Search results for "Annulus"
showing 6 items of 26 documents
Limit Periodic Sets
1998
As explained at the end of the previous chapter, the most difficult problem in the study of bifurcations in a family of vector fields on a surface of genus 0 is the control of the periodic orbits. In fact, in generic smooth families the periodic orbits will be isolated for each value of the parameter. For analytic families we have two possibilities for each orbit: it may be isolated or belong to a whole annulus of periodic orbits. In this last case and for the parameter values for which the system has infinitely many periodic orbits, the vector field has a local analytic first integral and the nearby vector fields in the family may be studied by the perturbation theory introduced in Chapter…
Thin plastic foil X-ray optics with spiral geometry
2007
Winding a plastic foil ribbon into spiral cylinder or spiral cones we can design and build single or multiple reflection X-ray grazing incidence focusing optics with potential applications in Astronomy as well as experimental physics. The use of thin plastic foils from common industrial applications and of a mounting technique which does not require the construction of mandrels make these optics very cost effective. A spiral geometry focusing optic produces an annular image of a point source with the angular size of the annulus depending mainly on the pitch of the winding and the focal length. We use a ray-tracing code to evaluate the performances of cylindrical, and double conical spiral g…
Multiplane Two-Dimensional versus Real Time Three-Dimensional Transesophageal Echocardiography in Ischemic Mitral Regurgitation
2011
Objectives: Intraoperative three-dimensional (3D) transesophageal echocardiography (TEE) has been suggested to be a valuable technique for the evaluation of the mechanisms of ischemic mitral regurgitation (IMR). Studies comparing multiplane two-dimensional (2D) with 3D TEE reconstruction of the mitral valve using the new mitral valve quantification (MVQ) software are lacking. We undertook a prospective comparison between multiplane 2D and 3D TEE for the assessment of IMR. Methods: We evaluated echocardiographically 45 patients with IMR who underwent mitral valve surgery in our institution. 2D and 3D TEE examinations followed by a 3D offline assessment of the mitral valve apparatus were perf…
CAD Modeling for Evaluating LVOT Obstruction in Transcatheter Mitral Valve Replacement
2019
The current generation of transcatheter heart valves (THV), as the Edwards SAPIEN 3 Ultra (S3), is not specifically designed for mitral position implantation and has intrinsic design geometry that may make mitral implantation suboptimal. This study aimed to develop a computed-tomography (CT) based CAD workflow for the preoperative planning of transcatheter mitral valve replacement (TMVR) by evaluating the resulting obstruction in the left ventricular outflow tract (LVOT). Specifically, the computational framework to reconstruct heart anatomy and virtually deploy the THV into mitral valve annulus was developed and successively applied to the cases of two patients who experienced annuloplasty…
Transcatheter indirect mitral annuloplasty induces annular and left atrial remodelling in secondary mitral regurgitation
2020
Abstract Aims Mitral annuloplasty using the Carillon Mitral Contour System (CMCS) reduces secondary mitral regurgitation (SMR) and leads to reverse left ventricular remodelling. The aim of this study was to evaluate the effect of the CMCS on the mitral valve annulus (MA) and left atrial volume (LAV). Methods and results We retrospectively evaluated the data of all patients treated with the CMCS at our centre. Using transthoracic echocardiography, MA diameters were assessed by measuring the anterolateral to posteromedial extend (ALPM) and the anterior to posterior (AP) dimensions, respectively. Also, LAV and left ventricular end‐diastolic volume (LVEDV) were assessed. Patients were examined …
Enhanced prolylhydroxylase activity in the posterior annulus fibrosus of canine intervertebral discs following long-term running exercise
2010
The effect of long-term excercise on the intervertebral disc collagen concentration (hydroxyproline), collagen-synthesizing enzymes (prolyl-4-hydroxylase, PH, and galactosyl-hydroxylysyl glucosyltransferase, GGT) and hydroxypyridinium crosslinks was studied in ten female beagle dogs. The dogs were run on a treadmill for 1 year starting at the age of 15 weeks. The daily running distance was gradually increased to 40km, which distance the dogs ran for the final 15 weeks. Ten untrained dogs from the same breeding colony served as controls. The nucleus pulposus and anterior and posterior halves of the annulus fibrosus of C2-3, T10-12, L4-5 disc segments were analysed. Crosslinks were measured f…