Dunbar (Or Median Arcuate Ligament) Syndrome: A Case Series

Dunbar syndrome (DS) (or Median arcuate ligament syndrome) is a rare entity of the vascular compression syndrome, where there is focal proximal coeliac axis compression by Median arcuate ligament (MAL). It results in an insufficient supply of blood to the respective organs of the gastrointestinal tract (GIT). Multi-detector computed tomography (MDCT) is a very convenient non-invasive modality in diagnosing this condition and helpful in distinguishing it from other conditions, such as atherosclerotic disease. DS can further be treated disorder surgically by relieving the compression and sometimes may need vascular reconstruction. We present five cases of the DS.

The vasculature of the stomach and intestinal tract during compression stenosis of the celiac axis

At the current moment, there is no single approach regarding diagnostics and after-treatment of compression stenosis of the celiac axis. This work aims to study the state of the vasculature of the stomach and intestinal tract during compression stenosis of the celiac axis. Compression stenosis of the celiac axis is a disease caused by extravasal pressure of the celiac axis of the abdominal aorta applied by the arcuate ligament of the diaphragm, diaphragmatic peduncle, or neurophibromatic tissue of celiac plexus. It presents in chronic abdominal pain, dyspeptic events, and neurovegetative disorders. This work aims to study the state of the vasculature of the stomach and intestinal tract during compression stenosis of the celiac axis. Materials and methods. Intraorgan vasculature has been studied – 18 specimens of stomachs and intestinal tracts, gathered during autopsies of dead bodies with compression stenosis of the celiac axis. Autopsie material has been studied sensu L. Reiner. Research has been conducted with angiology, roentgenologic and histologic methods. To achieve the set goal a universal method has been developed, based on classical impregnation methods: intravascular – Ranvier-Goyer, and immersional – Belschowsky-Gros. Results. The conducted research has allowed locating significant changes of histostructure of microcirculation vessels’ vascular wall: wall shredding, edema of basal membrane, swelling of perivascular connective tissue. Overall the stomach and intestinal tract looked paralytically dilated. The most prominent morphologic changes of microvasculature have been revealed in the pyloric part of the stomach and first intestinal segment of dodecadactylon. In addition to diffuse atrophic changes of the stomach lining and intestinal lining, observed during stenosis of the celiac axis, these changes take the form of helcoid process in separate parts of it. As a result, the conducted research has allowed exposing prominent changes of histostructure of vascular walls of stomach and intestines during compression stenosis of the celiac axis.

Design and Fabrication of Complex-Shaped Ceramic Bone Implants via 3D Printing Based on Laser Stereolithography

3D printing allows the fabrication of ceramic implants, making a personalized approach to patients’ treatment a reality. In this work, we have tested the applicability of the Function Representation (FRep) method for geometric simulation of implants with complex cellular microstructure. For this study, we have built several parametric 3D models of 4 mm diameter cylindrical bone implant specimens of four different types of cellular structure. The 9.5 mm long implants are designed to fill hole defects in the trabecular bone. Specimens of designed ceramic implants were fabricated at a Ceramaker 900 stereolithographic 3D printer, using a commercial 3D Mix alumina (Al2O3) ceramic paste. Then, a single-axis compression test was performed on fabricated specimens. According to the test results, the maximum load for tested specimens constituted from 93.0 to 817.5 N, depending on the size of the unit cell and the thickness of the ribs. This demonstrates the possibility of fabricating implants for a wide range of loads, making the choice of the right structure for each patient much easier.

Hot Processing of Powder Metallurgy and Wrought Ti-6Al-4V Alloy with Large Total Deformation: Physical Modeling and Verification by Rolling

The influence of the total deformation amount on the microstructure and selected properties of Ti-6Al-4V alloy was determined in this study. Multi-axis compression tests on the MaxStrain module were performed to obtain large strains. Starting material for the research was obtained by the powder metallurgy (PM) route. Plastically processed cast alloy of the same chemical composition as PM alloy was also tested as reference material. The tests were performed with the cooling of samples between successive deformation stages, which allowed for the simulation of the temperature drop occurring during industrial processes. The multi-stage deformation ability of PM Ti-6Al-4V alloy without decohesion was confirmed. It has also been shown that the application of increasing total strain at a controlled temperature changes the samples resulting in the refinement of the microstructure and leads to the fragmentation of lamellae. The results obtained from MaxStrain tests were verified by multi-stage hot-rolling tests. Defect-free products were obtained, whose good quality was confirmed by the microstructural observations as well as by the investigations of their properties. The results of the rolling tests confirmed the possibility of hot processing of Ti-6Al-4V alloy compacts in industrial conditions, applying large total strain.

Spontaneous Retroperitoneal Hemorrhage Secondary to Chronic Celiac Axis Compression Treated with Embolization Utilizing Cone Beam CT

Median arcuate ligament syndrome (MALS) is a rare and often misdiagnosed vascular pathology. In this paper, we discuss a 51-year-old female with MALS presenting with hypotension due to retroperitoneal hemorrhage. Currently, there is no consensus regarding the optimal treatment approach for such patients. This case report demonstrates the utility of conventional mesenteric angiography, cone beam CT with 3D reconstruction, and selective mesenteric transarterial embolization as an effective treatment approach for patients with spontaneous aneurysm rupture in MALS.

Surface Hardening of AlMg5Si2Mn Alloy through Multi-Axis Compression Using Max Strain

Severe plastic deformation (SPD) processing techniques are applied to polycrystalline metallic materials in order to refine the grain size up to the sub-micrometre or nanometer level. The decrease in grain size to a sub-micrometre level is related to beneficial mechanical properties such as very high strength. The most widely applied SPD method is equal-channel angular pressing (ECAP). In distinction to traditional cold rolling or drawing, SPD techniques frequently employ cyclic strain paths that can lead to an essentially unchanged shape of the material sample after processing. In this paper, multi-axis compression is applied by using the MAXStrain (R) unit to impose cyclic compression in two mutually orthogonal directions. This study is aimed to realize the evolution of microstructure and mechanical properties of AlMg5Si2Mn aluminium cast alloy subjected to multi-axis compression. The microstructure of the alloy in the as-cast and as deformed state was characterized by light and scanning electron microscopy. The results reveal that multi-axis compression has a great influence on the evolution of microstructure and final mechanical properties. The enhanced mechanical properties are associated with the progressive formation of refined microstructure which is heterogeneously distributed across the sample.