Rasanen J, Huhta J C, Weiner S, Wood D C, Ludomirski A
Department of Obstetrics and Gynecology, Pennsylvania Hospital, Philadelphia 19107, USA.
Am J Obstet Gynecol. 1996 May;174(5):1441-9. doi: 10.1016/s0002-9378(96)70586-0.
Our purpose was to establish normal physiologic parameters in the fetal proximal and distal branch pulmonary arterial vascular impedance during the second half of pregnancy and to analyze relationships between proximal and distal pulmonary arterial blood velocity waveforms.
In this cross-sectional study 100 uncomplicated singleton pregnancies were studied by pulsed color Doppler techniques between 18 and 41 weeks of gestation (median 30 weeks). Both right and left proximal (immediately after the bifurcation of the main pulmonary artery) and distal (beyond the first bifurcation of the branch pulmonary artery) pulmonary artery blood velocity waveforms were recorded and pulsatility index values were calculated. Peak systolic velocities and time-to-peak-velocity intervals were measured. Time-to-peak-velocity intervals were also analyzed at the level of aortic and pulmonary valves and at the ductus arteriosus. Right and left pulmonary artery diameters and right lung length were measured.
In both right and left proximal and distal pulmonary arteries pulsatility index values decreased (p < 0.0001) and the peak systolic velocities (p < 0.003) and time-to-peak-velocity intervals (p < 0.0001) increased during the second half of pregnancy. In the proximal pulmonary arteries the pulsatility index values decreased linearly until 34 to 35 weeks of gestation and in the distal pulmonary arteries until 31 weeks of gestation. Thereafter they remained unchanged. In pulmonary arteries time-to-peak-velocity intervals were shorter (p < 0.01) than at the pulmonary valve level. There were no significant differences between the right or left pulmonary arteries in the pulsatility index values, peak systolic velocities, time-to-peak-velocity intervals, or pulmonary artery diameters. In the proximal pulmonary arteries the pulsatility index values (p < 0.02) and peak systolic velocities (p < 0.0001) were higher and time-to-peak-velocity intervals (p < 0.0001) were longer than in the distal pulmonary arteries. There was a 2.5-fold increase in pulmonary artery diameters and right lung length.
Fetal branch pulmonary arterial vascular impedance decreases significantly during the second half of pregnancy. The linear decrease in vascular impedance during the second trimester and in the beginning of the third trimester may be related to the growth of the lung and the increase in the number of resistance vessels. During the latter part of the third trimester pulmonary vascular impedance does not decrease further.
我们的目的是建立妊娠后半期胎儿近端和远端分支肺动脉血管阻抗的正常生理参数，并分析近端和远端肺动脉血流速度波形之间的关系。
在这项横断面研究中，采用脉冲彩色多普勒技术对100例单胎妊娠无并发症孕妇进行了研究，妊娠周数为18至41周（中位数为30周）。记录了左右近端（主肺动脉分叉后即刻）和远端（分支肺动脉第一次分叉后）肺动脉的血流速度波形，并计算搏动指数值。测量了收缩期峰值速度和达峰时间间隔。还在主动脉瓣、肺动脉瓣和动脉导管水平分析了达峰时间间隔。测量了左右肺动脉直径和右肺长度。
妊娠后半期，左右近端和远端肺动脉的搏动指数值均下降（p<0.0001），收缩期峰值速度（p<0.003）和达峰时间间隔增加（p<0.0001）。在近端肺动脉中，搏动指数值在妊娠34至35周前呈线性下降，在远端肺动脉中，在妊娠31周前呈线性下降。此后它们保持不变。肺动脉的达峰时间间隔比肺动脉瓣水平短（p<0.01）。左右肺动脉在搏动指数值、收缩期峰值速度、达峰时间间隔或肺动脉直径方面无显著差异。近端肺动脉的搏动指数值（p<0.02）和收缩期峰值速度（p<0.0001）高于远端肺动脉，达峰时间间隔（p<0.0001）长于远端肺动脉。肺动脉直径和右肺长度增加了2.5倍。
妊娠后半期胎儿分支肺动脉血管阻抗显著降低。妊娠中期和妊娠晚期开始时血管阻抗的线性下降可能与肺的生长和阻力血管数量的增加有关。在妊娠晚期，肺血管阻抗不再进一步下降。
