Hu H H, Kuo T B, Wong W J, Luk Y O, Chern C M, Hsu L C, Sheng W Y
Section of Cerebrovascular Disease, Veteran General Hospital-Taipei, Taiwan, Republic of China.
J Cereb Blood Flow Metab. 1999 Apr;19(4):460-5. doi: 10.1097/00004647-199904000-00012.
This study evaluates the validity of the transfer function analysis of spontaneous fluctuations of arterial blood pressure (ABP) and blood flow velocity of the middle cerebral artery (MCAFV) as a simple, convenient method to assess human cerebral autoregulation in patients with carotid stenosis. Eighty-three consecutive patients with various degrees of carotid stenosis and 37 healthy controls were enrolled. The carotid stenosis was graded based on the diagnostic criteria of duplex ultrasound. Instantaneous bilateral MCAFV and ABP of all participants were assessed noninvasively using transcranial Doppler sonography and the servocontrolled infrared finger plethysmography, respectively. Spectral analyses of ABP and MCAFV were performed by fast Fourier transform. The fluctuations in ABP as well as in MCAFV were diffracted into three components at specific frequency ranges designated as high-frequency (HF; 0.15 to 0.4 Hz), low-frequency (LF; 0.04 to 0.15 Hz), and very low-frequency (VLF; 0.016 to 0.04 Hz). Cross-spectral analysis was applied to quantify the coherence, transfer phase, and magnitude in individual HF, LF, and VLF components. Transcranial Doppler CO2 vasomotor reactivity was measured with 5% CO2 inhalation. The LF phase angle (r=-0.53, P<0.001); magnitude of VLF (r=-0.29, P=0.002), LF (r=-0.35, P<0.001), and HF (r=-0.47, P<0.001); and CO2 vasomotor reactivity (r=-0.66, P<0.001) were negatively correlated with the severity of stenosis. Patients with unilateral high-grade (greater than 90% stenosis) carotid stenosis demonstrated significant reduction in LF phase angle (P<0.001) and HF magnitude (P=0.018) on the ipsilateral side of the affected vessel compared with their contralateral side. The study also revealed a high sensitivity, specificity, and accuracy using LF phase angle and HF magnitude to detect a high-grade carotid stenosis. A strong correlation existed between the LF phase angle and the CO2 vasomotor reactivity test (r=0.62, P<0.001), and the correlation between the HF magnitude and the CO2 vasomotor reactivity (r=0.44, P<0.001) was statistically significant as well. We conclude that transfer function analysis of spontaneous fluctuations of MCAFV and ABP could be used to identify hemodynamically significant high-grade carotid stenosis with impaired cerebral autoregulation or vasomotor reserve.
本研究评估了动脉血压（ABP）自发波动与大脑中动脉血流速度（MCAFV）的传递函数分析作为一种简单、便捷的方法来评估颈动脉狭窄患者脑自动调节功能的有效性。连续纳入了83例不同程度颈动脉狭窄的患者和37名健康对照者。根据双功超声诊断标准对颈动脉狭窄进行分级。分别使用经颅多普勒超声和伺服控制红外手指体积描记法对所有参与者的双侧瞬时MCAFV和ABP进行无创评估。通过快速傅里叶变换对ABP和MCAFV进行频谱分析。ABP和MCAFV的波动在特定频率范围内被分解为三个分量，分别称为高频（HF；0.15至0.4Hz）、低频（LF；0.04至0.15Hz）和极低频（VLF；0.016至0.04Hz）。应用交叉谱分析来量化各个HF、LF和VLF分量中的相干性、传递相位和幅值。通过吸入5%二氧化碳来测量经颅多普勒二氧化碳血管运动反应性。LF相角（r=-0.53，P<0.001）；VLF幅值（r=-0.29，P=0.002）、LF幅值（r=-0.35，P<0.001）和HF幅值（r=-0.47，P<0.001）；以及二氧化碳血管运动反应性（r=-0.66，P<0.001）与狭窄严重程度呈负相关。与对侧相比，单侧高度（大于90%狭窄）颈动脉狭窄患者患侧血管同侧的LF相角（P<0.001）和HF幅值（P=0.018）显著降低。该研究还显示，使用LF相角和HF幅值检测高度颈动脉狭窄具有较高的敏感性、特异性和准确性。LF相角与二氧化碳血管运动反应性测试之间存在强相关性（r=0.62，P<0.001），HF幅值与二氧化碳血管运动反应性之间的相关性（r=0.44，P<0.001）也具有统计学意义。我们得出结论，MCAFV和ABP自发波动的传递函数分析可用于识别具有脑自动调节功能受损或血管运动储备受损的血流动力学显著高度颈动脉狭窄。
