The Importance of Assessment of Endothelial Function According to the Time Course of Flow-mediated Dilation of the Brachial Artery

Ultrasonography is widely used to evaluate atherosclerosis. Therefore, many ultrasound parameters exist, each with its own clinical implications. Many reports have shown that these ultrasound parameters are useful for evaluating the progression of atherosclerosis or the risk of cardiovascular disease in healthy persons and in persons with cardiovascular risk factors. Ultrasound parameters are categorized as either structural or functional parameters. Particularly in the early stage of atherosclerosis, functional parameters are useful for evaluating the risk of the further development of atherosclerosis. We have also reported that the pulsatility index of the brachial artery is related to atherothrombotic infarctions in high-risk elderly subjects1. Next, we studied flow-mediated dilation (FMD) as a functional parameter in the early stage of atherosclerosis. FMD is believed to be associated with endothelial nitric oxide (NO) synthesis. Furthermore, NO has the ability to prevent progression in the early stage of atherosclerosis. Guideline for FMD measurement have already been established2. FMD has been defined as the rate of brachial artery vasodilation 60 seconds after a sphygmomanometric cuff is deflated after being inflated for 5 minutes to a pressure 50mmHg greater than the systolic blood pressure.