Segment Of Arch Research Articles

Clinical predictors of recurrent cephalic arch stenosis and impact of the access flow reduction on the patency rate

Despite the widespread use of conventional percutaneous transluminal angioplasty (PTA), recurrence of cephalic arch stenosis (CAS), and low patency rate after PTA remain challenging problem. We aimed to identify the clinical predictors of recurrence of CAS and evaluate the effect of the access flow reduction on the fistula patency rate in patients with recurrent CAS. In 1118 angiographies of 220 patients with CAS, access circuit patency rates after PTA and potential clinical predictors of recurrence of CAS were assessed. The effect of the banding procedure was evaluated in terms of post-interventional primary patency rate, and the number of interventions per access-year. At 3, 6, and 12 months after the first PTA on CAS, the post-interventional access circuit primary patency rates were 68.8%, 40.5%, and 25.1%, respectively. High CV to CA ratio (the ratio of the maximal diameter of the distal cephalic vein to the diameter of the cephalic arch) (Hazard ratio (HR), 1.437; 95% confidence interval (CI), 1.036-1.992) and involvement of the proximal segment of cephalic arch (HR, 1.828; 95% CI, 1.194-2.801) were significant predictors of recurrent CAS. For those with recurrent CAS (>3 times/year) and an access flow rate >1.5 L/minute, endovascular banding procedure was performed. The banding procedure significantly reduced the number of interventions per access-year (t = 3.299, p = 0.005 and t = 2.989, p = 0.007, respectively). Post-interventional access circuit primary patency rate after banding was significantly higher than that before banding (p = 0.01). High CV to CA ratio and involvement of the proximal segment of the cephalic arch are independent clinical predictors of recurrent CAS. Endovascular banding might delay recurrence of CAS in patients with high CV to CA ratio and high access flow.

POS-590 CLINICAL PREDICTORS OF RECURRENT CEPHALIC ARCH STENOSIS AND IMPACT OF THE ACCESS FLOW REDUCTION ON THE PATENCY RATE

Despite the widespread use of conventional percutaneous transluminal angioplasty (PTA), recurrence of cephalic arch stenosis (CAS) and low patency rate after PTA remain challenging problem. We aimed to identify the clinical predictors of recurrence of CAS and evaluate the effect of the access flow reduction on the fistula patency rate in patients with recurrent CAS. In 1,118 angiographies of 231 patients with CAS, access circuit patency rates after PTA and potential clinical predictors of recurrence of CAS were assessed. The effect of the banding procedure was evaluated in terms of post-interventional primary patency rate, and the number of interventions per access-year. At 3, 6, and 12 months after the first PTA on CAS, the post-interventional access circuit primary patency rates were 64.7%, 41.4%, and 24.8%, respectively. High CV to CA ratio (the ratio of the maximal diameter of the distal cephalic vein to the diameter of the cephalic arch) (Hazard ratio [HR], 1.425; 95% confidence interval [CI], 1.041-1.951) and involvement of the proximal segment of cephalic arch (HR, 1.773; 95% CI, 1.177-2.671) were significant predictors of recurrent CAS. The banding procedure significantly reduced the number of interventions per access-year (t = 3.299, p = 0.005 and t = 2.989, p = 0.007, respectively). Post-interventional access circuit primary patency rate after banding was significantly higher than that before banding (p = 0.01). High CV to CA ratio and involvement of the proximal segment of the cephalic arch are independent clinical predictors of recurrent CAS. Endovascular banding might delay recurrence of CAS in patients with high CV to CA ratio and high access flow.

Structural analysis and improvement for a new form traveler in long-span cantilever-casting arch bridge

A form traveler used in bridge construction has a great influence on the safety of the performance and alignment of bridges. As a cantilever casting segment of a bridge becomes longer and heavier, the traditional form traveler may not meet the strength and stiffness requirements, and there is a risk of collapse. This study has devised a new triangle truss form traveler and investigated the performance based on the Ye-Lang Lake arch bridge in China. Firstly, the numerical models of the form traveler were established to get the strength and stiffness index of the form traveler used for the arch Segment 2. Subsequently, the improvement scheme of the mechanical properties of the form traveler has been proposed. Then the partial refined numerical analysis model of the C-type hook has been established, a finite element model, and a design scheme for improving partial structures of the C-type hook was proposed. Finally, the field load test was carried out to verify the reliability of the new form traveler. The test results show that the improvement of the new form traveler is effective.

A tectonic model for the Transcontinental Arch: Progressive migration of a Laurentian drainage divide during the Neoproterozoic–Cambrian Sauk Transgression

AbstractA widespread provenance shift recorded by passive margin strata of western Laurentia, from predominant Stenian (1.2–1.0 Ga) detrital zircon age components to their absence, occurred during the Neoproterozoic–Cambrian Sauk transgression and is commonly used as a ca. 540 Ma chronostratigraphic marker throughout the west/south‐western United States. However, in Neoproterozoic–Cambrian strata of this region, we identify a probable shift from distal to more proximal Stenian‐age zircon sources before a diachronous loss of Stenian detrital zircon age components. We suggest these provenance patterns reflect progressive subsidence of the passive margins surrounding Laurentia and concomitant relative uplift of the Transcontinental Arch, a broad and segmented northeast–southwest trending topographic high across the Laurentian midcontinent possibly due to lithospheric flexure. The Transcontinental Arch segments align with transverse rift structures of the Neoproterozoic–Cambrian Iapetan margin and the Mesoproterozoic Midcontinent Rift, perhaps reflecting rejuvenation of midcontinent lithospheric weaknesses during the Sauk transgression and final Rodinia breakup.

Surprising astigmatism hypercorrection after corneal ring segments implantation in keratoconus treatment after 8 years of follow up

Objective: To report a case of hypercorrection of astigmatism (Cyl) after implantation of 2 segments of short arch ring for keratoconus treatment and to describe its replacement by long arch segment. Methods: This is a case report of a patient with keratoconus and no adaptation to glasses or contact lenses, who was implanted 2 ring segments: upper nasal (155º/ 200μm) and inferior temporal (155º/ 250μm).Results: First postoperative month: CVA = 20/ 50 (-10.50-2.50x135°) and SimK K1 = 48.4x143° and K2 = 51.2x53° (Cyl 2,8D). In the 3rd year: CVA 20/ 30 (-6.00-2.50x135º), with inversion of the axes: K1 = 49,5x60º and K2 = 52,0x150º (Cyl 2,6D). The hypercorrection increased up to the 8th year: CVA = 20/40 (-4,50-6,00x75º) and SimK 47,8x51º/ 60,4x141º (Cyl 12,6D). The 2 segments were replaced for a single segment (320º/ 300μm) and after 1 month: CVA = 20/ 25 (-5,75 spherical) with SimK 46,8x38º/ 48,9x128º (Cyl 2,1D). Conclusion: The ring aims to flatten the most curved meridian, but surpassing the previous value induces astigmatism in the opposite meridian. The hypercorrection of the 2 short segments must occur due to its movement of the extremities, which does not occur with the single long arc segment (≥ 300º).Abbreviations: CVA = Corrected visual acuity, SimK = Simulated keratometry, LE = Left eye, RE = Right eye

Application of a combined precast and in-situ-cast construction method for large-span underground vaults

Exploitation of large underground space calls for innovative structures and construction methods. In this paper, a combined precast and in-situ-cast method for construction of large-span underground vaults is proposed. It was applied to an engineering example in the form of the vault of the Wuzhong Road Metro Station in Shanghai. This vault consists of 56 elements. Construction of an element involves the following steps. Firstly, upper ribbed arch segments are precast in a factory. After hardening, they are transported to the site and then assembled to three-hinged arches. The latter serve as a permanent formwork. Then, steel cages are made, followed by in-situ casting of concrete. As the concrete hardens, an integral arch, representing an element of the vault, is obtained. It carries the dead load of the covering soil and the overload on top of it. Structural analysis of this example is based on transfer relations, representing analytical solutions of the linear theory of slender circular arches. From the viewpoint of engineering practice and computational analysis, the advantages of the combined precast and in-situ-cast method over the in-situ-cast method are as follows: (i) the construction period is shortened by 50%, (ii) a fair-faced concrete surface of the vault is produced, rendering decoration work superfluous, and (iii) the maximum bending moment of an element of the studied vault is reduced by 40%.

Ascending Aortic Slide for Interrupted Aortic Arch Repair

Interrupted aortic arch (IAA) often presents with a wide gap between the proximal and distal portions of the arch which challenge a tension-free anastomosis, potentially increasing the risk for residual or recurrent arch obstruction, and left main bronchial compression. When possible, to preserve potential for growth of the repair, native tissue-to-tissue reconstruction is always preferred. Accordingly, rather than forcing a direct anastomosis with native tissue under tension or needing an interposition graft, the ascending aortic slide is an alternative useful technique to repair interrupted aortic arch in neonates and infants with difficult anatomy. Using a bridging flap of native tissue from the split ascending aorta and completion with patch material to fill in the lesser arch curvature, it has successfully been used in nine babies for bi-ventricular repair and uni-ventricular palliation with satisfactory results, and potential for growth. Interrupted aortic arch (IAA) often presents with a wide gap between the proximal and distal portions of the arch which challenge a tension-free anastomosis, potentially increasing the risk for residual or recurrent arch obstruction, and left main bronchial compression. When possible, to preserve potential for growth of the repair, native tissue-to-tissue reconstruction is always preferred. Accordingly, rather than forcing a direct anastomosis with native tissue under tension or needing an interposition graft, the ascending aortic slide is an alternative useful technique to repair interrupted aortic arch in neonates and infants with difficult anatomy. Using a bridging flap of native tissue from the split ascending aorta and completion with patch material to fill in the lesser arch curvature, it has successfully been used in nine babies for bi-ventricular repair and uni-ventricular palliation with satisfactory results, and potential for growth. Commentary: Sometimes, the Bench Players Are Your Most Valuable PlayersOperative Techniques in Thoracic and Cardiovascular SurgeryVol. 26Issue 3PreviewIn the current issue of the Operative Techniques Journal, Dodge-Khatami and Meyer describe their strategy for repair of interrupted aortic arch using the ascending aortic slide technique to bridge the gap between the interrupted arch segments. In their technique, the medial ascending aorta is split longitudinally in half starting from the sinotubular junction up to the arch origin. This ascending aorta flap is then rotated leftward and posteriorly and used as a posterior bridge of native tissue to connect the proximal and distal parts of the interruption. Full-Text PDF

The choice of tactic for surgical treatment of aortic arch hypoplasia with ventricular septal defect in infants

Aim: to determine the optimal tactic for surgical correction of aortic arch hypoplasia and ventricular septal defect (VSD) in infants based on the comparison of immediate and follow-up outcomes of one- and two-stage repair.Materials and methods. Between 2011 to 2019, 138 patients under the age of one year underwent surgical repair of aortic arch hypoplasia with VSD in the leading Ukrainina cardiosurgical institutions – National M. Amosov Institute of Cardiovascular Surgery Affilated to National Academy of Medical Sciences of Ukraine and Center for Pediatric Cardiology and Cardiac Surgery. Patients were divided into two groups: group I involved 66 (47.8 %) patients who underwent one-stage repai of aortic arch hypoplasia and VSD, group II included 72 (52.2 %) patients with two-stage repair, consisting of aortic arch reconstruction and pulmonary banding at the first stage, and correction of VSD at the second stage.Results. The total hospital mortality was 3.6 % (n = 5). In group I, hospital mortality was 3.0 % (n = 2), in group II – 4.2 % (n = 3), but this difference is not statistically significant (P > 0.05). Follow-up was from 1 month to 11 years. Mortality rate over follow-up period was 0 %. Aortic arch restenosis developed in 16 (11.6 %) patients: 6 (9.1 %) patients in group I and 10 (13.9 %) patients in group II. There was no statistically significant difference in restenosis development between two groups. Compression of the trachea and left main bronchus developed in two patients of group II (2.8 %). There were no residual VSDs which would need repeated repair.Conclusions. Both one-stage and two-stage tactic for surgical treatment of aortic arch hypoplasia with VSD in infants is effective and safe showing good immediate and long-term follow-up results. The study indicates that one- stage correction is more acceptable in infants with hypoplasia of segment C or all aortic arch segments. Stage tactic can be used in hypoplasia of segments B and A.

Abstract 13025: Methotrexate Carried in Lipid Core Nanoparticles Prevented the Dilation and Dissection of the Aortic Arch in Mice With Marfan Syndrome by Increasing the Bioavailability of Intracellular Adenosine

Introduction: Mutations in the fibrillin-1 gene result in aneurysms and rupture of the aorta, the main cause of mortality in patients with Marfan syndrome (MFS). Inflammation is associated with dissection and rupture of the aorta. We showed that methotrexate (MTX) carried in lipid core nanoparticles (LDE) had powerful anti-inflammatory effects on atherosclerotic lesions and myocardial infarction. Hypothesis: To investigate whether treatment with LDE-MTX can prevent the development of aortic arch lesions in MFS. Methods: mgΔloxPneo MFS murine model and wild-type mice were allocated in 3 groups of treatment: LDE only; MTX in commercial formulation; LDE-MTX. The treatment occurred weekly at a dose of 1mg/kg ip, between the 3rd and 6th month of life, period in which both dilation and dissection of the aortic arch are observed. After 12 weeks, animals were submitted to analysis of the aortic arch. Results: Compared to LDE and MTX groups, LDE-MTX treatment showed smaller lumen area of ascending and descending aorta and aortic arch segments in MFS mice. LDE-MTX also decreased collagen volume fraction and the amount of aortic dissections, but did not affect the thickness of the vessel wall and the number of elastic fiber ruptures. Protein expression of the inflammatory markers CD68 (macrophages), CD3 (lymphocytes) and tumor necrosis factor alpha, of the apoptotic marker caspase 3 and of type 1 collagen were lower in LDE-MTX group when compared to LDE and MTX. Moreover, treatment with LDE-MTX reduced TGF-β, ERK and SMAD3 protein expression. Of note, CD68 and CD3 protein expression were positively correlated with the lumen area of the aortic arch (r2=0.36; p<0.001), indicating the importance of inflammation for the aortic dilation. The increase in bioavailability of intracellular adenosine was suggested by higher expression of A2a adenosine receptor and lower levels of adenosine deaminase in the aortic arch. Conclusions: Possibly by increasing the bioavailability of intracellular adenosine, LDE-MTX treatment had the ability to reduce the processes of inflammation, apoptosis and fibrosis that are consequent to fibrillin-1 mutation. By these means, LDE-MTX may conceivably prevent the development of the dilation and dissection in the aortic arch, the hallmarks of MFS.

Radiologic Analysis of Malar Arch Movement in Reduction Malarplasty Without Bony Resection.

Reduction malarplasty has been popular among Asians with a wide facial width. In general, malar setback after bony resection is regarded as the standard objective of reduction malarplasty. However, unnecessary bony resection may lead to various postoperative complications. Therefore, we suggest the use of reduction malarplasty without bony resection to achieve a similar narrowing effect of the facial width, based on radiographic analysis of malar arch movement. This retrospective study analyzed 48 patients with a wide midface who underwent reduction malarplasty between September 2018 and December 2019. We included 40 cases of advancement repositioning malarplasty (AR) without bony resection and 8 cases of setback reduction malarplasty (SR) with bony resection. The three-dimensional position of the malar arch expressed by coordinates (x, y, and z) on three-dimensional computed tomography scans was used to compare the positional change between the surgical methods. The paired t-test, Wilcoxon text, and independent t-test were used in data analysis, and statistical analysis was performed using SPSS 23.0 software. Medial and superior movement of the freed malar arch segment was significantly different between AR and SR (P < 0.05). Although medialization and superiorization were not significantly different between AR and SR, there was a significant difference in anterior-posterior movement between AR and SR (P < 0.05). The radiologic analysis based on malar arch movement between AR and SR showed similar narrowing effects on medialization and superiorization of the malar arch regardless of bony resection. Therefore, the AR can be effectively applied in case of arch dominant type or malar asymmetry. In addition, further comprehensive study including analysis on movement of facial soft tissue following malar bony movement is expected based on this study in near future.

Methotrexate associated with a lipid core nanoparticle prevented the dilation and dissection of the aortic arch in mice with Marfan syndrome

Abstract Introduction Mutations in the fibrillin-1 gene result in dilation, dissection and rupture of the aorta, the main cause of mortality in patients with Marfan syndrome (MFS). Inflammation is associated with greater susceptibility to dissection and rupture of the aorta. Previously, we showed that methotrexate (MTX) carried in lipid core nanoparticles (LDE) had powerful anti-inflammatory and anti-proliferative effects on rheumatoid arthritis and atherosclerotic lesions induced in rabbits and improved myocardial infarction morphological and functional aspects in rats with ligation of left coronary artery. When MTX is associated to LDE, the uptake of the drug by the cells is increased several-fold, which conceivably endows MTX with enhanced action mechanisms and the drug toxicity is diminished. Purpose To investigate whether treatment with LDE-MTX can prevent the development of aortic arch lesions in a murine model of MFS. Methods mgΔloxPneo MFS murine model and wild-type mice were allocated in 3 groups of treatment: LDE only; MTX in commercial formulation; LDE-MTX. The treatment occurred weekly at a dose of 1mg/kg ip, between the 3rd and 6th month of life, period in which both dilation and dissection of the aortic arch are observed. After 12 weeks, the animals were submitted to echocardiography, morphometry and protein expression of the aortic arch. Results Compared to LDE and MTX groups, LDE-MTX treatment showed smaller lumen area of ascending and descending aorta and aortic arch segments in MFS mice. LDE-MTX also decreased the collagen volume fraction and the amount of aortic dissections, but did not affect the thickness of the vessel wall and the number of elastic fiber ruptures. The protein expression of the inflammatory markers CD68 (macrophages), CD3 (lymphocytes) and tumor necrosis factor alpha, of the apoptotic marker caspase 3 and of type 1 collagen were lower in MFS LDE-MTX group when compared to MFS mice treated with LDE and MTX. Moreover, treatment with LDE-MTX reduced TGF-β, ERK and the SMAD3 protein expression. Of note, CD68 and CD3 protein expression was positively correlated with the lumen area of the aortic arch (r2=0.36; p&amp;lt;0.001), indicating the importance of inflammation for the aortic dilation. The increase in bioavailability of intracellular adenosine in MFS animals treated with LDE-MTX was suggested by the higher expression of A2a adenosine receptor and the lower expression of adenosine deaminase in the aortic arch. Conclusion Possibly by increasing the bioavailability of intracellular adenosine, LDE-MTX treatment had the ability to reduce the processes of inflammation, apoptosis and fibrosis that are consequent to fibrillin-1 mutation. By these means, LDE-MTX may conceivably prevent the development of the dilation and dissection in the aortic arch, the hallmarks of MFS, in this animal model. Funding Acknowledgement Type of funding source: Public grant(s) – National budget only. Main funding source(s): FAPESP (Fundação de Amparo à Pesquisa do Estado de São Paulo)

Correction of the aortic arch hypoplasia in newborn babies, suffering complete form of atrio-ventricular septal defect

Objective. Tactics of treatment and results of the hypoplasia of the aortic arch correction in newborn babies with complete form of atrio-ventricular septal defect were studied.&#x0D; Маterials and methods. During period from 2011 tо 2019 yrs in 21 patients correction of hypoplasia of aortic arch and atrio-ventricular septal defect were performed. The investigated group consisted of patients with a two-ventricular physiology. The patients, suffering imbalanced form of atrio-ventricular septal defect and with variants of hypoplasia in left parts of the heart, were excluded from the investigation. There were 9 (42.9%) boys and 12 (57.1%) girls. Average age of the patients have constituted (2.3 ± 1.1) mo (from 0.06 до 7.7 mo). Average body mass of the patients have constituted (3.8 ± 1.0) kg (from 2.0 до 5.9 kg). The aortic arch segment was considered a hypoplastic one if a Z-score (Standard Score - standard estimation) shift have constituted lesser than 2.0.&#x0D; Results. Hospital lethality have constituted 14.2%. Three newborn babies died: 2 - after first stage of correction, and 1 - after second stage of correction. All the patients, to whom a one-staged correction was done, have survived. The causes of lethality were not connected with method of the aortic arch reconstruction. While performance of echocardiography before discharge from the hospital the pressure gradient on place of the aortic arch plasty have constituted (13.6 ± 6.8) mm Hg at average. Average follow-up period have constituted (2.6 ± 2.1) yrs (from 2 mo tо 8.1 yr). In late follow-up period lethality was absent. In 2 (9.5%) patients in postoperative period reoperations on aortic arch and mitral valve were performed. Tracheal compression as well as the main bronchi compression, neurological complications in late follow-up period were absent.&#x0D; Conclusion. For the patients, suffering complete form of atrio-ventricular septal defect in conjunction with hypoplasia of aortic arch the staged correction constitutes a more favorable option, owing good immediate and late results. A staged approach in the treatment is indicated for newborn babies, suffering hypoplasia of distal aortic arch and competent atrio-venticular valves or with small regurgitation. Оne-stage correction is indicated in hypoplasia of aortic arch, pronounced regurgitation on common atrio-ventricular valve and pronounced heart failure.

Estimate of DMFT index using teeth most affected by dental caries in Benghazi, Libya

Background: Although the oral health status is improved over the past years, the dental caries is still the most common chronic disease in childhood. Oral health affects many aspects of life such as ability to speak, mastication and well being. Aims: to determine the prevalence of caries of the first permanent molars (FPMs) and to compare the caries incidence between maxillary and mandibular arch, and to determine the most affect segment by the decay in the dental arch. Material and Methods: This cross-sectional survey was conducted of 375 children aged 6 to 12 years in Benghazi city of Libya. The clinical examination for dental caries was based on the World Health Organization (WHO) criteria. It has been calculated the frequency of caries free (CF) and the DMFT index in terms of decayed teeth (DT), filled teeth (FT) and missing teeth (MT). Data were analyses using SPSS version 16, Chi-square test and the Kruskal-Wallis tests were used. Results: A significant difference was found between sound and carious FPMs in all dental arch segments (P =0.001). The DMFT index of the sample was (1.80±.081) whereas; the highest rate was in left side of the mandible (0.51±.026). The DT component was the highest rate (92.6%) of the DMFT index. Conclusion: The DMFT in the mandible was higher than the maxilla. The caries prevalence of FPMs was similar in both sides of the dental arches, thus the intensive preventive and health service activities should be promote in Libya to decrease caries risk in school children.

Aortic heterogeneity across segments and under high fat/salt/glucose conditions at the single-cell level.

The aorta, with ascending, arch, thoracic and abdominal segments, responds to the heartbeat, senses metabolites and distributes blood to all parts of the body. However, the heterogeneity across aortic segments and how metabolic pathologies change it are not known. Here, a total of 216 612 individual cells from the ascending aorta, aortic arch, and thoracic and abdominal segments of mouse aortas under normal conditions or with high blood glucose levels, high dietary salt, or high fat intake were profiled using single-cell RNA sequencing. We generated a compendium of 10 distinct cell types, mainly endothelial (EC), smooth muscle (SMC), stromal and immune cells. The distributions of the different cells and their intercommunication were influenced by the hemodynamic microenvironment across anatomical segments, and the spatial heterogeneity of ECs and SMCs may contribute to differential vascular dilation and constriction that were measured by wire myography. Importantly, the composition of aortic cells, their gene expression profiles and their regulatory intercellular networks broadly changed in response to high fat/salt/glucose conditions. Notably, the abdominal aorta showed the most dramatic changes in cellular composition, particularly involving ECs, fibroblasts and myeloid cells with cardiovascular risk factor-related regulons and gene expression networks. Our study elucidates the nature and range of aortic cell diversity, with implications for the treatment of metabolic pathologies.

The task 3 of forming a network on the sphere from the circles of the same radius

one of the methods of formation of geometric networks of arches of the same radius using regular spherical polyhedra is Investigated. The conditions of the task of placing the specified network on the sphere are set. The criterion for evaluating the effectiveness of solving the problem is the minimum number of standard sizes of segments of the dome arches, the possibility of using technologies of enlarging assembly. The solution of one variant of the problem of placing a geometric network on a spherical cube and, accordingly, on a sphere is given. Placement on the sphere of arches of one radius, different from placement in the form of meridians, has an effective solution in the form of a network with minimal dimensions of arch segments and nodes of paired arches formed on the basis of circles of identical radii formed on the basis of regular spherical polyhedra. The problem is solved by constructing an independent framework of arches of the same radius on the basis of paired circles of the same radius in the spherical cube system.

Quasi-static tests on 1:3 scaled arch segments of the Old Bridge in Mostar

Masonry stone arch, and other types of masonry structures, owed their durability through the centuries primarily to the inventiveness of the builders, who, by introducing new connection elements, managed to build structures that would resist various effects through the time. Connection elements used for assembling bridge vaults, or clamps and dowels made of wrought iron with the additional use of liquid lead and mortar, are one of the successful ways to increase stability and load-bearing capacity of this type of structures. A similar assembly technique was applied during construction of the original Old Bridge in Mostar in 1566 and its reconstruction in 2004. This paper presents experimental tests performed on 1:3 scaled arch segments of the Old Bridge in Mostar and obtained results. This experimental research was conducted in order to describe the behaviour of all connection elements participating in the transfer of loads that can occur. Obtained results of the performed experimental tests are highly utilisable for further numerical analyses and verification of the existing and new mathematical models.

Quasi-static tests on 1:3 scaled arch segments of the Old Bridge in Mostar

Quasi-static tests on 1:3 scaled arch segments of the Old Bridge in Mostar

Metoda plastyki łuku aorty z zachowaniem przewodowego przepływu systemowego w leczeniu krytycznej koarktacji o morfologii bovine trunk

Introduction. Coarctation of the aorta is a congenital heart defect defined as aortic narrowing at the isthmus. It may occur in association with other defects, which requires a discussion regarding the choice of optimal therapy. Critical aortic coarctation with aortic hypoplasia and so-called bovine trunk anatomy is one of the more challenging forms of this defect, characterized by a common origin of the brachiocephalic trunk and the left common carotid artery, which form a common vessel extending as a direct continuation of the ascending aorta. Therapeutic decisions are made depending on the distance between the ascending aorta and the isthmus and descending aorta, taking into account the typical management of hypoplastic aortic arch. Material and methods. The clinical presentation in the neonatal period includes weak or absent femoral pulse, pallor, apathy, dyspnea and signs of systemic hypoperfusion with progressive lung edema and acidosis. The diagnosis is mostly based on echocardiography while magnetic resonance imaging or computed tomography allow detailed imaging of the collateral vessels. The most important diagnostic issues are the anatomy of the defect, severity of concomitant aortic isthmus narrowing, and its hemodynamic effect. The medical management is directed at maintaining patency of the ductus arteriosus with prostaglandin E1 infusion and an appropriate balance between peripheral systemic and pulmonary resistance. The recommended treatment of choice is an early surgical correction of the aortic arch defect. The aortic arch reconstruction method with ductus-dependent systemic flow preservation implies resection of the coarctation along with the isthmus narrowing and proximal end-to-side anastomosis, with reconstruction of the inflow to the left subclavian artery using a hypoplastic distal segment of the aortic arch. The operation is performed by the left posterolateral thoracotomy without using extracorporeal circulation. Conclusions. The prerequisite for selecting a neonate for the proposed procedure is a detailed assessment of aortic arch anatomy, with particular attention to the measurement of the distance between the ascending aorta and the area where the ductus arteriosus connects to the descending aorta. The major advantage of this technique is the ability to perform an off-pump procedure via the lateral access, using only healthy native patient tissues for aortic flow restoration.

The Performance Assessment of a Precast, Panel-Segmented Arch Bridge with Outriggers

Stone arch bridges, which are globally implemented, are advantageous with respect to material strength and durability. To minimize environmental damage from arch bridges, a structurally stable scheme that can resist variable external loads is required. This paper proposes a segmented precast arch bridge with outriggers to resist both the tensile force applied on the precast panels and the compressive force during construction and use. To assess the structural behavior and safety of the proposed arch bridge, a three-dimensional (3D) nonlinear structural analysis was conducted, considering the construction step and rise ratio of the arch bridge. The structural analysis of the proposed arch bridge revealed that its maximum horizontal and vertical displacements occurred at the support of the precast panel and the arch crown in a self-weight state. However, because of the compressive resistance characteristics of the outriggers connected to the precast panels, the structure demonstrated an effective performance in the self-weight state. With an increase in the construction steps, and the final completion of proposed arch bridge via installation of the precast arch segments and earthwork for the precast arch bridge with outriggers, the deformation of the arch members was mitigated, and the relative difference between the stress distributions of the members reduced. Hence, the arch bridge achieved structural stability. Based on the thrust line analysis results of the arch bridge with respect to the construction step using 3D structural analysis results, the thrust line was formed outside the precast panel at the arch crown and support, so was attributed to the behavior of the arch bridge in a self-weight state. The thrust line was found to act within the precast panel depending on the construction step. Analysis results confirmed that the behavior of the precast panel arch bridge with the proposed outrigger was stable and structurally effective.

Out-Of-Plane Buckling of Steel I-Section Circular Arches

Circular arches subjected to in plane loading are restrained with discrete lateral bracing to improve their out of plane stabilities in many cases. The arch segment between two adjacent bracing may buckle out of plane if the effective length of the arch segment is sufficiently large. But replacing the flat web with corrugated web will increase the out of plane stability of the circular arches. This paper investigates the out of plane elastic buckling of steel I-section circular arches with flat web and sinusoidal corrugated web. This study considers pin-ended and fixed circular steel arches with a sinusoidal corrugated web under a uniform radial load or uniform vertical load to elucidate numerically their different failure modes. Arches subjected to in-plane loading may suddenly deflect laterally and twist out of loading plane and fail in an out-of-plane elastic buckling mode.