A comparison between single gate and multigate ultrasonic Doppler measurements for the assessment of the velocity pattern in the human ascending aorta.

The velocity pattern in the ascending aorta of 15 healthy adults was measured quasisimultaneously from the Doppler-shifts produced in 16 gates distributed equally within the cross-section along a narrow ultrasound beam which centrally traversed the vessel upstream of the brachiocephalic trunk. A comparison between the time integrals of the velocities in gates 9 (centre line), 4 and 13 (off centre) and the time integral of the weighted mean of the velocities of all gates correlated with r = 0.90, SEE = 1.05 (gate 9), r = 0.90, SEE 0.88 (gate 4) and r = 0.92, SEE 0.94 (gate 13). A better correlation (r = 0.96, SEE = 0.60) was found between the linear mean of all gates and the weighted mean. These results show that Doppler measurements in single small gates are not appropriate to determine the average cross-sectional blood flow velocity in healthy adults.