A vector based approach to age-related changes of Doppler velocity waveforms in the brachial artery

The shape of blood flow velocity wave has been correlated with age. The continuous wave Doppler ultrasound technique was used to obtain the blood flow velocity from the brachial arteries in 40 subjects of different age. The blood flow velocity was analysed by means of the Fourier method. The changes of relative values of harmonics were observed according to age. The second harmonic was maximum for the young and the first one for the old. To quantify these changes the vector formed from the first eight moduli was introduced. The angle between the vector so defined and a certain reference vector was accepted as a measure of the Fourier transform. Continuous alteration of wave shape described by angle has been observed according to age. The correlation between angle and age was r = 0.79 (p less than 0.001).