Fig. 1

a Continuous monitoring of the arterial pulsation waveform during flow-mediated dilation (FMD). The arterial diameter was monitored using amplitude- and brightness-mode ultrasonography with a linear array 10-MHz transducer (UNEXEF18G, UNEX, Nagoya, Japan). b Definition of the arterial pulse amplitude. The change in arterial diameter over the course of one cardiac cycle is presented. c Two characteristic examples of arterial pulsation behavior during FMD. The arterial pulse amplitude increased during FMD in Patient 1, whereas it decreased in Patient 2. d The arterial pulse amplitude is plotted along the time course of FMD for Patients 1 and 2