The fetal circulation

Bladder hemangioma: case report

OBJECTIVE

Bladder hemangioma is a benign rare lesion. There are no pathognomonic clinical signs and management is controversial due to the bleeding risk. We report a bladder cavernous hemangioma resolved using bipolar transurethral resection.

METHODS

We review the case of a female patient who presented with asymptomatic hematuria. On cystoscopy we discovered a reddish sessile lesion compatible with bladder hemangioma. We describe the diagnostic work up, surgical management and review other therapeutic alternatives for these lesions.

RESULTS

Fifty five year old healthy female patient consulting for total painless hematuria. Cystoscopic evaluation revealed a 1 cm diameter sessile reddish elevated lesion near the bladder neck. We performed a transurethral endoscopic resection using the Gyrus Bipolar resectoscope®. Pathologic report concluded cavernous angioma.

CONCLUSION

Bladder hemangiomas are benign and rare lesions. Clinical presentation has no pathognomonic signs although gross painless hematuria is the most frequent complain. Management is controversial due to the bleeding risk of this highly vascularized lesion. However, it appears that small lesions could be treated using transurethral resection. Although they have a benign course, follow up is mandatory to detect recurrence or residual disease.

Characterizing the right ventricle: advancing our knowledge

Our ability to evaluate the right ventricle (RV) in pulmonary hypertension has traditionally been quite limited: the RV's complex anatomy is not adequately represented by 2-dimensional imaging, and our understanding of what is an adaptive and maladaptive RV response is incomplete. However, measures of RV function appear to be a strong predictor of survival in pulmonary hypertension. This is, therefore, a promising area for future study. To more fully understand the challenges and opportunities in this area, this article provides a review of RV embryology and anatomy, current assessment of the RV function, animal models of RV function, RV-pulmonary artery coupling, and how translating lessons from studies of the left ventricle may increase our knowledge of the RV.

Metabolomic analysis reveals differences in umbilical vein plasma metabolites between normal and growth-restricted fetal pigs during late gestation

Intrauterine growth restriction (IUGR) remains a major problem for both human health and animal production due to its association with high rates of neonatal morbidity and mortality, low efficiency of food utilization, permanent adverse effects on postnatal growth and development, and long-term health and productivity of the offspring. However, the underlying mechanisms for IUGR are largely unknown. In this study, one IUGR fetus and one normal body weight (NBW) fetus were obtained from each of 9 gilts at each of 2 gestational ages (d 90 and 110). Metabolomes of umbilical vein plasma in IUGR and NBW fetuses were determined by MS, while hormones, amino acids, and related metabolites in maternal and fetal plasma were measured using assay kits and chromatographic methods. Metabolites (including glucose, urea, ammonia, amino acids, and lipids) in umbilical vein plasma exhibited a cluster of differences between IUGR and NBW fetuses on d 90 and 110 of gestation. These changes in the IUGR group are associated with disorders of nutrient and energy metabolism as well as endocrine imbalances, which may contribute to the retardation of fetal growth and development. The findings help provide information regarding potential mechanisms responsible for IUGR in swine and also have important implications for the design of effective strategies to prevent, diagnose, and treat IUGR in other mammalian species, including humans.

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.

A preliminary retrospective study about the relationship between ductus venosus Doppler indices, nuchal translucency (NT) and biochemical markers in the first and second trimester screening tests

In our study, we tried to assess the relation between ductus venosus Doppler indices [pulsatility index (PI), resistance index (RI) and S/D] and first-trimester screening markers (MoM of serum pregnancy-associated plasma protein A, pappalysin 1 (PAPP-A), MoM of serum free β-human chorionic gonadotrophin (β-hCG), and nuchal translucency (NT) and second trimester screening markers (MoM of serum α-fetoprotein, MoM of serum total β-hCG and MoM of serum estriol). We analyzed the data of 121 singleton pregnancies. Roche cobas e 601ECLIA (electrochemiluminescence immunoassay) was used to measure MoM of serum PAPP-A and Roche cobas e 602 ECLIA (electrochemiluminescence immunoassay) was used to measure MoM of serum free β-hCG in the first trimester. Beckman Coulter Access 2 Immunoassay was used to measure MoM of serum α-fetoprotein, MoM of serum total β-hCG and MoM of serum estriol in the second trimester. The first author performed all ultrasound screenings and ductus venosus Doppler studies. What we found new in our study is presented as following; MoM of serum α-fetoprotein had a negative correlation with RI of ductus venosus Doppler, MoM of serum estriol had a negative correlation with RI of ductus venosus Doppler and MoM of serum estriol had a negative correlation with S/D of ductus venosus doppler. The results of our study suggest that ductus venosus Doppler can be used to increase the effectiveness of the second trimester screening test.

The methodology of Doppler-derived central blood flow measurements in newborn infants

Central blood flow (CBF) measurements are measurements in and around the heart. It incorporates cardiac output, but also measurements of cardiac input and assessment of intra- and extracardiac shunts. CBF can be measured in the central circulation as right or left ventricular output (RVO or LVO) and/or as cardiac input measured at the superior vena cava (SVC flow). Assessment of shunts incorporates evaluation of the ductus arteriosus and the foramen ovale. This paper describes the methodology of CBF measurements in newborn infants. It provides a brief overview of the evolution of Doppler ultrasound blood flow measurements, basic principles of Doppler ultrasound, and an overview of all used methodology in the literature. A general guide for interpretation and normal values with suggested cutoffs of CBFs are provided for clinical use.

Comparison of global and regional right and left ventricular longitudinal peak systolic strain, strain rate and velocity in healthy fetuses using a novel feature tracking technique

AIMS

To compare the feature tracking derived measurements of the right (RV) and left ventricular (LV) myocardium in healthy fetuses and evaluate the correlation with advancing pregnancy.

METHODS

Global and segmental longitudinal peak systolic strain, strain rate and velocity of the RV and LV myocardium were assessed with feature tracking technique in 150 healthy fetuses (13-39, median 22 weeks).

RESULTS

RV global and free wall strain and strain rate values were significantly higher than those in the LV segments (P<0.001 and P<0.001). In all segments on both ventricles longitudinal peak systolic velocity measurements exhibited a significant base to apex gradient (P<0.001) and increased with advancing pregnancy (P<0.001). LV global strain and strain rate values remained constant throughout gestation, whereas RV measurements decreased (P<0.05). With advancing pregnancy the difference between RV and LV global longitudinal velocity increased significantly, whereas the difference of strain and strain rate decreased significantly.

CONCLUSION

RV deformation parameters and velocity values are significantly higher compared to LV values. LV deformation parameters are stable throughout gestation, whereas RV measurements decrease significantly. The difference between global RV and LV myocardial values were significant throughout gestation, velocity values increased, whereas deformation parameters decreased.

The role of blood flow distribution in the regulation of cerebral oxygen availability in fetal growth restriction

Fetal growth restriction (FGR) elicits hemodynamic compensatory mechanisms in the fetal circulation. These mechanisms are complex and their effect on the cerebral oxygen availability is not fully understood. To quantify the contribution of each compensatory mechanism to the fetal cerebral oxygen availability, a mathematical model of the fetal circulation was developed. The model was based on cardiac-output distribution in the fetal circulation. The compensatory mechanisms of FGR were simulated and their effects on cerebral oxygen availability were analyzed. The mathematical analysis included the effects of cerebral vasodilation, placental resistance to blood flow, degree of blood shunting by the ductus venosus and the effect of maternal-originated placental insufficiency. The model indicated a unimodal dependency between placental blood flow and cerebral oxygen availability. Optimal cerebral oxygen availability was achieved when the placental blood flow was mildly reduced compared to the normal flow. This optimal ratio was found to increase as the hypoxic state of FGR worsens. The model indicated that cerebral oxygen availability is increasingly dependent on the cardiac output distribution as the fetus gains weight.

Aortic isthmus and cardiac monitoring of the growth-restricted fetus

Aortic isthmus acts as an arterial watershed between the cerebral and placental circulations, connecting 2 parallel fetal ventricular pumps. It plays a crucial role in the fetal circulatory dynamics. Information about aortic isthmus blood flow may improve the management of sick fetuses. However, perceived technical difficulties limit the clinical use of aortic isthmus Doppler for fetal hemodynamic monitoring. Changes in aortic isthmus blood flow pattern seem to reflect fetal cardiovascular status accurately and predict perinatal and long-term neurodevelopmental outcome in intrauterine growth restriction. This review evaluates the available scientific information and discusses the role of aortic isthmus in fetal circulation.

Assessment of right ventricular global and regional longitudinal peak systolic strain, strain rate and velocity in healthy fetuses and impact of gestational age using a novel speckle/feature-tracking based algorithm

OBJECTIVE

To evaluate the correlation between feature tracking-derived measurements of the right ventricular myocardium and gestational age in healthy fetuses.

METHODS

Global and segmental longitudinal peak systolic strain, strain rate and velocity values of the right ventricular myocardium were assessed by a novel feature-tracking technique in 150 healthy fetuses at between 13 and 39 weeks' gestation. Reference ranges were constructed with respect to gestational age, and inter- and intraobserver variability was analyzed.

RESULTS

Strain, strain rate and velocity exhibited a segmental base to apex gradient (P < 0.001). Global longitudinal peak systolic velocities increased significantly across the gestational age range considered (P < 0.001), whereas global longitudinal peak systolic strain and strain rate (taken as absolute values) decreased significantly (P < 0.001 and P < 0.001). Inter- and intraobserver variability of global right ventricular peak systolic strain, strain rate and velocity was acceptable. The SDs of measurement error between the two observers were 5.9%, 0.7/s and 0.5 cm/s, respectively.

CONCLUSIONS

Global myocardial peak systolic velocities of the right ventricle increase with gestational age whereas global myocardial peak absolute systolic strain and strain rate significantly decrease throughout gestation. This novel angle-independent technique offers a new non-invasive approach for quantifying and monitoring fetal myocardial function throughout gestation.

Ductus Venosus: A Love Story of 14 Years

Ductus venosus is a tiny vessel with a central role in fetal circulation. Combining B-mode with color and pulsed Doppler is feasible to identify this vessel and evaluate the blood flow waveform at 11 to 13 weeks. The higher prevalence of abnormal A-wave in fetuses with abnormal karyotype and/or cardiac defects turned DV evaluation into a useful marker for chromosomal abnormalities and cardiopathies. Even when combined with nuchal translucency (NT) or biochemical markers, DV blood flow evaluation contributes to an increase in sensitivity and reduces false-positive rate. Abnormal ductal flow is also related to a worse fetal and perinatal outcome. In monochorionic twin pregnancies, in addition to NT measurement at 11 to 14 weeks, the Doppler assessment of DV blood flow increases relevantly the performance of screening for those at higher risk of developing twin-to-twin transfusion syndrome. This story of 14 years surely contributed to change the way first trimester screening is being implemented.

Ductus venosus velocimetry in monitoring pregnancy in women with pregestational diabetes mellitus

OBJECTIVE

The purpose of this research was to assess the ability of ductus venosus (DV) Doppler velocimetry to predict adverse perinatal outcome in pregnancies complicated by pre-existing diabetes mellitus.

METHODS

This was a prospective study conducted at a tertiary referral obstetric facility in Brisbane, Australia. The study group included women with pregestational diabetes mellitus who delivered in the hospital between 1 January 1995 and 31 December 2006. The DV Doppler index was defined as abnormal if the DV peak velocity index for veins (PVIV) was equal to or greater than the 95(th) percentile for gestation. Adverse perinatal outcome included one or more of the following criteria: small-for-gestational-age infant; Cesarean section for non-reassuring fetal status; fetal acidemia at delivery; a 1-min Apgar score of <or= 3; a 5-min Apgar score of < 7; hypoxic ischemic encephalopathy; and stillbirth or neonatal death. The maternal characteristics and perinatal outcomes of pregnancies with normal or abnormal DV Doppler indices were compared.

RESULTS

Eighty-two pregestational diabetic pregnancies were studied and an abnormal DV-PVIV was identified in 25 (30.5%). Adverse perinatal outcome was identified in eight of 25 (32.0%) pregnancies with an abnormal DV-PVIV compared to seven of 57 (12.3%) pregnancies with a normal DV-PVIV (P < 0.05). The sensitivity of the DV-PVIV in predicting adverse perinatal outcomes in pregestational diabetic pregnancies was 53.3%, the specificity was 74.6%, the positive predictive value was 32.0% and the negative predictive value was 87.7%.

CONCLUSION

It may be useful to include DV-PVIV in the antenatal screening of pregnancies complicated by pregestational diabetes.

Umbilical vein anomaly in fetuses with Down syndrome

OBJECTIVE

To describe the prevalence of abnormal umbilical vein (UV) anatomy in fetuses with Down syndrome.

METHODS

This was a retrospective survey covering a 24-month period of fetuses with a genetic diagnosis of Down syndrome following a routine early second-trimester (12-16-week) detailed fetal anomaly scan at a single academic tertiary referral center. In our unit this exam includes fetal umbilicoportal venous system evaluation.

RESULTS

During the study period, 37 fetuses were diagnosed with Down syndrome and had a detailed early anatomy scan. In four (11%) the detailed early anomaly scan revealed that the UV was connected to the hepatic portion of the inferior vena cava (IVC) at a position lower than its usual site. Their average gestational age at diagnosis was 13 + 6 (range, 11 + 6 to 15 + 2) weeks. Three of the four fetuses had a nuchal translucency thickness of 3-4 mm. In one fetus there was an additional finding of significant tricuspid regurgitation and the one with normal nuchal translucency thickness had an atrioventricular septal defect (atrioventricular canal) and umbilical cord hernia. During the same period three of 2500 (0.12%) fetuses with normal karyotype demonstrated similar anomalous insertion of the UV into the IVC, creating a portocaval shunt which had normal ductus venosus-like Doppler flow in all three cases. The odds ratio for abnormal umbilicoportal venous system in fetuses with Down syndrome compared with the normal population was 107.4 (95% CI, 19.2-637.1).

CONCLUSIONS

Fetuses with Down syndrome demonstrate an increased prevalence of abnormal connection of the UV to the IVC.

Systemic and cerebral hemodynamics during the transitional period after premature birth

Little is known about the effect on clinically relevant outcomes of the complex hemodynamic changes occurring during adaptation to extrauterine life in preterm neonates, particularly in very low birth weight neonates. As cardiovascular adaptation in this extremely vulnerable patient population is complicated by immaturity of all organ systems, especially that of the cardiorespiratory, central nervous, and endocrine systems, maladaptation has been suspected, but not necessarily proven, to contribute to mortality and long-term morbidities. This article describes recent advances in the understanding of hemodynamic changes in very low birth weight neonates during postnatal transition, and reviews the complex and developmentally regulated interaction between systemic and cerebral hemodynamics and the effect of this interaction on clinically relevant outcomes.

Polybrominated diphenyl ethers cause oxidative stress in human umbilical vein endothelial cells

Polybrominated diphenyl ethers (PBDEs) are used as flame retardants to prevent combustion in consumer products, such as electronics, construction materials, and textiles and, therefore, have become important commercial substances. PBDEs were also detected in maternal blood, breast milk, umbilical cord blood, and cord tissue, thereby indicating that fetuses were also exposed to PBDEs. The purpose of this study is to identify the effect of PBDEs on human umbilical vein endothelial cells (HUVECs). Cultured HUVECs were exposed to a commercial mixture of penta-BDE (DE71), octa-BDE (DE79), and deca-BDE (DE83). Each gene expression that was altered in DNA microarray was confirmed by real-time reverse transcription-polymerase chain reaction and Western blotting analysis. The results indicated that gene expressions concerning antioxidant system, i.e., thioredoxin family, 24-dehydrocholesterol reductase (DHCR24), and tumor suppressor protein p53, were altered by PBDEs exposure in HUVECs. Moreover, it was demonstrated that thioredoxin-interacting protein (TXNIP) was a target gene in exposure to DE71 and DE79 in HUVECs, by drastically decreasing time-dependent TXNIP expression in HUVECs.

The diagnosis of the cause of the death of Venerina

Venerina (little Venus) is the name given to a wax model representing a pregnant young woman that was created in Florence (Italy) by Clemente Susini (1754-1814) in 1782. It is currently located in the historic Science Museum of the University of Bologna. The model was constructed so as to enable removal of the thoracic and abdominal walls and various organs, exposing the heart, diaphragm and an opened uterus with a well-developed fetus. The woman is small, about 145 cm (4' 9') tall and of delicate build; she looks like a teenage girl. We know that Clemente Susini worked directly with the cadaver and copied the anatomical preparation exactly. This artist often represented the true structure using a wax mould; the existence of two other versions of this specimen suggests that this model was made in this way. Therefore, Venerina's body may be a faithful representation of a young woman who died while pregnant. Observation of the body confirms that the organs are normal, except for the heart and great vessels. The walls of both ventricles are of equal thickness and the ventricles themselves of approximately equal size. The arch of the aorta and the enlarged pulmonary trunk are connected by a short duct about 3.5 mm in diameter. If this structure represents an open arterial duct, we can deduce that the two ventricles worked under the same conditions of blood pressure, hence their equal wall thickness. If the young woman died from this congenital disease, the cause of death has been diagnosed on a wax model of her body after more than two centuries.

Cerebral blood flow and metabolism in the developing fetus

The inaccessibility of the human fetal brain to studies of perfusion and metabolism has impeded progress in the understanding of the normal and abnormal systems of oxygen substrate supply and demand. Consequently, current understanding is based on studies in fetal animals or in the premature infant (ex utero fetus), neither of which is ideal. Despite promising developments in fetal magnetic resonance imaging (MRI) and Doppler ultrasound, major advances in fetal neurodiagnostics will be required before rational and truly informed brainoriented care of the fetus becomes feasible.

Evaluation of fetal cerebrovascular circulation and brain development: the role of ultrasound and Doppler

The human fetal brain is protected from pressure changes by autoregulation of the cerebral circulation. However, antenatal intrauterine cerebrovascular events are found to play an important role in the pathogenesis of perinatal brain damage. Changes in placental vascular resistance, cardiac contractibility, vessel compliance, and blood viscosity alter the normal dynamics of fetal cerebral circulation. The introduction of various sonographic techniques and the collection of data from the arterial and venous cerebral circulation provide a powerful tool for the evaluation of physiological and pathological hemodynamic events. Anatomic and physiological considerations of cerebral vasculature in healthy and disease states are relevant in studying brain development and variations in fetal brain blood perfusion. The major role of ultrasound and Doppler modalities in the evaluation of fetal cerebrovascular circulation is enabled by implementation of these considerations. Changes in flow characteristics in fetal cerebral vasculature can be used for clinical decision making in situations of fetal compromise, such as growth restriction and anemia.

Fetal-to-neonatal transition--what is normal and what is not?

These articles review the physiologic adaptations occurring during the transition from fetal to neonatal life and examine common red flags which may alert care providers to an infant experiencing delayed transition or an underlying disease process, congenital abnormality, or birth injury.

Fetal aortic isthmus blood flow and the fraction of cardiac output distributed to the upper body and brain at 11-20 weeks of gestation

OBJECTIVE

To measure serial changes in fetal aortic isthmus (AI) blood flow and estimate the fraction of fetal cardiac output distributed to the upper body, including the brain, at 11-20 weeks of gestation.

METHODS

Using pulsed-wave Doppler and two-dimensional ultrasound, blood flow velocities and inner diameter of the AI, aortic valve (AV) and pulmonary valve (PV) were measured longitudinally in 143 fetuses and volume blood flows (Q) were calculated for each site using the formula: Q (mL/min) = pix (diameter/2)(2) x velocity time integral x heart rate x 60. The sum of Q(av) and Q(pv) constituted the combined cardiac output (CCO) and the fraction (%) of the upper body (including brain) blood flow was calculated as: (Q(av)-Q(ai))x100/CCO.

RESULTS

AI blood velocities as well as the vessel diameter increased with advancing gestation, resulting in a significant increase in Q(ai) from 1.9 to 40.5 mL/min during weeks 11 to 20. The AI peak systolic velocity increased from 29 to 63 cm/s, end-diastolic velocity from 1.2 to 5.2 cm/s, and the time-averaged maximum velocity from 11 to 22 cm/s, resulting in a fairly stable pulsatility index (PI) of 2.4-2.6 and resistance index (RI) of 0.91-0.94. On average, 75% of blood ejected by the left ventricle (which represented about 35% of the CCO) passed through the AI to the descending aorta. The fraction of CCO distributed to the upper body, including the brain, was estimated as approximately 13%.

CONCLUSION

We have established longitudinal reference ranges for fetal AI diameter, blood flow velocities, PI, RI and volume blood flow at 11-20 weeks of gestation. The human fetus appears to direct a relatively small fraction (13%) of its CCO to the upper body, including the brain, during this period of pregnancy.

Development of an artificial placenta I: pumpless arterio-venous extracorporeal life support in a neonatal sheep model

PURPOSE

Effective treatment of respiratory failure in premature infants remains an unsolved problem. The development of an artificial placenta, in the form of a pumpless arteriovenous extracorporeal life support (AV-ECLS) circuit that maintains fetal circulation, is an appealing alternative.

METHODS

A near-term (140 d/term = 145 days) neonatal lamb model was used (n = 7). Fetuses were exposed by hysterotomy, and flow probes were placed on the ductus arteriosus, aorta, and carotid artery. Catheters were placed into the umbilical vessels, and pumpless AV-ECLS was initiated. Fetuses were submerged in a warm saline bath, and support was maintained for up to 4 hours.

RESULTS

Mean initial device flow was 383 mL/min but steadily declined to 177 mL/min at 4 hours. Mean initial pO(2) was 24 mm Hg and 18 mm Hg at 4 hours. Initial mean pCO(2) was 60 mm Hg and declined to 42 mm Hg at 4 hours. Mean arterial pressure was initially 43 mm Hg and decreased to 34 mm Hg at 4 hours. Flow in the ductus arteriosus was maintained for 4 hours. Of 7 fetuses, 5 survived 4 hours of support.

CONCLUSIONS

Pumpless AV-ECLS can support gas exchange and maintain fetal circulation in a neonatal lamb model for a 4-hour period. Prolonged support (>4 hours) is hampered by high cannula resistance and declining device flow.

Ductus venosus S-wave/isovolumetric A-wave (SIA) index and A-wave reversed flow in severely premature growth-restricted fetuses

OBJECTIVE

Ductus venosus (DV) Doppler waveforms show 2 periods of decreased velocity during iso-volumetric relaxation (isovolumetric relaxation velocity [IRV]) and atrial contraction (A wave or end-diastolic velocity [EDV]). In intrauterine growth-restricted (IUGR) fetuses, both may become abnormal. The hypothesis for this study was that in severely premature IUGR fetuses, Doppler assessment of both the IRV and EDV allows a more accurate prediction of fetal outcome than absent/reversed end-diastolic flow (A/REDF) alone.

METHODS

Ductus venosus Doppler waveforms were serially studied in 49 severely premature IUGR fetuses from diagnosis until death or delivery. The DV waveforms were assessed for peak systolic velocity (PSV), IRV, and EDV and qualitatively for forward end-diastolic flow or A/REDF. The S-wave/isovolumetric A-wave (SIA) index [PSV/(IRV + EDV)] for each fetus was compared to fetal/neonatal outcomes.

RESULTS

There were 8 cases of fetal death (FD), 9 cases of neonatal death (ND), and 32 cases of neonatal survival (NS). A receiver operating characteristic (ROC) curve for the SIA index in all cases showed that values less than -1.25 correlated with FD and those greater than -1.25 correlated with live birth, with 100% sensitivity and 100% specificity. A second ROC curve of live births showed that values less than 2.07 correlated with NS and those greater than 2.07 correlated with ND with 67% sensitivity and 94% specificity. Ductus venosus A/REDF correlated with FD, ND, and NS with sensitivity values of 88%, 78%, and 32%, respectively. Of the 32 NSs, 11 (34%) had A/REDF with a median of 11 days before delivery.

CONCLUSIONS

The SIA index is a novel Doppler parameter for assessment of severely premature IUGR fetuses that allows a much more accurate prediction of fetal outcome compared to A/REDF alone.

Non-influence of fetal gender on ductus venosus Doppler flow in the first trimester

OBJECTIVES

Recent findings have suggested that ductus venosus blood flow may be influenced by fetal gender. The aim of this study was to investigate further the influence of fetal gender on ductus venosus Doppler flow in the first trimester.

METHODS

This was a cross-sectional and retrospective study performed between January 1998 and January 2003. A total of 932 fetuses at between 10 and 14 weeks' gestation were included. The following inclusion criteria were used: singleton gestation; crown-rump length between 39 and 84 mm; and absence of fetal anomalies. The following variables of the ductus venosus were evaluated: peak velocity during ventricular systole (S-wave) and diastole (D-wave); nadir during atrial contraction in late diastole (A-wave); pulsatility index for veins (PIV); peak velocity index for veins (PVIV); and time-averaged maximum velocity (TAMXV).

RESULTS

Four hundred and forty-eight (48.1%) female and 484 (51.9%) male fetuses were included in the study. Comparing males and females at between 10 and 14 weeks' gestation, there was no statistically significant difference in S-wave, D-wave, A-wave, PIV, PVIV or TAMXV.

CONCLUSIONS

Our study suggests that fetal gender does not influence ductus venosus blood flow in the first trimester.

Vascular development and differentiation during human liver organogenesis

The vascular architecture of the human liver is established at the end of a complex embryological history. The hepatic primordium emerges at the 4th week and is in contact with two major venous systems of the fetal circulation: the vitelline veins and the umbilical veins. The fetal architecture of the afferent venous circulation of the liver is acquired between the 4th and the 6th week. At the end of this process, the portal vein is formed from several distinct segments of the vitelline veins; the portal sinus, deriving from the subhepatic intervitelline anastomosis, connects the umbilical vein, which is the predominant vessel of the fetal liver, to the portal system; the ductus venosus connects the portal sinus to the vena cava inferior. At birth, the umbilical vein and the ductus venosus collapse; the portal vein becomes the only afferent vein of the liver. The efferent venous vessels of the liver derive from the vitelline veins and are formed between the 4th and the 6th week. The hepatic artery forms at the 8th week; intrahepatic arterial branches progressively extend from the central to the peripheral areas of the liver between the 10th and the 15th week. Hepatic sinusoids appear very early, as soon as hepatic cords invade the septum transversum at the 4th week. They then progressively acquire their distinctive structural and functional characters, through a multistage process. Vascular development and differentiation during liver organogenesis is, therefore, a unique process; many of the cellular and molecular mechanisms involved remain poorly understood.

Analysis of Segmental and Global Function of the Fetal Heart Using Novel Automatic Functional Imaging

BACKGROUND

Functional assessment of the fetal heart has always been a challenge. Automatic functional imaging (AFI), a novel non-Doppler methodology based on 2-dimensional acoustic markers tracking, measures myocardial deformation regardless of angle of interrogation. Thus, we studied the validity of AFI in segmental and global assessment of myocardial function in the fetus.

METHODS

AFI-based myocardial deformation parameters including segmental tissue velocity, strain, and strain rate as well as biventricular global strain and strain rate were measured from raw scan-line data obtained from 28 normal fetuses (20-38, median 28 weeks of gestation). Interobserver and intraobserver variability was analyzed. AFI data were compared with analogous Doppler-derived tissue velocity imaging parameters measured in the same 28 fetuses.

RESULTS

AFI was feasible in 94% of the fetuses studied with high reproducibility. AFI-based tissue velocity (3.9 +/- 1 cm/s) was comparable with tissue velocity imaging-based velocity (4 +/- 1.6 cm/s) in the right ventricle and in the left ventricle (AFI velocity 3.3 +/- 0.6 vs tissue velocity imaging 3.1 +/- 0.9 cm/s). Strain rate obtained by these two methods was also similar. Biventricular global strain and strain rate measured 16 +/- 4% and 1.6 +/- .5 seconds(-1), respectively. Tissue velocity increased whereas segmental strain rate decreased throughout gestation. Strain remained unchanged. Global strain rate significantly decreased with gestational age (r = -0.7).

CONCLUSION

AFI, a novel non-Doppler methodology, allows fast and accurate quantification of segmental and global myocardial function in the fetus. AFI-based tissue velocity increases with gestational age whereas segmental and the new parameter global strain rate decrease throughout gestation.

Absence of ductus venosus-importance of umbilical venous drainage site

OBJECTIVE

To evaluate the conditions associated with absent ductus venosus (ADV) diagnosed by prenatal ultrasonography.

METHODS

Retrospective review of 23 cases with ADV diagnosed in two tertiary referral centers with a general screening policy concerning Doppler assessment of the ductus venosus. The results are discussed together with 63 cases from a review of the literature.

RESULTS

In 19 fetuses the umbilical vein connected to the portal sinus, while the remaining four fetuses had extrahepatic umbilical venous drainage. Associated anomalies were present in 15 out of 23 fetuses: complex malformation syndromes (n = 6), chromosomal anomalies (n = 4), isolated cardiac defects (n = 4) and isolated extracardiac anomalies (n = 1). Eight fetuses had either no associated anomalies or minor anomalies. Hydropic changes were present in 12 of the 23 fetuses. In common with the reviewed cases, the presence of cardiac malformations, complex non-chromosomal malformation syndromes and hydrops was significantly associated with intrauterine or postnatal death while the type of umbilical venous drainage was not significantly different between survivors and non-survivors. However, among fetuses with no or minor associated anomalies the outcome was significantly better in the group without liver bypass.

CONCLUSIONS

ADV is significantly associated with fetal cardiac and extracardiac anomalies, aneuploidies and hydrops. Fetuses with liver bypass have an additional risk of developing congestive heart failure that significantly affects outcome, even if the fetal cardiovascular anatomy is otherwise normal. ADV without liver bypass seems to have a more favorable prognosis if it is not associated with other malformations.

Ductus venosus blood flow alterations in fetuses with obstructive lesions of the right heart

OBJECTIVE

To assess the impact of isolated lesions of the fetal right heart on ductus venosus (DV) blood flow profiles.

METHODS

Retrospective evaluation of DV blood flow profiles in 83 fetuses with isolated right-sided cardiac lesions. Cases were divided into two groups. Group A had right-sided cardiac lesions associated with a large ventricular septal defect that equalized interventricular pressures (double outlet right ventricle (n = 12), tetralogy of Fallot (n = 19), pulmonary atresia (n = 5)). Group B had right-sided cardiac lesions with obstruction of the inflow (tricuspid atresia with ventricular septal defect (n = 14)) or obstruction of the outflow with intact ventricular septum (Ebstein's anomaly (n = 13), pulmonary stenosis (n = 13) and pulmonary atresia (n = 7)). Comparisons were made with 585 uneventful singleton pregnancies and previously published normative values.

RESULTS

Fetuses in Group B had significantly higher rates of abnormal DV flow profiles compared to Group A and controls (P < 0.01). Conversely, there were no significant differences concerning DV parameters between fetuses in Group A and controls. Despite these different DV flow characteristics, there were no significant differences concerning signs of cardiac failure and/or survival to the perinatal period between the two groups.

CONCLUSIONS

Right-sided cardiac lesions with obstruction of the inflow or outflow with intact ventricular septum are significantly associated with abnormally high pulsatilities in the DV and may even cause a reversal of flow during atrial contraction. These changes do not necessarily indicate cardiac failure, as they are primarily attributable to the special hemodynamics of the cardiac defect.

Regional difference of endothelium-dependent contractility in human umbilical artery

To investigate whether vascular reactivity of the umbilical artery influences differences in Doppler waveform depending on the sampling site along the cord, we studied a regional difference of endothelium-dependent vascular contractility in human umbilical artery using mechanical responses to the quick stretch of vascular smooth muscle strips. The umbilical artery resistance index (RI) values for the fetal end were significantly higher than those for the placental end. In endothelium-intact strips, stretch-induced contraction of the umbilical artery appears to decrease from the fetal to the placental end of the umbilical artery. No significant differences were noted between strips from the two locations when endothelial cells were rubbed, indicating that this regional difference is related to endothelial cell function. Indo-methacin decreased the stretch-induced contraction of endothelium-intact strips, but tetrodotoxin did not affect this association, suggesting that arachidonic acid metabolism via the cyclooxygenase pathway contributes to modulation of human umbilical artery responsiveness to stretch. These findings suggest that the difference in Doppler waveform of the umbilical artery depending on the sampling site is related to differences in vascular resistance that result from endothelium-related function.

Transcatheter closure of patent ductus venosus with the Amplatzer vascular plug in twin brothers

We describe the transcatheter closure of a patent ductus venosus in twin brothers with an ill-defined systemic illness and respiratory failure using the Amplatzer vascular plug. To our knowledge, this is the first description of the use of the Amplatzer vascular plug for ductus venosus closure.

Cardiopulmonary Bypass in Ewe’s Fetus: Advances and Setbacks in Our Learning Curve

Fetal cardiac surgery represents a surgical challenge and several centers are attempting to establish a suitable methodology in animals. We present our experience with extra-corporeal bypass procedures in preterm and term sheep fetuses. Twenty-two fetuses (103-139 days gestation, mean 115 days gestation) underwent a 1-hour period of right heart-to-pulmonary artery extracorporeal circulation followed by 1 hour of observation. Animals were divided into group 1 and group 2, according to gestational age (above and below 0.85). Three pumps were used: centrifugal without (group 1) reservoir, centrifugal with (group 2) reservoir, and roller with reservoir (group 2). Experiments were completed in 75% of fetuses in group 1 and in 37% of fetuses in group 2. Bleeding was the main cause of failure, especially for group 2. A slow deterioration of blood gas status was noted in group 1, while this trend could be partially reversed in group 2 with corrective measures. Complete heart bypass could not be achieved in either group, and residual fluctuations in arterial pressure were observed. During bypass, body temperature decreased more in group 2 than in group 1. We conclude that cardiac bypass is feasible over a short period in near-term fetuses. A successful outcome may also be obtained in younger fetuses, but better measures need to be implemented for the prevention of surgical bleeding.