Childhood Cardiac Function After Severe Maternal Red Cell Isoimmunization

The rhesus incompatible pregnancy and its consequences for affected fetuses and neonates

Rhesus incompatibility in pregnancy may result in haemolytic disease of the fetus and newborn (HDFN). This review discusses the fetal, neonatal and long-term consequences of HDFN and its management. Untreated, the fetal and neonatal prognosis of HDFN is poor. Provision of intravascular intrauterine transfusion (IUT) in a dedicated referral centre significantly reduces perinatal loss. Early-onset, severe fetal anaemia carries a greater risk of adverse fetal and neonatal outcomes and is less amenable to treatment with IUT. Interventions to prevent and treat severe, early onset disease have been investigated, however evidence from randomised controlled trials is required. Neonatal consequences of Rhesus haemolytic disease include early and late postnatal anaemia, and hyperbilirubinaemia leading to bilirubin-induced neurological dysfunction. Neurodevelopmental impairment and adult cardiovascular disease are long-term complications that have been reported in association with severe fetal anaemia. Strategies to prevent fetal hydrops, and further research into the long-term impacts of fetal anaemia may improve health outcomes for adult survivors of HDFN.

Red cell alloimmunization: A 2020 update

Management of maternal red cell alloimmunization has been revolutionized over the last 60 years. Advances in the prevention, screening, diagnosis, and treatment of alloimmune-induced fetal anemia make this condition an exemplar for contemporary practice in fetal therapy. Since survival is now an expectation, attention has turned to optimization of long-term outcomes following an alloimmunized pregnancy. In this review, the current management of red cell alloimmunization is described. Current research and future directions are discussed with particular emphasis on later life outcomes after alloimmune fetal anemia.

Fetal anemia: Diagnosis and management

Fetal anemia has been known for many years as a dangerous complication of pregnancy. Its most common causes are maternal alloimmunization and parvovirus B19 infection, although it can be associated with many different pathological conditions including fetal aneuploidies, vascular tumors, and arteriovenous malformations of the fetus or placenta and inherited conditions such as alpha-thalassemia or genetic metabolic disorders. Doppler ultrasonographic assessment of the peak velocity of systolic blood flow in the middle cerebral artery for the diagnosis of fetal anemia and intravascular intrauterine transfusion for its treatment are the current practice standards. Live birth rates as high as 95% have been reported in recent years. The additional role of intravenous immunoglobulin therapy and the long-term consequences of the condition are the subjects of active ongoing research.

Fetal anemia

The diagnosis and management of fetal anemia has been at the forefront of advances in the fields of fetal physiology, immunology, fetal imaging, and fetal therapy among others. Alloimmunization and parvovirus infection are the leading cause of fetal anemia in the United States. The middle cerebral artery peak systolic velocity (MCA-PSV) diagnoses fetal anemia. Its discovery is considered one of the most important achievements in fetal medicine. Accumulation of experience in recent years as well as refinement of surgical techniques have led to safer invasive procedures. It is expected that long term follow-up of affected pregnancies, continues to reflect all these improvements in care. It is also expected that treatment of other less common causes of fetal anemia becomes more frequently reported and that the management principles of fetal anemia are successfully applied to other fetal pathologies.

Long-term cardiovascular outcome following fetal anaemia and intrauterine transfusion: a cohort study

OBJECTIVE

To compare long-term cardiovascular outcomes in survivors of fetal anaemia and intrauterine transfusion with those of non-anaemic siblings.

DESIGN

Retrospective cohort study.

SETTING

Auckland, New Zealand.

PARTICIPANTS

Adults who received intrauterine transfusion for anaemia due to rhesus disease (exposed) and their unexposed sibling(s).

EXPOSURE

Fetal anaemia requiring intrauterine transfusion.

MAIN OUTCOME MEASURES

Anthropometry, blood pressure, lipids, heart rate variability and cardiac MRI, including myocardial perfusion.

RESULTS

Exposed participants (n=95) were younger than unexposed (n=92, mean±SD 33.7±9.3 vs 40.1±10.9 years) and born at earlier gestation (34.3±1.7 vs 39.5±2.1 weeks). Exposed participants had smaller left ventricular volumes (end-diastolic volume/body surface area, difference between adjusted means -6.1, 95% CI -9.7 to -2.4 mL/m²), increased relative left ventricular wall thickness (difference between adjusted means 0.007, 95% CI 0.001 to 0.012 mm.m²/mL) and decreased myocardial perfusion at rest (ratio of geometric means 0.86, 95% CI 0.80 to 0.94). Exposed participants also had increased low frequency-to-high frequency ratio on assessment of heart rate variability (ratio of geometric means 1.53, 95% CI 1.04 to 2.25) and reduced high-density lipoprotein concentration (difference between adjusted means -0.12, 95% CI -0.24 to 0.00 mmol/L).

CONCLUSIONS

This study provides the first evidence in humans that cardiovascular development is altered following exposure to fetal anaemia and intrauterine transfusion, with persistence of these changes into adulthood potentially indicating increased risk of cardiovascular disease. These findings are relevant to the long-term health of intrauterine transfusion recipients, and may potentially also have implications for adults born preterm who were exposed to anaemia at a similar postconceptual age.

Fetal cardiac function: technical considerations and potential research and clinical applications

Fetal echocardiography was initially used to detect structural anomalies but has more recently also been proposed to assess fetal cardiac function. This review summarizes technical issues and limitations in fetal cardiac function evaluation, as well as its potential research and clinical applications. Functional echocardiography has been demonstrated to select high-risk populations and to be associated with outcome in several fetal conditions including intrauterine growth restriction, twin-to-twin transfusion syndrome, maternal diabetes, and congenital diaphragmatic hernia. Fetal heart evaluation is challenging due to the smallness and high heart rate of the fetus and restricted access to the fetus far from the transducer. Due to these limitations and differences in cardiac function which are related to fetal maturation, cardiovascular parameters should be validated in the fetus and used with caution. Despite these precautions, in expert hands and with appropriate ultrasound equipment, evaluation of cardiac function is feasible in most fetuses. Functional fetal echocardiography is a promising tool that may soon be incorporated into clinical practice. Research is warranted to further refine the contribution of fetal cardiac assessment to the diagnosis, monitoring, or prediction of outcomes in various fetal conditions.