Twin-to-twin transfusion syndrome: perinatal outcome and recipient heart disease according to treatment strategy

Fetal cardiovascular alterations in twin-to-twin transfusion syndrome

Twin-to-twin transfusion syndrome (TTTS) is the consequence of vascular anastomoses of the shared placenta of monochorionic twin pregnancies. Both circulating inter-twin blood flow and vasoactive mediators imbalance cause hypovolemia in the donor and hypervolemia in the recipient fetus. If left untreated, TTTS has a high perinatal mortality rate and adverse long-term outcomes mainly cardiovascular and neurological. The recipient has cardiovascular changes including atrioventricular valve regurgitation, diastolic dysfunction and pulmonary stenosis/atresia. The maladaptive response to vascular changes determines a constant decreased blood flow in the donor that permanently modifies the arterial structure leading to postnatal alterations in the vascular system. Fetoscopic LASER surgery of placental vascular anastomoses may disrupt the underlying pathophysiology and improves cardiovascular function with normalization of systolic and diastolic function within weeks after treatment. The impact of cardiovascular changes is relevant for the safety of the management of a TTTS case. The improvement of the perinatal survival after intrauterine surgery leads to viable infants with the longer-term sequelae. Therefore accurate quantification of cardiovascular involvement is essential for clinicians for pregnancy management but also for patient counseling about the potential treatment options the outcome.

Neurological complications after therapy for fetal-fetal transfusion syndrome: a systematic review of the outcomes at 24 months

OBJECTIVE

The main objective of this study was to review the available scientific evidence about mid-term neurological outcomes in twins after laser therapy for twin-to-twin transfusion syndrome (TTTS).

METHODS

A systematic review of studies on neurodevelopmental outcomes (cognition, motor development, communication skills and cerebral palsy) of twins after laser therapy for TTTS was conducted. Outcomes at 24 months of age and the use of validated scales for assessment were the selected criteria. Electronic and manual research identified 25 studies, and nine of them were eligible for the review.

RESULTS

The global mean rate of neurological injury in twins treated with laser was 14.07%. The mean rate of cognitive impairment was 8.41%, 11.14% for motor delay, 16.5% for communication delay and 5.73% for cerebral palsy. These rates were higher than the results found in dichorionic twins, but lower than the results found in twins treated with amnio-reductions or conservative management.

CONCLUSION

Laser therapy is associated with a lower rate of neurological injury at 24 months of age compared to other therapeutic techniques. This tendency was also observed with specific incidences regarding cognition, motor skills and cerebral palsy.

Outcome reporting across randomized trials and observational studies evaluating treatments for twin-twin transfusion syndrome: systematic review

OBJECTIVE

Twin-twin transfusion syndrome (TTTS) is associated with significant mortality and morbidity. Potential treatments for the condition require robust evaluation. The aim of this study was to evaluate outcome reporting across observational studies and randomized controlled trials assessing treatments for TTTS.

METHODS

Cochrane Central Register of Controlled Trials, EMBASE and MEDLINE were searched from inception to August 2016. Observational studies and randomized controlled trials reporting outcome following treatment for TTTS in monochorionic-diamniotic twin pregnancy and monochorionic-triamniotic or dichorionic-triamniotic triplet pregnancy were included. Outcome reporting was systematically extracted and categorized.

RESULTS

Six randomized trials and 94 observational studies were included, reporting data from 20 071 maternal participants and 3199 children. Six different treatments were evaluated. Included studies reported 62 different outcomes, including six fetal, seven offspring mortality, 25 neonatal, six early childhood and 18 maternal/operative outcomes. Outcomes were reported inconsistently across trials. For example, when considering offspring mortality, 31 (31%) studies reported live birth, 31 (31%) reported intrauterine death, 49 (49%) reported neonatal mortality and 17 (17%) reported perinatal mortality. Four (4%) studies reported respiratory distress syndrome. Only 19 (19%) studies were designed for long-term follow-up and 11 (11%) of these reported cerebral palsy.

CONCLUSIONS

Studies evaluating treatments for TTTS have often neglected to report clinically important outcomes, especially neonatal morbidity outcomes, and most are not designed for long-term follow-up. The development of a core outcome set could help standardize outcome collection and reporting in TTTS studies. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Fetal cardiovascular hemodynamics in twin-twin transfusion syndrome

Twin-twin transfusion syndrome (TTTS) complicates 10-15% of monochorionic-diamniotic (MCDA) pregnancies. It originates from unbalanced transfer of fluid and vasoactive mediators from one twin to its co-twin via placental anastomoses. This results in hypovolemia in the donor and hypervolemia and vasoconstriction in the recipient twin. Consequently, the recipient demonstrates cardiovascular alterations including atrioventricular valve regurgitation, diastolic dysfunction, and pulmonary stenosis/atresia that do not necessarily correlate with Quintero-stages. Selective fetoscopic laser photocoagulation of placental vascular anastomoses disrupts the underlying pathophysiology and usually improves cardiovascular function in the recipient with normalization of systolic and diastolic function within weeks after treatment. Postnatal studies have demonstrated early decreased arterial distensibility in ex-donor twins, but 10-year follow up is encouraging with survivors showing normal cardiovascular function after TTTS. However, prediction and appropriate early management of TTTS remain poor. Assessment of the cardiovascular system provides additional insight into the pathophysiology and severity of TTTS and may permit more targeted early surveillance of MCDA pregnancies in future. It should form an integral part of the diagnostic algorithm.

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.

Twin-twin transfusion syndrome: a frequently missed diagnosis with important consequences

OBJECTIVE

To evaluate the incidence and consequences of 'misdiagnosed' cases of twin-twin transfusion syndrome (TTTS).

METHODS

Chorionicity and referral diagnoses were reviewed in pregnant women with monochorionic twin pregnancies complicated by TTTS treated with fetoscopic laser ablation. 'Misdiagnosed' cases, defined as failure to correctly identify chorionicity and/or to diagnose TTTS prior to referral, were compared with cases in whom chorionicity and TTTS were diagnosed correctly. TTTS stage, gestational age at referral, overall survival, fetal and perinatal mortality, gestational age at delivery, operating time and maternal complications were compared.

RESULTS

Failure to identify monochorionicity and/or TTTS was observed in 33% (107/323) of referrals to our center. Compared with cases in whom chorionicity and TTTS were correctly diagnosed, misdiagnosed patients were referred at a more advanced stage of disease (Stage IV TTTS: 16.8% vs 7.9%, P = 0.014) and later in pregnancy (gestational age at laser: 20.9 weeks vs 20.1 weeks, P = 0.018). They also delivered more prematurely (30.3 weeks' gestation vs 31.5 weeks' gestation, P = 0.04) and fetal and neonatal mortality were higher (neonatal death within 7 days: 19.6% vs 6.0%, P < 0.001). When the diagnosis was incorrect, major maternal complications and intensive care unit admissions were increased.

CONCLUSIONS

Poor recognition of chorionicity in the first trimester of pregnancy might lead to inadequate ultrasound follow up (failure to assess every 2 weeks) and patient education. Early accurate recognition of both chorionicity and TTTS, with timely referral to a fetal therapy center, are key to ensuring optimal maternal and fetal outcomes.