Systems and methods are provided for assessing patient blood flow using video image processing. According to one aspect, a method of analyzing at least one blood flow characteristic of a patient includes capturing a video including a plurality of frames of an arterio-venous (AV) fistula on the patient； amplifying motion in the video to produce a motion- amplified video； determining a difference in intensity between consecutive frames in the motion-amplified video to produce a time-function of an amplitude of the optic flow representing movement in an area of interest on the patient； and determining the at least one blood flow characteristic of the patient based on the time-function.
