Miltiadis Matsagkas

Background/Objectives: This study compared the hemodynamic performance of fenestrated (FEVAR), branched (BEVAR), and chimney endovascular aortic aneurysm repair (chEVAR) in patients with complex aortic aneurysms. Methods: The pre- (native) and post-endovascular repair (endograft-defined) blood lumen was reconstructed from computed tomography angiographies of nine (9) elective patients treated with FEVAR (n = 3), BEVAR (n = 3), and chEVAR (n = 3). Computational fluid dynamics (CFD) simulations obtained blood flow properties. Velocity magnitude, wall shear stress (WSS), time-averaged wall shear stress (TAWSS), oscillatory shear index (OSI), relative residence time (RRT), and local normalized helicity (LNH) were computed at peak systole and mid-diastole. The hemodynamic data were statistically analyzed to evaluate correlations between FEVAR, BEVAR, and chEVAR, focusing on targeted visceral arteries. Results: Only slight differences were observed regarding RRT, OSI, and TAWSS between FEVAR and BEVAR, whereas the chEVAR group demonstrated a marked deviation from both. In FEVAR, the postoperative helical flow structures appeared more compact, while in BEVAR they were more developed and exhibited a more rotational configuration. The LNH of the visceral vessel patterns exhibited similar qualitative features across groups. Regarding TAWSS, higher values were found in BEVAR, whereas chEVAR showed the lowest. Conclusions: FEVAR, BEVAR, and chEVAR improved postoperative blood flow characteristics toward near-physiological conditions, reducing undesired flow patterns and recirculation zones. FEVAR showed more stable visceral flow, and BEVAR demonstrated higher flow rates and fewer recirculation zones, while chEVAR exhibited more streamlined visceral artery flow with reduced regurgitation at bridging stent entries. Despite variations, all approaches effectively preserved visceral artery perfusion.

Background/Objectives: This study compared the hemodynamic performance of fenestrated (FEVAR), branched (BEVAR) and chimney endovascular aortic aneurysm repair (chEVAR) in patients with complex aortic aneurysms. Methods: The pre- (native) and post-endovascular repair (endograft-defined) blood lumen was reconstructed from computed tomography angiographies of nine (9) elective patients treated with FEVAR (n=3), BEVAR (n=3), and chEVAR (n=3). Computational Fluid Dynamics (CFD) simulations obtained blood flow properties. Velocity magnitude, wall shear stress (WSS), time-averaged wall shear stress (TAWSS), oscillatory shear index (OSI), relative residence time (RRT) and local normalized helicity (LNH) were computed at peak-systole and mid-diastole. The hemodynamic data were statistically analyzed to evaluate correlations between FEVAR, BEVAR and chEVAR, focusing on targeted visceral arteries. Results: Only slight differences were observed regarding RRT, OSI and TAWSS between FEVAR and BEVAR, whereas the chEVAR group demonstrated a marked deviation from both. In FEVAR, the postoperative helical flow structures appeared more compact, while in BEVAR, they were more developed and exhibited a more rotational configuration. The LNH of the visceral vessel patterns exhibited similar qualitative features across groups. Regarding TAWSS, higher values were found in BEVAR, whereas chEVAR showed the lowest. Conclusions: FEVAR, BEVAR, and chEVAR improved postoperative blood flow characteristics toward near-physiological conditions, reducing undesired flow patterns and recirculation zones. FEVAR showed more stable visceral flow, BEVAR demonstrated higher flow rates and fewer recirculation zones while chEVAR exhibited more streamlined visceral artery flow with reduced regurgitation at bridging stent entries. Despite variations, all approaches effectively preserved visceral artery perfusion.

Background/Objectives: This study aimed to prospectively assess the incidence of retinal embolization and to evaluate the vascular and structural changes in the retina and choroid in 52 patients with asymptomatic severe carotid artery disease who underwent carotid artery revascularization. Methods: In our study, 35 patients underwent carotid endarterectomy (CEA) and 17 underwent carotid artery stenting (CAS). Biomicroscopy, fundoscopy, optical coherence tomography (OCT), and OCT-angiography (OCTA) were performed at baseline and 1 month after revascularization. Results: The subfoveal choroidal thickness (SFCT), peripapillary choroidal thickness inferior to the optic nerve head (ppCTi), total overall average retinal vascular density (rVDtot), and total overall average choriocapillaris vascular density (ccVDtot) of the eyes ipsilateral to the operated carotid artery increased significantly after revascularization, whereas a statistically significant increase was also found in the SFCT, rVDtot, and ccVDtot of the contralateral eyes in the overall cohort. Comparing the two study groups, we found that the SFCT, superior and inferior peripapillary choroidal thicknesses (ppCTs, ppCTi), rVDtot, and ccVDtot increased in both groups after revascularization, but significantly only in the CEA group. Furthermore, the temporal choriocapillaris vascular density (ccVDt) increased significantly after revascularization in both groups to a similar degree. Conclusions: Carotid artery revascularization led to a statistically significant increase in retinal and choroidal vascular densities, which indicates significantly improved ocular perfusion. The analysis of the findings of the two study groups suggests the superiority of CEA in terms of improving ocular perfusion in asymptomatic severe carotid artery disease. The rate of retinal embolization was similar in both surgical groups.

Pathophysiological conditions in arteries, such as stenosis or aneurysms, have a great impact on blood flow dynamics enforcing the numerical study of such pathologies. Computational fluid dynamics (CFD) could provide the means for the calculation and interpretation of pressure and velocity fields, wall stresses, and important biomedical factors in such pathologies. Additionally, most of these pathological conditions are connected with geometric vessel changes. In this study, the numerical solution of the 2D flow in a branching artery and a multiscale model of 3D flow are presented utilizing CFD. In the 3D case, a multiscale approach (3D and 0D–1D) is pursued, in which a dynamically altered velocity parabolic profile is applied at the inlet of the geometry. The obtained waveforms are derived from a 0D–1D mathematical model of the entire arterial tree. The geometries of interest are patient-specific 3D reconstructed abdominal aortic aneurysms after fenestrated (FEVAR) and branched endovascular aneurysm repair (BEVAR). Critical hemodynamic parameters such as velocity, wall shear stress, time averaged wall shear stress, and local normalized helicity are presented, evaluated, and compared.

Objective: To analyze the effectiveness of prophylactic mesh augmentation (PMA) of the abdominal wall following open aortic aneurysm repair as compared to primary sutured (PS) closure in preventing incisional hernia (IH) formation by performing an individual patient-data meta-analysis (IPDMA). Background: IH is a prevalent complication after abdominal surgery, especially in high-risk groups. PMA of the abdominal wall has been studied as a preventive measure for IH formation, but strong recommendations are lacking. Methods: A systematic literature search was conducted till September 23, 2024, to identify randomized controlled trials (RCTs) that compared PMA with PS after open AAA surgery. Lead authors of eligible studies were asked to share individual patient-data. A one-stage analysis was performed, and Cox regression analyses were used to assess time-to-event outcomes. Results: Five randomized trials with a total of 493 patients were included. Intention to treat analysis revealed that PMA was associated with a significantly lower risk of IH [hazard ratio of 0.25 (95% CI: 0.12–0.50)] as compared with PS closure. Three-year incisional hernia rates were 13.2% and 39.6%, respectively, with a number needed to treat of 3.7. The effect was similar for onlay and retro-rectus PMA. PMA resulted in longer operative time (mean 27 min) and more seroma formation (especially onlay PMA) but did not increase the risk of surgical site infection. Conclusions: PMA after elective open abdominal aortic aneurysm surgery is proven to be an effective measure to reduce IH formation and should be considered in future guidelines as a standard of care.

Background: The prevalence of anticoagulant therapy-associated hemorrhagic complications in hospitalized patients with pulmonary embolism (PE) has been scarcely investigated. Aim: To evaluate the prevalence of hemorrhages in hospitalized PE patients. Methods: The Information System “ASKLIPIOS™ HOSPITAL” implemented in the Respiratory Medicine Department, University of Thessaly, was used to collect demographic, clinical and outcome data from January 2013 to April 2021. Results: 326 patients were included. Males outnumbered females. The population’s mean age was 68.7 ± 17.0 years. The majority received low molecular weight heparin (LMWH). Only 5% received direct oral anticoagulants. 15% of the population were complicated with hemorrhage, of whom 18.4% experienced a major event. Major hemorrhages were fewer than minor (29.8% vs. 70.2%, p = 0.001). Nadroparin related to 83.3% of the major events. Hematuria was the most common hemorrhagic event. 22% of patients with major events received a transfusion, and 11% were admitted to intensive care unit (ICU). The events lasted for 3 ± 2 days. No death was recorded. Conclusions: 1/5 of the patients hospitalized for PE complicated with hemorrhage without a fatal outcome. The hemorrhages were mainly minor and lasted for 3 ± 2 days. Among LMWHs, nadroparin was related to a higher percentage of hemorrhages.

Background: Our knowledge on the burden of symptomatic and asymptomatic venous thromboembolism (VTE) in patients with cancer undergoing chemotherapy is limited. The aim of our study was to prospectively investigate the frequency of symptomatic VTE and asymptomatic deep vein thrombosis of the lower limbs among cancer patients undergoing chemotherapy. Methods: We studied 231 patients (164 men) with pancreatic (N.=36), lung (N.=136), ovarian (N.=32) or prostate (N.=27) cancer receiving first line (N.=192, 83.1%) or adjuvant chemotherapy, followed-up for 3-6 months. Results: Some 17 patients were diagnosed with VTE, either asymptomatic detected on leg ultrasound (N.=7) or symptomatic (N.=10). The total frequency of VTE was 10.3% (17/165 with follow-up). Pancreatic cancer had the highest frequency of VTE (4/25, 16%) followed by ovarian (3/26, 11.5%) and lung cancer (10/94, 10.6%). There was no statistically significant difference in VTE rates among cancer types (P=0.36). VTE occurred more frequently in the presence of metastases (13/85, 15.3% vs. 4/80, 5.0%, for the remainder, P=0.03, OR 3.4). In the subgroup of patients receiving first line treatment, VTE occurred more frequently in patients with metastases (13/84, 15.5% vs. 2/53, 3.8%, for the remainder, P=0.033). In patients with pancreatic, lung or ovarian cancer receiving first line treatment, VTE occurred more frequently in patients with metastatic disease (19.1% vs. 4.0%, for the remainder, P=0.015). Conclusions: VTE occurrence in this real-world patient cohort was high, reaching almost 20% in certain groups, like those with disseminated pancreatic, lung or ovarian cancer receiving first-line chemotherapy. Furthermore, VTE occurs mostly as a symptomatic event, being likely a result of the prothrombotic state of malignancy.

On page 10, the sentence of the Discussion: "Additionally, we observed for the first time in implanted endograft a statistically significant positive correlation between AWSS and helicity intensity h2 (i.e., the highest the helicity intensity, the lower the WSS, and consequently, the higher the WSS-related risk)." Should read: "Additionally, we observed for the first time in implanted endograft a statistically significant positive correlation between AWSS and helicity intensity h2 (i.e., the higher the helicity intensity, the higher the WSS, and consequently, the lower the WSS-related risk)." There were no errors in the data reported in Table 1. None of the results or conclusions of the paper are affected by this correction.

Endovascular aneurysm repair (EVAR) has disseminated rapidly as an alternative to open surgical repair for the treatment of abdominal aortic aneurysms (AAAs), because of its reduced invasiveness, low mortality, and morbidity rate. The effectiveness of the endovascular devices used in EVAR is always at question as postoperative adverse events can lead to re-intervention or to a possible fatal scenario for the circulatory system. Motivated by the assessment of the risks related to thrombus formation, here the impact of two different commercial endovascular grafts on local hemodynamics is explored through 20 image-based computational hemodynamic models of EVAR-treated patients (N = 10 per each endograft model). Hemodynamic features, susceptible to promote thrombus formation, such as flow separation and recirculation, are quantitatively assessed and compared with the local hemodynamics established in image-based infrarenal abdominal aortic models of healthy subjects (N = 10). Moreover, the durability of endovascular devices is investigated analyzing the displacement forces (DFs) acting on them. The hemodynamic analysis is complemented by a geometrical characterization of the EVAR-induced reshaping of the infrarenal abdominal aortic vascular region. The findings of this study indicate that (1) the clinically observed propensity to thrombus formation in devices used in EVAR strategies can be explained in terms of local hemodynamics by means of image-based computational hemodynamics approach; (2) reportedly prothrombotic hemodynamic structures are strongly associated with the geometry of the aortoiliac tract postoperatively; and (3) DFs are associated with cross-sectional area of the aortoiliac tract postoperatively. In perspective, our study suggests that future clinical followup studies could include a geometric analysis of the region of the implant, monitoring shape variations that can lead to hemodynamic disturbances of clinical significance.