| Adult pulmonary vein blood flow waveforms can be used to estimate left ventricular diastolic function. Fetal circulating system is different from adults’. Fetal lung has no respiratory function and is in collapsed state, which provide blood flow spectrum of pulmonary vein of fetal lung with favorable acoustic window. The blood flow spectrum of pulmonary vein could be obtained easily and pulmonary vein has no valve and connects left atrium directly, therefore, pulmonary venous flow is mainly influenced by left arterial pressure. Fetal pulmonary vein blood flow spectrum will get changed when fetal cardiac structure or function is abnormal. Based on the statistics data, the high incidence of congenital heart diseases is about7‰～8‰in neonates.80%of dead babies have cardiac deformity and one third of them have serious cardiac deformity. The research is to analyze the value of pulmonary veins blood flow spectrum in diagnosing fetal cardiac defect.208fetuses were recruited from these who came to our hospital for pregnancy examination. These fetuses were between22and38weeks. They were divided into2groups:the normal group includes146fetuses with normal heart, the abnormal group includes62fetuses with abnormal heart (8fetuses with arrhythmia and54fetuses with abnormal structure of heart). The E8Ultrasonoscope with RAB-4-8-D Volume of convex array probe (1.91-7.77MHz),4C-D convex array probe (1.5-4.6MHz), M6C Plane array probe (2.6-7.77MHz) were used to examine fetal heart. Echocardiographic examination condition was used and the picture was adjusted to the best condition. The pregnant women were lying horizontally or on the side. Firstly, examine the fetal structure and estimate gestational weeks. According to fetal head and spine, we can decide the position of the baby. Then, fetal echocardiographic examination condition was used to evaluate the structure and function of the fetal heart comprehensively. These views were used such as the fetal abdomen horizontal view, four chamber view, left and right outflowtract view, three blood vessel trachea view, short axis views of left ventricles, short axes section of large arteries, aortic arch and ductus arteriosus arch view, superior and inferiorvena cava long axis view and other nonstandard views.Then, the probe was moved to fetal head after the four chamber view was showed, then slow down the speed scale to about15cm/s. The bilateral pulmonary veins drainaging into the left atrium was visualized with color doppler flow imaging. Keeping the angle between the sample line and blood flow less than20, sample volume was between1and3millimetres. When appearing more than3continuous and complete flow spectrums, we took the measure of peak systolic velocity(S), peak diastolic velocity(D), end diastolic velocity (A) of left and right pulmonary veins at the hilum of the lung. We measured these parameters3times, then took the average. S/D, S/A, and (S-A)/D were calculated. These parameters were compared between the two groups.SPSS17.0statistical software was used. The data of pulmonary venous flow velocity was expressed as mean±SD. The t-test was applied in the intergroup comparison. P-value less than0.005was considered statistically significant. The flow velocity of left and right pulmonary venous were compared by a paired t-test. Relevance between the parameters of S, D, A, S/D, S/A,(S-A)/D and gestational ages were analysed by linear correlation analysis. The results showed as followsAll of the146fetal pulmonary vein blood spectrums contain S, D, A. There is a positive correlation between S, D, A and gestational ages. S/D, S/A,(S-A)/D have no significant effect on gestational age. The pattern left and right pulmonary vein blood spectrums were similar and most of them S/D are greater than1, a small number of them S/D are less than1, rare of them S/D are equal to1.In the abnormal group,16fetal pulmonary veins spectrum morphology changed:5fetuses with A wave absent,9fetuses with A wave reversed, The spectrum of vertical vein was similar to vena cava’s in one fetus, one fetal the spectrum form was similar to sine wave, and8fetuses with atrial ectopics were recognised by an early A wave disrupting the regular A-A timing. A larger amplitude S wave can be seen after the earlier A wave.Use t-test to analyse the parameters of pulmonary vein blood flow between normal fetuses and38abnormal fetuses with forward A wave.(S-A)/D was significantly different between them(P<0.05). Other parameters has no statistic significance (P>0.05).Echocardiography indicated that one fetus had coarctation of aorta, and its pulmonary vein blood flow spectrum A wave was reverse. After postpartum, echocardiography coarctation of aorta was proved. Echocardiography indicated that two fetal aortic arches inter diameters were small, and the speed was high. After postpartum, there were no obvious anomaly in aortic arches.In conclusion, The normal fetal bilateral pulmonary vein blood flow spectrums are similar. It contains S, D, A. There is positive correlation between S, D, A and gestational ages. There is positive correlation between S wave, D wave, A wave and gestational age, and S/D, S/A,(S-A)/D have no significant effect on gestational ages. When A wave of fetal pulmonary vein blood flow spectrum is missing or reverse, fetal cardiac abnormalities should be considered under the condition of excluding maternal factors. We suggest them to do fetal echocardiographic examination further. Pulmonary vein blood flow spectrum can also be used for evaluation of fetal arrhythmia. When fetal pulmonary vein blood spectrum morphology changes, we should consider whether it has anomalous pulmonary venous connection.(S-A)/D can be used as a high-risk indicaors. While it is abnormal, we suggest them to do fetal echocardiographic examination which can exclude fetal cardiac abnormalities. Pulmonary vein blood spectrum has implications for assessing prognosis. Measuring fetal pulmonary venous flow should be used as a routine examination. |
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