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We report our initial experience using the intraoperative positioning system (IOPS), a novel endovascular navigation system that does not require contrast or radiation, in the treatment of chronic mesenteric ischemia (CMI). We used IOPS to help treat three of four consecutive patients with CMI. Technical problems prevented successful use in one patient. For the patients for whom IOPS was used effectively, catheterization of the mesenteric artery was accomplished more quickly than for the patient for whom IOPS was not effective. Our experience has shown that IOPS can be safely and effectively used for CMI and can reduce the contrast load and radiation dose.

New formulations and applications of hemostatic adjuncts such as fibrin sealant (FS) to support local hemostasis and sutures continue to be developed. In a pivotal, confirmatory, controlled, prospective, single-blinded, randomized, multicenter phase III clinical trial, the efficacy and safety of FS Grifols during vascular surgeries were evaluated.Patients undergoing a nonemergency, open, peripheral vascular surgical procedure with moderate arterial bleeding were recruited. In an initial preliminary part of the study, all patients were treated with FS Grifols. In a subsequent primary part, patients were randomized (2:1) to FS Grifols or manual compression (MC). The primary efficacy end point was the proportion of the primary part patients achieving hemostasis by 4 minutes after the start of treatment. Cumulative proportion and time to hemostasis were secondary efficacy end points. Safety end points (in pooled preliminary and primary parts) included adverse events (AEs), vital signs, physical assessments, clinical laboratory tests, viral markers, and immunogenicity.The primary efficacy end point was met by 76.1% of patients (83/109) for the FS Grifols group versus 22.8% of patients (13/57) for the MC group (P .001). The cumulative proportion of patients at 5, 7, and 10 minutes was 80.7%, 84.4%, and 88.1%, respectively, in the FS Grifols treatment group, and 28.1%, 35.1%, and 45.6% in the MC treatment group (P .001). The median time to hemostasis was shorter in the FS Grifols group (4 minutes vs ≥10 minutes in the MC group; P .001). The nature of AEs reported were those expected in the study patient profile. The percentage of patients experiencing treatment-emergent AEs were similar in both the FS Grifols (pooled n = 59 + 109) and MC groups (81.0% and 77.2%, respectively), most recurrent being procedural pain (34.5% and 36.8%, respectively) and pyrexia (11.3% and 10.5%, respectively).FS Grifols was superior in efficacy and similar in safety to MC as an adjunct local hemostatic agent in patients undergoing open vascular surgeries.

Introduction Vascular impingement of the esophagus is a rare cause of dysphagia, and is most commonly due to aortic arch anomalies such as arterial lusoria. Dysphagia resultant from venous compression is even further less likely. Presentation of case We present a highly unusual case of dysphagia secondary to a large aneurysm of the azygous vein near its confluence with the superior vena cava, which was managed with endovascular modalities. Despite initial treatment success, patient reported some intermittent solid food dysphagia, and was also found to have esophagogastric junction outflow obstruction (EGJOO) on high resolution impedance manometry (HRIM) which was successfully managed with surgical myotomy and partial fundoplication. Discussion The azygos vein has an intimate anatomic relationship with the esophagus as it traverses the posterior mediastinum. Because of this anatomic association, the azygos vein may present a point of esophageal obstruction in the setting of significant pathology. Conclusion This case highlights the possibility of multifactorial causes of dysphagia, and that HRIM is a key aspect of this workup. Additionally we discuss the pertinent anatomy, diagnosis, and treatments for azygos vein aneurysm and EGJOO., Highlights • Vascular impingement of the esophagus is a rare cause of dysphagia. • This type of dysphagia is most commonly due to aortic arch anomalies such as arterial lusoria. • The azygos vein may present a point of esophageal obstruction in the setting of significant pathology. • Endovascular therapy in selected patients can provide resolution of dysphagia in patients with azygos vein aneurysm. • There is possibility of multifactorial causes of dysphagia, and high resolution manometry is a key aspect of this workup.

The maximum diameter criterion is the most important factor in the clinical management of abdominal aortic aneurysms (AAA). Consequently, interventional repair is recommended when an aneurysm reaches a critical diameter, typically 5.0 cm in the United States. Nevertheless, biomechanical measures of the aneurysmal abdominal aorta have long been implicated in AAA risk of rupture. The purpose of this study is to assess whether other geometric characteristics, in addition to maximum diameter, may be highly correlated with the AAA peak wall stress (PWS). Using in-house segmentation and meshing algorithms, 30 patient-specific AAA models were generated for finite element analysis using an isotropic constitutive material for the AAA wall. PWS, evaluated as the spatial maximum of the first principal stress, was calculated at a systolic pressure of 120 mmHg. The models were also used to calculate 47 geometric indices characteristic of the aneurysm geometry. Statistical analyses were conducted using a feature reduction algorithm in which the 47 indices were reduced to 11 based on their statistical significance in differentiating the models in the population (p < 0.05). A subsequent discriminant analysis was performed and 7 of these indices were identified as having no error in discriminating the AAA models with a significant nonlinear regression correlation with PWS. These indices were: D(max) (maximum diameter), T (tortuosity), DDr (maximum diameter to neck diameter ratio), S (wall surface area), K(median) (median of the Gaussian surface curvature), C(max) (maximum lumen compactness), and M(mode) (mode of the Mean surface curvature). Therefore, these characteristics of an individual AAA geometry are the highest correlated with the most clinically relevant biomechanical parameter for rupture risk assessment. We conclude that the indices can serve as surrogates of PWS in lieu of a finite element modeling approach for AAA biomechanical evaluation.

The objective of this work was to perform image-based classification of abdominal aortic aneurysms (AAA) based on their demographic, geometric, and biomechanical attributes. We retrospectively reviewed existing demographics and abdominal computed tomography angiography images of 100 asymptomatic and 50 symptomatic AAA patients who received an elective or emergent repair, respectively, within 1–6 months of their last follow up. An in-house script developed within the MATLAB computational platform was used to segment the clinical images, calculate 53 descriptors of AAA geometry, and generate volume meshes suitable for finite element analysis (FEA). Using a third party FEA solver, four biomechanical markers were calculated from the wall stress distributions. Eight machine learning algorithms (MLA) were used to develop classification models based on the discriminatory potential of the demographic, geometric, and biomechanical variables. The overall classification performance of the algorithms was assessed by the accuracy, area under the receiver operating characteristic curve (AUC), sensitivity, specificity, and precision of their predictions. The generalized additive model (GAM) was found to have the highest accuracy (87%), AUC (89%), and sensitivity (78%), and the third highest specificity (92%), in classifying the individual AAA as either asymptomatic or symptomatic. The k-nearest neighbor classifier yielded the highest specificity (96%). GAM used seven markers (six geometric and one biomechanical) to develop the classifier. The maximum transverse dimension, the average wall thickness at the maximum diameter, and the spatially averaged wall stress were found to be the most influential markers in the classification analysis. A second classification analysis revealed that using maximum diameter alone results in a lower accuracy (79%) than using GAM with seven geometric and biomechanical markers. We infer from these results that biomechanical and geometric measures by themselves are not sufficient to discriminate adequately between population samples of asymptomatic and symptomatic AAA, whereas MLA offer a statistical approach to stratification of rupture risk by combining demographic, geometric, and biomechanical attributes of patient-specific AAA.

Abdominal aortic aneurysm (AAA) is a vascular disease characterized by the enlargement of the infrarenal segment of the aorta. A ruptured AAA can cause internal bleeding and carries a high mortality rate, which is why the clinical management of the disease is focused on preventing aneurysm rupture. AAA rupture risk is estimated by the change in maximum diameter over time (i.e., growth rate) or if the diameter reaches a prescribed threshold. The latter is typically 5.5 cm in most clinical centers, at which time surgical intervention is recommended. While a size-based criterion is suitable for most patients who are diagnosed at an early stage of the disease, it is well known that some small AAA rupture or patients become symptomatic prior to a maximum diameter of 5.5 cm. Consequently, the mechanical stress in the aortic wall can also be used as an integral component of a biomechanics-based rupture risk assessment strategy. In this work, we seek to identify geometric characteristics that correlate strongly with wall stress using a sample space of 100 asymptomatic, unruptured, electively repaired AAA models. The segmentation of the clinical images, volume meshing, and quantification of up to 45 geometric measures of each AAA were done using in-house Matlab scripts. Finite element analysis was performed to compute the first principal stress distributions from which three global biomechanical parameters were calculated: peak wall stress, 99(th)-percentile wall stress and spatially averaged wall stress. Following a feature reduction approach consisting of Pearson’s correlation matrices with Bonferroni correction and linear regressions, a multivariate stepwise regression analysis was conducted to find the geometric measures most highly correlated with each of the biomechanical parameters. Our findings indicate that wall stress can be predicted by geometric indices with an accuracy of up to 94% when AAA models are generated with uniform wall thickness and up to 67% for patient specific, non-uniform wall thickness AAA. These geometric predictors of wall stress could be used in lieu of complex finite element models as part of a geometry-based protocol for rupture risk assessment.

In this work, we provide a quantitative assessment of the biomechanical and geometric features that characterize abdominal aortic aneurysm (AAA) models generated from 19 Asian and 19 Caucasian diameter-matched AAA patients. 3D patient-specific finite element models were generated and used to compute peak wall stress (PWS), 99th percentile wall stress (99th WS), and spatially averaged wall stress (AWS) for each AAA. In addition, 51 global geometric indices were calculated, which quantify the wall thickness, shape, and curvature of each AAA. The indices were correlated with 99th WS (the only biomechanical metric that exhibited significant association with geometric indices) using Spearman's correlation and subsequently with multivariate linear regression using backward elimination. For the Asian AAA group, 99th WS was highly correlated (R2 = 0.77) with three geometric indices, namely tortuosity, intraluminal thrombus volume, and area-averaged Gaussian curvature. Similarly, 99th WS in the Caucasian AAA group was highly correlated (R2 = 0.87) with six geometric indices, namely maximum AAA diameter, distal neck diameter, diameter-height ratio, minimum wall thickness variance, mode of the wall thickness variance, and area-averaged Gaussian curvature. Significant differences were found between the two groups for ten geometric indices; however, no differences were found for any of their respective biomechanical attributes. Assuming maximum AAA diameter as the most predictive metric for wall stress was found to be imprecise: 24% and 28% accuracy for the Asian and Caucasian groups, respectively. This investigation reveals that geometric indices other than maximum AAA diameter can serve as predictors of wall stress, and potentially for assessment of aneurysm rupture risk, in the Asian and Caucasian AAA populations. Nanyang Technological University This work was funded by a Research Student Scholarship from the Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore to Tejas Canchi, and a U.S. National Institutes of Health award (R01HL121293) to Ender A. Finol.

Abdominal aortic aneurysm (AAA) is an asymptomatic aortic disease with a survival rate of 20% after rupture. It is a vascular degenerative condition different from occlusive arterial diseases. The size of the aneurysm is the most important determining factor in its clinical management. However, other measures of the AAA geometry that are currently not used clinically may also influence its rupture risk. With this in mind, the objectives of this work are to develop an algorithm to calculate the AAA wall thickness and abdominal aortic diameter at planes orthogonal to the vessel centerline, and to quantify the effect of geometric indices derived from this algorithm on the overall classification accuracy of AAA based on whether they were electively or emergently repaired. Such quantification was performed based on a retrospective review of existing medical records of 150 AAA patients (75 electively repaired and 75 emergently repaired). Using an algorithm implemented within the MATLAB computing environment, 10 diameter- and wall thickness-related indices had a significant difference in their means when calculated relative to the AAA centerline compared to calculating them relative to the medial axis. Of these 10 indices, nine were wall thickness-related while the remaining one was the maximum diameter (D(max)). D(max) calculated with respect to the medial axis is over-estimated for both electively and emergently repaired AAA compared to its counterpart with respect to the centerline. C5.0 decision trees, a machine learning classification algorithm implemented in the R environment, were used to construct a statistical classifier. The decision trees were built by splitting the data into 70% for training and 30% for testing, and the properties of the classifier were estimated based on 1000 random combinations of the 70/30 data split. The ensuing model had average and maximum classification accuracies of 81.0% and 95.6%, respectively, and revealed that the three most significant indices in classifying AAA are, in order of importance: AAA centerline length, L2-norm of the Gaussian curvature, and AAA wall surface area. Therefore, we infer that the aforementioned three geometric indices could be used in a clinical setting to assess the risk of AAA rupture by means of a decision tree classifier. This work provides support for calculating cross-sectional diameters and wall thicknesses relative to the AAA centerline and using size and surface curvature based indices in classification studies of AAA.

Abdominal aortic aneurysm (AAA) is an asymptomatic aortic disease with a survival rate of 20% after rupture. It is a vascular degenerative condition different from occlusive arterial diseases. The size of the aneurysm is the most important determining factor in its clinical management. However, other measures of the AAA geometry that are currently not used clinically may also influence its rupture risk. With this in mind, the objectives of this work are to develop an algorithm to calculate the AAA wall thickness and abdominal aortic diameter at planes orthogonal to the vessel centerline, and to quantify the effect of geometric indices derived from this algorithm on the overall classification accuracy of AAA based on whether they were electively or emergently repaired. Such quantification was performed based on a retrospective review of existing medical records of 150 AAA patients (75 electively repaired and 75 emergently repaired). Using an algorithm implemented within the MATLAB computing environment, 10 diameter- and wall thickness-related indices had a significant difference in their means when calculated relative to the AAA centerline compared to calculating them relative to the medial axis. Of these 10 indices, nine were wall thickness-related while the remaining one was the maximum diameter (Dmax). Dmax calculated with respect to the medial axis is over-estimated for both electively and emergently repaired AAA compared to its counterpart with respect to the centerline. C5.0 decision trees, a machine learning classification algorithm implemented in the R environment, were used to construct a statistical classifier. The decision trees were built by splitting the data into 70% for training and 30% for testing, and the properties of the classifier were estimated based on 1000 random combinations of the 70/30 data split. The ensuing model had average and maximum classification accuracies of 81.0 and 95.6%, respectively, and revealed that the three most significant indices in classifying AAA are, in order of importance: AAA centerline length, L2-norm of the Gaussian curvature, and AAA wall surface area. Therefore, we infer that the aforementioned three geometric indices could be used in a clinical setting to assess the risk of AAA rupture by means of a decision tree classifier. This work provides support for calculating cross-sectional diameters and wall thicknesses relative to the AAA centerline and using size and surface curvature based indices in classification studies of AAA.

Objective The standard of care in the treatment of vascular disease continues to evolve as endovascular therapies develop. Currently, it is unclear how medical malpractice litigation has adapted to the "endovascular era." This retrospective case review is the most comprehensive analysis to date of malpractice actions involving endovascular procedures performed by vascular surgeons (VSs), interventional radiologists (IRs), interventional cardiologists (ICs), and cardiothoracic surgeons (CTSs). Methods The legal databases LexisNexis and Westlaw were searched for all published legal cases in the United States involving endovascular procedures. The search was limited to state and federal cases up to and including the year 2016. Keywords included "malpractice," "vascular," "endovascular," "catheter," "catheterization," "stent," "angiogram," "angiography," and "surgery." Cases involving tax revenue, insurance disputes, Social Security Disability, and hospital employment contract disputes were excluded. Data were analyzed using χ 2 test. Results There were 2115 initial search results identified, and 369 cases were included in final analysis. The rate of endovascular procedure-related lawsuits (per 1000 active physicians in the specialty) was highest for ICs (105.56), whereas rates for VSs and IRs were comparable (18.47 and 16.85, respectively); 93% of the IC cases were related to coronary interventions. Overall, 55% (148/271 classifiable cases) of actions were related to elective procedures. For VSs specifically, 46% (25/54) of cases arose from diagnostic angiography and inferior vena cava filter placement, two relatively minor procedure types. Overall, 83% (176/211 finalized cases) of verdicts favored defendants, with no significant differences across the specialties; 43% (157/368) of total cases involved death of the patient. Among the four specialties, there was a significant ( P = .0004) difference in the primary allegation (informed consent, preprocedure negligence, intraprocedure complications, or postprocedure complications) underlying the litigation. For CTSs and VSs, there was a predominance of informed consent and preprocedure negligence allegations (70% [7/10] and 52% [28/54], respectively). Intraprocedure negligence was the most common allegation for IRs (59% [23/39]), whereas allegations were more evenly distributed among ICs. Conclusions Key issues were identified regarding malpractice litigation involving the specialties that commonly perform endovascular procedures. Despite the increasing number of ICs doing peripheral interventions, a large majority of IC cases were related to coronary treatments. A surprisingly large percentage of VS cases were related to seemingly minor cases. There were significant interspecialty differences in the primary underlying allegations. As the scope of endovascular procedures broadens and deepens, it is important for clinicians to be aware of legal considerations relevant to their practice.

An abdominal aortic aneurysm (AAA) carries one of the highest mortality rates among vascular diseases when it ruptures. To predict the role of surface curvature in rupture risk assessment, a discriminatory analysis of aneurysm geometry characterization was conducted. Data was obtained from 205 patient-specific computed tomography image sets corresponding to three AAA population subgroups: patients under surveillance, those that underwent elective repair of the aneurysm, and those with an emergent repair. Each AAA was reconstructed and their surface curvatures estimated using the biquintic Hermite finite element method (BQFE). Local surface curvatures were processed into ten global curvature indices. Statistical analysis of the data revealed that the L2-norm of the Gaussian and Mean surface curvatures can be utilized as classifiers of the three AAA population subgroups. The application of statistical machine learning on the curvature features yielded 85.5% accuracy in classifying electively and emergent repaired AAAs, compared to a 68.9% accuracy obtained by using maximum aneurysm diameter alone. Such combination of non-invasive geometric quantification and statistical machine learning methods can be used in a clinical setting to assess the risk of rupture of aneurysms during regular patient follow-ups.

ObjectiveThe ideal hemostatic agent for treatment of suture-line bleeding at vascular anastomoses has not yet been established. This study evaluated whether the use of a fibrin sealant containing 500 IU/mL thrombin and synthetic aprotinin (FS; marketed in the United States under the name TISSEEL) is beneficial for treatment of challenging suture-line bleeding at vascular anastomoses of expanded polytetrafluoroethylene (ePTFE) grafts, including those further complicated by concomitant antiplatelet therapies.MethodsOver a 1-year period ending in 2010, ePTFE graft prostheses, including arterio-arterial bypasses and arteriovenous shunts, were placed in 140 patients who experienced suture-line bleeding that required treatment after completion of anastomotic suturing. Across 24 US study sites, 70 patients were randomized and treated with FS and 70 with manual compression (control). The primary end point was the proportion of patients who achieved hemostasis at the study suture line at 4 minutes after start of application of FS or positioning of surgical gauze pads onto the study suture line.ResultsThere was a statistically significant difference in the comparison of hemostasis rates at the study suture line at 4 minutes between FS (62.9%) and control (31.4%) patients (P < .0001), which was the primary end point. Similarly, hemostasis rates in the subgroup of patients on antiplatelet therapies were 64.7% (FS group) and 28.2% (control group). When analyzed by bleeding severity, the hemostatic advantage of FS over control at 4 minutes was similar (27.8% absolute improvement for moderate bleeding vs 32.8% for severe bleeding). Logistic regression analysis (accounting for gender, age, intervention type, bleeding severity, blood pressure, heparin coating of ePTFE graft, and antiplatelet therapies) found a statistically significant treatment effect in the odds ratio (OR) of meeting the primary end point between treatment groups (OR, 6.73; P < .0001), as well as statistically significant effects for intervention type (OR, 0.25; P = .0055) and bleeding severity (OR, 2.59; P = .0209). The safety profile of FS was excellent as indicated by the lack of any related serious adverse events.ConclusionsThe findings from this phase 3 study confirmed that FS is safe and its efficacy is superior to manual compression for hemostasis in patients with peripheral vascular ePTFE grafts. The data also suggest that FS promotes hemostasis independently of the patient's own coagulation system, as shown in a representative population of patients with vascular disease under single- or dual-antiplatelet therapies.

Focal infrarenal aortic stenosis is relatively rare. Traditionally, aortic endarterectomy and aortic bypass surgery have been used to treat these lesions. However, percutaneous transluminal angioplasty and stenting have become well-defined alternatives. A 62-year-old woman presented with bilateral ischemic rest pain. Angiography revealed a mid-infrarenal aortic stenosis adjacent to an enlarged, patent inferior mesenteric artery. Celiac artery and superior mesenteric artery stenoses were also present. The kissing-stent technique is a viable option for ensuring inferior mesenteric artery patency when treating distal aortic lesions by endovascular means in patients with asymptomatic multivessel mesenteric artery disease.

Introduction Bien que benefique, la faible thrombogenicite, porosite et elasticite des protheses en polytetrafluoroethylene expanse (ePTFE) peut exacerber le probleme des saignements sur ligne de suture au niveau des anastomoses vasculaires et conduire a augmenter la duree operatoire. L'objectif global de cette etude prospective, randomisee, controlee, avec sujets aveugles, multicentrique de phase 2 etait d'evaluer l'efficacite et la securite d'une colle de fibrine (CF) contenant 500 IU/mL de thrombine et d'aprotinine de synthese (vendue aux Etats-Unis sous le nom de TISSEEL) pour l'hemostase chez les sujets operes en chirurgie vasculaire recevant des protheses vasculaires en ePTFE. Methodes La CF etait comparee a la compression manuelle par compresses chirurgicales qui constitue le standard en matiere d'hemostase en chirurgie vasculaire. Deux delais de polymerisation de la CF (60 et 120 secondes) etaient examines afin d'evaluer l'influence sur les resultats en termes d'efficacite. Les patients qui avaient la mise en place d'une prothese en ePTFE (N = 73) et qui necessitaient un traitement supplementaire apres hemostase chirurgicale etaient randomises pour traitement par CF a clamps ouverts pendant 60 secondes (CF-60 ; N = 26), traitement par CF a clamps ouverts pendant 120 secondes (CF-120 ; N = 24) ou compression manuelle par compresses chirurgicales (controles ; N = 23). La proportion de sujets chez lesquels l'hemostase etait obtenue a 4 minutes (critere primaire de jugement) ainsi qu'a 6 et 10 minutes (criteres secondaires de jugement) au sein des trois groupes de traitement etait analysee en regression logistique, en prenant en compte le sexe, l'âge, le type d'intervention, la severite du saignement, la pression arterielle systolique, la pression arterielle diastolique, l'heparinisation des protheses ePTFE et les antiagregants plaquettaires. Resultats Il existait des differences substantielles concernant la proportion de sujets chez qui l'hemostase etait obtenue au niveau de la ligne de suture a 4 minutes entre le groupe CF-120 (62,5%) et le groupe controle (34,8% ; amelioration relative de 79,6%). L'analyse en regression logistique retrouvait un effet therapeutique statistiquement significatif a un niveau de 10% sur l'odds ratio (OR) concernant l'obtention de l'hemostase a 4 minutes entre le groupe CF-120 et le groupe controle (OR = 3,98, p = 0,0991). De plus, il etait montre que l'administration peri-operatoire d'antiagregants plaquettaires influencait significativement (OR = 3,89, p = 0,0607) le niveau d'hemostase suivant le critere primaire de jugement. Aucun effet therapeutique statistiquement significatif n'etait retrouve pour les autres facteurs. Les analyses par regression logistique concernant les criteres secondaires de jugement demontraient un effet therapeutique significatif sur l'hemostase a 6 minutes (OR = 9,92, p = 0,0225) et a 10 minutes (OR = 6,70, p = 0,0708) entre le groupe CF-120 et le groupe controle. Des effets statistiquement significatifs au cours des analyses en regression logistique etaient trouves a un niveau de 10% concernant l'OR d'obtention de l'hemostase a 6 et 10 minutes, respectivement, pour les facteurs suivants: CF-120 versus groupe controle (OR = 9,92 ; p = 0,0225 et OR = 6,70 ; p = 0,0708, respectivement), le type d'intervention (OR = 0,3 ; p = 0,0775 et OR = 0,25 ; p = 0,0402, respectivement), et l'heparinisation des protheses en ePTFE (OR = 4,83 ; p = 0,0413 et OR = 3,65 ; p = 0,911, respectivement). La CF etait sure et bien toleree, comme indique par l'absence d'evenement indesirable serieux. Conclusion Les resultats de cette etude de phase 2 soutiennent le fort profil de securite de la CF et suggerent qu'il s'agit d'un agent hemostatique efficace lors de la mise en place d'une prothese chirurgicale en ePTFE et d'un outil utile en chirurgie vasculaire peripherique avec de possibles applications.

Background The low thrombogenicity, porosity, and limited elasticity of expanded polytetrafluoroethylene (ePTFE) vascular grafts, although beneficial, may exacerbate the problem of suture-line bleeding at vascular anastomoses and consequently lead to increased operating times. The overall objective of this prospective, randomized, controlled, subject-blinded, multicenter phase 2 study was to evaluate the efficacy and safety of a fibrin sealant containing 500 IU/mL thrombin and synthetic aprotinin (FS; marketed in the United States under the name TISSEEL) for hemostasis in subjects undergoing vascular surgery and receiving prosthetic ePTFE vascular grafts. Methods FS was compared with manual compression with surgical gauze pads, a standard of care for hemostasis in vascular surgery. Two FS polymerization/setting times (60 and 120 seconds) were investigated to evaluate influence on the efficacy results. Patients undergoing ePTFE graft placement surgery ( N = 73) who experienced bleeding that required treatment after surgical hemostasis were randomized to be treated with FS with clamps opened at 60 seconds (FS-60; N = 26), with FS with clamps opened at 120 seconds (FS-120; N = 24), or with manual compression with surgical gauze pads (control; N = 23). The proportion of subjects achieving hemostasis at 4 minutes (primary endpoint) as well as at 6 and 10 minutes (secondary endpoints) in the three treatment groups was analyzed using logistic regression analysis, taking into account gender, age, type of intervention, severity of bleeding, systolic blood pressure, diastolic blood pressure, heparin coating of the ePTFE graft, and platelet inhibitors. Results There were substantial differences in the proportion of subjects who achieved hemostasis at the study suture line at 4 minutes from treatment application between FS-120 (62.5%) and control (34.8%) groups (a 79.6% relative improvement). Logistic regression analyses found a statistically significant treatment effect at the 10% level in the odds ratio (OR) of achieving hemostasis at 4 minutes between the FS-120 and control groups (OR = 3.98, p = 0.0991). Furthermore, it has been shown that the perioperative administration of platelet inhibitors significantly influences (OR = 3.89, p = 0.0607) hemostasis rates at the primary endpoint. No statistically significant treatment effects were found for the other factors. Logistic regression analyses performed on the secondary endpoints demonstrated a significant treatment effect of achieving hemostasis at 6 minutes (OR = 9.92, p = 0.0225) and at 10 minutes (OR = 6.70, p = 0.0708) between the FS-120 and control groups. Statistically significant effects in the logistic regression analyses were found at the 10% level in the OR of achieving hemostasis at 6 and 10 minutes, respectively, for the following factors: FS-120 versus control group (OR = 9.92; p = 0.0225 and OR = 6.70; p = 0.0708, respectively), type of intervention (OR = 0.3; p = 0.0775 and OR = 0.25; p = 0.0402, respectively), and heparin coating of the ePTFE prosthesis (OR = 4.83; p = 0.0413 and OR = 3.65; p = 0.0911, respectively). FS was safe and well-tolerated, as indicated by the lack of any related serious adverse events. Conclusion The findings from this phase 2 study support the strong safety profile of FS and suggest that it is an efficacious hemostatic agent in ePTFE graft placement surgery, as well as a useful tool in peripheral vascular surgery applications.

Introduction Le but de cette etude etait de determiner quelles caracteristiques de la zone d’ancrage proximale etaient predictives de l’apparition d’endofuite de type IA precoce et tardive apres le traitement endovasculaire d’un anevrysme de l’aorte abdominale sous-renale (EVAR). Methodes Nous avons evalue 146 patients qui ont eu une EVAR entre janvier 2006 et mars 2007. Dans la cohorte, les angioscanners de 100 (68,5%) patients etaient disponibles, montrant la mesure detaillee des parametres proximaux du collet, incluant le diametre, la longueur, les calcifications, le thrombus, l’angulation sus et sous-renal, et la morphologie conique. L’ensemble des donnees numeriques ont ete traitees pour obtenir des mesures de ligne centrale. Les dossiers medicaux et les angioscanners de suivi ont ete revus. Resultats L'âge moyen des patients etait de 72,7 ans, avec 78% d’hommes. Parmi ces patients, 66% ne completaient pas les instructions d'usage du dispositif d’EVAR Zenith, et 50% ne completaient pas les instructions d'usage pour du dispositif AneuRx. Neuf patients ont eu une endofuite de type IA peroperatoire. Un taux de succes technique primaire assiste de 100% a ete obtenu avec l'utilisation supplementaire d’angioplasties ( n = 4), de stents nus ( n = 3), et d’extension couverte ( n = 2). Il y avait une association significative entre l’apparition d’une endofuite de type IA et l’ampleur de l'angle sous-renal ( p Conclusions Nos donnees indiquent que l'angulation sous-renale est liee a l’incidence d’endofuite de type IA peroperatoire, mais les autres facteurs souvent indicateurs d’une l'anatomie defavorable du collet ne sont pas des facteurs predictifs significatifs. D'ailleurs, toutes les endofuites de type IA dans cette cohorte ont ete eliminees avec succes en peroperatoire, et la durabilite a ete confirmee par la surveillance postoperatoire. Ces donnees demontrent que l'anatomie difficile du collet est associee au recours de gestes supplementaires endovasculaires peroperatoires, et qu’une exclusion efficace et durable de l'anevrysme peut alors etre obtenue.

The purpose of this study was to determine which proximal seal zone characteristics were predictive of early and late type Ia endoleak development after endovascular aortic aneurysm repair (EVAR) for infrarenal abdominal aortic aneurysmal disease.We evaluated 146 patients who underwent EVAR between January 2006 and March 2007. In the cohort, high-resolution computed tomography images of 100 (68.5%) patients were available, which showed detailed measurement of proximal neck parameters, including diameter, length, calcification, thrombus, suprarenal and infrarenal angles, and reverse taper morphology. Postprocessing of digital data sets was performed to obtain centerline-of-flow measurements. Relevant medical records and follow-up computed tomography scans were reviewed.Mean age of the patients was 72.7 years, with 78% being male. Of these patients, 66% did not satisfy the instructions for use for the Zenith EVAR device, and 50% did not satisfy the instructions for use for the AneuRx device. Nine patients had intraoperative type Ia endoleaks. A 100% assisted primary technical success rate was achieved with the adjunctive use of angioplasty (n = 4), uncovered stent (n = 3), and extension cuff (n = 2) placement. There was a significant association between type Ia endoleak development and magnitude of the infrarenal angle (p0.01); however, other parameters were not significant. At follow-up (mean, 587 days), no patient had a type Ia endoleak, and there were no aneurysm-related deaths.Our data indicate that infrarenal angle is related to intraoperative type Ia endoleak occurrence, but other factors often thought to be indicative of adverse neck anatomy are not significant predictors. Moreover, all type Ia endoleaks in this cohort were successfully eliminated intraoperatively, and durability was confirmed on postoperative surveillance. These data demonstrate that challenging neck anatomy is associated with the need for intraoperative endovascular adjuncts, and that effective and durable aneurysm exclusion should still be expected.

Rationnelle L’hyperplasie myointimale est un resultat pathologique de la reponse inflammatoire normale du corps aux dommages des vaisseaux sanguins et est la principale cause d’echec des pontages arteriels peripheriques. Puisque les agents immunosuppresseurs sont connus pour diminuer l’inflammation, nous avons presume que les resultats des pontages des membres inferieurs chez les greffes renaux doivent etre superieurs a ceux des hemodialyses. Methodes le registre de chirurgie vasculaire d’un centre de soin tertiaire simple a ete retrospectivement passe en revue pour identifier les patients qui ont subi des procedures de pontages aux membres inferieurs. Tous les patients presentant une histoire de transplantation renale ont ete choisis pour l’analyse. Un groupe consecutif de patients pontes presentant une insuffisance renale dialysee a ete choisi comme groupe temoin. Le critere de jugement primaire etait la survie sans amputation. Resultats La reconstruction vasculaire pour maladie vasculaire chronique peripherique a donne un taux de survie sans amputation de 82% a 1 an dans le groupe temoin par rapport seulement a 22% dans le groupe avec transplantation renale ( p = 0,02), qui correspondait exactement a permeabilite primaire a 1 an. Les patients ont ete operes pour claudication severe ( n = 1), douleur de decubitus ( n = 1), et troubles trophiques ( n = 17). Il n’y avait aucune difference entre les groupes en ce qui concerne l’indication operatoire ou les etats de comorbidites. Conclusions Ces donnees suggerent un effet deletere de l’immunosuppression sur les resultats des pontages aux membres inferieurs aux doses exigees pour empecher le rejet du greffon. Cette conclusion, qui a ete a peine rapportee, sous-estime l’importance de la recherche de la maladie vasculaire peripherique dans la population de greffe et la necessite d’une intervention precoce une fois medicalement indiquee.

Background Myointimal hyperplasia is a pathologic result of the body’s natural inflammatory response to injury of the blood vessels and a leading cause of peripheral arterial bypass failure. Because immunosuppressive agents are known to abate inflammation, we hypothesized the superior outcome of lower extremity bypass in renal transplant recipients compared with the hemodialysis population. Methods The vascular surgery registry at a single tertiary care center was retrospectively reviewed to identify patients who underwent lower extremity bypass procedures. All patients with a history of renal transplantation were selected for analysis. A consecutive group of bypass patients with dialysis-dependent renal failure was selected as a control cohort. The primary endpoint was amputation-free survival. Results Vascular reconstruction for chronic peripheral vascular disease yielded an amputation-free survival rate of 82% at 1 year for the those in the control group as compared with only 22% in the those with a history of renal transplantation ( p = 0.02), which corresponded exactly with primary patency at 1 year. Patients were operated on for severe claudication ( n = 1), rest pain ( n = 1), and tissue loss ( n = 17). There was no difference between the groups with regard to indication for operation or comorbid conditions. Conclusions These data suggest a deleterious effect of immunosuppression on outcome of lower extremity bypass procedures at the doses required to prevent allograft rejection. This finding, which has been scarcely reported, underscores the importance of peripheral vascular disease screening in the transplant population and early intervention when clinically indicated.

Type IA endoleaks associated with endovascular aortic aneurysm repair are typically treated with endovascular adjuncts. Technical failure results when such maneuvers are unsuccessful, and endograft removal may, unfortunately, become necessary. The novel management of a recalcitrant type IA endoleak using the artificial embolization device, Onyx (Micro Therapeutics Inc, Irvine, Calif) is presented for the case of a nonagenarian with prohibitive surgical risk after conventional techniques had failed.

Long-term success of endovascular aneurysm repair (EVAR) relies on a stable proximal neck. The authors' goal was to determine whether neck dilatation after EVAR varies among 4 different endografts and whether it is related to complications of the proximal neck. Core laboratory data from 4 phase II trials of aortic endografts were analyzed for neck diameter changes over time. Patients who had at least 24 months' follow-up were included in the analysis. Neck measurement methodology varied among the 3 core labs used. Values are reported within the parameters used by each lab. Short-axis neck diameter close to 5 mm below the renal arteries, when available, was used for longitudinal comparisons. Dilation was defined as an enlargement of 3 mm or more from the first postoperative scan to the last available follow-up for each patient. Graft migration and late proximal endoleaks were determined by the individual core labs. A limited number of Lifepath grafts had most recent follow-up measurements performed by the authors. Results were compared by using Student's t test, chi-square analysis, and the Pearson correlation coefficient. Postoperative measurements from 729 EVAR patients were examined. Follow-up ranged from 24 to 60 months for 229 Ancure (Guidant) and 258 AneuRx (Medtronic) patients, and from 24 to 36 months for 211 Excluder (Gore) and 31 first-generation Lifepath (Edwards) patients. Neck dilation was noted in 124 patients (17.0%) and did not differ significantly among graft types. The incidences of late proximal endoleaks were similar among graft types, but rates of migration differed (p= 0.01). Dilation was associated with migration in Ancure (p=0.03) and Excluder (p=0.02) grafts. Late proximal endoleaks were seen in 4.1% of patients with and in 0.7% of patients without dilation (p=0.001). Patients with initial neck diameter >25 mm had significantly less dilatation than those with smaller necks (p

This study addresses the hypothesis that exposure to peripheral arterial (ART) or coronary (COR) hemodynamics and wall biomechanics affect platelet deposition on vein segments. Intact human saphenous vein (HSV) and porcine internal jugular vein (PIJV) segments were studied under venous (VEN), ART, and COR environments using in vitro perfusion systems. Wall shear stress (tau) and circumferential wall stress (sigma(theta)) were calculated for PIJV segments. Platelet deposition was measured using a radioactive assay. PIJV ART segments exhibited a 14% increase in inner diameter over time (P < 0.05). tau, acting on PIJV ART specimens, was less at 6 h compared with time 0 (P < 0.05). sigma(theta) was lower in the VEN specimens compared with ART and COR groups (P < 0.01). Platelet deposition decreased by 40% on PIJV ART segments (P < 0.05) but increased 3.2-fold on PIJV COR segments (P < 0.05) versus VEN control segments. Platelet deposition was increased 1.75-fold in COR HSV cases versus VEN segments. These data indicate that short-term exposure to COR conditions lead to enhanced platelet deposition, whereas ART conditions decrease platelet deposition.

Purpose: To examine if 3-dimensional (3D) reconstructions of computed tomographic (CT) data, by imaging perpendicular to blood flow, can improve aortic diameter measurement accuracy over axial (2D) CT. Methods: Two independent, blinded observers used electronic calipers to measure the minor axis and the line perpendicular to it on 40 2.5-mm 2D CT scans from 31 patients. A circular electronic tool was used to estimate diameters on 3D reconstructions from the same 40 scans. Measurements of the aortic neck were obtained 5 mm below the renal arteries and the widest slice of the aneurysm was used to measure sac diameter. Only the minor axis was measured at the iliac arteries immediately above the left (LI) and right (RI) iliac bifurcations. Datasets were compared with an intraclass correlation coefficient (ICC), Bland and Altman variation assessments, and absolute differences. Results: ICC between 2D and 3D scans demonstrated high correlation with 2D minor axis measurements (neck=0.9282, sac=0.8956, RI=0.8755, LI=0.7381). 3D to 2D major axis correlation was lower (neck=0.6388, sac=0.8995). Variation between 3D and 2D minor axis measurements was low (0.51-mm average variation from the mean for the minor axis and 1.30-mm variation for the major axis). Average absolute difference between 3D and 2D diameters was 1.01 mm (minor axis) versus 2.61 mm (major axis). Interobserver correlation was highest for sac measurements both in 2D minor axis (ICC=0.8990) and 3D (ICC=0.9518). Conclusions: Minor axis measurements on axial CT scan can substitute for diameters obtained from 3D reconstructions in most clinical situations.

Objective: This study was undertaken to determine the effect of nitric oxide (NO) on tissue factor (TF) expression in vascular smooth muscle cells. Study Design: Rat aortic smooth muscle cells (RASMCs) were exposed to NO delivered exogenously with the NO donor S -nitroso- N -acetylpenicillamine (SNAP) or produced endogenously after infection with an adenoviral vector carrying human inducible NO synthase (AdiNOS). Functional TF activity was assessed with chromogenic TF assay. TF antigen was determined with immunohistochemistry. Northern blot analysis was used to determine steady- state TF messenger RNA (mRNA). Electrophoretic mobility gel shift assay was performed to determine the nuclear binding activity of nuclear factor κ-B (NFκB). NFκB activity was inhibited by either prior transduction of RASMCs with mutant IκB or treatment with pyrrolidine dithiocarbamate. Results: RASMCs exposed to SNAP or infected with AdiNOS exhibited increased functional TF activity and antigen. Regardless of the source of NO, a time-dependent and concentration-dependent increase in TF activity was observed. Steady-state TF mRNA levels were also increased by NO delivered via either method. NFκB nuclear binding activity was also increased by NO. Inhibition of NFκB activity by either pyrrolidine dithiocarbamate treatment or mutant IκB transduction abrogated NO-induced enhancement of TF mRNA and functional activity. Conclusion: In RASMC, NO exposure results in upregulation of TF functional activity, antigen, and mRNA. This effect appears to be mediated by an NFκB-dependent pathway. (J Vasc Surg 2003;37:650-9.)

Objective: The purpose of this study was to delineate the natural history of claudication and determine risk factors for ischemic rest pain (IRP) and ischemic ulceration (IU) among patients with claudication. Methods: We prospectively collected data on 1244 men with claudication during a 15-year period, including demographics, clinical risk factors, and ankle-brachial index (ABI). We followed these patients serially with ABIs, self-reported walking distance (WalkDist), and monitoring for IRP and IU. We used Kaplan-Meier and proportional hazards modeling to find independent predictors of IRP and IU. Results: Mean follow-up was 45 months; statistically valid follow-up could be carried out for as long as 12 years. ABI declined an average of 0.014 per year. WalkDist declined at an average rate of 9.2 yards per year. The cumulative 10-year risks of development of IU and IRP were 23% and 30%, respectively. In multivariate analysis using several clinical risk factors, we found that only DM (relative risk [RR], 1.8) and ABI (RR, 2.2 for 0.1 decrease in ABI) predicted the development of IRP. Similarly, only DM (RR, 3.0) and ABI (RR, 1.9 for 0.1 decrease in ABI) were significant predictors of IU. Conclusion: This large serial study of claudication is, to our knowledge, the longest of its kind. We documented an average rate of ABI decline of 0.014 per year and a decline in WalkDist of 9.2 yards per year. Two clinical factors, ABI and DM, were found to be associated with the development of IRP and IU. Our findings may be useful in predicting the clinical course of claudication. (J Vasc Surg 2001;34:962-70.)

Objective: The purpose of this study was to delineate the natural history of claudication and determine risk factors for death. Methods: We reviewed the key outcomes (death, revascularization, amputation) in 2777 male patients with claudication identified over 15 years at a Veterans Administration hospital with both clinical and noninvasive criteria. Patients with rest pain or ulcers were excluded. Data were analyzed with life-table and Cox hazard models. Results: The mean follow-up was 47 months. The cohort exhibited a mortality rate of 12% per year, which was significantly (P

Introduction: Postoperative care after infrarenal abdominal aortic aneurysm (AAA) repair has traditionally involved admission to the intensive care unit (ICU). With the advent of endovascular AAA repair, the management of open procedures has received increased scrutiny. We recently modified our AAA clinical pathway to include selective use of the ICU. Methods: Consecutive elective infrarenal AAA repairs performed by members of the vascular surgery division at a university medical center from 1994 to 1999 were analyzed retrospectively with a computerized database, the Medical Archival Retrieval System. Group I consisted of 245 patients who were treated in the ICU for 1 or more days, and Group II included 69 patients admitted directly to the floor. Ruptured, symptomatic, suprarenal, endovascular, and reoperative repairs were excluded. Outcome variables were compared over the 6-year period. Results: Floor admissions increased over the study period with 0%, 0%, 3.3%, 16.3%, 48.6%, and 43.6% of patients admitted directly to the surgery ward from 1994 to 1999. The average ICU length of stay declined from 4.6 to 1.2 days, whereas the hospital length of stay decreased from 12.5 to 6.8 days from 1994 to 1999. The change in ICU use had no effect on death (2.4% in Group I vs 0% in Group II). Major and minor morbidity was comparable. Hospital charges were significantly lower for patients in Group II. Conclusion: A policy of selective utilization of the ICU after elective infrarenal AAA repair is safe. It can reduce resource use without a negative impact on the quality of care. (J Vasc Surg 2000;32:634-42.)

Objective: The compression of femoral artery pseudoaneurysms is a time consuming, painful, and sometimes unsuccessful procedure. Thrombin injection has been advocated as a superior alternative. In this study, we compare our experiences with both techniques. Methods: All the records of femoral artery false aneurysms that were treated in the vascular laboratory from January 1996 to April 1999 were retrospectively reviewed. Treatment with ultrasound scan–guided compression was compared with treatment with dilute thrombin injection (100 U/mL). Results: Both groups had similar demographics and aneurysm sizes ( P > .2). Of the pseudoaneursyms, 88% were caused by cardiac catheterization and the others were the results of femoral artery access for cardiac surgery (6%), arteriography (5%), and renal dialysis (1%). Compression was successful in 25 of 40 patients (63%). Nine persistent aneurysms necessitated operation, and six were treated successfully with thrombin injection. Primary thrombin injection successfully obliterated 21 pseudoaneurysms in 23 patients. Overall, 27 of 29 pseudoaneurysms were treated successfully with thrombin injection (93%). Thrombosis occurred within seconds of the thrombin injection and required, on average, 300 units of thrombin (100 to 600 units). The patients who underwent successful compression required an average of 37 minutes of compression (range, 5 to 70 minutes) and required analgesia on several occasions. No patients in the thrombin group required analgesia or sedation. Neither group had complications. A cost analysis shows that thrombin treatment results in considerable savings in vascular laboratory resource use but not in overall hospital expenditures. Conclusion: Ultrasound scan–guided thrombin injection is a safe, fast, and painless procedure that completely obliterates femoral artery pseudoaneurysms. The shift from compressive therapy to thrombin injection reduces vascular laboratory use and is less expensive, although it does not significantly impact hospital costs. (J Vasc Surg 1999;30:1052-9.)

Background: Severe oxygen-dependent chronic obstructive pulmonary disease (COPD) is considered by many to be a contraindication to open abdominal aortic aneurysm (AAA) repair. We reviewed our own experience with this patient population. Methods: From July 1995 to March 1999, 14 consecutive patients limited by home oxygen-dependent COPD underwent elective open infrarenal AAA repair. Their medical records were reviewed. Results: The mean aortic aneurysm size was 6.3 cm. The mean PaO 2 = 70 mm Hg, PaCO 2 = 45 mm Hg, forced expiratory volume in 1 second (FEV 1 ) = 34% of predicted, and forced vital capacity (FVC) = 67% of predicted. All 14 patients were extubated within 24 hours, mean length of hospital stay was 5.9 days, and there were no perioperative deaths. Conclusions: Severe home oxygen-dependent COPD is not a contraindication to safe elective open AAA repair.

Ruptured abdominal aortic aneurysm (RAAA) is a lethal disease. The aim of this study was to assess resource use, long-term outcome, and functional status of patients surviving repair of RAAAs. A retrospective review was made over a 42-month period. Functional status was assessed by use of the Medical Outcomes Study Short Form 36 (MOS SF-36) at a mean follow-up time of 29 months. Fifty-seven patients with an RAAA underwent surgical repair. The overall in-hospital mortality rate after surgical repair was 39%. Risk factors predictive for a poor hospital outcome were preoperative systolic blood pressure less than 90 mmHg, hematocrit less than 25%, transfusion requirements greater than 15 units, renal failure, and need for perioperative cardiopulmonary resuscitation (CPR). Total hospital costs were significantly higher for survivors compared with nonsurvivors. Hospital cost per survivor was $86,977. Intensive Care Unit, laboratory, and blood bank costs accounted for 50% of total hospital costs. Based on the eight domains of the MOS SF-36, no significant difference was found between the functional status of those patients surviving emergent repair of RAAAs and that of the general population of a similar age.

Background: Endovascular repair of abdominal aortic aneurysms (AAA) is gaining momentum although it is not yet approved in the United States by regulatory agencies. The Endovascular Grafting System (EGS), the first device to enter clinical trials in 1993, is now in phase III testing. Methods: We reviewed the first 50 patients to undergo an EGS repair of AAA over 24 months at our institution. Results were compared with 69 patients who underwent open repair during the same time period by the same surgeon. Results: Devices were successfully implanted in 47 of 50 (94%) patients. Three were converted to standard repair. Although length of stay was shorter, costs were similar. Follow-up was 3 to 24 months. Perigraft flow was noted in 33% at discharge; 73% of those stopped either spontaneously or with coiling. Three graft limbs occluded, requiring thrombolytic therapy. Conclusions: The EGS repair of AAA is feasible and effective. Cooperation between surgery and radiology is important for the success of a new endovascular program.

Clinical management of abdominal aortic aneurysms (AAA) can benefit from patient-specific computational biomechanics-based assessment of the disease. Individual variations in shape and aortic material properties are expected to influence the assessment of AAA wall mechanics. While patient-specific geometry can be reproduced using medical images, the accurate individual and regionally varying tissue material property estimation is currently not feasible. This work addresses the relative uncertainties arising from variations in AAA material properties and its effect on the ensuing wall mechanics. Computational simulations were performed with five different isotropic material models based on an ex-vivo AAA wall material characterization and a subject population sample of 28 individuals. Care was taken to exclude the compounding effects of variations in all other geometric and biomechanical factors. To this end, the spatial maxima of the principal stress (σ max), principal strain (e max), strain-energy density (ψ max), and displacement (δ max) were calculated for the diameter-matched cohort of 28 geometries for each of the five different constitutive materials. This led to 140 quasi-static simulations, the results of which were assessed on the basis of intra-patient (effect of material constants) and inter-patient (effect of individual AAA shape) differences using statistical averages, standard deviations, and Box and Whisker plots. Mean percentage variations for σ max, e max, ψ max, and δ max for the intra-patient analysis were 1.5, 7.1, 8.0, and 6.1, respectively, whereas for the inter-patient analysis these were 11.1, 4.5, 15.3, and 12.9, respectively. Changes in the material constants of an isotropic constitutive model for the AAA wall have a negligible influence on peak wall stress. Hence, this study endorses the use of population-averaged material properties for the purpose of estimating peak wall stress, strain-energy density, and wall displacement. Conversely, strain is more dependent on the material constant variation than on the differences in AAA shape in a diameter-matched population cohort.

Abdominal Aortic Aneurysm (AAA) is a localized permanent dilatation occurring in abdominal region of the aorta. Nearly 8% of the population above 65 years old is diagnosed with this disease [1], which has been shown to be associated with smoking history, heredity, and male gender. As it is asymptomatic, vascular surgeons may opt for surgical intervention or follow a wait-and-watch strategy if their assessment of the risk of rupture is low. During surgical intervention grafts are placed inside the aorta. Design of such intravascular devices as well as monitoring the progression of the disease by means of scientific approach may benefit from information on the strains that occur in the aneurysmatic region at different instances due to cyclic internal pressurization during cardiac cycle.Copyright © 2013 by ASME

The current clinical management of abdominal aortic aneurysm (AAA) disease is based to a great extent on measuring the aneurysm maximum diameter to decide when timely intervention is required. Decades of clinical evidence show that aneurysm diameter is positively associated with the risk of rupture, but other parameters may also play a role in causing or predisposing the AAA to rupture. Geometric factors such as vessel tortuosity, intraluminal thrombus volume, and wall surface area are implicated in the differentiation of ruptured and unruptured AAAs. Biomechanical factors identified by means of computational modeling techniques, such as peak wall stress, have been positively correlated with rupture risk with a higher accuracy and sensitivity than maximum diameter alone. In the present work, we performed a controlled study targeted at evaluating the effect of uncertainty of the constitutive material model used for the vascular wall in the ensuing peak wall stress. Based on the outcome of this study, a second analysis was conducted based on the geometric characterization of surface curvature in two groups of aneurysm geometries, to discern which curvature metric can adequately discriminate ruptured from electively repaired AAA. The outcome of this work provides preliminary evidence on the importance of quantitative geometry characterization for AAA rupture risk assessment in the clinic.Copyright © 2013 by ASME

Abdominal aortic aneurysm (AAA) is an irreversible, localized growth, typically in the infrarenal region of the aorta. Nearly 8% of the population above 65 years old is diagnosed with this disease [1], which has been shown to be associated with smoking history, heredity, and male gender. As it is asymptomatic, vascular surgeons may opt for surgical intervention or follow a wait-and-watch strategy if their assessment of the risk of rupture is low. Different criteria, such as maximum diameter, growth rate, wall stiffness, thickness of intraluminal thrombus (ILT), wall tension, etc., have been proposed for predicting rupture risk [2], which should be weighed against the risk of surgery, given that most AAA patients are elderly. The maximum diameter criterion is widely used in clinical practice [3], with the threshold diameter for decision making (typically 5.5 cm) following an evidence-based approach. However, an autopsy study of 473 AAA cases found that 13% of aneurysms 5 cm in diameter or smaller ruptured, whereas 60% of aneurysms of diameter greater than 5 cm did not [4]. Diameter-based rules for rupture prediction fail for 10%–25% patients in small and large AAA [5]. Hence, there is a clear need to accurately assess rupture risk on a patient-specific basis by using more rigorous, scientific means. A biomechanics-based approach can be helpful toward achieving this goal by accurately modeling the individual AAA geometry. Wall thickness is an important geometry variable that can potentially increase the accuracy of AAA biomechanical analysis. Rupture is a local phenomenon that should be assessed by modeling spatially varying local geometry, thereby eliminating the role of globally defined criteria, such as diameter and sac volume for patient-specific rupture risk analysis. Vascular wall thickness is believed to be an influential geometric feature for biomechanical stress evaluation. From a mechanics perspective, the shape of an aneurysm and the thickness of the artery should govern dominantly the stress distribution compared to the overall size of the aneurysm [6]. Acknowledging that there are limitations inherent to image acquisition sequences and resolution, deriving accurate segmentation and geometric modeling algorithms are highlighted as open problems in computational vascular biomechanics [7]. Thickness, nonlinear material behavior, strength of the AAA wall, and the spatial distribution of these variables are said to be essential for achieving accurate finite element (FE) simulations and, therefore, also for a realistic prediction of AAA rupture risk [8,9]. Few studies report experimental measurements of aneurysmatic wall thickness [10–12,33] and with large differences in their findings, as described in Table ​Table1.1. The autopsy-based observation that AAA rupture location occurs mostly on the posterior wall [4] is in agreement with the finding by Raghavan et al. [11] that wall thickness is slightly less in the posterior region compared to the anterior region. It should be noted that the severity of a posterior wall rupture is relatively less than that of an anterior wall rupture. Hence, it is more likely that posterior wall rupture cases are documented in the medical literature, since a patient with anterior wall rupture may not reach a hospital alive, thereby compounding the aforementioned observations. In a healthy aorta, the anterior wall is thicker than the posterior [10] and with a mean wall thickness of 1.39 mm [13]. The challenge of estimating regional variations of wall thickness and the subsequent incorporation in FE analysis is a complex one. Hence, the assumption of a uniform wall thickness in numerical models reported in the literature is questionable, and there is need for addressing whether the regional variations are needed on a patient-specific basis. To that end, Martufi et al. [14] reported the validation of a set of matlab routines for estimating regional vessel wall thickness from CT images by comparing it with postmortem AAA tissue measurements [11], resulting in an average relative difference of 7.8%. A framework for semiautomatic vessel wall detection and quantification of thickness using contrast-enhanced CT images was described by Shum et al. [15], resulting in low repeatability and reproducibility errors when compared to the manual segmentations performed by trained vascular surgeons. Quantitative assessment of AAA geometry [16] has shown promising results, with wall thickness being one of the morphological indicators significant for rupture risk stratification. These developments are paving the way for noninvasive, automatic geometric assessment of AAAs yielding population stratification in clinical practice. Table 1 Brief summary of previously reported experimental measurements on wall thickness (eAAA—electively repaired AAA; rAAA—ruptured AAA)

Rupture risk assessment of abdominal aortic aneurysms (AAA) by means of biomechanical analysis is a viable alternative to the traditional clinical practice of using a critical diameter for recommending elective repair. However, an accurate prediction of biomechanical parameters, such as mechanical stress, strain, and shear stress, is possible if the AAA models and boundary conditions are truly patient specific. In this work, we present a complete fluid-structure interaction (FSI) framework for patient-specific AAA passive mechanics assessment that utilizes individualized inflow and outflow boundary conditions. The purpose of the study is two-fold: (1) to develop a novel semiautomated methodology that derives velocity components from phase-contrast magnetic resonance images (PC-MRI) in the infrarenal aorta and successfully apply it as an inflow boundary condition for a patient-specific fully coupled FSI analysis and (2) to apply a one-way–coupled FSI analysis and test its efficiency compared to transient computational solid stress and fully coupled FSI analyses for the estimation of AAA biomechanical parameters. For a fully coupled FSI simulation, our results indicate that an inlet velocity profile modeled with three patient-specific velocity components and a velocity profile modeled with only the axial velocity component yield nearly identical maximum principal stress (σ1), maximum principal strain (ε1), and wall shear stress (WSS) distributions. An inlet Womersley velocity profile leads to a 5% difference in peak σ1, 3% in peak ε1, and 14% in peak WSS compared to the three-component inlet velocity profile in the fully coupled FSI analysis. The peak wall stress and strain were found to be in phase with the systolic inlet flow rate, therefore indicating the necessity to capture the patient-specific hemodynamics by means of FSI modeling. The proposed one-way–coupled FSI approach showed potential for reasonably accurate biomechanical assessment with less computational effort, leading to differences in peak σ1, ε1, and WSS of 14%, 4%, and 18%, respectively, compared to the axial component inlet velocity profile in the fully coupled FSI analysis. The transient computational solid stress approach yielded significantly higher differences in these parameters and is not recommended for accurate assessment of AAA wall passive mechanics. This work demonstrates the influence of the flow dynamics resulting from patient-specific inflow boundary conditions on AAA biomechanical assessment and describes methods to evaluate it through fully coupled and one-way–coupled fluid-structure interaction analysis.

Summary The patient with chronic limb ischemia requires careful evaluation to determine the need for either medical therapy alone, or for both medical therapy and revascularization. With judicious use of angiography and proper selection of the method of revascularization, excellent operative results with good long-term graft patency can be achieved.

The current clinical management of abdominal aortic aneurysm (AAA) disease is based to a great extent on measuring the aneurysm maximum diameter to decide when timely intervention is required. Decades of clinical evidence show that aneurysm diameter is positively associated with the probability of rupture, but that other parameters may also play a role in causing or predisposing the AAA to rupture. Biological factors associated with smooth muscle apoptosis are implicated in AAA expansion while geometric and biomechanical factors identified by means of computational modeling techniques have been positively correlated with rupture risk with a higher accuracy and sensitivity than maximum diameter alone. The objective of this review is to examine the factors found to influence AAA disease progression, clinical management and rupture, as well as a patent review that highlights developments in this arena in the past few years.

Background Complicated skin and skin structure infections (cSSSIs) frequently result in hospitalization with significant morbidity and mortality. Methods In this phase 3b/4 parallel, randomized, open-label, comparative study, 531 subjects with cSSSI received tigecycline (100 mg initial dose, then 50 mg intravenously every 12 hrs) or ampicillin-sulbactam 1.5-3 g IV every 6 hrs or amoxicillin-clavulanate 1.2 g IV every 6-8 hrs. Vancomycin could be added at the discretion of the investigator to the comparator arm if methicillin-resistant Staphylococcus aureus (MRSA) was confirmed or suspected within 72 hrs of enrollment. The primary endpoint was clinical response in the clinically evaluable (CE) population at the test-of-cure (TOC) visit. Microbiologic response and safety were also assessed. The modified intent-to-treat (mITT) population comprised 531 subjects (tigecycline, n = 268; comparator, n = 263) and 405 were clinically evaluable (tigecycline, n = 209; comparator, n = 196). Results In the CE population, 162/209 (77.5%) tigecycline-treated subjects and 152/196 (77.6%) comparator-treated subjects were clinically cured (difference 0.0; 95% confidence interval [CI]: -8.7, 8.6). The eradication rates at the subject level for the microbiologically evaluable (ME) population were 79.2% in the tigecycline treatment group and 76.8% in the comparator treatment group (difference 2.4; 95% CI: -9.6, 14.4) at the TOC assessment. Nausea, vomiting, and diarrhea rates were higher in the tigecycline group. Conclusions Tigecycline was generally safe and effective in the treatment of cSSSIs. Trial registration ClinicalTrials.gov NCT00368537

Rupture of abdominal aortic aneurysm (AAA) is the 10th leading cause of death for men over age of 50 in US. The decision for surgical intervention is currently based on aneurysm diameter or its expansion rate. However, the use of these criteria for all patients is debatable. For example, small aneurysms do rupture or become symptomatic before reaching the critical diameter. Computationally predicted mechanical wall stress is considered a viable alternative criterion for rupture risk assessment. Hence, it is important to evaluate the effect of different modeling approaches on the accuracy of the predicated AAA wall stress. For computational solid stress (CSS) analysis or finite element analysis (FEA), a uniform static or transient intraluminal pressure is generally applied on the wall-lumen surface whereas in fluid-structure interaction (FSI) modeling the wall-lumen surface experiences transient and non-uniform fluid stress. An earlier comparison on idealized AAA models [1] revealed that static and transient CSS underestimate the peak wall stress (PWS) by an average 20–30% for variable wall thickness and 10% for uniform wall thickness when compared to fully coupled FSI. However, FSI-predicted stresses and strains were observed to be sensitive to inflow and outflow boundary conditions, warranting further study on a more accurate approach for FSI modeling. Though significant work has been performed on modeling outflow boundary conditions [2], studies on the sensitivity of computed stress or strain to the type of FSI inflow boundary condition is scarce [2–4]. We hypothesize that a FSI framework with a patient specific velocity boundary condition derived from magnetic resonance imaging (MRI) data applied to patient specific AAA geometry would provide better accuracy of PWS calculations compared to a FEA model. In this work, we present a framework where the AAA geometry is reconstructed from computed tomography (CT) images, on which FSI simulations were performed with inlet velocity components extracted from patient MR images of the abdominal aorta. Fully coupled FSI simulations were performed and results were compared with CSS simulations with uniform transient pressure boundary conditions.Copyright © 2012 by ASME

Data mining techniques are capable of extracting important relationships and correlations among large amounts of data while machine learning methodologies can utilize these correlations to generate models capable of classification and prediction. The combination of machine learning and data mining is an important contribution of the present work for two reasons: (1) given a large database of features that describe the geometry of native abdominal aortic aneurysms (AAAs), patterns and relationships in the data are derived that may not be apparent to the human eye, and (2) statistical models are generated that can classify new data and determine which features discriminate among different aneurysm populations. The objectives of this study were to use anatomically realistic AAA models to evaluate a proposed set of global geometric indices describing the size, shape and individual wall thickness of the aneurysm sac, and use a learning algorithm to develop a model that is capable of discriminating the rupture status of these aneurysms.Copyright © 2012 by ASME

A localized dilatation of the abdominal aorta is termed an abdominal aortic aneurysm (AAA). The rupture of AAAs continues to be a leading cause of morbidity and mortality in the United States, especially in patients older than 65 years of age. If an AAA ruptures, 50% of the patients will die prior to reaching the hospital. Of those patients that reach the operating room, only 50% will successfully have the aneurysm repaired [1]. In an effort to prevent rupture, patients with known AAA undergo periodic abdominal ultrasound or CT scan surveillance. When the aneurysm grows to a diameter of 5.0–5.5 cm or is shown to expand at a rate greater than 1 cm/yr, elective operative repair is undertaken. While this strategy certainly prevents a number of potentially catastrophic ruptures, AAA rupture can occur at sizes less than 5 cm. From a biomechanical standpoint, aneurysm rupture occurs when wall stress exceeds wall strength. By using noninvasive techniques, such as finite element analysis (FEA), wall stress can be estimated for patient specific AAA models, which can perhaps more carefully predict the rupture potential of a given aneurysm, regardless of size. FEA is a computational method that can be used to evaluate complicated structures such as aneurysms. To this end, it was reported earlier that AAA peak wall stress provides a better assessment of rupture risk than the commonly used maximum diameter criterion [2]. What has yet to be examined; however, is the relationship between wall stress and AAA geometry during aneurysm growth. Such a finding has the potential for providing individualized predictions of AAA rupture potential during patient surveillance. The purpose of this investigation is to estimate peak wall stress for a case study of one AAA under surveillance and evaluate its potential correlation with geometric features characteristic of the aneurysm's morphology.

In an effort to prevent rupture, patients with known AAA undergo periodic abdominal ultrasound or CT scan surveillance. When the aneurysm grows to a diameter of 5.0–5.5 cm or is shown to expand at a rate greater than 1 cm/yr, elective operative repair is undertaken. While this strategy certainly prevents a number of potentially catastrophic ruptures, AAA rupture can occur at sizes less than 5 cm. From a biomechanical standpoint, aneurysm rupture occurs when wall stress exceeds wall strength. By using non-invasive techniques, such as finite element analysis (FEA), wall stress can be estimated for patient specific AAA models, which can perhaps more carefully predict the rupture potential of a given aneurysm, regardless of size. FEA is a computational method that can be used to evaluate complicated structures such as aneurysms. To this end, it was reported earlier that AAA peak wall stress provides a better assessment of rupture risk than the commonly used maximum diameter criterion [1]. What has yet to be examined, however, is the relationship between wall stress and AAA geometry during aneurysm growth. Such finding has the potential for providing individualized predictions of AAA rupture potential during patient surveillance. The purpose of this study is to estimate peak wall stress for an AAA under surveillance and evaluate its potential correlation with geometric features characteristic of the aneurysm’s morphology.Copyright © 2011 by ASME

indices that describe the size, shape, curvature, and regional variations Recent clinical studies have shown that the maximum transverse diameter of an abdominal aortic aneurysm (AAA) alone, or in combination with its expansion rate are not entirely reliable indicators of rupture potential. We hypothesize that AAA shape, size, and wall thickness may be related to rupture risk and can be deciding factors in the clinical management of the disease. A non-invasive, image-based evaluation of AAA size and geometry was implemented using an in-house code (AAAVASC v1.0, Carnegie Mellon University) on a retrospective study of 88 subjects. The contrast enhanced, computed tomography (CT) scans of 44 .patients who suffered AAA rupture within 1 month of the scan were compared to those of 44 patients who received elective repair. The images were segmented and three-dimensional models were generated. Twenty-eight geometry-based indices were calculated to characterize the size and shape of each AAA and estimate regional variations in wall thickness. A multivariate analysis of variance was performed for all indices comparing the ruptured and non-ruptured data sets to determine which indices were statistically significant. A classification model was created using a J48 decision tree algorithm and its performance was assessed using 10-fold cross validation. The model correctly classified eighty-six data sets and had an average prediction accuracy of 74% ( Figure 1. Flowchart = 0.69). Such a decision model can be used in a clinical setting to assess the risk of AAA rupture with minimal user intervention.

Background To evaluate our experience with staged carotid endarterectomy (CEA) followed by coronary artery bypass grafting (CABG) within the perioperative period for patients with severe carotid and coronary artery disease. Methods From 1998 to August of 2010, 40 patients who were referred for isolated coronary surgery were found to have significant carotid disease. All patients underwent CEA followed by subsequent CABG within 30 days of the CEA. Severe carotid stenosis was defined as >70%. Results Average patient age was 65.5 ± 10.6 years and 32 (80%) were male. Severe carotid stenosis was unilateral in 37 of the patients, bilateral in 3, and asymptomatic in 37. Patients underwent CEA with either patch angioplasty or eversion technique. General anesthesia with selective shunting was used in all cases. There were zero deaths, zero strokes, and one myocardial infarction (MI) (2.5%) immediately after CEA. After CEA, CABG was performed within 30 days. The average interval between procedures was 6.87 days. There were two (5.0%) deaths, one from MI and the other from multisystem organ failure. There were two strokes (5.0%), with one having permanent effects. The perioperative mortality, stroke, and MI rates after both operations were 5.0%, 5.0%, and 5.0%, respectively. Conclusions Staging of CEA followed by CABG in the immediate perioperative period may be an acceptable approach to patients with severe carotid and coronary disease. Despite the presence of known severe coronary disease, the performance of CEA under general anesthesia as the initial procedure was well tolerated. We propose that this strategy may be a possible option for patients who present with severe disease in both coronary and carotid distributions. The results of our study, though based on a limited cohort, suggest that this approach of staged CEA–CABG within the perioperative period

Recent studies have shown that the maximum transverse diameter of an abdominal aortic aneurysm (AAA) and expansion rate are not entirely reliable indicators of rupture potential. We hypothesize that aneurysm morphology and wall thickness can be quantified in a systematic approach leading to accurate differentiation of the geometric characteristics of aneurysm population subsets. A non-invasive, image-based evaluation of AAA shape was implemented on a retrospective study of sixty-six subjects who underwent elective repair and twenty-eight subjects who suffered AAA rupture within 1 month of their last pre-operative follow-up. The contrast-enhanced computed tomography (CT) scans of these patients were used to generate three-dimensional models from the segmented images. Twenty-eight geometry-based indices were calculated to characterize the size and shape of the AAA sac, and regional variations in wall thickness were estimated based on a novel segmentation algorithm. A multivariate analysis of variance using a maximum AAA diameter of 5.5 cm as a factor was performed for all indices as dependent variables, for the electively repaired group. Box and Whisker plots and ROC curves were generated to determine the indices’ potential as predictors of rupture risk. Listed from highest to lowest area under the ROC curve (AUC), the following six indices were found statistically significant (p < 0.05): volume (V, p < 0.0001), surface area (S, p < 0.0001), intraluminal thrombus volume (VILT, p < 0.0001), diameter-to-diameter ratio (DDr, p < 0.0001), diameter-to-height ratio (DHr, p = 0.015), and centroid distance of the maximum diameter (dc, p = 0.008). Given that individual AAAs have complex, tortuous and asymmetric shapes with local changes in surface curvature and wall thickness, the assessment of AAA rupture risk should require the accurate characterization of aneurysmal sac shape.

Background: Aberrant right subclavian artery (ARSA) is the most common congenital arch anomaly, which can be complicated by aneursymal dilation at its ostium. We describe a successful repair of an ARSA with a three-stage operative procedure using a left carotid to subclavian bypass, coiling of the ARSA, and thoracic endovascular aortic repair with long-term clinical and radiographic follow-up. (J Card Surg 2010;25:390-393)