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CC BY-NC-ND 4.0 · Asian J Neurosurg 2025; 20(01): 061-068
DOI: 10.1055/s-0044-1791842
Original Article

Effect of the Effective Metal Surface Area of Two Different Flow Diverter Stents on the Stagnation Region Formation Inside the Aneurysm Sac

Muhammed Talha Gunaydin
1   Department of Mechanical Engineering, Faculty of Engineering, Yeditepe University, Istanbul, Türkiye
,
Gorkem Guclu
1   Department of Mechanical Engineering, Faculty of Engineering, Yeditepe University, Istanbul, Türkiye
,
Ali Bahadir Olcay
1   Department of Mechanical Engineering, Faculty of Engineering, Yeditepe University, Istanbul, Türkiye
,
Atakan Orscelik 
2   Department of Neurological Surgery, University of California, San Francisco, San Francisco, California, United States
,
Cem Bilgin
3   Department of Radiology, Mayo Clinic, Rochester, Minnesota, United States
,
Bahattin Hakyemez
4   Department of Radiology, Uludag University School of Medicine, Bursa, Türkiye
› Author Affiliations Funding This work has been supported by TUBITAK (The Scientific and Technological Research Council of Türkiye) under the 1001 Program, Project #: 117M491.
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Abstract

Objective Flow diversion (FD) is a relatively new technique for treating large, wide-necked, or fusiform aneurysms. Although FD is a more preferred option than coiling or clipping techniques in neurosurgery and neuroradiology clinics, the blood flow mechanism inside the aneurysm sac is not fully understood after the treatment. Besides, effective metal surface area (EMSA), a property of an FD related to porosity, shows variation at the patient's aneurysm neck by providing more or less blood flow inside an aneurysm sac than planned, causing nonstagnant or stagnant fluid region formation in the sac, respectively. Thus, the change in FD's EMSA can significantly affect the treatment's effectiveness, making even operation unsuccessful when variation in FD's EMSA at the aneurysm neck is overlooked.

Materials and Methods In this study, a large aneurysm of a 52-year-old female patient was numerically investigated by virtually placing two commercially available FDs with different EMSA values one by one into the aneurysm-carrying artery.

Results While FD stents at the aneurysm site substantially reduced the blood flow into the aneurysm, an FD with a 15.6% EMSA caused blood to flow in the aneurysm sac to have six times more kinetic energy than that of FD with a 29.5% EMSA.

Conclusion Although FD's EMSA value demonstrated nearly up to 20% reduction at the patient's aneurysm neck based on a product catalog value, numerical model results revealed that the stagnated region's formation inside the aneurysm sac could be determined within a 9% difference based on digital subtraction angiography reformat image.

Keywords

effective metal surface area - internal carotid artery aneurysm - flow diverter stent - patient-specific - CFD modeling

Authors' Contributions

M.T.G. was responsible for conceptualization, data curation, formal analysis, investigation, methodology, project administration, resources, visualization, and writing the original draft. G.G. contributed to conceptualization, data curation, investigation, methodology, resources, visualization, and writing the original draft. A.B.O. was involved in formal analysis, conceptualization, data curation, and writing – review and editing. A.O. contributed to conceptualization, data curation, validation, and writing – review and editing. C.B. provided resources, software, and participated in writing – review and editing. B.H. was responsible for conceptualization, investigation, methodology, supervision, validation, and writing – review and editing.


Ethical Approval

For only a single case report, ethical approval was not required by the Ethics Committee of the Faculty of Medicine, Uludag University, Bursa, Türkiye. The patient's data in this case report retained full confidentiality in compliance with the Declaration of Helsinki.




Publication History

Article published online:
21 October 2024

© 2024. Asian Congress of Neurological Surgeons. This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commercial purposes, or adapted, remixed, transformed or built upon. (https://creativecommons.org/licenses/by-nc-nd/4.0/)

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