SciCombinator

Discover the most talked about and latest scientific content & concepts.

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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The growing experience in aortic valve (AV) repair showed that annular stabilization is a crucial component to achieve stable long-term results after AV repair. Dynamic changes in the AV annulus during the cardiac cycle may have an impact on annuloplasty design.

Concepts: Cardiology, Heart, Annulus, Left ventricle, Aortic valve, Mitral valve repair, Aortic valve repair

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Feature tracking in cine cardiac magnetic resonance (CMR) is a quantitative technique to assess heart structure and function. We investigated 4-dimensional (4D) dynamics and morphology of the mitral annulus (MA) using a novel tracking system based on radially rotational long-axis cine CMR series. A total of 30 normal controls and patients with mitral regurgitation were enrolled. The spatiotemporal changes of the MA were characterized by an in-house developed program. Dynamic and morphological parameters extracted from all 18 radial slices were used as references and were compared with those from subsequently generated sub-datasets with different degrees of sparsity. An excellent agreement was found among all datasets including routine 2-, 3- and 4-chamber views for MA dynamics such as peak systolic velocity (Sm) and mitral annular plane systolic excursion (MAPSE). MA morphology for size and shape was addressed adequately by as few as 6 radial slices, but poorly by only three routine views. Patients with regurgitation showed significantly reduced mitral dynamics and mild annular deformation, which was consistent between three routine views and 18 reference slices. In conclusion, feature tracking cine CMR provided a comprehensive and distinctive profile for 4D MA dynamics and morphology, which may help in studying different cardiac diseases.

Concepts: Heart, Heart disease, Annulus, Mitral valve, Mitral regurgitation, Mitral valve prolapse, Academic degree, Tracking system

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Pulmonary valvular stenosis is a relatively common disorder, accounting for approximately 10% of all CHDs. Pulmonic valvular disease can get clinically detected at different ages of life. The more severe the obstruction, the earlier detected the valvular abnormality. Surgical pulmonary valvotomy has been available as a treatment since 1956. This article is about a case of pulmonary annular and valvular stenosis in a 1-year-old child, and it also explores surgical operation of this condition. Transannular patches are usually used within the 1st year of age in pulmonary annular and valvular stenosis. In recent years, anterior leaflet augmentation has been preferred for annulus enlargements. In our 1-year-old case, we expanded the annulus by the anterior leaflet expansion technique and we also augmented other leaflets by polytetrafluoroethylene patch.

Concepts: Medicine, Age, Annulus, Cardiothoracic surgery, Valvular heart disease, Valve, Pulmonary valve stenosis, Augment

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Interrupted pledget-armed braided sutures are widely used for valve implantation. In a 74-year-old woman with aortic valve endocarditis and shallow annular abscess, annulus dehiscence resulted after resection. As resistance was too high for sufficient primary approximation, a snug fit of the valve by means of circumferential application of curbed tourniquets resembling Medusa’s head after suture placement was achieved. Closest possible approximation of the upper and lower part of the annulus with the prosthesis prior to final fixation was thus possible, so that application of too much tension on a single suture could be avoided.

Concepts: Annulus, Surgical suture, Aortic valve, Aortic valve stenosis, Dehiscence, Medusa

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The lack of annular stabilization is the drawback of aortic root remodeling, and recently the addition of annuloplasty has been proposed. Limited data, however, exist on late annular size after remodeling. We studied annular size over time.

Concepts: Annulus, Aorta, Ascending aorta, Annular ring

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Using in vitro models, the mechanics as well as surgical techniques for mitral valves (MV) and MV devices can be studied in a more controlled environment with minimal monetary investment and risk. However, these current models rely on certain simplifications, one being that the MV has a static, rigid annulus. In order to study more complex issues of imaging diagnostics and implanted device function, it would be more advantageous to verify their use for a dynamic environment in a dynamic simulator. This study provides the novel design and development of a dynamically contracting annulus (DCA) within an in vitro simulator, and its subsequent use to study MV biomechanics. Experiments were performed to study the ability of the DCA to reproduce the MV leaflet mechanics in vitro, as seen in vivo, as well as investigate how rigid annuloplasties affect MV leaflet mechanics. Experiments used healthy, excised MVs and normal hemodynamics; contractile waveforms were derived from human in vivo data. Stereophotogrammetry and echocardiography were used to measure anterior leaflet strain and the change in MV geometry. In pursuit of the first in vitro MV simulator that more completely represents the dynamic motion of the full valvular apparatus, this study demonstrated the successful operation of a dynamically contracting mitral annulus. It was seen that the diseased contractile state increased anterior leaflet strain compared to the healthy contractile state. In addition, it was also shown in vitro that simulated rigid annuloplasty increased mitral anterior leaflet strain compared to a healthy contraction.

Concepts: In vivo, In vitro, Annulus, Novel, Mitral valve, Mitral valve prolapse, Contract, Mitral valve repair

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The shear swirling flow vibration cementing (SSFVC) technique rotates the downhole eccentric cascade by circulating cementing fluid. It makes the casing eccentrically revolve at high speed around the borehole axis. It produces strong agitation action to the annulus fluid, makes it in the state of shear turbulent flow, and results in the formation of pulse pressure which affects the surrounding rock stress. This study was focused on 1) the calculation of the pulse pressure in an annular turbulent flow field based on the finite volume method, and 2) the analysis of the effect of pulse pressure on borehole stability. On the upside, the pulse pressure is conducive to enhancing the liquidity of the annulus fluid, reducing the fluid gel strength, and preventing the formation of fluid from channeling. But greater pulse pressure may cause lost circulation and even formation fracturing. Therefore, in order to ensure smooth cementing during SSFVC, the effect of pulse pressure should be considered when cementing design.

Concepts: Fundamental physics concepts, Fluid dynamics, Thermodynamics, Viscosity, Annulus, Fluid, Computational fluid dynamics, Partial differential equation

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Lower back pain, the leading cause of workplace absences and disability, is often attributed to intervertebral disc (IVD) degeneration in which nucleus pulposus (NP) herniates through lesions in the annulus fibrosus (AF) and impinges on the spinal cord and surrounding nerves. Surgeons remove extruded NP via discectomy when indicated by local/radicular pain supported by radiographic evidence, however current interventions do not alter the underlying disease or seal the AF. The reported rates of recurrent herniation or pain following discectomy cases range from 5-25%, which has pushed spine research in recent years towards annular repair and closure strategies. Synthetic implants designed to mechanically seal the AF have been subject to large animal and clinical trials, with limited success in preventing recurrent herniation. Like gold standard interventions, purely mechanical devices fail to promote tissue integration, long term healing, or restore native biomechanical function to the spine. Biological repair strategies utilizing principles of tissue engineering have demonstrated success in overcoming the inadequacies of current interventions and mechanical implants, yet none have reached clinical or proof-of-concept trials in humans. In this review, we will discuss annular repair strategies promoting biological healing that have been implemented in small and large animal models in vivo, and ways to enhance the efficacy of these treatments.

Concepts: Spinal disc herniation, Extracellular matrix, Vertebral column, Pre-clinical development, Annulus, Vertebra, Intervertebral disc, The Spine