The Ultrasound Assessment Of Endothelial Function And Its Clinical Value

Background and Objective Coronary atherosclerosis is characterized by an early loss endothelium-dependent vasodilation. However, the methods of assessing coronary endothelial function are invasive and difficult to repeat over time. Recently, a noninvasive ultrasound method has been widely used to measure flow-mediated dilation in the brachial artery as a surrogate for endothelial function. Non-invasive ultrasound techniques to assess flow-mediated vasodilation (FMD)and reactive hyperemia (RH) are frequently used to assess arterial endothelial vasodilator function. This study is to evaluate the effects of age on the endothelial function in healthy subjects and patients with coronary artery disease using highfrequency ultrasound. Meanwhile, the study sought to compare the arterial endothelial vasodilator function between normal person and patient with coronary heart disease.Material and Methods 428 normal volunteers (175 males and 253 females) (mean age 58.36+13. 82 years ) were enrolled in this study . We also included 89 patients with coronary heart disease (69 males and 20 females) (mean age 59.82 + 11. 65 years ) in this study. All of the patients had accepted coronary angiography and the diagnoses of coronary heart disease were confirmed. Patients with valvular heart disease, cardiomyopathy and congenital heart disease were excluded. All of them were measured using high resolution (7.0MHz) ultrasound and strain gauge by blood-pressure meter. Brachial artery diameter (DO) and Doppler blood flow velocities (VO) were measured before cuff charge. After 5 minute cuff occlusion, Doppler blood flow velocities (V1) were measured immediatelyafter cuff deflation.Brachial artery diameter (Dl) was measured 60-90 seconds after cuff deflation. These were as the brachial artery vasodilation, compared with baseline and expressed as a percent increase.Q: (blood flux) =60 7TVD74.Q0 (ml/min): (baseline blood flux), Ql (ral/min): (expressed bloodflux)oFMD (%): (Flow-mediated diameter) =(Dl-D0)/D0X 100%oRH (%): (Reactive hyperemia) =(Ql-Q0)/Q0X 100%Results1. In healthy person group , while the age increase, FMD and RH became step down. P< 0. 001. Analysis of FMD~Age: Correlative coefficient: r=-0.9822, P=0.003; Regressive equation: FMD=25.0086-0.2091*Age. Analysis of RH-Age: Correlative coefficient: r=-0.9688, P=0.001; Regressive equation: RH=238.2185-1.7201*Age.2. In coronary heart disease group, while the age increase, FMD and RH became step down either. P< 0.001. Analysis of FMD—Age: Correlative coefficient: r=-0.8064, P=0.028; Regressive equation: FMD=12.5752-0.1229*Age.Analysis of RH--Age: Correlative coefficient: r=-0.9526, P=0.003; Regressive equation: RH=105.9052-1.0084*Age.3. FMD and RH were significantly lower in coronary heart disease group than in normal subjects group. P< 0. 001.4. While the amount of the sick coronary artery increase, FMD and RH were significantly became step down. PO.01.5. FMD was above 10% in healthy human. But in patients with coronary heart disease FMD was down 6-7%. The more serious was coronary heart disease, the lower was FMD.