Computational Fluid Dynamics Predicting Intraprosthetic Thrombus Formation and Burden Following Endovascular Aortic Repair: A Two-Center Retrospective Study.

Significance of preoperative thrombus burden in the prediction of a persistent type II and reintervention after infrarenal endovascular aneurysm repair

The modern open surgical management of abdominal aortic aneurysm (AAA) has changed little since its inception in the 1950s. Endoaneurysmorrhaphy, first described by Rudolph Matas in 1888, involved ligating the branches of an aneurysm from within the aneurysm sac. Approximately 25 years later at the

To explore independent predictors of aortic growth in patients with type B aortic dissection (TBAD) after thoracic endovascular aortic repair (TEVAR), utilizing computational fluid dynamics (CFD) simulation. Patients who underwent TEVAR for TBAD in a single center between April 2014 and April 2023 were evaluated retrospectively. Rapid enlargement (defined as ≥5 mm/year) or aortic rupture were used to categorize patients into aortic growth and nongrowth groups. The analyzed hemodynamic parameters included wall pressure, flow velocity, flow rate, wall shear stress (WSS), time-averaged WSS, oscillatory shear index (OSI), and relative residence time. Four parallel cross-sections (L1-L4) were utilized to extract data from the hemodynamic cloud maps. Multivariate logistic regression analysis was conducted to identify independent predictors. Receiver operating characteristic (ROC) curves and the area under the curve (AUC) for these predictors were also determined. The aortic growth rate was 17.9%. A total of 51 geometric models were successfully constructed, 17 in the growth group and 34 in the nongrowth group. For morphological variables, the growth group exhibited more re-entry tears (p=0.011) and a longer patent false lumen (p=0.028), compared with the nongrowth group. For hemodynamic variables, the growth group had higher L2 pressure (p=0.040), L3 flow rate (p=0.048), and L3 OSI (p=0.020). Multivariate analysis revealed that L3 OSI (OR=7.82, 95% CI 4.122-11.33, p=0.020) and L2 pressure (OR=1.05, 95% CI 1.001-1.099, p=0.044) were independent risk factors for aortic growth. The AUC for L3 OSI and L2 pressure as predictors of aortic growth were 68.25% (95% CI 53.85-82.66) and 64.36% (95% CI 49.13-79.59), respectively. CFD simulation demonstrated that elevated pressure and increased OSI in false lumen could independently predict aortic growth following TEVAR. Monitoring these specific metrics could help identify high-risk patients immediately after stent graft implantation. However, the predictive value of these predictors was low, indicating a need for larger sample, higher-quality studies to validate these findings.Clinical ImpactThoracic endovascular aortic repair (TEVAR) is the important treatment for patients with acute type B aortic dissection (TBAD). However, aortic growth following TEVAR remains an important unresolved issue. Previous case/ cases reports found aortic growth was not solely driven by anatomical factors but influenced by hemodynamics within the false lumen. However, no further higher-quality studies supported the conclusion. In this comparative study, aortic growth and non-growth groups were divided. The computational fluid dynamics (CFD) simulation showed that elevated pressure and oscillatory shear index (OSI) in the false lumen could independently predict aortic growth after TEVAR. Our conclusions allowed vascular surgeons to make a decision on further intervention for distal aortic dissection immediately after stent graft implantation, to prevent potentially post-dissection aortic aneurysm (PDAA) and rupture in the future.

Primary aortoenteric fistula following endovascular aortic repair due to type II endoleak

Detection of Late Complications After Endovascular Abdominal Aortic Aneurysm Repair and Implications for Follow-up

Background and ObjectivesDespite the widespread use of fenestrated thoracic endovascular aortic repair (TEVAR), clinical outcomes exhibit considerable heterogeneity whose underlying hemodynamic mechanisms remain poorly understood. This study aimed to establish a patient-specific computational framework integrating postoperative computed tomography angiography (CTA) and computational fluid dynamics (CFD) to quantitatively evaluate morpho-hemodynamic alterations after fenestrated TEVAR.MethodsSix aortic dissection patients undergoing TEVAR with left subclavian artery (LSA) fenestration (three in situ, three in vitro) were included. Patient-specific 3D aortic geometries were reconstructed from postoperative CTA. High-fidelity CFD simulations were performed to analyze flow distribution, velocity, time-averaged wall shear stress (TAWSS), and oscillatory shear index (OSI).ResultsComputational analysis revealed that the brachiocephalic trunk was the least affected vessel following TEVAR (median ARBT 0.80, IQR 0.74–0.89). Notable abnormalities included one case of severe LSA stenosis (ARLSA = 5.25, VLSA, systole = 1.15 m/s), and one instance of mild stent-induced proximal LCCA compromise (ARLCCA = 1.27, VLCCA, systole = 1.06 m/s), both demonstrating TAWSS elevation at affected segments. Additionally, one patient exhibited inadequate endovascular recovery in the descending aorta, which received only 42.83% of the total cardiac output. The remaining patients showed no significant hemodynamic abnormalities.ConclusionThis pilot study establishes a patient-specific computational framework that integrates CTA with CFD to decipher post-intervention morpho-hemodynamic alterations. By quantitatively linking stent-induced geometric changes to adverse hemodynamic phenotypes, the demonstrated methodology explores a mechanistic approach for understanding post-surgical outcome disparities, thereby establishing a computational tool for postoperative evaluation. The clinical utility and predictive value of this tool, however, await validation in larger, prospective cohorts.

Urgent endovascular repair for ruptured aortic aneurysm using computed tomography image fusion

Purpose: Lifelong follow-up after endovascular abdominal aortic aneurysm repair (EVAR) is recommended due to a continued risk of complications, especially if the first postoperative imaging shows abnormal findings. We studied the long-term outcomes in patients with abnormalities on the first postoperative computed tomography angiography (CTA) following EVAR. Materials and Methods: This is a retrospective study of all consecutive patients who underwent elective EVAR for nonruptured abdominal aortic aneurysm (AAA) between January 2007 and January 2012 in 16 Dutch hospitals with follow-up until December 2018. Patients were included if the first postoperative CTA showed one of the following abnormal findings: endoleak type I–IV, endograft kinking, infection, or limb occlusion. AAA diameter, complications, and secondary interventions during follow-up were registered. Primary endpoint was overall survival, and other endpoints were secondary interventions and intervention-free survival. Kaplan-Meier analyses were used to estimate overall and intervention-free survival. Cox regression analyses were used to identify the association of independent determinants with survival and secondary interventions. Results: A total of 502 patients had abnormal findings on the first postoperative CTA after EVAR and had a median follow-up (interquartile range IQR) of 83.0 months (59.0). The estimated overall survival rate at 1, 5, and 10 years was 84.7%, 51.0%, and 30.8%, respectively. Age [hazard ratio (HR) 1.06, 95% confidence interval (CI) 1.05 to 1.10] and American Society of Anesthesiologists (ASA) classification (ASA IV HR 3.20, 95% CI 1.99 to 5.15) were significantly associated with all-cause mortality. Overall, 167 of the 502 patients (33.3%) underwent 238 secondary interventions in total. Fifty-eight patients (12%) underwent an intervention based on a finding on the first postoperative CTA. Overall survival was 38.4% for patients with secondary interventions and 44.5% for patients without (log rank; p=0.166). The intervention-free survival rate at 1, 5, and 10 years was 82.9%, 61.3%, and 45.6%, respectively. Conclusions: Patients with abnormalities on the first postoperative CTA after elective EVAR for infrarenal AAA cannot be discharged from regular imaging follow-up due to a high risk of secondary interventions. Patients who had a secondary intervention had similar overall survival as those without secondary interventions.

Objective: The aim of the present study is to investigate the potential morphological and hemodynamic risk factors related to intracranial aneurysms (IAs) rupture and establish a system to stratify the risk of IAs rupture to help the clinical decision-making.Methods: Patients admitted to our hospital for single-IAs were selected from January 2012 and January 2018. A propensity score matching was conducted to match patients. The morphological parameters were obtained from high solution CTA images, and the hemodynamic parameters were obtained in accordance with the outcomes of computational fluid dynamics (CFDs) simulation. Differences in the morphologic and hemodynamic parameters were compared. The significant parameters were selected to establish a novel scoring system (Intracranial Aneurysm Rupture Score, IARS). The comparison was drawn between the discriminating accuracy of IARS and the Rupture Resemblance Score (RRS) system to verify the value of IARS. Then, a group of patients with unruptured IAs was stratified into the high risk and low risk groups by IARS and RRS system separately and was followed up for 18–27 months to verify the value of IARS. The outcome of different stratifications was compared.Results: The matching process yielded 167 patients in each group. Differences of statistical significance were found in aneurysm length (p = 0.001), perpendicular height (H) (p < 0.001), aspect ratio (AR) (p < 0.001), size ratio (SR) (p < 0.001), deviated angle (DA) (p < 0.001), normalized average wall shear stress (NWSSa) (p < 0.001), wall shear stress gradient (WSSG) (p < 0.001), low shear area ratio (LSAR) (p = 0.01), and oscillatory shear index (OSI) (p = 0.01). Logistic regression analysis further demonstrated that SR, DA, NWSSa, LSAR, and OSI were the independent risk factors of IAs rupture. SR, DA, LSAR, and OSI were finally selected to establish the IARS. Our present IARS showed a higher discriminating value (AUC 0.81 vs. 0.77) in comparison with the RRS (SR, NWSSa, and OSI). After follow-up, seven patients were subject to IAs rupture. 5/26 in high risk group stratified by IARS, yet 7/57 in high risk group stratified by RRS. The accuracy of IARS was further verified (19.2% vs. 12.3%, AUC for the IARS and the RRS was 0.723 and 0.673, respectively).Conclusion: SR, DA, NWSSa, LSAR, and OSI were considered the independent risk factors of IAs rupture. Our novel IARS showed higher accuracy in discriminating IA rupture in comparison with RRS.

Invited commentary

The association between perioperative embolization of hypogastric arteries and type II endoleaks after endovascular aortic aneurysm repair

Risk factors for the rupture of mirror middle cerebral artery aneurysm using computer-assisted semiautomated measurement and hemodynamic analysis

Ascending aortic volume: A feasible indicator for ascending aortic aneurysm elective surgery?

Introduction: Surveillance for endoleak after endovascular aortic aneurysm repair with computed tomography angiography has the associated risks of radiation exposure and nephrotoxic contrast agents. The purpose of this study was to evaluate the performance of contrast-enhanced ultrasound in the detection of endoleak post–endovascular aortic aneurysm repair. Methods: A single-center retrospective cohort study was performed evaluating patients with abdominal aortic aneurysm treated with endovascular aortic aneurysm repair between October 29, 2017 and April 21, 2021 and follow-up imaging with both computed tomography angiography and contrast-enhanced ultrasound. The sample included 35 imaging combinations in 28 patients. Positive and negative results for detection of endoleak by contrast-enhanced ultrasound were tabulated as true positive, false positive, true negative, and false negative compared to computed tomography angiography and conventional angiography. Sensitivity, specificity, positive predictive value, and negative predictive value of contrast-enhanced ultrasound were calculated. Results: Out of 35 imaging combinations, endoleak was detected in 24 cases by computed tomography angiography and in 23 cases by contrast-enhanced ultrasound. Using computed tomography angiography as the reference standard, contrast-enhanced ultrasound yielded 96% sensitivity, 100% specificity, 100% positive predictive value, and 92% negative predictive value for endoleak detection. In the 23 cases of endoleak detection by both contrast-enhanced ultrasound and computed tomography angiography, contrast-enhanced ultrasound discerned the correct endoleak type in all 23 cases, while computed tomography angiography identified the correct endoleak type in 20 cases ( P = .2333). Discussion: Endoleak detection by contrast-enhanced ultrasound appears at least equivalent to computed tomography angiography. Some of the advantages of contrast-enhanced ultrasound in the surveillance of endoleak after endovascular aortic aneurysm repair include an avoidance of radiation, elimination of nephrotoxic contrast agents, reduction in costs, real-time imaging, discerning flow directionality, and visualizing endoleaks in regions previously embolized with coils/plugs/liquid embolic agents. Limitations include operator dependence and variables that obscure the visual field including obese body habitus. With these advantages and excellent comparison data, contrast-enhanced ultrasound should be considered as a first-line imaging modality for long-term surveillance of endoleaks after endovascular aortic aneurysm repair. Conclusion: Contrast-enhanced ultrasound is a safe and viable option for long-term surveillance post–endovascular aortic aneurysm repair.

To determine the incidence and risk factors of renal dysfunction after abdominal endovascular aortic repair (EVAR) and thoracic endovascular aortic repair (TEVAR). The study consisted of 227 patients treated with EVAR and 90 with TEVAR for aortic aneurysms. Parameters, including patients' background factors, preoperative renal function, contrast dose and aortic wall irregularity on CT images were assessed in relation to postoperative renal dysfunction. Deterioration of renal function was observed in 33 of 218 patients (15.1%) after EVAR and in 7 of 79 (8.9%) patients after TEVAR. Hemodialysis was required in one patient after EVAR. In EVAR, renal dysfunction correlated with age (p=0.034) and occlusion of accessory renal artery (p=0.0001). In TEVAR, renal dysfunction correlated with age (p=0.021), contrast dose (p=0.042) and irregularity of the descending aortic wall (p=0.023). In a multiple regression analysis, postoperative renal dysfunction was correlated with occlusion of accessory renal artery (p=0.0003) after EVAR, and age (p=0.02), contrast dose (p=0.026) and irregularity of the descending aortic wall (p=0.042) after TEVAR. Occlusion of accessory renal artery in EVAR, and age, contrast dose and irregularity of the descending aortic wall in TEVAR were considered to be predictors of postoperative renal dysfunction.