Aneurysm Growth Research Articles

A Novel Combined Microsurgical and Endovascular Approach for Type II Endoleak Embolization Through Direct Puncture of a Lumbar Segmental Artery: A Technical Case Instruction

BACKGROUND AND IMPORTANCE: Despite the advances in endovascular aortic repair techniques, type II endoleaks with aneurysm sac expansion remain frequent and challenging problems. CLINICAL PRESENTATION: An elderly gentleman underwent a combined microsurgical and endovascular procedure to address a type 2 endoleak and the growth of a recurrent abdominal aortic aneurysm caused by direct puncture of a lumbar segmental artery. The patient tolerated the procedure well and was discharged without complications. Follow-up imaging revealed no further endoleak and a smaller aneurysm size. CONCLUSION: This unique case presents a novel multidisciplinary surgical strategy for treating complex, recurrent aortic aneurysms with type II endoleaks. The approach is tailored to the individual patient and has shown effectiveness. Long-term follow-up data will be crucial for assessing the efficacy and durability of this approach.

Modeling and Visual Simulation of Bifurcation Aneurysms Using Smoothed Particle Hydrodynamics and Murray’s Law

Aneurysm modeling and simulation play an important role in many specialist areas in the field of medicine such as surgical education and training, clinical diagnosis and prediction, and treatment planning. Despite the considerable effort invested in developing computational fluid dynamics so far, visual simulation of blood flow dynamics in aneurysms, especially the under-explored aspect of bifurcation aneurysms, remains a challenging issue. To alleviate the situation, this study introduces a novel Smoothed Particle Hydrodynamics (SPH)-based method to model and visually simulate blood flow, bifurcation progression, and fluid–structure interaction. Firstly, this research consider blood in a vessel as a kind of incompressible fluid and model its flow dynamics using SPH; and secondly, to simulate bifurcation aneurysms at different progression stages including formation, growth, and rupture, this research models fluid particles by using aneurysm growth mechanism simulation in combination with vascular geometry simulation. The geometry incorporates an adjustable bifurcation structure based on Murray’s Law, and considers the interaction between blood flow, tissue fluid, and arterial wall resistance. Finally, this research discretizes the computation of wall shear stress using SPH and visualizes it in a novel particle-based representation. To examine the feasibility and validity of the proposed method, this research designed a series of numerical experiments and validation scenarios under varying test conditions and parameters. The experimental results based on numerical simulations demonstrate the effectiveness and efficiency of proposed method in modeling and simulating bifurcation aneurysm formation and growth. In addition, the results also indicate the feasibility of the proposed wall shear stress simulation and visualization scheme, which enriches the means of blood analysis.

Linear growth pattern can be used to predict ascending aortic aneurysm growth

Objectives. Current guidelines recommend that surveillance imaging should be performed at least every third year for patients with ascending thoracic aortic aneurysm (ATAA) even though such aneurysms’ growth rate is mostly minimal. The purpose of this study was to clarify the pattern of the growth of ATAAs in a real-life patient population to adjust the optimal timing of aortic surveillance for each patient. Methods. This study includes patients (n = 209) who had been followed due to ATAA in the central hospital of North Karelia in Eastern Finland between years 2007 and 2023. Aortic imaging was performed using either computed tomography (CT) or transthoracic echocardiography (TTE). In the CT images, the aortic dimensions were measured according to guidelines in four levels of the ascending aorta. TTE measurements were collected from medical records. Measurements were used to explore the pattern of the ATAA growth. Results. During the mean surveillance time 5.0 ± 3.5 years, the median growth rate of ATAAs was 0.37 mm/year. One fifth (21.5%) of the aneurysms showed no expansion during the follow-up. Despite the minimal growth rate during surveillance, some patients ended up exceeding the cut-off for preventive surgery. Among the patients, who showed expansion during the follow-up, the linear model seemed to best describe the growth of ATAA. Conclusions. The majority of the patients had a very low ATAA growth rate. Based on this study, the growth of ATAAs could be described using a linear model, which could, in turn, be used to predict the growth of an aneurysm.

Abstract 4117345: Predicting Downstream Aneurysmal Degeneration Following Type A Dissection Repair With Computational Fluid Dynamics

Introduction: Acute type A aortic dissection (ATAAD) is typically treated by replacement of the ascending aorta (+/- root) and proximal arch. However, 70-85% of patients have residual distal dissection post-repair, and 20-40% require late reoperation for aneurysmal degeneration of the distal aorta (ADDA). Since an individual patient’s risk of ADDA cannot be accurately predicted, current guidelines recommend lifelong aortic surveillance imaging for all patients. Hypothesis: Computational fluid dynamics (CFD) simulations of aortic hemodynamics post-repair can accurately identify patients at late risk of ADDA. Methods: We performed CFD simulations of 50 patients following hemi-arch replacement for ATAAD. Patient-specific 3D models were generated from the aortic root to iliac bifurcation (including arch branches) from postoperative 0.6mm contrast-enhanced CT angiograms taken <1 year after index repair (Figure). Exclusion criteria were known heritable thoracic aortic disease and absence of residual dissection. The primary outcome was ADDA, defined as late growth of the distal arch/descending thoracic aorta (DTA) to a diameter ≥5.5cm. Hemodynamic simulations were run for 6 cardiac cycles on a high-performance computing cluster using HARVEY, a CFD solver implementing the lattice Boltzmann method. The primary hemodynamic metric was time-averaged wall shear stress (TAWSS) ratio between the false and true lumens. Results: ADDA developed in 22 patients (44%) at a mean of 3.2 years postoperatively. There were no significant clinical differences between those with and without ADDA (Table). The development of late aneurysm growth was significantly associated with a higher TAWSS ratio in the proximal DTA ( p <0.05, Figure). Conclusion: ADDA following hemi-arch repair for ATAAD is associated with significantly higher false lumen TAWSS as early as the first surveillance scan. CFD simulations may help clinicians risk-stratify patients years before they meet reoperation criteria.

Long noncoding RNA Sngh20 promotes vascular smooth muscle cell senescence and abdominal aortic aneurysm growth by interacting with dead-box helicase 5

Abstract Background Development of non-surgical treatment of human abdominal aortic aneurysm (AAA) has clinical significance. Long noncoding RNAs (lncRNAs) are emerging as powerful mediators participated in cellular senescence process that a critical pathological alteration prompting AAA development. Purpose To investigate the role and underlying mechanism of lncRNA Small nucleolar RNA host gene-20 (Snhg20) in AAA formation. Methods Experimental AAA mice models were produced by peri-aortic CaPO4 injury in C57bl/6J mice or Subcutaneousangiotensin-II (Ang-II) infusion in Apoe–/– mice and gapmeR was used to knockdown Snhg20 expression. Adeno-associated virus and anti-IL-6 monoclonal antibody was used to knockdown dead-box helicase 5 (DDX5) and neutralize IL-6, respectively.Immunohistochemical and immunofluorescent staining, ELISA and real-time PCR were performed to determine the vascular structure and inflammation, cellular senescence and senescence-associated secretory phenotype (SASP) content in human and mouse AAA lesions. Human aortic SMC cell line was used to investigate the effect of Snhg20 knockdown on senescence and SASP in vitro. LncRNA pulldown and mass spectrometry were used to identify potential targets that interact with Snhg20. p53 DNA binding affinity was examined by EMSA. Results The expression of Snhg20 was downregulated in both human and mice AAA lesion. Snhg20 knockdown promoted SMC senescence and loss, vascular inflammation and AAA growth in both experimental AAA mice models. Mechanistically, Snhg20 interacted with DDX5, an important transcriptional coactivator of p53. The absence of snhg20 increased DDX5 and p53 interaction and thereby promoted p53 DNA binding affinity to transcriptionally initiate p21expression, resulting in increased cellular senescence and senescence-associated secretory phenotype (SASP) secretion, including IL-6. Moreover, DDX5 silencing or anti-IL-6 therapy rescued the SMC senescence and loss, vascular inflammation and AAA growth mediated by Snhg20 knockdown. Furthermore, human AAA lesions showed increased DDX5 co-localization with p53 and abundant senescent vascular SMC. Conclusion These findings identify an important role of Snhg20 in controlling vascular SMC senescence and SPAP expression and suggest that Snhg20 is a potential target for AAA treatment aimed at reducing VSMCs senescence.Schematic summary

The value of systemic immune inflammation index, white blood cell to platelet ratio, and homocysteine in predicting the instability of small saccular intracranial aneurysms

Inflammation has a destructive effect on the homeostasis of the vascular wall, which is involved in the formation, growth, and rupture of human intracranial aneurysms (IAs) disease progression. However, inflammation-related markers have not been well studied in the risk stratification of unruptured IAs. The purpose of this study was to investigate the predictive value of serum inflammatory markers in the unstable progression of small saccular intracranial aneurysms (SIAs). This study retrospectively included 275 patients with small SIAs (aneurysm diameter less than or equal to 7 mm), to compare the level difference of serum inflammatory complex marker systemic immune-inflammatory index (SII), white blood cell to platelet ratio (WPR), and homocysteine (Hcy) in patients with stable (asymptomatic unruptured) and unstable (symptomatic unruptured, ruptured) small SIAs. 187 patients (68%) had aneurysm-related compression symptoms and rupture outcomes. In the multivariate logistic regression after adjusting for baseline differences, SII, WPR, and Hcy were independent risk factors for the instability of small SIAs, the prediction model combined with other risk factors (previous stroke history, aneurysm irregularity) showed good predictive ability for the instability of small SIAs, with an area under the curve of 0.905. In addition, correlation analysis showed that SII, WPR, and Hcy also had significant differences in patients with symptomatic unruptured and ruptured small SIAs, and higher inflammation levels often promoted the disease progression of small SIAs. Higher levels of SII, WPR and Hcy can be used as independent predictors of instability of small SIAs. As an economical and convenient biomarker, it is crucial for clinical treatment strategies of stable small SIAs.

A Review of Hemodynamic Parameters in Cerebral Aneurysm

Abstract—A cerebral aneurysm is a localized dilation that weakens the wall of a blood vessel in the brain. This condition comes in the form of abnormal widening, ballooning or in the form of a bleb. Gaining an understanding of the initiation, growth, and rupture of cerebral aneurysm has played a critical role in finding treatments that prevent the possibility of mortality and morbidity. Cerebral aneurysm develops as a result of the thinning of artery wall, and it is often difficult to diagnose prior to its rupture that leads to several fatal diseases, including brain damage, hemorrhagic stroke, behavioral inconsistency, and eye movement disturbance. A computational fluid dynamic study of cerebral aneurysm employs blood flow simulation wherein hemodynamic parameters indicate the rupture status of a vessel. These hemodynamic parameters actually trigger the biological factors of blood flow in the brain vessels with aneurysm. This paper offers a review of these hemodynamic parameters, and it elucidates the correlation of these parameters with cerebral aneurysm. Specifically, this review highlights the hemodynamic parameters that are related to the formation, growth, and morphological features, namely, size and shape, of cerebral aneurysm Keywords—Cerebral aneurysm, Hemodynamics, Wall shear stress, rupture risk, ansys

Baseline Diameter Does Not Predict Growth Rate in a Presurgical Ascending Thoracic Aortic Aneurysm Population.

Patients with ascending thoracic aortic aneurysm are recommended to undergo routine imaging surveillance. Although maximal diameter is the primary metric of disease severity, recent American College of Cardiology/American Heart Association guidelines emphasize the importance of aortic growth in determining surgical candidacy and risk. As diameter increases, it is assumed that aortic growth rate accelerates because of increased wall tension; however, this relationship is poorly studied. We aim to investigate the relationship between ascending thoracic aortic aneurysm diameter and growth rate using vascular deformation mapping, a validated technique for 3-dimensional growth mapping with submillimeter accuracy. We retrospectively identified adult patients with ascending aortic dilation (≥4.0 cm) and serial gated computed tomography angiograms separated by ≥2 years, excluding confirmed heritable thoracic aortic disease. Ascending growth rate was defined as 90th percentile radial wall deformation by vascular deformation mapping. Maximal diameter measurements were derived from the baseline computed tomography angiogram, and aortic length and body size-adjusted indexes were calculated. Among 258 included patients (63.2% men; age of 63 years [interquartile range, 55-69 years]), mean±SD baseline diameter was 46.3±3.6 mm and median growth rate was 0.21 mm/year (interquartile range, 0.13-0.38 mm/year). No correlation was noted between growth rate and baseline diameter (r=0.02, P=0.74) or other aortic size metrics. On multivariate analysis, age was independently predictive of growth rate (β=-0.007, P=0.021), alongside weight (β=0.003, P=0.016) and the presence of moderate or severe aortic valve insufficiency (β=0.146, P=0.049). Maximal aortic diameter is not predictive of aortic growth rate, in this contemporary cohort of patients with sizes under current surgical thresholds (<55 mm).

Women Experience Higher Rates of Mortality Following Thoracic Endovascular Aneurysm Repair

ObjectivesThoracic endovascular aortic repair (TEVAR) and complex endovascular thoraco-abdominal aneurysm repair (cEVAR) has been increasingly adopted in the treatment of thoracic and thoracoabdominal aorta aneurysms, offering a less invasive approach for patients with appropriate anatomy. Women usually present with smaller aortic diameter. However, they usually have greater aneurysm growth rates. How sex can affect postoperative and short-term outcomes after TEVAR is not well reported. The aim of this study was to assess outcomes in female versus male patients undergoing TEVAR for treatment of thoracic and thoracoabdominal aneurysms in a Medicare-linked database. MethodsWe retrospectively reviewed patients undergoing TEVAR for thoracic and thoracoabdominal aneurysm repair in the Vascular Quality Initiative (VQI) Vascular Implant Surveillance and Interventional Outcomes Network (VISION) database from 2003 to 2018. Patients were divided into males and females. Patients presented with ruptured aneurysm were excluded from the analysis. Postoperative outcomes included in-hospital stroke, myocardial infarction (MI), spinal cord ischemia, and 30-day mortality. One-year outcomes included mortality, aneurysmal rupture, and reintervention. Postoperative outcomes were assessed using multivariable logistic regression analysis and one-year outcomes were evaluated using Kaplan Meier Survival and Cox regression analyses. ResultsA total of 3,058 males and 1,843 females were available for the analysis. Female patients had smaller median aortic diameter, were more likely to be black, with chronic obstructive pulmonary disease, and chronic kidney disease, and to be symptomatic on presentation. Male patients were more likely to be on preoperative medications such as aspirin, beta-blockers, angiotensin-converting enzyme inhibitors, P2Y12 antagonists, and anticoagulants. After adjusting for potential confounders, female gender was associated with double the risk of in-hospital stroke (OR: 2.3, 95%CI ((1.5-3.7), P<0.001) and 80% increase in 30-day mortality (OR: 1.8, 95%CI (1.3-2.6), P=0.001). At one year, female gender was associated with a higher risk of mortality (HR: 1.2, 95%CI (1.05-1.4), P=0.011). There was a trend towards higher risk of reintervention (HR: 1.2, 95%CI (0.97-1.6), P=0.079). ConclusionsMortality after TEVAR seems to be higher in female patients at 30 days and up to one year of follow-up. Female patients also face a two times higher risk of in-hospital stroke. Future studies with a larger female population should aim to identify and potentially ameliorate the factors associated with these unfavorable outcomes in females.

Design and Characterisation of a Novel Z-Shaped Inductor-Based Wireless Implantable Sensor for Surveillance of Abdominal Aortic Aneurysm Post-Endovascular Repair.

An abdominal aortic aneurysm (AAA) is a dilation of the aorta over its normal diameter (> 3 cm). The minimally invasive treatment adopted uses a stent graft to be deployed into the aneurysm by a catheter to flow blood through it. However, this approach demands frequent monitoring using imaging modalities that involve radiation and contrast agents. Moreover, the multiple follow-ups are expensive, time-consuming, and resource-demanding for healthcare systems. This study proposes a novel wireless implantable medical sensor (WIMS) to measure the aneurysm growth after the endovascular repair. The proposed sensor is composed of a Z-shaped inductor, similar to a stent ring. The proposed design of the sensor is explored by investigating the inductance, resistance, and quality factor of different possible geometries related to a Z-shaped configuration, such as the height and number of struts. The study is conducted through a combination of numerical simulations and experimental tests, with the assessment being carried out at a frequency of 13.56 MHz. The results show that a higher number of struts result in higher values of inductance and resistance. On the other hand, the increase in the number of struts decreases the quality factor of the Z-shaped inductor due to the presence of high resistance from the inductor. Moreover, it is observed that the influence of the number of struts present in the Z-shaped inductor tends to decrease for larger radii. The numerical and experimental evaluation concludes the ability of the proposed sensor to measure the size of the aneurysm.

Targeted plasma multi-omics propose glutathione, glycine and serine as biomarkers for abdominal aortic aneurysm growth on serial CT scanning

Background and aimsAbdominal aortic aneurysm (AAA) patients undergo uniform imaging surveillance until reaching the surgical threshold. In spite of the ongoing exploration of AAA pathophysiology, biomarkers for personalized surveillance are lacking. This study aims to identify potential circulating biomarkers for AAA growth on serial CT scans. MethodsPatients with an AAA (maximal diameter ≥40 mm) were included in this multicentre, prospective cohort study. Participants underwent baseline blood sampling and yearly CT-imaging to determine AAA diameter and volume. Proteins and metabolites were measured using proximity extension assay (Olink Cardiovascular III) or separate ELISA panels, and mass-spectrometry (LC-TQMS), respectively. Linear mixed-effects, orthogonal partial least squares, and Cox regression were used to explore biomarker associations with AAA volume growth rate and the risk of surpassing the surgical threshold, as formulated by current guidelines. Results271 biomarkers (95 proteins, 176 metabolites) were measured in 109 (90.8 % male) patients with mean age 72. Median baseline maximal AAA diameter was 47.8 mm, volume 109 mL. Mean annual AAA volume growth rate was 11.5 %, 95 % confidence interval (CI) (10.4, 12.7). Median follow-up time was 23.2 months, 49 patients reached the surgical threshold. Patients with one standard deviation (SD) higher glutathione and glycine levels at baseline had an AAA volume growth rate that respectively was 1.97 %, 95%CI (0.97, 2.97) and 1.74 %, 95%CI (0.78, 2.71) larger, relative to the actual aneurysm size. Serine was associated with the risk of reaching the surgical threshold, independent of age and baseline AAA size (cause-specific hazard ratio per SD difference 1.78, 95%CI (1.30, 2.44)). ConclusionsAmong multiple intertwined biomarkers related to AAA pathophysiology and progression, glutathione, glycine and serine were most promising.

Effects of paroxetine, a P2X4 inhibitor, on cerebral aneurysm growth and recanalization after coil embolization: the NHO Drug for Aneurysm Study.

Rupture of cerebral aneurysms has a poor prognosis, and growing aneurysms are prone to rupture. Although the number of coil embolization procedures is increasing worldwide, they are more prone to recurrence than clipping surgeries. However, there is still no drug that prevents aneurysm growth or recanalization after coil embolization. The authors have previously focused on the role of hemodynamics in cerebral aneurysm development and reported that inhibition of the P2X4 purinoceptor, by which vascular endothelial cells sense blood flow, reduced the induction and growth of aneurysms in an animal model. In this study, the authors investigated the effects of paroxetine, a P2X4 inhibitor also used as an antidepressant, on aneurysm growth and recanalization after endovascular coiling. Using the J-ASPECT Study registry, the largest comprehensive reimbursement database system for acute stroke inpatient care in Japan, the authors searched for patients incidentally taking paroxetine who were registered in the decade 2010-2019 with an unruptured cerebral aneurysm or who underwent aneurysm coiling. They calculated the growth incidence and growth rate by the person-year method and the odds ratio for recanalization within 1 year after coiling and statistically compared to controls. Seventy-eight stroke facilities participated, and 275 patients were identified as potentially eligible. Thirty-seven patients with unruptured aneurysms and 38 after coil embolization met all eligibility criteria. They were compared with 396 control cases of unruptured aneurysms and 308 coil-placement controls. Multivariate analysis showed that paroxetine significantly reduced the incidence of aneurysm growth (number of cases with growth/person/year; incidence rate ratio [IRR] 0.24, 95% CI 0.05-0.66; p = 0.003) and the growth rate (total increase in maximum diameter in millimeters/person/year; IRR 0.57, 95% CI 0.28-0.98; p = 0.04). Paroxetine also significantly reduced the odds of recanalization in the year after coiling (OR 0.21, 95% CI 0.05-0.95; p = 0.04). The authors then performed propensity score matching to reduce bias due to imbalances in patient characteristics between the two groups; the outcome confirmed that paroxetine significantly reduced aneurysm growth incidence (IRR 0.02, 95% CI 0.008-0.05; p < 0.0001) and growth rate (IRR 0.03, 95% CI 0.01-0.06; p < 0.0001) and the 1-year recanalization (OR 0.18, 95% CI 0.03-0.99; p = 0.04). This observational cohort study suggests that P2X4 inhibitors such as paroxetine may be clinically applicable as prophylaxis against aneurysm rupture and postoperative recanalization.

Assessing the impact of fetal-type posterior cerebral artery variations on cerebral hemodynamics

The circle of Willis (CoW) is a critical, arterial structure that ensures balanced, cerebral-blood supply. The fetal-type posterior cerebral artery (f-PCA) is a CoW variant that can significantly affect hemodynamics and elevate the risk of cerebrovascular diseases. This study used computational fluid dynamics simulations and a patient-specific, three-dimensional model to evaluate the hemodynamic effects of the f-PCA variants on cerebral-blood flow and key hemodynamic indices—such as time-averaged wall-shear stress (TAWSS), oscillatory shear index (OSI), pulsatility index, and resistive index. The fetal ratio (FR) is defined as the ratio of the diameter of the posterior communicating artery (PCoA) to that of the first segment (P1) of the PCA. Our findings indicate that as the FR increases, the contribution of the basilar artery to the second segment (P2) of PCA decreases significantly. Specifically, the flow rate through ipsilateral P1 decreased by 40.0% for FR = 1 and 70.9% for FR = 2, with the internal carotid artery (ICA) compensating for this reduction. Moreover, variations in f-PCA led to significant increases in TAWSS and OSI in key arterial segments (including the ipsilateral P1, PCoA, and the anterior communicating artery), which are associated with a higher risk of aneurysm initiation and growth. Under conditions of unilateral stenosis in the ipsilateral ICA, f-PCA models exhibit a more complex and pronounced impact on blood flow than models without f-PCA, emphasizing the need for detailed hemodynamic assessments in clinical evaluations and preoperative planning to mitigate the risks associated with CoW anatomical variations.

Rate of Ascending Aortic Enlargement in a Large Echocardiographic Cohort: Associated Risk Factors and Adverse Aortic Events

Understanding ascending aortic aneurysm growth and associated risk factors is critical to advising appropriate echocardiographic follow-up intervals for patients. This study aimed to identify aortic aneurysm growth rate on serial echocardiograms as well as the clinical and demographic variables that contribute to baseline aortic size and subsequent aortic growth. Patients identified with ascending aortic aneurysm and undergoing serial echocardiograms within five years were evaluated. Ascending aortic size was measured as part of routine echocardiogram exams. Clinical and demographic variables including aortic valve type (trileaflet, bicuspid or prosthetic) were evaluated for association with baseline aortic size as well as with aortic progression rate. Clinical events including aortic dissection, elective or emergent surgical repair were recorded. 3639 patients were identified, (78% males, median age of 69 years, 175 (4.8%) with bicuspid valve, and 206 (5.6%) with prior aortic valve replacement (AVR). Patients with larger aorta at baseline were older with higher tobacco use and prior prosthetic valves. Over a mean of 2.4 years, aortic growth was observed and differed by valve type (trileaflet valve: 0.08 mm/year , bicuspid valve: 0.4 mm/year , p<0.001). In six patients who developed aortic dissection the estimated average annual growth rate was 0.98 mm/year. In a large echo cohort, aortic aneurysm growth rate was 0.08 mm/year though higher in those with bicuspid valves ( 0.4 mm/ year), but initial aortic size did not correlate with change in the aortic progression rate. This data may help inform recommended echocardiographic surveillance intervals.

Assessing abdominal aortic aneurysm growth using radiomic features of perivascular adipose tissue after endovascular repair

ObjectivesThe study aimed to investigate the relationship between the radiomic features of perivascular adipose tissue (PVAT) and abdominal aortic aneurysm (AAA) growth after endovascular aneurysm repair (EVAR).MethodsPatients with sub-renal AAA who underwent regular follow-up after EVAR between March 2014 and March 2024 were retrospectively collected. Two radiologists segmented aneurysms and PVAT. Patients were categorised into growing and non-growing groups based on volumetric changes observed in two follow-up computed tomography examinations. One hundred seven radiomic features were automatically extracted from the PVAT region. Univariable and multivariable logistic regression was performed to analyse radiomic features and clinical characteristics. Furthermore, the performance of the integrated clinico-radiological model was compared with models using only radiomic features or clinical characteristics separately.ResultsA total of 79 patients (68 ± 9 years, 89% men) were enroled in this study, 19 of whom had a growing aneurysm. Compared to the non-growing group, PVAT of growing AAA showed a higher surface area to volume ratio (non-growing vs growing, 0.63 vs 0.70, p = 0.04), and a trend of low dependence and high dispersion manifested by texture features (p < 0.05). The area under the curve of the integrated clinico-radiological model was 0.78 (95% confidence intervals 0.65–0.91), with a specificity of 87%. The integrated model outperformed models using only radiomic or clinical features separately (0.78 vs 0.69 vs 0.69).ConclusionsHigher surface area to volume ratio and more heterogeneous texture presentation of PVAT were associated with aneurysm dilation after EVAR. Radiomic features of PVAT have the potential to predict AAA progression.Clinical relevance statementRadiomic features of PVAT are associated with AAA progression and can be an independent risk factor for aneurysm dilatation to assist clinicians in postoperative patient surveillance and management.Key PointsAfter EVAR for AAA, patients require monitoring for progression.PVAT surrounding growing AAA after EVAR exhibits a more heterogeneous texture.Integrating PVAT-related features and clinical features results in better predictive performance.Graphical

Sex Differences in Intracranial Aneurysms: A Matched Cohort Study.

Background: Aneurysmal subarachnoid hemorrhage (SAH) predominantly affects women, accounting for 65% of cases. Women have a 1.3 times higher relative risk than men, with the incidence rising particularly in women aged 55-85 years. Women also have a higher prevalence of unruptured intracranial aneurysms (IAs), especially after the age of 50 years, and are at greater risk of aneurysm growth and rupture. This study aimed to isolate the influence of sex on rupture rate, bleeding severity, functional outcomes, and complications by using a matched cohort, while also examining the impact of sex on aneurysm localization and multiplicity. Methods: We utilized a retrospectively collected database of 300 patients with 511 IAs. Inclusion criteria included the availability of clinical data and 3D angiography for semi-automatic reconstruction of IA morphology. Female patients and their IA were matched with male patients according to clinical parameters and 21 morphological characteristics using an interactive visual exploration tool for multidimensional matching. Results: Contrary to previously published results, our study found no significant sex differences in rupture rates or vasospasm rates between male and female patients. The severity of SAH, functional outcomes, and complications such as hydrocephalus were also similar in women and men. However, women exhibited a higher prevalence of multiple aneurysms and distinct localization patterns. Conclusions: This study underscores the complex role of sex in IA development and rupture. Although sex-specific biological factors influence aneurysm characteristics, they do not necessarily translate into differences in clinical outcomes. Further research is needed to explore these factors and their impact on aneurysm development and management.

Fluid-Structure Interaction Simulations of the Initiation Process of Cerebral Aneurysms.

Background: Hemodynamics during the growth process of cerebral aneurysms are incompletely understood. We developed a novel fluid-structure interaction analysis method for the identification of relevant scenarios of aneurysm onset. Method: This method integrates both fluid dynamics and structural mechanics, as well as their mutual interaction, for a comprehensive analysis. Patients with a single unruptured cerebral aneurysm were included. Results: Overall, three scenarios were identified. In scenario A, wall shear stress (WSS) was low, and the oscillatory shear index (OSI) was high in large areas within the region of aneurysm onset (RAO). In scenario B, the quantities indicated a reversed behavior, where WSS was high and OSI was low. In the last scenario C, a behavior in-between was found, with scenarios A and B coexisting simultaneously in the RAO. Structural mechanics demonstrated a similar but independent trend. Further, we analyzed the change in hemodynamics between the onset and a fully developed aneurysm. While scenarios A and C remained unchanged during aneurysm growth, 47% of aneurysms in scenario B changed into scenario A and 20% into scenario C. Conclusions: In conclusion, these findings suggest that WSS and the OSI are reciprocally regulated, and both low and high WSS/OSI conditions can lead to aneurysm onset.

Impact of blood viscosity on hemodynamics of large intracranial aneurysms

BackgroundHemodynamic factors play an important role in the formation and rupture of intracranial aneurysms. Blood viscosity has been recognized as a potential factor influencing the hemodynamics of aneurysms. Computational fluid dynamics (CFD) is one of the main methods to study aneurysm hemodynamics. However, current CFD studies often set the viscosity to a standard value, neglecting the effect of individualized viscosity on hemodynamics. We investigate the impact of blood viscosity on hemodynamics in large intracranial aneurysm (IA) and assess the potential implications for aneurysm growth and rupture risk. MethodsCFD simulations of 8 unruptured large internal carotid artery aneurysms were conducted using pulsatile inlet conditions. For each aneurysm, CFD simulations were performed at 5 different viscosity levels (0.004, 0.006, 0.008, 0.010, and 0.012 Pa·s). Differences in hemodynamic parameters across viscosity levels were compared using paired t-tests, and the correlation between viscosity and hemodynamic parameters was analyzed. ResultsIncreasing blood viscosity leads to significant decrease in blood flow velocity within aneurysms. Time-averaged wall shear stress (WSS) showed significant positive correlation with viscosity, particularly at the aneurysm neck. Oscillatory shear index (OSI) showed general decreasing trend with increased viscosity, while it displayed an irregular pattern in a few cases. ConclusionsVariations in viscosity markedly influence velocity, WSS, and OSI in aneurysms, suggesting a role in modulating aneurysm growth and rupture risk. Incorporating patient-specific viscosity values in CFD simulations is vital for accurate and reliable outcomes.

Does it stable? Intracranial aneurysm wall enhancement might be the warning signals: a meta-analysis of observational studies.

Magnetic resonance vessel wall imaging (MR-VWI) is an emerging imaging technology used to assess the progressive risk of unruptured intracranial aneurysms (UIAs). Unlike the standard evaluation model, MR-VWI is still debatable. This study aims to further define the potential relationship between aneurysm wall enhancement (AWE) and aneurysm stability. Using "intracranial aneurysm", "magnetic resonance", and "enhancement" as keywords, relevant studies were systematically searched in PubMed, Embase, and Cochrane, and the qualified studies were enrolled for further analysis. There were 13 case-control studies, 4 cohort studies, and 2,678 cases of intracranial aneurysms included in the meta-analysis. It was shown that AWE was correlated with intracranial aneurysm rupture (OR = 35.90, 95% CI: 15.58 to 82.75, p < 0.001), growth (OR = 6.69, 95% CI: 2.69 to 16.63, p < 0.001), and presence of symptoms (OR = 14.46, 95% CI: 9.07 to 23.05, p < 0.001). This finding had a high diagnostic value, but the correlation was probably not independent of aneurysm size. The pooled relative risks of the follow-up studies revealed that the risk of UIA progression was approximately 3.33 times higher with AWE than without AWE (RR = 3.33, 95% CI: 2.33 to 4.78, p < 0.001). In addition, the pooled results demonstrated that quantitative indices of VWI enhancement were equally linked with aneurysm stability (OR = 19.61, 95% CI: 10.63 to 36.17, p < 0.001). AWE is an effective imaging method to assess the stability of UIAs, and it can be a marker for the prophylactic treatment of small unruptured intracranial aneurysms in the future, which remains to be validated by prospective studies with large samples.

Metformin Improves the Function of Abdominal Aortic Aneurysm Patient-Derived Aortic Smooth Muscle Cells

Type 2 diabetes mellitus (T2DM) is a cardiovascular risk factor. Paradoxically, a decreased risk of abdominal aortic aneurysm (AAA) presence and growth rate is described among patients with T2DM, associated with metformin use. This study aimed to investigate the effect of metformin on AAA patient derived aortic smooth muscle cell (SMC) function. Aortic biopsies were obtained from patients with AAA (n = 21) and controls (n = 17) during surgery. The SMCs of non-pathological aortic controls, non-diabetic patients with AAA, and diabetic patients with AAA were cultured from explants and treated with or without metformin. The SMC contractility was measured upon ionomycin stimulation, as well as metabolic activity, proliferation, and migration. Then, mRNA and protein expression of markers for contraction, metabolic activity, proliferation, and inflammation were measured. The mRNA expression of KLF4 and GYS1, genes involved in metabolic activity, differed between the SMCs from non-diabetic and diabetic patients with AAA before metformin stimulation (p < .041). However, the effect of metformin on the various SMC functions was similar between non-diabetic and diabetic patients with AAA. Upon stimulation, metformin increased the contractility of AAA patient SMCs (p = .001). The mRNA expression of smoothelin, a marker for the contractile phenotype, increased in the SMCs of patients with AAA after treatment with metformin (p = .006). An increase in metabolic activity (p < .001) and a decrease in proliferation (p < .001) and migration were found in the SMCs of controls and patients with AAA with metformin. Increased mRNA expression of PPARγ, a nuclear receptor involved in mitochondrial biogenesis (p < .009), and a decrease in gene expression of Ki-67, a marker for proliferation (p < .005), were observed. Gene expression of inflammation markers MCP-1 and IL-6, and protein expression of NF-κB p65 decreased after treatment with metformin in patients with AAA. This study found that metformin increases contractility and metabolic activity, and reduces proliferation, migration, and inflammation in aortic SMCs in vitro.