Three-dimensional imaging core laboratory of the endovascular aneurysm repair trials: validation of methodology

OBJECTIVE: The aim of this study was to establish and validate a three-dimensional imaging protocol for the assessment of Computed Tomography (CT) scans of abdominal aortic aneurysms in UK EVAR trials patients. Quality control and repeatability of anatomical measurements is important for the validity of any core laboratory. METHODS: Three different observers performed anatomical measurements on 50 preoperative CT scans of aortic aneurysms using the Vitrea 2 three-dimensional post-imaging software in a core laboratory setting. We assessed the accuracy of intra and inter observer repeatability of measurements, the time required for collection of measurements, 3 different levels of automation and 3 different automated criteria for measurement of neck length. RESULTS: None of the automated neck length measurements demonstrated sufficient accuracy and it was necessary to perform checking of the important automated landmarks. Good intra and limited inter observer agreement were achieved with three-dimensional assessment. Complete assessment of the aneurysm and iliacs took an average (SD) of 17.2 (4.1) minutes. CONCLUSIONS: Aortic aneurysm anatomy can be assessed reliably and quickly using three-dimensional assessment but for scans of limited quality, manual checking of important landmarks remains necessary. Using a set protocol, agreement between observers is satisfactory but not as good as within observers.

Endovascular repair of abdominal aortic aneurysms: only a mechanical solution for a biological problem?

Endovascular aneurysm repair has matured significantly over the last 20 years and is becoming increasingly popular as a minimally invasive treatment option for patients with abdominal aortic aneurysms (AAA). Long-term durability of this fascinating treatment, however, is in doubt as continuing aneurysmal degeneration of the aortoiliac graft attachment zones is clearly associated with late adverse sequelae. In recent years, our growing understanding of the physiopathology of AAA formation has facilitated scrutiny of various potential drug treatment concepts. In this article we review the mechanical and biological challenges associated with endovascular treatment of infrarenal AAAs and discuss potential approaches to ongoing aneurysmal degeneration, which hampers long-term outcomes of this minimally invasive therapy.

Retrograde ascending aortic dissection during or after thoracic aortic stent graft placement: insight from the European registry on endovascular aortic repair complications

BACKGROUND: Single-center reports have identified retrograde ascending aortic dissection (rAAD) as a potentially lethal complication of thoracic endovascular aortic repair (TEVAR). METHODS AND RESULTS: Between 1995 and 2008, 28 centers participating in the European Registry on Endovascular Aortic Repair Complications reported a total of 63 rAAD cases (incidence, 1.33%; 95% CI, 0.75 to 2.40). Eighty-one percent of patients underwent TEVAR for acute (n=26, 54%) or chronic type B dissection (n=13, 27%). Stent grafts with proximal bare springs were used in majority of patients (83%). Only 7 (15%) patients had intraoperative rAAD, with the remaining occurring during the index hospitalization (n=10, 21%) and during follow-up (n=31, 64%). Presenting symptoms included acute chest pain (n=16, 33%), syncope (n=12, 25%), and sudden death (n=9, 19%) whereas one fourth of patients were asymptomatic (n=12, 25%). Most patients underwent emergency (n=25) or elective (n=5) surgical repair. Outcome was fatal in 20 of 48 patients (42%). Causes of rAAD included the stent graft itself (60%), manipulation of guide wires/sheaths (15%), and progression of underlying aortic disease (15%). CONCLUSIONS: The incidence of rAAD was low (1.33%) in the present analysis with high mortality (42%). Patients undergoing TEVAR for type B dissection appeared to be most prone for the occurrence of rAAD. This complication occurred not only during the index hospitalization but after discharge up to 1050 days after TEVAR. Importantly, the majority of rAAD cases were associated with the use of proximal bare spring stent grafts with direct evidence of stent graft-induced injury at surgery or necropsy in half of the patients.

Clinical experience with the use of bivalirudin in a large population undergoing endovascular abdominal aortic aneurysm repair

PURPOSE: To retrospectively evaluate the safety and effectiveness of the use of bivalirudin, a direct thrombin antagonist, compared with unfractionated heparin in endovascular aneurysm repair (EVAR). MATERIALS AND METHODS: Between March 1994 and September 2007, 740 consecutive patients (mean age, 75.7 y +/- 7.7; 69 women) underwent elective EVAR for infrarenal abdominal aortic aneurysm. Bivalirudin was used in 98 of these 740 (13.2%) and unfractioned heparin was used in the other 642 (86.8%). Complications were classified according to the Society of Vascular Surgery/International Society for Cardiovascular Surgery criteria. Major bleeding was defined as clinically overt blood loss resulting in a decrease of hemoglobin of more than 3 g/dL, any decrease in hemoglobin of more than 4 g/dL, transfusion of 2 U or more of red blood cells, or intracranial or retroperitoneal hemorrhage. RESULTS: Grade 1 major complications were observed in 161 of 642 patients (25.2%) in the heparin group and 12 of 98 patients (12.2%) in the bivalirudin group (P = .0046), whereas the incidences of grade 3 major complications were not significantly different between groups (P = .57). The rate of total complications was higher in the heparin group than in the bivalirudin group (247 of 642 [38.5%] vs 21 of 98 [21.4%]; P = .001). Major bleeding occurred in 10 of 98 patients (10.2%) receiving bivalirudin and in 91 of 642 patients (14.2%) receiving heparin (P = .34). One of 21 major complications (4.76%) in the bivalirudin group and 12 of 247 major complications (4.86%) in the heparin group were attributable to thrombosis (P = 1.0). CONCLUSIONS: Bivalirudin is a safe and feasible alternative to unfractionated heparin in patients undergoing EVAR.

JExample: Exploiting Dependencies Between Tests to Improve Defect Localization

To quickly localize defects, we want our attention to be focussed on relevant failing tests. We propose to improve defect localization by exploiting dependencies between tests, using a JUnit extension called JExample. In a case study, a monolithic white-box test suite for a complex algorithm is refactored into two traditional JUnit style tests and to JExample. Of the three refactorings, JExample reports five times fewer defect locations and slightly better performance (-8-12\%), while having similar maintenance characteristics. Compared to the original implementation, JExample greatly improves maintainability due the improved factorization following the accepted test quality guidelines. As such, JExample combines the benefits of test chains with test quality aspects of JUnit style testing.

Repair - Beispiel: Mobile mit Halogenleuchten

Das RTeJournal möchte in seiner Rubrik:“ Repair“, Berichte aufnehmen, in denen die Reparatur oder der Ersatz von Bauteilen durch Additive Manufacturing (AM) Lösungen aufgenommen wird. Einmal als Anregung sich damit auseinander zu setzen und gleichzeitig auch als Dienstleistung beim Bedarf von Reparaturen. Es würde uns freuen, wenn Sie uns Beispiele mit einem kleinen Reparaturbericht zusenden könnten, die zum Einsatz von Additive Manufacturing führten. Email: eich@fh-aachen.de

Optical properties and defect structure of Sr2+ co-doped LaBr3:5%Ce scintillation crystals

Sr2+ co-doped LaBr3:5%Ce scintillators show a record low energy resolution of 2% at 662 keV and a considerably better proportional response compared to standard LaBr3:5%Ce. This paper reports on the optical properties and time response of Sr co-doped LaBr3:5%Ce. Multiple excitation and emission bands were observed in X-ray and optically excited luminescence measurements. Those bands are ascribed to three different Ce3+ sites. The first is the unperturbed site with the same luminescence properties as those of standard LaBr3:Ce. The other two are perturbed sites with red-shifted 4f-5d1 Ce3+ excitation and emission bands, longer Ce3+ decay times, and smaller Stokes shifts. The lowering of the lowest 5d level of Ce3+ was ascribed to larger crystal field interactions at the perturbed sites. Two types of point defects in the LaBr3 matrix were proposed to explain the observed results. No Ce4+ ions were detected in Sr co-doped LaBr3:5%Ce by diffuse reflectance measurements.

Effect of lateral meniscectomy and osteochondral grafting of a lateral femoral condylar defect on contact mechanics: a cadaveric study in dogs

BACKGROUND Osteochondral autograft transfer (OAT) aims at restoring normal articular cartilage surface geometry and articular contact mechanics. To date, no studies have evaluated the contact mechanics of the canine stifle following OAT. Additionally, there are no studies that evaluated the role of the meniscus in contact mechanics following OAT in human or canine femorotibial joints. The objective of this study was to measure the changes in femorotibial contact areas (CA), mean contact pressure (MCP) and peak contact pressure (PCP) before and after osteochondral autograft transplantation (OAT) of a simulated lateral femoral condylar cartilage defect with an intact lateral meniscus and following lateral meniscectomy. RESULTS With an intact lateral meniscus, creation of an osteochondral defect caused a decrease in MCP and PCP by 11% and 30%, respectively, compared to the intact stifle (p < 0.01). With an intact meniscus, implanting an osteochondral graft restored MCP and PCP to 96% (p = 0.56) and 92% (p = 0.41) of the control values. Lateral meniscectomy with grafting decreased CA by 54% and increased PCP by 79% compared to the intact stifle (p < 0.01). CONCLUSIONS OAT restored contact pressures in stifles with a simulated lateral condylar defect when the meniscus was intact. The lateral meniscus has a significant role in maintaining normal contact pressures in both stifles with a defect or following OAT. Meniscectomy should be avoided when a femoral condylar defect is present and when performing OAT.

Taking the Law into Your Own Hands: Establishing an In-house Book Repair Program

Law collections pose some unique problems in terms of their physical care due to filing and updating practices, use patterns and special binding structures such as loose-leafs and pocket parts. This workshop is designed to address specific preservation needs of law collections through lecture, demonstration and hands-on opportunities. Participants will learn the fundamentals of book repair, treatment options and decision-making, and preservation best practices. Emphasis will be placed on moving knowledge into practice through guidelines for establishing institution-appropriate in house book repair programs, by training the trainers in basic book repair techniques and providing all participants with a start-up tool kit.

New insights regarding the incidence, presentation and treatment options of aorto-oesophageal fistulation after thoracic endovascular aortic repair: the European Registry of Endovascular Aortic Repair Complications

OBJECTIVES To review the incidence, clinical presentation, definite management and 1-year outcome in patients with aorto-oesophageal fistulation (AOF) following thoracic endovascular aortic repair (TEVAR). METHODS International multicentre registry (European Registry of Endovascular Aortic Repair Complications) between 2001 and 2011 with a total caseload of 2387 TEVAR procedures (17 centres). RESULTS Thirty-six patients with a median age of 69 years (IQR 56-75), 25% females and 9 patients (19%) following previous aortic surgery were identified. The incidence of AOF in the entire cohort after TEVAR in the study period was 1.5%. The primary underlying aortic pathology for TEVAR was atherosclerotic aneurysm formation in 53% of patients and the median time to development of AOF was 90 days (IQR 30-150). Leading clinical symptoms were fever of unknown origin in 29 (81%), haematemesis in 19 (53%) and shock in 8 (22%) patients. Diagnosis could be confirmed via computed tomography in 92% of the cases with the leading sign of a new mediastinal mass in 28 (78%) patients. A conservative approach resulted in a 100% 1-year mortality, and 1-year survival for an oesophageal stenting-only approach was 17%. Survival after isolated oesophagectomy was 43%. The highest 1-year survival rate (46%) could be achieved via an aggressive treatment including radical oesophagectomy and aortic replacement [relative risk increase 1.73 95% confidence interval (CI) 1.03-2.92]. The survival advantage of this aggressive treatment modality could be confirmed in bootstrap analysis (95% CI 1.11-3.33). CONCLUSIONS The development of AOF is a rare but lethal complication after TEVAR, being associated with the need for emergency TEVAR as well as mediastinal haematoma formation. The only durable and successful approach to cure the disease is radical oesophagectomy and extensive aortic reconstruction. These findings may serve as a decision-making tool for physicians treating these complex patients.

Hybrid aortic arch repair

The successes of thoracic endovascular aortic repair (TEVAR) have spurned new approaches to addressing thoracic aortic pathologies. These hybrid techniques offer an alternative in patients with multi-segmental thoracic aortic pathologies which would have otherwise required a two-step arch replacement and open descending arch repair. The following article offers a clinical insight to the available hybrid approaches, such as rerouting of supra-aortic vessels. Unique complications to endovascular repairs, and technical risks and issues, are also presented along with management options and strategies to minimize such concerns.

Annexin A1 is a biomarker of T-tubular repair in skeletal muscle of nonmyopathic patients undergoing statin therapy

Skeletal muscle complaints are a common consequence of cholesterol-lowering therapy. Transverse tubular (T-tubular) vacuolations occur in patients having statin-associated myopathy and, to a lesser extent, in statin-treated patients without myopathy. We have investigated quantitative changes in T-tubular morphology and looked for early indicators of T-tubular membrane repair in skeletal muscle biopsy samples from patients receiving cholesterol-lowering therapy who do not have myopathic side effects. Gene expression and protein levels of incipient membrane repair proteins were monitored in patients who tolerated statin treatment without myopathy and in statin-naive subjects. In addition, morphometry of the T-tubular system was performed. Only the gene expression for annexin A1 was up-regulated, whereas the expression of other repair genes remained unchanged. However, annexin A1 and dysferlin protein levels were significantly increased. In statin-treated patients, the volume fraction of the T-tubular system was significantly increased, but the volume fraction of the sarcoplasmic reticulum remained unchanged. A complex surface structure in combination with high mechanical loads makes skeletal muscle plasma membranes susceptible to injury. Ca(2+)-dependent membrane repair proteins such as dysferlin and annexin A1 are deployed at T-tubular sites. The up-regulation of annexin A1 gene expression and protein points to this protein as a biomarker for T-tubular repair.