Visualising velocity profiles in great arteries--a preliminary report.

Using a constant temperature anemometer and an L-shaped 1 mm conical hot-film anemometer probe, blood velocities were registered in a patient after implantation of a Starr-Edwards ball valve in the aortic position. Velocities were registered at 41 predetermined points in the ascending aorta, equally distributed over the cross-sectional area. Data were recorded on tape and later analysed to make three-dimensional plots of the velocity profile at 200 time intervals during one "mean" heart cycle, and a film of the velocity profile in this cycle was made. The film gave the impression of great velocity fluctuations at different places in the cross-sectional area.