Fetal Doppler in monochorionic pregnancies complicated by twin-to-twin transfusion syndrome and selective in utero growth restriction

BACKGROUND

Monochorionic (MC) twin pregnancies may be complicated by placental pathologies that impact fetal cardiac function, such as twin-twin transfusion syndrome (TTTS) and selective intrauterine growth-restriction (sIUGR). In the TTTS, the unbalanced blood flow through placental anastomoses lead a recipient volume overload, hypertension and hypertrophic cardiomyopathy and the donor twin experiences hypovolemia and hypertension due to increased placental resistance and poor renal perfusion. When MC pregnancies were complicated by sIUGR, the increase of placental resistances lead to complex fetal compensatory mechanisms with redistribution of cardiac output to vital organs. Increased placental vascular resistances, hypoxia and hemodynamic compensation mechanisms lead to higher pre and/or afterload for both ventricles, right cardiac failure and eventually left cardiac failure observed just before fetal death.

OBJECTIVES

The purpose of this study was to describe the anomalies of umbilical, ductal and aortic isthmic Doppler as well as left and right myocardial performance index (MPI) across various clinical phenotypes of MC twin pregnancies, uncomplicated or complicated by TTTS or sIUGR, in order to help differentiating these conditions and to improve the understanding of TTTS and sIUGR pathophysiology.

STUDY DESIGN

Aortic isthmic systolic index (ISI), umbilical artery pulsatility index (UAPI), ductus venosus pulsatility index (DVPI), and MPI were studied in uncomplicated MC twins (control group) and cases of sIUGR or TTTS.

RESULTS

The measurements were obtained in 113 pregnancies (24 uncomplicated, 22 sIUGR, 51 TTTS). In comparison with controls, the sIUGR smaller twin sets had lower ISI and higher UAPI, and the larger twin had higher ISI. The TTTS donor and recipient had lower ISI, higher UAPI and DVPI. Compared to the co-twin, the ISI values were lower in the sIUGR smaller twin and the TTTS donor had lower ISI and MPI. Comparing TTTS and sIUGR, the recipient had higher DVPI and MPI than the sIUGR larger twin.

CONCLUSIONS

The Doppler anomalies observed in the smaller twin reflected increased placental blood flow resistance, presumably due to abnormal feto-fetal transfusion in TTTS and to unequal placental sharing in sIUGR. Early hemodynamic changes suggestive of cardiac overload in the recipient twin may help to differentiate TTTS and sIUGR.

Factors associated to early intrauterine fetal demise after laser for TTTS by preoperative fetal heart and Doppler ultrasound

OBJECTIVE

To determine the prognostic value of fetal Doppler and echocardiographic parameters for intrauterine fetal demise (IUFD) within 24 hours and within 1 week after laser coagulation in monochorionic pregnancies complicated by twin-twin transfusion syndrome.

METHOD

This retrospective study correlated the preoperative hemodynamic and echocardiography parameters to the outcome in fetuses with twin-twin transfusion syndrome undergoing laser therapy.

RESULTS

One hundred and twelve laser coagulations were performed between February 2006 and June 2015. The total (single and double) IUFD rate was 27.7%. Further, 59% of IUFD occurred within 24 hours and 74.4% occurred within 1 week after laser. The following were associated to IUFD within 24 hours: the middle cerebral arterial pulsatility index in the donor, abnormal umbilical artery (UA) end diastolic flow, increased middle cerebral artery peak systolic velocity, and right ventricular myocardial performance index (RV-MPI) z-score in the recipient. For IUFD within 1 week were the pulsatility index in the donor UA and the recipient abnormalities in UA, ductus venosus, middle cerebral artery-peak systolic velocity, and RV-MPI z-score.

CONCLUSION

Following laser was early IUFD that was associated with Doppler findings suggesting donor cerebroplacental redistribution, and recipient overload cardiomyopathy, such as abnormal ductus venosus and UA Dopplers as well as an increase of RV-MPI.

Aortic Isthmus Flow Recording Predicts the Outcome of the Recipient Twin after Laser Coagulation in Twin-Twin Transfusion Syndrome

INTRODUCTION

The objective was to assess the prognostic value of the systolic flow through the aortic isthmus in monochorionic pregnancies complicated by twin-twin transfusion syndrome (TTTS) treated by placental laser ablation.

MATERIAL AND METHODS

Fetal echocardiography and outcome data of 105 cases of TTTS treated by laser photocoagulation of placental anastomoses were reviewed. Hemodynamic parameters were collected before and after treatment. The isthmic systolic index (ISI) was calculated as the peak systolic velocity/systolic nadir ratio.

RESULTS

A total of 105 laser coagulations were studied. Fetal echocardiography pre- and post-laser were available in 68 cases, including 55 with data on aortic isthmic Doppler. Survival rates were 17, 22, and 61% for 0, 1, or 2 twins, respectively. At least 1 twin was delivered alive in 83% of the pregnancies. The mean gestational age at surgery was 21 weeks (range 16-26). Median ISI values were similar for donor and recipient twins, before and after laser ablation (all p > 0.05). A lower recipient ISI before laser was related to early recipient demise within 24 h (p = 0.04).

DISCUSSION

A lower ISI before placental laser ablation for TTTS is associated with postoperative demise of the recipient twin.

Oxidative conditions prevail in severe IUGR with vascular disease and Doppler anomalies

OBJECTIVE

Intrauterine growth restriction (IUGR) and prenatal exposure to oxidative stress are thought to lead to increased risks of cardiovascular disease later in life. The objective of the present study was to document whether cord blood oxidative stress biomarkers vary with the severity of IUGR and of vascular disease in the twin pregnancy model in which both fetuses share the same maternal environment.

METHODS

This prospective cohort study involved dichorionic twin pairs, with one co-twin with IUGR. Oxidative stress biomarkers were measured in venous cord blood samples from each neonate of 32 twin pairs, and compared, according to severity of IUGR (IUGR <5th percentile), Doppler anomalies of the umbilical artery and early onset IUGR (in the second trimester) of the growth restricted twin.

RESULTS

Oxidized Low-Density Lipoproteins (oxLDL) and Malondialdehyde (MDA) concentrations were increased proportionally in cases of severe IUGR. OxLDL concentrations were also increased in cases of IUGR with Doppler anomaly.

CONCLUSION

Our data indicate that severe IUGR, is related to a derangement in redox balance, illustrated by increased venous cord blood oxidative stress biomarkers concentrations. Severe IUGR and IUGR with abnormal Doppler can be translated into conditions with intense oxidative stress.

Profiling left and right ventricular proportional output during fetal life with a novel systolic index in the aortic isthmus

OBJECTIVE

Left ventricular ejection causes forward flow in the fetal aortic isthmus while the right ventricle has a retrograde influence. The aim of this study was to create reference values for an isthmic systolic index (ISI) reflecting the changing influence of right and left ventricular performance on Doppler flow velocity waveforms of the aortic isthmus throughout normal pregnancy.

METHODS

Doppler recordings of 260 normal fetuses with a gestational age of 18-37 weeks were reviewed. Peak systolic velocity (PSV) and end-systolic velocity (or systolic nadir; Ns) were measured on all aortic isthmus waveforms. An ISI was derived from the ratio Ns/PSV. Left and right ventricular outputs were also calculated.

RESULTS

Up to 22-23 weeks' gestation, the mean ISI is stable at around 0.2. At about 28 weeks, a brief end-systolic deceleration wave is observed on the aortic isthmus waveforms, progressing steadily with gestation and causing a fall of ISI towards a mean value of zero between 30 and 31 weeks. This trend continues thereafter and a mean value of -0.4 was observed at the end of pregnancy. An inverse correlation was found between right ventricular output and Ns (r = -0.334, P = 0.001). Simultaneous recordings of the isthmus and the ductus arteriosus Doppler waveforms demonstrated that the primary cause of the end-systolic deceleration and ultimate reversal of flow at the isthmus is the increasingly dominant flow from the right ventricle.

CONCLUSION

The transitional changes of the respective right and left ventricular outputs throughout pregnancy are well profiled by the ISI. This index highlights the physiological increase in fetal right ventricle flow preponderance as pregnancy progresses. Alteration of the ISI profile could be expected in clinical conditions associated with unbalanced alteration of the fetal ventricular outputs.

Diagnosis and management of fetal heart failure

Congestive fetal heart failure, defined as inability of the heart to deliver adequate blood flow to organs such as the brain, liver, and kidneys, is a common final outcome of many intrauterine disease states that may lead to fetal demise. Advances in fetal medicine during the past 3 decades now provide the diagnostic tools to detect and also treat conditions that may lead to fetal heart failure. Fetal echocardiographic findings depend on severity of diastolic and systolic dysfunction of both ventricles. At an advanced stage, findings include cardiomegaly; valvar regurgitation; venous congestion; fetal edema and effusions; oligohydramnios; and preferential shunting of blood flow to the brain, heart, and adrenals in the distressed fetus. A useful diagnostic tool to quantify severity of heart failure is the cardiovascular profile score, which is a composite score based on 5 different echocardiographic parameters. To predict outcomes, the score should be interpreted in the context of the underlying disease, as different causes of intrauterine heart failure may have highly variable outcomes. Low fetal cardiac output may result from a myocardial disease (cardiomyopathy, myocarditis, ischemia), abnormal loading conditions (arterial hypertension, obstructive structural heart disease, atrioventricular malformations, twin-to-twin transfusion), arrhythmia, or external cardiac compression (pleural and/or pericardial effusions, cardiac tumours). Treatment options are available for several of these conditions.

Prenatal diagnosis of long QT syndrome with the superior vena cava-aorta Doppler approach

We describe a fetus at 36 weeks with long QT syndrome presenting with variable types of atrioventricular blocks, ventricular premature beats, and torsades de pointes. All these diagnoses were made with the superior vena cava-aorta Doppler approach and confirmed with postnatal electrocardiography.

Assessment of uterine artery and aortic isthmus Doppler recordings as predictors of necrotizing enterocolitis

OBJECTIVE

The purpose of this study was to evaluate whether changes of uterine arteries and aortic isthmus Doppler blood flow recordings could enhance the prediction of necrotizing enterocolitis.

STUDY DESIGN

Doppler characteristics of the uterine artery, umbilical and middle cerebral arteries, ductus venosus, and aortic isthmus were reviewed in 123 growth-restricted fetuses who were then divided into 2 groups: with and without necrotizing enterocolitis.

RESULTS

Twelve of 123 newborn infants (9%) expressed necrotizing enterocolitis. This group showed significant association between necrotizing enterocolitis and bilateral notching on the uterine artery (83.3% vs 29.7%; P < .001), uterine artery mean resistance index (83.3% vs 36.9%; P < .002), aortic isthmus diastolic blood flow velocity integrals (Z score: -7.32 vs -3.99; P = .028), and absent or negative "a" wave on the ductus venosus (17% vs 1.8%; P = .021). With the use of logistic regression, uterine bilateral notching could predict necrotizing enterocolitis with a sensitivity of 83.3% and a specificity of 70.3%.

CONCLUSION

More than any other variable, uterine bilateral notching should be recognized as a strong risk factor for necrotizing enterocolitis.

Ultrasonographic diagnosis of delayed atrioventricular conduction during fetal life: a reliability study

OBJECTIVE

The objective of the study was to evaluate the reliability of the 2 most commonly used ultrasonographic approaches for monitoring fetal atrioventricular conduction time (AVCT): (1) superior vena cava/ascending aorta (SVC/AA), and (2) left ventricular inflow/outflow tract (LVI/O) Doppler recordings.

STUDY DESIGN

Echographic studies from fetuses followed up for first-degree atrioventricular block (AVB-1) between 1998 and 2008 were reviewed. The ability to identify atrial contractions in the same fetuses by the SVC/AA and LVI/O approaches was analyzed.

RESULTS

Sixty-six studies of 13 fetuses with AVB-1 were available. Atrial contractions were visible in all SVC/AA studies. With the LVI/O approach, atrial contractions could not be identified in 26 studies (39%). AVCT delay was significantly greater in the nonidentifiable compared with the identifiable atrial contraction group (P < .001). Differences in heart rate and gestational age were not significant.

CONCLUSION

The LVI/O is unsuitable for prenatal screening of conduction system anomalies.

Profiling fetal cardiac function in twin-twin transfusion syndrome

OBJECTIVES

Cardiomyopathy in the recipient twin is a marker of severity in twin-twin transfusion syndrome (TTTS), making it a potentially valuable tool for staging the disease. This study aimed to provide a quantitative description of cardiac function in the recipient twin.

METHODS

Consecutive monochorionic pregnancies complicated with TTTS and treated by percutaneous laser coagulation underwent fetal echocardiography before surgery. An unsupervised classification analysis was conducted to identify groups of twins with similar cardiac profiles. The predictive value of the recipient twin's preoperative cardiac function based on these profiles was assessed, using perinatal death of at least one twin as the main outcome. The cardiac function profiles that we identified were compared with the current Quintero staging.

RESULTS

A total of 107 pregnancies were included, with six of these lost to follow-up; 63/107 complete cases were available for multivariate description of the recipient's cardiac function. Three different preoperative cardiac profiles were identified with increasing right and left myocardial performance index, decreasing right and left shortening fraction, and increasing ductus venosus pulsatility index. Although the three groups represented progressive stages of the syndrome-related cardiomyopathy, no correlation was found with pregnancy outcome. Of Quintero Stage 1 cases, 55% showed significant alterations of cardiac function in the recipient twin.

CONCLUSIONS

Progressive cardiomyopathy can be assessed quantitatively in the recipient twin and does not influence pregnancy outcome when fetoscopic laser coagulation is the first-line treatment. Compared with the current staging, cardiac profiling allows discrimination of cases with significant myocardial dysfunction.

[Blood flow through the fetal aortic isthmus: a new physiological concept with many clinical implications]

The new physiological concept: because of the parallel disposition of the fetal ventricles and of their respective arterial outlet, the flow through the aortic isthmus represents the only arterial shunt in the fetal circulation. The low resistance of the placental circulation explains the forward systolic and diastolic flows normally observed through the isthmus.

CLINICAL IMPLICATIONS

(1) assessment of individual performances of each ventricle : left ventricle causes forward flow while the right ventricle has a retrograde influence; (2) any changes of flow and/or resistances affecting one of the two fetal arterial systems organized in parallel should influence the flow pattern within the isthmus. Examples : peripheral arterio-venous fistula, increase in placental vascular resistance leading to intra-uterine growth restriction, etc.

CONCLUSION

doppler flow recordings in the fetal aortic isthmus: (1) provides information on the global condition of the fetal cardiocirculatory system; (2) is a good indicator of fetal individual ventricular performance; (3) allows assessment of hemodynamic consequences of abnormalities of the peripheral circulatory systems.

Determinants of outcome in fetal pulmonary valve stenosis or atresia with intact ventricular septum

Pulmonary valve stenosis or atresia with intact ventricular septum represents a spectrum of severity. This study aimed to identify ultrasound markers of biventricular versus non-biventricular outcome. The fetal echocardiograms of 41 fetuses diagnosed with pulmonary stenosis or atresia and right ventricular (RV)/left ventricular (LV) length ratios >0.4 from 17 to 31 weeks of gestation were reviewed. Of 27 live-born patients with intention to treat, 8 had non-biventricular outcomes and 19 had biventricular circulation. At the time of diagnosis, poor RV function, flow reversal in the arterial duct, the degree of tricuspid valve (TV) regurgitation, and inferior vena cava Doppler flow pattern did not differ between the 2 outcome groups. However, RV sinusoids, the RV/LV length ratio, the TV/mitral valve ratio, and TV inflow duration were significantly different. Cut-off values derived from receiver-operating characteristic curves yielding the best sensitivity and specificity for a non-biventricular outcome were TV/mitral valve ratio <0.7, RV/LV length ratio <0.6, TV inflow duration <31.5% of cardiac cycle length, and the presence of RV sinusoids. If 3 of these 4 criteria were fulfilled, this predicted a non-biventricular outcome with sensitivity of 100% and specificity of 75%. In conclusion, in fetuses < or =31 weeks of gestation with pulmonary stenosis or atresia and intact ventricular septum, progression to a non-biventricular outcome can be predicted by a 4-criterion scoring system. The criteria may be useful in selecting fetuses for prenatal catheter intervention to prevent progressive RV hypoplasia.

[Fetal haemodynamic and left heart dysfunction]

Foetal cardiology is a well established field of paediatric cardiology. It is no longer a simple exercise of prenatal diagnosis of cardiac malformations. It also covers the investigation and treatment of arrhythmias and functional and dynamic cardiocirculatory evaluation of the foetus which does not always have primary organic cardiac disease. It is this aspect which will be described in this article. The interactions of the left heart / foetal haemodynamics are classified in two main groups according to whether the left myocardial dysfunction is primary or secondary to changes of pre- or afterload. The haemodynamics singularities of the normal foetal circulation are and essential basis for the understanding of the phenomena observed.

Fetal arrhythmias: the Saint-Justine hospital experience

We intend to review our experience with the investigation and management of foetal arrhythmia on the basis of superior vena cava/ascending aorta (SVC/AA) Doppler flow velocity recordings. Irregular rhythms n = 307. Premature atrial and ventricular contractions were easily identified and generally self-limited in time. Sustained bradycardia n = 19. Four had sinus bradycardia, six presented with blocked atrial bigeminism, three showed 2:1, and five had a complete atrio-ventricular (AV) block. Another foetus that presented with first-degree AV block developed a Luciani-Wenckebach phenomenon 1 week later. These different types of bradycardia were all identified on SVC/AA Doppler recordings. Tachyarrhythmia n = 30. Five types of tachyarrhythmia were observed: Type I: Short ventriculo-atrial (VA) tachycardia (VA < AV), n = 11. Ten foetuses of this group presented a distinctive Doppler flow velocity pattern characterised by 1:1 AV conduction and a tall atrial wave ('a' wave) superimposed on the aortic ejection wave. They were considered to have re-entrant tachycardia through a fast-conducting AV accessory pathway; all 10 responded to digoxin therapy. The eleventh foetus with short VA tachycardia had atrial ectopic tachycardia with AV node dysfunction; he was treated successfully with sotalol. Type II: Long VA tachycardia (VA > AV): n = 8. In seven cases, an 'a' wave of normal amplitude with normal AV time interval could be clearly identified in front of the aortic ejection wave: one foetus in this group was considered to be in sinus tachycardia based on the variability of its heart rate; in another, sudden onset of tachycardia triggered by extrasystoles led to the possibility of permanent junctional reciprocating tachycardia (PJRT). The five other foetuses had atrial ectopic tachycardia. The last foetus presented with AV and VA intervals of the same duration and a heart rate of 210 beats/min; he did not respond either to digoxin or to sotalol, and was found after birth to have PJRT. The drug of first choice in this group was sotalol. Type III: Simultaneous onset of atrial and ventricular contractions: n = 3. These foetuses were classified as junctional ectopic tachycardia. Two responded to amiodarone. The other foetus converted spontaneously to sinus rhythm. Type IV: Flutter: n = 7. All presented with 2:1 AV relationship except one who had a variable block. Digoxin was prescribed as a first choice associated with sotalol in three cases. Conversion to sinus rhythm was documented in all; however, one hydropic foetus with advanced cardiomyopathy died one day after birth. Type V: Ventricular tachycardia: n = 1. This 30-week foetus presented alternance of AV dissociation (atrial rate: 130, ventricular rate: 170 beats/min) and atrial capture (ventricular rate of 138 beats/min). The arrhythmia responded well to propanol, and no recurrence was recorded after birth. Precise prenatal identification of arrhythmia type can be achieved with the SVC/AA Doppler approach. Such information allows for a better management and a rational choice of appropriate anti-arrhythmic drug.

Fetal Doppler echocardiographic diagnosis and successful steroid therapy of Luciani-Wenckebach phenomenon and endocardial fibroelastosis related to maternal anti-Ro and anti-La antibodies

BACKGROUND

Complete fetal heart block (HB) and endocardial fibroelastosis (EFE) are known to be associated with maternal anti-Ro and anti-La antibodies. Complete fetal HB is irreversible.

OBJECTIVES

We sought to (1) assess the value of the superior vena cava/ascending aorta Doppler approach in the early detection of abnormal delay in the fetal atrioventricular (AV) time of conduction, before appearance of complete fetal HB; and (2) report the effect of prenatal steroid therapy on EFE, HB, or both.

RESULTS

The clinical history, echocardiographic, and Doppler investigations of 3 fetuses and children born to mothers positive for anti-Ro and anti-La antibodies are reported. Two fetuses presented with EFE either isolated (29 weeks) or associated with AV block (25 weeks). In this last case, the superior vena cava/ascending aorta approach allowed the identification of a Luciani-Wenckebach phenomenon. In a third fetus, 2:1 AV block was noted at 23 weeks of gestation. Dexamethasone (4 mg/day) was administered to all 3 patients. Complete regression of the EFE and conduction abnormalities was documented in all cases.

CONCLUSION

Early prenatal detection of abnormal delay in fetal AV time conduction is possible with the Doppler superior vena cava/ascending aorta approach. Steroid therapy can cure fetal EFE and AV conduction delays associated with maternal anti-Ro and anti-La antibodies.

Neonatal cholestasis associated with fetal arrhythmia

We evaluated the consequence of different types of fetal arrhythmia in the development of neonatal cholestasis. The charts of 38 children born at St. Justine Hospital between 1993 and 2001 with sustained and hemodynamically significant fetal arrhythmias were studied: 19 with supraventricular tachycardia, 14 with atrial flutter, and 5 with atrio-ventricular (AV) block. Six of these 38 children presented with cholestasis. The average duration of arrhythmia was 15.7 days in the noncholestatic group, compared with 40.3 days in the cholestatic group ( P <.05). The three infants with supraventricular tachycardia who developed cholestasis survived and resolved their cholestasis, whereas 2 of 3 infants with AV block died. No infant with atrial flutter developed cholestasis. We conclude that newborns who developed tachyarrhythmia during their fetal life can show transient neonatal cholestasis. In patients with AV block, severe and irreversible liver failure could be observed. In addition, extensive collapse of the stroma and the absence of hepatocytes (foie vide) also were observed in a patient with anti-Ro antibodies.

The relationship between an aortic isthmus blood flow velocity index and the postnatal neurodevelopmental status of fetuses with placental circulatory insufficiency

OBJECTIVE

The purpose of this study was to evaluate the association between an abnormal aortic isthmus blood flow index and postnatal neurodevelopmental outcome in fetuses with placental circulatory insufficiency. STUDY DESIGN Forty-eight children who were born between 1991 and 1999 were included in this study on the basis of abnormal umbilical artery Doppler velocimetry. Prenatal isthmus blood flow index was obtained by dividing the sum of the systolic and diastolic Doppler blood flow velocity integrals by the systolic blood flow integrals. Neurodevelopmental outcome between 2 and 5 years was classified as optimal, when neurologic assessment and developmental quotient were within normal limits and as nonoptimal when abnormal neurologic findings and/or a nonoptimal developmental quotient was present. Neurodevelopmental outcome was analyzed in relation to isthmus flow index and pulsatility indices in the umbilical artery.

RESULTS

The mean gestational age at delivery was 33.0 +/- 2 weeks. Nonoptimal neurodevelopmental outcome was found in 60.4% of the children (29/48). An inverse correlation was found between the isthmus blood flow index and postnatal neurodevelopmental outcome. All 13 children with an isthmus blood flow index of <0.5 were in the nonoptimal group. All 19 children with an optimal outcome had an isthmus blood flow index of >0.5, but this was also the case for 16 other children with nonoptimal neurodevelopmental outcome. An isthmus blood flow index cut-off value of 0.70 was associated with the highest overall positive and negative predictive values. The pulsatility index in the umbilical artery did not provide any significant contribution in the explanation of the outcome.

CONCLUSION

The isthmic blood flow index can help to identify a subgroup of fetuses with placental circulatory insufficiency that might benefit from early delivery.

Early Intertwin Differences in Myocardial Performance During the Twin-to-Twin Transfusion Syndrome

Background— In the twin-to-twin transfusion syndrome (TTTS), pressure rather than volume overload is increasingly considered as a key factor in the pathogenesis of the cardiomyopathy of the recipient twin. If this is the case, cardiac dysfunction should be among the first signs observed with TTTS. The objective of this study was to determine whether intertwin differences in myocardial function are modified early in the course of TTTS and whether they can help to differentiate this condition from intrauterine growth restriction (IUGR).

Methods and Results— Eight variables were analyzed on the first fetal echocardiography on 21 pairs of twins with TTTS and 11 with IUGR. No difference was found between the 2 groups for the cardiothoracic ratio, pulsatility indices in the umbilical and middle cerebral arteries, and peak velocity of the middle cerebral artery. Significant difference was found for ventricular septal thickness, but with no association with the conditions under study. With TTTS, left ventricular shortening fraction was consistently greater in the donor twins, and myocardial performance indices (MPIs) were elevated in the recipient twins. This increase in MPI was caused by a lengthening of the isovolumic periods compared with those of the donor twin: left ventricular and right ventricular isovolumic periods 0.105±0.047 and 0.097±0.026 seconds, respectively, for the recipient twins versus 0.0561±0.46 and 0.065±0.03 seconds, respectively, for the donor twins ( P <0.001). These changes in the isovolumic periods were mainly due to significant prolongation of isovolumic relaxation times. A change in left ventricular MPI ≥0.09 combined with a change in right ventricular MPI ≥0.05 would identify a TTTS with a sensitivity of 75% and a false-positive rate of 9%.

Conclusions— The observed diastolic function impairment goes along with the pressure-overload pathogenic concept proposed in TTTS. Assessment of intertwin difference in MPI is a valuable tool for early differential diagnosis between TTTS and isolated IUGR.

Prostaglandin E2--mediated relaxation of the ductus arteriosus: effects of gestational age on g protein-coupled receptor expression, signaling, and vasomotor control

BACKGROUND

In the preterm newborn, a patent ductus arteriosus is in large part a result of the increased sensitivity of the immature ductus to prostaglandin E2 (PGE2). PGE2 acts through 3 G protein-coupled receptors (EP2, EP3, and EP4) that activate both adenyl cyclase and K(ATP) channels. We explored these pathways to identify the mechanisms responsible for the increased sensitivity of the immature ductus to PGE2.

METHODS AND RESULTS

We measured EP receptor content (mRNA and protein), receptor binding, cAMP production, and isometric tension in rings of ductus taken from immature (65% gestation) and mature (95% gestation) sheep and baboon fetuses. Ductus relaxation and cAMP generation were augmented in response to selective EP receptor agonists in the immature ductus. 8-Br-cAMP, a stable cAMP analogue, produced greater relaxation in the immature ductus. In the presence of a selective protein kinase A inhibitor, Rp-8-CPT cAMPS, the developmental differences in sensitivity to PGE2 could no longer be demonstrated. EP2, EP3, and EP4 receptor densities were higher in immature ductus, despite similar receptor mRNA and protein contents at the 2 gestational ages. In contrast, forskolin and NaF, direct activators of adenyl cyclase and Gs, respectively, elicited comparable increases in cAMP in both age groups. KATP channel inhibition also had similar effects on PGE2-induced relaxation in both age groups.

CONCLUSIONS

Two mechanisms explain the increased sensitivity of the immature ductus to PGE2: (1) increased cAMP production because of increased binding of PGE2 to the individual EP receptors and (2) increased potency of cAMP on protein kinase A-regulated pathways.

Transplacental Fetal Treatment Improves the Outcome of Prenatally Diagnosed Complete Atrioventricular Block Without Structural Heart Disease

BACKGROUND

Untreated isolated fetal complete atrioventricular block (CAVB) has a significant mortality rate. A standardized treatment approach, including maternal dexamethasone at CAVB diagnosis and beta-stimulation for fetal heart rates <55 bpm, has been used at our institutions since 1997. The study presents the impact of this approach.

METHODS AND RESULTS

Thirty-seven consecutive cases of fetal CAVB since 1990 were studied. Mean age at diagnosis was 25.6+/-5.2 gestational weeks. In 33 patients (92%), CAVB was associated with maternal anti-Ro/La autoantibodies. Patients were separated into those diagnosed between 1990 and 1996 (group 1; n=16) and those diagnosed between 1997 and 2003 (group 2; n=21). The 2 study groups were comparable in the clinical presentation at CAVB diagnosis but did differ in prenatal management (treated patients: group 1, 4/16; group 2, 18/21; P<0.0001). Overall, 22 fetuses were treated, 21 with dexamethasone and 9 with beta-stimulation for a mean of 7.5+/-4.5 weeks. Live-birth and 1-year survival rates of group 1 were 80% and 47%, and these improved to 95% for group 2 patients (P<0.01). The 21 patients treated with dexamethasone had a 1-year survival rate of 90%, compared with 46% without glucocorticoid therapy (P<0.02). Immune-mediated conditions (myocarditis, hepatitis, cardiomyopathy) resulting in postnatal death or heart transplantation were significantly more common in untreated anti-Ro/La antibody-associated pregnancies compared with patients treated with steroids (0/18 versus 4/9 live births; P=0.007).

CONCLUSIONS

A standardized treatment approach, including transplacental fetal administration of dexamethasone and beta-stimulation at heart rates <55 bpm, reduced the morbidity and improved the outcome of isolated fetal CAVB.

Developmental regulation of prostaglandin E2 synthase in porcine ductus arteriosus

The synthesis of PGE2, the major vasodilator prostanoid of the ductus arteriosus (DA), is catalyzed by PGE2 synthases (PGES). The factors implicated in increased PGE2 synthesis in the perinatal DA are not known. We studied the developmental changes of PGES along with that of cyclooxygenase (COX)-2 and cytosolic phospholipase A2 (cPLA2) in the DA of fetal (75-90% gestation) and immediately postnatal newborn (NB) piglets. Levels of microsomal PGES (mPGES), COX-2, and PGE2 in the DA of NB were ∼7-fold higher than in fetus; activities of cytosolic PGES (cPGES) and cPLA2 in DA of the fetus and NB did not differ. Because platelet-activating factor (PAF) could regulate COX-2 expression, the former was measured and found to be more abundant in the DA of the NB than of fetus. PAF elicited an increase in mPGES, COX-2, and PGE2 in fetal DA to levels approaching those of the NB; cPGES, cPLA2, and COX-1 were unaffected. In perinatal NB DA, PAF receptor antagonists BN-52021 and THG-315 reduced mPGES, COX-2, and PGE2 levels and were associated with increased DA tone. It is concluded that PAF contributes in regulating DA tone by governing mPGES, COX-2, and ensuing PGE2 levels in the perinate.

Immediate and short-term effects of pulmonary artery banding on left ventricular performance in foetal sheep

AIM

To evaluate foetal left ventricular performance when its preload was increased by banding the pulmonary artery, a study design where a simultaneous change in left ventricular afterload is unlikely.

METHODS

Nine ovine foetuses were studied with real-time images and Doppler echocardiography before, 3-4 and 6-8 d after surgery. Seven of these foetuses were also studied during the surgical intervention, immediately before and within 2 min after banding.

RESULTS

The immediate effects of a 90-95% reduction of the pulmonary artery cross-sectional area were: a 53 +/- 20% (mean +/- SD) decrease and a 38 +/- 10% increase of right (RvQ) and left ventricular output (LvQ), respectively. Comparing measurements before and 3-4 d after operation, there was a 64 +/- 16% decrease of RvQ and a 64 +/- 25% increase of LvQ. The increase in LvQ was due to an increase in both heart rate (19 +/- 10%) and stroke volume (38 +/- 18%). After an additional 3-4 postoperative days, heart rate remained increased to the same extent, but there was a more pronounced increase of LvQ (93 +/- 19%) and stroke volume (59 +/- 22%).

CONCLUSION

The parallel foetal circulation has a capacity to handle a severely increased afterload for the right ventricle by immediately improving and maintaining an increased left ventricular performance. This improvement was in part accomplished by an increase in stroke volume.

Agenesis of the ductus venosus that is associated with extrahepatic umbilical vein drainage: prenatal features and clinical outcome

OBJECTIVE

We sought to study the clinical and ultrasonographic findings and outcomes of fetuses with ductus venosus agenesis as the result of extrahepatic umbilical vein drainage.

STUDY DESIGN

This was an observational study of 12 fetuses who were diagnosed with these anomalies between 1995 and 2001.

RESULTS

The umbilical vein drained either directly into the right atrium (n = 7 fetuses), the inferior vena cava (n = 3 fetuses), or the iliac vein (n = 2 fetuses). Combined cardiac output (n = 8 fetuses) was nearly 2-fold increased to 891 +/- 210 mL/kg per minute. Other relevant findings were (1) considerable umbilical vein enlargement (12/12 cases; range, 8-13 mm) with an accelerated (peak, 0.53 +/- 0.1 m/s), (2) pulsatile Doppler flow pattern within its intra-abdominal course, (3) cardiomegaly (12/12 fetuses), (4) secundum atrial septal defects (5/12 fetuses), (5) extracardiac anomalies (5/12 fetuses), (6) polyhydramnios (4/12 fetuses), and (7) progressive heart failure (3/12 fetuses). Two fetuses died: 1 death was unexplained at 29 weeks of gestation; the other death from hydrops occurred after delivery at 32 weeks of gestation. So far, none of the survivors have had other long-term sequelae that were related to ductus venosus agenesis.

CONCLUSION

Careful assessment of the umbilical venous return and the ductus venosus should be part of the routine evaluation of every fetus with heart failure and polyhydramnios.

Minor neurological signs and developmental performance in high risk children at preschool age

The aim of this study was to establish correlations between minor neurological findings and developmental performance. A cohort of 72 preschool children was studied (38 females, 34 males; mean age 3 years 8 months, SD 1 year 2 months, range 2 to 5 years) who were considered to be at high risk due to placental insufficiency. The cohort was divided into four categories of neurological status: (1) minimal cerebral palsy (MCP) with independent walking before age 2 years; (2) Amiel-Tison triad (ATT) including imbalance of passive axial tone, phasic stretch reflex in triceps surae, and cranial signs, particularly on the squamous suture; (3) intermediate with one or two of the three ATT signs; and (4) absence of neurological findings. Six subscales of the Griffiths Mental Developmental Scales assessing locomotion, eye-hand coordination, interpersonal skills, language, performance, and practical reasoning were administered. Significant differences were found according to neurological status in three specific domains of development: coordination (F=2.84, p=0.04), language (F=3.65, p=0.02), and practical reasoning (F=3.62, p=0.02). In addition, significant differences were also found in language (L) and practical reasoning (R) performances according to the side of the abnormal stretch reflex: bilateral stretches (L=87.8; R=75.3) or an isolated right stretch (L=95.3; R=83.6) are more strongly associated with impaired developmental performances than an isolated left stretch (L=101.3; R=88.2) with F=2.94; p=0.04 for language and F=3.00, p=0.04 for practical reasoning. We concluded that a short neurological examination, easily performed by pediatricians and family practitioners, can identify permanent markers of minor brain damage occurring before, during, or soon after birth and so anticipate consequences.

Prostanoid receptors: ontogeny and implications in vascular physiology

Prostanoids exert significant effects on circulatory beds. They play a role in the response of the vasculature to adjustments in perfusion pressure and oxygen and carbon dioxide tension, and they mediate the actions of numerous factors. The role of prostanoids in governing circulation of the perinate is suggested to surpass that in the adult. Prostanoids are abundantly generated in the perinate. They have been implicated in autoregulation of blood flow as studied in brain and eyes. Prostaglandins are also dominant regulators of ductus arteriosus tone. The effects of these autacoids are mediated through specific G protein-coupled receptors. In addition to the pharmacological characterization of the prostanoid receptors, important advances in understanding the biology of these receptors have been made in the last decade. Their cloning and the development of animals with disrupted genes of these receptors have been very informative. The involvement of prostanoid receptors in the developing subject, especially on brain and ocular vasculature and on ductus arteriosus, has also begun to be investigated; the expression of these receptors changes with development. Some but not all of the ontogenic changes in these receptors are attributed to homologous regulation. Interestingly, in the process of elucidating their effects, functional perinuclear prostaglandin E2 receptors have been uncovered. This article reviews prostanoid receptors and addresses implications on the developing subject with attention to vascular physiology.

[Investigation of fetal arrhythmias by simultaneous recording of ascending aortic and superior vena caval blood flow]

In a period of 18 consecutive months, all the foetus referred to our Foetal Cardiology Unit for investigation of arrhythmia were systematically assessed by M mode echocardiography and simultaneous recording of blood flow in the superior vena cava and the aorta (SVC/Ao). This study was undertaken to compare the performance of these two approaches. The foetus were classified into three groups according to the arrhythmia diagnosed: Group 1: irregular arrhythmias, Group 2: bradycardias, Group 3: tachycardias. A surface ECG was recorded in all the neonates in whom the arrhythmias persisted. In Group 1, including 50 cases of extrasystoles (49 atrial and 1 ventricular), M mode echo and the Doppler provided the diagnosis in 42 and 47 cases respectively. This difference was not statistically significant. Group 2 comprised four cases of bradycardia (2 blocked atrial bigeminy, 2 complete atrioventricular blocks); the two methods provided the diagnosis in all 4 cases. Group 3 comprised 11 cases including 7 supraventricular tachycardias (SVT), 2 flutter, 1 chaotic atrial rhythm and 1 ectopic junctional rhythm. Complete analysis of these arrhythmias was possible by M mode in 4 cases and by Doppler in all cases. This difference was significant. The distribution of the 7 cases of SVT with respect to the duration of the ventriculoatrial interval was possible by M mode in 2 cases and in all cases by Doppler. This was a decisive factor in the choice of antiarrhythmic therapy. The authors conclude that Doppler and M mode are two echocardiographic approaches which are equally effective in the investigation of foetal atrial extrasystoles and probably of sustained foetal bradycardia. However, Doppler recording of SVC/Ao gives a more detailed and precise diagnosis of more complex foetal arrhythmias.

Characterization of PGE2 receptors in fetal and newborn lamb ductus arteriosus

Although the role of PGE2 in maintaining ductus arteriosus (DA) patency is well established, the specific PGE2 receptor subtype(s) (EP) involved have not been clearly identified. We used late gestation fetal and neonatal lambs to study developmental regulation of EP receptors. In the fetal DA, radioligand binding and RT-PCR assays virtually failed to detect EP1 but detected EP2, EP3D, and EP4 receptors in equivalent proportions. In the newborn lamb, DA total density was one-third of that found in the fetus and only EP2 was detected. Stimulation of EP2 and EP4 increased cAMP formation and was associated with DA relaxation. Though stimulation of EP3 inhibited cAMP formation, it surprisingly relaxed the fetal DA both in vitro and in vivo. This EP3-induced relaxation was specifically diminished by the ATP-sensitive K(+) (K(ATP)) channel blocker glibenclamide. In conclusion, PGE2 dilates the late gestation fetal DA through pathways that involve either cAMP (EP2 and EP4) or K(ATP) channels (EP3). The loss of EP3 and EP4 receptors in the newborn DA is consistent with its decreased responsiveness to PGE2.

Characterization of PGE2 receptors in fetal and newborn ductus arteriosus in the pig

We compared the total density and the relative expression of EP receptor (EP) subtypes in ductus arteriosus (DA) of the newborn with that of the fetal piglet. Saturation binding experiments showed 3-fold less PGE2 receptors in the newborn than in the fetus because of loss of EP3 and EP4 receptors thus explaining, at least partly, the reduced responsiveness to PGE2 of the newborn DA. Displacement experiments showed that the relative proportions of EP2, EP3, and EP4 were similar in the fetal DA but only EP2 was detected in the DA of the newborn pig. Hence, PGE2 effects in the newborn DA seem to be exclusively mediated by EP2 receptors both in vitro and in vivo. These findings may help to propose more specific therapies for regulation of DA's tone in certain newborns for whom conventional therapy is contraindicated.

Fetal cardiac performance in uncomplicated and well-controlled maternal type I diabetes

OBJECTIVE

To study the impact of well-controlled, uncomplicated maternal diabetes on fetal cardiac development and performance.

METHODS

The following variables were studied in 45 fetuses of type I diabetic women by means of mid- and late-trimester echocardiography: interventricular septal thickness; aortic and pulmonary valve diameters; peak and time-to-peak flow velocity of the great arteries; the ratio between peak velocities during early (E) and late (A) ventricular filling at the level of the atrioventricular values; ventricular fractional shortenings; and output. The findings were compared to age-matched control groups of normal fetuses.

RESULTS

A significant augmentation of interventricular septal thickness was demonstrated for mid-trimester fetuses of diabetic women, which progressed further towards the end of pregnancy. However, the indices of diastolic and systolic function remained comparable between the gestational age-matched groups.

CONCLUSION

Progressive myocardial thickening occurs commonly in mid- and late-trimester fetuses of uncomplicated and well-controlled diabetic pregnancies. The observed degree of hypertrophy is generally mild and does not affect age-related changes in fetal cardiac function.

Generation of reactive O2 species in the myocardium of newborn lambs following intrauterine increase in right ventricular pressure

Fetuses with pulmonary stenosis and constriction of the ductus arteriosus or the recipient twin in the context of a twin-to-twin transfusion syndrome may present with severe right ventricular myocardial dysfunction. Free O2 radicals are known to be increased in hypertrophied adult myocardium secondary to an increase in endocavitary pressure. This study investigates whether products of reactive O2 species generation are abnormally elevated in the myocardium of fetuses with increased right ventricular pressure. Banding of the main pulmonary artery was performed in five fetal lambs at 90 to 100 days of gestation. Three other animals had a sham intervention and were used as controls. Postoperative observation lasted on average 42 days (range 33-49 days). The levels of hydroperoxides were found to be significantly higher in the right ventricle of the stenosed lambs (6.6 +/- 3.5 nmol/mg protein) compared to the left ventricle of the same lambs (0.7 +/- 0.7 nmol/mg protein), and compared to the right (0.12 +/- 0.1 nmol/mg protein) and the left (0.5 +/- 0.8 nmol/mg protein) ventricles of the controls. It is concluded that during fetal life, an increase in right ventricular pressure is associated with a marked accumulation of products of reactive O2 species generation in the right ventricular myocardium.

Prenatal diagnosis of junctional ectopic tachycardia

The congenital form of junctional ectopic tachycardia has never been reported during the prenatal period. We describe a case in which the diagnosis could be ascertained in utero with the superior vena cava/ascending aorta Doppler approach. The diagnosis was based on the evidence of ventricular tachycardia with atrioventricular (AV) dissociation and the simultaneous occurrence of atrial and ventricular contractions during an episode of tachycardia with 1:1 AV relationship.

Correlation between prenatal velocity waveforms in the aortic isthmus and neurodevelopmental outcome between the ages of 2 and 4 years

OBJECTIVE

Experimental studies on fetal lambs have shown that during an increase in the resistance to placental flow the delivery of oxygen to the brain is preserved as long as net flow through the aortic isthmus is antegrade. Our purpose was to determine whether the same changes in aortic isthmus flow in human subjects have any impact on neurodevelopmental outcome.

STUDY DESIGN

Forty-four fetuses were retrospectively included in this study on the basis of an abnormal Doppler velocity in the umbilical artery. Mean gestational age at delivery was 33.0 +/- 2.0 weeks and mean birth weight 1386 +/- 435 g. The neurodevelopmental condition was assessed between the ages of 2 and 4 years. The developmental score was analyzed in relation to the flow patterns in the fetal aortic isthmus, which were classified as follows: group A, net isthmic flow antegrade (defined as the ratio of the systolic antegrade to the diastolic retrograde velocity integrals) (n = 39); group B, net isthmic flow retrograde (n = 5).

RESULTS

Nonoptimal neurodevelopment was observed in 19 (49%) of 39 fetuses in group A and in all 5 fetuses (100%) in group B. This difference is significant and leads to a relative risk of 2.05 (95% confidence interval, 1.49-2.83) for neurodevelopmental deficit when predominantly retrograde flow is observed in the fetal aortic isthmus before birth.

CONCLUSION

Measuring the ratio of antegrade to retrograde velocity integrals in the aortic isthmus could help in the indirect assessment of cerebral oxygenation during placental circulatory insufficiency.

Doppler and M-mode ultrasonography to time fetal atrial and ventricular contractions

OBJECTIVE

To compare ease of recording and reliability of ultrasonographic approaches used to time fetal heart atrial and ventricular contractions.

METHODS

Seventeen consecutive fetuses seen at our fetal cardiology unit for possible fetal cardiac arrhythmia were included in this study. The same ultrasonographer obtained M-mode tracings of atrial and ventricular free walls, atrial wall and opening of the aortic valves, a peak of the mitral valve, and the opening of the aortic valves; and Doppler signals of flow-velocity waveforms in the outflow tract of the left ventricle and simultaneous flow-velocity waveforms in the aorta and superior vena cava. The outcome measures were rate of successful attempts and intra- and interobserver reliability coefficients.

RESULTS

Valid recordings were made for all patients with one M-mode (atrial and ventricular free walls) and two Doppler (intraventricular, superior vena cava, and ascending aorta) approaches. Atrioventricular intervals were significantly longer with M-mode compared with Doppler ultrasonography. Reliability coefficients were excellent (at least 0.89) for all intraobserver measurements. Comparisons of atrioventricular and ventriculoatrial interval measurements made by two observers gave the following intraclass correlation coefficients (95% confidence interval): atrioventricular = M-mode: 0.87 (0.79, 0. 91), left ventricular outflow: 0.93 (0.89, 0.96), superior vena cava-aorta: 0.98 (0.97, 0.99); ventriculoatrial = M-mode: 0.79 (0.67, 0.87), left ventricular outflow: 0.97 (0.95, 0.98); superior vena cava-aorta: 0.99 (0.98, 0.99).

CONCLUSION

Fetal atrioventricular intervals measured indirectly from M-mode or Doppler tracings were equally reliable when measured by the same observer; the Doppler approaches had better correlation between measurements made by two different observers.

Isolated ductus arteriosus aneurysm in the fetus and infant: a multi-institutional experience

OBJECTIVES

The purpose of this study was to describe the clinical characteristics and outcome and to elucidate the pathogenesis of ductus arteriosus aneurysm (DAA).

BACKGROUND

Ductus arteriosus aneurysm is a rare lesion that can be associated with severe complications including thromboembolism, rupture and death.

METHOD

We reviewed the clinical records, diagnostic imaging studies and available histology of 24 cases of DAA, diagnosed postnatally (PD) in 15 and antenatally (AD) in 9 encountered in five institutions.

RESULTS

Of PD cases, 13 presented at <2 months, and all AD cases were detected incidentally after 33 weeks of gestation during a late trimester fetal ultrasound study. Of the 24, only 4 had DAA-related symptoms and 6 had associated syndromes: Marfan, Smith-Lemli-Opitz, trisomies 21 and 13 and one possible Ehlers-Danlos. Three had complications related to the DAA: thrombus extension into the pulmonary artery, spontaneous rupture, and asymptomatic cerebral infarction. Six underwent uncomplicated DAA resection for ductal patency, DAA size or extension of thrombus. In the four examined, there was histologic evidence of reduced intimal cushions in two and abnormal elastin expression in two. Five of the 24 died, with only one death due to DAA. Of 19 survivors, all but one remain clinically asymptomatic at a median follow-up of 35 months; however, two have developed other cardiac lesions that suggest Marfan syndrome. A review of 200 consecutive third trimester fetal ultrasounds suggests an incidence of DAA of 1.5%.

CONCLUSIONS

Ductus arteriosus aneurysm likely develops in the third trimester perhaps due to abnormal intimal cushion formation or elastin expression. Although it can be associated with syndromes and severe complications, many affected infants have a benign course. Given the potential for development of other cardiac lesions associated with connective tissue disease, follow-up is warranted.

Reference values for differences between cardio-circulatory variables of normal twin fetuses

BACKGROUND

No reference values exist concerning the differences between cardio-circulatory variables of normal twin fetuses. The normal data could be useful in the identification of conditions causing opposite hemodynamic effects on each twin.

OBJECTIVE

To establish the normal differences among cardio-circulatory parameters of twin fetuses during the second and third trimesters of gestation.

MATERIALS AND METHODS

Twenty-seven normal twin pregnancies were used in this longitudinal and prospective study. Doppler-echocardiographic investigations were performed every 2-3 weeks starting at an average of 23.11 +/- 3.13 (mean +/- standard deviation) weeks' gestation. At each visit, the following cardio-circulatory variables were evaluated: the cardio-thoracic ratio, the ventricular wall and septal thicknesses, end-diastolic and systolic diameters, ventricular fractional shortenings, velocity of circumferential fibre shortenings and left and right ventricular outputs. In addition the following measurements were made from Doppler recordings: through both aortic and pulmonary valve the acceleration and ejection times, the peak systolic velocities and the velocity time integrals; and through both mitral and tricuspid valves peak velocities of E and A waves and the E/A ratios. Finally the pulsatility index of the umbilical artery was also evaluated.

RESULTS

There was no single variable where the intertwin difference changed with gestational age. No systematic difference between the smaller and larger twin could be demonstrated for any variables except for the cardio-thoracic ratio.

CONCLUSION

Reference tables should permit a comparative approach between the two twins in the investigation of life threatening complications such as twin-to-twin transfusion syndrome.