velocity ratio
Comparison of peak velocities between stenotic and normal vessel segments to quantify stenosis severity.
Full Definition
Velocity ratio is a hemodynamic parameter calculated by comparing the peak systolic velocity at the site of maximal stenosis to the velocity in a normal reference segment, typically measured proximal to the lesion. This ratio helps quantify the severity of arterial stenosis and provides standardized criteria for grading vascular disease across different vessel sizes and anatomical locations. Velocity ratios are particularly valuable in carotid artery evaluation, where specific thresholds guide clinical management decisions. The calculation normalizes for individual variations in cardiac output and provides more reliable stenosis assessment than absolute velocity measurements alone.
Usage
Usage note: Always specify reference segment location and calculation methodology.
In Context
- "The internal carotid artery velocity ratio was 3.8, indicating severe stenosis requiring intervention." — Carotid Doppler ultrasound
- "Velocity ratio calculations were performed using the highest stenotic velocity compared to the pre-stenotic segment." — Vascular laboratory protocol