[Factors with Impact on the Outcome after Surgical Interventions for Abdominal Aortic Aneurysms]. / Einflussfaktoren auf das Outcome nach operativer Therapie abdominaler Aortenaneurysmen.

BACKGROUND: Since its introduction, endovascular aortic aneurysm repair (EVAR) has proved as a favourable alternative to open surgery (OR) in the treatment of abdominal aortic aneurysms (AAA). Long-term outcomes of EVAR and OR are similar while complications are more likely to develop after EVAR. Risk factors for mortality and complications after AAA surgery have been identified, however, a general overview is lacking. METHODS: In a systematic literature search via PubMed, we identified publications on the topic of factors influencing the postoperative outcome of AAA surgery. RESULTS: Patient age > 80 years was found to be a significant predictor of increased mortality, whereas the influence of aneurysm diameter on OR remains moderate, the outcome of EVAR performed in AAA > 6.5 cm is associated with higher mortality and increased complication rates. In patients with ruptured AAA the postoperative mortality is higher than in those with intact aneurysms. Preoperative haemodynamic instability has a crucial influence on patient outcome and is strongly associated with intra- and postoperative death. The prevalence of cardiovascular co-morbidity leads to increased long-term mortality. Preoperative statin medication was found to reduce short- and long-term mortality by the factor of 0.5. Patients suffering from chronic lung disease such as COPD and patients with a deficiency in renal function are more likely to experience adverse events including death. While the prevalence of cerebrovascular disease is associated with an increase in mortality by the factor of 1.5 or higher, findings on patients with diabetes mellitus are conflicting with no definite point to be made. CONCLUSION: Several factors influencing the outcome of surgery for AAA present a condition developed from factors involved in the pathogenesis of AAA. The impact of non-disease factors like patient age and aneurysm diameter can be reduced by the means of population-wide screening for AAA, and optimised treatment of disease-related risk factors can reduce mortality. Studies comparing the outcome of EVAR and OR in patients with risk factors should be performed to support decision-making about the ideal individual treatment.

Orientation relations during the α-ω phase transition of zirconium: in situ texture observations at high pressure and temperature.

Transition metals Ti, Zr, and Hf have a hexagonal close-packed structure (α) at ambient conditions, but undergo phase transformations with increasing temperature and pressure. Of particular significance is the high-pressure hexagonal ω phase which is brittle compared to the α phase. There has been a long debate about transformation mechanisms and orientation relations between the two crystal structures. Here we present the first high pressure experiments with in situ synchrotron x-ray diffraction texture studies on polycrystalline aggregates. We follow crystal orientation changes in Zr, confirming the original suggestion by Silcock for an α→ω martensitic transition for Ti, with (0001)(α)||(1120)(ω), and a remarkable orientation memory when ω reverts back to α.

[Surgery of the renal artery: the role of the vascular surgeon in current therapy]. / Nierenarterienchirurgie: Was bleibt für den Gefäßchirurgen übrig?

INTRODUCTION: After the establishment of the different operation procedures, in the 1970s and 1980s, PTA and stenting were favoured in the follow-ing decade. METHODS: Current operative, interventional and endovascular procedures are described and the results of several multicentre studies are discussed. RESULTS AND CONCLUSIONS: Vascular surgery was required only for treatment of complications and for the combination of treatment of the renal artery together with aortoiliac reconstruction. Numerous studies lead one to believe that medical treatment alone was justified in renal artery stenoses. Nevertheless, all these studies can be criticised, therefore, treatment of the renal artery is still required. Evidence-based data should be generated for optimal treatment of renal artery stenoses.

Nanostructure of calcium silicate hydrates in cements.

Calcium silicate hydrate (CSH) is the major volume phase in the matrix of Portland cement concrete. Total x-ray scattering measurements with synchrotron x rays on synthetic CSH(I) shows nanocrystalline ordering with a particle diameter of 3.5(5) nm, similar to a size-broadened 1.1 nm tobermorite crystal structure. The CSH component in hydrated tricalcium silicate is found to be similar to CSH(I). Only a slight bend and additional disorder within the CaO sheets is required to explain its nanocrystalline structure.

[Erosive bleeding of the cystic artery into a cholecysto-colic fistula as a rare cause of acute gastrointestinal bleeding]. / Arrosionsblutung der A. cystica bei cholezysto-kolischer Fistel als seltene Ursache einer akuten gastrointestinalen Blutung.

Acute gastrointestinal bleeding is one of the most frequent medical emergencies. The most common causes are inflammations, ulcers, neoplasms and angiodysplasias. They can usually be diagnosed and treated via endoscopy, but less frequent causes, which require increased diagnostic and therapeutic efforts, must also be considered. We present the case of a 53-year-old patient with gastrointestinal bleeding. He was diagnosed with transverse colon bleeding in another hospital. A bleeding diverticulum was assumed. Following admission to our hospital, a bleeding through the ampulla of Vater was discovered via gastroscopy. The CT scan showed arterial bleeding into the gallbladder. We immediately performed a laparotomy and found a cholecysto-colic fistula as the cause of the bleeding into the transverse colon.

The relationship between volume and outcome following elective open repair of abdominal aortic aneurysms (AAA) in 131 German hospitals.

OBJECTIVES: Several studies indicate that high-volume hospitals have better results in open repair of unruptured abdominal aortic aneurysms (AAA). Up to now no studies had addressed this question in German hospitals. DESIGN: Post-hoc-analysis from a prospective physician-led registry. MATERIAL AND METHODS: Since 1999, the German Society for Vascular Surgery has conducted a prospective registry for open and endovascular repair of AAAs. This study includes 131 hospitals who conducted n=10163 elective open repairs for unruptured AAA between 1999 to 2004. All perioperative variables including annual volume as a continuous variable were analysed in a step-wise logistic regression model. In order to define a threshold annual volume an additional logistic regression analysis was performed by use of annual volume groups (0-9, 10-19, 20-29, 30-39, 40-49, 50 or more). The relationship between annual volume and further outcome parameters (length of procedure, blood transfusion, length of stay) were also analyzed. RESULTS: The overall mortality rate was 3.2%. The stepwise logistic regression model identified the following predictors of an increased perioperative mortality: age (OR 1.084, 95% CI 1.066-1.102), AAA diameter (OR 1.008, 95% CI 1.001-1.016), length of procedure (OR 1.008, 95% CI 1.006-1.009), ASA-Score (OR 2.636, 95% CI 2.129-3.264), suprarenal clamping (OR 1.447, 95% CI 1.008-2,078), blood transfusion (OR 1.786, 95% CI 1.268-2.514). Annual volume was moderately predictive (OR 1.003, 95% CI 1-1.006) but failed to reach statistical significance (p=0.07). The analysis of volume groups identified a significantly higher risk for hospitals with an annual volume of 1-9 AAA-repairs by comparison to hospitals with an annual volume of 50 or more AAA-repairs (OR 1.903, 95% CI 1.124-3.222). Operations at low volume hospitals were also longer (p<0.001), with an extended postoperative stay (p<0.001) and a higher transfusion rate (p<0.001). CONCLUSIONS: Patient's age, ASA classification, AAA diameter, length of procedure, suprarenal clamping and blood transfusion are predictive variables for an increased perioperative mortality in elective open AAA repair. Mortality is also increased by a low annual volume. Further studies are needed to examine whether these data are applicable to all German hospitals.

Certification of vascular centers - a project of the German Society for Vascular Surgery.

OBJECTIVES: Due to the progress vascular medicine has made in conventional vascular surgery, endovascular procedures, and conservative therapy close, interdisciplinary cooperation is required. In order to assure the contextual and structural quality of vascular centers, the German Society for Vascular Surgery established a list of criteria for certification of each interdisciplinary vascular center. MATERIAL AND METHODS: Between July 2002 and December 2005, 77 centers have submitted a written application and have been audited by the commission for quality assurance of the German Society for Vascular Surgery, 59 vascular centers were certified for a period of 3 years with one center in each in Austria and in Switzerland, 13 centers were not certified (16.8%), and the applications of 5 centers are still pending. This analysis is based on 57 German certified vascular centers. RESULTS: Each center treats a median of 1149 inpatients (11% of these are emergency admissions) and 2,159 outpatients per year. Sixty percent of the patients treated have an arterial disease. All centers have vascular surgery and radiology departments. In 11 out of 57 centers, angiology services are offered in cooperation with affiliated physicians. Each vascular center has an average of 4.2 vascular surgeons, 3 radiologists and 1 angiologist. All centers offer radiological and ultrasound diagnostics (CT angiography in 100%, MRT in 95%, duplex sonography in 100%). Each clinic executes a median of 521 (233-1436) arterial operations and 263 (37-1055) arterial interventions. In addition, they execute varicose surgeries (n=217), shunt applications/revisions (n=58), minor amputations (n=57) and major amputations (n=42). They conduct 338 (92-3606) conservative therapies per year (POAD, diabetic foot, phlebothrombosis, chronic venous insufficiency). CONCLUSIONS: The certification of interdisciplinary vascular centers is a new approach to assure the contextual and structural quality of interdisciplinary vascular centers.

[Results of the certification of vascular centers by the German Society for Vascular Surgery]. / Ergebnisse der Zertifizierung von Gefässzentren durch die Deutsche Gesellschaft für Gefässchirurgie.

INTRODUCTION: Advances in conventional vascular surgery, endovascular procedures and conservative treatment require close interdisciplinary cooperation. The term Vascular Centre indicates to patients and referring doctors optimal professional and organisational competence. METHODS: 73 applications by vascular centres for certification were made between June 2002 and December 2005, of which after audit 54 were successful for three years, including one centre each in Austria and Switzerland. 13 centres were not accepted and six are still under consideration. This analysis is based on the data of 52 certified centres in the Federal Republic of Germany. RESULTS: A mean of 1149 patients were hospitalized in these centres per year (12 % emergency admissions) and 2159 patients per year were treated as outpatients, 60 % with arterial vascular disease. All centres have vascular surgery and radiology department, 10 of the 52 centres cooperate with specialists in private practice to provide an angiology service. A mean of 460 arterial vascular operations and 239 arterial interventional procedures were performed at each centre annually. In addition there were operations for varicose veins (n = 217), shunt operations (n = 58) and major amputations (n = 42). Inpatient or outpatient conservative treatment (for peripheral vascular disease, diabetic foot syndrome, phlebothrombosis or chronic venous insufficiency) was given to a mean of 338 patients annually. CONCLUSIONS: Certification of interdisciplinary vascular centres provides structural and medical data and the beginnings of comparing such centres. A future task will be standardization of documentation and continuing assessment of the quality of results.

Deformation experiments in the diamond-anvil cell: texture in copper to 30 GPa.

The combination of the diamond-anvil cell, synchrotron x-ray diffraction in radial geometry and simultaneous Rietveld refinement with texture analysis allows us to quantitatively investigate the plastic deformation behaviour of materials at very high pressures. Our study of copper to 30 GPa shows in ideal experimental geometry a [110] fibre texture component, as is typical for axial compression of soft face centred cubic metals. Locally a plane strain texture develops which is energetically favoured (curling). A transition from compressional to plane strain/pure shear texture can be monitored by analysing individual images taken at different positions in the diamond cell.

Deformation textures produced in diamond anvil experiments, analysed in radial diffraction geometry.

Diamond anvil cells may not only impose pressure upon a sample but also a compressive stress that produces elastic and plastic deformation of polycrystalline samples. The plastic deformation may result in texture development if the material deforms by slip or mechanical twinning, or if grains have a non-equiaxed shape. In radial diffraction geometry, texture is revealed by variation of intensity along Debye rings relative to the compression direction. Diffraction images (obtained by CCD or image plate) can be used to extract quantitative texture information. Currently the most elegant and powerful method is a modified Rietveld technique as implemented in the software package MAUD. From texture data one can evaluate the homogeneity of strain in a diamond anvil cell, the strain magnitude and deformation mechanisms, the latter by comparing observed texture patterns with results from polycrystal plasticity simulations. Some examples such as olivine, magnesiowuestite, MgSiO(3) perovskite and ε-iron are discussed.

Crystallographic texture for tube and plate of the superelastic/shape-memory alloy Nitinol used for endovascular stents.

The superelastic/shape-memory material, Nitinol, an approximately equiatomic alloy of Ni and Ti, is rapidly becoming one of the most important metallic implant materials in the biomedical industry, in particular for the manufacture of endovascular stents. As such stents are invariably laser-machined from Nitinol tubes or sheets rolled into tubes, it is important to fully understand the physical phenomena that may affect the mechanical behavior of this material. With tubing and plate, one major issue is crystallographic texture, which can play a key role in influencing the mechanical properties of Nitinol. In this article, we present a study on how geometry and heat treatment can affect the texture of Nitinol, with specific quantification of the texture of Nitinol tube used for the production of endovascular stents.

[Malignant gastrointestinal stromal tumor (GIST) of the papilla vateri. A rare tumor entity]. / Maligner gastrointestinaler Stromatumor (GIST) der Papilla vateri. Eine seltene Tumorentität.

We present the case report of a 68-year-old female patient who had a malignant gastrointestinal stromal tumor of the papilla of Vater. The abdominal CT showed a coin-shaped lesion in the liver (segment VIII). Intraoperative rapid histological examination detected an old parasitic hepatic cyst. To exclude metastasis, we performed duodenopancreatectomy with curative intention. The postoperative course was without complications and neither chemotherapy nor other adjunct treatment was necessary. Because of heterogeneity, the different localization, and in this case the rare localization, surgery of gastrointestinal stromal tumors is difficult. However, we adhered to oncological and therapeutic standards of surgery for papillary carcinoma. This case is discussed based on a review of the literature. However, until now there has been no case report of gastrointestinal stromal tumor of the papilla of Vater in the literature.