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To investigate the effects of clinical modalities and configurations on oxygenator pressure loss (ΔP), oxygen transfer ability and thrombosis risk and to find out the optimal oxygenator configuration. Modified partial pressure of oxygen (PO2) and a newly proposed thrombosis risk model (constructed from platelets, coagulation factors, hemostatic proteins, and blood stagnation) were used for this study. Oxygen transport and thrombosis risk assessment experiments were used for validation. Both simulation and experimental results indicate that when oxygenator operates at low flow rates with low-pressure loss and high PO2, they produced thrombin concentrations and increased thrombosis risk. For the same membrane fiber region, variations in the oxygenator external structure did not affect PO2 and thrombin production. For the ΔP and thrombosis risk, square oxygenators > round oxygenators, single-inlet oxygenators > multiple-inlet oxygenators, and lower inlet and lower outlet oxygenators > center inlet and center outlet oxygenators. The oxygenator high thrombosis risk region was identified as the blood-to-blood/border impingement region. A study of 81 oxygenator inlet and outlet combinations found that the inlet and outlet locations had little effect on ΔP and PO2. Oxygenator thrombosis risk was the lowest when using a center inlet and an upper/lower outlet configuration. The accuracy of the thrombosis risk model was validated. The oxygenator operation mode had a significant effect on ΔP, PO2, and thrombosis risk. Changes in the oxygenator external configuration had a significant impact on thrombosis. The lowest thrombosis risk was found in the center inlet and upper/lower outlet round oxygenator configuration. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the relationship between the morphological structure and hemodynamic properties of the compressed iliac vein and explore the reason for the formation of thrombosis in the compressed iliac vein. Materials and Methods: A total of 11 patients with iliac vein compression syndrome (IVCS) were included in this study, and their iliac veins were reconstructed in 3 dimensions (3D). The morphological structures of the iliac veins (confluence angle, degree of stenosis) were analyzed based on the 3D model. Variations in the hemodynamic properties of the iliac vein were investigated at 4 typical moments in one cardiac cycle, and the relationship between the different morphological configurations and the pressure difference was investigated. Results: In the region of the compressed iliac vein, the blood flow velocity is accelerated and the pressure changes abruptly accompanied by the increase in pressure difference. Higher time averaged wall shear stress (TAWSS) and lower relative residence time (RRT) appeared in stenosis regions of compressed iliac vein, while TAWSS was low and RRT was large near the stenosis position. There was a strong positive correlation between the degree of stenosis and the pressure difference (r=0.894), and a positive correlation between the confluence angle of the iliac vein and the pressure difference (r=0.638). Conclusion: The morphological structure of the compressed iliac vein has an obvious influence on the hemodynamic surroundings; the pressure difference becomes larger when the degree of stenosis and the confluence angle increase. The iliac vein luminal areas with low TAWSS and high RRT near the compressed location can impede blood flow and lead to accumulation of blood components, which may increase the risk of thrombosis formation and should be fully considered in the treatment of IVCS. [ABSTRACT FROM AUTHOR]

An abdominal aortic aneurysm (AAA) is a typical aortic disease with serious complications. In clinical practice, the decision to intervene in treatment depends on the rupture risk of AAA. Therefore, monitoring the progression of the disease and accurately assessing the rupture risk is of great importance for its treatment. Studies have shown that the biomechanical indicators based on multi-scale models are more effective in accurately assessing the rupture risk of AAA. However, using computational fluid dynamics (CFD) to simulate the biomechanical environment is a cumbersome and time-consuming process, which is inadequate to meet the needs of clinical monitoring and quick decisions. While the hemodynamic environment of AAA is heavily dependent on geometry, more and more biomechanics-related morphological parameters have been raised and validated. In this review, we summarized typical morphological parameters associated with AAA rupture and their relationships with the mechanical environment, including maximum diameter, deformation rate, saccular index, asymmetry, AAA volume, tortuosity, and intraluminal thrombus (ILT), providing a reference for clinical preoperative risk assessment. Clinical Impact: Studies have shown that the biomechanical indicators based on multi-scale models are more effective in accurately assessing the rupture risk of AAA. To meet the need for clinical monitoring and rapid decision making, the typical morphological parameters associated with AAA rupture and their relationships with the mechanical environment have been summarized, which provide a reference for clinical preoperative risk assessment of AAA. [ABSTRACT FROM AUTHOR]

Thrombotic and bleeding events are the most common hematologic complications in patients with mechanically assisted circulation and are closely related to device-induced platelet dysfunction. In this study, we sought to link computational fluid dynamics (CFD) modeling of blood pumps with device-induced platelet defects. Fresh human blood was circulated in circulatory loops with four pumps (CentriMag, HVAD, HeartMate II, and CH-VAD) operated under a total of six clinically representative conditions. Blood samples were collected and analyzed for glycoprotein (GP) IIb/IIIa activation and receptor shedding of GPIbα and GPVI. In parallel, CFD modeling was performed to characterize the blood flow in these pumps. Numerical indices of platelet defects were derived from CFD modeling incorporating previously derived power-law models under constant shear conditions. Numerical results were correlated with experimental results by regression analysis. The results suggested that a scalar shear stress of less than 75 Pa may have limited contribution to platelet damage. The platelet defect indices predicted by the CFD power-law models after excluding shear stress <75 Pa correlated excellently with experimentally measured indices. Although numerical prediction based on the power-law model cannot directly reproduce the experimental data. The power-law model has proven its effectiveness, especially for quantitative comparisons., Competing Interests: Disclosure: Z.J.W. and B.P.G. disclose financial interest in Abiomed-Breethe, Inc. and intellectual property for ECMO systems, blood pumps blood pumps, and relevant enabling technologies. Z.J.W. serves as a consultant to Daiichi Sankyo, Inc. and CH Biomedical USA, Inc. J.Z. discloses financial interest in intellectual property for ECMO systems and blood pumps. The other authors have no conflicts of interest to report., (Copyright © ASAIO 2024.)