Abstract
We have been studying cerebral blood flow velocity of the bilateral internal carotid and vertebral arteries during each heart beat continuously and simultaneously. This study the calculation of compared the results of the averaged maximum velocity (AMV), which is very time consuming, with those of our new automatic analysis system, which we entitled the averaged maximum spectral density (AMSD) using a dual channel FFT analyzer.
AMSD is the arithmetical mean of the maximum value of the power spectrum (MVPS) . MVPS were recorded every 12.5 ms. When the moving averages of 4 MVPS exceed a certain preset value, the heart beat interval record is divided at that point and AMSD is calculated. After the preset value is reached, other divisions are inhibited for a preset duration. The reactivity of the cerebral arteries' velocity of each of 4 healthy males was analyzed before, during and after breath holding. Statistically significant changes occurred in 27 of 33 vessels. Mean values of every 10 seconds of AMV and AMSD showed the highest correlation. It seems that low correlation resulted from weakness of Doppler signals or high audionoise.
Even though vertebral blood flow requires careful attention for identification of preset values, we concluded that AMSD is valuable for overall cerebral blood flow monitoring.
