Investigation on the peak time of endothelium-dependent dilatation by ultrasound

Objective To observe the peak time and peak value of endothelium-dependent dilatation (EDD) after continuous measurement of internal diameter of brachial artery under reactive hyperemia by colour Doppler ultrasound in order to investigate the accuracy of this method. Methods In this experiment, 30 patients with hypertensive, hyperlipemia or diabetes (dysfunction group) and healthy subjects (control group) were enrolled. EDD and its peak time and peak value of the two groups were measured. The first measurement of brachial artery under reactive hyperemia was at about 20 sec after release and every 15 sec until the peak value dropped. Results Compared with control group, vasodilatation of brachial artery under reactive hyperemia was significantly lower in dysfunction group ( p0.01), which was 10% lower than normal value of EDD. The peak time underreactive hyperemia in dysfunction group and control group was 67.33±11.32 and 64.07±12.36 sec, and the frequency of peak value after continuous measurement was 1.33±0.66 and 1.30±0.53 times,respectively,which had no significant diference ( p0.05). Conclusion There are individual differences in the peak time of brachial artery under reactive hyperemia. The first measurement is ideal at 35 sec after vasodilatation, continuously measured at no more than 15 sec as an interval and the observation period shall be focused at50-80 sec, which makes the measurement of EDD more accurately.