Customized stent‐grafts for endovascular aneurysm repair with challenging necks: A numerical proof of concept

Abstract

Endovascular aortic repair (EVAR) is a challenging intervention whose longterm success strongly depends on the appropriate stent-graft (SG) selection and sizing. Most off-the-shelf SGs are straight and cylindrical. Especially in challenging vessel morphologies, the morphology of off-the-shelf SGs is not able to meet the patient-specific demands. Advanced manufacturing technologies facilitate the development of highly customized SGs. Customized SGs that have the same morphology as the luminal vessel surface could considerably improve the quality of the EVAR outcome with reduced likelihoods of EVAR related complications such as endoleaks type I and SG migration. In this contribution, we use an in silico EVAR methodology that approximates the deployed state of the elastically deformable SG in a hyperelastic, anisotropic vessel. The in silico EVAR results of off-the-shelf SGs and customized SGs are compared qualitatively and quantitatively in terms of mechanical and geometrical parameters such as stent stresses, contact tractions, SG fixation forces and the SG-vessel attachment. In a numerical proof of concept, eight different vessel morphologies, such as a conical vessel, a barrel shaped vessel and a curved vessel, are used to demonstrate the added value of customized SGs compared to off-the-shelf SGs. The numerical investigation has shown large benefits of the highly customized SGs compared to off-the-shelf SGs with respect to a better SG-vessel attachment and a considerable increase in SG fixation forces of up to 50% which indicate decreased likelihoods of EVAR related complications. Hence, this numerical proof of concept motivates further research and development of highly customized SGs for the use in challenging vessel morphologies. K E Y W O R D Sabdominal aortic aneurysm, customized stent-graft, endovascular repair, personalized medicine

A computational program for automated surgical planning of fenestrated endovascular repair

“…Moreover, recent literature has highlighted advances in using computational tools to aid the design of EVAR devices deployed in virtual models. Hemmler et al 19 developed an in-silico model of customized stent grafts that have the same morphology as the underlying luminal vessel surface for improved EVAR implantation with reduced likelihood of postoperative complications such as endoleaks and graft migration. While these studies seek to gain a better understanding of the mechanics of graft deployment that determine post-operative shape, none are implemented as a device-specific, automated design tool for minimizing trial and error graft planning.…”

Patient-Specific Numerical Simulations of Endovascular Procedures in Complex Aortic Pathologies: Review and Clinical Perspectives

“…Therefore, such structures can behave mechanically like an SG or aortic wall. In the cardiovascular area, this numerical simulation has the potential to predict trans-catheter implantable device deployment, such as aortic valves and aortic SG [14,[23][24][25][26][27][28].…”

Patient‐specific computational modeling of endovascular aneurysm repair: State of the art and future directions

“…After the SG deployment (removal of displacement constraints), both SG and aorta are treated as elastically deformable bodies subjected to stationary, physiologically meaningful, blood pressure states. The applicability of the direct placement method was demonstrated with patient‐specific cases, 44,48 SG and AAA parameter studies 45 as well as SG customization 46 …”

“…Hemmler et al 46 performed an in silico study comparing off‐the‐shelf SGs and customized SGs qualitatively and quantitatively in terms of mechanical and geometrical parameters such as stent stresses, contact tractions, and fixation forces. The numerical investigation has shown large benefits of the highly customized SGs compared to off‐the‐shelf SGs.…”

“…Comparison of the gap between aorta (gray) and SG (rainbow color scale) in the deployed state for the two SG cases. Figure reproduced with permission from Hemmler et al 46 …”