A MODEL FOR EVALUATING THE USE OF IMAGING IN IMAGE-GUIDED INTERVENTIONAL PROCEDURES-POSSIBLE IMPLICATIONS ON OPTIMISATION OF RADIATION PROTECTION.

The present study focuses on introducing the concept of optimisation and proposing a model, including evaluation of image quality, to be used in the clinical routines where image-guided intervention is being performed. The overall aim of the study was to develop a model for evaluating the use of imaging in X-ray-guided interventional procedures and its possible implications on optimisation of radiation protection. In the search for an adequate evaluation model, data from endovascular interventions of the aorta (EVAR procedures) were used. The procedure was schematically described in steps. Every imaging event was connected to the steps in the medical procedure and was also described with the purpose of the imaging event. Available technical, as well as procedural parameters, were studied and analysed. Data were collected from the X-ray equipment for 70 EVAR procedures and, out of these, 12 procedures were randomly selected to be recorded on video to understand the procedure better. It was possible to describe the EVAR procedures in a general way with explanations of the clinical purpose connected to each imaging event. Possible quality parameters of the procedure were identified for the imaging events (radiation dose, image quality). The model method still needs to be refined and will then be applied to clinical data and to other clinical procedures to test the validity.

Wave intensity analysis of maternal arterial stiffness: augmentation index and pulse wave velocity in pregnancies complicated by diabetes or hypertension.

PURPOSE: The aim of our study was to compare the maternal arterial stiffness in pregnant women with diabetic disease, hypertension and those with normal pregnancies. METHODS: A cross-sectional study was performed involving 65 pregnant women with diabetic disease (DD group), 26 pregnant women with hypertension (RR group) and 448 women with normal pregnancies (control group). The augmentation index (AIx) and the pulse wave velocity (PWV) of the right carotid artery were assessed using non-invasive sonographic wave intensity analysis. Furthermore, the reliability of the measurements was evaluated in 21 healthy women. RESULTS: Compared with the controls, the AIx and PWV were increased in the DD group [11.0 (interquartile range, IQR 7.3, 15.2) vs. 5.7 (IQR 2.4, 9.3), P < 0.001; 5.7 (IQR 5.1, 6.4) vs. 5.2 (IQR 4.6, 6.1), P = 0.001; respectively] and the RR group [9.3 (IQR 6.6, 11.5) vs. 5.7 (IQR 2.4, 9.3), P < 0.001; 7.1 (6.3, 7.9) vs. 5.2 (IQR 4.6, 6.1), P < 0.001; respectively]. The intraclass and interclass correlation coefficients were good to excellent for the AIx (ICC: 0.91, P < 0.001 and 0.74, P < 0.002; respectively) and PWV measurements (ICC: 0.71, P < 0.004 and 0.70, P < 0.005; respectively). CONCLUSION: Pregnancies complicated by diabetic disease or hypertension are associated with increased maternal arterial stiffness. The importance of wave intensity analysis needs to be verified and larger studies are needed to establish both normal and cutoff values that may be relevant for clinical decisions.

Cost-effectiveness of revascularization in patients with intermittent claudication.

BACKGROUND: Revascularization is a treatment option for patients with intermittent claudication. However, there is a lack of evidence to support its long-term benefits and cost-effectiveness. The aim of this study was to compare the cost-effectiveness of revascularization and best medical therapy (BMT) with that of BMT alone. METHODS: Data were used from the IRONIC (Invasive Revascularization Or Not in Intermittent Claudication) RCT where consecutive patients with mild-to-severe intermittent claudication owing to aortoiliac or femoropopliteal disease were allocated to either BMT alone (including a structured, non-supervised exercise programme) or to revascularization together with BMT. Inpatient and outpatient costs were obtained prospectively over 24 months of follow-up. Mean improvement in quality-adjusted life-years (QALYs) was calculated based on responses to the EuroQol Five Dimensions EQ-5D-3 L™ questionnaire. Cost-effectiveness was assessed as the cost per QALY gained. RESULTS: A total of 158 patients were randomized, 79 to each group. The mean cost per patient in the BMT group was €1901, whereas it was €8280 in the group treated with revascularization in addition to BMT, with a cost difference of €6379 (95 per cent c.i. €4229 to 8728) per patient. Revascularization in addition to BMT resulted in a mean gain in QALYs of 0·16 (95 per cent c.i. 0·06 to 0·24) per patient, giving an incremental cost-effectiveness ratio of €42 881 per QALY. CONCLUSION: The costs associated with revascularization together with BMT in patients with intermittent claudication were about four times higher than those of BMT alone. The incremental cost-effectiveness ratio of revascularization was within the accepted threshold for public willingness to pay according to the Swedish National Guidelines, but exceeded that of the UK National Institute for Health and Care Excellence guidelines.

The use of aortic balloon occlusion in traumatic shock: first report from the ABO trauma registry.

PURPOSE: Resuscitative endovascular balloon occlusion of the aorta (REBOA) is a technique for temporary stabilization of patients with non-compressible torso hemorrhage. This technique has been increasingly used worldwide during the past decade. Despite the good outcomes of translational studies, clinical studies are divided. The aim of this multicenter-international study was to capture REBOA-specific data and outcomes. METHODS: REBOA practicing centers were invited to join this online register, which was established in September 2014. REBOA cases were reported, both retrospective and prospective. Demographics, injury patterns, hemodynamic variables, REBOA-specific data, complications and 30-days mortality were reported. RESULTS: Ninety-six cases from 6 different countries were reported between 2011 and 2016. Mean age was 52 ± 22 years and 88% of the cases were blunt trauma with a median injury severity score (ISS) of 41 (IQR 29-50). In the majority of the cases, Zone I REBOA was used. Median systolic blood pressure before balloon inflation was 60 mmHg (IQR 40-80), which increased to 100 mmHg (IQR 80-128) after inflation. Continuous occlusion was applied in 52% of the patients, and 48% received non-continuous occlusion. Occlusion time longer than 60 min was reported as 38 and 14% in the non-continuous and continuous groups, respectively. Complications, such as extremity compartment syndrome (n = 3), were only noted in the continuous occlusion group. The 30-day mortality for non-continuous REBOA was 48%, and 64% for continuous occlusion. CONCLUSIONS: This observational multicenter study presents results regarding continuous and non-continuous REBOA with favorable outcomes. However, further prospective studies are needed to be able to draw conclusions on morbidity and mortality.

3D Image Fusion to Localise Intercostal Arteries During TEVAR.

PURPOSE: Preservation of intercostal arteries during thoracic aortic procedures reduces the risk of post-operative paraparesis. The origins of the intercostal arteries are visible on pre-operative computed tomography angiography (CTA), but rarely on intra-operative angiography. The purpose of this report is to suggest an image fusion technique for intra-operative localisation of the intercostal arteries during thoracic endovascular repair (TEVAR). TECHNIQUE: The ostia of the intercostal arteries are identified and manually marked with rings on the pre-operative CTA. The optimal distal landing site in the descending aorta is determined and marked, allowing enough length for an adequate seal and attachment without covering more intercostal arteries than necessary. After 3D/3D fusion of the pre-operative CTA with an intra-operative cone-beam CT (CBCT), the markings are overlaid on the live fluoroscopy screen for guidance. The accuracy of the overlay is confirmed with digital subtraction angiography (DSA) and the overlay is adjusted when needed. Stent graft deployment is guided by the markings. The initial experience of this technique in seven patients is presented. RESULTS: 3D image fusion was feasible in all cases. Follow-up CTA after 1 month revealed that all intercostal arteries planned for preservation, were patent. None of the patients developed signs of spinal cord ischaemia. CONCLUSION: 3D image fusion can be used to localise the intercostal arteries during TEVAR. This may preserve some intercostal arteries and reduce the risk of post-operative spinal cord ischaemia.

Amputation Rates, Mortality, and Pre-operative Comorbidities in Patients Revascularised for Intermittent Claudication or Critical Limb Ischaemia: A Population Based Study.

OBJECTIVES: The aims of this population based study were to describe mid- to long-term amputation risk, cumulative incidence of death or amputation, and differences in pre-operative comorbidities in patients revascularised for lower limb peripheral artery disease (PAD). METHODS: This was an observational cohort study. Data from the Swedish National Quality Registry for Vascular Surgery (Swedvasc) were combined with mandatory national health care registries and patient medical records. All patients who underwent revascularisation in Sweden between May 2008 and May 2013 for intermittent claudication (IC) or critical limb ischaemia (CLI), aged 50 years and older, were identified through the Swedvasc database. The mandatory national health care registries and medical records provided data on comorbidities, mortality, and major amputations. RESULTS: A total of 16,889 patients with PAD (IC, n = 6272; CLI, n = 10,617) were studied. The incidence of amputations in IC patients was 0.4% (range 0.3%-0.5%) per year. Among CLI patients, the amputation rate during the first 6 months following revascularisation was 12.0% (95% CI 11.3-12.6). Thereafter, the incidence declined to approximately 2% per year. The cumulative combined incidence of death or amputation 3 years after revascularisation was 12.9% (95% CI 12.0-13.9) in IC patients and 48.8% (95% CI 47.7-49.8) in CLI patients. Among CLI patients, compared with IC patients, the prevalence of diabetes, ischaemic stroke, heart failure, and atrial fibrillation was approximately doubled and renal failure was nearly tripled, even after age standardisation. CONCLUSION: The risk of amputation is particularly high during the first 6 months following revascularisation for CLI. IC patients have a benign course in terms of limb loss. Mortality in both IC and CLI patients is substantial. Revascularised CLI patients have different comorbidities from IC patients.

Assessment of Minimum Important Difference and Substantial Clinical Benefit with the Vascular Quality of Life Questionnaire-6 when Evaluating Revascularisation Procedures in Peripheral Arterial Disease.

OBJECTIVES: Patient reported outcomes are increasingly used to assess outcomes after peripheral arterial disease (PAD) interventions. VascuQoL-6 (VQ-6) is a PAD specific health-related quality of life (HRQoL) instrument for routine clinical practice and clinical research. This study assessed the minimum important difference for the VQ-6 and determined thresholds for the minimum important difference and substantial clinical benefit following PAD revascularisation. MATERIALS AND METHODS: This was a population-based observational cohort study. VQ-6 data from the Swedvasc Registry (January 2014 to September 2016) was analysed for revascularised PAD patients. The minimum important difference was determined using a combination of a distribution based and an anchor-based method, while receiver operating characteristic curve analysis (ROC) was used to determine optimal thresholds for a substantial clinical benefit following revascularisation. RESULTS: A total of 3194 revascularised PAD patients with complete VQ-6 baseline recordings (intermittent claudication (IC) n = 1622 and critical limb ischaemia (CLI) n = 1572) were studied, of which 2996 had complete VQ-6 recordings 30 days and 1092 a year after the vascular intervention. The minimum important difference 1 year after revascularisation for IC patients ranged from 1.7 to 2.2 scale steps, depending on the method of analysis. Among CLI patients, the minimum important difference after 1 year was 1.9 scale steps. ROC analyses demonstrated that the VQ-6 discriminative properties for a substantial clinical benefit was excellent for IC patients (area under curve (AUC) 0.87, sensitivity 0.81, specificity 0.76) and acceptable in CLI (AUC 0.736, sensitivity 0.63, specificity 0.72). An optimal VQ-6 threshold for a substantial clinical benefit was determined at 3.5 scale steps among IC patients and 4.5 in CLI patients. CONCLUSIONS: The suggested thresholds for minimum important difference and substantial clinical benefit could be used when evaluating VQ-6 outcomes following different interventions in PAD and in the design of clinical trials.

Predisposing Factors for Re-interventions with Additional Iliac Stent Grafts After Endovascular Aortic Repair.

BACKGROUND: Endoleaks of type Ib and III are relatively common causes of re-intervention after EVAR. The aim was to determine underlying causes and identify anatomical factors associated with these re-interventions. METHODS: A total of 444 patients with standard bifurcated stent grafts were included in a retrospective observational study. Patients requiring additional iliac stent grafts (n = 24) were compared to those who did not (n = 420). Pre- and post-operative CT examinations were reviewed in patients with additional iliac stents. Reasons for re-interventions were defined as migration (>5 mm at the distal end or at interconnections), progression of disease (iliac artery diameter exceeding graft diameter), inadequate distal seal length at primary repair, or a combination of these factors. RESULTS: Twenty-four patients received 31 additional grafts in 30 limbs after a median 46 months (range 2-92 months). Five re-interventions (21%) were due to rupture. Re-intervened limbs had a larger iliac artery diameter 18 mm (25th and 75th percentile 20-25) versus 15 mm (13-18 mm), p < .001. The degree of iliac limb oversizing at primary EVAR was lower in re-intervened patients (11% (8-18%) versus 18% (12-26%), p = .003). In re-intervened patients, iliac attachment zones were shorter in treated limbs than in untreated 23 mm (11-34) versus 34 mm (25-44), p < .001). Sixteen of 31 re-interventions (51%) were caused by migration (10 at the distal landing site, 6 at interconnections), nine of 31 (29%) by disease progression, and nine of 31 (29%) had inadequate initial stent graft placement. Three of 31 re-interventions (10%) were done as proactive procedures. CONCLUSIONS: Additional iliac stent grafting occurred late after primary repair; a considerable number were caused by rupture. A low degree of oversizing, migration at the distal landing site, separation of stent graft interconnections, disease progression at the distal landing site, and inadequate initial stent graft placement may all contribute. Patients with large iliac dimensions and short attachment zones may need a larger degree of oversizing and more vigorous surveillance.

Orthogonal Rings, Fiducial Markers, and Overlay Accuracy When Image Fusion is Used for EVAR Guidance.

OBJECTIVE: Evaluation of orthogonal rings, fiducial markers, and overlay accuracy when image fusion is used for endovascular aortic repair (EVAR). METHODS: This was a prospective single centre study. In 19 patients undergoing standard EVAR, 3D image fusion was used for intra-operative guidance. Renal arteries and targeted stent graft positions were marked with rings orthogonal to the respective centre lines from pre-operative computed tomography (CT). Radiopaque reference objects attached to the back of the patient were used as fiducial markers to detect patient movement intra-operatively. Automatic 3D-3D registration of the pre-operative CT with an intra-operative cone beam computed tomography (CBCT) as well as 3D-3D registration after manual alignment of nearby vertebrae were evaluated. Registration was defined as being sufficient for EVAR guidance if the deviation of the origin of the lower renal artery was less than 3 mm. For final overlay registration, the renal arteries were manually aligned using aortic calcification and vessel outlines. The accuracy of the overlay before stent graft deployment was evaluated using digital subtraction angiography (DSA) as direct comparison. RESULTS: Fiducial markers helped in detecting misalignment caused by patient movement during the procedure. Use of automatic intensity based registration alone was insufficient for EVAR guidance. Manual registration based on vertebrae L1-L2 was sufficient in 7/19 patients (37%). Using the final adjusted registration as overlay, the median alignment error of the lower renal artery marking at pre-deployment DSA was 2 mm (0-5) sideways and 2 mm (0-9) longitudinally, mostly in a caudal direction. CONCLUSION: 3D image fusion can facilitate intra-operative guidance during EVAR. Orthogonal rings and fiducial markers are useful for visualization and overlay correction. However, the accuracy of the overlaid 3D image is not always ideal and further technical development is needed.

Displacement Forces in Stent Grafts: Influence of Diameter Variation and Curvature Asymmetry.

OBJECTIVES: Long-term durability after endovascular aortic repair is influenced by stent graft migration causing types I and III endoleaks. Flow induced displacement forces have been shown to have the potential to cause migration. In this study, the influence of the distal diameter of iliac limb stent grafts and the shape of graft curvature on flow induced displacement forces, were investigated. METHODS: In an experimental pulsatile flow model mimicking aortic conditions in vivo, flow induced displacement forces at the proximal and distal ends of iliac limb stent grafts were studied at different angles (0-90°) and perfusion pressures (145/80, 170/90, 195/100 mmHg). Bell-bottomed, tapered, and non-tapered stent grafts and also asymmetric stent graft curvatures at 90° bend were studied. Measurements of graft movement were performed at all studied angulations and graft shapes. RESULTS: For all stent graft diameters, flow induced displacement forces increased with higher pressure and increased stent graft angulation. Forces in the bell-bottom graft were considerably higher than in tapered and non-tapered grafts, with a markedly elevated peak force at the distal end (proximal end, 2.3 ± 0.06 N and distal end, 6.9 ± 0.05 N compared with 1.7 ± 0.08 N and 1.6 ± 0.08 N in non-tapered grafts; p < .001 both). Peak forces in tapered and non-tapered grafts were not significantly different between the proximal and distal end. In asymmetric stent graft curvatures, a significant increase in displacement forces was observed in the attachment zone that was closest to the stent graft bend. Graft movement increased with greater displacement forces. CONCLUSION: Flow induced displacement forces in iliac limb stent grafts are significant and are influenced by distal stent graft diameter and the shape of the graft curvature. The displacement forces are particularly high at the large distal end of bell-bottom grafts. Wide iliac arteries treated with bell-bottom stent grafts may require more vigilant surveillance and improved stent graft fixation.

Importance of Transvaginal Elastography in the Diagnosis of Uterine Fibroids and Adenomyosis.

PURPOSE: To evaluate normal uterine tissue with special regard to age and the presence of uterine fibroids and adenomyosis with transvaginal elastography. MATERIALS AND METHODS: In a prospective study elastographic data of the uterus were obtained in 206 unselected women with transvaginal ultrasound. Women who presented without any uterine pathology in ultrasonography were included in a control group, women with uterine fibroids in a uterine fibroid group, and women with adenomyosis in an adenomyosis group. In the control group strain values were measured at two regions of interest (ROIs) placed one upon the other in the anterior inferior uterine segment during a cycle of compression. The maximum strain ratio (ROI1 / ROI2) was stored as the "age index". In all groups strain values were measured at two ROIs placed side by side in a uterine fibroid (uterine fibroid group) or adenomyosis (adenomyosis group) or healthy homogeneous tissue (control group) and adjacent healthy tissue. Maximum strain ratios (ROI3 / ROI4) were stored as the "lesion index". RESULTS: The "age index" was significantly negatively correlated with the age of the women (r = -0.49, p < 0.001). The median "lesion indices" were significantly (p < 0.001) different between the uterine fibroid, adenomyosis and control groups. Median "lesion indices" were 2.65, 0.44 and 1.19, respectively. CONCLUSION: The "age index" shows that normal uterine tissue has a certain age-dependent stiffness that increases with age. The "lesion index" allows for the assessment of the presence of a uterine fibroid or adenomyosis and helps to differentiate between both focal findings. Thus the use of elastography in addition to conventional ultrasound could help to diagnose uterine focal lesions and may be useful in preoperative planning.

Disinfection of transvaginal ultrasound probes in a clinical setting: comparative performance of automated and manual reprocessing methods.

OBJECTIVES: Transvaginal and intracavitary ultrasound probes are a possible source of cross-contamination with microorganisms and thus a risk to patients' health. Therefore appropriate methods for reprocessing are needed. This study was designed to compare the standard disinfection method for transvaginal ultrasound probes in Germany with an automated disinfection method in a clinical setting. METHODS: This was a prospective randomized controlled clinical study of two groups. In each group, 120 microbial samples were collected from ultrasound transducers before and after disinfection with either an automated method (Trophon EPR®) or a manual method (Mikrozid Sensitive® wipes). Samples were then analyzed for microbial growth and isolates were identified to species level. RESULTS: Automated disinfection had a statistically significantly higher success rate of 91.4% (106/116) compared with 78.8% (89/113) for manual disinfection (P = 0.009). The risk of contamination was increased by 2.9-fold when disinfection was performed manually (odds ratio, 2.9 (95% CI, 1.3-6.3)). Before disinfection, bacterial contamination was observed on 98.8% of probes. Microbial analysis revealed 36 different species of bacteria, including skin and environmental bacteria as well as pathogenic bacteria such as Staphylococcus aureus, enterobacteriaceae and Pseudomonas spp. CONCLUSIONS: Considering the high number of contaminated probes and bacterial species found, disinfection of the ultrasound probe's body and handle should be performed after each use to decrease the risk of cross-contamination. This study favored automated disinfection owing to its significantly higher efficacy compared with a manual method. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Editor's choice. A randomized controlled trial of the fascia suture technique compared with a suture-mediated closure device for femoral arterial closure after endovascular aortic repair.

OBJECTIVES: The aim was to investigate whether the fascia suture technique (FST) can reduce access closure time and procedural costs compared with the Prostar technique (Prostar) in patients undergoing endovascular aortic repair and to evaluate the short- and mid-term outcomes of both techniques. METHODS: In this two center trial, 100 patients were randomized to access closure by either FST or Prostar between June 2006 and December 2009. The primary endpoint was access closure time. Secondary outcome measures included access related costs and evaluation of the short- and mid-term complications. Evaluation was performed peri- and post-operatively, at discharge, at 30 days and at 6 months follow up. RESULTS: The median access closure time was 12.4 minutes for FST and 19.9 minutes for Prostar (p < .001). Prostar required a 54% greater procedure time than FST, mean ratio 1.54 (95% CI 1.25-1.90, p < .001) according to regression analysis. Adjusted for operator experience the mean ratio was 1.30 (95% CI 1.09-1.55, p = .005) and for patient body mass index 1.59 (95% CI 1.28-1.96, p < .001). The technical failure rate for operators at proficiency level was 5% (2/40) compared with 28% (17/59) for those at the basic level (p = .003). The proficiency level group had a technical failure rate of 4% (1/26) for FST and 7% (1/14) for Prostar, p = 1.00, while corresponding rates for the basic level group were 27% (6/22) for FST and 30% (11/37) for Prostar (p = .84). There was a significant difference in cost in favor of FST, with a median difference of €800 (95% CI 710-927, p < .001). CONCLUSIONS: In aortic endovascular repair FST is a faster and cheaper technique than the Prostar technique.

Endovascular technique for arterial shunting to prevent intraoperative ischemia.

OBJECTIVES: The use of an intraoperative shunt is an established technique used to reduce the ischemic time after acute arterial obstruction or in the prevention of hypoperfusion due to complex open vascular or endovascular operative procedures. To date, described methods of temporary extremity blood perfusion have required open surgical techniques. METHODS: An endovascular shunt (ES) was formed by connecting two introducer sheaths to each other, one positioned proximal and one distal to an arterial obstruction. The ES method was used in patients considered to be at high risk for prolonged lower limb ischemia in conjunction with a vascular procedure and where shunt creation by open surgical technique was not considered to be a practical alternative. The flow capacity of the ES was defined in a desktop model. RESULTS: The ES method was used clinically in 15 vascular interventions including eight complex endovascular aortic procedures, three open aortic operations, and four procedures for acute limb ischemia. The shunts were functional in all patients and there were no shunt occlusions. Postoperatively, there were no evident clinical reperfusion injuries. Flow analysis revealed that the ES had a flow capacity of 73% flow capacity compared to a Pruitt-Inahara shunt. CONCLUSION: A new method of temporary blood shunting in connection to vascular procedures has been demonstrated.

Quantitative elastography of the uterine cervix as a predictor of preterm delivery.

OBJECTIVE: To evaluate the correlation between preterm delivery before 37 weeks of gestation and ultrasound elastography strain measurement of cervical stiffness. STUDY DESIGN: In this prospective study, 182 pregnant women were examined vaginally by ultrasound elastography from a mid-sagittal plane. Cervical length was measured and strain was calculated in four regions of interest on the anterior cervical lip. First, the software was validated by intraobserver variability. Second, strain and strain ratios were calculated with adjusted software presets and correlated to the outcome of spontaneous preterm delivery (sPTD). RESULT: A total of 8928 regions of interest (ROIs) and 6696 ratios were evaluated. The median gestational age at examination was 26 ± 6.1 weeks. A median maternal age of 33 ± 5.6 and a medial parity of 1 ± 0.9 were observed. Intra-Class-Correlation values in validation phase ranged from 0.893 to 0.967. The prevalence of sPTD was 11.9%. Strain ratio Rselective was identified as the best predictor of preterm delivery. Rselective values >0.89 were associated with preterm delivery with a sensitivity of 0.59 and a specificity of 0.86 (odds ratio=1.474 for an increase of 0.1 in Rselective; P=0.002). CONCLUSION: Ultrasound elastography strain measurement of cervical stiffness is correlated with the predictability of preterm delivery.

Displacement forces in iliac landing zones and stent graft interconnections in endovascular aortic repair: an experimental study.

OBJECTIVES: Stent graft migration influences the long-term durability of endovascular aortic repair. Flow-induced displacement forces acting on the attachment zones may contribute to migration. Proximal fixation of aortic stent grafts has been improved by using hooks, while distal fixation and stent graft interconnections depend on self-expansion forces only. We hypothesized that flow-induced displacement forces would be significant at the distal end, and would correlate with graft movements. METHODS: As part of an experimental study, an iliac limb stent graft was inserted in a pulsatile flow model similar to aortic in vivo conditions, and fixed-mounted at its proximal and distal ends to strain gauge load cells. Peak displacement forces at both ends and pulsatile graft movement were recorded at different graft angulations (0-90°), perfusion pressures (145/80, 170/90, or 195/100 mmHg), and stroke frequencies (60-100 b.p.m.). RESULTS: Flow-induced forces were of the same magnitude at the proximal and distal end of the stent graft (peak 1.8 N). Both the forces and graft movement increased with angulation and perfusion pressure, but not with stroke rate. Graft movement reached a maximum of 0.29 ± 0.01 mm per stroke despite fixed ends. There were strong correlations between proximal and distal displacement forces (r = 0.97, p < .001), and between displacement forces and graft movement (r = 0.98, p < .001). CONCLUSIONS: Pulsatile flow through a tubular untapered stent graft causes forces of similar magnitude at both ends and induces pulsatile graft movements in its unsupported mid-section. Peak forces are close to those previously reported to be required to extract a stent graft. The forces and movements increase with increasing graft angulation and perfusion pressure. Improved anchoring of the distal end of stent grafts may be considered.

Construct validity and reliability of structured assessment of endoVascular expertise in a simulated setting.

OBJECTIVES: To study the construct validity and reliability of a novel endovascular global rating scale, Structured Assessment of endoVascular Expertise (SAVE). DESIGN: A Clinical, experimental study. MATERIALS: Twenty physicians with endovascular experiences ranging from complete novices to highly experienced operators performed a video-recorded simulated contra-lateral iliac-artery-stenting procedure. The virtual-patient case was a novel technically challenging procedure presenting the distal arteries below the knee. METHODS: Three experts assessed the performances blinded to operator identity. Validity was analysed by correlating experience with performance results. Reliability was analysed according to generalisability theory. RESULTS: The mean score on the 29 items of the SAVE scale correlated well with clinical experience (R = 0.84, P < 0.01) and was found discriminative even among the more experienced participants having performed up to 500 endovascular procedures in total. Only the most experienced participants (>5000 procedures) obtained maximum scores. The inter-rater reliability was high (G = 0.94 and G = 0.95). The procedure time (median 69 min, range 32-86) correlated moderately with clinical experience (R = -0.53, P < 0.05), whereas the fluoroscopy time and amount of contrast fluid did not correlate. CONCLUSIONS: The construct validity and reliability of assessment with the SAVE scale was high when applied to performances in a simulation setting with advanced realism. No ceiling effect was present in the assessment situation.

Celiac trunk coverage in endovascular aneurysm repair.

BACKGROUND AND AIMS: This retrospective study was undertaken to examine the risks associated with obstruction of the coeliac trunk in the process of treating aneurysms with endografting. MATERIAL AND METHODS: 120 patients were treated by endografting for aneurysmal disease. Of these, a subgroup of 9 patients had their celiac trunk covered. If possible, a preoperative angiography was performed to evaluate collateral flow from the superior mesenteric artery. This was considered to predict the risk for ischemia. RESULTS: None of the patients had any severe clinical event of the celiac trunk occlusion or clinical signs of intestinal ischemia. Three patients had transient increase of liver enzymes. CONCLUSIONS: In cases where the distal landing zone of the descending thoracic aorta is to short for endografting, covering of the celiac trunk may be an option if no other surgical alter-native is apparent. Preoperative angiography to visualise the presence of collateral vessels from the superior mesenteric artery is recommended.

Localization and preparation of recombination-active extended defects for transmission electron microscopy analysis.

Recombination-active extended defects in semiconductors frequently occur at a low density which makes their structural and chemical analysis by transmission electron microscopy (TEM) techniques virtually impossible. Here an approach is described that uses in situ electron beam induced current (EBIC) in a focused ion beam machine to localize such defects for TEM lamella preparation. As an example, a defect complex occurring in block-cast multicrystalline silicon with a density of less than 10(4) cm(-3) has been prepared and analyzed by TEM. The chemical sensitivity of the technique is estimated to be about 10(13) atoms cm(-2) which is comparable to synchrotron-based x-ray techniques. The localization accuracy of the TEM lamella is shown to be better than 50 nm when low-energy EBIC is used.