| Objective To evaluate the reliability of ductus diameter measured by color coded Doppler echocardiography. Method Clinical, echocardiographic and cineangiographic data of 106 patients with PDA were reviewed retrospectively, ductus diameters determined by color Doppler and angiography were compared. Data of 6 representative cases were provided to reproduce computer mimic flow dynamic map using Fluent 6.2 software. Result In cases with angiographic ductus diameter (d1)smaller than 5mm, the echocardiographic diameter(d) correlated well with d1 but was significantly greater than the latter,(d-d1)averaged to +0.63mm, which can be readily explained by "color spill-over" Doppler sonographic mechanism. The situation was just opposite in cases with ductus d1 larger than 5mm, as (d-d1) averaged to -1.86mm. Difference between d and d1 became dramatic in quite a few large ductus, e.g,d-d1 reached 8.8mm in one extreme case. This paradoxical phenomenon was reproduced exactly by the computer reconstructed flow map. The authors propose to describe the phenomenon with the term "intraductal preferential flow".Conclusion Color Doppler measurement of ductal diameter can provide an estimation of the true diameter of ductus with poor reliability. Especially in large ductuses, the echocardiographic artifact can be misleading clinically hence should be used with great caution prior to interventional procedure. |
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