Characterization of phenotypic spectrum of fetal heterotaxy syndrome by combining ultrasound and magnetic resonance imaging

OBJECTIVE

Heterotaxy or isomerism of the atrial appendages is a congenital disorder with variable presentation, associated with both cardiac and non-cardiac anomalies, which may have a serious impact on fetal outcome. The aim of this exploratory study was to assess the value of fetal magnetic resonance imaging (MRI), as a complementary tool to ultrasound, for describing the morphological spectrum encountered in heterotaxy.

METHODS

This retrospective study included 27 fetuses that underwent fetal MRI following prenatal suspicion of heterotaxy on ultrasound from 1998 to 2019 in a tertiary referral center. Heterotaxy was classified as left atrial isomerism (LAI) or right atrial isomerism (RAI) based on fetal echocardiography (FE) examination. In addition to routine prenatal ultrasound, fetal MRI was offered routinely to enhance the diagnosis of non-cardiac anomalies, which might have been missed on ultrasound. Prenatal findings on ultrasound, FE and MRI were reviewed systematically and compared with those of postnatal imaging and autopsy reports.

RESULTS

Twenty-seven fetuses with heterotaxy and cardiovascular pathology, of which 19 (70%) had LAI and eight (30%) had RAI, were included. Seven (7/19 (37%)) fetuses with LAI had normal intracardiac anatomy, whereas all fetuses with RAI had a cardiac malformation. All 27 fetuses had non-cardiac anomalies on fetal MRI, including situs and splenic anomalies. In 12/19 (63%) fetuses with LAI, a specific abnormal configuration of the liver was observed on MRI. In three fetuses, fetal MRI revealed signs of total anomalous pulmonary venous connection obstruction. An abnormal bronchial tree pattern was suspected on prenatal MRI in 6/19 (32%) fetuses with LAI and 3/8 (38%) fetuses with RAI.

CONCLUSIONS

Visualization on MRI of non-cardiac anomalies in fetuses with suspected heterotaxy is feasible and can assist the complex diagnosis of this condition, despite its limitations. This modality potentially enables differentiation of less severe cases from more complex ones, which may have a poorer prognosis. Fetal MRI can assist in prenatal counseling and planning postnatal management. © 2021 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Extracardiac anomalies in prenatally diagnosed heterotaxy syndrome

OBJECTIVE

To assess the incidence and impact of extracardiac anomalies on the prognosis of fetuses with heterotaxy syndrome.

METHODS

All fetuses diagnosed with heterotaxy syndrome by three experienced examiners over a period of 14 years (1999-2013) were reviewed retrospectively.

RESULTS

In total, 165 fetuses with heterotaxy syndrome were diagnosed in the study period. One hundred and fifty (90.9%) had cardiac defects; extracardiac anomalies that did not involve the spleen were present in 26/165 (15.8%) cases. Of the total study cohort, termination of pregnancy was performed in 49 (29.7%) cases, intrauterine death occurred in 11 (6.7%), postnatal death occurred in 38 (23.0%) and 67 (40.6%) were alive at the latest follow-up, resulting in a total perinatal and pediatric mortality of 59.4%. Among the 105 liveborn neonates, 15 (14.3%) had extracardiac anomalies with significant impact on the postnatal course: one neonate died following repair of an encephalocele, six had successful treatment for various types of intestinal malrotation and/or atresia and one underwent hiatal hernia repair; the remaining seven had biliary atresia, of which five died and the two survivors are awaiting liver transplantation. The status of the spleen was assessed in 93/105 liveborn children and was found to be abnormal in 84/93 (90.3%). There were three cases of lethal sepsis, all associated with asplenia. Of the 38 postnatal deaths, 29 (76.3%) had a cardiac cause, seven (18.4%) had an extracardiac cause and in two (5.2%) the reason was uncertain.

CONCLUSIONS

Although the leading causes of death in fetuses and children with heterotaxy syndrome are cardiac, a small subset of fetuses have extracardiac anomalies with significant impact on outcome. These anomalies often escape prenatal detection, and therefore neonates at risk should be monitored for bowel obstruction, biliary atresia and immune dysfunction in order to allow timely intervention through a multidisciplinary approach. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

How insights from cardiovascular developmental biology have impacted the care of infants and children with congenital heart disease

To illustrate the impact developmental biology and genetics have already had on the clinical management of the million infants born worldwide each year with CHD, we have chosen three stories which have had particular relevance for pediatric cardiologists, cardiothoracic surgeons, cardiac anesthesiologists, and cardiac nurses. First, we show how Margaret Kirby's finding of the unexpected contribution of an ectodermal cell population - the cranial neural crest - to the aortic arch arteries and arterial pole of the embryonic avian heart provided a key impetus to the field of cardiovascular patterning. Recognition that a majority of patients affected by the neurocristopathy DiGeorge syndrome have a chromosome 22q11 deletion, have also spurred tremendous efforts to characterize the molecular mechanisms contributing to this pathology, assigning a major role to the transcription factor Tbx1. Second, synthesizing the work of the last two decades by many laboratories on a wide gamut of metazoans (invertebrates, tunicates, agnathans, teleosts, lungfish, amphibians, and amniotes), we review the >20 major modifications and additions to the ancient circulatory arrangement composed solely of a unicameral (one-chambered), contractile myocardial tube and a short proximal aorta. Two changes will be discussed in detail - the interposition of a second cardiac chamber in the circulation and the septation of the cardiac ventricle. By comparing the developmental genetic data of several model organisms, we can better understand the origin of the various components of the multicameral (multi-chambered) heart seen in humans. Third, Martina Brueckner's discovery that a faulty axonemal dynein was responsible for the phenotype of the iv/iv mouse (the first mammalian model of human heterotaxy) focused attention on the biology of cilia. We discuss how even the care of the complex cardiac and non-cardiac anomalies seen in heterotaxy syndrome, which have long seemed impervious to advancements in surgical and medical intensive care, may yet yield to strategies grounded in a better understanding of the cilium. The fact that all cardiac defects seen in patients with full-blown heterotaxy can also be seen in patients without obvious laterality defects hints at important roles for ciliary function not only in left-right axis specification but also in cardiovascular morphogenesis. These three developmental biology stories illustrate how the remaining unexplained mortality and morbidity of congenital heart disease can be solved.