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  1. A geometric scaling model for assessing the impact of aneurysm size ratio on hemodynamic characteristics

    PubMed Central

    2014-01-01

    Background The intracranial aneurysm (IA) size has been proved to have impacts on the hemodynamics and can be applied for the prediction of IA rupture risk. Although the relationship between aspect ratio and hemodynamic parameters was investigated using real patients and virtual models, few studies focused on longitudinal experiments of IAs based on patient-specific aneurysm models. We attempted to do longitudinal simulation experiments of IAs by developing a series of scaled models. Methods In this work, a novel scaling approach was proposed to create IA models with different aneurysm size ratios (ASRs) defined as IA height divided by average neck diameter from a patient-specific aneurysm model and the relationship between the ASR and hemodynamics was explored based on a simulated longitudinal experiment. Wall shear stress, flow patterns and vessel wall displacement were computed from these models. Pearson correlation analysis was performed to elucidate the relationship between the ASR and wall shear stress. The correlation of the ASR and flow velocity was also computed and analyzed. Results The experiment results showed that there was a significant increase in IA area exposed to low WSS once the ASR > 0.7, and the flow became slower and the blood was more difficult to flow into the aneurysm as the ASR increased. Meanwhile, the results also indicated that average blood flow velocity and WSS had strongly negative correlations with the ASR (r = −0.938 and −0.925, respectively). A narrower impingement region and a more concentrated inflow jet appeared as the ASR increased, and the large local deformation at aneurysm apex could be found as the ASR >1.7 or 0.7 < the ASR <1.0. Conclusion Hemodynamic characteristics varied with the ASR. Besides, it is helpful to further explore the relationship between morphologies and hemodynamics based on a longitudinal simulation by building a series of patient-specific aneurysm scaled models applying our proposed IA

  2. Assessment Of Coronary Artery Aneurysms Using Transluminal Attenuation Gradient And Computational Modeling In Kawasaki Disease Patients

    NASA Astrophysics Data System (ADS)

    Grande Gutierrez, Noelia; Kahn, Andrew; Shirinsky, Olga; Gagarina, Nina; Lyskina, Galina; Fukazawa, Ryuji; Owaga, Shunichi; Burns, Jane; Marsden, Alison

    2015-11-01

    Kawasaki Disease (KD) can result in coronary artery aneurysms (CAA) in up to 25% of patients, putting them at risk of thrombus formation, myocardial infarction and sudden death. Clinical guidelines recommend CAA diameter >8 mm as the arbitrary criterion for initiating systemic anticoagulation. KD patient specific modeling and flow simulations suggest that hemodynamic data can predict regions at increased risk of thrombosis. Transluminal Attenuation Gradient (TAG) is determined from the change in radiological attenuation per vessel length and has been proposed as a non-invasive method for characterizing coronary stenosis from CT Angiography. We hypothesized that CAA abnormal flow could be quantified using TAG. We computed hemodynamics for patient specific coronary models using a stabilized finite element method, coupled numerically to a lumped parameter network to model the heart and vascular boundary conditions. TAG was quantified in the major coronary arteries. We compared TAG for aneurysmal and normal arteries and we analyzed TAG correlation with hemodynamic and geometrical parameters. Our results suggest that TAG may provide hemodynamic data not available from anatomy alone. TAG represents a possible extension to standard CTA that could help to better evaluate the risk of thrombus formation in KD.

  3. EXPERIMENTAL MODELLING OF AORTIC ANEURYSMS

    PubMed Central

    Doyle, Barry J; Corbett, Timothy J; Cloonan, Aidan J; O’Donnell, Michael R; Walsh, Michael T; Vorp, David A; McGloughlin, Timothy M

    2009-01-01

    A range of silicone rubbers were created based on existing commercially available materials. These silicones were designed to be visually different from one another and have distinct material properties, in particular, ultimate tensile strengths and tear strengths. In total, eleven silicone rubbers were manufactured, with the materials designed to have a range of increasing tensile strengths from approximately 2-4MPa, and increasing tear strengths from approximately 0.45-0.7N/mm. The variations in silicones were detected using a standard colour analysis technique. Calibration curves were then created relating colour intensity to individual material properties. All eleven materials were characterised and a 1st order Ogden strain energy function applied. Material coefficients were determined and examined for effectiveness. Six idealised abdominal aortic aneurysm models were also created using the two base materials of the study, with a further model created using a new mixing technique to create a rubber model with randomly assigned material properties. These models were then examined using videoextensometry and compared to numerical results. Colour analysis revealed a statistically significant linear relationship (p<0.0009) with both tensile strength and tear strength, allowing material strength to be determined using a non-destructive experimental technique. The effectiveness of this technique was assessed by comparing predicted material properties to experimentally measured methods, with good agreement in the results. Videoextensometry and numerical modelling revealed minor percentage differences, with all results achieving significance (p<0.0009). This study has successfully designed and developed a range of silicone rubbers that have unique colour intensities and material strengths. Strengths can be readily determined using a non-destructive analysis technique with proven effectiveness. These silicones may further aid towards an improved understanding of the

  4. Lessons from Animal Models of Arterial Aneurysm

    PubMed Central

    Gertz, S. David; Mintz, Yoav; Beeri, Ronen; Rubinstein, Chen; Gilon, Dan; Gavish, Leah; Berlatzky, Yacov; Appelbaum, Liat; Gavish, Lilach

    2013-01-01

    We review the results from the most common animal models of arterial aneurysm, including recent findings from our novel, laparoscopy-based pig model of abdominal aortic aneurysm, that contribute important insights into early pathogenesis. We emphasize the relevance of these findings for evaluation of treatment protocols and novel device prototypes for mechanism-based prevention of progression and rupture. PMID:26798701

  5. Aneurysm

    MedlinePlus

    ... is thought to play a role in abdominal aortic aneurysms. Atherosclerotic disease (cholesterol buildup in arteries) may also ... your risk of an aneurysm. Images Cerebral aneurysm Aortic aneurysm Intracerebellar hemorrhage - CT scan References Hauser SC. Vascular ...

  6. Steady flow in abdominal aortic aneurysm models.

    PubMed

    Budwig, R; Elger, D; Hooper, H; Slippy, J

    1993-11-01

    Steady flow in abdominal aortic aneurysm models has been examined for four aneurysm sizes over Reynolds numbers from 500 to 2600. The Reynolds number is based on entrance tube diameter, and the inlet condition is fully developed flow. Experimental and numerical methods have been used to determine: (i) the overall features of the flow, (ii) the stresses on the aneurysm walls in laminar flow, and (iii) the onset and characteristics of turbulent flow. The laminar flow field is characterized by a jet of fluid (passing directly through the aneurysm) surrounded by a recirculating vortex. The wall shear stress magnitude in the recirculation zone is about ten times less than in the entrance tube. Both wall shear stress and wall normal stress profiles exhibit large magnitude peaks near the reattachment point at the distal end of the aneurysm. The onset of turbulence in the model is intermittent for 2000 < Re < 2500. The results demonstrate that a slug of turbulence in the entrance tube grows much more rapidly in the aneurysm than in a corresponding length of uniform cross section pipe. When turbulence is present in the aneurysm the recirculation zone breaks down and the wall shear stress returns to a magnitude comparable to that in the entrance tube. PMID:8309237

  7. CFD-based Thrombotic Risk Assessment in Kawasaki Disease Patients with Coronary Artery Aneurysms

    NASA Astrophysics Data System (ADS)

    Sengupta, Dibyendu; Kung, Ethan; Kahn, Andrew; Burns, Jane; Marsden, Alison

    2012-11-01

    Coronary aneurysms occur in 25% of untreated Kawasaki Disease (KD) patients and put patients at increased risk for myocardial infarction and sudden death. Clinical guidelines recommend using aneurysm diameter >8 mm as the arbitrary criterion for treating with anti-coagulation therapy. This study uses patient-specific modeling to non-invasively determine hemodynamic parameters and quantify thrombotic risk. Anatomic models were constructed from CT angiographic image data from 5 KD aneurysm patients and one normal control. CFD simulations were performed to obtain hemodynamic data including WSS and particle residence times (PRT). Thrombosis was clinically observed in 4/9 aneurysmal coronaries. Thrombosed vessels required twice as many cardiac cycles (mean 8.2 vs. 4.2) for particles to exit, and had lower mean WSS (1.3 compared to 2.8 dynes/cm2) compared to vessels with non-thrombosed aneurysms of similar max diameter. 1 KD patient in the cohort with acute thrombosis had diameter < 8 mm. Regions of low WSS and high PRT predicted by simulations correlated with regions of subsequent thrombus formation. Thrombotic risk stratification for KD aneurysms may be improved by incorporating both hemodynamic and geometric quantities. Current clinical guidelines to assess patient risk based only on aneurysm diameter may be misleading. Further prospective study is warranted to evaluate the utility of patient-specific modeling in risk stratifying KD patients with coronary aneurysms. NIH R21.

  8. Using vortex corelines to analyze the hemodynamics of patient specific cerebral aneurysm models

    NASA Astrophysics Data System (ADS)

    Byrne, Greg; Mut, Fernando; Cebral, Juan

    2012-02-01

    We construct one-dimensional sets known as vortex corelines for computational fluid dynamic (CFD) simulations of blood flow in patient specific cerebral aneurysm models. These sets identify centers of swirling blood flow that may play an important role in the biological mechanisms causing aneurysm growth, rupture, and thrombosis. We highlight three specific applications in which vortex corelines are used to assess flow complexity and stability in cerebral aneurysms, validate numerical models against PIV-based experimental data, and analyze the effects of flow diverting devices used to treat intracranial aneurysms.

  9. Aneurysms

    MedlinePlus

    ... our e-newsletter! Aging & Health A to Z Aneurysms Basic Facts & Information Fill a balloon too full ... of what can happen when you have an aneurysm. Medically, when an artery “balloons,” or widens, it ...

  10. Experimental Models of Abdominal Aortic Aneurysms

    PubMed Central

    Tsui, Janice C

    2010-01-01

    Despite being a leading cause of death in the West, the pathophysiology of abdominal aortic aneurysms (AAA) is still incompletely understood. Pharmacotherapy to reduce the growth of small AAAs is limited and techniques for repairing aneurysms continue to evolve. Experimental models play a key role in AAA research, as they allow a detailed evaluation of the pathogenesis of disease progression. This review focuses on in vivo experimental models, which have improved our understanding of the potential mechanisms of AAA development and contributed to the advancement of new treatments. PMID:21270944

  11. LDV measurements in lateral model aneurysms of various sizes

    NASA Astrophysics Data System (ADS)

    Liou, T.-M.; Chang, W.-C.; Liao, C.-C.

    Laser Doppler velocimetry (LDV) measurements are presented of three-dimensional flow fields in lateral model aneurysms arising from a straight parent vessel at a 90° angle. The flow considered was pulsatile and the aneurysm wall was rigid. The mean, peak, and minimal Reynolds numbers based on the bulk average velocity and diameter of the parent vessel were 550, 790, and 375, respectively. Comparisons among present in vitro studies, previous in vitro studies, computational simulations, and in vivo studies were made. It was found that the inflow angle into the lateral aneurysm, the maximum wall shear stress acting on the distal lip of the lateral aneurysm, and the intra-aneurysmal vortical motion increased with decreasing aneurysm size. This fact together with the impingement bifurcation of the inflow at the aneurysm dome provide possible hemodynamic factors for the rupture of the lateral aneurysm at small critical size.

  12. Swine Hybrid Aneurysm Model for Endovascular Surgery Training

    PubMed Central

    Namba, K.; Mashio, K.; Kawamura, Y.; Higaki, A.; Nemoto, S.

    2013-01-01

    Summary The aim of this study was to develop a technically simple swine aneurysm-training model by inserting a silicone aneurysm circuit in the cervical vessels. A silicone aneurysm circuit was created by designing multiple aneurysms in size and configuration on a silicone vessel. Five swine underwent surgical implantation of this circuit in the cervical vessels: one end in the common carotid artery and the other in the external jugular vein. Using this model, an aneurysm coiling procedure was simulated under fluoroscopic guidance, roadmapping and digital subtraction angiography. Creating an aneurysm model for training purposes by this method was technically simple and enabled the formation of a wide variety of aneurysms in a single procedure. The quality of the model was uniform and the model was reproducible. Coiling training using this model resembled a realistic clinical situation. The swine hybrid aneurysm-training model was advantageous from the standpoint of technical simplicity in the creation and variety of aneurysms it provided. The swine hybrid aneurysm model may be an additional option for aneurysm coiling training. PMID:23693037

  13. Swine hybrid aneurysm model for endovascular surgery training.

    PubMed

    Namba, K; Mashio, K; Kawamura, Y; Higaki, A; Nemoto, S

    2013-06-01

    The aim of this study was to develop a technically simple swine aneurysm-training model by inserting a silicone aneurysm circuit in the cervical vessels. A silicone aneurysm circuit was created by designing multiple aneurysms in size and configuration on a silicone vessel. Five swine underwent surgical implantation of this circuit in the cervical vessels: one end in the common carotid artery and the other in the external jugular vein. Using this model, an aneurysm coiling procedure was simulated under fluoroscopic guidance, roadmapping and digital subtraction angiography. Creating an aneurysm model for training purposes by this method was technically simple and enabled the formation of a wide variety of aneurysms in a single procedure. The quality of the model was uniform and the model was reproducible. Coiling training using this model resembled a realistic clinical situation. The swine hybrid aneurysm-training model was advantageous from the standpoint of technical simplicity in the creation and variety of aneurysms it provided. The swine hybrid aneurysm model may be an additional option for aneurysm coiling training. PMID:23693037

  14. Constitutive modeling of ascending thoracic aortic aneurysms using microstructural parameters.

    PubMed

    Pasta, Salvatore; Phillippi, Julie A; Tsamis, Alkiviadis; D'Amore, Antonio; Raffa, Giuseppe M; Pilato, Michele; Scardulla, Cesare; Watkins, Simon C; Wagner, William R; Gleason, Thomas G; Vorp, David A

    2016-02-01

    Ascending thoracic aortic aneurysm (ATAA) has been associated with diminished biomechanical strength and disruption in the collagen fiber microarchitecture. Additionally, the congenital bicuspid aortic valve (BAV) leads to a distinct extracellular matrix structure that may be related to ATAA development at an earlier age than degenerative aneurysms arising in patients with the morphological normal tricuspid aortic valve (TAV). The purpose of this study was to model the fiber-reinforced mechanical response of ATAA specimens from patients with either BAV or TAV. This was achieved by combining image-analysis derived parameters of collagen fiber dispersion and alignment with tensile testing data. Then, numerical simulations were performed to assess the role of anisotropic constitutive formulation on the wall stress distribution of aneurysmal aorta. Results indicate that both BAV ATAA and TAV ATAA have altered collagen fiber architecture in the medial plane of experimentally-dissected aortic tissues when compared to normal ascending aortic specimens. The study findings highlight that differences in the collagen fiber distribution mostly influences the resulting wall stress distribution rather than the peak stress. We conclude that fiber-reinforced constitutive modeling that takes into account the collagen fiber defect inherent to the aneurysmal ascending aorta is paramount for accurate finite element predictions and ultimately for biomechanical-based indicators to reliably distinguish the more from the less 'malignant' ATAAs. PMID:26669606

  15. Computational Modeling of Flow-Altering Surgeries in Basilar Aneurysms

    PubMed Central

    Rayz, V. L.; Abla, A.; Boussel, L.; Leach, J. R.; Acevedo-Bolton, G.; Saloner, D.; Lawton, M. T.

    2014-01-01

    In cases where surgeons consider different interventional options for flow alterations in the setting of pathological basilar artery hemodynamics, a virtual model demonstrating the flow fields resulting from each of these options can assist in making clinical decisions. In this study, image-based computational fluid dynamics (CFD) models were used to simulate the flow in four basilar artery aneurysms in order to evaluate postoperative hemodynamics that would result from flow-altering interventions. Patient-specific geometries were constructed using MR angiography and velocimetry data. CFD simulations carried out for the preoperative flow conditions were compared to in vivo phase-contrast MRI measurements (4DFlowMRI) acquired prior to the interventions. The models were then modified according to the procedures considered for each patient. Numerical simulations of the flow and virtual contrast transport were carried out in each case in order to assess postoperative flow fields and estimate the likelihood of intra-aneurysmal thrombus deposition following the procedures. Postoperative imaging data, when available, were used to validate computational predictions. In two cases, where the aneurysms involved vital pontine perforator arteries branching from the basilar artery, idealized geometries of these vessels were incorporated into the CFD models. The effect of interventions on the flow through the perforators was evaluated by simulating the transport of contrast in these vessels. The computational results were in close agreement with the MR imaging data. In some cases, CFD simulations could help determine which of the surgical options was likely to reduce the flow into the aneurysm while preserving the flow through the basilar trunk. The study demonstrated that image-based computational modeling can provide guidance to clinicians by indicating possible outcome complications and indicating expected success potential for ameliorating pathological aneurysmal flow, prior

  16. The Asymmetric Vascular Stent: Efficacy in a rabbit aneurysm model

    PubMed Central

    Ionita, Ciprian N; Paciorek, Ann M; Dohatcu, Andreea; Hoffmann, Kenneth R; Bednarek, Daniel R; Kolega, John; Levy, Elad I; Hopkins, L. Nelson; Rudin, Stephen; Mocco, J.

    2009-01-01

    Background and Purpose Development of hemodynamic modifying devices to treat intracranial aneurysms (IAs) is an active area of research. The asymmetric vascular stent (AVS), a stent containing a low porosity patch, is such device. We evaluate AVS efficacy in an in vivo IA model. Methods We created twenty-four elastase rabbit model aneurysms: thirteen treated with the AVS, five treated with standard coronary stents, and six untreated controls. Four weeks following treatment, aneurysms underwent follow-up angiography, cone-beam micro-CT, histologic evaluation, and selective electron microscopy scanning. Results Four rabbits died early in the study: three during AVS treatment and one control (secondary to intra-procedural vessel injury and an unrelated tumor, respectively). AVS-treated aneurysms exhibited very weak or no aneurysm flow immediately after treatment and no flow in all aneurysms at follow-up. Stent-treated aneurysms showed flow both after treatment (5/5) and at follow-up (3/5). All control aneurysms remained patent during the study. Micro-CT scans showed: 9/9 of scanned AVS aneurysms were occluded, (6/9) AVSs were ideally placed and (3/9) the low porosity region partially covered the aneurysm neck; stent-treated aneurysms were 1/5 occluded, 2/5 patent, and 2/5 partially-patent. Histology results demonstrated: for AVS-treated aneurysms, advanced thrombus organization in the (9/9); for stent-treated aneurysms (1/4) no thrombus, (2/4) partially-thrombosed and (1/4) fully-thrombosed; for control aneurysms (4/4) no thrombus. Conclusion The use of AVSs shows promise as a viable new therapeutic in intracranial aneurysm treatment. These data encourage further investigation and provide substantial support to the AVS concept. PMID:19131663

  17. The Role of Geometric and Biomechanical Factors in Abdominal Aortic Aneurysm Rupture Risk Assessment

    PubMed Central

    Raut, Samarth S.; Chandra, Santanu; Shum, Judy; Finol, Ender A.

    2013-01-01

    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. The objective of this review is to examine these factors, which are found to influence AAA disease progression, clinical management and rupture potential, as well as to highlight on-going research by our group in aneurysm modeling and rupture risk assessment. PMID:23508633

  18. Morphology Parameters for Intracranial Aneurysm Rupture Risk Assessment

    PubMed Central

    Dhar, Sujan; Tremmel, Markus; Mocco, J; Kim, Minsuok; Yamamoto, Junichi; Siddiqui, Adnan H.; Hopkins, L. Nelson; Meng, Hui

    2008-01-01

    OBJECTIVE The aim of this study is to identify image-based morphological parameters that correlate with human intracranial aneurysm (IA) rupture. METHODS For 45 patients with terminal or sidewall saccular IAs (25 unruptured, 20 ruptured), three-dimensional geometries were evaluated for a range of morphological parameters. In addition to five previously studied parameters (aspect ratio, aneurysm size, ellipticity index, nonsphericity index, and undulation index), we defined three novel parameters incorporating the parent vessel geometry (vessel angle, aneurysm [inclination] angle, and [aneurysm-to-vessel] size ratio) and explored their correlation with aneurysm rupture. Parameters were analyzed with a two-tailed independent Student's t test for significance; significant parameters (P < 0.05) were further examined by multivariate logistic regression analysis. Additionally, receiver operating characteristic analyses were performed on each parameter. RESULTS Statistically significant differences were found between mean values in ruptured and unruptured groups for size ratio, undulation index, nonsphericity index, ellipticity index, aneurysm angle, and aspect ratio. Logistic regression analysis further revealed that size ratio (odds ratio, 1.41; 95% confidence interval, 1.03−1.92) and undulation index (odds ratio, 1.51; 95% confidence interval, 1.08−2.11) had the strongest independent correlation with ruptured IA. From the receiver operating characteristic analysis, size ratio and aneurysm angle had the highest area under the curve values of 0.83 and 0.85, respectively. CONCLUSION Size ratio and aneurysm angle are promising new morphological metrics for IA rupture risk assessment. Because these parameters account for vessel geometry, they may bridge the gap between morphological studies and more qualitative location-based studies. PMID:18797347

  19. Rheological Changes After Stenting of a Cerebral Aneurysm: A Finite Element Modeling Approach

    SciTech Connect

    Ohta, Makoto; Wetzel, Stephan G. Dantan, Philippe; Bachelet, Caroline; Lovblad, Karl O.; Yilmaz, Hasan; Flaud, Patrice; Ruefenacht, Daniel A.

    2005-12-15

    Hemodynamic changes in intracranial aneurysms after stent placement include the appearance of areas with stagnant flow and low shear rates. We investigated the influence of stent placement on blood flow velocity and wall shear stress of an intracranial aneurysm using a finite element modeling approach. To assess viscosity changes induced by stent placement, the rheology of blood as non-Newtonian fluid was taken into account in this model. A two-dimensional model with a parent artery, a smaller branching artery, and an aneurysm located at the bifurcation, before and after stent placement, was used for simulation. Flow velocity plots and wall shear stress before and after stent placement was calculated over the entire cardiac circle. Values for dynamic viscosity were calculated with a constitutive equation that was based on experimental studies and yielded a viscosity, which decreases as the shear rate increases. Stent placement lowered peak velocities in the main vortex of the aneurysm by a factor of at least 4 compared to peak velocities in the main artery, and it considerably decreased the wall shear stress of the aneurysm. Dynamic viscosity increases after stent placement persisted over a major part of the cardiac cycle, with a factor of up to 10, most pronounced near the dome of the aneurysm. Finite element modeling can offer insight into rheological changes induced by stent treatment of aneurysms and allows visualizing dynamic viscosity changes induced by stent placement.

  20. Thrombosis modeling in intracranial aneurysms: a lattice Boltzmann numerical algorithm

    NASA Astrophysics Data System (ADS)

    Ouared, R.; Chopard, B.; Stahl, B.; Rüfenacht, D. A.; Yilmaz, H.; Courbebaisse, G.

    2008-07-01

    The lattice Boltzmann numerical method is applied to model blood flow (plasma and platelets) and clotting in intracranial aneurysms at a mesoscopic level. The dynamics of blood clotting (thrombosis) is governed by mechanical variations of shear stress near wall that influence platelets-wall interactions. Thrombosis starts and grows below a shear rate threshold, and stops above it. Within this assumption, it is possible to account qualitatively well for partial, full or no occlusion of the aneurysm, and to explain why spontaneous thrombosis is more likely to occur in giant aneurysms than in small or medium sized aneurysms.

  1. A New Murine Model of Endovascular Aortic Aneurysm Repair

    PubMed Central

    Rouer, Martin; Meilhac, Olivier; Delbosc, Sandrine; Louedec, Liliane; Pavon-Djavid, Graciela; Cross, Jane; Legagneux, Josette; Bouilliant-Linet, Maxime; Michel, Jean-Baptiste; Alsac, Jean-Marc

    2013-01-01

    Endovascular aneurysm exclusion is a validated technique to prevent aneurysm rupture. Long-term results highlight technique limitations and new aspects of Abdominal aortic aneurysm (AAA) pathophysiology. There is no abdominal aortic aneurysm endograft exclusion model cheap and reproducible, which would allow deep investigations of AAA before and after treatment. We hereby describe how to induce, and then to exclude with a covered coronary stentgraft an abdominal aortic aneurysm in a rat. The well known elastase induced AAA model was first reported in 19901 in a rat, then described in mice2. Elastin degradation leads to dilation of the aorta with inflammatory infiltration of the abdominal wall and intra luminal thrombus, matching with human AAA. Endovascular exclusion with small covered stentgraft is then performed, excluding any interactions between circulating blood and the aneurysm thrombus. Appropriate exclusion and stentgraft patency is confirmed before euthanasia by an angiography thought the left carotid artery. Partial control of elastase diffusion makes aneurysm shape different for each animal. It is difficult to create an aneurysm, which will allow an appropriate length of aorta below the aneurysm for an easy stentgraft introduction, and with adequate proximal and distal neck to prevent endoleaks. Lots of failure can result to stentgraft introduction which sometimes lead to aorta tear with pain and troubles to stitch it, and endothelial damage with post op aorta thrombosis. Giving aspirin to rats before stentgraft implantation decreases failure rate without major hemorrhage. Clamping time activates neutrophils, endothelium and platelets, and may interfere with biological analysis. PMID:23851958

  2. An Animal Model of Abdominal Aortic Aneurysm Created with Peritoneal Patch: Technique and Initial Results

    SciTech Connect

    Maynar, Manuel Hernandez, Javier; Sun Fei; Miguel, Carmen de; Crisostomo, Veronica; Uson, Jesus; Pineda, Luis-Fernando

    2003-04-15

    The purpose of this study was to develop an abdominal aortic aneurysm model that more closely resembles themorphology of human aneurysms with potential for further growth of the sac. An infrarenal abdominal aortic aneurysm (AAA) model was created with a double-layered peritoneal patch in 27 domestic swine. The patch,measuring in average from 6 to 12 cm in length and from 2 to 3 cm in width, was sutured to the edge of an aortotomy. Pre- and postsurgical digital subtraction aortograms (DSA) were obtained to document the appearance and dimensions of the aneurysm. All animals were followed with DSA for up to 5 months. Laparoscopic examination enhanced by the use of laparoscopic ultrasound was also carried out in 2 animals to assess the aneurysm at 30 and 60 days following surgery. Histological examination was performed on 4 animals. All the animals that underwent the surgical creation of the AAA survived the surgical procedure.Postsurgical DSA demonstrated the presence of the AAA in all animals,defined as more than 50% increase in diameter. The aneurysmal mean diameter increased from the baseline of 10.27 {+-} 1.24 to 16.69{+-} 2.29 mm immediately after surgery, to 27.6 {+-} 6.59 mm at 14 days, 32.45 {+-} 8.76 mm at 30 days (p <0.01), and subsequently decreased to 25.98 {+-} 3.75 mm at 60 days. A total of 15 animals died of aneurysmal rupture that occurred more frequently in the long aneurysms ({>=}6 cm in length) than the short aneurysms (<6 cm in length) during the first 2 weeks after surgery(p < 0.05). No rupture occurred beyond 16 days after surgery. Four animals survived and underwent 60-day angiographic follow-up. Laparoscopic follow-up showed strong pulses, a reddish external appearance and undetectable suture lines on the aneurysmal wall. On pathology, the patches were well incorporated into the aortic wall, the luminal wall appeared almost completely endothelialized, and cellular and matrix proliferation were noted in the aneurysmal wall. A reproducible

  3. Aneurysm flow characteristics in realistic carotid artery aneurysm models induced by proximal virtual stenotic plaques: a computational hemodynamics study

    NASA Astrophysics Data System (ADS)

    Castro, Marcelo A.; Peloc, Nora L.; Chien, Aichi; Goldberg, Ezequiel; Putman, Christopher M.; Cebral, Juan R.

    2015-03-01

    Cerebral aneurysms may rarely coexist with a proximal artery stenosis. In that small percent of patients, such coexistence poses a challenge for interventional neuroradiologists and neurosurgeons to make the best treatment decision. According to previous studies, the incidence of cerebral aneurysms in patients with internal carotid artery stenosis is no greater than five percent, where the aneurysm is usually incidentally detected, being about two percent for aneurysms and stenoses in the same cerebral circulation. Those cases pose a difficult management decision for the physician. Case reports showed patients who died due to aneurysm rupture months after endarterectomy but before aneurysm clipping, while others did not show any change in the aneurysm after plaque removal, having optimum outcome after aneurysm coiling. The aim of this study is to investigate the intra-aneurysmal hemodynamic changes before and after treatment of stenotic plaque. Virtually created moderate stenoses in vascular models of internal carotid artery aneurysm patients were considered in a number of cases reconstructed from three dimensional rotational angiography images. The strategy to create those plaques was based on parameters analyzed in a previous work where idealized models were considered, including relative distance and stenosis grade. Ipsilateral and contralateral plaques were modeled. Wall shear stress and velocity pattern were computed from finite element pulsatile blood flow simulations. The results may suggest that wall shear stress changes depend on relative angular position between the aneurysm and the plaque.

  4. Lattice Boltzmann Modeling of Thrombosis in Giant Aneurysms

    NASA Astrophysics Data System (ADS)

    Chopard, B.; Ouared, R.; Ruefenacht, D. A.; Yilmaz, H.

    We propose a numerical model of blood flow and blood clotting whose purpose is to describe thrombus formation in cerebral aneurysms. We identify possible mechanisms that can cause occurence of spontaneous thrombosis in unruptured giant intracranial aneurysms. Our main claim is that, under normal conditions, there is a low shear rate threshold below which thrombosis starts and growths. This assumption is supported by several evidences from literature. The proposed mechanisms are incorporated into a Lattice Boltzmann (LB) model for blood flow and platelets adhesion and aggregation. Numerical simulations show that the low shear rate threshold assumption together with aneurysm geometry account well for the observations.

  5. Fractional Modeling of Viscoelasticity in Brain Aneurysms

    NASA Astrophysics Data System (ADS)

    Yu, Yue; Karniadakis, George

    2014-11-01

    We develop fundamental new numerical methods for fractional order PDEs, and investigate corresponding models for arterial walls. Specifically, the arterial wall is a heterogeneous soft tissue with complex biomechanical properties, and its constitutive laws are typically derived using integer-order differential equations. However, recent simulations on 1D model have indicated that fractional order models may offer a more powerful alternative for describing arterial wall mechanics, because they are less sensitive to the parameter estimation compared with the integer-calculus-based models. We study the specific fractional PDEs that better model the properties of the 3D arterial walls, and for the first time employ them in simulating flow structure interactions for patient-specific brain aneurysms. A comparison study indicates that for the integer order models, the viscous behavior strongly depends on the relaxation parameters while the fractional order models are less sensitive. This finding is consistent with what is observed in the 1D models for arterial networks (Perdikaris & Karniadakis, 2014), except that when the fractional order is small, the 3D fractional-order models are more sensitive to the fractional order compared to the 1D models.

  6. Magnetic Particle Imaging for High Temporal Resolution Assessment of Aneurysm Hemodynamics

    PubMed Central

    Frölich, Andreas; Spallek, Johanna; Forkert, Nils D.; Faizy, Tobias D.; Werner, Franziska; Knopp, Tobias; Krause, Dieter; Fiehler, Jens; Buhk, Jan-Hendrik

    2016-01-01

    Purpose The purpose of this work was to demonstrate the capability of magnetic particle imaging (MPI) to assess the hemodynamics in a realistic 3D aneurysm model obtained by additive manufacturing. MPI was compared with magnetic resonance imaging (MRI) and dynamic digital subtraction angiography (DSA). Materials and Methods The aneurysm model was of saccular morphology (7 mm dome height, 5 mm cross-section, 3–4 mm neck, 3.5 mm parent artery diameter) and connected to a peristaltic pump delivering a physiological flow (250 mL/min) and pulsation rate (70/min). High-resolution (4 h long) 4D phase contrast flow quantification (4D pc-fq) MRI was used to directly assess the hemodynamics of the model. Dynamic MPI, MRI, and DSA were performed with contrast agent injections (3 mL volume in 3 s) through a proximally placed catheter. Results and Discussion 4D pc-fq measurements showed distinct pulsatile flow velocities (20–80 cm/s) as well as lower flow velocities and a vortex inside the aneurysm. All three dynamic methods (MPI, MRI, and DSA) also showed a clear pulsation pattern as well as delayed contrast agent dynamics within the aneurysm, which is most likely caused by the vortex within the aneurysm. Due to the high temporal resolution of MPI and DSA, it was possible to track the contrast agent bolus through the model and to estimate the average flow velocity (about 60 cm/s), which is in accordance with the 4D pc-fq measurements. Conclusions The ionizing radiation free, 4D high resolution MPI method is a very promising tool for imaging and characterization of hemodynamics in human. It carries the possibility of overcoming certain disadvantages of other modalities like considerably lower temporal resolution of dynamic MRI and limited 2D characteristics of DSA. Furthermore, additive manufacturing is the key for translating powerful pre-clinical techniques into the clinic. PMID:27494610

  7. Implantation of 3D-Printed Patient-Specific Aneurysm Models into Cadaveric Specimens: A New Training Paradigm to Allow for Improvements in Cerebrovascular Surgery and Research

    PubMed Central

    Benet, Arnau; Plata-Bello, Julio; Abla, Adib A.; Acevedo-Bolton, Gabriel; Saloner, David; Lawton, Michael T.

    2015-01-01

    Aim. To evaluate the feasibility of implanting 3D-printed brain aneurysm model in human cadavers and to assess their utility in neurosurgical research, complex case management/planning, and operative training. Methods. Two 3D-printed aneurysm models, basilar apex and middle cerebral artery, were generated and implanted in four cadaveric specimens. The aneurysms were implanted at the same anatomical region as the modeled patient. Pterional and orbitozygomatic approaches were done on each specimen. The aneurysm implant, manipulation capabilities, and surgical clipping were evaluated. Results. The 3D aneurysm models were successfully implanted to the cadaveric specimens' arterial circulation in all cases. The features of the neck in terms of flexibility and its relationship with other arterial branches allowed for the practice of surgical maneuvering characteristic to aneurysm clipping. Furthermore, the relationship of the aneurysm dome with the surrounding structures allowed for better understanding of the aneurysmal local mass effect. Noticeably, all of these observations were done in a realistic environment provided by our customized embalming model for neurosurgical simulation. Conclusion. 3D aneurysms models implanted in cadaveric specimens may represent an untapped training method for replicating clip technique; for practicing certain approaches to aneurysms specific to a particular patient; and for improving neurosurgical research. PMID:26539542

  8. Experimental modelling of aortic aneurysms: novel applications of silicone rubbers.

    PubMed

    Doyle, Barry J; Corbett, Timothy J; Cloonan, Aidan J; O'Donnell, Michael R; Walsh, Michael T; Vorp, David A; McGloughlin, Timothy M

    2009-10-01

    A range of silicone rubbers were created based on existing commercially available materials. These silicones were designed to be visually different from one another and have distinct material properties, in particular, ultimate tensile strengths and tear strengths. In total, eleven silicone rubbers were manufactured, with the materials designed to have a range of increasing tensile strengths from approximately 2 to 4 MPa, and increasing tear strengths from approximately 0.45 to 0.7 N/mm. The variations in silicones were detected using a standard colour analysis technique. Calibration curves were then created relating colour intensity to individual material properties. All eleven materials were characterised and a 1st order Ogden strain energy function applied. Material coefficients were determined and examined for effectiveness. Six idealised abdominal aortic aneurysm models were also created using the two base materials of the study, with a further model created using a new mixing technique to create a rubber model with randomly assigned material properties. These models were then examined using videoextensometry and compared to numerical results. Colour analysis revealed a statistically significant linear relationship (p<0.0009) with both tensile strength and tear strength, allowing material strength to be determined using a non-destructive experimental technique. The effectiveness of this technique was assessed by comparing predicted material properties to experimentally measured methods, with good agreement in the results. Videoextensometry and numerical modelling revealed minor percentage differences, with all results achieving significance (p<0.0009). This study has successfully designed and developed a range of silicone rubbers that have unique colour intensities and material strengths. Strengths can be readily determined using a non-destructive analysis technique with proven effectiveness. These silicones may further aid towards an improved understanding of

  9. Experimental testing of the dual-layer Woven EndoBridge device using an elastase-induced aneurysm model in rabbits.

    PubMed

    Ding, Yong-Hong; Dai, Daying; Schroeder, Dana; Kadirvel, Ramanathan; Kallmes, David F

    2016-06-01

    The dual-layer Woven EndoBridge (WEB) device (WEB II) is designed to improve the performance of the first-generation WEB device. This study was performed to evaluate the acute and chronic performance of WEB II for aneurysm occlusion in an elastase-induced aneurysm model in rabbits. We implanted WEB II devices in 36 elastase-induced aneurysms and followed up for one, three, six, and 12 months. Degree of aneurysm occlusion at follow-up was graded on the Web Occlusion Scale (WOS): Grade A, complete aneurysm occlusion; Grade B, complete occlusion with recess filling; Grade C, residual neck filling; and Grade D, residual aneurysm filling. Hematoxylin and eosin staining was performed for histological assessment of aneurysm healing. Grades A, B, C, and D aneurysm occlusion at one-month follow-up were noted in three (17%), three (17%), eight (44%), and four (22%) of 18 cases, respectively. At the three-month time point Grades A, B, C, and D were shown in two (33%), two (33%), one (17%), and one (17%) aneurysms. Six months after treatment, one (17%), two (33%), two (33%), and one (17%) cases demonstrated Grades A, B, C, and D occlusion. At the 12-month time point, Grades B, C, and D were shown in three (50%), two (33%), and one (17%) aneurysms. Histologic evaluation showed progressive thrombus organization within aneurysm lumen from one to 12 months. These results indicated that the WEB II device can achieve high rates of aneurysm occlusion over time in experimental aneurysms. PMID:26847799

  10. Hemodynamic Characteristics Regarding Recanalization of Completely Coiled Aneurysms: Computational Fluid Dynamic Analysis Using Virtual Models Comparison

    PubMed Central

    Park, Wonhyoung; Song, Yunsun; Park, Kye Jin; Koo, Hae-Won; Yang, Kuhyun

    2016-01-01

    Purpose Hemodynamic factors are considered to play an important role in initiation and progression of the recurrence after endosaccular coiling of the intracranial aneurysms. We made paired virtual models of completely coiled aneurysms which were subsequently recanalized and compared to identify hemodynamic characteristics related to the recurred aneurysmal sac. Materials and Methods We created paired virtual models of computational fluid dynamics (CFD) in five aneurysms which were initially regarded as having achieved complete occlusion and then recurred during follow-up. Paired virtual models consisted of the CFD model of 3D rotational angiography obtained in the recurred aneurysm and the control model of the initial, parent artery after artificial removal of the coiled and recanalized aneurysm. Using the CFD analysis of the virtual model, we analyzed the hemodynamic characteristics on the neck of each aneurysm before and after its recurrence. Results High wall shear stress (WSS) was identified at the cross-sectionally identified aneurysm neck at which recurrence developed in all cases. A small vortex formation with relatively low velocity in front of the neck was also identified in four cases. The aneurysm recurrence locations corresponded to the location of high WSS and/or small vortex formation. Conclusion Recanalized aneurysms revealed increased WSS and small vortex formation at the cross-sectional neck of the aneurysm. This observation may partially explain the hemodynamic causes of future recanalization after coil embolization. PMID:26958410

  11. Cerebral aneurysms treated with flow-diverting stents: Computational models using intravascular blood flow measurements

    PubMed Central

    Levitt, Michael R; McGah, Patrick M; Aliseda, Alberto; Mourad, Pierre D; Nerva, John D; Vaidya, Sandeep S; Morton, Ryan P; Ghodke, Basavaraj V; Kim, Louis J

    2013-01-01

    Background and Purpose Computational fluid dynamics modeling is useful in the study of the hemodynamic environment of cerebral aneurysms, but patient-specific measurements of boundary conditions, such as blood flow velocity and pressure, have not been previously applied to the study of flow-diverting stents. We integrated patient-specific intravascular blood flow velocity and pressure measurements into computational models of aneurysms before and after treatment with flow-diverting stents to determine stent effects on aneurysm hemodynamics. Methods Blood flow velocity and pressure were measured in peri-aneurysmal locations using an intravascular dual-sensor pressure and Doppler velocity guidewire before and after flow-diverting stent treatment of four unruptured cerebral aneurysms. These measurements defined inflow and outflow boundary conditions for computational models. Intra-aneurysmal flow rates, wall shear stress and wall shear stress gradient were calculated. Results Measurements of inflow velocity and outflow pressure were successful in all four patients. Computational models incorporating these measurements demonstrated significant reductions in intra-aneurysmal wall shear stress and wall shear stress gradient, and a trend in reduced intra-aneurysmal blood flow. Conclusions Integration of intravascular dual-sensor guidewire measurements of blood flow velocity and blood pressure provided patient-specific computational models of cerebral aneurysms. Aneurysm treatment with flow-diverting stents reduces blood flow and hemodynamic shear stress in the aneurysm dome. PMID:23868162

  12. A New Flow-Diverter (the FloWise): In-Vivo Evaluation in an Elastase-Induced Rabbit Aneurysm Model

    PubMed Central

    Kim, Dong Joon; Kim, Dong Ik

    2016-01-01

    Objective We aimed to evaluate the efficacy and safety of a newly developed, partially retrievable flow-diverter (the FloWise) in an elastase-induced rabbit aneurysm model. Materials and Methods We developed a partially retrievable flow diverter composed of 48 strands of Nitinol and platinum wire. The FloWise is compatible with any microcatheter of 0.027-inch inner diameter, and is retrievable up to 70% deployment. The efficacy and safety of the FloWise were evaluated in the elastase-induced rabbit aneurysm model. The rate of technical success (full coverage of aneurysm neck) and assessment of aneurysm occlusion and stent patency was conducted by angiograms and histologic examinations at the 1-month, 3-month, and 6-month follow-up. The patency of small arterial branches (intercostal or lumbar arteries) covered by the FloWise were also assessed in the 5 subjects. Results We attempted FloWise insertion in a total of 32 aneurysm models. FloWise placement was successful in 31 subjects (96.9%). Two stents (6.2%) were occluded at the 3-month follow-up, but there was no evidence of in-stent stenosis in other subjects. All stented aneurysms showed progressive occlusion: grade I (complete aneurysm occlusion) in 44.4% and grade II (aneurysm occlusion > 90%) in 55.6% at 1 month; grade I in 90% and II in 10% at 3 months; and grade I in 90% and II in 10% at 6 months. All small arterial branches covered by the FloWise remained patent. Conclusion A newly developed, partially retrievable flow-diverter seems to be a safe and effective tool of aneurysm occlusion, as evaluated in the rabbit aneurysm model. PMID:26798228

  13. Endovascular Broad-Neck Aneurysm Creation in a Porcine Model Using a Vascular Plug

    SciTech Connect

    Muehlenbruch, Georg Nikoubashman, Omid; Steffen, Bjoern; Dadak, Mete; Palmowski, Moritz; Wiesmann, Martin

    2013-02-15

    Ruptured cerebral arterial aneurysms require prompt treatment by either surgical clipping or endovascular coiling. Training for these sophisticated endovascular procedures is essential and ideally performed in animals before their use in humans. Simulators and established animal models have shown drawbacks with respect to degree of reality, size of the animal model and aneurysm, or time and effort needed for aneurysm creation. We therefore aimed to establish a realistic and readily available aneurysm model. Five anticoagulated domestic pigs underwent endovascular intervention through right femoral access. A total of 12 broad-neck aneurysms were created in the carotid, subclavian, and renal arteries using the Amplatzer vascular plug. With dedicated vessel selection, cubic, tubular, and side-branch aneurysms could be created. Three of the 12 implanted occluders, two of them implanted over a side branch of the main vessel, did not induce complete vessel occlusion. However, all aneurysms remained free of intraluminal thrombus formation and were available for embolization training during a surveillance period of 6 h. Two aneurysms underwent successful exemplary treatment: one was stent-assisted, and one was performed with conventional endovascular coil embolization. The new porcine aneurysm model proved to be a straightforward approach that offers a wide range of training and scientific applications that might help further improve endovascular coil embolization therapy in patients with cerebral aneurysms.

  14. Neuropsychological assessments in patients with aneurysmal subarachnoid hemorrhage, perimesencephalic SAH, and incidental aneurysms.

    PubMed

    Krajewski, Kara; Dombek, Susanne; Martens, Tobias; Köppen, Johannes; Westphal, Manfred; Regelsberger, Jan

    2014-01-01

    Subarachnoid hemorrhage (SAH) is known to be associated with long-term cognitive deficits. Neurosurgical manipulation on the brain itself has been reported to have influence on neuropsychological sequelae. The following is a comparative study on perimesencephalic and aneurysmal subarachnoid hemorrhage patients as well as elective aneurysm patients that was carried out to determine the isolated and combined impact of surgical manipulation and hemorrhage, respectively, on long-term neuropsychological outcome. Inclusion criteria were good neurological recovery at discharge (modified Rankin Scale 0 or 1) without focal neurological deficit. Standardized psychological testing covered attention, memory, executive functions, and mood. Thirteen aneurysmal SAH patients, 15 patients undergoing elective clipping, and 14 patients with perimesencephalic SAH were analyzed. Standardized neuropsychological testing and social/professional history questionnaires were performed 2 years (mean) after discharge. Memory impairment and slower cognitive processing were found in the aneurysmal and perimesencephalic SAH groups, while elective aneurysm patients showed signs of impaired attention. However, compared with norm data for age-matched healthy controls, all groups showed no significant test results. In contrast, signs of clinical depression were seen in 9/42 patients, 45 % of all patients complained of stress disorders and 55 % of patients were unable to work in their previous professions. Nearly normal neuropsychological test results on long-term follow-up in SAH patients were unexpected. However, a 50 % rate of unemployment accompanied with stress disorders and depression manifests insufficient social and workplace reintegration. Therefore, even more specific rehabilitation programs are required following inpatient treatment to attain full recovery. PMID:23949148

  15. Unsteady velocity measurements in a realistic intracranial aneurysm model

    NASA Astrophysics Data System (ADS)

    Ugron, Ádám; Farinas, Marie-Isabelle; Kiss, László; Paál, György

    2012-01-01

    The initiation, growth and rupture of intracranial aneurysms are intensively studied by computational fluid dynamics. To gain confidence in the results of numerical simulations, validation of the results is necessary. To this end the unsteady flow was measured in a silicone phantom of a realistic intracranial aneurysm. A flow circuit was built with a novel unsteady flow rate generating method, used to model the idealised shape of the heartbeat. This allowed the measurement of the complex three-dimensional velocity distribution by means of laser-optical methods such as laser doppler anemometry (LDA) and particle image velocimetry (PIV). The PIV measurements, available with high temporal and spatial distribution, were found to have good agreement with the control LDA measurements. Furthermore, excellent agreement was found with the numerical results.

  16. Mining data from CFD simulation for aneurysm and carotid bifurcation models.

    PubMed

    Miloš, Radović; Dejan, Petrović; Nenad, Filipović

    2011-01-01

    Arterial geometry variability is present both within and across individuals. To analyze the influence of geometric parameters, blood density, dynamic viscosity and blood velocity on wall shear stress (WSS) distribution in the human carotid artery bifurcation and aneurysm, the computer simulations were run to generate the data pertaining to this phenomenon. In our work we evaluate two prediction models for modeling these relationships: neural network model and k-nearest neighbor model. The results revealed that both models have high prediction ability for this prediction task. The achieved results represent progress in assessment of stroke risk for a given patient data in real time. PMID:22256273

  17. Transluminal Attenuation Gradient for Thrombotic Risk Assessment in Kawasaki Disease Patients with Coronary Artery Aneurysms

    NASA Astrophysics Data System (ADS)

    Grande Gutierrez, Noelia; Kahn, Andrew; Burns, Jane; Marsden, Alison

    2014-11-01

    Kawasaki Disease (KD) can result in coronary aneurysms in up to 25% of patients if not treated early putting patients at risk of thrombus formation, myocardial infarction and sudden death. Clinical guidelines for administering anti-coagulation therapy currently rely on anatomy alone. Previous studies including patient specific modeling and computer simulations in KD patients have suggested that hemodynamic data can predict regions susceptible to thrombus formation. In particular, high Particle Residence Time gradient (PRTg) regions have shown to correlate with regions of thrombus formation. Transluminal Attenuation Gradient (TAG) is determined from the change in radiological attenuation per vessel length. TAG has been used for characterizing coronary artery stenoses, however this approach has not yet been used in aneurysmal vessels. The aim of this study is to analyze the correlation between TAG and PRTg in KD patients with aneurysms and evaluate the use of TAG as an index to quantify thrombotic risk. Patient specific anatomic models for fluids simulations were constructed from CT angiographic image data from 3 KD aneurysm patients and one normal control. TAG values for the aneurysm patients were markedly lower than for the non-aneurysmal patient (mean -18.38 vs. -2). In addition, TAG values were compared to PRTg obtained for each patient. Thrombotic risk stratification for KD aneurysms may be improved by incorporating TAG and should be evaluated in future prospective studies.

  18. MR Imaging of Myeloperoxidase Activity in a Model of the Inflamed Aneurysm Wall

    PubMed Central

    Gounis, M.J.; van der Bom, I.M.J.; Wakhloo, A.K.; Zheng, S.; Chueh, J.-Y.; Kühn, A.L.; Bogdanov, A.A.

    2014-01-01

    Background and Purpose Although myeloperoxidase (MPO) activity in vivo can be visualized using non-invasive imaging, successful clinical translation requires further optimization of the imaging approach. We report a motion-sensitized-driven-equilibrium (MSDE) for the detection of an MPO activity-specific gadolinium (Gd)-containing imaging agent (IA) in experimental aneurysm models that compensates for irregular blood flow enabling vascular wall imaging in the aneurysm. Materials and Methods We deployed a phantom model to optimize a MSDE MR sequence that suppresses complex flow patterns within the aneurysm for detection of an MPO-specific Gd-chelate. The phantom was built from rotational angiography of a rabbit elastase aneurysm model and connected to a cardiac pulse duplicator mimicking rabbit-specific flow conditions. Thereafter, we further refined the MSDE sequence and applied it in vivo to rabbit aneurysm models with and without inflammation in the aneurysmal wall. Under each condition, the aneurysms were imaged before and after intravenous administration of the IA. The signal-to-noise ratio (SNR) of each MR slice through the aneurysm was calculated. Results The MSDE sequence was optimized to reduce flow signal enabling detection of the MPO-IA in the phantom. The optimized imaging protocol in the rabbit model of saccular aneurysms revealed a significant increase in the change of SNR pre- to postcontrast MR signal intensities in the inflamed aneurysms as compared to naïve aneurysms and the adjacent carotid artery (p<0.0001). Conclusion A diagnostic MR protocol was optimized for molecular imaging of an MPO-specific molecular imaging agent in an animal model of brain aneurysms. PMID:25273534

  19. Characterization of the transport topology in patient-specific abdominal aortic aneurysm models

    NASA Astrophysics Data System (ADS)

    Arzani, Amirhossein; Shadden, Shawn C.

    2012-08-01

    Abdominal aortic aneurysm (AAA) is characterized by disturbed blood flow patterns that are hypothesized to contribute to disease progression. The transport topology in six patient-specific abdominal aortic aneurysms was studied. Velocity data were obtained by image-based computational fluid dynamics modeling, with magnetic resonance imaging providing the necessary simulation parameters. Finite-time Lyapunov exponent (FTLE) fields were computed from the velocity data, and used to identify Lagrangian coherent structures (LCS). The combination of FTLE fields and LCS was used to characterize topological flow features such as separation zones, vortex transport, mixing regions, and flow impingement. These measures offer a novel perspective into AAA flow. It was observed that all aneurysms exhibited coherent vortex formation at the proximal segment of the aneurysm. The evolution of the systolic vortex strongly influences the flow topology in the aneurysm. It was difficult to predict the vortex dynamics from the aneurysm morphology, motivating the application of image-based flow modeling.

  20. Endovascular Repair of Abdominal Aortic Aneurysm: Follow-up with Noninvasive Vascular Elastography in a Canine Model.

    PubMed

    Salloum, Eli; Bertrand-Grenier, Antony; Lerouge, Sophie; Kauffman, Claude; Héon, Hélène; Therasse, Eric; Salazkin, Igor; Roy Cardinal, Marie-Hélène; Cloutier, Guy; Soulez, Gilles

    2016-05-01

    Purpose To assess the ability of noninvasive vascular elastography (NIVE) to help characterize endoleaks and thrombus organization in a canine model of abdominal aortic aneurysm after endovascular aneurysm repair with stent-grafts, in comparison with computed tomography (CT) and pathologic examination findings. Materials and Methods All protocols were approved by the Animal Care Committee in accordance with the guidelines of the Canadian Council of Animal Care. Stent-grafts were implanted in a group of 18 dogs with aneurysms created in the abdominal aorta. Type I endoleak was created in four aneurysms; type II endoleak, in 13 aneurysms; and no endoleak, in one aneurysm. Doppler ultrasonography and NIVE examinations were performed at baseline and at 1-week, 1-month, 3-month, and 6-month follow-up. Angiography, CT, and macroscopic tissue examination were performed at sacrifice. Strain values were computed by using the Lagrangian speckle model estimator. Areas of endoleak, solid organized thrombus, and fresh thrombus were identified and segmented by comparing the results of CT and macroscopic tissue examination. Strain values were compared by using the Wilcoxon rank-sum and Kruskal-Wallis tests. Results All stent-grafts were successfully deployed, and endoleaks were clearly depicted in the last follow-up elastography examinations. Maximal axial strains over consecutive heart cycles in endoleak, organized thrombus, and fresh thrombus areas were 0.78% ± 0.22, 0.23% ± 0.02, 0.10% ± 0.04, respectively. Strain values were significantly different between endoleak and organized or fresh thrombus areas (P < .000) and between organized and fresh thrombus areas (P < .0002). No correlation was found between strain values and type of endoleak, sac pressure, endoleak size, and aneurysm size. Conclusion NIVE may be able to help characterize endoleak and thrombus organization, regardless of the size, pressure, and type of endoleak. (©) RSNA, 2015. PMID:26690905

  1. Reduction of aneurysm pressure and wall stress after endovascular repair of abdominal aortic aneurysm in a canine model.

    PubMed

    Marston, W A; Criado, E; Baird, C A; Keagy, B A

    1996-03-01

    A canine model was designed to evaluate the changes in abdominal aortic aneurysm (AAA) pressure and wall stress after endovascular repair. Eight canines underwent laparotomy and creation of an AAA. The aneurysm was then excluded with a transluminally placed endovascular graft (TPEG) inserted through the right femoral artery and deployed across the AAA to exclude the infrarenal aortic branches from aortic perfusion. Blood pressure and flow data were recorded for 6 hours. The AAA blood pressure decreased from 135 +/- 9.3 mm Hg before exclusion to 45 +/- 17.6 mm Hg at 10 minutes after exclusion (p < 0.001). At 6 hours, AAA blood pressure had declined further to 26 +/- 12.5 mm Hg. Blood flow in the excluded iliac artery decreased from a baseline of 242 +/- 58 ml/min to 41 +/- 29 ml/min 10 minutes after TPEG placement (p < 0.001). At 6 hours, flow was reduced to 12 +/- 3.5 ml/min (p < 0.05 compared with that at 10 minutes). Aortic wall stress was significantly reduced by TPEG placement but was only slightly lower than baseline aortic wall stress before AAA creation. The lumbar arteries were patent with retrograde flow in all cases and were found to be the major contributors to postexclusion aneurysm pressure. Endovascular AAA exclusion results in an immediate decrease in blood pressure and wall stress within the excluded aneurysm, but the aneurysm remains perfused by retrograde flow through the lumbar arteries, which resulted in near-baseline levels of aneurysm wall stress in this canine model. Embolization of patient lumbar vessels at prosthesis placement may further reduce the risk of late rupture. PMID:8733869

  2. Quantitative comparison of hemodynamics in simulated and 3D angiography models of cerebral aneurysms by use of computational fluid dynamics.

    PubMed

    Saho, Tatsunori; Onishi, Hideo

    2015-07-01

    In this study, we evaluated hemodynamics using simulated models and determined how cerebral aneurysms develop in simulated and patient-specific models based on medical images. Computational fluid dynamics (CFD) was analyzed by use of OpenFOAM software. Flow velocity, stream line, and wall shear stress (WSS) were evaluated in a simulated model aneurysm with known geometry and in a three-dimensional angiographic model. The ratio of WSS at the aneurysm compared with that at the basilar artery was 1:10 in simulated model aneurysms with a diameter of 10 mm and 1:18 in the angiographic model, indicating similar tendencies. Vortex flow occurred in both model aneurysms, and the WSS decreased in larger model aneurysms. The angiographic model provided accurate CFD information, and the tendencies of simulated and angiographic models were similar. These findings indicate that hemodynamic effects are involved in the development of aneurysms. PMID:25911446

  3. A Thrombus Generation Model Applied to Aneurysms Treated with Shape Memory Polymer Foam and Metal Coils

    NASA Astrophysics Data System (ADS)

    Horn, John; Ortega, Jason; Hartman, Jonathan; Maitland, Duncan

    2015-11-01

    To prevent their rupture, intracranial aneurysms are often treated with endovascular metal coils which fill the aneurysm sac and isolate it from the arterial flow. Despite its widespread use, this method can result in suboptimal outcomes leading to aneurysm recurrence. Recently, shape memory polymer foam has been proposed as an alternative aneurysm filler. In this work, a computational model has been developed to predict thrombus formation in blood in response to such cardiovascular implantable devices. The model couples biofluid and biochemical phenomena present as the blood interacts with a device and stimulates thrombus formation. This model is applied to simulations of both metal coil and shape memory polymer foam treatments within an idealized 2D aneurysm geometry. Using the predicted thrombus responses, the performance of these treatments is evaluated and compared. The results suggest that foam-treated aneurysms may fill more quickly and more completely with thrombus than coil-filled aneurysms, potentially leading to improved long-term aneurysm healing. This work was performed in part under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  4. Fast Virtual Stenting with Active Contour Models in Intracranical Aneurysm

    PubMed Central

    Zhong, Jingru; Long, Yunling; Yan, Huagang; Meng, Qianqian; Zhao, Jing; Zhang, Ying; Yang, Xinjian; Li, Haiyun

    2016-01-01

    Intracranial stents are becoming increasingly a useful option in the treatment of intracranial aneurysms (IAs). Image simulation of the releasing stent configuration together with computational fluid dynamics (CFD) simulation prior to intervention will help surgeons optimize intervention scheme. This paper proposed a fast virtual stenting of IAs based on active contour model (ACM) which was able to virtually release stents within any patient-specific shaped vessel and aneurysm models built on real medical image data. In this method, an initial stent mesh was generated along the centerline of the parent artery without the need for registration between the stent contour and the vessel. Additionally, the diameter of the initial stent volumetric mesh was set to the maximum inscribed sphere diameter of the parent artery to improve the stenting accuracy and save computational cost. At last, a novel criterion for terminating virtual stent expanding that was based on the collision detection of the axis aligned bounding boxes was applied, making the stent expansion free of edge effect. The experiment results of the virtual stenting and the corresponding CFD simulations exhibited the efficacy and accuracy of the ACM based method, which are valuable to intervention scheme selection and therapy plan confirmation. PMID:26876026

  5. In vivo tissue response following implantation of shape memory polyurethane foam in a porcine aneurysm model

    PubMed Central

    Rodriguez, Jennifer N.; Clubb, Fred J.; Wilson, Thomas S.; Miller, Matthew W.; Fossum, Theresa W.; Hartman, Jonathan; Tuzun, Egemen; Singhal, Pooja; Maitland, Duncan J.

    2014-01-01

    Cerebral aneurysms treated by traditional endovascular methods using platinum coils have a tendency to be unstable, either due to chronic inflammation, compaction of coils, or growth of the aneurysm. We propose to use alternate filling methods for the treatment of intracranial aneurysms using polyurethane based shape memory polymer (SMP) foams. SMP polyurethane foams were surgically implanted in a porcine aneurysm model to determine biocompatibility, localized thrombogenicity, and their ability to serve as a stable filler material within an aneurysm. The degree of healing was evaluated via gross observation, histopathology and low vacuum scanning electron microscopy (LV-SEM) imaging after zero, thirty and ninety days. Clotting was initiated within the SMP foam at time zero (less than one hour exposure to blood prior to euthanization), partial healing was observed at thirty days, and almost complete healing had occurred at ninety days in vivo, with minimal inflammatory response. PMID:23650278

  6. Biomechanical rupture risk assessment of abdominal aortic aneurysms based on a novel probabilistic rupture risk index.

    PubMed

    Polzer, Stanislav; Gasser, T Christian

    2015-12-01

    A rupture risk assessment is critical to the clinical treatment of abdominal aortic aneurysm (AAA) patients. The biomechanical AAA rupture risk assessment quantitatively integrates many known AAA rupture risk factors but the variability of risk predictions due to model input uncertainties remains a challenging limitation. This study derives a probabilistic rupture risk index (PRRI). Specifically, the uncertainties in AAA wall thickness and wall strength were considered, and wall stress was predicted with a state-of-the-art deterministic biomechanical model. The discriminative power of PRRI was tested in a diameter-matched cohort of ruptured (n = 7) and intact (n = 7) AAAs and compared to alternative risk assessment methods. Computed PRRI at 1.5 mean arterial pressure was significantly (p = 0.041) higher in ruptured AAAs (20.21(s.d. 14.15%)) than in intact AAAs (3.71(s.d. 5.77)%). PRRI showed a high sensitivity and specificity (discriminative power of 0.837) to discriminate between ruptured and intact AAA cases. The underlying statistical representation of stochastic data of wall thickness, wall strength and peak wall stress had only negligible effects on PRRI computations. Uncertainties in AAA wall stress predictions, the wide range of reported wall strength and the stochastic nature of failure motivate a probabilistic rupture risk assessment. Advanced AAA biomechanical modelling paired with a probabilistic rupture index definition as known from engineering risk assessment seems to be superior to a purely deterministic approach. PMID:26631334

  7. Sensitivity of CFD Based Hemodynamic Results in Rabbit Aneurysm Models to Idealizations in Surrounding Vasculature

    PubMed Central

    Zeng, Zijing; Kallmes, David F.; Durka, Michael J.; Ding, Yonghong; Lewis, Debra; Kadirvel, Ramanathan

    2010-01-01

    Computational fluid dynamics (CFD) studies provide a valuable tool for evaluating the role of hemodynamics in vascular diseases such as cerebral aneurysms and atherosclerosis. However, such models necessarily only include isolated segments of the vasculature. In this work, we evaluate the influence of geometric approximations in vascular anatomy on hemodynamics in elastase induced saccular aneurysms in rabbits. One representative high aspect ratio (AR—height/neck width) aneurysm and one low AR aneurysm were created at the origin of the right common carotid artery in two New Zealand white rabbits. Three-dimensional (3D) reconstructions of the aneurysm and surrounding arteries were created using 3D rotational angiographic data. Five models with varying extents of neighboring vasculature were created for both the high and low AR cases. A reference model included the aneurysm sac, left common carotid artery (LCCA), aortic arch, and downstream trifurcation/quadrification. Three-dimensional, pulsatile CFD studies were performed and streamlines, wall shear stress (WSS), oscillatory shear index, and cross sectional velocity were compared between the models. The influence of the vascular domain on intra-aneurysmal hemodynamics varied between the low and high AR cases. For the high AR case, even a simple model including only the aneurysm, a small section of neighboring vasculature, and simple extensions captured the main features of the steamline and WSS distribution predicted by the reference model. However, the WSS distribution in the low AR case was more strongly influenced by the extent of vasculature. In particular, it was necessary to include the downstream quadrification and upstream LCCA to obtain good predictions of WSS. The findings in this work demonstrate the accuracy of CFD results can be compromised if insufficient neighboring vessels are included in studies of hemodynamics in elastase induced rabbit aneurysms. Consideration of aspect ratio, hemodynamic

  8. Sensitivity of CFD based hemodynamic results in rabbit aneurysm models to idealizations in surrounding vasculature.

    PubMed

    Zeng, Zijing; Kallmes, David F; Durka, Michael J; Ding, Yonghong; Lewis, Debra; Kadirvel, Ramanathan; Robertson, Anne M

    2010-09-01

    Computational fluid dynamics (CFD) studies provide a valuable tool for evaluating the role of hemodynamics in vascular diseases such as cerebral aneurysms and atherosclerosis. However, such models necessarily only include isolated segments of the vasculature. In this work, we evaluate the influence of geometric approximations in vascular anatomy on hemodynamics in elastase induced saccular aneurysms in rabbits. One representative high aspect ratio (AR-height/neck width) aneurysm and one low AR aneurysm were created at the origin of the right common carotid artery in two New Zealand white rabbits. Three-dimensional (3D) reconstructions of the aneurysm and surrounding arteries were created using 3D rotational angiographic data. Five models with varying extents of neighboring vasculature were created for both the high and low AR cases. A reference model included the aneurysm sac, left common carotid artery (LCCA), aortic arch, and downstream trifurcation/quadrification. Three-dimensional, pulsatile CFD studies were performed and streamlines, wall shear stress (WSS), oscillatory shear index, and cross sectional velocity were compared between the models. The influence of the vascular domain on intra-aneurysmal hemodynamics varied between the low and high AR cases. For the high AR case, even a simple model including only the aneurysm, a small section of neighboring vasculature, and simple extensions captured the main features of the steamline and WSS distribution predicted by the reference model. However, the WSS distribution in the low AR case was more strongly influenced by the extent of vasculature. In particular, it was necessary to include the downstream quadrification and upstream LCCA to obtain good predictions of WSS. The findings in this work demonstrate the accuracy of CFD results can be compromised if insufficient neighboring vessels are included in studies of hemodynamics in elastase induced rabbit aneurysms. Consideration of aspect ratio, hemodynamic

  9. A spatio-temporal model for spontaneous thrombus formation in cerebral aneurysms.

    PubMed

    Malaspinas, O; Turjman, A; Ribeiro de Sousa, D; Garcia-Cardena, G; Raes, M; Nguyen, P-T T; Zhang, Y; Courbebaisse, G; Lelubre, C; Zouaoui Boudjeltia, K; Chopard, B

    2016-04-01

    We propose a new numerical model to describe thrombus formation in cerebral aneurysms. This model combines CFD simulations with a set of bio-mechanical processes identified as being the most important to describe the phenomena at a large space and time scales. The hypotheses of the model are based on in vitro experiments and clinical observations. We document that we can reproduce very well the shape and volume of patient specific thrombus segmented in giant aneurysms. PMID:26802480

  10. Blood flow dynamic improvement with aneurysm repair detected by a patient-specific model of multiple aortic aneurysms.

    PubMed

    Sughimoto, Koichi; Takahara, Yoshiharu; Mogi, Kenji; Yamazaki, Kenji; Tsubota, Ken'ichi; Liang, Fuyou; Liu, Hao

    2014-05-01

    Aortic aneurysms may cause the turbulence of blood flow and result in the energy loss of the blood flow, while grafting of the dilated aorta may ameliorate these hemodynamic disturbances, contributing to the alleviation of the energy efficiency of blood flow delivery. However, evaluating of the energy efficiency of blood flow in an aortic aneurysm has been technically difficult to estimate and not comprehensively understood yet. We devised a multiscale computational biomechanical model, introducing novel flow indices, to investigate a single male patient with multiple aortic aneurysms. Preoperative levels of wall shear stress and oscillatory shear index (OSI) were elevated but declined after staged grafting procedures: OSI decreased from 0.280 to 0.257 (first operation) and 0.221 (second operation). Graftings may strategically counter the loss of efficient blood delivery to improve hemodynamics of the aorta. The energy efficiency of blood flow also improved postoperatively. Novel indices of pulsatile pressure index (PPI) and pulsatile energy loss index (PELI) were evaluated to characterize and quantify energy loss of pulsatile blood flow. Mean PPI decreased from 0.445 to 0.423 (first operation) and 0.359 (second operation), respectively; while the preoperative PELI of 0.986 dropped to 0.820 and 0.831. Graftings contributed not only to ameliorate wall shear stress or oscillatory shear index but also to improve efficient blood flow. This patient-specific modeling will help in analyzing the mechanism of aortic aneurysm formation and may play an important role in quantifying the energy efficiency or loss in blood delivery. PMID:23852404

  11. Analysis of Hemodynamics and Aneurysm Occlusion after Flow Diverting Treatment in Rabbit Models

    PubMed Central

    Cebral, Juan R.; Mut, Fernando; Raschi, Marcelo; Hodis, Simona; Ding, Yong-Hong; Erickson, Bradley J.; Kadirvel, Ramanathan; Kallmes, David F.

    2015-01-01

    Purpose to investigate the relationship between hemodynamic conditions created immediately after flow diversion and subsequent occlusion of experimental aneurysms in rabbits. Methods The hemodynamic environment before and after flow diversion treatment of elastase induced aneurysms in 20 rabbits was modeled using image-based computational fluid dynamics. Local aneurysm occlusion was quantified using a voxelization technique on 3D images acquired 8 weeks after treatment. Global and local voxel-by-voxel hemodynamic variables were used to statistically compare aneurysm regions that later thrombosed to regions that remained patent. Results Six aneurysms remained patent at 8 weeks while 14 were completely or nearly completely occluded. Patent aneurysms had statistically larger neck sizes (p=0.0015) and smaller mean transit times (p=0.02). The velocity, vorticity and shear rate were about 2.8 times (p<0.0001) larger in patent regions, i.e. had larger “flow activity”, than regions that progressed to occlusion. Statistical models based on local hemodynamic variables were capable of predicting local occlusion with good precision (84% accuracy), especially away from the neck (92–94%). Predictions near the neck were poorer (73% accuracy). Conclusion These results suggests that the dominant healing mechanism of occlusion within the aneurysm dome are related to slow flow induced thrombosis while near the neck other processes could be at play simultaneously. PMID:24729467

  12. Analysis of Hemodynamics and Aneurysm Occlusion after Flow Diverting Treatment in Rabbit Models

    PubMed Central

    Cebral, Juan R.; Mut, Fernando; Raschi, Marcelo; Hodis, Simona; Ding, Yong-Hong; Erickson, Bradley J.; Kadirvel, Ramanathan; Kallmes, David F.

    2014-01-01

    Purpose to investigate the relationship between hemodynamic conditions created immediately after flow diversion and subsequent occlusion of experimental aneurysms in rabbits. Methods The hemodynamic environment before and after flow diversion treatment of elastase induced aneurysms in 20 rabbits was modeled using image-based computational fluid dynamics. Local aneurysm occlusion was quantified using a voxelization technique on 3D images acquired 8 weeks after treatment. Global and local voxel-by-voxel hemodynamic variables were used to statistically compare aneurysm regions that later thrombosed to regions that remained patent. Results Six aneurysms remained patent at 8 weeks while 14 were completely or nearly completely occluded. Patent aneurysms had statistically larger neck sizes (p=0.0015) and smaller mean transit times (p=0.02). The velocity, vorticity and shear rate were about 2.8 times (p<0.0001) larger in patent regions, i.e. had larger “flow activity”, than regions that progressed to occlusion. Statistical models based on local hemodynamic variables were capable of predicting local occlusion with good precision (84% accuracy), especially away from the neck (92–94%). Predictions near the neck were poorer (73% accuracy). Conclusion These results suggests that the dominant healing mechanism of occlusion within the aneurysm dome are related to slow flow induced thrombosis while near the neck other processes could be at play simultaneously. PMID:24722302

  13. Flow in experimental berry aneurysms: method and model.

    PubMed

    Kerber, C W; Heilman, C B

    1983-01-01

    This study addresses two basic questions: What are the flow dynamics in aneurysms? Can these flows be modified to enhance retention of adhesive? Using Pyrex glass bifurcations, fluid flow was studied in a variety of aneurysms placed at varying positions around the bifurcations. Indicators injected into the slipstreams were recorded and studied both by stop-frame high-speed movie analysis and with 35 mm slides. Even at low-flow rates, a central slipstream strikes the apex of bifurcations, and may be partly responsible for the initial production of berry aneurysms. A low-pressure zone occurs at the lateral angle of bifurcations, probably explaining the formation of endovascular cushions. Flow into symmetrically placed narrow neck aneurysms did not occur. Indicator entered the aneurysm in a turbulent fashion only when there was orifice (lip) asymmetry. Both lip asymmetry and rapid flow favor intraaneurysmal turbulent flow. PMID:6410748

  14. Three-band decomposition analysis in multiscale FSI models of abdominal aortic aneurysms

    NASA Astrophysics Data System (ADS)

    Nestola, Maria G. C.; Gizzi, Alessio; Cherubini, Christian; Filippi, Simonetta

    2016-07-01

    Computational modeling plays an important role in biology and medicine to assess the effects of hemodynamic alterations in the onset and development of vascular pathologies. Synthetic analytic indices are of primary importance for a reliable and effective a priori identification of the risk. In this scenario, we propose a multiscale fluid-structure interaction (FSI) modeling approach of hemodynamic flows, extending the recently introduced three-band decomposition (TBD) analysis for moving domains. A quantitative comparison is performed with respect to the most common hemodynamic risk indicators in a systematic manner. We demonstrate the reliability of the TBD methodology also for deformable domains by assuming a hyperelastic formulation of the arterial wall and a Newtonian approximation of the blood flow. Numerical simulations are performed for physiologic and pathologic axially symmetric geometry models with particular attention to abdominal aortic aneurysms (AAAs). Risk assessment, limitations and perspectives are finally discussed.

  15. Aneurysmal Subarachnoid Hemorrhage Models: Do They Need a Fix?

    PubMed Central

    Sehba, Fatima A.; Pluta, Ryszard M.

    2013-01-01

    The discovery of tissue plasminogen activator to treat acute stroke is a success story of research on preventing brain injury following transient cerebral ischemia (TGI). That this discovery depended upon development of embolic animal model reiterates that proper stroke modeling is the key to develop new treatments. In contrast to TGI, despite extensive research, prevention or treatment of brain injury following aneurysmal subarachnoid hemorrhage (aSAH) has not been achieved. A lack of adequate aSAH disease model may have contributed to this failure. TGI is an important component of aSAH and shares mechanism of injury with it. We hypothesized that modifying aSAH model using experience acquired from TGI modeling may facilitate development of treatment for aSAH and its complications. This review focuses on similarities and dissimilarities between TGI and aSAH, discusses the existing TGI and aSAH animal models, and presents a modified aSAH model which effectively mimics the disease and has a potential of becoming a better resource for studying the brain injury mechanisms and developing a treatment. PMID:23878760

  16. A Geodesics-Based Surface Parameterization to Assess Aneurysm Progression.

    PubMed

    Phan, Ly; Courchaine, Katherine; Azarbal, Amir; Vorp, David; Grimm, Cindy; Rugonyi, Sandra

    2016-05-01

    Abdominal aortic aneurysm (AAA) intervention and surveillance is currently based on maximum transverse diameter, even though it is recognized that this might not be the best strategy. About 10% of patients with small AAA transverse diameters, for whom intervention is not considered, still rupture; while patients with large AAA transverse diameters, for whom intervention would have been recommended, have stable aneurysms that do not rupture. While maximum transverse diameter is easy to measure and track in clinical practice, one of its main drawbacks is that it does not represent the whole AAA and rupture seldom occurs in the region of maximum transverse diameter. By following maximum transverse diameter alone clinicians are missing information on the shape change dynamics of the AAA, and clues that could lead to better patient care. We propose here a method to register AAA surfaces that were obtained from the same patient at different time points. Our registration method could be used to track the local changes of the patient-specific AAA. To achieve registration, our procedure uses a consistent parameterization of the AAA surfaces followed by strain relaxation. The main assumption of our procedure is that growth of the AAA occurs in such a way that surface strains are smoothly distributed, while regions of small and large surface growth can be differentiated. The proposed methodology has the potential to unravel different patterns of AAA growth that could be used to stratify patient risks. PMID:27003915

  17. Hemodynamic-Morphological Discriminant Models for Intracranial Aneurysm Rupture Remain Stable with Increasing Sample Size

    PubMed Central

    Xiang, Jianping; Yu, Jihnhee; Snyder, Kenneth V.; Levy, Elad I.; Siddiqui, Adnan H.; Meng, Hui

    2016-01-01

    Background We previously established three logistic regression models for discriminating intracranial aneurysm rupture status based on morphological and hemodynamic analysis of 119 aneurysms (Stroke. 2011;42:144–152). In this study we tested if these models would remain stable with increasing sample size and investigated sample sizes required for various confidence levels. Methods We augmented our previous dataset of 119 aneurysms into a new dataset of 204 samples by collecting additional 85 consecutive aneurysms, on which we performed flow simulation and calculated morphological and hemodynamic parameters as done previously. We performed univariate significance tests of these parameters, and on the significant parameters we performed multivariate logistic regression. The new regression models were compared against the original models. Receiver operating characteristics analysis was applied to compare the performance of regression models. Furthermore, we performed regression analysis based on bootstrapping resampling statistical simulations to explore how many aneurysm cases were required to generate stable models. Results Univariate tests of the 204 aneurysms generated an identical list of significant morphological and hemodynamic parameters as previously from analysis of 119 cases. Furthermore, multivariate regression analysis produced three parsimonious predictive models that were almost identical to the previous ones; with model coefficients that had narrower confidence intervals than the original ones. Bootstrapping showed that 10%, 5%, 2%, and 1% convergence levels of confidence interval required 120, 200, 500, and 900 aneurysms, respectively. Conclusions Our original hemodynamic-morphological rupture prediction models are stable and improve with increasing sample size. Results from resampling statistical simulations provide guidance for designing future large multi-population studies. PMID:25488922

  18. Assessment of contrast flow modification in aneurysms treated with closed-cell self-deploying asymmetric vascular stents (SAVS)

    NASA Astrophysics Data System (ADS)

    Ionita, Ciprian N.; Wang, Weiyuan; Bednarek, Daniel R.; Rudin, Stephen

    2010-03-01

    The Asymmetric Vascular Stent (AVS) for intracranial aneurysm (IA) treatment is an experimental device, specially designed for intra-aneurysmal blood flow diversion and thrombosis promotion. The stent has a low-porous patch to cover only the aneurysm neck while the rest of the stent is very porous to avoid blockage of adjacent branches. The latest AVS design is similar to state-of-art, closed-cell, self-expanding, neurovascular stent. The stents were used to treat sixteen rabbit-elastase aneurysm models. The treatment effect was analyzed using normalized-time-density-curves (NTDC) measured by pixel-value integration over a region-of-interest containing the aneurysm. Normalization constant was the total bolus injection determined angiographically. Based on NTDC measurement, five quantities were derived to describe the contrast flow. Two are related to the amount of contrast entering the aneurysm: NTDC peak and NTDC input slope. The other three are related to contrast presence in the aneurysmal dome: time-to-peak (TTP), wash-out-time (WOT) and mean-transit-time (MTT). Flow modification descriptions using the contrast related quantities were expressed as a pre-/post-stented NTDC parameter ratio, while the time related quantities were expressed as a post-/prestented ratio, so that ratios smaller than one indicate a desired effect. Thirteen aneurysms were treated successfully and achieved significant aneurysm occlusion. For these cases, the resulting average parameters were: peak-ratio=0.17+0.21; input-slope-ratio=0.19+/-0.24, TTP-ratio=0.17+0.21, WOT-ratio=0.58+/-0.73 and MTT-ratio=0.65+/-0.97). All the quantities revealed decreased aneurysmal flow due to blood flow diversion using the new self-expanding asymmetrical vascular stent (SAVS). Treatment outcome results and angiographic analysis indicate that the new self-deploying stent design has great potential for clinical implementation.

  19. Risk assessment and risk scores in the management of aortic aneurysms.

    PubMed

    Von Meijenfeldt, Gerdine C I; Van Der Laan, Maarten J; Zeebregts, Clark J; Balm, Ron; Verhagen, Hence J M

    2016-04-01

    The decision whether to operate a patient or not can be challenging for a clinician for both ruptured abdominal aortic aneurysms (AAAs) as well as elective AAAs. Prior to surgical intervention it would be preferable that the clinician exactly knows which clinical variables lower or increase the chances of morbidity and mortality postintervention. To help in the preoperative counselling and shared decision making several clinical variables can be identified as risk factors and with these, risk models can be developed. An ideal risk score for aneurysm repair includes routinely obtained physiological and anatomical variables, has excellent discrimination and calibration, and is validated in different geographical areas. For elective AAA repair, several risk scores are available, for ruptured AAA treatment, these scores are far less well developed. In this manuscript, we describe the designs and results of published risk scores for elective and open repair. Also, suggestions for uniformly reporting of risk factors and their statistical analyses are described. Furthermore, the preliminary results of a new risk model for ruptured aortic aneurysm will be discussed. This score identifies age, hemoglobin, cardiopulmonary resuscitation and preoperative systolic blood pressure as risk factors after multivariate regression analysis. This new risk score can help to identify patients that would not benefit from repair, but it can also potentially identify patients who would benefit and therefore lower turndown rates. The challenge for further research is to expand on validation of already existing promising risk scores in order to come to a risk model with optimal discrimination and calibration. PMID:26698033

  20. Visualization and finite element analysis of pulsatile flow in models of the abdominal aortic aneurysm.

    PubMed

    Fukushima, T; Matsuzawa, T; Homma, T

    1989-01-01

    Pulsatile flows in glass models simulating fusiform and lateral saccular aneurysms were investigated by a flow visualization method. When resting fluid starts to flow, the initial fluid motion is practically irrotational. After a short period of time, the flow began to separate from the proximal wall of the aneurysm. Then the separation bubble or vortex grew rapidly in size and filled the whole area of the aneurysm circumferentially. During this period of time, the center of the vortex moved from the proximal end to the distal point of the aneurysm. The transient reversal flow, for instance, which may occur at the end of the ejection period, passed between the wall of the aneurysm and the centrally located vortex. When the rate and pulsatile frequency of flow were high, the vortex broke down into highly disturbed flow (or turbulence) at the distal portion of the aneurysm. The same effect was observed when the length of the aneurysm was increased. A reduction in pulsatile amplitude made the flow pattern close to that in steady flow. A finite element analysis was made to obtain velocity and pressure fields in pulsatile flow through a tube with an axisymmetric expansion. Calculations were performed with the pulsatile flows used in the visualization experiment in order to study the effects of change in the pulsatile wave form by keeping the time-mean Reynolds number and Womersley's parameter unchanged. Calculated instantaneous patterns of velocity field and stream lines agreed well with the experimental results. The appearance and disappearance of the vortex in the dilated portion and its development resulted in complex distributions of pressure and shear fields. Locally minimum and maximum values of wall shear stress occurred at points just upstream and downstream of the distal end of the expansion when the flow rate reached its peak. PMID:2605323

  1. Enhancement of Mechanical Properties and Testing of Nitinol Stents in Cerebral Aneurysm Simulation Models.

    PubMed

    Nam, Hyo Geun; Yoo, Chang Min; Baek, Seoung Min; Kim, Han Ki; Shin, Jae Hee; Hwang, Min Ho; Jo, Ga Eun; Kim, Kyong Soo; Cho, Jae Hwa; Lee, Seung Hoon; Kim, Ho Chul; Lim, Chun Hak; Choi, Hyuk; Sun, Kyung

    2015-12-01

    Stents are promising medical devices widely used in the prevention of cerebral aneurysm rupture. As the performance of stents depends on their mechanical properties and cell configuration, the aim of this study was to optimize the stent design and test the hemodynamic properties by using computational solid mechanics and computational fluid dynamics. In order to test their performance, computer-based cerebral aneurysm models that mimic the conditions present after implantation into the human brain were tested. The strut configuration selected was the closed-cell type, and nitinol was chosen as the material for stent manufacture because the innate characteristics of this material increase stent flexibility. Three ideal sample stent types with different cell configurations were manufactured. Computational solid mechanics analysis of the sample stents showed over 30% difference in flexibility between stents. Furthermore, using a cerebral aneurysm model simulation, we found that the stents eased the hemodynamic factors of the cerebral aneurysm and lessened the flow velocity influx into the sac. A decrease in flow velocity led to a 50-60% reduction in wall shear stress, which is expected to prevent aneurysm rupture under clinical conditions. Stent design optimization was carried out by simulation and electropolishing. Corrosion resistance and surface roughness were evaluated after electropolishing performed under variable conditions, but 40 V and 10 s were the most optimal. PMID:26416549

  2. Deformable Surface Model for the Evaluation of Abdominal Aortic Aneurysms Treated with an Endovascular Sealing System.

    PubMed

    Casciaro, Mariano E; El-Batti, Salma; Chironi, Gilles; Simon, Alain; Mousseaux, Elie; Armentano, Ricardo L; Alsac, Jean-Marc; Craiem, Damian

    2016-05-01

    Rupture of abdominal aortic aneurysms (AAA) is responsible for 1-3% of all deaths among the elderly population in developed countries. A novel endograft proposes an endovascular aneurysm sealing (EVAS) system that isolates the aneurysm wall from blood flow using a polymer-filled endobag that surrounds two balloon-expandable stents. The volume of injected polymer is determined by monitoring the endobag pressure but the final AAA expansion remains unknown. We conceived and developed a fully deformable surface model for the comparison of pre-operative sac lumen size and final endobag size (measured using a follow-up scan) with the volume of injected polymer. Computed tomography images were acquired for eight patients. Aneurysms were manually and automatically segmented twice by the same observer. The injected polymer volume resulted 9% higher than the aneurysm pre-operative lumen size (p < 0.05), and 11% lower than the final follow-up endobag volume (p < 0.01). The automated method required minimal user interaction; it was fast and used a single set of parameters for all subjects. Intra-observer and manual vs. automated variability of measured volumes were 0.35 ± 2.11 and 0.07 ± 3.04 mL, respectively. Deformable surface models were used to quantify AAA size and showed that EVAS system devices tended to expand the sac lumen size. PMID:26350505

  3. Preliminary Computational Hemodynamics Study of Double Aortic Aneurysms under Multistage Surgical Procedures: An Idealised Model Study

    PubMed Central

    Otsuki, Yosuke; Bui Minh, Nhat; Ohtake, Hiroshi; Watanabe, Go; Matsuzawa, Teruo

    2013-01-01

    Double aortic aneurysm (DAA) falls under the category of multiple aortic aneurysms. Repair is generally done through staged surgery due to low invasiveness. In this approach, one aneurysm is cured per operation. Therefore, two operations are required for DAA. However, post-first-surgery rupture cases have been reported. Although the problems involved with managing staged surgery have been discussed for more than 30 years, investigation from a hemodynamic perspective has not been attempted. Hence, this is the first computational fluid dynamics approach to the DAA problem. Three idealized geometries were prepared: presurgery, thoracic aortic aneurysm (TAA) cured, and abdominal aortic aneurysm (AAA) cured. By applying identical boundary conditions for flow rate and pressure, the Navier-Stokes equation and continuity equations were solved under the Newtonian fluid assumption. Average pressure in TAA was increased by AAA repair. On the other hand, average pressure in AAA was decreased after TAA repair. Average wall shear stress was decreased at the peak in post-first-surgery models. However, the wave profile of TAA average wall shear stress was changed in the late systole phase after AAA repair. Since the average wall shear stress in the post-first-surgery models decreased and pressure at TAA after AAA repair increased, the TAA might be treated first to prevent rupture. PMID:24348172

  4. Hemodynamic performance of coil embolization and stentassisted coil embolization treatments: a numerical comparative study based on subject-specific models of cerebral aneurysms

    NASA Astrophysics Data System (ADS)

    Wang, Shengzhang; Zhang, Yisen; Lu, Gang; Yang, Xinjian; Zhang, Xiaolong; Ding, Guanghong

    2011-11-01

    Hemodynamic characteristics such as blood velocity, blood pressure, flow impingement, wall shear stress and oscillatory shear index are considered to play important roles in the initiation, growth, rupture and recurrence of the cerebral aneurysms. Endovascular therapy is widely implemented to treat the cerebral aneurysms by releasing coils into the aneurysm sac for limiting the blood flow to the sac and stent-assisted coil embolization is adopted to occlude the wide-necked or complex aneurysms. Some researchers believe that stents are not only a mechanical device but may act as a biological system and contribute to vessel wall healing. Hemodynamics simulation helps people understand the effect of hemodynamic characteristics on the recurrence of the coiled aneurysm and it also benefits the interventional planning of neurosurgeons. This study constructed the numerical model for a subject-specific ICA aneurysm treated with stent-assisted coil embolization, which combined the coiled model of the aneurysm with a porous stent placement, and simulated the pulsatile blood flow in these aneurysm models. When a stent was placed across the aneurysm orifice in the coiled aneurysm, the high wall shear stress around the distal aneurysm root was reduced more than that of the coiled aneurysm without a stent. The simulated results point to the conclusion that the stent not only protects the parent artery from occlusion due to extension of coils or thrombosis, but may also reduce the recurrence risk of the stent-assisted coiled aneurysm.

  5. Optical coherence tomography assessment of vessel wall degradation in thoracic aortic aneurysms

    NASA Astrophysics Data System (ADS)

    Real, Eusebio; Eguizabal, Alma; Pontón, Alejandro; Díez, Marta Calvo; Fernando Val-Bernal, José; Mayorga, Marta; Revuelta, José M.; López-Higuera, José M.; Conde, Olga M.

    2013-12-01

    Optical coherence tomography images of human thoracic aorta from aneurysms reveal elastin disorders and smooth muscle cell alterations when visualizing the media layer of the aortic wall. These disorders can be employed as indicators for wall degradation and, therefore, become a hallmark for diagnosis of risk of aneurysm under intraoperative conditions. Two approaches are followed to evaluate this risk: the analysis of the reflectivity decay along the penetration depth and the textural analysis of a two-dimensional spatial distribution of the aortic wall backscattering. Both techniques require preprocessing stages for the identification of the air-sample interface and for the segmentation of the media layer. Results show that the alterations in the media layer of the aortic wall are better highlighted when the textural approach is considered and also agree with a semiquantitative histopathological grading that assesses the degree of wall degradation. The correlation of the co-occurrence matrix attains a sensitivity of 0.906 and specificity of 0.864 when aneurysm automatic diagnosis is evaluated with a receiver operating characteristic curve.

  6. Exploring smooth muscle phenotype and function in a bioreactor model of abdominal aortic aneurysm

    PubMed Central

    2013-01-01

    Background Vascular smooth muscle cells (SMC) are central to arterial structure and function yet their involvement in the progression of abdominal aortic aneurysm (AAA) disease is not well studied. The progressive and silent nature of AAA in man essentially restricts research to the use of “end-stage” tissue recovered during surgical repair. This study aimed to generate an ex vivo model of AAA using protease-treated porcine carotid arteries maintained in a novel bioreactor, and to compare the structural and functional changes in SMC cultured from the recovered vessels with those from human tissue acquired at elective surgical repair. Methods Freshly isolated porcine arteries were pretreated with collagenase and/or elastase before culturing under flow in a bioreactor for 12 days. Human end-stage aneurysmal tissue and saphenous veins from age-matched controls were collected from patients undergoing surgery. SMC were cultured and characterised (immunocytochemistry, measurement of spread cell area) and assessed functionally at the level of proliferation (cell-counting) and matrix-metalloproteinase (MMP) secretion (gelatin zymography). Cellular senescence was investigated using β-galactosidase staining and apoptosis was quantified using a fluorescence-based caspase 3 assay. Results Co-expression of alpha-smooth muscle actin and smooth muscle myosin heavy chain confirmed all cell populations as SMC. Porcine SMC harvested and cultivated after collagenase/elastase pretreatment displayed a prominent “rhomboid” morphology, increased spread area (32%, P < 0.01), impaired proliferation (47% reduction, P < 0.05), increased senescence (52%, P < 0.001), susceptibility to apoptosis and reduced MMP-2 secretion (60% decrease, P < 0.01) compared with SMC from vehicle, collagenase or elastase pre-treated vessels. Notably, these changes were comparable to those observed in human AAA SMC which were 2.4-fold larger than non-aneurysmal SMC (P < 0.001) and

  7. Thrombotic risk stratification using computational modeling in patients with coronary artery aneurysms following Kawasaki disease

    PubMed Central

    Sengupta, Dibyendu; Kahn, Andrew M.; Kung, Ethan; Moghadam, Mahdi Esmaily; Shirinsky, Olga; Lyskina, Galina A.; Burns, Jane C.; Marsden, Alison L.

    2016-01-01

    Kawasaki disease (KD) is the leading cause of acquired heart disease in children and can result in life-threatening coronary artery aneurysms in up to 25 % of patients. These aneurysms put patients at risk of thrombus formation, myocardial infarction, and sudden death. Clinicians must therefore decide which patients should be treated with anticoagulant medication, and/or surgical or percutaneous intervention. Current recommendations regarding initiation of anticoagulant therapy are based on anatomy alone with historical data suggesting that patients with aneurysms ≥8 mm are at greatest risk of thrombosis. Given the multitude of variables that influence thrombus formation, we postulated that hemodynamic data derived from patient-specific simulations would more accurately predict risk of thrombosis than maximum diameter alone. Patient-specific blood flow simulations were performed on five KD patients with aneurysms and one KD patient with normal coronary arteries. Key hemodynamic and geometric parameters, including wall shear stress, particle residence time, and shape indices, were extracted from the models and simulations and compared with clinical outcomes. Preliminary fluid structure interaction simulations with radial expansion were performed, revealing modest differences in wall shear stress compared to the rigid wall case. Simulations provide compelling evidence that hemodynamic parameters may be a more accurate predictor of thrombotic risk than aneurysm diameter alone and motivate the need for follow-up studies with a larger cohort. These results suggest that a clinical index incorporating hemodynamic information be used in the future to select patients for anticoagulant therapy. PMID:24722951

  8. Blood flow in intracranial aneurysms treated with Pipeline embolization devices: computational simulation and verification with Doppler ultrasonography on phantom models

    PubMed Central

    2015-01-01

    Purpose: The aim of this study was to validate a computational fluid dynamics (CFD) simulation of flow-diverter treatment through Doppler ultrasonography measurements in patient-specific models of intracranial bifurcation and side-wall aneurysms. Methods: Computational and physical models of patient-specific bifurcation and sidewall aneurysms were constructed from computed tomography angiography with use of stereolithography, a three-dimensional printing technology. Flow dynamics parameters before and after flow-diverter treatment were measured with pulse-wave and color Doppler ultrasonography, and then compared with CFD simulations. Results: CFD simulations showed drastic flow reduction after flow-diverter treatment in both aneurysms. The mean volume flow rate decreased by 90% and 85% for the bifurcation aneurysm and the side-wall aneurysm, respectively. Velocity contour plots from computer simulations before and after flow diversion closely resembled the patterns obtained by color Doppler ultrasonography. Conclusion: The CFD estimation of flow reduction in aneurysms treated with a flow-diverting stent was verified by Doppler ultrasonography in patient-specific phantom models of bifurcation and side-wall aneurysms. The combination of CFD and ultrasonography may constitute a feasible and reliable technique in studying the treatment of intracranial aneurysms with flow-diverting stents. PMID:25754367

  9. Predictive Models with Patient Specific Material Properties for the Biomechanical Behavior of Ascending Thoracic Aneurysms.

    PubMed

    Trabelsi, Olfa; Duprey, Ambroise; Favre, Jean-Pierre; Avril, Stéphane

    2016-01-01

    The aim of this study is to identify the patient-specific material properties of ascending thoracic aortic aneurysms (ATAA) using preoperative dynamic gated computed tomography (CT) scans. The identification is based on the simultaneous minimization of two cost functions, which define the difference between model predictions and gated CT measurements of the aneurysm volume at respectively systole and cardiac mid-cycle. The method is applied on five patients who underwent surgical repair of their ATAA at the University Hospital Center of St. Etienne. For these patients, the aneurysms were collected and tested mechanically using an in vitro bench. For the sake of validation, the mechanical properties found using the in vivo approach and the in vitro bench were compared. We eventually performed finite-element stress analyses based on each set of material properties. Rupture risk indexes were estimated and compared, showing promising results of the patient-specific identification method based on gated CT. PMID:26178871

  10. Image based hemodynamic modeling of cerebral aneurysms and the determination of the risk of rupture

    NASA Astrophysics Data System (ADS)

    Kroon, D. J.; Slump, C. H.; Sluzewski, M.; van Rooij, W. J. J.

    2006-03-01

    This paper is about the quantitative prediction of the long term outcome of the endovascular coiling treatment of a patient's cerebral aneurysm. It is generally believed that the local hemodynamic properties of the patient's cerebral arteries are strongly influencing the origin and growth of aneurysms. We describe our approach: modelling the flow in a 3D Rotational Angiography (3DRA) reconstruction of the aneurysms including supplying and draining blood vessels, in combination with simulations and experiments of artificial blood vessel phantom constructs and measurements. The goal is to obtain insight in the observed phenomena to support the diagnostic decision process in order to predict the outcome of the intervention with possible simulation of the flow alternation due to the pertinent intervention.

  11. Flow modification in canine intracranial aneurysm model by an asymmetric stent: studies using digital subtraction angiography (DSA) and image-based computational fluid dynamics (CFD) analyses

    PubMed Central

    Hoi, Yiemeng; Ionita, Ciprian N.; Tranquebar, Rekha V.; Hoffmann, Kenneth R.; Woodward, Scott, H.; Taulbee, Dale B.; Meng, Hui; Rudin, Stephen

    2011-01-01

    An asymmetric stent with low porosity patch across the intracranial aneurysm neck and high porosity elsewhere is designed to modify the flow to result in thrombogenesis and occlusion of the aneurysm and yet to reduce the possibility of also occluding adjacent perforator vessels. The purposes of this study are to evaluate the flow field induced by an asymmetric stent using both numerical and digital subtraction angiography (DSA) methods and to quantify the flow dynamics of an asymmetric stent in an in vivo aneurysm model. We created a vein-pouch aneurysm model on the canine carotid artery. An asymmetric stent was implanted at the aneurysm, with 25% porosity across the aneurysm neck and 80% porosity elsewhere. The aneurysm geometry, before and after stent implantation, was acquired using cone beam CT and reconstructed for computational fluid dynamics (CFD) analysis. Both steady-state and pulsatile flow conditions using the measured waveforms from the aneurysm model were studied. To reduce computational costs, we modeled the asymmetric stent effect by specifying a pressure drop over the layer across the aneurysm orifice where the low porosity patch was located. From the CFD results, we found the asymmetric stent reduced the inflow into the aneurysm by 51%, and appeared to create a stasis-like environment which favors thrombus formation. The DSA sequences also showed substantial flow reduction into the aneurysm. Asymmetric stents may be a viable image guided intervention for treating intracranial aneurysms with desired flow modification features. PMID:21666881

  12. HiFiVS Modeling of Flow Diverter Deployment Enables Hemodynamic Characterization of Complex Intracranial Aneurysm Cases

    PubMed Central

    Xiang, Jianping; Damiano, Robert J.; Lin, Ning; Snyder, Kenneth V.; Siddiqui, Adnan H.; Levy, Elad I.; Meng, Hui

    2016-01-01

    Object Flow diversion via Pipeline Embolization Device (PED) represents the most recent advancement in endovascular therapy of intracranial aneurysms. This exploratory study aims at a proof of concept for an advanced device-modeling tool in conjunction with computational fluid dynamics (CFD) to evaluate flow modification effects by PED in real treatment cases. Methods We performed computational modeling of three PED-treated complex aneurysm cases. Case I had a fusiform vertebral aneurysm treated with a single PED. Case II had a giant internal carotid artery (ICA) aneurysm treated with 2 PEDs. Case III consisted of two tandem ICA aneurysms (a and b) treated by a single PED. Our recently developed high fidelity virtual stenting (HiFiVS) technique was used to recapitulate the clinical deployment process of PEDs in silico for these three cases. Pre- and post-treatment aneurysmal hemodynamics using CFD simulation was analyzed. Changes in aneurysmal flow velocity, inflow rate, and wall shear stress (WSS) (quantifying flow reduction) and turnover time (quantifying stasis) were calculated and compared with clinical outcome. Results In Case I (occluded within the first 3 months), the aneurysm experienced the most drastic aneurysmal flow reduction after PED placement, where the aneurysmal average velocity, inflow rate and average WSS was decreased by 76.3%, 82.5% and 74.0%, respectively, while the turnover time was increased to 572.1% of its pre-treatment value. In Case II (occluded at 6 months), aneurysmal average velocity, inflow rate and average WSS were decreased by 39.4%, 38.6%, and 59.1%, respectively, and turnover time increased to 163.0%. In Case III, Aneurysm III-a (occluded at 6 months) experienced decrease by 38.0%, 28.4%, and 50.9% in aneurysmal average velocity, inflow rate and average WSS, respectively and increase to 139.6% in turnover time, which was quite similar to Aneurysm II. Surprisingly, the adjacent Aneurysm III-b experienced more substantial flow

  13. Establishment of a chronic left ventricular aneurysm model in rabbit

    PubMed Central

    Xiao, Cang-Song; Gao, Chang-Qing; Li, Li-Bing; Wang, Yao; Zhao, Tao; Ye, Wei-Hua; Ren, Chong-Lei; Liu, Zhi-Yong; Wu, Yang

    2014-01-01

    Objectives To establish a cost-effective and reproducible procedure for induction of chronic left ventricular aneurysm (LVA) in rabbits. Methods Acute myocardial infarction (AMI) was induced in 35 rabbits via concomitant ligation of the left anterior descending (LAD) coronary artery and the circumflex (Cx) branch at the middle portion. Development of AMI was confirmed by ST segment elevation and akinesis of the occluded area. Echocardiography, pathological evaluation, and agar intra-chamber casting were utilized to validate the formation of LVA four weeks after the surgery. Left ventricular end systolic pressure (LVESP) and diastolic pressure (LVEDP) were measured before, immediately after and four weeks after ligation. Dimensions of the ventricular chamber, thickness of the interventricular septum (IVS) and the left ventricular posterior wall (LVPW) left ventricular end diastolic volume (LVEDV), systolic volume (LVESV), and ejection fraction (EF) were recorded by echocardiogram. Results Thirty one (88.6%) rabbits survived myocardial infarction and 26 of them developed aneurysm (83.9%). The mean area of aneurysm was 33.4% ± 2.4% of the left ventricle. LVEF markedly decreased after LVA formation, whereas LVEDV, LVESV and the thickness of IVS as well as the dimension of ventricular chamber from apex to mitral valve annulus significantly increased. LVESP immediately dropped after ligation and recovered to a small extent after LVA formation. LVEDP progressively increased after ligation till LVA formation. Areas in the LV that underwent fibrosis included the apex, anterior wall and lateral wall but not IVS. Agar intra-chamber cast showed that the bulging of LV wall was prominent in the area of aneurysm. Conclusions Ligation of LAD and Cx at the middle portion could induce development of LVA at a mean area ratio of 33.4% ± 2.4% which involves the apex, anterior wall and lateral wall of the left ventricle. PMID:25009567

  14. Cerebral Aneurysms

    MedlinePlus

    ... Enhancing Diversity Find People About NINDS NINDS Cerebral Aneurysms Information Page Synonym(s): Aneurysm, Brain Aneurysm Condensed from ... Español Additional resources from MedlinePlus What is Cerebral Aneurysms? A cerebral aneurysm is a weak or thin ...

  15. Commentary on “Inhibition of interleukin-1beta decreases aneurysm formation and progression in a novel model of thoracic aortic aneurysms”

    PubMed Central

    Bi, Yonghua; Zhong, Hongshan; Han, Xinwei; Xu, Ke

    2015-01-01

    Aortic aneurysm is a silent but life-threatening disease, whose pathogenesis remains poorly understood. Aneurysm models have been induced in small animals to study its pathogenesis, Johnston WF et al. successfully induced a novel model of thoracic aortic aneurysms (TAA) by periadventitial application of elastase in mice. We comment on this model according to our experiment. We hypothesize that endogenous MMPs, especially MMP2, play a vital role in complex repair process of aneurysmal wall, which should be a key target in the investigation and treatment of aortic aneurysms. PMID:26587231

  16. 2-Photon Characterization of Optical Proteolytic Beacons for Imaging Changes in Matrix-Metalloprotease Activity in a Mouse Model of Aneurysm

    PubMed Central

    Haskett, Darren G.; Maestas, David; Howerton, Stephen J.; Smith, Tyler; Ardila, D. Catalina; Doetschman, Tom; Utzinger, Urs; McGrath, Dominic; McIntyre, J. Oliver; Vande Geest, Jonathan P.

    2016-01-01

    Abdominal aortic aneurysm is a multifactorial disease that is a leading cause of death in developed countries. Matrix-metalloproteases (MMPs) are part of the disease process, however, assessing their role in disease initiation and progression has been difficult and animal models have become essential. Combining Förster resonance energy transfer (FRET) proteolytic beacons activated in the presence of MMPs with 2-photon microscopy allows for a novel method of evaluating MMP activity within the extracellular matrix (ECM). Single and 2-photon spectra for proteolytic beacons were determined in vitro. Ex vivo experiments using the apolipoprotein E knockout angiotensin II-infused mouse model of aneurysm imaged ECM architecture simultaneously with the MMP-activated FRET beacons. 2-photon spectra of the two-color proteolytic beacons showed peaks for the individual fluorophores that enable imaging of MMP activity through proteolytic cleavage. Ex vivo imaging of the beacons within the ECM revealed both microstructure and MMP activity. 2-photon imaging of the beacons in aneurysmal tissue showed an increase in proteolytic cleavage within the ECM (p < 0.001), thus indicating an increase in MMP activity. Our data suggest that FRET-based proteolytic beacons show promise in assessing MMP activity within the ECM and will therefore allow future studies to identify the heterogeneous distribution of simultaneous ECM remodeling and protease activity in aneurysmal disease. PMID:26903264

  17. 2-Photon Characterization of Optical Proteolytic Beacons for Imaging Changes in Matrix-Metalloprotease Activity in a Mouse Model of Aneurysm.

    PubMed

    Haskett, Darren G; Maestas, David; Howerton, Stephen J; Smith, Tyler; Ardila, D Catalina; Doetschman, Tom; Utzinger, Urs; McGrath, Dominic; McIntyre, J Oliver; Vande Geest, Jonathan P

    2016-04-01

    Abdominal aortic aneurysm is a multifactorial disease that is a leading cause of death in developed countries. Matrix-metalloproteases (MMPs) are part of the disease process, however, assessing their role in disease initiation and progression has been difficult and animal models have become essential. Combining Förster resonance energy transfer (FRET) proteolytic beacons activated in the presence of MMPs with 2-photon microscopy allows for a novel method of evaluating MMP activity within the extracellular matrix (ECM). Single and 2-photon spectra for proteolytic beacons were determined in vitro. Ex vivo experiments using the apolipoprotein E knockout angiotensin II-infused mouse model of aneurysm imaged ECM architecture simultaneously with the MMP-activated FRET beacons. 2-photon spectra of the two-color proteolytic beacons showed peaks for the individual fluorophores that enable imaging of MMP activity through proteolytic cleavage. Ex vivo imaging of the beacons within the ECM revealed both microstructure and MMP activity. 2-photon imaging of the beacons in aneurysmal tissue showed an increase in proteolytic cleavage within the ECM (p<0.001), thus indicating an increase in MMP activity. Our data suggest that FRET-based proteolytic beacons show promise in assessing MMP activity within the ECM and will therefore allow future studies to identify the heterogeneous distribution of simultaneous ECM remodeling and protease activity in aneurysmal disease. PMID:26903264

  18. Development of a static bioactive stent prototype and dynamic aneurysm-on-a-chip(TM) model for the treatment of aneurysms

    NASA Astrophysics Data System (ADS)

    Reece, Lisa M.

    Aneurysms are pockets of blood that collect outside blood vessel walls forming dilatations and leaving arterial walls very prone to rupture. Current treatments include: (1) clipping, and (2) coil embolization, including stent-assisted coiling. While these procedures can be effective, it would be advantageous to design a biologically active stent, modified with magnetic stent coatings, allowing cells to be manipulated to heal the arterial lining. Further, velocity, pressure, and wall shear stresses aid in the disease development of aneurysmal growth, but the shear force mechanisms effecting wound closure is elusive. Due to these factors, there is a definite need to cultivate a new stent device that will aid in healing an aneurysm in situ. To this end, a static bioactive stent device was synthesized. Additionally, to study aneurysm pathogenesis, a lab-on-a-chip device (a dynamic stent device) is the key to discovering the underlying mechanisms of these lesions. A first step to the reality of a true bioactive stent involves the study of cells that can be tested against the biomaterials that constitute the stent itself. The second step is to test particles/cells in a microfluidic environment. Therefore, biocompatability data was collected against PDMS, bacterial nanocellulose (BNC), and magnetic bacterial nanocellulose (MBNC). Preliminary static bioactive stents were synthesized whereby BNC was grown to cover standard nitinol stents. In an offshoot of the original research, a two-dimensional microfluidic model, the Aneurysm-on-a-ChipTM (AOC), was the logical answer to study particle flow within an aneurysm "sac" - this was the dynamic bioactive stent device. The AOC apparatus can track particles/cells when it is coupled to a particle image velocimetry software (PIV) package. The AOC fluid flow was visualized using standard microscopy techniques with commercial microparticles/cells. Movies were taken during fluid flow experiments and PIV was utilized to monitor.

  19. Characterization of cerebral aneurysms using 3D moment invariants

    NASA Astrophysics Data System (ADS)

    Millan, Raul D.; Hernandez, Monica; Gallardo, Daniel; Cebral, Juan R.; Putman, Christopher; Dempere-Marco, Laura; Frangi, Alejandro F.

    2005-04-01

    The rupture mechanism of intracranial aneurysms is still not fully understood. Although the size of the aneurysm is the shape index most commonly used to predict rupture, some controversy still exists about its adequateness as an aneurysm rupture predictor. In this work, an automatic method to geometrically characterize the shape of cerebral saccular aneurysms using 3D moment invariants is proposed. Geometric moments are efficiently computed via application of the Divergence Theorem over the aneurysm surface using a non-structured mesh. 3D models of the aneurysm and its connected parent vessels have been reconstructed from segmentations of both 3DRA and CTA images. Two alternative approaches have been used for segmentation, the first one based on isosurface deformable models, and the second one based on the level set method. Several experiments were also conducted to both assess the influence of pre-processing steps in the stability of the aneurysm shape descriptors, and to know the robustness of the proposed method. Moment invariants have proved to be a robust technique while providing a reliable way to discriminate between ruptured and unruptured aneurysms (Sensitivity=0.83, Specificity=0.74) on a data set containing 55 aneurysms. Further investigation over larger databases is necessary to establish their adequateness as reliable predictors of rupture risk.

  20. Modeling of the acute effects of primary hypertension and hypotension on the hemodynamics of intracranial aneurysms.

    PubMed

    Sarrami-Foroushani, Ali; Villa-Uriol, Maria-Cruz; Nasr Esfahany, Mohsen; Coley, Stuart C; Di Marco, Luigi Yuri; Frangi, Alejandro F; Marzo, Alberto

    2015-01-01

    Hemodynamics is a risk factor in intracranial aneurysms (IA). Hypertension and pharmacologically induced hypotension are common in IA patients. This study investigates how hypertension and hypotension may influence aneurysmal hemodynamics. Images of 23 IAs at typical locations were used to build patient-specific Computational Fluid Dynamics models. The effects of hypotension and hypertension were simulated through boundary conditions by modulating the normotensive flow and pressure waveforms, in turn produced by a 1D systemic vascular model. Aneurysm location and flow pattern types were used to categorize the influence of hypotension and hypertension on relevant flow variables (velocity, pressure and wall shear stress). Results indicate that, compared to other locations, vertebrobasilar aneurysms (VBA) are more sensitive to flow changes. In VBAs, space-averaged velocity at peak systole increased by 30% in hypertension (16-21% in other locations). Flow in VBAs in hypotension decreased by 20% (10-13% in other locations). Momentum-driven hemodynamic types were also more affected by hypotension and hypertension, than shear-driven types. This study shows how patient-specific modeling can be effectively used to identify location-specific flow patterns in a clinically-relevant study, thus reinforcing the role played by modeling technologies in furthering our understanding of cardiovascular disease, and their potential in future healthcare. PMID:25118666

  1. Biomechanical behaviour of cerebral aneurysm and its relation with the formation of intraluminal thrombus: a patient-specific modelling study.

    PubMed

    Wang, Xiaohong; Li, Xiaoyang

    2013-01-01

    Cerebral aneurysm is an irreversible dilatation causing intracranial haemorrhage with severe complications. It is assumed that the biomechanical factor plays a significant role in the development of cerebral aneurysm. However, reports on the correlations between the formation of intraluminal thrombus and the flow pattern, wall shear stress (WSS) distribution of the cerebral aneurysm as well as wall compliance are still limited. In this research, patient-specific numerical simulation was carried out for three cerebral aneurysms based on magnetic resonance imaging (MRI) data-sets. The interaction between pulsatile blood and aneurysm wall was taken into account. The biomechanical behaviour of cerebral aneurysm and its relation with the formation of intraluminal thrombus was studied systematically. The results of the numerical simulation indicated that the region of low blood flow velocity and the region of swirling recirculation were nearly coincident with each other. Besides, there was a significant correlation between the slow swirling flow and the location of thrombus deposition. Excessively low WSS was also found to have strong association with the regions of thrombus formation. Moreover, the relationship between cerebral aneurysm compliance and thrombus deposition was discovered. The patient-specific modelling study based on fluid-structure interaction) may provide a basis for future investigation on the prediction of thrombus formation in cerebral aneurysm. PMID:22292428

  2. A two-system, single-analysis, fluid-structure interaction technique for modelling abdominal aortic aneurysms.

    PubMed

    Kelly, S C; O'Rourke, M J

    2010-01-01

    This work reports on the implementation and validation of a two-system, single-analysis, fluid-structure interaction (FSI) technique that uses the finite volume (FV) method for performing simulations on abdominal aortic aneurysm (AAA) geometries. This FSI technique, which was implemented in OpenFOAM, included fluid and solid mesh motion and incorporated a non-linear material model to represent AAA tissue. Fully implicit coupling was implemented, ensuring that both the fluid and solid domains reached convergence within each time step. The fluid and solid parts of the FSI code were validated independently through comparison with experimental data, before performing a complete FSI simulation on an idealized AAA geometry. Results from the FSI simulation showed that a vortex formed at the proximal end of the aneurysm during systolic acceleration, and moved towards the distal end of the aneurysm during diastole. Wall shear stress (WSS) values were found to peak at both the proximal and distal ends of the aneurysm and remain low along the centre of the aneurysm. The maximum von Mises stress in the aneurysm wall was found to be 408kPa, and this occurred at the proximal end of the aneurysm, while the maximum displacement of 2.31 mm occurred in the centre of the aneurysm. These results were found to be consistent with results from other FSI studies in the literature. PMID:20923114

  3. Aortic Aneurysm

    MedlinePlus

    ... chest and abdomen. There are two types of aortic aneurysm: Thoracic aortic aneurysms - these occur in the part of the aorta running through the chest Abdominal aortic aneurysms - these occur in the part of the aorta ...

  4. Aortic Aneurysm

    MedlinePlus

    ... chest and abdomen. There are two types of aortic aneurysm: Thoracic aortic aneurysms (TAA) - these occur in the part of the aorta running through the chest Abdominal aortic aneurysms (AAA) - these occur in the part of the ...

  5. Aneurysm Repair

    MedlinePlus

    ... to other parts of the body (the aorta). Aortic aneurysms can occur in the area below the stomach ( ... or in the chest (thoracic aneurysms). An abdominal aortic aneurysm (AAA) is usually located below the kidneys. In ...

  6. Assessment of contrast flow modification in aneurysms treated with closed-cell self-deploying asymmetric vascular stents (SAVS).

    PubMed

    Ionita, Ciprian N; Wang, Weiyuan; Bednarek, Daniel R; Rudin, Stephen

    2010-01-01

    The Asymmetric Vascular Stent (AVS) for intracranial aneurysm (IA) treatment is an experimental device, specially designed for intra-aneurysmal blood flow diversion and thrombosis promotion. The stent has a low-porous patch to cover only the aneurysm neck while the rest of the stent is very porous to avoid blockage of adjacent branches. The latest AVS design is similar to state-of-art, closed-cell, self-expanding, neurovascular stent. The stents were used to treat sixteen rabbit-elastase aneurysm models. The treatment effect was analyzed using normalized-time-density-curves (NTDC) measured by pixel-value integration over a region-of-interest containing the aneurysm. Normalization constant was the total bolus injection determined angiographically. Based on NTDC measurement, five quantities were derived to describe the contrast flow. Two are related to the amount of contrast entering the aneurysm: NTDC peak and NTDC input slope. The other three are related to contrast presence in the aneurysmal dome: time-to-peak (TTP), wash-out-time (WOT) and mean-transit-time (MTT). Flow modification descriptions using the contrast related quantities were expressed as a pre-/post-stented NTDC parameter ratio, while the time related quantities were expressed as a post-/pre-stented ratio, so that ratios smaller than one indicate a desired effect. Thirteen aneurysms were treated successfully and achieved significant aneurysm occlusion. For these cases, the resulting average parameters were: peak-ratio=0.17±0.21; input-slope-ratio=0.19±0.24, TTP-ratio=0.17±0.21, WOT-ratio=0.58±0.73 and MTT-ratio=0.65±0.97). All the quantities revealed decreased aneurysmal flow due to blood flow diversion using the new self-expanding asymmetrical vascular stent (SAVS). Treatment outcome results and angiographic analysis indicate that the new self-deploying stent design has great potential for clinical implementation. PMID:21243093

  7. Fluid-structure interaction in axially symmetric models of abdominal aortic aneurysms.

    PubMed

    Fraser, K H; Li, M-X; Lee, W T; Easson, W J; Hoskins, P R

    2009-02-01

    Abdominal aortic aneurysm disease progression is probably influenced by tissue stresses and blood flow conditions and so accurate estimation of these will increase understanding of the disease and may lead to improved clinical practice. In this work the blood flow and tissue stresses in axially symmetric aneurysms are calculated using a complete fluid-structure interaction as a benchmark for calculating the error introduced by simpler calculations: rigid walled for the blood flow, homogeneous pressure for the tissue stress, as well as one-way-coupled interactions. The error in the peak von Mises stress in a homogeneous pressure calculation compared with a fluid-structure interaction calculation was less than 3.5 per cent for aneurysm diameters up to 7 cm. The error in the mean wall shear stress, in a rigid-walled calculation compared with a fluid-structure interaction calculation, varied from 30 per cent to 60 per cent with increasing aneurysm diameter. These results suggest that incorporation of the fluid-structure interaction is unnecessary for purely mechanical modelling, with the aim of evaluating the current rupture probability. However, for more complex biological modelling, perhaps with the aim of predicting the progress of the disease, where accurate estimation of the wall shear stress is essential, some form of fluid-structure interaction is necessary. PMID:19278197

  8. Flow dynamics in anatomical models of abdominal aortic aneurysms: computational analysis of pulsatile flow.

    PubMed

    Finol, Ender A; Amon, Cristina H

    2003-01-01

    Blood flow in human arteries is dominated by time-dependent transport phenomena. In particular, in the abdominal segment of the aorta under a patient's average resting conditions, blood exhibits laminar flow patterns that are influenced by secondary flows induced by adjacent branches and in irregular vessel geometries. The flow dynamics becomes more complex when there is a pathological condition that causes changes in the normal structural composition of the vessel wall, for example, in the presence of an aneurysm. An aneurysm is an irreversible dilation of a blood vessel accompanied by weakening of the vessel wall. This work examines the importance of hemodynamics in the characterization of pulsatile blood flow patterns in individual Abdominal Aortic Aneurysm (AAA) models. These patient-specific computational models have been developed for the numerical simulation of the momentum transport equations utilizing the Finite Element Method (FEM) for the spatial and temporal discretization. We characterize pulsatile flow dynamics in AAAs for average resting conditions by means of identifying regions of disturbed flow and quantifying the disturbance by evaluating wall pressure and wall shear stresses at the aneurysm wall. PMID:14515766

  9. Numerical modeling of the flow in intracranial aneurysms: prediction of regions prone to thrombus formation

    PubMed Central

    Rayz, V.L.; Boussel, L.; Lawton, M.T.; Acevedo-Bolton, G.; Ge, L.; Young, W.L.; Higashida, R.T.; Saloner, D.

    2009-01-01

    The deposition of intralumenal thrombus in intracranial aneurysms adds a risk of thrombo-embolism over and above that posed by mass-effect and rupture. In addition to biochemical factors, hemodynamic factors that are governed by lumenal geometry and blood flow rates likely play an important role in the thrombus formation and deposition process. In this study, patient-specific computational fluid dynamics (CFD) models of blood flow were constructed from MRA data for three patients who had fusiform basilar aneurysms that were thrombus-free and then proceeded to develop intra-lumenal thrombus. In order to determine whether features of the flow fields could suggest which regions had an elevated potential for thrombus deposition, the flow was modeled in the baseline, thrombus-free geometries. Pulsatile flow simulations were carried out using patient-specific inlet flow conditions measured with MR velocimetry. Newtonian and non-Newtonian blood behavior was considered. A strong similarity was found between the intra-aneurysmal regions with CFD-predicted slow, recirculating flows and the regions of thrombus deposition observed in vivo in the follow-up MR studies. In two cases with larger aneurysms, the agreement between the low velocity zones and clotted off regions improved when non-Newtonian blood behavior was taken into account. A similarity was also found between the calculated low shear stress regions and the regions that were later observed to clot. PMID:18787954

  10. Flat-detector computed tomography evaluation in an experimental animal aneurysm model after endovascular treatment: A pilot study.

    PubMed

    Ott, Sabine; Gölitz, Philipp; Adamek, Edyta; Royalty, Kevin; Doerfler, Arnd; Struffert, Tobias

    2015-08-01

    We compared flat-detector computed tomography angiography (FD-CTA) to multislice computed tomography (MS-CTA) and digital subtracted angiography (DSA) for the visualization of experimental aneurysms treated with stents, coils or a combination of both.In 20 rabbits, aneurysms were created using the rabbit elastase aneurysm model. Seven aneurysms were treated with coils, seven with coils and stents, and six with self-expandable stents alone. Imaging was performed by DSA, MS-CTA and FD-CTA immediately after treatment. Multiplanar reconstruction (MPR) was performed and two experienced reviewers compared aneurysm/coil package size, aneurysm occlusion, stent diameters and artifacts for each modality.In aneurysms treated with stents alone, the visualization of the aneurysms was identical in all three imaging modalities. Residual aneurysm perfusion was present in two cases and visible in DSA and FD-CTA but not in MS-CTA. The diameter of coil-packages was overestimated in MS-CT by 56% and only by 16% in FD-CTA compared to DSA (p < 0.05). The diameter of stents was identical for DSA and FD-CTA and was significantly overestimated in MS-CTA (p < 0.05). Beam/metal hardening artifacts impaired image quality more severely in MS-CTA compared to FD-CTA.MS-CTA is impaired by blooming and beam/metal hardening artifacts in the visualization of implanted devices. There was no significant difference between measurements made with noninvasive FD-CTA compared to gold standard of DSA after stenting and after coiling/stent-assisted coiling of aneurysms. FD-CTA may be considered as a non-invasive alternative to the gold standard 2D DSA in selected patients that require follow up imaging after stenting. PMID:26111985

  11. Challenges in imaging and histopathological assessment of a giant cell tumour with secondary aneurysmal cyst in the patella

    PubMed Central

    Low, Soo Fin; Hanafiah, Mohammad; Nurismah, Md Isa; Suraya, Aziz

    2013-01-01

    The patella is an uncommon site for all primary and metastatic bone tumours and primary intra-osseous tumours of the patella are very rare. A majority of the patella tumours are benign. We report a patient with a sudden onset swelling and pain of the right knee following a staircase fall. The plain radiograph showed an expansile multiseptated patella lesion and it was further assessed with an MRI. The radiological findings and the initial histopathological features from a limited sample were suggestive of a primary aneurysmal bone cyst. However, the final histopathological diagnosis from a more adequate specimen was a giant cell tumour with a secondary aneurysmal bone cyst. PMID:24057334

  12. Measurement of flow diverter hydraulic resistance to model flow modification in and around intracranial aneurysms

    PubMed Central

    Szikora, István; Paál, György

    2014-01-01

    Flow diverters (FDs) have been successfully applied in the recent decade to the treatment of intracranial aneurysms by impairing the communication between the flows in the parent artery and the aneurysm and, thus, the blood within the aneurysm sac. It would be desirable to have a simple and accurate computational method to follow the changes in the peri- and intraaneurysmal flow caused by the presence of FDs. The detailed flow simulation around the intricate wire structure of the FDs has three disadvantages: need for high amount of computational resources and highly skilled professionals to prepare the computational grid, and also the lack of validation that makes the invested effort questionable. In this paper, we propose a porous layer method to model the hydraulic resistance (HR) of one or several layers of the FDs. The basis of this proposal is twofold: first, from an application point of view, the only interesting parameter regarding the function of the FD is its HR; second, we have developed a method to measure the HR with a simple apparatus. We present the results of these measurements and demonstrate their utility in numerical simulations of patient-specific aneurysm simulations. PMID:24936307

  13. Volume Changes of Experimental Carotid Sidewall Aneurysms Due to Embolization with Liquid Embolic Agents: A Multidetector CT Angiography Study

    SciTech Connect

    Dudeck, O. Okuducu, A. F.; Jordan, O.; Tesmer, K.; Pech, M.; Weigang, E.; Ruefenacht, D. A.; Doelker, E.; Felix, R.

    2006-12-15

    Iodine-containing polyvinyl alcohol polymer (I-PVAL) is a novel precipitating liquid embolic that allows for artifact-free evaluation of CT angiography (CTA). As accurate aneurysm volumetry can be performed with multidetector CTA, we determined volumes of experimental aneurysms before, immediately after, and 4 weeks after embolization of 14 porcine experimental carotid sidewall aneurysms with this liquid embolic. An automated three-dimensional software measurement tool was used for volumetric analysis of volume-rendering CTA data. Furthermore, intra-aneurysmal pressure changes during liquid embolization were measured in four silicone aneurysms and potential polymer volume changes within 4 weeks were assessed in vitro. Liquid embolic injection was performed during temporary balloon occlusion of the aneurysm neck, resulting in a mean occlusion rate of 98.3%. Aneurysms enlarged significantly during embolization by 61.1 {+-} 28.9%, whereas a significant shrinkage of 5.6 {+-} 2.7% was observed within the follow-up period. Histologic analysis revealed an inflammatory foreign body reaction with partial polymer degradation. In silicone aneurysm models, intra-aneurysmal pressure remained unchanged during liquid embolic injection, whereas balloon inflation resulted in a mean pressure increase of 31.2 {+-} 0.7%. No polymer shrinkage was observed in vitro. The aneurysm enlargement noted was presumably due to pressure elevation after balloon inflation, which resulted in dilatation of the weak venous wall of the newly constructed aneurysm-another shortcoming of this experimental aneurysm model. The volume decrease after 4 weeks expressed partial polymer degradation.

  14. Assessment of Vascular Geometry for Bilateral Carotid Artery Ligation to Induce Early Basilar Terminus Aneurysmal Remodeling in Rats.

    PubMed

    Tutino, Vincent Matthew; Liaw, Nicholas; Spernyak, Joseph Andrew; Ionita, Ciprian Nicolae; Siddiqui, Adnan Hussain; Kolega, John; Meng, Hui

    2016-01-01

    Bilateral common carotid artery (CCA) ligation in rabbits is a model for basilar terminus (BT) aneurysm formation. We asked if this model could be replicated in rats. Fourteen female Sprague Dawley rats underwent bilateral CCA ligation (n=8) or sham surgery (n=6). After 7 days, 5 ligated and 3 sham rats were euthanized for histological evaluation of BT aneurysm formation, while the remaining rats were imaged with magnetic resonance angiography, euthanized, and subjected to corrosion casting of the Circle of Willis (CoW). 3D micro computed tomography images of CoW casts were used for flow simulations at the rat BT, and electron micrographs of the casts were analyzed for aneurysmal and morphological changes. Results from these analyses were compared to rabbit model data (n=10 ligated and n=6 sham). Bilateral CCA ligation did not produce aneurysmal damage at the rat BT. While the surgical manipulation increased rat basilar artery flow, fluid dynamics simulations showed that the initial hemodynamic stress at the rat BT was significantly less than in rabbits. Rats also exhibited fewer morphological and pathological changes (minor changes only occurred in the posterior CoW) than rabbits, which had drastic changes throughout the CoW. A comparison of CoW anatomies demonstrated a greater number of branching arteries at the BT, larger CoW arteries in relation to basilar artery, and a steeper BT bifurcation angle in the rat. These differences could account for the lower hemodynamic stress at the BT and in the cerebrovasculature of the rat. In conclusion, bilateral CCA ligation in rats does not recapitulate the rabbit model of early flow-induced BT aneurysm. We suspect that the different CoW morphology of the rat lessens hemodynamic insults, thereby diminishing flow-induced aneurysmal remodeling. PMID:26503026

  15. Measurement with microscopic MRI and simulation of flow in different aneurysm models

    SciTech Connect

    Edelhoff, Daniel Frank, Frauke; Heil, Marvin; Suter, Dieter; Walczak, Lars; Weichert, Frank; Schmitz, Inge

    2015-10-15

    Purpose: The impact and the development of aneurysms depend to a significant degree on the exchange of liquid between the regular vessel and the pathological extension. A better understanding of this process will lead to improved prediction capabilities. The aim of the current study was to investigate fluid-exchange in aneurysm models of different complexities by combining microscopic magnetic resonance measurements with numerical simulations. In order to evaluate the accuracy and applicability of these methods, the fluid-exchange process between the unaltered vessel lumen and the aneurysm phantoms was analyzed quantitatively using high spatial resolution. Methods: Magnetic resonance flow imaging was used to visualize fluid-exchange in two different models produced with a 3D printer. One model of an aneurysm was based on histological findings. The flow distribution in the different models was measured on a microscopic scale using time of flight magnetic resonance imaging. The whole experiment was simulated using fast graphics processing unit-based numerical simulations. The obtained simulation results were compared qualitatively and quantitatively with the magnetic resonance imaging measurements, taking into account flow and spin–lattice relaxation. Results: The results of both presented methods compared well for the used aneurysm models and the chosen flow distributions. The results from the fluid-exchange analysis showed comparable characteristics concerning measurement and simulation. Similar symmetry behavior was observed. Based on these results, the amount of fluid-exchange was calculated. Depending on the geometry of the models, 7% to 45% of the liquid was exchanged per second. Conclusions: The result of the numerical simulations coincides well with the experimentally determined velocity field. The rate of fluid-exchange between vessel and aneurysm was well-predicted. Hence, the results obtained by simulation could be validated by the experiment. The

  16. [Rapid 3-Dimensional Models of Cerebral Aneurysm for Emergency Surgical Clipping].

    PubMed

    Konno, Takehiko; Mashiko, Toshihiro; Oguma, Hirofumi; Kaneko, Naoki; Otani, Keisuke; Watanabe, Eiju

    2016-08-01

    We developed a method for manufacturing solid models of cerebral aneurysms, with a shorter printing time than that involved in conventional methods, using a compact 3D printer with acrylonitrile-butadiene-styrene(ABS)resin. We further investigated the application and utility of this printing system in emergency clipping surgery. A total of 16 patients diagnosed with acute subarachnoid hemorrhage resulting from cerebral aneurysm rupture were enrolled in the present study. Emergency clipping was performed on the day of hospitalization. Digital Imaging and Communication in Medicine(DICOM)data obtained from computed tomography angiography(CTA)scans were edited and converted to stereolithography(STL)file formats, followed by the production of 3D models of the cerebral aneurysm by using the 3D printer. The mean time from hospitalization to the commencement of surgery was 242 min, whereas the mean time required for manufacturing the 3D model was 67 min. The average cost of each 3D model was 194 Japanese Yen. The time required for manufacturing the 3D models shortened to approximately 1 hour with increasing experience of producing 3D models. Favorable impressions for the use of the 3D models in clipping were reported by almost all neurosurgeons included in this study. Although 3D printing is often considered to involve huge costs and long manufacturing time, the method used in the present study requires shorter time and lower costs than conventional methods for manufacturing 3D cerebral aneurysm models, thus making it suitable for use in emergency clipping. PMID:27506842

  17. Fluid-Structure Interaction Modeling of Intracranial Aneurysm Hemodynamics: Effects of Different Assumptions

    NASA Astrophysics Data System (ADS)

    Rajabzadeh Oghaz, Hamidreza; Damiano, Robert; Meng, Hui

    2015-11-01

    Intracranial aneurysms (IAs) are pathological outpouchings of cerebral vessels, the progression of which are mediated by complex interactions between the blood flow and vasculature. Image-based computational fluid dynamics (CFD) has been used for decades to investigate IA hemodynamics. However, the commonly adopted simplifying assumptions in CFD (e.g. rigid wall) compromise the simulation accuracy and mask the complex physics involved in IA progression and eventual rupture. Several groups have considered the wall compliance by using fluid-structure interaction (FSI) modeling. However, FSI simulation is highly sensitive to numerical assumptions (e.g. linear-elastic wall material, Newtonian fluid, initial vessel configuration, and constant pressure outlet), the effects of which are poorly understood. In this study, a comprehensive investigation of the sensitivity of FSI simulations in patient-specific IAs is investigated using a multi-stage approach with a varying level of complexity. We start with simulations incorporating several common simplifications: rigid wall, Newtonian fluid, and constant pressure at the outlets, and then we stepwise remove these simplifications until the most comprehensive FSI simulations. Hemodynamic parameters such as wall shear stress and oscillatory shear index are assessed and compared at each stage to better understand the sensitivity of in FSI simulations for IA to model assumptions. Supported by the National Institutes of Health (1R01 NS 091075-01).

  18. Three-dimensional aortic aneurysm model and endovascular repair: An educational tool for surgical trainees

    PubMed Central

    Wilasrusmee, Chumpon; Suvikrom, Jesada; Suthakorn, Jackrit; Lertsithichai, Panuwat; Sitthiseriprapip, Kriskrai; Proprom, Napaphat; Kittur, Dilip S

    2008-01-01

    OBJECTIVES: Endovascular aortic aneurysm repair (EVAR) is a current valid treatment option for patients with abdominal aortic aneurysms (AAAs). The success of EVAR depends on the selection of appropriate patients, which requires detailed knowledge of the patient’s vascular anatomy and preoperative planning. Three-dimensional (3D) models of AAA using a rapid prototyping technique were developed to help surgical trainees learn how to plan for EVAR more effectively. METHOD: Four cases of AAA were used as prototypes for the models. Nine questions associated with preoperative planning for EVAR were developed by a group of experts in the field of endovascular surgery. Forty-three postgraduate trainees in general surgery participated in the present study. The participants were randomly assigned into two groups. The ‘intervention’ group was provided with the rapid prototyping AAA models along with 3D computed tomography (CT) corresponding to the cases of the test, while the control group was provided with 3D CTs only. RESULTS: Differences in the scores between the groups were tested using the unpaired t test. The mean test scores were consistently and significantly higher in the 3D CT group with models compared with the 3D CT group without models for all four cases. Age, year of training, sex and previous EVAR experience had no effect on the scores. CONCLUSION: The 3D aortic aneurysm model constructed using the rapid prototype technique may significantly improve the ability of trainees to properly plan for EVAR. PMID:22477415

  19. A Computational Model of Biochemomechanical Effects of Intraluminal Thrombus on the Enlargement of Abdominal Aortic Aneurysms.

    PubMed

    Virag, Lana; Wilson, John S; Humphrey, Jay D; Karšaj, Igor

    2015-12-01

    Abdominal aortic aneurysms (AAAs) typically develop an intraluminal thrombus (ILT), yet most computational models of AAAs have focused on either the mechanics of the wall or the hemodynamics within the lesion, both in the absence of ILT. In the few cases wherein ILT has been modeled directly, as, for example, in static models that focus on the state of stress in the aortic wall and the associated rupture risk, thrombus has been modeled as an inert, homogeneous, load-bearing material. Given the biochemomechanical complexity of an ILT, there is a pressing need to consider its diverse effects on the evolving aneurysmal wall. Herein, we present the first growth and remodeling model that addresses together the biomechanics, mechanobiology, and biochemistry of thrombus-laden AAAs. Whereas it has been shown that aneurysmal enlargement in the absence of ILT depends primarily on the stiffness and turnover of fibrillar collagen, we show that the presence of a thrombus within lesions having otherwise the same initial wall composition and properties can lead to either arrest or rupture depending on the biochemical effects (e.g., release of proteases) and biomechanical properties (e.g., stiffness of fibrin) of the ILT. These computational results suggest that ILT should be accounted for when predicting the potential enlargement or rupture risk of AAAs and highlight specific needs for further experimental and computational research. PMID:26070724

  20. Patient-specific computer modeling of blood flow in cerebral arteries with aneurysm and stent

    NASA Astrophysics Data System (ADS)

    Takizawa, Kenji; Schjodt, Kathleen; Puntel, Anthony; Kostov, Nikolay; Tezduyar, Tayfun E.

    2012-12-01

    We present the special arterial fluid mechanics techniques we have developed for patient-specific computer modeling of blood flow in cerebral arteries with aneurysm and stent. These techniques are used in conjunction with the core computational technique, which is the space-time version of the variational multiscale (VMS) method and is called "DST/SST-VMST." The special techniques include using NURBS for the spatial representation of the surface over which the stent mesh is built, mesh generation techniques for both the finite- and zero-thickness representations of the stent, techniques for generating refined layers of mesh near the arterial and stent surfaces, and models for representing double stent. We compute the unsteady flow patterns in the aneurysm and investigate how those patterns are influenced by the presence of single and double stents. We also compare the flow patterns obtained with the finite- and zero-thickness representations of the stent.

  1. A System for Computer-Assisted Design of Stent-Grafts for Aortic Aneurysms Using 3-D Morphological Models

    SciTech Connect

    Imai, Yasuhiro; Urayama, Shin-ich; Uyama, Chikao; Inoue, Kanji; Ueno, Katsuya; Kuribayashi, Sachio; Takamiya, Makoto; Hamada, Seiki; Hirane, Yoshihisa

    2001-07-15

    A three-dimensional model was constructed from helical CT images for abdominal aortic aneurysm (AAA) and thoracic aortic aneurysm (TAA). A stent-graft was designed and positioned endoluminally on the computer. One hundred and nine stent-grafts for 101 patients were designed by this method and deployed well in all patients. The design time was reduced from 4 to 0.5 hr.

  2. Coil Embolization for Intracranial Aneurysms

    PubMed Central

    2006-01-01

    , resulting in a subarachnoid hemorrhage (SAH), the mortality rate can be 40% to 50%, with severe morbidity of 10% to 20%. The reported overall risk of rupture is 1.9% per year and is higher for women, cigarette smokers, and cocaine users, and in aneurysms that are symptomatic, greater than 10 mm in diameter, or located in the posterior circulation. If left untreated, there is a considerable risk of repeat hemorrhage in a ruptured aneurysm that results in increased mortality. In Ontario, intracranial aneurysms occur in about 1% to 4% of the population, and the annual incidence of SAH is about 10 cases per 100,000 people. In 2004-2005, about 660 intracranial aneurysm repairs were performed in Ontario. Treatment of Intracranial Aneurysms Treatment of an unruptured aneurysm attempts to prevent the aneurysm from rupturing. The treatment of a ruptured intracranial aneurysm aims to prevent further hemorrhage. There are 3 approaches to treating an intracranial aneurysm. Small, asymptomatic aneurysms less than 10 mm in diameter may be monitored without any intervention other than treatment for underlying risk factors such as hypertension. Open surgical clipping, involves craniotomy, brain retraction, and placement of a silver clip across the neck of the aneurysm while a patient is under general anesthesia. This procedure is associated with surgical risks and neurological deficits. Endovascular coil embolization, introduced in the 1990s, is the health technology under review. Literature Review Methods The Medical Advisory Secretariat searched the International Health Technology Assessment (INAHTA) Database and the Cochrane Database of Systematic Reviews to identify relevant systematic reviews. OVID Medline, Medline In-Process and Other Non-Indexed Citations, and Embase were searched for English-language journal articles that reported primary data on the effectiveness or cost-effectiveness of treatments for intracranial aneurysms, obtained in a clinical setting or analyses of primary

  3. A microfabricated microfluidic bioMEMS device to model human brain aneurisms: the aneurysm-on-a-chip

    NASA Astrophysics Data System (ADS)

    Reece, Lisa M.; Khor, Jian Wei; Thakur, Raviraj; Amin, Ahmed; Wereley, Steven T.; Leary, James F.

    2015-03-01

    Aneurysms are pockets of blood that collect outside blood vessel walls forming dilatations and leaving arterial walls very prone to rupture. There is little information concerning the causes of intracranial aneurysm formation, growth, and rupture. Current treatments include: (1) clipping, and (2) coil embolization, including stent-assisted coiling. Further, the evolution of any aneurysm is assumed to be caused by the remodeling of the affected blood vessel's material constituents (tunica intima, tunica media, or tunica adventitia). Velocity, pressure, and wall shear stresses aid in the disease development of aneurysmal growth, while the shear force mechanisms effecting wound closure are elusive. To study aneurysm pathogenesis, a lab-on-a-chip device is the key to discovering the underlying mechanisms of these lesions. A two-dimensional microfluidic model, the Aneurysm-on-a-Chip™ (AOC), was the logical answer to study particle flow within an aneurysm "sac". The AOC apparatus can track particles/cells when it is coupled to particle image velocimetry software (PIV) package. The AOC fluid flow was visualized using standard microscopy techniques with commercial microparticles and human aortic smooth muscle cells (HASMC). Images were taken during fluid flow experiments and PIV was utilized to monitor the flow of particles within the "sac" region, as well as particles entering and exiting the device. Quiver plots were generated from fluid flow experiments using standard 7 μm latex particles and fixed HASMC in PBS. PIV analysis shows that the particles flowed nicely from input to output. Wall shear stress provided evidence that there was some back flow at the edges of the "sac" - an indicator of aneurysm development in human patients.

  4. Intracranial and Abdominal Aortic Aneurysms: Similarities, Differences, and Need for a New Class of Computational Models

    PubMed Central

    Humphrey, J.D.; Taylor, C.A.

    2009-01-01

    Intracranial and abdominal aortic aneurysms result from different underlying disease processes and exhibit different rupture potentials, yet they share many histopathological and biomechanical characteristics. Moreover, as in other vascular diseases, hemodynamics and wall mechanics play important roles in the natural history and possible treatment of these two types of lesions. The goals of this review are twofold: first, to contrast the biology and mechanics of intracranial and abdominal aortic aneurysms to emphasize that separate advances in our understanding of each disease can aid in our understanding of the other disease, and second, to suggest that research on the biomechanics of aneurysms must embrace a new paradigm for analysis. That is, past biomechanical studies have provided tremendous insight but have progressed along separate lines, focusing on either the hemodynamics or the wall mechanics. We submit that that there is a pressing need to couple in a new way the separate advances in vascular biology, medical imaging, and computational biofluid and biosolid mechanics to understand better the mechanobiology, pathophysiology, and treatment of these lesions, which continue to be responsible for significant morbidity and mortality. We shall refer to this needed new class of computational tools as Fluid-Solid-Growth (FSG) Models. PMID:18647115

  5. Micro-RNAs in abdominal aortic aneurysms: insights from animal models and relevance to human disease.

    PubMed

    Raffort, Juliette; Lareyre, Fabien; Clement, Marc; Mallat, Ziad

    2016-05-15

    Abdominal aortic aneurysm (AAA) is a major health concern and may be associated with high rates of mortality linked to acute complications. Diagnosis and treatment are, respectively, based on imaging and surgical techniques. Drug-based therapies are still mostly ineffective, which highlight a real unmet need. Major pathophysiological mechanisms leading to aneurysm formation involve inflammatory processes, degradation of the extracellular matrix, and loss of smooth muscle cells. However, the precise cellular and molecular pathways are still poorly understood. Recently, microRNAs have emerged as major intracellular players in a wide range of biological processes, and their stability in extracellular medium within microvesicles has led to propose them as mediators of intercellular crosstalk and as potential biomarkers and therapeutic targets in a variety of disease settings. To date, several studies have been performed to address the involvement of micro-RNAs (miRs) in aneurysm formation and complications. Here, we discuss the roles and implications of miRs in animal models and their relevance to human AAA. PMID:26965051

  6. Effects of Variations of Flow and Heart Rate on Intra-Aneurysmal Hemodynamics in a Ruptured Internal Carotid Artery Aneurysm During Exercise

    PubMed Central

    Sarrami-Foroushani, Ali; Nasr Esfahany, Mohsen; Saligheh Rad, Hamidreza; Firouznia, Kavous; Shakiba, Madjid; Ghanaati, Hossein

    2016-01-01

    Background: Hemodynamics is thought to play an important role in the mechanisms responsible for initiation, growth, and rupture of intracranial aneurysms. Computational fluid dynamic (CFD) analysis is used to assess intra-aneurysmal hemodynamics. Objectives: This study aimed to investigate the effects of variations in heart rate and internal carotid artery (ICA) flow rate on intra-aneurysmal hemodynamics, in an ICA aneurysm, by using computational fluid dynamics. Patients and Methods: Computed tomography angiography (CTA) was performed in a 55 years old female case, with a saccular ICA aneurysm, to create a patient-specific geometrical anatomic model of the aneurysm. The intra-aneurysmal hemodynamic environments for three states with different flow and heart rates were analyzed using patient-specific image-based CFD modeling. Results: Results showed significant changes for the three simulated states. For a proportion of the states examined, results were counterintuitive. Systolic and time-averaged wall shear stress and pressure on the aneurysm wall showed a proportional evolution with the mainstream flow rate. Conclusion: Results reinforced the pivotal role of vascular geometry, with respect to hemodynamics, together with the importance of performing patient-specific CFD analyses, through which the effect of different blood flow conditions on the aneurysm hemodynamics could be evaluated. PMID:27110332

  7. Time analysis of aneurysm wall shear stress for both Newtonian and Casson flows from image-based CFD models

    NASA Astrophysics Data System (ADS)

    Castro, Marcelo A.; Ahumada Olivares, María. C.; Putman, Christopher M.; Cebral, Juan R.

    2014-03-01

    The optimal management of unruptured aneurysms is controversial, and current decision making is mainly based on aneurysm size and location. Incidentally detected unruptured aneurysms less than 5mm in diameter should be treated conservatively. However, small unruptured aneurysms also bleed. Risk factors based on the hemodynamic forces exerted over the arterial wall have been investigated using image-based computational fluid dynamic (CFD) methodologies during the last decade. Accurate estimation of wall shear stress (WSS) is required to properly study associations between flow features and aneurysm processes. Previous works showed that Newtonian and non-Newtonian (Casson) models produce similar WSS distributions and characterization, with no significant differences. Other authors showed that the WSS distribution computed from time-averaged velocity fields is significantly higher for the Newtonian model where WSS is low. In this work we reconstructed ten patient-specific CFD models from angiography images to investigate the time evolution of WSS at selected locations such as aneurysm blebs (low WSS), and the parent artery close to the aneurysm neck (high WSS). When averaging all cases it is seen that the estimation of the time-averaged WSS, the peak WSS and the minimum WSS value before the systolic peak were all higher when the Casson rheology was considered. However, none of them showed statistically significant differences. At the afferent artery Casson rheology systematically predicted higher WSS values. On the other hand, at the selected blebs either Newtonian or Casson WSS estimations are higher in some phases of the cardiac cycle. Those observations differ among individual cases.

  8. A Novel Thin Film Nitinol Covered Neurovascular Stent Significantly Decreases Intra-Aneurysmal Flow In Vitro

    NASA Astrophysics Data System (ADS)

    Chun, Youngjae; Hur, Soojung; Shayan, Mahdis; Kealey, Colin; Levi, Daniel; Mohanchandra, Kp; di Carlo, Dino; Carman, Gregory

    2013-11-01

    A novel thin film nitinol (TFN) stent has been developed to promote aneurysm quiescence by diminishing flow across the aneurysm's neck. Laboratory aneurysm models were used to assess the flow changes produced by stents covered with different patterns of TFN. Flow diversion stents were constructed by covering Wingspan stents (Boston Scientific, DxL:4x20mm) with TFNs (i.e., 77 and 82 percent porosity). The flow changes that occur after deployment of two different porous TFN covered stent in intracranial aneurysm models were evaluated in vitro. The 82 percent porous TFN covered stent reduced the intra-aneurysmal mean flow velocity by 86.42 percent, while a 77 percent porous TFN covered stent reduced to intra-aneurysmal mean flow velocity to 93.44 percent compared to a nonstented model. Local wall shear rates were also significantly reduced in wide-neck aneurysm model (i.e., 97.52 - 98.92 percent) with TFN stent placement. The results showed that TFN covered stents significantly reduced intra-aneurysmal flow velocity magnitudes and local wall shear rates. This suggests that TFN covered stents with both 77 and 82 percent porosity have great potential to promote thrombosis in both wide-necked and fusiform aneurysm sacs.

  9. Intra-aneurysmal flow reductions in a thin film nitinol flow diverter

    NASA Astrophysics Data System (ADS)

    Chun, Youngjae; Hur, Soojung Claire; Kealey, Colin P.; Levi, Daniel S.; Mohanchandra, K. P.; Di Carlo, Dino; Eldredge, Jeff D.; Vinuela, Fernando; Carman, Gregory P.

    2011-05-01

    A novel hyper-elastic thin film nitinol (HE-TFN) covered stent has been developed to promote aneurysm occlusion by diminishing flow in the aneurysm. Laboratory aneurysm models were used to assess the flow changes produced by stents covered with different patterns of HE-TFN placed across the aneurysm neck in the parent vessel. The flow diverters were constructed by covering Wingspan stents (Boston Scientific) with different HE-TFNs (i.e., of 82% and 77% porosity) and deployed in both in vitro wide-neck and fusiform glass aneurysm models. In wide-neck aneurysms, the 82% porous HE-TFN stent reduced mean flow velocity in the middle of the sac by 86 ± 1%, while the 77% porous stent reduced the velocity by 93 ± 5% (n = 3). Local wall shear rates were also significantly reduced by about 98% in this model after device placement. Tests conducted on the fusiform aneurysm revealed smaller intra-aneurysmal flow velocity reduction by 48 ± 3% for the 82% porous stent and by 59 ± 7% for the 77% porous stent. The wall shear was reduced by approximately 50% by HE-TFN stents in fusiform models. These results suggest that HE-TFN covered stents have the potential to promote thrombosis in both wide-neck and fusiform aneurysm sacs.

  10. A Systematic Review of Protocols for the Three-Dimensional Morphologic Assessment of Abdominal Aortic Aneurysms Using Computed Tomographic Angiography

    SciTech Connect

    Ghatwary, Tamer M. H.; Patterson, Benjamin O.; Karthikesalingam, Alan; Hinchliffe, Robert J.; Loftus, Ian M.; Morgan, Robert; Thompson, Matt M.; Holt, Peter J. E.

    2013-02-15

    The morphology of infrarenal abdominal aortic aneurysms (AAAs) directly influences the perioperative outcome and long-term durability of endovascular aneurysm repair. A variety of methods have been proposed for the characterization of AAA morphology using reconstructed three-dimensional (3D) computed tomography (CT) images. At present, there is lack of consensus as to which of these methods is most applicable to clinical practice or research. The purpose of this review was to evaluate existing protocols that used 3D CT images in the assessment of various aspects of AAA morphology. An electronic search was performed, from January 1996 to the end of October 2010, using the Embase and Medline databases. The literature review conformed to PRISMA statement standards. The literature search identified 604 articles, of which 31 studies met inclusion criteria. Only 15 of 31 studies objectively assessed reproducibility. Existing published protocols were insufficient to define a single evidence-based methodology for preoperative assessment of AAA morphology. Further development and expert consensus are required to establish a standardized and validated protocol to determine precisely how morphology relates to outcomes after endovascular aneurysm repair.

  11. Brain Aneurysm

    MedlinePlus

    A brain aneurysm is an abnormal bulge or "ballooning" in the wall of an artery in the brain. They are sometimes called berry aneurysms because they ... often the size of a small berry. Most brain aneurysms produce no symptoms until they become large, ...

  12. Differential Sex Response to Aspirin in Decreasing Aneurysm Rupture in Humans and Mice.

    PubMed

    Chalouhi, Nohra; Starke, Robert M; Correa, Tatiana; Jabbour, Pascal M; Zanaty, Mario; Brown, Robert D; Torner, James C; Hasan, David M

    2016-08-01

    We previously found that aspirin decreases the risk of cerebral aneurysm rupture in humans. We aim to assess whether a sex differential exists in the response of human cerebral aneurysms to aspirin and confirm these observations in a mouse model of cerebral aneurysm. A nested case-control analysis from the International Study of Unruptured Intracranial Aneurysms was performed to assess whether a sex differential exists in the response of human cerebral aneurysms to aspirin. A series of experiments were subsequently performed in a mouse model of cerebral aneurysms. Aneurysms were induced with hypertension and elastase injection into mice basal cisterns. We found that aspirin decreased the risk of aneurysm rupture more significantly in men than in women in the International Study of Unruptured Intracranial Aneurysms. In mice, aspirin and cyclooxygenase-2 inhibitor did not affect cerebral aneurysm formation but significantly decreased the incidence of rupture. The incidence of rupture was significantly lower in male versus female mice on aspirin. Gene expression analysis from cerebral arteries showed higher 15-hydroxyprostaglandin dehydrogenase levels in male mice. The rate of cerebral aneurysm rupture was similar in male mice receiving aspirin and 15-hydroxyprostaglandin dehydrogenase inhibitor compared with females receiving aspirin and 15-hydroxyprostaglandin dehydrogenase agonist, signaling a reversal of the sex-differential response to aspirin. Aspirin decreases aneurysm rupture in human and mice, in part through cyclooxygenase-2 pathways. Evidence from animal and human studies suggests a consistent differential effect by sex. 15-Hydroxyprostaglandin dehydrogenase activation in females reduces the incidence of rupture and eliminates the sex-differential response to aspirin. PMID:27296993

  13. Performance Comparison of Ultrasound-Based Methods to Assess Aortic Diameter and Stiffness in Normal and Aneurysmal Mice

    PubMed Central

    Trachet, Bram; Fraga-Silva, Rodrigo A.; Londono, Francisco J.; Swillens, Abigaïl; Stergiopulos, Nikolaos; Segers, Patrick

    2015-01-01

    Objective Several ultrasound-based methods are currently used to assess aortic diameter, circumferential strain and stiffness in mice, but none of them is flawless and a gold standard is lacking. We aimed to assess the validity and sensitivity of these methods in control animals and animals developing dissecting abdominal aortic aneurysm. Methods and Results We first compared systolic and diastolic diameters as well as local circumferential strains obtained in 47 Angiotensin II-infused ApoE -/- mice with three different techniques (BMode, short axis MMode, long axis MMode), at two different abdominal aortic locations (supraceliac and paravisceral), and at three different time points of abdominal aneurysm formation (baseline, 14 days and 28 days). We found that short axis BMode was preferred to assess diameters, but should be avoided for strains. Short axis MMode gave good results for diameters but high standard deviations for strains. Long axis MMode should be avoided for diameters, and was comparable to short axis MMode for strains. We then compared pulse wave velocity measurements using global, ultrasound-based transit time or regional, pressure-based transit time in 10 control and 20 angiotensin II-infused, anti-TGF-Beta injected C57BL/6 mice. Both transit-time methods poorly correlated and were not able to detect a significant difference in PWV between controls and aneurysms. However, a combination of invasive pressure and MMode diameter, based on radio-frequency data, detected a highly significant difference in local aortic stiffness between controls and aneurysms, with low standard deviation. Conclusions In small animal ultrasound the short axis view is preferred over the long axis view to measure aortic diameters, local methods are preferred over transit-time methods to measure aortic stiffness, invasive pressure-diameter data are preferred over non-invasive strains to measure local aortic stiffness, and the use of radiofrequency data improves the accuracy

  14. Aneurysm strength can decrease under calcification.

    PubMed

    Volokh, Konstantin Y; Aboudi, Jacob

    2016-04-01

    Aneurysms are abnormal dilatations of vessels in the vascular system that are prone to rupture. Prediction of the aneurysm rupture is a challenging and unsolved problem. Various factors can lead to the aneurysm rupture and, in the present study, we examine the effect of calcification on the aneurysm strength by using micromechanical modeling. The calcified tissue is considered as a composite material in which hard calcium particles are embedded in a hyperelastic soft matrix. Three experimentally calibrated constitutive models incorporating a failure description are used for the matrix representation. Two constitutive models describe the aneurysmal arterial wall and the third one - the intraluminal thrombus. The stiffness and strength of the calcified tissue are simulated in uniaxial tension under the varying amount of calcification, i.e. the relative volume of the hard inclusion within the periodic unit cell. In addition, the triaxiality of the stress state, which can be a trigger for the cavitation instability, is tracked. Results of the micromechanical simulation show an increase of the stiffness and a possible decrease of the strength of the calcified tissue as compared to the non-calcified one. The obtained results suggest that calcification (i.e. the presence of hard particles) can significantly affect the stiffness and strength of soft tissue. The development of refined experimental techniques that will allow for the accurate quantitative assessment of calcification is desirable. PMID:26717251

  15. Finite element modeling of endovascular coiling and flow diversion enables hemodynamic prediction of complex treatment strategies for intracranial aneurysm.

    PubMed

    Damiano, Robert J; Ma, Ding; Xiang, Jianping; Siddiqui, Adnan H; Snyder, Kenneth V; Meng, Hui

    2015-09-18

    Endovascular interventions using coil embolization and flow diversion are becoming the mainstream treatment for intracranial aneurysms (IAs). To help assess the effect of intervention strategies on aneurysm hemodynamics and treatment outcome, we have developed a finite-element-method (FEM)-based technique for coil deployment along with our HiFiVS technique for flow diverter (FD) deployment in patient-specific IAs. We tested four clinical intervention strategies: coiling (1-8 coils), single FD, FD with adjunctive coils (1-8 coils), and overlapping FDs. By evaluating post-treatment hemodynamics using computational fluid dynamics (CFD), we compared the flow-modification performance of these strategies. Results show that a single FD provides more reduction in inflow rate than low packing density (PD) coiling, but less reduction in average velocity inside the aneurysm. Adjunctive coils add no additional reduction of inflow rate beyond a single FD until coil PD exceeds 11%. This suggests that the main role of FDs is to divert inflow, while that of coils is to create stasis in the aneurysm. Overlapping FDs decreases inflow rate, average velocity, and average wall shear stress (WSS) in the aneurysm sac, but adding a third FD produces minimal additional reduction. In conclusion, our FEM-based techniques for virtual coiling and flow diversion enable recapitulation of complex endovascular intervention strategies and detailed hemodynamics to identify hemodynamic factors that affect treatment outcome. PMID:26169778

  16. Induction of continuous expanding infrarenal aortic aneurysms in a large porcine animal model

    PubMed Central

    Kloster, Brian O.; Lund, Lars; Lindholt, Jes S.

    2015-01-01

    Background A large animal model with a continuous expanding infrarenal aortic aneurysm gives access to a more realistic AAA model with anatomy and physiology similar to humans, and thus allows for new experimental research in the natural history and treatment options of the disease. Methods 10 pigs (group A) underwent infrarenal aortic dissection, balloon dilatation, infusion of elastase into the lumen and placement of a stenosing cuff around the aorta. 10 control pigs (group B) underwent a sham procedure. The subsequent 28 days the AP-diameters of the aneurysms were measured using ultrasound, hereafter the pigs were euthanized for inspection and AAA wall sampling for histological analysis. Results In group A, all pigs developed continuous expanding AAA's with a mean increase in AP-diameter to 16.26 ± 0.93 mm equivalent to a 57% increase. In group B the AP-diameters increased to 11.33 ± 0.13 mm equivalent to 9.3% which was significantly less than in group A (p < 0.001). In group A, a significant negative association between the preoperative weight and the resulting AP-diameters was found. Histology shoved more or less complete resolution of the elastic tissue in the tunica media in group A. The most frequent complication was a neurological deficit in the lower limbs. Conclusion In pigs it's possible to induce continuous expanding AAA's based upon proteolytic degradation and pathological flow, resembling the real life dynamics of human aneurysms. Because the lumbars are preserved, it's also a potential model for further studies of novel endovascular devices and their complications. PMID:25685342

  17. Pioglitazone Identifies a New Target for Aneurysm Treatment: Role of Egr1 in an Experimental Murine Model of Aortic Aneurysm.

    PubMed

    Charolidi, Nicoletta; Pirianov, Grisha; Torsney, Evelyn; Pearce, Stuart; Laing, Ken; Nohturfft, Axel; Cockerill, Gillian W

    2015-01-01

    Peroxisome proliferator-activated receptor x03B3; agonists have been shown to inhibit angiotensin II (AngII)-induced experimental abdominal aortic aneurysms. Macrophage infiltration to the vascular wall is an early event in this pathology, and therefore we explored the effects of the peroxisome proliferator-activated receptor x03B3; agonist pioglitazone on AngII-treated macrophages. Using microarray-based expression profiling of phorbol ester-stimulated THP-1 cells, we found that a number of aneurysm-related gene changes effected by AngII were modulated following the addition of pioglitazone. Among those genes, polycystic kidney disease 1 (PKD1) was significantly up-regulated (multiple testing corrected p < 0.05). The analysis of the PKD1 proximal promoter revealed a putative early growth response 1 (EGR1) binding site, which was confirmed by chromatin immunoprecipitation (ChIP) and quantitative PCR. Further analysis of publicly available ChIP-sequencing data revealed that this putative binding site overlapped with a conserved EGR1 binding peak present in 5 other cell lines. Quantitative real-time PCR showed that EGR1 suppressed PKD1, while AngII significantly up-regulated PKD1, an effect counteracted by pioglitazone. Conversely, in EGR1 short hairpin RNA lentivirally transduced THP-1 cells, reduced EGR1 led to a significant up-regulation of PKD1, especially after treatment with pioglitazone. In vivo, deficiency of Egr1 in the haematopoietic compartment of mice completely abolished the incidence of CaCl2-induced aneurysm formation. PMID:26113112

  18. Hemodynamics model of fluid–solid interaction in internal carotid artery aneurysms

    PubMed Central

    Fu-Yu, Wang; Lei, Liu; Xiao-Jun, Zhang; Hai-Yue, Ju

    2010-01-01

    The objective of this study is to present a relatively simple method to reconstruct cerebral aneurysms as 3D numerical grids. The method accurately duplicates the geometry to provide computer simulations of the blood flow. Initial images were obtained by using CT angiography and 3D digital subtraction angiography in DICOM format. The image was processed by using MIMICS software, and the 3D fluid model (blood flow) and 3D solid model (wall) were generated. The subsequent output was exported to the ANSYS workbench software to generate the volumetric mesh for further hemodynamic study. The fluid model was defined and simulated in CFX software while the solid model was calculated in ANSYS software. The force data calculated firstly in the CFX software were transferred to the ANSYS software, and after receiving the force data, total mesh displacement data were calculated in the ANSYS software. Then, the mesh displacement data were transferred back to the CFX software. The data exchange was processed in workbench software. The results of simulation could be visualized in CFX-post. Two examples of grid reconstruction and blood flow simulation for patients with internal carotid artery aneurysms were presented. The wall shear stress, wall total pressure, and von Mises stress could be visualized. This method seems to be relatively simple and suitable for direct use by neurosurgeons or neuroradiologists, and maybe a practical tool for planning treatment and follow-up of patients after neurosurgical or endovascular interventions with 3D angiography. PMID:20812022

  19. Management of Unruptured Intracranial Aneurysms.

    PubMed

    Nasr, Deena M; Brown, Robert D

    2016-09-01

    Unruptured intracranial aneurysms (UIA) occur in approximately 2-3 % of the population. Most of these lesions are incidentally found, asymptomatic and typically carry a benign course. Although the risk of aneurysmal subarachnoid hemorrhage is low, this complication can result in significant morbidity and mortality, making assessment of this risk the cornerstone of UIA management. This article reviews important factors to consider when managing unruptured intracranial aneurysms including patient demographics, comorbidities, family history, symptom status, and aneurysm characteristics. It also addresses screening, monitoring, medical management and current surgical and endovascular therapies. PMID:27443382

  20. Prognosis Predicting Score for Endovascular Treatment of Aneurysmal Subarachnoid Hemorrhage: A Risk Modeling Study for Individual Elderly Patients.

    PubMed

    Duan, Guoli; Yang, Pengfei; Li, Qiang; Zuo, Qiao; Zhang, Lei; Hong, Bo; Xu, Yi; Zhao, Wenyuan; Liu, Jianmin; Huang, Qinghai

    2016-02-01

    The elderly patients with aneurysmal subarachnoid hemorrhage (aSAH) have a greater risk of poor clinical outcome after endovascular treatment (EVT) than younger patients do. Hence, it is necessary to explore which factors are associated with poor outcome and develop a predictive score specifically for elderly patients with aSAH receiving EVT. The aim of this study was to develop and validate a predictive score for 1-year outcomes in individual elderly patients with aSAH underwent EVT.In this 10-year prospective study, 520 consecutive aSAH elderly (age ≥ 60 years) patients underwent EVT in a single center were included. The risk factors, periprocedural, and 1-year follow-up data of all patients were entered in a specific prospective database. The modified Rankin scale was used for evaluating clinical outcome. To optimize the model's predictive capacity, the original matrix was randomly divided in 2 submatrices (learning and testing). The predictive score was developed using Arabic numerals for all variables based on the variable coefficients (β) of multivariable logistic regression analysis in the learning set and the predictive performance evaluation was assessed in the testing set. The risk classes were constructed using classification criteria based on sensitivity and specificity. The poor outcome rate at 1 year was 26.15%. Six risk factors, including age, hypertension, Hunt-Hess scale, Fisher scale, aneurysm location, and periprocedural complications, were independently associated with poor outcome and assembled the Changhai score. The discriminative power analysis with the area under the receiver operating characteristic curve (AUC) of the Changhai score was statistically significant (0.864, 0.824-0.904, P < 0.001). The sensitivity and specificity of the Changhai score were 82.07% and 78.06%, respectively. Our study indicated that age, hypertension, Hunt-Hess scale, Fisher scale, aneurysm location, and periprocedural complications were independent risk

  1. Stochastic modelling of wall stresses in abdominal aortic aneurysms treated by a gene therapy.

    PubMed

    Mohand-Kaci, Faïza; Ouni, Anissa Eddhahak; Dai, Jianping; Allaire, Eric; Zidi, Mustapha

    2012-01-01

    A stochastic mechanical model using the membrane theory was used to simulate the in vivo mechanical behaviour of abdominal aortic aneurysms (AAAs) in order to compute the wall stresses after stabilisation by gene therapy. For that, both length and diameter of AAAs rats were measured during their expansion. Four groups of animals, control and treated by an endovascular gene therapy during 3 or 28 days were included. The mechanical problem was solved analytically using the geometric parameters and assuming the shape of aneurysms by a 'parabolic-exponential curve'. When compared to controls, stress variations in the wall of AAAs for treated arteries during 28 days decreased, while they were nearly constant at day 3. The measured geometric parameters of AAAs were then investigated using probability density functions (pdf) attributed to every random variable. Different trials were useful to define a reliable confidence region in which the probability to have a realisation is equal to 99%. The results demonstrated that the error in the estimation of the stresses can be greater than 28% when parameters uncertainties are not considered in the modelling. The relevance of the proposed approach for the study of AAA growth may be studied further and extended to other treatments aimed at stabilisation AAAs, using biotherapies and pharmacological approaches. PMID:21264784

  2. Temporary surgical clipping of flow-diverted arteries in an experimental aneurysm model.

    PubMed

    Darsaut, Tim E; Salazkin, Igor; Gentric, Jean-Christophe; Magro, Elsa; Gevry, Guylaine; Bojanowski, Michel W; Raymond, Jean

    2016-08-01

    OBJECTIVE Surgical management of recurrent aneurysms following failed flow diversion may pose difficulties in securing vascular control with temporary clips. The authors tested the efficacy and impact of different types of aneurysm clips on flow-diverted arteries. METHODS Six wide-necked experimental aneurysms were created in canines and treated with Pipeline flow diverters. In 4 aneurysms, occlusion of the artery at the level of the proximal and distal landing zones (n = 2 per aneurysm) was attempted, using temporary, fenestrated, single, and double permanent aneurysm clips. Two aneurysms served as unclipped controls. Serial angiography was performed to investigate the efficacy of clip occlusion, flow diverter deformation, and thrombus formation. After the animals were killed, the flow-diverted aneurysm constructs were opened and photographed to determine neointimal or device damage as a result of clip placement. RESULTS Angiography-confirmed clip occlusion was only possible for 4 of 8 of the tested flow-diverted arterial segments. Clip application attempts led to filling defects consistent with thrombus formation in 2 of 4 flow-diverted constructs, and to minor damage of the flow diverter with neointimal fracture in 1 of 4 cases. CONCLUSIONS Aneurysm clips placed on canine parent arteries bearing a Pipeline flow diverter were unable to reliably stop blood flow. Application of aneurysm clips can cause mild damage to the device and neointima, which might translate into thromboembolic risks. If possible, vascular control should be sought beyond the terminal ends of the implanted device. PMID:26745475

  3. Effect of Turbulence on the Temporal Variation of Hemodynamic Stresses in Aneurysm Model under Resting and Exercise Conditions

    NASA Astrophysics Data System (ADS)

    Khanafer, Khalil

    2005-11-01

    A numerical model is developed to analyze pulsatile turbulent flow in axisymmetric abdominal aortic aneurysm models (AAM) using realistic physiological resting and exercise waveforms. The transport equations are solved using the finite element formulation based on the Galerkin method of weighted residuals. The κ-ɛ model is used in this work to simulate turbulence characteristics of the convective flow by incorporating Boussinesq eddy-viscosity model. A number of interesting features of the flow field resulting from using realistic physiological waveforms are obtained for various pertinent parameters. Such parameters include Reynolds number, size of aneurysm, flexibility of aneurysm's wall, and the propagation of pressure and flow waves through AAM. The effect of non-Newtonian behavior of blood on hemodynamic stresses and compared with Newtonian behavior through AAM is investigated in the present study. The results of the present work illustrate that maximum turbulent shear stress occurs at the distal end of the AAA model. Furthermore, turbulence is found to have a significant effect on the pressure distribution along AAA wall for both physiological waveforms. This work paves the road for researchers in the area of AAA risk rupture to improve their understanding on the mechanics of aneurysm rupture enhanced by increased flow turbulence.

  4. Presentation and management of aneurysms.

    PubMed Central

    Wyatt, A. P.

    1976-01-01

    The aetiology and pathology of aneurysms, their sites of occurrence, and their general management are outlined. Since the abdominal aortic aneurysm is the type most commonly encountered by the surgeon its presentation, assessment, and operative and postoperative management are discussed in detail. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 8 Fig. 9 PMID:1259327

  5. Computational Hemodynamics Framework for the Analysis of Cerebral Aneurysms

    PubMed Central

    Mut, Fernando; Löhner, Rainald; Chien, Aichi; Tateshima, Satoshi; Viñuela, Fernando; Putman, Christopher; Cebral, Juan

    2010-01-01

    Assessing the risk of rupture of intracranial aneurysms is important for clinicians because the natural rupture risk can be exceeded by the small but significant risk carried by current treatments. To this end numerous investigators have used image-based computational fluid dynamics models to extract patient-specific hemodynamics information, but there is no consensus on which variables or hemodynamic characteristics are the most important. This paper describes a computational framework to study and characterize the hemodynamic environment of cerebral aneurysms in order to relate it to clinical events such as growth or rupture. In particular, a number of hemodynamic quantities are proposed to describe the most salient features of these hemodynamic environments. Application to a patient population indicates that ruptured aneurysms tend to have concentrated inflows, concentrated wall shear stress distributions, high maximal wall shear stress and smaller viscous dissipation ratios than unruptured aneurysms. Furthermore, these statistical associations are largely unaffected by the choice of physiologic flow conditions. This confirms the notion that hemodynamic information derived from image-based computational models can be used to assess aneurysm rupture risk, to test hypotheses about the mechanisms responsible for aneurysm formation, progression and rupture, and to answer specific clinical questions. PMID:21643491

  6. Ultrasound Screening for Abdominal Aortic Aneurysm

    PubMed Central

    2006-01-01

    Executive Summary Objective The aim of this review was to assess the effectiveness of ultrasound screening for asymptomatic abdominal aortic aneurysm (AAA). Clinical Need Abdominal aortic aneurysm is a localized abnormal dilatation of the aorta greater than 3 cm. In community surveys, the prevalence of AAA is reported to be between 2% and 5.4%. Abdominal aortic aneurysms are found in 4% to 8% of older men and in 0.5% to 1.5% of women aged 65 years and older. Abdominal aortic aneurysms are largely asymptomatic. If left untreated, the continuing extension and thinning of the vessel wall may eventually result in rupture of the AAA. Often rupture may occur without warning, causing acute pain. Rupture is always life threatening and requires emergency surgical repair of the ruptured aorta. The risk of death from ruptured AAA is 80% to 90%. Over one-half of all deaths attributed to a ruptured aneurysm take place before the patient reaches hospital. In comparison, the rate of death in people undergoing elective surgery is 5% to 7%; however, symptoms of AAA rarely occur before rupture. Given that ultrasound can reliably visualize the aorta in 99% of the population, and its sensitivity and specificity for diagnosing AAA approaches 100%, screening for aneurysms is worth considering as it may reduce the incidence of ruptured aneurysms and hence reduce unnecessary deaths caused by AAA-attributable mortality. Review Strategy The Medical Advisory Secretariat used its standard search strategy to retrieve international health technology assessments and English-language journal articles from selected databases to determine the effectiveness of ultrasound screening for abdominal aortic aneurysms. Case reports, letters, editorials, nonsystematic reviews, non-human studies, and comments were excluded. Questions asked: Is population-based AAA screening effective in improving health outcomes in asymptomatic populations? Is AAA screening acceptable to the population? Does this affect the

  7. Experimental validation of numerical simulations on a cerebral aneurysm phantom model

    PubMed Central

    Seshadhri, Santhosh; Janiga, Gábor; Skalej, Martin; Thévenin, Dominique

    2012-01-01

    The treatment of cerebral aneurysms, found in roughly 5% of the population and associated in case of rupture to a high mortality rate, is a major challenge for neurosurgery and neuroradiology due to the complexity of the intervention and to the resulting, high hazard ratio. Improvements are possible but require a better understanding of the associated, unsteady blood flow patterns in complex 3D geometries. It would be very useful to carry out such studies using suitable numerical models, if it is proven that they reproduce accurately enough the real conditions. This validation step is classically based on comparisons with measured data. Since in vivo measurements are extremely difficult and therefore of limited accuracy, complementary model-based investigations considering realistic configurations are essential. In the present study, simulations based on computational fluid dynamics (CFD) have been compared with in situ, laser-Doppler velocimetry (LDV) measurements in the phantom model of a cerebral aneurysm. The employed 1:1 model is made from transparent silicone. A liquid mixture composed of water, glycerin, xanthan gum and sodium chloride has been specifically adapted for the present investigation. It shows physical flow properties similar to real blood and leads to a refraction index perfectly matched to that of the silicone model, allowing accurate optical measurements of the flow velocity. For both experiments and simulations, complex pulsatile flow waveforms and flow rates were accounted for. This finally allows a direct, quantitative comparison between measurements and simulations. In this manner, the accuracy of the employed computational model can be checked. PMID:24265876

  8. Sensitivity of Quantified Intracranial Aneurysm Geometry to Imaging Modality

    PubMed Central

    Ramachandran, Manasi; Retarekar, Rohini; Harbaugh, Robert E.; Hasan, David; Policeni, Bruno; Rosenwasser, Robert; Ogilvy, Christopher; Raghavan, Madhavan L.

    2013-01-01

    The objective of this study is to assess the sensitivity of intracranial aneurysm geometry to the modality of imaging. Four imaging modalities—3D rotational angiography (3DRA), computed tomography angiography (CTA), contrast enhanced magnetic resonance angiography (CE-MRA), and time-of-flight magnetic resonance angiography (TOF-MRA)—were assessed using data from a flow phantom and human subjects. A silicone flow phantom of the head and neck arteries with a 10 mm ACOM aneurysm was imaged using all four modalities under steady flow conditions. Three human subjects with mid to large sized intracranial aneurysm who had a 3DRA scan and one of CTA, CE-MRA, or TOF-MRA performed within a day were also studied. The aneurysm and contiguous vasculature were segmented for all available scans and geometric measures of their size (5 indices) and shape (6 indices) were estimated and compared. Visually, the size and shape of segmented 3D models of the aneurysms were similar across scan modalities for both the human subjects and the flow phantom. Consequently, the computed indices were consistent across modalities in the key morphometric indices. In conclusion, quantified indices of 3D geometry of the mid to large sized intracranial aneurysms investigated in this small study population are not sensitive to scanning modality. PMID:24151529

  9. Finite Element Modeling of A Novel Self-Expanding Endovascular Stent Method in Treatment of Aortic Aneurysms

    NASA Astrophysics Data System (ADS)

    Arokiaraj, Mark C.; Palacios, Igor F.

    2014-01-01

    A novel large self-expanding endovascular stent was designed with strut thickness of 70 μm × 70 μm width. The method was developed and investigated to identify a novel simpler technique in aortic aneurysm therapy. Stage 1 analysis was performed after deploying it in a virtual aneurysm model of 6 cm wide × 6 cm long fusiform hyper-elastic anisotropic design. At cell width of 9 mm, there was no buckling or migration of the stent at 180 Hg. Radial force of the stents was estimated after parametric variations. In stage 2 analysis, a prototype 300 μm × 150 μm stent with a cell width of 9 mm was chosen, and it was evaluated similarly after embedding in the aortic wall, and also with a tissue overgrowth of 1 mm over the stent. The 300/150 μm stent reduced the peak wall stress by 70% in the aneurysm and 50% reduction in compliance after embedding. Stage 3 analysis was performed to study the efficacy of stents with struts (thickness/width) 70/70, 180/100 and 300/150 μm after embedding and tissue overgrowth. The adjacent wall stresses were very minimal in stents with 180/100 and 70/70 μm struts after embedding. There is potential for a novel stent method in aortic aneurysm therapy.

  10. Aortic Aneurysm Statistics

    MedlinePlus

    ... Blood Pressure Salt Cholesterol Million Hearts® WISEWOMAN Aortic Aneurysm Fact Sheet Recommend on Facebook Tweet Share Compartir ... cause of most deaths from aortic aneurysms. Aortic Aneurysm in the United States Aortic aneurysms were the ...

  11. Abdominal Aortic Aneurysm (AAA)

    MedlinePlus

    ... Resources Professions Site Index A-Z Abdominal Aortic Aneurysm (AAA) Abdominal aortic aneurysm (AAA) occurs when atherosclerosis ... aortic aneurysm treated? What is an abdominal aortic aneurysm? The aorta, the largest artery in the body, ...

  12. What Is an Aneurysm?

    MedlinePlus

    ... from the NHLBI on Twitter. What Is an Aneurysm? An aneurysm (AN-u-rism) is a balloon-like bulge ... the weakened or injured walls can cause an aneurysm. An aneurysm can grow large and rupture (burst) ...

  13. Brain aneurysm repair

    MedlinePlus

    ... aneurysm repair; Dissecting aneurysm repair; Endovascular aneurysm repair - brain; Subarachnoid hemorrhage - aneurysm ... Your scalp, skull, and the coverings of the brain are opened. A metal clip is placed at ...

  14. Thoracic aortic aneurysm

    MedlinePlus

    Aortic aneurysm - thoracic; Syphilitic aneurysm; Aneurysm - thoracic aortic ... The most common cause of a thoracic aortic aneurysm is hardening of the ... with high cholesterol, long-term high blood pressure, or who ...

  15. Can Surgeons Assess CT Suitability for Endovascular Repair (EVAR) in Ruptured Abdominal Aortic Aneurysm? Implications for a Ruptured EVAR Trial

    SciTech Connect

    Rayt, Harjeet Lambert, Kelly; Bown, Matthew; Fishwick, Guy; Morgan, Robert; McCarthy, Mark; London, Nick; Sayers, Robert

    2008-09-15

    The purpose of this study was to determine whether surgeons without formal radiological training are able to assess suitability of patients with ruptured abdominal aortic aneurysms (AAA) for EVAR. The CT scans of 20 patients with AAA were reviewed under timed conditions by six vascular surgeons. Twenty minutes was allocated per scan. They were asked to determine if each aneurysm would be treatable by EVAR in the emergency setting and, if so, to measure for device selection. The results were then compared with those of a vascular radiologist. Six surgeons agreed on the suitability of endovascular repair in 45% of cases (95% CI, 23.1-68.5%; 9/20 scans; {kappa} = 0.41 [p = 0.01]) and concurred with the radiologist in eight of these. Individually, agreement ranged from 13 to 16 of the 20 scans, 65-80% between surgeons. The kappa value for agreement between all the surgeons and the radiologist was 0.47 (p = 0.01, moderate agreement). For the individual surgeons, this ranged from 0.3 to 0.6 (p = 0.01). In conclusion, while overall agreement was moderate between the surgeons and the radiologist, it is clear that if surgeons are to assess patients for ruptured EVAR in the future, focused training of surgical trainees is required.

  16. Abdominal Aortic Aneurysms: Treatments

    MedlinePlus

    ... information Membership Directory (SIR login) Interventional Radiology Abdominal Aortic Aneurysms Interventional Radiologists Treat Abdominal Aneurysms Nonsurgically Interventional radiologists ...

  17. Contrast-Enhanced and Time-of-Flight MR Angiographic Assessment of Endovascular Coiled Intracranial Aneurysms at 1.5 T

    PubMed Central

    Levent, Akin; Yuce, Ihsan; Eren, Suat; Ozyigit, Omer; Kantarci, Mecit

    2014-01-01

    Summary This study evaluated contrast-enhanced magnetic resonance angiography (CE-MRA) and three-dimensional time-of-flight magnetic resonance angiography (3D-TOF-MRA) through comparisons with digital subtraction angiography (DSA) for the follow-up of intracranial aneurysms treated with detachable coils. Sixty-seven patients with 79 aneurysms underwent 3D-TOF-MRA, CE-MRA, and catheter angiography one year after coiling. Two independent observers classified recanalization status on images as neck or body remnant or no recanalization. For 3D-TOF-MRA and CE-MRA, the intermodality agreement, interobserver agreement, and correlation with angiography were assessed. Sixty-seven patients with 79 coiled aneurysms agreed to participate in the study. Three aneurysms could not be detected on 3D-TOF-MRA, so they were excluded from this study. Interobserver agreement was very good for 3D-TOF-MRA and CE-MRA (kappa (κ): 0.87, 0.94, respectively). Correlation of TOF-MRA with angiography was good (κ: 0.76). Correlation of CE-MRA with angiography was excellent (κ: 0.91). The sensitivity and specificity of TOF-MRA were 92% and 98%, respectively. The sensitivity and specificity of CE-MRA were 96% and 98%, respectively. After selective embolization of intracranial aneurysms, CE-MRA is useful and comparable to DSA in the assessment of aneurysmal recanalization. Agreement with the gold standard is stronger with CE-MRA than with 3D-TOF-MRA. PMID:25496678

  18. Aortic aneurysm: construction of a life-size model by rapid prototyping.

    PubMed

    Lermusiaux, P; Leroux, C; Tasse, J C; Castellani, L; Martinez, R

    2001-03-01

    Development of new endovascular techniques for repair of abdominal aortic aneurysm (AAA) requires the use of experimental models. Stereolithography is a rapid prototyping technique used in industry to prototype parts during the design phase. A stereolithography apparatus (STL) employs laser technology to build a digital model layer by layer with photopolymer resin. The purpose of this study was to use this technology to produce a life-size AAA model. Data were acquired by CT scan and stored in DICOM 3 format. Specifically designed software was used for 3-D imaging and conversion of data to a standard STL format. Two replicas were made: one to scale and the other 3 mm larger. The final model was made by pouring silicone rubber or polyurethane into the mold over the life-size model so as to obtain a sturdy, life-size, soft, transparent plastic casting. Arterial models made for living subjects with these rapid prototyping techniques can be used to simulate surgical procedures, calibrate imaging modalities, and design new stent grafts. PMID:11265074

  19. Aneurysms: thoracic aortic aneurysms.

    PubMed

    Chun, Kevin C; Lee, Eugene S

    2015-04-01

    Thoracic aortic aneurysms (TAAs) have many possible etiologies, including congenital heart defects (eg, bicuspid aortic valves, coarctation of the aorta), inherited connective tissue disorders (eg, Marfan, Ehlers-Danlos, Loeys-Dietz syndromes), and degenerative conditions (eg, medial necrosis, atherosclerosis of the aortic wall). Symptoms of rupture include a severe tearing pain in the chest, back, or neck, sometimes associated with cardiovascular collapse. Before rupture, TAAs may exert pressure on other thoracic structures, leading to a variety of symptoms. However, most TAAs are asymptomatic and are found incidentally during imaging for other conditions. Diagnosis is confirmed with computed tomography scan or echocardiography. Asymptomatic TAAs should be monitored with imaging at specified intervals and patients referred for repair if the TAAs are enlarging rapidly (greater than 0.5 cm in diameter over 6 months for heritable etiologies; greater than 0.5 cm over 1 year for degenerative etiologies) or reach a critical aortic diameter threshold for elective surgery (5.5 cm for TAAs due to degenerative etiologies, 5.0 cm when associated with inherited syndromes). Open surgery is used most often to treat asymptomatic TAAs in the ascending aorta and aortic arch. Asymptomatic TAAs in the descending aorta often are treated medically with aggressive blood pressure control, though recent data suggest that endovascular procedures may result in better long-term survival rates. PMID:25860136

  20. Active-shape-model-based segmentation of abdominal aortic aneurysms in CTA images

    NASA Astrophysics Data System (ADS)

    de Bruijne, Marleen; van Ginneken, Bram; Niessen, Wiro J.; Maintz, J. B. Antoine; Viergever, Max A.

    2002-05-01

    An automated method for the segmentation of thrombus in abdominal aortic aneurysms from CTA data is presented. The method is based on Active Shape Model (ASM) fitting in sequential slices, using the contour obtained in one slice as the initialisation in the adjacent slice. The optimal fit is defined by maximum correlation of grey value profiles around the contour in successive slices, in contrast to the original ASM scheme as proposed by Cootes and Taylor, where the correlation with profiles from training data is maximised. An extension to the proposed approach prevents the inclusion of low-intensity tissue and allows the model to refine to nearby edges. The applied shape models contain either one or two image slices, the latter explicitly restricting the shape change from slice to slice. To evaluate the proposed methods a leave-one-out experiment was performed, using six datasets containing 274 slices to segment. Both adapted ASM schemes yield significantly better results than the original scheme (p<0.0001). The extended slice correlation fit of a one-slice model showed best overall performance. Using one manually delineated image slice as a reference, on average a number of 29 slices could be automatically segmented with an accuracy within the bounds of manual inter-observer variability.

  1. A novel hyper-elastic thin film nitinol covered stent significantly decreases intra-aneurysmal flow in vitro

    NASA Astrophysics Data System (ADS)

    Chun, Youngjae; Hur, Soojung C.; Kealey, Colin P.; Levi, Daniel S.; Mohanchandra, K. P.; Di Carlo, Dino; Carman, Gregory P.

    2011-04-01

    A novel hyper-elastic thin film nitinol (HE-TFN) covered stent has been developed to promote aneurysm quiescence by diminishing flow across the aneurysm's neck. Laboratory aneurysm models were used to assess the flow changes produced by stents covered with different patterns of HE-TFN. The flow diverters were constructed by covering Wingspan stents (Boston Scientific) with HE-TFNs (i.e., 82 and 77% porosity) and deployed in both in vitro wide-neck and fusiform glass aneurysm models. In wide-neck aneurysms, the 82% porous HE-TFN stent reduced mean flow velocity in the middle of the sac by 86.42+/-0.5%, while a 77% porous stent reduced the velocity by 93.44+/-4.99% (n=3). Local wall shear rates were also significantly reduced by about 98% in this model after device placement. Tests conducted on the fusiform aneurysm revealed smaller intra-aneurysmal flow velocity reduction to 48.96+/-2.9% for 82% porous and to 59.2+/-6.9% for 77% porous stent, respectively. The wall shear was reduced by approximately 50% by HE-TFN stents in fusiform models. These results suggest that HE-TFN covered stents have potential to promote thrombosis in both wide-necked and fusiform aneurysm sacs.

  2. Angiographic analysis of blood flow modification in cerebral aneurysm models with a new asymmetric stent

    PubMed Central

    Wang, Zhou; Ionita, Ciprian; Rudin, Stephen; Hoffmann, Kenneth R.; Paxton, Adam B.; Bednarek, Daniel R.

    2011-01-01

    We have built new asymmetric stents for minimally invasive endovascular treatment of cerebral aneurysms. Each asymmetric stent consists of a commercial stent with a micro-welded circular mesh patch. The blood flow modification in aneurysm-vessel phantoms due to these stents was evaluated using x-ray angiographic analysis. However, the density difference between the radiographic contrast and the blood gives rise to a gravity effect, which was evaluated using an initial optical dye-dilution experiment. For the radiographic evaluations, curved-vessel phantoms instead of simple straight side-wall aneurysm phantoms were used in the characterization of meshes/stents. Six phantoms (one untreated, one treated with a commercial stent, and four treated with different asymmetric stents) with similar morphologies were used for comparison. We calculated time-density curves of the aneurysm region and then calculated the peak value (Pk) and washout rate (1/τ) after analytical curve fitting. Flow patterns in the angiograms showed reduction of vortex flow and slow washout in the dense mesh patch treated aneurysms. The meshes reduced Pk down to 21% and 1/τ down to 12% of the values for the untreated case. In summary, new asymmetric stents were constructed and their evaluation demonstrates that they may be useful in the endovascular treatment of aneurysms. PMID:21886414

  3. Lattice Boltzmann Model of 3D Multiphase Flow in Artery Bifurcation Aneurysm Problem

    PubMed Central

    Abas, Aizat; Mokhtar, N. Hafizah; Ishak, M. H. H.; Abdullah, M. Z.; Ho Tian, Ang

    2016-01-01

    This paper simulates and predicts the laminar flow inside the 3D aneurysm geometry, since the hemodynamic situation in the blood vessels is difficult to determine and visualize using standard imaging techniques, for example, magnetic resonance imaging (MRI). Three different types of Lattice Boltzmann (LB) models are computed, namely, single relaxation time (SRT), multiple relaxation time (MRT), and regularized BGK models. The results obtained using these different versions of the LB-based code will then be validated with ANSYS FLUENT, a commercially available finite volume- (FV-) based CFD solver. The simulated flow profiles that include velocity, pressure, and wall shear stress (WSS) are then compared between the two solvers. The predicted outcomes show that all the LB models are comparable and in good agreement with the FVM solver for complex blood flow simulation. The findings also show minor differences in their WSS profiles. The performance of the parallel implementation for each solver is also included and discussed in this paper. In terms of parallelization, it was shown that LBM-based code performed better in terms of the computation time required. PMID:27239221

  4. Lattice Boltzmann Model of 3D Multiphase Flow in Artery Bifurcation Aneurysm Problem.

    PubMed

    Abas, Aizat; Mokhtar, N Hafizah; Ishak, M H H; Abdullah, M Z; Ho Tian, Ang

    2016-01-01

    This paper simulates and predicts the laminar flow inside the 3D aneurysm geometry, since the hemodynamic situation in the blood vessels is difficult to determine and visualize using standard imaging techniques, for example, magnetic resonance imaging (MRI). Three different types of Lattice Boltzmann (LB) models are computed, namely, single relaxation time (SRT), multiple relaxation time (MRT), and regularized BGK models. The results obtained using these different versions of the LB-based code will then be validated with ANSYS FLUENT, a commercially available finite volume- (FV-) based CFD solver. The simulated flow profiles that include velocity, pressure, and wall shear stress (WSS) are then compared between the two solvers. The predicted outcomes show that all the LB models are comparable and in good agreement with the FVM solver for complex blood flow simulation. The findings also show minor differences in their WSS profiles. The performance of the parallel implementation for each solver is also included and discussed in this paper. In terms of parallelization, it was shown that LBM-based code performed better in terms of the computation time required. PMID:27239221

  5. A framework for the automatic generation of surface topologies for abdominal aortic aneurysm models.

    PubMed

    Shum, Judy; Xu, Amber; Chatnuntawech, Itthi; Finol, Ender A

    2011-01-01

    Patient-specific abdominal aortic aneurysms (AAAs) are characterized by local curvature changes, which we assess using a feature-based approach on topologies representative of the AAA outer wall surface. The application of image segmentation methods yields 3D reconstructed surface polygons that contain low-quality elements, unrealistic sharp corners, and surface irregularities. To optimize the quality of the surface topology, an iterative algorithm was developed to perform interpolation of the AAA geometry, topology refinement, and smoothing. Triangular surface topologies are generated based on a Delaunay triangulation algorithm, which is adapted for AAA segmented masks. The boundary of the AAA wall is represented using a signed distance function prior to triangulation. The irregularities on the surface are minimized by an interpolation scheme and the initial coarse triangulation is refined by forcing nodes into equilibrium positions. A surface smoothing algorithm based on a low-pass filter is applied to remove sharp corners. The optimal number of iterations needed for polygon refinement and smoothing is determined by imposing a minimum average element quality index with no significant AAA sac volume change. This framework automatically generates high-quality triangular surface topologies that can be used to characterize local curvature changes of the AAA wall. PMID:20853025

  6. [The role of intraoperative flowmetry in surgery of cerebral aneurysms].

    PubMed

    Shekhtman, O D; Éliava, Sh Sh; Shakhnovich, V A; Pilipenko, Iu V

    2011-01-01

    Aim of the study was to assess the capabilities of intraoperative ultrasonic flowmetry in cerebral aneurysm surgery for prevention and immediate correction of cerebral ischemia. Ultrasonic flowmeter (Model HT313/323, "ransonic Systems Inc.", USA) was used during surgery in patients with complicated, large and giant aneurysms for evaluation of cerebral blood flow in main arteries (internal carotid, anterior and middle cerebral) and their branches (branches of M2-M3 and A2 segments). The series included 20 adult patients (13 male and 7 female) operated in Burdenko Moscow Neurosurgery Institute during 2008-2011 years. Mean age was 47.4 +/- 8.6 years. Giant aneurysms (> 2.5 cm) were present in 12 (60%) patients, large (1.5-2.5 cm)--in 5 (25%). Aneurysms of internal carotid artery were found in 8 cases. 1 female patient was operated on giant aneurysm of anterior cerebral--anterior communicating artery. In 4 (20%) cases significant alterations of blood flow were registered after clipping (> 25% according to initial), the changes were not visible. This allowed to correct the position of clips. In 2 surgeries ('low' paraclinoid aneurysms) the collateral flow was sufficient during temporary clipping, this allowed trapping of aneurysms with good neurological outcome. In 3 cases flowmeter was used to evaluate blood flow after extracranial-intracranial bypass. Ultrasonic flowmetry is a simple, reproducible and safe technique for intraoperative assessment of blood flow. Despite visual sufficiency of arteries flowmetry allows detection of surgically significant alterations of blood flow after clipping. PMID:22066255

  7. CFD Modelling of Abdominal Aortic Aneurysm on Hemodynamic Loads Using a Realistic Geometry with CT

    PubMed Central

    Ng, E. Y. K.; Loong, T. H.; Bordone, Maurizio; Pua, Uei; Narayanan, Sriram

    2013-01-01

    The objective of this study is to find a correlation between the abdominal aortic aneurysm (AAA) geometric parameters, wall stress shear (WSS), abdominal flow patterns, intraluminal thrombus (ILT), and AAA arterial wall rupture using computational fluid dynamics (CFD). Real AAA 3D models were created by three-dimensional (3D) reconstruction of in vivo acquired computed tomography (CT) images from 5 patients. Based on 3D AAA models, high quality volume meshes were created using an optimal tetrahedral aspect ratio for the whole domain. In order to quantify the WSS and the recirculation inside the AAA, a 3D CFD using finite elements analysis was used. The CFD computation was performed assuming that the arterial wall is rigid and the blood is considered a homogeneous Newtonian fluid with a density of 1050 kg/m3 and a kinematic viscosity of 4 × 10−3 Pa·s. Parallelization procedures were used in order to increase the performance of the CFD calculations. A relation between AAA geometric parameters (asymmetry index (β), saccular index (γ), deformation diameter ratio (χ), and tortuosity index (ε)) and hemodynamic loads was observed, and it could be used as a potential predictor of AAA arterial wall rupture and potential ILT formation. PMID:23864906

  8. Medical treatment of small abdominal aortic aneurysm.

    PubMed

    Assar, A N

    2012-08-01

    Conventional open repair or endovascular aneurysm repair is indicated for infrarenal abdominal aortic aneurysm (AAA) when the diameter of the latter is ≥ 5.5 cm. This therapeutic strategy is based on results of randomized trials of open repair versus ultrasound surveillance of small AAA (<5.5 cm). Studies of screening for AAA have shown that >90% of aneurysms detected are small aneurysms (<5.5 cm). Despite the low annual risk of rupture of these aneurysms, patients with small AAA are left with a potentially life-threatening disease for which no immediate treatment is available. Hence, medical treatment directed at limiting the expansion of small AAA has emerged as an alternative therapeutic strategy. Randomized trials of doxycycline, roxithromycin, and propranolol in patients with small AAA have been published. The results of the doxycycline and roxithromycin trials suggest that both medications can limit AAA expansion, especially during the first year of treatment. Propranolol did not limit AAA expansion, and the trials were stopped because of its serious side effects. In other studies, statins and indomethacin have also been shown to limit AAA expansion. However, these studies were observational with relatively small numbers of patients. Thus, large randomized controlled trials with long follow-up are needed to objectively assess the efficacy of medications that have shown potential in limiting AAA expansion. In addition, recent evidence of regression of AAA in experimental animal models is likely to change our concepts of the molecular pathogenesis of AAA, and could make medical treatment of small AAA a possibility. PMID:22854530

  9. False-negative indocyanine green videoangiography among complex unruptured middle cerebral artery aneurysms: the importance of further aneurysm inspection.

    PubMed

    Kulwin, Charles; Cohen-Gadol, Aaron A

    2014-10-01

    Successful surgical treatment of cerebral aneurysms requires complete occlusion of the aneurysm lumen while maintaining patency of the adjacent branching and perforating arteries. Intraoperative flow assessment allows aneurysm clip repositioning in the event these requirements are not met, avoiding the risk of postoperative rehemorrhage or infarction. A number of modalities have been proposed for primarily intraoperative qualitative blood flow assessment, including microdoppler ultrasonography, intraoperative digital subtraction angiography (DSA), and more recently noninvasive fluorescent angiography including indocyanine green (ICG) fluorescent imaging. Puncture of the aneurysm dome to exclude aneurysm sac filling may also assess the efficacy of clip placement. Although a high concordance between ICG and DSA has been reported, there remains an important subset of aneurysms for which negative ICG study may erroneously suggest aneurysm occlusion. A high-risk situation for such a false-negative study is an atherosclerotic middle cerebral artery (MCA) aneurysm in which vessel wall plaque interferes with the ICG signal. Furthermore, a decreased flow within the aneurysm may not allow enough emission light for detection under the current technology. In this report, we describe our experience with cases of MCA aneurysms with false-negative ICG-VA studies requiring clip adjustment for optimal surgical treatment and discuss two illustrative cases of MCA aneurysms with intraoperative fluorescence studies that were falsely negative, requiring puncture of the aneurysm to correctly identify incomplete aneurysm occlusion. PMID:24552255

  10. Image-based investigation of hemodynamics and rupture of cerebral aneurysms of a single morphological type: terminal aneurysms

    NASA Astrophysics Data System (ADS)

    Castro, Marcelo; Putman, Christopher; Radaelli, Alessandro; Frangi, Alejandro; Cebral, Juan

    2008-03-01

    In this study, the relationship between hemodynamics patterns and aneurysmal rupture was investigated in cerebral aneurysms of a single morphological type (terminal aneurysms) regardless of their location. Hemodynamics information (intra-aneurysmal velocity and pressure fields and wall shear stress distributions) was derived from image-based computational fluid dynamics models with realistic patient specific anatomies. A total of 41 patient-specific models constructed from 3D rotational angiography images were analyzed. The results suggest that high wall shear stress may be associated with aneurysm rupture and that in turn different flow splitting patterns from the parent artery to the daughter branches and the aneurysm produce different levels of wall shear stress.

  11. ATP transport in saccular cerebral aneurysms at arterial bends.

    PubMed

    Imai, Yohsuke; Sato, Kodai; Ishikawa, Takuji; Comerford, Andrew; David, Tim; Yamaguchi, Takami

    2010-03-01

    ATP acts as an extracellular signaling molecule in purinergic signaling that regulates vascular tone. ATP binds purinergic P2 nucleotide receptors on endothelial cells. Understanding the mass transport of ATP to endothelial cells by blood flow is thus important to predict functional changes in aneurysmal walls. While some clinical observations indicate a difference of wall pathology between ruptured and unruptured aneurysms, no study has focused on the mass transport in aneurysms. We investigated the characteristics of ATP concentration at aneurysmal wall using a numerical model of ATP transport in aneurysms formed at arterial bends. The magnitude of ATP concentration at the aneurysmal wall was significantly smaller than that at the arterial wall. In particular, significantly low concentration was predicted at the proximal side of the aneurysmal sac. A strong correlation was revealed between the inflow flux at the aneurysmal neck and the resultant concentration at the aneurysmal wall. PMID:20012692

  12. Prediction of two month modified Rankin Scale with an ordinal prediction model in patients with aneurysmal subarachnoid haemorrhage

    PubMed Central

    2010-01-01

    Background Aneurysmal subarachnoid haemorrhage (aSAH) is a devastating event with a frequently disabling outcome. Our aim was to develop a prognostic model to predict an ordinal clinical outcome at two months in patients with aSAH. Methods We studied patients enrolled in the International Subarachnoid Aneurysm Trial (ISAT), a randomized multicentre trial to compare coiling and clipping in aSAH patients. Several models were explored to estimate a patient's outcome according to the modified Rankin Scale (mRS) at two months after aSAH. Our final model was validated internally with bootstrapping techniques. Results The study population comprised of 2,128 patients of whom 159 patients died within 2 months (8%). Multivariable proportional odds analysis identified World Federation of Neurosurgical Societies (WFNS) grade as the most important predictor, followed by age, sex, lumen size of the aneurysm, Fisher grade, vasospasm on angiography, and treatment modality. The model discriminated moderately between those with poor and good mRS scores (c statistic = 0.65), with minor optimism according to bootstrap re-sampling (optimism corrected c statistic = 0.64). Conclusion We presented a calibrated and internally validated ordinal prognostic model to predict two month mRS in aSAH patients who survived the early stage up till a treatment decision. Although generalizability of the model is limited due to the selected population in which it was developed, this model could eventually be used to support clinical decision making after external validation. Trial Registration International Standard Randomised Controlled Trial, Number ISRCTN49866681 PMID:20920243

  13. Improving the Efficiency of Abdominal Aortic Aneurysm Wall Stress Computations

    PubMed Central

    Zelaya, Jaime E.; Goenezen, Sevan; Dargon, Phong T.; Azarbal, Amir-Farzin; Rugonyi, Sandra

    2014-01-01

    An abdominal aortic aneurysm is a pathological dilation of the abdominal aorta, which carries a high mortality rate if ruptured. The most commonly used surrogate marker of rupture risk is the maximal transverse diameter of the aneurysm. More recent studies suggest that wall stress from models of patient-specific aneurysm geometries extracted, for instance, from computed tomography images may be a more accurate predictor of rupture risk and an important factor in AAA size progression. However, quantification of wall stress is typically computationally intensive and time-consuming, mainly due to the nonlinear mechanical behavior of the abdominal aortic aneurysm walls. These difficulties have limited the potential of computational models in clinical practice. To facilitate computation of wall stresses, we propose to use a linear approach that ensures equilibrium of wall stresses in the aneurysms. This proposed linear model approach is easy to implement and eliminates the burden of nonlinear computations. To assess the accuracy of our proposed approach to compute wall stresses, results from idealized and patient-specific model simulations were compared to those obtained using conventional approaches and to those of a hypothetical, reference abdominal aortic aneurysm model. For the reference model, wall mechanical properties and the initial unloaded and unstressed configuration were assumed to be known, and the resulting wall stresses were used as reference for comparison. Our proposed linear approach accurately approximates wall stresses for varying model geometries and wall material properties. Our findings suggest that the proposed linear approach could be used as an effective, efficient, easy-to-use clinical tool to estimate patient-specific wall stresses. PMID:25007052

  14. Cerebral Aneurysms Fact Sheet

    MedlinePlus

    ... Awards Enhancing Diversity Find People About NINDS Cerebral Aneurysms Fact Sheet See a list of all NINDS ... I get more information? What is a cerebral aneurysm? A cerebral aneurysm (also known as an intracranial ...

  15. Aortic aneurysm repair - endovascular

    MedlinePlus

    ... Endovascular aneurysm repair - aorta; AAA repair - endovascular; Repair - aortic aneurysm - endovascular ... leaking or bleeding. You may have an abdominal aortic aneurysm that is not causing any symptoms or problems. ...

  16. Aortic aneurysm repair - endovascular

    MedlinePlus

    EVAR; Endovascular aneurysm repair - aorta; AAA repair - endovascular; Repair - aortic aneurysm - endovascular ... leaking or bleeding. You may have an abdominal aortic aneurysm that is not causing any symptoms or problems. ...

  17. Hemodynamic Changes in Treated Cerebral Aneurysms and Correlations with Long-Term Outcomes

    NASA Astrophysics Data System (ADS)

    McGah, Patrick; Barbour, Michael; Levitt, Michael; Kim, Louis; Aliseda, Alberto

    2014-11-01

    The hemodynamic conditions in patients with cerebral aneurysms undergoing treatment, e.g. flow diverting stents or coil embolization, are investigated via computational simulations. Patient-specific 3D models of the vasculature are derived from rotational angiography. Patient-specific flow and pressure boundary conditions are prescribed utilizing intravascular pressure and velocity measurements. Pre-treatment and immediate post-treatment hemodynamics are studied in eight cases so as to ascertain the effect of the treatment on the intra-aneurysmal flow and wall shear stress. We hypothesize that larger reductions in intra-aneurysmal inflow and wall shear stress after treatment are correlated with an increased likelihood of aneurysmal occlusion and treatment success. Results indicate reductions of the intra-aneurysmal inflow and wall shear stress in all cases. Preliminary clinical six-month follow-up data, assessing if the treatment has been successful, shows that the cases with a persistent aneurysm had a smaller reduction in inflow and wall shear stress magnitude in the immediate post-treatment conditions. This suggests that CFD can be used to quantify a treatment's probability of success by computing the change in pre-and-post-treatment hemodynamics in cerebral aneurysms. NIH-NINDS.

  18. Combined Visualization of Wall Thickness and Wall Shear Stress for the Evaluation of Aneurysms.

    PubMed

    Glaßer, Sylvia; Lawonn, Kai; Hoffmann, Thomas; Skalej, Martin; Preim, Bernhard

    2014-12-01

    For an individual rupture risk assessment of aneurysms, the aneurysm's wall morphology and hemodynamics provide valuable information. Hemodynamic information is usually extracted via computational fluid dynamic (CFD) simulation on a previously extracted 3D aneurysm surface mesh or directly measured with 4D phase-contrast magnetic resonance imaging. In contrast, a noninvasive imaging technique that depicts the aneurysm wall in vivo is still not available. Our approach comprises an experiment, where intravascular ultrasound (IVUS) is employed to probe a dissected saccular aneurysm phantom, which we modeled from a porcine kidney artery. Then, we extracted a 3D surface mesh to gain the vessel wall thickness and hemodynamic information from a CFD simulation. Building on this, we developed a framework that depicts the inner and outer aneurysm wall with dedicated information about local thickness via distance ribbons. For both walls, a shading is adapted such that the inner wall as well as its distance to the outer wall is always perceivable. The exploration of the wall is further improved by combining it with hemodynamic information from the CFD simulation. Hence, the visual analysis comprises a brushing and linking concept for individual highlighting of pathologic areas. Also, a surface clustering is integrated to provide an automatic division of different aneurysm parts combined with a risk score depending on wall thickness and hemodynamic information. In general, our approach can be employed for vessel visualization purposes where an inner and outer wall has to be adequately represented. PMID:26356964

  19. Vascular dynamics of a shape memory polymer foam aneurysm treatment technique.

    PubMed

    Ortega, Jason; Maitland, Duncan; Wilson, Tom; Tsai, William; Savaş, Omer; Saloner, David

    2007-11-01

    The vascular dynamics of a shape memory polymer foam aneurysm treatment technique are assessed through the simulated treatment of a generic basilar aneurysm using coupled fluid dynamics and heat transfer calculations. The shape memory polymer foam, which expands to fill the aneurysm when heated, is modeled at three discrete stages of the treatment procedure. To estimate an upper bound for the maximum amount of thermal damage due to foam heating, a steady velocity is specified through the basilar artery, corresponding to a minimum physiological flow velocity over a cardiac cycle. During expansion, the foam alters the flow patterns within the aneurysm by shielding the aneurysm dome from a confined jet that issues from the basilar artery. The time scales for thermal damage to the artery walls and surrounding blood flow are computed from the temperature field. The flow through the post-treatment bifurcation is comprised of two counter-rotating vortex tubes that are located beneath the aneurysm neck and extend downstream into the outlet arteries. Beneath the aneurysm neck, a marked increase in the wall shear stress is observed due to the close proximity of the counter-rotating vortex tubes to the artery wall. PMID:17676399

  20. Is aspect ratio sufficient to classify intra-aneurysmal hemodynamics- a parametric approach

    NASA Astrophysics Data System (ADS)

    Durka, Michael; Robertson, Anne

    2013-11-01

    Intracranial aneurysms are a vascular pathology in which a localized bulge is formed in the arterial wall, most often in a saccular shape. It is believed that the blood flow field within the aneurysm plays a critical role in the degradation of the wall. Aneurysm rupture has a high mortality risk. Since only a small fracture of aneurysms rupture, and common treatments have their own risks, it is desirable to identify a useful means of assessing rupture risk. Therefore, numerous groups have endeavored to identify a correlation between rupture risk and sac geometry or flow dynamics. However, no clinically useful parameters have been identified to date. Prior work has suggested that the aspect ratio (sac height/neck) could be useful for risk stratification due to its influence on the sac hemodynamics. In this work, we make of a previously developed parametric model of the aneurysm geometry to evaluate the influence of aspect ratio (sac height/sac neck) on flow dynamics, using computational fluid dynamics. In particular, we assess the influence of aspect ratio on the number of vortices in the aneurysm sac over a wide range of sac geometries. The conclusions obtained for the parametric model are then assessed in 20 clinical cases.

  1. Endovascular image-guided treatment of in-vivo model aneurysms with asymmetric vascular stents (AVS): evaluation with time-density curve angiographic analysis and histology

    PubMed Central

    Dohatcu, A.; Ionita, C. N.; Paciorek, A.; Bednarek, D. R.; Hoffmann, K. R.; Rudin, S.

    2008-01-01

    In this study, we compare the results obtained from Time-Density Curve (TDC) analysis of angiographic imaging sequences with histological evaluation for a rabbit aneurysm model treated with standard stents and new asymmetric vascular stents (AVS) placed by image-guided endovascular deployment. AVSs are stents having a low-porosity patch region designed to cover the aneurysm neck and occlude blood flow inside. To evaluate the AVSs, rabbits with elastase-induced aneurysm models (n=20) were divided into three groups: the first (n=10) was treated with an AVS, the second (n=5) with a non-patch standard coronary stent, and third was untreated as a control (n=5). We used TDC analysis to measure how much contrast media entered the aneurysm before and after treatment. TDCs track contrast-media-density changes as a function of time over the region of interest in x-ray DSA cine-sequences. After 28 days, the animals were sacrificed and the explanted specimens were histologically evaluated. The first group showed an average reduction of contrast flow into the aneurysm of 95% after treatment with an AVS with fully developed thrombus at 28 days follow-up. The rabbits treated with standard stents showed an increase in TDC residency time after treatment and partial-thrombogenesis. The untreated control aneurysms displayed no reduction in flow and were still patent at follow-up. The quantitative TDC analysis findings were confirmed by histological evaluation suggesting that the new AVS has great potential as a definitive treatment for cerebro-vascular aneurysms and that angiographic TDC analysis can provide in-vivo verification. PMID:18958295

  2. Popliteal aneurysms.

    PubMed

    Farina, C; Cavallaro, A; Schultz, R D; Feldhaus, R J; di Marzo, L

    1989-07-01

    A 15 year experience with 50 popliteal aneurysms in 36 patients is reviewed. Forty-seven popliteal aneurysms were atherosclerotic while three were related to entrapment of the popliteal artery. Fourteen asymptomatic popliteal aneurysms were observed preoperatively during a mean period of 26 months. Ischemic complications developed in five of these. At admission, 16 limbs were asymptomatic (group 1) while the other 34 limbs presented with ischemic symptoms (group 2). No operation was performed upon three limbs, and another two were surgically explored and amputated. No operative deaths resulted from 45 vascular reconstructions. Results from follow-up study of one to 176 months (a mean of 57 months) revealed a late patency rate of 62 per cent. The late patency rate of autologous saphenous vein (ASV) was 100 per cent; polytetrafluoroethylene (PTFE) and Dacron (polyester fiber) grafts had a patency rate of 74 and 34 per cent, respectively (ASV versus PTFE, p = N.S.; ASV versus Dacron, p less than 0.002). The rate of late salvage of limbs was 88 per cent. The bypass grafts of group 1 and those performed upon limbs with good runoff fared significantly better than others (p less than 0.05 and p less than 0.001). The risk of natural complications of popliteal aneurysms and the good results from surgical treatment suggested that a revascularization procedure in the asymptomatic stage is always recommended. The use of PTFE grafts for repair of popliteal aneurysms is justified when the ASV is not available. The use of Dacron grafts is no longer indicated. PMID:2740973

  3. Neuroimaging characteristics of ruptured aneurysm as predictors of outcome after aneurysmal subarachnoid hemorrhage: pooled analyses of the SAHIT cohort.

    PubMed

    Jaja, Blessing N R; Lingsma, Hester; Steyerberg, Ewout W; Schweizer, Tom A; Thorpe, Kevin E; Macdonald, R Loch

    2016-06-01

    OBJECT Neuroimaging characteristics of ruptured aneurysms are important to guide treatment selection, and they have been studied for their value as outcome predictors following aneurysmal subarachnoid hemorrhage (SAH). Despite multiple studies, the prognostic value of aneurysm diameter, location, and extravasated SAH clot on computed tomography scan remains debatable. The authors aimed to more precisely ascertain the relation of these factors to outcome. METHODS The data sets of studies included in the Subarachnoid Hemorrhage International Trialists (SAHIT) repository were analyzed including data on ruptured aneurysm location and diameter (7 studies, n = 9125) and on subarachnoid clot graded on the Fisher scale (8 studies; n = 9452) for the relation to outcome on the Glasgow Outcome Scale (GOS) at 3 months. Prognostic strength was quantified by fitting proportional odds logistic regression models. Univariable odds ratios (ORs) were pooled across studies using random effects models. Multivariable analyses were adjusted for fixed effect of study, age, neurological status on admission, other neuroimaging factors, and treatment modality. The neuroimaging predictors were assessed for their added incremental predictive value measured as partial R(2). RESULTS Spline plots indicated outcomes were worse at extremes of aneurysm size, i.e., less than 4 or greater than 9 mm. In between, aneurysm size had no effect on outcome (OR 1.03, 95% CI 0.98-1.09 for 9 mm vs 4 mm, i.e., 75th vs 25th percentile), except in those who were treated conservatively (OR 1.17, 95% CI 1.02-1.35). Compared with anterior cerebral artery aneurysms, posterior circulation aneurysms tended to result in slightly poorer outcome in patients who underwent endovascular coil embolization (OR 1.13, 95% CI 0.82-1.57) or surgical clipping (OR 1.32, 95% CI 1.10-1.57); the relation was statistically significant only in the latter. Fisher CT subarachnoid clot burden was related to outcome in a gradient manner. Each

  4. Correlation Between Aneurysm Size and Hemodynamics in One Individual with Multiple Small Intracranial Aneurysms

    PubMed Central

    Britz, Gavin

    2016-01-01

    Objective A large number of cases are needed in the patient-specific modeling of intracranial aneurysms to establish the statistical significance due to individual variation of risk factors that are difficult to account for. However, these risk factors are critical in hemorrhage risk as demonstrated in large clinical studies. Rupture risks for aneurysms in an individual are easier to compare because these aneurysms are under the same physiological environment, and their only differences are the local hemodynamic factors associated with their anatomic locations. Methods Eight small aneurysms (< 7 mm) from one individual were analyzed using patient-specific hemodynamic modeling. Four scenarios with different perfusion assumptions were performed to account for the flow rate at two smaller communicating arteries. Wall shear stresses (WSS) at these aneurysms were compared to determine their relationship with the aneurysm size. Results Each of the three largest aneurysms is either the most proximal or distal aneurysm in a given artery so that blood pressure does not have a direct influence on aneurysm size. No wall shear stress-derived hemodynamic variables are found to be related to aneurysm size. Discussion A study of multiple aneurysms from one individual offers a unique opportunity to examine various hemodynamic factors without selection biases. Aneurysms greater than 4 mm (Group 1) have a higher product of maximum WSS and area of low WSS; aneurysms smaller than 4 mm (Group 2) have a lower product of maximum WSS and area of low WSS. In addition, aneurysm size is linearly correlated with the flow rate at the parent artery in each group. PMID:27555981

  5. Correlation Between Aneurysm Size and Hemodynamics in One Individual with Multiple Small Intracranial Aneurysms.

    PubMed

    Jou, Liangder; Britz, Gavin

    2016-01-01

    Objective A large number of cases are needed in the patient-specific modeling of intracranial aneurysms to establish the statistical significance due to individual variation of risk factors that are difficult to account for. However, these risk factors are critical in hemorrhage risk as demonstrated in large clinical studies. Rupture risks for aneurysms in an individual are easier to compare because these aneurysms are under the same physiological environment, and their only differences are the local hemodynamic factors associated with their anatomic locations. Methods Eight small aneurysms (< 7 mm) from one individual were analyzed using patient-specific hemodynamic modeling. Four scenarios with different perfusion assumptions were performed to account for the flow rate at two smaller communicating arteries. Wall shear stresses (WSS) at these aneurysms were compared to determine their relationship with the aneurysm size. Results Each of the three largest aneurysms is either the most proximal or distal aneurysm in a given artery so that blood pressure does not have a direct influence on aneurysm size. No wall shear stress-derived hemodynamic variables are found to be related to aneurysm size. Discussion A study of multiple aneurysms from one individual offers a unique opportunity to examine various hemodynamic factors without selection biases. Aneurysms greater than 4 mm (Group 1) have a higher product of maximum WSS and area of low WSS; aneurysms smaller than 4 mm (Group 2) have a lower product of maximum WSS and area of low WSS. In addition, aneurysm size is linearly correlated with the flow rate at the parent artery in each group. PMID:27555981

  6. Fluid, solid and fluid-structure interaction simulations on patient-based abdominal aortic aneurysm models.

    PubMed

    Kelly, Sinead; O'Rourke, Malachy

    2012-04-01

    This article describes the use of fluid, solid and fluid-structure interaction simulations on three patient-based abdominal aortic aneurysm geometries. All simulations were carried out using OpenFOAM, which uses the finite volume method to solve both fluid and solid equations. Initially a fluid-only simulation was carried out on a single patient-based geometry and results from this simulation were compared with experimental results. There was good qualitative and quantitative agreement between the experimental and numerical results, suggesting that OpenFOAM is capable of predicting the main features of unsteady flow through a complex patient-based abdominal aortic aneurysm geometry. The intraluminal thrombus and arterial wall were then included, and solid stress and fluid-structure interaction simulations were performed on this, and two other patient-based abdominal aortic aneurysm geometries. It was found that the solid stress simulations resulted in an under-estimation of the maximum stress by up to 5.9% when compared with the fluid-structure interaction simulations. In the fluid-structure interaction simulations, flow induced pressure within the aneurysm was found to be up to 4.8% higher than the value of peak systolic pressure imposed in the solid stress simulations, which is likely to be the cause of the variation in the stress results. In comparing the results from the initial fluid-only simulation with results from the fluid-structure interaction simulation on the same patient, it was found that wall shear stress values varied by up to 35% between the two simulation methods. It was concluded that solid stress simulations are adequate to predict the maximum stress in an aneurysm wall, while fluid-structure interaction simulations should be performed if accurate prediction of the fluid wall shear stress is necessary. Therefore, the decision to perform fluid-structure interaction simulations should be based on the particular variables of interest in a given

  7. Construction of 3 animal experimental models in the development of honeycomb microporous covered stents for the treatment of large wide-necked cerebral aneurysms.

    PubMed

    Nakayama, Yasuhide; Satow, Tetsu; Funayama, Marina; Moriwaki, Takeshi; Tajikawa, Tsutomu; Furukoshi, Maya; Hamano, Eika; Ishi, Daizo; Hayashi, Masataka; Sugata, Sei; Ishibashi-Ueda, Hatsue; Takahashi, Jun C

    2016-06-01

    The treatment of large or wide-necked cerebral aneurysms is extremely difficult, and carries a high risk of rupture, even when surgical or endovascular methods are available. We are developing novel honeycomb microporous covered stents for treating such aneurysms. In this study, 3 experimental animal models were designed and evaluated quantitatively before preclinical study. The stents were prepared using specially designed balloon-expandable stents (diameter 3.5-5.0 mm, length 16-28 mm) by dip-coating to completely cover their struts with polyurethane film (thickness 20 µm) and microprocessing to form the honeycomb pattern after expansion. (1) In an internal carotid artery canine model (n = 4), all stents mounted on the delivery catheter passed smoothly through the tortuous vessel with minimal arterial damage. (2) In an the large, wide-necked, outer-sidewall aneurysm canine model, almost all parts of the aneurysms had embolized immediately after stenting (n = 4), and histological examination at 2 months revealed neointimal formation with complete endothelialization at all stented segments and entirely organized aneurysms. (3) In a perforating artery rabbit model, all lumbar arteries remained patent (n = 3), with minimal change in the vascular flow pattern for over 1 year, even after placement of a second, overlapping stent (n = 3). At 2 months after stenting, the luminal surface was covered with complete thin neointimal formation. Excellent embolization performance of the honeycomb microporous covered stents without disturbing branching flow was confirmed at the aneurysms in this proof-of-concept study. PMID:26742535

  8. An Integrated Fluid-Chemical Model Toward Modeling the Formation of Intra-Luminal Thrombus in Abdominal Aortic Aneurysms

    PubMed Central

    Biasetti, Jacopo; Spazzini, Pier Giorgio; Swedenborg, Jesper; Gasser, T. Christian

    2012-01-01

    Abdominal Aortic Aneurysms (AAAs) are frequently characterized by the presence of an Intra-Luminal Thrombus (ILT) known to influence their evolution biochemically and biomechanically. The ILT progression mechanism is still unclear and little is known regarding the impact of the chemical species transported by blood flow on this mechanism. Chemical agonists and antagonists of platelets activation, aggregation, and adhesion and the proteins involved in the coagulation cascade (CC) may play an important role in ILT development. Starting from this assumption, the evolution of chemical species involved in the CC, their relation to coherent vortical structures (VSs) and their possible effect on ILT evolution have been studied. To this end a fluid-chemical model that simulates the CC through a series of convection-diffusion-reaction (CDR) equations has been developed. The model involves plasma-phase and surface-bound enzymes and zymogens, and includes both plasma-phase and membrane-phase reactions. Blood is modeled as a non-Newtonian incompressible fluid. VSs convect thrombin in the domain and lead to the high concentration observed in the distal portion of the AAA. This finding is in line with the clinical observations showing that the thickest ILT is usually seen in the distal AAA region. The proposed model, due to its ability to couple the fluid and chemical domains, provides an integrated mechanochemical picture that potentially could help unveil mechanisms of ILT formation and development. PMID:22934022

  9. MicroRNA-92a Regulates Expression of Kruppel-like Factor2 in Rabbit Model of Intracranial Aneurysm.

    PubMed

    Wu, X; Zhang, J; Huang, Q; Yang, P; Chen, J; Liu, J

    2015-01-01

    To explore role of miRNA-92a in regulation of KLF2 expression in intracranial aneurysm model, real time PCR, IHC, ISH and luciferase activity were used to test relationship of miR-92a and KLF2. The results demonstrated that KLF2 showed a time-dependent increase following development of IA model, but the miR-92a showed a time-dependent decrease, co-expression of miR-92a was found to effectively down-regulate luciferase expression in constructs with 3'UTRs of KLF2, to determine the functions of miR-92a in rabbit ECs, we transfected the pre-miR-92a into rabbit ECs for over-expression, the results showed that the protein level of KLF2 was significantly down-regulated when over-expression of miR-92a. In conclusion, our research demonstrated that miR-92a and KLF2 were negative correlation in intracranial aneurysm model, and miR-92a could directly target KLF2 in endothelial cells through complementary sequence of 3'UTR region. PMID:26718427

  10. Hemodynamic Intervention of Cerebral Aneurysms

    NASA Astrophysics Data System (ADS)

    Meng, Hui

    2005-11-01

    Cerebral aneurysm is a pathological vascular response to hemodynamic stimuli. Endovascular treatment of cerebral aneurysms essentially alters the blood flow to stop them from continued growth and eventual rupture. Compared to surgical clipping, endovascular methods are minimally invasive and hence rapidly gaining popularity. However, they are not always effective with risks of aneurysm regrowth and various complications. We aim at developing a Virtual Intervention (VI) platform that allows: patient-specific flow calculation and risk prediction as well as recommendation of tailored intervention based on quantitative analysis. This is a lofty goal requiring advancement in three areas of research: (1). Advancement of image-based CFD; (2) Understanding the biological/pathological responses of tissue to hemodynamic factors in the context of cerebral aneurysms; and (3) Capability of designing and testing patient-specific endovascular devices. We have established CFD methodologies based on anatomical geometry obtained from 3D angiographic or CT images. To study the effect of hemodynamics on aneurysm development, we have created a canine model of a vascular bifurcation anastomosis to provide the hemodynamic environment similar to those in CA. Vascular remodeling was studied using histology and compared against the flow fields obtained from CFD. It was found that an intimal pad, similar to those frequently seen clinically, developed at the flow impingement site, bordering with an area of `groove' characteristic of an early stage of aneurysm, where the micro environment exhibits an elevated wall shear stresses. To further address the molecular mechanisms of the flow-mediated aneurysm pathology, we are also developing in vitro cell culture systems to complement the in vivo study. Our current effort in endovascular device development focuses on novel stents that alters the aneurysmal flow to promote thrombotic occlusion as well as favorable remodeling. Realization of an

  11. Clipping techniques in cerebral aneurysm surgery.

    PubMed

    Acciarri, Nicola; Toniato, Giovanni; Raabe, Andreas; Lanzino, Giuseppe

    2016-03-01

    The history of cerebral aneurysm surgery owes a great tribute to the tenacity of pioneering neurosurgeons who designed and developed the clips used to close the aneurysms neck. However, until the beginning of the past century, surgery of complex and challenging aneurysms was impossible due to the lack of surgical microscope and commercially available sophisticated clips. The modern era of the spring clips began in the second half of last century. Until then, only malleable metal clips and other non-metallic materials were available for intracranial aneurysms. Indeed, the earliest clips were hazardous and difficult to handle. Several neurosurgeons put their effort in developing new clip models, based on their personal experience in the treatment of cerebral aneurysms. Finally, the introduction of the surgical microscope, together with the availability of more sophisticated clips, has allowed the treatment of complex and challenging aneurysms. However, today none of the new instruments or tools for surgical therapy of aneurysms could be used safely and effectively without keeping in mind the lessons on innovative surgical techniques provided by great neurovascular surgeons. Thanks to their legacy, we can now treat many types of aneurysms that had always been considered inoperable. In this article, we review the basic principles of surgical clipping and illustrate some more advanced techniques to be used for complex aneurysms. PMID:26657306

  12. The interactions between bloodstream and vascular structure on aortic dissecting aneurysmal model: A numerical study

    NASA Astrophysics Data System (ADS)

    Chen, Zeng-Sheng; Fan, Zhan-Ming; Zhang, Xi-Wen

    2013-06-01

    Stent-graft implantation is an important means of clinical treatment for aortic dissecting aneurysm (ADA). However, researches on fluid dynamics effects of stent were rare. Computer simulation was used to investigate the interactions between bloodstream and vascular structure in a stented ADA, which endures the periodic pulse velocity and pressure. We obtained and analyzed the flow velocity distribution, the wall displacement and wall stress in the ADA. By comparing the different results between a non-stented and a stented ADA, we found that the insertion of a vascular graft can make the location of maximum stress and displacement move from the aneurysm lumen wall to the artery wall, accompanied with a greatly decrease in value. These results imply that the placement of a stent-graft of any kind to occlude ADA will result in a decreased chance of rupture.

  13. Patient-specific modelling of abdominal aortic aneurysms: The influence of wall thickness on predicted clinical outcomes.

    PubMed

    Conlisk, Noel; Geers, Arjan J; McBride, Olivia M B; Newby, David E; Hoskins, Peter R

    2016-06-01

    Rupture of abdominal aortic aneurysms (AAAs) is linked to aneurysm morphology. This study investigates the influence of patient-specific (PS) AAA wall thickness on predicted clinical outcomes. Eight patients under surveillance for AAAs were selected from the MA(3)RS clinical trial based on the complete absence of intraluminal thrombus. Two finite element (FE) models per patient were constructed; the first incorporated variable wall thickness from CT (PS_wall), and the second employed a 1.9mm uniform wall (Uni_wall). Mean PS wall thickness across all patients was 1.77±0.42mm. Peak wall stress (PWS) for PS_wall and Uni_wall models was 0.6761±0.3406N/mm(2) and 0.4905±0.0850N/mm(2), respectively. In 4 out of 8 patients the Uni_wall underestimated stress by as much as 55%; in the remaining cases it overestimated stress by up to 40%. Rupture risk more than doubled in 3 out of 8 patients when PS_wall was considered. Wall thickness influenced the location and magnitude of PWS as well as its correlation with curvature. Furthermore, the volume of the AAA under elevated stress increased significantly in AAAs with higher rupture risk indices. This highlights the sensitivity of standard rupture risk markers to the specific wall thickness strategy employed. PMID:27056256

  14. Time evolution and hemodynamics of cerebral aneurysms

    NASA Astrophysics Data System (ADS)

    Sforza, Daniel M.; Putman, Christopher; Tateshima, Satoshi; Viñuela, Fernando; Cebral, Juan

    2011-03-01

    Cerebral aneurysm rupture is a leading cause of hemorrhagic strokes. Because they are being more frequently diagnosed before rupture and the prognosis of subarachnoid hemorrhage is poor, clinicians are often required to judge which aneurysms are prone to progression and rupture. Unfortunately, the processes of aneurysm initiation, growth and rupture are not well understood. Multiple factors associated to these processes have been identified. Our goal is to investigate two of them, arterial hemodynamics (using computational fluid dynamics) and the peri-aneurysmal environment, by studying a group of growing cerebral aneurysms that are followed longitudinally in time. Six patients with unruptured untreated brain aneurysms which exhibited growth during the observation period were selected for the study. Vascular models of each aneurysm at each observation time were constructed from the corresponding computed tomography angiography (CTA) images. Subsequently, models were aligned, and geometrical differences quantified. Blood flow was modeled with the 3D unsteady incompressible Navier-Stokes equation for a Newtonian fluid, and wall shear stress distribution and flow patterns were calculated and visualized. Analysis of the simulations and changes in geometry revealed asymmetric growth patterns and suggests that areas subject to vigorous flows, i.e. relative high wall shear stress and concentrated streamlines patterns; correspond to regions of aneurysm growth. Furthermore, in some cases the geometrical evolution of aneurysms is clearly affected by contacts with bone structures and calcifications in the wall, and as a consequence the hemodynamics is greatly modified. Thus, in these cases the peri-aneurysmal environment must be considered when analyzing aneurysm evolution.

  15. Informed consent for abdominal aortic aneurysm repair: Assessing variations in surgeon opinion through a national survey

    PubMed Central

    Dardik, Alan; Bradley, Elizabeth H.; Gusberg, Richard J.; Fraenkel, Liana

    2009-01-01

    Objective Informed consent discussions for elective abdominal aortic aneurysm (AAA) repair should reflect appropriate risks of the open or endovascular repair (EVAR), but few guidelines exist describing what surgeons should discuss. This study examines expert opinion regarding what constitutes informed consent. Methods Design We conducted an anonymous, web-based, national survey of vascular surgeons. Associations between surgeon characteristics and opinions regarding informed consent were measured using bivariate statistics; multivariable logistic regression was performed to estimate effects adjusted for covariates. Setting Academic and private practice surgeons were surveyed. Subjects United States members of the International Society for Vascular Surgery membership. Main Outcome Measure. Surgeons' self-reported opinions regarding the content of informed consent for AAA repair. Results A total of 199 surgeons completed the survey (response rate 51%). More than 90% of respondents reported that it was essential to discuss mortality risk for both procedures. However, only 60% and 30% of respondents reported that it was essential to discuss the risk of myocardial infarction and stroke, respectively. Opinions varied by procedure regarding the risks of impotence (32% vs 62%; EVAR vs open repair), reintervention (78% vs 17%), and rupture during long-term follow-up (57% vs 17%). Younger and private practice surgeons were more likely to discuss complications compared with older surgeons and those in academic practice. Surgeons who perform predominantly EVAR were more likely to quote higher mortality rates for open repair (odds ration [OR] = 3.1, 95% confidence interval [CI] = 1.4-6.4) and lower reintervention rates for EVAR (OR = 0.3, 95% CI = 0.1-0.7) compared with other surgeons. Conclusions This is the first study of the practice of informed consent for AAA repair. The only risk that the vast majority of surgeons agreed should be included in informed consent for AAA

  16. Influencing factors of immediate angiographic results in intracranial aneurysms patients after endovascular treatment.

    PubMed

    Chen, Jia-Xiang; Lai, Ling-Feng; Zheng, Kuang; Li, Guo-Xiong; He, Xu-Ying; Li, Liang-Ping; Duan, Chuan-Zhi

    2015-09-01

    The purpose of this study was to analyze influencing factors associated with immediate angiographic results in intracranial aneurysms patients after endovascular treatment (EVT), providing theoretical evidence and guidance for clinical treatment of intracranial aneurysms. Totally 529 patients met the inclusive criteria, consisting of 338 males and 191 females. Gender; age; history of hypertension, diabetes, and smoking; intracranial atherosclerosis; rupture status, size and location, features of aneurysmal neck, shapes; vasospasm; treatment modality; and degree of aneurysm occlusion were all carefully and completely recorded. All data were investigated in univariate and multivariate logistic regression model to determine whether they were correlated with the degree of aneurysm occlusion. According to aneurysm size, aneurysms were classified as micro-miniature, miniature, and large aneurysms. There were 451 narrow-neck aneurysms and 78 wide-neck aneurysms. Totally 417 were regular and 112 were irregular. And 125 were un-ruptured aneurysms; 404 were ruptured aneurysms. The modalities of treatment were as follows: embolization with coil (n = 415), stent-assisted coil embolization (n = 89), and balloon-assisted coil embolization (n = 25). Univariate analysis showed that aneurysm size, feature of aneurysm neck, shape, and rupture status might affect the immediate occlusion after EVT. Multivariate logistic regression analysis indicated that ruptured aneurysm, tiny aneurysm, and wide-neck aneurysm were independent influencing factors of complete occlusion of intracranial aneurysm. Aneurysm rupture status, size, feature of aneurysmal neck, and shape might be the independent influencing factors of immediate angiographic results in intracranial aneurysm patients after EVT. Un-ruptured, micro-miniature, narrow-neck, and regular-shaped aneurysms were more probable to be occluded completely. PMID:26100332

  17. How Is an Aneurysm Treated?

    MedlinePlus

    ... NHLBI on Twitter. How Is an Aneurysm Treated? Aortic aneurysms are treated with medicines and surgery. Small aneurysms ... doing your normal daily activities Treatment for an aortic aneurysm is based on its size. Your doctor may ...

  18. In vitro investigation of contrast flow jet timing in patient-specific intracranial aneurysms

    PubMed Central

    Desai, Virendra R.; Britz, Garvin W.

    2016-01-01

    Background The direction and magnitude of intra-aneurysmal flow jet are significant risk factors of subarachnoid hemorrhage, and the change of flow jet during an endovascular procedure has been used for prediction of aneurysm occlusion or whether an additional flow diverter (FD) is warranted. However, evaluation of flow jets is often unreliable due to a large variation of flow jet on the digital subtraction angiograms, and this flow pattern variation may result in incorrect clinical diagnosis Therefore, factors contributing to the variation in flow jet are examined at an in vitro setting, and the findings can help us to understand the nature of flow jet and devise a better plan to quantify the aneurysmal hemodynamics accurately. Methods Intra-aneurysmal flows in three patient-specific aneurysms between 11 and 25 mm were investigated in vitro, and a FD was deployed in each aneurysm model. X-ray imaging of these models were performed at injection rates between 0.2 and 2 mL/s. Pulsatile blood pump and aneurysm model were imaged together to determine the timing of flow jet. Results The contrast bolus arrives at the aneurysm early at high contrast injection rates. The flow patterns with slow injection rates exhibit strong inertia that is associated with the systole flow. Flow jets arrive at the aneurysms at the peak systole when the bolus is injected at 0.2 mL/s. The contrast-to-signal ratio is the highest at the injection rate of 0.5 mL/s. Effect of flow diversion can only be assessed at an injection rate greater than 0.5 mL/s. Conclusions Intra-aneurysmal flow jet is highly dependent on the injection rate of the contrast agent. For the internal carotid artery (ICA) aneurysms, the systolic flows can be visualized at slow injection rates (<0.5 mL/s), while the diastolic flow jets are visible at higher injection rates (>1 mL/s). Dependence of flow jet on the contrast injection rate has serious clinical implications and needs to be considered during diagnostic procedures

  19. The Genetic Basis of Aortic Aneurysm

    PubMed Central

    Lindsay, Mark E.; Dietz, Harry C.

    2014-01-01

    Gene identification in human aortic aneurysm conditions is proceeding at a rapid pace and the integration of pathogenesis-based management strategies in clinical practice is an emerging reality. Human genetic alterations causing aneurysm involve diverse gene products including constituents of the extracellular matrix, cell surface receptors, intracellular signaling molecules, and elements of the contractile cytoskeleton. Animal modeling experiments and human genetic discoveries have extensively implicated the transforming growth factor-β (TGF-β) cytokine-signaling cascade in aneurysm progression, but mechanistic links between many gene products remain obscure. This chapter will integrate human genetic alterations associated with aortic aneurysm with current basic research findings in an attempt to form a reconciling if not unifying model for hereditary aortic aneurysm. PMID:25183854

  20. Patient specific stress and rupture analysis of ascending thoracic aneurysms.

    PubMed

    Trabelsi, Olfa; Davis, Frances M; Rodriguez-Matas, Jose F; Duprey, Ambroise; Avril, Stéphane

    2015-07-16

    An ascending thoracic aortic aneurysm (ATAA) is a serious medical condition which, more often than not, requires surgery. Aneurysm diameter is the primary clinical criterion for determining when surgical intervention is necessary but, biomechanical studies have suggested that the diameter criterion is insufficient. This manuscript presents a method for obtaining the patient specific wall stress distribution of the ATAA and the retrospective rupture risk for each patient. Five human ATAAs and the preoperative dynamic CT scans were obtained during elective surgeries to replace each patient's aneurysm with a synthetic graft. The material properties and rupture stress for each tissue sample were identified using bulge inflation tests. The dynamic CT scans were used to generate patient specific geometries for a finite element (FE) model of each patient's aneurysm. The material properties from the bulge inflation tests were implemented in the FE model and the wall stress distribution at four different pressures was estimated. Three different rupture risk assessments were compared: the maximum diameter, the rupture risk index, and the overpressure index. The peak wall stress values for the patients ranged from 28% to 94% of the ATAA's failure stress. The rupture risk and overpressure indices were both only weakly correlated with diameter (ρ=-0.29, both cases). In the future, we plan to conduct a large experimental and computational study that includes asymptomatic patients under surveillance, patients undergoing elective surgery, and patients who have experienced rupture or dissection to determine if the rupture risk index or maximum diameter can meaningfully differentiate between the groups. PMID:25979384

  1. Layer- and region-specific material characterization of ascending thoracic aortic aneurysms by microstructure-based models.

    PubMed

    Sassani, Sophia G; Tsangaris, Sokrates; Sokolis, Dimitrios P

    2015-11-01

    Material characterization of ascending thoracic aortic aneurysms is indispensable for the determination of stress distributions across wall thickness and the different aneurysm regions that may be responsible for their catastrophic rupture or dissection, but only few studies have addressed this issue hitherto. In this article, we are presenting our findings of implementing microstructure-based formulations for characterizing layer- and region-specific variations in wall properties, which is a reasonable consensus today. Together, we performed image-based analysis to derive collagen-fiber orientation angles that may serve as validation of the preferred candidate for a fiber-reinforced constitutive descriptor. We considered a four-fiber model with dispersions of fiber angles about the main directions, based on our histological observations, demonstrating a wide distribution of fiber orientations spanning circumferential to longitudinal directions, and its successful implementation to our biomechanical data from tensile testing. However, an in-depth parametric analysis showed that a condensed model without longitudinal-fiber family described the data just as well and did not omit essential histological organization of collagen fibers, while reserving a smaller number of parameters, which makes it advantageous for computational applications. A major aberration from almost all existing models in the literature is the hypothesis made that fibers can support compressive stresses. Such a hypothesis needs further examination but it has the benefits of allowing improved fits to the vanishing transverse stresses under uniaxial test conditions and of properly reflecting the exponential nature of the compressive stress-strain response of aortic tissue, being consistent with observations of collagen being under compression in the unloaded wall. PMID:26476765

  2. Cerebral aneurysms: Formation, progression and developmental chronology

    PubMed Central

    Etminan, Nima; Buchholz, Bruce A.; Dreier, Rita; Bruckner, Peter; Torner, James C.; Steiger, Hans-Jakob; Hänggi, Daniel; Macdonald, R. Loch

    2015-01-01

    The prevalence of unruptured intracranial aneurysms (UAIs) in the general population is up to 3%. Existing epidemiological data suggests that only a small fraction of UIAs progress towards rupture over the lifetime of an individual, but the surrogates for subsequent rupture and the natural history of UIAs are discussed very controversially at present. In case of rupture of an UIA, the case-fatality is up to 50%, which therefore continues to stimulate interest in the pathogenesis of cerebral aneurysm formation and progression. Actual data on the chronological development of cerebral aneurysm has been especially difficult to obtain and, until recently, the existing knowledge in this respect is mainly derived from animal or mathematical models or short-term observational studies. Here, we highlight the current data on cerebral aneurysm formation and progression as well as a novel approach to investigate the developmental chronology of cerebral aneurysms. PMID:24323717

  3. Flow characteristics in a canine aneurysm model: A comparison of 4D accelerated phase-contrast MR measurements and computational fluid dynamics simulations

    PubMed Central

    Jiang, Jingfeng; Johnson, Kevin; Valen-Sendstad, Kristian; Mardal, Kent-Andre; Wieben, Oliver; Strother, Charles

    2011-01-01

    Purpose: Our purpose was to compare quantitatively velocity fields in and around experimental canine aneurysms as measured using an accelerated 4D PC-MR angiography (MRA) method and calculated based on animal-specific CFD simulations. Methods: Two animals with a surgically created bifurcation aneurysm were imaged using an accelerated 4D PC-MRA method. Meshes were created based on the geometries obtained from the PC-MRA and simulations using “subject-specific” pulsatile velocity waveforms and geometries were then solved using a commercial CFD solver. Qualitative visual assessments and quantitative comparisons of the time-resolved velocity fields obtained from the PC-MRA measurements and the CFD simulations were performed using a defined similarity metric combining both angular and magnitude differences of vector fields. Results: PC-MRA and image-based CFD not only yielded visually consistent representations of 3D streamlines in and around both aneurysms, but also showed good agreement with regard to the spatial velocity distributions. The estimated similarity between time-resolved velocity fields from both techniques was reasonably high (mean value >0.60; one being the highest and zero being the lowest). Relative differences in inflow and outflow zones among selected planes were also reasonable (on the order of 10%–20%). The correlation between CFD-calculated and PC-MRA-measured time-averaged wall shear stresses was low (0.22 and 0.31, p < 0.001). Conclusions: In two experimental canine aneurysms, PC-MRA and image-based CFD showed favorable agreement in intra-aneurismal velocity fields. Combining these two complementary techniques likely will further improve the ability to characterize and interpret the complex flow that occurs in human intracranial aneurysms. PMID:22047395

  4. Laparo- and thoracoscopic aortic aneurysm neck optimization and treatment of potential endoleaks type IA and II in a porcine model

    PubMed Central

    Kloster, Brian O.; Lund, Lars; Lindholt, Jes S.

    2015-01-01

    Background Endovascular repair of aortic aneurysms has a higher incidence of late complications, and open conversion (OC) associated with high mortality may be required. As alternatives to OCs, we propose minimal invasive laparo-/thoracoscopic approaches, either to control endoleaks after endovascular repair, or to convert non-endovascular treatable cases due to a hostile neck anatomy by inserting a peri-aortic PTFE collar before endovascular repair. Such interventions may reduce complications and the necessity for OCs in the future. Methods In twelve pigs, were 10 had infra-/juxtrarenal AAAs, externally placed collars/aneuwraps around the proximal AAA neck and just below the left subclavian artery and division of the aortic side branches were carried out laparo-and thoracoscopically. Results For the laparoscopic and thoracoscopic procedures respectively, mean operative time was 143 ± 41 min and 86 ± 51 min and a mean of 2.6 and 2.25 aortic side branches were ligated/divided. For both procedures, the last half in the series were carried out significantly faster (p < 0.05) indicating a learning curve. Blood loss was minimal and no procedure related complications were seen. Conclusion Using these minimal invasive endoscopic approaches, it seems feasible to externally band aneurysm necks and ligate aortic side branches in a pig model. These procedures could potentially be considered as alternatives to OCs in controlling endoleaks and in improving the safety of endovascular interventions. As endoscopic aortic surgery is challenging a learning curve is expected. Practicing the described procedures using this model, can be used as a learning tool prior to similar interventions on humans. PMID:26793311

  5. Cerebral aneurysm (image)

    MedlinePlus

    ... loss of nerve function may indicate that an aneurysm may be causing pressure on adjacent brain tissue. ... changes or other neurological changes can indicate the aneurysm has ruptured and is bleeding into the brain. ...

  6. Abdominal aortic aneurysm

    MedlinePlus

    ... to the abdomen, pelvis, and legs. An abdominal aortic aneurysm occurs when an area of the aorta becomes ... blood pressure Male gender Genetic factors An abdominal aortic aneurysm is most often seen in males over age ...

  7. New method for retrospective study of hemodynamic changes before and after aneurysm formation in patients with ruptured or unruptured aneurysms

    PubMed Central

    2013-01-01

    Background Prospective observation of hemodynamic changes before and after formation of brain aneurysms is often difficult. We used a vessel surface repair method to carry out a retrospective hemodynamic study before and after aneurysm formation in a ruptured aneurysm of the posterior communicating artery (RPcomAA) and an unruptured aneurysm of the posterior communicating artery (URPcomAA). Methods Arterial geometries obtained from three-dimensional digital subtraction angiography of cerebral angiograms were used for flow simulation by employing finite-volume modeling. Hemodynamic parameters such as wall shear stress (WSS), blood-flow velocity, streamlines, pressure, and wall shear stress gradient (WSSG) in the aneurysm sac and at the site of aneurysm formation were analyzed in each model. Results At “aneurysm” status, hemodynamic analyses at the neck, body, and dome of the aneurysm revealed the distal aneurysm neck to be subjected to the highest WSS and blood-flow velocity, whereas the aneurysm dome presented the lowest WSS and blood-flow velocity in both model types. More apparent changes in WSSG at the aneurysm dome with an inflow jet and narrowed impaction zone were revealed only in the RPcomAA. At “pre-aneurysm” status, hemodynamic analyses in both models showed that the region of aneurysm formation was subjected to extremely elevated WSS, WSSG, and blood-flow velocity. Conclusions These data suggest that hemodynamic analyses in patients with ruptured or unruptured aneurysms using the vessel surface repair method are feasible, economical, and simple. Our preliminary results indicated that the arterial wall was subjected to elevated WSS, WSSG and blood-flow velocity before aneurysm generation. However, more complicated flow patterns (often with an inflow jet or narrowed impaction zone) were more likely to be observed in ruptured aneurysm. PMID:24195732

  8. BIOMECHANICS OF ABDOMINAL AORTIC ANEURYSM

    PubMed Central

    Vorp, David A.

    2009-01-01

    Abdominal aortic aneurysm (AAA) is a condition whereby the terminal aorta permanently dilates to dangerous proportions, risking rupture. The biomechanics of AAA has been studied with great interest since aneurysm rupture is a mechanical failure of the degenerated aortic wall and is a significant cause of death in developed countries. In this review article, the importance of considering the biomechanics of AAA is discussed, and then the history and the state-of-the-art of this field is reviewed - including investigations into the biomechanical behavior of AAA tissues, modeling AAA wall stress and factors which influence it, and the potential clinical utility of these estimates in predicting AAA rupture. PMID:17254589

  9. Microcatheter Looping to Facilitate Aneurysm Selection in Coil Embolization of Paraclinoid Aneurysms

    PubMed Central

    Cho, Young Dae; Rhim, Jong Kook; Park, Jeong Jin; Jeon, Jin Sue; Yoo, Roh-Eul; Kim, Jeong Eun; Cho, Won-Sang; Han, Moon Hee

    2015-01-01

    Objective Described herein is a microcatheter looping technique to facilitate aneurysm selection in paraclinoid aneurysms, which remains to be technically challenging due to the inherent complexity of regional anatomy. Materials and Methods This retrospective study was approved by our Institutional Review Board, and informed consent was waived. Microcatheter looping method was employed in 59 patients with paraclinoid aneurysms between January 2012 and December 2013. In the described technique, construction of a microcatheter loop, which is steam-shaped or pre-shaped, based on the direction of aneurysms, is mandatory. The looped tip of microcatheter was advanced into distal internal carotid artery and positioned atop the target aneurysm. By steering the loop (via inner microguidewire) into the dome of aneurysm and easing tension on the microcatheter, the aneurysm was selected. Clinical and morphologic outcomes were assessed with emphasis on technical aspects of the treatment. Results Through this looping technique, a total of 59 paraclinoid aneurysms were successfully treated. After aneurysm selection as described, single microcatheter technique (n = 25) was most commonly used to facilitate coiling, followed by balloon protection (n = 21), stent protection (n = 7), multiple microcatheters (n = 3), and stent/balloon combination (n = 3). Satisfactory aneurysmal occlusion was achieved through coil embolization in 44 lesions (74.6%). During follow-up of 53 patients (mean interval, 10.9 ± 5.9 months), only one instance (1.9%) of major recanalization was observed. There were no complications related to microcatheter looping. Conclusion This microcatheter looping method facilitates safe and effective positioning of microcatheter into domes of paraclinoid aneurysms during coil embolization when other traditional microcatheter selection methods otherwise fail. PMID:26175591

  10. Evaluation of flow with dynamic x-ray imaging for aneurysms

    NASA Astrophysics Data System (ADS)

    Dohatcu, Andreea Cristina

    The main goal of this thesis is to evaluate blood flow inside cerebrovascular aneurysms using dynamic x-ray imaging. X-ray contrast substance (dye) was auto injected in elastomer aneurysm models placed in a flow loop (for in-vitro studies) to trace flow passing through aneurysms. More specifically, an improved Time-Density Curves (TDC) Roentgen-videodensitometric tracking technique, that included looking to designated regions (R) within an aneurysm rather than focusing on the entire aneurysm, was employed to get information about blood flow using cine-angiographic sequences. It is the first time R-TDC technique has been used. In complex real-time interventions on patients, 2D/3D angiographic analysis of contrast media flow is the only reliable and rapid source of information that we have in order to assess the seriousness of the disease, suggest the treatment, and verify the result of the treatment. The present study focused on finding a "correlation metric" to quantitatively describe the flow behavior within the aneurysms and examine the hemodynamic implications of several treatments using flow modulating devices applied to saccular and bifurcation geometries aneurysms. The main idea in treatment of an aneurysm is rapid reduction of the risk of rupture. This is usually done endovascularly now by totally occluding the aneurysm by packing it with mechanical or chemical agents. Our research, however, involves a new method of blocking the neck using various types of asymmetric vascular stents (AVS). We proposed and analyzed, using R-TDCs, the feasibility of a new modified endovascular method of treatment based on alteration of blood flow through the aneurysm by partial occlusion only. In-vitro studies using aneurysm phantoms with patient-specific aneurysm models were performed. Also, for the first time the new methods were used in in-vivo studies as well, on rabbit-model experimental data, in an attempt to correlate thrombogenic response of a living organism to flow

  11. Celiac Artery Aneurysm

    PubMed Central

    McMullan, D. Michael; McBride, Michael; Livesay, James J.; Dougherty, Kathryn G.; Krajcer, Zvonimir

    2006-01-01

    Aneurysm of the celiac artery is an uncommon clinical problem; fewer than 180 cases have been reported in the world medical literature. Most patients are symptomatic at the time of diagnosis. However, occasionally such aneurysms are detected incidentally during diagnostic imaging for other diseases. We present the case of a 72-year-old man who had an asymptomatic celiac artery aneurysm detected by computed tomographic angiography after endoluminal exclusion of an infrarenal aortic aneurysm. The patient underwent successful resection of the aneurysm and revascularization of the aorta–common hepatic and splenic arteries with use of an autologous saphenous vein graft. PMID:16878636

  12. [Idiopathic pulmonary trunk aneurysm].

    PubMed

    Uehara, Mayuko; Kuroda, Yosuke; Ohori, Syunsuke; Mawatari, Toru; Morishita, Kiyofumi

    2010-07-01

    Pulmonary trunk aneurysm is generally associated with congenital cardiac defects, pulmonary hypertension, or infection. Idiopathic pulmonary trunk aneurysm without any associated diseases is a rare lesion and has seldom been reported. Here, we report a case of a 68-year-old woman with idiopathic pulmonary trunk aneurysm. The maximum diameter of the aneurysm was 53 mm while she was 142 cm in height. We successfully performed aneurysmorrhaphy and her postoperative course was uneventful. Aneurysmorrhaphy was an effective technique for idiopathic pulmonary trunk aneurysm without pulmonary hypertention. PMID:20662238

  13. A method for semi-automatic segmentation and evaluation of intracranial aneurysms in bone-subtraction computed tomography angiography (BSCTA) images

    NASA Astrophysics Data System (ADS)

    Krämer, Susanne; Ditt, Hendrik; Biermann, Christina; Lell, Michael; Keller, Jörg

    2009-02-01

    The rupture of an intracranial aneurysm has dramatic consequences for the patient. Hence early detection of unruptured aneurysms is of paramount importance. Bone-subtraction computed tomography angiography (BSCTA) has proven to be a powerful tool for detection of aneurysms in particular those located close to the skull base. Most aneurysms though are chance findings in BSCTA scans performed for other reasons. Therefore it is highly desirable to have techniques operating on standard BSCTA scans available which assist radiologists and surgeons in evaluation of intracranial aneurysms. In this paper we present a semi-automatic method for segmentation and assessment of intracranial aneurysms. The only user-interaction required is placement of a marker into the vascular malformation. Termination ensues automatically as soon as the segmentation reaches the vessels which feed the aneurysm. The algorithm is derived from an adaptive region-growing which employs a growth gradient as criterion for termination. Based on this segmentation values of high clinical and prognostic significance, such as volume, minimum and maximum diameter as well as surface of the aneurysm, are calculated automatically. the segmentation itself as well as the calculated diameters are visualised. Further segmentation of the adjoining vessels provides the means for visualisation of the topographical situation of vascular structures associated to the aneurysm. A stereolithographic mesh (STL) can be derived from the surface of the segmented volume. STL together with parameters like the resiliency of vascular wall tissue provide for an accurate wall model of the aneurysm and its associated vascular structures. Consequently the haemodynamic situation in the aneurysm itself and close to it can be assessed by flow modelling. Significant values of haemodynamics such as pressure onto the vascular wall, wall shear stress or pathlines of the blood flow can be computed. Additionally a dynamic flow model can be

  14. Embolization of Brain Aneurysms and Fistulas

    MedlinePlus

    ... Professions Site Index A-Z Embolization of Brain Aneurysms and Arteriovenous Malformations/Fistulas Embolization of brain aneurysms ... Aneurysms and Fistulas? What is Embolization of Brain Aneurysms and Fistulas? Embolization of brain aneurysms and arteriovenous ...

  15. Management of Splenic Artery Aneurysms and False Aneurysms with Endovascular Treatment in 12 Patients

    SciTech Connect

    Guillon, R.; Garcier, J.M.; Abergel, A.; Mofid, R.; Garcia, V.; Chahid, T.; Ravel, A.; Pezet, D.; Boyer, L.

    2003-06-15

    Purpose: To assess the endovascular treatment of splenic artery aneurysms and false aneurysms. Methods: Twelve patients (mean age 59 years, range 47-75 years) with splenic artery aneurysm (n = 10) or false aneurysm (n = 2) were treated. The lesion was asymptomatic in 11 patients; hemobilia was observed in one patient. The lesion was juxta-ostial in one case, located on the intermediate segment of the splenic artery in four, near the splenic hilus in six,and affected the whole length of the artery in one patient. In 10 cases, the maximum lesion diameter was greater than 2 cm; in one case 30% growth of an aneurysm 18 mm in diameter had occurred in 6 months;in the last case, two distal aneurysms were associated (17 and 18 mm in diameter). In one case, stent-grafting was attempted; one detachable balloon occlusion was performed; the 10 other patients were treated with coils. Results: Endovascular treatment was possible in 11 patients (92%) (one failure: stenting attempt). In four cases among 11, the initial treatment was not successful (residual perfusion of aneurysm); surgical treatment was carried out in one case, and a second embolization in two. Thus in nine cases (75%) endovascular treatment was successful: complete and persistent exclusion of the aneurysm but with spleen perfusion persisting at the end of follow-upon CT scans (mean 13 months). An early and transient elevation of pancreatic enzymes was observed in four cases. Conclusion: Ultrasound and CT have made the diagnosis of splenic artery aneurysm or false aneurysm more frequent. Endovascular treatment, the morbidity of which is low, is effective and spares the spleen.

  16. Aortic aneurysm repair - endovascular- discharge

    MedlinePlus

    ... page: //medlineplus.gov/ency/patientinstructions/000236.htm Aortic aneurysm repair - endovascular - discharge To use the sharing features ... enable JavaScript. AAA repair - endovascular - discharge; Repair - aortic aneurysm - endovascular - discharge; EVAR - discharge; Endovascular aneurysm repair - discharge ...

  17. Aortitis causing rapid growth of a mycotic aortic aneurysm

    PubMed Central

    Williams, Zoheb Berry; Ryden, Lauren E.; Organ, Nicole M.

    2016-01-01

    Mycotic infrarenal aortic aneurysms are rare and often masquerade as other abdominal pathology. We present a case where serial imaging made the diagnosis and provided an insight into the pathophysiology of mycotic aneurysm. A 71-year-old man presents with abdominal pain, rigours and dysuria. Computed tomography reveals an irregular, thickened ectatic abdominal aorta, but cholescintigraphy suggests acalculous cholecystitis. Deterioration prompts repeat radiographical assessment, which demonstrates an increase in the size of the aorta over 10 days. The patient was treated emergently with an open aortic ligation, debridement and extra-anatomical bypass. Infections account for up to 2% of abdominal aortic aneurysms. The rate of growth of mycotic aneurysms is sparsely discussed in the literature and to our knowledge, there are no reports with serial single-modality imaging. The most significant finding was rapid expansion in aneurysm size. While mycotic aneurysm requires urgent treatment, diagnosis can be delayed and difficult. PMID:27009324

  18. Thrombus Volume Change Visualization after Endovascular Abdominal Aortic Aneurysm Repair

    NASA Astrophysics Data System (ADS)

    Maiora, Josu; García, Guillermo; Macía, Iván; Legarreta, Jon Haitz; Boto, Fernando; Paloc, Céline; Graña, Manuel; Abuín, Javier Sanchez

    A surgical technique currently used in the treatment of Abdominal Aortic Aneurysms (AAA) is the Endovascular Aneurysm Repair (EVAR). This minimally invasive procedure involves inserting a prosthesis in the aortic vessel that excludes the aneurysm from the bloodstream. The stent, once in place acts as a false lumen for the blood current to travel down, and not into the surrounding aneurysm sac. This procedure, therefore, immediately takes the pressure off the aneurysm, which thromboses itself after some time. Nevertheless, in a long term perspective, different complications such as prosthesis displacement or bloodstream leaks into or from the aneurysmatic bulge (endoleaks) could appear causing a pressure elevation and, as a result, increasing the danger of rupture. The purpose of this work is to explore the application of image registration techniques to the visual detection of changes in the thrombus in order to assess the evolution of the aneurysm. Prior to registration, both the lumen and the thrombus are segmented

  19. Virtual Treatment of Basilar Aneurysms Using Shape Memory Polymer Foam

    PubMed Central

    Ortega, J.M.; Hartman, J.; Rodriguez, J.N.; Maitland, D.J.

    2013-01-01

    Numerical simulations are performed on patient-specific basilar aneurysms that are treated with shape memory polymer (SMP) foam. In order to assess the post-treatment hemodynamics, two modeling approaches are employed. In the first, the foam geometry is obtained from a micro-CT scan and the pulsatile blood flow within the foam is simulated for both Newtonian and non-Newtonian viscosity models. In the second, the foam is represented as a porous media continuum, which has permeability properties that are determined by computing the pressure gradient through the foam geometry over a range of flow speeds comparable to those of in vivo conditions. Virtual angiography and additional post-processing demonstrate that the SMP foam significantly reduces the blood flow speed within the treated aneurysms, while eliminating the high-frequency velocity fluctuations that are present within the pre-treatment aneurysms. An estimation of the initial locations of thrombus formation throughout the SMP foam is obtained by means of a low fidelity thrombosis model that is based upon the residence time and shear rate of blood. The Newtonian viscosity model and the porous media model capture similar qualitative trends, though both yield a smaller volume of thrombus within the SMP foam. PMID:23329002

  20. Epidermal growth factor receptor inhibitor protects against abdominal aortic aneurysm in a mouse model.

    PubMed

    Obama, Takashi; Tsuji, Toshiyuki; Kobayashi, Tomonori; Fukuda, Yamato; Takayanagi, Takehiko; Taro, Yoshinori; Kawai, Tatsuo; Forrester, Steven J; Elliott, Katherine J; Choi, Eric; Daugherty, Alan; Rizzo, Victor; Eguchi, Satoru

    2015-05-01

    Angiotensin II (Ang II) has been implicated in the development of abdominal aortic aneurysm (AAA). In vascular smooth muscle cells (VSMC), Ang II activates epidermal growth factor receptor (EGFR) mediating growth promotion. We hypothesized that inhibition of EGFR prevents Ang II-dependent AAA. C57BL/6 mice were co-treated with Ang II and β-aminopropionitrile (BAPN) to induce AAA with or without treatment with EGFR inhibitor, erlotinib. Without erlotinib, 64.3% of mice were dead due to aortic rupture. All surviving mice had AAA associated with EGFR activation. Erlotinib-treated mice did not die and developed far fewer AAA. The maximum diameters of abdominal aortas were significantly shorter with erlotinib treatment. In contrast, both erlotinib-treated and non-treated mice developed hypertension. The erlotinib treatment of abdominal aorta was associated with lack of EGFR activation, endoplasmic reticulum (ER) stress, oxidative stress, interleukin-6 induction and matrix deposition. EGFR activation in AAA was also observed in humans. In conclusion, EGFR inhibition appears to protect mice from AAA formation induced by Ang II plus BAPN. The mechanism seems to involve suppression of vascular EGFR and ER stress. PMID:25531554

  1. Hemodynamic Changes Caused by Flow Diverters in Rabbit Aneurysm Models: Comparison of Virtual and Realistic FD Deployments Based on Micro-CT Reconstruction

    PubMed Central

    Fang, Yibin; Yu, Ying; Cheng, Jiyong; Wang, Shengzhang; Wang, Kuizhong; Liu, Jian-Min; Huang, Qinghai

    2013-01-01

    Adjusting hemodynamics via flow diverter (FD) implantation is emerging as a novel method of treating cerebral aneurysms. However, most previous FD-related hemodynamic studies were based on virtual FD deployment, which may produce different hemodynamic outcomes than realistic (in vivo) FD deployment. We compared hemodynamics between virtual FD and realistic FD deployments in rabbit aneurysm models using computational fluid dynamics (CFD) simulations. FDs were implanted for aneurysms in 14 rabbits. Vascular models based on rabbit-specific angiograms were reconstructed for CFD studies. Real FD configurations were reconstructed based on micro-CT scans after sacrifice, while virtual FD configurations were constructed with SolidWorks software. Hemodynamic parameters before and after FD deployment were analyzed. According to the metal coverage (MC) of implanted FDs calculated based on micro-CT reconstruction, 14 rabbits were divided into two groups (A, MC >35%; B, MC <35%). Normalized mean wall shear stress (WSS), relative residence time (RRT), inflow velocity, and inflow volume in Group A were significantly different (P<0.05) from virtual FD deployment, but pressure was not (P>0.05). The normalized mean WSS in Group A after realistic FD implantation was significantly lower than that of Group B. All parameters in Group B exhibited no significant difference between realistic and virtual FDs. This study confirmed MC-correlated differences in hemodynamic parameters between realistic and virtual FD deployment. PMID:23823503

  2. Feasibility and methodology of optical coherence tomography imaging of human intracranial aneurysms: ex vivo pilot study

    NASA Astrophysics Data System (ADS)

    Vuong, Barry; Sun, Cuiru; Khiel, Tim-Rasmus; Gardecki, Joseph A.; Standish, Beau A.; da Costa, Leodante; de Morais, Josaphat; Tearney, Guillermo J.; Yang, Victor X. D.

    2012-02-01

    Rupture of intracranial aneurysm is a common cause of subarachnoid hemorrhage. An aneurysm may undergo microscopic morphological changes or remodeling of the vessel wall prior to rupture, which could potentially be imaged. In this study we present methods of tissue sample preparation of intracranial aneurysms and correlation between optical coherence tomography imaging and routine histology. OCT has a potential future in the assessment of microscopic features of aneurysms, which may correlate to the risk of rupture.

  3. Micromanaging abdominal aortic aneurysms.

    PubMed

    Maegdefessel, Lars; Spin, Joshua M; Adam, Matti; Raaz, Uwe; Toh, Ryuji; Nakagami, Futoshi; Tsao, Philip S

    2013-01-01

    The contribution of abdominal aortic aneurysm (AAA) disease to human morbidity and mortality has increased in the aging, industrialized world. In response, extraordinary efforts have been launched to determine the molecular and pathophysiological characteristics of the diseased aorta. This work aims to develop novel diagnostic and therapeutic strategies to limit AAA expansion and, ultimately, rupture. Contributions from multiple research groups have uncovered a complex transcriptional and post-transcriptional regulatory milieu, which is believed to be essential for maintaining aortic vascular homeostasis. Recently, novel small noncoding RNAs, called microRNAs, have been identified as important transcriptional and post-transcriptional inhibitors of gene expression. MicroRNAs are thought to "fine tune" the translational output of their target messenger RNAs (mRNAs) by promoting mRNA degradation or inhibiting translation. With the discovery that microRNAs act as powerful regulators in the context of a wide variety of diseases, it is only logical that microRNAs be thoroughly explored as potential therapeutic entities. This current review summarizes interesting findings regarding the intriguing roles and benefits of microRNA expression modulation during AAA initiation and propagation. These studies utilize disease-relevant murine models, as well as human tissue from patients undergoing surgical aortic aneurysm repair. Furthermore, we critically examine future therapeutic strategies with regard to their clinical and translational feasibility. PMID:23852016

  4. Cardiac ventricular aneurysm

    PubMed Central

    Harley, Hugh R. S.

    1969-01-01

    A case of successful excision of a ventricular aneurysm due to myocardial infarction is presented. The aetiology, incidence, pathogenesis, pathology, clinical features, and diagnosis of the condition are discussed. An account is given of the haemodynamic upset caused by aneurysms of the ventricle. The prognosis of untreated aneurysms is discussed. Although there is difference of opinion, it is concluded that a ventricular aneurysm adversely affects the prognosis after myocardial infarction. The indications for, and the mortality and results of, resection of ventricular aneurysms are discussed. The conclusion is drawn that persistent cardiac failure and angina can be relieved and the risk of systemic embolism reduced by the excision of expansile ventricular aneurysms of a fibrous nature. It is possible that excision may also reduce the incidence of subsequent acute myocardial infarction. Images PMID:5821618

  5. Utility of Balloon-Assisted Guglielmi Detachable Coiling in the Treatment of Cerebral Aneurysms

    PubMed Central

    Mangiafico, S.; Cellerini, M.; Villa, G.; Nistri, M.; Pandolfo, C.; Ammannati, F.; Mennonna, P.; Giordano, GP.

    2002-01-01

    Summary Balloon-assisted Guglielmi detachable coiling (BAGDC) is a new technical option developed to allow endovascular treatment of wide-necked aneurysms. Aim of the following work is to report a single center experience of BADGC of aneurysms with assessment of its efficacy and safety. BAGDC of wide-necked aneurysms (SNR close to 1) was retrospectively evaluated in 37 patients (28 females, nine males, mean age: 56.6 yrs, range: 27-81 yrs) who underwent the procedure between january 1999 and january 2002 for a total of 45 procedures on 41 aneurysms. Twenty-nine patients presented with SAH from an acutely ruptured aneurysm. In two patients BAGDC failed whereas 35 patients successfully underwent BADGC (39 aneurysms). Twenty-nine patients (31 aneurysms) were available for angiographic follow-up (mean: 10 mo, range: 3-24 mo). At the last angiographic follow-up 29/33 aneurysms (87%) resulted stable and occluded (22 aneurysms with dense and seven with loose packing of the sac and the neck), two aneurysms showed regrowth, one aneurysm showed a neck remnant and another one a sac and neck remnant. Complications directly related to the procedure occurred in five patients (three perforations, one thromboembolism, one femoral AV) with a mortality and morbility rate of 2.7 and 5.4 respectively. BAGDC is a promising adjunct to treatment of wide-necked aneurysms broadening the spectrum of indications for endovascular treament of challenging aneurysms. PMID:20594481

  6. Identification of MMP1 as a novel risk factor for intracranial aneurysms in ADPKD using iPSC models

    PubMed Central

    Ameku, Tomonaga; Taura, Daisuke; Sone, Masakatsu; Numata, Tomohiro; Nakamura, Masahiro; Shiota, Fumihiko; Toyoda, Taro; Matsui, Satoshi; Araoka, Toshikazu; Yasuno, Tetsuhiko; Mae, Shin-Ichi; Kobayashi, Hatasu; Kondo, Naoya; Kitaoka, Fumiyo; Amano, Naoki; Arai, Sayaka; Ichisaka, Tomoko; Matsuura, Norio; Inoue, Sumiko; Yamamoto, Takuya; Takahashi, Kazutoshi; Asaka, Isao; Yamada, Yasuhiro; Ubara, Yoshifumi; Muso, Eri; Fukatsu, Atsushi; Watanabe, Akira; Sato, Yasunori; Nakahata, Tatsutoshi; Mori, Yasuo; Koizumi, Akio; Nakao, Kazuwa; Yamanaka, Shinya; Osafune, Kenji

    2016-01-01

    Cardiovascular complications are the leading cause of death in autosomal dominant polycystic kidney disease (ADPKD), and intracranial aneurysm (ICA) causing subarachnoid hemorrhage is among the most serious complications. The diagnostic and therapeutic strategies for ICAs in ADPKD have not been fully established. We here generated induced pluripotent stem cells (iPSCs) from seven ADPKD patients, including four with ICAs. The vascular cells differentiated from ADPKD-iPSCs showed altered Ca2+ entry and gene expression profiles compared with those of iPSCs from non-ADPKD subjects. We found that the expression level of a metalloenzyme gene, matrix metalloproteinase (MMP) 1, was specifically elevated in iPSC-derived endothelia from ADPKD patients with ICAs. Furthermore, we confirmed the correlation between the serum MMP1 levels and the development of ICAs in 354 ADPKD patients, indicating that high serum MMP1 levels may be a novel risk factor. These results suggest that cellular disease models with ADPKD-specific iPSCs can be used to study the disease mechanisms and to identify novel disease-related molecules or risk factors. PMID:27418197

  7. Identification of MMP1 as a novel risk factor for intracranial aneurysms in ADPKD using iPSC models.

    PubMed

    Ameku, Tomonaga; Taura, Daisuke; Sone, Masakatsu; Numata, Tomohiro; Nakamura, Masahiro; Shiota, Fumihiko; Toyoda, Taro; Matsui, Satoshi; Araoka, Toshikazu; Yasuno, Tetsuhiko; Mae, Shin-Ichi; Kobayashi, Hatasu; Kondo, Naoya; Kitaoka, Fumiyo; Amano, Naoki; Arai, Sayaka; Ichisaka, Tomoko; Matsuura, Norio; Inoue, Sumiko; Yamamoto, Takuya; Takahashi, Kazutoshi; Asaka, Isao; Yamada, Yasuhiro; Ubara, Yoshifumi; Muso, Eri; Fukatsu, Atsushi; Watanabe, Akira; Sato, Yasunori; Nakahata, Tatsutoshi; Mori, Yasuo; Koizumi, Akio; Nakao, Kazuwa; Yamanaka, Shinya; Osafune, Kenji

    2016-01-01

    Cardiovascular complications are the leading cause of death in autosomal dominant polycystic kidney disease (ADPKD), and intracranial aneurysm (ICA) causing subarachnoid hemorrhage is among the most serious complications. The diagnostic and therapeutic strategies for ICAs in ADPKD have not been fully established. We here generated induced pluripotent stem cells (iPSCs) from seven ADPKD patients, including four with ICAs. The vascular cells differentiated from ADPKD-iPSCs showed altered Ca(2+) entry and gene expression profiles compared with those of iPSCs from non-ADPKD subjects. We found that the expression level of a metalloenzyme gene, matrix metalloproteinase (MMP) 1, was specifically elevated in iPSC-derived endothelia from ADPKD patients with ICAs. Furthermore, we confirmed the correlation between the serum MMP1 levels and the development of ICAs in 354 ADPKD patients, indicating that high serum MMP1 levels may be a novel risk factor. These results suggest that cellular disease models with ADPKD-specific iPSCs can be used to study the disease mechanisms and to identify novel disease-related molecules or risk factors. PMID:27418197

  8. Novel Molecular Imaging Approaches to Abdominal Aortic Aneurysm Risk Stratification.

    PubMed

    Toczek, Jakub; Meadows, Judith L; Sadeghi, Mehran M

    2016-01-01

    Selection of patients for abdominal aortic aneurysm repair is currently based on aneurysm size, growth rate, and symptoms. Molecular imaging of biological processes associated with aneurysm growth and rupture, for example, inflammation and matrix remodeling, could improve patient risk stratification and lead to a reduction in abdominal aortic aneurysm morbidity and mortality. (18)F-fluorodeoxyglucose-positron emission tomography and ultrasmall superparamagnetic particles of iron oxide magnetic resonance imaging are 2 novel approaches to abdominal aortic aneurysm imaging evaluated in clinical trials. A variety of other tracers, including those that target inflammatory cells and proteolytic enzymes (eg, integrin αvβ3 and matrix metalloproteinases), have proven effective in preclinical models of abdominal aortic aneurysm and show great potential for clinical translation. PMID:26763279

  9. Design and biocompatibility of endovascular aneurysm filling devices

    PubMed Central

    Rodriguez, Jennifer N.; Hwang, Wonjun; Horn, John; Landsman, Todd L.; Boyle, Anthony; Wierzbicki, Mark A.; Hasan, Sayyeda M.; Follmer, Douglas; Bryant, Jesse; Small, Ward; Maitland, Duncan J.

    2014-01-01

    The rupture of an intracranial aneurysm, which can result in severe mental disabilities or death, affects approximately 30,000 people in the United States annually. The traditional surgical method of treating these arterial malformations involves a full craniotomy procedure, wherein a clip is placed around the aneurysm neck. In recent decades, research and device development have focused on new endovascular treatment methods to occlude the aneurysm void space. These methods, some of which are currently in clinical use, utilize metal, polymeric, or hybrid devices delivered via catheter to the aneurysm site. In this review, we present several such devices, including those that have been approved for clinical use, and some that are currently in development. We present several design requirements for a successful aneurysm filling device and discuss the success or failure of current and past technologies. We also present novel polymeric based aneurysm filling methods that are currently being tested in animal models that could result in superior healing. PMID:25044644

  10. Parosteal aneurysmal bone cyst☆

    PubMed Central

    Meohas, Walter; de Sá Lopes, Ana Cristina; da Silveira Möller, João Victor; Barbosa, Luma Duarte; Oliveira, Marcelo Bragança dos Reis

    2015-01-01

    The incidence of aneurysmal bone cysts is 0.14 cases per 100,000 individuals. Parosteal aneurysmal bone cysts are the least prevalent subtype and represent 7% of all aneurysmal bone cysts. We present the case of a 38-year-old male patient with pain and bulging in his right arm for eight months. He had previously been diagnosed as presenting giant-cell tumor, but his slides were reviewed and his condition was then diagnosed as parosteal aneurysmal bone cyst. The patient was treated with corticosteroid and calcitonin infiltration into the lesion and evolved with clinical and radiological improvement within the first five weeks after the operation. PMID:26535209

  11. Abdominal Aortic Aneurysms

    PubMed Central

    Fortner, George; Johansen, Kaj

    1984-01-01

    Aneurysms are common in our increasingly elderly population, and are a major threat to life and limb. Until the advent of vascular reconstructive techniques, aneurysm patients were subject to an overwhelming risk of death from exsanguination. The first successful repair of an abdominal aortic aneurysm using an interposed arterial homograft was reported by Dubost in 1952. A milestone in the evolution of vascular surgery, this event and subsequent diagnostic, operative and prosthetic graft refinements have permitted patients with an unruptured abdominal aortic aneurysm to enjoy a better prognosis than patients with almost any other form of major systemic illness. Images PMID:6702193

  12. Method to Quantify Flow Reduction in Aneurysmal Cavities of Lateral Wall Aneurysms Produced by Stent Implants Used for Flow Diversion

    PubMed Central

    Fujimura, N.; Ohta, M.; Abdo, G.; Ylmaz, H.; Lovblad, K.-O; Rüfenacht, D.A.

    2006-01-01

    Summary Stent implants placed across the neck of cerebral aneurysms are capable of reducing aneurysmal flow when coils are not used for filling the aneurysms. It is important to evaluate the effects of flow reduction caused by stent implants used for the treatment of cerebral aneurysms. Subtracted vortex centers path line method (SVC method) is one of the image post processing methods employed for quantitative flow measurement. We developed a modified SVC method by employing Cinematic Angiography (25 frames/s) and digital video recording (30 frames/s) with a commercial digital camera. We successfully compared the flow effectiveness using a tubular silicon model with a sidewall aneurysm. The result suggests that our modified SVC method is useful for a comparative examination of the effect of aneurysmal flow reduction caused by stent implants. PMID:20569631

  13. Bronchial Aneurysms Mimicking Aortic Aneurysms: Endovascular Treatment in Two Patients

    SciTech Connect

    Vernhet, Helene; Bousquet, Claudine; Jean, Betty; Lesnik, Alvian; Durand, Gerard; Giron, Jacques; Senac, Jean Paul

    1999-05-15

    Bronchial artery dilatation and aneurysm formation is a potential complication of local inflammation, especially in bronchiectasis. When the bronchial artery has an ectopic origin from the inferior segment of the aortic arch, aneurysms may mimick aortic aneurysms. Despite this particular location, endovascular treatment is possible. We report two such aneurysms that were successfully embolized with steel coils.

  14. Computational analysis of anterior communicating artery aneurysm shear stress before and after aneurysm formation

    NASA Astrophysics Data System (ADS)

    Castro, Marcelo A.; Putman, Christopher M.; Cebral, Juan R.

    2011-12-01

    It is widely accepted that complexity in the flow pattern at the anterior communicating artery (AComA) is associated with the high rate of aneurysm formation at that location observed in large studies. The purpose of this work is to study associations between hemodynamic patterns, and AComA aneurysm initiation by comparing hemodynamics in the aneurysm and the normal model where the aneurysm was computationally removed. Vascular models of both right and left circulation were independently reconstructed from three-dimensional rotational angiography images using deformable models after image registration of both images, and fused using a surface merging algorithm. The geometric models were then used to generate high-quality volumetric finite element grids of tetrahedra with an advancing front technique. For each patient, the second anatomical model was created by digitally removing the aneurysm. It was iteratively achieved by applying a Laplacian smoothing filter and remeshing the surface. Finite element blood flow numerical simulations were performed for both the pathological and normal models under the same personalized pulsatile flow conditions imposed at the inlets of both models. The Navier-Stokes equations were numerically integrated by using a finite-element formulation. It was observed that aneurysms initiated in regions of high and moderate WSS in the counterpart normal models. Adjacent or close to those regions, low WSS portions of the arterial wall were not affected by the disease. These results are in line with previous observations at other vascular locations.

  15. Quantitative Characterization of the Hemodynamic Environment in Ruptured and Unruptured Brain Aneurysms

    PubMed Central

    Cebral, Juan R.; Mut, Fernando; Weir, Jane; Putman, Christopher

    2011-01-01

    Background and purpose Hemodynamics is thought to play an important role in the mechanisms of aneurysm pathogenesis, progression and rupture. The purpose of this study was to define quantitative measures related to qualitative flow characteristics previously analyzed and to investigate their relationship to aneurysm rupture. Methods The hemodynamic environments in 210 cerebral aneurysms were analyzed using image-based CFD under different flow conditions. Quantitative hemodynamic variables were defined and extracted from the simulation results. A statistical analysis of the relationship to the previous history of aneurysm rupture was performed, and the variability with flow conditions was assessed. Results Ruptured aneurysms were more likely to have larger inflow concentrations, larger maximum wall shear stress (WSS), larger shear concentrations and lower viscous dissipation ratios than unruptured aneurysms. Areas under low WSS and measures of abnormally low shear force distributions of ruptured and unruptured aneurysms were not statistically different. Although the values of hemodynamic quantities changed with different flow conditions, the statistical differences or ratios between their mean values over the ruptured and unruptured groups were maintained, for both pulsatile and steady flows. Conclusions Concentrated inflow streams and WSS distributions with elevated levels of maximal WSS and low aneurysmal viscous dissipation are statistically associated with a clinical history of prior aneurysm rupture. In contrast, the area and total viscous shear force applied in the aneurysm region subjected to abnormally low WSS levels are not. This study highlights the potential for image-based CFD for investigating aneurysm evolution mechanisms and for clinical assessment of aneurysm risks. PMID:21127144

  16. Patient-specific computational analysis of the influence of a stent on the unsteady flow in cerebral aneurysms

    NASA Astrophysics Data System (ADS)

    Takizawa, Kenji; Schjodt, Kathleen; Puntel, Anthony; Kostov, Nikolay; Tezduyar, Tayfun E.

    2013-06-01

    We present a patient-specific computational analysis of the influence of a stent on the unsteady flow in cerebral aneurysms. The analysis is based on four different arterial models extracted form medical images, and the stent is placed across the neck of the aneurysm to reduce the flow circulation in the aneurysm. The core computational technique used in the analysis is the space-time (ST) version of the variational multiscale (VMS) method and is called "DSD/SST-VMST". The special techniques developed for this class of cardiovascular fluid mechanics computations are used in conjunction with the DSD/SST-VMST technique. The special techniques include NURBS representation of the surface over which the stent model and mesh are built, mesh generation with a reasonable resolution across the width of the stent wire and with refined layers of mesh near the arterial and stent surfaces, modeling the double-stent case, and quantitative assessment of the flow circulation in the aneurysm. We provide a brief overview of the special techniques, compute the unsteady flow patterns in the aneurysm for the four arterial models, and investigate in each case how those patterns are influenced by the presence of single and double stents.

  17. Abdominal aortic aneurysm.

    PubMed

    Keisler, Brian; Carter, Chuck

    2015-04-15

    Abdominal aortic aneurysm refers to abdominal aortic dilation of 3.0 cm or greater. The main risk factors are age older than 65 years, male sex, and smoking history. Other risk factors include a family history of abdominal aortic aneurysm, coronary artery disease, hypertension, peripheral artery disease, and previous myocardial infarction. Diagnosis may be made by physical examination, an incidental finding on imaging, or ultrasonography. The U.S. Preventive Services Task Force released updated recommendations for abdominal aortic aneurysm screening in 2014. Men 65 to 75 years of age with a history of smoking should undergo one-time screening with ultrasonography based on evidence that screening will improve abdominal aortic aneurysm-related mortality in this population. Men in this age group without a history of smoking may benefit if they have other risk factors (e.g., family history of abdominal aortic aneurysm, other vascular aneurysms, coronary artery disease). There is inconclusive evidence to recommend screening for abdominal aortic aneurysm in women 65 to 75 years of age with a smoking history. Women without a smoking history should not undergo screening because the harms likely outweigh the benefits. Persons who have a stable abdominal aortic aneurysm should undergo regular surveillance or operative intervention depending on aneurysm size. Surgical intervention by open or endovascular repair is the primary option and is typically reserved for aneurysms 5.5 cm in diameter or greater. There are limited options for medical treatment beyond risk factor modification. Ruptured abdominal aortic aneurysm is a medical emergency presenting with hypotension, shooting abdominal or back pain, and a pulsatile abdominal mass. It is associated with high prehospitalization mortality. Emergent surgical intervention is indicated for a rupture but has a high operative mortality rate. PMID:25884861

  18. Non coding RNAs in aortic aneurysmal disease

    PubMed Central

    Duggirala, Aparna; Delogu, Francesca; Angelini, Timothy G.; Smith, Tanya; Caputo, Massimo; Rajakaruna, Cha; Emanueli, Costanza

    2015-01-01

    An aneurysm is a local dilatation of a vessel wall which is >50% its original diameter. Within the spectrum of cardiovascular diseases, aortic aneurysms are among the most challenging to treat. Most patients present acutely after aneurysm rupture or dissection from a previous asymptomatic condition and are managed by open surgical or endovascular repair. In addition, patients may harbor concurrent disease contraindicating surgical intervention. Collectively, these factors have driven the search for alternative methods of identifying, monitoring and treating aortic aneurisms using less invasive approaches. Non-coding RNA (ncRNAs) are emerging as new fundamental regulators of gene expression. The small microRNAs have opened the field of ncRNAs capturing the attention of basic and clinical scientists for their potential to become new therapeutic targets and clinical biomarkers for aortic aneurysm. More recently, long ncRNAs (lncRNAs) have started to be actively investigated, leading to first exciting reports, which further suggest their important and yet largely unexplored contribution to vascular physiology and disease. This review introduces the different ncRNA types and focus at ncRNA roles in aorta aneurysms. We discuss the potential of therapeutic interventions targeting ncRNAs and we describe the research models allowing for mechanistic studies and clinical translation attempts for controlling aneurysm progression. Furthermore, we discuss the potential role of microRNAs and lncRNAs as clinical biomarkers. PMID:25883602

  19. Non coding RNAs in aortic aneurysmal disease.

    PubMed

    Duggirala, Aparna; Delogu, Francesca; Angelini, Timothy G; Smith, Tanya; Caputo, Massimo; Rajakaruna, Cha; Emanueli, Costanza

    2015-01-01

    An aneurysm is a local dilatation of a vessel wall which is >50% its original diameter. Within the spectrum of cardiovascular diseases, aortic aneurysms are among the most challenging to treat. Most patients present acutely after aneurysm rupture or dissection from a previous asymptomatic condition and are managed by open surgical or endovascular repair. In addition, patients may harbor concurrent disease contraindicating surgical intervention. Collectively, these factors have driven the search for alternative methods of identifying, monitoring and treating aortic aneurisms using less invasive approaches. Non-coding RNA (ncRNAs) are emerging as new fundamental regulators of gene expression. The small microRNAs have opened the field of ncRNAs capturing the attention of basic and clinical scientists for their potential to become new therapeutic targets and clinical biomarkers for aortic aneurysm. More recently, long ncRNAs (lncRNAs) have started to be actively investigated, leading to first exciting reports, which further suggest their important and yet largely unexplored contribution to vascular physiology and disease. This review introduces the different ncRNA types and focus at ncRNA roles in aorta aneurysms. We discuss the potential of therapeutic interventions targeting ncRNAs and we describe the research models allowing for mechanistic studies and clinical translation attempts for controlling aneurysm progression. Furthermore, we discuss the potential role of microRNAs and lncRNAs as clinical biomarkers. PMID:25883602

  20. Pharmacological Inhibitor of Notch Signaling Stabilizes the Progression of Small Abdominal Aortic Aneurysm in a Mouse Model

    PubMed Central

    Cheng, Jeeyun; Koenig, Sara N.; Kuivaniemi, Helena S.; Garg, Vidu; Hans, Chetan P.

    2014-01-01

    Background The progression of abdominal aortic aneurysm (AAA) involves a sustained influx of proinflammatory macrophages, which exacerbate tissue injury by releasing cytokines, chemokines, and matrix metalloproteinases. Previously, we showed that Notch deficiency reduces the development of AAA in the angiotensin II–induced mouse model by preventing infiltration of macrophages. Here, we examined whether Notch inhibition in this mouse model prevents progression of small AAA and whether these effects are associated with altered macrophage differentiation. Methods and Results Treatment with pharmacological Notch inhibitor (DAPT [N‐(N‐[3,5‐difluorophenacetyl]‐L‐alanyl)‐S‐phenylglycine t‐butyl ester]) at day 3 or 8 of angiotensin II infusion arrested the progression of AAA in Apoe−/− mice, as demonstrated by a decreased luminal diameter and aortic width. The abdominal aortas of Apoe−/− mice treated with DAPT showed decreased expression of matrix metalloproteinases and presence of elastin precursors including tropoelastin and hyaluronic acid. Marginal adventitial thickening observed in the aorta of DAPT‐treated Apoe−/− mice was not associated with increased macrophage content, as observed in the mice treated with angiotensin II alone. Instead, DAPT‐treated abdominal aortas showed increased expression of Cd206‐positive M2 macrophages and decreased expression of Il12‐positive M1 macrophages. Notch1 deficiency promoted M2 differentiation of macrophages by upregulating transforming growth factor β2 in bone marrow–derived macrophages at basal levels and in response to IL4. Protein expression of transforming growth factor β2 and its downstream effector pSmad2 also increased in DAPT‐treated Apoe−/− mice, indicating a potential link between Notch and transforming growth factor β2 signaling in the M2 differentiation of macrophages. Conclusions Pharmacological inhibitor of Notch signaling prevents the progression of AAA by macrophage

  1. Aneurysm in the brain

    MedlinePlus

    ... Supplements Videos & Tools Español You Are Here: Home → ... JavaScript. An aneurysm is a weak area in the wall of a blood vessel that causes the blood vessel to bulge or balloon out. When an aneurysm occurs in a blood ...

  2. Brain aneurysm repair - discharge

    MedlinePlus

    ... Supplements Videos & Tools Español You Are Here: Home → ... You had a brain aneurysm. An aneurysm is a weak area in the wall of a blood vessel that bulges or balloons out. Once it reaches a certain size, it ...

  3. The Strategic Assessment Model.

    ERIC Educational Resources Information Center

    Glazner, Steve, Ed.

    This book presents six papers focusing on the application of the strategic assessment model (SAM) to the management of higher education facilities. The papers are part of an ongoing effort by the Association of Higher Education Facilities Officers to provide comparative cost and staffing information and to develop a benchmarking process. The…

  4. Acquired Jugular Vein Aneurysm

    PubMed Central

    Hopsu, Erkki; Tarkkanen, Jussi; Vento, Seija I.; Pitkäranta, Anne

    2009-01-01

    Venous malformations of the jugular veins are rare findings. Aneurysms and phlebectasias are the lesions most often reported. We report on an adult patient with an abruptly appearing large tumorous mass on the left side of the neck identified as a jugular vein aneurysm. Upon clinical examination with ultrasound, a lateral neck cyst was primarily suspected. Surgery revealed a saccular aneurysm in intimate connection with the internal jugular vein. Histology showed an organized hematoma inside the aneurysmal sac, which had a focally thinned muscular layer. The terminology and the treatment guidelines of venous dilatation lesions are discussed. For phlebectasias, conservative treatment is usually recommended, whereas for saccular aneurysms, surgical resection is the treatment of choice. While an exact classification based on etiology and pathophysiology is not possible, a more uniform taxonomy would clarify the guidelines for different therapeutic modalities for venous dilatation lesions. PMID:20107571

  5. Diversity in the Strength and Structure of Unruptured Cerebral Aneurysms

    PubMed Central

    Robertson, Anne M.; Duan, Xinjie; Aziz, Khaled M.; Hill, Michael R.; Watkins, Simon C.; Cebral, Juan R.

    2015-01-01

    Intracranial aneurysms are pathological enlargements of brain arteries that are believed to arise from progressive wall degeneration and remodeling. Earlier work using classical histological approaches identified variability in cerebral aneurysm mural content, ranging from layered walls with intact endothelium and aligned smooth muscle cells, to thin, hypocellular walls. Here, we take advantage of recent advances in multiphoton microscopy, to provide novel results for collagen fiber architecture in 15 human aneurysm domes without staining or fixation as well as in 12 control cerebral arteries. For all aneurysm samples, the elastic lamina was absent and the abluminal collagen fibers had similar diameters to control arteries. In contrast, the collagen fibers on the luminal side showed great variability in both diameter and architecture ranging from dense fiber layers to sparse fiber constructs suggestive of ineffective remodeling efforts. The mechanical integrity of eight aneurysm samples was assessed using uniaxial experiments, revealing two sub-classes (i) vulnerable unruptured aneurysms (low failure stress and failure pressure), and (ii) strong unruptured aneurysms (high failure stress and failure pressure). These results suggest a need to refine the end-point of risk assessment studies that currently do not distinguish risk levels among unruptured aneurysms. We propose that a measure of wall integrity that identifies this vulnerable wall subpopulation will be useful for interpreting future biological and structural data. PMID:25632891

  6. 3D real-time visualization of blood flow in cerebral aneurysms by light field particle image velocimetry

    NASA Astrophysics Data System (ADS)

    Carlsohn, Matthias F.; Kemmling, André; Petersen, Arne; Wietzke, Lennart

    2016-04-01

    Cerebral aneurysms require endovascular treatment to eliminate potentially lethal hemorrhagic rupture by hemostasis of blood flow within the aneurysm. Devices (e.g. coils and flow diverters) promote homeostasis, however, measurement of blood flow within an aneurysm or cerebral vessel before and after device placement on a microscopic level has not been possible so far. This would allow better individualized treatment planning and improve manufacture design of devices. For experimental analysis, direct measurement of real-time microscopic cerebrovascular flow in micro-structures may be an alternative to computed flow simulations. An application of microscopic aneurysm flow measurement on a regular basis to empirically assess a high number of different anatomic shapes and the corresponding effect of different devices would require a fast and reliable method at low cost with high throughout assessment. Transparent three dimensional 3D models of brain vessels and aneurysms may be used for microscopic flow measurements by particle image velocimetry (PIV), however, up to now the size of structures has set the limits for conventional 3D-imaging camera set-ups. On line flow assessment requires additional computational power to cope with the processing large amounts of data generated by sequences of multi-view stereo images, e.g. generated by a light field camera capturing the 3D information by plenoptic imaging of complex flow processes. Recently, a fast and low cost workflow for producing patient specific three dimensional models of cerebral arteries has been established by stereo-lithographic (SLA) 3D printing. These 3D arterial models are transparent an exhibit a replication precision within a submillimeter range required for accurate flow measurements under physiological conditions. We therefore test the feasibility of microscopic flow measurements by PIV analysis using a plenoptic camera system capturing light field image sequences. Averaging across a sequence of

  7. Identification and characteristics of microRNAs with altered expression patterns in a rat model of abdominal aortic aneurysms.

    PubMed

    Liu, Guang; Huang, Ying; Lu, Xinwu; Lu, Min; Huang, Xintian; Li, Weimin; Jiang, Mier

    2010-11-01

    Abdominal aortic aneurysm (AAA) is a lethal disease, occurring mostly in men more than 65 years of age. Until recently, the pathogenesis of AAA remains poorly understood. MicroRNAs (miRNAs) are a novel class of endogenous small non-coding RNAs that play important roles in diverse biological and pathological processes including cardiovascular diseases. However, their biological roles in AAA formation have not been elucidated. In this study, we employed oligonucleotide microarrays to detect and compare miRNA expression profiles in a rat model of AAA. The abdominal aorta was exposed and incubated for 20 min with saline supplemented with calcium chloride and collagenase. After 28 days, the treated aortas were evaluated by digital measurement and angiography. A 50% increase over the normal diameter is considered as AAA. Our results revealed a set of differentially expressed miRNAs, with 10 significantly up-regulated and 5 significantly down-regulated miRNAs in AAA tissues. Four miRNAs (miR-19a, miR-19b, miR-132, and miR-221) were randomly selected for validation using real-time RT-PCR. Functional annotations of all putative targets of differentially expressed miRNAs via bioinformatics approaches revealed that predicted targets were highly enriched and involved in several key signaling pathways important for AAA formation, including pathways in cancer and signaling pathways involving mitogen-activated protein kinase, Wnt, neurotrophin, and ErbB. In summary, this study indicates that miRNAs might contribute to AAA formation probably by affecting multiple target genes and signaling pathways, which is expected to provide new clues to develop targeted therapies against this calamitous disease. PMID:21030819

  8. What You Should Know about Cerebral Aneurysms

    MedlinePlus

    ... About Stroke What You Should Know About Cerebral Aneurysms Updated:Jun 13,2014 About Cerebral Aneurysms Diagnosis ... to view an animation What is a cerebral aneurysm? An aneurysm is a weak area in a ...

  9. Morphological and Biomechanical Differences in the Elastase and AngII apoE−/− Rodent Models of Abdominal Aortic Aneurysms

    PubMed Central

    Phillips, Evan H.; Yrineo, Alexa A.; Schroeder, Hilary D.; Wilson, Katherine E.; Cheng, Ji-Xin; Goergen, Craig J.

    2015-01-01

    An abdominal aortic aneurysm (AAA) is a potentially fatal cardiovascular disease with multifactorial development and progression. Two preclinical models of the disease (elastase perfusion and angiotensin II infusion in apolipoprotein-E-deficient animals) have been developed to study the disease during its initiation and progression. To date, most studies have used ex vivo methods to examine disease characteristics such as expanded aortic diameter or analytic methods to look at circulating biomarkers. Herein, we provide evidence from in vivo ultrasound studies of the temporal changes occurring in biomechanical parameters and macromolecules of the aortic wall in each model. We present findings from 28-day studies in elastase-perfused rats and AngII apoE−/− mice. While each model develops AAAs specific to their induction method, they both share characteristics with human aneurysms, such as marked changes in vessel strain and blood flow velocity. Histology and nonlinear microscopy confirmed that both elastin and collagen, both important extracellular matrix molecules, are similarly affected in their levels and spatial distribution. Future studies could make use of the differences between these models in order to investigate mechanisms of disease progression or evaluate potential AAA treatments. PMID:26064906

  10. Hemodynamics of Cerebral Aneurysms

    PubMed Central

    Sforza, Daniel M.; Putman, Christopher M.; Cebral, Juan Raul

    2009-01-01

    The initiation and progression of cerebral aneurysms are degenerative processes of the arterial wall driven by a complex interaction of biological and hemodynamic factors. Endothelial cells on the artery wall respond physiologically to blood-flow patterns. In normal conditions, these responses are associated with nonpathological tissue remodeling and adaptation. The combination of abnormal blood patterns and genetics predisposition could lead to the pathological formation of aneurysms. Here, we review recent progress on the basic mechanisms of aneurysm formation and evolution, with a focus on the role of hemodynamic patterns. PMID:19784385

  11. Increased 18F-FDG Uptake Is Predictive of Rupture in a Novel Rat Abdominal Aortic Aneurysm Rupture Model

    PubMed Central

    English, Sean J.; Piert, Morand R.; Diaz, Jose A.; Gordon, David; Ghosh, Abhijit; D'Alecy, Louis G.; Whitesall, Steven E.; Sharma, Ashish K.; DeRoo, Elise P.; Watt, Tessa; Su, Gang; Henke, Peter K.; Eliason, Jonathan L.; Ailawadi, Gorav; Upchurch, Gilbert R.

    2015-01-01

    Objective To determine whether 18F-fluorodeoxyglucose (18F-FDG) micro–positron emission tomography (micro-PET) can predict abdominal aortic aneurysm (AAA) rupture. Background An infrarenal AAA model is needed to study inflammatory mechanisms that drive rupture. 18F-FDG PET can detect vascular inflammation in animal models and patients. Methods After exposing Sprague-Dawley rats to intra-aortic porcine pancreatic elastase (PPE) (12 U/mL), AAA rupture was induced by daily, subcutaneous, β-aminopropionitrile (BAPN, 300 mg/kg, N = 24) administration. Negative control AAA animals (N = 15) underwent daily saline subcutaneous injection after PPE exposure. BAPN-exposed animals that did not rupture served as positive controls [nonruptured AAA (NRAAA) 14d, N = 9]. Rupture was witnessed using radiotelemetry. Maximum standard uptakes for 18F-FDG micro-PET studies were determined. Aortic wall PAI-1, uPA, and tPA concentrations were determined by western blot analyses. Interleukin (IL)-1β, IL-6, IL-10, and MIP-2 were determined by Bio-Plex bead array. Neutrophil and macrophage populations per high-power field were quantified. Matrix metalloproteinase (MMP) activities were determined by zymography. Results When comparing ruptured AAA (RAAA) to NRAAA 14d animals, increased focal 18F-FDG uptakes were detected at subsequent sites of rupture (P = 0.03). PAI-1 expression was significantly less in RAAA tissue (P = 0.01), with comparable uPA and decreased tPA levels (P = 0.02). IL-1β (P = 0.04), IL-6 (P = 0.001), IL-10 (P = 0.04), and MIP-2 (P = 0.02)expression, neutrophil (P = 0.02) and macrophage presence (P = 0.002), and MMP9 (P < 0.0001) activity were increased in RAAA tissue. Conclusions With this AAA rupture model, increased prerupture 18F-FDG uptake on micro-PET imaging was associated with increased inflammation in the ruptured AAA wall. 18F-FDG PET imaging may be used to monitor inflammatory changes before AAA rupture. PMID:24651130

  12. Integrated Assessment Model Evaluation

    NASA Astrophysics Data System (ADS)

    Smith, S. J.; Clarke, L.; Edmonds, J. A.; Weyant, J. P.

    2012-12-01

    Integrated assessment models of climate change (IAMs) are widely used to provide insights into the dynamics of the coupled human and socio-economic system, including emission mitigation analysis and the generation of future emission scenarios. Similar to the climate modeling community, the integrated assessment community has a two decade history of model inter-comparison, which has served as one of the primary venues for model evaluation and confirmation. While analysis of historical trends in the socio-economic system has long played a key role in diagnostics of future scenarios from IAMs, formal hindcast experiments are just now being contemplated as evaluation exercises. Some initial thoughts on setting up such IAM evaluation experiments are discussed. Socio-economic systems do not follow strict physical laws, which means that evaluation needs to take place in a context, unlike that of physical system models, in which there are few fixed, unchanging relationships. Of course strict validation of even earth system models is not possible (Oreskes etal 2004), a fact borne out by the inability of models to constrain the climate sensitivity. Energy-system models have also been grappling with some of the same questions over the last quarter century. For example, one of "the many questions in the energy field that are waiting for answers in the next 20 years" identified by Hans Landsberg in 1985 was "Will the price of oil resume its upward movement?" Of course we are still asking this question today. While, arguably, even fewer constraints apply to socio-economic systems, numerous historical trends and patterns have been identified, although often only in broad terms, that are used to guide the development of model components, parameter ranges, and scenario assumptions. IAM evaluation exercises are expected to provide useful information for interpreting model results and improving model behavior. A key step is the recognition of model boundaries, that is, what is inside

  13. Alterations in membrane type-1 matrix metalloproteinase abundance after the induction of thoracic aortic aneurysm in a murine model

    PubMed Central

    Jones, Jeffrey A.; Ruddy, Jean Marie; Bouges, Shenikqua; Zavadzkas, Juozas A.; Brinsa, Theresa A.; Stroud, Robert E.; Mukherjee, Rupak; Spinale, Francis G.

    2010-01-01

    Thoracic aortic aneurysms (TAAs) develop as a result of dysregulated extracellular matrix remodeling mediated by several matrix metalloproteinases (MMPs). Membrane type-1 MMP (MT1-MMP) is the prototypical member of a unique family of membrane-bound MMPs, possessing multiple substrates and functions. The present study tested the hypothesis that MT1-MMP expression, abundance, and activity would be elevated during TAA development and that this protease is produced primarily by mesenchymal cells within the thoracic aorta. Descending thoracic aortas were harvested from C57BL/6J mice at multiple time points (2, 4, 8, and 16 wk, n = 15 each) post-TAA induction (0.5M CaCl2, 15 min) and compared with reference controls (n = 15). The expression and abundance of MT1-MMP, MMP-2, and tissue inhibitor of metalloproteinase (TIMP)-2 were assessed by quantitative PCR and immunoblot analysis. MT1-MMP activity was determined by fluorescent peptide assay. MT1-MMP was localized within the aortic wall by immunohistochemistry. MT1-MMP abundance and localization in live animals (8 wk post-TAA induction vs. control) was determined by microultrasound imaging with an MT1-MMP-targeted microbubble contrast agent. Aortic diameter was increased 172 ± 7% at 16 wk post-TAA induction (P < 0.05). MT1-MMP and MMP-2 mRNA levels were elevated at 2 wk post-TAA induction (P < 0.05). MT1-MMP protein abundance increased progressively to a maximum of 178 ± 26% at 16 wk post-TAA induction, whereas MMP-2 and TIMP-2 peaked at 2 wk post-TAA induction (526 ± 93% and 376 ± 48%, respectively, P < 0.05). MT1-MMP colocalized with fibroblasts, and MT1-MMP-targeted contrast binding was elevated in 8-wk TAA-induced mice versus control mice (217 ± 53% vs. 81 ± 8%, P < 0.05). In conclusion, these novel results suggest that MT1-MMP plays a dynamic multifunctional role in TAA development and, therefore, may provide a significant target for therapeutic strategies. PMID:20418476

  14. Safety of coil occlusion of the parent artery for endovascular treatment of anterior communicating artery aneurysm.

    PubMed

    Kim, Sanghyeon; Kang, Myongjin; Choi, Jae-Hyung; Kim, Dong Won

    2016-06-01

    Many studies lay emphasis on the clinical importance of perforating branches of the anterior communicating artery (ACoA) and report that vascular damage of the perforators from ACoA aneurysm during surgery cause subsequent postoperative amnesia. The purpose of our study was to analyze the safety of parent artery occlusion for ACoA aneurysm coiling based on the anatomical features of the ACoA complex in 13 patients with 13 ACoA aneurysms. All patients underwent coiling of the aneurysm sac and ACoA. Aneurysm characteristics including size, dome-to-neck ratio, anterior/posterior orientation of the aneurysm dome with respect to the axis of the pericallosal artery, location of the aneurysm neck with respect to the A1-A2 segment of the anterior cerebral artery (ACA) or the ACoA, and the presence of hypoplasia/aplasia of A1 segment were assessed. The aneurysm neck was located directly on the ACoA in five aneurysms (38%), whereas eight (62%) had the neck located at the A1-A2 junction. Of the five patients whose aneurysm neck was located in the ACoA, four patients had infarcts in the basal forebrain. Three of the patients complained of amnesia. None of the aneurysms with the neck located at the A1-A2 junction were associated with infarction. There has been little evidence thus far that parent vessel occlusion of ACoA aneurysms is a safe method for the treatment of aneurysms. Patients with the aneurysm neck located at the A1-A2 junction and without A1 aplasia, who were treated with aneurysm sac and ACoA embolism, were potentially safe. PMID:26988084

  15. A shell-based inverse approach of stress analysis in intracranial aneurysms

    PubMed Central

    Lu, Jia; Hu, Shouhua; Raghavan, Madhavan L.

    2013-01-01

    Predicting pressure induced wall stress in intracranial aneurysms continues to be of interest for aneurysm safety assessment. In quasi-static analysis, there are two distinct approaches that one may take, the forward approach and the inverse approach. The inverse approach starts from a deformed configuration and thus is naturally suited to image-based, patient-specific analysis. Early studies by the authors’ team suggested that the inverse approach, in the context of estimating the wall stress in cerebral aneurysms, depends weakly on the material description. In this article, we present a population study to further demonstrate the inverse method, in particular, the remarkable feature of insensitivity to material properties. Twenty six aneurysm models derived from patient-specific images were employed in the study. Wall stresses were predicted in both the inverse and forward approaches using three material models. Results showed that, while forward computation yielded up to ~100% stress difference between some materials, the inverse solutions stayed close across materials. The inverse method, in addition to being methodologically accurate in dealing with pre-deformations, has the added convenience of insensitivity to uncertainties in wall tissue properties. New insight into the stress-geometry relation was also discussed. PMID:23392863

  16. Global Change Assessment Model (GCAM)

    EPA Science Inventory

    The Global Change Assessment Model (GCAM) is an integrated assessment model that links the world's energy, agriculture and land use systems with a climate model. The model is designed to assess various climate change policies and technology strategies for the globe over long tim...

  17. Prenatal diagnosis of ductus arteriosus aneurysm.

    PubMed

    Ganesan, S; Hutchinson, D P; Sampson, A J

    2015-11-01

    The ductus arteriosus holds major functional importance within the fetal circulation, and anomalies within the ductus arteriosus may interfere with the integrity of the fetal circulation. Ductus arteriosus aneurysm, previously considered a rare lesion, is now a well-reported finding in infancy with some reports describing this finding in the prenatal period. Postnatally, most ductus arteriosus aneurysms resolve spontaneously; however, a small group of infants show complications such as connective-tissue disorders, thrombo-embolism, compression of surrounding thoracic structures and life-threatening spontaneous rupture requiring surgical correction. As such, postnatal assessment in this group is recommended. PMID:27433265

  18. Saphenous vein graft aneurysm: A case report

    PubMed Central

    Gurbuz, Ahmet Seyfeddin; Ozturk, Semi; Acar, Emrah; Efe, Suleyman Cagan; Kilicgedik, Alev; Kirma, Cevat

    2016-01-01

    BACKGROUND Saphenous vein graft aneurysms (SVGAs) are rare seen issues after coronary artery bypass graft (CABG) operation which may lead to major complications including compression of adjacent structure, myocardial ischemia, rupture, and even death. CASE REPORT We report a patient with recurrent SVGA and its treatment by percutaneous intervention with a covered stent, the diagnostic and treatment procedure were based on contrast enhanced computed tomography and myocardial perfusion scintigraphy (MPS). CONCLUSION Multimodality imaging is required to demonstrate the true size and complications of the SVGA, the relationship among the adjacent structure, and to assess ischemia and size of myocardial territory supplied by the aneurysmal graft to decide treatment strategy.

  19. Endovascular treatment of basilar aneurysms.

    PubMed

    Marlin, Evan S; Ikeda, Daniel S; Shaw, Andrew; Powers, Ciarán J; Sauvageau, Eric

    2014-07-01

    Basilar artery aneurysms account for a small percentage of intracranial aneurysms; however, they are a diverse group of lesions necessitating different treatment techniques for those that are ruptured and unruptured. Basilar apex aneurysms are the most common type and are frequently wide-necked, necessitating stent-assisted coiling or balloon remodeling. Other techniques have evolved to forego stenting in acutely ruptured wide-necked aneurysms. The prevention of delayed thromboembolic complications with dual antiplatelet therapy in patients with stents is critical. After treatment, basilar aneurysms require close follow-up to ensure complete occlusion. Basilar apex aneurysms often require delayed re-treatment, especially when previously ruptured. PMID:24994086

  20. Treatment of rabbit carotid aneurysms by hybrid stents (microporous thin polyurethane-covered stents): Preservation of side-branches

    PubMed Central

    Nishi, Shogo; Nakayama, Yasuhide; Ishibashi-Ueda, Hatsue; Yoshida, Masato; Yonetani, Hiroshi

    2014-01-01

    Objective We sought to determine the patency of normal arterial branches from the covered segments of an artery after stenting. Background Most intracranial aneurysms occur at arterial branching points (bifurcations, side-branches, or perforators). The post-stenting patency of normal arterial branches from the covered segments of the artery is important. We have previously developed a hybrid stent with micropores to prevent early parent artery occlusion by more early endothelialization, and mid- to long-term parent artery stenosis by control of intimal hyperplasia after aneurysm occlusion. Methods We created aneurysms in 10 rabbits by distal ligation and intraluminal incubation of elastase within an endovascularly trapped proximal segment of the common carotid artery. All animals were treated with hybrid stents having micropores. Four animals were observed for one month and three each for three and 12 months. The patency of the side-branches of the subclavian artery was evaluated angiographically and in some cases, histologically. Results Aneurysms were completely occluded at all time points other than 12 months. The subclavian artery and brachiocephalic artery were patent, without significant stenosis. All the side-branches of the subclavian artery detected on the preoperative angiogram remained patent at the final assessment. Conclusion The use of hybrid stents for aneurysm repair and side-branch patency seems to be effective, as per the long-term results obtained in an animal model. PMID:23887877

  1. Integrated Assessment Modeling

    SciTech Connect

    Edmonds, James A.; Calvin, Katherine V.; Clarke, Leon E.; Janetos, Anthony C.; Kim, Son H.; Wise, Marshall A.; McJeon, Haewon C.

    2012-10-31

    This paper discusses the role of Integrated Assessment models (IAMs) in climate change research. IAMs are an interdisciplinary research platform, which constitutes a consistent scientific framework in which the large-scale interactions between human and natural Earth systems can be examined. In so doing, IAMs provide insights that would otherwise be unavailable from traditional single-discipline research. By providing a broader view of the issue, IAMs constitute an important tool for decision support. IAMs are also a home of human Earth system research and provide natural Earth system scientists information about the nature of human intervention in global biogeophysical and geochemical processes.

  2. Biosafety Risk Assessment Model

    SciTech Connect

    2011-05-27

    Software tool based on a structured methodology for conducting laboratory biosafety risk assessments by biosafety experts. Software is based upon an MCDA scheme and uses peer reviewed criteria and weights. The software was developed upon Microsoft’s .net framework. The methodology defines likelihood and consequence of a laboratory exposure for thirteen unique scenarios and provides numerical relative risks for each of the relevant thirteen. The software produces 2-d graphs reflecting the relative risk and a sensitivity analysis which highlights the overall importance of each factor. The software works as a set of questions with absolute scales and uses a weighted additive model to calculate the likelihood and consequence.

  3. Giant Subclavian Artery Aneurysm.

    PubMed

    Counts, Sarah; Zeeshan, Ahmad; Elefteriades, John

    2016-06-01

    We report the case of a 37-year-old construction executive presenting with chest pain, shortness of breath, and dizziness on exertion secondary to a giant left subclavian artery aneurysm and aortic valvular disease. PMID:27231430

  4. Abdominal aortic aneurysm

    MedlinePlus

    ... main blood vessel that supplies blood to the abdomen, pelvis, and legs. An abdominal aortic aneurysm occurs ... dissection). Symptoms of rupture include: Pain in the abdomen or back. The pain may be severe, sudden, ...

  5. Popliteal vein aneurysm.

    PubMed

    Falkowski, A; Poncyljusz, W; Zawierucha, D; Kuczmik, W

    2006-06-01

    The incidence of a popliteal vein aneurysm is extremely low. Two cases of this rare venous anomaly are described. The epidemiology, morphology, and diagnostic methods are discussed and the potentially dangerous complications and treatment methods are presented. PMID:16796307

  6. Aneurysmal Subarachnoid Hemorrhage.

    PubMed

    D'Souza, Stanlies

    2015-07-01

    Aneurysmal subarachnoid hemorrhage (SAH) is a worldwide health burden with high fatality and permanent disability rates. The overall prognosis depends on the volume of the initial bleed, rebleeding, and degree of delayed cerebral ischemia (DCI). Cardiac manifestations and neurogenic pulmonary edema indicate the severity of SAH. The International Subarachnoid Aneurysm Trial (ISAT) reported a favorable neurological outcome with the endovascular coiling procedure compared with surgical clipping at the end of 1 year. The ISAT trial recruits were primarily neurologically good grade patients with smaller anterior circulation aneurysms, and therefore the results cannot be reliably extrapolated to larger aneurysms, posterior circulation aneurysms, patients presenting with complex aneurysm morphology, and poor neurological grades. The role of hypothermia is not proven to be neuroprotective according to a large randomized controlled trial, Intraoperative Hypothermia for Aneurysms Surgery Trial (IHAST II), which recruited patients with good neurological grades. Patients in this trial were subjected to slow cooling and inadequate cooling time and were rewarmed rapidly. This methodology would have reduced the beneficial effects of hypothermia. Adenosine is found to be beneficial for transient induced hypotension in 2 retrospective analyses, without increasing the risk for cardiac and neurological morbidity. The neurological benefit of pharmacological neuroprotection and neuromonitoring is not proven in patients undergoing clipping of aneurysms. DCI is an important cause of morbidity and mortality following SAH, and the pathophysiology is likely multifactorial and not yet understood. At present, oral nimodipine has an established role in the management of DCI, along with maintenance of euvolemia and induced hypertension. Following SAH, hypernatremia, although less common than hyponatremia, is a predictor of poor neurological outcome. PMID:25272066

  7. Abdominal aortic aneurysm.

    PubMed

    Setacci, Francesco; Galzerano, Giuseppe; De Donato, Gianmarco; Benevento, Domenico; Guerrieri, Massimiliano W; Ruzzi, Umberto; Borrelli, Maria P; Setacci, Carlo

    2016-02-01

    Endovascular repair of abdominal aortic aneurysms has become a milestone in the treatment of patients with abdominal aortic aneurysm. Technological improvement allows treatment in more and more complex cases. This review summarizes all grafts available on the market. A complete review of most important trial on this topic is provided to the best of our knowledge, and technical tips and tricks for standard cases are also included. PMID:26771730

  8. Pelvic aneurysmal bone cyst

    PubMed Central

    Sharifah, MIA; Nor Hazla, MH; Suraya, A; Tan, SP

    2011-01-01

    This paper describes an extremely rare case of a huge aneurysmal bone cyst (ABC) in the pelvis, occurring in the patient’s 5th decade of life. The patient presented with a history of painless huge pelvic mass for 10 years. Plain radiograph and computed tomography showed huge expansile lytic lesion arising from the right iliac bone. A biopsy was performed and histology confirmed diagnosis of aneurysmal bone cyst. Unfortunately, the patient succumbed to profuse bleeding from the tumour. PMID:22279501

  9. Aneurysmal Subarachnoid Hemorrhage

    PubMed Central

    2015-01-01

    Aneurysmal subarachnoid hemorrhage (SAH) is a worldwide health burden with high fatality and permanent disability rates. The overall prognosis depends on the volume of the initial bleed, rebleeding, and degree of delayed cerebral ischemia (DCI). Cardiac manifestations and neurogenic pulmonary edema indicate the severity of SAH. The International Subarachnoid Aneurysm Trial (ISAT) reported a favorable neurological outcome with the endovascular coiling procedure compared with surgical clipping at the end of 1 year. The ISAT trial recruits were primarily neurologically good grade patients with smaller anterior circulation aneurysms, and therefore the results cannot be reliably extrapolated to larger aneurysms, posterior circulation aneurysms, patients presenting with complex aneurysm morphology, and poor neurological grades. The role of hypothermia is not proven to be neuroprotective according to a large randomized controlled trial, Intraoperative Hypothermia for Aneurysms Surgery Trial (IHAST II), which recruited patients with good neurological grades. Patients in this trial were subjected to slow cooling and inadequate cooling time and were rewarmed rapidly. This methodology would have reduced the beneficial effects of hypothermia. Adenosine is found to be beneficial for transient induced hypotension in 2 retrospective analyses, without increasing the risk for cardiac and neurological morbidity. The neurological benefit of pharmacological neuroprotection and neuromonitoring is not proven in patients undergoing clipping of aneurysms. DCI is an important cause of morbidity and mortality following SAH, and the pathophysiology is likely multifactorial and not yet understood. At present, oral nimodipine has an established role in the management of DCI, along with maintenance of euvolemia and induced hypertension. Following SAH, hypernatremia, although less common than hyponatremia, is a predictor of poor neurological outcome. PMID:25272066

  10. Hemodynamic Alterations after Stent Implantation in 15 Cases of Intracranial Aneurysms

    PubMed Central

    Wang, Chao; Tian, Zhongbin; Liu, Jian; Jing, Linkai; Paliwal, Nikhil; Wang, Shengzhang; Zhang, Ying; Xiang, Jianping; Siddiqui, Adnan H; Meng, Hui; Yang, Xinjian

    2016-01-01

    Background Stent-assisted coiling technology has been widely used in the treatment of intracranial aneurysms. In current study, we investigated the intra-aneurysmal hemodynamic alterations after stent implantation and its association with aneurysm location. Methods We first retrospectively studied 15 aneurysm cases (8 internal carotid artery-ophthalmic artery (ICA-OphA) aneurysms and 7 posterior communicating artery (PcoA) aneurysms) treated with Enterprise stents and coils. Then based on patient-specific geometries before and after stenting, we built virtual stenting computational fluid dynamics (CFD) simulation models. Results Before and after stent deployment, the average Wall Shear Stress (WSS) on the aneurysmal sac at systolic peak changed from 7.04 Pa (4.14 Pa, 15.77 Pa) to 6.04 Pa (3.86 Pa, 11.13 Pa), P = 0.001; and the spatially averaged value of flow velocity in the perpendicular plane of aneurysm dropped from 0.5 m/s (0.28 m/s, 0.7 m/s) to 0.33 m/s (0.25 m/s, 0.49 m/s), P = 0.001, respectively. Post-stent implantation, WSS in ICA-OphA aneurysms and PcoA aneurysms decreased by 14.4% (P = 0.012) and 16.6% (P = 0.018) respectively, and flow velocity also reduced by 10.3% (P = 0.029) and 10.5% (P = 0.013), respectively. Changes in WSS, flow velocity, and pressure were not significantly different between ICA-OphA aneurysms and PcoA aneurysms (P > 0.05). Stent implantation did not significantly change the peak systolic pressure in both aneurysm types. Conclusion After stent implantation, intra-aneurysmal flow velocity and WSS decreased independent of aneurysm type (ICA-OphA and PcoA). Little change was observed on peak systolic pressure. PMID:26746828

  11. Development and validation of a disease-specific scale to assess psychosocial well-being of patients living with unruptured intracranial aneurysm.

    PubMed

    Fujishima-Hachiya, Asami; Inoue, Tomoko

    2012-12-01

    Although the detection rate for unruptured intracranial aneurysm (UIA) has improved since the 1990s, the quality of life and psychosocial status of patients living with UIA have been negatively affected. However, a comprehensive assessment tool for UIA patients is still awaited. This study aimed to develop and validate a disease-specific scale to assess UIA patients' psychosocial well-being in their daily lives. On the basis of previous qualitative research, 52 items on a six-dimension scale were generated. After a pilot study, statistical analysis was conducted to examine construct validity-including convergent validity, discriminant and known-group validity, and internal reliability. Between 2010 and 2011, 124 patients across three hospitals in Japan were tested using a tentative scale. As a result of exploratory factor analysis, we identified 25 items based on five conceptually derived dimensions (psychological stability, trust in healthcare resources, satisfaction with the decision-making process, positive perception of self-management, and confidence in UIA knowledge) as a final psychosocial well-being scale for UIA patients (UIA-PW scale). Cronbach's alpha coefficients for each subscale ranged between .76 and .90, with .83 for the total score, which indicated satisfactory internal consistency. The total score for the UIA-PW scale correlated significantly with the existing quality of life and mental health scales, but it is important to note that psychological stability and positive perception of self-management were negatively correlated. Although additional investigation is needed, the UIA-PW scale shows reasonable validity and reliability in assessing psychosocial well-being of patients living with UIA. PMID:22948040

  12. Haemodynamics of giant cerebral aneurysm: A comparison between the rigid-wall, one-way and two-way FSI models

    NASA Astrophysics Data System (ADS)

    Khe, A. K.; Cherevko, A. A.; Chupakhin, A. P.; Bobkova, M. S.; Krivoshapkin, A. L.; Orlov, K. Yu

    2016-06-01

    In this paper a computer simulation of a blood flow in cerebral vessels with a giant saccular aneurysm at the bifurcation of the basilar artery is performed. The modelling is based on patient-specific clinical data (both flow domain geometry and boundary conditions for the inlets and outlets). The hydrodynamic and mechanical parameters are calculated in the frameworks of three models: rigid-wall assumption, one-way FSI approach, and full (two-way) hydroelastic model. A comparison of the numerical solutions shows that mutual fluid- solid interaction can result in qualitative changes in the structure of the fluid flow. Other characteristics of the flow (pressure, stress, strain and displacement) qualitatively agree with each other in different approaches. However, the quantitative comparison shows that accounting for the flow-vessel interaction, in general, decreases the absolute values of these parameters. Solving of the hydroelasticity problem gives a more detailed solution at a cost of highly increased computational time.

  13. Screening for Abdominal Aortic Aneurysm

    MedlinePlus

    Understanding Task Force Recommendations Screening for Abdominal Aortic Aneurysm The U.S. Preventive Services Task Force (Task Force) ... final recommendation statement on Screening for Abdominal Aortic Aneurysm. This final recommendation statement applies to adults ages ...

  14. [Thoracoabdominal aortic aneurysm].

    PubMed

    Kalder, J; Kotelis, D; Jacobs, M J

    2016-09-01

    Thoracoabdominal aortic aneurysms (TAAA) are rare events with an incidence of 5.9 cases per 100,000 persons per year. In Germany approximately 940 TAAA procedures are performed annually. The cause of TAAA is mostly degenerative but they can also occur on the basis of an aortic dissection or connective tissue disease (e. g. Marfan's syndrome). Patients often have severe comorbidities and suffer from hypertension, coronary heart disease or chronic obstructive pulmonary disease, mostly as a result of smoking. Operative treatment is indicated when the maximum aortic diameter has reached 6 cm (> 5 cm in patients with connective tissue disease) or the aortic diameter rapidly increases (> 5 mm/year). Treatment options are open surgical aortic repair with extracorporeal circulation, endovascular repair with branched/fenestrated endografts and parallel grafts (chimneys) or a combination of open and endovascular procedures (hybrid procedures). Mortality rates after both open and endovascular procedures are approximately 8 % depending on the extent of the repair. Furthermore, there are relevant risks of complications, such as paraplegia (up to 20 %) and the necessity for dialysis. In recent years several approaches to minimize these risks have been proposed. Besides cardiopulmonary risk evaluation, clinical assessment of patients by the physician with respect to the patient-specific anatomy influences the allocation of patients to one treatment option or another. Surgery of TAAA should ideally be performed in high-volume centers in order to achieve better results. PMID:27558261

  15. Biosafety Risk Assessment Model

    Energy Science and Technology Software Center (ESTSC)

    2011-05-27

    Software tool based on a structured methodology for conducting laboratory biosafety risk assessments by biosafety experts. Software is based upon an MCDA scheme and uses peer reviewed criteria and weights. The software was developed upon Microsoft’s .net framework. The methodology defines likelihood and consequence of a laboratory exposure for thirteen unique scenarios and provides numerical relative risks for each of the relevant thirteen. The software produces 2-d graphs reflecting the relative risk and a sensitivitymore » analysis which highlights the overall importance of each factor. The software works as a set of questions with absolute scales and uses a weighted additive model to calculate the likelihood and consequence.« less

  16. Diabetes may affect intracranial aneurysm stabilization in older patients: Analysis based on intraoperative findings

    PubMed Central

    Song, Jihye; Shin, Yong Sam

    2016-01-01

    Background: Only a small proportion of aneurysms progress to rupture. Previous studies have focused on predicting the rupture risk of intracranial aneurysms. Atherosclerotic aneurysm wall appears resistant to rupture. The purpose of this study was to evaluate clinical and morphological factors affecting atherosclerosis of an aneurysm and identify the parameters that predict aneurysm stabilization. Methods: We conducted a retrospective analysis of 253 consecutive patients with 291 unruptured aneurysms who underwent clipping surgery in a single institution between January 2012 and October 2013. Aneurysms were categorized based on intraoperative video findings and assessed morphologic and demographic data. Aneurysms which had the atherosclerotic wall without any super thin and transparent portion were defined as stabilized group and the others as a not-stabilized group. Results: Of the 207 aneurysms, 176 (85.0%) were assigned to the not-stabilized group and 31 (15.0%) to the stabilized group. The relative proportion of stabilized aneurysms increased significantly as the age increased (P < 0.001). Univariate logistic analysis showed that age ≥65 years (P < 0.001), hypertension (P = 0.012), diabetes (P = 0.007), and height ≥3 mm (P = 0.007) were correlated with stabilized aneurysms. Multivariate logistic analysis showed that age ≥65 years (P = 0.009) and hypertension (P = 0.041) were strongly correlated with stable aneurysms. In older patients (≥65 years of age), multivariate logistic regression revealed that only diabetes was associated with stabilized aneurysms (P = 0.027). Conclusions: In patients ≥65 years of age, diabetes mellitus may highly predict the stabilized aneurysms. These results provide useful information in determining treatment and follow-up strategies, especially in older patients. PMID:27313965

  17. How Is an Aneurysm Diagnosed?

    MedlinePlus

    ... from the NHLBI on Twitter. How Is an Aneurysm Diagnosed? If you have an aortic aneurysm but no symptoms, your doctor may find it ... a routine physical exam. More often, doctors find aneurysms during tests done for other reasons, such as ...

  18. Accuracy of Computational Cerebral Aneurysm Hemodynamics Using Patient-Specific Endovascular Measurements

    PubMed Central

    McGah, Patrick M.; Levitt, Michael R.; Barbour, Michael C.; Morton, Ryan P.; Nerva, John D.; Mourad, Pierre D.; Ghodke, Basavaraj V.; Hallam, Danial K.; Sekhar, Laligam N.; Kim, Louis J.; Aliseda, Alberto

    2013-01-01

    Computational hemodynamic simulations of cerebral aneurysms have traditionally relied on stereotypical boundary conditions (such as blood flow velocity and blood pressure) derived from published values as patient-specific measurements are unavailable or difficult to collect. However, controversy persists over the necessity of incorporating such patient specific conditions into computational analyses. We perform simulations using both endovascular-derived patient-specific and typical literature-derived inflow and outflow boundary conditions. Detailed three-dimensional anatomical models of the cerebral vasculature are developed from rotational angiography data, and blood flow velocity and pressure are measured in situ by a dual-sensor pressure and velocity endovascular guidewire at multiple peri-aneurysmal locations in ten unruptured cerebral aneurysms. These measurements are used to define inflow and outflow boundary conditions for computational hemodynamic models of the aneurysms. The additional in situ measurements which are not prescribed in the simulation are then used to assess the accuracy of the simulated flow velocity and pressure drop. Simulated velocities using patient-specific boundary conditions show good agreement with the guidewire measurements at measurement locations inside the domain, with no bias in the agreement and a random scatter of ≈25%. Simulated velocities using the simplified, literature-derived values show a systematic bias and over-predicted velocity by ≈30% with a random scatter of ≈40%. Computational hemodynamics using endovascularly measured patient-specific boundary conditions have the potential to improve treatment predictions as they provide more accurate and precise results of the aneurysmal hemodynamics than those based on commonly accepted reference values for boundary conditions. PMID:24162859

  19. Unruptured Intracranial Aneurysms:

    PubMed Central

    Raymond, J.; Nguyen, T.; Chagnon, M.; Gevry, G.

    2007-01-01

    'if a man will begin with certainties, he shall end in doubts; 'but if he will be content to begin with doubts he shall end in certainties'. Sir Francis Bacon, The Advancement of Learning Summary In the absence of level one evidence, the treatment of unruptured intracranial aneurysms is grounded on opinions. Results of the largest registry available, ISUIA (the International Study on Unruptured Intraacranial Aneurysms) suggest that surgical or endovascular treatments are rarely justified. Yet the unruptured aneurysm is the most frequent indication for treatment in many endovascular centres. In preparation for the initiation of a randomized trial, we aimed at a better knowledge of endovascular expert opinions on unruptured aneurysms. We administered a standard questionnaire to 175 endovascular experts gathered at the WFITN meeting in Val d'lsère in 2007. Four paradigm unruptured aneurysms were used to poll opinions on risks of treatment or observation, as well as on their willingness to treat, observe or propose to the patient participation in a randomized trial, using six questions for each aneurysm. Opinions varied widely among lesions and among participants. Most participants (92.5%) were consistent, as they would offer treatment only if their estimate of the ten-year risk of spontaneous hemorrhage would exceed risks of treatment. Estimates of the natural history were consistently higher than that reported by ISUIA. Conversely, treatment risks were underestimated compared to those reported in ISUIA, but within the range reported in a recent French registry (ATENA). Participants were more confident in their evaluation of treatment risks and in their skills at treating aneurysms than in their estimates of risks of rupture entailed by the presence of the lesion, the latter being anchored at or close to 1% /year. The gulf between expert opinions, clinical practices and available data from registries persist. Expert opinions are compatible with the primary hypothesis

  20. A study of the hemodynamics of anterior communicating artery aneurysms

    NASA Astrophysics Data System (ADS)

    Cebral, Juan R.; Castro, Marcelo A.; Putman, Christopher M.

    2006-03-01

    In this study, the effects of unequal physiologic flow conditions in the internal carotid arteries on the intra-aneurysmal hemodynamics of anterior communicating artery aneurysms were investigated. Patient-specific vascular computational fluid dynamics models of five cerebral aneurysms were constructed from bilateral 3D rotational angiography images. The aneurysmal hemodynamics was analyzed under a range of physiologic flow conditions including the effects of unequal mean flows and phase shifts between the flow waveforms of the left and right internal carotid arteries. A total of five simulations were performed for each patient, and unsteady wall shear stress (WSS) maps were created for each flow condition. Time dependent curves of average WSS magnitude over selected regions on the aneurysms were constructed and used to analyze the influence of the inflow conditions. It was found that mean flow imbalances in the feeding vessels tend to shift the regions of elevated WSS (flow impingement region) towards the dominating inflow jet and to change the magnitude of the WSS peaks. However, the overall qualitative appearance of the WSS distribution and velocity simulations is not substantially affected. In contrast, phase differences tend to increase the temporal complexity of the hemodynamic patterns and to destabilize the intra-aneurysmal flow pattern. However, these effects are less important when the A1 confluence is less symmetric, i.e. dominated by one of the A1 segments. Conditions affecting the flow characteristics in the parent arteries of cerebral aneurysms with more than one avenue of inflow should be incorporated into flow models.

  1. Aneurysmal Neck Clipping as the Primary Treatment Option for Both Ruptured and Unruptured Middle Cerebral Artery Aneurysms

    PubMed Central

    Choi, Jai Ho; Park, Jung Eon; Kim, Myeong Jin; Kim, Bum Su

    2016-01-01

    Objective Although middle cerebral artery (MCA) aneurysms are less amenable to coil embolization, an increasing number of studies support favorable endovascular treatment for them. The purpose of this study is to compare the outcomes of two different treatments (surgery versus coiling) and evaluate the benefits of surgical clipping for MCA aneurysms. Methods Here we retrospectively analyzed the outcomes of 178 ruptured and unruptured MCA aneurysms treated in patients between September 2008 and April 2012. Parameters assessing treatment outcomes include degree of aneurysm occlusion, presence of regrowth, clinical status, and complications. Results Among 178 MCA aneurysms, 153 were treated surgically. After a mean follow-up of 12 months, the surgery group showed a clinically significant complete occlusion rate (98%) compared with the coiling group (56%) (p<0.001). Follow-up radiologic evaluation showed a higher regrowth rate (four of 16 cases) in the coiling group than in the surgery group (one of 49 cases) (p=0.003). There was no statistically significant difference in favorable clinical outcome rate between the two groups. The procedure-related permanent morbidity and mortality rates were 2% (three of 153 cases) in the surgery group and 0% (0 of 25 cases) in the coiling group. Conclusion Compared to endovascular treatment, surgical neck clipping for both ruptured and unruptured MCA aneurysms results in a significantly higher complete obliteration rate and less regrowth. Therefore, even in this endovascular era, we still recommend surgical clipping as the primary treatment option for MCA aneurysms rather than coil embolization. PMID:27226859

  2. Verminous aneurysm caused by filaria.

    PubMed

    Toledo, F V; de Araújo, A P; da Cunha, A M; Sidow, J R; Pavão, S G; de Araújo, E D

    1983-06-01

    Aneurysms caused by atherosclerosis are relatively frequent, as a consequence of the high incidence of this degenerative disease of the arteries. Other types of aneurysm, for example, those of infectious etiology, are more uncommon. Bacterias and fungi are able to cause aneurysms in several parts of the arterial tree. Stengel et al (1943), in a review of world literature described 217 cases of mycotic aneurysms. The Stedman's Medical Dictionary refers to a special type of aneurysm observed in horses, caused by intra-vascular migration of a worm, the Strongylus vulgaris. It has been named verminous aneurysm and generally involves the mesenteric arteries. We haven't found in medical literature any similar observations refering to human cases. The purpose of this paper is to describe a case of aneurysm the etiology of which we have imputed to the filaria (Wuchereria bancrofti). This case was observed in Marcilio Dias Naval Hospital, Rio de Janeiro, Brazil. PMID:6346961

  3. Long Telomeres in Blood Leukocytes Are Associated with a High Risk of Ascending Aortic Aneurysm

    PubMed Central

    Huusko, Tuija J.; Santaniemi, Merja; Kakko, Sakari; Taskinen, Panu; Ukkola, Olavi; Kesäniemi, Y. Antero; Savolainen, Markku J.; Salonurmi, Tuire

    2012-01-01

    Ascending aortic aneurysm is a connective tissue disorder. Even though multiple novel gene mutations have been identified, risk profiling and diagnosis before rupture still represent a challenge. There are studies demonstrating shorter telomere lengths in the blood leukocytes of abdominal aortic aneurysm patients. The aim of this study was to measure whether relative telomere lengths are changed in the blood leukocytes of ascending aortic aneurysm patients. We also studied the expression of telomerase in aortic tissue samples of ascending aortic aneurysms. Relative lengths of leukocyte telomeres were determined from blood samples of patients with ascending aortic aneurysms and compared with healthy controls. Telomerase expression, both at the level of mRNA and protein, was quantified from the aortic tissue samples. Mean relative telomere length was significantly longer in ascending aortic aneurysm blood samples compared with controls (T/S ratio 0.87 vs. 0.61, p<0.001). Expressions of telomerase mRNA and protein were elevated in the aortic aneurysm samples (p<0.05 and p<0.01). Our study reveals a significant difference in the mean length of blood leukocyte telomeres in ascending aortic aneurysm and controls. Furthermore, expression of telomerase, the main compensating factor for telomere loss, is elevated at both the mRNA and protein level in the samples of aneurysmal aorta. Further studies will be needed to confirm if this change in telomere length can serve as a tool for assessing the risk of ascending aortic aneurysm. PMID:23209831

  4. Endovascular Management of Ruptured Pancreaticoduodenal Artery Aneurysms Associated with Celiac Axis Stenosis

    SciTech Connect

    Suzuki, Kojiro Tachi, Yasushi; Ito, Shinji; Maruyama, Kunihiro; Mori, Yoshine; Komada, Tomohiro; Matsushima, Masaya; Ota, Toyohiro; Naganawa, Shinji

    2008-11-15

    The purpose of this study was to assess the efficacy of transcatheter arterial embolization for ruptured pancreaticoduodenal artery (PDA) aneurysms associated with celiac axis stenosis (CS). Seven patients (four men and three women; mean age, 64; range, 43-84) were treated with transcatheter arterial embolization between 2002 and 2007. They were analyzed with regard to the clinical presentation, radiological finding, procedure, and outcome. All patients presented with sudden epigastric pain or abdominal discomfort. Contrast-enhanced CT showed a small aneurysm and retroperitoneal hematoma around the pancreatic head in all patients. The aneurysms ranged from 0.3 to 0.9 cm in size. In one patient, two aneurysms were detected. The aneurysms were located in the pancreaticoduodenal artery (n = 5) and the dorsal pancreatic artery (n = 3). Embolization was performed with microcoils in all aneurysms (n = 8). N-Butyl 2-cyanoacrylate (n = 1) and gelatine particle (n = 1) were also used. Complete occlusion was achieved in four patients. In the other three patients, a significantly reduced flow to the aneurysm remained at final angiography. However, these aneurysms were thrombosed on follow-up CT within 2 weeks. And there was no recurrence of the symptoms and bleeding during follow-up (mean, 28 months; range, 5-65 months) in all patients. In conclusion, transcatheter arterial embolization for PDA aneurysms associated with CS is effective. Significant reduction of the flow to the aneurysm at final angiography may be predictive of future thrombosis.

  5. Virtual Treatment of Basilar Aneurysms Using Shape Memory Polymer Foam

    NASA Astrophysics Data System (ADS)

    Ortega, J. M.; Hartman, J.; Rodriguez, J. N.; Maitland, D. J.

    2012-11-01

    Numerical simulations are performed on patient-specific basilar aneurysms that are treated with shape memory polymer (SMP) foam. In order to assess the post-treatment hemodynamics, two modeling approaches are employed. In the first, the foam geometry is obtained from a micro-CT scan and the pulsatile blood flow within the foam is simulated for both Newtonian and non-Newtonian viscosity models. In the second, the foam is represented as a porous media continuum, which has permeability properties that are determined by computing the pressure gradient through the foam geometry over a range of flow speeds comparable to those of in vivo conditions. Virtual angiography and additional post-processing demonstrate that the SMP foam significantly reduces the blood flow speed within the treated aneurysms, while eliminating the high-frequency velocity fluctuations that are present prior to treatment. A prediction of the initial locations of thrombus formation throughout the SMP foam is obtained by means of a low fidelity thrombosis model that is based upon the residence time and shear rate of blood. The two modeling approaches capture similar qualitative trends for the initial locations of thrombus within the SMP foam.

  6. The Effect of Hemodynamics on Cerebral Aneurysm Morphology

    NASA Astrophysics Data System (ADS)

    Metcalfe, Ralph; Mantha, Aishwarya; Karmonik, Christof; Strother, Charles

    2004-11-01

    One of the difficulties in applying principles of hemodynamics to the study of blood flow in aneurysms are the drastic variations in possible shape of both the aneurysms and the parent arteries in the region of interest. We have taken data from three para-opthalmic internal carotid artery aneurysms using 3D-digital subtraction angiography (3D-DSA) and performed CFD simulations of steady and unsteady flows through the three different cases using the same pressure gradients and pulsatile flow waveforms (based on the Ku model for flow through the Carotid bifurcation). We have found that the total pressure differential within the aneurysms is consistent with the direction of flow, and that the dynamic pressure gradient within the aneurysm is very small compared with the static pressure variations. Wall shear stresses were highest near regions of sharp arterial curvature, but always remained low inside the aneurysm. These results suggest a more complex role for hemodynamics in aneurysm generation, growth and rupture.

  7. Computer Simulation of Flow Dynamics in Paraclinoidal Aneurysms

    PubMed Central

    Kobayashi, N.; Miyachi, S.; Okamoto, T.; Kojima, T.; Hattori, K.; Qian, S.; Takeda, H.; Yoshida, J.

    2005-01-01

    Summary Endovascular treatment, which is very useful method especially for paraclinoidal aneurysms, has the limitations of coil compaction and recanalization, which are difficult to predict. We tried to understand flow dynamic features, one of the important factors of such problems, using computer flow dynamics (CFD) simulations. CFD simulations were made in paraclinoidal aneurysm model of different size and protruded directions. Flow patterns, flow velocities and pressure are analyzed. Although the pressure on the aneurismal orifice is highest in the aneurysm protruding vertically upward, the flow velocity is highest in the superior-medial protruding one. Significant difference is not observed in either flow patterns, flow velocities or pressures on the aneurismal orifices between the sizes of aneurismal sac. Among paraclinoidal aneurysms, an aneurysm protruding to superior-medially receives the most severe haemodynamic stresses at the orifice and the aneurysm size does not cause significant differences in the aspect of flow dynamics. It should be considered in the treatment of such aneurysms. PMID:20584475

  8. Aneurysmal Subarachnoid Hemorrhage and Neuroinflammation: A Comprehensive Review

    PubMed Central

    Lucke-Wold, Brandon P.; Logsdon, Aric F.; Manoranjan, Branavan; Turner, Ryan C.; McConnell, Evan; Vates, George Edward; Huber, Jason D.; Rosen, Charles L.; Simard, J. Marc

    2016-01-01

    Aneurysmal subarachnoid hemorrhage (SAH) can lead to devastating outcomes including vasospasm, cognitive decline, and even death. Currently, treatment options are limited for this potentially life threatening injury. Recent evidence suggests that neuroinflammation plays a critical role in injury expansion and brain damage. Red blood cell breakdown products can lead to the release of inflammatory cytokines that trigger vasospasm and tissue injury. Preclinical models have been used successfully to improve understanding about neuroinflammation following aneurysmal rupture. The focus of this review is to provide an overview of how neuroinflammation relates to secondary outcomes such as vasospasm after aneurysmal rupture and to critically discuss pharmaceutical agents that warrant further investigation for the treatment of subarachnoid hemorrhage. We provide a concise overview of the neuroinflammatory pathways that are upregulated following aneurysmal rupture and how these pathways correlate to long-term outcomes. Treatment of aneurysm rupture is limited and few pharmaceutical drugs are available. Through improved understanding of biochemical mechanisms of injury, novel treatment solutions are being developed that target neuroinflammation. In the final sections of this review, we highlight a few of these novel treatment approaches and emphasize why targeting neuroinflammation following aneurysmal subarachnoid hemorrhage may improve patient care. We encourage ongoing research into the pathophysiology of aneurysmal subarachnoid hemorrhage, especially in regards to neuroinflammatory cascades and the translation to randomized clinical trials. PMID:27049383

  9. Computational study of anterior communicating artery hemodynamics before aneurysm formation

    NASA Astrophysics Data System (ADS)

    Castro, Marcelo A.; Putman, Christopher M.; Cebral, Juan R.

    2012-03-01

    It is widely accepted that complexity in the flow pattern at the anterior communicating artery (AComA) is associated with the high rate of aneurysm formation in that location observed in large studies. A previous computational hemodynamic study showed a possible association between high maximum intraaneurysmal wall shear stress (WSS) at the systolic peak with rupture in a cohort of AComA aneurysms. In another study it was observed a connection between location of aneurysm blebs and regions of high WSS in models where blebs were virtually removed. However, others reported associations between low WSS and either rupture or blister formation. The purpose of this work is to study associations between hemodynamic patterns and AComA aneurysm initiation by comparing hemodynamics in the aneurysm and the normal model where the aneurysm was computationally removed. Vascular models of both right and left circulation were independently reconstructed from three-dimensional rotational angiography images using deformable models, and fused using a surface merging algorithm. The geometric models were then used to generate high-quality volumetric finite element grids of tetrahedra with an advancing front technique. For each patient, the second anatomical model was created by digitally removing the aneurysm. It was iteratively achieved by applying a Laplacian smoothing filter and remeshing the surface. Finite element blood flow numerical simulations were performed. It was observed that aneurysms initiated in regions of high and moderate WSS in the counterpart normal models. Adjacent or close to those regions, low WSS portions of the arterial wall were not affected by the disease.

  10. The Endovascular Management of Iliac Artery Aneurysms

    SciTech Connect

    Stroumpouli, Evangelia; Nassef, Ahmed; Loosemore, Tom; Thompson, Matt; Morgan, Robert; Belli, Anna-Maria

    2007-11-15

    Background: Isolated aneurysms of the iliac arteries are uncommon. Previously treated by conventional surgery, there is increasing use of endografts to treat these lesions. Purpose: The purpose of this study was to assess the efficacy, safety, and durability of the stent-grafts for treatment of iliac artery aneurysms (IAAs). The results of endografting for isolated IAAs over a 10-year period were analyzed retrospectively. The treatment methods differed depending on the anatomic location of the aneurysms. Twenty-one patients (1 woman, 20 men) underwent endovascular stent-graft repair, with one procedure carried out under emergency conditions after acute rupture. The mean aneurysm diameter was 4.6 cm.Results:The procedural technical success was 100%. There was zero 30-day mortality. Follow-up was by interval CT scans. At a mean follow-up of 51.2 months, the stent-graft patency rate was 100%. Reintervention was performed in four patients (19%): one patient (4.7%) with a type I endoleak and three patients (14.3%) with type II endoleaks.Conclusion:We conclude that endovascular repair of isolated IAAs is a safe, minimally invasive technique with low morbidity rates. Follow-up results up to 10 years suggest that this approach is durable and should be regarded as a first treatment option for appropriate candidates.

  11. Incremental value of live/real time three-dimensional transesophageal echocardiography over the two-dimensional technique in the assessment of sinus of valsalva aneurysm rupture.

    PubMed

    Raslan, Saleem; Nanda, Navin C; Lloyd, Lancelot; Khairnar, Prakash; Reilly, Stephanie D; Holman, William L

    2011-09-01

    We present an adult patient with rupture of the right sinus of Valsalva aneurysm in whom the two-dimensional transesophageal echocardiogram failed to show the rupture. On the other hand, live/real time three-dimensional transesophageal echocardiography clearly delineated the site of rupture into the pericardium and mediastinum. PMID:21827544

  12. Pulsatile blood flow in Abdominal Aortic Aneurysms

    NASA Astrophysics Data System (ADS)

    Salsac, Anne-Virginie; Lasheras, Juan C.; Singel, Soeren; Varga, Chris

    2001-11-01

    We discuss the results of combined in-vitro laboratory measurements and clinical observations aimed at determining the effect that the unsteady wall shear stresses and the pressure may have on the growth and eventual rupturing of an Abdominal Aortic Aneurysm (AAA), a permanent bulging-like dilatation occurring near the aortic bifurcation. In recent years, new non-invasive techniques, such as stenting, have been used to treat these AAAs. However, the development of these implants, aimed at stopping the growth of the aneurysm, has been hampered by the lack of understanding of the effect that the hemodynamic forces have on the growth mechanism. Since current in-vivo measuring techniques lack the precision and the necessary resolution, we have performed measurements of the pressure and shear stresses in laboratory models. The models of the AAA were obtained from high resolution three-dimensional CAT/SCANS performed in patients at early stages of the disease. Preliminary DPIV measurements show that the pulsatile blood flow discharging into the cavity of the aneurysm leads to large spikes of pressure and wall shear stresses near and around its distal end, indicating a possible correlation between the regions of high wall shear stresses and the observed location of the growth of the aneurysm.

  13. Anesthetic considerations for endovascular abdominal aortic aneurysm repair

    PubMed Central

    Kothandan, Harikrishnan; Haw Chieh, Geoffrey Liew; Khan, Shariq Ali; Karthekeyan, Ranjith Baskar; Sharad, Shah Shitalkumar

    2016-01-01

    Aneurysm is defined as a localized and permanent dilatation with an increase in normal diameter by more than 50%. It is more common in males and can affect up to 8% of elderly men. Smoking is the greatest risk factor for abdominal aortic aneurysm (AAA) and other risk factors include hypertension, hyperlipidemia, family history of aneurysms, inflammatory vasculitis, and trauma. Endovascular Aneurysm Repair [EVAR] is a common procedure performed for AAA, because of its minimal invasiveness as compared with open surgical repair. Patients undergoing EVAR have a greater incidence of major co-morbidities and should undergo comprehensive preoperative assessment and optimization within the multidisciplinary settings. In majority of cases, EVAR is extremely well-tolerated. The aim of this article is to outline the Anesthetic considerations related to EVAR. PMID:26750684

  14. Abdominal aortic aneurysm repair - open - discharge

    MedlinePlus

    AAA - open - discharge; Repair - aortic aneurysm - open - discharge ... You had open aortic aneurysm surgery to repair an aneurysm (a widened part) in your aorta, the large artery that carries blood to your ...

  15. Interleukin-6 as a Prognostic Biomarker in Ruptured Intracranial Aneurysms

    PubMed Central

    Kao, Hung-Wen; Kuo, Chen-Ling; Huang, Ching-Shan; Tseng, Wan-Min; Lin, Ching-Po

    2015-01-01

    Background Interleukin-6 (IL-6), a proinflammatory cytokine, was found to surge in the cerebral spinal fluid after aneurysmal subarachnoid hemorrhage (SAH). We hypothesized that the plasma level of IL-6 could be an independent biomarker in predicting clinical outcome of patients with ruptured intracranial aneurysm. Methods We prospectively included 53 consecutive patients treated with platinum coil embolization of the ruptured intracranial aneurysm. Plasma IL-6 levels were measured in the blood samples at the orifices of the aneurysms and from peripheral veins. The outcome measure was the modified Rankin Scale one month after SAH. Multiple logistic regression analyses were used to evaluate the associations between the plasma IL-6 levels and the neurological outcome. Results Significant risk factors for the poor outcome were old age, low Glasgow Coma Scale (GCS) on day 0, high Fisher grades, and high aneurysmal and venous IL-6 levels in univariate analyses. Aneurysmal IL-6 levels showed modest to moderate correlations with GCS on day 0, vasospasm grade and Fisher grade. A strong correlation was found between the aneurysmal and the corresponding venous IL-6 levels (ρ = 0.721; P<0.001). In the multiple logistic regression models, the poor 30-day mRS was significantly associated with high aneurysmal IL-6 level (OR, 17.97; 95% CI, 1.51–214.33; P = 0.022) and marginally associated with high venous IL-6 level (OR, 12.71; 95% CI, 0.90–180.35; P = 0.022) after adjusting for dichotomized age, GCS on day 0, and vasospasm and Fisher grades. Conclusions The plasma level of IL-6 is an independent prognostic biomarker that could be used to aid in the identification of patients at high-risk of poor neurological outcome after rupture of the intracranial aneurysm. PMID:26176774

  16. Morphological and Hemodynamic Analysis of Mirror Posterior Communicating Artery Aneurysms

    PubMed Central

    Wu, Xi; Wu, Yongfa; Jiang, Che; Wang, Shengzhang; Huang, Qinghai; Liu, Jianmin

    2013-01-01

    Background and Purpose Hemodynamic factors are commonly believed to play an important role in the pathogenesis, progression, and rupture of cerebral aneurysms. In this study, we aimed to identify significant hemodynamic and morphological parameters that discriminate intracranial aneurysm rupture status using 3-dimensional-angiography and computational fluid dynamics technology. Materials and Methods 3D-DSA was performed in 8 patients with mirror posterior communicating artery aneurysms (Pcom-MANs). Each pair was divided into ruptured and unruptured groups. Five morphological and three hemodynamic parameters were evaluated for significance with respect to rupture. Results The normalized mean wall shear stress (WSS) of the aneurysm sac in the ruptured group was significantly lower than that in the unruptured group (0.52±0.20 versus 0.81±0.21, P = .012). The percentage of the low WSS area in the ruptured group was higher than that in the unruptured group (4.11±4.66% versus 0.02±0.06%, P = .018). The AR was 1.04±0.21 in the ruptured group, which was significantly higher than 0.70±0.17 in the unruptured group (P = .012). By contrast, parameters that had no significant differences between the two groups were OSI (P = .674), aneurysm size (P = .327), size ratio (P = .779), vessel angle (P = 1.000) and aneurysm inclination angle (P = 1.000). Conclusions Pcom-MANs may be a useful disease model to investigate possible causes of aneurysm rupture. The ruptured aneurysms manifested lower WSS, higher percentage of low WSS area, and higher AR, compared with the unruptured one. And hemodynamics is as important as morphology in discriminating aneurysm rupture status. PMID:23383184

  17. Complications in the Treatment of Intracranial Aneurysms with Silk Stents: an Analysis of 30 Consecutive Patients

    PubMed Central

    Cirillo, L.; Leonardi, M.; Dall’olio, M.; Princiotta, C.; Stafa, A.; Simonetti, L.; Toni, F.; Agati, R.

    2012-01-01

    Summary Flow-diverting stents (Silk and PED) have radically changed the approach to intracranial aneurysm treatment from the use of endosaccular materials to use of an extraaneurysmal endoluminal device. However, much debate surrounds the most appropriate indications for the use of FD stents and the problems raised by several possible complications. We analysed our technical difficulties and the early (less than ten days after treatment) and late complications encountered in 30 aneurysms treated comprising 13 giant lesions, 12 large, five with maximum diameters <10 mm and one blister-like aneurysm. In our experience the primary indications for the use of FD stents can be the symptomatic intracavernous giant aneurysms. Although the extracavernous carotid siphon aneurysms have major risk of bleeding, FD stents are indicated clearly explaining the risks to the patient in case of severe mass effect. There is a very complex assessment for aneurysms of the vertebrobasilar circulation. PMID:23217636

  18. The effect of inlet waveforms on computational hemodynamics of patient-specific intracranial aneurysms.

    PubMed

    Xiang, J; Siddiqui, A H; Meng, H

    2014-12-18

    Due to the lack of patient-specific inlet flow waveform measurements, most computational fluid dynamics (CFD) simulations of intracranial aneurysms usually employ waveforms that are not patient-specific as inlet boundary conditions for the computational model. The current study examined how this assumption affects the predicted hemodynamics in patient-specific aneurysm geometries. We examined wall shear stress (WSS) and oscillatory shear index (OSI), the two most widely studied hemodynamic quantities that have been shown to predict aneurysm rupture, as well as maximal WSS (MWSS), energy loss (EL) and pressure loss coefficient (PLc). Sixteen pulsatile CFD simulations were carried out on four typical saccular aneurysms using 4 different waveforms and an identical inflow rate as inlet boundary conditions. Our results demonstrated that under the same mean inflow rate, different waveforms produced almost identical WSS distributions and WSS magnitudes, similar OSI distributions but drastically different OSI magnitudes. The OSI magnitude is correlated with the pulsatility index of the waveform. Furthermore, there is a linear relationship between aneurysm-averaged OSI values calculated from one waveform and those calculated from another waveform. In addition, different waveforms produced similar MWSS, EL and PLc in each aneurysm. In conclusion, inlet waveform has minimal effects on WSS, OSI distribution, MWSS, EL and PLc and a strong effect on OSI magnitude, but aneurysm-averaged OSI from different waveforms has a strong linear correlation with each other across different aneurysms, indicating that for the same aneurysm cohort, different waveforms can consistently stratify (rank) OSI of aneurysms. PMID:25446264

  19. Morphological and Hemodynamic Discriminators for Rupture Status in Posterior Communicating Artery Aneurysms

    PubMed Central

    Karmonik, Christof; Fang, Yibin; Xu, Jinyu; Yu, Ying; Cao, Wei; Liu, Jianmin; Huang, Qinghai

    2016-01-01

    Background and Purpose The conflicting findings of previous morphological and hemodynamic studies on intracranial aneurysm rupture may be caused by the relatively small sample sizes and the variation in location of the patient-specific aneurysm models. We aimed to determine the discriminators for aneurysm rupture status by focusing on only posterior communicating artery (PCoA) aneurysms. Materials and Methods In 129 PCoA aneurysms (85 ruptured, 44 unruptured), clinical, morphological and hemodynamic characteristics were compared between the ruptured and unruptured cases. Multivariate logistic regression analysis was performed to determine the discriminators for rupture status of PCoA aneurysms. Results While univariate analyses showed that the size of aneurysm dome, aspect ratio (AR), size ratio (SR), dome-to-neck ratio (DN), inflow angle (IA), normalized wall shear stress (NWSS) and percentage of low wall shear stress area (LSA) were significantly associated with PCoA aneurysm rupture status. With multivariate analyses, significance was only retained for higher IA (OR = 1.539, p < 0.001) and LSA (OR = 1.393, p = 0.041). Conclusions Hemodynamics and morphology were related to rupture status of intracranial aneurysms. Higher IA and LSA were identified as discriminators for rupture status of PCoA aneurysms. PMID:26910518

  20. The Effect of Inlet Waveforms on Computational Hemodynamics of Patient-Specific Intracranial Aneurysms

    PubMed Central

    Xiang, J.; Siddiqui, A.H.; Meng, H.

    2014-01-01

    Due to the lack of patient-specific inlet flow waveform measurements, most computational fluid dynamics (CFD) simulations of intracranial aneurysms usually employ waveforms that are not patient-specific as inlet boundary conditions for the computational model. The current study examined how this assumption affects the predicted hemodynamics in patient-specific aneurysm geometries. We examined wall shear stress (WSS) and oscillatory shear index (OSI), the two most widely studied hemodynamic quantities that have been shown to predict aneurysm rupture, as well as maximal WSS (MWSS), energy loss (EL) and pressure loss coefficient (PLc). Sixteen pulsatile CFD simulations were carried out on four typical saccular aneurysms using 4 different waveforms and an identical inflow rate as inlet boundary conditions. Our results demonstrated that under the same mean inflow rate, different waveforms produced almost identical WSS distributions and WSS magnitudes, similar OSI distributions but drastically different OSI magnitudes. The OSI magnitude is correlated with the pulsatility index of the waveform. Furthermore, there is a linear relationship between aneurysm-averaged OSI values calculated from one waveform and those calculated from another waveform. In addition, different waveforms produced similar MWSS, EL and PLc in each aneurysm. In conclusion, inlet waveform has minimal effects on WSS, OSI distribution, MWSS, EL and PLc and a strong effect on OSI magnitude, but aneurysm-averaged OSI from different waveforms has a strong linear correlation with each other across different aneurysms, indicating that for the same aneurysm cohort, different waveforms can consistently stratify (rank) OSI of aneurysms. PMID:25446264

  1. MULTIMEDIA EXPOSURE ASSESSMENT MODEL (MULTIMED)

    EPA Science Inventory

    The Multimedia Exposure Assessment Model (MULTIMED) for exposure assessment simulates the movement of contaminants leaching from a waste disposal facility. The model consists of a number of modules which predict concentrations at a receptor due to transport in the subsurface, sur...

  2. Alteration of Intra-Aneurysmal Hemodynamics for Flow Diversion Using Enterprise and Vision Stents

    PubMed Central

    Tremmel, Markus; Xiang, Jianping; Natarajan, Sabareesh K.; Hopkins, L. Nelson; Siddiqui, Adnan H.; Levy, Elad I.; Meng, Hui

    2010-01-01

    Objective Flow diversion is a novel concept for intracranial aneurysm treatment. The recently developed Enterprise Vascular Reconstruction Device (Codman Neurovascular, Raynham MA) provides easy delivery and repositioning. Although designed specifically for restraining coils within an aneurysm, this stent has theoretical effects on modifying flow dynamics, which have not been studied. The goal of this study was to quantify the effect of single and multiple self-expanding Enterprise stents alone or in combination with balloon-mounted stents on aneurysm hemodynamics using computational fluid dynamics (CFD). Methods The geometry of a wide-necked, saccular, basilar trunk aneurysm was reconstructed from computed tomographic angiography images. Various combinations of 1–3 stents were “virtually” conformed to fit into the vessel lumen and placed across the aneurysm orifice. CFD analysis was performed to calculate hemodynamic parameters considered important in aneurysm pathogenesis and thrombosis for each model. Results The complex aneurysmal flow pattern was suppressed by stenting. Stent placement lowered average flow velocity in the aneurysm; further reduction was achieved by additional stent deployment. Aneurysmal flow turnover time, an indicator of stasis, was increased to 114-117% for single-stent, 127-128% for double-stent, and 141% for triple-stent deployment. Furthermore, aneurysmal wall shear stress (WSS) decreased with increasing number of deployed stents. Conclusion This is the first study analyzing flow modifications associated with placement of Enterprise stents for aneurysm occlusion. Placement of 2-3 stents significantly reduced intra-aneurysmal hemodynamic activities, thereby increasing the likelihood of inducing aneurysm thrombotic occlusion. PMID:21197155

  3. Layer- and Direction-Specific Material Properties, Extreme Extensibility and Ultimate Material Strength of Human Abdominal Aorta and Aneurysm: A Uniaxial Extension Study.

    PubMed

    Teng, Zhongzhao; Feng, Jiaxuan; Zhang, Yongxue; Huang, Yuan; Sutcliffe, Michael P F; Brown, Adam J; Jing, Zaiping; Gillard, Jonathan H; Lu, Qingsheng

    2015-11-01

    Mechanical analysis has the potential to provide complementary information to aneurysm morphology in assessing its vulnerability. Reliable calculations require accurate material properties of individual aneurysmal components. Quantification of extreme extensibility and ultimate material strength of the tissue are important if rupture is to be modelled. Tissue pieces from 11 abdomen aortic aneurysm (AAA) from patients scheduled for elective surgery and from 8 normal aortic artery (NAA) from patients who scheduled for kidney/liver transplant were collected at surgery and banked in liquid nitrogen with the use of Cryoprotectant solution to minimize frozen damage. Prior to testing, specimen were thawed and longitudinal and circumferential tissue strips were cut from each piece and adventitia, media and thrombus if presented were isolated for the material test. The incremental Young's modulus of adventitia of NAA was direction-dependent at low stretch levels, but not the media. Both adventitia and media had a similar extreme extensibility in the circumferential direction, but the adventitia was much stronger. For aneurysmal tissues, no significant differences were found when the incremental moduli of adventitia, media or thrombus in both directions were compared. Adventitia and media from AAA had similar extreme extensibility and ultimate strength in both directions and thrombus was the weakest material. Adventitia and media from AAA were less extensible compared with those of NAA, but the ultimate strength remained similar. The material properties, including extreme extensibility and ultimate strength, of both healthy aortic and aneurysmal tissues were layer-dependent, but not direction-dependent. PMID:25905688

  4. Hemodynamic Influences on Abdominal Aortic Aneurysm Disease: Application of Biomechanics to Aneurysm Pathophysiology

    PubMed Central

    Dua, Monica M.; Dalman, Ronald L.

    2010-01-01

    “Atherosclerotic” abdominal aortic aneurysms (AAAs) occur with the greatest frequency in the distal aorta. The unique hemodynamic environment of this area predisposes it to site-specific degenerative changes. In this review, we summarize the differential hemodynamic influences present along the length of the abdominal aorta, and demonstrate how alterations in aortic flow and wall shear stress modify AAA progression in experimental models. Improved understanding of aortic hemodynamic risk profiles provides an opportunity to modify patient activity patterns to minimize risk of aneurysmal degeneration. PMID:20347049

  5. MicroRNAs, fibrotic remodeling, and aortic aneurysms.

    PubMed

    Milewicz, Dianna M

    2012-02-01

    Aortic aneurysms are a common clinical condition that can cause death due to aortic dissection or rupture. The association between aortic aneurysm pathogenesis and altered TGF-β signaling has been the subject of numerous investigations. Recently, a TGF-β-responsive microRNA (miR), miR-29, has been identified to play a role in cellular phenotypic modulation during aortic development and aging. In this issue of JCI, Maegdefessel and colleagues demonstrate that decreasing the levels of miR-29b in the aortic wall can attenuate aortic aneurysm progression in two different mouse models of abdominal aortic aneurysms. This study highlights the relevance of miR-29b in aortic disease but also raises questions about its specific role. PMID:22269322

  6. Image-based analysis of blood flow modification in stented aneurysms

    NASA Astrophysics Data System (ADS)

    Cebral, Juan; Mut, Fernando; Appanaboyina, Sunil; Löhner, Rainald; Miranda, Carlos; Escrivano, Esteban; Lylyk, Pedro; Putman, Christopher

    2009-02-01

    Currently there is increased interest in the use of stents as flow diverters for the treatment of intracranial aneurysms, especially wide necked aneurysms that are difficult to treat by coil embolization or surgical clipping. This paper presents image-based patient-specific computational models of the hemodynamics in cerebral aneurysms before and after treatment with a stent alone, with the goal of better understanding the hemodynamic effects of these devices and their relation to the outcome of the procedures. Stenting of cerebral aneurysms is a feasible endovascular treatment option for aneurysms with wide necks that are difficult to treat with coils or by surgical clipping. However, this requires stents that are capable of substantially modifying the intra-aneurysmal flow pattern in order to cause thrombosis of the aneurysm. The results presented in this paper show that the studied stent was able to change significantly the hemodynamic characteristics of the aneurysm. In addition, it was shown that patient-specific computational models constructed from medical images are capable of realistically representing the in vivo hemodynamic characteristics observed during conventional angiography examinations before and after stenting. This indicates that these models can be used to better understand the effects of different stent designs and to predict the alteration in the hemodynamic pattern of a given aneurysm produced by a given flow diverter. This is important for improving current design of flow diverting devices and patient treatment plans.

  7. Hemodynamic Study of Flow Remodeling Stent Graft for the Treatment of Highly Angulated Abdominal Aortic Aneurysm

    PubMed Central

    Yeow, Siang Lin; Leo, Hwa Liang

    2016-01-01

    This study investigates the effect of a novel flow remodeling stent graft (FRSG) on the hemodynamic characteristics in highly angulated abdominal aortic aneurysm based on computational fluid dynamics (CFD) approach. An idealized aortic aneurysm with varying aortic neck angulations was constructed and CFD simulations were performed on nonstented models and stented models with FRSG. The influence of FRSG intervention on the hemodynamic performance is analyzed and compared in terms of flow patterns, wall shear stress (WSS), and pressure distribution in the aneurysm. The findings showed that aortic neck angulations significantly influence the velocity flow field in nonstented models, with larger angulations shifting the mainstream blood flow towards the center of the aorta. By introducing FRSG treatment into the aneurysm, erratic flow recirculation pattern in the aneurysm sac diminishes while the average velocity magnitude in the aneurysm sac was reduced in the range of 39% to 53%. FRSG intervention protects the aneurysm against the impacts of high velocity concentrated flow and decreases wall shear stress by more than 50%. The simulation results highlighted that FRSG may effectively treat aneurysm with high aortic neck angulations via the mechanism of promoting thrombus formation and subsequently led to the resorption of the aneurysm. PMID:27247612

  8. Computational hemodynamic study of intracranial aneurysms coexistent with proximal artery stenosis

    NASA Astrophysics Data System (ADS)

    Castro, Marcelo A.; Peloc, Nora L.; Putman, Christopher M.; Cebral, Juan R.

    2012-03-01

    Intracranial aneurysms and artery stenosis are vascular diseases with different pathophysiological characteristics. However, although unusual, aneurysms may coexist in up to 5% of patients with stenotic plaque, according to a previous study. Another study showed that incidental detection of cerebral aneurysm in the same cerebral circulation as the stenotic plaque was less than 2%. Patients with concomitant carotid artery stenosis and unruptured intracranial aneurysms pose a difficult management decision for the physician. Case reports showed patients who died due to aneurysm rupture months after endarterectomy but before aneurysm clipping, while others did not show any change in the aneurysm after plaque removal, having optimum outcome after aneurysm coiling. The purpose of this study is to investigate the intraaneurysmal hemodynamic changes before and after treatment of stenotic plaque. Idealized models were constructed with different stenotic grade, distance and relative position to the aneurysm. Digital removal of the stenotic plaque was performed in the reconstructed model of a patient with both pathologies. Computational fluid dynamic simulations were performed using a finite element method approach. Blood velocity field and hemodynamic forces were recorded and analyzed. Changes in the flow patterns and wall shear stress values and distributions were observed in both ideal and image-based models. Detailed investigation of wall shear stress distributions in patients with both pathologies is required to make the best management decision.

  9. Maximum Diameter Measurements of Aortic Aneurysms on Axial CT Images After Endovascular Aneurysm Repair: Sufficient for Follow-up?

    SciTech Connect

    Baumueller, Stephan Nguyen, Thi Dan Linh Goetti, Robert Paul; Lachat, Mario; Seifert, Burkhardt; Pfammatter, Thomas Frauenfelder, Thomas

    2011-12-15

    Purpose: To assess the accuracy of maximum diameter measurements of aortic aneurysms after endovascular aneurysm repair (EVAR) on axial computed tomographic (CT) images in comparison to maximum diameter measurements perpendicular to the intravascular centerline for follow-up by using three-dimensional (3D) volume measurements as the reference standard. Materials and Methods: Forty-nine consecutive patients (73 {+-} 7.5 years, range 51-88 years), who underwent EVAR of an infrarenal aortic aneurysm were retrospectively included. Two blinded readers twice independently measured the maximum aneurysm diameter on axial CT images performed at discharge, and at 1 and 2 years after intervention. The maximum diameter perpendicular to the centerline was automatically measured. Volumes of the aortic aneurysms were calculated by dedicated semiautomated 3D segmentation software (3surgery, 3mensio, the Netherlands). Changes in diameter of 0.5 cm and in volume of 10% were considered clinically significant. Intra- and interobserver agreements were calculated by intraclass correlations (ICC) in a random effects analysis of variance. The two unidimensional measurement methods were correlated to the reference standard. Results: Intra- and interobserver agreements for maximum aneurysm diameter measurements were excellent (ICC = 0.98 and ICC = 0.96, respectively). There was an excellent correlation between maximum aneurysm diameters measured on axial CT images and 3D volume measurements (r = 0.93, P < 0.001) as well as between maximum diameter measurements perpendicular to the centerline and 3D volume measurements (r = 0.93, P < 0.001). Conclusion: Measurements of maximum aneurysm diameters on axial CT images are an accurate, reliable, and robust method for follow-up after EVAR and can be used in daily routine.

  10. Models of Personnel Needs Assessment.

    ERIC Educational Resources Information Center

    Mattson, Beverly

    This report presents samples of models and strategies for determining professional development needs of special education personnel. The following areas are covered: definitions of needs and the needs assessment process; personnel needs assessment regulations under the Comprehensive System of Personnel Development, the Individuals with…

  11. Fluid-structure interaction of a patient-specific abdominal aortic aneurysm treated with an endovascular stent-graft

    PubMed Central

    Molony, David S; Callanan, Anthony; Kavanagh, Eamon G; Walsh, Michael T; McGloughlin, Tim M

    2009-01-01

    Background Abdominal aortic aneurysms (AAA) are local dilatations of the infrarenal aorta. If left untreated they may rupture and lead to death. One form of treatment is the minimally invasive insertion of a stent-graft into the aneurysm. Despite this effective treatment aneurysms may occasionally continue to expand and this may eventually result in post-operative rupture of the aneurysm. Fluid-structure interaction (FSI) is a particularly useful tool for investigating aneurysm biomechanics as both the wall stresses and fluid forces can be examined. Methods Pre-op, Post-op and Follow-up models were reconstructed from CT scans of a single patient and FSI simulations were performed on each model. The FSI approach involved coupling Abaqus and Fluent via a third-party software - MpCCI. Aneurysm wall stress and compliance were investigated as well as the drag force acting on the stent-graft. Results Aneurysm wall stress was reduced from 0.38 MPa before surgery to a value of 0.03 MPa after insertion of the stent-graft. Higher stresses were seen in the aneurysm neck and iliac legs post-operatively. The compliance of the aneurysm was also reduced post-operatively. The peak Post-op axial drag force was found to be 4.85 N. This increased to 6.37 N in the Follow-up model. Conclusion In a patient-specific case peak aneurysm wall stress was reduced by 92%. Such a reduction in aneurysm wall stress may lead to shrinkage of the aneurysm over time. Hence, post-operative stress patterns may help in determining the likelihood of aneurysm shrinkage post EVAR. Post-operative remodelling of the aneurysm may lead to increased drag forces. PMID:19807909

  12. Bone marrow-derived endothelial progenitor cells are involved in aneurysm repair in rabbits.

    PubMed

    Fang, Xinggen; Zhao, Rui; Wang, Kuizhong; Li, Zifu; Yang, Penfei; Huang, Qinghai; Xu, Yi; Hong, Bo; Liu, Jianmin

    2012-09-01

    Endothelial progenitor cells (EPC) are believed to be involved in aneurysmal repair and remodeling. The aim of this study was to test this hypothesis and, if true, explore how EPC contribute to aneurysm repair in a rabbit model of elastase-induced carotid aneurysm. Rabbits were divided randomly into an in situ carotid EPC transfusion group (ISCT group, n=5), and an intravenous EPC transfusion group (IVT group, n=5). Autologous EPC were double-labeled with Hoechst 33342 and 5,6-carboxyfluorescein diacetate succinimidyl ester before injection into the animals in either the carotid artery (ISCT group) or marginal ear veins (IVT group). Three weeks later, labeled cells in the aneurysms were observed with respect to location, adhesion, and growth to detect signs of aneurysm repair. Labeled EPC were detected within the neointima in all five aneurysms in the ISCT group and in three of the five aneurysms in the IVT group, but there was no endothelial growth in the aneurysmal neointima in either group. These results show that bone marrow-derived EPC are involved in the process of aneurysm repair in this rabbit model. PMID:22789632

  13. An irreversible constitutive model for fibrous soft biological tissue: a 3-D microfiber approach with demonstrative application to abdominal aortic aneurysms.

    PubMed

    Christian Gasser, T

    2011-06-01

    Understanding the failure and damage mechanisms of soft biological tissue is critical to a sensitive and specific characterization of tissue injury tolerance and its relation to biological responses. Despite increasing experimental and analytical efforts, failure-related irreversible effects of soft biological tissue are still poorly understood. There is still no clear definition of what "damage" of a soft biological material is, and conventional macroscopic indicators, as known from damage of engineering materials for example, may not identify the tissue's tolerance to injury appropriately. To account for the complex three-dimensional arrangement of collagen, a microfiber model approach is applied, where constitutive relations for collagen fibers are integrated over the unit sphere, which in turn defines the tissue's macroscopic properties. A collagen fiber is represented by a bundle of proteoglycan cross-linked collagen fibrils that undergoes irreversible deformations when exceeding its elastic tensile limit. The proposed constitutive model is able to predict strain stiffening at physiological strain levels and does not exhibit a clear macroscopic elastic limit, two typical features known from soft biological tissue testing. An elastic-predictor/plastic-corrector implementation of the model is followed and constitutive parameters are estimated from in vitro test data from a particular abdominal aortic aneurysm (AAA). Damage-based structural instabilities of the AAA under different inflation conditions are investigated, where the collagen orientation density has been estimated from its in vivo stress state. PMID:21338718

  14. Decision Impact Assessment Model

    Energy Science and Technology Software Center (ESTSC)

    1991-08-01

    DIAMOND represents the decision-making environment that utility planners and executives face. Users interact with the model after every year or two of simulation, which provides an opportunity to modify past decisions as well as to make new decisions. For example, construction of a power plant can be started one year, and if circumstances change, the plant can be accelerated, mothballed, cancelled, or continued as originally planned. Similarly, the marketing and financial incentives for demand-side managementmore » programs can be changed from year to year. This frequent user interaction with the model, an operational game, should build greater understanding and insights among utility planners about the risks associated with different types of resources.« less

  15. The Assessment Cycle: A Model for Learning through Peer Assessment

    ERIC Educational Resources Information Center

    Reinholz, Daniel

    2016-01-01

    This paper advances a model describing how peer assessment supports self-assessment. Although prior research demonstrates that peer assessment promotes self-assessment, the connection between these two activities is underspecified. This model, the assessment cycle, draws from theories of self-assessment to elaborate how learning takes place…

  16. Intracranial aneurysm and sildenafil

    PubMed Central

    Edriss, Hawa; Nugent, Kenneth

    2016-01-01

    Sildenafil is one of the most commonly used drugs for the treatment of erectile dysfunction. To date, we found five reported cases of intracerebral bleeding and two reported cases of subarachnoid hemorrhage related to sildenafil use. We report a 49-year-old hypertensive and diabetic patient who presented with acute pulmonary edema and loss of consciousness following ingestion of 100 mg of sildenafil prior to sexual intercourse. He was not previously aware of the presence of an aneurysm and had no family history of it. Computed tomography of his head revealed a subarachnoid hemorrhage due to rupture of a saccular aneurysm with subsequent repeat hemorrhage within a few hours of presentation. A sudden increase in blood pressure led to pulmonary edema. Studies have shown that sildenafil acts on phosphodiesterase-1, -2 and -5 receptors and leads to a secondary increase in intracerebral circulation and vasodilatory effects, leading to sympathetic overactivity which increases the risk for intracranial bleeding. PMID:27034561

  17. Wall Mechanical Properties and Hemodynamics of Unruptured Intracranial Aneurysms

    PubMed Central

    Cebral, Juan R.; Duan, Xinjie; Chung, Bong Jae; Putman, Christopher; Aziz, Khaled; Robertson, Anne

    2016-01-01

    Purpose To investigate the relationship between the intra-aneurysmal hemodynamic conditions and the mechanical properties of the wall in human aneurysms. Methods A total of eight unruptured aneurysms were analyzed. Computational fluid dynamics (CFD) models were constructed from pre-operative 3D rotational angiography images. The aneurysms were clipped and the domes were resected and mechanically tested to failure with a uniaxial testing system under multi-photon microscopy. Linear regression analysis was performed to explore possible correlations between hemodynamic quantities and the failure characteristics and stiffness of the wall. Results The ultimate strain was negatively correlated to aneurysm inflow rate (p=0.021), mean velocity (p=0.025), and mean wall shear stress (p=0.039). It was also negatively correlated to inflow concentration, oscillatory shear index and measures of the complexity and instability of the flow; however these trends did not reach statistical significance. The wall stiffness at high strains was positively correlated to inflow rate (p=0.014), mean velocity (p=0.008), inflow concentration (p=0.04), flow instability (p=0.006), flow complexity (p=0.019), wall shear stress (p=0.002) and oscillatory shear index (p=0.004). Conclusions In a study of 8 unruptured intracranial aneurysms, ultimate strain is negatively correlated with aneurysm inflow rate, mean velocity and mean wall shear stress. Wall stiffness is positively correlated with aneurysm inflow rate, mean velocity, wall shear stress, flow complexity and stability, and oscillatory shear index. These trends and the impact of hemodynamics on wall structure and mechanical properties should be further investigated in larger studies. PMID:26228891

  18. The role of β-arrestin2-dependent signaling in thoracic aortic aneurysm formation in a murine model of Marfan syndrome.

    PubMed

    Wisler, James W; Harris, Emily M; Raisch, Michael; Mao, Lan; Kim, Jihee; Rockman, Howard A; Lefkowitz, Robert J

    2015-11-01

    Ang II type 1a receptor (AT1aR)-mediated activation of MAPKs contributes to thoracic aortic aneurysm (TAA) development in Marfan syndrome (MFS). β-Arrestin2 (βarr2) is known to mediate AT1aR-dependent MAPK activation, as well as proproliferative and profibrotic signaling in aortic vascular smooth muscle cells. Therefore, we investigated whether βarr2-dependent signaling contributes to TAA formation in MFS. We used a murine model of MFS [fibrillin (Fbn)(C1039G/+)] to generate an MFS murine model in combination with genetic βarr2 deletion (Fbn(C1039G/+)/βarr2(-/-)). Fbn(C1039G/+)/βarr2(-/-) mice displayed delayed aortic root dilation compared with Fbn(C1039G/+) mice. The mRNA and protein expression of several mediators of TAA formation, including matrix metalloproteinase (MMP)-2 and -9, was reduced in the aorta of Fbn(C1039G/+)/βarr2(-/-) mice relative to Fbn(C1039G/+) mice. Activation of ERK1/2 was also decreased in the aortas of Fbn(C1039G/+)/βarr2(-/-) mice compared with Fbn(C1039G/+) animals. Small interfering RNA targeting βarr2 inhibited angiotensin-stimulated expression of proaneurysmal signaling mediators in primary aortic root smooth muscle cells. Angiotensin-stimulated expression of the proaneurysmal signaling mediators MMP-2 and -9 was inhibited by blockade of ERK1/2 or the EGF receptor, whereas blockade of the transforming growth factor-β receptor had no effect. These results suggest that βarr2 contributes to TAA formation in MFS by regulating ERK1/2-dependent expression of proaneurysmal genes and proteins downstream of the AT1aR. Importantly, this demonstration of the unique signaling mechanism by which βarr2 contributes to aneurysm formation identifies multiple novel, potential therapeutic targets in MFS. PMID:26371162

  19. Design and biocompatibility of endovascular aneurysm filling devices

    DOE PAGESBeta

    Rodriguez, Jennifer N.; Hwang, Wonjun; Horn, John; Landsman, Todd L.; Boyle, Anthony; Wierzbicki, Mark A.; Hasan, Sayyeda M.; Follmer, Douglas; Bryant, Jesse; Small, Ward; et al

    2014-08-04

    We report that the rupture of an intracranial aneurysm, which can result in severe mental disabilities or death, affects approximately 30,000 people in the United States annually. The traditional surgical method of treating these arterial malformations involves a full craniotomy procedure, wherein a clip is placed around the aneurysm neck. In recent decades, research and device development have focused on new endovascular treatment methods to occlude the aneurysm void space. These methods, some of which are currently in clinical use, utilize metal, polymeric, or hybrid devices delivered via catheter to the aneurysm site. In this review, we present several suchmore » devices, including those that have been approved for clinical use, and some that are currently in development. We present several design requirements for a successful aneurysm filling device and discuss the success or failure of current and past technologies. Lastly, we also present novel polymeric based aneurysm filling methods that are currently being tested in animal models that could result in superior healing.« less

  20. Design and biocompatibility of endovascular aneurysm filling devices

    SciTech Connect

    Rodriguez, Jennifer N.; Hwang, Wonjun; Horn, John; Landsman, Todd L.; Boyle, Anthony; Wierzbicki, Mark A.; Hasan, Sayyeda M.; Follmer, Douglas; Bryant, Jesse; Small, Ward; Maitland, Duncan J.

    2014-08-04

    We report that the rupture of an intracranial aneurysm, which can result in severe mental disabilities or death, affects approximately 30,000 people in the United States annually. The traditional surgical method of treating these arterial malformations involves a full craniotomy procedure, wherein a clip is placed around the aneurysm neck. In recent decades, research and device development have focused on new endovascular treatment methods to occlude the aneurysm void space. These methods, some of which are currently in clinical use, utilize metal, polymeric, or hybrid devices delivered via catheter to the aneurysm site. In this review, we present several such devices, including those that have been approved for clinical use, and some that are currently in development. We present several design requirements for a successful aneurysm filling device and discuss the success or failure of current and past technologies. Lastly, we also present novel polymeric based aneurysm filling methods that are currently being tested in animal models that could result in superior healing.

  1. 21 CFR 882.5200 - Aneurysm clip.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Aneurysm clip. 882.5200 Section 882.5200 Food and... NEUROLOGICAL DEVICES Neurological Therapeutic Devices § 882.5200 Aneurysm clip. (a) Identification. An aneurysm clip is a device used to occlude an intracranial aneurysm (a balloonlike sac formed on a blood...

  2. 21 CFR 882.5200 - Aneurysm clip.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Aneurysm clip. 882.5200 Section 882.5200 Food and... NEUROLOGICAL DEVICES Neurological Therapeutic Devices § 882.5200 Aneurysm clip. (a) Identification. An aneurysm clip is a device used to occlude an intracranial aneurysm (a balloonlike sac formed on a blood...

  3. 21 CFR 882.5200 - Aneurysm clip.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Aneurysm clip. 882.5200 Section 882.5200 Food and... NEUROLOGICAL DEVICES Neurological Therapeutic Devices § 882.5200 Aneurysm clip. (a) Identification. An aneurysm clip is a device used to occlude an intracranial aneurysm (a balloonlike sac formed on a blood...

  4. 21 CFR 882.5200 - Aneurysm clip.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Aneurysm clip. 882.5200 Section 882.5200 Food and... NEUROLOGICAL DEVICES Neurological Therapeutic Devices § 882.5200 Aneurysm clip. (a) Identification. An aneurysm clip is a device used to occlude an intracranial aneurysm (a balloonlike sac formed on a blood...

  5. 21 CFR 882.5200 - Aneurysm clip.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Aneurysm clip. 882.5200 Section 882.5200 Food and... NEUROLOGICAL DEVICES Neurological Therapeutic Devices § 882.5200 Aneurysm clip. (a) Identification. An aneurysm clip is a device used to occlude an intracranial aneurysm (a balloonlike sac formed on a blood...

  6. True aneurysm of brachial artery.

    PubMed

    Hudorović, Narcis; Lovričević, Ivo; Franjić, Dario Bjorn; Brkić, Petar; Tomas, Davor

    2010-10-01

    True upper extremity peripheral artery aneurysms are a rarely encountered arterial disorder. Following computer-tomography angiographic (CT-a) imaging examination, true saccular aneurysm, originating from the left brachial artery was diagnosed in the 77-year-old female without history of trauma. The aneurysm was resected by surgical intervention, and primary repair of the brachial artery was performed by interposition of a part of great saphenous vein harvested from the left groin and creation of two end-to-end anastomoses between interposition graft and previously resected part of brachial artery. No complication was observed during the follow-up. Surgical intervention for upper extremity aneurysms should be initiated without delay. Factors combined with minimal morbidity associated with repair suggest that surgical repair should be performed routinely for true upper extremity arterial aneurysms. PMID:20865459

  7. The unruptured intracranial aneurysm treatment score

    PubMed Central

    Brown, Robert D.; Beseoglu, Kerim; Juvela, Seppo; Raymond, Jean; Morita, Akio; Torner, James C.; Derdeyn, Colin P.; Raabe, Andreas; Mocco, J.; Korja, Miikka; Abdulazim, Amr; Amin-Hanjani, Sepideh; Al-Shahi Salman, Rustam; Barrow, Daniel L.; Bederson, Joshua; Bonafe, Alain; Dumont, Aaron S.; Fiorella, David J.; Gruber, Andreas; Hankey, Graeme J.; Hasan, David M.; Hoh, Brian L.; Jabbour, Pascal; Kasuya, Hidetoshi; Kelly, Michael E.; Kirkpatrick, Peter J.; Knuckey, Neville; Koivisto, Timo; Krings, Timo; Lawton, Michael T.; Marotta, Thomas R.; Mayer, Stephan A.; Mee, Edward; Pereira, Vitor Mendes; Molyneux, Andrew; Morgan, Michael K.; Mori, Kentaro; Murayama, Yuichi; Nagahiro, Shinji; Nakayama, Naoki; Niemelä, Mika; Ogilvy, Christopher S.; Pierot, Laurent; Rabinstein, Alejandro A.; Roos, Yvo B.W.E.M.; Rinne, Jaakko; Rosenwasser, Robert H.; Ronkainen, Antti; Schaller, Karl; Seifert, Volker; Solomon, Robert A.; Spears, Julian; Steiger, Hans-Jakob; Vergouwen, Mervyn D.I.; Wanke, Isabel; Wermer, Marieke J.H.; Wong, George K.C.; Wong, John H.; Zipfel, Gregory J.; Connolly, E. Sander; Steinmetz, Helmuth; Lanzino, Giuseppe; Pasqualin, Alberto; Rüfenacht, Daniel; Vajkoczy, Peter; McDougall, Cameron; Hänggi, Daniel; LeRoux, Peter; Rinkel, Gabriel J.E.; Macdonald, R. Loch

    2015-01-01

    Objective: We endeavored to develop an unruptured intracranial aneurysm (UIA) treatment score (UIATS) model that includes and quantifies key factors involved in clinical decision-making in the management of UIAs and to assess agreement for this model among specialists in UIA management and research. Methods: An international multidisciplinary (neurosurgery, neuroradiology, neurology, clinical epidemiology) group of 69 specialists was convened to develop and validate the UIATS model using a Delphi consensus. For internal (39 panel members involved in identification of relevant features) and external validation (30 independent external reviewers), 30 selected UIA cases were used to analyze agreement with UIATS management recommendations based on a 5-point Likert scale (5 indicating strong agreement). Interrater agreement (IRA) was assessed with standardized coefficients of dispersion (vr*) (vr* = 0 indicating excellent agreement and vr* = 1 indicating poor agreement). Results: The UIATS accounts for 29 key factors in UIA management. Agreement with UIATS (mean Likert scores) was 4.2 (95% confidence interval [CI] 4.1–4.3) per reviewer for both reviewer cohorts; agreement per case was 4.3 (95% CI 4.1–4.4) for panel members and 4.5 (95% CI 4.3–4.6) for external reviewers (p = 0.017). Mean Likert scores were 4.2 (95% CI 4.1–4.3) for interventional reviewers (n = 56) and 4.1 (95% CI 3.9–4.4) for noninterventional reviewers (n = 12) (p = 0.290). Overall IRA (vr*) for both cohorts was 0.026 (95% CI 0.019–0.033). Conclusions: This novel UIA decision guidance study captures an excellent consensus among highly informed individuals on UIA management, irrespective of their underlying specialty. Clinicians can use the UIATS as a comprehensive mechanism for indicating how a large group of specialists might manage an individual patient with a UIA. PMID:26276380

  8. Parallel multiscale simulations of a brain aneurysm

    SciTech Connect

    Grinberg, Leopold; Fedosov, Dmitry A.; Karniadakis, George Em

    2013-07-01

    Cardiovascular pathologies, such as a brain aneurysm, are affected by the global blood circulation as well as by the local microrheology. Hence, developing computational models for such cases requires the coupling of disparate spatial and temporal scales often governed by diverse mathematical descriptions, e.g., by partial differential equations (continuum) and ordinary differential equations for discrete particles (atomistic). However, interfacing atomistic-based with continuum-based domain discretizations is a challenging problem that requires both mathematical and computational advances. We present here a hybrid methodology that enabled us to perform the first multiscale simulations of platelet depositions on the wall of a brain aneurysm. The large scale flow features in the intracranial network are accurately resolved by using the high-order spectral element Navier–Stokes solver NεκTαr. The blood rheology inside the aneurysm is modeled using a coarse-grained stochastic molecular dynamics approach (the dissipative particle dynamics method) implemented in the parallel code LAMMPS. The continuum and atomistic domains overlap with interface conditions provided by effective forces computed adaptively to ensure continuity of states across the interface boundary. A two-way interaction is allowed with the time-evolving boundary of the (deposited) platelet clusters tracked by an immersed boundary method. The corresponding heterogeneous solvers (NεκTαr and LAMMPS) are linked together by a computational multilevel message passing interface that facilitates modularity and high parallel efficiency. Results of multiscale simulations of clot formation inside the aneurysm in a patient-specific arterial tree are presented. We also discuss the computational challenges involved and present scalability results of our coupled solver on up to 300 K computer processors. Validation of such coupled atomistic-continuum models is a main open issue that has to be addressed in

  9. Parallel multiscale simulations of a brain aneurysm

    NASA Astrophysics Data System (ADS)

    Grinberg, Leopold; Fedosov, Dmitry A.; Karniadakis, George Em

    2013-07-01

    Cardiovascular pathologies, such as a brain aneurysm, are affected by the global blood circulation as well as by the local microrheology. Hence, developing computational models for such cases requires the coupling of disparate spatial and temporal scales often governed by diverse mathematical descriptions, e.g., by partial differential equations (continuum) and ordinary differential equations for discrete particles (atomistic). However, interfacing atomistic-based with continuum-based domain discretizations is a challenging problem that requires both mathematical and computational advances. We present here a hybrid methodology that enabled us to perform the first multiscale simulations of platelet depositions on the wall of a brain aneurysm. The large scale flow features in the intracranial network are accurately resolved by using the high-order spectral element Navier-Stokes solver NɛκTαr. The blood rheology inside the aneurysm is modeled using a coarse-grained stochastic molecular dynamics approach (the dissipative particle dynamics method) implemented in the parallel code LAMMPS. The continuum and atomistic domains overlap with interface conditions provided by effective forces computed adaptively to ensure continuity of states across the interface boundary. A two-way interaction is allowed with the time-evolving boundary of the (deposited) platelet clusters tracked by an immersed boundary method. The corresponding heterogeneous solvers (NɛκTαr and LAMMPS) are linked together by a computational multilevel message passing interface that facilitates modularity and high parallel efficiency. Results of multiscale simulations of clot formation inside the aneurysm in a patient-specific arterial tree are presented. We also discuss the computational challenges involved and present scalability results of our coupled solver on up to 300 K computer processors. Validation of such coupled atomistic-continuum models is a main open issue that has to be addressed in future

  10. Parallel multiscale simulations of a brain aneurysm.

    PubMed

    Grinberg, Leopold; Fedosov, Dmitry A; Karniadakis, George Em

    2013-07-01

    Cardiovascular pathologies, such as a brain aneurysm, are affected by the global blood circulation as well as by the local microrheology. Hence, developing computational models for such cases requires the coupling of disparate spatial and temporal scales often governed by diverse mathematical descriptions, e.g., by partial differential equations (continuum) and ordinary differential equations for discrete particles (atomistic). However, interfacing atomistic-based with continuum-based domain discretizations is a challenging problem that requires both mathematical and computational advances. We present here a hybrid methodology that enabled us to perform the first multi-scale simulations of platelet depositions on the wall of a brain aneurysm. The large scale flow features in the intracranial network are accurately resolved by using the high-order spectral element Navier-Stokes solver εκ αr . The blood rheology inside the aneurysm is modeled using a coarse-grained stochastic molecular dynamics approach (the dissipative particle dynamics method) implemented in the parallel code LAMMPS. The continuum and atomistic domains overlap with interface conditions provided by effective forces computed adaptively to ensure continuity of states across the interface boundary. A two-way interaction is allowed with the time-evolving boundary of the (deposited) platelet clusters tracked by an immersed boundary method. The corresponding heterogeneous solvers ( εκ αr and LAMMPS) are linked together by a computational multilevel message passing interface that facilitates modularity and high parallel efficiency. Results of multiscale simulations of clot formation inside the aneurysm in a patient-specific arterial tree are presented. We also discuss the computational challenges involved and present scalability results of our coupled solver on up to 300K computer processors. Validation of such coupled atomistic-continuum models is a main open issue that has to be addressed in future

  11. Computational hemodynamics of abdominal aortic aneurysms: Three-dimensional ultrasound versus computed tomography.

    PubMed

    Owen, Benjamin; Lowe, Christopher; Ashton, Neil; Mandal, Parthasarathi; Rogers, Steven; Wein, Wolfgang; McCollum, Charles; Revell, Alistair

    2016-03-01

    The current criterion for surgical intervention in abdominal aortic aneurysms, based upon a maximal aortic diameter, is considered conservative due to the high mortality rate in case of rupture. The research community is actively investigating the use of computational mechanics tools combined with patient-specific imaging to help identify more accurate criteria. Widespread uptake of a successful metric will however be limited by the need for computed tomography, which is at present the primary image extraction method on account of the location and complex shape of the aneurysms. The use of three-dimensional ultrasound as the scanning method is more attractive on account of increased availability, reduced cost and reduced risk to patients. The suitability of three-dimensional ultrasound is assessed for this purpose in the present work; computational fluid dynamics simulations were performed on geometries obtained from the same patient using both ultrasound and computed tomography. The influence of different smoothing algorithms is investigated in the geometry preparation stage and Taubin's low-pass filter was found to best preserve geometry features. Laminar, Newtonian, steady-state simulation analysis identified haemodynamic characteristics to be qualitatively similar in terms of wall shear stress, velocity and vorticity. The study demonstrates the potential for three-dimensional ultrasound to be integrated into a more accessible patient-specific modelling tool able to identify the need for surgical intervention of abdominal aortic aneurysms. PMID:26893226

  12. Vein graft aneurysms following popliteal aneurysm repair are more common than we think.

    PubMed

    Sharples, Alistair; Kay, Mark; Sykes, Timothy; Fox, Anthony; Houghton, Andrew

    2015-10-01

    True infrainguinal vein graft aneurysms are reported infrequently in the literature. We sought to identify the true incidence of these graft aneurysms after popliteal aneurysm repair and identify factors which may increase the risk of such aneurysms developing. Using a prospectively compiled database, we identified patients who underwent a popliteal aneurysm repair between January 1996 and January 2011 at a single district general hospital. Patients were routinely followed up in a graft surveillance programme. Out of 45 patients requiring repair of a popliteal aneurysm over a 15-year period, four (8.8%) patients developed aneurysmal graft disease. Of the patients who developed graft aneurysms, all had aneurysmal disease at other sites compared with 18 (45.0%) patients who did not develop graft aneurysms. Patients with graft aneurysms had a mean of 1.60 aneurysms elsewhere compared to 0.58 in patients with non-aneurysmal grafts (P = 0.005). True vein graft aneurysms occur in a significant number of patients following popliteal aneurysm repair. Our data would suggest this to be more likely in patients who have aneurysms elsewhere and therefore a predisposition to aneurysmal disease. It may be appropriate for patients with aneurysms at other sites to undergo more prolonged post-operative graft surveillance. PMID:25331071

  13. In vitro analysis of localized aneurysm rupture.

    PubMed

    Romo, Aaron; Badel, Pierre; Duprey, Ambroise; Favre, Jean-Pierre; Avril, Stéphane

    2014-02-01

    In this study, bulge inflation tests were used to characterize the failure response of 15 layers of human ascending thoracic aortic aneurysms (ATAA). Full field displacement data were collected during each of the mechanical tests using a digital image stereo-correlation (DIS-C) system. Using the collected displacement data, the local stress fields at burst were derived and the thickness evolution was estimated during the inflation tests. It was shown that rupture of the ATAA does not systematically occur at the location of maximum stress, but in a weakened zone of the tissue where the measured fields show strain localization and localized thinning of the wall. Our results are the first to show the existence of weakened zones in the aneurysmal tissue when rupture is imminent. An understanding these local rupture mechanics is necessary to improve clinical assessments of aneurysm rupture risk. Further studies must be performed to determine if these weakened zones can be detected in vivo using non-invasive techniques. PMID:24406100

  14. Aneurysm-osteoarthritis syndrome with visceral and iliac artery aneurysms

    PubMed Central

    van der Linde, Denise; Verhagen, Hence J. M.; Moelker, Adriaan; van de Laar, Ingrid M. B. H.; Van Herzeele, Isabelle; De Backer, Julie; Dietz, Harry C.; Roos-Hesselink, Jolien W.

    2014-01-01

    Objective Aneurysms-osteoarthritis syndrome (AOS), caused by SMAD3 mutations, is a recently described autosomal-dominant syndrome characterized by arterial aneurysms, tortuosity, and aortic dissections in combination with osteoarthritis. Our objective was to evaluate the AOS-related vascular consequences in the visceral and iliac arteries and raise awareness for this aggressive syndrome among vascular specialists. Methods All AOS patients were monitored regularly according to our clinical AOS protocol. The study included those with one or more visceral aneurysms or tortuosity, or both. Clinical and surgical data were obtained from record abstraction. Results The study included 17 AOS patients (47% men) aged 47 ± 13 years. A total of 73 aneurysms were encountered, of which 46 were located in the abdomen. The common iliac artery was most commonly affected (37%), followed by the superior mesenteric artery (15%), celiac trunk (11%), and splenic artery (9%). Rapid aneurysm growth ≤1 year was found in three arteries (gastric, hepatic, and vertebral artery). Furthermore, arterial tortuosity was noted in 94% of patients. Four patients underwent six elective (endo) vascular interventions for aneurysms in the iliac, hepatic, gastric, or splenic artery, without major perioperative or postoperative complications. Conclusions AOS predisposes patients to widespread visceral and iliac artery aneurysms and extreme arterial tortuosity. Early elective aneurysm repair should be considered because the risk of aneurysm rupture is estimated to be very high and elective (endo) vascular interventions were not complicated by fragility of arterial tissue. Given the aggressive behavior of AOS, it is of utmost importance that vascular specialists are aware of this new syndrome. PMID:22975338

  15. HRST architecture modeling and assessments

    SciTech Connect

    Comstock, D.A.

    1997-01-01

    This paper presents work supporting the assessment of advanced concept options for the Highly Reusable Space Transportation (HRST) study. It describes the development of computer models as the basis for creating an integrated capability to evaluate the economic feasibility and sustainability of a variety of system architectures. It summarizes modeling capabilities for use on the HRST study to perform sensitivity analysis of alternative architectures (consisting of different combinations of highly reusable vehicles, launch assist systems, and alternative operations and support concepts) in terms of cost, schedule, performance, and demand. In addition, the identification and preliminary assessment of alternative market segments for HRST applications, such as space manufacturing, space tourism, etc., is described. Finally, the development of an initial prototype model that can begin to be used for modeling alternative HRST concepts at the system level is presented. {copyright} {ital 1997 American Institute of Physics.}

  16. HRST architecture modeling and assessments

    NASA Astrophysics Data System (ADS)

    Comstock, Douglas A.

    1997-01-01

    This paper presents work supporting the assessment of advanced concept options for the Highly Reusable Space Transportation (HRST) study. It describes the development of computer models as the basis for creating an integrated capability to evaluate the economic feasibility and sustainability of a variety of system architectures. It summarizes modeling capabilities for use on the HRST study to perform sensitivity analysis of alternative architectures (consisting of different combinations of highly reusable vehicles, launch assist systems, and alternative operations and support concepts) in terms of cost, schedule, performance, and demand. In addition, the identification and preliminary assessment of alternative market segments for HRST applications, such as space manufacturing, space tourism, etc., is described. Finally, the development of an initial prototype model that can begin to be used for modeling alternative HRST concepts at the system level is presented.

  17. DSA volumetric 3D reconstructions of intracranial aneurysms: A pictorial essay

    PubMed Central

    Cieściński, Jakub; Serafin, Zbigniew; Strześniewski, Piotr; Lasek, Władysław; Beuth, Wojciech

    2012-01-01

    Summary A gold standard of cerebral vessel imaging remains the digital subtraction angiography (DSA) performed in three projections. However, in specific clinical cases, many additional projections are required, or a complete visualization of a lesion may even be impossible with 2D angiography. Three-dimensional (3D) reconstructions of rotational angiography were reported to improve the performance of DSA significantly. In this pictorial essay, specific applications of this technique are presented in the management of intracranial aneurysms, including: preoperative aneurysm evaluation, intraoperative imaging, and follow-up. Volumetric reconstructions of 3D DSA are a valuable tool for cerebral vessels imaging. They play a vital role in the assessment of intracranial aneurysms, especially in evaluation of the aneurysm neck and the aneurysm recanalization. PMID:22844309

  18. Left Atrial Appendage Aneurysm.

    PubMed

    Hosseini, Saeid; Hashemi, Arash; Saedi, Sedigheh; Jalili, Farshad; Maleki, Majid; Jalalian, Rozita; Rezaei, Yousef

    2016-09-01

    Left atrial appendage aneurysms (LAAA) are extremely rare. This condition is usually diagnosed incidentally or after the occurrence of thrombotic events or cardiac tachyarrhythmias in the second to fourth decades of life. It can predispose to hazardous adverse events, including atrial fibrillation, myocardial infarction, and systemic thromboembolism. We report a case of LAAA in a 68-year-old woman presenting with atypical chest pain, exertional dyspnea, and episodes of sudden-onset palpitation. Aneurysmectomy with the patient under cardiac arrest with cardiopulmonary bypass was performed. In addition, we explore the diagnosis, management, and prognosis of this entity through a meticulous literature review. PMID:27549544

  19. Abnormal cerebral vasodilation in aneurysmal subarachnoid hemorrhage: use of serial 133Xe cerebral blood flow measurement plus acetazolamide to assess cerebral vasospasm.

    PubMed

    Tran Dinh, Y R; Lot, G; Benrabah, R; Baroudy, O; Cophignon, J; Seylaz, J

    1993-10-01

    A patient with cerebral vasospasm following subarachnoid hemorrhage (SAH) was investigated by serial measurement of cerebral blood flow (CBF) using the xenon-133 emission tomography method. The CBF was measured before and after acetazolamide injection. On Day 2 after SAH, there was early local hyperperfusion in the middle cerebral artery (MCA) territory, ipsilateral to the left posterior communicating artery aneurysm. The regional CBF of this arterial territory decreased slightly after acetazolamide injection, probably because of vasoplegia and the "steal" phenomenon, and thus surgery was delayed. A right hemiplegia with aphasia and disturbed consciousness occurred 4 days later (on Day 6 after SAH) due to arterial vasospasm, despite treatment with a calcium-channel blocker. The initial hyperemia of the left MCA territory was followed by ischemia. The vasodilation induced by acetazolamide administration was significantly subnormal until Day 13, at which time CBF and vasoreactivity amplitude returned to normal and the patient's clinical condition improved. Surgery on Day 14 and outcome were without complication. It is concluded that serial CBF measurements plus acetazolamide injection are useful for monitoring the development of cerebral vasospasm to determine the most appropriate time for aneurysm surgery. PMID:8410215

  20. Spontaneous thrombosis in giant intracranial aneurysms.

    PubMed Central

    Whittle, I R; Dorsch, N W; Besser, M

    1982-01-01

    Twelve patients in a series of 22 with giant intracranial aneurysms demonstrated neuroradiological features of partial or total spontaneous intra-aneurysmal thrombosis. The presence of this intra-aneurysmal clot significantly altered the computed tomographic appearance of the giant aneurysm. Massive intra-aneurysmal thrombosis did not protect against subarachnoid haemorrhage and the likelihood of rupture of a clot containing giant aneurysm was not significantly different from that of a non-thrombosed giant aneurysm. Although parent artery occlusion from a thrombosed giant aneurysm, and massive aneurysmal thrombosis leading to the formation of giant serpentine aneurysm were documented, these are rare epiphenomena. The risk of embolisation from a partially thrombosed giant aneurysm, which was documented in one case, would appear to be greater than that from a non-thrombosed giant aneurysm. The findings in this series, and a review of literature, suggest that the presence of intra-aneurysmal clot in giant intracranial aneurysms has little prognostic significance and does not alter the management or outcome after treatment. Images PMID:7175528

  1. An Earth Penetrating Modeling Assessment

    SciTech Connect

    Stokes, E; Yarrington, P; Glenn, L

    2005-06-21

    Documentation of a study to assess the capability of computer codes to predict lateral loads on earth penetrating projectiles under conditions of non-normal impact. Calculations simulated a set of small scale penetration tests into concrete targets with oblique faces at angles of 15 and 30 degrees to the line-of-flight. Predictive codes used by the various calculational teams cover a wide range of modeling approaches from approximate techniques, such as cavity expansion, to numerical methods, such as finite element codes. The modeling assessment was performed under the auspices of the Phenomenology Integrated Product Team (PIPT) for the Robust Nuclear Earth Penetrator Program (RNEP). Funding for the penetration experiments and modeling was provided by multiple earth penetrator programs.

  2. Chronic Thoracic Aortic Aneurysm Presenting 29 Years following Trauma

    PubMed Central

    Miller, Sarah; Kumar, Prashant; Van den Bosch, Rene; Khanafer, Adib

    2015-01-01

    Blunt, nonpenetrating injuries of the thoracic aorta are uncommon and associated with a high mortality rate within the first hour. Aortic injury is missed in 1-2% of patients that survive to hospital, and a chronic thoracic aortic aneurysm may subsequently form. We present a case in which a chronic thoracic aortic aneurysm was diagnosed 29 years following a significant motor vehicle accident. We discuss the epidemiology, presentation, and management of this uncommon consequence of blunt, nonpenetrating aortic injury. Our case illustrates an important clinical lesson; a past medical history of trauma should not be overlooked at any patient assessment. PMID:26351610

  3. Ventricular Aneurysm Following Myocardial Infarction

    PubMed Central

    Walters, M. B.

    1966-01-01

    Cineradiographic examination appears to be the best method for the study of cardiac pulsations. Fifty consecutive patients, who had sustained transmural myocardial infarction at least six months previously, were studied by this technique. Thirty-six had some abnormality of pulsation and eight had dynamic ventricular aneurysm. Six of the eight had suffered severe infarct. Functional recovery in those with aneurysm was not as complete as in the rest of the group. Two made a poor functional recovery, two a fair recovery, and four a moderately good recovery. Clinically, there were no systemic emboli in the patients with dynamic aneurysms. Five of the 50 had persistent ST-segment elevation and “coving” of the T waves; three of these patients had aneurysms. There was no good correlation between the electrocardiographic site of the infarct and the site of the abnormal pulsation. ImagesFig. 1 PMID:5928534

  4. Climate Modeling Computing Needs Assessment

    NASA Astrophysics Data System (ADS)

    Petraska, K. E.; McCabe, J. D.

    2011-12-01

    This paper discusses early findings of an assessment of computing needs for NASA science, engineering and flight communities. The purpose of this assessment is to document a comprehensive set of computing needs that will allow us to better evaluate whether our computing assets are adequately structured to meet evolving demand. The early results are interesting, already pointing out improvements we can make today to get more out of the computing capacity we have, as well as potential game changing innovations for the future in how we apply information technology to science computing. Our objective is to learn how to leverage our resources in the best way possible to do more science for less money. Our approach in this assessment is threefold: Development of use case studies for science workflows; Creating a taxonomy and structure for describing science computing requirements; and characterizing agency computing, analysis, and visualization resources. As projects evolve, science data sets increase in a number of ways: in size, scope, timelines, complexity, and fidelity. Generating, processing, moving, and analyzing these data sets places distinct and discernable requirements on underlying computing, analysis, storage, and visualization systems. The initial focus group for this assessment is the Earth Science modeling community within NASA's Science Mission Directorate (SMD). As the assessment evolves, this focus will expand to other science communities across the agency. We will discuss our use cases, our framework for requirements and our characterizations, as well as our interview process, what we learned and how we plan to improve our materials after using them in the first round of interviews in the Earth Science Modeling community. We will describe our plans for how to expand this assessment, first into the Earth Science data analysis and remote sensing communities, and then throughout the full community of science, engineering and flight at NASA.

  5. Cerebral aneurysms: relations between geometry, hemodynamics and aneurysm location in the cerebral vasculature

    NASA Astrophysics Data System (ADS)

    Passerini, Tiziano; Veneziani, Alessandro; Sangalli, Laura; Secchi, Piercesare; Vantini, Simone

    2010-11-01

    In cerebral blood circulation, the interplay of arterial geometrical features and flow dynamics is thought to play a significant role in the development of aneurysms. In the framework of the Aneurisk project, patient-specific morphology reconstructions were conducted with the open-source software VMTK (www.vmtk.org) on a set of computational angiography images provided by Ospedale Niguarda (Milano, Italy). Computational fluid dynamics (CFD) simulations were performed with a software based on the library LifeV (www.lifev.org). The joint statistical analysis of geometries and simulations highlights the possible association of certain spatial patterns of radius, curvature and shear load along the Internal Carotid Artery (ICA) with the presence, position and previous event of rupture of an aneurysm in the entire cerebral vasculature. Moreover, some possible landmarks are identified to be monitored for the assessment of a Potential Rupture Risk Index.

  6. Aneurysm of the Splenic Artery

    PubMed Central

    Bedford, P. D.; Lodge, Brian

    1960-01-01

    This paper records an incidence of 10·4% of aneurysm of the splenic artery in 250 consecutive routine post-mortem examinations. Medial degeneration seemed to be the commonest cause of such aneurysms and although a number were associated with other intraabdominal pathology, including portal hypertension, the association may be fortuitous and not causal. ImagesFig. 1Fig. 2Fig. 3Fig. 4Fig. 5Fig. 6 PMID:13688586

  7. Left Main Coronary Artery Aneurysm

    PubMed Central

    Doustkami, Hossein; Maleki, Nasrollah; Tavosi, Zahra

    2016-01-01

    Aneurysms of the left main coronary artery are exceedingly rare clinical entities, encountered incidentally in approximately 0.1% of patients who undergo routine angiography. The most common cause of coronary artery aneurysms is atherosclerosis. Angiography is the gold standard for diagnosis and treatment. Depending on the severity of the coexisting coronary stenosis, patients with left main coronary artery aneurysms can be effectively managed either surgically or pharmacologically. We herein report a case of left main coronary artery aneurysm in a 72-year-old man with a prior history of hypertension presenting to our hospital because of unstable angina. The electrocardiogram showed ST-segment depression and T-wave inversion in the precordial leads. All the data of blood chemistry were normal. Echocardiography showed akinetic anterior wall, septum, and apex, mild mitral regurgitation and ejection fraction of 45%. Coronary angiography revealed a saccular aneurysm of the left main coronary artery with significant stenosis in the left anterior descending, left circumflex, and right coronary artery. The patient immediately underwent coronary artery bypass grafting and ligation of the aneurysm. At six months’ follow-up, he remained asymptomatic. PMID:27403190

  8. Segmental Aortic Stiffening Contributes to Experimental Abdominal Aortic Aneurysm Development

    PubMed Central

    Raaz, Uwe; Zöllner, Alexander M.; Schellinger, Isabel N.; Toh, Ryuji; Nakagami, Futoshi; Brandt, Moritz; Emrich, Fabian C.; Kayama, Yosuke; Eken, Suzanne; Adam, Matti; Maegdefessel, Lars; Hertel, Thomas; Deng, Alicia; Jagger, Ann; Buerke, Michael; Dalman, Ronald L.; Spin, Joshua M.; Kuhl, Ellen; Tsao, Philip S.

    2015-01-01

    Background Stiffening of the aortic wall is a phenomenon consistently observed in age and in abdominal aortic aneurysm (AAA). However, its role in AAA pathophysiology is largely undefined. Methods and Results Using an established murine elastase-induced AAA model, we demonstrate that segmental aortic stiffening (SAS) precedes aneurysm growth. Finite element analysis (FEA) reveals that early stiffening of the aneurysm-prone aortic segment leads to axial (longitudinal) wall stress generated by cyclic (systolic) tethering of adjacent, more compliant wall segments. Interventional stiffening of AAA-adjacent aortic segments (via external application of surgical adhesive) significantly reduces aneurysm growth. These changes correlate with reduced segmental stiffness of the AAA-prone aorta (due to equalized stiffness in adjacent segments), reduced axial wall stress, decreased production of reactive oxygen species (ROS), attenuated elastin breakdown, and decreased expression of inflammatory cytokines and macrophage infiltration, as well as attenuated apoptosis within the aortic wall. Cyclic pressurization of segmentally stiffened aortic segments ex vivo increases the expression of genes related to inflammation and extracellular matrix (ECM) remodeling. Finally, human ultrasound studies reveal that aging, a significant AAA risk factor, is accompanied by segmental infrarenal aortic stiffening. Conclusions The present study introduces the novel concept of segmental aortic stiffening (SAS) as an early pathomechanism generating aortic wall stress and triggering aneurysmal growth, thereby delineating potential underlying molecular mechanisms and therapeutic targets. In addition, monitoring SAS may aid the identification of patients at risk for AAA. PMID:25904646

  9. Hemodynamic patterns of anterior communicating artery aneurysms: a possible association with rupture

    NASA Astrophysics Data System (ADS)

    Castro, Marcelo A.; Putman, Christopher M.; Cebral, Juan R.

    2007-03-01

    The aim of this study is to characterize the different flows present at anterior communicating artery (AcoA) aneurysms and investigate possible associations with rupture. For that purpose, patient-specific computational models of 26 AcoA aneurysms were constructed from 3D rotational angiography images. Bilateral images were acquired in 15 patients who had both A1 segments of the anterior cerebral arteries and models were created by fusing the reconstructed left and right arterial trees. Computational fluid dynamics simulations were performed under pulsatile flow conditions. Visualizations of the flow velocity pattern were created to classify the aneurysms into the following flow types: A) inflow from both A1 segments, B) flow jet in the parent artery splits into three secondary jets, one enters the aneurysm and the other two are directed to the A2 segments, C) the parent artery jet splits into two secondary jets, one is directed to one of the A2 segments and the other enters the aneurysm before being directed to the other A2 segment, and D) the parent artery jet enters the aneurysm before being directed towards the A2 segments. The maximum wall shear stress in the aneurysm at the systolic peak (MWSS) was calculated. Most aneurysms in group A were unruptured and had the lowest MWSS. Group B had the same number of unruptured and ruptured aneurysms, and a low MWSS. Groups C and D had high rupture ratios, being the average MWSS significantly higher in group C. Finally, it was found that the MWSS was higher for ruptured aneurysms of all flow types.

  10. A Concealed Intracranial Aneurysm Detected after Recanalization of an Occluded Vessel: A Case Report and Literature Review

    PubMed Central

    Torikoshi, Sadaharu; Akiyama, Yoshinori

    2016-01-01

    Background Based on the results of several randomized controlled trials, acute endovascular thrombectomy is strongly recommended for patients with acute ischemic stroke due to large artery occlusion (LAO). The incidence of an intracranial aneurysm has been reported to be approximately 5% in the general population. Therefore, the possibility of the coincidence of LAO and an intracranial aneurysm at the distal part of an occluded vessel should be considered. Summary A 74-year-old female patient presented with the sudden onset of consciousness disturbance and left-sided weakness. Neuroimages demonstrated an acute infarction due to right middle cerebral artery occlusion. The occlusion was successfully treated, and an aneurysm was incidentally detected at the occluded artery. We reviewed the literature and identified 11 cases in 8 reports, which were similar to our case. Among the 11 cases, aneurysms ruptured during endovascular therapy in 2 cases. In the present report, we discussed the prediction of concealed aneurysms and avoidance of their rupture during endovascular intervention. Key Message The presence of an aneurysm concealed behind an embolus should be carefully assessed on preoperative and intraoperative neuroimages. The important findings for suspecting such an aneurysm are a hyperdense nodular sign on preoperative computed tomography and unusual motion of the microwire during the endovascular intervention. Even if there is no finding indicative of an aneurysm, the catheter and thrombectomy devices should be more carefully advanced than usual, especially at the common sites of aneurysms, and the devices should be appropriately chosen. PMID:27051404

  11. When Blood Vessels Bulge: All About Aneurysms

    MedlinePlus

    ... Vessels Bulge When Blood Vessels Bulge All About Aneurysms An aneurysm—a balloon-like bulge in an artery—can ... for years without causing any symptoms. But an aneurysm is a silent threat to your health. If ...

  12. Aspergillus mycotic aneurysm--case report.

    PubMed

    Komatsu, Y; Narushima, K; Kobayashi, E; Tomono, Y; Nose, T

    1991-06-01

    A 61-year-old female developed subarachnoid hemorrhage after trans-sphenoidal surgery for Rathke's cleft cyst. Neuroradiological examination revealed a large aneurysm at the C1 portion of the right internal carotid artery. Autopsy revealed marked proliferation of aspergillus hyphae in the wall of the aneurysm. A review of previously reported cases of fungal aneurysm proposes two developmental processes. Aneurysms secondary to fungal meningitis tend to be large in size and located in the major cerebral artery trunk, but aneurysms following fungal sepsis tend to be small and in peripheral branches. The former aneurysms are probably caused by fungus invasion into the intracranium, usually from the paranasal sinus, and the latter may be due to fungal emboli like bacterial emboli in bacterial endocarditis. Ruptured fungal aneurysms are difficult to treat, so fungal meningitis or sepsis must be eradicated before an aneurysm develops. PMID:1724300

  13. Aneurysms - Multiple Languages: MedlinePlus

    MedlinePlus

    ... Supplements Videos & Tools You Are Here: Home → Multiple Languages → All Health Topics → Aneurysms URL of this page: https://medlineplus.gov/languages/aneurysms.html Other topics A-Z A B ...

  14. Aneurysms - Multiple Languages: MedlinePlus

    MedlinePlus

    ... Supplements Videos & Tools You Are Here: Home → Multiple Languages → All Health Topics → Aneurysms URL of this page: https://www.nlm.nih.gov/medlineplus/languages/aneurysms.html Other topics A-Z A B ...

  15. Aneurysmal bone cyst.

    PubMed

    Rapp, Timothy B; Ward, James P; Alaia, Michael J

    2012-04-01

    Aneurysmal bone cysts are rare skeletal tumors that most commonly occur in the first two decades of life. They primarily develop about the knee but may arise in any portion of the axial or appendicular skeleton. Pathogenesis of these tumors remains controversial and may be vascular, traumatic, or genetic. Radiographic features include a dilated, radiolucent lesion typically located within the metaphyseal portion of the bone, with fluid-fluid levels visible on MRI. Histologic features include blood-filled lakes interposed between fibrous stromata. Differential diagnosis includes conditions such as telangiectatic osteosarcoma and giant cell tumor. The mainstay of treatment is curettage and bone graft, with or without adjuvant treatment. Other management options include cryotherapy, sclerotherapy, radionuclide ablation, and en bloc resection. The recurrence rate is low after appropriate treatment; however, more than one procedure may be required to completely eradicate the lesion. PMID:22474093

  16. Endovascular Exclusion of Renal Artery Aneurysm

    SciTech Connect

    Andersen, Poul Erik Rohr, Nils

    2005-06-15

    A patient who was operated for an abdominal aortic aneurysm 7 years earlier presented with recently discovered iliac and renal artery aneurysms. The renal artery had an angulation of 90{sup o}, but the aneurysm was successfully excluded using a covered vascular stent graft placed over an extrastiff guidewire. Even in cases of complex anatomy of a renal aneurysm, endovascular treatment should be considered. With development of more flexible and low-profile endoprosthesis with accurate deployment, these have become more usable.

  17. Changes of size and shape of small, unruptured intracranial aneurysms in repeated computed tomography angiography studies

    PubMed Central

    Kunert, Przemysław; Jaworski, Maciej; Rosiak, Grzegorz; Marchel, Andrzej; Rowiński, Olgierd

    2015-01-01

    Introduction Unruptured intracranial aneurysms (UIAs) are frequently detected in noninvasive imaging studies such as computed tomography angiography (CTA) or magnetic resonance angiography (MRA). If small, UIAs are observed in these modalities in order to detect growth or shape change, but there are many questions about proper protocol of the follow-up. Aim To assess changes of small (< 7 mm) UIAs dome size and shape in repeated CTA studies as predictors of growth and rupture. Material and methods One hundred and ten UIAs (10 posterior circulation) in 70 patients (55 women) were observed, with a cumulative observation time of 333.32 years. Aneurysms’ dome and neck perpendicular dimensions were measured in the first and the last CTA study at least twice with the developed application. Confidence intervals (CI) for measurements and dome shape parameters were calculated. For aneurysms ruptured during follow-up intermediate studies were analyzed. Patients’ clinical information was recorded. The aneurysm growth detection algorithm integrated CI and spatial resolution of the CT scanner. Results Twenty-three aneurysms increased in volume, 10 in height and 14 in dome width. Volume increased in 90% of cases of height and 93% of width increase. Posterior circulation aneurysms grew faster than anterior ones (p < 0.003), but calculated time to significant size increase (eT) did not differ between the groups due to higher CI in the posterior circulation. Analysis of eT with Kaplan-Meier curves showed that 75% of growing aneurysms could be detected in the first 3 years of observation. During the follow-up 3 aneurysms bled, and they grew faster than other growing aneurysms. Two of the bleeding aneurysms formed daughter sacs. Conclusions Dome volume assessment is superior to single dimension assessment in aneurysm growth detection. Confidence intervals assessment helps to avoid overestimation of growth. Seventy-five percent of growing aneurysms could be detected in the first 3

  18. Surgical treatment of an aneurysm of a distal branch of the renal artery.

    PubMed

    Abdalla, Solafah; Pierret, Charles; Ba, Bakar; Mlynski, Amélie; de Kerangal, Xavier; Houlgatte, Alain

    2014-01-01

    Aneurysms of the renal artery and its branches are rare, but are associated with significant morbimortality due to the absence of clinical symptoms and hemorrhagic risk in the event of rupture. We report the case of a patient with an aneurysm of a distal branch of the right renal artery that measured 25 mm in diameter. The diagnosis and localization were obtained using selective arteriography. Treatment consisted of resection of the aneurysmal sac associated with closure with a saphenous vein patch rather than an endovascular treatment in order to preserve the nephronic capital. Right renal parenchymatous vascularization was satisfactory on arterial echo-Doppler and angioscanner assessment at 1 year. PMID:24120233

  19. The quasi-static failure properties of the abdominal aortic aneurysm wall estimated by a mixed experimental-numerical approach.

    PubMed

    Forsell, Caroline; Swedenborg, Jesper; Roy, Joy; Gasser, T Christian

    2013-07-01

    Assessing the risk for abdominal aortic aneurysm (AAA) rupture is critical in the management of aneurysm patients and an individual assessment is possible with the biomechanical rupture risk assessment. Such an assessment could potentially be improved by a constitutive AAA wall model that accounts for irreversible damage-related deformations. Because of that the present study estimated the elastic and inelastic properties of the AAA wall through a mixed experimental-numerical approach. Specifically, finite element (FE) models of bone-shaped tensile specimens were used to merge data from failure testing of the AAA wall with their measured collagen orientation distribution. A histo-mechanical constitutive model for collagen fibers was employed, where plastic fibril sliding determined not only remaining deformations but also weakening of the fiber. The developed FE models were able to replicate the experimentally recorded load-displacement property of all 16 AAA wall specimens that were investigated in the study. Tensile testing in longitudinal direction of the AAA defined a Cauchy strength of 569(SD 411) kPa that was reached at a stretch of 1.436(SD 0.118). The stiffness and strength of specimens decreased with the wall thickness and were elevated (p = 0.018; p = 0.030) in patients with chronic obstructive pulmonary disease (COPD). Smoking affected the tissue parameters that were related to the irreversible deformation response, and no correlation with gender and age was found. The observed effects on the biomechanical properties of the AAA wall could have long-term consequences for the management of aneurysm patients, i.e., specifically they might influence future AAA rupture risk assessments. However, in order to design appropriate clinical validation studies our findings should firstly be verified in a larger patient cohort. PMID:23263935

  20. Hydropower Resource Assessment Modeling Results

    SciTech Connect

    Conner, Alison Marie; Francfort, James Edward

    1999-07-01

    The U.S. Department of Energy's Hydropower Program developed the Hydropower Evaluation Software to model the undeveloped hydropower resources in the United States based on environmental, legal, and institutional constraints. This Hydropower Resource Assessment effort has identified 5,677 sites that have an undeveloped total capacity of about 30,000 megawatts. The Hydropower Evaluation Software uses the Federal Energy Regulatory Commission's Hydroelectric Power Resource Assessment database to identify sites with undeveloped hydropower capacity and the estimated megawatts of undeveloped capacity at each site. The software integrates this information with environmental values from the National Park Service's National Rivers Inventory database. Other constraints to development that are modeled include Federal and state legislative protection for river segments that have been identified as being wild and scenic river segments. River segments containing threatened and/or endangered wildlife and fish are also modeled for their influence on hydropower development. The amount that each attribute affects the likelihood of development is dependent on the prior development of a site.

  1. Hydropower Resource Assessment Modeling Results

    SciTech Connect

    Conner, A M; Francfort, J E

    1999-07-06

    The U.S. Department of Energy's Hydropower Program developed the Hydropower Evaluation Software to model the undeveloped hydropower resources in the United States based on environmental, legal, and institutional constraints. This Hydropower Resource Assessment effort has identified 5,677 sites that have an undeveloped total capacity of about 30,000 megawatts. The Hydropower Evaluation Software uses the Federal Energy Regulatory Commission's Hydroelectric Power Resource Assessment database to identify sites with undeveloped hydropower capacity and the estimated megawatts of undeveloped capacity at each site. The software integrates this information with environmental values from the National Park Service's National Rivers Inventory database. Other constraints to development that are modeled include Federal and state legislative protection for river segments that have been identified as being wild and scenic river segments. River segments containing threatened and/or endangered wildlife and fish are also modeled for their influence on hydropower development. The amount that each attribute affects the likelihood of development is dependent on the prior development of a site.

  2. Prognosis Predicting Score for Endovascular Treatment of Aneurysmal Subarachnoid Hemorrhage

    PubMed Central

    Duan, Guoli; Yang, Pengfei; Li, Qiang; Zuo, Qiao; Zhang, Lei; Hong, Bo; Xu, Yi; Zhao, Wenyuan; Liu, Jianmin; Huang, Qinghai

    2016-01-01

    Abstract The elderly patients with aneurysmal subarachnoid hemorrhage (aSAH) have a greater risk of poor clinical outcome after endovascular treatment (EVT) than younger patients do. Hence, it is necessary to explore which factors are associated with poor outcome and develop a predictive score specifically for elderly patients with aSAH receiving EVT. The aim of this study was to develop and validate a predictive score for 1-year outcomes in individual elderly patients with aSAH underwent EVT. In this 10-year prospective study, 520 consecutive aSAH elderly (age ≥ 60 years) patients underwent EVT in a single center were included. The risk factors, periprocedural, and 1-year follow-up data of all patients were entered in a specific prospective database. The modified Rankin scale was used for evaluating clinical outcome. To optimize the model's predictive capacity, the original matrix was randomly divided in 2 submatrices (learning and testing). The predictive score was developed using Arabic numerals for all variables based on the variable coefficients (β) of multivariable logistic regression analysis in the learning set and the predictive performance evaluation was assessed in the testing set. The risk classes were constructed using classification criteria based on sensitivity and specificity. The poor outcome rate at 1 year was 26.15%. Six risk factors, including age, hypertension, Hunt–Hess scale, Fisher scale, aneurysm location, and periprocedural complications, were independently associated with poor outcome and assembled the Changhai score. The discriminative power analysis with the area under the receiver operating characteristic curve (AUC) of the Changhai score was statistically significant (0.864, 0.824–0.904, P < 0.001). The sensitivity and specificity of the Changhai score were 82.07% and 78.06%, respectively. Our study indicated that age, hypertension, Hunt–Hess scale, Fisher scale, aneurysm location, and periprocedural complications were

  3. Thoracoabdominal aortic aneurysm repair: current endovascular perspectives

    PubMed Central

    Orr, Nathan; Minion, David; Bobadilla, Joseph L

    2014-01-01

    Thoracoabdominal aneurysms account for roughly 3% of identified aneurysms annually in the United States. Advancements in endovascular techniques and devices have broadened their application to these complex surgical problems. This paper will focus on the current state of endovascular thoracoabdominal aneurysm repair, including specific considerations in patient selection, operative planning, and perioperative complications. Both total endovascular and hybrid options will be considered. PMID:25170271

  4. Transcatheter Coil Embolization of Splenic Artery Aneurysm

    SciTech Connect

    Yamamoto, Satoshi Hirota, Shozo; Maeda, Hiroaki; Achiwa, Sachiko Arai, Keisuke; Kobayashi, Kaoru; Nakao, Norio

    2008-05-15

    The purpose of this study was to evaluate clinical results and technical problems of transcatheter coil embolization for splenic artery aneurysm. Subjects were 16 patients (8 men, 8 women; age range, 40-80 years) who underwent transcatheter embolization for splenic artery aneurysm (14 true aneurysms, 2 false aneurysms) at one of our hospitals during the period January 1997 through July 2005. Two aneurysms (12.5%) were diagnosed at the time of rupture. Multiple splenic aneurysms were found in seven patients. Aneurysms were classified by site as proximal (or strictly ostial) (n = 3), middle (n = 3), or hilar (n = 10). The indication for transcatheter arterial embolization was a false or true aneurysm 20 mm in diameter. Embolic materials were fibered coils and interlocking detachable coils. Embolization was performed by the isolation technique, the packing technique, or both. Technically, all aneurysms were devascularized without severe complications. Embolized aneurysms were 6-40 mm in diameter (mean, 25 mm). Overall, the primary technical success rate was 88% (14 of 16 patients). In the remaining 2 patients (12.5%), partial recanalization occurred, and re-embolization was performed. The secondary technical success rate was 100%. Seven (44%) of the 16 study patients suffered partial splenic infarction. Intrasplenic branching originating from the aneurysm was observed in five patients. We conclude that transcatheter coil embolization should be the initial treatment of choice for splenic artery aneurysm.

  5. Comparative study of novel endovascular treatment techniques for intracranial aneurysms

    NASA Astrophysics Data System (ADS)

    Cantón, Gádor; Lasheras, Juan C.; Levy, David I.; Sparks, Steven R.

    2002-11-01

    Intracranial aneurysms are life-threatening vascular lesions, which are potentially treatable to avoid the consequences of their rupture. Current treatments, either surgical or endovascular, are all guided to reduce the hemodynamic forces acting on the aneurysm wall in an effort to minimize the risk of rupture. Surgical clipping is still the most used technique to treat this type of aneurysm but there is a continued demand for less invasive approaches. This has led to the development of several endovascular techniques. We report here a comparative study of the reduction in the hemodynamic stresses and the modification of the flow in the parent vessel resulting from the use of three different techniques. The first one consists of endosaccular packing with platinum coils (GDC, Target Therapeutics), which is already widely used but its long-term efficacy has not yet been determined. The second one consists of the embolization of the aneurismal sac with Onyx, a polymer which hardens when in contact with the blood (being developed by Micro Therapeutics, Inc.). The third one involves the packing of the sac with hydrocoils, platinum wires coated with a gel which quickly hydrates when in contact with blood (developed by MicroVention). A Digital Particle Image Velocimetry (DPIV) system is used to measure in vitro the velocity field inside a model of an ACOM aneurysm (an aneurysm forming in the anterior communicating artery). Physiological accurate pulsatile flow conditions are input to the arterial model through a programmable pump. The measurements show that although all treatment techniques lead to a reduction in both normal and tangential shear stresses on the aneurismal sac, each one of them also leads to different modifications of the flow in the parent vessel which may have consequences related to potential for clotting. Comparison of the untreated aneurysm with the above three treated cases also showed that the characteristics of the wall shear stresses on the parent

  6. Phantom-based experimental validation of computational fluid dynamics simulations on cerebral aneurysms

    SciTech Connect

    Sun Qi; Groth, Alexandra; Bertram, Matthias; Waechter, Irina; Bruijns, Tom; Hermans, Roel; Aach, Til

    2010-09-15

    Purpose: Recently, image-based computational fluid dynamics (CFD) simulation has been applied to investigate the hemodynamics inside human cerebral aneurysms. The knowledge of the computed three-dimensional flow fields is used for clinical risk assessment and treatment decision making. However, the reliability of the application specific CFD results has not been thoroughly validated yet. Methods: In this work, by exploiting a phantom aneurysm model, the authors therefore aim to prove the reliability of the CFD results obtained from simulations with sufficiently accurate input boundary conditions. To confirm the correlation between the CFD results and the reality, virtual angiograms are generated by the simulation pipeline and are quantitatively compared to the experimentally acquired angiograms. In addition, a parametric study has been carried out to systematically investigate the influence of the input parameters associated with the current measuring techniques on the flow patterns. Results: Qualitative and quantitative evaluations demonstrate good agreement between the simulated and the real flow dynamics. Discrepancies of less than 15% are found for the relative root mean square errors of time intensity curve comparisons from each selected characteristic position. The investigated input parameters show different influences on the simulation results, indicating the desired accuracy in the measurements. Conclusions: This study provides a comprehensive validation method of CFD simulation for reproducing the real flow field in the cerebral aneurysm phantom under well controlled conditions. The reliability of the CFD is well confirmed. Through the parametric study, it is possible to assess the degree of validity of the associated CFD model based on the parameter values and their estimated accuracy range.

  7. Patient-specific simulation of endovascular repair surgery with tortuous aneurysms requiring flexible stent-grafts.

    PubMed

    Perrin, David; Badel, Pierre; Orgeas, Laurent; Geindreau, Christian; du Roscoat, Sabine Rolland; Albertini, Jean-Noël; Avril, Stéphane

    2016-10-01

    The rate of post-operative complications is the main drawback of endovascular repair, a technique used to treat abdominal aortic aneurysms. Complex anatomies, featuring short aortic necks and high vessel tortuosity for instance, have been proved likely prone to these complications. In this context, practitioners could benefit, at the preoperative planning stage, from a tool able to predict the post-operative position of the stent-graft, to validate their stent-graft sizing and anticipate potential complications. In consequence, the aim of this work is to prove the ability of a numerical simulation methodology to reproduce accurately the shapes of stent-grafts, with a challenging design, deployed inside tortuous aortic aneurysms. Stent-graft module samples were scanned by X-ray microtomography and subjected to mechanical tests to generate finite-element models. Two EVAR clinical cases were numerically reproduced by simulating stent-graft models deployment inside the tortuous arterial model generated from patient pre-operative scan. In the same manner, an in vitro stent-graft deployment in a rigid polymer phantom, generated by extracting the arterial geometry from the preoperative scan of a patient, was simulated to assess the influence of biomechanical environment unknowns in the in vivo case. Results were validated by comparing stent positions on simulations and post-operative scans. In all cases, simulation predicted stents deployed locations and shapes with an accuracy of a few millimetres. The good results obtained in the in vitro case validated the ability of the methodology to simulate stent-graft deployment in very tortuous arteries and led to think proper modelling of biomechanical environment could reduce the few local discrepancies found in the in vivo case. In conclusion, this study proved that our methodology can achieve accurate simulation of stent-graft deployed shape even in tortuous patient specific aortic aneurysms and may be potentially helpful to

  8. Unruptured anterior communicating artery aneurysm presenting as depression: A case report and review of literature

    PubMed Central

    Bunevicius, Adomas; Cikotas, Paulius; Steibliene, Vesta; Deltuva, Vytenis P.; Tamsauskas, Arimantas

    2016-01-01

    Background: Intracranial aneurysms most commonly present following rupture causing subarachnoid hemorrhage. Mental disorders are common among patients with unruptured intracranial aneurysms and in aneurysmal subarachnoid hemorrhage survivors. However, to the best of our knowledge, there is no published report of unruptured intracranial aneurysm presenting as a mental disorder. Case Description: A 69-year-old male without a past history of mental disorders and neurological symptoms presented with a 2-month history of anxiety, sadness, lack of pleasure in usual activities, fatigue, difficulties falling asleep and waking up early in the morning, reduced appetite, and weight loss. The patient was diagnosed with major depressive disorder and antidepressant treatment was initiated. Subsequent non-contrast computed tomography (CT) of the head demonstrated hypointense oval-shaped lesion within the projection of the anterior communicating artery. CT angiography confirmed the diagnosis of a 0.8 × 0.6 cm saccular aneurysm originating from the anterior communicating artery and anterior cerebral artery. The patient underwent microsurgical clipping of the aneurysm. On psychiatric assessment 1 month after the surgery, there were no signs of depressive disorder and antidepressive treatment was discontinued. On follow-up visit 1 year after the surgery, the patient did not have any mood symptoms. Conclusions: The case indicates that organic brain lesions, including intracranial aneurysms, should be suspected in elderly patients presenting with their first episode of mental disorder. PMID:27583172

  9. Intracranial aneurysms: Diagnostics accuracy of three-dimensional, fourier transform, time-of-flight MR angiography

    SciTech Connect

    Korogi, Yukunori; Takahashi, Mutsumasa; Mabuchi, Nobuhisa; Miki, Hitoshi; Fujiwara, Satoru; Horikawa, Yoshiharu; Nakagawa, Toshio; O`Uchi, Toshihiro; Watabe, Tsuneya; Shiga, Hayao

    1994-10-01

    To assess the accuracy of three-dimensional, Fourier transform, time-of-flight magnetic resonance (MR) angiography in the identification of intracranial aneurysms. MR angiograms of 126 patients (59 male and 67 female patients, aged 12-77 years) with various intracranial vascular lesions were evaluated. Seventy-eight aneurysms, including 60 less than 5 mm in diameter, in 61 patients were depicted at conventional angiography. Eight projection images, as well as one axial collapsed MR angiogram obtained with a maximum-intensity projection algorithm, were used for evaluation. Sensitivity for the five observers ranged from 58% to 68% (mean, 63%). Higher sensitivity was achieved for anterior communicating and middle cerebral artery aneurysms, while that for internal carotid artery aneurysms was poor. Sensitivities for small and medium aneurysms ranged from 50% to 60% (mean, 56%) and from 77% to 94% (mean, 85%), respectively. MR angiography can depict intracranial aneurysms 5 mm or larger with good accuracy but is less useful for the identification of smaller aneurysms. 12 refs., 5 figs., 5 tabs.

  10. Utility of Social Modeling for Proliferation Assessment - Preliminary Assessment

    SciTech Connect

    Coles, Garill A.; Gastelum, Zoe N.; Brothers, Alan J.; Thompson, Sandra E.

    2009-06-01

    This Preliminary Assessment draft report will present the results of a literature search and preliminary assessment of the body of research, analysis methods, models and data deemed to be relevant to the Utility of Social Modeling for Proliferation Assessment research. This report will provide: 1) a description of the problem space and the kinds of information pertinent to the problem space, 2) a discussion of key relevant or representative literature, 3) a discussion of models and modeling approaches judged to be potentially useful to the research, and 4) the next steps of this research that will be pursued based on this preliminary assessment. This draft report represents a technical deliverable for the NA-22 Simulations, Algorithms, and Modeling (SAM) program. Specifically this draft report is the Task 1 deliverable for project PL09-UtilSocial-PD06, Utility of Social Modeling for Proliferation Assessment. This project investigates non-traditional use of social and cultural information to improve nuclear proliferation assessment, including nonproliferation assessment, proliferation resistance assessments, safeguards assessments and other related studies. These assessments often use and create technical information about the State’s posture towards proliferation, the vulnerability of a nuclear energy system to an undesired event, and the effectiveness of safeguards. This project will find and fuse social and technical information by explicitly considering the role of cultural, social and behavioral factors relevant to proliferation. The aim of this research is to describe and demonstrate if and how social science modeling has utility in proliferation assessment.

  11. Management of Complicated Aortic Aneurysms Using Multiple Overlapping Uncovered Stents

    PubMed Central

    Zhang, Yongxue; Teng, Zhongzhao; Lu, Qingsheng; Zhao, Zhiqing; Bao, Junmin; Feng, Xiang; Feng, Rui; Chen, Zengsheng; Huang, Yuan; Sadat, Umar; Gillard, Jonathan H; Jing, Zaiping

    2014-01-01

    Abstract This study sought to report the mid-term outcome of a modified flow-diverting strategy in the treatment of complicated aortic aneurysms of different morphology. Historical data suggested aortic aneurysm expansion and rupture after endovascular treatment with current commercial flow-diverters, indicating the essentiality of further investigation of this technique prior to its large-scale clinical application. An alternative flow-diverting strategy using layer-by-layer assembled multiple overlapping uncovered stents was employed in this study. The treatment outcome in aneurysms of different morphology (saccular, fusiform, and dissecting) was assessed during a mid-term follow-up period. Of 42 patients enrolled in this study (30 male, mean age: 63.3 years), technical success was achieved in 40 cases. During an average follow-up period of 20.9 months, mean aneurysm diameter shrunk from 53.4 ± 13.6 mm to 48.8 ± 13.9 mm (P < 0.001), while stent-induced sac thrombosis ratio increased significantly (18.1 ± 14.9% to 93.6 ± 9.5%, P < 0.001). The majority of side branches (74/76 major visceral branches, 237/244 minor segmental arteries), covered by 3.3 stents on average, maintained their patency after stenting. Saccular aneurysms manifested the highest thrombus deposition speed (18/20 were totally thrombosed within 12 months) and most significant shrinkage (51.4 ± 13.3 mm pre-operatively vs 43.5 ± 10.2 mm during follow-up, P < 0.001) compared with fusiform and dissecting aneurysms. This modified flow-diverting strategy could be a feasible alternative in the management of complicated aortic aneurysms where vital branches need to be preserved. The treatment outcome may depend on the aneurysm type. Further studies with larger patient cohort and longer follow-up are required to substantiate these results. PMID:25501077

  12. Endovascular treatment of intracranial aneurysms.

    PubMed

    Diaz, Orlando; Rangel-Castilla, Leonardo

    2016-01-01

    Intracranial aneurysms are abnormal dilations of the intracranial vessels, in which all the layers of the vascular wall are affected by degenerative changes that lead to distension of the vessel. Intracranial aneurysms can be classified based on their anatomic location, size, and morphology. Subarachnoid hemorrhage is the most devastating clinical presentation. The goal of preventing hemorrhage or rehemorrhage can only be achieved by excluding the aneurysm from the cerebral circulation. Endovascular or surgical clipping can achieve this goal. Multiple surgical and endovascular approaches have been described for treatment of intracranial aneurysm. Surgical approaches for anterior-circulation intracranial aneurysms include: pterional, orbitozygomatic, and lateral supraorbital craniotomies. Modern microsurgical techniques involve skull base dissection to achieve adequate exposure with minimal brain retraction. Endovascular techniques can be divided into: parent artery reconstruction with coil deposition (primary coil, balloon-assisted coiling, stent-assisted coiling, and other new techniques such as neck reconstruction devices and intraluminal occlusion devices); reconstruction with flow diversion; and deconstructive techniques with involving parent artery sacrifice with or without bypass. PMID:27430470

  13. Influence of medial collagen organization and axial in situ stretch on saccular cerebral aneurysm growth.

    PubMed

    Eriksson, Thomas; Kroon, Martin; Holzapfel, Gerhard A

    2009-10-01

    A model for saccular cerebral aneurysm growth, proposed by Kroon and Holzapfel (2007, "A Model for Saccular Cerebral Aneurysm Growth in a Human Middle Cerebral Artery," J. Theor. Biol., 247, pp. 775-787; 2008, "Modeling of Saccular Aneurysm Growth in a Human Middle Cerebral Artery," ASME J. Biomech. Eng., 130, p. 051012), is further investigated. A human middle cerebral artery is modeled as a two-layer cylinder where the layers correspond to the media and the adventitia. The immediate loss of media in the location of the aneurysm is taken to be responsible for the initiation of the aneurysm growth. The aneurysm is regarded as a development of the adventitia, which is composed of several distinct layers of collagen fibers perfectly aligned in specified directions. The collagen fibers are the only load-bearing constituent in the aneurysm wall; their production and degradation depend on the stretch of the wall and are responsible for the aneurysm growth. The anisotropy of the surrounding media was modeled using the strain-energy function proposed by Holzapfel et al. (2000, "A New Constitutive Framework for Arterial Wall Mechanics and a Comparative Study of Material Models," J. Elast., 61, pp. 1-48), which is valid for an elastic material with two families of fibers. It was shown that the inclusion of fibers in the media reduced the maximum principal Cauchy stress and the maximum shear stress in the aneurysm wall. The thickness increase in the aneurysm wall due to material growth was also decreased. Varying the fiber angle in the media from a circumferential direction to a deviation of 10 deg from the circumferential direction did, however, only show a little effect. Altering the axial in situ stretch of the artery had a much larger effect in terms of the steady-state shape of the aneurysm and the resulting stresses in the aneurysm wall. The peak values of the maximum principal stress and the thickness increase both became significantly higher for larger axial

  14. Subcutaneous Angiotensin II Infusion using Osmotic Pumps Induces Aortic Aneurysms in Mice

    PubMed Central

    Lu, Hong; Howatt, Deborah A.; Balakrishnan, Anju; Moorleghen, Jessica J.; Rateri, Debra L.; Cassis, Lisa A.; Daugherty, Alan

    2015-01-01

    Osmotic pumps continuously deliver compounds at a constant rate into small animals. This article introduces a standard protocol used to induce aortic aneurysms via subcutaneous infusion of angiotensin II (AngII) from implanted osmotic pumps. This protocol includes calculation of AngII amount and dissolution, osmotic pump filling, implantation of osmotic pumps subcutaneously, observation after pump implantation, and harvest of aortas to visualize aortic aneurysms in mice. Subcutaneous infusion of AngII through osmotic pumps following this protocol is a reliable and reproducible technique to induce both abdominal and thoracic aortic aneurysms in mice. Infusion durations range from a few days to several months based on the purpose of the study. AngII 1,000 ng/kg/min is sufficient to provide maximal effects on abdominal aortic aneurysmal formation in male hypercholesterolemic mouse models such as apolipoprotein E deficient or low-density lipoprotein receptor deficient mice. Incidence of abdominal aortic aneurysms induced by AngII infusion via osmotic pumps is 5 - 10 times lower in female hypercholesterolemic mice and also lower in both genders of normocholesterolemic mice. In contrast, AngII-induced thoracic aortic aneurysms in mice are not hypercholesterolemia or gender-dependent. Importantly, multiple features of this mouse model recapitulate those of human aortic aneurysms. PMID:26436287

  15. Involvement of the renin-angiotensin system in abdominal and thoracic aortic aneurysms.

    PubMed

    Lu, Hong; Rateri, Debra L; Bruemmer, Dennis; Cassis, Lisa A; Daugherty, Alan

    2012-11-01

    Aortic aneurysms are relatively common maladies that may lead to the devastating consequence of aortic rupture. AAAs (abdominal aortic aneurysms) and TAAs (thoracic aortic aneurysms) are two common forms of aneurysmal diseases in humans that appear to have distinct pathologies and mechanisms. Despite this divergence, there are numerous and consistent demonstrations that overactivation of the RAS (renin-angiotensin system) promotes both AAAs and TAAs in animal models. For example, in mice, both AAAs and TAAs are formed during infusion of AngII (angiotensin II), the major bioactive peptide in the RAS. There are many proposed mechanisms by which the RAS initiates and perpetuates aortic aneurysms, including effects of AngII on a diverse array of cell types and mediators. These experimental findings are complemented in humans by genetic association studies and retrospective analyses of clinical data that generally support a role of the RAS in both AAAs and TAAs. Given the lack of a validated pharmacological therapy for any form of aortic aneurysm, there is a pressing need to determine whether the consistent findings on the role of the RAS in animal models are translatable to humans afflicted with these diseases. The present review compiles the recent literature that has shown the RAS as a critical component in the pathogenesis of aortic aneurysms. PMID:22788237

  16. Subcutaneous Angiotensin II Infusion using Osmotic Pumps Induces Aortic Aneurysms in Mice.

    PubMed

    Lu, Hong; Howatt, Deborah A; Balakrishnan, Anju; Moorleghen, Jessica J; Rateri, Debra L; Cassis, Lisa A; Daugherty, Alan

    2015-01-01

    Osmotic pumps continuously deliver compounds at a constant rate into small animals. This article introduces a standard protocol used to induce aortic aneurysms via subcutaneous infusion of angiotensin II (AngII) from implanted osmotic pumps. This protocol includes calculation of AngII amount and dissolution, osmotic pump filling, implantation of osmotic pumps subcutaneously, observation after pump implantation, and harvest of aortas to visualize aortic aneurysms in mice. Subcutaneous infusion of AngII through osmotic pumps following this protocol is a reliable and reproducible technique to induce both abdominal and thoracic aortic aneurysms in mice. Infusion durations range from a few days to several months based on the purpose of the study. AngII 1,000 ng/kg/min is sufficient to provide maximal effects on abdominal aortic aneurysmal formation in male hypercholesterolemic mouse models such as apolipoprotein E deficient or low-density lipoprotein receptor deficient mice. Incidence of abdominal aortic aneurysms induced by AngII infusion via osmotic pumps is 5-10 times lower in female hypercholesterolemic mice and also lower in both genders of normocholesterolemic mice. In contrast, AngII-induced thoracic aortic aneurysms in mice are not hypercholesterolemia or gender-dependent. Importantly, multiple features of this mouse model recapitulate those of human aortic aneurysms. PMID:26436287

  17. Neurofibromin Deficient Myeloid Cells are Critical Mediators of Aneurysm Formation In Vivo

    PubMed Central

    Li, Fang; Downing, Brandon D.; Smiley, Lucy C.; Mund, Julie A.; DiStasi, Matthew R.; Bessler, Waylan K.; Sarchet, Kara N.; Hinds, Daniel M.; Kamendulis, Lisa M.; Hingtgen, Cynthia M.; Case, Jamie; Clapp, D. Wade; Conway, Simon J.; Stansfield, Brian K.; Ingram, David A.

    2014-01-01

    Background Neurofibromatosis Type 1 (NF1) is a genetic disorder resulting from mutations in the NF1 tumor suppressor gene. Neurofibromin, the protein product of NF1, functions as a negative regulator of Ras activity in circulating hematopoietic and vascular wall cells, which are critical for maintaining vessel wall homeostasis. NF1 patients have evidence of chronic inflammation resulting in development of premature cardiovascular disease, including arterial aneurysms, which may manifest as sudden death. However, the molecular pathogenesis of NF1 aneurysm formation is unknown. Method and Results Utilizing an angiotensin II-induced aneurysm model, we demonstrate that heterozygous inactivation of Nf1 (Nf1+/−) enhanced aneurysm formation with myeloid cell infiltration and increased oxidative stress in the vessel wall. Using lineage-restricted transgenic mice, we show loss of a single Nf1 allele in myeloid cells is sufficient to recapitulate the Nf1+/− aneurysm phenotype in vivo. Finally, oral administration of simvastatin or the antioxidant apocynin, reduced aneurysm formation in Nf1+/− mice. Conclusion These data provide genetic and pharmacologic evidence that Nf1+/− myeloid cells are the cellular triggers for aneurysm formation in a novel model of NF1 vasculopathy and provide a potential therapeutic target. PMID:24370551

  18. A Model for Assessing Institutional Effectiveness

    ERIC Educational Resources Information Center

    Volkwein, J. Fredericks

    2010-01-01

    In this chapter, the author proposes a model for assessing institutional effectiveness. The Volkwein model for assessing institutional effectiveness consists of five parts that summarize the steps for assessing institutions, programs, faculty, and students. The first step in the model distinguishes the dual purposes of institutional effectiveness:…

  19. Endovascular Repair of Thoracic Aortic Aneurysms

    PubMed Central

    Findeiss, Laura K.; Cody, Michael E.

    2011-01-01

    Degenerative aneurysms of the thoracic aorta are increasing in prevalence; open repair of descending thoracic aortic aneurysms is associated with high rates of morbidity and mortality. Repair of isolated descending thoracic aortic aneurysms using stent grafts was introduced in 1995, and in an anatomically suitable subgroup of patients with thoracic aortic aneurysm, repair with endovascular stent graft provides favorable outcomes, with decreased perioperative morbidity and mortality relative to open repair. The cornerstones of successful thoracic endovascular aneurysm repair are appropriate patient selection, thorough preprocedural planning, and cautious procedural execution, the elements of which are discussed here. PMID:22379281

  20. Iatrogenic cortical aneurysm post-craniotomy.

    PubMed

    Zanini, Marco Antonio; Borges, Rodrigo Almeida; Nunes Aquino, Gustavo Henrique; de Freitas, Carlos Clayton Macedo

    2010-04-01

    Taking into account the number of craniotomies performed every day around the world, iatrogenic aneurysm post-craniotomy is extremely rare with only anecdotal cases reported in literature. We report an iatrogenic aneurysm affecting a cortical vessel which probably developed during dural closure of a conventional craniotomy. The aneurysm was discovered 6 months after surgery on a routine control angiography. The patient was successfully treated by trapping the parent vessel and excising the aneurysm. Histopathological findings were compatible with a true type of traumatic aneurysm. The possibility of this rare condition occurring highlights the risk of arterial injury during craniotomy. PMID:20121386

  1. Bilateral asymptomatic giant renal artery aneurysm

    PubMed Central

    Özkan, G; Ulusoy, Ş; Dinç, H; Kaynar, K; Sönmez, B; Akagündüz, K

    2011-01-01

    The incidence of renal artery aneurysm is very low. Approximately in 20% of these patients hypertension is observed. The diameter of aneurysm increases with accompanying complication rates. The most feared complication is rupture. The risk of rupture also increases with the diameter of aneurysm. We report an aneurysm with the biggest diameter reported in the literature. The patient had a 12 cm-diameter of aneurysm in one kidney and did not show any symptoms including hypertension until she was seventy years old. PMID:22435028

  2. Surgical Resection of a Giant Coronary Aneurysm.

    PubMed

    Mehall, John R; Verlare, Jordan L

    2015-06-01

    Coronary aneurysms are quite uncommon, and those qualifying as giant aneurysms are even more so. Currently, no standardized treatment protocol exists. We report the case of a 46-year-old man presenting with clinical signs and symptoms of acute myocardial infarction who was found to have a giant coronary aneurysm. The patient was initially evaluated with a computed tomography angiogram, which revealed a 9-cm aneurysm of the left circumflex coronary artery. Surgical resection of the aneurysm, ligation of the proximal circumflex artery, and bypass using the left internal mammary artery to vascularize the proximal circumflex artery was performed. PMID:26046882

  3. A combined vascular surgical and clinical genetics approach to diffuse aneurysmal disease.

    PubMed

    Jones, K A; Choong, A M T L; Canham, N; Renton, S; Pollitt, R; Nesbitt, M; Kopcke, D; Islam, L; Buckley, J; Ghali, N; Vandersteen, A

    2015-07-01

    We report two patients who presented with extensive aneurysmal disease, in association with minimal external physical signs. Patient 1 remained genetically undiagnosed despite multiple structural, biochemical and genetic investigations. He made a good recovery following surgery for popliteal and left axillary artery aneurysms. Patient 2 was diagnosed with vascular type Ehlers-Danlos syndrome, associated with a high degree of tissue and blood vessel fragility, and is being managed conservatively. Early multidisciplinary assessment of such patients facilitates accurate diagnosis and management. PMID:26264107

  4. Behavior model for performance assessment.

    SciTech Connect

    Borwn-VanHoozer, S. A.

    1999-07-23

    Every individual channels information differently based on their preference of the sensory modality or representational system (visual auditory or kinesthetic) we tend to favor most (our primary representational system (PRS)). Therefore, some of us access and store our information primarily visually first, some auditorily, and others kinesthetically (through feel and touch); which in turn establishes our information processing patterns and strategies and external to internal (and subsequently vice versa) experiential language representation. Because of the different ways we channel our information, each of us will respond differently to a task--the way we gather and process the external information (input), our response time (process), and the outcome (behavior). Traditional human models of decision making and response time focus on perception, cognitive and motor systems stimulated and influenced by the three sensory modalities, visual, auditory and kinesthetic. For us, these are the building blocks to knowing how someone is thinking. Being aware of what is taking place and how to ask questions is essential in assessing performance toward reducing human errors. Existing models give predications based on time values or response times for a particular event, and may be summed and averaged for a generalization of behavior(s). However, by our not establishing a basic understanding of the foundation of how the behavior was predicated through a decision making strategy process, predicative models are overall inefficient in their analysis of the means by which behavior was generated. What is seen is the end result.

  5. Trials and tribulations: an evidence-based approach to aneurysm treatment.

    PubMed

    Sorenson, Thomas; Lanzino, Giuseppe

    2016-03-01

    Since the introduction of embolic coils in the early 1990s, endovascular treatment has gained much traction for use when treating ruptured and unruptured intracranial aneurysms. Three prospective studies have been conducted comparing endovascular coil embolization versus clipping for ruptured intracranial aneurysms. The first study took place in Finland and was the first head-to-head look at treating ruptured aneurysms by either endovascular coiling or surgical clipping. Results from this study suggested better functional outcome after endovascular treatment than surgery at the expenses of higher rates of incomplete aneurysm occlusion. The second largest and only multicenter study was the International Subarachnoid Aneurysm Trial (ISAT). The ISAT took place across Europe and was the first large-scale comparison between endovascular and surgical treatments. The results from this study caused a major opinion shift across the world in regards to optimal treatment of ruptured aneurysms. Additionally, the quantity of data from this study allowed for many subgroup analyses to be made. However, to assess the generalizability of the ISAT study, the Barrow Neurological Institute investigators conducted a single-center study. The intent of this latter study was to remove any potential bias and preselection by enrolling every consenting patient that presented with the designated pathology without any exclusion. However, this enrollment strategy resulted in a high percentage of patients with aneurysms not suitable for endovascular therapy being assigned to the coil group which in turn resulted in a high rate of turn over from the endovascular to the surgical arm of the study. Despite, these limitations, this latter trial presented similar results as the Kuopio and ISAT. Although each of these trials was not methodologically flawless, the combined results from all three suggest that endovascular treatment of ruptured aneurysms suitable for this treatment strategy results in

  6. Safety and efficacy of aneurysm treatment with WEB: results of the WEBCAST study.

    PubMed

    Pierot, Laurent; Costalat, Vincent; Moret, Jacques; Szikora, Istvan; Klisch, Joachim; Herbreteau, Denis; Holtmannspötter, Markus; Weber, Werner; Januel, Anne-Christine; Liebig, Thomas; Sychra, Vojtech; Strasilla, Christoph; Cognard, Christophe; Bonafé, Alain; Molyneux, Andrew; Byrne, James V; Spelle, Laurent

    2016-05-01

    OBJECT WEB is an innovative intrasaccular treatment for intracranial aneurysms. Preliminary series have shown good safety and efficacy. The WEB Clinical Assessment of Intrasaccular Aneurysm Therapy (WEBCAST) trial is a prospective European trial evaluating the safety and efficacy of WEB in wide-neck bifurcation aneurysms. METHODS Patients with wide-neck bifurcation aneurysms for which WEB treatment was indicated were included in this multicentergood clinical practices study. Clinical data including adverse events and clinical status at 1 and 6 months were collected and independently analyzed by a medical monitor. Six-month follow-up digital subtraction angiography was also performed and independently analyzed by a core laboratory. Success was defined at 6 months as complete occlusion or stable neck remnant, no worsening in angiographic appearance from postprocedure, and no retreatment performed or planned. RESULTS Ten European neurointerventional centers enrolled 51 patients with 51 aneurysms. Treatment with WEB was achieved in 48 of 51 aneurysms (94.1%). Adjunctive implants (coils/stents) were used in 4 of 48 aneurysms (8.3%). Thromboembolic events were observed in 9 of 51 patients (17.6%), resulting in a permanent deficit (modified Rankin Scale [mRS] Score 1) in 1 patient (2.0%). Intraoperative rupture was not observed. Morbidity (mRS score > 2) and mortality were 2.0% (1 of 51 patients, related to rupture status on entry to study) and 0.0% at 1 month, respectively. Success was achieved at 6 months in 85.4% of patients treated with WEB: 23 of 41 patients (56.1%) had complete occlusion, 12 of 41 (29.3%) had a neck remnant, and 6 of 41 (14.6%) had an aneurysm remnant. CONCLUSIONS The WEBCAST study showed good procedural and short-term safety of aneurysm treatment with WEB and good 6-month anatomical results. PMID:26381253

  7. Management of Symptomatic Venous Aneurysm

    PubMed Central

    Gabrielli, Roberto; Rosati, Maria Sofia; Siani, Andrea; Irace, Luigi

    2012-01-01

    Venous aneurysms (VAs) have been described in quite of all the major veins. They represent uncommon events but often life-threatening because of pulmonary or paradoxical embolism. We describe our twelve patients' series with acute pulmonary emboli due to venous aneurysm thrombosis. Our experience underlines the importance of a multilevel case-by-case approach and the immediate venous lower limbs duplex scan evaluation in pulmonary embolism events. Our data confirm that anticoagulant alone is not effective in preventing pulmonary embolism. We believe that all the VAs of the deep venous system of the extremities should be treated with surgery as well as symptomatic superficial venous aneurysm. A simple excision can significantly improve symptoms and prevent pulmonary embolism. PMID:22566766

  8. Management of symptomatic venous aneurysm.

    PubMed

    Gabrielli, Roberto; Rosati, Maria Sofia; Siani, Andrea; Irace, Luigi

    2012-01-01

    Venous aneurysms (VAs) have been described in quite of all the major veins. They represent uncommon events but often life-threatening because of pulmonary or paradoxical embolism. We describe our twelve patients' series with acute pulmonary emboli due to venous aneurysm thrombosis. Our experience underlines the importance of a multilevel case-by-case approach and the immediate venous lower limbs duplex scan evaluation in pulmonary embolism events. Our data confirm that anticoagulant alone is not effective in preventing pulmonary embolism. We believe that all the VAs of the deep venous system of the extremities should be treated with surgery as well as symptomatic superficial venous aneurysm. A simple excision can significantly improve symptoms and prevent pulmonary embolism. PMID:22566766

  9. Thoracic aortic aneurysms and pregnancy.

    PubMed

    Coulon, Capucine

    2015-11-01

    Half of acute aortic dissection in women under the age of 40 occurs during pregnancy or peripartum period. Marfan syndrome is the most common syndromic presentation of ascending aortic aneurysm, but other syndromes such as vascular Ehlers-Danlos syndrome, Loeys-Dietz syndrome and Turner syndrome also have ascending aortic aneurysms and the associated cardiovascular risk of aortic dissection and rupture. Management of aortic root aneurysm has been established in recent recommendations, even if levels of evidence are weak. Pregnancy and postpartum period should be followed very closely and determined to be at high risk. Guidelines suggest that women with aortopathy should be counseled against the risk of pregnancy and about the heritable nature of the disease prior to pregnancy. PMID:26454306

  10. [What is the evidence to support screening for abdominal aortic aneurysm and what is the role of the primary care physicians ?].

    PubMed

    Motte, S

    2015-09-01

    Abdominal aortic aneurysm is a serious and potentially fatal vascular disease. Surgical intervention is typically reserved for aneurysms 55 mm in diameter or greater. Randomized trials addressing the efficacy of ultrasound screening for abdominal aortic aneurysm have shown that screening reduced aneurysm-related mortality in men but not in women who have a lower prevalence of abdominal aortic aneurysm. Screening with ultrasonography is recommended in men 65 to 75 years of age with a history of smoking and is suggested in women in this age group if they have risk factors such as smoking and hypertension. Men and women with a family history of abdominal aortic aneurysm should undergo screening as well. Persons who have a stable aneurysm should undergo regular surveillance or operative intervention depending on aneurysm size. Primary care physicians have to play a key role before prescribing screening in assessing risks and benefits of repair in each patient. For persons with an aneurysm of less than 55 mm in diameter, the primary care physicians should provide information and interventions for the prevention of cardiovascular disease such as screening for and treating hypertension and interventions for tobacco cessation for smokers. The family physicians should also ensure that radiological monitoring of aneurysms is complete. PMID:26591322

  11. The hemodynamics in intracranial aneurysm ruptured region with active contrast leakage during computed tomography angiography

    NASA Astrophysics Data System (ADS)

    Li, Ming-Lung; Wang, Yi-Chou; Liou, Tong-Miin; Lin, Chao-An

    2014-10-01

    Precise locations of rupture region under contrast agent leakage of five ruptured cerebral artery aneurysms during computed tomography angiography, which is to our knowledge for the first time, were successfully identified among 101 patients. These, together with numerical simulations based on the reconstructed aneurysmal models, were used to analyze hemodynamic parameters of aneurysms under different cardiac cyclic flow rates. For side wall type aneurysms, different inlet flow rates have mild influences on the shear stresses distributions. On the other hand, for branch type aneurysms, the predicted wall shear stress (WSS) correlates strongly with the increase of inlet vessel velocity. The mean and time averaged WSSes at rupture regions are found to be lower than those over the surface of the aneurysms. Also, the levels of the oscillatory shear index (OSI) are higher than the reported threshold value, supporting the assertion that high OSI correlates with rupture of the aneurysm. However, the present results also indicate that OSI level at the rupture region is relatively lower.

  12. Abdominal Aortic Aneurysms and Risk Factors for Adverse Events.

    PubMed

    Ahmed, Raheel; Ghoorah, Kuldeepa; Kunadian, Vijay

    2016-01-01

    An abdominal aortic aneurysm (AAA) is a focal full thickness dilatation of the abdominal aorta, greater than 1.5 times its normal diameter. Although some patients with AAA experience back or abdominal pain, most remain asymptomatic until rupture. The prognosis after AAA rupture is poor. Management strategies for patients with asymptomatic AAAs include risk factor reduction, such as smoking cessation, optimizing antihypertensive treatment, and treating dyslipidemia, as well as surveillance by ultrasound. Currently, aneurysm diameter alone is often used to assess risk of rupture. Once the aneurysm diameter reaches 5.5 cm, the risk of rupture is considered greater than the risk of intervention and elective aneurysm repair is undertaken. There is increasing interest in detecting AAAs early, and national screening programs are now in place. Furthermore, there is increasing research interest in biomarkers, genetics, and functional imaging to improve detection of AAAs at risk of progression and rupture. In this review, we discuss risk factors for AAA rupture, which should be considered during the management process, to advance current deficiencies in management pathways. PMID:25580705

  13. Intracranial Pseudoaneurysms, Fusiform Aneurysms and Carotid-Cavernous Fistulas

    PubMed Central

    Lv, Xianli; Jiang, Chuhan; Li, Youxiang; Lv, Ming; Zhang, Jingbo; Wu, Zhongxue

    2008-01-01

    Summary The study assessed the effectiveness and safety of endovascular covered stents in the management of intracranial pseudoaneurysms, fusiform aneurysms and direct carotid-cavernous fistulas. Fourteen endovascular covered stents were used to repair three pseudoaneurysms, six fu-siform aneurysms and six direct carotid-cavernous fistulas. Aneurysms were in the carotid artery in seven cases, in the vertebral artery two cases. It was not possible to treat two additional cases transcutaneously for technical reasons
2/15. Percutaneous closure of the lesions with an endovascular covered stent was successful in 13 of 15 cases. Initial follow-up showed good stent patency. No complications were observed after stent implantation. During follow-up, stent thromboses were detected in two of nine patients with follow-up digital subtracted angiography. One carotid-cavernous fistula of Barrow Type A transformed into Barrow Type D at nine month follow-up study was cured with a procudure of Onyx-18 injection. Endovascular covered stents may be an option for percutaneous closure of intracranial pseudoaneurysms, fusiform aneurysms and direct carotid-cavernous fistulas. Endoluminal vascular repair with covered stents offers an alternative therapeutic approach to conventional modalities. PMID:20557743

  14. Comparison of two stents in modifying cerebral aneurysm hemodynamics.

    PubMed

    Kim, Minsuok; Taulbee, Dale B; Tremmel, Markus; Meng, Hui

    2008-05-01

    There is a general lack of quantitative understanding about how specific design features of endovascular stents (struts and mesh design, porosity) affect the hemodynamics in intracranial aneurysms. To shed light on this issue, we studied two commercial high-porosity stents (Tristar stent and Wallstent) in aneurysm models of varying vessel curvature as well as in a patient-specific model using Computational Fluid Dynamics. We investigated how these stents modify hemodynamic parameters such as aneurysmal inflow rate, stasis, and wall shear stress, and how such changes are related to the specific designs. We found that the flow damping effect of stents and resulting aneurysmal stasis and wall shear stress are strongly influenced by stent porosity, strut design, and mesh hole shape. We also confirmed that the damping effect is significantly reduced at higher vessel curvatures, which indicates limited usefulness of high-porosity stents as a stand-alone treatment. Finally, we showed that the stasis-inducing performance of stents in 3D geometries can be predicted from the hydraulic resistance of their flat mesh screens. From this, we propose a methodology to cost-effectively compare different stent designs before running a full 3D simulation. PMID:18264766

  15. Comparison of Two Stents in Modifying Cerebral Aneurysm Hemodynamics

    PubMed Central

    Kim, Minsuok; Taulbee, Dale B.; Tremmel, Markus; Meng, Hui

    2009-01-01

    There is a general lack of quantitative understanding about how specific design features of endovascular stents (struts and mesh design, porosity) affect the hemodynamics in intracranial aneurysms. To shed light on this issue, we studied two commercial high-porosity stents (Tristar stent™ and Wallstent®) in aneurysm models of varying vessel curvature as well as in a patient-specific model using Computational Fluid Dynamics. We investigated how these stents modify hemodynamic parameters such as aneurysmal inflow rate, stasis, and wall shear stress, and how such changes are related to the specific designs. We found that the flow damping effect of stents and resulting aneurysmal stasis and wall shear stress are strongly influenced by stent porosity, strut design, and mesh hole shape. We also confirmed that the damping effect is significantly reduced at higher vessel curvatures, which indicates limited usefulness of high-porosity stents as a stand-alone treatment. Finally, we showed that the stasis-inducing performance of stents in 3D geometries can be predicted from the hydraulic resistance of their flat mesh screens. From this, we propose a methodology to cost-effectively compare different stent designs before running a full 3D simulation. PMID:18264766

  16. Real-Time Evaluation of Anterior Choroidal Artery Patency During Aneurysm Clipping

    PubMed Central

    Zhao, David Y; Nayar, Vikram V; Kalhorn, Christopher G; McGrail, Kevin M; Mandir, Allen S; Minahan, Robert E

    2016-01-01

    Inadvertent occlusion of the anterior choroidal artery during aneurysm clipping can cause a disabling stroke in minutes. We evaluate the clinical utility of direct cortical motor evoked potential (MEP) monitoring during aneurysm clipping, as a real-time assessment of arterial patency, prior to performing indocyanine green videoangiography.   Direct cortical MEPs were recorded in seven patients undergoing surgery for aneurysms that involved or abutted the anterior choroidal artery. The aneurysms clipped in those seven patients included four anterior choroidal artery aneurysms and six posterior communicating artery aneurysms. Serial MEP recordings were performed during the intradural dissection, aneurysm exposure, and clip placement. A significant change in MEPs after clip placement would prompt immediate inspection and removal or repositioning of the clip. If the clip placement appeared satisfactory and MEP recordings were stable, then an intraoperative indocyanine green videoangiogram was performed to confirm obliteration of the aneurysm and patency of the arteries.  Seven patients underwent successful clipping of anterior choroidal artery aneurysms and posterior communicating artery aneurysms using direct cortical MEP monitoring, with good clinical and radiographic outcomes. In six patients, no changes in MEP amplitudes were observed following permanent clip placement. In one patient, a profound decrease in MEP amplitude occurred 220 seconds after placement of a permanent clip on a large posterior communicating aneurysm. An inspection revealed that the anterior choroidal artery was kinked. The clip was immediately removed, and the MEP signals returned to baseline shortly thereafter. A clip was then optimally placed, and the patient awoke without neurologic deficit.  Direct cortical MEPs are a useful adjunct to standard electrophysiologic monitoring in aneurysm surgery, particularly when the anterior choroidal artery or lenticulostriate arteries are at

  17. Recovery of Third Nerve Palsy after Endovascular Packing of Internal Carotid-Posterior Communicating Artery Aneurysms

    PubMed Central

    Mavilio, N.; Pisani, R.; Rivano, C.; Testa, V.; Spaziante, R.; Rosa, M.

    2000-01-01

    Summary Endovascular packing of intracranial aneurysm with preservation of the parent vessel has become in many cases a valid alternative to surgical clipping. Regression of oculomotor disorders after clipping of internal carotid-posterior communicating artery (ICA-PCoA) aneurysms has been well assessed. This report focuses on the reversal of third nerve palsy after endovascular packing of ICA-PCoA aneurysms. To this end, clinical appearances, neuroradiological features, and endovascular interventional procedures of six treated patient are reported and discussed in the light of the very few previous case observations found in the literature. Results indicate that endovascular packing of ICA-PCoA aneurysms may produce effective recovery of correlated third nerve dysfunction. PMID:20667199

  18. The biaxial biomechanical behavior of abdominal aortic aneurysm tissue.

    PubMed

    O'Leary, Siobhan A; Healey, Donagh A; Kavanagh, Eamon G; Walsh, Michael T; McGloughlin, Tim M; Doyle, Barry J

    2014-12-01

    Rupture of the abdominal aortic aneurysm (AAA) occurs when the local wall stress exceeds the local wall strength. Knowledge of AAA wall mechanics plays a fundamental role in the development and advancement of AAA rupture risk assessment tools. Therefore, the aim of this study is to evaluate the biaxial mechanical properties of AAA tissue. Multiple biaxial test protocols were performed on AAA samples harvested from 28 patients undergoing open surgical repair. Both the Tangential Modulus (TM) and stretch ratio (λ) were recorded and compared in both the circumferential (ϴ) and longitudinal (L) directions at physiologically relevant stress levels, the influence of patient specific factors such as sex, age AAA diameter and status were examined. The biomechanical response was also fit to a hyperplastic material model. The AAA tissue was found to be anisotropic with a greater tendency to stiffen in the circumferential direction compared to the longitudinal direction. An anisotropic hyperelastic constitutive model represented the data well and the properties were not influenced by the investigated patient specific factors however, a future study utilizing a larger cohort of patients is warranted to confirm these findings. This work provides further insights on the biomechanical behavior of AAA and may be useful in the development of more reliable rupture risk assessment tools. PMID:25201606

  19. Molecular Imaging of Experimental Abdominal Aortic Aneurysms

    PubMed Central

    Ramaswamy, Aneesh K.; Hamilton, Mark; Joshi, Rucha V.; Kline, Benjamin P.; Li, Rui; Wang, Pu; Goergen, Craig J.

    2013-01-01

    Current laboratory research in the field of abdominal aortic aneurysm (AAA) disease often utilizes small animal experimental models induced by genetic manipulation or chemical application. This has led to the use and development of multiple high-resolution molecular imaging modalities capable of tracking disease progression, quantifying the role of inflammation, and evaluating the effects of potential therapeutics. In vivo imaging reduces the number of research animals used, provides molecular and cellular information, and allows for longitudinal studies, a necessity when tracking vessel expansion in a single animal. This review outlines developments of both established and emerging molecular imaging techniques used to study AAA disease. Beyond the typical modalities used for anatomical imaging, which include ultrasound (US) and computed tomography (CT), previous molecular imaging efforts have used magnetic resonance (MR), near-infrared fluorescence (NIRF), bioluminescence, single-photon emission computed tomography (SPECT), and positron emission tomography (PET). Mouse and rat AAA models will hopefully provide insight into potential disease mechanisms, and the development of advanced molecular imaging techniques, if clinically useful, may have translational potential. These efforts could help improve the management of aneurysms and better evaluate the therapeutic potential of new treatments for human AAA disease. PMID:23737735

  20. Spinal axis imaging in non-aneurysmal subarachnoid hemorrhage: a prospective cohort study.

    PubMed

    Germans, Menno R; Coert, Bert A; Majoie, Charles B L M; van den Berg, René; Verbaan, Dagmar; Vandertop, W Peter

    2014-11-01

    In 15 % of all spontaneous subarachnoid hemorrhages (SAH), no intracranial vascular pathology is found. Those non-aneurysmal hemorrhages are categorized into perimesencephalic SAH (PMSAH) and non-perimesencephalic SAH (NPSAH). Searching for spinal pathology might reveal a cause for the hemorrhage in some patients. Our goal was to assess the yield of magnetic resonance (MR) imaging of the complete spinal axis in search for a spinal origin in non-aneurysmal SAH. In a prospective, observational study at a tertiary SAH referral center, we assessed clinical and radiological characteristics of patients who consecutively presented with spontaneous non-aneurysmal SAH, diagnosed by computed tomography (CT) or lumbar puncture, and negative CT angiography and digital subtraction angiography (DSA). Eligible patients were enrolled for investigation of the complete spinal axis by standard T1- and T2-weighted MR-imaging. Ninety-seven non-aneurysmal SAH patients were included in the study. Baseline characteristics were comparable between PMSAH and NPSAH patients. DSA and spinal MR-imaging were performed in 95 and 91 % of patients, respectively. This revealed one lumbar ependymoma in a 43-year-old male who was diagnosed by LP (yield 1 %). No spinal origin for the SAH was found in 51 PMSAH patients. The yield of MR-imaging of the complete spinal axis in spontaneous non-aneurysmal SAH patients is low. Routine radiological investigation of the spinal axis in non-aneurysmal SAH patients is therefore not recommended. PMID:25182702

  1. Integrated Environmental Modeling: Quantitative Microbial Risk Assessment

    EPA Science Inventory

    The presentation discusses the need for microbial assessments and presents a road map associated with quantitative microbial risk assessments, through an integrated environmental modeling approach. A brief introduction and the strengths of the current knowledge are illustrated. W...

  2. EPA CENTER FOR EXPOSURE ASSESSMENT MODELING (CEAM)

    EPA Science Inventory

    The EPA Center for Exposure Assessment Modeling (CEAM) supports the Agency and professional community in environmental, risk-based decision-making by expanding their applications expertise for quantitatively assessing pollutant exposure via aquatic, terrestrial, and multimedia pa...

  3. Giant Serpentine Aneurysms: Multidisciplinary Management

    PubMed Central

    Anshun, W.; Feng, L.; Daming, W.

    2000-01-01

    Summary Sixty-five cases of intracranial giant serpentine aneurysms (GSΛs), including 61 cases reported in the literature and four additional cases presented in this study were reviewed. The clinical presentation, possible causes, natural history, and especially management of GSAs are discussed with emphasis on the need for aggressive intervention and multidisciplinary management. PMID:20667180

  4. QUANTIFICATION OF HEMODYNAMIC CHANGES INDUCED BY VIRTUAL PLACEMENT OF MULTIPLE STENTS ACROSS A WIDE-NECKED BASILAR TRUNK ANEURYSM

    PubMed Central

    Kim, Minsuok; Levy, Elad I.; Meng, Hui; Hopkins, L. Nelson

    2009-01-01

    OBJECTIVE The porous intravascular stents that are currently available may not cause complete aneurysm thrombosis and may therefore fail to provide durable protection against aneurysm rupture when used as a sole treatment modality. The goal of this study was to quantify the effects of porous stents on aneurysm hemodynamics using computational fluid dynamics. METHODS The geometry of a wide-necked saccular basilar trunk aneurysm was reconstructed from a patient′s computed tomographic angiography images. Three commercial stents (Neuroform2; Boston Scientific/Target, San Leandro, CA; Wingspan; Boston Scientific, Fremont, CA; and Vision; Guidant Corp., Santa Clara, CA) were modeled. Various combinations of one to three stents were virtually conformed to fit into the vessel lumen and placed across the aneurysm orifice. An unstented aneurysm served as a control. Computational fluid dynamics analysis was performed to calculate the hemodynamic parameters considered important in aneurysm pathogenesis and thrombosis for each of the models. RESULTS The complex flow pattern observed in the unstented aneurysm was suppressed by stenting. Stent placement lowered the wall shear stress in the aneurysm, and this effect was increased by additional stent deployment. Turnover time was moderately increased after single- and double-stent placement and markedly increased after three stents were placed. The influence of stent design on hemodynamic parameters was more significant in double-stented models than in other models. CONCLUSION Aneurysm hemodynamic parameters were significantly modified by placement of multiple stents. Because the associated modifications may be helpful as well as harmful in terms of rupture risk, use of this technique requires careful consideration. PMID:18162911

  5. Application of ''Earl's Assessment "as", Assessment "for", and Assessment "of" Learning Model'' with Orthopaedic Assessment Clinical Competence

    ERIC Educational Resources Information Center

    Lafave, Mark R.; Katz, Larry; Vaughn, Norman

    2013-01-01

    Context: In order to study the efficacy of assessment methods, a theoretical framework of Earl's model of assessment was introduced. Objective: (1) Introduce the predictive learning assessment model (PLAM) as an application of Earl's model of learning; (2) test Earl's model of learning through the use of the Standardized Orthopedic Assessment Tool…

  6. Pain assessment in animal models of osteoarthritis.

    PubMed

    Piel, Margaret J; Kroin, Jeffrey S; van Wijnen, Andre J; Kc, Ranjan; Im, Hee-Jeong

    2014-03-10

    Assessment of pain in animal models of osteoarthritis is integral to interpretation of a model's utility in representing the clinical condition, and enabling accurate translational medicine. Here we describe behavioral pain assessments available for small and large experimental osteoarthritic pain animal models. PMID:24333346

  7. [Abdominal aortic aneurysm treated by endovascular surgery: a case report].

    PubMed

    Alconero-Camarero, Ana Rosa; Cobo-Sánchez, José Luis; Casaus-Pérez, María; García-Campo, María Elena; García-Zarrabeitia, María José; Calvo-Diez, Marta; Mirones-Valdeolivas, Luz Elena

    2008-01-01

    An aneurysm is an abnormal dilation or irreversible convex of a portion of an artery. The most common site of aneurysms is the abdominal aorta and their appearance is often due to degeneration of the arterial wall, associated with atherosclerosis and favored by risk factors such as smoking and hypertension, among others. Left untreated, aneurysm of the abdominal aorta usually leads to rupture. Treatment is surgical, consisting of the introduction of a prosthesis, composed basically of a stent and an introducer, into the aorta. We report the case of a person diagnosed with abdominal aortic aneurysm in a routine examination who was admitted for ambulatory surgical treatment. We designed a nursing care plan, following Virginia Henderson's conceptual model. The care plan was divided into 2 parts, a first preoperative phase and a second postimplantation or monitoring phase. The care plan contained the principal nursing diagnoses, based on the taxonomies of the North American Nursing Diagnosis Association (NANDA), nursing interventions classification (NIC) and nursing outcomes classifications (NOC), and collaboration problems/potential complications. The patient was discharged to home after contact was made with his reference nurse in the primary health center, since during the hospital phase, some NOC indicators remained unresolved. PMID:18448049

  8. Cavitation instability as a trigger of aneurysm rupture.

    PubMed

    Volokh, K Y

    2015-10-01

    Aneurysm formation and growth is accompanied by microstructural alterations in the arterial wall. Particularly, the loss of elastin may lead to tissue disintegration and appearance of voids or cavities at the micron scale. Unstable growth and coalescence of voids may be a predecessor and trigger for the onset of macroscopic cracks. In the present work, we analyze the instability of membrane (2D) and bulk (3D) voids under hydrostatic tension by using two experimentally calibrated constitutive models of abdominal aortic aneurysm enhanced with energy limiters. The limiters provide the saturation value for the strain energy, which indicates the maximum energy that can be stored and dissipated by an infinitesimal material volume. We find that the unstable growth of voids can start when the critical stress is considerably less than the aneurysm strength. Moreover, this critical stress may even approach the arterial wall stress in the physiological range. This finding suggests that cavitation instability can be a rational indicator of the aneurysm rupture. PMID:25637515

  9. The Numerical Study of the Hemodynamic Characteristics in the Patient-Specific Intracranial Aneurysms before and after Surgery

    PubMed Central

    Byun, Jun Soo; Choi, Sun-Young

    2016-01-01

    The patient-specific pre- and postsurgery cerebral arterial geometries in the study were reconstructed from computed tomography angiography (CTA). Three-dimensional computational fluid dynamics models were used to investigate the hemodynamic phenomena in the cerebral arteries before and after surgery of the aneurysm under realistic conditions. CFD simulations for laminar flow of incompressible Newtonian fluid were conducted by using commercial software, ANSYS v15, with the rigid vascular wall assumption. The study found that the flow patterns with the complex vortical structures inside the aneurysm were similar. We also found that the inflow jet streams were coming strongly in aneurysm sac in the presurgery models, while the flow patterns in postsurgery models were quite different from those in presurgery models. The average wall shear stress after surgery for model 1 was approximately three times greater than that before surgery, while it was about twenty times greater for model 2. The area of low WSS in the daughter saccular aneurysm region in model 2 is associated with aneurysm rupture. Thus the distribution of WSS in aneurysm region provides useful prediction for the risk of aneurysm rupture. PMID:27274764

  10. The Numerical Study of the Hemodynamic Characteristics in the Patient-Specific Intracranial Aneurysms before and after Surgery.

    PubMed

    Byun, Jun Soo; Choi, Sun-Young; Seo, Taewon

    2016-01-01

    The patient-specific pre- and postsurgery cerebral arterial geometries in the study were reconstructed from computed tomography angiography (CTA). Three-dimensional computational fluid dynamics models were used to investigate the hemodynamic phenomena in the cerebral arteries before and after surgery of the aneurysm under realistic conditions. CFD simulations for laminar flow of incompressible Newtonian fluid were conducted by using commercial software, ANSYS v15, with the rigid vascular wall assumption. The study found that the flow patterns with the complex vortical structures inside the aneurysm were similar. We also found that the inflow jet streams were coming strongly in aneurysm sac in the presurgery models, while the flow patterns in postsurgery models were quite different from those in presurgery models. The average wall shear stress after surgery for model 1 was approximately three times greater than that before surgery, while it was about twenty times greater for model 2. The area of low WSS in the daughter saccular aneurysm region in model 2 is associated with aneurysm rupture. Thus the distribution of WSS in aneurysm region provides useful prediction for the risk of aneurysm rupture. PMID:27274764

  11. A novel low profile wireless flow sensor to monitor hemodynamic changes in cerebral aneurysm

    NASA Astrophysics Data System (ADS)

    Chen, Yanfei; Jankowitz, Brian T.; Cho, Sung Kwon; Chun, Youngjae

    2015-03-01

    A proof of concept of low-profile flow sensor has been designed, fabricated, and subsequently tested to demonstrate its feasibility for monitoring hemodynamic changes in cerebral aneurysm. The prototype sensor contains three layers, i.e., a thin polyurethane layer was sandwiched between two sputter-deposited thin film nitinol layers (6μm thick). A novel superhydrophilic surface treatment was used to create hemocompatible surface of thin nitinol electrode layers. A finite element model was conducted using ANSYS Workbench 15.0 Static Structural to optimize the dimensions of flow sensor. A computational fluid dynamics calculations were performed using ANSYS Workbench Fluent to assess the flow velocity patterns within the aneurysm sac. We built a test platform with a z-axis translation stage and an S-beam load cell to compare the capacitance changes of the sensors with different parameters during deformation. Both LCR meter and oscilloscope were used to measure the capacitance and the resonant frequency shifts, respectively. The experimental compression tests demonstrated the linear relationship between the capacitance and applied compression force and decreasing the length, width and increasing the thickness improved the sensor sensitivity. The experimentally measured resonant frequency dropped from 12.7MHz to 12.48MHz, indicating a 0.22MHz shift with 200g ( 2N) compression force while the theoretical resonant frequency shifted 0.35MHz with 50g ( 0.5N). Our recent results demonstrated a feasibility of the low-profile flow sensor for monitoring haemodynamics in cerebral aneurysm region, as well as the efficacy of the use of the surface treated thin film nitinol for the low-profile sensor materials.

  12. General Considerations of Ruptured Abdominal Aortic Aneurysm: Ruptured Abdominal Aortic Aneurysm

    PubMed Central

    Lee, Chung Won; Bae, Miju; Chung, Sung Woon

    2015-01-01

    Although development of surgical technique and critical care, ruptured abdominal aortic aneurysm still carries a high mortality. In order to obtain good results, various efforts have been attempted. This paper reviews initial management of ruptured abdominal aortic aneurysm and discuss the key point open surgical repair and endovascular aneurysm repair. PMID:25705591

  13. A Literature Review of the Numerical Analysis of Abdominal Aortic Aneurysms Treated with Endovascular Stent Grafts

    PubMed Central

    Roy, David; Kauffmann, Claude; Delorme, Sébastien; Lerouge, Sophie; Cloutier, Guy; Soulez, Gilles

    2012-01-01

    The purpose of this paper is to present the basic principles and relevant advances in the computational modeling of abdominal aortic aneurysms and endovascular aneurysm repair, providing the community with up-to-date state of the art in terms of numerical analysis and biomechanics. Frameworks describing the mechanical behavior of the aortic wall already exist. However, intraluminal thrombus nonhomogeneous structure and porosity still need to be well characterized. Also, although the morphology and mechanical properties of calcifications have been investigated, their effects on wall stresses remain controversial. Computational fluid dynamics usually assumes a rigid artery wall, whereas fluid-structure interaction accounts for artery compliance but is still challenging since arteries and blood have similar densities. We discuss alternatives to fluid-structure interaction based on dynamic medical images that address patient-specific hemodynamics and geometries. We describe initial stresses, elastic boundary conditions, and statistical strength for rupture risk assessment. Special emphasis is accorded to workflow development, from the conversion of medical images into finite element models, to the simulation of catheter-aorta interactions and stent-graft deployment. Our purpose is also to elaborate the key ingredients leading to virtual stenting and endovascular repair planning that could improve the procedure and stent-grafts. PMID:22997538

  14. The coagulopathy associated with aortic aneurysms.

    PubMed Central

    Gétaz, E. P.; Louw, J. H.

    1977-01-01

    The authors in this article record their experience with eight-four patients with abdominal aortic aneurysms. Twenty-seven patients (32%) presented with ruptured aneurysms with an overall mortality of 56%. Of the unruptured aneurysms, 67% were operable with a mortality of 5.3%. The highest mortality amongst the patients with ruptured aneurysms was in the group who was shocked. In the group with ruptured aneurysms, of those in whom platelet counts were performed, 50% were abnormally low, and 56% had evidence of abnormal coagulation. Seventy per cent of those with coagulation abnormalities died. In the unruptured group 28.2% had thrombocytopenia but no other abnormalities of coagulation. All patients undergoint aneurysm resection should have a platelet count and a full clotting screen. Therapy should be directed to normalization of the coagulation system. PMID:593992

  15. Intracranial fungal aneurysm caused by Candida endocarditis.

    PubMed

    Takeda, S; Wakabayashi, K; Yamazaki, K; Miyakawa, T; Arai, H

    1998-01-01

    We describe a 67-year-old man who died 4 days after suffering a subarachnoid hemorrhage. Autopsy revealed a fresh subarachnoid hemorrhage and a ruptured fungal aneurysm near the trifurcation of the right middle cerebral artery. In comparison with 21 previously reported cases in which the fungal aneurysms were proved to be intracranial, the present case had several characteristic features: the causative fungus of the aneurysm was Candida (only one such case has been reported previously). The aneurysm was caused by direct Candida invasion of the arterial wall from the Candida embolus (previously reported aneurysms have been caused by direct invasion of the arterial wall during fungal meningitis). The source of the Candida was endocarditis (the main sources of fungus in previously reported cases have been sinusitis, dental extraction wounds, and some forms of surgery). We describe the features of this rare autopsy case of a ruptured fungal aneurysm caused by Candida originating from endocarditis and review the literature. PMID:9707334

  16. Angiographic analysis for phantom simulations of endovascular aneurysm treatments with a new fully retrievable asymmetric flow diverter

    NASA Astrophysics Data System (ADS)

    Yoganand, Aradhana; Wood, Rachel P.; Jimenez, Carlos; Siddiqui, Adnan; Snyder, Kenneth; Setlur Nagesh, S. V.; Bednarek, D. R.; Rudin, S.; Baier, Robert; Ionita, Ciprian N.

    2015-03-01

    Digital Subtraction Angiography (DSA) is the main diagnostic tool for intracranial aneurysms (IA) flow-diverter (FD) assisted treatment. Based on qualitative contrast flow evaluation, interventionists decide on subsequent steps. We developed a novel fully Retrievable Asymmetric Flow-Diverter (RAFD) which allows controlled deployment, repositioning and detachment achieve optimal flow diversion. The device has a small low porosity or solid region which is placed such that it would achieve maximum aneurysmal in-jet flow deflection with minimum impairment to adjacent vessels. We tested the new RAFD using a flow-loop with an idealized and a patient specific IA phantom in carotid-relevant physiological conditions. We positioned the deflection region at three locations: distally, center and proximally to the aneurysm orifice and analyzed aneurysm dome flow using DSA derived maps for mean transit time (MTT) and bolus arrival times (BAT). Comparison between treated and untreated (control) maps quantified the RAFD positioning effect. Average MTT, related to contrast presence in the aneurysm dome increased, indicating flow decoupling between the aneurysm and parent artery. Maximum effect was observed in the center and proximal position (~75%) of aneurysm models depending on their geometry. BAT maps, correlated well with inflow jet direction and magnitude. Reduction and jet dispersion as high as about 50% was observed for various treatments. We demonstrated the use of DSA data to guide the placement of the RAFD and showed that optimum flow diversion within the aneurysm dome is feasible. This could lead to more effective and a safer IA treatment using FDs.

  17. Neuropsychological outcome of patients operated upon for an intracranial aneurysm: analysis of general prognostic factors and of the effects of the location of the aneurysm.

    PubMed Central

    Desantis, A; Laiacona, M; Barbarotto, R; Basso, A; Villani, R; Spagnoli, D; Capitani, E

    1989-01-01

    One hundred and fourteen patients operated on for an intracranial aneurysm were followed up in order to investigate their neuropsychological outcome and to detect if there were any clinical features assessed around the time of operation that had prognostic significance. The neuropsychological examination evaluated language, apraxia, memory, intelligence and spatial ability. In the statistical analysis the overall severity of neuropsychological disorder was studied. "Late surgery timing" had a negative influence upon the neuropsychological outcome. There was not a difference between different aneurysm sites. Several patients with an apparently good clinical outcome showed neuropsychological deficits. Neuropsychological assessment is important in the evaluation of outcome after subarachnoid haemorrhage. PMID:2795039

  18. Numerical simulations of post-surgical flow and thrombosis in basilar artery aneurysms

    NASA Astrophysics Data System (ADS)

    Seshadhri, Santhosh; Lawton, Michael; Boussel, Loic; Saloner, David; Rayz, Vitaliy

    2015-11-01

    Surgical treatment of basilar artery aneurysms presents a major challenge since it is crucial to preserve the flow to the vital brainstem perforators branching of the basilar artery. In some cases, basilar aneurysms can be treated by clipping vessels in order to induce flow reduction and aneurysm thrombosis. Patient-specific CFD models can provide guidance to clinicians by simulating postoperative flows resulting from alternative surgeries. Several surgical options were evaluated for four basilar aneurysm patients. Patient-specific models were generated from preoperative MR angiography and MR velocimetry data and modified to simulate different procedures. The Navier-Stokes equations were solved with a finite-volume solver Fluent. Virtual contrast injections were simulated by solving the advection-diffusion equation in order to estimate the flow residence time and determine thrombus-prone regions. The results indicated on procedures that reduce intra-aneurysmal velocities and flow regions which are likely to become thrombosed. Thus CFD modeling can help improve the outcome of surgeries altering the flow in basilar aneurysms.

  19. Experimental study of physiological flow in a cerebral saccular tip aneurysm

    NASA Astrophysics Data System (ADS)

    Tsai, William; Savas, Omer; Ortega, Jason; Maitland, Duncan; Saloner, David

    2006-11-01

    Allowed to grow unchecked, a cerebral aneurysm may hemorrhage, leading to possible brain damage or death. Preventive treatment can alleviate this risk. The research presented will focus on cerebral saccular aneurysms. Flow visualization and particle image velocimetry are used at physiological input flow conditions in a simplified model geometry of a basilar artery bifurcation with a tip aneurysm. The results show the formation of vortical structures at the neck which impinge near the fundus and travel along the walls of the aneurysm. The goal of this research is to aid in the development of the implementation of laser-activated shape memory polymer devices for treatment. Future work on this project includes fluid flow and temperature studies during and post treatment.

  20. Periadventitial adipose-derived stem cell treatment halts elastase-induced abdominal aortic aneurysm progression

    PubMed Central

    Blose, Kory J; Ennis, Terri L; Arif, Batool; Weinbaum, Justin S; Curci, John A; Vorp, David A

    2014-01-01

    Aim Demonstrate that periadventitial delivery of adipose-derived mesenchymal stem cells (ADMSCs) slows aneurysm progression in an established murine elastase-perfusion model of abdominal aortic aneurysm (AAA). Materials & methods AAAs were induced in C57BL/6 mice using porcine elastase. During elastase perfusion, a delivery device consisting of a subcutaneous port, tubing and porous scaffold was implanted. Five days after elastase perfusion, 100,000 ADMSCs were delivered through the port to the aorta. After sacrifice at day 14, analyzed metrics included aortic diameter and structure of aortic elastin. Results ADMSC treated aneurysms had a smaller diameter and less fragmented elastin versus saline controls. Conclusion Periadventitial stem cell delivery prevented the expansion of an established aneurysm between days 5 and 14 after elastase perfusion. PMID:25431910

  1. Syphilitic aneurysm of the ascending aorta.

    PubMed

    Paulo, Nelson; Cascarejo, José; Vouga, Luís

    2012-02-01

    Syphilitic aortic aneurysm is a rare occurrence in the antibiotic era, making the diagnose assumption even more infrequent. Nonetheless, this pathology can appear and should be suspected in patients with aortic aneurysm. We report a case of a 57-year old patient who presents with neurosyphilis and, in the following study, a large ascending aorta aneurysm is identified. The authors discuss the diagnostic challenge, the epidemiologic concerns, surgical indication and treatment and subsequent follow-up. PMID:22159251

  2. Role of gender in types and frequency of coronary artery aneurysm and ectasia.

    PubMed

    Morrad, Baktash; Yazici, Huseyin Ugur; Aydar, Yuksel; Ovali, Cengiz; Nadir, Aydin

    2016-08-01

    This study aimed to evaluate the role of gender in types and frequency of coronary artery aneurysm and ectasia.We assessed retrospectively the angiography records of 6100 patients. At first, we mainly reviewed angiographic movies for the presence of coronary ectasia and/or aneurysm. Consequently, based on the number of the coronary artery involvement, the coronary ectasia and aneurysm were graded as mild if 1 coronary artery was involved and severe if 2 or more coronary arteries were involved. The location of ectasia and aneurysm was analyzed with respect to their isolated or combined location on various coronary arteries. The patients included in the present study were divided into 2 groups based on their gender as male and female. Then, we evaluated the impact of gender on severity and the location of the ectasia and aneurysm.The incidence of the aneurysm and ectasia was 3.5%. Among the patients with aneurysm and ectasia, 6.9% were male and 4.5% were female. Aneurysm and ectasia were evaluated together; their frequency was significantly higher in the male than female patients (P < 0.01). However, when their incidence was evaluated separately, coronary artery ectasia was markedly greater in male patients with regard to female patients (P < 0.01). Incidence of CAE presence on the RCA was significantly greater in males than females (2.7% vs 1.9%, P < 0.05).This study showed that incidence of CAE is more common in males than females. Particularly, frequency for the involvement of CAE on RCA and concurrently on 3 vessels is greater in male patients than female patients. PMID:27495054

  3. Role of gender in types and frequency of coronary artery aneurysm and ectasia

    PubMed Central

    Morrad, Baktash; Yazici, Huseyin Ugur; Aydar, Yuksel; Ovali, Cengiz; Nadir, Aydin

    2016-01-01

    Abstract This study aimed to evaluate the role of gender in types and frequency of coronary artery aneurysm and ectasia. We assessed retrospectively the angiography records of 6100 patients. At first, we mainly reviewed angiographic movies for the presence of coronary ectasia and/or aneurysm. Consequently, based on the number of the coronary artery involvement, the coronary ectasia and aneurysm were graded as mild if 1 coronary artery was involved and severe if 2 or more coronary arteries were involved. The location of ectasia and aneurysm was analyzed with respect to their isolated or combined location on various coronary arteries. The patients included in the present study were divided into 2 groups based on their gender as male and female. Then, we evaluated the impact of gender on severity and the location of the ectasia and aneurysm. The incidence of the aneurysm and ectasia was 3.5%. Among the patients with aneurysm and ectasia, 6.9% were male and 4.5% were female. Aneurysm and ectasia were evaluated together; their frequency was significantly higher in the male than female patients (P < 0.01). However, when their incidence was evaluated separately, coronary artery ectasia was markedly greater in male patients with regard to female patients (P < 0.01). Incidence of CAE presence on the RCA was significantly greater in males than females (2.7% vs 1.9%, P < 0.05). This study showed that incidence of CAE is more common in males than females. Particularly, frequency for the involvement of CAE on RCA and concurrently on 3 vessels is greater in male patients than female patients. PMID:27495054

  4. A Quantitative Software Risk Assessment Model

    NASA Technical Reports Server (NTRS)

    Lee, Alice

    2002-01-01

    This slide presentation reviews a risk assessment model as applied to software development. the presentation uses graphs to demonstrate basic concepts of software reliability. It also discusses the application to the risk model to the software development life cycle.

  5. Life-Threatening Surgery for Mycotic Aneurysm

    PubMed Central

    Mitrev, Zan K.; Anguseva, Tanja N.

    2013-01-01

    Infected aneurysm (or mycotic aneurysm) is defined as an infectious disease of the wall of an artery with formation of a blind, saccular out-pouching that is contiguous with the arterial lumen. Symptoms are frequently absent or nonspecific during the early stages. Once clinically presented, infected aneurysms are often at an advanced stage of development and associated with complications such as rupture. Nontreatment or delayed treatment of infected aneurysms has a poor outcome, with high morbidity and mortality rate via fulminant sepsis or hemorrhage. In clinically suspected cases, computed tomography is used for diagnosis. Urgent surgery, performed to prevent aortic rupture carries high morbidity and mortality rates. PMID:26798693

  6. Practical genetics of thoracic aortic aneurysm.

    PubMed

    Elefteriades, John A; Pomianowski, Pawel

    2013-01-01

    This chapter will provide a practical look at the rapidly evolving field regarding the genetics of thoracic aortic aneurysm. It will start with a look at the history of the genetics of thoracic aortic aneurysm and will then move on to elucidating the discovery of familial patterns of thoracic aortic aneurysm. We will next review the Mendelian genetics of transmission of thoracic aortic aneurysm. We will move on to the molecular genetics at the DNA level and finish with a discussion of the molecular genetics at the RNA level, including a promising investigational "RNA Signature" test that we have been developing at Yale. PMID:23993238

  7. Microsurgical clipping of an unruptured lenticulostriate aneurysm.

    PubMed

    Kalani, M Yashar S; Martirosyan, Nikolay L; Nakaji, Peter; Spetzler, Robert F

    2012-11-01

    Aneurysms of the lenticulostriate artery have been associated with hypertension, vasculopathy, tumors, and arteriovenous malformations. Although several cases of microsurgical treatment of ruptured lenticulostriate artery aneurysms have been reported, to our knowledge there is no published case of microsurgical treatment of an unruptured lenticulostriate artery aneurysm. We report a 66-year-old woman with a history of moyamoya disease, previously treated with a right-sided middle cerebral artery-to-superficial temporal artery bypass who presented with an unruptured aneurysm of a lenticulostriate artery. We report successful microsurgical treatment of this rare lesion and discuss the rationale for our treatment strategy. PMID:22925414

  8. An assessment model for atmospheric composition

    NASA Technical Reports Server (NTRS)

    Prather, Michael J. (Editor)

    1988-01-01

    Predicting future perturbations to global air quality and climate requires, as a prerequisite, prognostic models for the composition of the Earth's atmosphere. Such assessment models are needed to evaluate the impact on our environment of different social choices that affect emissions of the photochemically and radiatively important trace gases. Our presentation here of a prototype assessment model is intended to encourage public scientific discussions of the necessary components of the model and their interactions, with the recognition that models similar to this will likely be used by the Environmental Protection Agency and other regulatory agencies in order to assess the effect of changes in atmospheric composition on climate over the next century.

  9. The role of contrast-enhanced ultrasound imaging in the follow-up of patients post-endovascular aneurysm repair.

    PubMed

    Jawad, Nadia; Parker, Pamela; Lakshminarayan, Raghuram

    2016-02-01

    Endovascular aneurysm repair is a minimally invasive technique for the treatment of abdominal aortic aneurysms. Patients who undergo endovascular aneurysm repair are potentially at risk of developing problems related to the graft such as the development of endoleaks. Endoleaks can cause expansion of the aneurysmal sac, which can potentially lead to rupture. It is for this reason that lifelong surveillance of patients is required to assess the graft and the aneurysmal sac. This article discusses the role of contrast-enhanced ultrasound in the follow-up of patients post-endovascular aneurysm repair. Contrast-enhanced ultrasound is rapidly becoming a powerful, accurate and cost-effective tool to complement computed tomography in the follow-up of endovascular aneurysm repair patients. Real-time imaging of contrast filling into the arterial system means that contrast-enhanced ultrasound is an excellent problem-solving tool, particularly when assessing for the type and anatomy of endoleaks. In some instances, contrast-enhanced ultrasound can detect endoleaks when other modalities are equivocal. PMID:27433275

  10. Assessing and reducing hydrogeologic model uncertainty

    Technology Transfer Automated Retrieval System (TEKTRAN)

    NRC is sponsoring research that couples model abstraction techniques with model uncertainty assessment methods. Insights and information from this program will be useful in decision making by NRC staff, licensees and stakeholders in their assessment of subsurface radionuclide transport. All analytic...

  11. Novel mechanisms of abdominal aortic aneurysms.

    PubMed

    Lu, Hong; Rateri, Debra L; Bruemmer, Dennis; Cassis, Lisa A; Daugherty, Alan

    2012-10-01

    Abdominal aortic aneurysms (AAAs) are a common but asymptomatic disease that has high susceptibility to rupture. Current therapeutic options are limited to surgical procedures because no pharmacological approaches have been proven to decrease either expansion or rupture of human AAAs. The current dearth of effective medical treatment is attributed to insufficient understanding of the mechanisms underlying the initiation, propagation and rupture of AAAs. This review will emphasize recent advances in mechanistic studies that may provide insights into potential pharmacological treatments for this disease. While we primarily focus on recent salient findings, we also discuss mechanisms that continue to be controversial depending on models under study. Despite the progress on exploring mechanisms of experimental AAAs, ultimate validation of mechanisms will require completion of prospective double-blinded clinical trials. In addition, we advocate increased emphasis of collaborative studies using animal models and human tissues for determination of mechanisms that explore expansion and rupture of existing AAAs. PMID:22833280

  12. Pipeline™ embolization device for the treatment of complex intracranial aneurysms: a NICE Medical Technology Guidance.

    PubMed

    Withers, Kathleen; Carolan-Rees, Grace; Dale, Megan

    2013-02-01

    As part of its Medical Technologies Evaluation Programme, the National Institute of Health and Clinical Excellence (NICE) invited the manufacturer, Covidien, to provide clinical and economic evidence for the evaluation of the Pipeline™ embolization device (PED) for the treatment of complex intracranial aneurysms. Cedar; a consortium between Cardiff and Vale University Health Board and Cardiff University, was commissioned to act as an External Assessment Centre (EAC) for NICE to independently critique the manufacturers' submissions. This article gives an overview of the evidence provided, the findings of the EAC and the final guidance published by NICE. The scope issued by NICE considered PED as the intervention in a patient population with complex unruptured intracranial aneurysms (IAs), specifically large/giant, wide-necked and fusiform aneurysms. The comparator treatments identified were stent-assisted coiling, parent vessel occlusion, neurosurgical techniques and conservative management. The manufacturer claimed that PED fulfils a currently unmet clinical need in the treatment of large or giant, wide-necked or fusiform IAs. Thirteen studies were identified by the manufacturer as being relevant to the decision problem, with two of these included for data extraction. The EAC identified 16 studies as relevant, three of which had been published after the manufacturer's search. Data extraction was carried out on these studies as, although many were low level research comprising of case reports and case series, they provided useful, pertinent safety and outcome data. No relevant economic studies of the device were identified; therefore, a new economic model was designed by the manufacturer. The base-case scenario provided recognized the costs of PED to be higher than the costs for endovascular parent vessel occlusion, neurosurgical parent vessel occlusion, neurosurgical clipping and conservative management. However, PED was found to be cost saving compared with

  13. Modeling Diagnostic Assessments with Bayesian Networks

    ERIC Educational Resources Information Center

    Almond, Russell G.; DiBello, Louis V.; Moulder, Brad; Zapata-Rivera, Juan-Diego

    2007-01-01

    This paper defines Bayesian network models and examines their applications to IRT-based cognitive diagnostic modeling. These models are especially suited to building inference engines designed to be synchronous with the finer grained student models that arise in skills diagnostic assessment. Aspects of the theory and use of Bayesian network models…

  14. Validation of CFD Simulations of Cerebral Aneurysms With Implication of Geometric Variations

    PubMed Central

    Hoi, Yiemeng; Woodward, Scott H.; Kim, Minsuok; Taulbee, Dale B.; Meng, Hui

    2009-01-01

    Background Computational fluid dynamics (CFD) simulations using medical-image-based anatomical vascular geometry are now gaining clinical relevance. This study aimed at validating the CFD methodology for studying cerebral aneurysms by using particle image velocimetry (PIV) measurements, with a focus on the effects of small geometric variations in aneurysm models on the flow dynamics obtained with CFD. Method of Approach. An experimental phantom was fabricated out of silicone elastomer to best mimic a spherical aneurysm model. PIV measurements were obtained from the phantom and compared with the CFD results from an ideal spherical aneurysm model (S1). These measurements were also compared with CFD results, based on the geometry reconstructed from three-dimensional images of the experimental phantom. We further performed CFD analysis on two geometric variations, S2 and S3, of the phantom to investigate the effects of small geometric variations on the aneurysmal flow field. Results. We found poor agreement between the CFD results from the ideal spherical aneurysm model and the PIV measurements from the phantom, including inconsistent secondary flow patterns. The CFD results based on the actual phantom geometry, however, matched well with the PIV measurements. CFD of models S2 and S3 produced qualitatively similar flow fields to that of the phantom but quantitatively significant changes in key hemodynamic parameters such as vorticity, positive circulation, and wall shear stress. Conclusion. CFD simulation results can closely match experimental measurements as long as both are performed on the same model geometry. Small geometric variations on the aneurysm model can significantly alter the flow-field and key hemodynamic parameters. Since medical images are subjected to geometric uncertainties, image-based patient-specific CFD results must be carefully scrutinized before providing clinical feedback. PMID:17154684

  15. Sensitivity Assessment of Ozone Models

    SciTech Connect

    Shorter, Jeffrey A.; Rabitz, Herschel A.; Armstrong, Russell A.

    2000-01-24

    The activities under this contract effort were aimed at developing sensitivity analysis techniques and fully equivalent operational models (FEOMs) for applications in the DOE Atmospheric Chemistry Program (ACP). MRC developed a new model representation algorithm that uses a hierarchical, correlated function expansion containing a finite number of terms. A full expansion of this type is an exact representation of the original model and each of the expansion functions is explicitly calculated using the original model. After calculating the expansion functions, they are assembled into a fully equivalent operational model (FEOM) that can directly replace the original mode.

  16. Hemodynamics of Cerebral Aneurysms: Computational Analyses of Aneurysm Progress and Treatment

    PubMed Central

    Jeong, Woowon; Rhee, Kyehan

    2012-01-01

    The progression of a cerebral aneurysm involves degenerative arterial wall remodeling. Various hemodynamic parameters are suspected to be major mechanical factors related to the genesis and progression of vascular diseases. Flow alterations caused by the insertion of coils and stents for interventional aneurysm treatment may affect the aneurysm embolization process. Therefore, knowledge of hemodynamic parameters may provide physicians with an advanced understanding of aneurysm progression and rupture, as well as the effectiveness of endovascular treatments. Progress in medical imaging and information technology has enabled the prediction of flow fields in the patient-specific blood vessels using computational analysis. In this paper, recent computational hemodynamic studies on cerebral aneurysm initiation, progress, and rupture are reviewed. State-of-the-art computational aneurysmal flow analyses after coiling and stenting are also summarized. We expect the computational analysis of hemodynamics in cerebral aneurysms to provide valuable information for planning and follow-up decisions for treatment. PMID:22454695

  17. Pathogenesis of abdominal aortic aneurysms: microRNAs, proteases, genetic associations.

    PubMed

    Maegdefessel, Lars; Dalman, Ronald L; Tsao, Philip S

    2014-01-01

    Abdominal aortic aneurysm (AAA) disease is a common, morbid, and highly lethal pathology. Extraordinary efforts have been launched to determine the molecular and pathophysiological characteristics of AAAs. Although surgery is highly effective in preventing death by rupture for larger AAAs, no guidance or preventive therapy is currently available for the >90% of patients whose aneurysms are below the surgical threshold. Predictive animal models of AAA as well as human pathological samples have revealed a complex circuit of AAA formation and progression. The proteolytic destruction of matrix components of the aorta by different proteases has been extensively studied over many years. Recently, a novel class of small noncoding RNAs, called microRNAs, was identified as "fine-tuners" of the translational output of target genes; they act by promoting mRNA degradation. Their therapeutic potential in limiting AAA development appears very intriguing. Further, current studies assessing genetic and heritable associations for AAA disease have provided great insight into its pathogenesis, potentially enabling us to better clinically manage affected patients. PMID:24274177

  18. Renal failure after ruptured aneurysm.

    PubMed

    Abbott, W M; Abel, R M; Beck, C H; Fischer, J E

    1975-09-01

    The effectiveness of an intravenous nutritional program plus aggressive dialysis was studied in 32 patients with renal failure following ruptured abdominal aortic aneurysm. Each patient was managed postoperatively with a renal failure fluid regimen, consisting of the eight essential amino acids plus dextrose in conjunction with peritoneal dialysis and hemodialysis. This regimen induced salutary metabolic effects temporarily improving the patient's condition in most instances. No technical or septic complications associated with the intravenous dietary therapy occurred. However, the incidence of recovery of renal function was low, and the overall patient survival was only 12.5%. The experience indicates that although this program has been shown to be efficacious in some patients with acute renal failure, it seems of little benefit in those whose renal failure follows ruptured aortic aneurysm. PMID:808197

  19. Pathological findings of saccular cerebral aneurysms-impact of subintimal fibrin deposition on aneurysm rupture.

    PubMed

    Hokari, Masaaki; Nakayama, Naoki; Nishihara, Hiroshi; Houkin, Kiyohiro

    2015-07-01

    Although several studies have suggested that aneurysmal wall inflammation and laminar thrombus are associated with the rupture of saccular aneurysms, the mechanisms leading to the rupture remain obscure. We performed full exposure of aneurysms before clip application and attempted to keep the fibrin cap on the rupture point. Using these specimens in a nearly original state before surgery, we conducted a pathological analysis and studied the differences between ruptured and unruptured aneurysms to clarify the mechanism of aneurysmal wall degeneration. This study included ruptured (n = 28) and unruptured (n = 12) saccular aneurysms resected after clipping. All of the ruptured aneurysms were obtained within 24 h of onset. Immunostainings for markers of inflammatory cells (CD68) and classical histological staining techniques were performed. Clinical variables and pathological findings from ruptured and unruptured aneurysms were compared. Patients with ruptured or unruptured aneurysms did not differ by age, gender, size, location, and risk factors, such as hypertension, smoking, and hyperlipidemia. The absence or fragmentation of the internal elastica lamina, the myointimal hyperplasia, and the thinning of the aneurysmal wall were generally observed in both aneurysms. The existence of subintimal fibrin deposition, organized laminar thrombus, intramural hemorrhage, neovascularization, and monocyte infiltration are more frequently observed in ruptured aneurysms. Multivariate logistic regression analysis showed that ruptured aneurysm was associated with presence of subintimal fibrin deposition and monocyte infiltration. These findings suggest that subintimal fibrin deposition and chronic inflammation have a strong impact on degeneration of the aneurysmal wall leading to their rupture, and this finding may be caused by endothelial dysfunction. PMID:25860660

  20. Assessment of Molecular Modeling & Simulation

    SciTech Connect

    2002-01-03

    This report reviews the development and applications of molecular and materials modeling in Europe and Japan in comparison to those in the United States. Topics covered include computational quantum chemistry, molecular simulations by molecular dynamics and Monte Carlo methods, mesoscale modeling of material domains, molecular-structure/macroscale property correlations like QSARs and QSPRs, and related information technologies like informatics and special-purpose molecular-modeling computers. The panel's findings include the following: The United States leads this field in many scientific areas. However, Canada has particular strengths in DFT methods and homogeneous catalysis; Europe in heterogeneous catalysis, mesoscale, and materials modeling; and Japan in materials modeling and special-purpose computing. Major government-industry initiatives are underway in Europe and Japan, notably in multi-scale materials modeling and in development of chemistry-capable ab-initio molecular dynamics codes.

  1. Ecosystem Model Skill Assessment. Yes We Can!

    PubMed Central

    Olsen, Erik; Fay, Gavin; Gaichas, Sarah; Gamble, Robert; Lucey, Sean; Link, Jason S.

    2016-01-01

    Need to Assess the Skill of Ecosystem Models Accelerated changes to global ecosystems call for holistic and integrated analyses of past, present and future states under various pressures to adequately understand current and projected future system states. Ecosystem models can inform management of human activities in a complex and changing environment, but are these models reliable? Ensuring that models are reliable for addressing management questions requires evaluating their skill in representing real-world processes and dynamics. Skill has been evaluated for just a limited set of some biophysical models. A range of skill assessment methods have been reviewed but skill assessment of full marine ecosystem models has not yet been attempted. Northeast US Atlantis Marine Ecosystem Model We assessed the skill of the Northeast U.S. (NEUS) Atlantis marine ecosystem model by comparing 10-year model forecasts with observed data. Model forecast performance was compared to that obtained from a 40-year hindcast. Multiple metrics (average absolute error, root mean squared error, modeling efficiency, and Spearman rank correlation), and a suite of time-series (species biomass, fisheries landings, and ecosystem indicators) were used to adequately measure model skill. Overall, the NEUS model performed above average and thus better than expected for the key species that had been the focus of the model tuning. Model forecast skill was comparable to the hindcast skill, showing that model performance does not degenerate in a 10-year forecast mode, an important characteristic for an end-to-end ecosystem model to be useful for strategic management purposes. Skill Assessment Is Both Possible and Advisable We identify best-practice approaches for end-to-end ecosystem model skill assessment that would improve both operational use of other ecosystem models and future model development. We show that it is possible to not only assess the skill of a complicated marine ecosystem model, but that

  2. Hemodynamic study of overlapping bare-metal stents intervention to aortic aneurysm.

    PubMed

    Zhang, Peng; Sun, Anqiang; Zhan, Fan; Luan, Jingyuan; Deng, Xiaoyan

    2014-11-01

    To investigate the hemodynamic performance of overlapping bare-metal stents intervention treatment to thoracic aortic aneurysms (TAA), three simplified TAA models, representing, no stent, with a single stent and 2 overlapped stents deployed in the aneurismal sac, were studied and compared in terms of flow velocity, wall shear stress (WSS) and pressure distributions by means of computational fluid dynamics. The results showed that overlapping stents intervention induced a flow field of slow velocity near the aneurismal wall. Single stent deployment in the sac reduced the jet-like flow formed prior to the proximal neck of the aneurysm, which impinged on the internal wall of the aneurysm. This jet-like flow vanished completely in the overlapping double stents case. Overlapping stents intervention led to an evident decrease in WSS; meanwhile, the pressure acting on the wall of the aneurysm was reduced slightly and presented more uniform distribution. The results therefore indicated that overlapping stents intervention may effectively isolate the thoracic aortic aneurysm, protecting it from rupture. In conclusion, overlapping bare-metal stents may serve a purpose similar to that of the multilayer aneurysm repair system (MARS) manufactured by Cardiatis SA (Isnes, Belgium). PMID:25262876

  3. The cognitive and psychological sequelae of uncomplicated aneurysm surgery.

    PubMed Central

    Maurice-Williams, R S; Willison, J R; Hatfield, R

    1991-01-01

    Many patients are left with psychological symptoms after surgery for a ruptured intracranial aneurysm. Often the reason for these symptoms is not clear. A prospective study was carried out of 27 patients who were in a good (Grade 1 or 2) condition before operation to identify the origin of such symptoms and discover whether the basic techniques of aneurysm surgery could lead to serious psychological sequelae even in the absence of any specific complication. Each patient was given a modified psychometric assessment just before surgery and at the time of discharge from hospital. One year later a full psychometric and social assessment was carried out. Even a temporary worsening of psychometric performance did not occur unless there had been some specific surgical or post-operative problem. Five patients showed worsening of psychometric performance in the immediate post-operative period but by one year, only two of the 27 patients showed any abnormalities on formal psychometric evaluation; in both, clear reasons were evident. Although the majority of patients reported minor psychological symptoms, these had not hindered full functional recovery, and we doubt whether they had any organic basis. It is concluded that aneurysm surgery does not, itself, threaten higher intellectual function unless some specific complication occurs. PMID:2056319

  4. HYDROCARBON SPILL EXPOSURE ASSESSMENT MODELING

    EPA Science Inventory

    Hydrocarbon spills impact drinking water supplies at down gradient locations. onventional finite difference and finite element models of multiphase, multicomponent flow have extreme requirements for both computer time and site data. ite data and the intent of the modeling often d...

  5. Analysis of slipstream flow in two ruptured intracranial cerebral aneurysms.

    PubMed

    Imbesi, S G; Kerber, C W

    1999-10-01

    Replicas of ruptured posterior communicating and basilar artery aneurysms were created from cadaveric specimens and then were placed in a circuit of pulsating non-Newtonian fluid. Individual fluid slipstreams were opacified with isobaric dyes, and images were recorded on film. The slipstreams entered the distal aneurysm neck with impact against the distal lateral wall of the aneurysm. They then swirled slowly in a reverse vortical pattern within the aneurysm sac. Fluid exited the aneurysm at the proximal neck. The flow pattern clearly shows the impact zone of entering slipstreams (the point of aneurysm rupture) and provides information pertaining to aneurysm growth and formation. PMID:10543644

  6. Giant Serpentine Aneurysm of the Middle Cerebral Artery

    PubMed Central

    Lee, Seung Joo; Kwun, Byung Duk; Kim, Chang Jin

    2010-01-01

    Giant serpentine aneurysms are rare and have distinct angiographic findings. The rarity, large size, complex anatomy and hemodynamic characteristics of giant serpentine aneurysms make treatment difficult. We report a case of a giant serpentine aneurysm of the right middle cerebral artery (MCA) that presented as headache. Treatment involved a superficial temporal artery (STA)-MCA bypass followed by aneurysm resection. The patient was discharged without neurological deficits, and early and late follow-up angiography disclosed successful removal of the aneurysm and a patent bypass graft. We conclude that STA-MCA bypass and aneurysm excision is a successful treatment method for a giant serpentine aneurysm. PMID:20856671

  7. Idiopathic subvalvular aortic aneurysm masquerading as acute coronary syndrome.

    PubMed

    Natarajan, Balaji; Ramanathan, Sundar; Subramaniam, Natarajan; Janardhanan, Rajesh

    2016-01-01

    Subvalvular aneurysms are the least common type of left ventricular (LV) aneurysms and can be fatal. Subaortic LV aneurysms are much rarer than submitral LV aneurysms and mostly reported in infancy. They can be congenital or acquired secondary to infections, cardiac surgery or trauma. Here, we report a unique presentation of a large, idiopathic subaortic aneurysm in an adult masquerading as an acute coronary syndrome. Diagnosis was made with the help of a CT aortography. Aneurysm was surgically resected with good results. This case highlights the clinical presentation and management of subaortic aneurysms, an important differential for congenital aortic malformations. PMID:27591034

  8. Spontaneous Retroperitoneal Hemorrhage from Adrenal Artery Aneurysm

    SciTech Connect

    Gonzalez Valverde, F.M. Balsalobre, M.; Torregrosa, N.; Molto, M.; Gomez Ramos, M.J.; Vazquez Rojas, J.L.

    2007-04-15

    Spontaneous adrenal hemorrhage is a very rare but serious disorder of the adrenal gland that can require emergent treatment. We report on a 42-year-old man who underwent selective angiography for diagnosis and treatment of retroperitoneal hemorrhage from small adrenal artery aneurysm. This case gives further details about the value of transluminal artery embolization in the management of visceral aneurysm rupture.

  9. Pantopaque simulating thrombosed intracranial aneurysms on MRI

    SciTech Connect

    Lidov, M.W.; Silvers, A.R.; Mosesson, R.E.; Stollman, A.L.; Som, P.M.

    1996-03-01

    A patient is presented in whom iophendylate (Pantopaque) within the basal cisterns closely resembled the appearance on MRI of thrombosed aneurysms of the middle cerebral arteries. The sometimes subtle differences between the appearances on MRI of Pantopaque and aneurysmal clot are discussed to permit accurate diagnosis without resorting to more invasive diagnostic tests, such as cerebral angiography. 5 refs., 4 figs.

  10. [Aneurysm of the femoral and popliteal vein].

    PubMed

    Hansen, L G; Boris, P

    1986-04-01

    Aneurysms of the popliteal and femoral veins are rare and may be seen as casual findings with no clinical manifestations whatsoever. On the other hand they may be potential source of recurrent pulmonary embolism. A case is reported, where an aneurysm of the femoral vein was found in a clinically symptomless woman aged 48. PMID:3715020

  11. Two cases of giant serpentine aneurysm.

    PubMed

    Kumabe, T; Kaneko, U; Ishibashi, T; Kaneko, K; Uchigasaki, S

    1990-06-01

    Giant serpentine aneurysm (GSA) is an entity defined on radiological and pathological grounds as a giant, partially thrombosed aneurysm containing tortuous vascular channels. We have had the opportunity to study two patients with GSAs, which has allowed for a complete comparative anatomical and radiological study. This report emphasizes the etiology of the GSAs. Twenty-two patients with GSAs have been reported in the literature, of which pathological studies were done in 10. In most of these, the aneurysm was found to be filled with an organized thrombus, but in our patients the aneurysm was filled with relatively new clot. The aneurysm enlarged and a change in the tortuous vascular channel was observed over a period of 1 year in the first patient, whereas a globoid aneurysm developed into a GSA in the brief period of just 2 weeks in the second patient. This rapid transformation of a globoid aneurysm into a GSA is of particular interest when the etiology of GSAs is considered. Our patients therefore shed some interesting light on the possible pathophysiology of GSAs. That is, the bloodstream may change dynamically in a giant aneurysm and may become a serpentine channel under conditions that lead to a "Coanda effect." PMID:2362659

  12. Cardiovascular syphilis with coronary stenosis and aneurysm.

    PubMed

    Tewari, Satyendra; Moorthy, Nagaraja

    2014-01-01

    Cardiovascular manifestations of tertiary syphilis include aortitis, aortic root dilation, aneurysm formation, aortic regurgitation, and coronary ostial stenosis. Coronary ostial lesions have been detected in as many as 26% of patients with syphilitic aortitis. However nonostial coronary stenosis and coronary aneurysms in same patient is rarely described in cardiovascular syphilis. PMID:25634420

  13. Aneurysm of sinus of Valsalva: uncommon presentation.

    PubMed

    Elumalai, Raja Saravanan; Vaidyanathan, Kirthivasan; Nainar, Madhu Sankar; Balasubramaniam, Govini; George, Susan

    2011-12-01

    A 28-year-old man presented with acute onset of chest pain. Transthoracic echocardiography confirmed an aneurysm of the sinus of Valsalva dissecting into the interventricular septum. During the next 12 h, the aneurysm enlarged to involve the entire interventricular septum, and the patient developed features of cardiac tamponade. He underwent successful surgical repair. PMID:22160415

  14. Late Sac Behavior after Endovascular Aneurysm Repair for Abdominal Aortic Aneurysm

    PubMed Central

    Okada, Masahiro; Onohara, Toshihiro; Okamoto, Minoru; Yamamoto, Tsuyoshi; Shimoe, Yasushi; Yamashita, Masafumi; Takahashi, Toshiki; Kishimoto, Jyunji; Mizuno, Akihiro; Kei, Junichi; Nakai, Mikizou; Sakaki, Masayuki; Suhara, Hitoshi; Kasashima, Fuminori; Endo, Masamitsu; Nishina, Takeshi; Furuyama, Tadashi; Kawasaki, Masakazu; Iwata, Keiji; Marumoto, Akira; Urata, Yasuhisa; Sato, Katsutoshi; Ryugo, Masahiro

    2016-01-01

    Background: Sac behavior after endovascular aneurysm repair (EVAR) for abdominal aortic aneurysms (AAAs) is considered as a surrogate for the risk of late rupture. The purpose of the study is to assess the sac behavior of AAAs after EVAR. Methods and Results: Late sac enlargement (LSE) (≥5 mm) and late sac shrinkage (LSS) (≥5 mm) were analyzed in 589 consecutive patients who were registered at 14 national centers in Japan. The proportions of patients who had LSE at 1, 3 and 5 years were 2.6% ± 0.7%, 10.0% ± 1.6% and 19.0% ± 2.9%. The proportions of patients who had LSS at 1, 3 and 5 years were 50.1% ± 0.7%, 59.2% ± 2.3% and 61.7% ± 2.7%. Multiple logistic regression analysis identified two variables as a risk factor for LSE; persistent endoleak (Odds ratio 9.56 (4.84–19.49), P <0.001) and low platelet count (Odds ratio 0.92 (0.86–0.99), P = 0.0224). The leading cause of endoleak in patients with LSE was type II. Conclusions: The incidence of LSE is not negligible over 5 year period. Patients with persistent endoleak and/or low platelet count should carefully be observed for LSE. Clinical Trial Registration: UMIN-CTR (UMIN000008345). PMID:27375803

  15. Empirical assessment of model validity

    SciTech Connect

    Wolfe, R.R. )

    1991-05-01

    The metabolism of amino acids is far more complicated than a 1- to 2-pool model. Yet, these simple models have been extensively used with many different isotopically labeled tracers to study protein metabolism. A tracer of leucine and measurement of leucine kinetics has been a favorite choice for following protein metabolism. However, administering a leucine tracer and following it in blood will not adequately reflect the complex multi-pool nature of the leucine system. Using the tracer enrichment of the ketoacid metabolite of leucine, alpha-ketoisocaproate (KIC), to reflect intracellular events of leucine was an important improvement. Whether this approach is adequate to follow accurately leucine metabolism in vivo or not has not been tested. From data obtained using simultaneous administration of leucine and KIC tracers, we developed a 10-pool model of the in vivo leucine-KIC and bicarbonate kinetic system. Data from this model were compared with conventional measurements of leucine kinetics. The results from the 10-pool model agreed best with the simplified approach using a leucine tracer and measurement of KIC enrichment.

  16. Management of distal left main coronary artery aneurysm.

    PubMed

    Ko, Po-Yen; Chang, Chih-Ping; Lin, Jen-Jyh; Liu, Juhn-Cherng

    2013-12-01

    Aneurysms of the left main coronary artery are extremely rare. The cause of such aneurysms is uncertain. Although the treatment of distal left main aneurysms is very complicated, definitive treatment is necessary because the aneurysm may grow further and cause embolism or rupture. Herein, we report a case of acute myocardial infarction caused by aneurysm of the distal left main coronary artery, which was successfully treated by performing coronary artery bypass surgery, followed by implantation of a polytetrafluoroethylene-covered stent. PMID:22535673

  17. Hemodynamic simulations in coronary aneurysms of children with Kawasaki disease

    NASA Astrophysics Data System (ADS)

    Sengupta, Dibyendu; Burns, Jane; Marsden, Alison

    2009-11-01

    Kawasaki disease (KD) is a serious pediatric illness affecting the cardiovascular system. One of the most serious complications of KD, occurring in about 25% of untreated cases, is the formation of large aneurysms in the coronary arteries, which put patients at risk for myocardial infarction. In this project we performed patient specific computational simulations of blood flow in aneurysmal left and right coronary arteries of a KD patient to gain an understanding about their hemodynamics. Models were constructed from CT data using custom software. Typical pulsatile flow waveforms were applied at the model inlets, while resistance and RCR lumped models were applied and compared at the outlets. Simulated pressure waveforms compared well with typical physiologic data. High wall shear stress values are found in the narrow region at the base of the aneurysm and low shear values occur in regions of recirculation. A Lagrangian approach has been adopted to perform particle tracking and compute particle residence time in the recirculation. Our long-term goal will be to develop links between hemodynamics and the risk for thrombus formation in order to assist in clinical decision-making.

  18. Model assessment of fumigant emissions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Simulation models are useful for estimating the environmental fate and transport of pesticides. Soil fumigants such as methyl bromide are a special group of pesticides with high vapor pressure values. A main concern with fumigants is the large potential for atmospheric emissions. Because of the l...

  19. Teacher Assessment Competency: A Rasch Model Analysis.

    ERIC Educational Resources Information Center

    Zhang, Zhicheng

    A 67-item Assessment Practices Inventory (API) was administered to 311 inservice teachers. The application of principal components analysis to the data yielded a 6-factor solution that explained 64% of the variance. The Rasch rating scale model was applied to the API to estimate item calibrations. The factor analyzed assessment categories were…

  20. Minority Utility Rate Design Assessment Model

    Energy Science and Technology Software Center (ESTSC)

    2003-01-20

    Econometric model simulates consumer demand response to various user-supplied, two-part tariff electricity rate designs and assesses their economic welfare impact on black, hispanic, poor and majority households.

  1. Accuracy of Computational Cerebral Aneurysm Hemodynamics Using Patient-Specific Endovascular Measurements

    NASA Astrophysics Data System (ADS)

    McGah, Patrick; Levitt, Michael; Barbour, Michael; Mourad, Pierre; Kim, Louis; Aliseda, Alberto

    2013-11-01

    We study the hemodynamic conditions in patients with cerebral aneurysms through endovascular measurements and computational fluid dynamics. Ten unruptured cerebral aneurysms were clinically assessed by three dimensional rotational angiography and an endovascular guidewire with dual Doppler ultrasound transducer and piezoresistive pressure sensor at multiple peri-aneurysmal locations. These measurements are used to define boundary conditions for flow simulations at and near the aneurysms. The additional in vivo measurements, which were not prescribed in the simulation, are used to assess the accuracy of the simulated flow velocity and pressure. We also performed simulations with stereotypical literature-derived boundary conditions. Simulated velocities using patient-specific boundary conditions showed good agreement with the guidewire measurements, with no systematic bias and a random scatter of about 25%. Simulated velocities using the literature-derived values showed a systematic over-prediction in velocity by 30% with a random scatter of about 40%. Computational hemodynamics using endovascularly-derived patient-specific boundary conditions have the potential to improve treatment predictions as they provide more accurate and precise results of the aneurysmal hemodynamics. Supported by an R03 grant from NIH/NINDS

  2. Model-based safety assessments

    SciTech Connect

    Carlson, D.D.; Jones, T.R.

    1998-04-01

    Sandia National Laboratories performs systems analysis of high risk, high consequence systems. In particular, Sandia is responsible for the engineering of nuclear weapons, exclusive of the explosive physics package. In meeting this responsibility, Sandia has developed fundamental approaches to safety and a process for evaluating safety based on modeling and simulation. These approaches provide confidence in the safety of our nuclear weapons. Similar concepts may be applied to improve the safety of other high consequence systems.

  3. Stent-Grafts for Unruptured Abdominal Aortic Aneurysms: Current Status

    SciTech Connect

    Rose, John

    2006-06-15

    Aortic stent-grafts were introduced at the beginning of the 1990s as a less invasive method of dealing with aortic aneurysms in patients with poor cardiovascular reserve. The numbers of procedures performed worldwide has increased exponentially despite the current lack of any substantial evidence for long-term efficacy in comparison with the gold standard of open surgical grafting. This review summarizes the evolution of the abdominal aortic stent-graft, the techniques used for assessment and deployment, and the effect of the procedure on both the patient and the device. The recent publication of two national multicenter trials has confirmed that the endovascular technique confers a 2.5-fold reduction in 30-day mortality in comparison with open surgery. However, over 4 years of follow-up, there is a 3-fold increase in the risk of reintervention and the overall costs are 30% greater with endovascular repair. Although the improvement in aneurysm-related mortality persists in the mid-term, because of the initial reduction in perioperative mortality, the all-cause mortality rate at 4 years is actually no better than for open surgery. Longer-term data from the randomized trials are awaited as well as results from the latest trials utilizing state-of-the-art devices. Whilst the overall management of abdominal aortic aneurysms has undoubtedly benefited from the introduction of stent-grafts, open repair currently remains the gold standard treatment.

  4. Monitoring the biological activity of abdominal aortic aneurysms Beyond Ultrasound.

    PubMed

    Forsythe, Rachael O; Newby, David E; Robson, Jennifer M J

    2016-06-01

    Abdominal aortic aneurysms (AAAs) are an important cause of morbidity and, when ruptured, are associated with >80% mortality. Current management decisions are based on assessment of aneurysm diameter by abdominal ultrasound. However, AAA growth is non-linear and rupture can occur at small diameters or may never occur in those with large AAAs. There is a need to develop better imaging biomarkers that can identify the potential risk of rupture independent of the aneurysm diameter. Key pathobiological processes of AAA progression and rupture include neovascularisation, necrotic inflammation, microcalcification and proteolytic degradation of the extracellular matrix. These processes represent key targets for emerging imaging techniques and may confer an increased risk of expansion or rupture over and above the known patient-related risk factors. Magnetic resonance imaging, using ultrasmall superparamagnetic particles of iron oxide, can identify and track hotspots of macrophage activity. Positron emission tomography, using a variety of targeted tracers, can detect areas of inflammation, angiogenesis, hypoxia and microcalcification. By going beyond the simple monitoring of diameter expansion using ultrasound, these cellular and molecular imaging techniques may have the potential to allow improved prediction of expansion or rupture and to better guide elective surgical intervention. PMID:26879242

  5. Monitoring the biological activity of abdominal aortic aneurysms Beyond Ultrasound

    PubMed Central

    Forsythe, Rachael O; Newby, David E; Robson, Jennifer M J

    2016-01-01

    Abdominal aortic aneurysms (AAAs) are an important cause of morbidity and, when ruptured, are associated with >80% mortality. Current management decisions are based on assessment of aneurysm diameter by abdominal ultrasound. However, AAA growth is non-linear and rupture can occur at small diameters or may never occur in those with large AAAs. There is a need to develop better imaging biomarkers that can identify the potential risk of rupture independent of the aneurysm diameter. Key pathobiological processes of AAA progression and rupture include neovascularisation, necrotic inflammation, microcalcification and proteolytic degradation of the extracellular matrix. These processes represent key targets for emerging imaging techniques and may confer an increased risk of expansion or rupture over and above the known patient-related risk factors. Magnetic resonance imaging, using ultrasmall superparamagnetic particles of iron oxide, can identify and track hotspots of macrophage activity. Positron emission tomography, using a variety of targeted tracers, can detect areas of inflammation, angiogenesis, hypoxia and microcalcification. By going beyond the simple monitoring of diameter expansion using ultrasound, these cellular and molecular imaging techniques may have the potential to allow improved prediction of expansion or rupture and to better guide elective surgical intervention. PMID:26879242

  6. Effect of Aneurysmal Subarachnoid Hemorrhage on Word Generation

    PubMed Central

    Ladowski, Daniella; Qian, Winnie; Kapadia, Anish N.; Macdonald, R. Loch; Schweizer, Tom A.

    2014-01-01

    Background. Aneurysmal subarachnoid hemorrhage (aSAH) survivors commonly exhibit impairment on phonemic and semantic fluency tests; however, it is unclear which of the contributing cognitive processes are compromised in aSAH patients. One method of disentangling these processes is to compare initial word production, which is a rapid, semiautomatic, frontal-executive process, and late phase word production, which is dependent on more effortful retrieval and lexical size and requires a more distributed neural network. Methods. Seventy-two individuals with aSAH and twenty-five control subjects were tested on a cognitive battery including the phonemic and semantic fluency task. Demographic and clinical information was also collected. Results. Compared to control subjects, patients with aSAH were treated by clipping and those with multiple aneurysms were impaired across the duration of the phonemic test. Among patients treated by coiling, those with anterior communicating artery aneurysms or a neurological complication (intraventricular hemorrhage, vasospasm, and edema) showed worse output only in the last 45 seconds of the phonemic test. Patients performed comparably to control subjects on the semantic test. Conclusions. These results support a “diffuse damage” hypothesis of aSAH, indicated by late phase phonemic fluency impairment. Overall, the phonemic and semantic tests represent a viable, rapid clinical screening tool in the postoperative assessment of patients with aSAH. PMID:24803729

  7. Association between surgeon seniority and outcome in intracranial aneurysm surgery.

    PubMed

    Cunningham, E J; Debar, S; Bell, B A

    2003-04-01

    Specialist surgical registrars perform surgery as a requirement of their training, but the effect of the surgeon's level of training on outcome in intracranial aneurysm surgery is not known. This study addresses this question. A cohort of 278 consecutive patients who underwent a craniotomy to clip a recently ruptured intracranial aneurysm between January 1995 and December 1999 was assessed. Patients were divided into three groups according to whether the operating surgeon was a registrar, a senior registrar or a consultant. The frequency of a good outcome (defined as a Glasgow outcome score of 5) was compared in the three groups. Registrars operated on 91 patients (33%), senior registrars on 60 (21%) and consultants on 127 (46%). Between the three groups there was no statistically significant difference in patient age, male: female ratio, the timing of surgery after the haemorrhage, or the proportion of patients requiring preoperative ventriculostomy or with angiographic vasospasm, but more patients operated on by consultants had favourable admission World Federation of Neurological Surgeons grades. About two-thirds of patients achieved a Glasgow outcome score of 5 at 6 months, and there were no statistically significant differences in outcome between the three groups at discharge, at 6 months and at 1 year. Intracranial aneurysm surgery by trainees and consultants was not associated with differences in patient outcome in a cohort of patients treated at a University teaching hospital. PMID:12820753

  8. On the prediction of monocyte deposition in abdominal aortic aneurysms using computational fluid dynamics.

    PubMed

    Hardman, David; Doyle, Barry J; Semple, Scott I K; Richards, Jennifer M J; Newby, David E; Easson, William J; Hoskins, Peter R

    2013-10-01

    In abdominal aortic aneurysm disease, the aortic wall is exposed to intense biological activity involving inflammation and matrix metalloproteinase-mediated degradation of the extracellular matrix. These processes are orchestrated by monocytes and rather than affecting the aorta uniformly, damage and weaken focal areas of the wall leaving it vulnerable to rupture. This study attempts to model numerically the deposition of monocytes using large eddy simulation, discrete phase modelling and near-wall particle residence time. The model was first applied to idealised aneurysms and then to three patient-specific lumen geometries using three-component inlet velocities derived from phase-contrast magnetic resonance imaging. The use of a novel, variable wall shear stress-limiter based on previous experimental data significantly improved the results. Simulations identified a critical diameter (1.8 times the inlet diameter) beyond which significant monocyte deposition is expected to occur. Monocyte adhesion occurred proximally in smaller abdominal aortic aneurysms and distally as the sac expands. The near-wall particle residence time observed in each of the patient-specific models was markedly different. Discrete hotspots of monocyte residence time were detected, suggesting that the monocyte infiltration responsible for the breakdown of the abdominal aortic aneurysm wall occurs heterogeneously. Peak monocyte residence time was found to increase with aneurysm sac size. Further work addressing certain limitations is needed in a larger cohort to determine clinical significance. PMID:23886969

  9. Risk Factors for Rebleeding of Aneurysmal Subarachnoid Hemorrhage: A Meta-Analysis

    PubMed Central

    Tang, Chao; Zhang, Tian-Song; Zhou, Liang-Fu

    2014-01-01

    Background Rebleeding is a serious complication of aneurysmal subarachnoid hemorrhaging. To date, there are conflicting data regarding the factors contributing to rebleeding and their significance. Methods A systematic review of PubMed and Embase databases was conducted for studies pertaining to aneurysmal subarachnoid hemorrhage (aSAH) and rebleeding in order to assess the associated risk factors. Odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were estimated from fourteen studies comprised of a total of 5693 patients that met the inclusion criteria. Results Higher rebleeding rates were observed < 6 h after the initial aSAH (OR  = 3.22, 95% CI  = 1.46–7.12), and were associated with high systolic blood pressure (OR  = 1.93, 95% CI  = 1.31–2.83), poor Hunt-Hess grade (III–IV) (OR  = 3.43, 95% CI  = 2.33–5.05), intracerebral or intraventricular hematomas (OR  = 1.65, 95% CI  = 1.33–2.05), posterior circulation aneurysms (OR  = 2.15, 95% CI  = 1.32–3.49), and aneurysms >10 mm in size (OR  = 1.70, 95% CI  = 1.35–2.14). Conclusions Aneurysmal rebleeding occurs more frequently within the first 6 hours after the initial aSAH. Risk factors associated with rebleeding include high systolic pressure, the presence of an intracerebral or intraventricular hematoma, poor Hunt-Hess grade (III-IV), aneurysms in the posterior circulation, and an aneurysm >10 mm in size. PMID:24911172

  10. Endovascular management of renal artery aneurysms using the multilayer flow modulator

    PubMed Central

    Sultan, Sherif; Basuoniy Alawy, Mahmoud; Flaherty, Rita; Kavanagh, Edel P; Elsherif, Mohamed; Elhelali, Ala; Stefanov, Florian; Lundon, Violet; Hynes, Niamh

    2016-01-01

    Objective Our aim was to describe our experience of the Multilayer Flow Modulator (MFM, Cardiatis, Isnes, Belgium) used in the treatment of type III renal artery aneurysms (RAA). Methods This is a single-centre study. 3 patients (2 men and 1 woman; mean age 59 years; range 41–77 years) underwent treatment of a type III renal artery aneurysm using the MFM. The indications were a 23.9 mm type III RAA at the bifurcation of the upper and lower pole vessels, with 4 side branches; a 42.4 mm type III saccular RAA at the renal hilum; and a 23 mm type III RAA at the origin of the artery, supplying the upper pole. Results Patients had a mean follow-up of 27 months, and were assessed by perioperative renal function tests, and repeat postoperative CT scan. There were no immediate postoperative complications or mortality. The first patient's aneurysm shrank by 8.6 mm, from 23.9 to 15.3 mm over 19 months, with all 4 side branches remaining patent. The largest aneurysm at 42.4 mm completely thrombosed, while the renal artery remained patent to the kidney. The final patient refused to have any follow-up scans but had no deterioration in renal function below 30 mL/min, and no further symptoms reported. Conclusions The MFM is safe and effective in the management of patients with complex renal artery aneurysms. The MFM can be used to treat branched or distal renal artery aneurysms with exclusion of the aneurysm from the circulation, while successfully preserving the flow to the side branches and kidney. Initial results are promising, however, longer follow-up and a larger cohort are required to prove the effectiveness of this emerging technology. PMID:27042315

  11. Relative importance of aneurysm diameter and body size for predicting AAA rupture in men and women

    PubMed Central

    Lo, Ruby C.; Lu, Bing; Fokkema, Margriet T.M.; Conrad, Mark; Patel, Virendra I.; Fillinger, Mark; Matyal, Robina; Schermerhorn, Marc L.

    2014-01-01

    Objectives Women have been shown to have up to a four-fold higher risk of abdominal aortic aneurysm (AAA) rupture at any given aneurysm diameter compared to men, leading to recommendations to offer repair to women at lower diameter thresholds. Although this higher risk of rupture may simply reflect greater relative aortic dilatation in women who have smaller aortas to begin with, this has never been quantified. Our objective was therefore to quantify the relationship between rupture and aneurysm diameter relative to body size and to determine whether a differential association between aneurysm diameter, body size, and rupture risk exists for men and women. Methods We performed a retrospective review of all patients in the Vascular Study Group of New England (VSGNE) database who underwent endovascular or open AAA repair. Using each patient’s height and weight, body mass index (BMI) and body surface area (BSA) were calculated. Next, indices of each measure of body size (height, weight, BMI, BSA) relative to aneurysm diameter were calculated for each patient. To generate these indices, we divided aneurysm diameter (in cm) by the measure of body size [e.g. aortic size index (ASI) = aneurysm diameter (cm) / BSA (m2)]. Along with other relevant clinical variables, we used these indices to construct different age-adjusted and multivariable-adjusted logistic regression models to determine predictors of ruptured repair vs. elective repair. Models for men and women were developed separately and different models were compared using the area under the curve (AUC). Results We identified 4045 patients who underwent AAA repair (78% male, 53% EVAR). Women had significantly smaller diameter aneurysms, lower BSA, and higher BSA indices than men (Table 1). For men, the variable that increased the odds of rupture the most was aneurysm diameter (AUC = 0.82). Men exhibited an increased rupture risk with increasing aneurysm diameter (<5.5cm: OR 1.0; 5.5–6.4cm: OR 0.9, 95% CI 0.5–1

  12. An Artificial Neural Network Stratifies the Risks of Reintervention and Mortality after Endovascular Aneurysm Repair; a Retrospective Observational study

    PubMed Central

    Karthikesalingam, Alan; Attallah, Omneya; Ma, Xianghong; Bahia, Sandeep Singh; Thompson, Luke; Vidal-Diez, Alberto; Choke, Edward C.; Bown, Matt J.; Sayers, Robert D.; Thompson, Matt M.; Holt, Peter J.

    2015-01-01

    Background Lifelong surveillance after endovascular repair (EVAR) of abdominal aortic aneurysms (AAA) is considered mandatory to detect potentially life-threatening endograft complications. A minority of patients require reintervention but cannot be predictively identified by existing methods. This study aimed to improve the prediction of endograft complications and mortality, through the application of machine-learning techniques. Methods Patients undergoing EVAR at 2 centres were studied from 2004-2010. Pre-operative aneurysm morphology was quantified and endograft complications were recorded up to 5 years following surgery. An artificial neural networks (ANN) approach was used to predict whether patients would be at low- or high-risk of endograft complications (aortic/limb) or mortality. Centre 1 data were used for training and centre 2 data for validation. ANN performance was assessed by Kaplan-Meier analysis to compare the incidence of aortic complications, limb complications, and mortality; in patients predicted to be low-risk, versus those predicted to be high-risk. Results 761 patients aged 75 +/- 7 years underwent EVAR. Mean follow-up was 36+/- 20 months. An ANN was created from morphological features including angulation/length/areas/diameters/volume/tortuosity of the aneurysm neck/sac/iliac segments. ANN models predicted endograft complications and mortality with excellent discrimination between a low-risk and high-risk group. In external validation, the 5-year rates of freedom from aortic complications, limb complications and mortality were 95.9% vs 67.9%; 99.3% vs 92.0%; and 87.9% vs 79.3% respectively (p<0.001) Conclusion This study presents ANN models that stratify the 5-year risk of endograft complications or mortality using routinely available pre-operative data. PMID:26176943

  13. Iodine-containing cellulose mixed esters as radiopaque polymers for direct embolization of cerebral aneurysms and arteriovenous malformations.

    PubMed

    Mottu, F; Rüfenacht, D A; Laurent, A; Doelker, E

    2002-01-01

    The present study deals with the synthesis and characterization of radiopaque polymers which could, when solubilized in an appropriate water-miscible solvent, be useful embolic materials for the treatment of cerebral aneurysms and arteriovenous malformations. For this purpose cellulose (both microcrystalline and powdered) and partially substituted cellulose acetate (two different viscosity grades) were selected as starting materials to prepare iodine-containing polymers through various synthetic routes. The materials obtained were characterized by IR and NMR spectroscopy, molecular weight, iodine content, radiopacity and solubility in selected injectable organic solvents. The embolic liquids were evaluated for their precipitation behavior in a phosphate buffer solution (pH 7.4) mimicking physiological conditions using an in vitro aneurysm model. A sheep model was also used to assess in vivo the radiopacity and precipitation properties of a highly concentrated solution of a cellulose acetate 2,3,4-triiodobenzoate mixed ester. All materials with 4-iodo- and 2,3,5-triiodobenzoyl groups gave sufficient radiopacity to be regarded as possible embolization materials, whereas iododeoxycellulose and iododeoxycellulose acetate were not radiopaque because of their low iodine content. Esters synthesized using cellulose as starting material were not soluble in the selected organic solvents due to the presence of many residual hydroxyl groups, but could be used for other biomedical applications where insoluble radiopaque materials are used. In contrast, solubility of the materials as well as satisfactory precipitation properties were ensured using cellulose acetate as the starting material. In conclusion, cellulose acetate iodobenzoate mixed esters dissolved in diglyme or dimethyl isosorbide (dimethyl sulfoxide is probably less appropriate because of its toxicity and hemolytic properties) could be useful embolic liquids for the treatment of cerebral aneurysms or arteriovenous

  14. Cerebral aneurysms following radiotherapy for medulloblastoma

    SciTech Connect

    Benson, P.J.; Sung, J.H.

    1989-04-01

    Three patients, two males and one female aged 21, 14, and 31 years, respectively, developed cerebral saccular aneurysms several years after undergoing radiotherapy for cerebellar medulloblastoma at 2, 5, and 14 years of age, respectively. Following surgery, all three received combined cobalt-60 irradiation and intrathecal colloidal radioactive gold (/sup 198/Au) therapy, and died from rupture of the aneurysm 19, 9, and 17 years after the radiotherapy, respectively. Autopsy examination revealed no recurrence of the medulloblastoma, but widespread radiation-induced vasculopathy was found at the base of the brain and in the spinal cord, and saccular aneurysms arose from the posterior cerebral arteries at the basal cistern or choroidal fissure. The aneurysms differed from the ordinary saccular aneurysms of congenital type in their location and histological features. Their locations corresponded to the areas where intrathecally administered colloidal /sup 198/Au is likely to pool, and they originated directly from a segment of the artery rather than from a branching site as in congenital saccular aneurysms. It is, therefore, concluded that the aneurysms in these three patients were most likely radiation-induced.

  15. Physical Factors Effecting Cerebral Aneurysm Pathophysiology

    PubMed Central

    Sadasivan, Chander; Fiorella, David J.; Woo, Henry H.; Lieber, Baruch B.

    2013-01-01

    Many factors that are either blood-, wall-, or hemodynamics-borne have been associated with the initiation, growth, and rupture of intracranial aneurysms. The distribution of cerebral aneurysms around the bifurcations of the circle of Willis has provided the impetus for numerous studies trying to link hemodynamic factors (flow impingement, pressure, and/or wall shear stress) to aneurysm pathophysiology. The focus of this review is to provide a broad overview of such hemodynamic associations as well as the subsumed aspects of vascular anatomy and wall structure. Hemodynamic factors seem to be correlated to the distribution of aneurysms on the intracranial arterial tree and complex, slow flow patterns seem to be associated with aneurysm growth and rupture. However, both the prevalence of aneurysms in the general population and the incidence of ruptures in the aneurysm population are extremely low. This suggests that hemodynamic factors and purely mechanical explanations by themselves may serve as necessary, but never as necessary and sufficient conditions of this disease’s causation. The ultimate cause is not yet known, but it is likely an additive or multiplicative effect of a handful of biochemical and biomechanical factors. PMID:23549899

  16. Insights on a Giant Aneurysm Treated Endovascularly.

    PubMed

    Graziano, Francesca; Iacopino, Domenico Gerardo; Ulm, Arthur John

    2016-07-01

    Background Endovascular treatment with stent-assisted Guglielmi detachable coils is an accepted method for treating intracranial giant aneurysms that otherwise would require more invasive or destructive treatment or could not be treated at all. Nevertheless, there is a paucity of information concerning inner postcoiling aneurysmal changes in human subjects over the long term. We report a postmortem analysis of a patient with a giant aneurysm at the vertebrobasilar junction (VBJ) who was treated endovascularly and studied pathologically 24 months after treatment. Materials and Method The head was removed at autopsy and prefixed in a 10% neutral buffered formalin solution. The brain was gently removed from the skull base after cutting the intracranial nerves and vascular structures. The giant VBJ aneurysm and its relationship with the brainstem, cranial nerves, and vessels were captured photographically and analyzed. Afterward, under operating microscope guidance, the vertebrobasilar system with the aneurysm was gently and carefully detached from the brainstem and carefully analyzed. Results No complete fibrous obliteration of the aneurysm lumen could be detected in our case, and no endothelialization had taken place 24 months after treatment. Conclusions Our findings agree with those of previous similar reports. Coiling, in particular in large or giant aneurysms, may be burdened by the risk of coil compaction and recanalization, but it has the advantage of not affecting the flow in the perforating arteries. PMID:26296255

  17. Endovascular Repair of Abdominal Aortic Aneurysms: Analysis of Aneurysm Volumetric Changes at Mid-Term Follow-Up

    SciTech Connect

    Bargellini, Irene Cioni, Roberto; Petruzzi, Pasquale; Pratali, Alessandro; Napoli, Vinicio; Vignali, Claudio; Ferrari, Mauro; Bartolozzi, Carlo

    2005-05-15

    Purpose. To evaluate the volumetric changes in abdominal aortic aneurysms (AAA) after endovascular AAA repair (EVAR) in 24 months of follow-up. Methods. We evaluated the volume modifications in 63 consecutive patients after EVAR. All patients underwent strict duplex ultrasound and computed tomography angiography (CTA) follow-up; when complications were suspected, digital subtraction angiography was also performed. CTA datasets at 1, 6, 12, and 24 months were post-processed through semiautomatic segmentation, to isolate the aneurysmal sac and calculate its volume. Maximum transverse diameters (Dmax) were also obtained in the true axial plane, Presence and type of endoleak (EL) were recorded. A statistical analysis was performed to assess the degree of volume change, correlation with diameter modifications, and significance of the volume increase with respect to ELs. Results. Mean reconstruction time was 7 min. Mean volume reduction rates were 6.5%, 8%, and 9.6% at 6, 12, and 24 months follow-up, respectively. Mean Dmax reduction rates were 4.2%, 6.7%, and 12%; correlation with volumes was poor (r = 0.73-0.81). ELs were found in 19 patients and were more frequent (p = 0.04) in patients with higher preprocedural Dmax, The accuracies of volume changes in predicting ELs ranged between 74.6% and 84.1% and were higher than those of Dmax modifications. The strongest independent predictor of EL was a volume change at 6 months {<=}0.3% (p = 0.005), although 6 of 19 (32%) patients with EL showed no significant AAA enlargement, whereas in 6 of 44 (14%) patients without EL the aneurysm enlarged. Conclusion. The lack of volume decrease in the aneurysm of at least 0.3% at 6 months follow-up indicates the need for closer surveillance, and has a higher predictive accuracy for an endoleak than Dmax.

  18. Rasmussen's Aneurysm: A Forgotten Entity?

    SciTech Connect

    Keeling, A. N.; Costello, R.; Lee, M. J.

    2008-01-15

    We present the case of a rare entity which is a complication of a disease process that had almost disappeared from the Western World. With the recent resurgence in reported cases of Mycobacterium tuberculosis (TB) in Western communities, it is important to recognize complications and sequelae. A young alcoholic male with confirmed active TB suffered a cardiac arrest following massive haemoptysis. Multidetector computed tomography angiography diagnosed a Rasmussen's aneurysm, confirmed by digital subtraction angiography and then successfully embolized with glue. We outline this rare case and the embolization technique and review previously documented reports.

  19. Models and parameters for environmental radiological assessments

    SciTech Connect

    Miller, C W

    1984-01-01

    This book presents a unified compilation of models and parameters appropriate for assessing the impact of radioactive discharges to the environment. Models examined include those developed for the prediction of atmospheric and hydrologic transport and deposition, for terrestrial and aquatic food-chain bioaccumulation, and for internal and external dosimetry. Chapters have been entered separately into the data base. (ACR)

  20. @neurIST complex information processing toolchain for the integrated management of cerebral aneurysms

    PubMed Central

    Villa-Uriol, M. C.; Berti, G.; Hose, D. R.; Marzo, A.; Chiarini, A.; Penrose, J.; Pozo, J.; Schmidt, J. G.; Singh, P.; Lycett, R.; Larrabide, I.; Frangi, A. F.

    2011-01-01

    Cerebral aneurysms are a multi-factorial disease with severe consequences. A core part of the European project @neurIST was the physical characterization of aneurysms to find candidate risk factors associated with aneurysm rupture. The project investigated measures based on morphological, haemodynamic and aneurysm wall structure analyses for more than 300 cases of ruptured and unruptured aneurysms, extracting descriptors suitable for statistical studies. This paper deals with the unique challenges associated with this task, and the implemented solutions. The consistency of results required by the subsequent statistical analyses, given the heterogeneous image data sources and multiple human operators, was met by a highly automated toolchain combined with training. A testimonial of the successful automation is the positive evaluation of the toolchain by over 260 clinicians during various hands-on workshops. The specification of the analyses required thorough investigations of modelling and processing choices, discussed in a detailed analysis protocol. Finally, an abstract data model governing the management of the simulation-related data provides a framework for data provenance and supports future use of data and toolchain. This is achieved by enabling the easy modification of the modelling approaches and solution details through abstract problem descriptions, removing the need of repetition of manual processing work. PMID:22670202

  1. Real-time surgery simulation of intracranial aneurysm clipping with patient-specific geometries and haptic feedback

    NASA Astrophysics Data System (ADS)

    Fenz, Wolfgang; Dirnberger, Johannes

    2015-03-01

    Providing suitable training for aspiring neurosurgeons is becoming more and more problematic. The increasing popularity of the endovascular treatment of intracranial aneurysms leads to a lack of simple surgical situations for clipping operations, leaving mainly the complex cases, which present even experienced surgeons with a challenge. To alleviate this situation, we have developed a training simulator with haptic interaction allowing trainees to practice virtual clipping surgeries on real patient-specific vessel geometries. By using specialized finite element (FEM) algorithms (fast finite element method, matrix condensation) combined with GPU acceleration, we can achieve the necessary frame rate for smooth real-time interaction with the detailed models needed for a realistic simulation of the vessel wall deformation caused by the clamping with surgical clips. Vessel wall geometries for typical training scenarios were obtained from 3D-reconstructed medical image data, while for the instruments (clipping forceps, various types of clips, suction tubes) we use models provided by manufacturer Aesculap AG. Collisions between vessel and instruments have to be continuously detected and transformed into corresponding boundary conditions and feedback forces, calculated using a contact plane method. After a training, the achieved result can be assessed based on various criteria, including a simulation of the residual blood flow into the aneurysm. Rigid models of the surgical access and surrounding brain tissue, plus coupling a real forceps to the haptic input device further increase the realism of the simulation.

  2. Local Quantification of Wall Thickness and Intraluminal Thrombus Offer Insight into the Mechanical Properties of the Aneurysmal Aorta.

    PubMed

    Martufi, Giampaolo; Satriano, Alessandro; Moore, Randy D; Vorp, David A; Di Martino, Elena S

    2015-08-01

    Wall stress is a powerful tool to assist clinical decisions in rupture risk assessment of abdominal aortic aneurysms. Key modeling assumptions that influence wall stress magnitude and distribution are the inclusion or exclusion of the intraluminal thrombus in the model and the assumption of a uniform wall thickness. We employed a combined numerical-experimental approach to test the hypothesis that abdominal aortic aneurysm (AAA) wall tissues with different thickness as well as wall tissues covered by different thrombus thickness, exhibit differences in the mechanical behavior. Ultimate tissue strength was measured from in vitro tensile testing of AAA specimens and material properties of the wall were estimated by fitting the results of the tensile tests to a histo-mechanical constitutive model. Results showed a decrease in tissue strength and collagen stiffness with increasing wall thickness, supporting the hypothesis of wall thickening being mediated by accumulation of non load-bearing components. Additionally, an increase in thrombus deposition resulted in a reduction of elastin content, collagen stiffness and tissue strength. Local wall thickness and thrombus coverage may be used as surrogate measures of local mechanical properties of the tissue, and therefore, are possible candidates to improve the specificity of AAA wall stress and rupture risk evaluations. PMID:25631202

  3. Influence of Intracranial Aneurysm-to-Parent Vessel Size Ratio on Hemodynamics and Implication for Rupture: Results from a Virtual Experimental Study

    PubMed Central

    Tremmel, Markus; Dhar, Sujan; Levy, Elad I.; Mocco, J; Meng, Hui

    2009-01-01

    OBJECTIVE The effectiveness of intracranial aneurysm (IA) size as a predictor for rupture has been debated. We recently performed a retrospective analysis of IA morphology and found that a new index, namely, aneurysm-to-parent vessel size ratio (SR), was strongly correlated with IA rupture, with 77% of ruptured IAs showing an SR of more than 2, and 83% of unruptured IAs showing an SR of 2 or less. As hemodynamics have been implicated in both IA development and rupture, we examine how varying SR influences intra-aneurysmal hemodynamics. METHODS One sidewall and 1 terminal IA were virtually reconstructed from patient 3-dimensional angiographic images. In 2 independent in silico experiments, the SR was varied from 1.0 to 3.5 by virtually changing either aneurysm size or vessel diameter while keeping the other parameter constant. Pulsatile computational fluid dynamics simulations were performed on each model for hemodynamics analysis. RESULTS Low SR (≤2) aneurysm morphology consistently demonstrated simple flow patterns with a single intra-aneurysmal vortex, whereas higher SR (>2) aneurysm morphology presented multiple vortices and complex flow patterns. The aneurysm luminal area that was exposed to low wall shear stress increased with increasing SR. Complex flow, multiple vortices, and low aneurysmal wall shear stress have been associated with ruptured IAs in previous studies. CONCLUSION Higher SR, irrespective of aneurysm type and absolute aneurysm or vessel size, gives rise to flow patterns typically observed in ruptured IAs. These results provide hemodynamic support for the existing correlation of SR with rupture risk. PMID:19349824

  4. Transcatheter wiring of abdominal aortic aneurysm

    SciTech Connect

    Rossi, P.; Simonetti, G.; Passariello, R.; Stipa, S.; Cavallaro, A.

    1983-04-01

    A new technique of transcatheder wiring of unresectable aortic aneurysm is described that provides simultaneous transcatheder occlusion of both common iliac arteries followed by exillofemoral bypass. The spring coil used for aortic aneurysm wiring was of our own making. The outer portion of a movable core stainless steel guidewire was bent in a coil shape and introduced into the aneurysm through a 7 French Teflon catheder via the right femoral artery. The same catheder was also used for coil embolus occlusion of both iliac arteries.

  5. Identifying Heterogeneous Anisotropic Properties in Cerebral Aneurysms: A Pointwise Approach

    PubMed Central

    Zhao, Xuefeng; Raghavan, Madhavan L.; Lu, Jia

    2014-01-01

    The traditional approaches of estimating heterogeneous properties in a soft tissue structure using optimization based inverse methods often face difficulties because of the large number of unknowns to be simultaneously determined. This article proposes a new method for identifying the heterogeneous anisotropic nonlinear elastic properties in cerebral aneurysms. In this method, the local properties are determined directly from the pointwise stress-strain data, thus avoiding the need for simultaneously optimizing for the property values at all points/regions in the aneurysm. The stress distributions needed for a pointwise identification are computed using an inverse elastostatic method without invoking the material properties in question. This paradigm is tested numerically through simulated inflation tests on an image-based cerebral aneurysm sac. The wall tissue is modeled as an eight-ply laminate whose constitutive behavior is described by an anisotropic hyperelastic strain-energy function containing four parameters. The parameters are assumed to vary continuously in the sac. Deformed configurations generated from forward finite element analysis are taken as input to inversely establish the parameter distributions. The delineated and the assigned distributions are in excellent agreement. A forward verification is conducted by comparing the displacement solutions obtained from the delineated and the assigned material parameters at a different pressure. The deviations in nodal displacements are found to be within 0.2% in most part of the sac. The study highlights some distinct features of the proposed method, and demonstrates the feasibility of organ level identification of the distributive anisotropic nonlinear properties in cerebral aneurysms. PMID:20490886

  6. Assessment of turbulent models for scramjet flowfields

    NASA Technical Reports Server (NTRS)

    Sindir, M. M.; Harsha, P. T.

    1982-01-01

    The behavior of several turbulence models applied to the prediction of scramjet combustor flows is described. These models include the basic two equation model, the multiple dissipation length scale variant of the two equation model, and the algebraic stress model (ASM). Predictions were made of planar backward facing step flows and axisymmetric sudden expansion flows using each of these approaches. The formulation of each of these models are discussed, and the application of the different approaches to supersonic flows is described. A modified version of the ASM is found to provide the best prediction of the planar backward facing step flow in the region near the recirculation zone, while the basic ASM provides the best results downstream of the recirculation. Aspects of the interaction of numerica modeling and turbulences modeling as they affect the assessment of turbulence models are discussed.

  7. [Twenty Years' Experience of the Surgical Treatment of Giant Ascending Aortic Aneurysms].

    PubMed

    Charchan, E R; Stepanenko, A B; Gens, A P; Skvorstov, A A; Galeev, N A; Belov, Yu V

    2015-01-01

    Giant ascending aortic aneurysm is one of the worst lesions of the cardiovascular system. Timely surgical treatment provides the only chance to prolong the lives of such patients. Life expectancy without surgery in these patients is minimal; they die from a ruptured aneurysm or decompensation of organs and systems. In this paper, based on two decades' experience of treating patients with giant aneurysms of ascending aorta and aortic arch in B.V. Petrovsky National Research Center of Surgery we have assessed evaluated immediate results of surgery and proposed measures for prevention of possible complications. Out of 53 patients with giant. ascending aortic aneurysms spontaneous rupture after sternotomy or opening of the pericardium occurred in 5 cases. Overall hospital mortality was 1.9%. Our results indicate that with the right tactics surgical repair of giant ascending aortic aneurysms can be performed with a low mortality. Preliminary cardiopulmonary bypass with peripheral cannulation and cooling prior to sternotomy for the possibility of circulatory arrest is a prerequisite of the prevention of fatal massive hemorrhage. PMID:26898093

  8. Experimental Study of a Thoracic Aortic Aneurysm Prior to and After Surgical Repair Hemodynamics

    NASA Astrophysics Data System (ADS)

    Kerlo, Anna-Elodie; Frankel, Steven; Chen, Jun; Vlachos, Pavlos

    2014-11-01

    Once a Thoracic Aortic Aneurysm (TAA) is detected, the risk of rupture is estimated based on the TAA diameter compared to the normal aortic diameter and its expansion rate. However, there are no reliable predictors that can provide accurate prognosis, and each aneurysm may progress differently. This work aims to assess the hemodynamic characteristics and flow structures associated with TAAs. The flow in a patient specific thoracic aortic aneurysm is compared to the same patient after treatment, in order to quantify the differences in the hydrodynamic forces acting on the aneurysm. Flow visualization with dye and Particle Image Velocimetry (PIV) are used to study flow features within both geometries. Local flow patterns are visualized to predict potential areas of recirculation and low shear stresses as they are associated with thrombogenicity. Understanding the differences in flow features between a thoracic aortic aneurysm and a normal aorta (or a TAA after surgical repair) may lead to a better understanding of disease mechanisms that will enable clinicians to better estimate the risk of rupture.

  9. Position dependent right ventricular dysfunction caused by a giant right coronary artery aneurysm.

    PubMed

    Mora, Bruno; Urbanek, Bernhard; Loewe, Christian; Grimm, Michael; Dworschak, Martin

    2011-01-01

    We describe an instructive case of a 79-year-old patient with a giant coronary aneurysm and a second smaller aneurysm with an uncommon symptomatology. Giant coronary artery aneurysms (>2 cm diameter) are rare pathologic entities with a prevalence of 0.02%. They either can be congenital malformations or are atherosclerotic in origin. Although spontaneous rupture of giant coronary artery aneurysms has been reported, they generally remain silent or induce myocardial ischemia. Our patient, however, showed no signs of myocardial malperfusion but transient position-dependent pre-syncope. The cardiologic work-up and the intraoperative considerations regarding patient management are described. During surgery, manipulation of the giant coronary artery aneurysm caused impairment of right ventricular function and regional wall hypokinesia, as assessed by transesophageal echocardiography. Venous cannulation of the right atrium was thus abandoned and extracorporeal circulation was established via the femoral vein. Subsequent dissection and surgical repair were uneventful and further recovery of the elderly patient was uncomplicated. This case underlines that once the diagnosis is established, proper perioperative management enables successful surgical treatment even of patients of advanced age. PMID:21253776

  10. Fold assessment for comparative protein structure modeling.

    PubMed

    Melo, Francisco; Sali, Andrej

    2007-11-01

    Accurate and automated assessment of both geometrical errors and incompleteness of comparative protein structure models is necessary for an adequate use of the models. Here, we describe a composite score for discriminating between models with the correct and incorrect fold. To find an accurate composite score, we designed and applied a genetic algorithm method that searched for a most informative subset of 21 input model features as well as their optimized nonlinear transformation into the composite score. The 21 input features included various statistical potential scores, stereochemistry quality descriptors, sequence alignment scores, geometrical descriptors, and measures of protein packing. The optimized composite score was found to depend on (1) a statistical potential z-score for residue accessibilities and distances, (2) model compactness, and (3) percentage sequence identity of the alignment used to build the model. The accuracy of the composite score was compared with the accuracy of assessment by single and combined features as well as by other commonly used assessment methods. The testing set was representative of models produced by automated comparative modeling on a genomic scale. The composite score performed better than any other tested score in terms of the maximum correct classification rate (i.e., 3.3% false positives and 2.5% false negatives) as well as the sensitivity and specificity across the whole range of thresholds. The composite score was implemented in our program MODELLER-8 and was used to assess models in the MODBASE database that contains comparative models for domains in approximately 1.3 million protein sequences. PMID:17905832

  11. Endovascular treatment of popliteal aneurysm.

    PubMed

    de Donato, G; Setacci, F; Galzerano, G; Borrelli, M P; Mascolo, V; Mazzitelli, G; Ruzzi, U; Setacci, C

    2015-08-01

    Although traditional surgical repair by aneurysm exclusion and bypass is still considered the gold standard in the treatment of popliteal artery aneurysms (PAAs), the endovascular repair (ER) has been gaining great interest in the last decades. ER offers several advantages over open bypass, including lower morbidity and mortality, and faster functional recovery, but some concerns about migration, occlusion, or fracture remain when a stent graft is deployed across a joint that undergo constant flexion. This review summarizes the current evidence on ER for PAAs. Level I evidence is still very limited, while the majority of published data come from retrospective studies. Moreover the heterogeneity of PAA morphology seems to play a major role in the outcomes after popliteal endografts placement, so that many anatomical criteria should be taken into account to determine which patient is best treated endovascularly. In conclusion, while it is unlike that endovascular treatment may displace open surgical bypass in the near future, it indeed does provide a feasible option for selected patients with high surgical risk and good anatomical features. PMID:25742934

  12. Infectious or Noninfectious? Ruptured, Thrombosed Inflammatory Aortic Aneurysm with Spondylolysis

    SciTech Connect

    Stefanczyk, Ludomir; Elgalal, Marcin; Papiewski, Andrzej; Szubert, Wojciech; Szopinski, Piotr

    2013-06-15

    Osteolysis of vertebrae due to inflammatory aortic aneurysm is rarely observed. However, it is estimated that up to 10 % of infectious aneurysms coexist with bone tissue destruction, most commonly the vertebrae. Inflammatory aneurysms with no identified infection factor, along with infiltration of adjacent muscle and in particular extensive destruction of bone tissue have rarely been described in the literature. A case of inflammatory aneurysm with posterior wall rupture and inflammatory infiltration of the iliopsoas muscle and spine, together with extensive vertebral body destruction, is presented. The aneurysm was successfully treated with endovascular aneurysm repair EVAR.

  13. Mycotic aneurysm accompanied by aspergillotic granuloma: a case report.

    PubMed

    Kurino, M; Kuratsu, J; Yamaguchi, T; Ushio, Y

    1994-08-01

    Solid granulomas and aneurysms caused by Aspergillus of the central nervous system are rare. A fungal aneurysm is usually situated proximally on the intracranial vessels and is often fatal. We report a case in which a ruptured aneurysm arose from the distal portion of the left posterior inferior cerebellar artery (PICA) in the course of treatment for chronic meningitis forming a granuloma at the left pyramis. After biopsy of the granuloma, he presented subarachnoid hemorrhage caused by a saccular PICA aneurysm. Histologic examination of the aneurysmal wall and the granuloma revealed infection with Aspergillus hyphae. The literature regarding the management of aspergillotic aneurysm is reviewed. PMID:8091294

  14. Delayed Vasospasm after Aneurysmal Subarachnoid Hemorrhage in Behcet Syndrome

    PubMed Central

    Kim, Jun Hak; Lee, Si-Un; Huh, Choonwoong; Oh, Chang Wan; Bang, Jae Seung

    2016-01-01

    A man visited the emergency room with a headache. Brain computed tomography showed aneurysmal subarachnoid hemorrhage (SAH) and multiple aneurysms. After aneurysm clipping surgery, the patient was discharged. After 5 days, he was admitted to the hospital with skin ulceration and was diagnosed with Behcet syndrome. An angiogram taken 7 weeks after aneurysmal SAH showed intracranial vasospasm. Because inflammation in Behcet syndrome may aggravate intracranial vasospasm, intracranial vasospasm after aneurysmal SAH in Behcet syndrome should be monitored for longer compared to general aneurysmal SAH. PMID:27114963

  15. An unexpected pulmonary arterial aneurysm in a COPD patient.

    PubMed

    Karkoulias, K; Lykouras, D; Nanopoulou, M; Tsiamita, M; Iliopoulos, P; Spiropoulos, K

    2011-01-01

    We present a case of an idiopathic pulmonary artery aneurysm in an asymptomatic patient who was treated for an irrelevant medical condition. Pulmonary artery aneurysms (PAA) are quite rare and can either be congenital or acquired. Congenital aneurysms are usually associated with cardiac malformations leading to pulmonary hypertension. Acquired aneurysms can be idiopathic or associated with infections (tuberculosis, syphilis), trauma, pulmonary valvular stenosis, or collagen diseases. Pulmonary artery aneurysms are not common and an idiopathic pulmonary artery aneurysm is a rare finding that could be diagnosed incidentally. PMID:22145274

  16. General technical considerations for the endovascular management of cerebral aneurysms.

    PubMed

    Eboli, Paula; Ryan, Robert W; Alexander, Michael J

    2014-07-01

    Cerebral aneurysms pose a threat to patients because of their risk of rupture causing subarachnoid hemorrhage, and the goal of treatment is the exclusion of the aneurysm from the circulation to prevent bleeding (in the case of unruptured aneurysms) or rebleeding. This article analyzes the general technical factors associated with the endovascular treatment of cerebral aneurysms. It discusses issues with transarterial access; imaging of aneurysm size, morphology, and regional anatomy to determine the endovascular plan; the techniques for the major endovascular aneurysm devices; and periprocedural management issues to reduce potential treatment-related complications. PMID:24994079

  17. ASSESSMENT OF VENOUS THROMBOSIS IN ANIMAL MODELS

    PubMed Central

    SP, Grover; CE, Evans; AS, Patel; B, Modarai; P, Saha; A, Smith

    2016-01-01

    Deep vein thrombosis and common complications, including pulmonary embolism and post thrombotic syndrome, represent a major source of morbidity and mortality worldwide. Experimental models of venous thrombosis have provided considerable insight into the cellular and molecular mechanisms that regulate thrombus formation and subsequent resolution. Here we critically appraise the ex vivo and in vivo techniques used to assess venous thrombosis in these models. Particular attention is paid to imaging modalities, including magnetic resonance imaging, micro computed tomography and high frequency ultrasound that facilitate longitudinal assessment of thrombus size and composition. PMID:26681755

  18. Saccular Aneurysms of the Transverse Aortic Arch

    PubMed Central

    Preventza, Ourania; Coselli, Joseph S.

    2015-01-01

    Saccular aneurysms of the aortic arch, whether single or multiple, are uncommon. The choice of repair technique is influenced by patients' comorbidities and age. Repairing saccular aneurysms with traditional open techniques can be technically demanding; therefore, endovascular technology and a variety of hybrid approaches have been developed to facilitate such repairs and, potentially, to improve clinical outcomes, especially in high-risk patients. There have been no large, randomized studies to compare the outcomes of these different treatment options in patients with single or multiple saccular aneurysms of the arch. In this review, we outline the etiology and common locations of these aneurysms, the different open, completely endovascular, and hybrid techniques used to treat them, and the treatment selection process. PMID:26798759

  19. Tubercular mycotic aortic aneurysm: A case report

    PubMed Central

    Kumar, Satish; Babu, NM Sharath; Jaret, Pramod; Sharma, Ashok

    2016-01-01

    Tubercular aneurysms of larger vessels, particularly the aorta is very rare. The first case of tubercular involvement of the aorta in the form of aortitis was reported in 1882 by Weigert and the first case of tubercular mycotic aneurysm of the aorta was reported in 1895. The preoperative diagnosis of tubercular aortic aneurysm is difficult. Even at surgery, determining the tubercular nature of the lesion is problematic. The gross appearance may not be distinctive, and acid-fast stains are unlikely to be performed. We report the case of a young female patient who was started on antitubercular treatment for pleural effusion and was found to have aortic aneurysm, which later on proved to be tubercular in origin. PMID:27051108

  20. Microsurgical technique of symptomatic intracavernous aneurysm.

    PubMed

    Liao, Chih-Hsiang; Lin, Chun-Fu; Hsu, Sanford P C; Chen, Min-Hsiung; Shih, Yang-Hsin

    2015-07-01

    Symptomatic intracavernous aneurysm is rare. Cranial nerves in the cavernous sinus are subjected to the mass effect of an expanding aneurysm. Microsurgical clipping is the treatment of choice to relieve compressive cranial neuropathy. In this video, the authors present a case of intracavernous aneurysm causing diplopia, ptosis, and facial numbness. The patient was operated on via a pretemporal transclinoid-transcavernous approach. The aneurysm was completely obliterated through direct clipping. There were no new-onset neurologic deficits and complications after the operation. Complete recovery of the diplopia, ptosis, and facial numbness was observed at the 6-month postoperative follow up. The video can be found here: http://youtu.be/4w5QUoNIAQM. PMID:26132609

  1. Successful embolization of a suprascapular artery aneurysm.

    PubMed

    Bucci, Federico; P, Plagnol; B, Salvati; R, Capoano; L, Fiengo; A, Redler

    2014-01-01

    A 45-year-old woman was referred to our service because 9 months earlier she had developed a pulsating mass on the right supraclavicular fossa and torticollis. Ultrasounds and computed tomographic arteriography showed the presence of a subclavian collateral artery aneurysm with a diameter of 21 mm. On selective arteriography, an aneurysm of a suprascapular artery arising directly from the right subclavian artery was reported. The presence of thoracic outlet syndrome was excluded. The aneurysm was successfully treated with ethylene-vinyl alcohol polymer, a liquid embolic agent. The patient was discharged on postoperative day 1 in good general condition. After 12 months, control ultrasounds confirmed the complete thrombosis of the aneurysm sac. PMID:21620668

  2. Endovascular repair of thoracic aortic aneurysms.

    PubMed

    Cartes-Zumelzu, F; Lammer, J; Kretschmer, G; Hoelzenbein, T; Grabenwöger, M; Thurnher, S

    2000-03-01

    The standard technique for the treatment of descending thoracic aortic aneurysms is elective open surgical repair with graft interposition. This standard approach, although steadily improving, is associated with high morbidity and substantial mortality rates and implies a major surgical procedure with lateral thoracotomy, use of cardiopulmonary bypass, long operation times and a variety of peri- and postoperative complications. This and the success of the first endoluminal treatment of abdominal aortic aneurysms by Parodi et al. prompted the attention to be thrown on the treatment of descending thoracic aortic aneurysms with endoluminal stent-grafts in many large centres. The aim of this new minimally invasive technique is to exclude the aneurysm from blood flow and in consequence to avoid pressure stress on the aneurysmatic aortic wall, by avoiding a large open operation with significant perioperative morbidity. The potentially beneficial effect of this new treatment approach was evaluated in the course of this study. PMID:10875224

  3. Abdominal aortic aneurysm--the forgotten diagnosis?

    PubMed Central

    Contini, S.; McMaster, P.

    1980-01-01

    A review of all cases of abdominal aortic aneurysm presenting to Addenbrooke's Hospital, Cambridge, in a 4-year period revealed that there were 118 such patients and confirmed the relatively low operative mortality for elective aneurysmal surgery (6.6%) compared with the high mortality (66.6%) for ruptured or leaking abdominal aneurysm. In only 50% of the cases was the correct diagnosis made during the lifetime of the patient; nor was the correct diagnosis always made after admission to hospital. The need for an early and accurate diagnosis of abdominal aneurysms is stressed and an increased awareness of this condition, based on well established clinical features, would undoubtedly reduce the overall mortality. Images Fig. 1 PMID:7393787

  4. Giant intracranial aneurysms: rapid sequential computed tomography

    SciTech Connect

    Pinto, R.S.; Cohen, W.A.; Kricheff, I.I.; Redington, R.W.; Berninger, W.H.

    1982-11-01

    Giant intracranial aneurysms often present as mass lesions rather than with subarachnoid hemorrhage. Routine computed tomographic (CT) scans with contrast material will generally detect them, but erroneous diagnosis of basal meningioma is possible. Rapid sequential scanning (dynamic CT) after bolus injection of 40 ml of Renografin-76 can conclusively demonstrate an intracranial aneurysm, differentiating it from other lesions by transit-time analysis of the passage of contrast medium. In five patients, the dynamics of contrast bolus transit in aneurysms were consistently different from the dynamics in pituitary tumors, craniopharyngiomas, and meningiomas, thereby allowing a specific diagnosis. Dynamic CT was also useful after treatment of the aneurysms by carotid artery ligation and may be used as an alternative to angiographic evaluation in determining luminal patency or thrombosis.

  5. Flow diversion and coil embolization may perform best in conjunction for treatment of intracranial aneurysms: a hemodynamic investigation

    NASA Astrophysics Data System (ADS)

    Damiano, Robert; Ma, Ding; Siddiqui, Adnan; Meng, Hui

    2015-11-01

    Coiling and flow diversion is the current standard for treatment of intracranial aneurysms (IAs). Coils deployed into the IA sac trigger its thrombotic occlusion, while flow diverters (FDs) deployed across the IA ostium redirect blood flow and reconstruct the parent vessel. Despite the wide adoption of these interventions, poor treatment outcomes have been reported. Recent clinical reports indicate that IA patients treated with both coils and FDs had better outcomes, compared to individual strategies alone. To better understand the hemodynamic mechanisms underlying coiling and flow diversion, we applied our advanced FEM-based device modeling toolset in conjunction with CFD to investigate 3 clinical strategies: coiling, FD, and FD with adjunctive coiling. Using 3 patient-specific IAs as test beds, we assessed the hemodynamic modifications induced by each strategy. Hemodynamic modifications in inflow rate, velocity, and wall shear stress revealed that coils were most effective at reducing intra-aneurysmal flow, while FD worked best at reducing flow into the IA sac. When coils were combined with FD, these effects appeared to be synergistically enhanced. Our modeling results support clinical observations that flow diversion and coiling may work best in conjunction for treating IAs. Funded by the National Institutes of Health (1R01 NS 091075-01).

  6. Finite-element-based matching of pre- and intraoperative data for image-guided endovascular aneurysm repair

    PubMed Central

    Dumenil, Aurélien; Kaladji, Adrien; Castro, Miguel; Esneault, Simon; Lucas, Antoine; Rochette, Michel; Goksu, Cemil; Haigron, Pascal

    2013-01-01

    Endovascular repair of abdominal aortic aneurysms is a well-established technique throughout the medical and surgical communities. Although increasingly indicated, this technique does have some limitations. Because intervention is commonly performed under fluoroscopic control, two-dimensional (2D) visualization of the aneurysm requires the injection of a contrast agent. The projective nature of this imaging modality inevitably leads to topographic errors, and does not give information on arterial wall quality at the time of deployment. A specially-adapted intraoperative navigation interface could increase deployment accuracy and reveal such information, which preoperative three-dimensional (3D) imaging might otherwise provide. One difficulty is the precise matching of preoperative data (images and models) and intraoperative observations affected by anatomical deformations due to tool-tissue interactions. Our proposed solution involves a finite element-based preoperative simulation of tool/tissue interactions, its adaptive tuning regarding patient specific data, and the matching with intra-operative data. The biomechanical model was first tuned on a group of 10 patients and assessed on a second group of 8 patients. PMID:23269745

  7. Flow residence time and regions of intraluminal thrombus deposition in intracranial aneurysms.

    PubMed

    Rayz, V L; Boussel, L; Ge, L; Leach, J R; Martin, A J; Lawton, M T; McCulloch, C; Saloner, D

    2010-10-01

    Thrombus formation in intracranial aneurysms, while sometimes stabilizing lesion growth, can present additional risk of thrombo-embolism. The role of hemodynamics in the progression of aneurysmal disease can be elucidated by patient-specific computational modeling. In our previous work, patient-specific computational fluid dynamics (CFD) models were constructed from MRI data for three patients who had fusiform basilar aneurysms that were thrombus-free and then proceeded to develop intraluminal thrombus. In this study, we investigated the effect of increased flow residence time (RT) by modeling passive scalar advection in the same aneurysmal geometries. Non-Newtonian pulsatile flow simulations were carried out in base-line geometries and a new postprocessing technique, referred to as "virtual ink" and based on the passive scalar distribution maps, was used to visualize the flow and estimate the flow RT. The virtual ink technique clearly depicted regions of flow separation. The flow RT at different locations adjacent to aneurysmal walls was calculated as the time the virtual ink scalar remained above a threshold value. The RT values obtained in different areas were then correlated with the location of intra-aneurysmal thrombus observed at a follow-up MR study. For each patient, the wall shear stress (WSS) distribution was also obtained from CFD simulations and correlated with thrombus location. The correlation analysis determined a significant relationship between regions where CFD predicted either an increased RT or low WSS and the regions where thrombus deposition was observed to occur in vivo. A model including both low WSS and increased RT predicted thrombus-prone regions significantly better than the models with RT or WSS alone. PMID:20499185

  8. A meta-analysis of aneurysm formation in laser assisted vascular anastomosis (LAVA)

    NASA Astrophysics Data System (ADS)

    Chen, Chen; Peng, Fei; Xu, Dahai; Cheng, Qinghua

    2009-08-01

    Laser assisted vascular anastomosis (LAVA) is looked as a particularly promising non-suture method in future. However, aneurysm formation is one of the main reasons delay the clinical application of LAVA. Some scientists investigated the incidence of aneurysms in animal model. To systematically analyze the literature on reported incidence of aneurysm formation in LAVA therapy, we performed a meta-analysis comparing LAVA with conventional suture anastomosis (CSA) in animal model. Data were systematically retrieved and selected from PUBMED. In total, 23 studies were retrieved. 18 studies were excluded, and 5 studies involving 647 animals were included. Analysis suggested no statistically significant difference between LAVA and CSA (OR 1.24, 95%CI 0.66-2.32, P=0.51). Result of meta analysis shows that the technology of LAVA is very close to clinical application.

  9. Carotid artery aneurysm: last among equals.

    PubMed

    Dhillon, Ajit Kaur; Rowlands, Timothy; McMahon, Greg

    2016-01-01

    A 66-year-old man presented initially with a swelling in the left side of the neck, which was confirmed to be a carotid artery aneurysm on ultrasonography. He was subsequently admitted reporting intermittent episodes of visual loss in the left eye and right arm weakness. Further imaging confirmed multiple, small acute infarcts in the left cerebral hemisphere. The patient underwent open repair of the aneurysm and made an uncomplicated recovery with no persisting neurological deficit. PMID:27190119

  10. [Centralisation of treatment of ruptured aneurysm].

    PubMed

    Akkersdijk, Willem L; Akkersdijk, George J M; Akkersdijk, George P

    2014-01-01

    In the future, patients with a ruptured aneurysm will be treated at fewer hospitals in the Netherlands. Although there is a search for scientific support for this, the reason for centralisation is obvious: reduction of costs and reduction of workload for vascular surgeons during night and weekend shifts. Already there are a number of examples of regionally organised vascular surgeons who treat their patients with a ruptured aneurysm with great satisfaction and with good results. PMID:25563776

  11. Endovascular treatment of frontopolar artery aneurysm.

    PubMed

    Karanam, Lakshmi S Prasanna; Alurkar, Anand; Chakka, Sivaramakrishna

    2016-08-01

    Traumatic intracranial aneurysms are rare and usually present with subarachnoid hemorrhage, intracranial hemorrhage, subdural hematoma, or intraventricular hemorrhage. These are usually not true aneurysms; hence treatment of these cases poses a therapeutic challenge. In this case report, we describe a young Asian male who presented with a ruptured pseudoaneurysm of the distal branch of the anterior cerebral artery. It was treated successfully with endovascular embolization. To our knowledge, there are few reports of this entity in the literature. PMID:27048313

  12. Multiple Intracranial Aneurysms in HIV Infection.

    PubMed

    Dhawan, Sumeet R; Gupta, Anju; Gupta, Vivek; Singhi, Pratibha D

    2016-08-01

    Neurological findings in HIV are common and include cognitive impairment, microcephaly, nonspecific white matter lesions and seizures. Cerebral vasculopathy and stroke are uncommon and may be due to primary HIV vasculopathy or opportunistic infections such as tuberculosis and cryptococcal meningitis. The authors describe a 7-y-old boy who presented with severe headache and was detected to have aneurysmal bleed due to intracranial aneurysm. PMID:27072660

  13. [Diagnostic challenges of aneurysmal subarachnoid hemorrhage].

    PubMed

    Vehviläinen, Juho; Niemelä, Mika; Korja, Miikka

    2016-01-01

    Diagostic approach to aneurysmal subarachnoid hemorrhage (aSAH) is based on computer tomography (CT) imaging, although a lumbar puncture and subsequent cerebrospinal fluid analysis is sometimes necessary. Identification of the ruptured aneurysm is done using angiography. Despite of modern imaging techniques, diagnostic definition of aSAH is still occasionally challenging. We describe three cases in which the diagnosis of aSAH has been delayed, in spite of positive imaging or lumbar puncture findings. PMID:27089620

  14. Intracranial aneurysms: analysis of results of microneurosurgery.

    PubMed Central

    Adams, C B; Loach, A B; O'laoire, S A

    1976-01-01

    Subarachnoid haemorrhage from intracranial aneurysms has a poor prognosis. Operative management of intracranial aneurysms was once considered ineffective. The first 100 cases treated by micorsurgery were analysed to see whether mortality and morbidity were reduced. Modern surgical techniques halved the total mortality but the morbidity was unaltered. Results can be improved by delaying surgery seven days and by treating any hypertension before surgery. PMID:963461

  15. Mycotic aneurysm of the aortic arch.

    PubMed

    Aliaga, L; Cobo, F; Miranda, C; Lara, J

    2000-01-01

    A 61-year-old diabetic woman presented with a mycotic aneurysm of the aortic arch, also involving the left subclavian and vertebral arteries, caused by Staphylococcus aureus. Two months before, she had suffered from staphylococcal septic arthritis in her left knee. The patient was treated with antibiotics and an emergency operation was performed involving aneurysm excision and in situ synthetic graft replacement. She died on the fourth postoperative day from hemorrhagic shock. PMID:10961533

  16. Bronchial Artery Aneurysm Embolization with NBCA

    SciTech Connect

    Aburano, Hiroyuki Kawamori, Yasuhiro; Horiti, Yasushi; Kitagawa, Kiyohide; Sanada, Junichiro; Matsui, Osamu

    2006-12-15

    We present a case of asymptomatic bronchial artery aneurysm that formed a fistula with part of the pulmonary artery (there was no definite fistula with the pulmonary vein). We were able to catheterize the feeding vessel but could not reach the aneurysm. We therefore injected a mixture of N-butyl-2-cyanoacrylate (NBCA; Histoacryl, B. Braun, Melsungen, Germany) and iodized oil (Li