Objective To develop a quantitative methodology for assessing the aortic media damage induced by stent-grafted by integrating mechanical experimentation, continuous damage theory, and finite element analysis, and focus on the influence of various oversizing ratios on the integrity of the aortic media. MethodsUtilizing uniaxial tensile testing datum from aortic walls of patients with TEVAR, the material parameters of aortic wall's constitutive equation, inclusive of damage parameters, were meticulously determined. A finite element model was constructed to simulate the deployment process of stent-grafted. Damage factor was delineated to scrutinize the stress distribution and the resultant damage within aortic media under a spectrum of oversizing ratios of stent-grafted. Results The damage factor exhibited a distribution congruent with that of the Von Mises stress, with both peaking at the convex aspect near the aortic arch. Additionally, stress concentration was observed in the distal anchoring region of aortic wall. An escalation in oversizing ratio was correlated with a proportional increase in both peak values. At oversizing ratios of 10%, 15%, and 20%, the Von Mises stress maxima were recorded as 469 kPa, 480 kPa, and 580 kPa, respectively, reflecting increments of 2.3% and 20.8%. Correspondingly, the damage factor maxima were 0.01, 0.011, and 0.014, marking an elevation of 10% and 27.3%. ConclusionThe findings suggest that an increment in oversizing ratio is associated with a pronounced increase in the peak value of the damage factor, indicating a more severe impact on the vascular media. The distribution of the damage factor aligns closely with that of the Von Mises stress, with both exhibiting peak values at the convex side of the aortic arch. This correlation underscores the damage factor's efficacy as a reliable indicator of the aortic media's integrity, thereby providing a robust theoretical framework for the subsequent assessment of endovascular interventional treatment risks through damage factor analysis.
Interventional embolization therapy is widely used for procedures such as targeted tumour therapy, anti-organ hyperactivity and haemostasis. During embolic agent injection, doctors need to work under X-ray irradiation environment. Moreover, embolic agent injection is largely dependent on doctors’ experience and feelings, and over-injection of embolic agent can lead to reflux, causing ectopic embolism and serious complications. As an effective way to reduce radiation exposure and improve the success rate of interventional embolization therapy, embolic agent injection robot is highly anticipated, but how to decide the injection flow velocity of embolic agent is a problem that remains to be solved. On the basis of fluid dynamics simulation and experiment, we established an arterial pressure-injection flow velocity boundary curve model that can avoid reflux, which provides a design basis for the control of embolic agent injection system. An in vitro experimental platform for injection system was built and validation experiments were conducted. The results showed that the embolic agent injection flow speed curve designed under the guidance of the critical flow speed curve model of reflux could effectively avoid the embolic agent reflux and shorten the embolic agent injection time. Exceeding the flow speed limit of the model would lead to the risk of embolization of normal blood vessels. This paper confirms the validity of designing the embolic agent injection flow speed based on the critical flow speed curve model of reflux, which can achieve rapid injection of embolic agent while avoiding reflux, and provide a basis for the design of the embolic agent injection robot.