[Analysis of the frequency of Doppler blood flow signals in the common carotid artery].

The authors carried out quantitative analysis of the spectrum of the Doppler blood flow signals in the common carotid artery in 48 healthy subjects in two age groups (16-28 and 51-83 years) and 29 patients after ischaemic stroke. In the young subjects the greatest range of the spectrum was covered by the 1-2 kHz band (40.2% of the area of spectrum diagram). In later age this value decreased to 32.9% and in the patients it was 22.3%. At the same time the area covered by the 0-1 kHz band increased, from 35.9% in young subjects to 50.4% in the older ones and 66.9% in the patients. The spectrum comprised, most frequently, the frequency range 0-5 kHz and had a tendency for narrowing in the patients after stroke. In cases of common carotid artery stenosis it was found to increase to 10 kHz at the site of the stenosis, while above and below the stenosis the spectrum was reduced to 2 kHz, with 90% of its area occupied by the 0-1 kHz band. these results indicate the possibility of quantitative determination of haemodynamic disturbances by means of frequency analysis of Doppler signals.