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Journal ArticleDOI

Isolated effect of geometry on mitral valve function for in silico model development.

TL;DR: A ground-truth data-set is generated by quantifying the effects of isolated mitral annular flattening, asymmetric annular dilatation, symmetric papillary muscle (PM) displacement and asymmetric PM displacement on leaflet coaptation, mitral regurgitation (MR) and anterior leaflet strain to improve MV computational models and provide a platform for the development of future surgical planning tools.
Abstract: Computational models for the heart's mitral valve (MV) exhibit several uncertainties that may be reduced by further developing these models using ground-truth data-sets. This study generated a ground-truth data-set by quantifying the effects of isolated mitral annular flattening, symmetric annular dilatation, symmetric papillary muscle (PM) displacement and asymmetric PM displacement on leaflet coaptation, mitral regurgitation (MR) and anterior leaflet strain. MVs were mounted in an in vitro left heart simulator and tested under pulsatile haemodynamics. Mitral leaflet coaptation length, coaptation depth, tenting area, MR volume, MR jet direction and anterior leaflet strain in the radial and circumferential directions were successfully quantified at increasing levels of geometric distortion. From these data, increase in the levels of isolated PM displacement resulted in the greatest mean change in coaptation depth (70% increase), tenting area (150% increase) and radial leaflet strain (37% increase) while a...
Citations
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Journal ArticleDOI
TL;DR: Improvements in the current study to the HCFS permit increasingly accurate study of myocardial mechanics and suggests that the first application of this simulator to abnormal human cardiac function suggests that the authors' novel annuloplasty ring with a sub-valvular element will correct ischemic mitral regurgitation.
Abstract: Ischemic mitral regurgitation is associated with substantial risk of death. We sought to: (1) detail significant recent improvements to the Dassault Systemes human cardiac function simulator (HCFS); (2) use the HCFS to simulate normal cardiac function as well as pathologic function in the setting of posterior left ventricular (LV) papillary muscle infarction; and (3) debut our novel device for correction of ischemic mitral regurgitation. We synthesized two recent studies of human myocardial mechanics. The first study presented the robust and integrative finite element HCFS. Its primary limitation was its poor diastolic performance with an LV ejection fraction below 20% caused by overly stiff ex vivo porcine tissue parameters. The second study derived improved diastolic myocardial material parameters using in vivo MRI data from five normal human subjects. We combined these models to simulate ischemic mitral regurgitation by computationally infarcting an LV region including the posterior papillary muscle. Contact between our novel device and the mitral valve apparatus was simulated using Dassault Systemes SIMULIA software. Incorporating improved cardiac geometry and diastolic myocardial material properties in the HCFS resulted in a realistic LV ejection fraction of 55%. Simulating infarction of posterior papillary muscle caused regurgitant mitral valve mechanics. Implementation of our novel device corrected valve dysfunction. Improvements in the current study to the HCFS permit increasingly accurate study of myocardial mechanics. The first application of this simulator to abnormal human cardiac function suggests that our novel annuloplasty ring with a sub-valvular element will correct ischemic mitral regurgitation.

51 citations

Book ChapterDOI
17 Jan 2006
TL;DR: The most common manifestations of MVP are discussed, a condensed review of current pathophysiologic concepts are provided, and guidelines for diagnostic evaluation and further management are reviewed.
Abstract: nearly 50 years ago,1–3 consists of the displacement of an abnormally thickened, redundant mitral leaflet into the left atrium during systole.4 Initially named Barlow’s syndrome, it also been called billowing mitral cusp syndrome, floppy valve syndrome, systolic click-murmur syndrome, and myxomatous mitral valve. Since the first description was published in 1963, much has been learned about its underlying pathology, natural history, and possible complications, such as bacterial endocarditis, severe mitral regurgitation, and sudden cardiac death.5 Development of echocardiography has provided an ideal tool for studying this valvular abnormality and understanding its 3-dimensional structure.6,7 Results of randomized studies have provided evidence for appropriate medical and surgical interventions. This article discusses the most common manifestations of MVP, provides a condensed review of current pathophysiologic concepts, and reviews guidelines for diagnostic evaluation and further management.

49 citations

Journal ArticleDOI
TL;DR: It is revealed that eccentric distortion of a TAVR stent can have a considerable impact on dynamic leaflet deformation, inducing deleterious bending of the leaflet and increasing commissures strains, which might expedite leaflet structural failure compared to leaflets in a circular deployed valve.
Abstract: Transcatheter aortic valve replacements (TAVRs) are a percutaneous alternative to surgical aortic valve replacements and are used to treat patients with aortic valve stenosis. This minimally invasive procedure relies on expansion of the TAVR stent to radially displace calcified aortic valve leaflets against the aortic root wall. However, these calcium deposits can impede the expansion of the device causing distortion of the valve stent and pericardial tissue leaflets. The objective of this study was to elucidate the impact of eccentric TAVR stent distortion on the dynamic deformation of the tissue leaflets of the prosthesis in vitro. Dual-camera stereophotogrammetry was used to measure the regional variation in strain in a leaflet of a TAVR deployed in nominal circular and eccentric (eccentricity index = 28%) orifices, representative of deployed TAVRs in vivo. It was observed that (i) eccentric stent distortion caused incorrect coaptation of the leaflets at peak diastole resulting in a 'peel-back' leaflet geometry that was not present in the circular valve and (ii) adverse bending of the leaflet, arising in the eccentric valve at peak diastole, caused significantly higher commissure strains compared with the circular valve in both normotensive and hypertensive pressure conditions (normotension: eccentric = 13.76 ± 2.04% versus circular = 11.77 ± 1.61%, p = 0.0014, hypertension: eccentric = 15.07 ± 1.13% versus circular = 13.56 ± 0.87%, p = 0.0042). This study reveals that eccentric distortion of a TAVR stent can have a considerable impact on dynamic leaflet deformation, inducing deleterious bending of the leaflet and increasing commissures strains, which might expedite leaflet structural failure compared to leaflets in a circular deployed valve.

43 citations

Journal ArticleDOI
TL;DR: An overview of relevant mitral valve diseases is presented, the evolution of FE models of surgical valve repair techniques are described, and Computational modeling through finite element (FE) analysis is described.
Abstract: 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.

20 citations

References
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Journal ArticleDOI
TL;DR: MR was found to be an independent predictor of mortality after multivariable analysis and present in those with ischemic and nonischemic cardiomyopathies who underwent cardiac catheterization between 1986 and 2000.
Abstract: The goal of this study was to examine the frequency of mitral regurgitation (MR) in patients with left ventricular (LV) systolic dysfunction and to relate its presence and severity to long-term survival Remodeling of the left ventricle after myocyte injury leads to a progressive change in LV size and shape, and it may lead to the development of MR The frequency of MR and its relation to survival in patients with LV systolic dysfunction has not been completely characterized We analyzed the histories, coronary anatomy, and degree of MR in patients with symptomatic heart failure and LV ejection fraction <40% who underwent cardiac catheterization between 1986 and 2000 Cox's proportional hazards modeling was used to assess the independent effect of MR on survival Two thousand fifty-seven patients met study criteria; MR was common in this cohort (562%) Of patients with MR, 811 (701%) had mild (grades 1+ or 2+) and 345 (298%) had moderate or severe (grades 3+ or 4+) regurgitation Survival rates at 1, 3, and 5 years were significantly lower in patients with moderate to severe MR versus those with mild or no MR (p <0001) MR was found to be an independent predictor of mortality after multivariable analysis (hazards ratio 123, 95% confidence interval 113 to 134, p = 00001) This relation of MR and survival was present in those with ischemic and nonischemic cardiomyopathies MR is common in patients with LV systolic dysfunction and heart failure After adjusting for other clinical variables, the presence of MR independently predicted worsened survival

623 citations


"Isolated effect of geometry on mitr..." refers background in this paper

  • ...This disease is a significant clinical burden with suboptimal long-term survival (Trichon et al. 2003; Borger et al. 2006)....

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Journal ArticleDOI
TL;DR: Functional mitral regurgitation also paradoxically decreases in midsystole, despite peak transmitral driving pressure, suggesting a change in the force balance acting to create a regurgitant orifice, with rising transmitral pressure counteracting forces that restrict leaflet closure.
Abstract: Background Functional mitral regurgitation in patients with ischemic or dilated ventricles has been related to competing factors: altered tension on the leaflets due to displacement of their papillary muscle and annular attachments, which restricts leaflet closure, versus global ventricular dysfunction with reduced transmitral pressure to close the leaflets. In vivo, however, geometric changes accompany dysfunction, making it difficult to study these factors independently. Functional mitral regurgitation also paradoxically decreases in midsystole, despite peak transmitral driving pressure, suggesting a change in the force balance acting to create a regurgitant orifice, with rising transmitral pressure counteracting forces that restrict leaflet closure. In vivo, this mechanism cannot be tested independently of annular contraction that could also reduce midsystolic regurgitation. Methods and Results An in vitro model was developed that allows independent variation of papillary muscle position, annular size,...

375 citations

Journal ArticleDOI
TL;DR: Intermediate-term cutoff values for left ventricular reverse remodeling proved to be predictors for late mortality, and for patients with preoperative LVEDD of 65 mm or less, restrictive mitral annuloplasty with revascularization provides a cure for ischemic mitral regurgitation and heart failure; however, whenLVEDD exceeds 65 mm, outcome is poor and a ventricular approach should be considered.

291 citations


"Isolated effect of geometry on mitr..." refers result in this paper

  • ...When comparing these data with FMR patient cohorts, approximate ranges in patient coaptation length (0.3– 10mm), coaptation depth (3–14mm) and tenting area (0.2–4.2 cm2) are also similar to those observed within this study (Braun et al. 2008; Lee et al. 2009)....

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  • ...2 cm(2)) are also similar to those observed within this study (Braun et al. 2008; Lee et al. 2009)....

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Journal ArticleDOI
TL;DR: Large animal models recapitulating the clinical HF phenotype in large animal models can allow for the translation of basic science discoveries into clinical therapies and translate basic science to clinical applications have successfully traveled the journey from bench to bedside.
Abstract: Congestive heart failure (HF) is a clinical syndrome, with hallmarks of fatigue and dyspnea, that continues to be highly prevalent and morbid. Because of the growing burden of HF as the population ages, the need to develop new pharmacological treatments and therapeutic interventions is of paramount importance. Common pathophysiologic features of HF include changes in left ventricle structure, function, and neurohormonal activation. The recapitulation of the HF phenotype in large animal models can allow for the translation of basic science discoveries into clinical therapies. Models of myocardial infarction/ischemia, ischemic cardiomyopathy, ventricular pressure and volume overload, and pacing-induced dilated cardiomyopathy have been created in dogs, pigs, and sheep for the investigation of HF and potential therapies. Large animal models recapitulating the clinical HF phenotype and translating basic science to clinical applications have successfully traveled the journey from bench to bedside. Undoubtedly, large animal models of HF will continue to play a crucial role in the elucidation of biological pathways involved in HF and the development and refinement of HF therapies.

278 citations

01 Jan 2009
TL;DR: In this paper, the authors used large animal models of congestive heart failure (HF) for the elucidation of biological pathways involved in HF and the development and refinement of HF therapies.
Abstract: Congestive heart failure (HF) is a clinical syndrome, with hallmarks of fatigue and dyspnea, that continues to be highly prevalent and morbid. Because of the growing burden of HF as the population ages, the need to develop new pharmacological treatments and therapeutic interventions is of paramount importance. Common pathophysiologic features of HF include changes in left ventricle structure, function, and neurohormonal activation. The recapitulation of the HF phenotype in large animal models can allow for the translation of basic science discoveries into clinical therapies. Models of myocardial infarction/ischemia, ischemic cardiomyopathy, ventricular pressure and volume overload, and pacing-induced dilated cardiomyopathy have been created in dogs, pigs, and sheep for the investigation of HF and potential therapies. Large animal models recapitulating the clinical HF phenotype and translating basic science to clinical applications have successfully traveled the journey from bench to bedside. Undoubtedly, large animal models of HF will continue to play a crucial role in the elucidation of biological pathways involved in HF and the development and refinement of HF therapies. (Circ Heart Fail. 2009;2:262-271.)

247 citations