Kametas N A, McAuliffe F, Cook B, Nicolaides K H, Chambers J
Harris Birthright Research Centre for Fetal Medicine, King's College Hospital, London, UK.
Ultrasound Obstet Gynecol. 2001 Nov;18(5):467-74. doi: 10.1046/j.0960-7692.2001.00574.x.
Circumferential fiber shortening has been the dominant basis for conventional analysis by echocardiography of left ventricular systolic function during pregnancy. Results in the literature have been conflicting due mainly to the fact that geometric assumptions for the calculation of these indices are made that may not be valid due to changes in left ventricular shape during pregnancy. Left ventricular long-axis displacement is expected to be a useful index of systolic function, independent of the changes in left ventricular geometry. The aim of this study was to compare circumferential to long-axis shortening during left ventricular contraction in pregnant women.
This was a cross-sectional study of 125 pregnant women at 9-42 weeks of gestation and 19 non-pregnant female controls. Two-dimensional and M-mode echocardiography of the left ventricle was performed including measurement of left ventricular long-axis displacement and activation time on the lateral, septal, anterior and inferior sides of the mitral annulus. Activation time was assessed as the time from the start of the Q-wave of the electrocardiogram to the onset of left ventricular long-axis shortening.
Mean arterial pressure and activation time decreased during pregnancy, reaching a nadir at about 19 weeks' gestational age of 4% and 13%, respectively, below non-pregnant values; they subsequently increased towards term. Left ventricular long-axis displacement mirrored the changes in mean arterial pressure and activation time and increased with gestational age at all four sites of the atrioventricular plane reaching a peak at about 23 weeks (+ 12% compared to non-pregnant levels). The ejection fraction and fractional shortening remained stable until 30 and 32 weeks, respectively, and then decreased towards term.
Changes in left ventricular long-axis performance during pregnancy occur earlier than do measures of transverse function.
圆周纤维缩短一直是孕期超声心动图对左心室收缩功能进行传统分析的主要依据。文献中的结果相互矛盾，主要原因是在计算这些指标时所做的几何假设可能因孕期左心室形状的改变而无效。左心室长轴位移有望成为一个有用的收缩功能指标，不受左心室几何形状变化的影响。本研究的目的是比较孕妇左心室收缩期间圆周缩短与长轴缩短情况。
这是一项对125名妊娠9至42周的孕妇和19名非妊娠女性对照者进行的横断面研究。对左心室进行二维和M型超声心动图检查，包括测量左心室长轴位移以及二尖瓣环外侧、间隔、前侧和下侧的激活时间。激活时间评估为从心电图Q波开始到左心室长轴缩短开始的时间。
孕期平均动脉压和激活时间降低，在妊娠约19周时分别降至最低点，比非妊娠值低4%和13%；随后在足月时升高。左心室长轴位移反映了平均动脉压和激活时间的变化，并在房室平面的所有四个部位随孕周增加，在约23周时达到峰值（与非妊娠水平相比增加12%）。射血分数和缩短分数分别在30周和32周之前保持稳定，然后在足月时下降。
孕期左心室长轴功能的变化比横向功能指标的变化更早出现。
