Fig. 2

a Spectral Doppler showing the monophasic wave of left brachial artery with homogeneous blood flow. (location for figure no.156). b Spectral Doppler showing the typical triphasic wave of right brachial artery and the well-defined contour and distribution. (location for figure no.156). c Spectral Doppler showing the atycal triphasic wave of right brachial artery due to the decreasing peripheral resistance. (location for figure no.156). d A rare special wave of right brachial artery was showed in Spectral Doppler. (location for figure no.156)