The effect of fetoscopic laser therapy on fetal cardiac size in twin-twin transfusion syndrome

Cardiac adaptation and malformation in twin-twin transfusion syndrome and selective fetal growth restriction: A systematic review

OBJECTIVES

This systematic review explores cardiac adaptation in monochorionic (MC) twins with twin-twin transfusion syndrome (TTTS) or selective fetal growth restriction (sFGR) and assesses the risk of congenital heart defects (CHDs).

METHODS

Adhering to PRISMA guidelines, 63 studies were reviewed (49 on cardiac adaptation, 13 on CHD, one on both). A narrative synthesis of cardiac adaptation patterns was performed. Additionally, a meta-analysis compared the livebirth prevalence of CHD in TTTS and sFGR against uncomplicated MC twins.

RESULTS

In TTTS recipients, cardiac function may be impaired for diastolic, systolic, as well as global functions, while in donors, cardiac function is generally preserved. In sFGR, large twins may show hypertrophic cardiomyopathy, and small twins may show impaired systolic function. Co-occurrence of TTTS and sFGR magnifies cardiac impact but is often underreported. Meta-analysis for CHD prevalence revealed a relative risk ratio of 3.5 (95% CI: 2.5-4.9) for TTTS and 2.2 (95%CI: 1.3-3.5) for sFGR compared with uncomplicated MC twins.

CONCLUSIONS

This study highlights the well-documented cardiac adaptation in TTTS, contrasting with limited understanding in sFGR. Elevated CHD risks were observed in both conditions. Enhanced cardiovascular surveillance is warranted in complicated MC twin pregnancies. Future research should explore cardiac adaptation in sFGR and its long-term consequences.

Uncomplicated Monochorionic Twins: Two Normal Hearts Sharing One Placenta

Cardiovascular dysfunction has been reported in complicated monochorionic diamniotic (MCDA) pregnancies; however, little is known whether hemodynamic changes occur in uncomplicated MCDA twins. A prospective observational study was conducted including 100 uncomplicated MCDA twins matched by gestational age to 200 low-risk singletons. Echocardiography was performed at 26-30 weeks gestation and cord blood B-type natriuretic peptide (BNP) was measured at delivery. In both groups, z-scores for echocardiographic parameters were within normal ranges; however the monochorionic group had larger atrial areas (mean (standard deviation) right atria-to-heart ratio: 17.0 (2) vs. 15.9 (1); p = 0.018; left atria-to-heart ratio: 17.0 (3) vs. 15.8 (2); p < 0.001) and signs of concentric hypertrophy (right relative wall thickness: 0.66 (0.12) vs. 0.56 (0.11); p < 0.001; left relative wall thickness: 0.69 (0.14) vs. 0.58 (0.12); p < 0.001). Longitudinal function was increased in twins, leading to higher tricuspid annular plane systolic excursion (6.9 mm (0.9) vs. 5.9 mm (0.7); p < 0.001) and mitral annular plane systolic excursion (4.9 mm (0.8) vs. 4.4 mm (1.1); p < 0.001. BNP levels at birth were also higher in MCDA twins (median [interquartile range]: 20.81 pg/mL [16.69-34.01] vs. 13.14 pg/mL [9.17-19.84]; p < 0.001). Thus, uncomplicated MCDA fetuses have normal cardiac shape and function, but signs of cardiac adaptation were identified by echocardiographic and biochemical parameters, when compared with singletons.

Early postnatal cardiac follow-up of survivors of twin-twin transfusion syndrome treated with fetoscopic laser coagulation

OBJECTIVE

To assess the cardiac function and prevalence of congenital heart defects (CHD) in twin-twin transfusion syndrome (TTTS) survivors.

STUDY DESIGN

Prospective follow-up of TTTS pregnancies treated with laser surgery (2015-2018). Echocardiography was performed 1 day and 1 month after birth (corrected for prematurity). Results were compared with a control group of age-matched uncomplicated monochorionic twin-pairs at 1 month.

RESULT

Eighty-nine TTTS (168 neonates) and nine control pregnancies (18 neonates) were enrolled. CHD birth prevalence was 9.2% (8/87) in recipients and 13.6% (11/81) in donors (p = 0.37). Four of 19 (21%) were detected prenatally, all pulmonary stenosis. Donors had lower aortic peak velocities compared with recipients at day 1 (0.66 ± 0.15 m/s vs 0.71 ± 0.19 m/s, p = 0.04) and 1 month (1.04 ± 0.21 m/s vs 1.11 ± 0.18 m/s, p = 0.02), but not compared with controls.

CONCLUSION

CHD prevalence in TTTS survivors is high, with a low prenatal detection of minor abnormalities. Follow-up fetal echocardiograms and a postnatal echocardiogram should be offered.

Congenital Heart Defects in Monochorionic Twins: A Systematic Review and Meta-Analysis

Monochorionic (MC) twins are at an increased risk of developing congenital heart defects (CHDs) compared to singletons and dichorionic twins. The development of acquired CHDs in this specific group of twins is associated with twin-twin transfusion syndrome (TTTS). We performed a systematic review and meta-analysis to provide an overview of the reported birth prevalence of CHDs in liveborn MC twins with and without TTTS. Twelve studies were included in this review. Compared to the reference population, MC twins were 6.3 times more likely to be born with a CHD (59.3 per 1000 liveborn twins; relative risk (RR) 6.3; 95% confidence interval (CI): 4.4-9.1), and TTTS twins had a 12-fold increased risk of having a CHD at birth (87.3 per 1000 live births; RR 12.4, 95% CI: 8.6-17.8). The increased incidence of CHDs can mainly be attributed to the risk of right ventricular outflow tract obstruction (35/1000 TTTS twin live births vs. 0.5/1000 singleton live births). We recommend an expert fetal echocardiogram in all MC twins, follow-up scans in the event of TTTS, and a postnatal cardiac evaluation in all TTTS survivors.

Acquired right ventricular outflow tract obstruction in twin-to-twin transfusion syndrome; a prospective longitudinal study

OBJECTIVE

The pathophysiology of right ventricular outflow tract obstruction (RVOTO) in twin-to-twin transfusion syndrome (TTTS) recipients is incompletely understood. We aimed to investigate the development and spectrum of RVOTO in TTTS recipients.

METHODS

A prospective longitudinal cohort study was conducted between 2015 and 2017. Echocardiographic assessment was performed in recipients from TTTS diagnosis until the neonatal period.

RESULTS

Prenatal RVOTO, defined as abnormal flow velocity waveforms across the pulmonary valve (PV), was diagnosed in 12.9% (16/124) of recipients at TTTS diagnosis. Postnatal RVOTO was found in 6.7% (7/105) of surviving recipients. All recipients with severe postnatal RVOTO showed prenatal RVOTO at TTTS diagnosis. In 5.6% (6/108) of cases, prenatal RVOTO appeared only after laser therapy, and in 1.9% (2/108), this progressed to mild postnatal pulmonary stenosis. Elevated peak systolic PV velocities were more frequently associated with postnatal RVOTO compared with prenatal finding of functional pulmonary atresia. Postnatal RVOTO was associated with early manifestation of TTTS but was equally found in all Quintero stages.

CONCLUSION

In the spectrum of postnatal RVOTO, severe cases show prenatal RVOTO at TTTS diagnosis. However, RVOTO can develop after laser or even in the neonatal period and in all Quintero stages. A potential risk factor for postnatal RVOTO is early TTTS manifestation.

Echocardiographic Methods of Fetal Heart Size Assessmentheart to Chest Area Ratio and Transversal Heart Diameter

Introduction: Ultrasound assessment of fetal heart size (FHS) is widely used and recommended in many guidelines of fetal echocardiography due to its clinical value. The aim of this study was an analysis of some fetal heart measurements: ratio of heart area to chest area (HA/ CA) and transversal diameter of heart (AP) and their correlation to gestational age.

Material and methods: This retrospective study was based on database of records of ultrasound and echocardiographic examinations performed in our unit and included fetuses between 15th and 39th week of gestation with no evidence of heart defect or any abnormality.

Results: 609 ultrasound examinations were analyzed. The mean HA/CA was 0,30 ± 0,015, with no statistical difference between female and male (p>0,05), and seemed to be relatively constant with slight increase with advancing gestational age. The AP diameter in whole group correlated with gestational age (r=0,94) and there was no difference related to the fetuses gender.

Conclusion: The correlation of AP diameter and relative constancy of HA/CA ratio with gestational age presented in our normograms could be used for monitoring fetal development, but also for fetal cardiomegaly assessment.

Right ventricular outflow tract obstruction in complicated monochorionic twin pregnancy

OBJECTIVES

Severe right ventricular outflow tract obstruction (RVOTO) is a potential complication in recipient twins of twin-to-twin transfusion syndrome (TTTS) that requires postnatal follow-up or treatment. We aimed to evaluate pregnancy characteristics of neonates with RVOTO from complicated monochorionic twin pregnancies, determine the incidence of RVOTO in TTTS cases and construct a prediction model for its development.

METHODS

This was an observational cohort study of all complicated monochorionic twin pregnancies with a postnatal diagnosis of RVOTO examined at our center. Cases were referred for evaluation of the need for fetal therapy or intervention because of TTTS, selective intrauterine growth restriction (sIUGR) or multiple congenital malformations in one of the twins. Ultrasound data were retrieved from our monochorionic twin database. Among liveborn TTTS recipients treated prenatally with laser therapy, those with RVOTO were compared with those without RVOTO (controls). We describe four additional cases with RVOTO that were not TTTS recipients.

RESULTS

A total of 485 twin pregnancies received laser therapy for TTTS during the study period. RVOTO was diagnosed in 3% (11/368) of liveborn TTTS recipients, of whom two showed mild Ebstein's anomaly. Before laser therapy, pericardial effusion was seen in 45% (5/11) of RVOTO cases (P < 0.01) and abnormal A-wave in the ductus venosus (DV) in 73% (8/11) (P = 0.03), significantly higher proportions than in controls. Mean gestational age at laser therapy was 17 + 3 weeks in RVOTO cases compared with 20 + 3 weeks in controls (P = 0.03). A prediction model for RVOTO was constructed incorporating these three significant variables. One TTTS donor had RVOTO after the development of transient hydrops following laser therapy. Three larger twins in pregnancies complicated by sIUGR developed RVOTO, the onset of which was detectable early in the second trimester.

CONCLUSIONS

RVOTO occurs in TTTS recipient twins but can also develop in TTTS donors and larger twins of pregnancies complicated by sIUGR. Abnormal flow in the DV, pericardial effusion and early gestational age at onset of TTTS are predictors of RVOTO in TTTS recipients, which suggests increased vulnerability to hemodynamic imbalances in the fetal heart in early pregnancy. These findings could guide diagnostic follow-up protocols after TTTS treatment. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Cardiac Manifestations of Twin–to–Twin Transfusion Syndrome

This review addresses the physiology of monochorionic diamniotic (MC/DA) twins and the potential for twin–twin transfusion syndrome (TTTS). It focuses on the underlying cardiovascular pathophysiology of TTTS and the cardiovascular impact of TTTS for both the recipient and the donor twin. It explains the principles for assessment and monitoring of these cardiovascular changes and how these may be used to guide pregnancy management. Finally, it describes the effect of treatment on the altered hemodynamics and how this can influence pregnancy and perinatal management, as well as longer-term follow-up.

Blood pressure evaluation in children treated with laser surgery for twin-twin transfusion syndrome at 2-year follow-up

OBJECTIVE

Twin survivors of twin-twin transfusion syndrome (TTTS) may be at risk for early onset of cardiovascular disease. The aim of this study was to determine prevalence and risk factors for elevated blood pressure (BP) among children treated with selective laser photocoagulation of communicating vessels.

STUDY DESIGN

Data were prospectively collected from surviving children treated for TTTS with laser surgery from 2008 through 2010. Systolic BP (SBP) and diastolic BP (DBP) were obtained from 91 child survivors at age 24 months (±6 weeks) and evaluated based on age, sex, and height percentile. BP percentiles were calculated for each patient and categorized as normal (<95%) or abnormal (>95%). Clinical variables were evaluated using multilevel regression models to evaluate risk factors for elevated BP.

RESULTS

BP was categorized as normal in 38% and abnormal in 62% of twin survivors based on percentile for sex, age, and height; a comparable distribution was found for DBP elevation. There were no differences between donor and recipient twins for absolute SBP and DBP or BP classification. In a multivariate analysis, significant risk factors for higher SBP included prematurity (β -0.54; 95% confidence interval [CI], -0.99 to -0.09; P = .02), higher weight percentile (β 0.24; 95% CI, 0.05-0.42; P = .01), and presence of cardiac disease (β 0.50; 95% CI, 0.10-0.89; P = .01). Prematurity was also a significant risk for abnormal DBP (odds ratio, 0.89; 95% CI, 0.80-1.00; P = .05).

CONCLUSION

Child survivors of TTTS had elevated SBP and DBP measurements at 2 years of age, with no differences seen between former donor and recipient twins. Prematurity may be a risk factor for elevated BP measurements in this population. Future studies are warranted to ascertain whether these cardiovascular findings persist over time.

Intertwin cardiac status at 10-year follow-up after intrauterine laser coagulation therapy of severe twin-twin transfusion syndrome: comparison of donor, recipient and normal values

BACKGROUND

In twin-to-twin transfusion syndrome (TTTS), genetically identical twins are exposed to different haemodynamic conditions during fetal life, which are considered to be the cause of prenatal and postnatal cardiovascular differences between the donor and the recipient.

OBJECTIVE

To assess intertwin differences on childhood cardiac outcome after intrauterine laser coagulation therapy (LC) of severe TTTS.

DESIGN AND PATIENTS

Prospective, detailed, echocardiographic follow-up of 31 twin pairs aged 9.95±0.8 years (mean±SD) with severe TTTS treated by LC, and the comparison with reference values.

RESULTS

Cardiac function was normal and did not show intertwin differences in twins without structural heart disease. Discordant birth weight or birth weight <3rd centile for gestational age had no influence on blood pressure and cardiac indices. Pulmonary stenosis was more common (5/62; 8.1%) than in the general population (prevalence 0.066%, relative risk 134.4, 95% CI 42.1 to 428.8, p<0.0001) and affected both donor and recipient. Intertwin differences in late diastolic right ventricular filling (peak velocities: recipient 0.51±0.11 m/s vs donor 0.45±0.10 m/s, mean difference 0.74 m/s, 95% CI 0.23 to 1.24, p=0.009) and early septal relaxation (mean myocardial velocities: recipient -8.2±1.5 cm/s vs donor -8.9±1.2 cm/s, mean difference 0.7 cm/s, 95% CI 0.02 to 1.38, p=0.044) were found only when twins with right heart disease were included.

CONCLUSIONS

Despite severe prenatal cardiac involvement, childhood cardiac function is normal in the majority of surviving donors and recipients after successful LC of severe TTTS. This underlines the favourable impact of intrauterine LC on postnatal cardiovascular performance.

Long-term outcome after intrauterine laser treatment for twin-twin transfusion syndrome

Twin-twin transfusion syndrome (TTTS) is a severe complication occurring in about 10% of monochorionic twin pregnancies. The chronic unbalanced transfusion of blood across placental vascular communications from the donor to the recipient twin may lead to impairment of various organ systems in the affected twins. In Hamburg, Germany, since 1995 patients with TTTS were treated with fetoscopic laser coagulation as the first causal therapeutic strategy. All survivors after laser surgery were followed up in the University Children's Hospital in Bonn, Germany. In this article, we summarize long-term follow-up studies from our German study population and compare our results with data from the literature.

Effect of selective fetoscopic laser photocoagulation therapy for twin-twin transfusion syndrome on pulmonary valve pathology in recipient twins

OBJECTIVE

To investigate the impact of selective fetoscopic laser photocoagulation (SFLP) on pre-existing pulmonary valve pathology in the recipient twin in twin-twin transfusion syndrome (TTTS).

METHODS

We evaluated preoperative echocardiograms of all pregnancies with TTTS treated with SFLP at our institution from 2001 to 2009 (n = 76). Sixteen (21%) recipients had an abnormal pulmonary valve (stenosis/dysplasia, insufficiency or functional atresia) before SFLP. Postoperative echocardiograms and medical records from these 16 recipients were reviewed. Changes in pulmonary valve structure and function, and overall cardiac function, were noted after SFLP.

RESULTS

The mean gestational age at SFLP was 21 (range, 18.7-24.3) weeks. Seven of sixteen (44%) recipients with abnormal pulmonary valve prior to SFLP survived. Six of the 16 (37.5%) recipient twins had documented absence of persistent pulmonary valve abnormalities at birth or at autopsy. Two (12.5%) of the 16 recipients (2.6% of the original cohort) had persistent pulmonary valve abnormalities at birth, requiring intervention. Systolic and diastolic function improved or normalized after SFLP in all patients undergoing longitudinal follow-up. There was a tendency for a better cardiovascular profile score (best = 10 points) at initial evaluation in pregnancies with survivors compared with those with no survivors (mean (SD): 5.6 (2.2) vs. 6.75 (1.28)), but this was not statistically significant. Severity of cardiac involvement did not predict persistence of valve pathology or survival.

CONCLUSIONS

SFLP can improve flow through the pulmonary valve of the recipient twin in TTTS, probably as a consequence of improvements in right ventricular systolic and diastolic function. However, pulmonary valve pathology may persist and require postnatal intervention.

The relationship between amniotic fluid levels of brain-type natriuretic peptide and recipient cardiomyopathy in twin-twin transfusion syndrome

OBJECTIVE

We sought to evaluate amniotic fluid brain natriuretic peptide (BNP) levels as a biomarker of recipient twin (RT) cardiomyopathy (RTCM) in twin-twin transfusion syndrome.

STUDY DESIGN

Amniotic fluid samples were obtained from 157 twin-twin transfusion syndrome RTs and from 6 singletons (controls) from 2007 through 2009. N-terminal prohormone BNP (NT-proBNP) levels were quantified by enzyme-linked immunosorbent assay. RTCM was classified as mild (IIIA), moderate (IIIB), or severe (IIIC) by fetal echocardiography. The relationship between NT-proBNP and RTCM was evaluated using analysis of variance. The ability of NT-proBNP to predict moderate or greater RTCM was evaluated by receiver operating characteristic analysis.

RESULTS

There is a significant positive correlation between NT-proBNP levels and worsening RTCM (r = 0.33; P < .001). NT-proBNP thresholds of 569 fmol/mg and 369 fmol/mg had a sensitivity of 70% and 87%, and specificity of 67% and 42%, respectively, in predicting moderate or greater RTCM.

CONCLUSION

This is the first large case series that demonstrates a relationship between NT-proBNP and RTCM. This pathophysiologic insight supports ongoing efforts to develop screening biomarkers.

The Fetal Heart in Twin-to-Twin Transfusion Syndrome

Twin-to-twin transfusion syndrome is a severe complication occurring in 10% of monochorionic twin pregnancies. The disease is usually explained as due to an intrauterine imbalance in intertwin blood exchange, which leads to a volume depleted-donor twin and an overfilled recipient twin. The recipient has signs of cardiac dysfunction, which can be measured using echocardiography or blood and amniotic fluid derived biomarkers. Whereas cardiac dysfunction typically progresses in pregnancies treated with amniodrainage, it usually disappears within a few weeks after fetoscopic laser coagulation of the connecting intertwin anastomoses. Nevertheless, recipients remain at a increased risk of pulmonary stenosis. In this paper, we summarize the cardiac alterations in twin-to-twin transfusion syndrome, describe the changes seen after fetal therapy, list the newly proposed staging systems based on fetal cardiac function, and make recommendations about the use of fetal echocardiography in the evaluation and followup of pregnancies complicated by twin-to-twin transfusion syndrome.

Twin-to-twin transfusion syndrome: a comprehensive update

Twin-to-twin transfusion syndrome (TTTS) is a serious complication in about 10% to 20% of monozygous twin gestations with an incidence of 4% to 35% in the United States. Severe TTTS is reported to occur in 5.5% to 17.5% of cases. TTTS is a progressive disease in which sudden deteriorations in clinical status can occur, leading to death of a co-twin. Up to 30% of survivors may have abnormal neurodevelopment as a result of the combination of profound antenatal insult and the complications of severe prematurity. This article presents an overview of what is known about the pathophysiology and the diagnosis of TTTS, the role of echocardiography in TTTS, treatment options available for TTTS, complications of treatment for TTTS, and short- and long-term outcomes of TTTS.