Fetal Echocardiogram Normal and Abnormal

*Madhavi Latha Routhu and Gudikandula Krishna*

## **Abstract**

In this chapter, the normal anatomy of the heart as well as pathologic cases is consistent with cardiac malposition and isomerism, septal defects, pulmonary stenosis/atresia/absent pulmonary valve syndrome, aortic malformation, hypoplastic left heart, conotruncal anomalies/common arterial trunk, tricuspid dysplasia, Ebstein anomaly, univentricular heart, and systemic venous abnormalities among other congenital cardio vascular defects by ultrasound images. Anatomical details of most CHD in fetus were provided by two-dimensional (2D) ultrasound with higher quality imaging, which enhances the diagnostic accuracy in a variety of CHD.

**Keywords:** congenital heart disease, fetal echocardiogram, ultrasound

## **1. Introduction**

The incidence of congenital heart disease (CHD) is 8–9 per 1000 live births [1]. Including all subtle cardiac anomalies, the overall CHD incidence may be of 50 per 1000 live births (like bicuspid aortic valve, atrial septal aneurysm and Persistent left SVC) [2]. There are several risk factors for CHD which includes fetal and maternal factors. The fetal risk factors are extra cardiac abnormalities which are frequently associated with CHD even in the presence of normal karyotype [3]. About 10–20% of nonimmune hydrops is associated with CHD [4, 5]. One percent of arrhythmias are associated with CHD. Maternal factors like Diabetes mellitus, Phenylketonuria, Maternal exposure to Anticonvulsants, ethanol, nonsteroidal anti-inflammatory drugs, ACE inhibitors, indomethacin, and use of lithium increase the risk of CHD. IVF pregnancies increase CHD rates by four folds. CHD or syndromes associated with CHD in first-degree relatives increase risk of CHD. Half of the CHD cases are minor abnormalities and are easily corrected by surgery; prenatal diagnosis allows for better counseling and improved the outcome.

Guidelines for fetal echocardiogram by International society of ultrasound in obstetrics and gynecology (ISUOG), American institute of ultrasound in medicine (AIUM) and association for European pediatric cardiology (AEPC) (**Figure 1**): presence of clear guidelines for defining cardiac screening and fetal echocardiography helps to standardize the approach for the sonographic evaluation of fetal echocardiography.

Fetal echocardiogram is most optimally performed between 18 and 22 weeks gestation. The screening examination includes the upper abdomen; the fourchamber (4ch) view and outflow tracts for obtaining these planes need a sweep from four chamber view and into the upper mediastinum. Initial sweep shows five chamber (5ch) view followed by right ventricular outflow tract (RVOT),

#### **Figure 1.**

*(A) Selected views of fetal cardiac screening recommended by ISUOG. (B) Sagittal view as recommended by AIUM. (C) Standardized transverse scanning planes as recommended in the guidelines of the AIUM. (D) Low and high short axis views as recommended by AIUM.*

three vessel view (3vv) and three vessel trachea view (3VT) obese patients. Color flow Doppler may facilitate imaging of various cardiac structures and in obese patients. Guidelines involve situs determination and a sequential segmental analysis of Atria, Ventricles and great arteries and their connections. Documentation fetal heart rhythm should be performed. Fetal echo should be performed by real time imaging with acquisition of recording or digital video clips and still images. It is important to note that screening for cardiac malformations in the low risk population includes minimum views of four chambers and outflow tracts. It is not specified to screen three vessel trachea view, but it is relatively easy plane to obtain and provides significant information on outflow tracts and arches.

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*Fetal Echocardiogram Normal and Abnormal DOI: http://dx.doi.org/10.5772/intechopen.91867*

In third week of post conception, the embryo consists of three basic germ layers–the Ectoderm, Mesoderm and Endoderm. The lateral splanchnic mesoderm involves in the formation of single heart tube. The major steps in development of embryonic heart are (1) primitive heart tube, (2) looping, (3) atria, ventricles and outflow tracts septations, (4) septation of the atria, (5) septation of ventricles,

During cardiac looping, the primitive ventricles move downward to the right while the primitive atrium moves upward and to the left behind the ventricle. In the folded cardiac tube various regions are recognized and are separated by transitional zones. These regions will develop into cardiac cavities and the zones will become the septa and valves. Systemic veins begin with the formation of three paired veins the vitelline, umbilical and common cardinal veins, but the pulmonary veins develop

CHD and chromosomal deletion syndrome: (1) DiGeorge syndrome or 22q11mi-

CHD associated with single gene disorders: Noonan syndrome and RASopathies,

Familial recurrence of congenital heart defects: recurrence risk of 3% for two healthy nonconsanguineous parents with one affected child, risk of recurrence

Assessment of fetal visceral situs is essential first step in fetal echocardiogram. Evaluating cardiac position and orientation in thoracic cavity and anatomical relationship of abdominal organs is the part of the fetal echocardiogram examination. Steps for sequential segmental analysis in the fetus are identifying visceral situs, Atrial arrangement, Atrioventricular valves, ventricular arrangement, ventriculoarterial connection, Ventricular outflow tracts and systemic and pulmonary venous connections. First step is Fetal visceral situs (**Figure 2**) for this identify fetal presenting part (cephalic/breech) next step is to determine fetal lie by obtaining sagittal view of fetal spine and compare with the maternal spine after this determine the location of the fetal left side with the regard to maternal abdomen. Bronshtein et al. [6] described a method to determine situs is referred as the right-hand rule for abdominal scan and left-hand rule for transvaginal approach. Palm of the hand corresponds to the face of fetus and sonographer holds the hand according to the side of fetal face; left side of the fetus will be shown by the exam-

Types of visceral situs are situs solitus, situs inversus and situs ambiguous. Situs solitus is normal viscerocardiac arrangement where the cardiac apex, stomach and descending Aorta should be located on the fetal left side. Inferior vena cava is located on the right side. Situs inversus is the mirror image arrangement of organs and vessels to situs solitus. Incidence is about 0.01%. There is slight increased risk of CHD and 20% association with Kartagener's syndrome which is

crodeletion; (2) Williams-Beuren syndrome, 1p36 deletion syndrome.

Holt-Oram syndrome, Alagille syndrome, Tuberous sclerosis complex and

**2. Embryology of heart**

(6) septation of the outflow tracts.

**3. Genetic diseases related to cardiac anomalies**

increases to 10% with two affected siblings.

separately.

CHARGE syndrome.

**3.1 Fetal situs**

iners thumb.

autosomal recessive transmission.
