共查询到20条相似文献,搜索用时 15 毫秒
1.
H. G. Freling Y. J. van Slooten J. P. van Melle B. J. M. Mulder A. P. J. van Dijk H. L. Hillege M. C. Post G. Tj. Sieswerda M. R. M. Jongbloed T. P. Willems P. G. Pieper 《Netherlands heart journal》2012,20(10):419-424
Background
Data on long-term complications in adult patients with congenital heart disease (ACHD) and a prosthetic valve are scarce. Moreover, the influence of prosthetic valves on quality of life (QoL) and functional outcome in ACHD patients with prosthetic valves has not been studied.Objectives
The primary objective of the PROSTAVA study is to investigate the relation between prosthetic valve characteristics (type, size and location) and functional outcome as well as QoL in ACHD patients. The secondary objectives are to investigate the prevalence and predictors of prosthesis-related complications including prosthesis-patient mismatch.Methods
The PROSTAVA study, a multicentre cross-sectional observational study, will include approximately 550 ACHD patients with prosthetic valves. Primary outcome measures are maximum oxygen uptake during cardiopulmonary exercise testing and QoL. Secondary outcomes are the prevalence and incidence of valve-related complications including prosthesis-patient mismatch. Other evaluations are medical history, physical examination, echocardiography, MRI, rhythm monitoring and laboratory evaluation (including NT-proBNP).Implications
Identification of the relation between prosthetic valve characteristics in ACHD patients on one hand and functional outcome, QoL, the prevalence and predictors of prosthesis-related complications on the other hand may influence the choice of valve prosthesis, the indication for more extensive surgery and the indication for re-operation. 相似文献2.
Background
We examined whether impaired renal function causes thickening of the aortic valve leaflets in hyperlipidemic apoE-knockout (apoE-/-) mice, and whether the putative effect on the aortic valves could be prevented by inhibiting the angiotensin-converting enzyme (ACE) with enalapril.Methods
Thickening of the aortic valve leaflets in apoE-/- mice was induced by producing mild or moderate chronic renal failure resulting from unilateral nephrectomy (1/2 NX, n = 18) or subtotal nephrectomy (5/6 NX, n = 22), respectively. Additionally, the 5/6 NX mice were randomized to no treatment (n = 8) or enalapril treatment (n = 13). The maximal thickness of each leaflet was measured from histological sections of the aortic roots.Results
Leaflet thickness was significantly greater in the 5/6 NX mice than in the 1/2 NX mice (P = 0.030) or the unoperated mice (P = 0.003). The 5/6 NX mice treated with enalapril had significantly thinner leaflets than did the untreated 5/6 NX mice (P = 0.014).Conclusion
Moderate uremia causes thickening of the aortic valves in apoE-/- mice, which can be attenuated by ACE inhibition. The nephrectomized apoE-/- mouse constitutes a new model for investigating the mechanisms of uremia-induced aortic valve disease, and also provides an opportunity to study its pharmacologic prevention. 相似文献3.
Stéphane Cosson Jean-Philippe Kevorkian Paul Milliez Philippe Beaufils Ariel Cohen 《Cardiovascular ultrasound》2003,1(1):1-4
Background
Right-sided endocarditis occurs predominantly in intravenous drug users, patients with pacemakers or central venous lines and with congenital heart diseases. The vast majority of cases involve the tricuspid valve.Case presentation
A case of a 31-year-old woman with intravenous drug abuse who had a right-sided vegetation attached to the muscular bundle of the right ventricle is presented. Transthoracic echocardiography revealed a vegetation in the right ventricular outflow tract. Transesophageal echocardiography clearly showed that the 1.8 cm vegetation was not adherent to the pulmonary valve but attached to a muscular bundle.Conclusions
Our case points to an unusual location of right-sided endocarditis in intravenous drug users. It confirms that TTE remains an easy and highly sensitive first-line examination for the diagnosis of right-sided endocarditis. 相似文献4.
Improved scaling of minirhizotron data using an empirically-derived depth of field and correcting for the underestimation of root diameters 总被引:2,自引:0,他引:2
Benton N. Taylor Katilyn V. Beidler Allan E. Strand Seth G. Pritchard 《Plant and Soil》2014,374(1-2):941-948
Background and aims
Accurate data on the standing crop, production, and turnover of fine roots is essential to our understanding of major terrestrial ecological processes. Minirhizotrons offer a unique opportunity to study the dynamic processes of root systems, but are susceptible to several measurement biases.Methods
We use roots extracted from minirhizotron tube surfaces to calculate the depth of field of a minirhizotron image and present a model to correct for the underestimation of root diameters obscured by soil in minirhizotron images.Results
Non-linear regression analysis resulted in an estimated depth of field of 0.78 mm for minirhizotron images. Unadjusted minirhizotron data underestimated root net primary production and fine root standing crop by 61 % when compared to adjusted data using our depth of field and root diameter corrections. Changes in depth of field accounted for >99 % of standing crop adjustments with root diameter corrections accounting for <1 %.Conclusions
Our results represent the first effort to empirically derive depth of field for minirhizotron images. This work may explain the commonly reported underestimation of fine roots using minirhizotrons, and stands to improve the ability of researchers to accurately scale minirhizotron data to large soil volumes. 相似文献5.
Objective
To quantify and compare the forces exerted by scoliosis patients in fiberglass braces during exercises usually prescribed in departments where casts are made. The exercises are intended to increase corrective forces, activate muscles, stimulate ventilation and help the patient psychologically.Setting
Outpatient care.Patients
17 consecutive adolescent patients wearing fiberglass brace for idiopathic scoliosis.Interventions
Exercises (kyphotization, rotation, "escape from the pad") in different positions (sitting, supine, on all fours).Main outcome measure
Pressure detected by the F-Socket System between the rib hump and the pad of the brace.Results
In static and dynamic conditions, the position adopted did not alter the total pressure exerted by the brace, although the part of the sensor stimulated did vary. Kyphotization and rotation exercises produced a significant increase of pressure (+ 58.9% and +29.8%, respectively); however, the "escape from the pad" exercise, despite its name, did not produce any significant variation of pressure.Conclusion
Exercises in the brace allow adjunctive forces to be applied on soft tissues and through them, presumably on the spine. Different exercises can be chosen to obtain different actions. Physical exercises and sporting activities are useful in mechanical terms, although other important actions should not be overlooked. 相似文献6.
Istemihan Tengiz Ertugrul Ercan Emin Alioglu Ugur O Turk 《BMC cardiovascular disorders》2006,6(1):1-5
Background
Mid-ventricular obstructive hypertrophic cardiomyopathy (MVOHC) is a rare type of cardiomyopathy. The diagnosis is based on the hourglass appearance on the left ventriculogram and the presence of pressure gradient between apical and basal chamber of the ventriculum on the hemodynamic assessment.Case presentation
The present case represents successful percutaneous treatment with septal ablation to patient with MVOHC associated with systolic anterior motion of the mitral valve and obstruction at both the mid-ventricular and outflow levels.Conclusion
Alcohol septal ablation has been proposed as less invasive alternatives to surgery in patients with MVOHC. 相似文献7.
I. C. Joziasse A. Vink M. J. Cramer M. F. M. van Oosterhout L. A. van Herwerden R. Heijmen G. T. J. Sieswerda B. J. M. Mulder P. A. Doevendans 《Netherlands heart journal》2011,19(3):119-125
Background
Bicuspid aortic valve (BAV) is one of the most common congenital heart defects with a population prevalence of 0.5% to 1.3%. Identifying patients with BAV is clinically relevant because BAV is associated with aortic stenosis, endocarditis and ascending aorta pathology.Methods and Results
Patients with severe aortic stenosis necessitating aortic valve replacement surgery were included in this study. All dissected aortic valves were stored in the biobank of the University Medical Centre Utrecht. Additionally to the morphological assessment of the aortic valve by the surgeon and pathologist, echocardiographic and magnetic resonance imaging (MRI) images were evaluated. A total of 80 patients were included of whom 32 (40%) were diagnosed with BAV by the surgeon (gold standard). Patients with BAV were significantly younger (55 vs 71 years) and were more frequently male. Notably, a significant difference was found between the surgeon and pathologist in determining valve morphology. MRI was performed in 33% of patients. MRI could assess valve morphology in 96% vs 73% with echocardiography. The sensitivity of MRI for BAV in a population of patients with severe aortic stenosis was higher than echocardiography (75% vs 55%), whereas specificity was better with the latter (91% vs 79%). Typically, the ascending aorta was larger in patients with BAV.Conclusion
Among unselected patients with severe aortic valve stenosis, a high percentage of patients with BAV were found. Imaging and assessment of the aortic valve morphology when stenotic is challenging. 相似文献8.
Venous valve incompetence has been implicated in diseases ranging from chronic venous insufficiency (CVI) to intracranial venous hypertension. However, while the mechanical properties of venous valve leaflet tissues are central to CVI biomechanics and mechanobiology, neither stress–strain curves nor tangent moduli have been reported. Here, equibiaxial tensile mechanical tests were conducted to assess the tangent modulus, strength and anisotropy of venous valve leaflet tissues from bovine jugular veins. Valvular tissues were stretched to 60% strain in both the circumferential and radial directions, and leaflet tissue stress–strain curves were generated for proximal and distal valves (i.e., valves closest and furthest from the right heart, respectively). Toward linking mechanical properties to leaflet microstructure and composition, Masson’s trichrome and Verhoeff–Van Gieson staining and collagen assays were conducted. Results showed: (1) Proximal bovine jugular vein venous valves tended to be bicuspid (i.e., have two leaflets), while distal valves tended to be tricuspid; (2) leaflet tissues from proximal valves exhibited approximately threefold higher peak tangent moduli in the circumferential direction than in the orthogonal radial direction (i.e., proximal valve leaflet tissues were anisotropic; \(p<0.01\)); (3) individual leaflets excised from the same valve apparatus appeared to exhibit different mechanical properties (i.e., intra-valve variability); and (4) leaflets from distal valves exhibited a trend of higher soluble collagen concentrations than proximal ones (i.e., inter-valve variability). To the best of the authors’ knowledge, this is the first study reporting biaxial mechanical properties of venous valve leaflet tissues. These results provide a baseline for studying venous valve incompetence at the tissue level and a quantitative basis for prosthetic venous valve design. 相似文献
9.
Identification of pathogens in culture-negative infective endocarditis cases by metagenomic analysis
Jun Cheng Huan Hu Yue Kang Weizhi Chen Wei Fang Kaijuan Wang Qian Zhang Aisi Fu Shuilian Zhou Chen Cheng Qingqing Cao Feiyan Wang Shela Lee Zhou Zhou 《Annals of clinical microbiology and antimicrobials》2018,17(1):43
Background
Pathogens identification is critical for the proper diagnosis and precise treatment of infective endocarditis (IE). Although blood and valve cultures are the gold standard for IE pathogens detection, many cases are culture-negative, especially in patients who had received long-term antibiotic treatment, and precise diagnosis has therefore become a major challenge in the clinic. Metagenomic sequencing can provide both information on the pathogenic strain and the antibiotic susceptibility profile of patient samples without culturing, offering a powerful method to deal with culture-negative cases.Methods
To assess the feasibility of a metagenomic approach to detect the causative pathogens in resected valves from IE patients, we employed both next-generation sequencing and Oxford Nanopore Technologies MinION nanopore sequencing for pathogens and antimicrobial resistance detection in seven culture-negative IE patients. Using our in-house developed bioinformatics pipeline, we analyzed the sequencing results generated from both platforms for the direct identification of pathogens from the resected valves of seven clinically culture-negative IE patients according to the modified Duke criteria.Results
Our results showed both metagenomics methods can be applied for the causative pathogen detection in all IE samples. Moreover, we were able to simultaneously characterize respective antimicrobial resistance features.Conclusion
Metagenomic methods for IE detection can provide clinicians with valuable information to diagnose and treat IE patients after valve replacement surgery. However, more efforts should be made to optimize protocols for sample processing, sequencing and bioinformatics analysis.10.
Ashraf M Anwar Youssef FM Nosir Siti Khairani Zainal-Abidin Aref Ajam Hassan Chamsi-Pasha 《Cardiovascular ultrasound》2012,10(1):1-13
Aim of the work
To evaluate the feasibility and possible additional value of transthoracic real-time three-dimensional echocardiography (RT3D-TTE) for the assessment of cardiac structures as compared to 2D-TTE.Methods
320 patients (mean age 45 ± 8.4 years, 75% males) underwent 2D-TTE and RT3D-TTE using 3DQ-Q lab software for offline analysis. Volume quantification and functional assessment was performed in 90 patients for left ventricle and in 20 patients for right ventricle. Assessment of native (112 patients) and prosthetic (30 patients) valves morphology and functions was performed. RT3D-TTE was performed for evaluation of septal defects in 30 patients and intracardiac masses in 52 patients.Results
RT3D-TTE assessment of left ventricle was feasible and reproducible in 86% of patients while for right ventricle, it was (55%). RT3D-TTE could define the surface anatomy of mitral valve optimally (100%), while for aortic and tricuspid was (88% and 81% respectively). Valve area could be planimetered in 100% for the mitral and in 80% for the aortic. RT3D-TTE provided a comprehensive anatomical and functional evaluation of prosthetic valves. RT3D-TTE enface visualization of septal defects allowed optimal assessment of shape, size, area and number of defects and evaluated the outcome post device closure. RT3D-TTE allowed looking inside the intracardiac masses through multiple sectioning, valuable anatomical delineation and volume calculation.Conclusion
Our initial experience showed that the use of RT3D-TTE in the assessment of cardiac patients is feasible and allowed detailed anatomical and functional assessment of many cardiac disorders. 相似文献11.
Background
Generally, utility based decision making models focus on experimental outcomes. In this paper we propose a utility model based on molecular diffusion to simulate the choice behavior of Drosophila larvae exposed to different light conditions.Methods
In this paper, light/dark choice-based Drosophila larval phototaxis is analyzed with our molecular diffusion based model. An ISCEM algorithm is developed to estimate the model parameters.Results
By applying this behavioral utility model to light intensity and phototaxis data, we show that this model fits the experimental data very well.Conclusions
Our model provides new insights into decision making mechanisms in general. From an engineering viewpoint, we propose that the model could be applied to a wider range of decision making practices. 相似文献12.
Charlie Strange Felix JF Herth Kevin L Kovitz Geoffrey McLennan Armin Ernst Jonathan Goldin Marc Noppen Gerard J Criner Frank C Sciurba 《BMC pulmonary medicine》2007,7(1):1-12
Background
Lung volume reduction surgery is effective at improving lung function, quality of life, and mortality in carefully selected individuals with advanced emphysema. Recently, less invasive bronchoscopic approaches have been designed to utilize these principles while avoiding the associated perioperative risks. The Endobronchial Valve for Emphysema PalliatioN Trial (VENT) posits that occlusion of a single pulmonary lobe through bronchoscopically placed Zephyr® endobronchial valves will effect significant improvements in lung function and exercise tolerance with an acceptable risk profile in advanced emphysema.Methods
The trial design posted on Clinical trials.gov, on August 10, 2005 proposed an enrollment of 270 subjects. Inclusion criteria included: diagnosis of emphysema with forced expiratory volume in one second (FEV1) < 45% of predicted, hyperinflation (total lung capacity measured by body plethysmography > 100%; residual volume > 150% predicted), and heterogeneous emphysema defined using a quantitative chest computed tomography algorithm. Following standardized pulmonary rehabilitation, patients were randomized 2:1 to receive unilateral lobar placement of endobronchial valves plus optimal medical management or optimal medical management alone. The co-primary endpoint was the mean percent change in FEV1 and six minute walk distance at 180 days. Secondary end-points included mean percent change in St. George's Respiratory Questionnaire score and the mean absolute changes in the maximal work load measured by cycle ergometry, dyspnea (mMRC) score, and total oxygen use per day. Per patient response rates in clinically significant improvement/maintenance of FEV1 and six minute walk distance and technical success rates of valve placement were recorded. Apriori response predictors based on quantitative CT and lung physiology were defined.Conclusion
If endobronchial valves improve FEV1 and health status with an acceptable safety profile in advanced emphysema, they would offer a novel intervention for this progressive and debilitating disease.Trial Registration
ClinicalTrials.gov: NCT00129584 相似文献13.
Constantina Aggeli Ioannis Felekos Christina Kazazaki Dimitrios Giannopoulos Athanasios Kartalis Christos Pitsavos Christodoulos Stefanadis 《Cardiovascular ultrasound》2010,8(1):1-4
Introduction
The anterior mitral leaflet cleft is an unusual congenital lesion most often encountered in association with other congenital heart defects. The isolated anterior leaflet cleft is quite a rare anomaly and is usually cause of mitral valve regurgitation. The importance of the lesion is that it is often correctable. When feasible, cleft suture and, eventually, annuloplasty are preferable to valve replacement. Echocardiography is the first choice technique in the evaluation of mitral valve disease, providing useful information about valve anatomy and hemodynamic parameters.Case presentation
We present a case of an isolated anterior mitral leaflet cleft producing moderate-severe mitral regurgitation correctly identified by echocardiography and successfully surgically corrected.Conclusion
Isolated cleft is a rare aberration, that has to be known in order to be diagnosed. Transthoracic and transesophageal echocardiography is the most useful non invasive technique for cleft diagnosis and to indicate the right surgical correction. 相似文献14.
Abdelkarime K Jahrome Imo Hoefer Frans L Moll Graeme J Houston Peter A Stonebridge Peter J Blankestijn Gert J de Borst 《Annals of surgical innovation and research》2010,4(1):1-4
Purpose
Previously, we developed a porcine model for Arterio Venous Graft (AVG) failure to allow assessment of new access strategies. This model was limited concerning graft length. In the present technical report, we describe a modification of our model allowing the assessment of long AVGs.Technique
In 4 pigs, AVGs of 15 cm length were created bilaterally in a cross-over fashion between the carotid artery and the contralateral jugular vein. Two days (2 pigs) and two weeks (2 pigs) after AV shunting, graft patency was evaluated by angiography, showing all four grafts to be patent, with no sign of angiographic or macroscopic narrowing at the anastomoses sites.Conclusions
In this modified pig AVG failure model, implantation of a bilateral cross-over long AVG is a feasible approach. The present model offers a suitable tool to study local interventions or compare various long graft designs aimed at improvement of AVG patency. 相似文献15.
Background
Bacillus organisms are common laboratory contaminants. The majority of Bacillus bacteraemias are transient and not clinically significant. Clinically significant infection due to Bacillus species is rare and mostly due to Bacillus cereus infections in immuno-compromised hosts.Case presentation
We report a case of central venous catheter infection with Bacillus pumilus in an immunocompetent child with tufting enteropathy on long-term parenteral nutrition (PN). There were three episodes of central venous catheter infection with Bacillus pumilus in three months. Despite adequate and appropriate use of intravenous antibiotics, the infection failed to clear resulting in the need for removal of the catheter for complete cure.Conclusion
Bacillus species can cause clinically significant central venous catheter infection, even in an immunocompetent host. Despite adequate antibiotic treatment, the central venous catheter may need removal for complete cure. 相似文献16.
R. C. Schoonbeek P. G. Pieper Y. J. van Slooten H. G. Freling G. T. Sieswerda A. P. J. van Dijk M. R. M. Jongbloed M. C. Post B. J. Bouma R. M. F. Berger T. Ebels J. P. van Melle 《Netherlands heart journal》2016,24(11):653-665
Objectives
N-terminal B?type natriuretic peptide (NT-proBNP) is an important biomarker for the detection of heart failure. Adults with congenital heart disease (ACHD) and a prosthetic heart valve are at risk for heart failure. This study aimed to determine the value of NT-proBNP in ACHD patients with a prosthetic valve and investigate its relationship with cardiac function and exercise capacity.Methods
In this multi-centre cross-sectional observational study, data regarding medical history, echocardiography, exercise testing (VO2peak) and laboratory blood evaluation (including NT-proBNP) were collected in ACHD patients with a single prosthetic valve (either homografts, heterografts or mechanical valves).Results
A total of 306 ACHD patients with pulmonary valve replacement (PVR, n = 139), aortic valve replacement (n = 141), mitral valve replacement (n = 21) or tricuspid valve replacement (n = 5) were investigated. The majority of patients (77?%) were in NYHA class I or II. Elevated NT-proBNP levels (cut-off ≥125 pg/ml) were found in 50?% of the patients, with the highest levels in patients with mitral valve replacements. In this study population, NT-proBNP levels were associated with gender (p = 0.029) and VO2max (p < 0.001). In PVR patients, NT-proBNP levels were associated with lower VO2peak, also after adjustment for age, gender and age at valve replacement in a multivariate model (p = 0.015).Conclusions
In patients with ACHD and a prosthetic valve, elevated NT-proBNP levels are frequently observed despite preserved NYHA class. In PVR patients, a higher NT-proBNP level was associated with a lower VO2peak. These results may be of importance in the ongoing discussion about the timing of valve replacement in patients with CHD.17.
Ehsan Vaghefi Duane TK Malcolm Marc D Jacobs Paul J Donaldson 《Biomedical engineering online》2012,11(1):1-27
Background
It has been proposed that in the absence of a blood supply, the ocular lens operates an internal microcirculation system. This system delivers nutrients, removes waste products and maintains ionic homeostasis in the lens. The microcirculation is generated by spatial differences in membrane transport properties; and previously has been modelled by an equivalent electrical circuit and solved analytically. While effective, this approach did not fully account for all the anatomical and functional complexities of the lens. To encapsulate these complexities we have created a 3D finite element computer model of the lens.Methods
Initially, we created an anatomically-correct representative mesh of the lens. We then implemented the Stokes and advective Nernst-Plank equations, in order to model the water and ion fluxes respectively. Next we complemented the model with experimentally-measured surface ionic concentrations as boundary conditions and solved it.Results
Our model calculated the standing ionic concentrations and electrical potential gradients in the lens. Furthermore, it generated vector maps of intra- and extracellular space ion and water fluxes that are proposed to circulate throughout the lens. These fields have only been measured on the surface of the lens and our calculations are the first 3D representation of their direction and magnitude in the lens.Conclusion
Values for steady state standing fields for concentration and electrical potential plus ionic and fluid fluxes calculated by our model exhibited broad agreement with observed experimental values. Our model of lens function represents a platform to integrate new experimental data as they emerge and assist us to understand how the integrated structure and function of the lens contributes to the maintenance of its transparency. 相似文献18.
Objectives
To describe percutaneous embolization of varicocele and to evaluate the effect on fertility disorders.Materials and methods
One hundred nineteen patients, aged 11 to 48 years, underwent percutaneous embolization for varicocele indicated by a fertility disorder in 23% of cases. Correction of the varicocele and resolution of associated pain, improvement of testicular trophicity and the effect on fertility were studied and a review of the literature was performed.Results
Percutaneous embolization was performed using neuroleptanalgesia on an outpatient basis. The technique combined venous sclerotherapy and placement of coils in the gonadal vein. The technique was successful in 95% of cases and one complication was observed. At 3 months, the varicocele and related pain had resolved in 98% of treated patients. According to previous reports in the literature, the relations between varicocele and fertility disorders are still unclear, but improvement of fertility (semen quality and conception rates) after varicocele repair has been established.Conclusion
Although the consequences of varicocele on fertility have not been fully elucidated, treatment of varicocele appears to be beneficial. Percutaneous embolization of varicocele is a safe and effective alternative to surgery. This technique, based on a urological and radiological consensus, is the first-line treatment for varicocele in our institution. 相似文献19.
Bharat Rekhi Sophia George Bhulaxmi Madur RF Chinoy Rajesh Dikshit Amita Maheshwari 《Diagnostic pathology》2008,3(1):1-7
Introduction
Intravascular lesions of the hand comprise reactive and neoplastic entities. The clinical diagnosis of such lesions is often difficult, and usually requires pathologic examination. We present the largest series to date of intravascular lesions affecting the hand.Methods
A retrospective review of intravascular (arterial and venous) lesions involving the hand was conducted. Data regarding clinicopathologic findings were analyzed.Results
We identified 10 patients with intravascular lesions of their hands including thromboemboli (n = 3), reactive intravascular conditions such as papillary endothelial hyperplasia or Masson's tumor (n = 2) and fasciitis (n = 1), as well as vascular neoplasms including pyogenic granuloma (n = 2) and angioleiomyoma (n = 2).Conclusion
Blood vessel injury and/or venous thrombosis may predispose to several intravascular lesions of the hand. Recognition of reactive entities from neoplastic conditions is important. 相似文献20.
Grassland root demography responses to multiple climate change drivers depend on root morphology 总被引:1,自引:0,他引:1
R. Pilon C. Picon-Cochard J. M. G. Bloor S. Revaillot E. Kuhn R. Falcimagne P. Balandier J.-F. Soussana 《Plant and Soil》2013,364(1-2):395-408