Technical and clinical success after endovascular therapy for chronic type B aortic dissections

ObjectiveTo analyze early technical success and late clinical success after endovascular entry sealing for chronic type B dissection with special emphasis on reintervention, false lumen thrombosis, and aortic remodeling.MethodsRetrospective analysis of a prospective database. From September 1999 to January 2011, 19 patients with chronic type B dissections were treated by endovascular entry sealing. Median age was 60 years. Median time between onset of acute dissection and surgical intervention was 36 (1 to 60) months. Median follow-up was 13 months (1 to 124).ResultsThe endografts used were: Medtronic Captivia (5), Medtronic Valiant (5), Gore TAG (6), Gore C-TAG (2), and Cook Zenith (1). In four patients, revascularization of the left subclavian artery was performed prior to entry sealing. Primary technical success rate (entry sealing, absence of type I leak) was 18/19 (94.7%). In-hospital mortality was 0%. Spinal cord injury with persistent paraplegia occurred in 1/19 (5.2%) patients. After a maximal follow-up of 124 months, reinterventions in 9/19 (47.3%) were necessary: distal/proximal extension of stent graft (8), replacement of the aortic arch due to retrograde dissection (1), and open infrarenal aneurysm repair (1). During follow-up, none of the patients died due to stent-related complications.ConclusionEndovascular treatment (EVT) in chronic type B dissections has a high technical success rate and low mortality/morbidity. However reintervention rates are not negligible which might reduce the clinical success of EVT. Future investigations should aim at identifying patients who benefit from EVT at better defining the timing of EVT and at determining if entry sealing alone is sufficient

Effect of statin therapy on serum activity of proteinases and cytokines in patients with abdominal aortic aneurysm

Bernd Muehling1, Alexander Oberhuber1, Hubert Schelzig1, Gisela Bischoff1, Nikolaus Marx2, Ludger Sunder-Plassmann1, Karl H Orend11Department of Thoracic and Vascular surgery; 2Department of Internal Medicine, University of Ulm, Ulm, GermanyBackground and aims: Metalloproteinases (MMPs) are considered to be key enzymes in the pathogenesis of abdominal aortic aneurysms (AAA), with elevated levels in diseased aorta and in patient sera. Statins seem to exert an inhibitory effect on MMP activity in the aortic wall. No data exist on the effect of statins on serum activity of MMPs and inflammatory cytokines (interleukins, IL).Methods: The serum activities of MMP2 and MMP9, osteoprotegerin (OPG), and IL6 and IL10 in 63 patients undergoing elective infrarenal aneurysm repair were measured on the day before surgery. Levels were correlated to statin therapy and aneurysm diameter.Results: There was no significant difference between the two groups in the activity of circulating levels of MMP2/9, OPG, and IL6/10 in patients with infrarenal aortic aneurysm. IL6 levels in patients with AAA larger than 6 cm were significantly elevated; differences in serum activities of MMP2/9, OPG, and IL10 were not related to AAA diameter.Conclusion: Serum activities of MMP2/9, OPG, and IL6/10 are not correlated to statin therapy; IL6 levels are higher in patients with large aneurysms. Hence the effect of statin therapy in the treatment of aneurismal disease remains to be elucidated.Keywords: biomarkers, aneurismal disease, statin therap

Influence of operating conditions on loads and fatigue strength in a rod column of PCP

Актуальность исследования обусловлена необходимостью повышения надежности и ресурса штанговых винтовых насосных установок, используемых для осложненных условий эксплуатации скважин, поскольку они имеют низкую надежность в сравнении с электроцентробежными насосами, что ограничивает их применение. Винтовые насосные установки используются в скважинных условиях, характеризующихся высокой вязкостью откачиваемой пластовой жидкости (более 30 мПа·с) и высоким содержанием механических примесей в ней (коэффициент взвешенных частиц более 500 мг/литр). Опыт эксплуатации винтовых насосных установок показывает, что надежность насосных установок зависит в первую очередь от надежности штанговой колонны. Помимо крутящей нагрузки, необходимой для передачи вращения от асинхронного двигателя к винтовому насосу, погруженному на расстояние более одного километра от устья скважины, штанговая колонна испытывает растягивающие нагрузки от веса насосных штанг и осевой нагрузки винтового насоса, а также изгибающие нагрузки, вызванные пространственным искривлением ствола скважины. Цель исследования заключается в оценке влияния различных факторов эксплуатации на нагрузки, действующие на колонну насосных штанг в процессе эксплуатации скважины, а также на усталостную прочность насосных штанг. Методы: методика расчета штанговых колонн винтовых насосных установок с учетом осевых, крутящих и изгибающих нагрузок, учитывающая процессы трения штанговой колонны о насосно-компрессорные трубы, возникающие от Эйлеровых сил прижатия штанг к трубам из-за пространственного искривления ствола скважины, реализованная на языке программирования Python; факторный анализ нагрузок, действующих на привод насосной установки. Результаты. С помощью программного обеспечения, реализованного на языке программирования Python, произведены расчеты, показавшие влияние различных осложняющих факторов на величину нагрузок на штанговую колонну. Показано влияние нагрузок вследствие воздействия геолого-технических и технологических параметров на усталостную прочность насосных штанг. Разработанное программное обеспечение позволяет учесть степень влияния осложняющих факторов на стадии подбора компоновки винтовой насосной установки, а также в процессе эксплуатации и тем самым существенно увеличить межремонтный период работы штанговых винтовых насосных установок.The relevance of the research is caused by the need to increase the reliability and resource of progressing cavity pumps, used in complicated well operating conditions, since they have low reliability in comparison with electrical submersible pumps, that limits their application. Progressing cavity pumps are used in well conditions characterized by a high viscosity of the pumped fluid (more than 30 mPa·s) and a high content of solid particles in it (the coefficient of suspended particles is more than 500 mg/liter). Experience in operating progressing cavity pumps shows that the reliability of pumping installations depends primarily on the reliability of the rod string. In addition to the torque load required to transfer the rotation from the induction motor to the screw pump, immersed on more than one kilometer from the wellhead, the sucker string experiences tensile loads from the weight of the pump rods and the axial load of the screw pump, as well as bending loads caused by the spatial curvature of the wellbore. The paper proposes the implementation of methodology for calculating the sucker rod columns of progressing cavity pumps with regard to axial, torsional and bending loads in the Python programming language. The proposed method for calculating the rod column of a screw pumping unit takes into account the rod column friction on tubing pipes arising from the Eulerian forces pressing the rods to the pipes due to the spatial curvature of the wellbore. Using software implemented in the python programming language, the authors have made calculations that showed the influence of various complicating factors on the magnitude of the loads on the rod string. As a result of calculations of the fatigue strength of the pump rods, cyclic loads during the rotation of the rods in the local sections of the local curvature of the wellbore was shown. The developed software allows you to take into account the degree of influence of complicated well operating conditions at the design stage, and thus, significantly increase the turnaround time of the rod screw pumping units. The main aim of the research is to assess the influence of various operating factors on the loads acting on the string of pump rods during well operation, as well as on the fatigue strength of the pump rods. Methods. Using software implemented in the python programming language, calculations were performed that showed the influence of various complicating factors on the magnitude of the loads on the rod string. The paper demonstrated the effect of loads on the fatigue strength of sucker rods caused by cyclic loads during rotation of the rods in the areas of local curvature of the wellbore. The developed software allows taking into account the degree of influence of complicating factors at the stage of selecting the layout of a PCP, as well as during operation, and thereby significantly increasing the overhaul period of PCP operation