Fetal heart rate and umbilical artery velocity variability in pregnancies complicated by insulin-dependent diabetes mellitus.

OBJECTIVES: To examine the variability in fetal heart rate and absolute flow velocity, which are possible hemodynamic markers of cardiovascular homeostasis in pregnancies complicated by diabetes mellitus. METHODS: Doppler studies of umbilical artery velocity waveforms were performed at 12-21 weeks of gestation in 16 women with well-controlled type I (insulin-dependent) diabetes mellitus. From umbilical artery velocity waveforms of at least 13 s in duration, we determined absolute values and beat-to-beat variability for fetal heart rate and umbilical artery flow velocities and compared these findings with normal controls matched for gestational age. RESULTS: Fetuses of diabetic women displayed increased fetal heart rate variability and umbilical artery peak systolic velocity. Fetal heart rate, umbilical artery time-averaged velocity and variability in umbilical artery flow velocity were not essentially different between the two groups. CONCLUSION: Fetal heart rate variability and umbilical artery peak systolic velocity may be markers for fetal cardiovascular homeostasis in pregnancies complicated by insulin-dependent diabetes mellitus.     

Assessment of fetal heart rate variability and velocity variability by Doppler velocimetry of the descending aorta at 10-20 weeks of gestation.

OBJECTIVES: Determination of gestational age-related modulations in fetal heart rate and descending aorta blood flow velocity in the early human fetus and comparison of aortic variability data with data obtained from the umbilical artery. It is hypothesized that these modulations present in the umbilical artery also occur in the descending aorta. METHODS: Doppler studies of descending aorta velocity waveforms were performed at 10-20 weeks in 55 normal pregnant women. In 24 of the 55 women, Doppler recordings from both the descending aorta and the umbilical artery were collected. Absolute values and variability of fetal heart rate, peak systolic and time-averaged velocities were determined from flow velocity waveforms of at least 18 s in duration. RESULTS: From 10 to 20 weeks of gestation, the descending aorta peak systolic and time-averaged velocities increased, whereas the fetal heart rate decreased. The descending aorta peak systolic variability also increased. However, the time-averaged velocity variability and fetal heart rate variability remained constant during the study period. In the subset of 24 women, the fetal heart rate variability and velocity variability data from the descending aorta and umbilical artery were not significantly different. CONCLUSIONS: Reproducible fetal heart rate and velocity variability data can be derived from the descending aorta and umbilical artery. The increase in heart rate variability observed in the umbilical artery was not seen in recordings obtained from the descending aorta. Different fetal activity states may be the underlying mechanism for these heart rate variability discrepancies.     

Do heart rate and velocity variability derived from umbilical artery velocity waveforms change prior to clinical pregnancy-induced hypertension?

OBJECTIVE: To investigate the hypothesis that alterations in heart rate variability, peak systolic velocity variability and time-averaged velocity variability in the human umbilical artery may predict early signs of dysfunctional fetal-placental coupling in pregnancies that later develop pregnancy-induced hypertension. METHODS: Doppler flow velocity recordings from the umbilical artery were performed at 10-20 weeks of gestation in 12 nulliparous women who subsequently developed pregnancy-induced hypertension. From umbilical artery velocity waveforms of at least 12 s in duration we determined absolute values and beat-to-beat variability in fetal heart rate, peak systolic and time-averaged velocity and compared these findings with those in normal nulliparous pregnant women matched for gestational age. RESULTS: Absolute values for fetal heart rate, peak systolic and time-averaged velocity as well as beat-to-beat variability in fetal heart rate did not differ significantly between women later developing pregnancy-induced hypertension and normal controls. However, variability in peak systolic velocity and time-averaged velocity were decreased in women who subsequently developed pregnancy-induced hypertension. CONCLUSIONS: Whereas fetal heart rate variability was similar, umbilical artery flow velocity variability was reduced in women developing pregnancy-induced hypertension compared with controls. It is proposed from this study that variability of the umbilical artery flow velocity is associated with mechanical changes in the vascular bed of women who later develop pregnancy-induced hypertension.     

Impact of congenital heart disease on cerebrovascular blood flow dynamics in the fetus.

OBJECTIVES: Neurological abnormalities are present in some children after repair of congenital heart disease (CHD). Recently, structural brain abnormalities have been identified in infants prior to cardiac surgery. By altering in utero blood flow patterns, the type of CHD may impact upon cerebrovascular flow dynamics prior to birth. We sought to determine whether left- and right-sided obstructive congenital heart lesions modify cerebrovascular flow dynamics in the fetus. METHODS: Pulsed Doppler was used to measure blood flow velocities in the umbilical (UA) and middle cerebral (MCA) arteries in 172 fetuses from 20 to 39 weeks' gestational age referred for fetal echocardiography. Pulsatility index (PI), an indicator of downstream vascular resistance, was determined by (peak systolic velocity--end-diastolic velocity)/mean velocity. RESULTS: Fetuses with hypoplastic left heart syndrome (HLHS; n = 28) had decreased MCA-PI (P = 0.009) compared to normal fetuses (n = 114). Fetuses with right-sided obstructive lesions (RSOL; n = 17) had increased MCA-PI (P = 0.001) when compared to fetuses with HLHS. The UA-PI was elevated in fetuses with RSOLs (P = 0.045). CONCLUSIONS: Cerebrovascular resistance is lower than normal in fetuses with HLHS, a condition in which cerebral perfusion occurs retrograde via the ductus arteriosus. Fetuses with RSOL had significantly higher cerebrovascular resistance compared to fetuses with HLHS. The type of CHD impacts upon fetal cerebrovascular blood flow distribution and this may have implications for later development of neurological sequelae.     

Coronary artery blood flow velocities in various fetal conditions.

OBJECTIVE: To determine fetal coronary artery peak blood flow velocities in normal and high-risk pregnancies. METHODS: Coronary artery peak systolic and diastolic blood flow velocities were measured by pulsed-wave Doppler velocimetry after identification of the coronary arteries by color Doppler imaging. Peak blood velocities obtained from normal pregnancies were related to gestational age using linear regression analysis. Blood flow velocities in normal fetuses were compared to measurements obtained in various fetal conditions. RESULTS: In normal fetuses coronary artery blood flow was visualized at a median gestational age of 33 + 6 weeks; median systolic and diastolic peak blood flow velocities were 0.21 and 0.43 m/s, respectively, and showed no significant change with gestational age. In growth-restricted fetuses coronary artery blood flow was visualized significantly earlier in gestation (median 28 + 2 weeks); systolic and diastolic peak blood flow velocities were higher at 0.25 and 0.48 m/s, respectively (P < 0.05). The highest coronary blood flow velocities were observed with fetal anemia. Coronary artery blood flow was also measured in fetuses with ductus arteriosus constriction due to indomethacin. Velocities did not differ from normal fetuses. Both in fetal anemia and ductus arteriosus constriction coronary artery blood flow could no longer be visualized with resolution of the underlying condition. CONCLUSION: Examination of coronary artery blood flow dynamics in the human fetus demonstrates acute increases in diastolic velocities in severe anemia and ductus arteriosus constriction based on the severity of the condition. In fetuses with growth restriction increased coronary blood flow velocities can be appreciated throughout the cardiac cycle. Clinical correlation in the interpretation of coronary blood flow dynamics in the human fetus is essential.     

Fetal heart rate and blood flow velocity variability in the presence of increased nuchal translucency: a preliminary study.

OBJECTIVE: To study the power spectrum distribution of heart rate and umbilical artery flow velocity variability in fetuses with increased nuchal translucency thickness (NT). METHODS: Doppler velocity waveforms were collected from long-lasting (>20 s) umbilical artery recordings in 18 fetuses with increased NT (>3 mm) and 18 normal controls matched for gestational age at 11-14 (median, 12) weeks. The NT group included 11 abnormal karyotypes: trisomy 18 (n = 3), 45,X (n = 4), trisomy 21 (n = 3) and a balanced translocation. Absolute heart rate as well as the coefficient of variation for both beat-to-beat heart rate variability and umbilical artery blood flow velocity variability were determined. The ratios of the integrated low-frequency components (0.05-0.2 Hz) and the integrated high-frequency ones (0.25-1.6 Hz; LH ratio) from normalized power spectrum distributions were established to reflect sympathovagal balance. RESULTS: The mean heart rate was not significantly different between the two groups. However, mean heart rate variability and time-averaged flow velocity variability were significantly increased in the NT group, while there was no significant difference in the LH ratios between the two groups. The mean umbilical artery pulsatility index was significantly higher in the NT group. CONCLUSION: The autonomic nervous system does not seem to play a role in the altered cardiovascular homeostasis in the presence of increased fetal NT.     

Fetal heart rate and umbilical artery flow velocity variability in intrauterine growth restriction: a matched controlled study.

OBJECTIVES: To study heart rate and umbilical artery blood flow velocity variability in growth-restricted fetuses and investigate the influence of the autonomic nervous system on these parameters. METHODS: Doppler velocity waveforms were collected from long-lasting umbilical artery recordings in 15 fetuses with growth restriction and 15 normal age-matched controls at 23-35 weeks of gestation. Absolute heart rate and umbilical artery blood flow velocity as well as the coefficient of variation were determined. Using power spectral analysis the low- and high-frequency bands of heart rate variability and blood flow velocity variability were calculated. The low-to-high (LH) ratio of heart rate variability and blood flow velocity variability were examined as a measure of sympathovagal balance. RESULTS: In growth-restricted fetuses umbilical artery velocities were significantly reduced. Heart rate variability was significantly reduced in the presence of growth restriction, but no significant difference was demonstrated for blood flow velocity variability. The LH ratio for heart rate variability was significantly decreased in growth restriction, but no difference in LH ratio was demonstrated for blood flow velocity variability. CONCLUSION: Flow velocity variability in growth restriction seems not to be predominantly influenced by the autonomic nervous system, whereas the decreased heart rate variability seems to be influenced by altered sympathetic-parasympathetic balance.     

Modulation of middle cerebral artery flow velocity waveforms by breathing movements in the normal term fetus

Breathing dependency of fetal middle cerebral artery flow velocities was studied in 10 normal pregnancies at term. Peak systolic, end-diastolic and time-averaged flow velocities and pulsatility index during fetal breathing were not significantly different from those observed during apnoea. However, the standard deviation for each flow velocity parameter was significantly increased during fetal breathing activity, indicating marked modulation of middle cerebral artery velocities.     

Fetal brain/liver volume ratio and umbilical volume flow parameters relative to normal and abnormal human development.

OBJECTIVES: To estimate fetal brain volume from head circumference and published postmortem data; to determine normal values for the fetal brain/liver volume ratio relative to gestational age; to establish the relationship between the brain/liver volume ratio and fetal circulatory parameters during normal and restricted (SGA) fetal growth. PATIENTS AND METHOD: This was a cross-sectional study involving a total of 47 uncomplicated pregnancies appropriate-for-gestational age (AGA) and 23 pregnancies resulting in the delivery of a SGA fetus. At enrollment gestational age ranged between 20 and 36 weeks in both groups. Umbilical venous cross-sectional area and time-averaged velocity for calculation of volume flow as well as velocity waveforms from the umbilical artery, middle cerebral artery and ductus venosus, were recorded. Fetal liver volume measurements were obtained using three-dimensional ultrasound. Fetal brain volume was estimated from fetal head volume following comparison with published postmortem data on fetal brain weight. RESULTS: A significant correlation was observed between prenatally estimated fetal head volume and postmortem fetal brain volume. Fetal brain volume was approximately half that of fetal head volume. The normal fetal brain/liver volume ratio demonstrated a significant reduction with gestational age (R = -0.54; P < 0.001). The normal mean +/- standard deviation (SD) fetal brain/liver volume ratio (3.4 +/- 0.7) was significantly different (P < 0.001) from the mean fetal brain/liver volume ratio in the SGA group (n = 23) (5.9 +/- 1.9). A significant difference existed for mean umbilical venous volume flow between AGA (104.7 +/- 26.9 mL/min/kg) and SGA (59.6 +/- 22.7 mL/min/kg) fetuses. In the SGA fetus, there was a significant inverse relationship (P < 0.001) between fetal weight-related umbilical venous volume flow and fetal brain/liver volume ratio. In a subset of 16 SGA and 16 AGA fetuses matched for gestational age, a significant difference existed for umbilical artery pulsatility index (2.30 +/- 1.52 vs. 0.99 +/- 0.19), fetal middle cerebral artery pulsatility index (1.3 +/- 0.4 vs. 2.1 +/- 0.3) and late diastolic flow velocity in the fetal ductus venosus (6.9 +/- 14.2 cm/s vs. 23.9 +/- 8.8 cm/s), but not for peak systolic, early diastolic and time-averaged velocity in the ductus venosus. CONCLUSION: Sonographic estimates of fetal brain volume can be obtained. The fetal brain/liver volume ratio is a predictor of fetal outcome in the growth-restricted fetus. An inverse relationship exists in SGA fetuses between brain/liver volume ratio and fetal weight-related umbilical venous blood flow.     

Doppler-derived umbilical artery absolute velocities and their relationship to fetoplacental volume blood flow: a longitudinal study.

OBJECTIVES: To construct reference ranges for serial measurements of the umbilical artery (UA) absolute blood flow velocities in the second half of pregnancy and to test the hypothesis that significant associations exist between UA velocities and placental volume blood flow assessed from umbilical vein blood flow velocities and diameter. METHODS: This was a prospective longitudinal study of the umbilical circulation. UA absolute velocities and umbilical vein blood flow were measured at 4-weekly intervals between 19 and 42 weeks' gestation in 130 low-risk singleton pregnancies. A total of 511 observations were used to construct the reference ranges and assess the association between UA absolute velocities and placental volume flow using multilevel modeling. RESULTS: Both UA absolute velocities and placental volume blood flow showed a steady increase throughout the second half of pregnancy. However, the gestational age-related increase in the UA end-diastolic velocity (EDV) was greater than the corresponding increase in the peak systolic velocity (PSV). The time-averaged intensity-weighted mean velocity (TAWMV)/time-averaged maximum velocity (TAMXV) was 0.6 indicating probably not a completely parabolic velocity profile. There was a significant positive association (P < 0.00001) between UA absolute velocities and placental volume blood flow, but this association was modified by the gestational age. The intraobserver coefficients of variation for the UA PSV, EDV, TAMXV and TAWMV and placental volume blood flow were 10.17%, 16.29%, 11.46%, 18.18% and 8.61%, respectively. CONCLUSION: We have established new reference ranges for the UA absolute velocities based on longitudinal data. They show a significant association with fetoplacental volume blood flow and may have a clinical value in the assessment of the umbilical circulation.     

Fetal adrenal artery velocimetry measurements in appropriate-for-gestational age and intrauterine growth-restricted fetuses.

OBJECTIVE: To investigate adrenal artery blood flow in the fetus. DESIGN AND METHOD: Sixty-two appropriate-for-gestational-age (AGA) and 20 intrauterine growth-restricted (IUGR) fetuses were recruited to this cross-sectional study between 22 and 42 weeks of pregnancy in a tertiary referral fetal medicine unit of a university hospital. ENDPOINTS: Doppler velocimetry of the fetal adrenal, umbilical (UA), renal and middle cerebral arteries (MCA). Pulsatility index (PI), resistance index (RI), peak systolic velocity (PSV), time-averaged maximum velocity (TAMXV) and cerebroplacental ratio (MCA RI/UA RI; CPR). Obstetric outcome. RESULTS: The adrenal artery was detected in 82% of the fetuses. All flow velocity waveforms obtained from the adrenal artery indicated low impedance blood flow. No significant changes in PI, RI, PSV and TAMXV occurred with advancing gestation. The blood flow parameters of the adrenal artery did not differ between AGA and IUGR fetuses. In five IUGR fetuses with signs of redistribution of cardiac output in favor of the brain, the adrenal artery velocimetry results were unremarkable. The adrenal artery PI, RI, PSV and TAMXV values were higher in female fetuses than in male fetuses (P < 0.05). A relationship was observed between the velocity measurements and the estimated fetal weight (P < 0.01). CONCLUSIONS: The fetal adrenal artery could be readily detected. We observed no redistribution of blood flow in favor of the fetal adrenals in IUGR fetuses which were not severely compromised.     

Umbilical venous volume flow and fetal behavioral states in the normally developing fetus.

OBJECTIVE: To determine the relationship between umbilical venous (UV) volume flow and fetal behavioral states 1F (quiet sleep) and 2F (active sleep) in normal pregnancies at 36-40 weeks of gestation. METHODS: Fetal behavioral states were established in 17 normal pregnancies by means of combined assessment of fetal heart rate patterns (FHRP), and fetal eye and body movements. UV vessel area (mm(2)) as obtained by tracing the inner vessel area using Labview and Imaq Vision software and UV time-averaged flow velocity (mm/s Doppler) were multiplied to calculate UV volume flow (mL/min) including flow/kg fetus. The pulsatility index (PI) in the umbilical artery was also determined. In each woman, all parameters were measured between three and five times in each behavioral state. Data are reported as mean +/- 1 SD and analyzed by paired t-test. RESULTS: No statistically significant behavioral-state-related changes were observed for UV time-averaged velocity and UV volume flow, resulting in UV volume flow/kg fetus of 69.1 +/- 14.9 mL/min*kg at 1F and 71.6 +/- 12.1 mL/min*kg at 2F (not significant). A statistically significant increase (P = 0.02) was established for UV cross-sectional area (46.4 +/- 8.6 mm(2) vs. 49.0 +/- 10.1 mm(2)) and for fetal heart rate (FHR) from 134.2 +/- 10.3 bpm in 1F to 144.2 +/- 7 bpm in 2F. Umbilical artery PI was not significantly different between the two behavioral states. CONCLUSIONS: On the basis of high venous vessel wall compliance, the significant increase in UV cross-sectional area during fetal behavioral state 2F may be determined by a rise in mean venous pressure. The significant rise in FHR may reflect increased fetal cardiac output during state 2F while the resistance at the hepato-ductal pathway remains relatively constant with the purpose of meeting raised energy demands during the active sleep state. This is further supported by the observed trend towards an increase in UV volume flow.     

Serial sonographic findings of four fetuses with homozygous alpha-thalassemia-1 from 21 weeks onwards.

OBJECTIVES: To evaluate the potential usefulness of noninvasive ultrasound assessment of fetal anemia in the diagnosis and management of fetuses with homozygous alpha-thalassemia-1. METHODS: We describe four pregnancies complicated by fetal homozygous alpha-thalassemia-1. They presented with ultrasound abnormalities before the development of hydrops. As part of evaluating the fetal condition, we performed ultrasound and Doppler studies aimed at identifying fetal anemia. These studies included evaluation of intrahepatic umbilical venous maximum flow velocity, middle cerebral artery peak flow velocity, fetal liver length and spleen perimeter. RESULTS: In all four fetuses, ultrasound and Doppler studies suggested the presence of fetal anemia. Homozygous alpha-thalassemia-1 was diagnosed in all cases, with fetal blood sampling confirming anemia in three fetuses. The majority of the intrahepatic umbilical venous maximum flow velocity and middle cerebral artery peak flow velocity measurements were above the 95th centile. Two fetuses underwent intrauterine transfusion and fetal blood flow velocities returned to normal after correction of the fetal anemia. The fetal liver length and spleen perimeter measurements showed a similar trend, although they were less consistent before 28 weeks. CONCLUSION: Non-invasive ultrasound parameters, in particular quantification of intrahepatic umbilical venous maximum flow velocity and middle cerebral artery peak flow velocity, were found to be useful in the diagnosis and management of fetal anemia in pregnancies with fetal homozygous alpha-thalassemia-1.     

Blood flow velocity waveforms of the fetal pulmonary artery and the ductus arteriosus: reference ranges from 13 weeks to term.

OBJECTIVE: To establish reference ranges for blood flow velocity waveforms of the fetal main pulmonary artery and the ductus arteriosus during the second and third trimesters of pregnancy. METHODS: A prospective cross-sectional echocardiographic study was performed in 222 normal fetuses from 13 to 41 weeks of gestation using high resolution/color Doppler ultrasound equipment. RESULTS: Gestational age-specific reference ranges are given for peak velocity across the pulmonary valve, velocities in the ductus arteriosus, peak systolic velocity in the ductus arteriosus-to-peak velocity across the pulmonary valve ratio, ductal systolic velocity-to-diastolic velocity ratio, ductal resistance index and ductal pulsatility index. In the ductus arteriosus, increasing fetal heart rate was significantly associated with increasing end-diastolic velocity and decreasing systolic-to-diastolic ratio, decreasing resistance index, and decreasing pulsatility index. CONCLUSIONS: Based on a prospective study in more than 200 normal fetuses, the data provide gestational age specific reference ranges for blood flow velocity waveforms of the fetal pulmonary artery and the ductus arteriosus. The reference ranges may be helpful in prenatal diagnosis of cardiac malformations and ductal obstruction from 13 to 41 weeks of gestation.     

多普勒超声对高原地区胎儿脐动脉血流的研究

目的运用多普勒超声测量高原地区正常妊娠胎儿脐动脉血流,观察高原环境对胎儿脐带胎盘循环的影响。方法随机选取在外院(海拔2300 m)进行产前检查的正常妊娠孕妇103例为高原观察组,随机选取同期在我院(海拔44 m)进行产前检查的正常妊娠孕妇216例为平原对照组。高原组与平原组均按照孕周分为五组:20~23+6周、24~27+6周、28~31+6周、32~35+6周、36~40周,运用多普勒超声对两组胎儿脐动脉血流搏动指数(PI)、阻力指数(RI)、收缩期峰值流速与舒张末期流速比值(S/D)进行测定。结果孕中晚期五组中,高原组与平原组正常妊娠胎儿PI、RI和S/D差异均无统计学意义(P>0.05)。结论海拔2300 m高原地区正常妊娠胎儿脐带胎盘循环阻力与平原地区无明显差异。     

Umbilical venous volume flow in the normally developing and growth-restricted human fetus.

OBJECTIVE: To determine the reproducibility of measurement of umbilical venous volume flow components and to calculate umbilical venous volume flow in normal and growth-restricted (small-for-gestational age) fetuses in a cross-sectional study. METHOD: Using Labview and Imaq-vision software, the cross-sectional inner area of the umbilical vein was traced. Vessel area (mm2) and Doppler-derived time-averaged flow velocity (mm/s) were multiplied to calculate volume flow (mL/min) including flow per kg fetal weight. The coefficient of variation for vessel area and flow velocity scans and tracings were determined (n = 13; 26-35 weeks). Normal charts for components and volume flow were constructed (n = 100; 20-36 weeks) and related to data from growth restricted fetuses (birth weight < 5th centile) (n = 33; 22-36 weeks). In growth-restricted fetuses the umbilical artery pulsatility index was also obtained. RESULTS: Reproducibility: The coefficient of variation was 5.4% (vessel area) and 7.3% (time-averaged velocity) for scans and 6.6% and 10.5% for measurements, resulting in a coefficient of variation of 8.1% (scans) and 11.9% (measurements) for volume flow. A gestational age-related increase exists for vessel area, time-averaged flow velocity and umbilical venous volume flow from 33.2 (SD, 15.2) mL/min at 20 weeks to 221.0 (SD, 32.8) mL/min at 36 weeks of gestation, but there is a reduction from 117.5 (SD, 33.6) mL/min to 78.3 (SD, 12.4) mL/min for volume flow per kg fetal weight. In small-for-gestational age fetuses, the values were below the normal range in 31 of 33 cases for volume flow and in 21 of 33 cases for volume flow per kg fetal weight. Umbilical artery pulsatility index was significantly different between the subsets with normal and those with reduced volume flow per kg fetal weight. CONCLUSIONS: Measurements of umbilical venous vessel area and time-averaged velocity resulted in acceptable reproducibility of volume flow calculations, which show a seven-fold increase at 20-36 weeks of gestation. In growth-restricted fetuses, volume flow is significantly reduced. When calculated per kg/fetus, the values were reduced in 21 (63.6%) out of 33 cases.     

Effects of maternal hyperoxygenation on ductus venosus flow velocity waveforms in normal third-trimester fetuses.

On the basis of the data obtained in sheep fetuses showing a high interdependence between umbilical vein oxygenation and ductus venosus flow, we investigated the effect of maternal hyperoxygenation on ductus venosus velocity waveforms in normal third-trimester human fetuses. Ductus venosus velocity waveforms were recorded by using color and pulsed Doppler ultrasonography before and after 15 min of maternal administration of humidified 60% oxygen. During maternal hyperoxygenation, there was a significant increase of both estimated peak velocities during systole, diastole and atrial contraction and the mean temporal velocity during the total cardiac cycle and systolic and diastolic portions. On the other hand, during maternal hyperoxygenation, no significant changes were found in fetal heart rate or in the ratios between peak velocities and mean temporal velocities during systole and diastole. These findings suggest a close relationship between fetal oxygenation and ductus venosus velocity waveforms that may be useful in monitoring fetal hypoxemia.     

胎儿脐动脉血流速度与新生儿结局的关系(附166例分析)

目的 :探讨胎儿脐动脉血流速度与新生儿结局的关系。方法 :对 166名孕妇的脐动脉收缩期峰值 (S)与舒张末期峰值 (D)比值 (S/D比值 )测定结果、新生儿结局进行回顾性分析。结果 :S/D比值异常者 17例 ,其中小于胎龄儿 12例 (70 % ) ,新生儿死亡 3例 (18% ) ;正常 149名中小于胎龄儿7例 (5 % ) ,无新生儿死亡。两组比较有显著性差异。结论 :胎儿脐动脉 S/D比值可作为评估新生儿结局的一个重要指标。     

孕中期左心发育不良综合征胎儿的肺动脉血流参数特征的价值

目的探讨孕中期左心发育不良综合征（HLHS）胎儿肺动脉血流参数特征。 方法选取2015年8月至2017年5月在南京医科大学附属苏州医院确诊HLHS胎儿54例，将中孕期HLHS胎儿按照其房间隔血流模式分为血流通畅组（41例）与梗阻组（13例），并与正常胎儿（健康对照组，55例）在肺动脉主干内径、右肺动脉内径和右肺动脉第一级分支血流频谱参数3个层面进行对比，采用LSD-t检验分析通畅型和梗阻型HLHS胎儿的肺动脉内径、收缩期峰值流速（PSV）、舒张期末期速度（EDV）、平均速度（TAMXV）、速度-时间积分（VTI）和肺动脉搏动指数（PA PI）等血流参数特征。 结果肺动脉主干内径方面，三组间均值比较（5.4±0.6 vs 6.7±0.8 vs 6.8±0.9），差异有统计学意义（F=198.56，P<0.05），且通畅组和梗阻组的肺主干内径均大于健康对照组，差异均有统计学意义（t=-18.501、-13.97，P均<0.05），而通畅组和梗阻组的均值比较，差异无统计学意义（P=0.85）；右肺动脉内径方面，三组间均值比较，差异无统计学意义（P=0.59）；右肺动脉第一级分支血流频谱参数方面，三组间在PSV比较，差异无统计学意义（P=0.34），而在EDV、TAMXV、VTI和PA PI方面，差异均有统计学意义（F=62.98、38.45、13.19及12.46，P均<0.05），且通畅组和梗阻组胎儿EDV、TAMXV和VTI均值小于健康对照组，差异均有统计学意义（t=4.273和10.353、3.546和7.978、-0.441和5.418，P均<0.05），且梗阻组均值小于通畅组，差异均有统计学意义（t=5.542、7.033及4.098，P均<0.05）；而通畅组和梗阻组HLHS胎儿PA PI均值大于健康对照组，差异均有统计学意义（t=-2.638、-6.474，P均<0.05），且梗阻组大于通畅组，差异均有统计学意义（t=-2.541，P<0.05）。 结论HLHS胎儿肺动脉分支血流前向阻力增加，且房间隔血流梗阻型相对于通畅型表现更为显著，这可能与梗阻型肺血管床受损程度相对较重有关。     

Power spectrum analysis of heart rate and blood flow velocity variability measured in the umbilical and uterine arteries in early pregnancy: a comparative study.

OBJECTIVE: To compare power spectral derived variability parameters from the fetal side of the placental circulation with those from the maternal side of the placental circulation, during early pregnancy. METHODS: Doppler velocity waveforms were obtained from both the umbilical and the uterine arteries in a study group of 40 pregnant women between 10 and 14 (n = 25) and 15 and 20 (n = 15) weeks of gestation. The coefficient of variation of both the beat-to-beat heart rate variability and the blood flow velocity variability was determined. The ratio of the integrated low-frequency components (< 0.2 Hz) and the integrated high-frequency components (> 0.2 Hz) from normalized power spectrum analysis (LH-ratio) was established, to reflect sympathovagal balance. RESULTS: The coefficient of variation and LH-ratio of fetal heart rate variability constitute only a fraction of the same maternal heart rate variability parameters. Nevertheless a highly significant increase (P < 0.001) in LH-ratio was demonstrated with advancing gestational age. The coefficient of variation and LH-ratio of blood flow velocity variability were significantly lower in the fetal umbilical artery only in the 10-14-weeks' gestation group. Due to a decrease of the maternal uterine blood flow velocity variability parameters with advancing gestational age, statistically equal fetal and maternal values for coefficient of variation and LH-ratio were found in the 15-20 weeks' gestation group. CONCLUSIONS: The increase in LH-ratio of fetal heart rate variability indicates functional development of the fetal autonomic nervous system at 15-20 weeks' gestation. The umbilical blood flow velocity variability may be secondary to maternal uterine arterial flow variability rather than due to primary changes in fetal cardiovascular function.