e170 Article TypeCo respondence To the Editor:

We read with great interest the recent article by Dr Mahadevia and colleagues1 about altered systolic flow and aortopathy with bicuspid aortic valve (BAV) and the related editorial by Drs Uretsky and Gillam.2 We are pleased that the hemodynamic parameter of flow displace-ment performed well. It showed the clearest differences between patients with BAVs and control subjects and correlated with the pre-arch dilation seen in patients with right noncoronary leaflet fusion.1 Our experience with the parameter has been equally encouraging. It is easy to measure, shows excellent reproducibility, and appears to correlate well with aortic growth in initial application.3 We would like to point out, however, a technical difference between how Mahadevia et al used flow displacement and how it was originally intended. The parameter was correctly used to measure the distance between the “center of velocity ” of forward flow and the anatomic center of th