The Clinical And Pathological Study On The Non-Invasive Arterial Elasticity

BackgroundCardiovascular disease resulting from arteriosclerosis is a serious worldwide health risk. With the deepening investigation of atherosclerosis, people have realized that functional and structural changes in the artery wall precede and accompany atherosclerosis and its obstructive and thrombotic events. Earlier diagnosis and intervention in vascular disease is important to control the adverse cardiovascular events such as acute myocardial infarction, stroke, and cardiac death.Elasticity is an important characteristic of the arteries and a direct reflection of the condition of these blood vessels, and reduced arterial elasticity is a sensitive marker that indicates damage to the blood vessel wall. It has been reported that capacitive arterial compliance (Cl) and oscillatory arterial compliance (C2) can accurately reflect arterial elasticity. It has also been noted that the compliance of small arteries, defined as the change in volume per unit of pressure (?V/?P) and which reflects the buffering function of the vessel, is lower in postmenopausal women with symptomatic coronary artery disease than in those without coronary artery disease. Small artery compliance also reflects subtle vascular alterations due to aging, hypertension, and type 1 diabetes, and is gender dependent-female subjects have been observed to have lower small artery compliance than male subjects. It has been shown that lower small artery compliance is associated with diffuse-coronary heart disease (CHD). Small artery compliance appears, therefore, to be a useful tool for the clinical screening of individuals of CHD. Few studies, however, have investigated the changes in small artery compliance in people with angiographic coronary atherosclerosis prior to CHD.ObjectivesThis study was designed to investigate whether small artery compliance and large artery compliance were reduced in people with angiographic coronary atherosclerosis before they were diagnosed with CHD, and to search for the relationships between non-invasive arterial elasticity indexes and the Gensini score of coronary artery.Methods(1) Two study populations were observed in this study:elderly subjects(?65years of age) and non-elderly subjects (<65years of age).Each of the two study populations included 160 consecutive subjects who were divided into three groups according to the results of selective coronary angiography:50 subjects in the normal coronary angiogram group,55 subjects in the coronary atherosclerosis group and 55 subjects in the CHD group.(2) All patients were administered a standardized questionnaire that provided information about their occupation, age, medical history, drug using, and smoking history. Blood pressure and heart rate were measured and body mass index (BMI) was calculated. Levels of total cholesterol (TC), triglyceride (TG) and fasting blood glucose (FBG) were measured from fasting venous blood samples by automatic facilities.(3) The Gensini score of the coronary artery was acquired, and the capacitive arterial compliance (C1) and oscillatory arterial compliance (C2) were measured.(4) One-way ANOVA was used to evaluate the difference of C1 and C2 between the three groups. Bivariate analyses were performed to study the association between the Gensini score and each of C1 and C2.Results(1) One-way ANOVA analysis demonstrated a significant difference in C2 among the three groups:the normal coronary angiogram group, the coronary atherosclerosis group and the CHD group, but there was no significant difference in C1.(2) Bivariate analysis showed a negative correlation between the Gensini score and C2 in the 55 subjects of the coronary atherosclerosis group and in the 55 subjects of the CHD group. There was no significant correlation between Gensini score and C1.Conclusions(1) It can be concluded that C2 decreased in the early stages of the coronary artery atherosclerosis in patients when there were no significant stenoses in the coronary arteries independent of elderly populations or non-elderly populations.(2) Independent of elderly populations or non-elderly populations, C2 was significantly, negatively correlated with Gensine score of the coronary artery.(3) Identification of early coronary atherosclerosis may be aided by the prognostic value of C2. BackgroundWith the deepening investigation of atherosclerosis, people have realized that functional and structural changes in the artery wall precede and accompany atherosclerosis and its obstructive and thrombotic events. It has also been noted that elasticity, defined as the change in volume per unit of pressure(?V/?P), is an important characteristic of the arteries and a direct reflection of the condition of these blood vessels, and that reduced arterial elasticity is a sensitive marker that indicates damage to the blood vessel wall. So the analysis of arterial stiffness and function and of pressure wave reflection has received increasing attention for the past a few decades.A variety of techniques developed in recent years provide quantification of these pathophysiologic changes in the arterial wall. Among the methods to describe arterial stiffness, pulse wave velocity (PWV) and diastolic pulse contour analysis (DPCA) have been the most investigated in a clinical setting. It has been reported that carotid-femoral PWV (CFPWV), capacitive arterial compliance (C1), and oscillatory arterial compliance (C2) can accurately reflect arterial elasticity. Almost all conventional risk factors for atherosclerosis such as hypercholesterolemia, hypertension, diabetes, insulin resistance, smoking, and aging are associated with PWV, C1, or C2.It has been demonstrated that PWV, C1, and C2 are significant predictors of cardiovascular risk in diseased and older healthy populations.The human aorta contains vascular smooth muscle, and is rich in elastin and collagen. A delicate balance of collagen, elastin, and smooth muscle in the aortic wall is clearly essential for a compliant aorta. Thus, we postulate there must be a close relationship between CFPWV, C1, C2 and composition of the human aorta. However, the correlation between arterial elastic indices mentioned above and smooth muscle, elastin, or collagen of the aortic media has not previously been examined in human.ObjectivesThis study was designed first to investigate the influence of hypertension on the arterial elasticity and the histologic structure of the ascending aortic media in patients with coronary heart disease (CHD) undergoing coronary artery bypass graft (CABG) surgery. The second purpose of this study was to examine the relationship between structural changes of the ascending aortic media and the arterial elastic indices such as CFPWV, Cl, and C2.Methods(1) The study population comprised 60 consecutive CHD patients who underwent CABG surgery in Qilu Hospital of Shandong University and were divided into two groups:30 subjects were in the hypertension group and 30 subjects were in the non-hypertension group.(2) All patients were administered a standardized questionnaire that provided information about their occupation, age, medical history, drug using, and smoking history. Blood pressure and heart rate were measured and body mass index (BMI) was calculated. Levels of total cholesterol (TC), triglyceride (TG) and fasting blood glucose (FBG) were measured from fasting venous blood samples by automatic facilities.(3) CFPWV, C1, and C2 were measured in a quiet, temperature controlled room. (4) Selective coronary angiography was performed according to standard clinical practice and quantitative coronary angiographic analyses were performed using the computer-based edge-detection coronary angiography analysis system. Then Gensini score was calculated.(5) The specimens of ascending aorta were stained with Masson and Weigert's solution separately and examined by light microscopy to measure the percentage of medial surface occupied by smooth muscle, collagen, and elastic fibers by pathologists in a double-blinded manner.(6) All data analyses were performed using the program SPSS11.5 for Windows. Continuous variables were expressed as the means�SD. Categorical data were presented as numbers and percentages. An independent-sample t-test was used to compare continuous data and the X2 test was used to compare categorical variables between the two groups. Bivariate analyses were performed to study the associations between microstructure of the ascending aortic media and each of CFPWV, C1 and C2. A P-value of< 0.05 was considered to be statistically significant.Results(1) There were significant differences between the two groups in CFPWV and C1, but no differences between the two groups in C2.(2) There was a significant decrease in the relative content of elastin and a significant increase in the relative content of collagen in the media of ascending aorta of the hypertension group compared with those of the non-hypertension group. There was no significant difference between the two groups in smooth muscle content of the ascending aorta.(3) CFPWV had positive correlation with the relative contents of collagen and negative correlation with the relative contents of elastin in each of the two groups.(4) C1 had negative correlation with the relative contents of collagen and positive correlation with the relative contents of elastin in each of the two groups. (5) C2 had negative correlation with the Gensini score of the coronary artery in each of the two groups.(6) CFPWV had negative correlation with C1 in each of the two groups.Conclusions(1) It can be concluded that hypertension can cause a decrease in large artery elasticity of CHD patients and that the changes in relative contents of collagen and elastin, as well as alterations in microstructures of the two components in the media of the aortic wall caused by hypertension are responsible for this decrease.(2) The elevated CFPWV and the decreased Cl can reflect the changes in collagen and elastin of the arotic media caused by hypertension.(3) C2 can reflect the severity of coronary artery atherosclerosis in CHD patients.