Velocity distribution model for normal blood flow in the human ascending aorta.

During the study of velocities in the human ascending aorta it became necessary to establish a method for two-dimensional velocity profiles from discrete velocity data obtained from different heartbeats and with different techniques. A descriptive geometrical model was therefore developed and expanded to 16 elements each containing 16 constants by a serial optimising technique using a least-squares method. Published data from two different studies on velocity distribution in the ascending aorta comprising six subjects with normal aortic valves were used. Three-dimensional graphic displays of velocity profile at different time intervals of the heart cycle clearly show common features of distribution of velocity at a point 6 cm above the aortic valve. There was a pronounced skewness with clockwise rotation of the skewness direction during systole, reversed flow directed towards the left coronary sinus of Valsalva in late systole and early diastole concomitant with secondary flow augmentation along the opposite wall of the aorta. Consistent plane-symmetric features during the heart cycle could not be demonstrated.