treatment. In this article, we review current techniques for MICS MVR/r and upcoming catheter-based therapies for the mitral valve.

  9. Fluid-Structure Interaction Analysis of Ruptured Mitral Chordae Tendineae.

    PubMed

    Toma, Milan; Bloodworth, Charles H; Pierce, Eric L; Einstein, Daniel R; Cochran, Richard P; Yoganathan, Ajit P; Kunzelman, Karyn S

    2017-03-01

    The chordal structure is a part of mitral valve geometry that has been commonly neglected or simplified in computational modeling due to its complexity. However, these simplifications cannot be used when investigating the roles of individual chordae tendineae in mitral valve closure. For the first time, advancements in imaging, computational techniques, and hardware technology make it possible to create models of the mitral valve without simplifications to its complex geometry, and to quickly run validated computer simulations that more realistically capture its function. Such simulations can then be used for a detailed analysis of chordae-related diseases. In this work, a comprehensive model of a subject-specific mitral valve with detailed chordal structure is used to analyze the distinct role played by individual chordae in closure of the mitral valve leaflets. Mitral closure was simulated for 51 possible chordal rupture points. Resultant regurgitant orifice area and strain change in the chordae at the papillary muscle tips were then calculated to examine the role of each ruptured chorda in the mitral valve closure. For certain subclassifications of chordae, regurgitant orifice area was found to trend positively with ruptured chordal diameter, and strain changes correlated negatively with regurgitant orifice area. Further advancements in clinical imaging modalities, coupled with the next generation of computational techniques will enable more physiologically realistic simulations.

  10. Mitral Valve Surgery: Current Minimally Invasive and Transcatheter Options

    PubMed Central

    Ramlawi, Basel; Gammie, James S.

    2016-01-01

    The mitral valve is a highly complex structure, the competency and function of which relies on the harmonious action of its component parts. Minimally invasive cardiac surgery (MICS) for mitral valve repair or replacement (MVR/r) has been performed successfully with incremental improvements in techniques over the past decade. These minimally invasive procedures, while attractive to patients and referring physicians, should meet the same high bar for optimal clinical outcomes and long-term durability of valve repair as traditional sternotomy procedures. The majority of MICS MVR/r procedures are performed via a right minithoracotomy approach with direct or camera-assisted visualization, with a minority of centers performing robotic MVR/r. Outcomes with MICS MVR/r have been shown to have similar morbidity and mortality rates as traditional sternotomy MV procedures but with the advantage of reduced transfusions, postoperative atrial fibrillation, and time to recovery. More recently, transcatheter mitral valve repair and replacement (TMVR/r) has become a reality. Percutaneous MV repair technology is currently FDA approved for patients with nonsurgical high-risk degenerative mitral regurgitation. Other TMVR/r technology is at various levels of preclinical and clinical investigation, although these devices are proving to be more challenging compared to transcatheter aortic valve replacement (TAVR) due to the significantly more complex mitral anatomy and the greater heterogeneity of mitral disease requiring treatment. In this article, we review current techniques for MICS MVR/r and upcoming catheter-based therapies for the mitral valve. PMID:27127558

  11. [Percutaneous mitral commissurotomy using Inoue's balloon during pregnancy].

    PubMed

    Murillo, H; Ayala, F; Badui, E; Almazán, A; Solorio, S; Enciso, R; Madrid, R; Lepe, L; Rangel Abundis, A; Chávez, E

    1996-01-01

    The authors present three cases of pregnant women with symptomatic severe mitral stenosis with a mean age of 28.6 +/- 2.3 years, and during 27.6 +/- 1.52 weeks of pregnancy. Two patients were in class III and one in class IV of the New York Heart Association (NYHA). All patients had a mitral valvular area equal or less than 1 cm2, with a Wilkins score of 7 to 9 and mitral insufficiency grade I in two cases; two, had severe pulmonary arterial hypertension (mean > 50 mm Hg). After Percutaneous Mitral Valvuloplasty (PMV) the mitral valve measured by 2D echocardiography increased form 0.83 +/- 0.2 cm2 to 1.8 +/- 0.15 cm2; the mean transmitral gradient diminished from 13 +/- 3.4 mm Hg to 3.6 +/- 1.15 mm Hg; the degree of mitral insufficiency was no modified in neither case. Hemodynamic results revealed increasing of the mitral valve from 0.83 +/- 0.18 cm2 to 2.23 +/- 0.3 cm2; the mean mitral gradient decreased from 21.6 +/- 9 to 4.3 +/- 0.5 mm Hg; the mean left atrial pressure from 30 +/- 12 to 12.3 +/- 4 mm Hg; the mean pressure of the pulmonary artery diminished suddenly from 44.3 +/- 16 to 25.6 +/- 11 mm Hg. The average fluoroscopic time was 15.3 +/- 3 minutes. There were no complications. The patients were discharged 48 hours after the procedure and continued their pregnancies in class I NYHA, which resolved in a non complicated vaginal delivery with normal products. We conclude that PMV is a safe and useful therapy in pregnant patient with severe mitral stenosis refractory to medical treatment.

  12. Revival of the Jumping Disc

    ERIC Educational Resources Information Center

    Ucke, C.; Schlichting, H-J.

    2009-01-01

    Snap discs made of bimetal have many technical applications as thermostats. Jumping discs are a toy version of such snap discs. Besides giving technical information, we describe physical investigations. We show especially how, through simple measurements and calculations, you can determine the initial speed ([approximately equal to]3.5 m…

  13. The Chemistry of Optical Discs.

    ERIC Educational Resources Information Center

    Birkett, David

    2002-01-01

    Explains the chemistry used in compact discs (CD), digital versatile discs (DVD), and magneto-optical (MO) discs focusing on the steps of initial creation of the mold, the molding of the polycarbonate, the deposition of the reflective layers, the lacquering of the CDs, and the bonding of DVDs. (Contains 15 references.) (YDS)

  14. Revival of the Jumping Disc

    ERIC Educational Resources Information Center

    Ucke, C.; Schlichting, H-J.

    2009-01-01

    Snap discs made of bimetal have many technical applications as thermostats. Jumping discs are a toy version of such snap discs. Besides giving technical information, we describe physical investigations. We show especially how, through simple measurements and calculations, you can determine the initial speed ([approximately equal to]3.5 m…

  15. How do accretion discs break?

    NASA Astrophysics Data System (ADS)

    Dogan, Suzan

    2016-07-01

    Accretion discs are common in binary systems, and they are often found to be misaligned with respect to the binary orbit. The gravitational torque from a companion induces nodal precession in misaligned disc orbits. In this study, we first calculate whether this precession is strong enough to overcome the internal disc torques communicating angular momentum. We compare the disc precession torque with the disc viscous torque to determine whether the disc should warp or break. For typical parameters precession wins: the disc breaks into distinct planes that precess effectively independently. To check our analytical findings, we perform 3D hydrodynamical numerical simulations using the PHANTOM smoothed particle hydrodynamics code, and confirm that disc breaking is widespread and enhances accretion on to the central object. For some inclinations, the disc goes through strong Kozai cycles. Disc breaking promotes markedly enhanced and variable accretion and potentially produces high-energy particles or radiation through shocks. This would have significant implications for all binary systems: e.g. accretion outbursts in X-ray binaries and fuelling supermassive black hole (SMBH) binaries. The behaviour we have discussed in this work is relevant to a variety of astrophysical systems, for example X-ray binaries, where the disc plane may be tilted by radiation warping, SMBH binaries, where accretion of misaligned gas can create effectively random inclinations and protostellar binaries, where a disc may be misaligned by a variety of effects such as binary capture/exchange, accretion after binary formation.

  16. The DISC Quotient

    NASA Astrophysics Data System (ADS)

    Elliott, John R.; Baxter, Stephen

    2012-09-01

    D.I.S.C: Decipherment Impact of a Signal's Content. The authors present a numerical method to characterise the significance of the receipt of a complex and potentially decipherable signal from extraterrestrial intelligence (ETI). The purpose of the scale is to facilitate the public communication of work on any such claimed signal, as such work proceeds, and to assist in its discussion and interpretation. Building on a "position" paper rationale, this paper looks at the DISC quotient proposed and develops the algorithmic steps and comprising measures that form this post detection strategy for information dissemination, based on prior work on message detection, decipherment. As argued, we require a robust and incremental strategy, to disseminate timely, accurate and meaningful information, to the scientific community and the general public, in the event we receive an "alien" signal that displays decipherable information. This post-detection strategy is to serve as a stepwise algorithm for a logical approach to information extraction and a vehicle for sequential information dissemination, to manage societal impact. The "DISC Quotient", which is based on signal analysis processing stages, includes factors based on the signal's data quantity, structure, affinity to known human languages, and likely decipherment times. Comparisons with human and other phenomena are included as a guide to assessing likely societal impact. It is submitted that the development, refinement and implementation of DISC as an integral strategy, during the complex processes involved in post detection and decipherment, is essential if we wish to minimize disruption and optimize dissemination.

  17. Herniated Lumbar Disc

    MedlinePlus

    ... at and just below the waist. A herniated lumbar disc can press on the nerves in the spine and may cause pain, numbness, ... point injections do not help heal a herniated lumbar ... on and irritating the nerves, causing symptoms of pain and weakness. The most ...

  18. The Teddy Bears' Disc.

    ERIC Educational Resources Information Center

    Laurillard, Diana

    1985-01-01

    Reports an evaluation of the Teddy Bear disc, an interactive videodisc developed at the Open University for a second-level course in metallurgy and materials technology. Findings from observation of students utilizing the videodisc are reviewed; successful design features and design problems are considered; and development costs are outlined. (MBR)

  19. Hybrid cervical disc arthroplasty.

    PubMed

    Tu, Tsung-Hsi; Wu, Jau-Ching; Cheng, Henrich; Mummaneni, Praveen V

    2017-01-01

    For patients with multilevel cervical stenosis at nonadjacent segments, one of the traditional approaches has included a multilevel fusion of the abnormal segments as well as the intervening normal segment. In this video we demonstrate an alternative treatment plan with tailored use of a combination of anterior cervical discectomy and fusion (ACDF) and cervical disc arthroplasty (CDA) with an intervening skipped level. The authors present the case of a 72-year-old woman with myeloradiculopathy and a large disc herniation with facet joint degeneration at C3-4 and bulging disc at C5-6. After nonoperative treatment failed, she underwent a single-level ACDF at C3-4 and single-level arthroplasty at C5-6, which successfully relieved her symptoms. No intervention was performed at the normal intervening C4-5 segment. By using ACDF combined with arthroplasty, the authors have avoided a 3-level fusion for this patient and maintained the range of motion of 2 disc levels. The video can be found here: https://youtu.be/OrxcPUBvqLk .

  20. The Teddy Bears' Disc.

    ERIC Educational Resources Information Center

    Laurillard, Diana

    1985-01-01

    Reports an evaluation of the Teddy Bear disc, an interactive videodisc developed at the Open University for a second-level course in metallurgy and materials technology. Findings from observation of students utilizing the videodisc are reviewed; successful design features and design problems are considered; and development costs are outlined. (MBR)

  1. Echocardiographic analysis of a malfunctioning Davila-Sierra mitral valve.

    PubMed

    Tri, Terry B.; Gregoratos, Gabriel

    1981-03-01

    Although the Davila-Sierra mitral valve prosthesis was removed from the market nearly a decade ago, a number of patients still have this valve in place. We recently studied the echocardiographic features of a malfunctioning Davila-Sierra mitral valve prosthesis. Abnormalities that suggested improper functioning of the prosthesis included a markedly delayed poppet opening and an early diastolic hump believed to represent motion of the mitral annulus. Previously described echocardiographic indications of dys-function were not observed in our patient. We report the first known echocardiographic evaluation of a Davila-Sierra prosthesis.

  2. Echocardiographic analysis of a malfunctioning Davila-Sierra mitral valve

    PubMed Central

    Tri, Terry B.; Gregoratos, Gabriel

    1981-01-01

    Although the Davila-Sierra mitral valve prosthesis was removed from the market nearly a decade ago, a number of patients still have this valve in place. We recently studied the echocardiographic features of a malfunctioning Davila-Sierra mitral valve prosthesis. Abnormalities that suggested improper functioning of the prosthesis included a markedly delayed poppet opening and an early diastolic hump believed to represent motion of the mitral annulus. Previously described echocardiographic indications of dys-function were not observed in our patient. We report the first known echocardiographic evaluation of a Davila-Sierra prosthesis. Images PMID:15216230

  3. [A Case of Mitral Valvular Re-repair in a Patient with Hemolytic Anemia after Mitral Valvular Repair].

    PubMed

    Tomino, Mikiko; Miyata, Kazuto; Takeshita, Yuji; Kaneko, Koki; Kanazawa, Hiroko; Uchino, Hiroyuki

    2015-07-01

    A 54-year-old woman was admitted for mitral valvular repair. After folding plasty to A3, a 30 mm Cosgrove-Edwards ring was placed. There was no mitral regurgitation jet observed by transesophageal echocardiography (TEE) during the operation. However, high blood pressure was monitored and treated in the intensive care unit, hemolytic anemia developed, and the serum lactate dehydrogenase level was elevated. Two weeks after the operation, serum lactate dehydrogenase was again elevated. TEE showed mild mitral regurgitation and the regurgitation jet colliding with the annuloplasty ring. Multiple transfusions of red blood cells were required. Repeat surgery was therefore undertaken. Lam and associates previously studying patients on hemolysis after mitral valvular repair noted high grade mitral regurgitation jets fragmented or accelerated. In the present case, mitral regurgitation was mild, but the high velocity and manner of regurgitation (collision with the annuloplasty ring) could cause hemolytic anemia. In the present case, high blood pressure might have caused chordae rupture. Furthermore, a flexible ring, such as the Cosgrove-Edwards ring, is likely to cause hemolytic anemia. As contributing factors to hemolysis after mitral valvular repair, perioperative blood pressure management and type of ring are significant.

  4. Resolution of massive left atrial appendage thrombi with rivaroxaban before balloon mitral commissurotomy in severe mitral stenosis

    PubMed Central

    Li, Yuechun; Lin, Jiafeng; Peng, Chen

    2016-01-01

    Abstract Rationale: Data on nonvitamin K antagonist oral anticoagulant being used for the treatment of LAA thrombi are limited only in nonvalvular atrial fibrillation. There are no data on the antithrombotic efficacy and safety of nonvitamin K antagonist oral anticoagulant in the resolution of left atrial appendage (LAA) thrombi in patients with rheumatic mitral stenosis. Patient concerns: A 49-year-old woman with known rheumatic mitral stenosis and atrial fibrillation was referred for percutaneous transvenous mitral commissurotomy because of progressive dyspnea on exertion over a period of 3 months. Diagnoses: Transesophageal echocardiography (TEE) demonstrated a large LAA thrombus protruding into left atria cavity before the procedure. Interventions: Direct factor Xa (FXa) inhibitor rivaroxaban (20 mg/d) was started for the patient. After 3 weeks of rivaroxaban treatment TEE showed a relevantly decreased thrombus size, and a complete thrombus resolution was achieved after 5 weeks of anticoagulant therapy with the FXa inhibitor. Outcomes: To the best of our knowledge, this is the first documented case of large LAA thrombus resolution with nonvitamin K antagonist oral anticoagulant in severe mitral stenosis, and in which percutaneous transvenous mitral commissurotomy was performed subsequently. Lessons: The report indicated that rivaroxaban could be a therapeutic option for mitral stenosis patients with LAA thrombus. Further study is required before the routine use of rivaroxaban in patients with rheumatic mitral stenosis and atrial fibrillation. PMID:27930571

  5. Study of Effectiveness and Safety of Percutaneous Balloon Mitral Valvulotomy for Treatment of Pregnant Patients with Severe Mitral Stenosis

    PubMed Central

    Joshi, Hasit Sureshbhai; Deshmukh, Jagjeet Kishanrao; Prajapati, Jayesh Somabhai; Sahoo, Sibasis Shahsikant; Vyas, Pooja Maheshbhai

    2015-01-01

    Introduction In pregnant women mitral stenosis is the commonest cardiac valvular lesion. When it is present in majorly severe condition it leads to maternal and fetal morbidity and mortality. In mitral stenosis pregnancy can lead to development of heart failure. Aim To evaluate the safety and efficacy of balloon mitral valvulotomy (BMV) in pregnant females with severe mitral stenosis. Materials and Methods A total of 30 pregnant patients who underwent BMV were included in the study from July 2011 to November 2013. Clinical follow-up during pregnancy was done every 3 months until delivery and after delivery. The mean follow up time after BMV was 6.72±0.56 months. Results From the 30 pregnant females 14 (46.67%) and 16 (53.3%) patients underwent BMV during the third and second trimester of pregnancy respectively. The mean mitral valve area was 0.85+0.16 cm2 before BMV that increased to 1.60+0.27 cm2 (p<0.0001) immediately after BMV. Peak and mean diastolic gradients had decreased significantly within 48 hours after the procedure (p<0.001) but remained very much unchanged at 6.72 month period of follow-up. Two patients had an increase in mitral regurgitation by 2 grades. Conclusion During pregnancy BMV technique is safe and effective in patients with severe mitral stenosis. This results in marked symptomatic relief along with long term maternal and fetal outcomes. PMID:26816932

  6. Percutaneous mitral valve repair with MitraClip for severe functional mitral regurgitation.

    PubMed

    Yeo, Khung Keong; Ding, Zee Pin; Chua, Yeow Leng; Lim, Soo Teik; Sin, Kenny Yoong Kong; Tan, Jack Wei Chieh; Chiam, Paul Toon Lim; Hwang, Nian Chih; Koh, Tian Hai

    2013-01-01

    A 67-year-old Chinese woman with comorbidities of chronic obstructive lung disease, hypertension and prior coronary artery bypass surgery presented with severe functional mitral regurgitation (MR) and severely depressed left ventricular function. She was in New York Heart Association (NYHA) Class II-III. Due to high surgical risk, she was referred for percutaneous treatment with the MitraClip valve repair system. This procedure is typically performed via the femoral venous system and involves a transseptal puncture. A clip is delivered to grasp the regurgitant mitral valve leaflets and reduce MR. This was performed uneventfully in our patient, with reduction of MR from 4+ to 1+. She was discharged on post-procedure Day 2 and her NYHA class improved to Class I. This was the first successful MitraClip procedure performed in Asia and represents a valuable treatment option in patients with severe MR, especially those with functional MR or those at high surgical risk.

  7. Progression to moderate or severe mitral regurgitation after percutaneous transvenous mitral commissurotomy using stepwise inflation technique.

    PubMed

    Matsubara, T; Yamazoe, M; Tamura, Y; Tanabe, Y; Hori, T; Konno, T; Higuchi, K; Ida, T; Takemoto, M; Aizawa, Y

    1998-05-01

    Progression to moderate or severe mitral regurgitation (MR) was studied after Inoue balloon percutaneous transvenous mitral commissurotomy (PTMC) using the stepwise inflation technique, performed at increments of 1 mm of balloon diameter, in 49 consecutive patients with rheumatic mitral stenosis (aged from 32-73 years; 8 males, 41 females). The patients were classified on the basis of the degree of MR after PTMC, compared with that before PTMC, into either Group A, development of moderate or more severe (> or = grade 2) MR (n = 8) or Group B, no increase in MR or development of mild (grade 1) MR (n = 41). Progression to moderate or severe MR was significantly associated only with advanced age (60 +/- 8 vs 52 +/- 10 years, p < 0.05) and narrower mitral valve area (0.87 +/- 0.35 vs 1.11 +/- 0.29 cm2, p < 0.05), but other characteristics before PTMC were similar in both groups. There was no difference between the two groups in the total number and degree of balloon inflation. Immediately before the final inflation, the left atrial mean pressure and v wave pressure were decreased in smaller degrees in Group A compared with Group B (-2 +/- 2 vs -5 +/- 4 mmHg, p < 0.05; -2 +/- 2 vs -6 +/- 6 mmHg, p < 0.05, respectively). Thus, the stepwise inflations require careful monitoring of changes in the left atrial pressure and waveform to recognize the aggravation of MR, especially in older patients with severe stenosis. Patients who do not have a significant drop in left atrial mean pressure and v wave pressure during stepwise inflations of the balloon might be at risk of development of moderate or severe MR after further dilations.

  8. Single-centre experience with mitral valve repair in asymptomatic patients with severe mitral valve regurgitation†

    PubMed Central

    van Leeuwen, Wouter J.; Head, Stuart J.; de Groot-de Laat, Lotte E.; Geleijnse, Marcel L.; Bogers, Ad J.J.C.; Van Herwerden, Lex A.; Kappetein, A. Pieter

    2013-01-01

    OBJECTIVES Guidelines recommend surgical mitral valve repair in selected patients with asymptomatic severe mitral valve regurgitation (MR), but the role of repair remains a matter of debate. Survival analyses of operated asymptomatic patients have been reported, but long-term haemodynamics and quality of life are not well defined. The aim of this study was to report the long-term follow-up focusing on these aspects. METHODS Our database identified patients who underwent primary isolated mitral valve repair for severe MR and were asymptomatic by New York Heart Association Class I and in sinus rhythm. To obtain sufficient length of follow-up, only patients operated on before 2006 returned for an echocardiogram and quality-of-life assessment (SF-36). RESULTS Between May 1991 and December 2005, 46 asymptomatic patients with severe MR and a normal left ventricular function (ejection fraction >60%) were operated on. Mean age was 50.2 ± 13.2 years and 89% of patients were male. There were no operative deaths. Mean follow-up was 8.4 ± 3.9 years with 386 patient-years, survival was 93.3% at 12 years and comparable with the general age-matched Dutch population. Follow-up echocardiography showed that 92% had no to mild MR, and 3 patients had moderate MR. Left ventricular function was good/impaired/moderate in 66/29/5% of patients. Quality-of-life SF-36 assessment showed that mean physical and mental health components were 83 ± 17 and 79 ± 17, which was comparable with that of the general age- and gender-matched Dutch population. CONCLUSIONS Our experience shows that mitral valve repair for severe MR in asymptomatic patients is safe, and has satisfactory long-term survival with a low recurrence rate of MR, good left ventricular function, and excellent quality of life that is comparable with the general Dutch population. PMID:23442941

  9. Fully automated software for mitral annulus evaluation in chronic mitral regurgitation by 3-dimensional transesophageal echocardiography.

    PubMed

    Aquila, Iolanda; Fernández-Golfín, Covadonga; Rincon, Luis Miguel; González, Ariana; García Martín, Ana; Hinojar, Rocio; Jimenez Nacher, Jose Julio; Indolfi, Ciro; Zamorano, Jose Luis

    2016-12-01

    Three-dimensional (3D) transesophageal echocardiography (TEE) is the gold standard for mitral valve (MV) anatomic and functional evaluation. Currently, dedicated MV analysis software has limitations for its use in clinical practice. Thus, we tested here a complete and reproducible evaluation of a new fully automatic software to characterize MV anatomy in different forms of mitral regurgitation (MR) by 3D TEE.Sixty patients were included: 45 with more than moderate MR (28 organic MR [OMR] and 17 functional MR [FMR]) and 15 controls. All patients underwent TEE. 3D MV images obtained using 3D zoom were imported into the new software for automatic analysis. Different MV parameters were obtained and compared. Anatomic and dynamic differences between FMR and OMR were detected. A significant increase in systolic (859.75 vs 801.83 vs 607.78 mm; P = 0.002) and diastolic (1040.60 vs. 1217.83 and 859.74 mm; P < 0.001) annular sizes was observed in both OMR and FMR compared to that in controls. FMR had a reduced mitral annular contraction compared to degenerative cases of OMR and to controls (17.14% vs 32.78% and 29.89%; P = 0.007). Good reproducibility was demonstrated along with a short analysis time (mean 4.30 minutes).Annular characteristics and dynamics are abnormal in both FMR and OMR. Full 3D software analysis automatically calculates several significant parameters that provide a correct and complete assessment of anatomy and dynamic mitral annulus geometry and displacement in the 3D space. This analysis allows a better characterization of MR pathophysiology and could be useful in designing new devices for MR repair or replacement.

  10. Fully automated software for mitral annulus evaluation in chronic mitral regurgitation by 3-dimensional transesophageal echocardiography

    PubMed Central

    Aquila, Iolanda; Fernández-Golfín, Covadonga; Rincon, Luis Miguel; González, Ariana; García Martín, Ana; Hinojar, Rocio; Jimenez Nacher, Jose Julio; Indolfi, Ciro; Zamorano, Jose Luis

    2016-01-01

    Abstract Three-dimensional (3D) transesophageal echocardiography (TEE) is the gold standard for mitral valve (MV) anatomic and functional evaluation. Currently, dedicated MV analysis software has limitations for its use in clinical practice. Thus, we tested here a complete and reproducible evaluation of a new fully automatic software to characterize MV anatomy in different forms of mitral regurgitation (MR) by 3D TEE. Sixty patients were included: 45 with more than moderate MR (28 organic MR [OMR] and 17 functional MR [FMR]) and 15 controls. All patients underwent TEE. 3D MV images obtained using 3D zoom were imported into the new software for automatic analysis. Different MV parameters were obtained and compared. Anatomic and dynamic differences between FMR and OMR were detected. A significant increase in systolic (859.75 vs 801.83 vs 607.78 mm2; P = 0.002) and diastolic (1040.60 vs. 1217.83 and 859.74 mm2; P < 0.001) annular sizes was observed in both OMR and FMR compared to that in controls. FMR had a reduced mitral annular contraction compared to degenerative cases of OMR and to controls (17.14% vs 32.78% and 29.89%; P = 0.007). Good reproducibility was demonstrated along with a short analysis time (mean 4.30 minutes). Annular characteristics and dynamics are abnormal in both FMR and OMR. Full 3D software analysis automatically calculates several significant parameters that provide a correct and complete assessment of anatomy and dynamic mitral annulus geometry and displacement in the 3D space. This analysis allows a better characterization of MR pathophysiology and could be useful in designing new devices for MR repair or replacement. PMID:27930514

  11. Planet-disc interaction in laminar and turbulent discs

    NASA Astrophysics Data System (ADS)

    Stoll, Moritz H. R.; Picogna, Giovanni; Kley, Wilhelm

    2017-07-01

    In weakly ionised discs turbulence can be generated through the vertical shear instability (VSI). Embedded planets are affected by a stochastic component in the torques acting on them, which can impact their migration. In this work we study the interplay between a growing planet embedded in a protoplanetary disc and the VSI turbulence. We performed a series of 3D hydrodynamical simulations for locally isothermal discs with embedded planets in the mass range from 5 to 100 Earth masses. We study planets embedded in an inviscid disc that is VSI unstable, becomes turbulent, and generates angular momentum transport with an effective α = 5 × 10-4. This is compared to the corresponding viscous disc using exactly this α-value. In general we find that the planets have only a weak impact on the disc turbulence. Only for the largest planet (100 M⊕) does the turbulent activity become enhanced inside of the planet. The depth and width of a gap created by the more massive planets (30,100 M⊕) in the turbulent disc equal exactly that of the corresponding viscous case, leading to very similar torque strengths acting on the planet, with small stochastic fluctuations for the VSI disc. At the gap edges vortices are generated that are stronger and longer-lived in the VSI disc. Low mass planets (with Mp ≤ 10 M⊕) do not open gaps in the disc in either case, but generate for the turbulent disc an overdensity behind the planet that exerts a significant negative torque. This can boost the inward migration in VSI turbulent discs well above the Type I rate. Owing to the finite turbulence level in realistic 3D discs the gap depth will always be limited and migration will not stall in inviscid discs.

  12. Intentional Laceration of the Anterior Mitral Valve Leaflet to Prevent Left Ventricular Outflow Tract Obstruction During Transcatheter Mitral Valve Replacement

    PubMed Central

    Khan, Jaffar M.; Rogers, Toby; Schenke, William H.; Mazal, Jonathan R.; Faranesh, Anthony Z.; Greenbaum, Adam B.; Babaliaros, Vasilis C.; Chen, Marcus Y.; Lederman, Robert J.

    2017-01-01

    OBJECTIVES The authors propose a novel transcatheter transection of the anterior mitral leaflet to prevent iatrogenic left ventricular outflow tract (LVOT) obstruction during transcatheter mitral valve replacement (TMVR). BACKGROUND LVOT obstruction is a life-threatening complication of TMVR caused by septal displacement of the anterior mitral leaflet. METHODS In vivo procedures in swine were guided by biplane x-ray fluoroscopy and intracardiac echocardiography. Retrograde transaortic 6-F guiding catheters straddled the anterior mitral leaflet. A stiff 0.014-inch guidewire with polymer jacket insulation was electrified and advanced from the LVOT, through the A2 leaflet base, into the left atrium. The wire was snared and externalized, forming a loop that was energized and withdrawn to lacerate the anterior mitral leaflet. RESULTS The anterior mitral leaflet was successfully lacerated in 7 live and 1 post-mortem swine under heparinization. Lacerations extended to 89 ± 19% of leaflet length and were located within 0.5 ± 0.4 mm of leaflet centerline. The chordae were preserved and retracted the leaflet halves away from the LVOT. LVOT narrowing after benchtop TMVR was significantly reduced with intentional laceration of the anterior mitral leaflet to prevent LVOT obstruction than without (65 ± 10% vs. 31 ± 18% of pre-implantation diameter, p < 0.01). The technique caused mean blood pressure to fall (from 54 ± 6 mm Hg to 30 ± 4 mm Hg, p < 0.01), but blood pressure remained steady until planned euthanasia. No collateral tissue injury was identified on necropsy. CONCLUSIONS Using simple catheter techniques, the anterior mitral valve leaflet was transected. Cautiously applied in patients, this strategy can prevent anterior mitral leaflet displacement and LVOT obstruction caused by TMVR. PMID:27609260

  13. Collagen organization in canine myxomatous mitral valve disease: an x-ray diffraction study.

    PubMed

    Hadian, Mojtaba; Corcoran, Brendan M; Han, Richard I; Grossmann, J Günter; Bradshaw, Jeremy P

    2007-10-01

    Collagen fibrils, a major component of mitral valve leaflets, play an important role in defining shape and providing mechanical strength and flexibility. Histopathological studies show that collagen fibrils undergo dramatic changes in the course of myxomatous mitral valve disease in both dogs and humans. However, little is known about the detailed organization of collagen in this disease. This study was designed to analyze and compare collagen fibril organization in healthy and lesional areas of myxomatous mitral valves of dogs, using synchrotron small-angle x-ray diffraction. The orientation, density, and alignment of collagen fibrils were mapped across six different valves. The findings reveal a preferred collagen alignment in the main body of the leaflets between two commissures. Qualitative and quantitative analysis of the data showed significant differences between affected and lesion-free areas in terms of collagen content, fibril alignment, and total tissue volume. Regression analysis of the amount of collagen compared to the total tissue content at each point revealed a significant relationship between these two parameters in lesion-free but not in affected areas. This is the first time this technique has been used to map collagen fibrils in cardiac tissue; the findings have important applications to human cardiology.

  14. Investigation of Product Performance of Al-Metal Matrix Composites Brake Disc using Finite Element Analysis

    NASA Astrophysics Data System (ADS)

    Fatchurrohman, N.; Marini, C. D.; Suraya, S.; Iqbal, AKM Asif

    2016-02-01

    The increasing demand of fuel efficiency and light weight components in automobile sectors have led to the development of advanced material parts with improved performance. A specific class of MMCs which has gained a lot of attention due to its potential is aluminium metal matrix composites (Al-MMCs). Product performance investigation of Al- MMCs is presented in this article, where an Al-MMCs brake disc is analyzed using finite element analysis. The objective is to identify the potentiality of replacing the conventional iron brake disc with Al-MMCs brake disc. The simulation results suggested that the MMCs brake disc provided better thermal and mechanical performance as compared to the conventional cast iron brake disc. Although, the Al-MMCs brake disc dissipated higher maximum temperature compared to cast iron brake disc's maximum temperature. The Al-MMCs brake disc showed a well distributed temperature than the cast iron brake disc. The high temperature developed at the ring of the disc and heat was dissipated in circumferential direction. Moreover, better thermal dissipation and conduction at brake disc rotor surface played a major influence on the stress. As a comparison, the maximum stress and strain of Al-MMCs brake disc was lower than that induced on the cast iron brake disc.

  15. Pregnancy-induced remodeling of collagen architecture and content in the mitral valve.

    PubMed

    Pierlot, Caitlin M; Lee, J Michael; Amini, Rouzbeh; Sacks, Michael S; Wells, Sarah M

    2014-10-01

    Pregnancy produces rapid, non-pathological volume-overload in the maternal circulation due to the demands of the growing fetus. Using a bovine model for human pregnancy, previous work in our laboratory has shown remarkable pregnancy-induced changes in leaflet size and mechanics of the mitral valve. The present study sought to relate these changes to structural alterations in the collagenous leaflet matrix. Anterior mitral valve leaflets were harvested from non-pregnant heifers and pregnant cows (pregnancy stage estimated by fetal length). We measured changes in the thickness of the leaflet and its anatomic layers via Verhoeff-Van Gieson staining, and in collagen crimp (wavelength and percent collagen crimped) via picrosirius red staining and polarized microscopy. Collagen concentration was determined biochemically: hydroxyproline assay for total collagen and pepsin-acid extraction for uncrosslinked collagen. Small-angle light scattering (SALS) assessed changes in internal fiber architecture (characterized by degree of fiber alignment and preferred fiber direction). Pregnancy produced significant changes to collagen structure in the mitral valve. Fiber alignment decreased 17% with an 11.5° rotation of fiber orientation toward the radial axis. Collagen fiber crimp was dramatically lost, accompanied by a 53% thickening of the fibrosa, and a 16% increase in total collagen concentration, both suggesting that new collagen is being synthesized. Extractable collagen concentration was low, both in the non-pregnant and pregnant state, suggesting early crosslinking of newly-synthesized collagen. This study has shown that the mitral valve is strongly adaptive during pregnancy, with significant changes in size, collagen content and architecture in response to rapidly changing demands.

  16. Sinus Rhythm in Rheumatic Mitral Stenosis after Balloon Mitral Valvotomy: Is it Feasible?

    PubMed Central

    Shukla, Anand N; Shah, Saurin; Nayak, Vidya; Prabhu, Sridevi; Pai, Umesh

    2017-01-01

    Introduction Atrial Fibrillation (AF) is largely present in patients with rheumatic valvular disease, leading to hospitalizations. Aim We aimed to study the restoration and maintenance of Sinus Rhythm (SR) in rheumatic patients with Mitral Stenosis (MS) and AF after Balloon Mitral Valvotomy (BMV) and evaluated the factors which affect the maintenance of SR. Materials and Methods A total of 50 patients who underwent BMV at U. N. Mehta Institute of Cardiology and Research Centre from 2010 November to 2013 January were included in the study. Subsequently, all patients were treated with amiodarone and electrical cardioversion was applied in patients in whom it was necessary. The patients were followed for six months for conversion and maintenance of SR. Results Total 34 (68%) patients reverted to SR. Twelve patients reverted to SR with amiodarone and 22 patients with electrical cardioversion and amiodarone. Out of the total, 29 patients and 26 patients remained in SR at the end of follow up at 3 months and 6 months respectively. Conclusion Smaller Left Atrial (LA) size and greater Mitral Valve Area (MVA) are the chief predictors of restoration and maintenance of SR. Combining BMV with an aggressive anti-arrhythmic strategy offers the best prospect of rhythm control. PMID:28384905

  17. Biomechanical and biochemical outcomes of porcine temporomandibular joint disc deformation.

    PubMed

    Matuska, Andrea M; Muller, Stephen; Dolwick, M Franklin; McFetridge, Peter S

    2016-04-01

    The structure-function relationship in the healthy temporomandibular joint (TMJ) disc has been well established, however the changes in dysfunctional joints has yet to be systematically evaluated. Due to the poor understanding of the etiology of temporomandibular disorders (TMDs) this study evaluated naturally occurring degenerative remodeling in aged female porcine temporomandibular joint (TMJ) discs in order to gain insight into the progression and effects on possible treatment strategies of TMDs. Surface and regional biomechanical and biochemical properties of discal tissues were determined in grossly deformed (≥Wilkes Stage 3) and morphologically normal (≤Wilkes Stage 2) TMJ discs. Compared to normal disc structure the deformed discs lacked a smooth biconcave shape and characteristic ECM organization. Reduction in tensile biomechanical integrity and increased compressive stiffness and cellularity was found in deformed discs. Regionally, the posterior and intermediate zones of the disc were most frequently affected along with the inferior surface. The frequency of degeneration observed on the inferior surface of the disc (predominantly posterior), suggests that a disruption in the disc-condyle relationship likely contributes to the progression of joint dysfunction more than the temporodiscal relationship. As such, the inferior joint space may be an important consideration in early clinical diagnosis and treatment of TMDs, as it is overlooked in techniques performed in the upper joint space, including arthroscopy and arthrocentesis. Furthermore, permanent damage to the disc mechanical properties would limit the ability to successfully reposition deformed discs, highlighting the importance of emerging therapies such as tissue engineering. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. 26 CFR 1.6011-2 - Returns, etc., of DISC's and former DISC's.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 26 Internal Revenue 13 2011-04-01 2011-04-01 false Returns, etc., of DISC's and former DISC's. 1...., of DISC's and former DISC's. (a) Records and information. Every DISC and former DISC (as defined in..., statements, and special returns. Thus, for example, a DISC is required to maintain the books of account or...

  19. [Displacement and tissue remodeling of temporomandibular joint disc].

    PubMed

    Wang, M Q

    2017-03-09

    Sounding takes the highest prevalence of the signs of temporomandibular disorders (TMD). The well accepted theory of the mechanism for temporomandibular joint (TMJ) sounding is the internal derangement typically characterized by disc displacement. However, according to literature, there are approximately one third of asymptomatic joints in population had disc displacement, and, on the other hand, there are one fourth of TMJ sounding patients had not signs or very limited signs of disc displacement. Replacing the displaced disc to the normal position via methods like surgical operation did not achieve satisfactory long-term outcomes. In this review, we discuss and analyze the possible remodeling of the joint disc displacement diagnosed with imaging based on the anatomy and pathophysiology.

  20. Analytical Investigation on Squeal Phenomena Generated in Bicycle Disc Brakes

    NASA Astrophysics Data System (ADS)

    Nakae, Takashi; Sueoka, Atsuo; Ryu, Takahiro

    The squeal phenomenon is often generated in bicycle disc brakes. This paper deals analytically with the generation mechanism and the criterion of whether or not the squeal occurs. According to the experimental studies, it has been made clear that the squeal is mainly in-plane vibration in the direction of disc surface with the frequency about 1kHz caused by frictional characteristics with negative slope with respect to the relative velocity. An analytical model of the bicycle disc brake system has been devised to confirm the experimental results, in which a coupled in-plane and out-of-plane vibrating system is composed of the disc, hub, caliper and spokes. The resulting frequency of squeal and the unstable vibration modes of the disc and spokes from the analytical model agreed well with the experimental results.

  1. Minimally Invasive, Nonsurgical Approach to Repairing Mitral Valve Leaks

    MedlinePlus

    Minimally Invasive, Nonsurgical Approach to Repairing Mitral Valve Leaks - David X. Zhao, MD Click Here to view the BroadcastMed, Inc. Privacy Policy and Legal Notice © 2017 BroadcastMed, Inc. All rights ...

  2. MitraClip catheter-based mitral valve repair system.

    PubMed

    Jönsson, Anders; Settergren, Magnus

    2010-07-01

    The ongoing evolution of transcatheter valve technology is impressive. Mitral valve regurgitation is the most common type of heart valve insufficiency and mitral valve surgery is, next to aortic valve surgery, the second leading valvular surgical procedure in the western world. However, there is a large patient population suffering from mitral valve regurgitation that is currently not treated with heart surgery because of significant morbidity and mortality risks. This large underserved patient population could benefit from a less invasive treatment. The MitraClip system (Abbott Vascular, Menlo Park, CA, USA) is the first commercially available medical technology providing a catheter-based nonsurgical repair alternative for patients suffering from mitral valve regurgitation and has the greatest clinical experience compared with other alternative devices. The device is currently in late-stage clinical trials in the USA and has received the CE mark.

  3. Robotic mitral valve surgery: current limitations and future directions

    PubMed Central

    Suri, Rakesh; Mick, Stephanie; Mihaljevic, Tomislav

    2016-01-01

    Use of the surgical robot facilitates less invasive mitral valve surgery. Although multiple single center studies confirmed excellent results with robotically-assisted mitral valve surgery, both real and perceived limitations have slowed adoption of this technology. Some still question the safety and efficacy of robotically-assisted mitral valve surgery. However, present data suggests that robotic operations can be performed by specialized surgeons in appropriately selected patients without compromising results. That said, the robot does introduce additional procedural complexity related to management of cardiopulmonary bypass and myocardial protection. A direct approach to these challenges combined with careful patient selection enables the surgeon to obtain excellent results with robotically-assisted mitral valve surgery. PMID:27942490

  4. Mitral valve aneurysm: A serious complication of aortic valve endocarditis.

    PubMed

    Sousa, Maria João; Alves, Vasco; Cabral, Sofia; Antunes, Nuno; Pereira, Luís Sousa; Oliveira, Filomena; Silveira, João; Torres, Severo

    2016-11-01

    Mitral valve aneurysms are rare and occur most commonly in association with aortic valve endocarditis. Transesophageal echocardiography is the most sensitive imaging modality for the diagnosis of this entity and its potential complications, such as leaflet rupture and mitral regurgitation, which mandate prompt surgical intervention. We present the case of a 70-year-old male patient with aortic valve endocarditis complicated with a ruptured aneurysm of the anterior mitral valve leaflet and associated severe mitral regurgitation, diagnosed by transesophageal echocardiography, with impressive images. We hypothesized that the aneurysm developed through direct extension of infection from the aortic valve or from a prolapsing aortic vegetation, with abscess formation and subsequent rupture and drainage. This case highlights the importance of appropriate imaging for early detection and timely surgical intervention (repair or replacement) to prevent fatal outcomes. Copyright © 2016 Sociedade Portuguesa de Cardiologia. Publicado por Elsevier España, S.L.U. All rights reserved.

  5. Tissue Engineering a Biological Repair Strategy for Lumbar Disc Herniation

    PubMed Central

    O'Connell, Grace D.; Leach, J. Kent; Klineberg, Eric O.

    2015-01-01

    Abstract The intervertebral disc is a critical part of the intersegmental soft tissue of the spinal column, providing flexibility and mobility, while absorbing large complex loads. Spinal disease, including disc herniation and degeneration, may be a significant contributor to low back pain. Clinically, disc herniations are treated with both nonoperative and operative methods. Operative treatment for disc herniation includes removal of the herniated material when neural compression occurs. While this strategy may have short-term advantages over nonoperative methods, the remaining disc material is not addressed and surgery for mild degeneration may have limited long-term advantage over nonoperative methods. Furthermore, disc herniation and surgery significantly alter the mechanical function of the disc joint, which may contribute to progression of degeneration in surrounding tissues. We reviewed recent advances in tissue engineering and regenerative medicine strategies that may have a significant impact on disc herniation repair. Our review on tissue engineering strategies focuses on cell-based and inductive methods, each commonly combined with material-based approaches. An ideal clinically relevant biological repair strategy will significantly reduce pain and repair and restore flexibility and motion of the spine. PMID:26634189

  6. Severe rheumatic mitral stenosis: a 21st century medusa.

    PubMed

    Carrilho-Ferreira, Pedro; Pedro, Monica Mendes; Varela, Manuel Gato; Diogo, Antonio Nunes

    2011-09-12

    Although the prevalence of rheumatic fever has greatly decreased in developed countries, rheumatic mitral stenosis still causes significant morbidity and mortality. Symptomatic patients have a poor prognosis, with a 0 to 15% 10-year survival rate, particularly if percutaneous or surgical intervention are contraindicated or considered high risk. We present a case of severe rheumatic mitral stenosis with an evolution over 4 decades, in which exceptional venous distention has established.

  7. Isolated true parachute mitral valve in an asymptomatic elderly patient.

    PubMed

    Yamamoto, Tetsushi; Onishi, Tetsuari; Omar, Alaa Marbrouk Salem; Norisada, Kazuko; Tatsumi, Kazuhiro; Matsumoto, Kensuke; Hayashi, Nobuhide; Kinoshita, Shouhiro; Kawano, Seiji; Kawai, Hiroya; Hirata, Ken-Ichi; Kumagai, Shunichi

    2010-12-01

    We report the extremely rare case of a 73-year-old asymptomatic patient who has an isolated true parachute mitral valve (PMV). In the echocardiographic examination, the parasternal long-axis view showed a single papillary muscle. The short-axis view revealed the presence of a symmetric mitral valve orifice with all chordae attaching to a large anterolateral papillary muscle. Because detailed examination did not reveal the presence of other complications, this patient was diagnosed as an isolated true PMV.

  8. Reexamining contraindications for minimally invasive mitral valve surgery.

    PubMed

    Reade, Clifton C; Bower, Curtis E; Kypson, Alan P; Nifong, L Wiley; Wooden, William A; Chitwood, W Randolph

    2005-01-01

    Historically, contraindications to minimally invasive or robotic mitral valve surgery have included prior mastectomy, thoracic reconstruction, or chest radiation. However, we believe that by granting flexibility in the choice of skin incision site while performing careful dissection, surgeons can provide these patients the outstanding results afforded by a minithoracotomy. We present a patient who had undergone a prior mastectomy and radiation treatment in whom we performed a minimally invasive mitral valve repair through a right-sided minithoracotomy using the previous mastectomy incision.

  9. Anomalous left coronary artery from pulmonary artery with mitral stenosis.

    PubMed

    Das, Mrinalendu; Mahindrakar, Pallavi; Das, Debasis; Behera, Sukanta Kumar; Chowdhury, Saibal Roy; Bandyopadhyay, Biswajit

    2011-08-01

    The usual presentation of anomalous left coronary artery from pulmonary artery is severe left-sided heart failure and mitral valve insufficiency presenting during the first months of life. The manifestations of left heart failure may be masked if pulmonary artery pressure remains high. We believe this is a rarest of rare case of anomalous left coronary artery from pulmonary artery with severe mitral stenosis and pulmonary hypertension in which pulmonary hypertension, along with good collateral circulation helped to preserve left ventricular function.

  10. LUMBAR DISC HERNIATION

    PubMed Central

    Vialle, Luis Roberto; Vialle, Emiliano Neves; Suárez Henao, Juan Esteban; Giraldo, Gustavo

    2015-01-01

    Lumbar disc herniation is the most common diagnosis among the degenerative abnormalities of the lumbar spine (affecting 2 to 3% of the population), and is the principal cause of spinal surgery among the adult population. The typical clinical picture includes initial lumbalgia, followed by progressive sciatica. The natural history of disc herniation is one of rapid resolution of the symptoms (four to six weeks). The initial treatment should be conservative, managed through medication and physiotherapy, sometimes associated with percutaneous nerve root block. Surgical treatment is indicated if pain control is unsuccessful, if there is a motor deficit greater than grade 3, if there is radicular pain associated with foraminal stenosis, or if cauda equina syndrome is present. The latter represents a medical emergency. A refined surgical technique, with removal of the extruded fragment and preservation of the ligamentum flavum, resolves the sciatic symptoms and reduces the risk of recurrence over the long term. PMID:27019834

  11. Mechanotransduction in intervertebral discs

    PubMed Central

    Tsai, Tsung-Ting; Cheng, Chao-Min; Chen, Chien-Fu; Lai, Po-Liang

    2014-01-01

    Mechanotransduction plays a critical role in intracellular functioning—it allows cells to translate external physical forces into internal biochemical activities, thereby affecting processes ranging from proliferation and apoptosis to gene expression and protein synthesis in a complex web of interactions and reactions. Accordingly, aberrant mechanotransduction can either lead to, or be a result of, a variety of diseases or degenerative states. In this review, we provide an overview of mechanotransduction in the context of intervertebral discs, with a focus on the latest methods of investigating mechanotransduction and the most recent findings regarding the means and effects of mechanotransduction in healthy and degenerative discs. We also provide some discussion of potential directions for future research and treatments. PMID:25267492

  12. Increased dispersion of refractoriness in the absence of QT prolongation in patients with mitral valve prolapse and ventricular arrhythmias.

    PubMed Central

    Tieleman, R. G.; Crijns, H. J.; Wiesfeld, A. C.; Posma, J.; Hamer, H. P.; Lie, K. I.

    1995-01-01

    BACKGROUND--The mechanism responsible for the reported high incidence of ventricular arrhythmias in mitral valve prolapse is not clear. Electrocardiographic studies show an increased occurrence of repolarisation abnormalities on the 12 lead surface electrocardiogram, indicating regional differences in ventricular recovery. The purpose of this study was to investigate whether dispersion of refractoriness was an arrhythmogenic mechanism. METHODS--QT dispersion was measured in 32 patients with echocardiographically documented mitral valve prolapse and ventricular arrhythmias on 24 hour Holter recordings. QT dispersion was defined as the difference between the maximum and minimum average QT interval in any of the 12 leads of the surface electrocardiogram. QT dispersion corrected for heart rate was calculated by Bazett's formula. The results were compared with the data from 32 matched controls without a history of cardiac disease. Patients taking drugs that influence the QT interval and patients with a QRS duration > 120 ms were excluded. RESULTS--QT dispersion was greater in patients with mitral valve prolapse than in matched controls (60 (20) v 39 (11 ms) respectively, P < or = 0.001) as was corrected QT (64 (20 ms) v 43 (12 ms) respectively, P < or = 0.001). There was no significant difference in minimum or maximum QT intervals between the two groups. CONCLUSIONS--QT dispersion on the 12 lead surface electrocardiogram was greater in patients with mitral valve prolapse with ventricular arrhythmias than in normal controls, but the maximum QT interval was not increased. The results accord with the hypothesis that regional shortening and lengthening of repolarisation times in patients with mitral valve prolapse may account for the increased dispersion of refractoriness. PMID:7888258

  13. Rheology of intervertebral disc: an ex vivo study on the effect of loading history, loading magnitude, fatigue loading, and disc degeneration.

    PubMed

    Kuo, Ya-Wen; Wang, Jaw-Lin

    2010-07-15

    An ex vivo biomechanical study on the rheological properties of healthy porcine and degenerated human intervertebral disc. To quantify the effect of loading history, loading magnitude, fatigue loading, and degeneration on disc rheology. Disc rheological parameters, i.e., the aggregate modulus (HA) and hydraulic permeability (k) regulate the mechanical and biologic function of disc. The knowledge of effects of loading condition and degeneration on disc rheology can be beneficial for the design of new disc/nucleus implants or therapy. The following 4 phases of experiments were conducted to find the changes of disc rheological properties: (1) Effect of loading history during 1-hour creep (640 N) and relaxation (20% strain) test. (2) Effect of loading magnitude (420 N vs. 640 N) during the creep test. (3) Effect of fatigue loading (420 N, 5 Hz for 0.5, 1, and 2 hours) on the creep loading behavior. (4) Difference of healthy porcine and degenerated human discs during creep loading. The experimental data were fitted with linear biphasic model. The aggregate modulus increased but hydraulic permeability decreased during creep loading. The aggregate modulus decreased but the hydraulic permeability did not change significantly during relaxation loading. The higher creep loading increased the aggregate modulus but decreased the hydraulic permeability. The fatigue loading did not change the aggregate modulus significantly, but decreased hydraulic permeability. Comparing the degenerated human disc to the healthy porcine disc, the aggregate modulus was higher but the hydraulic permeability was lower. The external loading and degeneration induce disc structural changes, e.g., the disc water content and interstitial matrix porosity, hence affect the disc rheological properties. The increase of aggregate modulus may be due to the reduction of disc hydration level, whereas the decrease of hydraulic permeability may be because of the shrinkage of disc matrix pores.

  14. Robotic mitral valve surgery: overview, methodology, results, and perspective

    PubMed Central

    2016-01-01

    Robotic mitral valve repair began in 1998 and has advanced remarkably. It arose from an interest in reducing patient trauma by operating through smaller incisions with videoscopic assistance. In the United States, following two clinical trials, the FDA approved the daVinci Surgical System in 2002 for intra-cardiac surgery. This device has undergone three iterations, eventuating in the current daVinci XI. At present it is the only robotic device approved for mitral valve surgery. Many larger centers have adopted its use as part of their routine mitral valve repair armamentarium. Although these operations have longer perfusion and arrest times, complications have been either similar or less than other traditional methods. Preoperative screening is paramount and leads to optimal patient selection and outcomes. There are clear contraindications, both relative and absolute, that must be considered. Three-dimensional (3D) echocardiographic studies optimally guide surgeons in operative planning. Herein, we describe the selection criteria as well as our operative management during a robotic mitral valve repair. Major complications are detailed with tips to avoid their occurrence. Operative outcomes from the author’s series as well as those from the largest experiences in the United States are described. They show that robotic mitral valve repair is safe and effective, as well as economically reasonable due to lower costs of hospitalization. Thus, the future of this operative technique is bright for centers adopting the “heart team” approach, adequate clinical volume and a dedicated and experienced mitral repair surgeon. PMID:27942486

  15. Role of Imaging Techniques in Percutaneous Treatment of Mitral Regurgitation.

    PubMed

    Li, Chi-Hion; Arzamendi, Dabit; Carreras, Francesc

    2016-04-01

    Mitral regurgitation is the most prevalent valvular heart disease in the United States and the second most prevalent in Europe. Patients with severe mitral regurgitation have a poor prognosis with medical therapy once they become symptomatic or develop signs of significant cardiac dysfunction. However, as many as half of these patients are inoperable because of advanced age, ventricular dysfunction, or other comorbidities. Studies have shown that surgery increases survival in patients with organic mitral regurgitation due to valve prolapse but has no clinical benefit in those with functional mitral regurgitation. In this scenario, percutaneous repair for mitral regurgitation in native valves provides alternative management of valvular heart disease in patients at high surgical risk. Percutaneous repair for mitral regurgitation is a growing field that relies heavily on imaging techniques to diagnose functional anatomy and guide repair procedures. Copyright © 2016 Sociedad Española de Cardiología. Published by Elsevier España, S.L.U. All rights reserved.

  16. [Atrial functional mitral regurgitation. Three-dimensional echocardiographic study].

    PubMed

    Hernández-Ramírez, José Miguel; Ortega-Trujillo, José Ramón

    2017-07-24

    Atrial fibrillation can lead to a left atrium remodeling and induce functional mitral regurgitation. The aim of this study is to establish what features of the mitral annulus are related to atrial functional mitral regurgitation. Retrospectively 29 patients with persistent atrial fibrillation and 36 controls in sinus rhythm were enrolled. The characteristics of the mitral annulus were analyzed by three-dimensional transesophageal echocardiography in both groups. 2D and 3D echocardiographic parameters were correlated with the effective regurgitant orifice. Patients with atrial fibrillation had larger left atrium volume, anteroposterior diameter at end-diastole and lower percentage of change in this diameter (P: 0.015, 0.019 and <0.001, respectively). In the multiple regression analysis the ellipticity index (β: -0.756, P: 0.004) and height-anterolateral-posteriomedial diameter ratio (β: -0704, P: 0.003) were independent parameters correlated with the effective regurgitant orifice (R(2): 0.699, P: 0.019) in patients with atrial fibrillation. Atrial fibrillation leads to atrial dilatation and alterations in the size and dynamic of the anteroposterior diameter, producing a circular mitral annulus. The independents determinants of atrial functional mitral regurgitation in the atrial fibrillation group were the ellipticity index and height-anterolateral-posteromedial diameter ratio. Copyright © 2017 Instituto Nacional de Cardiología Ignacio Chávez. Publicado por Masson Doyma México S.A. All rights reserved.

  17. Total disc replacement.

    PubMed

    Vital, J-M; Boissière, L

    2014-02-01

    Total disc replacement (TDR) (partial disc replacement will not be described) has been used in the lumbar spine since the 1980s, and more recently in the cervical spine. Although the biomechanical concepts are the same and both are inserted through an anterior approach, lumbar TDR is conventionally indicated for chronic low back pain, whereas cervical TDR is used for soft discal hernia resulting in cervicobrachial neuralgia. The insertion technique must be rigorous, with precise centering in the disc space, taking account of vascular anatomy, which is more complex in the lumbar region, particularly proximally to L5-S1. All of the numerous studies, including prospective randomized comparative trials, have demonstrated non-inferiority to fusion, or even short-term superiority regarding speed of improvement. The main implant-related complication is bridging heterotopic ossification with resulting loss of range of motion and increased rates of adjacent segment degeneration, although with an incidence lower than after arthrodesis. A sufficiently long follow-up, which has not yet been reached, will be necessary to establish definitively an advantage for TDR, particularly in the cervical spine. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  18. Pivotal role of bedside Doppler echocardiography in the assessment of patients with acute heart failure and mitral regurgitation.

    PubMed

    Ennezat, Pierre Vladimir; Bellouin, Annaïk; Maréchaux, Sylvestre; Juthier, Francis; Fayad, Georges; Vincentelli, André; Berrébi, Alain; Auffray, Jean Luc; Bauchart, Jean Jacques; Mouquet, Frédéric; Montaigne, David; Asseman, Philippe; Le Jemtel, Thierry H; Pibarot, Philippe

    2009-01-01

    Patients presenting with mitral regurgitation and acute heart failure remain a challenge for the clinicians. Bedside echocardiography ascertains the functional or primary nature of mitral regurgitation, thereby allowing to focus therapy on the left ventricle and mitral valve apparatus in patients with functional mitral regurgitation and to hasten mitral valve repair or replacement when acute heart failure results from primary mitral regurgitation. This short article reviews the evaluation by bedside echocardiography to guide management of these patients. Copyright 2009 S. Karger AG, Basel.

  19. Estrogens and the intervertebral disc.

    PubMed

    Calleja-Agius, J; Muscat-Baron, Y; Brincat, M P

    2009-09-01

    Intervertebral discs are an integral part of the vertebral column. It has been shown that menopause has a negative effect on bone and on intervertebral discs. Estrogen has a beneficial effect of preserving the health of collagen-containing tissues, including the intervertebral disc. The intervertebral disc allows for mobility of the spine, and maintains a uniform stress distribution of the area of the vertebral endplates. Also, the disc influences spinal height. The disc tissue is adapted for this biomechanical function. The function of the spine is impaired if there is a loss of disc tissue. Narrowing of the disc space due to degeneration of intervertebral discs is associated with a significantly increased risk of vertebral fractures. Estrogen should be seen as the first-choice therapy for bones and other collagen-rich tissues, such as intervertebral discs, because it maintains homeostasis of the bone-remodelling unit. Unlike bisphosphonates, estrogen is unique in its ability to regenerate bone collagen after its disintegration, apart from suppressing osteoclastic activity. Besides, there is insufficient data on deterioration in bone qualities and micro-cracks in patients on long-term bisphosphonates.

  20. Polarimetric microlensing of circumstellar discs

    NASA Astrophysics Data System (ADS)

    Sajadian, Sedighe; Rahvar, Sohrab

    2015-12-01

    We study the benefits of polarimetry observations of microlensing events to detect and characterize circumstellar discs around the microlensed stars located at the Galactic bulge. These discs which are unresolvable from their host stars make a net polarization effect due to their projected elliptical shapes. Gravitational microlensing can magnify these signals and make them be resolved. The main aim of this work is to determine what extra information about these discs can be extracted from polarimetry observations of microlensing events in addition to those given by photometry ones. Hot discs which are closer to their host stars are more likely to be detected by microlensing, owing to more contributions in the total flux. By considering this kind of discs, we show that although the polarimetric efficiency for detecting discs is similar to the photometric observation, but polarimetry observations can help to constraint the disc geometrical parameters e.g. the disc inner radius and the lens trajectory with respect to the disc semimajor axis. On the other hand, the time-scale of polarimetric curves of these microlensing events generally increases while their photometric time-scale does not change. By performing a Monte Carlo simulation, we show that almost four optically thin discs around the Galactic bulge sources are detected (or even characterized) through photometry (or polarimetry) observations of high-magnification microlensing events during 10-yr monitoring of 150 million objects.

  1. Growth of mitral annulus in the pediatric patient after suture annuloplasty of the entire posterior mitral annulus.

    PubMed

    Komoda, Takeshi; Huebler, Michael; Berger, Felix; Hetzer, Roland

    2009-08-01

    When mitral annuloplasty is performed in small children, room for annular growth should be allowed. However, it has not been reported how the valve develops after mitral annuloplasty of the entire posterior annulus. We report a case showing traces of annular growth at redo surgery. A female patient suffering from mitral valve insufficiency due to annular dilatation underwent modified Paneth plasty with Kay-Wooler commissural plication annuloplasty at the age of two years one month. In redo surgery 8.4 years after initial repair, enlargement of the commissural portion of the posterior annulus in addition to enlargement of the anterior leaflet and anterior annulus was observed. Modified Paneth plasty reinforced with a pericardial strip and Kay-Wooler annuloplasty of the posteromedial commissure were performed. Mitral orifice size measured with the Hegar dilator was 18 mm after the re-repair, increasing from 16 mm after the initial repair. Taking into account the normal mitral annulus diameter related to body surface area (BSA) of 16 mm at initial operation and 20 mm at redo surgery, the increase in mitral orifice size from 16 mm to 18 mm in this patient may be regarded as the annular growth in 8.4 years.

  2. Disc-mass distribution in star-disc encounters

    NASA Astrophysics Data System (ADS)

    Steinhausen, M.; Olczak, C.; Pfalzner, S.

    2012-02-01

    Aims: Investigations of stellar encounters in cluster environments have demonstrated their potential influence on the mass and angular momentum of protoplanetary discs around young stars. We investigated how far the initial surface density in the disc surrounding a young star influences the outcome of an encounter. Methods: The numerical method applied here allows us to determine the mass and angular momentum losses in an encounter for any initial disc-mass distribution. On the basis of a power-law ansatz for the surface density, Σ(r) ∝ r - p, we perform a parameter study of star-disc encounters with different initial disc-mass distributions using N-body simulations. Results: We demonstrate that the shape of the disc-mass distribution has a significant impact on the quantity of the disc-mass and angular momentum losses in star-disc encounters. In particular, the results are most sensitive to how the outer parts of the disc are perturbed by high-mass stars. In contrast, disc-penetrating encounters lead more or less independently of the disc-mass distribution always to large losses. However, maximum losses are generally obtained for initially flat distributed disc material. Based on a parameter study, a fit formula is derived, describing how the relative mass and angular momentum loss depend on the initial disc-mass distribution index p. Encounters generally lead to a steepening of the density profile of the disc. The resulting profiles can have a r-2-dependence or an even steeper one that is independent of the initial distribution of the disc material. Conclusions: From observations, the initial density distribution in discs remains unconstrained, hence the strong dependence on the initial density distribution that we find here might require a revision of the effect of encounters in young stellar clusters. The steep surface density distributions induced by some encounters might be a prerequisite to the formation of planetary systems similar to our own Solar

  3. Rethinking Black Hole Accretion Discs

    NASA Astrophysics Data System (ADS)

    Salvesen, Greg

    Accretion discs are staples of astrophysics. Tapping into the gravitational potential energy of the accreting material, these discs are highly efficient machines that produce copious radiation and extreme outflows. While interesting in their own right, accretion discs also act as tools to study black holes and directly influence the properties of the Universe. Black hole X-ray binaries are fantastic natural laboratories for studying accretion disc physics and black hole phenomena. Among many of the curious behaviors exhibited by these systems are black hole state transitions -- complicated cycles of dramatic brightening and dimming. Using X-ray observations with high temporal cadence, we show that the evolution of the accretion disc spectrum during black hole state transitions can be described by a variable disc atmospheric structure without invoking a radially truncated disc geometry. The accretion disc spectrum can be a powerful diagnostic for measuring black hole spin if the effects of the disc atmosphere on the emergent spectrum are well-understood; however, properties of the disc atmosphere are largely unconstrained. Using statistical methods, we decompose this black hole spin measurement technique and show that modest uncertainties regarding the disc atmosphere can lead to erroneous spin measurements. The vertical structure of the disc is difficult to constrain due to our ignorance of the contribution to hydrostatic balance by magnetic fields, which are fundamental to the accretion process. Observations of black hole X-ray binaries and the accretion environments near supermassive black holes provide mounting evidence for strong magnetization. Performing numerical simulations of accretion discs in the shearing box approximation, we impose a net vertical magnetic flux that allows us to effectively control the level of disc magnetization. We study how dynamo activity and the properties of turbulence driven by the magnetorotational instability depend on the

  4. Effect of Losartan on Mitral Valve Changes After Myocardial Infarction.

    PubMed

    Bartko, Philipp E; Dal-Bianco, Jacob P; Guerrero, J Luis; Beaudoin, Jonathan; Szymanski, Catherine; Kim, Dae-Hee; Seybolt, Margo M; Handschumacher, Mark D; Sullivan, Suzanne; Garcia, Michael L; Titus, James S; Wylie-Sears, Jill; Irvin, Whitney S; Messas, Emmanuel; Hagège, Albert A; Carpentier, Alain; Aikawa, Elena; Bischoff, Joyce; Levine, Robert A

    2017-09-05

    After myocardial infarction (MI), mitral valve (MV) tethering stimulates adaptive leaflet growth, but counterproductive leaflet thickening and fibrosis augment mitral regurgitation (MR), doubling heart failure and mortality. MV fibrosis post-MI is associated with excessive endothelial-to-mesenchymal transition (EMT), driven by transforming growth factor (TGF)-β overexpression. In vitro, losartan-mediated TGF-β inhibition reduces EMT of MV endothelial cells. This study tested the hypothesis that profibrotic MV changes post-MI are therapeutically accessible, specifically by losartan-mediated TGF-β inhibition. The study assessed 17 sheep, including 6 sham-operated control animals and 11 with apical MI and papillary muscle retraction short of producing MR; 6 of the 11 were treated with daily losartan, and 5 were untreated, with flexible epicardial mesh comparably limiting left ventricular (LV) remodeling. LV volumes, tethering, and MV area were quantified by using three-dimensional echocardiography at baseline and at 60 ± 6 days, and excised leaflets were analyzed by histopathology and flow cytometry. Post-MI LV dilation and tethering were comparable in the losartan-treated and untreated LV constraint sheep. Telemetered sensors (n = 6) showed no significant losartan-induced changes in arterial pressure. Losartan strongly reduced leaflet thickness (0.9 ± 0.2 mm vs. 1.6 ± 0.2 mm; p < 0.05; 0.4 ± 0.1 mm sham animals), TGF-β, and downstream phosphorylated extracellular-signal-regulated kinase and EMT (27.2 ± 12.0% vs. 51.6 ± 11.7% α-smooth muscle actin-positive endothelial cells, p < 0.05; 7.2 ± 3.5% sham animals), cellular proliferation, collagen deposition, endothelial cell activation (vascular cell adhesion molecule-1 expression), neovascularization, and cells positive for cluster of differentiation (CD) 45, a hematopoietic marker associated with post-MI valve fibrosis. Leaflet area increased comparably (17%) in constrained and losartan

  5. Postoperative warfarin following mitral valve repair or bioprosthetic valve replacement.

    PubMed

    Thourani, Vinod H; Gunter, Rebecca L; Hurst, Stuart; Kilgo, Patrick; Padala, Murali; Puskas, John D; Lattouf, Omar M; Halkos, Michael E; Guyton, Robert A

    2013-09-01

    Short-term postoperative warfarin therapy has been used to decrease neurologic events following mitral valve repair or bioprosthetic replacement (MVR). The study aim was to compare the short- and long-term outcomes of patients undergoing mitral valve surgery with or without short-term postoperative warfarin. A single academic US institution retrospective review was performed on discharged patients who underwent MVR between January 1996 and March 2010. Patients were allocated to two groups: MVR with four to six weeks of postoperative warfarin (n = 315; Warfarin group) or MVR without postoperative warfarin (n = 257; No warfarin group). Patients who required either preoperative or postoperative warfarin for any disease process (e.g., atrial fibrillation, mechanical valve, deep venous thrombosis) were excluded. Logistic and Cox proportional hazards regression models were constructed to evaluate the effects of warfarin on short- and long-term outcomes, respectively. Adjusted odds ratios (AOR) and adjusted hazard ratios (AHR), with 95% confidence intervals (CI) were constructed for each outcome. To reduce selection bias, propensity scoring methods were employed to balance the groups with respect to 54 preoperative variables. Mean age was not significantly different between groups (No warfarin group = 56.8 +/- 14.5 years versus Warfarin group 55.9 +/- 12.9 years; p = 0.46). The average length of hospital stay was 9.8 +/- 8.4 days and 7.3 +/- 4.5 days in the No warfarin and Warfarin groups, respectively (p < 0.001). At the six-week follow up the incidences of stroke (p = 0.74), pleural effusions (p = 0.88), pericardial effusions (p = 0.75), and bleeding complications (p = 0.30) were similar between the two groups. In an unadjusted Kaplan-Meier analysis, the No warfarin group had a poorer long-term survival than the Warfarin group (p < 0.001). However, after propensity adjustment, the benefit of warfarin was not statistically significant (AHR = 0.66, 95% CI 0.40-1.08, p = 0

  6. Enclosed rotary disc air pulser

    DOEpatents

    Olson, A. L.; Batcheller, Tom A.; Rindfleisch, J. A.; Morgan, John M.

    1989-01-01

    An enclosed rotary disc air pulser for use with a solvent extraction pulse olumn includes a housing having inlet, exhaust and pulse leg ports, a shaft mounted in the housing and adapted for axial rotation therein, first and second disc members secured to the shaft within the housing in spaced relation to each other to define a chamber therebetween, the chamber being in communication with the pulse leg port, the first disc member located adjacent the inlet port, the second disc member being located adjacent the exhaust port, each disc member having a milled out portion, the disc members positioned on the shaft so that as the shaft rotates, the milled out portions permit alternative cyclical communication between the inlet port and the chamber and the exhaust port and the chamber.

  7. Heat distribution in disc brake

    NASA Astrophysics Data System (ADS)

    Klimenda, Frantisek; Soukup, Josef; Kampo, Jan

    2016-06-01

    This article is deals by the thermal analysis of the disc brake with floating caliper. The issue is solved by numerically. The half 2D model is used for solution in program ADINA 8.8. Two brake discs without the ventilation are solved. One disc is made from cast iron and the second is made from stainless steel. Both materials are an isotropic. By acting the pressure force on the brake pads will be pressing the pads to the brake disc. Speed will be reduced (slowing down). On the contact surface generates the heat, which the disc and pads heats. In the next part of article is comparison the maximum temperature at the time of braking. The temperatures of both materials for brake disc (gray cast iron, stainless steel) are compares. The heat flux during braking for the both materials is shown.

  8. Evolution of gas in debris discs

    NASA Astrophysics Data System (ADS)

    Kral, Quentin; Wyatt, Mark; Pringle, Jim

    2015-12-01

    A non negligible quantity of gas has been discovered in an increasing number of debris disc systems. ALMA high sensitivity and high resolution is changing our perception of the gaseous component of debris discs as CO is discovered in systems where it should be rapidly photodissociated. It implies that there is a replenishment mechanism and that the observed gas is secondary. Past missions such as Herschel probed the atomic part of the gas through O I and C II emission lines. Gas science in debris discs is still in its infancy, and these new observations raise a handful of questions concerning the mechanisms to create the gas and about its evolution in the planetary system when it is released. The latter question will be addressed in this talk as a self-consistent gas evolution scenario is proposed and is compared to observations for the peculiar case of β Pictoris.Our model proposes that carbon and oxygen within debris discs are created due to photodissociation of CO which is itself created from the debris disc dust (due to grain-grain collisions or photodesorption). The evolution of the carbon atoms is modelled as viscous spreading, with viscosity parameterised using an α model. The temperature, ionisation fraction and population levels of carbon are followed with a PDR model called Cloudy, which is coupled to the dynamical viscous α model. Only carbon gets ionised due to its lower ionisation potential than oxygen. The carbon gas disc can end up with a high ionisation fraction due to strong FUV radiation field. A high ionisation fraction means that the magnetorotational instability (MRI) is very active, so that α is very high. Gas density profiles can be worked out for different input parameters such as the α value, the CO input rate, the location of the input and the incoming radiation field. Observability predictions can be made for future observations, and our model is tested on β Pictoris observations. This new gas evolution model fits the carbon and CO

  9. Effects of acute ischemic mitral regurgitation on three-dimensional mitral leaflet edge geometry.

    PubMed

    Bothe, Wolfgang; Nguyen, Tom C; Ennis, Daniel B; Itoh, Akinobu; Carlhäll, Carl Johan; Lai, David T; Ingels, Neil B; Miller, D Craig

    2008-02-01

    Improved quantitative understanding of in vivo leaflet geometry in ischemic mitral regurgitation (IMR) is needed to improve reparative techniques, yet few data are available due to current imaging limitations. Using marker technology we tested the hypotheses that IMR (1) occurs chiefly during early systole; (2) affects primarily the valve region contiguous with the myocardial ischemic insult; and (3) results in systolic leaflet edge restriction. Eleven sheep had radiopaque markers sutured as five opposing pairs along the anterior (A(1)-E(1)) and posterior (A(2)-E(2)) mitral leaflet free edges from the anterior commissure (A(1)-A(2)) to the posterior commissure (E(1)-E(2)). Immediately postoperatively, biplane videofluoroscopy was used to obtain 4D marker coordinates before and during acute proximal left circumflex artery occlusion. Regional mitral orifice area (MOA) was calculated in the anterior (Ant-MOA), middle (Mid-MOA), and posterior (Post-MOA) mitral orifice segments during early systole (EarlyS), mid systole (MidS), and end systole (EndS). MOA was normalized to zero (minimum orifice opening) at baseline EndS. Tenting height was the distance of the midpoint of paired markers to the mitral annular plane at EndS. Acute ischemia increased echocardiographic MR grade (0.5+/-0.3 vs 2.3+/-0.7, p<0.01) and MOA in all regions at EarlyS, MidS, and EndS: Ant-MOA (7+/-10 vs 22+/-19 mm(2), 1+/-2 vs 18+/-16 mm(2), 0 vs 17+/-15 mm(2)); Mid-MOA (9+/-13 vs 25+/-17 mm(2), 3+/-6 vs 21+/-19 mm(2), 0 vs 25+/-17 mm(2)); and Post-MOA (8+/-10 vs 25+/-16, 2+/-4 vs 22+/-13 mm(2), 0 vs 23+/-13 mm(2)), all p<0.05. There was no change in MOA throughout systole (EarlyS vs MidS vs EndS) during baseline conditions or ischemia. Tenting height increased with ischemia near the central and the anterior commissure leaflet edges (B(1)-B(2): 7.1+/-1.8mm vs 7.9+/-1.7 mm, C(1)-C(2): 6.9+/-1.3mm vs 8.0+/-1.5mm, both p<0.05). MOA during ischemia was larger throughout systole, indicating that acute IMR

  10. EFFECTS OF ACUTE ISCHEMIC MITRAL REGURGITATION ON THREE DIMENSIONAL MITRAL LEAFLET EDGE GEOMETRY

    PubMed Central

    Bothe, Wolfgang; Nguyen, Tom C.; Ennis, Daniel B.; Itoh, Akinobu; Carlhäll, Carl Johan; Lai, David T.; Ingels, Neil B.; Miller, D. Craig

    2008-01-01

    Background: Improved quantitative understanding of in-vivo leaflet geometry in ischemic mitral regurgitation (IMR) is needed to improve reparative techniques, yet few data are available due to current imaging limitations. Using marker technology we tested the hypotheses that IMR: (1) Occurs chiefly during early-systole; (2) Affects primarily the valve region contiguous with the myocardial ischemic insult; and, (3) Results in systolic leaflet edge restriction. Methods: Eleven sheep had radiopaque markers sutured as five opposing pairs along the anterior (A1-E1) and posterior (A2-E2) mitral leaflet free-edges from the anterior commissure (A1-A2) to the posterior commissure (E1-E2). Immediately postoperatively, biplane videofluoroscopy was used to obtain 4-D marker coordinates before and during acute proximal left circumflex artery occlusion. Regional mitral orifice area (MOA) was calculated in the anterior (Ant-MOA), middle (Mid-MOA) and posterior (Post-MOA) mitral orifice segments during early-systole (EarlyS), mid-systole (MidS), and end-systole (EndS). MOA was normalized to zero (minimum orifice opening) at baseline EndS. Tenting height was the distance of the midpoint of paired markers to the mitral annular plane at EndS. . Results: Acute ischemia increased echocardiographic MR grade (0.5±0.3 vs. 2.3±0.7, p<0.01) and MOA in all regions at EarlyS, MidS and EndS: Ant-MOA (7±10 vs. 22±19mm2, 1±2 vs. 18±16mm2, 0 vs. 17±15mm2); Mid-MOA (9±13 vs. 25±17mm2, 3±6 vs. 21±19mm2, 0 vs. 25±17mm2); and Post-MOA (8±10 vs. 25±16, 2±4 vs. 22±13mm2, 0 vs. 23±13mm2), all p<0.05. There was no change in MOA throughout systole (EarlyS vs. MidS vs. EndS) during baseline conditions or ischemia. Tenting height increased with ischemia near the central and the anterior commissure leaflet edges (B1-B2: 7.1±1.8mm vs. 7.9±1.7mm, C1-C2: 6.9±1.3mm vs. 8.0±1.5mm, both p<0.05). Conclusions: (1) MOA during ischemia was larger throughout systole, indicating that acute IMR in

  11. TGF-β signalling and reactive oxygen species drive fibrosis and matrix remodelling in myxomatous mitral valves.

    PubMed

    Hagler, Michael A; Hadley, Thomas M; Zhang, Heyu; Mehra, Kashish; Roos, Carolyn M; Schaff, Hartzell V; Suri, Rakesh M; Miller, Jordan D

    2013-07-01

    Myxomatous mitral valve disease (MMVD) is associated with leaflet thickening, fibrosis, matrix remodelling, and leaflet prolapse. Molecular mechanisms contributing to MMVD, however, remain poorly understood. We tested the hypothesis that increased transforming growth factor-β (TGF-β) signalling and reactive oxygen species (ROS) are major contributors to pro-fibrotic gene expression in human and mouse mitral valves. Using qRT-PCR, we found that increased expression of TGF-β1 in mitral valves from humans with MMVD (n = 24) was associated with increased expression of connective tissue growth factor (CTGF) and matrix metalloproteinase 2 (MMP2). Increased levels of phospho-SMAD2/3 (western blotting) and expression of SMAD-specific E3 ubiquitin-protein ligases (SMURF) 1 and 2 (qRT-PCR) suggested that TGF-β1 signalling occurred through canonical signalling cascades. Oxidative stress (dihydroethidium staining) was increased in human MMVD tissue and associated with increases in NAD(P)H oxidase catalytic subunits (Nox) 2 and 4, occurring despite increases in superoxide dismutase 1 (SOD1). In mitral valves from SOD1-deficient mice, expression of CTGF, MMP2, Nox2, and Nox4 was significantly increased, suggesting that ROS can independently activate pro-fibrotic and matrix remodelling gene expression patterns. Furthermore, treatment of mouse mitral valve interstitial cells with cell permeable antioxidants attenuated TGF-β1-induced pro-fibrotic and matrix remodelling gene expression in vitro. Activation of canonical TGF-β signalling is a major contributor to fibrosis and matrix remodelling in MMVD, and is amplified by increases in oxidative stress. Treatments aimed at reducing TGF-β activation and oxidative stress in early MMVD may slow progression of MMVD.

  12. Fluid-Structure Interaction Analysis of Papillary Muscle Forces Using a Comprehensive Mitral Valve Model with 3D Chordal Structure.

    PubMed

    Toma, Milan; Jensen, Morten Ø; Einstein, Daniel R; Yoganathan, Ajit P; Cochran, Richard P; Kunzelman, Karyn S

    2016-04-01

    Numerical models of native heart valves are being used to study valve biomechanics to aid design and development of repair procedures and replacement devices. These models have evolved from simple two-dimensional approximations to complex three-dimensional, fully coupled fluid-structure interaction (FSI) systems. Such simulations are useful for predicting the mechanical and hemodynamic loading on implanted valve devices. A current challenge for improving the accuracy of these predictions is choosing and implementing modeling boundary conditions. In order to address this challenge, we are utilizing an advanced in vitro system to validate FSI conditions for the mitral valve system. Explanted ovine mitral valves were mounted in an in vitro setup, and structural data for the mitral valve was acquired with [Formula: see text]CT. Experimental data from the in vitro ovine mitral valve system were used to validate the computational model. As the valve closes, the hemodynamic data, high speed leaflet dynamics, and force vectors from the in vitro system were compared to the results of the FSI simulation computational model. The total force of 2.6 N per papillary muscle is matched by the computational model. In vitro and in vivo force measurements enable validating and adjusting material parameters to improve the accuracy of computational models. The simulations can then be used to answer questions that are otherwise not possible to investigate experimentally. This work is important to maximize the validity of computational models of not just the mitral valve, but any biomechanical aspect using computational simulation in designing medical devices.

  13. RT 3D TEE: Characteristics of Mitral Valve in Ischemic Mitral Regurgitation Evaluated by MVQ Program

    PubMed Central

    Kovalova, Sylva; Necas, Josef

    2011-01-01

    Aim To assess the changes of mitral valve (MV) in ischemic mitral regurgitation (IMR) using Mitral Valve Quantification (MVQ) program. Methods We examined 46 patients (18 women) with IMR aged 45-86 and a control group of 33 healthy individuals (14 women) aged 18-88. Following parameters were assessed: Area of minimal surface spanning annulus (A3), annulus height (h), tenting height (Th), exposed area of anterior (AL), posterior (PL) and both leaflets (BL), ejection fraction of the left ventricle (LV EF), regurgitation volume (RV) and BL/A3, AL/A3, PL/A3 ratios. The normal range of BL/A3 ratio was defined as the average ± 2SD of control group. The study group was separated into subgroup 1 with BL/A3 ratio within normal values and subgroup 2 with pathological BL/A3 ratio. Corresponding parameters of IMR group were compared to the controls and both subgroups were comp