Aneurysm Wall Research Articles

Overview of perianeurysmal edema following the endovascular management of cerebral aneurysms: A pooled analysis of 48 cases.

Perianeurysmal edema occurring after endovascular treatment for cerebral aneurysms is uncommon compared to surgical clipping. The clinical aspects and the exact explanation are poorly understood. We searched PubMed, Google Scholar, and Web of Science. We used the following keywords: "endovascular management of cerebral aneurysms," "perianeurysmal cerebral edema," "perianeurysmal cerebral edema after endovascular treatment endovascular treatment," "intracranial aneurysms with perianeurysmal edema," and "vessel wall enhancement after endovascular therapy." For each case, demographic, clinicopathological, therapeutic, and follow-up data were gathered and analyzed. Perianeurysmal edema after endovascular treatment has a clear female predilection, with a male: female ratio of 12:29 (25%; 60.41%). The average time from EVT to the onset of edema ranged from 1day to about 8years. The aneurysm dimension ranged from 6.8 to 25mm as the largest size reported. Most patients were asymptomatic (18 [37.5 %]), and headache was the presenting symptom in 10 patients (20.8%). Aneurysmal wall enhancement was reported in 16 (33.3 %) patients with perianeurysmal edema. About 12 patients (25%) developed post-EVT hydrocephalus. The most common coil used was the platinum type (31 [64.58%]). Most of the patients were treated expectantly with follow-up (17 [35.41 %]), while steroids were used only in 14 (29.16%) patients. Most of the patients have their edema resolved (29 [60.41%]) or stable (9 [37.5%]). There is growing evidence supporting the incidence of post-embolization inflammatory reactions involving the vessel wall and the surrounding parenchyma; however, the exact clinical perspectives and the predisposing factors are not fully uncovered. This analysis highlights the possible presentations and short-term outcome of patients presenting with perianeurysmal edema after endovascular management of cerebral aneurysms.

Near-Wall Slow Flow Contributes to Wall Enhancement of Middle Cerebral Artery Bifurcation Aneurysms on Vessel Wall MRI

Background: The mechanism of aneurysm wall enhancement (AWE) in middle cerebral artery (MCA) bifurcation aneurysms on vessel wall magnetic resonance imaging (VW-MRI) remains unclear. We aimed to explore the morphologically related hemodynamic mechanism for the AWE of MCA bifurcation aneurysms. Methods: Patients with unruptured MCA bifurcation aneurysms undergoing VW-MRI were enrolled. Logistic regression analyses were performed to determine the risk factors for AWE. Based on the results of retrospective analyses, bifurcation aneurysm silicone models with a specific aspect ratio (AR) were designed and underwent VW-MRI with different inlet velocities. Computational fluid dynamics (CFD) analyses were conducted on both silicone models and patients’ aneurysms. Results: A total of 104 aneurysms in 95 patients (mean age 60; 34 males) were included for baseline analysis and morphological analysis. Logistic regression analysis indicated AR (OR, 5.92; 95% CI, 2.00–17.55; p = 0.001) was associated with AWE. In the high-AR group of 45 aneurysms with AWE, the aneurysm sac exhibited lower blood flow velocity, lower wall shear stress, a larger proportion of low-flow regions and higher wall enhancement values. In total, 15 silicone models were analyzed, divided into three subgroups based on neck width (4 mm, 6 mm, and 8 mm). Each subgroup contained aneurysms with five different ARs: 1.0, 1.25, 1.5, 1.75, and 2.0. In silicone models, contrast enhancement (CE) was mainly located beneath the dome of the aneurysm wall. With the same inlet velocity, CE gradually increased as the AR increased. Similarly, at the same AR, CE increased as the inlet velocity decreased. CFD demonstrated a moderate positive correlation between the near-wall enhancement index and the ratio of the low-velocity area (r = 0.6672, p < 0.001). Conclusions: The AR is associated with the AWE of MCA bifurcation aneurysms. A high AR may promote wall enhancement by causing near-wall slow flow.

Contact pressure explains half of the abdominal aortic aneurysms wall thickness inter-study variability.

The stochastic rupture risk assessment of an abdominal aortic aneurysm (AAA) critically depends on sufficient data set size that would allow for the proper distribution estimate. However, in most published cases, the data sets comprise no more than 100 samples, which is deemed insufficient to describe the tails of AAA wall thickness distribution correctly. In this study, we propose a stochastic Bayesian model to merge thickness data from various groups. The thickness data adapted from the literature were supplemented by additional data from 81 patients. The wall thickness was measured at two different contact pressures for 34 cases, which allowed us to estimate the radial stiffness. Herein, the proposed stochastic model is formulated to predict the undeformed wall thickness. Furthermore, the model is able to handle data published solely as summary statistics. After accounting for the different contact pressures, the differences in the medians reported by individual groups decreased by 45%. Combined data can be fitted with a lognormal distribution with parameters μ = 0.85 and σ = 0.32 which can be further used in stochastic analyses.

Irregular pulsation on 4D-CTA and quantitative wall enhancement on VW-MRI are associated with symptoms of unruptured intracranial aneurysms

BackgroundUnruptured intracranial aneurysms (IAs) that become symptomatic have been associated with instability.ObjectiveTo investigate the relationship between irregular pulsation on four-dimensional CT angiography (4D-CTA) and aneurysm wall enhancement (AWE) on vessel...

Intracranial aneurysm instability prediction model based on 4D-Flow MRI and HR-MRI

This study aims to develop a reliable predictive model for assessing intracranial aneurysm (IA) instability by utilizing four-dimensional flow magnetic resonance imaging (4D-Flow MRI) and high-resolution MRI (HR-MRI). Initially, we curated a prospective dataset, dubbed the primary cohort, by aggregating patient data that was consecutively enrolled across two centers from November 2018 to November 2021. Unstable aneurysms were defined as those with symptoms, morphological change or ruptured during follow-up periods. We introduce a specialized ensemble learning framework, termed the Hybrid Model, which synergistically combines two heterogeneous base learning algorithms: 4D-Flow logistic regression (4D-Flow-LR) and Multi-crop Attention Branch Network (MicroAB-Net). The ability of the hybrid model to predict aneurysm instability was compared with baseline models: PHASES (population, hypertension, age, size, earlier rupture, and site) LR, ELAPSS (earlier subarachnoid hemorrhage, location, age, population, size, and shape) LR, aneurysm wall enhancement (AWE) LR, and Radiomics using the area under the curve (AUC) with Delong's test. Finally, the Hybrid Model was further validated in the validation cohort (patients enrolled between December 2021 to May 2022). In the primary cohort, 189 patients (144 women [76.2 ​%]; aged 58.90 years ​± ​10.32) with 213 IAs were included. In the validation cohort, 48 patients (35 women [72.9 ​%]; aged 55.0 years ​± ​10.77) with 53 IAs were included. The Hybrid Model achieved the highest performance both in the primary cohort (AUC ​= ​0.854) and the validation cohort (AUC ​= ​0.876). The Hybrid model provided a promising prediction of aneurysm instability.

Management of venous aneurysms and the vascular surgical treatment options : Selection of representative case constellations illustrating experiences at acenter for vascular surgery

Venous aneurysms are arare entity in vascular surgery, which are mostly described in individual case series and meta-analyses generated from them. The treatment concepts are diverse and surgical treatment is highlighted due to the risk of thrombosis and pulmonary embolism. There is still an ongoing debate regarding the postoperative necessity and duration of anticoagulation. Case series of aconsecutive patient cohort with venous aneurysms from the last 18years in acenter of (highly specialized care) vascular surgery including i)own experiences obtained in daily vascular surgical practice and ii)aselected and current literature search of relevant references on possible and, in particular, established diagnosis-specific therapeutic concepts. Between 2005 and 2023, atotal of 11cases of venous aneurysms were reported in patients aged 30-84years (mean: 52.5, median: 50), with 1 patient requiring surgery for a recurrence after 2years. The gender ratio was 7:3 (m:f) and the popliteal vein was the most frequently affected anatomical region with 36.4%, followed by the internal jugular vein and axillary/subclavian vein each with 18.2%. Aneurysms of the inferior vena cava, the common iliac vein and the cubital vein occurred only once. Surgical treatment of the aneurysms was performed in 9cases. The surgical methods used were i)tangential resection of the aneurysm wall and continuous purse-string suture, ii)resection of the aneurysm and interposition of an 8‑mm GORE-TEX® vascular graft prosthesis (Gore, Putzbrunn, Germany), iii)ligation of the aneurysm and iv)ligation with subsequent resection of the aneurysm. The rarity of venous aneurysms should be a reason to register these cases centrally (possibly, nationwide diagnosis-related register). Surgical treatment is usually unproblematic and associated with few complications. The risk of pulmonary embolism appears to be significantly increased in venous aneurysms of the extremities, pelvic veins and inferior vena cava, while venous aneurysms of the head and neck are significantly less prone to this. Perioperative and postoperative anticoagulation has been adapted to the development of specific anticoagulants and novel drugs, in favor of treatment with direct oral anticoagulants (DOAC). In personal experience, immediate postoperative heparin perfusion (low dose) and subsequent therapeutic bridging with low-molecular-weight heparin before switching to an anticoagulant for outpatient clinic-based care appears to safeguard the perioperative phase with respect to keeping the surgery-related complication rate (e.g., thrombosis, bleeding) low.

Sequential Hemodynamic Analysis of Ruptured Posterior Communicating Artery Aneurysms Treated With Coil Embolization and Delayed Flow Diversion.

Computational fluid dynamics has advanced our knowledge of the pathogenesis of intracranial aneurysms and the dynamic changes observed after treatment. Herein, we analyze hemodynamic changes throughout the intervention stages for ruptured posterior communicating artery (PComA) aneurysms, treated with acute coiling and delayed flow diversion (FD). We performed a retrospective analysis of ruptured PComA aneurysms treated with the acute coiling and delayed FD strategy between June 2013 to November 2022, using 3-dimensional reconstructions of digital subtraction angiographies. Hemodynamic simulations using ANSYS® calculated aneurysmal and adjacent arteries' wall shear stress (WSS), aneurysmal low shear areas (LSA), and mean velocities in the distal arteries. Six of the 22 patients were selected for computational fluid dynamics analysis, including 4 females and 2 males with a median age of 60 years. The average aneurysm volume was 984.12 mm3, with an average surface area of 386.11 mm2; LSA was 22.90%, and the average WSS was 3.39 Pa. The 2 largest aneurysms also had the highest LSA values. After coiling, there was a reduction in the aneurysmal volume (-78.42%) and the average surface area (-55.28%), and aneurysmal WSS increased to 6.10 Pa (+79.90%). WSS values for the middle cerebral artery (MCA) increased to 10.76 Pa, while anterior cerebral artery (ACA) increased to 7.51 Pa. Complete occlusion was achieved with delayed FD at a median follow-up of 19.7 months. After FD, average WSS increased to 14.94 Pa for the MCA (+70.64%) and to 10.82 Pa for the ACA (+30.10%). The mean MCA velocity increased to 43.04 cm/s (+36.85%), and 3 cases showed an increase in ACA velocities. LSA may have triggered rupture for the PComA aneurysms analyzed. After coiling, average WSS increased in the aneurysm wall and downstream vessels in the majority of cases analyzed. Delayed FD caused hemodynamic disturbances distal to deployment, reflected in the sequential increase in the WSS and velocities in both the ACA and MCA.

Branching and nonbranching intracranial aneurysms in the presence of a persistent stapedial artery and an aberrant internal carotid artery assessed with computational hemodynamics: illustrative case.

The mechanisms underlying the initiation and progression of bifurcation versus lateral wall aneurysms are not well understood. Computational fluid dynamics (CFD) can improve the understanding of these mechanisms and can consequently help identify patients at higher risk for developing aneurysms and monitor them more closely. A 36-year-old man presented with a ruptured anterior communicating artery aneurysm, which was successfully treated with microsurgical clipping. Imaging also revealed a persistent stapedial artery with an elongated and tortuous posterior communicating artery (PComA). Fourteen years later, he was readmitted for a ruptured aneurysm on a PComA loop. CFD helped identify considerable collateral circulation due to the aberrant internal carotid artery (ICA). High flow rates trigger both types of aneurysms, but nuances exist in the hemodynamic mechanisms that drive their growth. Berry aneurysms and lateral wall aneurysms initially start due to a high flow rate, a common underlying cause. However, the formation of true sidewall aneurysms is primarily characterized by locally increased wall shear stress, while the development of berry aneurysms is mainly linked to high local blood pressure at arterial bifurcations. An aberrant ICA can lead to supraphysiological compensatory flow in the anterior and posterior circulation, increasing the risk of intracranial aneurysm formation at both branching and nonbranching sites, underscoring the need for lifelong monitoring. https://thejns.org/doi/10.3171/CASE24421.

First-in-Human Abdominal Aortic Aneurysms Trial with Tricaprin (F-HAAAT): Study Design and Protocol

Approximately 2–12% of individuals aged > 65 years worldwide are estimated to have an abdominal aortic aneurysm (AAA), with a mortality rate exceeding 60% in rupture cases. The sole preventive intervention against rupture is timely surgery, which requires substantial medical resources, including postoperative complication management. Although numerous randomized clinical trials have been performed, no oral medication effectively treats AAA. Tricaprin, a medium-chain triglyceride (MCT) with three capric acids, is used in dietary therapy for metabolic and neurological disorders. Our group recently reported that tricaprin, unlike other MCTs, showed reverse remodeling of AAA in a rat model. Determining whether this basic finding could be translated to clinical practice is important. The First-in-Human Abdominal Aortic Aneurysms trial with Tricaprin (F-HAAAT) proposes the first-in-human AAA trial to confirm the safety of tricaprin in patients with small AAA, exploring novel assessment methods to evaluate treatment efficacy. This single-center, open-label, single-arm study will include ten patients (aged 50–85 years) with small AAA (30–45 mm in diameter) receiving daily oral tricaprin (1.5–3.0 g/day) for 52 weeks. Primary endpoints include safety evaluation of tricaprin determined by monitoring all adverse events, particularly major adverse cardiovascular events, AAA-related adverse events, and other unpredictable events. Secondary endpoints include parameters to validate tricaprin efficacy by measuring AAA diameter, volume, and Agatston score, and analyzing computed tomography values of the aortic aneurysmal wall. F-HAAAT outcomes may provide insights into noninvasive methods for indirectly analyzing AAA pathological characteristics and revealing aneurysmal reverse remodeling. (jRCTs051240036, Japan Registry of Clinical Trials)

On the Relative Effects of Wall and Intraluminal Thrombus Constitutive Material Properties in Abdominal Aortic Aneurysm Wall Stress.

An abdominal aortic aneurysm (AAA) is a dilation localized in the infrarenal segment of the abdominal aorta that can expand continuously and rupture if left untreated. Computational methods such as finite element analysis (FEA) are widely used with in silico models to calculate biomechanical predictors of rupture risk while choosing constitutive material properties for the AAA wall and intraluminal thrombus (ILT). In the present work, we investigated the effect of different constitutive material properties for the wall and ILT on 21 idealized and 10 unruptured patient-specific AAA geometries. Three material properties were used to characterize the wall and two for the ILT, leading to six material model combinations for each AAA geometry subject to appropriate boundary conditions. The results of the FEA simulations indicate significant differences in the average peak wall stress (PWS), 99th percentile wall stress (99th WS), and spatially averaged wall stress (SAWS) for all AAA geometries subject to the choice of a material model combination. Specifically, using a material model combination with a compliant ILT yielded statistically higher wall stresses compared to using a stiff ILT, irrespective of the constitutive equation used to model the AAA wall. This work provides quantitative insight into the variability of the wall stress distributions ensuing from AAA FEA modeling due to its strong dependency on population-averaged soft tissue material characterizations. This dependency leads to uncertainty about the true biomechanical state of stress of an individual AAA and the subsequent assessment of its rupture risk.

Emergency microsurgical trapping, decompression, and revascularization of a middle cerebral artery dissecting aneurysm using a minipterional approach in a pediatric patient: illustrative case.

Pediatric intracranial aneurysms present unique diagnostic and therapeutic challenges due to their rarity and their distinct anatomical and physiological considerations compared with those of adult intracranial aneurysms. The authors present the case of a symptomatic pediatric patient who required emergency microsurgical treatment after a thrombosed dissecting aneurysm was identified in the right M1 segment of the middle cerebral artery. The lesion completely occluded its parent vessel, although distal blood flow was reconstituted through leptomeningeal collaterals. However, aneurysm wall contrast enhancement and signs of early perfusion changes were noticed, which prompted emergency treatment consisting of microsurgical aneurysm trapping, decompression, and extracranial/intracranial revascularization to be successfully performed through a minipterional craniotomy. After 1 year, the bypass occluded, although the patient remained asymptomatic. A slight enlargement of the ipsilateral anterior cerebral artery suggested the possibility of a benign hemodynamic rearrangement. Emergency treatment may be necessary when signs of lesion instability or hemodynamic compromise are present; however, a comprehensive multidisciplinary evaluation is required. Treatment of complex vascular lesions using a minipterional approach is feasible even in pediatric patients, and delayed bypass occlusion may be a benign phenomenon reflecting gradual blood flow reorganization. https://thejns.org/doi/10.3171/CASE24484.

Comparison and Significance of Contrast-Enhanced Computed Tomographic Findings of Large-Vessel Vasculitis Before and After Treatment: Differences Between Takayasu Arteritis and Giant Cell Arteritis.

Imaging is essential for diagnosing large-vessel vasculitis (LVV). During diagnostic imaging, assessing disease activity and vascular damage separately is important. Acute-phase findings represent disease activity, while chronic-phase findings represent vascular damage; however, whether the imaging findings are acute or chronic may be unclear. We investigated how vascular lesions change before and after treatment and whether they were acute- or chronic-phase findings. Fifty-one patients with LVV who had undergone contrast-enhanced computed tomography (CT) scans from the neck to the pelvis before treatment and 1-4 months after treatment were recruited. Wall thickening, wall contrast enhancement, stenosis, occlusion, dilation, aneurysm, and calcification were semi-quantitatively assessed in 21 vessels from the common carotid to the common iliac artery. Twenty-four patients were diagnosed with Takayasu arteritis (TAK), and 27 with giant cell arteritis (GCA). Wall thickening and wall contrast enhancement improved after the treatment, which was especially significant in the GCA group. No significant differences in stenosis, occlusion, dilation, aneurysm, or calcification were observed before and after treatment. Stenosis and occlusion were more common with TAK, while calcification was more common with GCA. Wall thickening and wall contrast enhancement are acute-phase findings (activity), while stenosis, occlusion, dilation, aneurysm, and calcification are chronic-phase findings (damage). The frequencies of these findings differ between TAK and GCA.

An In vivo Pilot Study to Estimate the Swelling of the Aneurysm Wall Rabbit Model Generated with Pulsed Fluid Against the Aneurysm Wall.

This study addresses the critical issue of evaluating the risk of rupture of unruptured intracranial aneurysms (UIAs) through the assessment of the mechanical properties of the aneurysm wall. To achieve this, an original approach based on the development of an in vivo deformation device prototype (DDP) of the vascular wall is proposed. The DDP operates by pulsing a physiological fluid onto the vascular wall and measuring the resulting deformation using spectral photon counting computed tomography (SPCCT) imaging. In this preliminary study conducted on a rabbit animal model, an aneurysm was induced on the carotid artery, followed by deformation of the aneurysm sac wall using the DDP. The change in luminal volume of the aneurysm sac induced by the deformation of the vascular wall was then quantified. The initial experimental results demonstrated an increase in the luminal volume of the aneurysm sac in relation to the increased flow rate of the fluid pulsed by the DDP onto the arterial wall. Measurement of the pressure generated by the DDP in relation to the different flow rate values imposed by the pulsation system revealed experimental values of the same order of magnitude as dynamic blood pressure. Furthermore, theoretical pressure values on the deformed area, calculated using Euler's theorem, appeared to be correlated with experimental pressure measurements. This equivalence between theory and experiment is a key element in the use of the DDP for estimating the mechanical properties of the vascular wall, particularly for the use of finite element models to characterise the stress state of the deformed vascular wall. This preliminary work thus presents a novel, innovative, and promising approach for the evaluation and management of the risk of rupture of unruptured intracranial aneurysms.

Exploring the hemodynamic behavior of residual aneurysms after coiling and clipping: A computational flow dynamic analysis.

Residual intracranial aneurysms post-clipping or coiling pose a poorly established risk of rupture. Computational fluid dynamic (CFD) offers insights into hemodynamic changes following such interventions. This study aims to assess hemodynamic parameters in residual aneurysms pre- and post-treatment with surgical clips or coils using CFD. A retrospective analysis of consecutive patients between January 2015 and January 2024 was conducted. Digital subtraction angiography images were reconstructed using 3D modeling techniques, and hemodynamic parameters were analyzed with ANSYS® software. Six aneurysms were analyzed: Five unruptured and one ruptured. The aneurysms were located at the basilar apex (2), middle cerebral artery bifurcation (2), and origin of the posterior communicating artery (2). Post-treatment, there was a significant reduction in both aneurysm area (median reduction of 33.73%) and volume (median reduction of 25.3%). Five of the six cases demonstrated fewer low wall shear stress (WSS) areas, which could indicate a reduction in regions prone to thrombus formation and diminished risk of rupture. In the unruptured aneurysms, there was a median increase of 137.6% in average WSS. Notably, the only case with increased low WSS area also had the highest increase in average WSS. One basilar artery aneurysm showed increased WSS across all parameters, suggesting a higher rupture risk. The increase in average and high WSS area, along with a decrease in low WSS area, reflects a complex balance between factors of stability and rupture risk. However, a simultaneous increase in all WSS parameters may represent the highest rupture risk due to increased mechanical stress on the aneurysm wall, necessitating closer monitoring.

Insight in the (Phospho)proteome of Vascular Smooth Muscle Cells Derived From Patients With Abdominal Aortic Aneurysm Reveals Novel Disease Mechanisms.

Abdominal aortic aneurysm (AAA) is characterized by weakening and dilatation of the aortic wall in the abdomen. The aim of this study was to gain insight into cell-specific mechanisms involved in AAA pathophysiology by analyzing the (phospho)proteome of vascular smooth muscle cells derived from patients with AAA compared with those of healthy donors. A (phospho)proteomics analysis based on tandem mass spectrometry was performed on vascular smooth muscle cells derived from patients with AAA (n=24) and healthy, control individuals (C-SMC, n=8). Following protein identification and quantification using MaxQuant, integrative inferred kinase activity analysis was used to calculate kinase activity scores. Expression differences between vascular smooth muscle cells derived from patients with AAA and healthy, control individuals were predominantly found in proteins involved in ECM (extracellular matrix) remodeling (THSD4 [thrombospondin type-1 domain-containing protein 4] and ADAMTS1 [A disintegrin and metalloproteinase with thrombospondin motifs 1]), energy metabolism (GYS1 [glycogen synthase 1] and PCK2 [phosphoenolpyruvate carboxykinase 2, mitochondrial]), and contractility (CACNA2D1 [calcium voltage-dependent channel subunit α-2/δ-1] and TPM1 [tropomyosin α-1 chain]). Phosphorylation patterns on proteins related to actin cytoskeleton organization dominated the phosphoproteome of vascular smooth muscle cells derived from patients with AAA . Besides, phosphorylation changes on proteins related to energy metabolism (GYS1), contractility (PARVA [α-parvin], PPP1R12A [protein phosphatase 1 regulatory subunit 12A], and CALD1 [caldesmon 1]), and intracellular communication (GJA1 [gap junction α-1 protein]) were seen. Kinase activity of NUAK1 (NUAK family SNF1-like kinase 1), FYN (tyrosine-protein kinase Fyn), MAPK7 (mitogen-activated protein kinase 7), and STK10 (serine/threonine kinase 10) was different in vascular smooth muscle cells derived from patients with AAA compared with those from healthy, control individuals. This study revealed changes in expression and phosphorylation levels of proteins involved in various processes responsible for AAA progression and development (eg, energy metabolism, ECM remodeling, actin cytoskeleton organization, contractility, intracellular communication, and cell adhesion). These newly identified proteins, phosphosites, and related kinases provide further insight into the underlying mechanism of vascular smooth muscle cell dysfunction within the aneurysmal wall. Our omics data thereby offer the opportunity to study the relevance, either as drug target or biomarker, of these proteins in AAA development.

Morphological rationale for surgical treatment of patients with true splenic artery aneurysm

Aim. To study the morphological features of the wall structure of the splenic artery aneurysm in order to identify the safest and most effective method of surgical treatment.Materials and methods. From 2020 to 2023, 43 patients underwent surgery for true splenic artery aneurysm. Interventions involved laparoscopic clipping of aneurysm branches, laparoscopic resection of aneurysm, laparoscopic splenectomy, and resection of giant splenic artery aneurysm. A clinical and morphological study of 16 slides of splenic artery aneurysm was performed. The aneurysm wall and the adjacent wall of the splenic artery without macroscopic signs of lumen dilatation for 1 cm from the aneurysmal dilatation were examined.Results. Microscopic study revealed fragments of loose, edematous wall of large elastic arteries with atherosclerosis, atheromatosis and calcification. Atherosclerotic plaques were observed in the intima; calcium deposits were detected in 81.25% of slides, and defects in elastic fibers – in all slides. The elastic membrane was thinned or had a discontinuous structure. Morphological changes in the wall of the splenic artery persisted up to 1.0 ± 0.2 cm proximal and distal to the aneurysm.Conclusion. Taking into account the revealed features of the morphological structure of the aneurysm, the formation of an end-to-end vascular anastomosis of the splenic artery, clipping or suturing of the aneurysm neck pose a significant risk of aneurysm recurrence. Laparoscopic clipping of splenic artery aneurysm branches at a distance of >1.5 cm from the edges of the aneurysm becomes the operation of choice for patients in this category.

Nonlinear biomechanical behaviour of extracranial carotid artery aneurysms in the framework of Windkessel effect via FSI technique

Extracranial carotid artery aneurysms (ECCA) lead to rupture and neurologic symptoms from embolisation, with potentially fatal outcomes. Investigating the biomechanical behaviour of EECA with blood flow dynamics is crucial for identifying regions more susceptible to rupture. A coupled three-dimensional (3D) Windkessel-framework and hyperelastic fluid-structure interaction (FSI) analysis of ECCAs with patient-specific geometries, was developed in this paper with a particular focus on hemodynamic parameters and the arterial wall's biomechanical response. The blood flow has been modelled as non-Newtonian, pulsatile, and turbulent. The biomechanical characteristics of the aneurysm and artery are characterised employing a 5-parameter Mooney-Rivlin hyperelasticity model. The Windkessel effect is also considered to efficiently simulate pressure profile of the outlets and to capture the dynamic changes over the cardiac cycle. The study found the aneurysm carotid artery exhibited the high levels of pressure, wall shear stress (WSS), oscillatory shear index (OSI), and relative residence time (RRT) compared to the healthy one. The deformation of the arterial wall and the corresponding von Mises (VM) stress were found significantly increased in aneurysm cases, in comparison to that of no aneurysm cases, which strongly correlated with the hemodynamic characteristics of the blood flow and the geometric features of the aneurysms. This escalation would intensify the risk of aneurysm wall rupture. These findings have critical implications for enhancing treatment strategies for patients with extracranial aneurysms.

Hemodynamics study of anterior cerebral artery with different sac centerline lengths for rupture risk assessment.

The present research extensively investigates the significance of the sac centerline length of the anterior cerebral artery (ACA) on aneurysm rupture risk. Hemodynamic factors influencing aneurysm rupture are assessed to identify critical regions prone to rupture. Wall shear stress is analyzed by modeling blood flow in three real saccular ACA cases with varying sac centerline lengths. A one-way fluid-solid interaction (FSI) model is employed to examine the interaction between blood flow and vessel deformation. The computational study reveals that wall shear stress on the ACA saccular aneurysm wall is significantly higher when the sac centerline length is shorter. Conversely, the mean oscillatory index changes with different sac centerline lengths, showing that an increase in sac centerline length leads to higher blood oscillation within the sac area in ACA cases.

The Association between Plasma Proinflammatory Cytokine Concentrations and Endoleak after Endovascular Aortic Aneurysm Repair

The most common complication after endovascular aortic aneurysm repair (EVAR) is continuous sac perfusion, known as endoleak. Evaluating markers released from the aneurysm wall into circulation has been suggested as a possible alternative for detecting endoleaks. The aim of this study was to examine whether circulating concentrations of different proinflammatory interleukins (IL-1β, IL-2, IL-6, IL-8), monocyte chemoattractant protein-1 (MCP-1), and tumor necrosis factor alpha (TNF-α) were elevated in patients with endoleak after EVAR. A prospective observational study with 100 patients undergoing elective EVAR was conducted. Blood samples were taken before surgery, at 7days, 6months, and 12months after EVAR to quantify the mentioned cytokines using a Bio-Plex assay. Patients were followed up for 12months to detect endoleak occurrence. In patients with endoleak, mean concentrations of certain cytokines in plasma differed significantly from those without endoleak: preoperative IL-8 (9.83; P<0.001), preoperative MCP-1 (75.94; P=0.003), preoperative TNF-α (5.46; P=0.05), among others. A binary logistic regression analysis revealed that preoperative IL-8 (P=0.003), MCP-1 at 7days postoperative (P=0.002), and IL-1 at 12months postoperative were significantly associated with endoleak, with IL-1 being the most influential biomarker (odds ratio=2.2). A receiver operating characteristic curve showed an area under the curve of 0.7, with cutoff points of 33.4 for preoperative IL-8, 145 for MCP-1 at 7days postoperative, and 2.3 for IL-1 at 12months postoperative. This study suggests that inflammatory biomarkers such as IL-1, IL-8, MCP-1, and TNF-α have the potential to serve as important adjuncts to conventional imaging techniques in monitoring patients post-EVAR. These biomarkers may help identify individuals at higher risk of developing endoleaks, guiding more focused and timely imaging follow-up. However, their practical applicability requires further investigation.

There is poor agreement between the subjective and quantitative adjudication of aneurysm wall enhancement.

The determination of Aneurysm wall enhancement (AWE) by human readers on visual inspection alone is subjective and prone to error. A three-dimensional (3D) method for quantifying the aneurysm wall's signal intensity (SI) enables objective determination of AWE. Inter-reader agreement and agreement between subjective and objective determination of AWE were assessed in this study. Patients with saccular intracranial aneurysms (IAs) were imaged with high-resolution MRI. Subjective assessment: Two internal adjudicators visually determined AWE if the degree of enhancement was equal to or higher than the pituitary stalk. An experienced internal neuroradiologist resolved disagreements. This internal adjudication was compared with an external adjudication to assess inter-rater agreement among centers. Objective assessment: The distribution of SI across the aneurysm wall after normalizing the SI to the corpus callosum was determined with an in-house code. The normalized mean SI on post-contrast T1 MRI was defined as 3D-circumferential AWE (3D-CAWE). If the 3D-CAWE value was higher than one, an IA was defined as objectively "enhancing." Inter-rater agreement was analyzed with kappa coefficients. Inter-technique agreement between subjective and objective assessment was performed using kappa statistics. Univariate regressions were performed to identify which morphological characteristics influenced subjective adjudication of enhancement. A total of 113 IAs were analyzed. The agreement of the internal assessment was moderate (k = 0.63), 49.5% of IAs (56) were classified as "enhancing" and 50.5% (57) as "non-enhancing" after consensus. Inter-rater agreement between internal and external adjudication was weak (k = 0.52) for the presence of AWE. There was no agreement between the subjective assessment of AWE and objective 3D-CAWE (k = 0.16, p 0.02). Subjective assessment was less likely to reliably adjudicate enhancement when assessing multiple aneurysms (OR 0.4, 95% CI 0.16 -0.97, p 0.04) and IAs larger than > 7 mm (OR 0.22, 95% CI 0.09 -0.55, p 0.002) despite being objectively "non-enhancing". Subjective adjudication of AWE has poor inter-rater agreement, and no agreement with an objective 3D method of determining AWE. It is also less likely than objective quantification to identify enhancement in aneurysms larger than 7 mm or when multiple aneurysms are present. Objective 3D quantification, such as the technique used in this study, should therefore be considered when assessing AWE, especially in patients with multiple aneurysms and aneurysms larger than 7 mm in size. 3D, three-dimensional; 3D-CAWE, three-dimensional circumferential aneurysm wall enhancement; AWE, aneurysm wall enhancement; Gd, gadolinium; HR-MRI, high resolution MRI; HR 3D T1 VWI, high-resolution 3D T1 weighted black blood vessel wall imaging; IA, intracranial aneurysm; SI, signal intensity.