Compliance study in both stented and unstented zones of endovascular stent-grafts incorporated with polyester and polyurethane grafts

Abstract

Event Abstract Back to Event Compliance study in both stented and unstented zones of endovascular stent-grafts incorporated with polyester and polyurethane grafts Ying Guan1*, Lu Wang1*, Jing Lin1* and Martin W. King1, 2* 1 Donghua University, Key Laboratory of Textile Science and Technology of Ministry of Education, College of Textiles, China 2 North Carolina State University, College of Textiles, United States Introduction: Stent-grafts act as the main part of EVAR, however migration and endoleaks may happen in late period of postoperative[1], which may be related to the compliance mismatch between stent-graft and host artery[2]. The introduction of a relative stiff stent-graft to a blood vessel also causes change in flow pattern. So an ideal stent-graft should be with excellent compliance. While there is few paper published in the area of stent-graft compliance, it needs study in detail. This work aimed to find out the basic features of the compliance of stent-grafts in both stented and unstented zones, meanwhile, whether the compliance of grafts make difference on the compliance of stent-graft was studied. Materials and Methods: Compliance of nitinol Z-stent supported stent-grafts were tested in the middle of stented (S3) and unstented (G3) zones respectively under the pressure range from 80 mmHg to 120 mmHg shown in Fig. 1. Those two kinds of stent-grafts were incorporated with less compliant polyester (PET) and more compliant polyurethane (PU) grafts, and named as PET-SG and PU-SG respectively. Fig. 1 Two stent-grafts and testing positions in stented (S3) and unstented (G3) zones Fig. 2 Compliance of PET-SG and PU-SG in unstented (G3) and stented (S3) zones Results: The compliance of PET-SG is 0.88 ± 0.09 %/ 100 mmHg in unstented (G3) zone, and 0.63 ± 0.19 %/ 100 mmHg in stented (S3) zone, while the compliance of PU-SG in unstented (G3) zone is 17.21 ± 0.36 %/ 100 mmHg and it turns out to be 10.06 ± 0.45 %/ 100 mmHg in stented (S3) zone (Fig. 2). Discussion: There is no significant difference of compliance between unstented and stented zones in PET-SG, however the amount of compliance in unstented zone is twice that of the stented region in PU-SG which showed significant difference (p <0.05). This indicated that the existence of stent would limit the circumferential deformation of the graft and decrease its compliance. Significant differences are found between the compliance of the PET-SG and PU-SG no matter in stented or unstented zones. The compliance of PU-SG is higher than that of PET-SG for at least 17 times in the unstented (G3) region and 9 times in the stented (S3) region. The nitinol Z-stents of those two stent-grafts, PU-SG and PET-SG, were totally the same, the difference was that PU graft was more compliant than PET graft, this made big difference on the compliance of stent-grafts. Conclusion: PET-SG showed uniform compliance along the length of the stent-graft, however non-uniformity existed in PU-SG between stented and unstented zones, and its stented region was less compliant due to the existence of stent. The compliance of a more compliant graft covered PU-SG is higher than that of less compliant graft covered PET-SG. National Natural Science Foundation of China (grant No.81371648); Fundamental Research Funds for the Central Universities (grant No. 2232015A3-02); 111 Project “Biomedical Textile Materials Science and Technology” (grant No. B07024); Chinese Universities Scientific Fund (No. CUSF-DH-D-2015007)