Impact of Revascularization on the Distal to Proximal Pressure Ratio in Case of Multiple Coronary Stenoses

Objective: In order to take a decision about the revascularization approach to be adopted, it is of fundamental importance to determine whether coronary artery stenoses induce ischemia or not. An index, named (Fractional Flow Reserve), based on pressure measurements has been proposed to this aim and is usually interpreted in terms of flows. The objective of this work is to compute simultaneously pressures and flow rates in the coronary network of patients with three-vessel disease, in order to study more precisely the relationship between these two quantities. Approach: 22 patients have been included in the study. Some pressure and flow rate measurements were collected during by-pass surgery. These clinical data allow determining parameters for a patient’s specific model, based on the electric/hydraulic analogy. Collateral pathways are included in the model, as well as the severity of the disease and the impact of revascularization. Main Results: For patients with stenoses on LAD, LCx, LMCA and occlusion of the RCA, the flow rate delivered to the right territory is of course a function of the aortic pressure, the left stenoses severity, and the pressure distal to the thrombosis. But it mainly depends on the capillary and collateral resistances, and on the proportion between them. Abnormal microvascular hemodynamics, may be present in patients with non-hemodynamic significant lesions as assessed by the pressure ratio. Complete revascularization with the 3 grafts is demonstrated to be fully justified. The direction of collateral flows may be reversed, depending on the pressure gradient. In any case, they remain low and become negligible when the 3 grafts are operating. Significance: Surgical decision based only on pressure measurements may miss some real hemodynamic problems due to the considered stenosis. This risk is even greater in case of serial stenoses.

Platelet-rich plasma for de Quervain’s tenosynovitis: A systematic review and meta-analysis

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.

Effects of stenoses on non-Newtonian flow of blood in blood vessels

In this paper, a mathematical model for steady blood flow through blood vessels with uniform cross-section in stenoses arteries has been proposed. Blood is assumed to be non- Newtonian, incompressible and homogeneous fluid. Blood in human artery is represented as Bingham plastic fluid. Expressions for flow rate, wall shear stress, and resistance to flow against stenoses size have been obtained. Obtained results indicate that stenoses size decreases the flow rate and increases the wall shear stress as well as resistance to flow.

The effects of slip condition and fluid flow through a channel multiple stenoses on micropolar of non-uniform cross-section

In this paper, steady incompressible micropolar fluid flow through a non-uniform channel with multiple stenoses is considered. Assuming the stenoses to be mild and using the slip boundary condition, the equations governing the flow of the proposed model are solved, and closed-form expressions for the flow characteristics （resistance to flow and wall shear stress） are derived. The effects of different parameters on these flow characteristics are analyzed. It is observed that both the resistance to the flow and the wall shear stress increase with the heights of the stenoses and the slip parameter; but decrease with the Darcy number, b^rthermore, the effects of the wall exponent parameter, the cross-viscosity coefficient and the micropolar parameter on the flow characteristics are discussed.

Biodegradable stents in gastrointestinal endoscopy

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.

Endoscopic approach to malignant strictures at the hepatic hilum

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.

Fractional flow reserve: Current applications and overview of the available data

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.

Contrast-free endoscopic stent insertion in malignant biliary obstruction

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.

Management of primary sclerosing cholangitis

Primary sclerosing cholangitis (PSC) is a rare cholestatic liver disease with major morbidity and mortality.Therapeutic management is difficult,due to lack of conclusive data and individual disease progression.High-dose UDCA was used for years as a pharmacotherapeutic agent to prevent disease progression,based on a positive trend in pilot studies,but has recently been proven to have a negative effect in advanced disease.Immunosuppressants might be useful in patients with overlap syndromes.Dominant bile duct stenoses should be treated endoscopically,and cholangiocellular carcinoma (CCC) still remains a therapeutic challenge in PSC patients.Early diagnosis of CCC must be improved and new strategies such as neoadjuvant radiochemotherapy with subsequent liver transplantation in selected patients are further options to be considered.

Endoscopic Internal Urethrotomy (EIU): Results of a Dynamic Study at the Urology-Andrology Department of the University Hospital Center (UHC) of Conakry

Introduction: Endoscopic internal urethrotomy (EIU) is a technique that consists of an incision of the stenosed urethra under visual control. Its indication is widespread since the first description in 1971 by Sachse. The objective was to analyze the results of EIU in the treatment of urethral stenosis (US) at the Andro-Urology Department of the UHC of Conakry. Methodology: It is a prospective descriptive study, lasting 18 months (January 2016-30 June 2017). It involved 102 patients. The variables were: age, etiology of US, type of catheter, duration of catheter wear and recurrences. After a 12-month follow-up, our results were considered good in the absence of recurrences. Results: The average age was 54.25 years with the extremes comprising between 16 and 96 years. The main reasons for medical checkup were chronic urine retention at 58.82%. Etiology infection was the most frequent with a ratio of 81.37%, while Escherichia coli was found at 51.29%. US was bulbar (71.57%), unique (67.64%) and less than 1 cm (60.78%). Surgical complication occurred with 9 patients (8.82%) with urethrorrhagia and the external genital organs infiltration in 4 cases. Results were good for 77 patients (75.49%). Stenosis post infection, long and multiple stenoses, urethral catheterization with latex catheter and urethral catheterization of more than 4 days were strongly associated with the recurrence occurrence. Conclusion: The EIU is a minimally invasive surgical technique that offers good results.

A Study for Analyzing the Effect of Overlapping Stenosis and Dilatation on Non-Newtonian Blood Flow in an Inclined Artery

The stenosis in the artery, which reduces the flow passage to blood, is a common cardiovascular disease that is responsible even for cardiac arrest sometimes. The hemodynaics reveals that the severe blockage in an artery due to stenosis generates pressure tangential stress that impacts adversely on the arterial wall downstream to stenosis and weakens the arterial wall. The site of weakened wall in the artery generates post stenotic dilatation. The objective of this paper is to study flow of blood, of non-Newtonian in nature described by Herschel-Bulkley model, in a diseased artery suffering with partly overlapped two stenoses and a dilatation distal to the stenoses. A mathematical model, describing the blood flow, has been derived using Navier-Stokes equations along with the prescribed geometry of the diseased artery. The expressions of velocity profile, resistive impedance to flow and wall shear stress (skin-friction) are derived. The effect of inclination of the vessel on the resistive impedance to flow is discussed along with the effect of rheological and geometrical parameters on the resistive impedance to flow and skin friction.

Infliximab induces remission in cryptogenic multifocal ulcerous stenosing enteritis:First case

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.

A prediction of in vivo mechanical stresses in blood vessels using thermal expansion method and its application to hypertension and vascular stenosis

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.

Biomathematical study of time-dependent flow of a Carreau nanofluid through inclined catheterized arteries with overlapping stenosis

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.

Cryptogenic multifocal ulcerous stenosing enteritis: Radiologic features and 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.

Post-inflammatory acquired atresia of the external auditory canal

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.

Genetic analysis is helpful for the diagnosis of small bowel ulceration

The widespread use of capsule endoscopy and balloonassisted endoscopy has provided easy access for detailed mucosal assessment of the small intestine. However, the diagnosis of rare small bowel diseases, such as cryptogenic multifocal ulcerous stenosing enteritis(CMUSE), remains difficult because clinical and morphological features of these diseases are obscure even for gastroenterologists. In an issue of this journal in 2017, Hwang et al reviewed and summarized clinical and radiographic features of 20 patients with an established diagnosis of CMUSE. Recently, recessive mutations in the PLA2G4A and SLCO2A1 genes have been shown to cause small intestinal diseases. The small bowel ulcers in each disease mimic those in the other and furthermore those found in nonsteroidal anti-inflammatory drug-induced enteropathy. These recent and novel findings suggest that a clinical diagnosis exclusively based on the characteristics of small bowel lesions is possibly imprecise. Genetic analyses seem to be inevitable for the diagnosis of rare small bowel disorders such as CMUSE.

Non-Newtonian biomagnetic fluid flow through a stenosed bifurcated artery with a slip boundary condition

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.

NUMERICAL INVESTIGATION OF EFFECT OF ROLLING MANIPULATION OF TRADITIONAL CHINESE MEDICAL MASSAGE ON BLOOD FLOW

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.

Numerical study of biomechanical characteristics of plaque rupture at stenosed carotid bifurcation:a stenosis mechanical property-specific guide for blood pressure control in daily activities

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.