Numerical simulation of coping strategies for the “bird-beak” phenomenon in thoracic endovascular aortic repair_Journal of Biomedical Engineering

Authors：

HE Dali ^1,2 , CHEN Shiliang ^1,2 , ZHANG Hanbing ^1,2 ,  QIAO Aike ^1,2

1. Department of Biomedical Engineering, College of Chemistry and Life Sciences, Beijing University of Technology, Beijing 100124, P. R. China;
2. Intelligent Physiological Measurement and Clinical Translation, Beijing International Base for Scientific and Technological Cooperation, Beijing 100124, P. R. China;

Corresponding?author：

QIAO Aike, Email: qak@bjut.edu.cn

Keywords：

Thoracic endovascular aortic repair; Stent-graft; Bird-beak phenomenon; Numerical simulation

DOI：

10.7507/1001-5515.202511037

Video：

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This study aims to explore the effects of different surgical strategies on the “bird-beak” phenomenon during thoracic endovascular aortic repair (TEVAR), so as to provide a theoretical basis for clinical intervention optimization. Three finite element aortic arch models with arch apex angles of 45°, 55°, and 65° were established via finite element simulation. Two stent implantation regions and three gradient stent oversizing ratios of 10%, 20%, and 30% were configured. The bird-beak angle, stent contact area, and vascular wall von Mises stress were quantitatively analyzed to compare the mechanical performance of stent implantation under different parameter combinations. Our results revealed a negative correlation between aortic arch angle and the threshold oversizing ratio required for bird-beak elimination. For 45° small angle aortic arches, 30% oversizing was necessary to resolve the bird-beak effect, whereas merely 20% oversizing sufficed for 55° and 65° larger angle arches. Nevertheless, excessive oversizing of 30% induced stent ring kinking and prolapse, reduced stent vessel apposition area, substantially elevated aortic wall stress, and raised the risk of vascular injury. Furthermore, landing zone 2 implantation was associated with a significantly higher risk of bird-beak formation compared with landing zone 3. In conclusion, stents with >20% oversizing are recommended for patients with 45° small angle aortic arches, with close attention paid to preventing stent deformation. For 55° and 65° aortic arches, 20% oversizing is sufficient to mitigate complications related to bird-beak. These findings offer theoretical support for operative planning and complication reduction in clinical TEVAR practice.

Citation： HE Dali, CHEN Shiliang, ZHANG Hanbing, QIAO Aike. Numerical simulation of coping strategies for the “bird-beak” phenomenon in thoracic endovascular aortic repair. Journal of Biomedical Engineering, 2026, 43(4): 760-768. doi: 10.7507/1001-5515.202511037 Copy

1.	周旻, 符偉國. Stanford B型主動脈夾層診斷和治療中國專家共識(2022版)[J]. 中國血管外科雜志(電子版), 2022, 14(2): 119-130.
2.	Liu J, Chen X, Xia J, et al. Comparisons of open surgical repair, thoracic endovascular aortic repair, and optimal medical therapy for acute and subacute type B aortic dissection: a systematic review and meta-analysis[J]. BMC Cardiovasc Disord, 2025, 25(1): 86.
3.	Nakajima T, Iba Y, Ogura K, et al. Partial arch replacement of type A aortic dissection after thoracic endovascular aortic repair for type B dissection[J]. Egypt Heart J, 2023, 75(1): 81.
4.	何才華. TEVAR術后Stanford B型主動脈夾層遠端破口近中期預后因素分析[D]. 貴陽: 貴州醫科大學, 2025: 24.
5.	Ullery B W, Tran K. Complications in endovascular thoracoabdominal aortic aneurysm repair[M]//Dryjski M L, Harris L M. Complications in endovascular surgery. Philadelphia: Elsevier, 2022: 117-126.
6.	Mussa F F, Kougias P. Management of acute type B aortic dissection[J]. N Engl J Med, 2025, 393(9): 895-905.
7.	Shahbazian N, Romero D A, Forbes T L, et al. Identification of geometric and mechanical factors predictive of bird-beak configuration in thoracic endovascular aortic repair using computational models of stent graft deployment[J]. JVS Vasc Sci, 2022, 3: 259-273.
8.	Shahbazian N, Romero D A, Forbes T L, et al. Prediction of bird-beak configuration in thoracic endovascular aortic repair preoperatively using patient-specific finite element simulations[J]. JVS Vasc Sci, 2023, 4: 100108.
9.	Donik ?, Li W, Nnate B, et al. A computational study of artery curvature and endograft oversize influence on seal zone behavior in endovascular aortic repair[J]. Comput Biol Med, 2024, 178: 108745.
10.	Squizzato F, Spertino A, Grego F, et al. Optimization of the proximal sealing in thoracic endovascular aortic repair (TEVAR)[J]. Vessel Plus, 2023, 7: 16.
11.	Liu Z, Teng S, Chen G, et al. A systematic approach to further improve stent-graft performance[J]. Mater Des, 2021, 211: 110144.
12.	Nagpal H, Sharma P K, Chopra J, et al. Aortic arch morphometry and its clinical implication – a computed tomography study[J]. Arch Anat Physiol. 2018; 3(1): 5-8.
13.	劉宗超. 新一代鎳鈦合金覆膜支架的設計及關鍵力學性能研究[D]. 廣州: 廣東工業大學, 2021: 38.
14.	Liu Z, Wu L, Yang J, et al. Thoracic aorta stent grafts design in terms of biomechanical investigations into flexibility[J]. Math Biosci Eng, 2021, 18(1): 800-816.
15.	Denis S, Moritz S B, Katrin M, et al. A 10-year single-center experience with the GORE TAG conformable thoracic stent graft in the treatment of thoracic aortic disease[J]. J Endovasc Ther, 2022, 29(3): 370-380.
16.	B?ckler D, Bischoff M S, Kronsteiner D, et al. Outcome analysis of the Gore conformable thoracic stent graft with active control system for the treatment of arch and descending thoracic aortic disease[J]. Eur J Cardiothorac Surg, 2021, 60(6): 1455-1463.
17.	Mao L, Luan J, Yang Y, et al. The efficacy and safety of Gore conformable thoracic stent graft and Valiant Captivia thoracic stent graft for acute type B aortic dissection[J]. Int J Cardiol, 2023, 382: 3-11.
18.	Panesar H, Simonian G, O'Connor D. GORE TAG conformable thoracic stent graft for the treatment of descending aortic pathologies[J]. Future Cardiol, 2022, 18(5): 431-441.
19.	張晗冰, 杜田明, 張艷萍, 等. 不同應力水平對支架降解影響的有限元分析[J]. 北京生物醫學工程, 2024, 43(3): 229-235, 241.
20.	孟莊源, 馬韜, 王盛章, 等. 覆膜支架治療主動脈夾層的有限元分析[J]. 醫用生物力學, 2018, 33(4): 326-331.
21.	Sherifova S, Holzapfel G A. Biomechanics of aortic wall failure with a focus on dissection and aneurysm: a review[J]. Acta Biomater, 2019, 99: 1-17.
22.	Kadry K, Olender M L, Marlevi D, et al. A platform for high-fidelity patient-specific structural modelling of atherosclerotic arteries: from intravascular imaging to three-dimensional stress distributions[J]. J R Soc Interface, 2021, 18(182): 20210436.
23.	陳文楨, 郭寶磊, 劉浩飛. 支架源性主動脈中膜力學損傷分析[J]. 醫用生物力學, 2025, 40(4): 1020-1026.
24.	Salmasi M Y, Sasidharan S, Frattolin J, et al. Regional variation in biomechanical properties of ascending thoracic aortic aneurysms[J]. Eur J Cardiothorac Surg, 2022, 62(3): ezac392.
25.	Diebels I, Hendriks J M H, Durnez J, et al. Retrograde type A aortic dissection 48 hours after TEVAR in a patient with a delayed diagnosis of vascular Ehlers-Danlos syndrome[J]. Aorta, 2022, 10(3): 141-144.
26.	Mutlu O, Mazhar N, Saribay M, et al. Finite element analysis of Evolut transcatheter heart valves: effects of aortic geometries and valve sizes on post-TAVI wall stresses and deformations[J]. J Clin Med, 2025, 14(3): 850.
27.	孫浩, 陶克怡, 劉昭, 等. 適形貼壁支架的"適形"與"可行"結構設計及其力學分析[J]. 生物醫學工程學雜志, 2024, 41(4): 790-797, 806.
28.	Khawar M, Ali U, Rasheed M A, et al. Thoracic endovascular vs open surgical repair in descending thoracic aortic aneurysms: a systematic review and meta-analysis[J]. World J Cardiol, 2025, 17(10): 110962.
29.	Upchurch G R Jr, Escobar G A, Azizzadeh A, et al. Society for Vascular Surgery clinical practice guidelines of thoracic endovascular aortic repair for descending thoracic aortic aneurysms[J]. J Vasc Surg, 2021, 73(1S): 55S-83S.
30.	Arin C B, Abdi I A, Karata? M, et al. Clinical predictors of mortality and endoleak following EVAR and TEVAR[J]. Ann Med Surg, 2025, 87(11): 7017-7020.
31.	Scurto L, Peluso N, Pascucci F, et al. Type 1A endoleak after TEVAR in the aortic arch: a review of the literature[J]. J Pers Med, 2022, 12(8): 1279.
32.	Bianchi D, Conti M, Bissacco D, et al. Impact of thoracic endovascular aortic repair on aortic biomechanics: integration of in silico and ex vivo analysis using porcine model[J]. Int J Numer Method Biomed Eng, 2023, 39(4): e3594.
33.	Zhou X B, Chen X, Wang Z, et al. Complications after treatment of type B aortic dissection with TEVAR stent-graft deployment in zone 2[J]. BMC Cardiovasc Disord, 2025, 25(1): 91.
34.	Bashir M, Jubouri M, Surkhi A O, et al. Aortic arch debranching and thoracic endovascular aortic repair (TEVAR) for type B aortic dissection[J]. Ann Vasc Surg, 2024, 99: 320-331.
35.	Frohlich M M, Suh G Y, Bondesson J, et al. Thoracic aortic geometry correlates with endograft bird-beaking severity[J]. J Vasc Surg, 2020, 72(4): 1196-1205.
36.	Zhou X, Yang F, Gong X, et al. Development of new endovascular stent-graft system for type B thoracic aortic dissection with finite element analysis and experimental verification[J]. J Mater Sci Technol, 2019, 35(11): 2682-2692.
37.	Lombardi J V, Hughes G C, Appoo J J, et al. Society for Vascular Surgery (SVS) and Society of Thoracic Surgeons (STS) reporting standards for type B aortic dissections[J]. J Vasc Surg, 2020, 71(3): 723-747.
38.	Kan X, Ma T, Lin J, et al. Patient-specific simulation of stent-graft deployment in type B aortic dissection: model development and validation[J]. Biomech Model Mechanobiol, 2021, 20(6): 2247-2258.

1. 周旻, 符偉國. Stanford B型主動脈夾層診斷和治療中國專家共識(2022版)[J]. 中國血管外科雜志(電子版), 2022, 14(2): 119-130.
2. Liu J, Chen X, Xia J, et al. Comparisons of open surgical repair, thoracic endovascular aortic repair, and optimal medical therapy for acute and subacute type B aortic dissection: a systematic review and meta-analysis[J]. BMC Cardiovasc Disord, 2025, 25(1): 86.
3. Nakajima T, Iba Y, Ogura K, et al. Partial arch replacement of type A aortic dissection after thoracic endovascular aortic repair for type B dissection[J]. Egypt Heart J, 2023, 75(1): 81.
4. 何才華. TEVAR術后Stanford B型主動脈夾層遠端破口近中期預后因素分析[D]. 貴陽: 貴州醫科大學, 2025: 24.
5. Ullery B W, Tran K. Complications in endovascular thoracoabdominal aortic aneurysm repair[M]//Dryjski M L, Harris L M. Complications in endovascular surgery. Philadelphia: Elsevier, 2022: 117-126.
6. Mussa F F, Kougias P. Management of acute type B aortic dissection[J]. N Engl J Med, 2025, 393(9): 895-905.
7. Shahbazian N, Romero D A, Forbes T L, et al. Identification of geometric and mechanical factors predictive of bird-beak configuration in thoracic endovascular aortic repair using computational models of stent graft deployment[J]. JVS Vasc Sci, 2022, 3: 259-273.
8. Shahbazian N, Romero D A, Forbes T L, et al. Prediction of bird-beak configuration in thoracic endovascular aortic repair preoperatively using patient-specific finite element simulations[J]. JVS Vasc Sci, 2023, 4: 100108.
9. Donik ?, Li W, Nnate B, et al. A computational study of artery curvature and endograft oversize influence on seal zone behavior in endovascular aortic repair[J]. Comput Biol Med, 2024, 178: 108745.
10. Squizzato F, Spertino A, Grego F, et al. Optimization of the proximal sealing in thoracic endovascular aortic repair (TEVAR)[J]. Vessel Plus, 2023, 7: 16.
11. Liu Z, Teng S, Chen G, et al. A systematic approach to further improve stent-graft performance[J]. Mater Des, 2021, 211: 110144.
12. Nagpal H, Sharma P K, Chopra J, et al. Aortic arch morphometry and its clinical implication – a computed tomography study[J]. Arch Anat Physiol. 2018; 3(1): 5-8.
13. 劉宗超. 新一代鎳鈦合金覆膜支架的設計及關鍵力學性能研究[D]. 廣州: 廣東工業大學, 2021: 38.
14. Liu Z, Wu L, Yang J, et al. Thoracic aorta stent grafts design in terms of biomechanical investigations into flexibility[J]. Math Biosci Eng, 2021, 18(1): 800-816.
15. Denis S, Moritz S B, Katrin M, et al. A 10-year single-center experience with the GORE TAG conformable thoracic stent graft in the treatment of thoracic aortic disease[J]. J Endovasc Ther, 2022, 29(3): 370-380.
16. B?ckler D, Bischoff M S, Kronsteiner D, et al. Outcome analysis of the Gore conformable thoracic stent graft with active control system for the treatment of arch and descending thoracic aortic disease[J]. Eur J Cardiothorac Surg, 2021, 60(6): 1455-1463.
17. Mao L, Luan J, Yang Y, et al. The efficacy and safety of Gore conformable thoracic stent graft and Valiant Captivia thoracic stent graft for acute type B aortic dissection[J]. Int J Cardiol, 2023, 382: 3-11.
18. Panesar H, Simonian G, O'Connor D. GORE TAG conformable thoracic stent graft for the treatment of descending aortic pathologies[J]. Future Cardiol, 2022, 18(5): 431-441.
19. 張晗冰, 杜田明, 張艷萍, 等. 不同應力水平對支架降解影響的有限元分析[J]. 北京生物醫學工程, 2024, 43(3): 229-235, 241.
20. 孟莊源, 馬韜, 王盛章, 等. 覆膜支架治療主動脈夾層的有限元分析[J]. 醫用生物力學, 2018, 33(4): 326-331.
21. Sherifova S, Holzapfel G A. Biomechanics of aortic wall failure with a focus on dissection and aneurysm: a review[J]. Acta Biomater, 2019, 99: 1-17.
22. Kadry K, Olender M L, Marlevi D, et al. A platform for high-fidelity patient-specific structural modelling of atherosclerotic arteries: from intravascular imaging to three-dimensional stress distributions[J]. J R Soc Interface, 2021, 18(182): 20210436.
23. 陳文楨, 郭寶磊, 劉浩飛. 支架源性主動脈中膜力學損傷分析[J]. 醫用生物力學, 2025, 40(4): 1020-1026.
24. Salmasi M Y, Sasidharan S, Frattolin J, et al. Regional variation in biomechanical properties of ascending thoracic aortic aneurysms[J]. Eur J Cardiothorac Surg, 2022, 62(3): ezac392.
25. Diebels I, Hendriks J M H, Durnez J, et al. Retrograde type A aortic dissection 48 hours after TEVAR in a patient with a delayed diagnosis of vascular Ehlers-Danlos syndrome[J]. Aorta, 2022, 10(3): 141-144.
26. Mutlu O, Mazhar N, Saribay M, et al. Finite element analysis of Evolut transcatheter heart valves: effects of aortic geometries and valve sizes on post-TAVI wall stresses and deformations[J]. J Clin Med, 2025, 14(3): 850.
27. 孫浩, 陶克怡, 劉昭, 等. 適形貼壁支架的"適形"與"可行"結構設計及其力學分析[J]. 生物醫學工程學雜志, 2024, 41(4): 790-797, 806.
28. Khawar M, Ali U, Rasheed M A, et al. Thoracic endovascular vs open surgical repair in descending thoracic aortic aneurysms: a systematic review and meta-analysis[J]. World J Cardiol, 2025, 17(10): 110962.
29. Upchurch G R Jr, Escobar G A, Azizzadeh A, et al. Society for Vascular Surgery clinical practice guidelines of thoracic endovascular aortic repair for descending thoracic aortic aneurysms[J]. J Vasc Surg, 2021, 73(1S): 55S-83S.
30. Arin C B, Abdi I A, Karata? M, et al. Clinical predictors of mortality and endoleak following EVAR and TEVAR[J]. Ann Med Surg, 2025, 87(11): 7017-7020.
31. Scurto L, Peluso N, Pascucci F, et al. Type 1A endoleak after TEVAR in the aortic arch: a review of the literature[J]. J Pers Med, 2022, 12(8): 1279.
32. Bianchi D, Conti M, Bissacco D, et al. Impact of thoracic endovascular aortic repair on aortic biomechanics: integration of in silico and ex vivo analysis using porcine model[J]. Int J Numer Method Biomed Eng, 2023, 39(4): e3594.
33. Zhou X B, Chen X, Wang Z, et al. Complications after treatment of type B aortic dissection with TEVAR stent-graft deployment in zone 2[J]. BMC Cardiovasc Disord, 2025, 25(1): 91.
34. Bashir M, Jubouri M, Surkhi A O, et al. Aortic arch debranching and thoracic endovascular aortic repair (TEVAR) for type B aortic dissection[J]. Ann Vasc Surg, 2024, 99: 320-331.
35. Frohlich M M, Suh G Y, Bondesson J, et al. Thoracic aortic geometry correlates with endograft bird-beaking severity[J]. J Vasc Surg, 2020, 72(4): 1196-1205.
36. Zhou X, Yang F, Gong X, et al. Development of new endovascular stent-graft system for type B thoracic aortic dissection with finite element analysis and experimental verification[J]. J Mater Sci Technol, 2019, 35(11): 2682-2692.
37. Lombardi J V, Hughes G C, Appoo J J, et al. Society for Vascular Surgery (SVS) and Society of Thoracic Surgeons (STS) reporting standards for type B aortic dissections[J]. J Vasc Surg, 2020, 71(3): 723-747.
38. Kan X, Ma T, Lin J, et al. Patient-specific simulation of stent-graft deployment in type B aortic dissection: model development and validation[J]. Biomech Model Mechanobiol, 2021, 20(6): 2247-2258.

Journal of Biomedical Engineering

Numerical simulation of coping strategies for the “bird-beak” phenomenon in thoracic endovascular aortic repair

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