Arteriosclerosis is the pathophysiological basis of various cardiovascular system diseases, and early screening benefits prevention of cardiovascular diseases. Currently, there are many methods for evaluating early arteriosclerosis and functional lesion, including visualized imaging and arterial stiffness functional exanimation (pulse wave velocity, AIx, ankle brachial index, pulse pressure and atherogenic index). AIx can reflect arterial stiffness degree and has aroused increasing attention in the diagnosis of early arteriosclerosis.
The present study investigated the AIx in normal people of Xinjiang Uygur for the first time. Results showed that the female AIx was greater than male AIx in different age groups, and multiple stepwise regression analysis showed sex was an influential factor of AIx, consistent with studies of other population[4-6]. Xinjiang Uygur female AIx was greater than male AIx, potentially because female height was shorter than the male, and the distance between the heart and reflection point was nearer, leading to shorter reflected wave recovery duration.
In addition, results from the present study showed that cSBP and SBP were influential factors of Xinjiang Uygur AIx, consistent with domestic study results[7], implying close correlation between blood pressure level and arterial elasticity function. RAS is activated under hypertension, and angiotensin II can induce vascular endothelial cells apoptosis, endothelial functional disorder, and participate in vascular chronic inflammatory reaction and smooth muscle proliferation, resulting in vascular damage and decreased vascular elasticity[8].
In the present study, AIx of male and female of Xinjiang Uygur was increased with age. Correlation analysis showed that AIx was positively correlated with age in male and female, even if the other factors were corrected. Moreover, multiple stepwise regression analysis revealed that age was an influential factor for male and female AIx, consistent with previous results[9-12]. Age is a major factor for arteriosclerosis, because arterial wall tunica intima is thickened, vascular smooth muscle over-grows, elastic layer of large artery renews, and elastic fibers break, which induce arterial wall thickening and sclerosis, decreased elasticity. Early reaction of these changes is shown in pressure waveform alterations, such as antedisplacement of reflected wave, accelerated reflected wave transduction. The reflected wave overlays at advanced central systolic stage, which increases cardiac load and increases AIx[13].
In addition, CRP was one factor that influenced AIx. One study reported that CRP was correlated with AIx, even if the related factors have been corrected[14]. CRP is a reactive protein in acute inflammation. It plays opsonification role and can activate complement, promote phagocytosis, and stimulate tissue factor expression at monocyte surface. CRP plays a direct pathopoiesis effect in vascular injury, and a pro-inflammatory factor in atherosclerosis[15]. CRP might induce blood vessel endothelium functional disorder through the mechanisms as follows: (1) CRP can reduce nitric oxide synthase activities in endothelium by decoupling, resulting in peroxide product increase, nitric oxide synthesis reduction and endothelium dysfunction[16-17]. (2) CRP binds receptors of ligand, lipoprotein, monocyte, and granulocyte, activates these receptors through activating complement system, leading to blood vessel endothelium injury[18]. (3) CRP can release and activate nuclear factor-κB through inducing tumor necrosis factor α to induce inflammation-related gene expression and inflammatory media release, further activating vascular endothelial cells and leading to blood vessel endothelium functional disorder[19-20]. Damaged blood vessel endothelium function is an early mark of atherosclerosis. Studies have shown that endothelium function is related to AIx and might participate in AIx regulation[21-22]. This might be one mechanism by which CRP influences AIx.
In summary, AIx in normal people of Xinjiang Uygur was correlated with age. Age, cSBP, SBP and CRP were influential factors of AIx.
