Search results for "valve"
showing 10 items of 576 documents
Long-Term Outcome with New Generation Prostheses in Patients Undergoing Transcatheter Aortic Valve Replacement
2021
The aim of this study was to compare patients with transcatheter aortic valve replacement (TAVR) receiving new generation prostheses SAPIEN 3 (S3, Edwards Lifesc.) and Evolut R (ER, Medtronic Inc.) in terms of periprocedural and long-term outcome. Our retrospective, single-center analysis included 359 consecutive patients with severe aortic stenosis who underwent TAVR with S3 or ER from 2014–2016 (mean age 82 ± 7 years, 47% male, mean EuroSCORE II 8.0 ± 8%, mean follow-up 3.8 years). Device Success was equal (S3 93.0% vs. ER 92.4%, p = 0.812). We report a 30-day mortality of 2.8% in the S3 group, and 2.1% in the ER group (p = 0.674). There was no difference in stroke, conversion to open sur…
Transesophageal contrast echocardiography is not always the gold standard method in the identification of a patent foramen ovale: A clinical case
2015
In the embryo, Eustachian valve is a crescent-shaped membrane extending from the lower margin of the inferior vena cava and the ostium of the coronary sinus into the right atrium toward fossa ovalis and tricuspid valve. At birth, after the functional closure of the foramen ovale, the Eustachian valve loses its function, reducing to an embryo remnant. According to growing evidence, a persistent Eustachian valve is a frequent finding in patients with a patent foramen ovale (PFO). By directing the blood from the inferior cava to the interatrial septum, it may prevent the spontaneous closure of PFO after birth and indirectly predispose to paradoxical embolism. Transesophageal contrast enhanced …
The progression rate of aortic stenosis: key to tailoring the management and potential target for treatment
2021
: Aortic stenosis is the most frequent valvular disease to require intervention in the western world and has always been featured as a progressive disease. The rate of progression can be assessed by carefully performed Doppler echocardiography and can vary greatly between individuals with a profound impact on prognosis. Unfortunately, the determinants of disease progression had been insufficiently studied and remain challenging to define, particularly in the outpatient setting. Multiple factors have been proposed and tested, but at present, there are no proven therapies to slow the course of the stenotic process. Heart valve clinics may be particularly important to define the progression ra…
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…
Light on the molecular and cellular mechanisms of bicuspid aortic valve to unveil phenotypic heterogeneity
2019
Research on bicuspid aortic valve disease (BAV) and related complications has grown in an exponential manner in the last decades. However, the current knowledge of the mechanisms underlying the development of this disease is still limited, since all clinical and surgical studies on BAV mainly focused their objects on its major vascular complications, such as ascending aortic aneurysms and dissection. It is now clear that a better understanding of the pivotal molecular and cellular pathophysiological aspects of bicuspid valve aortopathy, including natural history, phenotypic expression, histology, cellular mechanisms and pathways, is critical for improving its clinical management. This chang…
Molecular Spintronic Devices: from Molecular Spin Valves to Spin-OLEDs
2017
La investigación llevada a cabo durante el periodo de tesis doctoral y que se describe en este manuscrito pertenece al campo de la espintrónica molecular. Ha sido motivada por el deseo de incorporar nuevos materiales moleculares a dispositivos espintrónicos y ahondar en la comprensión de la inyección y el transporte de espín en este tipo de capas, a través del estudio de dispositivos como la válvula de espín molecular y el spin-OLED. En 1988 Albert Fert y Peter Grünberg descubrieron que la resistencia eléctrica de unas multicapas de Fe-Cr variaba considerablemente en función de la magnetización de las láminas. El efecto se conoce hoy en día como magnetoresistencia gigante o GMR, por sus sig…
Patient-specific computational evaluation of stiffness distribution in ascending thoracic aortic aneurysm
2021
Quantifying local aortic stiffness properties in vivo is acknowledged as essential to assess the severity of an ascending thoracic aortic aneurysm (ATAA). Recently, the LESI (local extensional stiffness identification) methodology has been established to quantify non-invasively local stiffness properties of ATAAs using electrocardiographic-gated computed tomography (ECG-gated CT) scans. The aim of the current study was to determine the most sensitive markers of local ATAA stiffness estimation with the hypothesis that direct measures of local ATAA stiffness could better detect the high-risk patients. A cohort of 30 patients (12 BAV and 18 TAV) referred for aortic size evaluation by ECG-gated…
Molluscan antimicrobial peptides, a review from activity-based evidences to computer-assisted sequences
2011
Antimicrobial peptides (AMPs) represent the most universal immune effectors. Molluscs constitute the second largest animal phylum, after Arthropods, in term of number of species. Only a negligible number has been investigated regarding AMPs. The choice of the species to be studied relied on their economical importance and availability. First studies on molluscan AMPs dated from 1996 and were based on biological activities of biochemical-purified fractions. Such approach released all the original structures we know, with biological activity sometimes different from one isoform to another. Then, molecular biology techniques were applied to molluscan AMPs starting in 1999. Complete screening o…
Enabling Energy Savings in Offshore Mechatronic Systems by using Self-Contained Cylinders
2019
This paper proposes a novel actuation system for an offshore drilling application. It consists of three self-contained electro-hydraulic cylinders that can share and store regenerated energy. The energy saving potential of the proposed solution is analyzed through a multibody system simulation. The self-contained system demonstrates superior energy efficiency compared to the benchmark system representing the state-of-the-art approach used today (i.e., valve-controlled cylinders by means of pressure-compensated directional control valves and counter-balance valves, supplied by a centralized hydraulic power unit). Due to the power on demand capability, the cancellation of the throttling losse…
Numerical and Experimental Study of a Novel Concept for Hydraulically Controlled Negative Loads
2016
This paper presents a numerical and experimental investigation of a novel concept that eliminates oscillations in hydraulic systems containing a counterbalance valve in series with a pressure compensated flow supply. The concept utilizes a secondary circuit where a low-pass filtered value of the load pressure is generated and fed back to the compensator of the flow supply valve. The novel concept has been implemented on a single boom actuated by a cylinder. A nonlinear model of the system has been developed and an experimental verification shows good correspondence between the model and the real system. The model is used for a parameter study on the novel concept. From the study it is found…