Hemodynamics of Ulcerated Plaques: Before and After

2010 ◽  
Vol 132 (10) ◽  
Author(s):  
Megan Cummins ◽  
Jenn Stroud Rossmann
Keyword(s):  
Flow Patterns ◽  
Secondary Flows ◽  
Patient Specific ◽  
Governing Equations ◽  
Unstable Plaque ◽  
Vessel Remodeling ◽  
Before And After ◽  
Recirculation Zones ◽  
Insight Into

The hemodynamics and fluid mechanical forces in blood vessels have long been implicated in the deposition and growth of atherosclerotic plaque. Detailed information about the hemodynamics in vessels affected by significant plaque deposits can also provide insight into the mechanisms and likelihood of plaque weakening and rupture. In the current study, the governing equations are solved in their finite volume formulation in several patient-specific stenotic geometries. Of specific interest are the flow patterns and forces near ulcerations in the plaque. The flow patterns and forces in vessels with ulcerated plaques are compared with those in stenotic vessels without evidence of ulceration and to the hemodynamics in the same vessels as they likely appeared prior to ulceration. Hemodynamics “before” and “after” hemorrhage may suggest fluid mechanical and morphological factors of diagnostic and predictive value. Recirculation zones, vortex shedding, and secondary flows are captured by both laminar and turbulent solutions. The forces on vessel walls are shown to correlate with unstable plaque deposits. Performing before and after studies of vessels in long-term radiology studies may illuminate mechanisms of hemorrhage and other vessel remodeling.

Numerical Simulation of Blood Flow in Patient-Specific Stenotic Carotid Bifurcation Geometries

2009 ◽  
Author(s):  
Megan Cummins ◽  
Jenn S. Rossmann
Keyword(s):  
Vortex Shedding ◽  
Carotid Bifurcation ◽  
Secondary Flows ◽  
Patient Specific ◽  
Mechanical Forces ◽  
Plaque Vulnerability ◽  
Governing Equations ◽  
Unstable Plaque ◽  
Recirculation Zones ◽  
Insight Into

The hemodynamics and fluid mechanical forces in blood vessels have long been implicated in the deposition and growth of atherosclerotic plaque. Detailed information about the hemodynamics in vessels affected by significant plaque deposits can provide insight into the mechanisms and likelihood of plaque weakening and rupture. In the current study, the governing equations are solved in their finite volume formulation in several patient-specific geometries. Recirculation zones, vortex shedding, and secondary flows are captured. The forces on vessel walls are shown to correlate with unstable plaque deposits. The results of these simulations suggest morphological features that may usefully supplement percent stenosis as a predictor of plaque vulnerability.

Improved Patient-Specific Coronary Artery Graft Configurations Using CFD Coupled Shape Optimizer

2009 ◽  
Author(s):  
Onur Dur ◽  
Sinan T. Coskun ◽  
Levent B. Kara ◽  
Kerem Pekkan
Keyword(s):  
Coronary Artery ◽  
Artery Bypass ◽  
Patient Specific ◽  
Coronary Artery Bypass Grafts ◽  
Shear Stresses ◽  
Graft Occlusion ◽  
Surgical Anastomosis ◽  
Artery Graft ◽  
Recirculation Zones

Bypass conduits provide an alternative route around critically blocked arteries. Current surgical anastomosis techniques and the design of synthetic coronary artery bypass grafts (CABG) frequently lead to post-surgical complications such as intimal thickening, restenosis and eventual long term graft failure. Pathological hemodynamic states are usually precursors of intimal hyperplasia or platelet deposition and result in graft occlusion. From fluid mechanics perspective, abnormalities in coronary flow include recirculation zones, low/oscillating shear stresses, vortices, and areas of stagnation within the CABG.

scholarly journals Incomplete Restoration of Homeostatic Shear Stress Within Arteriovenous Fistulae

2012 ◽  
Vol 135 (1) ◽  
Author(s):  
Patrick M. McGah ◽  
Daniel F. Leotta ◽  
Kirk W. Beach ◽  
R. Eugene Zierler ◽  
Alberto Aliseda
Keyword(s):  
3D Ultrasound ◽  
Patient Specific ◽  
Shear Stresses ◽  
Arteriovenous Fistulae ◽  
Vessel Remodeling ◽  
Mechanical Homeostasis ◽  
Stage Renal Disease ◽  
End Stage ◽  
Hemodynamic Simulations

Arteriovenous fistulae are surgically created to provide adequate access for dialysis patients suffering from end-stage renal disease. It has long been hypothesized that the rapid blood vessel remodeling occurring after fistula creation is, in part, a process to restore the mechanical stresses to some preferred level, i.e., mechanical homeostasis. We present computational hemodynamic simulations in four patient-specific models of mature arteriovenous fistulae reconstructed from 3D ultrasound scans. Our results suggest that these mature fistulae have remodeled to return to ‘‘normal’’ shear stresses away from the anastomoses: about 1.0 Pa in the outflow veins and about 2.5 Pa in the inflow arteries. Large parts of the anastomoses were found to be under very high shear stresses >15 Pa, over most of the cardiac cycle. These results suggest that the remodeling process works toward restoring mechanical homeostasis in the fistulae, but that the process is limited or incomplete, even in mature fistulae, as evidenced by the elevated shear at or near the anastomoses. Based on the long term clinical viability of these dialysis accesses, we hypothesize that the elevated nonhomeostatic shear stresses in some portions of the vessels were not detrimental to fistula patency.

Patient-specific models of human trachea to predict mechanical consequences of endoprosthesis implantation

2010 ◽  
Vol 368 (1921) ◽  
pp. 2881-2896 ◽  
Author(s):  
A. Pérez del Palomar ◽  
O. Trabelsi ◽  
A. Mena ◽  
J. L. López-Villalobos ◽  
A. Ginel ◽  
...  
Keyword(s):  
Real Data ◽  
Patient Specific ◽  
Adaptation Algorithm ◽  
Specific Patient ◽  
Before And After ◽  
Operative Planning ◽  
Human Trachea ◽  
Insight Into ◽  
Endoprosthesis Implantation

Nowadays, interventions associated with the implantation of tracheal prostheses in patients with airway pathologies are very common. This surgery may promote problems such as migration of the prosthesis, development of granulation tissue at the edges of the stent with overgrowth of the tracheal lumen or accumulation of secretions inside the prosthesis. Among the movements that the trachea carries out, swallowing seems to have harmful consequences for the tracheal tissues surrounding the prosthesis. In this work, a finite-element-based tool is presented to construct patient-specific tracheal models, introducing the endotracheal prosthesis and analysing the mechanical consequences of this surgery during swallowing. A complete description of a patient-specific tracheal model is given, and a fully experimental characterization of the tracheal tissues is presented. To construct patient-specific grids, a mesh adaptation algorithm has been developed and the implantation of a tracheal prosthesis is simulated. The ascending deglutition movement of the trachea is recorded using real data from each specific patient from fluoroscopic images before and after implantation. The overall behaviour of the trachea is modified when a prosthesis is introduced. The presented tool has been particularized for two different patients (patient A and patient B), allowing prediction of the consequences of this kind of surgery. In particular, patient A had a decrease of almost 30 per cent in his ability to swallow, and an increase in stresses that were three times higher after prosthesis implantation. In contrast, patient B, who had a shorter trachea and who seemed to undergo more damaging effects, did not have a significant reduction in his ability to swallow and did not present an increase in stress in the tissues. In both cases, there are clinical studies that validate our results: namely, patient A underwent a further intervention whereas the outcome of patient B’s surgery was completely successful. Notwithstanding the fact that there are a lot of uncertainties relating to the implantation of endotracheal prostheses, the present work gives a new insight into these procedures, predicting their mechanical consequences. This tool could be used in the future as pre-operative planning software to help thoracic surgeons in deciding the optimal prosthesis as well as its size and positioning.

scholarly journals The Numerical Study of the Hemodynamic Characteristics in the Patient-Specific Intracranial Aneurysms before and after Surgery

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
Jun Soo Byun ◽  
Sun-Young Choi ◽  
Taewon Seo
Keyword(s):  
Numerical Study ◽  
Cerebral Arteries ◽  
Three Dimensional ◽  
Vascular Wall ◽  
Flow Patterns ◽  
Aneurysm Rupture ◽  
Patient Specific ◽  
Jet Streams ◽  
Before And After ◽  
Hemodynamic Characteristics

The patient-specific pre- and postsurgery cerebral arterial geometries in the study were reconstructed from computed tomography angiography (CTA). Three-dimensional computational fluid dynamics models were used to investigate the hemodynamic phenomena in the cerebral arteries before and after surgery of the aneurysm under realistic conditions. CFD simulations for laminar flow of incompressible Newtonian fluid were conducted by using commercial software, ANSYS v15, with the rigid vascular wall assumption. The study found that the flow patterns with the complex vortical structures inside the aneurysm were similar. We also found that the inflow jet streams were coming strongly in aneurysm sac in the presurgery models, while the flow patterns in postsurgery models were quite different from those in presurgery models. The average wall shear stress after surgery for model 1 was approximately three times greater than that before surgery, while it was about twenty times greater for model 2. The area of low WSS in the daughter saccular aneurysm region in model 2 is associated with aneurysm rupture. Thus the distribution of WSS in aneurysm region provides useful prediction for the risk of aneurysm rupture.

Turkish Muslims in a German city: Entrepreneurial and residential self-determination

2015 ◽  
Vol 12 (1) ◽  
pp. 1-12
Author(s):  
Sarah Hackett
Keyword(s):  
Residential Patterns ◽  
Academic Literature ◽  
Self Employment ◽  
German City ◽  
Post War ◽  
Oral History Interviews ◽  
The City ◽  
Insight Into ◽  
Term Objective

Drawing upon a collection of oral history interviews, this paper offers an insight into entrepreneurial and residential patterns and behaviour amongst Turkish Muslims in the German city of Bremen. The academic literature has traditionally argued that Turkish migrants in Germany have been pushed into self-employment, low-quality housing and segregated neighbourhoods as a result of discrimination, and poor employment and housing opportunities. Yet the interviews reveal the extent to which Bremen’s Turkish Muslims’ performances and experiences have overwhelmingly been the consequences of personal choices and ambitions. For many of the city’s Turkish Muslim entrepreneurs, self-employment had been a long-term objective, and they have succeeded in establishing and running their businesses in the manner they choose with regards to location and clientele, for example. Similarly, interviewees stressed the way in which they were able to shape their housing experiences by opting which districts of the city to live in and by purchasing property. On the whole, they perceive their entrepreneurial and residential practices as both consequences and mediums of success, integration and a loyalty to the city of Bremen. The findings are contextualised within the wider debate regarding the long-term legacy of Germany’s post-war guest-worker system and its position as a “country of immigration”.

The role of probiotics in correction of microbiocenosis and cytokine balance of the oral cavity of patient with chronic inflammatory disease of periodont

2020 ◽  
Vol 25 (4) ◽  
pp. 323-330
Author(s):  
E. S. Ovcharenko ◽  
V. V. Erichev ◽  
S. I. Risovannij ◽  
T. V. Aksenova ◽  
S. V. Melekhov ◽  
...  
Keyword(s):  
Oral Cavity ◽  
Periodontal Diseases ◽  
Treatment Protocol ◽  
Chronic Inflammatory Disease ◽  
Oral Microbiome ◽  
Comprehensive Treatment ◽  
Local Immunity ◽  
Treatment Techniques ◽  
Before And After

Relevance. A long-term inflammation in the oral cavity, unreasonable treatment of periodontal patients with antibiotics cause imbalance between certain types of fungal-bacterial associations accompanied by oral dysbiosis and change of local immune status. So, development and application of new comprehensive diagnosis and treatment techniques in periodontal patients, use of products for correction of microbiota and local immunity are a current and a long-term task. Purpose is to optimize the comprehensive treatment protocol of inflammatory periodontal diseases by introducing probiotics and evaluation of oral microbiome and cytokine profile.Materials and methods. 140 patients were examined. Of these 60 patients had chronic generalized plaque-induced gingivitis and 60 patients suffered from moderate chronic generalized periodontitis. Bacterial and fungal microbiome was assessed and the host immune response was evaluated in all patients before and after the treatment. Half of the patients were treated conventionally and the other half were treated according to a modified scheme: probiotic “Bifidumbacterin Forte” was added.Results. A large number of yeast-like fungi Candida and commensal bacteria were detected in periodontal pockets of patients with chronic generalized plaque-induced gingivitis and moderate chronic generalized periodontitis. That correlates with a significant increase of pro-inflammatory cytokines (TNF-α, IL—8), decrease of concentration of INF-γ and increase of antiinflammatory cytokine IL-4.Conclusion. Changes in clinical, microbiological and immunological values during a modified combination therapy with a probiotic and during a conventional treatment demonstrated that effectiveness of treatment of chronic gingivitis and chronic periodontitis increased by 40% and 37% respectively.

REPEATED LONG-TERM SPACE FLIGHTS: PROTEOMIC INVESTIGATIONS OF COSMONAUTS' BLOOD

2020 ◽  
Vol 54 (5) ◽  
pp. 15-22
Author(s):  
I.M. Larina ◽  
◽  
D.N. Kashirina ◽  
K.S. Kireev ◽  
A.I. Grigoriev ◽  
...  
Keyword(s):  
Bone Structure ◽  
Space Station ◽  
The Body ◽  
Coagulation Cascade ◽  
Chemical Components ◽  
Blood Proteins ◽  
Blood Indices ◽  
Before And After ◽  
Biochemical Indices

We performed the first ever comparative analysis of modifications in the proteome, ionogram and some other blood plasma biochemical indices of 18 male cosmonauts (44 ± 6 years of age) before and after maiden or repeated long-term missions to the Russian segment of the International space station (ISS RS). Levels of proteins, substrates and ions as well as chemical components were measured using the LC-MS-based proteomics and routine biochemical techniques. A total of 256 to 281 indices were investigated with the methods of descriptive statistic, regression analysis, and access to bioinformatics resources. It was shown that blood indices recovery from the maiden and repeated missions reflects changes in the body systems and goes at a various speed. The results of measurements made prior to launch and on day 7 after landing are dependent on the number of missions. The bioinformatics techniques showed that after maiden missions both the mediator proteins of alkaline phosphatase (AP) and blood proteins with reliably changing concentrations are associated with the bio-processes including stress, metabolism and DNA reparation, apoptosis, catabolism and proteolysis. During early re-adaptation from repeated missions the AP level was affected by bone remodeling, phosphorylation, angiogenesis and coagulation cascade suggesting a distinct and urgent trigger of the processes of bone structure and mineralization.

Moving Songs

2019 ◽  
pp. 590-606
Author(s):  
Sally Treloyn ◽  
Matthew Dembal Martin ◽  
Rona Goonginda Charles
Keyword(s):  
Cultural Heritage ◽  
Knowledge Transmission ◽  
Intercultural Relationships ◽  
Cultural Negotiation ◽  
Intercultural Collaboration ◽  
Present Collection ◽  
Intergenerational Knowledge ◽  
Early Phases ◽  
Insight Into

Repatriation has become almost ubiquitous in ethnomusicological research on Australian Indigenous song. This article provides insights into processes of a repatriation-centered song revitalization project in the Kimberley, northwest Australia. Authored by an ethnomusicologist and two members of the Ngarinyin cultural heritage community, the article provides firsthand accounts of the early phases of a long-term repatriation-centered project referred to locally as the Junba Project. The authors provide a sample of narratives and dialogues that deliver insight into experiences of the work of identifying recordings “in the archive” and cultural negotiation and use of recordings “on Country.” The entanglement of local epistemological frameworks with past and present collection, archival research, repatriation, and dissemination for intergenerational knowledge transmission between spirits, Country, and the living, is explored, showing how recordings move song knowledge from community to archive to community and from generation to generation, and move people in present-day communities. The chapter considers how these “moving songs” allow an interrogation of the fraught endeavor of intercultural collaboration in the pursuit of revitalizing Indigenous song traditions. It positions repatriation as a method that can support intergenerational knowledge transmission and as a method to consider past and present intercultural relationships within research projects and between cultural heritage communities and collecting institutions.

scholarly journals Feasibility and Enjoyment of Exercise Video Games in Older Adults

2020 ◽  
Vol 4 (Supplement_1) ◽  
pp. 559-559
Author(s):  
Sara Freed ◽  
Briana Sprague ◽  
Lesley Ross
Keyword(s):  
Older Adults ◽  
Video Games ◽  
Game Design ◽  
Long Term Effects ◽  
Short Term ◽  
Qualitative And Quantitative ◽  
Before And After ◽  
Xbox Kinect ◽  
Game Developers

Abstract Interventions using exercise video games, or exergames, have shown short-term cognitive and physical benefits to older adults, though long-term effects are less promising. Enjoyment of exergames may promote exergame use after the intervention period, though little work has examined older adults’ views of exergames before and after gameplay experience. We invited 20 older adults between 65 and 84 years of age (M=73.30, SD=5.95) to play two Xbox Kinect games, Just Dance and Kinect Sports Rivals, for twenty minutes. In our presentation, we will present qualitative and quantitative findings of this pilot study, including findings that older adults reported that they were not likely to play similar exergames in the future and that they did not find the exergames to be more fun compared to other ways of exercising. We will discuss implications for game design and research relevant to game developers, manufacturers, and researchers. Part of a symposium sponsored by Technology and Aging Interest Group.

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