Cardiovascular diseases remain the main cause of death in the EU, and their treatment costs approximately EUR 282 billion, or 11% of the healthcare budget [1]. Vascular pathologies such as aortic dissection, stroke, and aneurysm are related to the rupture of the vascular wall, often with devastating consequences for patients. Predicting and preventing such ruptures requires a deep understanding of the underlying fracture mechanisms. With the aim to explore vessel wall fracture, the in-vitro symmetry-constrained Compact Tension (symconCT) test [2] acquired ground truth data for our model calibration and validation exercises. The vessel wall shows complex mechanical properties [3], and isotropic (Yeoh) as well as anisotropic (Gasser-Ogden-Holzapfel (GOH)) finite deformation descriptions of the bulk material have been explored. In addition, as viscoelasticity has a paramount implication on tissue fracture [4], a five-element Maxwell description captured the rate-dependent tissue properties. Similarly to the description of the bulk material, we explored isotropic as well as anisotropic phase field descriptions [5] in the modelling of the actual tissue failure. All our models have been realized within FEAP (Univ. of California at Berkeley, US). Phase field modelling allows to deal with most complexity of vascular tissue fracture but requires significant numerical resources. Anisotropic bulk properties of the vessel influenced the direction on the fracture propagation, and, in highly diseased human specimens from the aneurysmatic aorta, fracture was often diverted along the circumferential direction [6], an experimental observation that could only be captured by an anisotropic phase field description. REFERENCES [1] EACH: https://www.cardiovascular-alliance.eu/european-union-takes-action-for-the-cardiovascular-health-of-its-440-million-people [2] M. Alloisio, M. Chatziefraimidou, J. Roy, T.C. Gasser. Acta Biomat. 167, 147-157, 2023. [3] T.C. Gasser, Vascular biomechanics. Concepts. Models and Applications. Springer (2021) [4] C. Forsell and T.C. Gasser. J. Biomech. 44, 45-51, 2011. [5] Aldakheel F., Leibniz Universität Hannover – Habilitation: https://doi.org/10.15488/11367 (2021) [6] M. Alloisio, A. Siika, D. Freiholtz, A. Franco-Cereceda, J. Roy, H.M. Björck, T.C. Gasser. Sci. Rep. 15, 667 2025.