SciCombinator

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Concept: Annulus

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Due to the increased life expectancy and continual improvements in cardiological treatment options, diseases of the tricuspid valve, in particular tricuspid valve insufficiency will become increasingly more recognized as an interventional target. While tricuspid stenosis is rare and can be effectively treated with balloon valvuloplasty, no effective transcatheter approach to tricuspid regurgitation (TR) has yet been established. As the tricuspid annulus is a complex and highly dynamic structure that offers little resistance, orthotopic long-term fixation of transcatheter valves with the current techniques is challenging and has not yet been performed in human patients. Alternative treatment concepts include transcatheter caval valve implantation (CAVI) to address the regurgitation of blood into the caval veins, which has resulted in hemodynamic improvement and is currently undergoing further clinical investigation. Other interventional treatment concepts are aimed at tricuspid valve repair, e.g. by annular plication with the Mitralign™ device or the TriCinch™ system. In the medium-term it can be assumed that percutaneous systems and therapy options will become available for these indications whereby the functional and prognostic effects of these treatment procedures will be corroborated in the appropriate patient groups by corresponding studies.

Concepts: Heart, Right atrium, Tricuspid valve, Annulus, Abstraction, Tricuspid insufficiency, Regurgitation, Valvular heart disease

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We aimed to evaluate the success rates of balloon valvuloplasty post-dilation (BVPD) and a second-valve deployment in reducing residual aortic regurgitation (AR) after transcatheter aortic valve implantation (TAVI) and its impact on outcome. Residual AR immediately post-TAVI in patients with aortic stenosis is a common condition that adversely affects outcome. Patients who underwent TAVI who had more-than-mild residual AR were managed either with medical therapy, re-intervention with BVPD, or a second valve. The clinical impact of these strategies was evaluated, and the anatomical features of patients with successful and unsuccessful intervention were compared. Among 572 patients with TAVI, 110 (19%) had significant residual AR after initial device deployment. Sixty patients were treated by BVPD (n = 49) or second-device deployment (n = 11), whereas 50 patients were treated medically. Successful reduction in residual AR to mild and below was achieved in 56% of the intervention group. Eccentric and calcified annuli were present in patients in whom residual AR remained despite re-intervention (p = 0.004). Interventions to reduce residual AR were independently associated with improved survival compared with conservative medical therapy (hazard ratio 0.45, 95% confidence interval 0.94 to 0.21, p = 0.03). BVPD or a second valve were safe and were not associated with increased rate of periprocedural complications. In conclusion, both BVPD and a second-valve deployment to reduce residual AR post-TAVI are effective and safe. The success rates are inversely correlated with the annulus eccentricity and calcification. These measures should be encouraged to reduce acute residual AR as they are associated with improved long-term survival.

Concepts: Medicine, Therapy, Annulus, Normal distribution, Aortic valve, Valvular heart disease, Aortic valve stenosis, Aortic insufficiency

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The sand rat, a member of the gerbil family, is a valuable small animal model in which intervertebral disc degeneration occurs spontaneously as the animal ages. Radiographic features of cervical and lumbar degeneration resemble those in human spines. We conducted a retrospective analysis of spines of 140 animals 3-41 months old focusing specifically on the presence of annular tears that are not visible by radiography and have not been described previously in the sand rat disc. During degeneration of the nucleus pulposus, notochordal cell death occurs and granular material, which stains with Alcian blue for proteoglycans, accumulates. Lamellar architecture also deteriorates and annular tears occur that are morphologically similar to the concentric, radiating and transdiscal annular tears in human discs. These tears contain granular material that provides a “marker” that can be used to distinguish the annular tears from artefactual separations during sectioning. We observed lamellar degeneration and separation in the annulus fibrosus at 4 months with associated tears that contained granular material in the nucleus. Tears that contained granular material and displacement of the degenerating nucleus were common in cervical and lumbar discs of animals older than 9 months; some specimens showed tears at 4 and 5 months. With advanced degeneration, granular globules were displaced dorsally adjacent to and into the spinal cord area and also ventrally into regions where osteophytes formed. We present morphologic data that expand the utility of this rodent model of spontaneous age-related disc degeneration and provide novel information on annular tears and disc degeneration.

Concepts: Spinal disc herniation, Skeletal system, Animal, Vertebral column, Radiography, Annulus, Rodent, Granular material

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Surgical repair of functional tricuspid regurgitation (FTR) is an increasingly common practice, but annuloplasty suture dehiscence remains a significant problem. Quantitative and mechanistic understanding of annular suture holding strength can support more effective techniques for tricuspid valve device anchoring.

Concepts: Tricuspid valve, Annulus, Tricuspid insufficiency, Regurgitation

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Growth of nerve fibers has been shown to occur in a rabbit model of intravertebral disc degeneration (IVD) induced by needle puncture. As nerve growth may underlie the process of chronic pain in humans affected by disc degeneration, we sought to investigate the factors underlying nerve ingrowth in a minimally invasive annulotomy rabbit model of IVD by comparing the effects of empty disc defects with those of defects filled with poly(lactic-co-glycolic acid)/fibrin gel (PLGA) plugs.

Concepts: Nervous system, Neuroanatomy, Action potential, Axon, Minimally invasive, Annulus, Nerve, Nerves

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Graphene annulus possesses special wrinkling phenomenon with wide range of potential applications. Using molecular dynamics simulation, this study concerns the effect of boundary on the mechanical properties of circular and elliptical graphene annuli under circular shearing at inner edge. Both the wrinkle characteristic and torque capacity of annular graphene can be effectively tuned by outer boundary radius and aspect ratio. For circular annulus with fixed inner radius, the critical angle of rotation can be increased by several times without sacrificing its torque capacity by increasing outer boundary radius. The wrinkle characteristic of graphene annulus with elliptical outer boundary differs markedly with that of circular annulus. Torque capacity anomalously decreases with the increase of aspect ratio, and a coupled effect of the boundary aspect ratio and the ratio of minor axis to inner radius on wrinkling are revealed. By studying the stress distribution and wrinkle characteristics, we find the decay of torque capacity is the result of circular stress concentration around the minor axis, while the nonuniform stress distribution is anomalously caused by the change of wrinkle profiles near the major axis. The specific mechanism of out-of-plane deformation on in-plane strength provides a straightforward means to develop novel graphene-based devices.

Concepts: Molecular dynamics, Ratio, Annulus, Aspect ratio, Annular ring, Hyperbola, Eccentricity, Semi-minor axis

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Cardiac valve plane displacement (CVPD) reflects longitudinal LV function. The purpose of the present study was to determine regional heterogeneity of CVPD in healthy adults to provide normal values by cardiac magnetic resonance (CMR). We measured the anterior aortic plane systolic excursion (AAPSE); the anterior, anterolateral, inferolateral, inferior, and inferoseptal mitral annular plane systolic excursion (MAPSE); and the lateral tricuspid annulus plane systolic excursion (TAPSE). Systolic excursion was measured as the distance from peak end-diastolic to peak end-sysstolic annular position (peak-to-peak) in cine images acquired in 2-, 3- and 4-chamber views. Echocardiographic measurements of CVPD were performed in M-Mode as previously described. We retrospectively analyzed 209 healthy Caucasians (57% men), who participated in the Heidelberg normal cohort between March 2009 and September 2014. The analysis was possible in all participants. Mean values were: AAPSE = 14 ± 3 mm (8-20); MAPSEanterior = 14 ± 3 mm (8-20); MAPSEanterolateral = 16 ± 3 mm (10-22); MAPSEinferolateral = 16 ± 3 mm (10-22); MAPSEinferior = 17 ± 3 mm (11-23); MAPSEinferoseptal = 13 ± 3 mm (7-19) and TAPSE = 26 ± 4 mm (18-34) respectively. MAPSE was significantly elevated in lateral compared to septal regions (p = 0.0001). Sex-differences for CVPD were not found. Age-dependency of CVPD revealed distinct regional differences. AAPSE decreased the most with age (B=-0.48; p = 0.0001), whereas MAPSEinferior was the least age-dependent site (B=-0.17; p = 0.01). AAPSE revealed favorable intra-/interobserver reproducibility and interstudy agreement. Intermethod-comparison of CMR and M-Mode echocardiography showed good agreement between both measurements of CVPD. Age-stratified normal values of regional CVPD are provided. AAPSE revealed the most pronounced age-related decrease and provided favorable reproducibility compared to other regions of cardiac valve plane.

Concepts: Cardiology, Heart, Echocardiography, Measurement, Mean, Annulus, Mitral valve prolapse, Region

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Severe device landing zone calcification (DLZ-CA) predicted paravalvular leak (PVL) and post-dilatation (PD) after transcatheter aortic valve implantation (TAVI). The aim of this study was to determine the influence of DLZ-CA on PVL or PD rates after SAPIEN XT (XT) versus CoreValve (CV).We analyzed patients undergoing TAVI who had severe DLZ-CA. Severe DLZ-CA defined the upper left ventricular outflow tract calcification; the cross-sectional region 2 mm inferior to the annular plane. PVL was evaluated at 30days using transthoracic echocardiography. Overall, 133 patients had XT-TAVI and the remaining 41 patients had CV-TAVI. Two patients had annulus injury in the XT group (oversizing 20.2% and 20.5% for two XT cases). PD was less frequently performed in the XT group (34.1% versus 12.8%; P = 0.002), but PVL rates were similar between both groups (42.1% versus 41.5% for the XT and CV groups, respectively; P = 0.94). Importantly, excessive oversizing or the degree of filling volume was not associated with decreased PVL after XT-TAVI (P = non-significant for all). On multivariate analysis, CV-TAVI was found to be one of the independent predictors of need for PD (Odds ratio 3.63, 95% confidence interval 1.55 to 8.53, P = 0.003).In the setting of severe DLZ-CA, XT and CV have similar rates of PVL but XT had less need for PD. Excessive oversizing with XT carries a risk of root injury which could be further increased by DLZ-CA.

Concepts: Echocardiography, Prediction, Annulus, Hypertrophic cardiomyopathy, Left ventricle, Prediction interval, Aortic valve, Valve

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The fluid front dynamics resulting from the coexisting infiltration and evaporation phenomena in nanofluidic systems has been investigated. More precisely, water infiltration in both titania and silica mesoporous films was studied through a simple experiment: a sessile drop was deposited over the film and the advancement of the fluid front into the porous structure was optically followed and recorded in time. In the case of titania mesoporous films, capillary infiltration arrested at a given distance, and a steady annular region of wetted material was formed. A simple model that combines Lucas-Washburn infiltration and surface evaporation was derived, which appropriately describes the observed filling dynamics and the annulus width in dissimilar mesoporous morphologies. In the case of worm-like mesoporous morphologies, a remarkable phenomenon was found: instead of reaching a steady infiltration-evaporation balance, the fluid front exhibits an oscillating behavior. This complex filling dynamics opens interesting possibilities to study unusual nanofluidic phenomena, as well as to discover novel applications.

Concepts: Observation, Liquid, Surface tension, Annulus, Distance, Phenomenon, Riemann surface, Annular ring

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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.

Concepts: Scientific method, Cardiology, Echocardiography, Annulus, Mitral valve, Mitral regurgitation, Mitral valve prolapse, Diastole