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Eliminating Regurgitation Reduces Fibrotic Remodeling of Functional Mitral Regurgitation Conditioned Valves.

ABSTRACT: Functional mitral regurgitation (FMR) is an insidious and poorly understood condition affecting patients with myocardial disease. While current treatments reduce regurgitation, their ability to reverse mitral valve pathology is unclear. We utilized a pseudo-physiological flow loop to study how repair impacted valve composition. Porcine mitral valves were cultured in control geometry (native papillary muscle position and annular area) or high-tension FMR geometry (5 mm apical and 5 mm lateral displacement of papillary muscles, 65% increased annular area) for 2 weeks. To mimic repair, a reversal condition was created by returning one-week FMR conditioned valves to a non-regurgitant geometry and culturing for 1 week. Valve composition and material properties were analyzed. After two-week culture, FMR conditioned tissues were stiffer and stronger than control and underwent extensive fibrotic remodeling, with increased prolyl-4-hydroxylase, lysyl oxidase, matrix metalloproteinase-1, and decorin. The reversal condition displayed a heterogeneous, leaflet- and orientation-dependent response. Reversal-conditioned anterior leaflets and circumferential tissue sections continued to have significant fibrotic remodeling compared to control, whereas reversal-conditioned posterior leaflets, chordae tendineae, and radial tissue sections had significantly decreased remodeling compared to FMR-conditioned tissues. These findings suggest current repairs only partially reverse pathology, underscoring the need for innovation in the treatment of FMR.

SUBMITTER: Connell PS

PROVIDER: S-EPMC5897174 | biostudies-literature | 2018 May

REPOSITORIES: biostudies-literature

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Eliminating Regurgitation Reduces Fibrotic Remodeling of Functional Mitral Regurgitation Conditioned Valves.

Connell Patrick S PS Vekilov Dragoslava P DP Diaz Christine M CM Kim Seulgi E SE Grande-Allen K Jane KJ

Annals of biomedical engineering 20180205 5

Functional mitral regurgitation (FMR) is an insidious and poorly understood condition affecting patients with myocardial disease. While current treatments reduce regurgitation, their ability to reverse mitral valve pathology is unclear. We utilized a pseudo-physiological flow loop to study how repair impacted valve composition. Porcine mitral valves were cultured in control geometry (native papillary muscle position and annular area) or high-tension FMR geometry (5 mm apical and 5 mm lateral dis ...[more]

PMID: 29404848

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Project description:Rationale: Ischemic mitral regurgitation (IMR) is frequently observed following myocardial infarction (MI) and is associated with higher mortality and poor clinical prognosis if left untreated. Accumulating evidence suggests that mitral valve (MV) leaflets actively remodel post-MI, yet the cellular mechanisms underlying these responses and how this affects tissue function remain largely unknown. Objective: We sought to elucidate MV remodeling post-MI at the tissue, cellular, and transcriptomic levels. Methods and Results: The mechanical behavior of ovine MV leaflets pre-MI and 8 weeks post-MI reveal a significant decrease in radial direction extensibility, which essentially eliminated the mechanical anisotropy typically observed in healthy MVs. Quantitative histology and ultrastructural assessment by transmission electron microscopy revealed altered leaflet composition and architecture at 8 weeks post-MI. Assessment of the MV interstitial cell (MVIC) nuclear aspect ratio, a metric of cellular deformation, revealed that MVICs were on average rounder following MI. RNA sequencing (RNA-seq) indicated that YAP-induced genes were elevated at 4 weeks post-MI and genes related to extracellular matrix organization were some of the most downregulated in sheep with IMR compared to sheep without IMR at 4 weeks post-MI. Additionally, RNA-seq revealed the possible recruitment of immune cells in this remodeling process due to the drastic elevation of CXCL9 and CLEC10A. Conclusions: This multiscale assessment revealed significant mechanical and microstructural changes due to MI. RNA-seq provided a baseline for global gene expression changes in response to MI with and without IMR and suggests YAP-induced mechanotransduction, altered expression of ECM-related genes, and recruitment of immune cells as mechanisms contributing to altered MV biomechanics post-MI. Conclusions: This multiscale assessment revealed significant mechanical and microstructural changes due to MI. RNA-seq provided a baseline for global gene expression changes in response to MI with and without IMR and suggests YAP-induced mechanotransduction, altered expression of ECM-related genes, and recruitment of immune cells as mechanisms contributing to altered MV biomechanics post-MI.

Project description:AimThe objective of this study was to investigate the prognostic importance of right ventricular dysfunction (RVD) and tricuspid regurgitation (TR) in patients with moderate-severe functional mitral regurgitation (FMR) receiving MitraClip procedure. RVD and TR grade are associated with cardiovascular mortality in the general population and other cardiovascular diseases. However, there are limited data from observational studies on the prognostic significance of RVD and TR in FMR receiving MitraClip procedure.Methods and resultsA systemic review and meta-analysis were performed using MEDLINE, Scopus, and Embase to assess the prognostic value of RVD and TR grade for mortality in patients with functional mitral regurgitation (FMR) receiving MitraClip procedure. Hazard ratios were extracted from multivariate models reporting on the association of RVD and TR with mortality and described as pooled estimates with 95% confidence intervals. A total of eight non-randomized studies met the inclusion criteria with seven studies having at least 12 months follow-up with a mean follow-up of 20.9 months. Among the aforementioned studies, a total of 1112 patients (71.5% being male) were eligible for being included in our meta-analysis with an overall mortality rate of 28.4% (n = 316). Of the enrolled patients, RVD was present in 46.1% and moderate-severe TR in 29.2%. RVD was significantly associated with mortality compared to normal RV function (HR, 1.79, 95% CI, 1.39-2.31, P < 0.001, I2 = 0). Patients with moderate-severe TR showed increased risk of mortality compared with those in the none-mild TR group (HR, 1.61. 95% CI, 1.11-2.33, P = 0.01, I2 = 14).ConclusionsThis meta-analysis demonstrates the prognostic importance of RVD and TR grade in predicting all-cause mortality in patients with significant FMR. RV function and TR parameters may therefore be useful in the risk stratification of patients with significant FMR undergoing MitraClip procedure.

Project description:We aimed to identify predictors of mitral regurgitation recurrence (MR) after percutaneous mitral valve repair (PMVR) in patients with functional mitral regurgitation (FMR). Patients with FMR were enrolled who underwent PMVR using the MitraClip® device. Procedural success was defined as reduction of MR of at least one grade to MR grade ≤ 2 + assessed at discharge. Recurrence of MR was defined as MR grade 3 + or worse at one year after initially successful PMVR. A total of 306 patients with FMR underwent PMVR procedure. In 279 out of 306 patients (91.2%), PMVR was successfully performed with MR grade ≤ 2 + at discharge. In 11.4% of these patients, MR recurrence of initial successful PMVR after 1 year was observed. Recurrence of MR was associated with a higher rate of heart failure rehospitalization during the 12 months follow-up (52.0% vs. 30.3%; p = 0.029), and less improvement in New York Heart Association (NYHA) functional class [68% vs. 19% of the patients presenting with NYHA functional class III or IV one year after PMVR when compared to patients without recurrence (p = 0.001)]. Patients with MR recurrence were characterized by a higher left ventricular sphericity index {0.69 [Interquartile range (IQR) 0.64, 0.74] vs. 0.65 (IQR 0.58, 0.70), p = 0.003}, a larger left atrium volume [118 (IQR 96, 143) ml vs. 102 (IQR 84, 123) ml, p = 0.019], a larger tenting height 10 (IQR 9, 13) mm vs. 8 (IQR 7, 11) mm (p = 0.047), and a larger mitral valve annulus [41 (IQR 38, 43) mm vs. 39 (IQR 36, 40) mm, p = 0.015] when compared to patients with durable optimal long-term results. In a multivariate regression model, the left ventricular sphericity index [Odds Ratio (OR) 1.120, 95% Confidence Interval (CI) 1.039-1.413, p = 0.003)], tenting height (OR 1.207, 95% CI 1.031-1.413, p = 0.019), and left atrium enlargement (OR 1.018, 95% CI 1.000-1.038, p = 0.047) were predictors for MR recurrence after 1 year. In patients with FMR, baseline parameters of advanced heart failure such as spherical ventricle, tenting height and a large left atrium might indicate risk of recurrent MR one year after PMVR.

Project description:BackgroundMild physiologic mitral regurgitation (MR) is common in normal individuals. Patients with primary MR due to mitral valve prolapse (MVP) may also exhibit less than moderate MR. We sought to determine whether MVP patients with less than moderate MR displayed early cardiac chamber remodeling or factors related to early remodeling and whether early remodeling predicted MR progression.MethodsConsecutive MVP patients with less than moderate MR by proximal isovelocity surface area-derived effective regurgitant orifice < 20 mm2 and regurgitant volume < 30 mL, were matched for age and sex with non-MVP patients (controls) having less than moderate MR. Patients with moderate or greater dysfunctional left- or right-sided valves and left ventricular ejection fraction < 50% were excluded. We evaluated left ventricle (LV) and left atrium (LA) remodeling parameters (LV end-diastolic and end-systolic indexed diameters, LA volume-index, and LV mass-index) as well as determinants of remodeling. The last available transthoracic echocardiography was reviewed to identify progression to moderate-severe MR or more.ResultsA total of 253 MVP patients with less than moderate MR were matched to 344 controls (P for age and sex, ≥.18) with less than moderate MR. Patients with MVP (mean effective regurgitant orifice and regurgitant volume, 12 ± 4 mm2 and 18 ± 6 mL, respectively) had more premature ventricular contractions (PVCs), larger LV and LA remodeling parameters, and more mild-to-moderate MR (all P < .0001). Multivariate linear regression models showed that larger LV remodeling parameters were independently associated with MVP and female sex but not MR severity (all P < .0001). The LA volume index was independently associated with MVP, age, and E/e' (all P < .0001). The LV mass index was associated with MVP, age, and hypertension (all P ≤ .002). Presence of PVCs was associated with LV end-systolic diameter ≥ 40 mm and indexed ≥ 22 mm2 (P = .005). Among 323 (54%) patients having subsequent transthoracic echocardiography, 17 patients (all MVP) progressed to moderate-severe MR or more at a median of 4.3 (interquartile range, 1.7-6.4) years. Isolated posterior leaflet prolapse was the single factor associated with MR progression (adjusted hazard ratio, 2.70; 95% CI, 0.99-7.34; P = .048) after adjustment for MR severity. At a median of 5.9 (interquartile range, 4.6-7.2) years of follow-up, female sex and MVP (vs controls) were protective factors for mortality.ConclusionsPatients with less than moderate MR due to MVP exhibit early LV and LA remodeling, which does not predict MR progression or mortality. Left ventricle remodeling is associated with MVP, female sex, and presence of PVCs. Early chamber remodeling associated with MVP may be the phenotypical expression of a genetically mediated process and is at least partially related to PVCs.

Dataset Information

Eliminating Regurgitation Reduces Fibrotic Remodeling of Functional Mitral Regurgitation Conditioned Valves.

Publications

Eliminating Regurgitation Reduces Fibrotic Remodeling of Functional Mitral Regurgitation Conditioned Valves.

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