| Autor: |
Parikh, Shaiv, Spronck, Bart, Debeij, Gijs, Ganizada, Berta, Ramaekers, Mitch, Schalla, Simon, Natour, Ehsan, Maessen, Jos, Delhaas, Tammo, Huberts, Wouter, Bidar, Elham, Reesink, Koen |
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| Zdroj: |
Artery Research; 2020, Vol. 26, pS28-S29, 2p |
| Abstrakt: |
Background: Dysfunctional cellular mechanosensing appears central to aneurysm formation [1]. We aimed to derive material parameters of aneurysm tissue from in vivo deformations, which may increase insight into the underlying structural integrity of the pathological tissue. Methods: Videos of tracking markers (example Video in supplement, screenshot in Figure) placed on ascending aortic segments were captured alongside radial arterial blood pressure in patients undergoing open-thorax ascending thoracic aorta aneurysm (ATAA) repair (n = 5) and coronary bypass (controls; n = 2). Normalised cross-correlation was used to determine marker displacements, resulting in estimates of systolic/diastolic diameters, distensibility, and cyclic axial engineering strain. A thinwalled, cylindrical geometry was assumed, with amorphous (Neo-Hookean) and fibrous (two-family) constitutive contributions [2]. This framework was fitted to individual patient measurements, by varying parameters c (amorphous material constant), k1 and k2 (fiber stiffness and strain stiffening parameter), β (fiber angle w.r.t. circumferential direction), unloaded intact length (L), and internal radius (Ri). Results: Axial strain tended to be lower (expected) and distensibility larger (unexpected) in aneurysm than controls (Figure). However, the intrinsic pressure-dependence of distensibility must be considered when drawing conclusions related to differences in structural stiffness between both groups [3]. Material stiffness parameters (c and k1) appeared higher in aneurysm patients than in controls which is in line with previous studies in mice [4]. Conclusion: We are developing a method to determine ATAA material properties from in vivo deformations and observed increased material stiffness in ATAA. Aneurysm Control Measured outcomes Diastolic diameter [mm] 40 ± 5 23 ± 3 DBP [mmHg] 58 ± 11 34 ± 2 SBP [mmHg] 90 ± 18 93 ± 7 Distensibility [MPa–1] 4.3 ± 3.0 3.7 ± 1.1 Axial strain [%] 4.3 ± 2.1 7.6 ± 3.5 Estimated properties c [kPa] 37 ± 29 15 ± 13 k [kPa] 43 ± 26 24 ± 24 R1 [mm] 17 ± 1 10 ± 1 β [degrees] 35 ± 3 36 ± 2 k2 – 34 ± 9 37 ± 3 L [mm] 24 ± 5 15 ± 2 [ABSTRACT FROM AUTHOR] |
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