Study On Fetal Cardiac Hemodynamic Changes And Chromosomal Abnormalities In Early Pregnancy With Transvaginal Ultrasonography

Most of the complex congenital heart diseases can be diagnosis prenatally by transabdominal fetal echocardiography in the second and third trimester. But intervention carried out in this period cause relatively great injury to the pregnant women. So, an earlier non-invasive diagnostic method is important. The development of cardiovascular system includes morphogenesis,growth and hemodynamic changes. The abnormal hemodynamic changes usually relate to abnormal cardiac development. Abnormal signals of blood flow had been found in abnormal embryonic mouse heart by using Doppler echocardiography; and abnormal fetal heart rate was associated with fetal chromosomal abnormalities in early studies. So we suspect that the abnormal fetal cardiac hemodynamic changes perhaps may be due to cardiac malformations and chromosomal abnormalities. Screening significant cardiac blood flow signals can provide valuable clues to the early diagnosis. In recent years, high-frequency transvaginal ultrasound with high resolution has been implemented in prenatal diagnosis of fetal congenital abnormalities. Clinical experiences demonstrated its high resolution and safety to the pregnant women. In the present study we used a combination of transvaginal real-time with pulsed Doppler system(6～9MHz) to study gestational age-related hemodynamic changes in normal fetal heart blood flow in the first trimester and to learn the relationship between these abnormal changes in fetal heart blood flow and chromosomal or cardiac structural abnormalities; Fetal nuchal translucency of 10-14 weeks gestational age and chromosomal or cardiac structural abnormalities in fetus with increased nuchal translucency thickness were studied to explore a simple and efficient method in the earlier prenatal diagnosis.1. Transvaginal ultrasonography of fetal cardiac hemodynamic changes in the first trimester 172 fetuses of first-trimester healthy pregnant women of less than 35 years of age, with regular menstrual period, without high risk factors for fetal cardiac andkaryotypic abnormalities were studied as normal sample. The following indexes were recorded: (1) blood flow wave and its changes; (2) blood flow velocity, e/a ratio was measured when inlet tract wave appeared; (3) heart rate; (4) isovolumetric contraction time; (5) isovolumetric relaxation time; (6) ejection time; (7) filling time. Fetal cardiac hemodynamic changes demonstrated that: (1) Before 6 weeks of gestational age, Doppler signal produced by primitive heart beat showed as simple wave; From 7 gestational weeks on, the blood flow of in-and-out flow tract-velocity was opposite , the inflow tract velocity was ( 'a' wave); The inflow tract-velocity changed from monophasic to biphasic in 9 weeks of gestational age.,'e'wave appeared, the appearance rate of monophasic wave increased with gestational age; (2) 'e'wave increased significantly with gestational age (r=0.50, p<0.05), there was less increase in 'a' wave after 8 weeks of gestational age(r=0.09, p>0.05), increasing of e/a ratio with the gestational age was due to the improvement of heart compliance, the increase of 'e' wave was responsible for the increase of e/a ratio ; (3) The outflow tract velocities increased significantly with gestational age (r=0.43, p<0.05); (4) The fetal heart rate increased with gestational age (r=0.65,p<0.05) before 10 gestational weeks, and gradually decreased thereafter; (5) .The changes of cardiac isovolumetric contraction time (ICT) and isovolumetric relaxation time (IRT) as expressed as percentage of total cardiac time decreased closely with gestational age.(r=－0.73,－0.58, respectively, p<0.05) , while the decrease of ICT was more significant; (6) High-frequency recordings or clicks corresponding to the opening or closing of the semilunar and atrioventricular valves can be clearly seen in 9～10 weeks of gestations.2. Study on the abnormal hemodynamic changes of fetal heart with transvaginal doppler ultrasound and the relationship with fetal katyotapes and cardiac microdissection1022 ran...