Geva T, Mauer M B, Striker L, Kirshon B, Pivarnik J M
Section of Pediatric Cardiology, Texas Children's Hospital, USA.
Am Heart J. 1997 Jan;133(1):53-9. doi: 10.1016/s0002-8703(97)70247-3.
Left ventricular (LV) adaptation to the hemodynamic load of pregnancy has been studied with load-sensitive ejection-phase indexes, but the results of these studies are conflicting. The aim of this study was to examine the effects of the hemodynamic load of pregnancy on the contractile state of the left ventricle by using load-adjusted indexes of contractility. Thirty-four healthy women were prospectively studied by serial echo and Doppler examinations at six periods during pregnancy and after delivery. LV volume increased 10.5%, paralleling the change in stroke volume. End-systolic stress, an index of myocardial afterload, decreased 28.8% because of a decrease in end-systolic pressure and an increase in LV thickness/diameter ratio. Despite the increase in preload and the decrease in afterload, ejection phase indexes did not change during or after pregnancy. Although remaining within the normal range, the afterload-adjusted velocity of circumferential fiber shortening, an index of contractility that is relatively insensitive to preload, transiently decreased by 1.75 SDs during gestation, returning to non-pregnant values 2 to 4 weeks postpartum. Thus the increase in hemodynamic load that characterizes normal pregnancy is associated with preservation of global pump function. The transient decrease in contractile state may represent an adaptation phase of the contractile elements of the myocardium to the rapid changes in loading conditions observed during the first trimester of pregnancy.
左心室（LV）对妊娠血流动力学负荷的适应性已通过负荷敏感的射血期指标进行了研究，但这些研究结果相互矛盾。本研究的目的是通过使用负荷调整后的收缩性指标来研究妊娠血流动力学负荷对左心室收缩状态的影响。对34名健康女性在孕期的六个阶段及产后进行了前瞻性的系列超声心动图和多普勒检查。左心室容积增加了10.5%，与每搏输出量的变化平行。心肌后负荷指标——收缩末期应力，由于收缩末期压力降低和左心室厚度/直径比增加而下降了28.8%。尽管前负荷增加而后负荷降低，但射血期指标在孕期或产后并未改变。虽然仍在正常范围内，但相对前负荷不敏感的收缩性指标——后负荷调整后的圆周纤维缩短速度，在妊娠期短暂下降了1.75个标准差，产后2至4周恢复到非妊娠时的值。因此，正常妊娠所特有的血流动力学负荷增加与整体泵功能的维持有关。收缩状态的短暂下降可能代表心肌收缩成分对妊娠早期观察到的负荷条件快速变化的适应阶段。
