The Relationship Between Low Ankle-brachisal Index And Intra-and Extra-cranial Atherosclerosis

Object:Ankle-brachial index (Ankle-Brachial Index, ABI) refers to the ratio of ankle systolic blood pressure and brachial artery systolic blood pressure, which has been widely used as the evaluation of peripheral vascular elasticity and an important indicator of atherosclerosis of Peripheral artery disease(PAD). ABI (<0.9) reduction in PAD diagnostic as a method has greatly increased rate of diagnosis of PAD, to make up for the missed diagnosis based solely on clinical manifestations. Atherosclerosis as a systemic disease, according to lesion site, can be expressed as heart, cerebral ischemic events and PAD. Cardiovascular, cerebrovascular ischemic events and PAD caused by atherosclerotic lesions can occur in the same individual simultaneously, and count for risk factors of relapse and progress. Therefore, the ABI test for the diagnosis of PAD, can still be used to predict the risk and prognosis of ischemic events in heart, brain. Domestic and international studies have confirmed the location of atherosclerosis in different ethnic groups. The predilection sites of the Asian population of AS is intracranial arteries and European and American Caucasian, extra-cranial arteries. In addition to different structure of the intra-cranial and extra-cranial arteries, causes for this difference include cultural differences between the race, vascular risk factors and different inter-ethnic intracranial vascular epithelial to withstand the lateral pressure. Based on this, we use the atherosclerotic intracranial arterial thrombosis patients as subjects and ABI as an indicator to reflect peripheral arterial and atherosclerotic lesions for the study, to investigate whether differences exist between atherosclerosis of the intracranial and extra-cranial individuals and whether ABI can be used as an indicator to reflect cerebral infarction in patients with intracranial and extra-cranial atherosclerosis.Methods:Our data included300patients with ischemic stroke and admitted to the Department of Neurology, Third Hospital of Hebei Medical University from December2011to December2012. All the patients were diagnosis by computed tomography, magnetic resonance imaging, transcranial doppler sonography and/or magnetic resonance angiography and were examined for other risk factors. All the patients were registered by general characteristics included age, sex, and other risk factors such as hypertension, hyperlipidemia, diabetes mellitus, CAD, current smoking, family history of CVD and so on.For ABI measurement, a standard sphygmomanometer and a Doppler device with an8-MHz continuous-wave probe was used. Measurement of upper-and lower-extremity blood pressure was performed after at least10minutes of rest. The patient was in a supine position. The blood pressure cuffs were placed above the elbow and the ankle on each side, then SBPs of the brachial, posterior tibial, and dorsalis pedis arteries were measured. ABI was calculated according to the AHA definition as the quotient of the higher of the systolic blood pressures of the2ankle arteries of that limb and the higher of the2brachial systolic blood pressures.We screened ischemic stroke patients who were identified as large-artery atherosclerosis (LAA) and small-artery occlusion(SAD), according to classic TOAST subtype. The LAA patients were classified into two groups based on the site of atherosclerosis. We compared the prevalence of abnormal ankle-brachial index (ABI) and the related risk factors between the groups.Carotid duplex ultrasonography and transcranial duppler ultrasonography (TCD), were used to determine ECS and IAS. All the patients were divided into two groups. The intra-cranial artery stenosis group, which only had a>50%stenosis of intra-cranial artery stenosis, did not have any extra-cranial artery stenosis. In contrast, the extra-cranial artery stenosis group, had a>50%stenosis of extra-cranial artery stenosis. The degree of extra-carotid artery stenosis was evaluated based on the criteria of American Society of Neuroimaging.Measurement data were shown as mean±standard deviation (SD), and numeration data in masccline number and constituent ratio.Making χ2-test analysis were used to compare characteristics between the ratio of the abnormal ankle brachial index with each group. And t test for the numerical variable data of the Gaussian distribution. Multiple logistic regression analysis was used to construct a model with abnormal ABI as the dependent bariable. P <0.05was considered statistically significant.SPSS13.0software was used for statistical analysis.Results:1.300ischemic stroke patients were analyzed. The mean age of all patients was64.45±10.412. The number of patients with SAD was81(27.0%) and with LAA was121(40.3%). Then121(40.5%) patients were admitted to IAS group, and53(17.7%) to ECS. About28.3%(85/300) of the patients had abnormal ABI.2. The rate of abnormal ABI in LAA patients is much higher than SAD patients (31.51%vs19.75%,χ2=4.023,p=0.045). The prevalence of abnormal ABI in ECS patients is47.17%, much higher than IAS patients (22.31%, χ2=10.867, p=0.001). Multivariable logistic regression identified peripheral artery disease (OR=2.759,95%CI:1.485-5.124) and smoke (OR=2.032,95%CI:1.093-3.779) as the independent risk factors for ECS, and hypertension (OR=1.957,95%CI:1.119-3.421) and male sex (OR=2.024,95%CI:1.251-3.274) for IAS. Peripheral artery disease wasn’t related to IAS. Multivariable logistic regression identified ECS (OR=2.667,p=0.002)、age (OR=1.815,p=0.010) and diabetes mellitus (OR=1.812, p=0.028) as the independent risk factors for low ABI.Conclusion:Vascular risk factors were not the same between intracranial artery disease and extra-cranial artery disease. The mechanism of atherosclerosis may differ between intracranial and extra-cranial artery diseases. Abnormal ABI often suggested carotid artery stenosis.