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.

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.

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.

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.

Cryptogenic multifocal ulcerous stenosing enteritis: Radiologic features and clinical behavior

AIM 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.METHODS Twenty 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 followup 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. RESULTS The 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 followup 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.CONCLUSION Under 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.

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.

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.

Blood Flow Through a Catheterized Artery Having a Mild Stenosis at the Wall with a Blood Clot at the Centre

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.

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.

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.

Factors associated with trigger digit following carpal tunnel release

BACKGROUND Trigger digit is a common disorder of the hand associated with carpal tunnel syndrome.Carpal tunnel release(CTR)surgery may be a risk factor for trigger digit development;however,the association between surgical approach to CTR and postoperative trigger digit is equivocal.AIM To investigate patient risk factors for trigger digit development following either open carpal tunnel release(OCTR)or endoscopic carpal tunnel release(ECTR).METHODS This retrospective chart analysis evaluated 967 CTR procedures from 694 patients for the development of postoperative trigger digit.Patients were stratified according to the technique utilized for their CTR,either open or endoscopic.The development of postoperative trigger digit was evaluated at three time points:within 6 mo following CTR,between 6 mo and 12 mo following CTR,and after 12 mo following CTR.Firth’s penalized likelihood logistic regression was conducted to evaluate sociodemographic and patient comorbidities as potential independent risk factors for trigger digit.Secondary regression models were conducted within each surgical group to reveal any potential interaction effects between surgical approach and patient risk factors for the development of postoperative trigger digit.RESULTS A total of 47 hands developed postoperative trigger digit following 967 CTR procedures(4.9%).In total,64 digits experienced postoperative triggering.The long finger was most commonly affected.There was no significant difference between the open and endoscopic groups for trigger digit development at all three time points following CTR.Furthermore,there were no significant independent risk factors for postoperative trigger digit;however,within group analysis revealed a significant interaction effect between gender and surgical approach(P=0.008).Females were more likely to develop postoperative trigger digit than males after OCTR(OR=3.992),but were less likely to develop postoperative trigger digit than males after ECTR(OR=0.489).CONCLUSION Patient comorbidities do not influence the development of trigger digit following CTR.Markedly,gender differences for postoperative trigger digit may depend on surgical approach to CTR.

Pulsatile MHD Flow in an Inclined Catheterized Stenosed Artery with Slip on the Wall

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.

Effectiveness of shockwave therapy for stenosing tenosynovitis of radius styloid process:a meta-analysis

Objective:To systematically evaluate the clinical efficacy of extracorporeal shock wave in the treatment of stenosing tenosynovitis of radius styloid process.Methods:All randomized controlled trials of extracorporeal shock wave in the treatment of stenotic tenosynovitis of radius styloid process were retrieved by computer.Two researchers independently screened,extracted and incorporated the literature into the literature evaluation.The quality evaluation was carried out with the bias risk assessment tool provided by Cochrane Collaboration Network,and the meta-analysis was carried out with RevMan 5.3 software.Result:According to the prescribed retrieval method,there were 8 articles and 447 subjects.The results showed that the effective rate of extracorporeal shock wave was(OR=5.37,95%CI(2.85,10.12),P<0.00001)compared with other therapies,and the difference was statistically significant.Meanwhile,there were significant differences in VAS pain score and Cooney dysfunction score.Conclusion:Extracorporeal shock wave can effectively relieve the pain symptoms of stenosing tenosynovitis of the radius styloid process,improve wrist dysfunction and improve the clinical efficiency of stenosing tenosynovitis of the radius styloid process,but a large number of high-quality studies are needed to provide more sufficient evidence.

Mathematical modelling of couple stresses on fluid flow in constricted tapered artery in presence of slip velocity-effects of catheter

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.

Interspinous Process Implants Causes Wear of the Spinous Processes in Patients Treated for Spinal Stenosis—An Experimental Biomechanical Study with Comparison to Clinical Cases

There are few biomechanical studies on Interspinous Process Implants (IPD);however none investigate the amount of wear on spinous processes. Therefore the objective of the present study was to investigate the effect of repetitive loading of the IPD Aperius on the spinous processes in a biomechanical porcine model. For comparison, three patients treated surgically with the same device have been followed for one to two years clinically and with image analyses (X-rays, MRI, CT-scans). Four lumbar spines from 6 months old porcine were divided into seven segments, which received IPD. The segments were exposed to 20,000 cyclical loads. Afterwards the deformation (wear) of the segments was registered. The wear of the spinous processes was measured in mm on a following CT-scan. Additionally, the wear of the ex-vivo was compared to that of the spinous processes investigated by CT-scans or X-ray in three patients treated surgically with the same interspinous implant. The mean maximal deformation of porcine specimens was 1.79 mm (SD 0.25) with the largest deformation occurring in the first quarter of the loading (<5000 cycles). The mean wear of the spinous processes after loading was 6.57 mm. A similar level of wear (mean 12.7 mm) of the spinous processes was detected in the patients. The Aperius IPD creates significant wear on the spinous processes in an experimental biomechanical study. Similar wear of the spinous processes is also present in patients treated with the same device post-operatively. How these findings influence the short and long term result of this implant device remains to be investigated in further biomechanical as well as clinical studies. For future development of this type of devices a proper selection of materials and design is essential to minimize wear effects on the spinous processes and thereby increases the possibilities for the devices to function as suggested.