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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Vergleich echokardiographischer transthorakaler Befunde vor und nach Mitralklappenrekonstruktion

Langel, Martin 31 August 2016 (has links) (PDF)
In der vorliegenden Studie wurden die prä- und postoperativen transthorakalen echokardiographischen Untersuchungen von 31 Patienten mit Mitralklappenrekonstruktion im Zeitraum von 2007 bis 2011 retrospektiv analysiert. Es wurden die Untersuchungen eingeschlossen, bei denen sowohl vor als auch nach dem operativen Eingriff das Bilddatenmaterial komplett zur Verfügung stand. Die echokardiographische Dokumentation der im klinischen Alltag durchgeführten Untersuchungen ermöglichte die Evaluation der Dimensionen von rechten und linken Ventrikel sowie beider Vorhöfe, der systolischen und diastolischen linksventrikulären Funktion, der Morphologie der Herzklappen sowie der pulmonalarteriellen Drücke. Die Patientenkohorte wurde zusätzlich in Subgruppen nach Symptomatik, nach additiven chirurgischen Interventionen und nach dem Vorliegen von chronischem Vorhofflimmern analysiert. Die Ergebnisse der Mitralklappenrekonstruktion zeigten erwartungsgemäß postoperativ eine signifikante Reduktion des Schweregrades der Mitralklappenregurgitation, eine Verkleinerung der linksseitigen Herzhöhlen, eine Normalisierung der linksventrikulären Pumpfunktion und der pulmonalarteriellen Drücke. Asymptomatische Patienten im Sinusrhythmus mit isolierter Mitralklappenrekonstruktion hatten die günstigsten postoperativen echokardiographischen Ergebnisse. Weiterhin war eine postoperativ eingeschränkte rechtsventrikuläre und linksventrikuläre diastolische Funktion zu postulieren. Ein mit fast 20% beträchtlicher Anteil der Patienten mit einer postoperativen Vena contracta der Mitralklappenregurgitation ≥ 3mm war vermutlich auf eine Vorselektion der Patienten zurückzuführen. Schlussfolgernd sollte eine Mitralklappenrekonstruktion möglichst vor Eintreten irreversibler kardialer Schädigungen durchgeführt werden.
2

Développement d’un système magnétique d’assistance à la coaptation valvulaire cardiaque : étude de faisabilité / Experimental use of magnets in cardiac valve repair

Laali, Mojgan 14 November 2011 (has links)
Les valvulopathies cardiaques sont des maladies cardiaques fréquentes. Certaines se traduisent par un manque de coaptation des valves, on désigne ce type de pathologie sous le terme d’insuffisance. Le traitement standard de ces valvulopathies consiste à remplacer les valves malades par des valves prothétiques. L'absence de substitut valvulaire idéal et les inconvénients inhérents au matériel prothétique et à la nécessité d’un traitement anticoagulant, incitent à favoriser, chaque fois que cela est possible, les techniques de chirurgie conservatrice des valves. Actuellement, la réparation de la valve aortique demeure un défi chirurgical. En revanche en ce qui concerne la valve mitrale une réparation est plus souvent réalisable. Cependant, la faisabilité et le résultat final, dépends du mécanisme de la fuite, de l’extension des lésions ainsi que de la technique de réparation chirurgicale utilisée. C’est pour tenter de surmonter tous ces obstacles qu’est né le projet d’étude des forces magnétiques d’aimants permanents comme traitement complémentaire à une plastie ou comme traitement exclusif, pour rétablir une coaptation valvulaire efficace. Pour concrétiser cette idée, nous avons réalisé notre recherche en trois étapes essentielles : 1- La conception d’un système magnétique d’aide à la coaptation. 2- Une étude de faisabilité portant sur la vérification du fonctionnement des aimants in vitro et in vivo. 3- La vérification de l’efficacité de la force magnétique pour atteindre la coaptation nécessaire pour corriger l’insuffisance valvulaire. Cette recherche a été réalisée en étroite collaboration entre le service de Chirurgie Thoracique et Cardio-vasculaire du groupe hospitalier Pitié-Salpêtrière à Paris et le groupe de recherche électrodynamique - GREM3 - du Laboratoire LAPLACE à Toulouse. Les aimants ont été fabriqués en tenant compte des facteurs suivants : la biocompatibilité, la conservation de l'aimantation en milieu sanguin, la flexibilité mécanique des éléments implantés, et la nécessité de stérilisation. L'une des préoccupations principales était d’obtenir une force magnétique adaptée pour fermer la valve et permettre son ouverture en fonction du cycle cardiaque. Dans un deuxième temps, sur la base des concepts précédemment décrits, et après réalisation des tests in vitro, une étude expérimentale a été réalisée in vivo en vue de démontrer la faisabilité du projet. Cette phase d’expérimentation animale a consisté en l’implantation d’aimants permanents sur la valve aortique chez sept moutons gardés en vie pendant 3 mois. Les résultats ont été satisfaisants : aucun prolapsus iatrogène, parfaite bio-tolérance des aimants implantés sans nécessité de traitement anticoagulant, absence de réaction inflammatoire visible à l’autopsie après sacrifice des moutons au troisième mois postopératoire. En dernier lieu, afin d’étudier la valeur de la force magnétique nécessaire pour atteindre la coaptation souhaitée dans l’insuffisance valvulaire, trois modèles d’aimants ont été implantés chez quatre moutons. Malheureusement les résultats n’ont pas été entièrement satisfaisants. Actuellement, forts des enseignements tirés de ces expériences, nous tentons d’améliorer le problème de fabrication des aimants ; de nouveaux aimants sont en cours de réalisation. A notre connaissance, l’utilisation de la force magnétique pour corriger l'insuffisance valvulaire n'a jamais été rapportée dans la littérature. Même si la phase d’expérimentation des aimants destinés à traiter ces insuffisances valvulaires n’est pas arrivée à son terme, nous avons montré la faisabilité du concept sur valve saine. Ce champ d'investigation doit continuer à être exploré compte tenu des avantages qu’ont ces aimants. D’une part, ils sont techniquement faciles à poser et pourraient donc permettre de réaliser une réparation rapide et reproductible des valves. D’autre part, en raison de cette simplicité, on pourrait envisager une implantation par voie percutanée exclusive, ouvrant alors une voie nouvelle, en matière de chirurgie conservatrice des insuffisances valvulaires cardiaques (aortique et mitrale). / Valvular heart diseases are important cardiac pathology and valvular heart insufficiency is one of them. The standard treatment is valve replacement with prosthetic valve. Lacks of ideal prosthetic valve and the drawbacks inherent in prosthetic material and anticoagulant therapy, encourage us to develop techniques of conservative surgery of the valve. Today, repair of the aortic valve remains a surgical challenge, but mitral valve repair is frequently possible. However, the result and possibility of repair depends on the mechanism of insufficiency and the extension of the lesion of the mitral valve. For overcoming all these obstacles, we proposed the theory to study of the magnetic forces of permanent magnets as an adjuvant, or as exclusive treatment to restore effective valve coaptation. To realize this idea, we based our research on three steps: 1 - Characterization of magnets required. 2 - Feasibility study of the magnets in vitro and in vivo 3 - Verification of the effectiveness of the magnetic force to achieve the desired coaptation in valvular insufficiency. This research is done in collaboration between the department of Thoracic and Cardiovascular surgery of Pitié-Salpêtrière hospital in Paris and the research group Electrodynamics - GREM3 LAPLACE Laboratory in Toulouse. The magnets were fabricated by taking into account the following factors: lowprofile and permanency; biocompatibility; the conservation of magnetization in a blood medium; mechanical flexibility of the implanted elements; and the possibility of sterilization. One of the main concerns was to elaborate the adapted intensity of the magnetic force, such that it would be sufficiently strong to close the valve, yet be weak enough to allow valve opening during cardiac cycle. To assess the feasibility, before conducting experiments in animals, in vitro data were obtained and judged appropriate by using a circulating pig heart model with a paracorporeal pneumatic (Thoratec®) ventricular assist device. The phase of animal testing was carried out by the establishment of three permanent magnets on the aortic valve in seven sheep kept alive for 3 months and the results were satisfactory: - No iatrogenic prolepses, - Perfect bio-tolerance without the need for anticoagulation - No visible inflammatory reaction at autopsy on the third postoperative month. Finally, to study the effectiveness of the magnetic force to achieve the desired coaptation in valvular insufficiency, three models of magnets have been tested on 4 sheep, but the results were not satisfactory. Currently we try to solve the problem and new magnets are by the way of conception. To our knowledge, the use of magnetic force to correct valvular incompetence has never been reported. Even if the experimental phase of magnets for treating valvular insufficiency has not reached its conclusion, we demonstrated the feasibility of the concept of healthy valve. This field of investigation must continue to be explored because the magnets have several advantages. On the one hand, they are technically easy to perform, and could thus allow a rapid repair. On the other hand, because of this simplicity, we could consider a percutaneous implantation, which will open a new way for conservative surgery in valvular insufficiency.
3

Value of Robotically Assisted Surgery for Mitral Valve Disease

Koprivanac, Marijan 23 August 2013 (has links)
No description available.
4

A modified Park's stitch to correct aortic insufficiency for bioprosthetic valve at time of left ventricular assist device implant: a case report

Kazui, Toshinobu, Sydow, Nicole, Friedman, Mark, Kim, Samuel, Lick, Scott, Khalpey, Zain 30 November 2016 (has links)
Background: Aortic valve insufficiency (AI) at the time of left ventricular assist device (LVAD) insertion needs to be corrected, however there is little known about how to manage bioprosthetic valvular AI. Case presentation: A 55-year-old female with dilated cardiomyopathy who previously had a bioprosthetic aortic valve replacement needed a LVAD as a bridge to transplant. Her left ventricular ejection fraction was 10% and had mild to moderate transvalvular AI. She underwent a HeartWare HVAD insertion along with aortic valvular coaptation stitch repair (Park's stitch) to the bioprosthetic valve. Conclusion: Her AI improved to trivial with minimal ejection through the bioprosthetic valve. She was transplanted 6 months following the surgery. A Park's stitch to the bioprosthetic aortic valve with more than mild AI might be a good option for bridge to transplant patient.
5

Mitral valve force balance: a quantitative assessment of annular and subvalvular forces

Siefert, Andrew William 08 June 2015 (has links)
In vitro and in vivo models were proposed to evaluate the effects of ischemic mitral regurgitation and surgical repair on the function and mechanics of the heart’s mitral valve. In specific aim 1, a novel transducer was developed to measure the radially directed forces that may act on devices implanted to the mitral annulus. In an ovine model, radial forces were found to statistically increase with left ventricular pressure and were reduced in the setting of ischemic mitral regurgitation. In specific aim 2, the suture forces required to constrain true-sized and undersized annuloplasty rings to the mitral annulus of ovine animals was evaluated. Suture forces were observed to be larger on the anterior aspect of the rings and were elevated with annular undersizing. In specific aim 3, an in vitro simulator’s ability to mimic healthy and ischemic mitral regurgitation ovine mitral valve function was evaluated. After understanding the accuracy of the model, the in vitro ischemic mitral regurgitation model was used to evaluate the progressive effects of annuloplasty on strut and intermediary chordal tethering. The generated data and knowledge will contribute to the development of more durable devices and techniques to assess the significant clinical burden known as ischemic mitral regurgitation.
6

Barlow’s Mitral Valve Disease: A Comparison of Neochordal (Loop) and Edge-To-Edge (Alfieri) Minimally Invasive Repair Techniques

da Rocha e Silva, Jaqueline Grace 04 January 2016 (has links)
Background. Barlow’s mitral valve (MV) disease re- mains a surgical challenge. We compared short- and medium-term outcomes of neochordal (“loop”) versus edge-to-edge (“Alfieri”) minimally invasive MV repair in patients with Barlow’s disease. Methods. From January 2009 to April 2014, 123 consecutive patients with Barlow’s disease (defined as bileaflet billowing or prolapse [or both], excessive leaflet tissue, and annular dilatation with or without calcifica- tion) underwent minimally invasive MV operations for severe mitral regurgitation (MR) at our institution. Three patients (2.4%) underwent MV replacement during the study period and were excluded from subsequent anal- ysis. The loop MV repair technique was used in 68 pa- tients (55.3%) and an edge-to-edge repair was performed in 44 patients (35.8%). Patients who underwent a combi- nation of these 2 techniques (n [ 8 [6.5%]) were excluded. The median age was 48 years, and 62.5% of patients were men. Concomitant procedures included closure of a patent foramen ovale or atrial septal defect (n [ 19), tricuspid valve repair (n [ 5), and atrial fibril- lation ablation (n [ 15). Follow-up was performed 24.7 ± 17 months postoperatively and was 98% complete. Results. No deaths occurred perioperatively or during follow-up. Aortic cross-clamp time (64.1 ± 17.6 minutes versus 95.9 ± 29.5 minutes) and cardiopulmonary bypass (CPB) time (110.0 ± 24.2 minutes versus 146.4 ± 39.1 mi- nutes) were significantly shorter (p < 0.001) in patients who received edge-to-edge repair. Although patients who underwent edge-to-edge repair received a larger annulo- plasty ring (38.6 ± 1.5 mm versus 35.8 ± 2.7 mm; p < 0.001), the early postoperative resting mean gradients were higher(3.3±1.2mmHgversus2.6±1.2mmHg;p[ 0.007) and the mitral orifice area tended to be smaller in this group (2.8 ± 0.7 cm2 versus 3.0 ± 0.7 cm2; p [ 0.06). The amount of residual MR was similar between groups (0.3 ± 0.6 versus 0.6 ± 1.0 for edge-to-edge versus loop procedures, respectively; p [ 0.08). More than mild MR requiring early MV reoperation was present in 3 patients who underwent loop procedures (4.4%) and in no patients who had edge-to-edge procedures (p [ 0.51). During follow-up, 2 patients (1 in each group) required MV replacement for severe MR. The 4-year freedom from MV reoperation was 92.8% ± 5.0% in the Alfieri group compared with 90.9% ± 4.6% in the loop group (p [ 0.94). Conclusions. Minimally invasive MV repair can be accomplished with excellent early and medium-term outcomes in patients with Barlow’s disease. The edge- to-edge (Alfieri) repair can be performed with reduced operative times when compared with the loop technique, but it results in mildly increased transvalvular gradients and mildly decreased valve opening areas without any difference in residual MR.
7

Outcome after mitral valve surgery for mitral valve regurgitation

Heikkinen, J. (Jouni) 08 January 2008 (has links)
Abstract The repair of degenerative mitral valve regurgitation has been shown to be an effective procedure with durable results. The techniques for mitral valve repair are not completely risk-free for late failure, and the identification of factors associated with this increased risk is of clinical relevance as it permits an appropriate selection of patients for whom mitral valve surgery should be offered and by which technique. The European system for cardiac operative risk evaluation score (EuroSCORE) has been used and demonstrated worldwide to be a valid tool for the prediction of immediate postoperative outcome after coronary artery bypass surgery. There are only a few studies which examine its value in heart valve surgery. Mitral valve repair has been shown to be associated with significant improvement in terms of functional capacity, but the late quality of life in these patients has not been adequately assessed, and there is no data on the quality of life of long-term survivors. The study population consisted of two groups of patients operated on at our institution. The first group included 164 patients who underwent isolated or combined mitral valve repair for mitral valve regurgitation during the period 1993 to 2000, while the second group consisted of 207 patients who underwent mitral valve repair (164 patients) or replacement (43 patients) for isolated mitral valve regurgitation during the same time-period. The first study aimed to identify preoperative variables which may have impact on the 30-day postoperative outcome. In the second study, the long-term outcome after mitral valve repair was evaluated in order to identify the risk factors associated with late failures. The third study analyzed quality of life after valve repair and compared it to that of an age- and gender-adjusted Finnish general population. In the fourth study, the validity of EuroSCORE was tested in predicting the immediate and late outcome of patients who had undergone mitral valve repair or replacement for isolated valve regurgitation. Patient age, a history of prior cardiac surgery and NYHA functional class were independent predictors of poor outcome. A residual regurgitation grade of more than one immediately after primary repair and chronic pulmonary disease were independent predictors of mitral valve reoperation. After valve repair, quality of life was similar to the age- and sex-adjusted general Finnish population. Both additive and logistic EuroSCOREs were predictors of the immediate and late outcomes of patients after surgery for mitral valve regurgitation.
8

Evaluating the Feasibility and Effectiveness of a Measurement Device to Be Used Intraoperatively During Aortic Valve Repair

Qureshi, Rohail 27 October 2021 (has links)
The ability to accurately and in a repeatable fashion, measure aortic valve dimensions during aortic valve repair is critical to the restoration of function in a diseased aortic valve, as for example in aortic insufficiency. Although several methods for measuring aortic valve dimensions have been shown to be feasible, they are approximate and lack the accuracy, robustness, and repeatability one would expect to support aortic valve repair surgery. In addition, they do not allow for the intra-operative measurement of aortic valves under conditions equivalent to the physiological (pressurized) state. A prototype medical device was designed, and 3-D printed at the University of Ottawa that would allow cardiac surgeons performing aortic valve repair to do just that. The prototype was tested for its accuracy and precision at the University of Ottawa Heart Institute using porcine aortic valves. Based on unsatisfactory results of this experimentation, namely, that the device was applying forces that were too large, a numerical simulation study was designed using a commercial finite element software LS-DYNA. This simulation study was used to explore the forces that the prototype device needed to apply to obtain end-diastolic pressurized dimensions of the aortic valve. The simulation study showed that one single device was likely not possible to obtain measurements in an aortic valve. However, a system of two devices could be imagined, one to measure the STJ diameter and free margin length of the aortic valve cusps, and one to measure the cusp height of the same valve, for the purposes of aortic valve repair.
9

Vergleich echokardiographischer transthorakaler Befunde vor und nach Mitralklappenrekonstruktion

Langel, Martin 18 August 2016 (has links)
In der vorliegenden Studie wurden die prä- und postoperativen transthorakalen echokardiographischen Untersuchungen von 31 Patienten mit Mitralklappenrekonstruktion im Zeitraum von 2007 bis 2011 retrospektiv analysiert. Es wurden die Untersuchungen eingeschlossen, bei denen sowohl vor als auch nach dem operativen Eingriff das Bilddatenmaterial komplett zur Verfügung stand. Die echokardiographische Dokumentation der im klinischen Alltag durchgeführten Untersuchungen ermöglichte die Evaluation der Dimensionen von rechten und linken Ventrikel sowie beider Vorhöfe, der systolischen und diastolischen linksventrikulären Funktion, der Morphologie der Herzklappen sowie der pulmonalarteriellen Drücke. Die Patientenkohorte wurde zusätzlich in Subgruppen nach Symptomatik, nach additiven chirurgischen Interventionen und nach dem Vorliegen von chronischem Vorhofflimmern analysiert. Die Ergebnisse der Mitralklappenrekonstruktion zeigten erwartungsgemäß postoperativ eine signifikante Reduktion des Schweregrades der Mitralklappenregurgitation, eine Verkleinerung der linksseitigen Herzhöhlen, eine Normalisierung der linksventrikulären Pumpfunktion und der pulmonalarteriellen Drücke. Asymptomatische Patienten im Sinusrhythmus mit isolierter Mitralklappenrekonstruktion hatten die günstigsten postoperativen echokardiographischen Ergebnisse. Weiterhin war eine postoperativ eingeschränkte rechtsventrikuläre und linksventrikuläre diastolische Funktion zu postulieren. Ein mit fast 20% beträchtlicher Anteil der Patienten mit einer postoperativen Vena contracta der Mitralklappenregurgitation ≥ 3mm war vermutlich auf eine Vorselektion der Patienten zurückzuführen. Schlussfolgernd sollte eine Mitralklappenrekonstruktion möglichst vor Eintreten irreversibler kardialer Schädigungen durchgeführt werden.
10

Cardiac output states in patients with severe functional tricuspid regurgitation: impact on treatment success and prognosis

Unterhuber, Matthias, Kresoja, Karl-Patrik, Besler, Christian, Rommel, Karl-Philipp, Orban, Mathias, von Roeder, Maximilian, Braun, Daniel, Stolz, Lukas, Massberg, Steffen, Trebicka, Jonel, Zachäus, Markus, Hausleiter, Jörg, Thiele, Holger, Lurz, Philipp 05 June 2023 (has links)
Aims To investigate whether there is evidence for distinct cardiac output (CO) based phenotypes in patients with chronic right heart failure associated with severe tricuspid regurgitation (TR) and to characterize their impact on TR treatment and outcome. Methods and results A total of 132 patients underwent isolated transcatheter tricuspid valve repair (TTVR) for functional TR at two centres. Patients were clustered according to k-means clustering into low [cardiac index (CI) < 1.7 L/min/m2], intermediate (CI 1.7–2.6 L/min/m2) and high CO (CI > 2.6 L/min/m2) clusters. All-cause mortality and clinical characteristics during follow-up were compared among different CO clusters. Mortality rates were highest for patients in a low (24%) and high CO state (42%, log-rank P < 0.001). High CO state patients were characterized by larger inferior vena cava diameters (P = 0.003), reduced liver function, higher incidence of ascites (P = 0.006) and markedly reduced systemic vascular resistance (P < 0.001) as compared to TTVR patients in other CO states. Despite comparable procedural success rates, the extent of changes in right atrial pressures (P = 0.01) and right ventricular dimensions (P < 0.001) per decrease in regurgitant volume following TTVR was less pronounced in high CO state patients as compared to other CO states. Successful TTVR was associated with the smallest prognostic benefit among low and high CO state patients. Conclusions Patients with chronic right heart failure and severe TR display distinct CO states. The high CO state is characterized by advanced congestive hepatopathy, a substantial decrease in peripheral vascular tone, a lack of response of central venous pressures to TR reduction, and worse prognosis. These data are relevant to the pathophysiological understanding and management of this important clinical syndrome. Graphical Abstract Proposed mechanism of hypercirculatory tricuspid regurgitation. Tricuspid regurgitation related backward failure causes liver congestion and dysfunction with portal hypertension and reduced washout of vasoactive substances. Consequent splanchnic and peripheral vasodilatation alongside with reduced renal blood flow results in renin–angiotensin–aldosterone system (RAAS) activation and sympathetic overactivation. The sympathetic drive and volume retention lead to further capacitance depletion and volume overload, eventually resulting in a high cardiac output state, with limited preload reduction and prognostic benefit following transcatheter tricuspid valve repair. The alterations in the graph should be interpreted as simultaneous interaction rather than a timeline. Continuous lines indicate findings in the present study. Dashed lines express currently accepted mechanistical considerations. AP, alkaline phosphatase; γGT, gamma-glutamyl-transferase; RA, right atrium; RV, right ventricle.

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