**2.2. Turner's syndrome**

therapeutic and sometimes ethical challenges. Treatment of the fetuses with CHD may expose the mother to significant risks, which may compete with the welfare of the mother [2, 3].

414 Congenital Anomalies - From the Embryo to the Neonate

Advances in the field of prenatal imaging, and increasing experience in fetal cardiology and echocardiography over the last two decades has allowed for most heart defects to be well defined as early as the second trimester [4]. Pediatric cardiologists specializing in fetal medicine, play a critical role in help making an accurate diagnosis. In addition, these specialized physicians will be critical in providing prenatal counseling to help guide parents to understand the diagnosis and in the decision-making process. This counseling will give parents information about the fetus' heart defect and its expected outcomes. Fetal echocardiography has evolved since its inception, which now can provide precise details of cardiac structural and hemodynamic aberration in fetuses with CHD. During pregnancy, the sequential use of this modality can predict the evolution of disease in utero and transition to postnatal life. Such an approach allows for detailed prenatal counseling and detection of fetuses at high risk for morbidity and mortality. This allows for appropriate planning and postnatal management [5, 6]. Most CHD is well tolerated in utero, and does not present hemodynamic risks immediately. After birth, many of these babies, with simple cardiac lesion do not require specialized delivery care. However, some high-risk fetuses may develop hemodynamic instability soon after birth and may require immediate intervention [5]. With such infants it is highly recommended that these children be born at centers where a pediatric cardiac team and intensive care personnel are available to make appropriate therapeutics decisions and intervention, without delay. Is the availability of a perinatal diagnosis of CHD is associated with improved surgical outcomes and less neonatal mortality? Some studies report a positive impact on outcomes while others showing no difference in outcomes compared to babies diagnosed with CHD after birth [7–19]. A recent meta-analysis evaluating the differences in pre-operative mortality rates between newborns with and without a prenatal diagnosis found that prenatal diagnosis of critical CHD improves neonatal pre-operative survival, and newborns with a postnatal diagnosis were more likely to die of cardiovascular compromise prior to planned cardiac surgery [20]. The etiology of CHD is multifaceted including environmental, genetic, and stochastic factors [21, 22]. Knowing the basis of the CHD will aid in the counseling of parents and help them to attain a complete understanding of the fetuses cardiac defect [23]. Although it will not change the course or management option, but it will allow for familial planning and future pregnancies.

Genetic syndromes are defined as a consistent pattern of malformation caused by a genetic alteration. A malformation syndrome consists of multiple structural defects that are thought to be due to a single cause, even if the suspected cause has not yet been identified [24].

The Noonan phenotype includes characteristic facies (ptosis, hypertelorism, low set ears, and low posterior hairline), short stature, webbed neck and cardiac anomalies. Noonan syndrome occurs in I per 1000 to 1 per 2500 live births diagnosed clinically [25–27]. Cardiac anomalies are present in 80% of individuals [28]. In 70–80% of cases, the lesion is pulmonary stenosis, usually due to

**2. Genetic syndromes**

**2.1. Noonan's syndrome**

The classical Turner's syndrome phenotype includes short stature, webbed neck, renal anomalies, congenital lymphedema, ovarian dysgenesis and cardiac anomalies. In many, the features are sufficiently subtle to be overlooked until the teenage years. The prevalence of Turner's syndrome is 1 in 2500 female births [32]. The phenotype depends on whether the X chromosome is absent (45, X in almost 50% of patient) or structurally abnormal [33].

The most common presentation is spontaneous abortion with hydrops or lymphatic malformation in the neck or mediastinum. Cardiac anomalies are present in 30% of patients with Tuner Syndrome, bicuspid aortic valve (30%), coarctation of the aorta (10%) and hypoplastic left heart syndrome (HLHS); partial anomalous pulmonary venous connection is also associated with this syndrome. Aortic root dilatation is present in 5–10% of cases, associated with aortic root dissection in later life, this finding is mostly related to decreased numbers of smooth muscle and elastic fibers in the vascular walls [32]. Gotzsche et al. demonstrated a correlation between the precise karyotype and the form of congenital heart disease; 38% of patients with X0 had aortic valve anomalies and coarctation of the aorta, compared with 11% of individuals with mosaic X0 [34].

Fetuses with Turner's syndrome have been shown to have small hearts in 90% of the cases. Significant myocardial hypoplasia is thought to be associated with the high incidence of fetal death [32]. Neonatal diagnosis may be difficult but should be considered in females presenting with left-sided heart anomalies or lymphedema.
