Automated analysis of flow convergence proximal to regurgitant orifices: flow rate calculation using digital Doppler velocity maps

To automate quantification of valvular regurgitation, the authors developed an algorithm which uses the full proximal convergence zone (output as a digital map) to automatically define the orifice center and calculate the flow rate. For a user defined region of interest, the actual velocity field is compared with the expected velocity map generated by the function ν=(Qcosψ/2πr² ), where r is the distance from the test center, ψ the angle between the converging velocity and the ultrasound beam, and Q the flow rate which is being solved for. The optimal orifice center is that point which maximizes the correlation between observed and predicted velocity. In vitro testing revealed good agreement with flow rate: r=0.98, ΔQ=-3.7±15.8 cm³ /sec