Search results for "Outflow"

Simulation of left ventricular outflow tract (LVOT) obstruction in transcatheter mitral valve-in-ring replacement.

2020

Left ventricular outflow tract (LVOT) obstruction is a feared complication of transcatheter mitral valve replacement (TMVR). This procedure leads to an elongation of LVOT in the left ventricle (namely, the neoLVOT), ultimately portending hemodynamic impairment and death. This study sought to understand the biomechanical implications of LVOT obstruction in two patients who underwent TMVR as an "off-label" application of the Edwards SAPIEN 3 (S3) Ultra transcatheter heart valve (THV). A computational framework of TMVR was developed to assess the neoLVOT area and quantify the sub-aortic flow structure. We observed that the annuloplasty ring serves as the key anchor zone of S3 Ultra THV. A good…

Focus on right ventricular outflow tract septal pacing

2013

SummaryExperimental and clinical studies have shown that right ventricular apical pacing may result in long-term deleterious effects on account of its negative impact on left ventricular remodeling through desynchronization. This risk appears more pronounced in patients with even moderate left ventricular dysfunction and generally occurs after at least 1 year of pacing. As right ventricular apical pacing may be associated with the development of organic mitral insufficiency, other sites that allow for more physiological stimulation, such as right ventricular outflow tract septal pacing, have been developed, with good feasibility and reproducibility. However, the prospective randomized studi…

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…

87Non-invasive virtual prediction of site of origin in outflow tract ventricular arrhythmias with a patient-specific computational model

2017

Activation of the glymphatic system during sleep – is the cerebral venous outflow a missing piece of the puzzle?

2019

Until recently, mechanisms responsible for an activation of the glymphatic system of the brain, the system which is responsible for cleansing of this organ of waste products, were unclear. A recently published paper has finally shed some light on this problem. It has been demonstrated that there is a temporary decrease of the arterial cerebral blood flow during the deep phase of sleep, which is followed by an influx of the cerebrospinal fluid into the cranial cavity, and that this phenomenon is probably responsible for the activation of the glymphatic system. Although, of as yet, this issue has not been studied, it is likely that such a mechanism is not effective in the settings of disturbe…

Diagnostic accuracy of Doppler sonography and magnetic resonance venography for the assessmentv of impaired outflow from the internal jugular vein in…

2015

Objectives: This prospective study was aimed at evaluation of diagnostic value of Doppler sonography and magnetic resonance (MR) venography in the internal jugular vein territory. Material and methods: There were assessed 126 patients (252 internal jugular veins). The patients were initially diagnosed using Doppler sonography and MR venography, and then catheter venography of the veins was performed. For the purpose of this study catheter venography was regarded the reference test. We interpreted sonographic findings in the context of criteria proposed by Zamboni and criteria by International Society for Neurovascular Disease (ISNVD). We applied MR protocols aimed at flow assessment in the …

MRI in the Diagnosis of Right Ventricular Dysplasia

2006

ARVD is part of the group of cardiomyopathies characterised pathologically by fibrofatty replacement of the right ventricular myocardium and clinically by right ventricular arrhythmias of the LBBB pattern. Pathogenesis, prevalence, and aetiology are yet not fully known. The diagnosis of ARVD is based on the presence of structural, histological, electrocardiographic, and genetic factors. Therapeutic options include antiarrhythmic medication, catheter ablation, implantable cardioverter defibrillation, and surgery. Angiography and echocardiography lack sensitivity and specificity in the diagnosis of ARVD. MR imaging allows a three-dimensional evaluation of especially the right ventricle, and p…

Pre-Operative Modeling of Transcatheter Mitral Valve Replacement in a Surgical Heart Valve Bioprosthesis

2020

Obstruction of the left ventricular outflow tract (LVOT) is a common complication of transcatheter mitral valve replacement (TMVR). This procedure can determine an elongation of an LVOT (namely, the neo-LVOT), ultimately portending hemodynamic impairment and patient death. This study aimed to understand the biomechanical implications of LVOT obstruction in a patient who underwent TMVR using a transcatheter heart valve (THV) to repair a failed bioprosthetic heart valve. We first reconstructed the heart anatomy and the bioprosthetic heart valve to virtually implant a computer-aided-design (CAD) model of THV and evaluate the neo-LVOT area. A numerical simulation of THV deployment was then deve…

Fast changes in the morphology of the X-ray emitting shocks in HH 154

2006

Our recent second epoch Chandra observations have shown a fast morphological evolution of the X-ray source associated with the protostellar jet HH 154 (Fig.\ 1). We propose to study the evolution of the optical structures in the jet, specially the ones associated with the X-ray emission with a monitoring program of imaging narrow and broad band optical observations. We will determine the proper motions (and braking) of the optical knows associated with shock features and the evolution of their line luminosity and therefore their cooling time. These data, together with our past and future X-ray observations, constitute a fundamental input and constraint to our parallel program of ongoing hyd…

High Energy Emission and its Variability in Young Stellar Objects

2019

Young stars show a variety of highly energetic phenomena, from accretion and outflow processes to hot coronal plasmas confined in their outer atmosphere, all regulated by the intense stellar magnetic fields. Many aspects on each of these phenomena are debated, but, most notably, their complex mutual interaction remains obscure. In this work I report how these phenomena are simultaneously responsible for the high-energy emission from young stars, with a special focus on the expected and observed variability in the X-ray band. Investigating variations in the X-ray emission from young stars allows us to pose constraints on flare and coronal plasma properties, coronal heating, accretion stream …