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Thrombosis is a complex biological process which involves many biochemical reactions and is influenced by blood flow. Various computational models have been developed to simulate natural thrombosis in diseases such as aortic dissection (AD), and device-induced thrombosis in blood-contacting biomedical devices. While most hemodynamics-based models consider the role of low shear stress in the initiation and growth of thrombus, they often ignore the effect of thrombus breakdown induced by elevated shear stress. In this study, a new shear stress-induced thrombus breakdown function is proposed and implemented in our previously published thrombosis model. The performance of the refined model is assessed by quantitative comparison with experimental data on thrombus formation in a backward-facing step geometry, and qualitative comparison with in vivo data obtained from an AD patient. Our results show that incorporating thrombus breakdown improves accuracy in predicted thrombus volume and captures the same pattern of thrombus evolution as measured experimentally and in vivo. In the backward-facing step geometry, thrombus breakdown impedes growth over the step and downstream, allowing a stable thrombus to be reached more quickly. Moreover, the predicted thrombus volume, height and length are in better agreement with the experimental measurements compared to the original model which does not consider thrombus breakdown. In the patient-specific AD, the refined model outperforms the original model in predicting the extent and location of thrombosis. In conclusion, the effect of thrombus breakdown is not negligible and should be included in computational models of thrombosis., (© 2023. The Author(s).)

Objective: To assess trends in abdominal aortic aneurysm (AAA) hospital admissions, interventions, and aneurysm related mortality in England, and to examine the impact of endovascular repair on mortality for the years 1998 - 2020., Methods: Hospital admission and operative approach (endovascular aortic aneurysm repair, or open surgical repair [OSR]) using Hospital Episodes Statistics (HES), and aneurysm related mortality data from the Office for National Statistics for England standardised to the 2013 European Standard Population, were analysed using linear regression and Joinpoint regression analyses. Aneurysm related mortality was compared between the pre-endovascular era (1998 - 2010) and the endovascular era (2011 - 2019)., Results: A declining trend in hospital admission incidence was observed, mainly due to a decline in ruptured admissions from 34.6 per 100 000 (95% confidence interval [CI] 33.5 - 35.6) to 13.5 per 100 000 (95% CI 12.9 - 14.2; β i  = -1.04, r 2  = .97, p < .001). Operative interventions have been declining over the last 23 years mainly due to the statistically significant decline in open procedures (41.2 per 100 000 in 2000 [95% CI 40 - 42.3] to 9.6 per 100 000 [95% CI 9.1 - 10.1]; β i  = -1.92, r 2  = .95; p < .001). There was an increasing trend toward endovascular procedures (5.8 per 100 000 [95% CI 5.3 - 6.2] in 2006 to 16.9 per 100 000 [95% CI 16.2 - 17.5] in 2020; β i  = .82, r 2  = .30, p = .040). Reductions in aneurysm related mortality due to AAAs were observed for males and females, irrespective of age and rupture status., Conclusion: A significant decrease in hospital admissions for AAAs was observed over the last 23 years in England, paralleled by a shift toward endovascular repair and a decline in OSR. Declines in aneurysm related mortality were observed overall, and in the endovascular era irrespective of age, sex, and rupture status., (Copyright © 2023 The Author(s). Published by Elsevier B.V. All rights reserved.)

Background: Type B aortic dissection (TBAD) is a dangerous pathological condition with a high mortality rate. TBAD is initiated by an intimal tear that allows blood to flow between the aortic wall layers, causing them to separate. As a result, alongside the original aorta (true lumen), a false lumen (FL) develops. TBAD compromises the whole cardiovascular system, in the worst case resulting in complete aortic rupture. Clinical studies have shown that dilation and rupture of the FL are related to the failure of the FL to thrombose. Complete FL thrombosis has been found to improve the clinical outcomes of patients with chronic TBAD and is the desired outcome of any treatment. Partial FL thrombosis has been associated with late dissection-related deaths and the requirement for re-intervention, thus the level of FL thrombosis is dominant in classifying the risk of TBAD patients. Therefore, it is important to investigate and understand under which conditions complete thrombosis of the FL occurs. Method: Local FL hemodynamics play an essential role in thrombus formation and growth. In this study, we developed a simplified phenomenological model to predict FL thrombosis in TBAD under physiological flow conditions. Based on an existing shear-driven thrombosis model, a comprehensive model reduction study was performed to improve computational efficiency. The reduced model has been implemented in Ansys CFX and applied to a TBAD case following thoracic endovascular aortic repair (TEVAR) to test the model. Predicted thrombus formation based on post-TEVAR geometry at 1-month was compared to actual thrombus formation observed on a 3-year follow-up CT scan. Results: The predicted FL status is in excellent agreement with the 3-year follow-up scan, both in terms of thrombus location and total volume, thus validating the new model. The computational cost of the new model is significantly lower than the previous thrombus model, with an approximate 65% reduction in computational time. Such improvement means the new model is a significant step towards clinical applicability. Conclusion: The thrombosis model developed in this study is accurate and efficient at predicting FL thrombosis based on patient-specific data, and may assist clinicians in choosing individualized treatments in the future., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Jafarinia, Armour, Gibbs, Xu and Hochrainer.)

Objective: To assess trends in thoracic aortic aneurysm (TAA) hospital admissions, interventions, and aneurysm related mortality (ARM) in England, and examine the impact of endovascular repair on mortality for the years 1998 to 2020., Methods: Hospital admission and operative approach (thoracic endovascular aortic repair, [TEVAR] or open surgical repair) using Hospital Episodes Statistics, and ARM data from the Office for National Statistics for England standardised to the 2013 European Standard Population were analysed using linear regression and Joinpoint regression analyses. ARM was compared between the pre-endovascular era (1998 - 2008) and the endovascular era (2009 - 2019)., Results: A rising trend in hospital admission incidence has been observed, mainly due non-ruptured admissions (4.11 per 100 000 in 1998; 95% confidence interval (CI) 3.71 - 4.50 to 12.61 per 100 000 in 2020; 95% CI 12.00 - 13.21 in 2020; r 2  = .98; p < .001). Operative interventions increased mainly due to an increase in TEVAR (2.15 per 100 000; 95% CI 1.91 - 2.41 in 2020 vs. 0.26 per 100 000; 95% CI 0.16 - 0.36 in 2006; r 2  = .90; p < .001). Reductions in ARM from TAA were observed for males and females, irrespective of age and rupture status. The greatest reduction in ARM in the endovascular era was observed in females aged > 80 years with ruptured disease (15.26 deaths per 100 000 vs. 9.50 deaths per 100 000; p < .001)., Conclusion: A significant increase in hospital admissions for non-ruptured TAA has been observed in the last 23 years in England, paralleled by a shift towards endovascular repair, and significant declining trends in ARM, irrespective of sex and age. The significant reductions in age standardised death rates from ruptured and non-ruptured TAA in the endovascular era, particularly for females aged > 80 years with ruptured disease, affirm the positive impact of an endovascular approach to TAA., (Crown Copyright © 2022. Published by Elsevier B.V. All rights reserved.)

Background: We assessed trends in aortic dissection (AD) death rates in 23 countries from 2000 to 2017., Methods: We extracted AD mortality data for countries with high usability data from the World Health Organization (WHO) Mortality Database and from the Center for Disease Control (CDC) WONDER Database for the United States of America (USA). Age Standardized Death Rates (ASDRs) per 100,000 population were computed. Trends were assessed by locally weighted scatter plot smoother (LOWESS) regression., Results: Between 2000 and 2017, ASDRs from AD decreased in Australia, Belgium, Croatia, Denmark, France, Italy, New Zealand, Norway, Sweden, the United Kingdom, and the USA for both sexes. Increasing AD mortality was observed in Austria, Czech Republic, Germany, Hungary, Israel, and Japan for both sexes. The largest absolute increases in ASDR were in Japan for men (+1.59) and women (+1.11). The largest percentage decreases were in Norway for men (-0.91) and in New Zealand (-0.6) for women. In 2017, the highest mortality rates were in Japan for both sexes (3.22 and 2.09, respectively). The lowest ASDR was in Kyrgyzstan for both sexes (0.16 and 0.10, respectively). ASDRs for AD in 2017 were higher for men than women in all countries included. Spain had the greatest difference between the gender's mortality rates with a 2.71-fold higher mortality average rate in men., Conclusion: We identified an overall decrease in AD mortality in most included countries, while an increase was noted in other countries including Israel and Japan., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Purpose: To report a study that assesses the influence of the distance between the distal end of a thoracic stent-graft and the first reentry tear (SG-FRT) on the progression of false lumen (FL) thrombosis in patients who underwent thoracic endovascular aortic repair (TEVAR). Materials and Methods: Three patient-specific geometrical models were reconstructed from postoperative computed tomography scans. Two additional models were created by artificially changing the SG-FRT distance in patients 1 and 2. In all 5 models, computational fluid dynamics simulations coupled with thrombus formation modeling were performed at physiological flow conditions. Predicted FL thrombosis was compared to follow-up scans. Results: There was reduced false lumen flow and low time-averaged wall shear stress (TAWSS) in patients with large SG-FRT distances. Predicted thrombus formation and growth were consistent with follow-up scans for all patients. Reducing the SG-FRT distance by 30 mm in patient 1 increased the flow and time-averaged wall shear stress in the upper abdominal FL, reducing the thrombus volume by 9.6%. Increasing the SG-FRT distance in patient 2 resulted in faster thoracic thrombosis and increased total thrombus volume. Conclusion: The location of reentry tears can influence the progression of FL thrombosis following TEVAR. The more distal the reentry tear in the aorta the more likely it is that FL thrombosis will occur. Hence, the distal landing zone of the stent-graft should be chosen carefully to ensure a sufficient SG-FRT distance.

Objective: Identification of patients with high-risk asymptomatic carotid plaques remains an elusive but essential step in stroke prevention. Inflammation is a key process in plaque destabilization and a prelude to clinical sequelae. There are currently no clinical imaging tools to assess the inflammatory activity within plaques. This study characterized inflammation in atherosclerosis using dual-targeted microparticles of iron oxide (DT-MPIO) as a magnetic resonance imaging (MRI) probe., Methods: DT-MPIO were used to detect and characterize inflammatory markers, vascular cell adhesion molecule 1 (VCAM-1). and P-selectin on (1) tumor necrosis factor-α-treated cells by immunocytochemistry and (2) aortic root plaques of apolipoprotein-E deficient mice by in vivo MRI. Furthermore, apolipoprotein E-deficient mice with focal carotid plaques of different phenotypes were developed by means of periarterial cuff placement to allow in vivo molecular MRI using these probes. The association between biomarkers and the magnetic resonance signal in different contrast groups was assessed longitudinally in these models., Results: Immunocytochemistry confirmed specificity and efficacy of DT-MPIO to VCAM-1 and P-selectin. Using this in vivo molecular MRI strategy, we demonstrated (1) the DT-MPIO-induced magnetic resonance signal tracked with VCAM-1 (r = 0.69; P = .014), P-selectin (r = 0.65; P = .022), and macrophage content (r = 0.59; P = .045) within aortic root plaques and (2) high-risk inflamed plaques were distinguished from noninflamed plaques in the murine carotid artery within a practical clinical imaging time frame., Conclusions: These molecular MRI probes constitute a novel imaging tool for in vivo characterization of plaque vulnerability and inflammatory activity in atherosclerosis. Further development and translation into the clinical arena will facilitate more accurate risk stratification in carotid atherosclerotic disease in the future., (Copyright © 2017 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.)

Aneurysmal disease involving the origins of supra aortic vessels often requires complex open and/or endovascular repair that is not only associated with significant risk of mortality and morbidity but also often with perioperative blood loss requiring transfusion. We report a successful repair of a large thoracic aortic aneurysm (TAA) involving the aortic arch with a custom-made Bolton Relay 2-vessel branched thoracic aortic endograft in a 42-year-old Jehovah's Witness who would otherwise be very unlikely to survive an open repair. Branched thoracic aortic endografting offers a potentially safe, minimally invasive, and effective alternative for TAA disease involving the supra-aortic arteries, especially in patients who are at high risk of open surgery.

Thoracic endovascular repair (TEVAR) has recently been established as the preferred treatment option for complicated type B dissection. This procedure involves covering the primary entry tear to stimulate aortic remodelling and promote false lumen thrombosis thereby restoring true lumen flow. However, complications associated with incomplete false lumen thrombosis, such as aortic dilatation and stent graft induced new entry tears, can arise after TEVAR. This study presents the application and validation of a recently developed mathematical model for patient-specific prediction of thrombus formation and growth under physiologically realistic flow conditions. The model predicts thrombosis through the evaluation of shear rates, fluid residence time and platelet distribution, based on convection-diffusion-reaction transport equations. The model was applied to 3 type B aortic dissection patients: two TEVAR cases showing complete and incomplete false lumen thrombosis respectively, and one medically treated dissection with no signs of thrombosis. Predicted thrombus growth over time was validated against follow-up CT scans, showing good agreement with in vivo data in all cases with a maximum difference between predicted and measured false lumen reduction below 8%. Our results demonstrate that TEVAR-induced thrombus formation in type B aortic dissection can be predicted based on patient-specific anatomy and physiologically realistic boundary conditions. Our model can be used to identify anatomical or stent graft related factors that are associated with incomplete false lumen thrombosis following TEVAR, which may help clinicians develop personalised treatment plans for dissection patients in the future., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Background: There is currently no clinical imaging technique available to assess the degree of inflammation associated with atherosclerotic plaques. This study aims to develop targeted superparamagnetic particles of iron oxide (SPIO) as a magnetic resonance imaging (MRI) probe for detecting inflamed endothelial cells., Methods: The in vitro study consists of the characterisation and detection of inflammatory markers on activated endothelial cells by immunocytochemistry and MRI using biotinylated anti-P-selectin and anti-VCAM-1 (vascular cell adhesion molecule 1) antibody and streptavidin conjugated SPIO., Results: Established an in vitro cellular model of endothelial inflammation induced with TNF-α (tumor necrosis factor alpha). Inflammation of endothelial cells was confirmed with both immunocytochemistry and MRI. These results revealed both a temporal and dose dependent expression of the inflammatory markers, P-selectin and VCAM-1, on exposure to TNF-α., Conclusion: This study has demonstrated the development of an in vitro model to characterise and detect inflamed endothelial cells by immunocytochemistry and MRI. This will allow the future development of contrast agents and protocols for imaging vascular inflammation in atherosclerosis. This work may form the basis for a translational study to provide clinicians with a novel tool for the in vivo assessment of atherosclerosis.