中塚 喬之¹, 原 正忠¹, 照屋 日出夫¹, 古幡 博², 吉村 正蔵¹

Takayuki NAKATSUKA¹, Masatada HARA¹, Hideo TERUYA¹, Hiroshi FURUHATA², Shozo YOSHIMURA¹

¹慈恵医大第四内科, ²慈恵医大ME研究室

¹The Fourth Dept. of Int. Med., Jikei Univ. School of Med., ²ME Laboratory, Jikei Univ. School of Med.

キーワード : aortic stenosis, turbulent flow, frequency analysis, frequency distribution, ultrasound pulse doppler flowmeter

It is already known that the more blood flow is disturbed, the more wide band frequency spectrum of blood flow signal obtained by the ultrasound pulsed Doppler flowmeter exhibits. The authors made frequency analysis of the blood flow signals of the ascending aorta obtained by the ultrasound pulsed Doppler flowmeter, and examined the possibility to evaluate the severity of aortic stenosis on the basis of the quantitative assessment of the frequency distribution.
The Doppler signals underwent A-D conversion in high speed, were analysed by a FFT program, and displayed on the bidirectional soundspectrogram. Instantaneous mean frequency and instantaneous frequency distribution which was shown as a standard deviation of the power spectrum were calculated, and then further mean systolic frequency, mean systolic frequency distribution and the ratio of the last two items were calculated. The frequency distribution of the spectrum was a good parameter to correlate with turbulency of the flow, and the ratio of the mean systolic frequency to the mean systolic frequency distribution was a good parameter to correlate with the severity of aortic stenosis.
The turbulent flow analysis by the pulsed Doppler flowmetry may be clinically useful for the evaluation of the severity of aortic stenosis.