The Establishment Of Chinese Anisotropic Hyperelastic Coronary Model And Coupling Analysis

Coronary arteries supply blood to heart, which pla y a very important role innorma l phys ica l activities. Therefore ma ny efforts have been put, aiming toexpla in and model the mecha nis ms that govern the m in both healthy andpatho logical cases, s ince the1960s as the beginning of b iomecha nics. In2000, anew model of arteria l wall was introduced by G.A. Holzapfe l, which based on thereal properties of coronary vessel, anisotropic, nonlinear, superelastic orpseudoelastic ity and is co mposed by three-layer structures. T.C. Gasser and R.W.Ogden did a further improvement to this constitutive equation. After that, anearly perfect model o f arteria l wall was achieved, recognized as―HGO‖model.In this paper, we established the HGO model for coronary arteries by finiteeleme nt method and ana lyzed the mechanica l properties of coronaries. The ma inpurpose of this paper is to obtain the mechanica l response and str ess distributionof Chinese coronary arteries after stent expans ion, and provide reference forcoronary interventio nal procedures.For the d ifferences of coronary mechanical strength between Chinese andWesterners, a reasonable assumption was proposed that the changing scopes ofthe two parameters,C10andk1, would not go out of an order of magnitude.Based on that, we did the unia xia l tens ile simulation, which found that the resultof parameter set a2was much c lose to the experimenta l result of proxima lsegment o f RCA of Chinese. In view of the importance of residua l stress andstra in in improving vascular stress leve l, we explored the distribution ofanisotropic hyperelastic vascular resid ual stress and strain under different va luesof materia l parameters and opening angles. The research of resid ual strain madeit c lear of its distributio n characteristics in the blood vessels, and also confirmedthe correctness of the assumptions about the range of materia l pa rameters, on theother hand, it laid a solid foundation for the establishment of the―HGO‖modelconta ined resid ual strain. F ina lly, we comp leted the whole coronary-stentcoup ling model that conta ined residua l strain under different material parameters,got various stresses along different directions with stent expans ion and the trendequation of stress–expansion with high goodness of fit by rationa l fraction fitting.The research on resid ual stra in made us a better understanding o f materia lparameters and opening angles. By the simulatio n, we recognized the importanceand necessity of residua l strain that improving the leve l of stress of arteria l wallsin phys iolo gical optimizations.The stress–expans ion trend equation proposed did have a great benefit tointerventiona l procedures, by whic h the stress increase caused by stent expansioncould be accurately expressed in numerical form. Substituting the vascularultimate stress obtained through experime nts into trend equation, the specificsize of stent expans ion can be drawn. It will be a valuable reference for theinterventiona l procedures, us ing the equatio n to get the feasible s ize of stentexpansion for the preoperative preparation. Combined with the patient’s ownphys iologica l cond itions, we can avo id too large expans ion leading to arteria lpenetration, in a certain extent.