Peak systolic velocity (PSV) is the highest velocity recorded on a spectral Doppler waveform during the systolic phase of the cardiac cycle. It is the primary parameter used to grade stenosis severity in vascular studies. In carotid ultrasound, an ICA PSV greater than 125 cm/s indicates at least 50% stenosis; PSV greater than 230 cm/s indicates 70–99% stenosis. PSV is also used to evaluate renal artery stenosis, mesenteric artery disease, and peripheral arterial occlusive disease.