Search results for "Blood vessel prosthesis"

Outcomes of aortic valve repair according to valve morphology and surgical techniques

2012

OBJECTIVES: The aim of this study was to assess the impact of aortic valve morphology and different surgical aortic valve repair techni- ques on long-term clinical outcomes. METHODS: Between February 2003 and May 2010, 216 patients with aortic insufficiency underwent aortic valve repair in our institu- tion. Ages ranged between 26 and 82 years (mean 53 ± 15 years). Aortic valve dysfunctions, according to functional classification, were: type I in 55 patients (25.5%), type II in 126 (58.3%) and type III in 35 (16.2%). Sixty-six patients (27.7%) had a bicuspid valve. Aortic valve repair techniques included sub-commissural plasty in 138 patients, plication in 84, free-edge reinforcement in 80,…

Reduced protein adsorption on plastics via direct plasma deposition of triethylene glycol monoallyl ether

1997

The direct plasma-induced deposition of tri(ethylene glycol) monoallyl ether is reported. RF plasma polymerization of this monomer was carried out under both continuous wave (CW) and pulsed plasma operation. The major focus of this work was optimization of the degree of retention of the C-O-C bonds of the starting monomer during the deposition process. This successfully was accomplished using low RF power during the CW runs and low RF duty cycles during the pulsed plasma experiments. Spectroscopic analysis of the plasma films revealed a strong dependence of film composition on the RF power and duty cycles employed. In particular, an unusually high level of film chemistry compositional contr…

Large platelets but not putative endothelial progenitor cells are associated with low strut coverage after drug-eluting stent implantation

2015

Objectives This study assessed whether different subsets of circulating endothelial and putative endothelial progenitor cells (CEC and EPC) correlate with stent strut coverage (SSC) using second generation optical coherence tomography (OCT). Background Due to the lack of imaging modalities with a resolution down to the magnitude of a few cells, the influence of EPC on endothelialisation of drug-eluting stents has not been assessed in patients. Methods In 37 patients, SSC of everolimus-eluting stents was assessed by OCT 5-7months after stent implantation. Different subsets of EPC (CD34(+)KDR(+), CD34(+)KDR(+)CD45(dim), CD133(+), CD3(+)CD31(+)), CEC (CD31(+)CD45(-)CD146(+)), and CD31(+)CD45(-…

Mortality of ruptured abdominal aortic aneurysm with selective use of endovascular repair

2009

The aim of this review was to examine the results over a seven-year period of treatment for ruptured abdominal aortic aneurysm (RAAA). From 2002 on, our tertiary referral centre offered both open and endovascular (EVAR) treatment modalities for RAAA. All patients with a proven RAAA who were admitted into our hospital were included. Primary outcome measure was surgical mortality. In total 261 patients were admitted with suspicion of acute AAA. Of these, 175 (67%) had a RAAA, confirmed by computed tomography-scanning or at laparotomy. One hundred and fifty-nine patients (90.9%) were treated, 114 by open repair and 45 by EVAR. Overall mortality of patients treated was 25.2%, with an open repai…

External stenting with a new polyester mesh reduces neointimal hyperplasia of vein grafts in a sheep model.

2007

Objective External stents placed around vein grafts have demonstrated effectiveness in reducing neointimal hyperplasia by preventing distension of the thin-walled vein grafts when exposed to arterial pressure. However, the ideal stent material has yet to be defined. The following study investigates the short- and long-term effects of an innovative polyester mesh stent designed with optimized adaptation of circumferential compliance. Methods Following in vitro definition of the ideal macro-porous polyester stent material, a total of 12 sheep underwent implantation of bilateral carotid artery vein graft bypasses. In six sheep, the short-term outcome (four weeks of implantation) was investigat…

The use of Endurant stent-graft for abdominal aortic aneurysm: the story about extension of instruction for use with persistent good results of stent…

2012

The Endurant stent-graft (Medtronic, Inc., Minneapolis, MN, USA) is a latest generation device for the treatment of abdominal aortic aneurysm. The idea behind designing such a graft came from the intention to broad the instruction for use (IFU) and to enable it to treat more challenging anatomy including the 10mm neck lengths, and more severe suprarenal and infrarenal angulations. Endurant stent-graft has active fixation through suprarenal stent with anchoring pins to provide migration resistance, optimized heights of stents and spacing between them for improved flexibility and conformability, low-profile delivery system with hydrophilic coating and controlled simple deployment mechanism. S…

2017

We propose a mesh-free and discrete (particle-based) multi-physics approach for modelling the hydrodynamics in flexible biological valves. In the first part of this study, the method is successfully validated against both traditional modelling techniques and experimental data. In the second part, it is further developed to account for the formation of solid aggregates in the flow and at the membrane surface. Simulations of various types of aggregates highlight the main benefits of discrete multi-physics and indicate the potential of this approach for coupling the hydrodynamics with phenomena such as clotting and calcification in biological valves.

Stent oversizing or not-oversizing? An unresolved dilemma

2021

Primary PCI plus stent implantation is indicated for treatment of acute coronary syndrome. Technically, due to the difference in lumen diameter between vessel portions and stent size in some coronary arteries, post-expansion of the stent is usually necessary to match proximal reference diameter and optimize stent apposition. Incomplete stent apposition has been associated with increased risk of in stent restenosis (ISR) and stent thrombosis (1) despite new stent technologies have largely reduced this risk (2-3). Although new antiplatelet drugs showed a more rapid onset of action and a stronger effect (4-5), stent apposition remains an important risk factor for stent thrombosis. As stent pos…

Multi-objective optimization of nitinol stent design.

2017

Nitinol stents continuously experience loadings due to pulsatile pressure, thus a given stent design should possess an adequate fatigue strength and, at the same time, it should guarantee a sufficient vessel scaffolding. The present study proposes an optimization framework aiming at increasing the fatigue life reducing the maximum strut strain along the structure through a local modification of the strut profile.The adopted computational framework relies on nonlinear structural finite element analysis combined with a Multi Objective Genetic Algorithm, based on Kriging response surfaces. In particular, such an approach is used to investigate the design optimization of planar stent cell.The r…

Bioengineered vascular scaffolds: the state of the art

2014

To date, there is increasing clinical need for vascular substitutes due to accidents, malformations, and ischemic diseases. Over the years, many approaches have been developed to solve this problem, starting from autologous native vessels to artificial vascular grafts; unfortunately, none of these have provided the perfect vascular substitute. All have been burdened by various complications, including infection, thrombogenicity, calcification, foreign body reaction, lack of growth potential, late stenosis and occlusion from intimal hyperplasia, and pseudoaneurysm formation. In the last few years, vascular tissue engineering has emerged as one of the most promising approaches for producing …