Experimental Investigation of the Local Blood Flow Pattern in Stented Coronary Bifurcations

2011 ◽  
Author(s):  
Stefano Morlacchi ◽  
Jaime Schmieg ◽  
Dan Cooper ◽  
Francesco Burzotta ◽  
Francesco Migliavacca ◽  
...  
Keyword(s):  
Blood Flow ◽  
Invasive Procedure ◽  
Cost Effective ◽  
Clinical Results ◽  
Shear Stresses ◽  
Local Blood Flow ◽  
Time Saving ◽  
Acute Thrombosis ◽  
Hemodynamic Forces ◽  
Stent Restenosis

Stenting procedures give the opportunity to treat cardiovascular diseases with a time saving, cost effective and minimally invasive procedure when compared to coronary artery by-pass, while ensuring improved clinical results than balloon angioplasty. However, despite their success, stenting procedures are still associated with some clinical problems like sub-acute thrombosis (ST) and in-stent restenosis (ISR). Several clinical studies associate these issues to the local blood flow alterations caused by stent implantation. In particular, hemodynamic forces like wall shear stresses induce endothelial cells to experience an enhanced proliferative attitude.

Numerical Modelling of Stenting Procedures in Coronary Bifurcations: A Structural and Fluid Dynamic Combined Approach

2011 ◽  
Author(s):  
Stefano Morlacchi ◽  
Claudio Chiastra ◽  
Gabriele Dubini ◽  
Francesco Migliavacca
Keyword(s):  
Fluid Dynamic ◽  
Coronary Vessels ◽  
Invasive Procedure ◽  
Cost Effective ◽  
Clinical Results ◽  
Time Saving ◽  
Acute Thrombosis ◽  
Stent Restenosis ◽  
Biological Studies ◽  
New Treatment

Stenting procedures give the opportunity to treat cardiovascular diseases with a time saving, cost effective and minimally invasive procedure if compared to coronary artery by-pass, ensuring at the same time better clinical results than balloon angioplasty. Despite their success, stenting procedures are still associated to some clinical problems like sub-acute thrombosis (ST) and in-stent restenosis (ISR) whose main outcome is the re-narrowing of the coronary vessels and the necessity of a new treatment to restore blood flow and perfusion to downstream tissues. Their mechanisms and causes are still not fully understood but clinical and biological studies agree the idea that these are caused by a combination of both structural and hemodynamic factors [1,2].

Numerical Analysis of Blood Flow in the Vertebral Artery

1982 ◽  
Vol 104 (2) ◽  
pp. 143-147 ◽  
Author(s):  
Takayoshi Fukushima ◽  
Takehiko Azuma ◽  
Teruo Matsuzawa
Keyword(s):  
Blood Flow ◽  
Numerical Analysis ◽  
Vertebral Artery ◽  
Arterial Blood Flow ◽  
Vascular Lesions ◽  
Shear Stresses ◽  
Hemodynamic Forces ◽  
Atherosclerotic Lesions ◽  
Arterial Blood ◽  
Structure Of Flow

Abnormal hemodynamic forces associated with distortions of blood vessel lumen have been thought to play an important role in the pathogenesis of focal vascular lesions. In the vertebral artery, segments located between osseous rings are ectatic compared with those surrounded by the rings. Based on the assumption that arterial blood flow was quasi-steady, this work was undertaken to investigate the structure of flow through arterial models with one or two sinusoidal stenoses. Numerical analysis was performed by an integral-momentum method. The validity of the method was examined by comparison of experimental data so far reported with theoretical results. Velocity and wall shear stress distributions were explored in a model with two stenoses simulating a part of the vertebral artery. The ectatic segments of the vertebral artery have been known as predilection sites for atherosclerotic lesions. The present study suggested that the ectatic wall was under unstable shear stresses, the direction of which was dependent upon the magnitude of the Reynolds number.

scholarly journals Flow-mediated endothelial mechanotransduction

1995 ◽  
Vol 75 (3) ◽  
pp. 519-560 ◽  
Author(s):  
P. F. Davies
Keyword(s):  
Endothelial Cells ◽  
Blood Flow ◽  
Blood Vessel ◽  
Vascular Tone ◽  
Shear Stresses ◽  
Mechanical Forces ◽  
Hemodynamic Forces ◽  
Atherosclerotic Lesions ◽  
Arterial Structure ◽  
Gene Regulatory

Mechanical forces associated with blood flow play important roles in the acute control of vascular tone, the regulation of arterial structure and remodeling, and the localization of atherosclerotic lesions. Major regulation of the blood vessel responses occurs by the action of hemodynamic shear stresses on the endothelium. The transmission of hemodynamic forces throughout the endothelium and the mechanotransduction mechanisms that lead to biophysical, biochemical, and gene regulatory responses of endothelial cells to hemodynamic shear stresses are reviewed.

scholarly journals Cost-Effectiveness of Percutaneous Automated Lumbar Nucleotomy

1999 ◽  
Vol 5 (1) ◽  
pp. 35-42 ◽  
Author(s):  
R. Dullerud ◽  
H. Lie ◽  
B. Magnæs
Keyword(s):  
Cost Effectiveness ◽  
Surgical Treatment ◽  
Lumbar Disc ◽  
Invasive Procedure ◽  
Cost Effective ◽  
Clinical Results ◽  
Complication Rates ◽  
Success Rates ◽  
One Year ◽  
The Cost

This study was conducted in order to evaluate the cost-effectiveness of percutaneous automated lumbar nucleotomy in comparison with traditional macro-procedure discectomy in the treatment of herniated discs. Sixty-eight patients undergoing surgical procedures and 90 treated with nucleotomy were consecutively included. Both cohorts were assessed pre-operatively and at regular intervals for one year or more after treatment by independent observers, using a clinical overall scoring system (COS) with 0 being the best attainable result and 1000 the poorest conceivable status of the patients. There were better clinical results after surgery with 78% successes after one year compared to 62% after nucleotomy. By including subsequent operations and re-operations after failure to respond to the primary treatment, the success rates rose to 79% and 77%, respectively. The cost of surgical treatment was calculated to USD 6.119 per patient and the cost of a nucleotomy procedure was USD 1.252. Owing to an almost five times higher price of surgery than nucleotomy, the latter turned out to be 2.7 to 3.9 times more cost-effective, depending on whether secondary treatment was included or not. Due to the minimal difference in final outcome between the groups, however, the marginal cost per extra success in patients primarily treated with surgery was as high as USD 205.850. The study concludes that nucleotomy, as a mini-invasive procedure with low complication rates and the potential of a quick recovery, is more cost-effective than traditional surgical treatment for lumbar disc herniation.

scholarly journals Numerical Investigation of the Fetal Left Heart Hemodynamics During Gestational Stages

2021 ◽  
Vol 12 ◽  
Author(s):  
Huseyin Enes Salman ◽  
Reema Yousef Kamal ◽  
Huseyin Cagatay Yalcin
Keyword(s):  
Blood Flow ◽  
Mitral Valve ◽  
Heart Defects ◽  
Shear Stresses ◽  
Ultrasound Images ◽  
Left Heart ◽  
Hemodynamic Forces ◽  
Hemodynamic Assessment ◽  
Peak Shear Stress ◽  
Gestational Week

Flow-driven hemodynamic forces on the cardiac tissues have critical importance, and have a significant role in the proper development of the heart. These mechanobiological mechanisms govern the cellular responses for the growth and remodeling of the heart, where the altered hemodynamic environment is believed to be a major factor that is leading to congenital heart defects (CHDs). In order to investigate the mechanobiological development of the normal and diseased hearts, identification of the blood flow patterns and wall shear stresses (WSS) on these tissues are required for an accurate hemodynamic assessment. In this study, we focus on the left heart hemodynamics of the human fetuses throughout the gestational stages. Computational fetal left heart models are created for the healthy fetuses using the ultrasound images at various gestational weeks. Realistic inflow boundary conditions are implemented in the models using the Doppler ultrasound measurements for resolving the specific blood flow waveforms in the mitral valve. Obtained results indicate that WSS and vorticity levels in the fetal left heart decrease with the development of the fetus. The maximum WSS around the mitral valve is determined around 36 Pa at the gestational week of 16. This maximum WSS decreases to 11 Pa at the gestational week of 27, indicating nearly three-times reduction in the peak shear stress. These findings reveal the highly dynamic nature of the left heart hemodynamics throughout the development of the human fetus and shed light into the relevance of hemodynamic environment and development of CHDs.

E-Voting Kepala Desa dan Modal Sosial

2019 ◽  
Vol 2 (6) ◽  
pp. 759
Author(s):  
Khaulah Afifah ◽  
Lala M Kolopaking ◽  
Zessy Ardinal Barlan
Keyword(s):  
Social Capital ◽  
Random Sampling ◽  
Qualitative Data ◽  
Sampling Technique ◽  
Cost Effective ◽  
Simple Random Sampling ◽  
Community Based ◽  
Time Saving ◽  
The Social ◽  
Voting System

Head of a village election with e-voting system is a new thing for community The success level of e-voting system can be reached by fulfil several principles in order to the implementation going effective and the result of the election can be accepted by all. The objectives of this research is to analyze the relation between the success level of e-voting system with social capital of the community. This research is carried out with the quantitative approach and supported by qualitative data. This research takes 60 respondents using simple random sampling technique. The results showed that the success level of e-voting has a correlation with the level of social capital of the community. Based on the field study, the social capital of the community is classified as high. The high social capital makes the implementation of e-voting successful and the success level is also high, because in the election ten years ago occurred a conflict. The community considers e-voting easier and more practical, cost effective and time-saving, and the results of e-voting are also reliable. A practical and fast of e-voting system can be a solution especially for “rural-urban” community who are busy or work outside the village.Keywords: E-voting, the success level of the system, social capital Pemilihan kepala desa dengan sistem e-voting merupakan hal yang baru bagi masyarakat. Keberhasilan penerapan sistem e-voting dilihat dari terpenuhinya beberapa prinsip agar penerapannya berlangsung efektif dan hasilnya dapat diterima oleh seluruh masyarakat. Penelitian ini bertujuan untuk menganalisis hubungan tingkat keberhasilan sistem e-voting dalam pemilihan kepala desa dengan tingkat modal sosial masyarakat. Bentuk penelitian ini adalah penelitian kuantitatif yang didukung oleh analisis data kualitatif. Penelitian ini mengambil enam puluh responden dengan teknik simple random sampling. Hasil penelitian menunjukkan bahwa tingkat keberhasilan e-voting memiliki hubungan dengan tingkat modal sosial masyarakat. Berdasarkan kajian di lapang, modal sosial masyarakat tergolong tinggi. Tingginya modal sosial tersebut membuat pelaksanaan e-voting berhasil dan tingkat keberhasilannya juga tergolong tinggi karena pada pemilihan sepuluh tahun silam sempat terjadi konflik. Masyarakat menganggap sistem evoting lebih mudah dan praktis, hemat dalam segi biaya dan waktu, serta hasil dari pemilihan juga dapat dipertanggungjawabkan. Sistem e-voting yang praktis dan cepat dapat menjadi solusi khususnya bagi masyarakat daerah “desa-kota” yang memiliki kesibukan atau pekerjaan di luar desa.Kata Kunci: E-voting, keberhasilan sistem, modal sosial. 

Kinetic Behaviour of Amylase According to pH: A New Perspective for Starch Hydrolysis Process

2020 ◽  
Vol 16 (2) ◽  
pp. 135-144
Author(s):  
Ravneet K. Grewal ◽  
Baldeep Kaur ◽  
Gagandeep Kaur
Keyword(s):  
Metal Ions ◽  
Competitive Inhibition ◽  
Deae Cellulose ◽  
Kinetic Studies ◽  
Cost Effective ◽  
Starch Hydrolysis ◽  
Divalent Metal Ions ◽  
Activity Data ◽  
Time Saving ◽  
Alkaline Conditions

Background: Amylases are the most widely used biocatalysts in starch saccharification and detergent industries. However, commercially available amylases have few limitations viz. limited activity at low or high pH and Ca2+ dependency. Objective: The quest for exploiting amylase for diverse applications to improve the industrial processes in terms of efficiency and feasibility led us to investigate the kinetics of amylase in the presence of metal ions as a function of pH. Methods: The crude extract from soil fungal isolate cultures is subjected to salt precipitation, dialysis and DEAE cellulose chromatography followed by amylase extraction and is incubated with divalent metal ions (i.e., Ca2+, Fe2+, Cu2+, and Hg2+); Michaelis-Menton constant (Km), and maximum reaction velocity (Vmax) are calculated by plotting the activity data obtained in the absence and presence of ions, as a function of substrate concentration in Lineweaver-Burk Plot. Results: Kinetic studies reveal that amylase is inhibited un-competitively at 5mM Cu2+ at pH 4.5 and 7.5, but non-competitively at pH 9.5. Non-competitive inhibition of amylase catalyzed starch hydrolysis is observed with 5mM Hg2+ at pH 9.5, which changes to mixed inhibition at pH 4.5 and 7.5. At pH 4.5, Ca2+ induces K- and V-type activation of amylase catalyzed starch hydrolysis; however, the enzyme has V-type activation at 7mM Ca2+ under alkaline conditions. Also, K- and V-type of activation of amylase is observed in the presence of 7mM Fe2+ at pH 4.5 and 9.5. Conclusion: These findings suggest that divalent ions modulation of amylase is pH dependent. Furthermore, a time-saving and cost-effective solution is proposed to overcome the challenges of the existing methodology of starch hydrolysis in starch and detergent industries.

Monitoring cyclical coronary blood flow alterations after coronary angioplasty for stent restenosis with a Doppler guide wire

1993 ◽  
Vol 125 (4) ◽  
pp. 1159-1161 ◽  
Author(s):  
Morton J Kern ◽  
Thomas Donohue ◽  
Richard Bach ◽  
Frank Aguirre ◽  
Calvin Bell
Keyword(s):  
Blood Flow ◽  
Coronary Blood Flow ◽  
Coronary Angioplasty ◽  
Guide Wire ◽  
Stent Restenosis

A revised FMEA application to the quality control management

2014 ◽  
Vol 31 (7) ◽  
pp. 788-810 ◽  
Author(s):  
Claudia Paciarotti ◽  
Giovanni Mazzuto ◽  
Davide D’Ettorre
Keyword(s):  
Quality Control ◽  
Failure Modes ◽  
Cost Effective ◽  
Weight Functions ◽  
Time Saving ◽  
Content Type ◽  
Complete Procedure ◽  
Medium Enterprise ◽  
Control Management ◽  
Critical Situations

Purpose – The purpose of this paper is to propose a cost-effective, time-saving and easy-to-use failure modes and effects analysis (FMEA) system applied on the quality control of supplied products. The traditional FMEA has been modified and adapted to fit the quality control features and requirements. The paper introduces a new and revised FMEA approach, where the “failure concept” has been modified with “defect concept.” Design/methodology/approach – The typical FMEA parameters have been modified, and a non-linear scale has been introduced to better evaluate the FMEA parameters. In addition, two weight functions have been introduced in the risk priority number (RPN) calculus in order to consider different critical situations previously ignored and the RPN is assigned to several similar products in order to reduce the problem of complexity. Findings – A complete procedure is provided in order to assist managers in deciding on the critical suppliers, the creation of homogeneous families overcome the complexity of single product code approach, in RPN definition the relative importance of factors is evaluated. Originality/value – This different approach facilitates the quality control managers acting as a structured and “friendly” decision support system: the quality control manager can easily evaluate the critical situations and simulate different scenarios of corrective actions in order to choose the best one. This FMEA technique is a dynamic tool and the performed process is an iterative one. The method has been applied in a small medium enterprise producing hydro massage bathtub, shower, spas and that commercializes bathroom furniture. The firm application has been carried out involving a cross-functional and multidisciplinary team.

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