Preliminary Application Of Velocity Vector Imaging In Arterial Remodeling

Background and Purpose:Arteries are the vessels away from the heart with the thick wall. They have more elastic fibers with great elasticity. The innermost layer of the arteries is the tunica intima, divided into endothelia,subendothelial layer and elastic layer. Large arteries include aorta,anonyma,common carotid artery,subclavicular artery et al. with multiple elastic layers,much more elastic fibers and less smooth muscle. So great arteries are also called elastic arteries. Thick muscular bands are found in the tunica media of the medium-sized arteries.Arterial remodeling is the process regulated by genes, with the changes of molecules, cells and interstitial which could have the expression of the changes morphologically and functionally. It is affected by the hemodynamic load,activation of neuroendocrine et al. Lipid,vascular smooth muscle,collagen participate in the process, but the cells of arterial wall play the main roles.With the improvement of living, longevity and the changes of customs, atherosclerosis has the high incidence in China. Atherosclerosis is one of the most important diseases affecting arterial transportation. The stenosis and spasm of the arteries may cause ischemia and infarction of remote tissue and organ. Plague is the signal of vascular pathological change. It is worth discussing that the changes of mechanical properties and functions of arterial wall caused by plagues. So it is important to master the discipline of arterial remodeling to prevention,intervention and treatment of atherosclerosis. For a long time, many scholars have the exploration in arterial remodeling, especially the atherosclerosis. Currently, in addition to the biochemical indexes reflecting the function of intima(vWF,ET,CRP,Sicam-1,E-selectin et al.),angiograpy,intravascular ultrasound imaging,ultrasonography,pulse wave velocity,augmentation index,diastolic pulse contour analysis are all exploited clinically to arterial function. But the limitations are obvious. Current non-invasive method can not meet the need of the doctors to the prevention,intervention and treatment of arterial diseases in the early stage. It limits the process of the study of vascular remodeling to some extent. Velocity vector imaging technology is convenient, making up the deficiency of other methods.Velocity Vector Imaging technology, developed by Siemens Company, is an advanced two-dimensional quantitative tool for assessment of global and regional myocardial muscle and motion mechanics firstly. The principal technique of VVI is speckle tracking, pixel tracking and other tracking methods. Visual and quantitative data output include velocity, strain, strain rate, ejection fraction, rotation, displacement and volume. Measures cardiac motion from any imaging view, any imaging window, enabling simple and intuitive visualization through use of moving vectors. It uses individual vectors to display direction and relative velocity of frame-to-frame tissue movement, delivering motion measurement at any point in the cardiac cycle. Moreover, it quickly gathers information for many clinical applications including rapid assessment of ventricular synergy in heart failure. It has more applications in the heart and vessel of the adults, children, fetus transesophageally or intravascularly.Benefits to traditional ultrasound:1. VVI is independent of angles because it is not related to Doppler effect. It is a visual and quantitative method for assessing cardiac mechanics, or the dynamics of cardiac motion.2. Measures cardiac motion in any direction from any imaging view, any imaging window.3. Evaluate the motion of endocardium and epicardium simultaneously. 4.VVI can fixes the center of radial movement automatically, tracks the intima of CCA on the basis of the monitor points. The media-adventitia interface of the carotid arterial wall is manually traced from a still frame and automatically tracked by the software. Display of the direction and magnitude of wall velocities throughout the cardiac cycle was obtained with the frame of reference at the center of the artery.This study has examined the impacts of age and sex on CCA, popliteal artery, brachial artery remodeling using VVI, comparing the arterial macro and microbiological structure mechanics of the young and the old; evaluated the change of arterial elasticity; preliminarily evaluated the changes of structural mechanics of carotid plaques using VVI.PartⅠDetection of arterial remodeling and elastic changes with the age in CCA,popliteal artery and brachial artery by VVIAbstract Objective To analyze the arterial remodeling and elastic changes with the age in CCA, popliteal artery and brachial artery by VVI. Methods Seventy six young healthy subjects(25.1±2.7岁,36 male 40 female)and sixty old healthy subjects (65.8±3.9岁,40 male,40 female) were recruited from the Heath Examination Center of Qilu Hospital, Shandong University. No subjects had any history of hypercholesterolemia, hypertension, insulin resistance, or diabetes. All old women were post-menopausal who had not hormone replacement therapy. All measurements were performed after those were requested to fast for 8 hours and abstain from caffeine and/or alcohol for 8 hours. To detect the right side of CCA,popliteal artery and brachial artery by VVI. Measurement of peak radial velocity, strain, strain rate, et al. were performed on each artery, and of intima-medial thickness, lumen diameter and IMT/lumen ratio were implemented at same time. Analyze the characteristics of arterial remodeling caused by aging. Results Regardless of CCA,PA and BA, IMT and lumen diameter increased with age; IMT and internal diameter for each artery, were lager in both young and old men than in the corresponding groups of women; the systolic maximum velocity, strain and strain rate of each artery long axis were lower in men than women; the systolic maximum velocity long axis of anterior wall is higher than that of posterior wall, with higher strain posteriorly and a little higher strain rate posteriorly, but they have not statistical significance; The lumen diameter of CCA is wider than that of PA and BA; the systolic maximum velocity long axis, the strain and strain rate of CCA were higher than those of PA; the systolic maximum velocity, strain and strain rate of CCA, BA and PA long axis in the old subjects were lower than those in the young. Conclusion The remodeling of the arterial wall happens and the elasticity decreases with ageing. The WI could evaluate the microbiological structure mechanics of different arteries with sex and age, providing a new way to further study the physiological and pathological arterial remodeling. It confirms the atherosclerosis is diffused pathological change on multiple different arterial basis. WI may be a new mean of exploring the mechanism of atherosclerosis and a useful marker of prevention, treatment and drug evaluation of atherosclerosis.PART II Preliminary evaluation of the changes of structural mechanics in carotid plaques using WIAbstract: Objective To evaluate the changes of structural mechanics in carotid plaques preliminarily using WI. Methods Fifty subjects(35 male,15 female,62.9±5.7 years) were recruited from the inpatients of Qilu Hospital, Shandong University, including 29 cerebral infarction,11 hypertension,10 diabetes mellitus with 67 solitary atherosclerotic plaques on either side of common carotid artery. All the patients were in the sinus rhythm and echocardiography were carried out to exclude the impact of abnormal cardiac structure before measurement. All measurements were performed after those were requested to fast for 8 hours and abstain from caffeine and/or alcohol for 8 hours. To observe the motion characteristics of carotid plaques and non-plaque area, analyze the peak systolic velocity, strain, strain rate using VVI. Results IMT of plaques were significantly thicker than non-plaque area. Longitudinal and circumferential velocity, strain and strain rate were significantly lower than non-plaque area. We can not get the values of that of radial direction because of the thin wall of non-plaque area. Longitudinal strain changed greatly along the plaque. The shoulder systolic strain was higher. Velocity vector in the non-plaque area displayed unanimously with better synchronization, and disordered in the plaques with poor synchronization. Conclusion It is an effective means to evaluate the changes of structural mechanics in carotid plaques using VVI.Conclusion1. The remodeling of the arterial wall happens and the elasticity decreases with ageing. The VVI could evaluate the microbiological structure mechanics of different arteries with sex and age, providing a new way to further study the physiological and pathological arterial remodeling. It confirms the atherosclerosis is diffused pathological change on multiple different arterial basis. VVI may be a new mean of exploring the mechanism of atherosclerosis and a useful marker of prevention, treatment and drug evaluation of atherosclerosis.2. IMT of plaques was significantly thicker than non-plaque area. Longitudinal and circumferential velocity, strain and strain rate were significantly lower than non-plaque area. We can not get the values of that of radial direction because of the thin wall of non-plaque area. Longitudinal strain changed greatly along the plaque. The shoulder systolic strain was higher. Velocity vector in the non-plaque area displayed unanimously with better synchronization, and disordered in the plaques with poor synchronization. It is an effective means to evaluate the changes of structural mechanics in carotid plaques using VVI. Main Innovative Points1. This study was the first to investigate the CCA, BA, PA simultaneously using WI to prove atherosclerosis is diffused pathological change on multiple different arterial basis.2. This study was the first to evaluate the microbiological structure mechanics of different arteries with sex and age.3. This study was the first to discuss the mechanical properties of atherosclerotic plaques in the circumferential, longitudinal and radial direction in humans, comparing to the non-plaques area.