Spatial Velocity Distributions in the Ascending Aorta of Healthy Humans and Cardiac Patients

Blood velocity profiles in the human ascending aorta were assessed with the aid of ultrasonic Doppler echocardiography. To this end, the transducer was placed in the suprasternal notch, and the spatial velocity profiles along an axis passing through the center of the aortic cross section were recorded by a multigate Doppler instrument. The profiles are analyzed with respect to characteristics independent of the angle of incidence and the cross sectional area. Data from 10 healthy individuals, 10 patients with hypertrophic obstructive cardiomyopathy (HOCM), and 10 patients with severe aortic insufficiency (AI) are compared. Five instantaneous profiles recorded at different times during systole and the temporal average of all profiles recorded during the entire cardiac cycle at 16 ms intervals are examined. Considerable differences between the three groups of subjects are observed visually as well as quantitatively in terms of specific parameters. The representation of the velocity maps in the form of contour graphs is particularly incisive. The results demonstrate that the temporal velocity patterns measured depend, in general, on both the disease and the location of the sampling volume within the aortic lumen. Reliable aortic volume flow rate measurements may have to be based on a method which takes into account the velocity at every point of the entire vascular cross section of patients with HOCM or AI.