Three-Dimensional Visualization of Velocity Profiles in the Ascending Aorta in Humans.

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Abstract
Blood velocities were recorded intraoperatively in the ascending aorta approximately 6 cm downstream of the aortic annulus in eight patients with normal aortic valves (prior to coronary bypass surgery) and in seven patients after implantation of a St. Jude Medical valve (4) or Starr-Edwards Silastic Ball valve (3) in the aortic position by means of constant temperature hot-film anemometry. The velocities were measured during 5-15 heart cycles at 41 predetermined measurement points almost evenly distributed in the cross sectional area. Velocity profiles were visualized three-dimensionally at 100 time intervals during one mean heart cycle. The standard deviation of velocities was correspondingly three-dimensionally visualized. For the patients with normal aortic valves the velocity profiles were generally flat but skew, with the highest velocity closer to the left vessel wall at the start of systole. During systole the skewness turned counterclockwise with the highest velocities closer to the posterior, right and finally anterior vessel wall at the end of systole. In patients with an artificial heart valve in the aortic position the design of the valve was reflected on the contour of the profiles. The findings correspond well with model studies.