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Mechanical Valve

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https://www.readbyqxmd.com/read/28722138/a-red-blood-cell-model-to-estimate-the-hemolysis-fingerprint-of-cardiovascular-devices
#1
Riccardo Toninato, Giuseppe Fadda, Francesca Maria Susin
One of the most relevant and open issues within cardiovascular prosthetic hemodynamic performance is a realistic quantification of the damage sustained by red blood cells (RBCs). Specifically, the optimal design of bileaflet mechanical heart valves (BMHVs) requires both low shear stresses along the leaflets and short particle resident times. This study approaches RBC damage estimation by developing a numerical model of RBCs and computing the damage sustained by a set of passive RBCs immersed within in vitro flows...
July 19, 2017: Artificial Organs
https://www.readbyqxmd.com/read/28722131/kept-in-the-loop-longitudinal-strain-volume-relationships-for-the-assessment-of-left-ventricular-mechanical-performance
#2
Stephen P Wright, Robert Lakin, Denise J Wooding, Leah Groves
In health, the aortic valve facilitates unidirectional forward flow from the left ventricle (LV) to the systemic circulation. This article is protected by copyright. All rights reserved.
July 19, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/28719764/surgical-anatomy-does-not-affect-the-progression-of-intestinal-failure-associated-liver-disease-in-neonatal-piglets
#3
Celeste M Lavallee, Pamela R Wizzard, Marihan Lansing, Donna F Vine, Patrick N Nation, Jason Y Yap, Benjamin P Willing, Paul W Wales, Justine M Turner
BACKGROUND: Intestinal failure-associated liver disease (IFALD) causes significant morbidity in neonates with short bowel syndrome (SBS) dependent on parenteral nutrition (PN). Resected ileum, with loss of the ileocecal valve (ICV), is the most common anatomy in SBS, yet its impact on IFALD has not been adequately studied. METHODS: Neonatal piglets were randomized to 75% intestinal resection with jejunocolic anastomosis (JC, n = 12), 75% resection with jejunoileal anastomosis and intact ICV (JI, n = 13), PN-fed sham (sham, n = 14), or sow-fed control (SF, n = 8)...
July 1, 2017: JPEN. Journal of Parenteral and Enteral Nutrition
https://www.readbyqxmd.com/read/28716564/endothelial-to-mesenchymal-transition-in-the-cardiovascular-system
#4
REVIEW
Hui Gong, Xing Lu, Qiong Wang, Min Hu, Xiangyu Zhang
Endothelial to mesenchymal transition (EndMT) is a special type of epithelial to mesenchymal transition. It is a process that is characterized by the loss of features of endothelial cells and acquisition of specific markers of mesenchymal cells. A variety of stimuli, such as inflammation, growth factors, and hypoxia, regulate EndMT through various signaling pathways and intracellular transcription factors. It has been demonstrated that epigenetic modifications are also involved in this process. Recent studies have identified the essential role of EndMT in the cardiovascular system...
July 14, 2017: Life Sciences
https://www.readbyqxmd.com/read/28715132/return-of-neonatal-cpap-resistance-the-medijet-device-family-examined-using-in-vitro-flow-simulations
#5
M Falk, S Donaldsson, B Jonsson, T Drevhammar
AIM: Medijet nasal continuous positive airway pressure (CPAP) generators are a family of devices developed from the Benveniste valve. Previous studies have shown that the in-vitro performance of the Medijet disposable generator was similar to the Neopuff resistor system. We hypothesised that resistance would be the main mechanism of CPAP generation in the Medijet disposable generator. METHODS: The in-vitro performance of the Medijet reusable and disposable systems, the Neopuff resistor system and the Benveniste and Infant Flow non-resistor systems were investigated using static and dynamic bench tests...
July 17, 2017: Acta Paediatrica
https://www.readbyqxmd.com/read/28712720/manual-aspiration-thrombectomy-in-patients-with-acute-stroke-related-calcified-cerebral-emboli
#6
Esther Koh, Hyo Sung Kwak, Gyung-Ho Chung
OBJECTIVE: The aim of this study was to evaluate the effectiveness of mechanical aspiration thrombectomy (MAT) in patients with acute ischemic stroke from calcified cerebral emboli. METHODS: Procedural results were reviewed for acute stroke patients with clinically neurological deficits who underwent recanalization from October 2012 through September 2015. Initial imaging studies and cerebral angiography were analyzed. RESULTS: Of the total number of patients with acute stroke, 5 patients were confirmed to have acute ischemic stroke by calcified cerebral emboli...
July 13, 2017: Journal of Stroke and Cerebrovascular Diseases: the Official Journal of National Stroke Association
https://www.readbyqxmd.com/read/28712585/conduction-disturbance-after-isolated-surgical-aortic-valve-replacement-in-degenerative-aortic-stenosis
#7
You Mi Hwang, Jun Kim, Ji Hyun Lee, Minsu Kim, Jongmin Hwang, Joon Bum Kim, Sung-Ho Jung, Suk Jung Choo, Gi Byoung Nam, Kee Joon Choi, Cheol Hyun Chung, Jae Won Lee, You Ho Kim
OBJECTIVE: Conduction disturbances are common in patients with aortic stenosis. We investigated the incidence, reversibility, and prognosis of conduction disorders requiring permanent pacemaker implantation in patients with degenerative aortic stenosis after isolated aortic valve replacement. METHODS: This was a retrospective study conducted at a tertiary care center. We evaluated the incidence of conduction disturbances in patients who underwent isolated surgical aortic valve replacement for aortic stenosis between January 2005 and May 2015...
June 15, 2017: Journal of Thoracic and Cardiovascular Surgery
https://www.readbyqxmd.com/read/28708210/particle-image-velocimetry-tests-on-pediatric-45-cc-and-30-cc-ventricle-assist-devices-effects-of-heart-rate-on-vad-operation
#8
Dariusz Witkowski, Damian Obidowski, Piotr Reorowicz, Daniel Jodko, Krzysztof Jozwik
BACKGROUND: This study investigated flow analysis inside pediatric ventricle assist devices (VADs) designed and manufactured at the Foundation for Cardiac Surgery Development (FRK), Zabrze, Poland. The main goal of the experiment was to define the minimal heart rate admissible in clinical practice. METHODS: The flow was directed by mechanical, single-disc valves developed at the Lodz University of Technology, Institute of Turbomachinery in Lodz, Poland. VAD operation conditions under different heart rates were analyzed...
July 8, 2017: International Journal of Artificial Organs
https://www.readbyqxmd.com/read/28707559/viscoelastic-properties-of-mitral-valve-leaflets-an-analysis-of-regional-variation-and-frequency-dependency
#9
Jonathan Baxter, Keith G Buchan, Daniel M Espino
The aim of this study was to determine the regional variation in viscoelastic properties of mitral valve leaflets over a range of physiological and patho-physiological frequencies. This included comparisons to be made between anterior and posterior leaflets, anterior leaflet clear and rough zones, and radial and circumferential leaflet orientation. Dynamic mechanical analysis was used to determine frequency-dependent viscoelastic properties. The valve leaflets were dissected from eight porcine hearts. The leaflets were loaded under a sinusoidal tensile displacement, with a mean dynamic peak to trough strain of 11%, applied to all leaflet samples at nine different frequencies, ranging from 0...
July 1, 2017: Proceedings of the Institution of Mechanical Engineers. Part H, Journal of Engineering in Medicine
https://www.readbyqxmd.com/read/28706871/tricuspid-valve-regurgitation-after-heart-transplantation
#10
Murray H Kwon, Richard J Shemin
Tricuspid valve regurgitation (TVR) in the orthotopic heart transplant (OHT) recipient is quite common and has varied clinical sequelae. In its severest forms, it can lead to right-sided failure symptoms indistinguishable from that seen in native heart TVR disease. While certain implantation techniques are widely recognized to reduce the risk of TVR in the cardiac allograft, concomitant tricuspid annuloplasty, while having advocates, is not currently accepted as a routinely established adjunct. Decisions to surgically correct TVR in the OHT recipient must be made carefully, as certain clinical scenarios have high risk of failure...
May 2017: Annals of Cardiothoracic Surgery
https://www.readbyqxmd.com/read/28706178/surgery-for-cardiac-papillary-fibroelastoma-a-12-year-single-institution-experience
#11
Sabreen Mkalaluh, Marcin Szczechowicz, Saeed Torabi, Bashar Dib, Anton Sabashnikov, Ahmed Mashhour, Matthias Karck, Alexander Weymann
BACKGROUND We reviewed our clinical experience with cardiac papillary fibroelastoma from 2005 to 2017. The objective of this study was to investigate the clinical and operative data, as well as the early survival rate and immediate postoperative complications. MATERIAL AND METHODS We performed a retrospective analysis of 11 patients (eight males and three females) who underwent resection of cardiac papillary fibroelastoma in our institution. RESULTS Mean age at tumor diagnosis was 60±14 years. The mean dimension of the tumor was 14±11 mm...
July 14, 2017: Medical Science Monitor Basic Research
https://www.readbyqxmd.com/read/28705798/a-mass-obstructing-mechanical-prosthetic-heart-valve-thrombus-or-pannus
#12
Kunal Mahajan, Sanjeev Asotra, Prakash Negi, Prince Kumar Paul
No abstract text is available yet for this article.
July 13, 2017: BMJ Case Reports
https://www.readbyqxmd.com/read/28704282/excessive-surgical-adhesive-mimicking-aortic-root-abscess-a-case-report
#13
Natalie A Silverton, David A Bull, Candice K Morrissey
Aortic root abscess is a complication of aortic valve endocarditis that is associated with a high morbidity and mortality. The diagnosis usually is made with transesophageal echocardiography, which is highly sensitive and specific for the disease. We present a case of suspected aortic root abscess 1 week after mechanical aortic valve replacement for native valve endocarditis. The diagnosis was made by the use of transesophageal echocardiography but surgical inspection revealed that the paravalvular fluid collection was excessive surgical adhesive...
July 15, 2017: A & A Case Reports
https://www.readbyqxmd.com/read/28699262/recurrent-myocardial-infarction-in-a-47-year-old-woman-with-a-mechanical-mitral-valve-prosthesis-atherosclerosis-embolism-or-spasm
#14
Bimmer E Claessen, Thomas P W van den Boogert, Jan J Piek
We present a case of a 47-year-old woman with a mechanical mitral valve prosthesis and recurrent myocardial infarction. The most common etiology of spontaneous myocardial infarction is an acute coronary syndrome caused by rupture or erosion of an atherosclerotic plaque. However, the differential diagnosis in the patient described below also included infarction due to embolization or coronary spasm. It can be challenging to discriminate between the different causes of myocardial infarction based on interpretation of symptoms, physical examination, laboratory tests, and electrocardiography alone...
July 12, 2017: Catheterization and Cardiovascular Interventions
https://www.readbyqxmd.com/read/28699120/valve-related-modes-of-pump-failure-in-collecting-lymphatics-numerical-and-experimental-investigation
#15
C D Bertram, C Macaskill, M J Davis, J E Moore
Lymph is transported along collecting lymphatic vessels by intrinsic and extrinsic pumping. The walls have muscle of a type intermediate between blood-vascular smooth muscle and myocardium; a contracting segment between two valves (a lymphangion) constitutes a pump. This intrinsic mechanism is investigated ex vivo in isolated, spontaneously contracting, perfused segments subjected to controlled external pressures. The reaction to varying afterload is probed by slowly ramping up the outlet pressure until pumping fails...
July 11, 2017: Biomechanics and Modeling in Mechanobiology
https://www.readbyqxmd.com/read/28698289/mechanism-and-implications-of-the-tricuspid-regurgitation-from-the-pathophysiology-to-the-current-and-future-therapeutic-options
#16
REVIEW
Antonio Mangieri, Claudio Montalto, Matteo Pagnesi, Richard J Jabbour, Josep Rodés-Cabau, Neil Moat, Antonio Colombo, Azeem Latib
The tricuspid valve was virtually ignored for a long time in the past. However, significant tricuspid regurgitation (TR) often accompanies left-side heart valve pathology and does not always reverse with its correction. If left untreated, TR can progress and result in progressive right ventricular failure. Current guideline recommendations still hold minor differences. Nevertheless, there is a consensus to operate on patients with severe TR undergoing left-sided valve surgery (class I) or those with mild to moderate TR with a dilated annulus (≥40 or ≥21 mm(2), Class IIa)...
July 2017: Circulation. Cardiovascular Interventions
https://www.readbyqxmd.com/read/28697893/mechanical-valves-in-the-pulmonary-position-an-international-retrospective-analysis
#17
Hanna Pragt, Joost P van Melle, Hoda Javadikasgari, Dong Man Seo, John M Stulak, Igor Knez, Jürgen Hörer, Christian Muñoz-Guijosa, Mahyar G Dehaki, Hong Ju Shin, Joseph A Dearani, Maziar G Dehaki, Petronella G Pieper, Christine Eulenburg, Laura Dos, Tjark Ebels
OBJECTIVE: Life expectancy of patients with congenital heart disease has improved over the past decades, increasing the need for a durable pulmonary prosthetic valve. Biological valves in various forms have become the valve of choice for pulmonary valve replacement (PVR), but structural valve deterioration is unavoidable in the long term. Use of a mechanical valve could be an alternative, but data on long-term outcomes are sparse. METHODS: We retrospectively collected and analyzed data on 364 patients with mechanical valves implanted in the pulmonary position between 1965 and 2014...
May 20, 2017: Journal of Thoracic and Cardiovascular Surgery
https://www.readbyqxmd.com/read/28695557/impact-of-new-technologies-and-experience-on-procedural-aspects-of-surgical-aortic-valve-replacement-a-process-analysis
#18
Bettina Langhammer, Maria Nucera, Lars Englberger, Eva Roost, David Reineke, Florian Schönhoff, Henriette Most, Bernhard Winkler, Fabian Gisler, Thierry Carrel, Christoph Huber
BACKGROUND: Surgical aortic valve replacement (SAVR) is the treatment of choice in severe symptomatic aortic valve disease. New techniques and prostheses have been recently developed to facilitate the procedure and reduce aortic cross-clamp time (AOx). The aim of this study was to analyse the different procedural steps in order to identify the most time-consuming part during aortic clamping time and to compare impact of experience on procedural aspects. METHODS: AOx during SAVR was divided into five consecutive steps...
July 11, 2017: Swiss Medical Weekly
https://www.readbyqxmd.com/read/28692845/constitutive-modeling-of-jugular-vein-derived-venous-valve-leaflet-tissues
#19
Nayyan Kaul, Hsiao-Ying Shadow Huang
Venous valve tissues, though used in vein reconstruction surgeries and bioprosthetic valves with moderate success, have not been extensively studied with respect to their structure. Their inherent anisotropic, non-linear behavior combined with severe diseases which affect veins, such as chronic venous insufficiency, warrant understanding the structure and material behavior of these tissues. Hence, before any bioprosthetic grafts may be used in place of tissues, it is of the utmost importance to understand the mechanical and structural properties of these tissues as this may lead to higher success rates for valve replacement surgeries...
July 1, 2017: Journal of the Mechanical Behavior of Biomedical Materials
https://www.readbyqxmd.com/read/28691909/fracturing-mechanics-before-valve-in-valve-therapy-of-small-aortic-bioprosthetic-heart-valves
#20
Peter Johansen, Henrik Engholt, Mariann Tang, Rasmus F Nybo, Per D Rasmussen, Jens Erik Nielsen-Kudsk
AIMS: Patients with degraded bioprosthetic heart valves (BHV) who are not candidates for valve replacement may benefit from transcatheter valve-in-valve (VIV) therapy. However, at smaller sized surgical BHV the resultant orifice may become too narrow. To overcome this, the valve frame can be fractured by a high-pressure balloon prior to VIV. However, knowledge on fracture pressures and mechanics are prerequisites. The aim of this study is to identify the fracture pressures needed in BHV, and to describe the fracture mechanics...
July 11, 2017: EuroIntervention
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