Which characteristic indicates a high-grade stenosis on Doppler examination?

A high-grade stenosis is characterized by significant narrowing of a blood vessel, leading to changes in blood flow patterns that can be detected through Doppler examination. One key aspect that indicates high-grade stenosis is an increased peak systolic velocity.

When a vessel narrows, the same volume of blood must flow through a smaller diameter, which causes an acceleration of blood flow through the stenotic area. This is reflected in an increase in peak systolic velocity. Typically, a peak systolic velocity greater than certain threshold values (specific to the vessel being examined) suggests that a high-grade stenosis is present.

In contrast, decreased peak systolic velocity is usually associated with either low-grade stenosis or significant distal occlusion where blood flow is impeded. Similarly, stable blood flow patterns without marked changes or disturbances do not suggest significant narrowing. Non-pulsatile flow is often indicative of severe obstruction or an arterial occlusion rather than stenosis.

Thus, an increased peak systolic velocity serves as a strong indicator of the presence of high-grade stenosis, making it the correct choice for this question.