Perinatal Cardiology Part 1

Edward Araujo Júnior, Nathalie Jeanne M. Bravo-Valenzuela, Alberto Borges Peixoto

• Publisher: Bentham Science Publishers
• Year: 2020
• ISBN:
  9789811446801
• Topic: Médecine
• Subtopic: Périnatalogie et néonatologie

In Perinatal Cardiology, fetal cardiology experts providekey information on tools for fetal evaluation through echocardiography /cardiac ultrasonography, with a primary focus on the nature and prenataldetection of structural and functional cardiac heart defects (CHDs). In this two-partbook, readers will find details about different types of fetal cardiacabnormalities along with important updates on the diagnosis, management, planning delivery, and postnatal treatment in CHD cases. This information issupplemented with guidelines for the clinical management of patients with a fetusaffected by cardiovascular defects, and surgical procedures in neonates. Key Features: -presents information gathered by experts in perinatal cardiology, organized into 26 topic-based chapters- explores the cardiac development, fetal cardiovascular hemodynamics, genetic and environmental factors associated with congenital heart defects(CHD), perinatal management, planning delivery, and postnatal treatment ofnewborns with CHD- presents information about normal cardiac functions and heart defects to give readers a clear and detailed picture of abnormal cardiac function- presents information about perinatal ultrasound physiology- gives practical guidelines for ultrasound and echography parametersrequired for evaluating fetal heart anatomy and diagnosing diseases- includes a new system of classifying prenatal CHDs based on thestratification of the risk level of care- features a straightforward and accessible style of presentationsuitable for all readers- provides references in each chapter for further reading Part 1 of this two-part set covers the basics of perinatal cardiology which chapters that introduce readersto CHD classification, fetal heart and placental physiology and pathology, diagnosisof fetal cardiac malposition and anomalies and some congenital heart defects suchas septal defects, cardiac anomalies of the left and right sides, conotruncalanomalies and aortic arch anomalies. Perinatal Cardiology is an essential reference for postgraduatemedical students seeking to improve their knowledge of fetal and pediatriccardiology as part of their residency and professional training. The bookequips readers with the information necessary to understand the role of theperinatal cardiologist and goes further to facilitate the ability to performadequate risk assessments for fetal CHD.

Early Fetal Echocardiography

Ritu Mogra^{1, 2}, Jon A. Hyett^{1, 2, *}

¹ RPA Women and Babies, Royal Prince Alfred Hospital, Sydney Institute for Women, Children and their Families, Sydney, Australia

² Discipline of Obstetrics, Gynaecology and Neonatology, Central Clinical School, Faculty of Medicine, University of Sydney, Sydney, Australia

Abstract

The role of first-trimester ultrasound has evolved from the measurement of crown-rump length (CRL), nuchal translucency (NT) and nasal bone to involve more detailed assessment of fetal anatomy. The majority of cardiac malformations are properly defined and potentially detectable by the time of the 11-13⁺⁶ week ultrasound examination. The sensitivity of ultrasound screening for cardiac abnormalities varies according to the marker being assessed (increased NT, tricuspid regurgitation, abnormal ductus venous flow), operator experience and the extent of a protocol for formal sequential structural assessment of the heart. All cardiac structures can be visualised from 13 weeks onwards. Early fetal echocardiography has been shown to be feasible and highly sensitive and specific in experienced hands. Early identification of cardiac abnormalities allows the assessment of chromosomal abnormalities/genetic syndrome at an early stage, giving parents more reproductive autonomy. Operators should be aware of the limitations of an early cardiac examination: Some lesions progress as pregnancy advances and there is still a need for a follow up ultrasound at 20 weeks’ gestation.

Keywords: Cardiac abnormalities, Early fetal echo, Prenatal screening.

---

^* Corresponding author Jon Hyett: RPA Women and Babies, Royal Prince Alfred Hospital, Missenden Road, Camperdown NSW 2050, Sydney, Australia; Tel: [phone], Fax: [phone],
E-mail: [email protected]

Introduction

Congenital heart diseases (CHD) are the most common structural malformations resulting in stillbirth, neonatal and childhood death and are a major cause of childhood morbidity [1^-5]. The purpose of prenatal screening to identify CHD is to allow parents to collect more information about underlying chromosomal and genetic conditions, to discuss likely prognosis and enable decisions about termination of pregnancy (where this is an option). For parents who chose to continue the pregnancy, prenatal diagnosis allows clinicians to optimise perinatal management by planning mode, time and place of delivery; delivering a stable

neonate in the best possible hemodynamic condition. Prenatal diagnosis has had a significant impact on morbidity and mortality associated with congenital heart defects resulting in more favourable long-term outcomes [6^-9].

This chapter reviews the detection of major cardiac defects in early pregnancy including a description of markers defining high-risk cases, the technique of early fetal echocardiography and the sensitivity, specificity, and accuracy of screening in low- and high- risk populations.

Adjunctive Prenatal Diagnosis

Early diagnosis of structural heart defects allows earlier assessment of associated chromosomal and genetic conditions [10, 11]. The test of choice is either chorionic villous sampling (CVS) (typically offered at 11-14 weeks’ gestation) or amniocentesis (from 15/16 weeks’ gestation) as these tests allow assessment of the whole genome using aCGH analysis. Non-invasive prenatal testing (NIPT) - which has recently emerged as a screening tool for aneuploidy - is not normally the best tool for diagnostic assessment. A proportion of fetuses that have a chromosomal abnormality underlying the structural cardiac abnormality will have an ‘atypical’ chromosomal abnormality that is not normally identified through NIPT [12^-14]. Cell free fetal DNA testing can be extended to include anomalies such as del22q11, which is commonly associated with certain cardiac abnormalities, but the sensitivity is not 100% and it is therefore difficult to advocate this as a replacement for a diagnostic test [15]. Although del22q11 is responsible for a very significant proportion of microdeletions that can be characterised, it is more appropriate to use a genome wide approach to testing rather than a targeted approach.

A number of genetic syndromes are also known to be associated with cardiac abnormalities. It may also be possible to test for specific genetic syndromes prenatally, but this is normally dependent on being able to identify other, extracardiac features on ultrasound and on having an understanding of the likely gene mutation associated with the condition [16^-18]. In the best hands, ultrasound will identify 50% of syndromic fetuses and most genetic syndromes involve multiple potential sites of genetic variation; so establishing a firm genetic diagnosis is a complex task. A number of lab groups now produce ‘panels’ that can be used to assess a range of genetic conditions associated with cardiac disease either through invasive testing (CVS or amniocentesis) or a non-invasive cell free DNA based approach.

Early identification of a cardiac defect establishes the risk of a chromosomal abnormality or genetic syndrome at an early stage. If this is followed by early prenatal testing, then this gives parents time to make decisions about the ongoing pregnancy. The decision to terminate pregnancy will be influenced by the nature of the chromosomal abnormality, the severity of the cardiac condition and any extracardiac malformations. More than 90% of women that have a fetus affected by chromosomal abnormality and 45% of women that have a fetus affected by a cardiac defect opt to terminate the pregnancy [19, 20]. Early prenatal diagnosis allows safer options for termination of pregnancy [21^-23]. Routine screening for both chromosomal abnormality and CHD has a significant impact on the prevalence of live born CHD [24].

Early Ultrasound Assessment of the Fetal Heart

Ultrasound screening for CHD traditionally involved the ass...