The effects of a velocity slip and an external magnetic field on the flow of biomagnetic fluid(blood)through a stenosed bifurcated artery are investigated by using ANSYS FLUENT.Blood is regarded as a non-Newtonian pow...The effects of a velocity slip and an external magnetic field on the flow of biomagnetic fluid(blood)through a stenosed bifurcated artery are investigated by using ANSYS FLUENT.Blood is regarded as a non-Newtonian power-law fluid,and the magnetization and electrical conductivity are considered in the mathematical model.The no-slip condition is replaced by the first-order slip condition.The slip boundary condition and magnetic force are compiled in the solver by the user-defined function(UDF).Numerical solutions are obtained by the finite volume method based on a nonuniform grid structure.The accuracy and efficiency of the solver are verified through a comparison with the literature.The results are presented graphically for different parameter values,and the effects of the magnetic number,the magnetic source position,the vascular obstruction ratio,the slip parameter,and the power-law index on the flow and temperature fields are illustrated.展开更多
This Communication deals with the blood flow of Prandtl fluid through a tapered stenosed arteries having permeable walls.The governing equations of two-dimensional Prandtl fluid model are modelled in cylindrical coord...This Communication deals with the blood flow of Prandtl fluid through a tapered stenosed arteries having permeable walls.The governing equations of two-dimensional Prandtl fluid model are modelled in cylindrical coordinates.The highly nonlinear equations are simplified with the help of non-dimensional variables under the assumption of mild stenosis.The solution of reduced nonlinear equation subject to boundary condition of porous walls having the effects of Darcy's number and slip parameter are computed analytically with the help of perturbation method.Effects of emerging parameters such as impedance A,slip parameter a,stenosis height 6,magnetic parameter and stress component Srz on velocity are illustrated graphically.The streamlines have also been presented to discuss the trapping bolus discipline.展开更多
Acute stress concentration plays an important role in plaque rupture and may cause stroke or myocardial infarction.Quantitative evaluation of the relation between in vivo plaque stress and variations in blood pressure...Acute stress concentration plays an important role in plaque rupture and may cause stroke or myocardial infarction.Quantitative evaluation of the relation between in vivo plaque stress and variations in blood pressure and flow rates is valuable to optimize daily monitoring of the cardiovascular system for high-risk patients as well as to set a safe physical exercise intensity for better quality of life.In this study,we constructed an in vivo stress model for a human carotid bifurcation with atherosclerotic plaque,and analyzed the effects of blood pressure,flow rates,plaque stiffness,and stenosis on the elastic stress and fluid viscous stress around the plaque.According to the maximum values of the mechanical stress,we define a risk index to predict the risk level of plaque rupture under different exercise intensities.For a carotid bifurcation where the blood flow divides,the results suggest that the stenosis ratio determines the ratio of the contributions of elastic shear stress and viscous shear stress to plaque rupture.A n increase of the plaque stiffness enhances the maximum elastic shear stress in the plaque,indicating that a high-stiffness plaque is more prone to rupture for given stenosis ratio.High stress co-localization at the shoulder of plaques agrees with the region of plaque injury in clinical observations.It is demonstrated that,due to the stress-shield effect,the rupture risk of a high-stiffness plaque tends to decrease under high-stenosis conditions,suggesting the existence of a specific stenosis corresponding to the maximum risk.This study may help to complement risk stratification of vulnerable plaques in clinical practice and provides a stenosis mechanical property-specific guide for blood pressure control in cardiovascular health management.展开更多
Catheter is commonly used by the surgeons for various reasons in the treatment of a patient suffering with cardiovascular diseases. Catheterization increases the mean flow resistance in the arterial blood flow and man...Catheter is commonly used by the surgeons for various reasons in the treatment of a patient suffering with cardiovascular diseases. Catheterization increases the mean flow resistance in the arterial blood flow and many other complications are associated with the presence of catheter in the artery. Effects of catheter in stenosed artery can be estimated non-invasively by means of hemo-dynamic indicator-WSS, WSSG, volume flow rate and impedance. The effect of slip at the arterial wall, inclination of the artery and magnetic field on the hemodynamic indicators and flow profiles are computed, presented and discussed through graphs.展开更多
In this paper, we have discussed the biomathematical analysis of Sutterby fluid model for blood flow in stenosed tapered arteries. The equations for the Sutterby fluid model are modeled in cylindrical geometry. The eq...In this paper, we have discussed the biomathematical analysis of Sutterby fluid model for blood flow in stenosed tapered arteries. The equations for the Sutterby fluid model are modeled in cylindrical geometry. The equations have been developed for the ease of mild stenosis. Perturbation solutions are attained in terms of small Sutterby fluid parameter β for the velocity, impedance resistance and wall shear stress. Three types of arteries i.e. converging, diverging and non-tapered have been considered for the analysis and discussion. Graphical results have been presented for different parameters of interest. Streamlines have been plotted at the end of the paper.展开更多
BACKGROUND Platelet-rich plasma(PRP)injection is used as an alternative non-operative management for de Quervain’s tenosynovitis(DQT)to regenerate tendon healing.AIM To assess and conclude the research-based study sy...BACKGROUND Platelet-rich plasma(PRP)injection is used as an alternative non-operative management for de Quervain’s tenosynovitis(DQT)to regenerate tendon healing.AIM To assess and conclude the research-based study systematically to analyse the efficacy of PRP on DQT.METHODS This systematic review used the Cochrane Handbook for Systematic Reviews and the guideline of preferred reporting items for systematic review and metaanalysis.A systematic literature search was applied to 11 databases.The authors assessed the study quality and risk of bias of each included study.Results of the meta-analysis were presented using mean difference(MD)/standardized mean difference(SMD)and 95%condence interval(CI).RESULTS The authors evaluated 275 studies found in the literature search;12 studies met the criteria for this review,and then the study quality and risk of bias were assessed.Pooled analysis of data from two studies involving 194 subjects with DQT showed that,compared with conservative treatment,PRP injection was associated with a greater reduction in visual analog scale pain in one month and six months after treatment(MD:-0.67,P value<0.00001;MD:-1.16,P value<0.00001)and the increase of Mayo’s wrist score in one month and six months after treatment(SMD:3.72,P value<0.00001;SMD:4.44,P value<0.00001).CONCLUSION PRP can be used as an alternative non-operative treatment for DQT due to the tissue regenerative effect of PRP.展开更多
Mechanical stimuli play critical roles in cardiovascular diseases,in which in vivo stresses in blood vessels present a great challenge to predict.Based on the structural-thermal coupled finite element method,we propos...Mechanical stimuli play critical roles in cardiovascular diseases,in which in vivo stresses in blood vessels present a great challenge to predict.Based on the structural-thermal coupled finite element method,we propose a thermal expansion method to estimate stresses in multi-layer blood vessels under healthy and pathological conditions.The proposed method provides a relatively simple and convenient means to predict reliable in vivo mechanical stresses with accurate residual stress.The method is first verified with the opening-up process and the pressure-radius responses for single and multi-layer vessel models.It is then applied to study the stress variation in a human carotid artery at different hypertension stages and in a plaque of vascular stenosis.Our results show that specific or optimal residual stresses exist for different blood pressures,which helps form a homogeneous stress distribution across vessel walls.High elastic shear stress is identified on the shoulder of the plaque,which contributes to the tearing effect in plaque rupture.The present study indicates that the proposed numerical method is a capable and efficient in vivo stress evaluation of patient-specific blood vessels for clinical purposes.展开更多
This work is concerned with the analysis of blood flow through inclined catheterized arteries having a balloon(angioplasty) with time-variant overlapping stenosis. The nature of blood in small arteries is analyzed mat...This work is concerned with the analysis of blood flow through inclined catheterized arteries having a balloon(angioplasty) with time-variant overlapping stenosis. The nature of blood in small arteries is analyzed mathematically by considering it as a Carreau nanofluid. The highly nonlinear momentum equations of nanofluid model are simplified by considering the mild stenosis case. The formulated problem is solved by a homotopy perturbation expansion in terms of a variant of the Weissenberg number to obtain explicit forms for the axial velocity, the stream function, the pressure gradient, the resistance impedance and the wall shear stress distribution. These solutions depend on the Brownian motion number, thermophoresis number, local temperature Grashof number G_r and local nanoparticle Grash of number B_r. The results were also studied for various values of the physical parameters, such as the Weissenberg number W_i, the power law index n, the taper angle φ, the maximum height of stenosis δ~*, the angle of inclination α, the maximum height of balloon σ~*, the axial displacement of the balloon z_d~*,the flow rate F and the Froud number Fr. The obtained results show that the transmission of axial velocity curves through a Newtonian fluid(Wi=0, n=1, Gr=0, Br=0, Nt=0, Nb≠0) is substantially lower than that through a Carreau nanofluid near the wall of balloon while the inverse occurs in the region between the balloon and stenosis. The streamlines have a clearly distinguished shifting toward the stenotic region and this shifting appears near the wall of the balloon, while it has almost disappeared near the stenotic wall and the trapping bolus in the case of horizontal arteries and Newtonian fluid(Wi=0, n=1, Gr=0, Br=0, Nt=0, Nb≠0) does not appear but for the case of Carreau nanofluid bolus appears.展开更多
The hemodynamic mechanism of rolling manipulation (RM) of traditional Chinese medical massage (TCMM) is investigated. An axisymmetrical nonlinear model and an arbitrary Lagrangian-Eulerian finite element method (ALE-F...The hemodynamic mechanism of rolling manipulation (RM) of traditional Chinese medical massage (TCMM) is investigated. An axisymmetrical nonlinear model and an arbitrary Lagrangian-Eulerian finite element method (ALE-FEM) with rezoning algorithm were introduced to study the viscous flow through an axisymmetrical rigid tube with axially moving stenosis to simulate the rolling manipulation. Flow rate and wall shear stress were obtained by solving complete Navier-Stokes equations numerically. The numerical results show that the stenosis moving frequency, namely the frequency of rolling manipulation, has great effect on the disturbance of flow and the wall shear stress. The stenosis coefficient, which characterizes the severity of the stenosis, another adjustable parameter in rolling manipulation, also shows the significant effect on flow rate and wall shear stress. These numerical results may provide some data that can be taken into consideration when massage is used in clinic.展开更多
This paper explores the mathematical model for couple stress fluid flow through an annular region. The above model is used for studying the blood flow be-tween the clogged （stenotic） artery and the catheter. The asy...This paper explores the mathematical model for couple stress fluid flow through an annular region. The above model is used for studying the blood flow be-tween the clogged （stenotic） artery and the catheter. The asymmetric nature of the stenosis is considered. The closed form expressions for the physiological parameters such as impedance and shear stress at the wall are obtained. The effects of various geomet-ric parameters and the parameters arising out of the fluid considered are discussed by considering the slip velocity and tapering angle. The study of the above model is very significant as it has direct applications in the treatment of cardiovascular diseases.展开更多
The Chinese traditional medical massage has been used as a natural therapy to eliminate some diseases. Here, the effect of the rolling massage frequency to the blood flow in the blood vessels under the rolling massage...The Chinese traditional medical massage has been used as a natural therapy to eliminate some diseases. Here, the effect of the rolling massage frequency to the blood flow in the blood vessels under the rolling massage manipulation is studied by the lattice Boltzmann simulation. The simulation results show that when the frequency is smaller than or comparable to the pulsatile frequency of the blood flow, the effect on the blood flux by the rolling massage is small. 011 the contrast, if the frequency is twice or more times of the pulsatile frequency of the blood flow, the blood flux is greatly enhanced and increases linearly with respect to the frequency. Similar behavior has also been observed on the shear stress on the blood vessel walls. The result is helpful for understanding that the rolling massage has the function of promoting the blood circulation and removing the blood stasis.展开更多
The blood flow through a catheterized artery having a mild stenosis at the wall together with a blood clot at the centre is studied in the current investigation.Stenosis can occur in vessels carrying blood to brain(i....The blood flow through a catheterized artery having a mild stenosis at the wall together with a blood clot at the centre is studied in the current investigation.Stenosis can occur in vessels carrying blood to brain(i.e.,Carotid arteries),Renal arteries that supply blood to kidneys etc.The flow is refined in such vessels by application of catheter.We have used a Newtonian viscous fluid model and also distinct shapes of stenosis,(i.e.,symmetric and non-symmetric shapes)are considered for this study.The entropy generation togetherwith viscous dissipation is also taken into account for a complete description of heat transfer mechanism.Exact solutions are calculated for the problem subject to given“no slip conditions”.The results are discussed graphically.The velocity quickly increases for a non-symmetric stenosis as compared to a symmetric stenosis.When the height of mild stenosis increases and the channel becomes narrow then the velocity increases in the centre but it decreases with the stenosed wall.However,as the height of blood clotσincreases then the velocity of blood flow reduces with the wall having clot but it remains almost same with the stenosed wall.Streamlines are plotted to visualize the flow pattern.The trapping is symmetric for a symmetric stenosis shape but it changes to non-symmetric trapping when we have a non-symmetric shape of stenosis.展开更多
We present the case of a 29-year-old patient with a history of abdominal pain and vomiting.Based on wireless video capsule findings he was previously diagnosed with ileal Crohn's disease at a different institution...We present the case of a 29-year-old patient with a history of abdominal pain and vomiting.Based on wireless video capsule findings he was previously diagnosed with ileal Crohn's disease at a different institution,although the clinical and radiological picture was not typical and the response to corticosteroids was poor.We performed a single-balloon enteroscopy showing a short,ulcerous stenosis 50 cm proximal from Bauhin's valve.The endoscopic and clinical histopathological findings were compatible with cryptogenic multifocal ulcerous stenosing enteritis(CMUSE).High dose corticosteroids were again started,without effect.The monoclonal tumor necrosis factor-α(TNF-α) antibody infliximab was added to the medical therapy.After induction therapy,both clinical and endoscopic amelioration was obtained.Larger case studies are needed to confirm the efficacy of TNF-α inhibition in steroid refractory CMUSE.展开更多
Biodegradable stents(BDSs)are an attractive option to avoid ongoing dilation or surgery in patients with benign stenoses of the small and large intestines.The experience with the currently the only BDS for endoscopic ...Biodegradable stents(BDSs)are an attractive option to avoid ongoing dilation or surgery in patients with benign stenoses of the small and large intestines.The experience with the currently the only BDS for endoscopic placement,made of Poly-dioxanone,have shown promising results.However some aspects should be improved as are the fact that BDSs lose their radial force over time due to the degradable material,and that can cause stent-induced mucosal or parenchymal injury.This complication rate and modest clinical efficacy has to be carefully considered in individual patients prior to placement of BDSs.Otherwise,the price of these stents therefore it is nowadays an important limitation.展开更多
Hilar tumors have proven to be a challenge to treat and manage because of their poor sensitivity to conventional therapies and our inability to prevent or to detect early tumor formation. Endoscopic stent drainage has...Hilar tumors have proven to be a challenge to treat and manage because of their poor sensitivity to conventional therapies and our inability to prevent or to detect early tumor formation. Endoscopic stent drainage has been proposed as an alternative to biliary-enteric bypass surgery and percutaneous drainage to palliate malignant biliary obstruction. Prosthetic palliation of patients with malignant hilar stenoses poses particular difficulties, especially in advanced lesions （type Ⅱ lesions or higher）. The risk of cholangitis after contrast injection into the biliary tree in cases where incomplete drainage is achieved is well known. The success rate of plastic stent insertion is around 80% in patients with proximal tumors. Relief of symptoms can be achieved in nearly all patients successfully stented.展开更多
To investigate the characteristic radiologic findings of cryptogenic multifocal ulcerous stenosing enteritis (CMUSE) which can be differentiated from other similar bowel disease and to assess their clinical behavior. ...To investigate the characteristic radiologic findings of cryptogenic multifocal ulcerous stenosing enteritis (CMUSE) which can be differentiated from other similar bowel disease and to assess their clinical behavior. METHODSTwenty pathologically and clinically confirmed CMUSE patients (males:females = 8:12; mean age: 40.4 years) between March 2002 and August 2015 from seven academic centers in South Korea were retrospectively reviewed. We evaluated small bowel series (SBS; n = 25), computed tomography (CT) enterography (n = 21), magnetic resonance (MR) enterography (n = 2), and abdominopelvic CT (n = 18) images, focusing on enteric and perienteric manifestations. Any change in radiologic features during follow-up period was recorded. We evaluated clinical data including presenting symptoms, laboratory finding and presence of relapse from electronic medical records. Histopathologic findings were also evaluated. RESULTSThe main symptoms were abdominal pain (n = 12) and anemia (n = 10). All patients showed small bowel strictures (n = 52, mean: 2.6 per patient) on initial CT/MR, located in the ileum (n = 47) or jejunum (n = 5). Strictures showed short-length (mean: 10.44 mm) and circumferential bowel wall thickening (mean: 5.56 mm) with layered enhancement (n = 48) that were also noted on initial SBS (n = 36) with shallow ulcers (n = 10). Some ulcerative lesions or wall thickening progressed into strictures on follow-up SBS/CT, and some strictures revealed recurrent ulceration on follow-up SBS. There were no penetrating disease features like fistula or abscess and no gastrointestinal tract involvement except the small bowel. Nine patients experienced disease recurrence (median relapse-free period: 32 mo) even post-operatively. Histopathologic features of surgically resected specimens were characterized as multiple superficial ulcerations confined to mucosa or submucosa and multiple strictures. CONCLUSIONUnder characteristic radiologic findings with multiple short-segmental strictures and/or shallow ulcers of the small intestine, CMUSE should be considered when assessing patients with recurrent abdominal pain and anemia.展开更多
Acquired atresia of the external auditory canal(EAC)is a rare cause of conductive hearing loss.It has been traditionally classified into 4 categories:traumatic,post-operative,neoplastic and inflammatory.Post-inflammat...Acquired atresia of the external auditory canal(EAC)is a rare cause of conductive hearing loss.It has been traditionally classified into 4 categories:traumatic,post-operative,neoplastic and inflammatory.Post-inflammatory acquired auditory canal atresia is thought to be the result of chronic and repetitive infectious bouts affecting the auditory canal.Nevertheless,the underlying pathophysiology of this disorder is yet to be fully elucidated.Current data fail to clearly state the impact that certain underlying systemic disorders may have on the EAC.The possible association to metabolic disturbances such as iron deficiency is also emphasized.In the light of these findings,this analysis can be used to improve the classification of this entity thereby standardizing the assessment of therapeutic approaches.展开更多
Flow fractional reserve(FFR) allows to evaluate the functional significance of coronary artery lesions, through the ratio of the mean coronary artery pressure after the stenosis to the mean aortic pressure duringmaxim...Flow fractional reserve(FFR) allows to evaluate the functional significance of coronary artery lesions, through the ratio of the mean coronary artery pressure after the stenosis to the mean aortic pressure duringmaximum hyperemia. The actual widely accepted cutoff value is 0.80. Below this value a coronary lesion is considered significant and therefore it requires invasive revascularization. Several studies [in particular Fractional Flow Reserve vs Angiography for Multivessel Evaluation 1(FAME-1) and FAME-2] have shown the relationship between FFR measurement and hard end-points(death, myocardial infarction, and urgent revascularization). Consequently, FFR evaluation represents the cornerstone in the decision-making in intermediate coronary lesions. Recent studies paved the way for further applications of FFR evaluation in complex and tricky clinical settings. In this paper, we perform an overview of the data regarding contemporary application of FFR. In particular, we review the use of FFR in: left main intermediate stenoses, serial stenoses, evaluation after stenting, guidance in coronary artery bypass surgery, and acute coronary syndrome. All the data presented in our overview confirm the essential role of FFR assessment in the daily clinical practice. The shift from "operator-dependent" to "FFR-dependent" evaluation in intermediate coronary artery stenosis is of paramount importance in order to improve the prognosis of our patients, through the discrimination of the functional role of every single coronary stenosis.展开更多
AIM： To present a case series of MRCP-guided endoscopic biliary stent placement, performed entirely without contrast injection. METHODS： Contrast-free endoscopic biliary drainage was attempted in 20 patients with ma...AIM： To present a case series of MRCP-guided endoscopic biliary stent placement, performed entirely without contrast injection. METHODS： Contrast-free endoscopic biliary drainage was attempted in 20 patients with malignant obstruction, unsuitable for resection on the basis of tumor extent or medical illness. MRCP images were used to confirm the diagnosis of tumor, to exclude other biliary diseases and to demonstrate the stenoses as well as dilation of proximal liver segments. The procedure was carried out under conscious sedation. Patients were placed in the left lateral decubitus position. The endoscope was inserted, the papilla identified and cannulated by a papiUotome. A guide wire was inserted and guided deeply into the biliary tree, above the stenosis, by fluoroscopy. A papillotomy approximately 1 cm. long was performed and the papillotome was exchanged with a guiding-catheter. A 10 Fr＇ Amsterdam-type plastic stent, 7 to 15 cm long, was finally inserted over the guide wire/ guiding catheter by a pusher tube system. RESULTS： Successful stent insertion was achieved in all patients. There were no major complications. Successful drainage, with substantial reduction in bilirubin levels, was achieved in all patients. CONCLUSION： This new method of contrast-free endoscopic stenting in malignant biliary obstruction is a safe and effective method of palliation. However＇ a larger, randomized study comparing this new approach with the standard procedure is needed to confirm the findings of the present study.展开更多
基金Project supported by the Fundamental Research Funds for the Central Universities of China(No.FRF-BR-18-008B)。
文摘The effects of a velocity slip and an external magnetic field on the flow of biomagnetic fluid(blood)through a stenosed bifurcated artery are investigated by using ANSYS FLUENT.Blood is regarded as a non-Newtonian power-law fluid,and the magnetization and electrical conductivity are considered in the mathematical model.The no-slip condition is replaced by the first-order slip condition.The slip boundary condition and magnetic force are compiled in the solver by the user-defined function(UDF).Numerical solutions are obtained by the finite volume method based on a nonuniform grid structure.The accuracy and efficiency of the solver are verified through a comparison with the literature.The results are presented graphically for different parameter values,and the effects of the magnetic number,the magnetic source position,the vascular obstruction ratio,the slip parameter,and the power-law index on the flow and temperature fields are illustrated.
文摘This Communication deals with the blood flow of Prandtl fluid through a tapered stenosed arteries having permeable walls.The governing equations of two-dimensional Prandtl fluid model are modelled in cylindrical coordinates.The highly nonlinear equations are simplified with the help of non-dimensional variables under the assumption of mild stenosis.The solution of reduced nonlinear equation subject to boundary condition of porous walls having the effects of Darcy's number and slip parameter are computed analytically with the help of perturbation method.Effects of emerging parameters such as impedance A,slip parameter a,stenosis height 6,magnetic parameter and stress component Srz on velocity are illustrated graphically.The streamlines have also been presented to discuss the trapping bolus discipline.
基金This work was supported by the National Key R&D Program of China(Grant 2017YFE0117100)the National Natural Science Foundation of China(Grants 11872040 and 11232010)+1 种基金the Outstanding Clinical Discipline Project of Shanghai Pudong(Grant PWYgy-2018-08)the Science and Technology Commission of Shanghai Municipality(Grant 18ZR1433900).
文摘Acute stress concentration plays an important role in plaque rupture and may cause stroke or myocardial infarction.Quantitative evaluation of the relation between in vivo plaque stress and variations in blood pressure and flow rates is valuable to optimize daily monitoring of the cardiovascular system for high-risk patients as well as to set a safe physical exercise intensity for better quality of life.In this study,we constructed an in vivo stress model for a human carotid bifurcation with atherosclerotic plaque,and analyzed the effects of blood pressure,flow rates,plaque stiffness,and stenosis on the elastic stress and fluid viscous stress around the plaque.According to the maximum values of the mechanical stress,we define a risk index to predict the risk level of plaque rupture under different exercise intensities.For a carotid bifurcation where the blood flow divides,the results suggest that the stenosis ratio determines the ratio of the contributions of elastic shear stress and viscous shear stress to plaque rupture.A n increase of the plaque stiffness enhances the maximum elastic shear stress in the plaque,indicating that a high-stiffness plaque is more prone to rupture for given stenosis ratio.High stress co-localization at the shoulder of plaques agrees with the region of plaque injury in clinical observations.It is demonstrated that,due to the stress-shield effect,the rupture risk of a high-stiffness plaque tends to decrease under high-stenosis conditions,suggesting the existence of a specific stenosis corresponding to the maximum risk.This study may help to complement risk stratification of vulnerable plaques in clinical practice and provides a stenosis mechanical property-specific guide for blood pressure control in cardiovascular health management.
文摘Catheter is commonly used by the surgeons for various reasons in the treatment of a patient suffering with cardiovascular diseases. Catheterization increases the mean flow resistance in the arterial blood flow and many other complications are associated with the presence of catheter in the artery. Effects of catheter in stenosed artery can be estimated non-invasively by means of hemo-dynamic indicator-WSS, WSSG, volume flow rate and impedance. The effect of slip at the arterial wall, inclination of the artery and magnetic field on the hemodynamic indicators and flow profiles are computed, presented and discussed through graphs.
文摘In this paper, we have discussed the biomathematical analysis of Sutterby fluid model for blood flow in stenosed tapered arteries. The equations for the Sutterby fluid model are modeled in cylindrical geometry. The equations have been developed for the ease of mild stenosis. Perturbation solutions are attained in terms of small Sutterby fluid parameter β for the velocity, impedance resistance and wall shear stress. Three types of arteries i.e. converging, diverging and non-tapered have been considered for the analysis and discussion. Graphical results have been presented for different parameters of interest. Streamlines have been plotted at the end of the paper.
文摘BACKGROUND Platelet-rich plasma(PRP)injection is used as an alternative non-operative management for de Quervain’s tenosynovitis(DQT)to regenerate tendon healing.AIM To assess and conclude the research-based study systematically to analyse the efficacy of PRP on DQT.METHODS This systematic review used the Cochrane Handbook for Systematic Reviews and the guideline of preferred reporting items for systematic review and metaanalysis.A systematic literature search was applied to 11 databases.The authors assessed the study quality and risk of bias of each included study.Results of the meta-analysis were presented using mean difference(MD)/standardized mean difference(SMD)and 95%condence interval(CI).RESULTS The authors evaluated 275 studies found in the literature search;12 studies met the criteria for this review,and then the study quality and risk of bias were assessed.Pooled analysis of data from two studies involving 194 subjects with DQT showed that,compared with conservative treatment,PRP injection was associated with a greater reduction in visual analog scale pain in one month and six months after treatment(MD:-0.67,P value<0.00001;MD:-1.16,P value<0.00001)and the increase of Mayo’s wrist score in one month and six months after treatment(SMD:3.72,P value<0.00001;SMD:4.44,P value<0.00001).CONCLUSION PRP can be used as an alternative non-operative treatment for DQT due to the tissue regenerative effect of PRP.
基金The authors would like to thank Prof.Shu Takagi and Prof.Huaxiong Huang for their instructive comments.The authors would also like to acknowledge Jianda Yang for assisting with FEM simulations.This work was supported by the National Natural Science Foundation of China(Grants 11372191,11232010,11650(Grant 91111138)the National Institute of Health(Grant 2R01DC005642-10A1).
文摘Mechanical stimuli play critical roles in cardiovascular diseases,in which in vivo stresses in blood vessels present a great challenge to predict.Based on the structural-thermal coupled finite element method,we propose a thermal expansion method to estimate stresses in multi-layer blood vessels under healthy and pathological conditions.The proposed method provides a relatively simple and convenient means to predict reliable in vivo mechanical stresses with accurate residual stress.The method is first verified with the opening-up process and the pressure-radius responses for single and multi-layer vessel models.It is then applied to study the stress variation in a human carotid artery at different hypertension stages and in a plaque of vascular stenosis.Our results show that specific or optimal residual stresses exist for different blood pressures,which helps form a homogeneous stress distribution across vessel walls.High elastic shear stress is identified on the shoulder of the plaque,which contributes to the tearing effect in plaque rupture.The present study indicates that the proposed numerical method is a capable and efficient in vivo stress evaluation of patient-specific blood vessels for clinical purposes.
文摘This work is concerned with the analysis of blood flow through inclined catheterized arteries having a balloon(angioplasty) with time-variant overlapping stenosis. The nature of blood in small arteries is analyzed mathematically by considering it as a Carreau nanofluid. The highly nonlinear momentum equations of nanofluid model are simplified by considering the mild stenosis case. The formulated problem is solved by a homotopy perturbation expansion in terms of a variant of the Weissenberg number to obtain explicit forms for the axial velocity, the stream function, the pressure gradient, the resistance impedance and the wall shear stress distribution. These solutions depend on the Brownian motion number, thermophoresis number, local temperature Grashof number G_r and local nanoparticle Grash of number B_r. The results were also studied for various values of the physical parameters, such as the Weissenberg number W_i, the power law index n, the taper angle φ, the maximum height of stenosis δ~*, the angle of inclination α, the maximum height of balloon σ~*, the axial displacement of the balloon z_d~*,the flow rate F and the Froud number Fr. The obtained results show that the transmission of axial velocity curves through a Newtonian fluid(Wi=0, n=1, Gr=0, Br=0, Nt=0, Nb≠0) is substantially lower than that through a Carreau nanofluid near the wall of balloon while the inverse occurs in the region between the balloon and stenosis. The streamlines have a clearly distinguished shifting toward the stenotic region and this shifting appears near the wall of the balloon, while it has almost disappeared near the stenotic wall and the trapping bolus in the case of horizontal arteries and Newtonian fluid(Wi=0, n=1, Gr=0, Br=0, Nt=0, Nb≠0) does not appear but for the case of Carreau nanofluid bolus appears.
基金Project supported by the National Natural Science Foundation of China (No. 30070951)
文摘The hemodynamic mechanism of rolling manipulation (RM) of traditional Chinese medical massage (TCMM) is investigated. An axisymmetrical nonlinear model and an arbitrary Lagrangian-Eulerian finite element method (ALE-FEM) with rezoning algorithm were introduced to study the viscous flow through an axisymmetrical rigid tube with axially moving stenosis to simulate the rolling manipulation. Flow rate and wall shear stress were obtained by solving complete Navier-Stokes equations numerically. The numerical results show that the stenosis moving frequency, namely the frequency of rolling manipulation, has great effect on the disturbance of flow and the wall shear stress. The stenosis coefficient, which characterizes the severity of the stenosis, another adjustable parameter in rolling manipulation, also shows the significant effect on flow rate and wall shear stress. These numerical results may provide some data that can be taken into consideration when massage is used in clinic.
文摘This paper explores the mathematical model for couple stress fluid flow through an annular region. The above model is used for studying the blood flow be-tween the clogged （stenotic） artery and the catheter. The asymmetric nature of the stenosis is considered. The closed form expressions for the physiological parameters such as impedance and shear stress at the wall are obtained. The effects of various geomet-ric parameters and the parameters arising out of the fluid considered are discussed by considering the slip velocity and tapering angle. The study of the above model is very significant as it has direct applications in the treatment of cardiovascular diseases.
基金supported by the National Fundamental Research Program of China under Grant No.2006CB708612Zhejiang Funding Scheme to Young College Teachers
文摘The Chinese traditional medical massage has been used as a natural therapy to eliminate some diseases. Here, the effect of the rolling massage frequency to the blood flow in the blood vessels under the rolling massage manipulation is studied by the lattice Boltzmann simulation. The simulation results show that when the frequency is smaller than or comparable to the pulsatile frequency of the blood flow, the effect on the blood flux by the rolling massage is small. 011 the contrast, if the frequency is twice or more times of the pulsatile frequency of the blood flow, the blood flux is greatly enhanced and increases linearly with respect to the frequency. Similar behavior has also been observed on the shear stress on the blood vessel walls. The result is helpful for understanding that the rolling massage has the function of promoting the blood circulation and removing the blood stasis.
文摘The blood flow through a catheterized artery having a mild stenosis at the wall together with a blood clot at the centre is studied in the current investigation.Stenosis can occur in vessels carrying blood to brain(i.e.,Carotid arteries),Renal arteries that supply blood to kidneys etc.The flow is refined in such vessels by application of catheter.We have used a Newtonian viscous fluid model and also distinct shapes of stenosis,(i.e.,symmetric and non-symmetric shapes)are considered for this study.The entropy generation togetherwith viscous dissipation is also taken into account for a complete description of heat transfer mechanism.Exact solutions are calculated for the problem subject to given“no slip conditions”.The results are discussed graphically.The velocity quickly increases for a non-symmetric stenosis as compared to a symmetric stenosis.When the height of mild stenosis increases and the channel becomes narrow then the velocity increases in the centre but it decreases with the stenosed wall.However,as the height of blood clotσincreases then the velocity of blood flow reduces with the wall having clot but it remains almost same with the stenosed wall.Streamlines are plotted to visualize the flow pattern.The trapping is symmetric for a symmetric stenosis shape but it changes to non-symmetric trapping when we have a non-symmetric shape of stenosis.
文摘We present the case of a 29-year-old patient with a history of abdominal pain and vomiting.Based on wireless video capsule findings he was previously diagnosed with ileal Crohn's disease at a different institution,although the clinical and radiological picture was not typical and the response to corticosteroids was poor.We performed a single-balloon enteroscopy showing a short,ulcerous stenosis 50 cm proximal from Bauhin's valve.The endoscopic and clinical histopathological findings were compatible with cryptogenic multifocal ulcerous stenosing enteritis(CMUSE).High dose corticosteroids were again started,without effect.The monoclonal tumor necrosis factor-α(TNF-α) antibody infliximab was added to the medical therapy.After induction therapy,both clinical and endoscopic amelioration was obtained.Larger case studies are needed to confirm the efficacy of TNF-α inhibition in steroid refractory CMUSE.
文摘Biodegradable stents(BDSs)are an attractive option to avoid ongoing dilation or surgery in patients with benign stenoses of the small and large intestines.The experience with the currently the only BDS for endoscopic placement,made of Poly-dioxanone,have shown promising results.However some aspects should be improved as are the fact that BDSs lose their radial force over time due to the degradable material,and that can cause stent-induced mucosal or parenchymal injury.This complication rate and modest clinical efficacy has to be carefully considered in individual patients prior to placement of BDSs.Otherwise,the price of these stents therefore it is nowadays an important limitation.
文摘Hilar tumors have proven to be a challenge to treat and manage because of their poor sensitivity to conventional therapies and our inability to prevent or to detect early tumor formation. Endoscopic stent drainage has been proposed as an alternative to biliary-enteric bypass surgery and percutaneous drainage to palliate malignant biliary obstruction. Prosthetic palliation of patients with malignant hilar stenoses poses particular difficulties, especially in advanced lesions （type Ⅱ lesions or higher）. The risk of cholangitis after contrast injection into the biliary tree in cases where incomplete drainage is achieved is well known. The success rate of plastic stent insertion is around 80% in patients with proximal tumors. Relief of symptoms can be achieved in nearly all patients successfully stented.
文摘To investigate the characteristic radiologic findings of cryptogenic multifocal ulcerous stenosing enteritis (CMUSE) which can be differentiated from other similar bowel disease and to assess their clinical behavior. METHODSTwenty pathologically and clinically confirmed CMUSE patients (males:females = 8:12; mean age: 40.4 years) between March 2002 and August 2015 from seven academic centers in South Korea were retrospectively reviewed. We evaluated small bowel series (SBS; n = 25), computed tomography (CT) enterography (n = 21), magnetic resonance (MR) enterography (n = 2), and abdominopelvic CT (n = 18) images, focusing on enteric and perienteric manifestations. Any change in radiologic features during follow-up period was recorded. We evaluated clinical data including presenting symptoms, laboratory finding and presence of relapse from electronic medical records. Histopathologic findings were also evaluated. RESULTSThe main symptoms were abdominal pain (n = 12) and anemia (n = 10). All patients showed small bowel strictures (n = 52, mean: 2.6 per patient) on initial CT/MR, located in the ileum (n = 47) or jejunum (n = 5). Strictures showed short-length (mean: 10.44 mm) and circumferential bowel wall thickening (mean: 5.56 mm) with layered enhancement (n = 48) that were also noted on initial SBS (n = 36) with shallow ulcers (n = 10). Some ulcerative lesions or wall thickening progressed into strictures on follow-up SBS/CT, and some strictures revealed recurrent ulceration on follow-up SBS. There were no penetrating disease features like fistula or abscess and no gastrointestinal tract involvement except the small bowel. Nine patients experienced disease recurrence (median relapse-free period: 32 mo) even post-operatively. Histopathologic features of surgically resected specimens were characterized as multiple superficial ulcerations confined to mucosa or submucosa and multiple strictures. CONCLUSIONUnder characteristic radiologic findings with multiple short-segmental strictures and/or shallow ulcers of the small intestine, CMUSE should be considered when assessing patients with recurrent abdominal pain and anemia.
文摘Acquired atresia of the external auditory canal(EAC)is a rare cause of conductive hearing loss.It has been traditionally classified into 4 categories:traumatic,post-operative,neoplastic and inflammatory.Post-inflammatory acquired auditory canal atresia is thought to be the result of chronic and repetitive infectious bouts affecting the auditory canal.Nevertheless,the underlying pathophysiology of this disorder is yet to be fully elucidated.Current data fail to clearly state the impact that certain underlying systemic disorders may have on the EAC.The possible association to metabolic disturbances such as iron deficiency is also emphasized.In the light of these findings,this analysis can be used to improve the classification of this entity thereby standardizing the assessment of therapeutic approaches.
文摘Flow fractional reserve(FFR) allows to evaluate the functional significance of coronary artery lesions, through the ratio of the mean coronary artery pressure after the stenosis to the mean aortic pressure duringmaximum hyperemia. The actual widely accepted cutoff value is 0.80. Below this value a coronary lesion is considered significant and therefore it requires invasive revascularization. Several studies [in particular Fractional Flow Reserve vs Angiography for Multivessel Evaluation 1(FAME-1) and FAME-2] have shown the relationship between FFR measurement and hard end-points(death, myocardial infarction, and urgent revascularization). Consequently, FFR evaluation represents the cornerstone in the decision-making in intermediate coronary lesions. Recent studies paved the way for further applications of FFR evaluation in complex and tricky clinical settings. In this paper, we perform an overview of the data regarding contemporary application of FFR. In particular, we review the use of FFR in: left main intermediate stenoses, serial stenoses, evaluation after stenting, guidance in coronary artery bypass surgery, and acute coronary syndrome. All the data presented in our overview confirm the essential role of FFR assessment in the daily clinical practice. The shift from "operator-dependent" to "FFR-dependent" evaluation in intermediate coronary artery stenosis is of paramount importance in order to improve the prognosis of our patients, through the discrimination of the functional role of every single coronary stenosis.
文摘AIM： To present a case series of MRCP-guided endoscopic biliary stent placement, performed entirely without contrast injection. METHODS： Contrast-free endoscopic biliary drainage was attempted in 20 patients with malignant obstruction, unsuitable for resection on the basis of tumor extent or medical illness. MRCP images were used to confirm the diagnosis of tumor, to exclude other biliary diseases and to demonstrate the stenoses as well as dilation of proximal liver segments. The procedure was carried out under conscious sedation. Patients were placed in the left lateral decubitus position. The endoscope was inserted, the papilla identified and cannulated by a papiUotome. A guide wire was inserted and guided deeply into the biliary tree, above the stenosis, by fluoroscopy. A papillotomy approximately 1 cm. long was performed and the papillotome was exchanged with a guiding-catheter. A 10 Fr＇ Amsterdam-type plastic stent, 7 to 15 cm long, was finally inserted over the guide wire/ guiding catheter by a pusher tube system. RESULTS： Successful stent insertion was achieved in all patients. There were no major complications. Successful drainage, with substantial reduction in bilirubin levels, was achieved in all patients. CONCLUSION： This new method of contrast-free endoscopic stenting in malignant biliary obstruction is a safe and effective method of palliation. However＇ a larger, randomized study comparing this new approach with the standard procedure is needed to confirm the findings of the present study.
