Studies Of The Relationship Between Arterial Vascular Disease And Morphological Feature Changes Of Vessels And Relevant Hemodynamics Mechanisms

Cardiovascular disease(CVD) is the leading cause of death globally and over 30% of death was caused by this disease each year,especially for elderly people.Moreover,atherosclerotic disease accounts for the most percentage of death caused by CVDs.Due to its high clinical incidence,the atherosclerotic disease has been investigated intensively by researchers.Endothelial dysfunction is a key factor in atherogenesis formation,moreover,the dysfunction of endothelium is usually stimulated by the complex hemodynamic forces,such as vortex flow,secondary flow,and oscillatory shear flow.In addition,complex hemodynamics environments are always appearing around the arterial bifurcations.Therefore,it is of great clinical significance to study the relationship among the morphological feature of bifurcations,the hemodynamics in vessels and atherosclerotic disease.With the development of hardware and software of the computed tomography angiography(CTA),the CTA imaging technique has been applied in the characterization,visualization,and identification of atherosclerotic disease in recent decades.Using the CTA imaging-based 3D reconstruction approach,the arterial trees can be obtained on a real scale with high precision.With this technique,many studies have investigated the structural features of vascular bifurcations between healthy individuals and patients,between juvenile and adult,male and female,etc.However,it is still unclear why morphological features change was bad to vessels or related to vascular diseases,and what morphological features change could lead to complex flow fields,and how to make full use of morphological changes to develop potential tools for early estimation of CVDs risk.In response to the above scientific questions,the medical data used to reconstruct 3D arterial bifurcations were from coronary CTA images of Southern Chinese populations(the original data were from Southern Medical University and Guangdong General Hospital).The healthy CTA images were from donated cadaver cardiovascular system(being checked with no coronary artery disease(CAD)history)and diseased CTA images were from patients with CAD lesions.In the earlier part of this article,we first measured the morphological features of the 3D bifurcations from both disease cases and healthy individuals.Then,based on the principle of minimum work in organs,we introduced Murray's law to estimate the deviation of the structure of arterial trees from their optimal and safe state.To develop a potential decision-making tool for early estimating CAD risk,we further applied the machine learning techniques(such as logistic regression(LR),decision tree(DT),linear discriminant analysis(LDA),k-nearest neighbors(k-NN),artificial neural network(ANN),and three support vector machine(SVM)models:Linear-SVM,Polynomial-SVM,and RBF-SVM))for building a model to the detection of CAD disease.In these parts,we found that the levels of coronary bifurcations with CAD lesion deviating from their optimal structure were higher than those without CAD lesion individuals,consistent with the risk of developing coronary artery disease.In addition,we demonstrated two novel morphological features((?) and AER) that were great potentially used to build machine learning classifiers for early coronary artery disease diagnosis.Meanwhile,by using the morphometric data for building the machine learning model,we further found that the Polynomial-SVM model may have great clinical application prospects in the early estimation of cardiovascular disease risk.Moreover,our present strategy of machine learning provided a stable and effective tool for detecting CAD disease.To justify the idea of the bad blood flow field in the diseased vessel that could be caused by the change of the morphological feature in the vascular bifurcations,in the subsequent sections of this article,we designed several bifurcations that were deviating their optimal state,and we further utilized the computational fluid dynamics(CFD) technique for analyzing the change of the hemodynamic characteristics in the corresponding bifurcation status.The results showed that,compared with the optimal structure,vascular bifurcations with larger angles were more likely to produce complex blood flow environments at the bifurcation sites than the bifurcations with smaller angles do.Vessels with higher asymmetry ratio and larger area expansion ratio were prone to generate low wall shear stress(WSS),high oscillatory shear index(OSI),high relative residence time(RRT)and high wall shear stress gradient(WSSG).Moreover,we systematically studied the blood flow field distribute at the atherosclerotic plaque within different stenosis rates with the changes of Reynolds number(Re).The results found that the low stenosis rate and small may be conducive to cell adhesion hence promoting further growth of atherosclerotic plaques.Moreover,results also suggested that the rupture of the atherosclerotic plaques may prone to happen at the root of the plaque and the stenosis rate of the vulnerable plaque may be generally low.Finally,we also studied the effects of the different physical factors on platelet adhesion in the human aorta.We found that when compared to steady-state flow,pulsatile flow can reduce the area of the Catch-bond region on the aorta arterial wall.Moreover,decreasing the frequency of pulsatile flow leads to a larger area of Catch-bond regions on the luminal surface.This suggested that the pulsating flow has a protective effect on the blood vessel.In addition,we found that larger body force conditions could decrease the platelet deposition rate in the human aorta arterial wall.Moreover,the higher hematocrit with higher platelet concentration in the blood flow would lead to a higher platelet deposition rate.As the formation of atherosclerotic plaque usually related to the high level of platelet deposition,therefore,the present computer strategies may be great potential in predicting the local atherosclerosis lesion.In summary,the research in this paper will help medical workers and physiologists to deeply understand the mechanism of atherosclerotic plaque formation from the perspective of morphology and hemodynamics,and it can provide new ideas for the prediction and diagnosis of vascular diseases.