Tei index to assess fetal cardiac performance in fetuses at risk for fetal inflammatory response syndrome

Value of fetal echocardiographic examination in pregnancies complicated by preterm premature rupture of membranes

OBJECTIVES

Cardiopulmonary and infectious complications are more common in preterm newborns after preterm premature rupture of membranes (pPROM). Fetal echocardiography may be helpful in predicting neonatal condition. Our aim was to assess the cardiovascular changes in fetuses from pregnancies complicated by pPROM and possible utility in predicting the intrauterine or neonatal infection, and neonatal heart failure (HF).

METHODS

It was a prospective study enrolling 46 women with singleton pregnancies complicated by pPROM between 18+0 and 33+6 weeks of gestation and followed until delivery. 46 women with uncomplicated pregnancies served as a control group. Fetal echocardiographic examinations with the assessment of cardiac structure and function (including pulmonary circulation) were performed in all patients.

RESULTS

Mean gestational age of pPROM patients was 26 weeks. Parameters suggesting impaired cardiac function in fetuses from pPROM were: higher right ventricle Tei index (0.48 vs. 0.42 p<0.001), lower blood flow velocity in Ao z-score (0.14 vs. 0.84 p=0.005), lower cardiovascular profile score (CVPS), higher rate of tricuspid regurgitation (18.2 % vs. 4.4 % p=0.04) and pericardial effusion (32.6 vs. 0 %). Intrauterine infection was diagnosed in 18 patients (39 %). 4 (8.7 %) newborns met the criteria of early onset sepsis (EOS). HF was diagnosed in 9 newborns. In fetal echocardiographic examination HF group had shorter mitral valve inflow time and higher left ventricle Tei index (0.58 vs. 0.49 p=0.007).

CONCLUSIONS

Worse cardiac function was observed in fetuses from pPROM compared to fetuses from uncomplicated pregnancies.

Intra-amniotic infection and/or inflammation is associated with fetal cardiac concentric hypertrophy and diastolic dysfunction in preterm labor and preterm prelabor rupture of membranes

BACKGROUND

Preterm delivery is associated with cardiovascular remodeling and dysfunction in children and adults. However, it is unknown whether these effects are caused by the neonatal consequences of preterm birth or if these are already present in utero.

OBJECTIVE

We evaluated fetal cardiac morphology and function in fetuses of mothers admitted for preterm labor or preterm prelabor rupture of membranes and the association of these changes with the presence of intra-amniotic infection and/or inflammation.

STUDY DESIGN

In this prospective cohort study, fetal echocardiography and amniocentesis were performed at admission in singleton pregnant women with preterm labor and/or preterm prelabor rupture of membranes between 24.0 and 34.0 weeks' gestation with (intra-amniotic infection and/or inflammation group, n=41) and without intra-amniotic infection and/or inflammation (non-intra-amniotic infection and/or inflammation, n=54). Controls (n=48) were outpatient pregnant women without preterm labor or preterm prelabor rupture of membranes. Intra-amniotic infection was defined by a positive amniotic fluid culture or positive 16S ribosomal RNA gene. Intra-amniotic inflammation was defined by using the amniotic fluid interleukin-6 cutoff levels previously reported by our group being >1.43 ng/mL in preterm prelabor rupture of membranes and >13.4 ng/mL in preterm labor. Fetal cardiac morphology and function was evaluated using echocardiography, and troponin-I and N-terminal pro-brain natriuretic peptide concentrations were measured in amniotic fluid from women with preterm labor or preterm prelabor rupture of membranes and compared with 20 amniotic fluid Biobank samples obtained for reasons other than preterm labor or preterm prelabor rupture of membranes or cardiac pathology. The data were adjusted for the estimated fetal weight below the 10th percentile and for preterm prelabor rupture of membranes at admission and also for gestational age at amniocentesis when amniotic fluid biomarkers were compared.

RESULTS

From 2018 to 2021, 143 fetuses were included; 95 fetuses were from mothers admitted with a diagnosis of preterm labor or preterm prelabor rupture of membranes, and among those, 41 (28.7%) were in the intra-amniotic infection and/or inflammation group and 54 (37.8%) were in the non-intra-amniotic infection and/or inflammation group. A total of 48 (33.6%) fetuses were included in the control group. Fetuses with preterm labor and/or preterm prelabor rupture of membranes had signs of subclinical cardiac concentric hypertrophy (median left wall thickness of 0.93 [interquartile range, 0.72-1.16] in the intra-amniotic infection and/or inflammation group; 0.79 [0.66-0.92] in the non-intra-amniotic infection and/or inflammation group; and 0.69 [0.56-0.83] in controls; P<.001) and diastolic dysfunction (tricuspid A duration 0.23 seconds [0.21-0.25], 0.24 [0.22-0.25], and 0.21 [0.2-0.23]; P=.007). Systolic function was similar among groups. Higher values of amniotic fluid troponin I (1413 pg/mL [927-2334], 1190 [829-1636], and 841 [671-959]; P<.001) and N-terminal pro-brain natriuretic peptide were detected (35.0%, 17%, and 0%; P=.005) in fetuses with preterm labor or preterm prelabor rupture of membranes when compared with the control group. The highest N-terminal pro-brain natriuretic peptide concentrations were found in the intra-amniotic infection and/or inflammation group.

CONCLUSION

Fetuses with preterm labor or preterm prelabor rupture of membranes showed signs of cardiac remodeling and subclinical dysfunction, which were more pronounced in those exposed to intra-amniotic infection and/or inflammation. These findings support that the cardiovascular effects observed in children and adults born preterm have, at least in part, a prenatal origin.

Neonatal sepsis and cardiovascular dysfunction I: mechanisms and pathophysiology

The highest incidence of sepsis across all age groups occurs in neonates leading to substantial mortality and morbidity. Cardiovascular dysfunction frequently complicates neonatal sepsis including biventricular systolic and/or diastolic dysfunction, vasoregulatory failure, and pulmonary arterial hypertension. The haemodynamic response in neonatal sepsis can be hyperdynamic or hypodynamic and the underlying pathophysiological mechanisms are heterogeneous. The diagnosis and definition of both neonatal sepsis and cardiovascular dysfunction complicating neonatal sepsis are challenging and not consensus-based. Future developments in neonatal sepsis management will be facilitated by common definitions and datasets especially in neonatal cardiovascular optimisation. IMPACT: Cardiovascular dysfunction is common in neonatal sepsis but there is no consensus-based definition, making calculating the incidence and designing clinical trials challenging. Neonatal cardiovascular dysfunction is related to the inflammatory response, which can directly target myocyte function and systemic haemodynamics.

The Importance of Tissue Doppler Imaging and M-Mode Ultrasonography in Fetuses With Preterm Premature Rupture of Membranes: A Case-Control Study

OBJECTIVE

To compare the cardiac functions of fetuses with preterm premature rupture of membranes (PPROM) between their control groups and investigate its relationship with perinatal outcomes.

METHODS

This prospective study was conducted with 102 pregnant women. Pregnant women with PPROM were divided into two subgroups Group A, between 26 and 30 weeks, and Group B, between 30 and 34 weeks. A control group was formed by randomly including one healthy pregnant woman for each study patient. Sociodemographic, obstetric data, tissue Doppler imaging, and M-mode imaging results were compared. The relationship between echocardiographic parameters and perinatal outcomes was also investigated.

RESULTS

Tricuspid annular plane systolic excursion (TAPSE), S', and ET' of systolic cardiac parameters were shortened in both groups compared with their controls. Diastolic function indicator E'/A', and global function indicator myocardial performance index' increased in both groups. Isovolumetric contraction time' did not change between groups. A correlation was found between myocardial performance index', and the length of neonatal intensive care unit stay in Group A and TAPSE and duration of respiratory support and length of neonatal intensive care unit stay in Group B.

CONCLUSIONS

The fetal cardiac function seems to be affected by PPROM, and these changes are associated with neonatal outcomes. Therefore, administering fetal cardiac function evaluation in pregnancies complicated by PPROM may help physicians establish more appropriate clinical management protocols in this special population.

The assessment of fetal cardiac functions in pregnancies with autoimmune diseases: a prospective case-control study

OBJECTIVES

This study aimed to assess the effect of the inflammatory process on fetal cardiac functions in pregnant women with autoimmune diseases (AID).

METHODS

This prospective study included 36 pregnant women with diagnosed AID. Nineteen systemic lupus erythematosus, 12 antiphospholipid syndrome, 5 Sjögren's syndrome, and 72 healthy pregnancies were included. Fetal cardiac functions were evaluated with pulsed-wave, tissue Doppler, and M-mode echocardiography.

RESULTS

Sociodemographic data were similar in both groups. Significant increases were found in tricuspid E (43.5 ± 0.9, p<0.001) and A (59.2 ± 2.2, p<0.001) and E/A (0.74 ± 0.03, p<0.001), E'/A' (0.64 ± 0.15, p<0.001), E/E' (6.5 ± 0.6, p<0.001), and left ventricular myocardial performance index (0.54 ± 0.03, p=0.005). We demonstrated a significant decrease in tricuspid E' (6.7 ± 0.6, p<0.001) and S' (6.9 ± 1, p<0.001) and in TAPSE (7.7 ± 0.5, p=0.002). We also found a significantly prolonged PR interval (130 ± 8, p<0.001). There was a significant increase in E' (6.8, p=0.033) and a significant decrease in E/E' ratio (6.4, p=0.027) in the group using hydroxychloroquine (HCQ) compared to non-users.

CONCLUSIONS

We found that pregnancy with autoimmune diseases affects fetal heart functions. Additionally, hydroxychloroquine may positively affect the heart of AID fetuses. This information might be useful to clinicians in the follow-up of cardiovascular diseases.

Artificial placenta technology: History, potential and perception

As presently conceptualised, the artificial placenta (AP) is an experimental life support platform for extremely preterm infants (i.e. 400-600 g; 21-23+6 weeks of gestation) born at the border of viability. It is based around the oxygenation of the periviable fetus using gas-exchangers connected to the fetal vasculature. In this system, the lung remains fluid-filled and the fetus remains in a quiescent state. The AP has been in development for some sixty years. Over this time, animal experimental models have evolved iteratively from employing external pump-driven systems used to support comparatively mature fetuses (generally goats or sheep) to platforms driven by the fetal heart and used successfully to maintain extremely premature fetuses weighing around 600 g. Simultaneously, sizable advances in neonatal and obstetric care mean that the nature of a potential candidate patient for this therapy, and thus the threshold success level for justifying its adoption, have both changed markedly since this approach was first conceived. Five landmark breakthroughs have occurred over the developmental history of the AP: i) the first human studies reported in the 1950's; ii) foundation animal studies reported in the 1960's; iii) the first extended use of AP technology combined with fetal pulmonary resuscitation reported in the 1990s; iv) the development of AP systems powered by the fetal heart reported in the 2000's; and v) the adaption of this technology to maintain extremely preterm fetuses (i.e. 500-600 g body weight) reported in the 2010's. Using this framework, the present paper will provide a review of the developmental history of this long-running experimental system and up-to-date assessment of the published field today. With the apparent acceleration of AP technology towards clinical application, there has been an increase in the attention paid to the field, along with some inaccurate commentary regarding its potential application and merits. Additionally, this paper will address several misrepresentations regarding the potential application of AP technology that serve to distract from the significant potential of this approach to greatly improve outcomes for extremely preterm infants born at or close to the present border of viability.

Change over time in internal cerebral vein pulsation in premature infants at risk of intraventricular hemorrhage

BACKGROUND

Prolonged continuation of augmented internal cerebral vein (ICV) pulsation may be related to the development of premature intraventricular hemorrhage (IVH). However, the characteristics of ICV flow patterns in premature infants are unclear.

AIM

To investigate the changes over time in ICV pulsation in premature infants at risk of IVH.

STUDY DESIGN

A 5-year retrospective observational study of a single-center trial.

SUBJECTS

In total, 112 very-low-birth-weight infants with gestational age of ≤32 weeks.

OUTCOME MEASURES

ICV flow was measured every 12 h until 96 h after birth and thereafter on days 7, 14, and 28. The ICV pulsation index (ICVPI), which is a ratio of the minimum/maximum speed of ICV flow, was calculated. We recorded longitudinal ICVPI change and compared ICVPI among three groups classified according to gestational age.

RESULTS

ICVPI started declining after day 1 and reached the minimum median value in 49-60 h after birth (1.0 during 0-36 h, 0.9 during 37-72 h, and 1.0 after 73-84 h). ICVPI was significantly lower during 25-96 h than during 0-24 h and on days 7, 14, and 28. ICVPI in the 23-25-week group was significantly lower between 13-24 h and day 14 than that in the 29-32-week group, and the same was observed for the 26-28-week group between 13-24 h and 49-60 h.

CONCLUSIONS

ICV pulsation was affected by time after birth and gestational age, and this ICVPI fluctuation may reflect a postnatal circulatory adaptation.

Linking the Perinatal Environment to Neonatal Cardiovascular Outcomes

Cases of high-risk pregnancies continue to rise throughout the United States and globally, increasing rates of maternal and neonatal morbidity. Common pregnancy complications and morbidities include preterm birth, hypertensive disorders, fetal growth restriction, diabetes mellitus, and chorioamnionitis. Exposure to these perinatal conditions contributes to cardiac morbidities in the fetus and neonate, including altered cardiac growth, congenital heart disease, and cardiac dysfunction. Significant research has demonstrated lasting effects of these pregnancy complications, with increased rates of cardiac morbidities seen in children and adults after these perinatal exposures. The link between the perinatal environment and long-term outcomes has not been fully elucidated. The aim of this review is to discuss the current understanding of the implications of a high-risk pregnancy on fetal and neonatal cardiac development.

Evaluation of fetal cardiac morphology and functions in pregnant women with familial Mediterranean fever

OBJECTIVE

We aimed to evaluate and compare fetal cardiac morphology and functions of pregnant women with familial Mediterranean fever (FMF) and healthy pregnant women.

METHODS

The study included 34 pregnant women with FMF and 68 healthy pregnant women matched with maternal age, gravidity, parity, gestational age, and pre-pregnancy body mass index (BMI) in 34th-37th gestational weeks. Fetal echocardiographic evaluation was performed with two-dimensional (2D) imaging, M-mode imaging, pulsed wave (PW) Doppler, and tissue Doppler imaging (TDI).

RESULTS

Fetal cardiac morphological measures, including cardiothoracic ratio, cardiac axis angle, right and left ventricular area, sphericity index, and ventricular septal thickness was similar in both groups. Compared with the control group, myocardial performance index (MPI), which indicates global myocardial performance, was significantly higher, and ejection time (ET) was significantly shortened in the FMF group. In addition, which shows the diastolic functional parameters such as, tricuspid E wave, E/A, E/E' ratio, and mitral E wave, E/A, E/E' ratio, were significantly higher; tricuspid A and mitral A waves were significantly lower. We found that mitral and tricuspid annular plane systolic excursion (MAPSE and TAPSE) were significantly lower in those with FMF duration over eight years than those with FMF duration less than 8 years.

CONCLUSION

There is no fetal cardiac morphological change in pregnant women with FMF. However, there may be changes in diastolic function. As the maternal FMF duration increases, systolic functions may also change.

The effect of nuchal umbilical cord on fetal cardiac and cerebral circulation-cross-sectional study

OBJECTIVES

The subject of our analysis is the influence of umbilical cord collision around the fetal neck on the fetal heart function and cerebral circulation.

METHODS

Our study was carried out on a group of 115 fetuses from single pregnancies with physiological course, during the 15th to 40th week of pregnancy. In our analysis, we examined the following parameters: Tei index for right ventricle, Tei index for left ventricle with Tei index components: isovolumetric contraction time, isovolumetric relaxation time, ejection time and cardiothoracic area ratio, middle cerebral artery peak systolic velocity (PS MCA), middle cerebral artery pulsatility index (PI MCA). Gestational age in our study was: 28+2±34. The study group of patients with fetal umbilical cord around neck group (fUCAN) included 38 fetuses (20 males, 18 females). The control group of patients with no fetal umbilical cord around neck group (NfUCAN) included 77 fetuses (43 males, 34 females).

RESULTS

In our study, we found no significant differences in the values obtained: Tei LV in fUCAN: 0.5±0.1 vs. in NfUCAN: 0.5±0.1; p=0.42), Tei RV in fUCAN: 0.5±0.2 vs. in NfUCAN: 0.4±0.1; (p=0.2). Tricuspid valve regurgitation-TR was observed with the following frequency: fUCAN: 7/38, 18% vs. NfUCAN: 13/77, 17%; p=0.8. MCA PS in study fUCAN group was significantly higher than in NfUCAN (40.2±11.5 vs. 32.5±9.5; p=0.003), although other hemodynamic and clinical variables did not differ between the study and control groups.

CONCLUSIONS

The fetal nuchal umbilical cord collision did not affect the fetal heart function expressed as Tei index, at the time of fetal heart examination (at mean gestational age 29+4 weeks). The fUCAN group presented elevated PS MCA, which was not related to other hemodynamic and clinical variables between the study and control groups.

Necrotizing funisitis and calcification of umbilical vein: case report and review

BACKGROUND

Necrotising funisitis (NF) is a rare, chronic stage of funisitis, a severe inflammation of the umbilical cord and an important risk factor for fetal adverse outcomes. NF is characterized by yellow-white bands running parallel to the umbilical blood vessels. These bands consist of inflammatory cells, necrotic debris, and calcium deposits. Calcification is visible in ultrasonography, which makes it possible to suspect NF when umbilical vascular wall calcification is detected by prenatal ultrasonography.

CASE PRESENTATION

Ultrasonography revealed calcification of the umbilical venous wall in an expectant 31-year-old woman who was gravida 1, para 0. The woman required emergency cesarean section because of fetal distress and suspected umbilical cord torsion at 31 weeks gestation. The root of the umbilical cord was quite fragile and broke during the operation. The pathological results on the placenta showed histologic chorioamnionitis and NF. The infant was diagnosed to have neonatal sepsis and acidosis after delivery but was discharged without severe complications after a one-month hospitalization that included antibiotic and supportive therapy.

CONCLUSION

NF is a rare and severe inflammation of the umbilical cord. Umbilical vascular wall calcification discovered in prenatal ultrasonography is diagnostically helpful.

Fetal myocardial performance index in pregnancies with idiopathic mildly increased amniotic fluid volume

PURPOSE

To evaluate modified myocardial performance index (MPI), or Tei index, in fetuses of pregnancies with idiopathic mildly increased amniotic fluid index (AFI).

METHODS

We studied 25 cases (24-40 weeks) with idiopathic mildly increased AFI, and 25 gestational age- and fetal gender-matched healthy controls. Fetal echocardiographic variables and Doppler-derived indices were recorded, including left and right MPI, left isovolumetric contraction time (IVCT), left ejection time (ET), left isovolumetric relaxation time (IVRT), aortic and pulmonary arterial peak systolic velocity (PSV), left and right E/A ratios, middle cerebral artery (MCA) pulsatility index (PI), and umbilical artery (UA) PI.

RESULTS

The mean left MPI (0.52 vs 0.41, P < .0001) and right MPI (0.50 vs 0.42, P < .001) were higher, and mean IVCT (37.7 vs 25.9, P < .0001) was longer in cases than in controls. However, there were no significant differences between the two groups in IVRT (45.2 vs 43.2, P = .381), ET (160.2 vs 170.0, P = .079), aortic PSV (P = .073), left E/A (P = .080), pulmonary artery PSV (P = .061), right E/A (P = .054), MCA PI (P = .259), UA PI (P = .685), and cerebroplacental ratio (P = .645).

CONCLUSION

Pregnancies with idiopathic mildly increased AFI were associated with a significant increase in the fetal MPI of both left and right ventricles.

Congenital Heart Defects and the Risk of Spontaneous Preterm Birth

OBJECTIVES

To estimate the association between major types of congenital heart defects (CHD) and spontaneous preterm birth, and to assess the potential underlying mechanisms.

STUDY DESIGN

This nationwide, registry-based study included a cohort of all singleton pregnancies in Denmark from 1997 to 2013. The association between CHD and spontaneous preterm birth was estimated by multivariable Cox regression, adjusted for potential confounders. The following potential mechanisms were examined: maternal genetics (sibling analyses), polyhydramnios, preterm prelabor rupture of membranes, preeclampsia, and indicators of fetal and placental growth.

RESULTS

The study included 1 040 474 births. Compared with the general population, CHD was associated with an increased risk of spontaneous preterm birth, adjusted hazard ratio 2.1 (95% CI, 1.9-2.4). Several subtypes were associated with increased risks, including pulmonary stenosis combined with a septal defect, 5.2 (95% CI, 3.7-7.5); pulmonary stenosis or atresia, 3.1 (95% CI, 2.4-4.1); tetralogy of Fallot 2.5 (95% CI, 1.6-3.8); coarctation or interrupted aortic arch 2.2 (95% CI, 1.5-3.2); and hypoplastic left heart syndrome, 2.0 (95% CI, 1.0-4.1). Overall, preterm prelabor rupture of membranes mediated more than one-half of the association. Maternal genetics, polyhydramnios, or indicators of fetal or placental growth did not explain the reported associations.

CONCLUSIONS

CHD, especially right ventricular outflow tract obstructions, were associated with an increased risk of spontaneous preterm birth. The risk was carried by the CHD and not by maternal genetics. Moreover, preterm prelabor rupture of membranes was identified as a potential underlying mechanism.

Maternal azithromycin therapy for Ureaplasma parvum intraamniotic infection improves fetal hemodynamics in a nonhuman primate model

BACKGROUND

Ureaplasma parvum infection is a prevalent cause of intrauterine infection associated with preterm birth, preterm premature rupture of membranes, fetal inflammatory response syndrome, and adverse postnatal sequelae. Elucidation of diagnostic and treatment strategies for infection-associated preterm labor may improve perinatal and long-term outcomes for these cases.

OBJECTIVE

This study assessed the effect of intraamniotic Ureaplasma infection on fetal hemodynamic and cardiac function and the effect of maternal antibiotic treatment on these outcomes.

STUDY DESIGN

Chronically catheterized pregnant rhesus monkeys were assigned to control (n=6), intraamniotic inoculation with Ureaplasma parvum (107 colony-forming units/mL, n=15), and intraamniotic infection plus azithromycin treatment (12.5 mg/kg twice a day intravenously, n=8) groups. At approximately 135 days' gestation (term=165 days), pulsed and color Doppler ultrasonography was used to obtain measurements of fetal hemodynamics (pulsatility index of umbilical artery, ductus venosus, descending aorta, ductus arteriosus, aortic isthmus, right pulmonary artery, middle cerebral artery and cerebroplacental ratio, and left and right ventricular cardiac outputs) and cardiac function (ratio of peak early vs late transmitral flow velocity [marker of ventricular function], Tei index [myocardial performance index]). These indices were stratified by amniotic fluid proinflammatory mediator levels and cardiac histology.

RESULTS

Umbilical and fetal pulmonary artery vascular impedances were significantly increased in animals from the intraamniotic inoculation with Ureaplasma parvum group (P<.05). Azithromycin treatment restored values to control levels. Amniotic fluid prostaglandin F2 alpha levels were significantly higher in animals with abnormal umbilical artery pulsatility index (>1.1) than in those with normal blood flow (P<.05; Spearman ρ=0.6, P<.05). In the intraamniotic inoculation with Ureaplasma parvum group, left ventricular cardiac output was significantly decreased (P<.001), and more animals had abnormal right-to-left ventricular cardiac output ratios (defined as >1.6, P<.05). Amniotic fluid interleukin-6 concentrations were elevated in cases of abnormal right-to-left ventricular cardiac output ratios compared with those in normal cases (P<.05).

CONCLUSION

Fetal hemodynamic alterations were associated with intraamniotic Ureaplasma infection and ameliorated after maternal antibiotic treatment. Doppler ultrasonographic measurements merit continuing investigation as a diagnostic method to identify fetal cardiovascular and hemodynamic compromise associated with intrauterine infection or inflammation and in the evaluation of therapeutic interventions or clinical management of preterm labor.

Normal reference ranges for fetal cardiac function: Assessed by modified Doppler myocardial performance index (Mod MPI) in the Egyptian population

AIM

To develop gestational age-based reference ranges for the modified Doppler myocardial performance index (Mod MPI) and to examine the maternal characteristics that affect this measurement.

METHODS

This was a cross-sectional study, comprised of 1021 healthy pregnancies between 20+0 to 35+6 weeks' gestation. They were all undergoing ultrasound examination in Cairo Fetal Medicine Unit (CAIFM) in Cairo University, Egypt from 1st April 2017 till 1st April 2019. Mod MPI was obtained used method described by Friedman et al. (2003). Median and SD models were fitted between Mod MPI and gestational age. The distributions of Mod MPI Z-scores were examined in relation to maternal characteristics RESULTS: The normal Mod MPI in second and third trimester (20 + 1 to 35 + 6 weeks' gestation) was 0.408 ± 0.08. Mod MPI was not affected by maternal age, body mass index (BMI) or parity (p value 0.5, 0.6 and 0.2 respectively).

CONCLUSION

This study established normal reference ranges for Mod MPI according to gestational age and generated a graph with 5th,10th, 90th and 95th centiles. Maternal characteristics as age, BMI or parity do not affect value of Mod MPI.

Placental malperfusion in response to intrauterine inflammation and its connection to fetal sequelae

Exposure to intrauterine inflammation (IUI) is associated with short- and long-term adverse perinatal outcomes. However, little data exist on utilizing placenta to prognosticate fetal injury in this scenario. Our study aimed to utilize imaging modalities to evaluate mechanisms contributing to placental injury following IUI exposure and correlated it to concomitant fetal brain injury. CD1 pregnant dams underwent laparotomies and received intrauterine injections of either lipopolysaccharide (LPS; a model of IUI) or phosphate-buffered saline (PBS). In utero ultrasound Doppler velocimetry of uterine and umbilical arteries and magnetic resonance imaging (MRI) of placental volumes with confirmatory immunohistochemical (vimentin) and histochemistry (fibrin) analyses were performed. ELISA for thrombosis markers, fibrinogen and fibrin was performed to analyze thrombi in placenta. Fetal brain immunohistochemistry was performed to detect microglial activation (ionized calcium-binding adaptor molecule 1, Iba1). On ultrasound, LPS group demonstrated elevated resistance indices, pulsatility indices and a greater occurrence of absent end-diastolic flow in the umbilical and uterine arteries. In the fetus, there was an increased cardiac Tei indices in the LPS group. MRI revealed decreased volume of placenta in the LPS group associated with placental thinning and placental endothelial damage on immunohistochemistry. Decreased fibrinogen content and more thrombi staining in placenta exposed to maternal LPS indicated the hypercoagulability. Furthermore, the expression of Iba1was significantly associated with placental thickness (r = -0.7890, Pearson correlation coefficient). Our data indicate that IUI can trigger events leading to maternal placental malperfusion and fetal vessel resistance, as well as predispose the developing fetus to cardiac dysfunction and brain damage. Furthermore, our data suggest that prenatal ultrasound can be a real-time clinical tool for assessing fetal risk for adverse neurologic outcomes following the potential IUI exposure.

The effect of increased amnion volume severity on fetal Doppler indices and perinatal outcomes in idiopathic polyhydramnios

Aim: To evaluate the relationship between polyhydramnios severity and alterations in Doppler indices and perinatal outcomes in idiopathic polyhydramnios.Methods: This prospective case control study was conducted in a tertiary hospital with 173 singleton pregnancies between 29 and 41 weeks gestational age between May 2015 and December 2016. Polyhydroamnios is classified as mild (amniotic fluid index 25-30 cm), moderate (30.1-35 cm), and severe (>35 cm) and the number of the patients in mild, moderate, and severe groups were 55, 39, and 26, respectively. The results were compared with 53 healthy controls. Fetal echocardiography and Doppler measurements of the groups were made and the perinatal outcomes from each group were noted. The relationship between the results and the severity of polyhydramnios was analyzed statistically.Results: The myocardial performance index was significantly higher in the fetuses of women with severe polyhydramnios compared to the other groups (p = .006). There were statistically significant differences among the groups in terms of first and fifth minutes according to the Apgar scores (p = .011, p = .016 respectively). In the severe polyhydramnios group compared with other groups, the middle cerebral artery pulstatility index was significantly lower (p = .002), while middle cerebral artery peak systolic velocity and umbilical artery pulstatility index values were significantly higher (p = .0001, p = .045).Conclusions: Our study showed an increase in myocardial performance index and middle cerebral artery peak systolic velocity values and a decrease in middle cerebral artery pulstatility index values, especially in the severe idiopathic polyhydramnios group. Idiopathic polyhydramnios were associated with low first and fifth minute Apgar score. Additionally, the increase in umbilical artery pulstatility index value and the decrease in middle cerebral artery pulstatility index value became more apparent with the increase in amniotic fluid volume. It should be taken into consideration that brain sparing effect may develop especially in cases with severe polyhydramnios.

Fetal modified left myocardial performance index monitoring during open surgery for myelomeningocele repair

OBJECTIVE

Fetal hemodynamic changes have already been described during open myelomeningocele repair. This study aimed to access fetal myocardial performance index (MPI) during this high-complexity surgery.

METHODS

Open myelomeningocele repair was performed in 37 fetuses between the 24th and 27th week of gestation. MPI was calculated at specific periods: pre-anesthesia, postanesthesia, neurosurgery (early skin manipulation, spinal cord releasing, and sintesis), and end of surgery. Mean ± standard deviation (SD) of MPI and its related times-isovolumetric contraction time (ICT), isovolumetric relaxation time (IRT), and ejection time (ET)-was determined for each period. Analysis of variance (ANOVA) with repeated measures was used to assess differences among these periods. Tukey multiple comparison times test compared global surgery stages.

RESULTS

The mean of MPI in the specific time points was 0.32, 0.32, 0.34, 0.48, 0.36, and 0.32, respectively (P < .001). In the two-tailed comparison times, neurosurgery stage presents MPI highest levels, especially on stage 3b (early skin manipulation and spinal cord releasing) related to ICT and IRT rising and ET decreased levels.

CONCLUSION

Fetal global cardiac function is altered during the open myelomeningocele repair. The neurosurgery stage represents the critical phase of the procedure.

Fetal isovolumetric time intervals as a marker of abnormal cardiac function in fetal anemia from homozygous alpha thalassemia-1 disease

OBJECTIVE

To determine whether fetal isovolumetric time intervals can be an early sonographic marker of fetal anemia in fetuses with homozygous alpha thalassemia-1.

METHODS

Pregnancies at risk for fetal homozygous alpha thalassemia-1 disease at 18-22 weeks were recruited before cordocentesis for hemoglobin typing. Isovolumetric contraction time (ICT) and isovolumetric relaxation time (IRT) intervals were measured by placing pulsed wave Doppler sample volume within the left ventricle to obtain the mitral and aortic waveform. Time intervals were compared between the affected group of homozygous alpha thalassemia-1 fetuses and the unaffected group.

RESULTS

Among 70 fetuses at risk, 28 cases were diagnosed as affected by homozygous alpha thalassemia-1 disease. Mean ICT and ICT + IRT intervals in the affected group were significantly longer than in the unaffected group (47.9 ± 12.5 ms vs 35.0 ± 6.7 ms, p < 0.001; and 96.2 ± 13.6 ms vs 80.9 ± 10.6 ms, p < 0.001. ICT effectively predicted affected fetuses with 71.4% sensitivity and 78.6% specificity using a cutoff value ≥40 ms.

CONCLUSIONS

Isovolumetric contraction time was significantly prolonged in fetal anemia from homozygous alpha thalassemia-1 during the early stage of hydropic changes. Because of its simple measurement and high efficacy, ICT can be a useful marker for prenatal screening of abnormal cardiac function in fetal anemia. © 2017 John Wiley & Sons, Ltd.

Novel Technique for Measurement of Fetal Right Myocardial Performance Index Using Dual Gate Pulsed-Wave Doppler

OBJECTIVES

To evaluate the reproducibility of the fetal right myocardial performance index determined by simultaneous recording of inflow and outflow using a dual gate pulsed-wave Doppler (DD).

METHODS

This was a prospective study of 39 normal singleton fetuses. Two experienced operators each measured the right myocardial performance index in three ways, twice: (1) separate recording of the inflow and outflow using single-gate pulsed-wave Doppler (PD), (2) simultaneous recordings of the inflow and outflow using tissue Doppler (TD), and (3) simultaneous recordings of the inflow and outflow using DD. Intra- and interoperator reproducibility were assessed with intraclass correlation coefficients. The measurements from all three methods taken by the more experienced operator were compared using Bland-Altman plots and mean differences.

RESULTS

For both operators, intra-operator reproducibility was the highest when using DD, followed by PD, and TD. Interoperator agreement was the highest for PD measurements, followed by DD, and TD. The smallest mean difference was between the PD and DD measurements by the more experienced operator. There was a positive correlation between PD and DD values (r = 0.369, P < .001).

CONCLUSIONS

Dual gate pulsed-wave Doppler may be an effective alternative to the PD or TD methods, and can separately evaluate systolic and diastolic myocardial function.

Right Heart Function of Fetuses and Infants with Large Ventricular Septal Defect: A Longitudinal Case-Control Study

The objective of this study was to detect the effect of a large ventricular septal defect (VSD) on right ventricular function before and after birth. All consecutive children with large VSD who were born in our hospital between January 2013-February 2016 and followed up throughout early infancy, and who lacked malformations or chromosomal abnormalities, were identified by a retrospective review of the medical records and included in this retrospective longitudinal case-control study (n = 30). Thirty normal control cases with an equivalent gestational age and gender served as controls. Tricuspid annular plane systolic excursion (TAPSE), right ventricle (RV) Tei index, and tricuspid E/E _m were measured in the fetal, neonatal (day 1-28), and infant (day 29-70) periods. In all periods, the VSD and control groups did not differ in TAPSE values, but VSD associated with higher Tei indices and tricuspid E/E _m values (in the fetal period: VSD group RV Tei was 0.48 ± 0.12 and E/E _m was 11.84 ± 1.53, control group RV Tei was 0.42 ± 0.16 and E/E _m was 10.16 ± 1.61; in neonatal period: VSD group RV Tei was 0.41 ± 0.17 and E/E _m was 12.21 ± 1.59, control group RV Tei was 0.30 ± 0.13 and E/E _m was 7.20 ± 1.28; in the infant period: VSD group RV Tei was 0.39 ± 0.09 and E/E _m was 11.89 ± 2.80, control group RV Tei was 0.28 ± 0.12 and E/E _m was 5.26 ± 1.90, all p < 0.05). In the fetal and neonatal periods, TAPSE correlated negatively with Tei index and tricuspid E/E _m in both groups. However, in the infant period, only the control group exhibited correlations between TAPSE and Tei index or tricuspid E/E _m. Tei index correlated positively with tricuspid E/E _m in both groups in all three periods. The VSD group had smaller correlation coefficients than the control group. Large VSD may already start to impair RV diastolic and global function before birth. This impairment continued and increased after birth. These changes did not associate with obvious RV longitudinal systolic function impairment. Large VSD mainly affected RV function by decreasing diastolic function and myocardial performance.

Fetal myocardial index during labor

BACKGROUND: The Myocardial Performance Index (MPI) is a Doppler derived myocardial function tool and can be used to evaluate systolic and diastolic function in fetuses. The objectives of this study were to investigate the MPI during labor and compare it to values in non-laboring women.

METHODOLOGY: 40 women with uncomplicated, term, singleton pregnancies were recruited to this prospective observational study at Thomas Jefferson University Hospital. Controls were a retrospective cohort of women > 34 weeks who underwent third trimester fetal echocardiography. Fetal left and right sided isovolumic contraction time, isovolumic relaxation time and ejection time were recorded before, during and after contractions. Right and left sided MPI was then calculated.

RESULTS: Laboring patients and non-laboring patients were comparable for age, race, gravidity and parity. During labor the average left MPI was 0.63 ± 0.17 and the average right MPI was 0.62 ± 0.20. The coefficient of correlation between MPI and cervical dilation was 0.15 for left MPI Index and 0.14 for right MPI. When comparing non-laboring to laboring women, the average left MPI for non-laboring women was 0.34 ± 0.04, p = <0.001.

CONCLUSIONS: Myocardial Performance Index is a non-invasive, easily attainable measure of cardiac function that can be obtained during labor and does not change with cervical dilation. MPI is significantly different between laboring and non-laboring women. The fetal MPI may help define fetal status in labor.

Effect of cordocentesis on fetal myocardial performance

OBJECTIVE

To compare fetal Tei index before, immediately after and 30 min after cordocentesis for prenatal diagnosis.

PATIENTS AND METHODS

Pregnant women undergoing prenatal diagnostic cordocentesis in the early mid-trimester underwent measurement of the fetal Tei index of both right and left ventricles just before cordocentesis, immediately after and at 30 min after the procedure.

RESULTS

A total of 143 singleton women underwent cordocentesis at a median gestational age of 19 weeks (range 16-23). The most common indication was fetal risk of beta-thalassemia/hemoglobin E disease (42%, 60 cases). Immediately after cordocentesis, fetal Tei index and all its components at both ventricles were significantly altered when compared with the baseline values (p < 0.001). At 30 min after cordocentesis, components of the Tei index had significantly improved but 5/6 had not completely recovered. No serious procedure-related short-term complications were observed in the study.

CONCLUSION

Cordocentesis has a negative impact on fetal hemodynamics as indicated by worsening of the Tei index. Although the adverse effect seems to be temporary, the recovery time may be longer than 30 min. © 2016 John Wiley & Sons, Ltd.

Ultrasonographic approach to diagnosis of fetal inflammatory response syndrome: a tool for at-risk fetuses?

Preterm parturition is a syndrome that may result from many underlying mechanisms. Infection and inflammation are the prominent ones. Intrauterine infection and inflammation have an effect akin to sepsis, and that is similar to systemic inflammatory response in adults. Indeed, there is evidence to support the association of a fetal inflammatory response syndrome (FIRS) to systemic infection and inflammation. The utilization of invasive procedures for the prenatal diagnosis of FIRS is associated with a risk for complications resulting from the invasive method. The progress in the imaging quality of obstetrical ultrasound and the development of novel methods for functional anatomical assessment of the fetal organs may help to identify, noninvasively, fetuses at risk for FIRS in patients presenting with preterm labor. We review the studies describing advanced sonographic modalities and the imaging findings in the heart, thymus, kidney, adrenal glands, and spleen of these fetuses.

Evaluation of right ventricular function in fetal hypoplastic left heart syndrome by color tissue Doppler imaging

OBJECTIVE

Postnatal outcome of fetuses with hypoplastic left heart syndrome (HLHS) is determined mainly by right ventricular function. Our study examines whether there are differences in right ventricular function during gestation of fetuses with HLHS compared with healthy fetuses.

METHODS

A prospective study was conducted including 20 fetuses with HLHS and 20 gestational age-matched controls. Peak systolic and diastolic right ventricular free wall velocities were assessed using color tissue Doppler imaging (c-TDI). Subsequently, isovolumic time intervals, ejection time (ET'), E'/A' ratio and tissue Doppler-derived myocardial performance index (MPI') were calculated. Possible changes to c-TDI indices during the course of pregnancy in both the HLHS group and the control group were investigated.

RESULTS

Examination of right ventricular function revealed significantly lower E' velocities (13.6 vs 21.0 cm/s; P = 0.017) and E'/A' ratios (0.55 vs 0.76; P = 0.012) and prolonged isovolumic contraction time (ICT') (57.0 vs 45.7 ms; P = 0.008) in the HLHS group compared with healthy fetuses. Furthermore, isovolumic relaxation time and MPI' increased significantly with gestational age in HLHS fetuses but not in controls. Values for systolic and diastolic peak velocities (E', A', S'), ET' and ICT' did not change significantly during gestation in either group.

CONCLUSION

Right ventricular function in HLHS is altered as early as in fetal life, well before palliative surgery is performed. Future research should provide further insight into ventricular remodeling during gestation in cases of HLHS. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Fetal left ventricular myocardial performance index: Defining normal values for Indian population and a review of literature

Objective:

The aim of this study was to determine normal values for fetal left ventricular (LV)-myocardial performance index (MPI) in Indian population and to assess its relation to advancing gestation and fetal heart rate (FHR).

Materials and Methods:

Two hundred pregnant women without any pregnancy-related complications and whose fetuses were shown to have structurally normal hearts were enrolled in this study. Doppler waveform involving simultaneous display of mitral inflow and LV outflow was obtained in all. Various intervals including isovolumetric contraction time (IVCT), isovolumetric relaxation time (IVRT), and ejection time (ET) were measured and then the MPI was calculated using the formula IVCT + IVRT/ET. Also the correlation between MPI and gestation age and FHR was assessed. We also reviewed the literature on the use of MPI for the assessment of fetal LV function.

Results:

The normal MPI in second and third trimester fetuses of Indian population was 0.42 ± 0.03. The mean IVCT was 33 ± 4 milliseconds (ms), mean IVRT was 39 ± 5 ms, and mean ET was 169 ± 9 ms. The mean heart rate was 148 ± 8 bpm and the mean PR interval was 111 ± 10 ms. There was no significant association of LV-MPI with either FHR or advancing gestation.

Conclusion:

MPI is a useful parameter for the assessment global cardiac function. MPI has the advantage of not being affected by FHR, ventricular size, and geometry or image quality. The review of literature shows its significant importance in monitoring complicated pregnancies.

Clinical chorioamnionitis at term V: umbilical cord plasma cytokine profile in the context of a systemic maternal inflammatory response

OBJECTIVE

Microbial invasion of the fetus due to intra-amniotic infection can lead to a systemic inflammatory response characterized by elevated concentrations of cytokines in the umbilical cord plasma/serum. Clinical chorioamnionitis represents the maternal syndrome often associated with intra-amniotic infection, although other causes of this syndrome have been recently described. The objective of this study was to characterize the umbilical cord plasma cytokine profile in neonates born to mothers with clinical chorioamnionitis at term, according to the presence or absence of bacteria and/or intra-amniotic inflammation.

MATERIALS AND METHODS

A cross-sectional study was conducted, including patients with clinical chorioamnionitis at term (n=38; cases) and those with spontaneous term labor without clinical chorioamnionitis (n=77; controls). Women with clinical chorioamnionitis were classified according to the results of amniotic fluid culture, broad-range polymerase chain reaction coupled with electrospray ionization mass spectrometry (PCR/ESI-MS) and amniotic fluid interleukin (IL)-6 concentration into three groups: 1) no intra-amniotic inflammation; 2) intra-amniotic inflammation without detectable microorganisms; or 3) microbial-associated intra-amniotic inflammation. A fetal inflammatory response syndrome (FIRS) was defined as an umbilical cord plasma IL-6 concentration >11 pg/mL. The umbilical cord plasma concentrations of 29 cytokines were determined with sensitive and specific V-PLEX immunoassays. Nonparametric statistical methods were used for analysis, adjusting for a false discovery rate of 5%.

RESULTS

1) Neonates born to mothers with clinical chorioamnionitis at term (considered in toto) had significantly higher median umbilical cord plasma concentrations of IL-6, IL-12p70, IL-16, IL-13, IL-4, IL-10 and IL-8, but significantly lower interferon gamma (IFN-γ) and tumor necrosis factor alpha (TNF)-α concentrations than neonates born to mothers with spontaneous term labor without clinical chorioamnionitis; 2) neonates born to mothers with clinical chorioamnionitis at term but without intra-amniotic inflammation had higher concentrations of IL-6, IL-12p70, IL-13, IL-4, IL-5, and IL-8, but lower IFN-γ, than neonates not exposed to clinical chorioamnionitis, suggesting that maternal fever in the absence of intra-amniotic inflammation leads to a change in the fetal cytokine network; 3) there were significant, positive correlations between maternal and umbilical cord plasma IL-6 and IL-8 concentrations (IL-6: Spearman correlation=0.53; P<0.001; IL-8: Spearman correlation=0.42; P<0.001), consistent with placental transfer of cytokines; 4) an elevated fetal plasma IL-6 (>11 pg/mL), the diagnostic criterion for FIRS, was present in 21% of cases (8/38), and all these neonates were born to mothers with proven intra-amniotic infection; and 5) FIRS was associated with a high concentration of umbilical cord plasma IL-8, IL-10 and monocyte chemoattractant protein (MCP)-1.

CONCLUSIONS

Neonates born to mothers with clinical chorioamnionitis at term had higher concentrations of umbilical cord plasma cytokines than those born to mothers without clinical chorioamnionitis. Even neonates exposed to clinical chorioamnionitis but not to intra-amniotic inflammation had elevated concentrations of multiple cytokines, suggesting that intrapartum fever alters the fetal immune response.

The Fetal Modified Myocardial Performance Index: Is Automation the Future?

The fetal modified myocardial performance index (Mod-MPI) is a noninvasive, pulsed-wave Doppler-derived measure of global myocardial function. This review assesses the progress in technical refinements of its measurement and the potential for automation to be the crucial next step. The Mod-MPI is a ratio of isovolumetric to ejection time cardiac time intervals, and the potential for the left ventricular Mod-MPI as a tool to clinically assess fetal cardiac function is well-established. However, there are wide variations in published reference ranges, as (1) a standardised method of selecting cardiac time intervals used in Mod-MPI calculation has not been established; (2) cardiac time interval measurement currently requires manual, inherently subjective placement of callipers on Doppler ultrasound waveforms; and (3) ultrasound machine settings and ultrasound system type have been found to affect Mod-MPI measurement. Collectively these factors create potential for significant inter- and intraobserver measurement variability. Automated measurement of the Mod-MPI may be the next key development which propels the Mod-MPI into routine clinical use. A novel automated system of Mod-MPI measurement is briefly presented and its implications for the future of the Mod-MPI in fetal cardiology are discussed.

Evaluation of right ventricular function in fetuses with hypoplastic left heart syndrome using tissue Doppler techniques

OBJECTIVE

The outcome of patients with hypoplastic left heart syndrome (HLHS) is influenced by right ventricular function. This study aimed to investigate whether differences in right ventricular function of fetuses with HLHS are present during gestation.

METHODS

This was a prospective study comprising 14 fetuses with HLHS (28 measurements obtained in total) and 28 normal control fetuses (31 measurements obtained in total). The two groups were matched for gestational age. Ultrasound M-mode was used to assess displacement of the tricuspid annulus. Spectral Doppler and myocardial tissue Doppler-derived inflow and outflow velocities were assessed. Tricuspid valve peak early wave to peak active wave (E/A) ratio, the early wave to early diastolic annular relaxation velocity (E/E') ratio and the tissue Doppler-derived myocardial performance index (MPI') were calculated.

RESULTS

E-wave velocity was significantly higher in fetuses with HLHS than in control fetuses (mean, 40.14 cm/s vs 35.47 cm/s; P < 0.05, respectively), and A-wave velocity in fetuses with HLHS showed a tendency for higher values in the right ventricle compared with normal control fetuses, but this did not reach statistical significance (61.16 cm/s vs 54.64 cm/s; P = 0.08). The E/A ratio increased during gestation in controls, but this increase was not seen in HLHS fetuses. Peak annular velocity during atrial contraction (A') and the E/E' ratio were significantly lower in controls than in HLHS fetuses: 9.50 cm/s vs 10.39 cm/s (P < 0.05) and 5.77 vs 7.37 (P < 0.05), respectively. There were no differences for right-ventricular MPI' or tricuspid annular plane systolic excursion between HLHS fetuses and controls.

CONCLUSION

The results of this study show that altered right ventricular function in HLHS infants may develop antenatally. It is hoped that confirmation of these findings using Doppler-independent techniques will lead to further exploration of ventricular function in HLHS fetuses. Consequently, parental counseling and postnatal management strategies could be influenced.

The (Pulsed-Wave) Doppler Fetal Myocardial Performance Index: Technical Challenges, Clinical Applications and Future Research

Functional cardiovascular assessment is becoming an increasingly important tool in the study of fetal pathology. The myocardial performance index (MPI) is a parameter measuring global myocardial function. Since its introduction, several studies have proposed methods to improve its reproducibility and have constructed normative reference ranges. Fetal heart evaluation using the MPI is technically challenging, requiring specific training and expertise, and a consensus has yet to be reached on the method of delineating the time periods used to calculate the index. Despite these limitations, it has been shown to be a useful and highly sensitive parameter of dysfunction in a number of fetal pathologies. Further research is warranted into the effect of pathology on MPI, parameters of unilateral cardiac strain that utilise MPI, and automation of the MPI to encourage incorporation of the MPI as a useful tool in clinical practice.

Fetal left and right ventricle myocardial performance index: defining normal values for the second and third trimesters--single tertiary center experience

Myocardial performance index (MPI), or Tei index, has become a commonly used parameter for the noninvasive, Doppler-derived assessment of global systolic and diastolic performance of the heart in both adults and children. Normal values have been established in adults and children; however, limited data exist in fetal hearts. The aim of this study was to further elucidate normal values of fetal left (LV) and right ventricle (RV) MPI values in second- and third-trimester fetuses and compare these values with other previously published data. This was a retrospective study to measure MPI in healthy fetuses. After Institutional Review Board approval, 2000 fetal echocardiography studies (FES) were acquired during a period of 4 years. Demographic parameters examined included gestational age (GA), maternal age (MA), and indication for fetal echocardiography. Fetuses with congenital heart disease, arrhythmias, or significant noncardiac fetal anomalies were excluded. The following echocardiography parameters were collected: LV ejection time (LVET), mitral valve close-to-open time (MVCO), RVET, tricuspid valve CO (TVCO), and fetal heart rate. For simplicity, LV and RV MPI values were calculated as follows: LV MPI = MVCO - LVET/LVET and RV MPI = TVCO - RVET/RVET. Four hundred twenty FES met the study criteria. LV MPI was evaluated in 230 and 190 FES in the second and third trimester, respectively. Of the 420 FES, 250 (150 in the second trimester and 100 in the third trimester) had all of the measurements required for RV MPI calculation. MA ranged between 16 and 49 years. Indications for FES included diabetes mellitus (N = 140; 33 %), suspected fetal anomalies on routine obstetrical ultrasound (N = 80; 20 %), autoimmune disorder (N = 60; 14 %), family history of CHD (N = 76; 18 %), medication exposure (N = 22; 5 %), increase nuchal thickness (N = 13; 3 %), and other indications (N = 29; 6 %). Averaged LV and RV MPI values were 0.464 ± 0.08 and 0.466 ± 0.09, respectively. Further analysis based on gestational period showed slightly greater LV and RV MPI values during the third compared with the second trimester, i.e., 0.48 and 0.49, respectively, with no statistically significant difference. There was no significant association of LV and RV MPI with heart rate. To our knowledge, this is the first study to establish normal values of fetal MPI based on a large fetal population from a single tertiary center. LV and RV MPI values were independent of GA and fetal heart rate. MPI is a useful parameter for the assessment of global cardiac function in the fetus and demonstrates good reproducibility with narrow interobserver and intraobserver variability. Its usefulness should be studied in fetal hearts with complex congenital anomalies.

Influence of equipment and settings on myocardial performance index repeatability and definition of settings to achieve optimal reproducibility

OBJECTIVE

To compare left myocardial performance index (MPI) values and reproducibility using different settings and ultrasound equipment in order to standardize optimal machine settings.

METHODS

Left MPI was prospectively evaluated by one observer performing conventional Doppler in 62 fetuses (28-36 weeks of gestational age) using different settings (changing sweep speed, gain and wall motion filter (WMF)) and two different ultrasound devices (Siemens Antares, Siemens; Voluson 730 Expert, GE Medical Systems). Intraclass coefficients of agreement (ICCs) were calculated using Bland-Altman analysis.

RESULTS

Using baseline settings on the Siemens, mean (SD) MPI was 0.44 (0.05) with an ICC of 0.81. Decreasing the sweep speed resulted in decreasing average MPI values (0.43) and decreasing ICC (0.61). Lowering gain also influenced average MPI values (0.46) and ICC (0.76). Raising gain resulted in similar MPI values (0.45) with better ICC (0.90) compared with baseline settings. Raising wall motion filter (WMF) provided the best ICC (0.94) compared with the other settings. Changing the ultrasound equipment resulted in an ICC of 0.64. The optimal settings to achieve the highest reproducibility in measurement of MPI were sweep speed 8, gain 60 dB and WMF 281 Hz for Siemens Antares and sweep speed 5, gain -10 dB and WMF 210 Hz for Voluson 730 Expert.

CONCLUSION

Changing ultrasound settings or equipment may affect the calculation and repeatability of measurement of MPI values. Strict standardization of methods decreases the variability of this parameter for fetal cardiac function assessment.

Modified myocardial performance index is not affected in fetuses with an isolated echogenic focus in the left ventricle

OBJECTIVES

We prospectively investigated the efficacy of modified myocardial performance index (mod-MPI) in the assessment of cardiac functions in fetuses with and without an isolated hyperechogenic focus (IHF) in the left ventricle and compared with conventional fetal echocardiography.

METHODS

The study group consisted of 50 fetuses with only an IHF in the left ventricle, without any other cardiac or extracardiac anomalies; 50 fetuses without IHF served as controls. All fetal echocardiographic studies were performed between 20th and 24th weeks of gestation. Left ventricular functions were evaluated with both conventional echocardiographic methods (peak velocity of the aortic valve, mitral E/A ratio, fractional shortening) and mod-MPI.

RESULTS

There was no statistically significant difference between the groups in terms of maternal age, BMI or gestational age at the time of examination (p > 0.05 for all). No statistically significant differences were found between the findings of conventional echocardiographic measurements and left ventricular mod-MPI between the study and control groups (p > 0.05 for all).

CONCLUSION

Fetal left ventricular mod-MPI is not affected by the presence of an IHF in the fetal left ventricle between 20th and 24th gestational weeks and thus it does not need to be assessed in this situation.

Characterization of the fetal blood transcriptome and proteome in maternal anti-fetal rejection: evidence of a distinct and novel type of human fetal systemic inflammatory response

BACKGROUND

The human fetus is able to mount a systemic inflammatory response when exposed to microorganisms. This stereotypic response has been termed the 'fetal inflammatory response syndrome' (FIRS), defined as an elevation of fetal plasma interleukin-6 (IL-6). FIRS is frequently observed in patients whose preterm deliveries are associated with intra-amniotic infection, acute inflammatory lesions of the placenta, and a high rate of neonatal morbidity. Recently, a novel form of fetal systemic inflammation, characterized by an elevation of fetal plasma CXCL10, has been identified in patients with placental lesions consistent with 'maternal anti-fetal rejection'. These lesions include chronic chorioamnionitis, plasma cell deciduitis, and villitis of unknown etiology. In addition, positivity for human leukocyte antigen (HLA) panel-reactive antibodies (PRA) in maternal sera can also be used to increase the index of suspicion for maternal anti-fetal rejection. The purpose of this study was to determine (i) the frequency of pathologic lesions consistent with maternal anti-fetal rejection in term and spontaneous preterm births; (ii) the fetal serum concentration of CXCL10 in patients with and without evidence of maternal anti-fetal rejection; and (iii) the fetal blood transcriptome and proteome in cases with a fetal inflammatory response associated with maternal anti-fetal rejection.

METHOD OF STUDY

Maternal and fetal sera were obtained from normal term (n = 150) and spontaneous preterm births (n = 150). A fetal inflammatory response associated with maternal anti-fetal rejection was diagnosed when the patients met two or more of the following criteria: (i) presence of chronic placental inflammation; (ii) ≥80% of maternal HLA class I PRA positivity; and (iii) fetal serum CXCL10 concentration >75th percentile. Maternal HLA PRA was analyzed by flow cytometry. The concentrations of fetal CXCL10 and IL-6 were determined by ELISA. Transcriptome analysis was undertaken after the extraction of total RNA from white blood cells with a whole-genome DASL assay. Proteomic analysis of fetal serum was conducted by two-dimensional difference gel electrophoresis. Differential gene expression was considered significant when there was a P < 0.01 and a fold-change >1.5.

RESULTS

(i) The frequency of placental lesions consistent with maternal anti-fetal rejection was higher in patients with preterm deliveries than in those with term deliveries (56% versus 32%; P < 0.001); (ii) patients with spontaneous preterm births had a higher rate of maternal HLA PRA class I positivity than those who delivered at term (50% versus 32%; P = 0.002); (iii) fetuses born to mothers with positive maternal HLA PRA results had a higher median serum CXCL10 concentration than those with negative HLA PRA results (P < 0.001); (iv) the median serum CXCL10 concentration (but not IL-6) was higher in fetuses with placental lesions associated with maternal anti-fetal rejection than those without such lesions (P < 0.001); (v) a whole-genome DASL assay of fetal blood RNA demonstrated differential expression of 128 genes between fetuses with and without lesions associated with maternal anti-fetal rejection; and (vi) comparison of the fetal serum proteome demonstrated 20 proteins whose abundance differed between fetuses with and without lesions associated with maternal anti-fetal rejection.

CONCLUSION

We describe a systemic inflammatory response in human fetuses born to mothers with evidence of maternal anti-fetal rejection. The transcriptome and proteome of this novel type of fetal inflammatory response were different from that of FIRS type I (which is associated with acute infection/inflammation).

Soluble ST2 in the fetal inflammatory response syndrome: in vivo evidence of activation of the anti-inflammatory limb of the immune response

OBJECTIVE

Inflammation is a mechanism of host response to infection, which can be harmful when inappropriately modulated. Soluble ST2 (sST2) is a decoy receptor of interleukin (IL)-33, and this complex modulates the balance in the Th1/Th2 immune response. Moreover, sST2 inhibits the production of pro-inflammatory cytokines in cooperation with an anti-inflammatory cytokine, IL-10. The objectives of this study were to: (1) determine whether umbilical cord plasma sST2 concentration differs between preterm neonates with and without funisitis and between those with and without the fetal inflammatory response syndrome (FIRS); and (2) evaluate the relationship between sST2 and IL-10 among neonates with funisitis and/or FIRS.

METHODS

Umbilical cord plasma was collected from neonates delivered prematurely due to preterm labor or preterm prelabor rupture of membranes with (n = 36), and without funisitis (n = 30). FIRS (umbilical cord IL-6 concentration ≥ 17.5 pg/mL) was identified in 29 neonates. Plasma sST2 and IL-10 concentrations were determined by enzyme linked immune sorbent assay.

RESULTS

The median umbilical cord plasma sST2 concentration was 6.7-fold higher in neonates with FIRS than in those without FIRS (median 44.6 ng/mL, interquartile range (IQR) 13.8-80.3 ng/mL versus median 6.7 ng/mL, IQR 5.6-20.1 ng/mL; p < 0.0001). Similarly, the median umbilical cord plasma sST2 concentration was 2.7-fold higher in neonates with funisitis than in those without funisitis (median 19.1 ng/mL; IQR 7.1-75.0 ng/mL versus median 7.2 ng/mL; IQR 5.9-23.1 ng/mL; p = 0.008). There was a strong positive correlation between sST2 and IL-10 in neonates with funisitis and/or FIRS (Spearman's Rho = 0.7, p < 0.0001).

CONCLUSION

FIRS and funisitis are associated with an elevation of umbilical cord plasma concentrations of soluble ST2. This protein represents an important mediator of the immune response in neonates diagnosed with FIRS by promoting an anti-inflammatory effect in association with IL-10.

Thrown off balance: the effect of antenatal inflammation on the developing lung and immune system

In recent years, translational research with various animal models has been helpful to answer basic questions about the effect of antenatal inflammation on maturation and development of the fetal lung and immune system. The fetal lung and immune systems are very plastic and their development can be conditioned and influenced by both endogenous and/or exogenous factors. Antenatal inflammation can induce pulmonary inflammation, leading to lung injury and remodeling in the fetal lung. Exposure to antenatal inflammation can induce interleukin-1α production, which enhances surfactant protein and lipid synthesis thereby promoting lung maturation. Interleukin-1α is therefore a candidate for the link between lung inflammation and lung maturation, preventing respiratory distress syndrome in preterm infants. Antenatal inflammation can, however, cause structural changes in the fetal lung and affect the expression of growth factors, such as transforming growth factor-beta, connective tissue growth factor, fibroblast growth factor-10, or bone morphogenetic protein-4, which are essential for branching morphogenesis. These alterations cause alveolar and microvascular simplification resembling the histology of bronchopulmonary dysplasia. Antenatal inflammation may also affect neonatal outcome by modulating the responsiveness of the immune system. Lipopolysaccharide-tolerance (endotoxin hyporesponsiveness/immunoparalysis), induced by exposure to inflammation in utero, may prevent fetal lung damage, but increases susceptibility to postnatal infections. Moreover, prenatal exposure to inflammation appears to be a predisposition for the development of adverse neonatal outcomes, like bronchopulmonary dysplasia, if the preterm infant is exposed to a second postnatal hit, such as mechanical ventilation oxygen exposure, infections, or steroids.

Right ventricular mechanics in the fetus with hypoplastic left heart syndrome

BACKGROUND

Right ventricular mechanics influence outcomes in patients with hypoplastic left heart syndrome (HLHS). The aim of this study was to determine whether differences in right ventricular performance have their origins in fetal life and if the architectural character of the hypoplastic left ventricle affects right ventricular mechanics.

METHODS

The first complete fetal echocardiograms after 17 weeks' gestation were reviewed in 84 fetuses with HLHS and in 115 gestational age-matched normal controls. Inflow, outflow, and myocardial tissue Doppler velocities were measured. E/A and E/e' ratios and right ventricular myocardial performance index were calculated.

RESULTS

In fetuses with HLHS, there were lower tricuspid E/A ratios (mean, 0.6 ± 0.1 vs 0.7 ± 0.1; P < .001), higher E/e' ratios (mean, 8.1 ± 2.6 vs 7.0 ± 1.3; P = .006), and higher right ventricular myocardial performance indices (mean, 0.47 ± 0.14 vs 0.40 ± 0.10; P < .001) compared with controls. Among fetuses with HLHS grouped according to left ventricular architecture, those with left ventricular endocardial fibroelastosis had the most striking differences in right ventricular mechanics.

CONCLUSIONS

Right ventricular mechanics are different from normal in fetuses with HLHS and are influenced by the presence of left ventricular endocardial fibroelastosis. These differences precede the imposition of undue loading conditions as a consequence of surgical palliation and may offer clues to the development of later right ventricular failure.

Interleukin-19 in fetal systemic inflammation

OBJECTIVE

The fetal inflammatory response syndrome (FIRS) is considered the fetal counterpart of the systemic inflammatory response syndrome (SIRS), which can be caused by infection and non-infection-related insults. Although the initial response is mediated by pro-inflammatory signals, the control of this response is achieved by anti-inflammatory mediators which are essential for the successful outcome of the affected individual. Interleukin (IL)-19 is capable of stimulating the production of IL-10, a major anti-inflammatory cytokine, and is a potent inducer of the T-helper 2 (Th2) response. The aim of this study was to determine if there is a change in umbilical cord plasma IL-19 and IL-10 concentrations in preterm neonates with and without acute funisitis, the histologic counterpart of FIRS.

METHODS

A case-control study was conducted including 80 preterm neonates born after spontaneous labor. Neonates were classified according to the presence (n = 40) or absence of funisitis (n = 40), which is the pathologic hallmark of FIRS. Neonates in each group were also matched for gestational age. Umbilical cord plasma IL-19 and IL-10 concentrations were determined by ELISA.

RESULTS

1) The median umbilical cord plasma IL-19 concentration was 2.5-fold higher in neonates with funisitis than in those without funisitis (median 87 pg/mL; range 20.6-412.6 pg/mL vs. median 37 pg/mL; range 0-101.7 pg/mL; p < 0.001); 2) newborns with funisitis had a significantly higher median umbilical cord plasma IL-10 concentration than those without funisitis (median 4 pg/mL; range 0-33.5 pg/mL vs. median 2 pg/mL; range 0-13.8 pg/mL; p < 0.001); and 3) the results were similar when we included only patients with funisitis who met the definition of FIRS by umbilical cord plasma IL-6 concentrations ≥ 17.5 pg/mL (p < 0.001).

CONCLUSION

IL-19 and IL-10 are parts of the immunologic response of FIRS. A subset of fetuses with FIRS had high umbilical cord plasma IL-19 concentrations. In utero exposure to high systemic concentrations of IL-19 may reprogram the immune response.

Development of Australian reference ranges for the left fetal modified myocardial performance index and the influence of caliper location on time interval measurement

OBJECTIVES

To construct gestational age-adjusted reference ranges of the left fetal modified myocardial performance index (Mod-MPI) in the Australian population and assess the influence of valve click caliper position on constituent time intervals and the Mod-MPI.

METHODS

This is a prospective longitudinal study of 117 normal singleton fetuses undergoing 318 ultrasound scans at 4-6 weekly intervals between 18 and 38 weeks of gestation. The isovolumetric contraction time (ICT), isovolumetric relaxation time (IRT), and ejection time (ET) were measured at 3 different caliper positions in each fetus: beginning of the original valve clicks ('original'), beginning of the reflected valve clicks ('reflected'), and peak of valve clicks ('peak'). The Mod-MPI was calculated as (ICT + IRT)/ET.

RESULTS

The Mod-MPI increased throughout gestation with means ± SD of 0.42 ± 0.05 'reflected' and 'peak' versus 0.49 ± 0.03 'original' at 19 weeks, and means of 0.46 ± 0.05 'reflected and peak' versus 0.51 ± 0.08 'original' at 36 weeks. Throughout gestation, ICT remained fairly constant and IRT increased, while ET decreased with 'original' click and remained constant for 'reflected' and 'peak' clicks. A modest increase in Mod-MPI was seen with increasing fetal heart rate. Analysis of repeatability for the 3 methods showed the following ICCs: 'original', 0.797 (95% CI 0.762-0.829); 'reflected', 0.809 (95% CI 0.775-0.839), and 'peak', 0.799 (95% CI 0.764-0.831).

CONCLUSIONS

Detailed exploration of the morphology of mitral and aortic valve closure and opening clicks shows how selection of different phases of these clicks may significantly influence the Mod-MPI. We recommend that the peak of the valve clicks be standardized between research groups.

Reproducibility of constituent time intervals of right and left fetal modified myocardial performance indices on pulsed Doppler echocardiography: a short report

OBJECTIVE

To assess reproducibility of constituent time intervals measured by pulsed Doppler echocardiography for calculation of the right and left fetal myocardial performance indices (MPIs).

METHODS

This was a prospective study of 30 normal singleton pregnancies (19-36 weeks). In each, five different time intervals were measured from the Doppler waveform and four repeated measures were taken for each time interval. Three were from the left heart: isovolumetric contraction time (ICT), isovolumetric relaxation time (IRT) and ejection time (ET); two were from the right heart: 'a-interval' and 'b-interval'. The left and right modified MPIs (Mod-MPIs) generated by these constituent time intervals were also evaluated. Two operators evaluated the reproducibility of all measures.

RESULTS

There was generally good intra- and interobserver reproducibility for all time intervals and resultant Mod-MPIs: ICT, range, 19-43 ms with intraclass correlation coefficient (ICC), 0.91 (95% CI, 0.85-0.95); ET, range, 160-184.8 ms with ICC, 0.90 (95% CI, 0.84-0.95); IRT, range, 35.8-48.5 ms with ICC, 0.67 (95% CI, 0.52-0.81); a-interval, range 208-265 ms with ICC, 0.89 (95% CI, 0.82-0.94); b-interval, range, 163.1-188.3 ms with ICC, 0.82 (95% CI, 0.71-0.90); left Mod-MPI, range, 0.33-0.48 with ICC, 0.84 (95% CI, 0.74-0.91); right Mod-MPI, range, 0.21-0.49 with ICC, 0.82 (95% CI, 0.71-0.90). The 95% limits of agreement showed no statistically significant difference in measurements between the two examiners for all time intervals.

CONCLUSION

This is the first study to evaluate the reproducibility of the component time intervals of both right and left fetal Mod-MPIs in the second and third trimesters and supports the reproducibility of fetal functional cardiac assessment. The IRT is the main source of variation for the left Mod-MPI so should be the focus of further investigation. Even using two separate pulsed-wave Doppler gates and therefore separate cardiac cycles, the right Mod-MPI is reproducible.

Evaluation of conventional Doppler fetal cardiac function parameters: E/A ratios, outflow tracts, and myocardial performance index

Structural evaluation of the fetal heart is well established. Functional evaluation using pulsed-wave Doppler may also be performed. E/A ratios express the relationship between the maximal velocities of the E and A waveforms of ventricular filling. In normal fetuses, E/A ratios are usually <1 but show a constant increment during gestation, mainly related to the increment of the E wave. In intrauterine growth restriction (IUGR) fetuses, E/A ratios are lower compared to values in normally grown fetuses at the same gestational age. Cardiac outflows provide information on the time-velocity integral that, combined with the vessel area, allows calculation of the left and right cardiac outputs. In normal fetuses there is a predominance of the right ventricle (55-60%) in contributing to the combined cardiac output. In IUGR fetuses this predominance shifts to the left ventricle in order to increase the flow to the upper part of the fetal body and brain. The myocardial performance index (MPI) also provides information on systolic and diastolic cardiac function. The MPI is an early and consistent marker of cardiac dysfunction which becomes altered in early stages of chronic hypoxia or in cases with cardiac overload such as in twin-to-twin transfusion syndrome.

Fetal cardiac function: technical considerations and potential research and clinical applications

Fetal echocardiography was initially used to detect structural anomalies but has more recently also been proposed to assess fetal cardiac function. This review summarizes technical issues and limitations in fetal cardiac function evaluation, as well as its potential research and clinical applications. Functional echocardiography has been demonstrated to select high-risk populations and to be associated with outcome in several fetal conditions including intrauterine growth restriction, twin-to-twin transfusion syndrome, maternal diabetes, and congenital diaphragmatic hernia. Fetal heart evaluation is challenging due to the smallness and high heart rate of the fetus and restricted access to the fetus far from the transducer. Due to these limitations and differences in cardiac function which are related to fetal maturation, cardiovascular parameters should be validated in the fetus and used with caution. Despite these precautions, in expert hands and with appropriate ultrasound equipment, evaluation of cardiac function is feasible in most fetuses. Functional fetal echocardiography is a promising tool that may soon be incorporated into clinical practice. Research is warranted to further refine the contribution of fetal cardiac assessment to the diagnosis, monitoring, or prediction of outcomes in various fetal conditions.

Fetal left modified myocardial performance index: technical refinements in obtaining pulsed-Doppler waveforms

OBJECTIVE

To assess the influence of machine settings (wall motion filter (WMF), angle of insonation, Doppler aliasing) and phase of valve clicks on repeatability of measurement of the fetal left modified myocardial performance index (Mod-MPI).

METHODS

Fetal left Mod-MPI was evaluated prospectively in 157 morphologically normal fetuses at 19-36 weeks' gestation. In a baseline cohort, a previously published technique and settings were used for measurement of Mod-MPI. In a second cohort, the influence of WMF, angle of insonation, Doppler aliasing and selection of the phase of the valve clicks on repeatability of measurement of Mod-MPI was assessed.

RESULTS

The intraclass correlation coefficient (ICC) for measurement repeatability in the baseline cohort was 0.22. Increase in WMF to 300 Hz or 500 Hz was associated with an increase in ICC to 0.60 and 0.55, respectively. An angle of insonation of < 15° was associated with an increase in ICC to 0.79 and 0.78 at a WMF of 300 and 500 Hz, respectively. A WMF of 300 Hz, angle of insonation of < 15° and absence of aliasing was associated with an increase in ICC to 0.85 and 0.87 at the beginning and peak of the valve click, respectively. Mod-MPI ranged from 0.35 to 0.48. An increase in calculated MPI was associated with increasing WMF, selection of the beginning vs. peak of the valve clicks and increase in angle of insonation. The presence or absence of aliasing had no effect.

CONCLUSIONS

Refinement of machine settings improves repeatability of Mod-MPI, as does selection of the peak of the valve click. We suggest a consensus be reached as to the precise measurement of MPI, but for the moment would suggest: WMF, 300 Hz; angle of insonation, < 15°; avoiding Doppler aliasing; and selection of valve click peak. Systematic variation in measurement of time intervals may be responsible for the widely varying published normal ranges for Mod-MPI.

Functional assessment of the fetal heart: a review

The purpose of this review is to evaluate the current modalities available for the assessment of fetal cardiac function. The unique anatomy and physiology of the fetal circulation are described, with reference to the difference between in-utero and ex-utero life. M-mode, early/atrial ratio, myocardial performance index, three-dimensional and four-dimensional ultrasound, tissue Doppler including strain and strain rate, speckle tracking, magnetic resonance imaging and venous flow assessment are described. The modalities are analyzed from the perspective of the clinician and certain questions are posed. Does the modality assess systolic function, diastolic function or both? Is it applicable to both ventricles? Does it require extensive post-processing or additional hardware, or does it make use of technology already available to the average practitioner? The reproducibility and reliability of the techniques are evaluated, with reference to their utility in clinical decision-making. Finally, directions for future research are proposed.

Temporal frequency requirements for tissue velocity imaging of the fetal heart

OBJECTIVES

The high velocity and short duration of myocardial motion requires a high sampling rate to obtain adequate temporal resolution; this issue becomes even more important when taking into consideration the high fetal heart rate. In this study we have established optimal sampling requirements for assessing the duration of various cardiac cycle events and myocardial velocities of the fetal heart using color-coded tissue velocity imaging (TVI).

METHODS

Recordings from 30 fetuses were acquired at an initial frame rate of 180-273 frames/s. All TVI recordings were performed from an apical four-chamber view and stored as cineloops of five to 10 consecutive cardiac cycles for subsequent offline analysis using software enabling a reduction in frame rate. Different components of the myocardial velocity curve, obtained from the basal part of the ventricular septum, were measured at the initial frame rate and compared with their equivalents at gradually decreased frame rates.

RESULTS

As acquisition frame rate was reduced, there was a marked increase in deviation from the initial values, resulting in an underestimation of all systolic and diastolic velocities. For the measured durations, there was a clear tendency to underestimate isovolumetric contraction and relaxation, and a clear tendency to overestimate ventricular ejection and diastolic E-wave and A-wave. An acceptable ⩽ 5% deviation from the value obtained at the highest frame rate corresponded to measurements obtained at above 150-200 frames/s.

CONCLUSIONS

A high sampling rate of at least 200 frames/s is necessary for adequate reconstruction of TVI data for the fetal heart. Frame rates that are too low result in considerable loss of temporal and velocity information.