Correlation Between Carotid Elasticity Measured By Velocity Vector Imaging And Serum Lipid And Visfatin In Patients With Acute Ischemic Stroke

Background:Carotid atherosclerosis is known to be associated with incident ischemic stroke. Carotid intima-media thickness (IMT) is the structural change of the local vessel early atherosclerosis, whereas the decrease of carotid elastic properties is earlier than arterial thickening. The elasticity of large artery measured by conventional ultrasonographic techniques is known to be associated with cardiocerebrovascular disease and its risk factors. Velocity vector imaging (VVI), a novel technique based on speckle tracking, is regarded as a noninvasive, qualitative and quantitative method for evaluating the elasticity and motion function of myocardium and vessel wall. Previous research shows that VVI technique can reflect the changes of the elasticity and the movement characteristics of carotid artery in the early stage of carotid atherosclerosis. But limited data on the carotid elastic properties of ischemic stroke were assessed by VVI, and lack of a control study of bilateral carotid artery.In addition to the traditional risk factors for stroke found in the research of Framingham, such as age, blood lipid, hypertension, and diabetes, some new possible risk factors were found along with the further researches. Visfatin is a kind of specific visceral fat factor, which was discovered by Japanese scholar Fukuhara et al in 2005. Visfatin has a variety of biological functions. Recent studies have shown that visfatin is closely related to atherosclerosis. Some studies suggest that increased serum visfatin is an independent risk factor for the development of atherosclerosis in patients with ischemic cerebrovascular disease. So, visfatin may be involved in the pathogenesis of stroke.There is very little published research on the correlation between carotid elasticity and serum lipid and visfatin in patients with acute ischemic stroke (AIS). Ultrasonographic VVI technique was used in our study to assess carotid artery elastic properties in patients with AIS. And we also want to investigate whether the changes of carotid elasticity in patients with stroke were related to serum lipid and serum visfatin level. The role of serum lipids and serum visfatin in atherosclerosis may be further verified by the correlation study.Because one side of the internal carotid artery supplies the ipsilateral anterior cerebral circulation area, we hypothesized that the elastic properties of one side carotid artery are in relation to the site of stroke. As far as we know, this is the first study to investigate the differences of elastic properties between ipsilateral and contralateral common carotid artery of acute ischemic stroke in unilateral anterior circulation by VVI technique. Our aim is to seek for noninvasive imaging methods to predict stroke. Carotid stiffness measured by conventional ultrasound is known to be associated with ischemic stroke. However, few data can be found on the carotid elastic properties in AIS examined by VVI technique.Objective:1. To evaluate the elastic properties of carotid of patients with AIS using ultrasonic VVI technique, and to explore the relationship among carotid elasticity, serum lipid and visfatin in patients with AIS preliminary.2. To investigate the differences of elastic properties between ipsilateral and contralateral common carotid artery of AIS in unilateral anterior circulation by VVI technique, and aim to seek for noninvasive imaging methods to predict ischemic cerebrovascular disease.Methods:1. A total of 58 consecutive hospitalized patients (age 64±10 years) with initial onset of acute ischemic stroke verified by brain magnetic resonance imaging (MRI) from November 2009 to April 2010 at affiliated hospital of jining medical university were enrolled in the first part of this study. Age, gender and body mass index (BMI) matched 40 healthy volunteers were selected as the control group. The VVI parameters, including radial velocity (RV), circumferential strain (CS), circumferential strain rate (CSR), radial displacement (RD), as well as intima-media thickness of bilateral carotid were measured by ultrasound with VVI technique. Automatic biochemical analyzer was used to detect the serum levels of total cholesterol (TC), triglyceride (TG), low density lipoprotein-cholesterol (LDL-C), high density lipoprotein-cholesterol (HDL-C), and fasting blood glucose (FBG) of all subjects fasting 12 h at the second morning. Enzyme-linked immunosorbent assay (ELISA) method was used to detect the level of serum visfatin. To investigate the elastic properties of carotid of all subjects using ultrasonic WI technique, and to explore the relationship among carotid elasticity, serum lipid and visfatin in patients with AIS. Informed consent was obtained from each study subject. The study protocol was approved by the Institutional Review Committee at our institute.2. The second part of this study included 44 cases with unilateral anterior circulation acute ischemic stroke verified by brain MRI. Twenty-four lesions of the patients were in the right anterior circulation area while 20 lesions in the left anterior circulation area. Forty healthy volunteers as normal control were matched by age, gender and BMI. Echocardiography and Carotid ultrasound were performed. Biplane modified Simpson’s method was used for determination of left ventricular systolic function, including left ventricular ejection fraction (LVEF) and stroke volume (SV). Cardiac output (CO) was calculated as SV multiplied by heart rate. All the subjects had normal heart function. The stenosis of bilateral extracranial carotid arteries of the AIS patients were all less than 50%. The VVI parameters, including RV, CS, CSR, RD, as well as IMT of left and right carotid were measured and compared by ultrasound with VVI technique. According to the MRI, the carotid of every AIS patient was divided into ipsilateral and contralateral carotid based on the site of stroke. WI parameters and IMT between ipsilateral and contralateral carotid were compared.Results:1.1 The two groups did not show significant differences in age, gender, BMI, TC, HDL-C and HDL-C (P>0.05). Compared to the control group, the patients with AIS had elevated SBP, DBP, TG, FBG and visfatin (P<0.05)1.2 The VVI parameters of the average of bilateral carotid were significantly lower in the stroke group than those in the control group (P<0.01)1.3 Spearman Rank Correlation analysis between the VVI parameters and systolic blood pressure (SBP), diastolic blood pressure (DBP), TC, HDL-C, LDL-C, TQ FBG, IMT, and visfatin showed that carotid CS and RD of the AIS patients were negatively associated with TQ FBQ IMT and visfatin (P<0.05), but showed no significant association with SBP, DBP, TC, HDL-C, and LDL-C.1.4 Spearman Rank Correlation analysis between serum visfatin and SBP, DBP, TC, HDL-C, LDL-C, TG, FBG, and IMT showed that serum visfatin was positively associated with TQ FBQ and IMT (P<0.05)1.5 After adjustment of TG and FBQ partial correlation analysis showed that the serum level of visfatin was still positively correlated with CS and RD (P<0.05) in the patients with acute ischemic stroke, which suggested that this effects were independent of TG and FBG2.1 The control group and the group of patients with unilateral anterior circulation AIS did not show significant differences in age, gender, BMI, TC, HDL-C, LVEF, FS and CO (P>0.05). Compared to the control group, the group of patients with unilateral anterior circulation AIS had elevated SBP, DBP, and FBG (P<0.05)2.2 The VVI parameters and IMT showed no significant differences between left and right carotid in both groups (P>0.05). The VVI parameters of left, right and average of bilateral carotid were significantly lower in the stroke group than those in the control group (P<0.01), whereas left, right and average of bilateral carotid IMT of the stroke group were significantly thicker than those of the control group (P<0.01).2.3 According to the MRI, the bilateral carotid of every stroke patient was divided into ipsilateral and contralateral carotid. The VVI parameters of ipsilateral and contralateral carotid were significantly lower in the stroke group than those in the control group (P<0.01), whereas ipsilateral and contralateral carotid IMT of the stroke group were significantly thicker than those of the control group (P<0.01). The VVI parameters of ipsilateral carotid were significantly higher than those of the contralateral carotid (P<0.01). However, there was no significant difference of IMT between ipsilateral and contralateral carotid (P>0.05)Conclusions:1. Carotid CS and RD of the AIS patients were negatively associated with TG, FBG, IMT and visfatin.2. After adjustment of TG and FBG, the serum level of visfatin was still positively correlated with CS and RD in the patients with acute ischemic stroke, which suggested that these effects were independent of TG and FBG.3. Our study suggested that the decreased elastic properties response to carotid atherosclerosis was earlier than arterial thickening, and were negatively associated with TG, FBG, and visfatin. That may be helpful to provide theoretical basis for early intervention of atherosclerosis.4. WI may represent a novel method for non-invasively quantifying carotid elastic properties alteration associated with AIS.5. The decrease and differences of elastic properties of bilateral carotid could be earlier and sensitive indicators to predict AIS.6. We suggest todetect carotid elasticity by using ultrasonic VVI technology, combined with serum lipids, fast glucose and serum visfatin levels in the presence of high-risk groups of cerebrovascular disease for early screening. And during this period, drug intervention, which can lower serum lipids and glucose, reduce serum visfatin level, could improve vascular function, would help to delay the occurrence and development of atherosclerotic cerebrovascular disease.