Three-dimensional visualization of velocity profiles in the ascending aorta in dogs, measured with a hot-film anemometer.

Three-dimensional blood velocity profiles were registered in the ascending aorta of dogs approximately 2 and 5 cm above the aortic valves by means of constant temperature hot-film anemometry. The velocity was measured at 41 predetermined points of measurement evenly distributed over the cross-sectional area. Later data analyses using a three-dimensional plotting system, visualized velocity profiles at 200 time intervals during one mean heart cycle. The overall appearance of the profiles was that of a flat transitional flow with a slight skewness. The highest velocity was found nearer to the posterior and left vessel wall. The skewness started during top systole and persisted to the beginning of diastole. Furthermore, many small velocity fluctuations were seen during top systole, but they might also be caused by secondary rotational flow phenomena. This new three-dimensional and dynamic method for visualizing velocity profiles seems to offer advantages, as it demonstrates the total velocity profile all over the cross-sectional area.