Vinkesteijn A S M, Ursem N T C, Struijk P C, Wladimiroff J W
Department of Obstetrics & Gynaecology, Erasmus Medical Centre, Rotterdam, The Netherlands.
Ultrasound Obstet Gynecol. 2004 Jan;23(1):19-22. doi: 10.1002/uog.949.
To study the power spectrum distribution of heart rate and umbilical artery flow velocity variability in fetuses with increased nuchal translucency thickness (NT).
Doppler velocity waveforms were collected from long-lasting (>20 s) umbilical artery recordings in 18 fetuses with increased NT (>3 mm) and 18 normal controls matched for gestational age at 11-14 (median, 12) weeks. The NT group included 11 abnormal karyotypes: trisomy 18 (n = 3), 45,X (n = 4), trisomy 21 (n = 3) and a balanced translocation. Absolute heart rate as well as the coefficient of variation for both beat-to-beat heart rate variability and umbilical artery blood flow velocity variability were determined. The ratios of the integrated low-frequency components (0.05-0.2 Hz) and the integrated high-frequency ones (0.25-1.6 Hz; LH ratio) from normalized power spectrum distributions were established to reflect sympathovagal balance.
The mean heart rate was not significantly different between the two groups. However, mean heart rate variability and time-averaged flow velocity variability were significantly increased in the NT group, while there was no significant difference in the LH ratios between the two groups. The mean umbilical artery pulsatility index was significantly higher in the NT group.
The autonomic nervous system does not seem to play a role in the altered cardiovascular homeostasis in the presence of increased fetal NT.
研究颈部半透明厚度（NT）增加的胎儿的心率和脐动脉血流速度变异性的功率谱分布。
从18例NT增加（>3mm）的胎儿及18例孕11 - 14周（中位数为12周）、孕周匹配的正常对照胎儿的长时间（>20s）脐动脉记录中采集多普勒速度波形。NT组包括11例异常核型：18三体（n = 3）、45,X（n = 4）、21三体（n = 3）和一种平衡易位。测定绝对心率以及逐搏心率变异性和脐动脉血流速度变异性的变异系数。建立归一化功率谱分布中低频成分（0.05 - 0.2Hz）与高频成分（0.25 - 1.6Hz；LH比值）的积分比值以反映交感迷走平衡。
两组间平均心率无显著差异。然而，NT组的平均心率变异性和时间平均血流速度变异性显著增加，而两组间LH比值无显著差异。NT组的平均脐动脉搏动指数显著更高。
在胎儿NT增加的情况下，自主神经系统似乎并未在心血管稳态改变中起作用。
