Relationships Between Carotid, Femoral Artery Intima-media Thickness And Endothelial Dilated Function In Patients With Coronary Artery Disease

BackgroundCoronary artery disease(CAD) is common disease and its incidence has been increasing year by year in our country.Now it has become a serious threat to human health,so it's very important to detect early atherosclerosis and take active prevention and treatment.Though coronary angiography(CAG) has been the "gold standard" to diagnose the coronary heart disease,it costs a lot and is invasive and need advanced equipments that limited its application,it can't be widely applied and it's hard to monitor patient's condition and prognosis.Now,it is a new topic to find an economical and simple method to assess coronary heart disease in the history of prevention and treatment of coronary heart disease.The main cause of CAD is coronary atherosclerosis.As the coronary artery and peripheral artery are in the same vascular beds,the atherosclerosis of them is affected by the same risk factors,pathogenesis and pathophysiology processes. Atherosclerosis is a diffuse process that starts early in childhood to progress symptomatically and its pathological process can be divided into three stages: vascular endothelial dysfunction,vascular intimal thickening and the formation of atherosclerotic plaque,vascular endothelial dysfunction and intimal thickening are the early stages of atherosclerosis,then the thickening vascular intimal can progress to be atherosclerotic plaque,that's the advanced stage.Intima-media thickness(IMT) is the thickness of intimal and media arterial wall, it is involved in the initiation of atherosclerosis and considered to be an early sign of atherosclerosis.In 1986,Pignoli et al first described the method of using highresolution ultrasound to measure IMT and compared this method to histopathological method,found that these two methods of IMT measurement had no significant differences,so the noninvasive ultrasound can accurately measure the IMT of the large,middle sized blood vessels.The ultrasound expression of the normal arterial wall is named as "double lines sign",there is a hypoechoic area between the two hyperechoic lines,the distance between the two hyperechoic lines is IMT.Since the invention of color Doppler ultrasound,it has become a main clinical method of detecting peripheral artery atherosclerosis because of its economy,simpleness, noninvasion,etc.The peripheral main arteries such as carotid artery,femoral artery are anatomical fixed,superficial,easy to identify and find,can be directly measured by ultrasound.It is possible to observe the coronary atherosclerotic damage indirectly in the way of observing the peripheral vascular morphology by small and light high-frequency probe.Recent years,lots of researches at home and abroad attempt to explore the relationships between carotid,femoral artery atherosclerosis and coronary heart disease,it is not known yet that which artery atherosclerosis is more closely related to CAD.In 1980,Furchgott et al first discovered vascular endothelial cells can secrete vascular endothelium-derived relaxing factor(EDRF),later it was confirmed that the chemical composition of EDRF was nitric oxide,so we can say nitric oxide is an important endocrine vascular relaxing factor.In 1992,Celermajer et al first applied the noninvasive high frequency ultrasound to evaluate the vascular endothelial function(flow-mediated dilation,FMD),they applied the high frequency ultrasound to evaluate the brachial artery and femoral artery flow mediated endothelium-dependent vasodilation and nitroglycerin induced non-endothelium-dependent vasodilation in smokers,family hypercholesterolemia children and patients with CAD.Anderson et al in 1995 applied the CAG and FMD in the brachial artery to confirm the correlation between coronary endothelial function and brachial artery endothelial function.Now the FMD in the brachial artery is generally used in large-scale clinical trials.More and more recent researches have found that vascular endothelial dysfunction is involved in the onset of many cardiovascular diseases and is the initial event of atherosclerosis(promoter).At present,it is available to observe the coronary atherosclerotic damage indirectly in the way of observing the peripheral vascular morphological and functional changes by high-frequency ultrasound.It becomes popular to study the correlations between either peripheral atherosclerosis or brachial artery FMD and CAD,but the correlations between them are not clear.In our study,we applied the high-frequency ultrasound to measure the carotid,femoral artery IMT and brachial artery FMD in patients with CAD,the aim of this study was to examine whether CAD could be detected based on FMD of the brachial artery and/or IMT of the carotid,femoral artery in patients with CAD.Objective1.To explore the feasibility of the brachial,carotid and femoral artery as a window reflecting coronary atherosclerosis.2.To investigate the severity of peripheral and coronary artery atherosclerosis in patients with CAD. 3.To explore the correlation between the severity of coronary atherosclerosis and IMT in carotid,femoral artery as well as FMD in the brachial artery.4.To explore the correlation between IMT in carotid,femoral artery and FMD in the brachial artery.Methods1.A total of 105 consecutive patients who underwent CAG were divided into normal group(29 patients) and CAD group(76 patients) according to the results of coronary angiography.All the patients admitted to the hospital were recorded their information:family history and personal history of cardiovascular event,smoking and living habits.A fasting blood sample was collected in the morning before cardiac catheterization for analysis of the following parameters using standard techniques: glucose,total cholesterol(TC),triglycerides(TG),high-density lipoprotein cholesterol(HDL-C),low density lipoprotein cholesterol(LDL-C),uric acid(UC).2.Coronary angiography was performed with standard Judkins techniques. The extent of CAD was coded according to the number of major coronary vessels with luminal stenosis＞50%.According to the results of coronary angiography,all the patients were divided into normal group(29 patients) and CAD group(76 patients),the CAD group(76 patients) was divided into one-vessel stenosis group(34 patients) and multi-vessel stenosis group(42patients).Gensini score was used to give a measure of severity and extent of coronary atherosclerosis,the higher the Gensini score is,the more serious the CAD is.3.Ultrasound measurement of IMT in the carotid and femoral artery B-mode ultrasonographic examination was performed in all patients,using a 8-13 MHz transducer(Acuson Sequoia-512).Scanning included left and right carotid and femoral arteries;all scans were performed by the same operator who was blinded to the coronary angiographic results.The carotid artery image was focused in the far wall and 3 segments were identified on each side:the distal 1.0 cm of the common carotid proximal to the bifurcation,the carotid bulb,and the proximal 1.0 cm of the internal carotid artery.A 1.0 cm long arterial segment proximal to the femoral bifurcation was defined as the common femoral artery segment.The mean value of bilateral carotid artery and femoral artery IMT is the carotid IMT,femoral artery IMT respectively.4.Ultrasound measurement of FMD in the brachial artery B-mode ultrasonographic examination was performed in all patients,using a 8-13 MHz transducer(Acuson Sequoia-512).Measure the baseline(DO) and flow mediated dilation(D1) brachial artery diameter respectively. (FMD%) =(D1 - DO) / D0×100%.5.Statistical analysisSPSS 13.0 statistical soft was used.The measurement data was shown as mean±SD((?)±s) and the count data was shown as percentage.The compared of measurement data in two groups was tested by t test,count data was measured byχ~2 test.In our study,the equal variance test of all the groups were not assumed,the compared of multi groups was tested by Welch one-way ANOVA,multiple comparison in different groups was tested by Dunnet's T3.The compared of count data in multi-groups was tested byχ~2 test,multiple comparison in different groups was tested by 2 independent samples test.The correlation between the IMT in carotid, femoral artery and FMD in the brachial artery was tested by Spearman rank correlation.The correlation between the severity of CAD and the IMT in carotid, femoral artery or FMD in the brachial artery was also tested by Spearman rank correlation.Statistical significance is defined as P＜0.05 on two-tailed testing.Results1.Comparisons of IMT in carotid,femoral artery and FMD in the brachial artery among different groups.FMD was significantly lower and IMT of the carotid,femoral were significantly higher in CAD group,comparing with normal group(all P＜0.001).There were significant differences in brachial artery FMD and carotid,femoral IMT between one-vessel and multi-vessel stenosis groups(all P＜0.001);2.The correlation between the severity of CAD and the IMT in carotid, femoral artery or FMD in the brachial artery.The Gensini score was positively related with carotid,femoral IMT and was negatively related with FMD(r=0.63,r=0.75,r=-0.85 respectively,all P＜0.001).3.The correlation between the IMT from carotid,femoral arteries and FMD in the brachial artery.There was a significant negative correlation between FMD and IMT(all P＜0.001).Conclusion1.The peripheral main arteries such as carotid artery,femoral artery are anatomical fixed,superficial and easy to identify,so the noninvasive high frequency ultrasound can directly measure the IMT in the carotid and femoral artery.As the ultrasound is economical,simple,noninvasive and accurate,it's a good method to detect the peripheral artery atherosclerosis.2.IMT from carotid and femoral arteries increased significantly and FMD in the brachial artery decreased significantly with an increase in CAD extent.3.IMT in the carotid,femoral artery and FMD in the brachial artery correlate significantly with the severity and extent of CAD,so the peripheral artery atherosclerosis can reflect the coronary atherosclerosis indirectly.4.The IMT from carotid and femoral arteries increased significantly and brachial artery endothelial-dependent vasodilation was damaged in patients with CAD.The peripheral artery atherosclerosis can reflect coronary atherosclerosis and help to diagnose the CAD,so it is worthy of further clinical application.