Variation of aortic blood velocity with age at rest and during exercise in normal subjects.

The effect of age on aortic blood velocity signal and its derived indices of left ventricular function namely peak velocity, stroke distance (the velocity-time integral) and minute distance (stroke distance x heart rate) was studied at rest and at maximal-tolerated supine exercise using a 2-mHz continuous-wave Doppler ultrasound applied via the suprasternal notch in 66 normal healthy volunteers. The peak velocity, stroke distance and the minute distance, both at rest and at maximal exercise decreased with advancing age by 1-1.1% per annum between the ages of 20 and 70 years. Accordingly a method for age-adjustment of the peak velocity, stroke and minute distances was introduced for clinical use in assessing individual subjects. These results indicate that age is an important variable affecting aortic blood velocity and its derived variables as non-invasive measures of left ventricular function both at rest and with exercise. The relationship with age is an important consideration when assessing individual subjects.