Current thoughts on twin-twin transfusion syndrome

Assessment of right ventricular function in recipient twin of twin to twin transfusion syndrome with speckle tracking echocardiography

This study was undertaken to evaluate the right ventricular myocardial systolic function and its relation to the fetal volume and pressure overload in recipient twin of twin to twin transfusion syndrome with speckle tracking echocardiography. Longitudinal peak systolic strains of the right ventricle were measured by speckle tracking echocardiography in 17 patients with twin-to-twin transfusion syndrome (TTTS) and 19 normal monochorionic diamniotic pregnancies. The right ventricular free wall thickness in recipient twin (0.43 ± 0.14 cm) was significantly larger than that in the donor (0.21 ± 0.04 cm, p < 0.05) and the control group (0.18 ± 0.03 cm, p < 0.05 for larger twin and 0.17 ± 0.02 cm, p < 0.05 for smaller twin). Although there were no significant differences in the right ventricular fractional shortening and cavity area percent change among control and the TTTS groups, the absolute value of peak systolic strains of ventricular septum, right ventricular free wall and global right ventricle in recipients were all significantly lower than those of the donors and the control group. Besides, the global right ventricular peak systolic strain correlated well with gestational age adjusted right ventricular free wall thickness (r = 0.65, p = 0.04) but not with gestational age adjusted right ventricular end-diastolic dimension (r = 0.38, p = 0.28) and cavity area percent change (r = 0.33, p = 0.35). Right ventricular systolic dysfunction measured with decreased right ventricular peak systolic longitudinal strain exists despite the absence of diminished fractional shortening and cavity area percent change and this reduced systolic function correlates with the right ventricular pressure overload as shown by increased right ventricular free wall thickness.

Search for hemodynamic compromise at 11–14 weeks in monochorionic twin pregnancy: Is abnormal flow in the ductus venosus predictive of twin–twin transfusion syndrome?

BACKGROUND AND OBJECTIVES

Twin-twin transfusion syndrome is a devastating complication of monochorionic twin pregnancies. The presence of increased nuchal translucency thickness (NT) in one of the monochorionic twins has been associated with an increased risk of developing this syndrome. One of the most plausible mechanisms for increased nuchal translucency is heart failure, indirectly manifested by abnormal blood flow in the ductus venosus. We aimed to clarify the pathophysiology of increased NT found more frequently in monochorionic twins prone to develop twin-twin transfusion syndrome.

DESIGN

We present 50 cases of monochorionic twin pregnancies in which nuchal translucency thickness was measured and ductus venosus blood flow evaluation was performed at 11-14 weeks of gestation.

RESULTS

Whenever the fetuses of a twin pregnancy were found to have discrepant nuchal translucency thickness measurements and abnormal flow in the ductus venosus was found in the fetus with increased nuchal translucency thickness, twin-twin transfusion syndrome eventually developed. Progression to twin-to-twin transfusion syndrome was not observed in the twins displaying no intertwin difference in nuchal translucency thickness measurements and it was not observed in those with discrepant nuchal translucency thickness but normal flow in the ductus venosus of both fetuses. In the two cases which developed twin-to-twin transfusion syndrome, fetoscopic laser coagulation of the vascular anastomoses was successfully carried out at 18 weeks and normalization of the venous return was recorded.

CONCLUSIONS

Both increased nuchal translucency and abnormal flow in the ductus venosus in monochorionic twins may be early manifestations of haemodynamic imbalance between donor and recipient. The combined evaluation of both parameters in monochorionic twin pregnancies may constitute an effective method for identifying those at risk of developing twin-to-twin transfusion syndrome.

Prenatal cardiovascular manifestations in the twin-to-twin transfusion syndrome recipients and the impact of therapeutic amnioreduction

OBJECTIVE

We evaluated the cardiovascular pathologic condition in the recipient twin in twin-to-twin transfusion syndrome and the influence of amnioreduction.

STUDY DESIGN

Fetal echocardiograms and medical records of 54 pregnancies that were complicated by twin-to-twin transfusion syndrome were reviewed. Recipient twin right and left ventricular wall thickness, diameters, systolic and diastolic function, valve regurgitation, and structural cardiac defects were assessed at examination and after amnioreduction.

RESULTS

At examination (n = 28 pregnancies), cardiomegaly because of right ventricular and/or left ventricular hypertrophy was observed in 58% of recipient twins, and biventricular hypertrophy was observed in 33% of recipient twins, without ventricular dilation. Biventricular diastolic dysfunction was present in two thirds of recipient twins, and right ventricular systolic dysfunction and significant atrioventricular valve regurgitation was observed in one third of recipient twins. Serial assessment (n = 21 pregnancies) revealed progressive biventricular hypertrophy and right ventricular systolic and biventricular diastolic dysfunction in most recipient twins. Steeper progression of hypertrophy, diastolic dysfunction, and structural or functional right ventricular outflow disease (20% incidence) were associated with an increased perinatal mortality rate.

CONCLUSION

In twin-to-twin transfusion syndrome, the recipient twin has progressive biventricular hypertrophy with predominant right ventricular systolic and biventricular diastolic dysfunction. Despite amnioreduction, the cardiovascular disease persists and even progresses in many recipient twins.

Maternal risk factors for fetal and neonatal brain damage

Prematurity is probably the major factor associated with brain damage in newborns. Our growing knowledge of the biochemical mechanisms leading to the onset of labour at term allows the biochemical correlates of the epidemiological risk factors for prematurity to be understood. Infection is the major cause of early preterm labour and is now recognised to be a major cause of fetal cerebral damage leading to cerebral palsy. Only some 5% of cerebral palsy is due to intrapartum asphyxia at term. This may occur due to an obstetric catastrophe or through inadequate placental function leading to chronic intrapartum asphyxia.

Prenatal diagnosis of twin-twin transfusion syndrome complicated with hydrops fetalis at 14 weeks of gestation

Twin-twin transfusion syndrome (TTTS) may complicate multiple pregnancy. Monochorionic discordant twins with oligohydramnios and polyhydramnios may be diagnostic. Hydrops fetalis is particularly ominous. All the signs can appear independently at any stage of gestation. However, TTTS with hydrops fetalis in early pregnancy is rare. We report here a case of TTTS complicated with hydrops fetalis diagnosed at 14 weeks of gestation. Our case may be one of the earliest cases of the prenatal diagnosis of TTTS complicated with hydrops fetalis in the literature.

Long term outcome of twin-twin transfusion syndrome

AIMS

To compare the perinatal mortality and morbidity of infants with twin-twin transfusion syndrome (TTTS) with those of gestation matched twin controls and to assess the neurodevelopmental outcome of surviving twins with TTTS.

METHODS

A cohort of 17 consecutive pregnancies with TTTS was enrolled over three years together with gestation matched twin pregnancies unaffected by TTTS. Serial amnioreduction for the TTTS pregnancies was performed as appropriate. Perinatal death and neonatal morbidities were recorded for both the TTTS cohort and controls. The TTTS survivors had neurodevelopmental follow up to at least 2 years of age.

RESULTS

In 12 of the pregnancies, serial amniocenteses were performed, but, in five, the infants were born before intervention. The mean gestational age at delivery was 29.1 weeks (range 23-36). There were five intrauterine deaths in the TTTS cohort and six neonatal deaths (survival 68%). In the control group, there was one intrauterine death and five neonatal deaths (survival 82%). Infants in the TTTS group had a greater requirement for inotropes (p = 0.04) and a higher incidence of renal failure (p = 0.005). Periventricular leucomalacia and cerebral atrophy were seen in 17% of the TTTS group, but none of the controls (p = 0.03). The 23 surviving TTTS infants were all followed up, with 22% having significant neurological morbidity: cerebral palsy and global developmental delay.

CONCLUSIONS

Twins with TTTS have high perinatal mortality and neonatal morbidity, and long term neurodevelopmental morbidity in survivors is high. Further investigation into the pathogenesis and management of TTTS is required.

Minimally invasive treatment of twin-to-twin transfusion syndrome

Selective laser photocoagulation of communicating vessels (SLPCV) is an application of minimally invasive endoscopic fetal surgery (i.e., surgical fetoscopy) performed for severe cases of twin-to-twin transfusion syndrome (TTTS), a complication of monochorionic twin pregnancies. Advances in ultrasound and endoscopy have aided the identification and treatment of this potentially lethal or fatal condition. Surgical fetoscopy, an innovation in the field of surgery and maternal-fetal medicine, benefits patients by reducing the morbidity and mortality associated with TTTS, with minimal risks to the mother.

Central nervous system in twin reversed arterial perfusion sequence with special reference to examination of the brain in acardius anceps

The twin-reversed arterial perfusion (TRAP) sequence, or acardia, is the most severe complication in monozygotic twinning. Although more than 400 cases with TRAP sequence were reported since 1533, thorough investigations of the brain in those cases with a rudimentary head remained infrequent. We report a TRAP sequence with microcephaly and a severely rudimentary brain anlage. Neuropathologic examination clearly demonstrated two types of change: (1) developmental arrest of brain at the prosencephalic stage (holoprosencephaly), and (2) hypoxic damage to the holospheric brain mantle with cystic change (hydranencephaly). With reference to previous studies in experimental animals showing that lack of oxygen during early embryogenesis can induce severe disruptions of head-brain and heart formation, it is concluded that oxygen deficiency due to TRAP may be responsible not only for the encephaloclastic changes in the acardius anceps, but for the developmental arrest of the brain cases as well. This would make it unnecessary to postulate additional primary causes such as asymmetric zygote cleavage (Schwalbe, '07) for the maldevelopment.

Treating previable twin-twin transfusion syndrome with fetoscopic laser surgery: outcomes following the learning curve

AIMS

We have performed fetoscopic laser occlusion of chorioangiopagous vessels (FLOC) in previable pregnancies affected by twin-twin transfusion syndrome (TTTS) since 1988. Treatment outcomes obtained after the procedure's learning curve are presented and compared to those from other centers performing FLOC or other treatment methods.

METHODS

A total of 100 cases of FLOC have been performed at our centers. The later 67 TTTS patients had a mean gestational age of 21.1 +/- 1.7 weeks (range 18-24.5) with a mean fundal height of 33.1 +/- 4.9 cm (range 27-44) when treated. Eighteen (27%) had failed another treatment method before FLOC.

RESULTS

All 67 cases have delivered with 82% (55/67) having at least one surviving twin and 93/134 (69%) of the twins surviving overall. Thirty-eight have surviving twins, 17 have one survivor (5 neonatal and 12 fetal deaths), and 12 have none. The mean duration of pregnancy following FLOC was 9.9 +/- 5.5 weeks (range 1.0-19). Only 4 of 93 (4.3%) survivors have significant handicaps at a mean follow-up of 14.3 +/- 10.1 months (range 1.0-34).

CONCLUSION

Fetoscopic laser occlusion of chorioangiopagous vessels within the vascular equator limits the duration of fetal pathophysiology in TTTS and results in neonatal outcomes superior to the modified procedure and other treatment methods.

Twin-twin transfusion syndrome: the challenge of etiology-based management decisions

Studies published in the past year have attempted to model the pathophysiology of the twin-twin transfusion syndrome and also to establish the minimal diagnostic criteria for the condition. Many papers focused on treatment regimens and their sequelae. Aggressive treatment with serial amnioreduction continues to predominate, and appears to be more successful than conservative medical management, whereas selective feticide is reserved for cases that fail to respond to amnioreduction. Small series utilizing laser ablation and amniotic septostomy appeared; with laser proponents suggesting that their approach may carry a lower risk of neurological sequelae. Progress in ultrasound and Doppler techniques has begun to yield earlier and better diagnostic approaches which, coupled with an awareness of the possible anastomotic configurations, may allow for the selection of the management protocol most likely to succeed in each individual case.