Fen Li

Purpose: To evaluate the hemodynamic performance and clinical implications of the WeFlow-Tribranch modular endograft system using patient-specific computational fluid dynamics (CFD) analysis. Methods: Pre- and postoperative CTA data sets from 3 patients treated with the WeFlow-Tribranch system were used to reconstruct 3-dimensional aortic models. CFD simulations were performed to compare changes in blood flow patterns, branch perfusion, and wall shear stress (WSS) parameters. The analysis focused on clinical metrics including branch perfusion distribution and hemodynamic markers associated with thrombus risk (TAWSS: time-averaged wall shear stress, OSI: oscillatory shear index, and RRT: relative residence time). Results: In the 3 analyzed cases, postoperative simulations showed that the device successfully restored more organized flow patterns in the aortic arch and effectively excluded aneurysms. Perfusion to the left common carotid artery (LCCA) improved in all 3 cases (+13% to +56%). However, perfusion to the brachiocephalic trunk (BCT) and left subclavian artery (LSA) varied substantially among the cases. Furthermore, simulations identified localized regions of low TAWSS and high OSI within the reconstructed branch tunnels, indicating potential sites for flow stagnation despite improvements in the main aortic flow. Conclusion: This preliminary CFD evaluation suggests that the WeFlow-Tribranch system has the potential to restore aortic arch hemodynamics and enhance LCCA perfusion in these specific cases. However, simulations indicated that the embedded branch design may compromise flow to the BCT or LSA in certain anatomical configurations, potentially inducing localized flow disturbances. These findings underscore the importance of patient-specific preoperative planning to anticipate perfusion changes and suggest that meticulous monitoring of branch patency is warranted. To fully evaluate its long-term performance and optimize its use, further studies involving larger patient cohorts and correlation with clinical outcomes are recommended. Clinical Impact: The WeFlow-Tribranch ^™ system offers a modular, minimally invasive solution for complex aortic arch pathologies. This CFD study demonstrates that while the device restores organized aortic flow and improves LCCA perfusion, its embedded branch design introduces localized flow disturbances and patient-specific variations in BCT and LSA perfusion. For clinicians, these findings emphasize that anatomical feasibility alone is insufficient for patient selection. Meticulous pre-operative planning and rigorous post-operative surveillance of branch patency are essential to mitigate risks of thrombosis or ischemia induced by non-physiological wall shear stress.

Purpose The cross-limb (CL) technique is a commonly used endovascular treatment for addressing unfavorable anatomical features in patients with abdominal aortic aneurysm (AAA). The configuration of CL stent-graft plays a critical role in determining the postoperative hemodynamic properties and physiological behaviors, which ultimately impact the efficacy and safety of endovascular AAA treatment. This study aims to investigate the relationship between hemodynamics and CL stent-graft configuration from a hemodynamic perspective. Methods Five distinct geometric models of cross-limb (CL) stent-graft configurations were constructed by optimizing the real clinical computed tomography angiography (CTA) data. These models varied in main body lengths and cross angles and were used to perform numerical simulations to analyze various hemodynamic parameters. Flow pattern, distribution of wall shear stress (WSS)-related parameters, localized normalized helicity (LNH), pressure drop, and the displacement force of all models were examined in this paper. Results In patient-specific cases, helical flow and WSS increase with the main body. However, it also generated secondary flow in localized areas, leading to increased oscillation in the WSS direction. Notably, increasing the stent graft’s main body length or decreasing the cross angle reduced the displacement force exerted on the stent-graft. Reducing the cross angle did not significantly alter the hemodynamic characteristics. Conclusion In the clinical practice of CL deployment, it is crucial to carefully consider the stent-graft configuration and the patient specific to achieve optimal postoperative outcomes. This study provides valuable insights for guiding stent selection and treatment planning in patients with abdominal aortic aneurysm undergoing CL techniques, from a hemodynamic perspective.

Background: Moderate renal artery stenosis (50–70%) may lead to uncontrolled hypertension and eventually cause irreversible damage to renal function. However, the clinical criteria for interventional treatment are still ambiguous in this condition. This study investigated the impact of the position and degree of renal artery stenosis on hemodynamics near the renal artery to assess the short-term and long-term risks associated with this disease. Methods: Calculation models with different degrees of stenosis (50%, 60%, and 70%) located at different positions in the right renal artery were established based on the computed tomography angiography (CTA) of a personalized case. And computational fluid dynamics (CFD) was used to analyze hemodynamic surroundings near the renal artery. Results: As the degree of stenosis increases and the stenosis position is far away from the aorta, there is a decrease in renal perfusion. An analysis of the wall shear stress (WSS)-related parameters indicated areas near the renal artery (downstream of the stenosis and the entrance of the right renal artery) with potential long-term risks of thrombosis and inflammation. Conclusion: The position and degree of stenosis play a significant role in judging short-term risks associated with renal perfusion. Moreover, clinicians should consider not only short-term risks but also independent long-term risk factors, such as certain regions of 50% stenosis with adequate renal perfusion may necessitate prompt intervention.

The modular inner branched stent-graft (MIBSG), a novel interventional therapy, has demonstrated good effects in the endovascular treatment of aortic arch pathologies, especially those involving the supra-aortic branches. Nevertheless, the long-term efficacy of the MIBSG and in-depth quantitative evaluation of postoperative outcomes remain to be examined. Moreover, the regularity of postoperative vascular remodeling induced by MIBSG implantation has yet to be explored. To address these questions, we constructed four models (normal, preoperative, 1 week postoperative, and 6 months postoperative) based on a single patient case to perform computational fluid dynamics simulations. The morphological and hemodynamic characteristics, including the velocity profile, flow rate distribution, and hemodynamic parameter distribution (wall shear stress and its derivative parameters), were investigated. After MIBSG implantation, the morphology of the supra-aortic branches changed significantly, and the branch point moved forward to the proximal ascending aorta. Moreover, the curvature radius of the aortic arch axis continued to change. These changes in morphology altered the characteristics of the flow field and wall shear stress distribution. As a result, the local forces exerted on the vessel wall by the blood led to vessel remodeling. This study provides insight into the vascular remodeling process after MIBSG implantation, which occurs as a result of the interplay between vascular morphological characteristics and blood flow characteristics.