Zhou Y Q, Faerestrand S, Matre K
Medical Department A, University of Bergen, Haukeland Hospital, Norway.
Eur Heart J. 1995 Mar;16(3):383-93. doi: 10.1093/oxfordjournals.eurheartj.a060922.
The cross-sectional velocity distribution in the left ventricular outflow tract was studied in 40 patients with valvular aortic stenosis. Doppler colour flow mapping and a time-interpolation method were used to construct the cross-sectional velocity and time-velocity integral (TVI) profiles at different levels. By using pulsed Doppler, the subaortic flow velocity was sampled from the anterior, middle and posterior regions along the diameter of the left ventricular outflow tract (at 0.5 to 1.0 cm proximal to the aortic anulus) in the apical long axis view. Thus, for each patient, three aortic valve areas were calculated by using the continuity equation. Each patient was assigned to one of three subgroups according to the left ventricular ejection fraction (EF): subgroup I with EF < or = 25% (n = 10), subgroup II with 25% < EF < or = 50% (n = 17) and subgroup III with EF > 50% (n = 13). Velocity distributions in the three subgroups were compared to each other.
(1) The velocity distribution in the left ventricular outflow tract was skewed with the highest velocities and TVIs along the anterior wall and septum. The skewness of the velocity distribution was more pronounced in the apical long axis view than in the four chamber view (P < 0.05). The extent of skewness of the TVI profile was positively correlated to the left ventricular EF both in the long axis view (r = 0.63; P < 0.001) and in the four chamber view (r = 0.57; P < 0.001). (2) Pulsed Doppler sampling from different regions along the diameter produced different TVIs, and therefore yielded significantly different calculated aortic valve areas, especially in subgroup III. Due to the skewness of the velocity distribution in the left ventricular outflow tract, location of the pulsed Doppler sample volume significantly affects the accuracy of aortic valve area calculation by using the continuity equation, especially in patients with relatively high left ventricular EF. In patients with low EF, selection of pulsed Doppler sampling site is less important.
对40例瓣膜性主动脉狭窄患者的左心室流出道横断面速度分布进行了研究。采用多普勒彩色血流图和时间插值法构建不同水平的横断面速度和时间速度积分（TVI）曲线。在心尖长轴视图中，通过脉冲多普勒从左心室流出道直径方向的前、中、后区域（主动脉瓣环近端0.5至1.0 cm处）采集主动脉下流速。因此，对于每位患者，使用连续性方程计算三个主动脉瓣面积。根据左心室射血分数（EF）将每位患者分为三个亚组之一：亚组I，EF≤25%（n = 10）；亚组II，25%＜EF≤50%（n = 17）；亚组III，EF＞50%（n = 13）。比较了三个亚组的速度分布。
（1）左心室流出道的速度分布呈偏态，前壁和室间隔处速度和TVI最高。速度分布的偏态在心尖长轴视图中比在四腔视图中更明显（P＜0.05）。TVI曲线的偏态程度在长轴视图（r = 0.63；P＜0.001）和四腔视图（r = 0.57；P＜0.001）中均与左心室EF呈正相关。（2）沿直径从不同区域进行脉冲多普勒采样产生不同的TVI，因此得出的计算主动脉瓣面积显著不同，尤其是在亚组III中。由于左心室流出道速度分布的偏态，脉冲多普勒采样容积的位置显著影响使用连续性方程计算主动脉瓣面积的准确性，尤其是在左心室EF相对较高的患者中。在EF较低的患者中，脉冲多普勒采样部位的选择不太重要。
