**3. Fetal heart evaluation. The cardiac sweep and longitudinal views**

Optimal views of the fetal heart are obtained when the cardiac apex is orientated toward the anterior maternal wall. Heart anatomy is evaluated using a sequential segmental analysis, starting from the venous plane (atria with veins connections), following the blood flow to ventricles and great arteries [23]. The information regarding fetal heart anatomy is achieved by examining five axial and three longitudinal scanning planes [18, 19, 24], described below, with examples of cardiac abnormalities. In general practice, only the axial sectional planes are evaluated during the cardiac sweep [25] (**Figure 1**).

	- *Situs*—the heart is normally left-sided, namely levocardia, or situs solitus. Rarely, a complete situs inversus is present. In the presence of an abnormal heart situs CHD but also congenital diaphragmatic hernia should be considered (**Figure 2**), as the presence of significant ectopic abdominal content in the chest displaces the heart.

• *Heart axis*—normally, the apex points toward the left side at 45 ± 15–20° (**Figure 1(2)**). Some studies on CHDs suggested that an abnormal cardiac axis is present in more than

**Figure 1.** Normal heart visualized during fetal cardiac sweep. Visualization of the cardiac transverse planes, by sweeping the transducer from the four-chamber plane toward the fetal neck as shown in the left of the image. Schematic presentation of the cardiac planes in duplex mode (gray-scale and color Doppler) that become apparent: (1) upper abdominal view, and abdominal situs; (2) four-chamber view (4CV). The atrioventricular Doppler flow is red because of the direction toward the direction during diastole. When the atrioventricular are closed, during systole, the atrioventricular flow is absent; (3) left ventricular outflow tract (LVOT). Note the continuity of the ventricular septum (VS) with the aortic wall. When the aortic valve (AoV) is closed, during diastole, the aortic flow is absent; (4) right ventricular outflow tract (RVOT) and (5) three-vessel and trachea (3VTV) and aortic arch views. L, left; R, right; St, stomach; D, diastole; and S, systole; UV, umbilical vein; DAo, descending aorta; IVC, inferior vena cava; SVC, superior vena cava; LV, left ventricle; RV, right ventricle; LA, left atrium; RA, right atrium; mb, moderator band; mv, mitral valve; tv, tricuspid valve; vi, valve insertion; pv, pulmonary veins; sp., septum primum; fo, foramen ovale, DAo, descendent aorta; MPA, main pulmonary artery; DA, ductus arteriosus; RPA, right pulmonary artery; PV, pulmonary valve Sp, spine; T, trachea. Modified with permission [26].

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• *Area of the heart,* is abnormally increased if higher than 1/3 of the thorax area, or cardiothoracic circumference ratio is above two standard deviations [28] (**Figure 3**). It can arise

two-thirds of the cases [27] (**Figure 15C**).

CHD etiology includes many genetic, environmental and teratogenic factors [12–16], but 90% of heart malformations have no identified cause. Conversely, the risk may be reduced with

A detailed sonographic examination, used to characterize fetal cardiac anatomy has traditionally been reserved for high-risk populations [18–22]: advanced maternal age, more than 35 years old, family history of CHD or disorders that involves potential CHD, infectious, autoimmune or metabolic diseases, exposure to drugs and teratogens. FECG was also proposed in certain pregnancy findings: structural defects, non-immune hydrops, arrhythmia, suspected chromosomal abnormalities, enlarged nuchal translucency, monochorionic multiple gestation. Nowadays, professional guidelines recommend a screening heart evaluation to all pregnancies, as most of the CHD cases are not associated with known risk factors [38–45]. Guidelines and training requirements have been developed [18, 19]. An accurate visualization of heat features is commonly achieved at 18–22 gestational weeks. FECG is a relatively brief but skilled ultrasound examination, because of the complexity and prenatal physiological and structural particularities of the fetal heart. Consequently, FECG has not been widely implemented, and the prenatal diagnosis of even severe CHD varies considerably, with less than

**3. Fetal heart evaluation. The cardiac sweep and longitudinal views**

Optimal views of the fetal heart are obtained when the cardiac apex is orientated toward the anterior maternal wall. Heart anatomy is evaluated using a sequential segmental analysis, starting from the venous plane (atria with veins connections), following the blood flow to ventricles and great arteries [23]. The information regarding fetal heart anatomy is achieved by examining five axial and three longitudinal scanning planes [18, 19, 24], described below, with examples of cardiac abnormalities. In general practice, only the axial sectional planes are

**1. Upper abdominal view** facilitates the evaluation of normal abdominal situs by identifying

**2. Four-chamber view (4CV)** is visualized in the lower half of the fetal chest, where the heart, with crux cordis occupying its central portion and a complete rib are present (**Figure 1(2)**).

• *Situs*—the heart is normally left-sided, namely levocardia, or situs solitus. Rarely, a complete situs inversus is present. In the presence of an abnormal heart situs CHD but also congenital diaphragmatic hernia should be considered (**Figure 2**), as the presence

the stomach, descending aorta and inferior vena cava position (**Figure 1(1)**).

of significant ectopic abdominal content in the chest displaces the heart.

**2. Indications and settings for fetal echocardiography (FECG)**

periconceptionally folic acid intake [17].

118 Congenital Anomalies - From the Embryo to the Neonate

half prenatally detected.

evaluated during the cardiac sweep [25] (**Figure 1**).

The evaluation parameters include:

**Figure 1.** Normal heart visualized during fetal cardiac sweep. Visualization of the cardiac transverse planes, by sweeping the transducer from the four-chamber plane toward the fetal neck as shown in the left of the image. Schematic presentation of the cardiac planes in duplex mode (gray-scale and color Doppler) that become apparent: (1) upper abdominal view, and abdominal situs; (2) four-chamber view (4CV). The atrioventricular Doppler flow is red because of the direction toward the direction during diastole. When the atrioventricular are closed, during systole, the atrioventricular flow is absent; (3) left ventricular outflow tract (LVOT). Note the continuity of the ventricular septum (VS) with the aortic wall. When the aortic valve (AoV) is closed, during diastole, the aortic flow is absent; (4) right ventricular outflow tract (RVOT) and (5) three-vessel and trachea (3VTV) and aortic arch views. L, left; R, right; St, stomach; D, diastole; and S, systole; UV, umbilical vein; DAo, descending aorta; IVC, inferior vena cava; SVC, superior vena cava; LV, left ventricle; RV, right ventricle; LA, left atrium; RA, right atrium; mb, moderator band; mv, mitral valve; tv, tricuspid valve; vi, valve insertion; pv, pulmonary veins; sp., septum primum; fo, foramen ovale, DAo, descendent aorta; MPA, main pulmonary artery; DA, ductus arteriosus; RPA, right pulmonary artery; PV, pulmonary valve Sp, spine; T, trachea. Modified with permission [26].


**Figure 2.** Two-dimensional US images in the cross-sectional plane of the thorax at the level of the four-chamber view of the heart. Stomach (red star) and small bowel loops (yellow stars) are identified intrathoracic and displaces fetal heart (figured by the blue tracing line) to the right; the lungs areas are highlighted by red tracing lines. With permission, Tudorache et al. [34].

from a number of situations which include CHD, particularly tricuspid atresia or dysplasia, including Ebstein's anomaly, twin to twin transfusion syndrome, fetal dilated cardiomyopathies, hydrops fetalis, or may be due to abnormal shunting from arteriovenous malformations, as the vein of Galen malformation or placental chorioangioma (**Figure 3**).


A diminutive ventricle may be associated with significant CHD, as the hypoplastic left/ right heart syndrome (**Figure 7**). Also, an abnormally small left ventricle may be an indirect sign of aortic coarctation (**Figure 19A**). However, less significant cardiac abnormalities may associate a larger right heart, as the persistence of left superior vena cava (**Figure 8**).

ventricular septum, causing communication between the two ventricles suggests the diagnosis. The entire septum must be swept (**Figure 9**) for a more confident diagnosis, and Doppler investigation enhances the diagnosis, especially for small defects (**Figure 10**). Ventricular septal defects are the most common cardiac abnormality and accounts for

**Figure 5.** Tuberous sclerosis. Increased thickness of ventricular walls and presence of solid tumors in ventricular cavities,

**Figure 3.** Cardiomegaly. (A) Increased area of the heart, occupying half of the thorax area. (B and C):Outflow tract

Congenital Abnormalities of the Fetal Heart http://dx.doi.org/10.5772/intechopen.74077 121

**Figure 4.** Ebstein's anomaly. The arrow indicates the dysplastic tricuspid valve with septal and posterior leaflets of the tricuspid valve displaced toward the apex of the right ventricle. Color Doppler investigation shows significant valvular

• *Atrial septum primum* presence, at the crux of the heart, along the *atrioventricular valves* insertion which is more apical for tricuspid valve. Atrioventricular septal defects, known

almost one third of all cardiac defects.

appears dilated in relation to the fetal thorax.

regurgitation.

highlighted with open arrows.

• *Ventricular septum integrity* is better evaluated from a lateral incidence, with the ultrasound beam perpendicular to the septum. A dropout of echoes or an opening of the

**Figure 3.** Cardiomegaly. (A) Increased area of the heart, occupying half of the thorax area. (B and C):Outflow tract appears dilated in relation to the fetal thorax.

**Figure 4.** Ebstein's anomaly. The arrow indicates the dysplastic tricuspid valve with septal and posterior leaflets of the tricuspid valve displaced toward the apex of the right ventricle. Color Doppler investigation shows significant valvular regurgitation.

from a number of situations which include CHD, particularly tricuspid atresia or dysplasia, including Ebstein's anomaly, twin to twin transfusion syndrome, fetal dilated cardiomyopathies, hydrops fetalis, or may be due to abnormal shunting from arteriovenous malformations, as the vein of Galen malformation or placental chorioangioma (**Figure 3**).

**Figure 2.** Two-dimensional US images in the cross-sectional plane of the thorax at the level of the four-chamber view of the heart. Stomach (red star) and small bowel loops (yellow stars) are identified intrathoracic and displaces fetal heart (figured by the blue tracing line) to the right; the lungs areas are highlighted by red tracing lines. With permission,

• *The atria* present similar size. The pulmonary veins enter the posterior left atrium and both vena cava enter the anterior right atrium (**Figure 1(2)**). Various condition may alter this spatial relation, as fetal isomerism and the normal atrial dimensions, where Eb-

• *The ventricles* should be visualized with similar width and contractility. The right ventricle is anterior, with more coarse lining and trabeculation. Abnormal shape of the ventricular wall lining may be an indicator for cardiac tumors, as tuberous sclerosis (**Figure 5**) or rhabdomyoma (**Figure 6**). Normally, the left ventricle forms the apex of the heart, the right ventricular apex contains the moderator band and septal insertion of the tricuspid valve is more apical than the mitral valve (**Figure 1(2)**). In later gestation, the right ventricle becomes slightly larger, but 2D or M-mode nomograms correlated with the gestational age or fetal biometry and Z-scores for fetal heart area and axis and cardiothoracic ratio, atrioventricular valve annuli, ventricular lengths and walls thickness, but also for emerging vessels, are available [29, 30]. A diminutive ventricle may be associated with significant CHD, as the hypoplastic left/ right heart syndrome (**Figure 7**). Also, an abnormally small left ventricle may be an indirect sign of aortic coarctation (**Figure 19A**). However, less significant cardiac abnormalities may associate a larger right heart, as the persistence of left superior vena cava (**Figure 8**).

• *Ventricular septum integrity* is better evaluated from a lateral incidence, with the ultrasound beam perpendicular to the septum. A dropout of echoes or an opening of the

stein's anomaly is the most representative condition (**Figure 4**).

Tudorache et al. [34].

120 Congenital Anomalies - From the Embryo to the Neonate

**Figure 5.** Tuberous sclerosis. Increased thickness of ventricular walls and presence of solid tumors in ventricular cavities, highlighted with open arrows.

ventricular septum, causing communication between the two ventricles suggests the diagnosis. The entire septum must be swept (**Figure 9**) for a more confident diagnosis, and Doppler investigation enhances the diagnosis, especially for small defects (**Figure 10**). Ventricular septal defects are the most common cardiac abnormality and accounts for almost one third of all cardiac defects.

• *Atrial septum primum* presence, at the crux of the heart, along the *atrioventricular valves* insertion which is more apical for tricuspid valve. Atrioventricular septal defects, known

**Figure 6.** Rhabdomyoma of the right ventricle, visible in 4CV (A) and left ventricle outflow tract view (B), and confirmed postabortum (C and D), penetrating the ventricular wall (C).

as endocardial cushion defects are situated in the central core of the heart. It involves the association of septum primum and ventricular septal defect and a variable degree of abnormal atrioventricular valves (**Figure 11**).


*Irregular cardiac rhythm* represents the most common rhythm anomaly and is almost always associated with isolated premature atrial contractions (PACs). Frequently blocked PACs will result in bradyarrhythmia that can mimic bradycardia (**Figure 13**). In rare cases,

**Figure 8.** Discordance of the cardiac ventricles, with enlarged right ventricle and dilated coronary sinus (CS), in the

**Figure 7.** Hypoplastic left heart syndrome (HLHS), with discordance of the heart chambers, ventricular cardiomyopathy and hypertrophic left ventricle (A), markedly reduced filling at Doppler evaluation (B), fibroelastosis, and reduced aortic

Congenital Abnormalities of the Fetal Heart http://dx.doi.org/10.5772/intechopen.74077 123

irregular rhythm may progress to supraventricular tachycardia.

caliber and flow (C).

presence of persistent left superior vena cava.

**Figure 7.** Hypoplastic left heart syndrome (HLHS), with discordance of the heart chambers, ventricular cardiomyopathy and hypertrophic left ventricle (A), markedly reduced filling at Doppler evaluation (B), fibroelastosis, and reduced aortic caliber and flow (C).

as endocardial cushion defects are situated in the central core of the heart. It involves the association of septum primum and ventricular septal defect and a variable degree of

**Figure 6.** Rhabdomyoma of the right ventricle, visible in 4CV (A) and left ventricle outflow tract view (B), and confirmed

• *Foramen ovale* represents about one third of the atrial septum and the flap bulges in the left atrium. A restrictive foramen ovale, because of a narrow foramen ovale orifice, or premature adhesion of the foramen ovale valve to the atrial septum, has repeatedly been discussed as a cause of fetal hemodynamic compromise [31]. Foramen ovale aneurysm is defined as dilatation of the atrial septum with bulging of the septum at least half the distance to the left atrial wall (**Figure 12**), is primarily a defect of septum primum which results in: septum primum bulging, loss of the normal biphasic motion of foramen ovale and arrhythmia. Associated abnormalities include: atrial septal defect, tricuspid atresia, hypoplastic right heart, aortic stenosis, transposition of the great vessels, Ebstein

• *Pericardial effusion* should be absent, or less than 2–4 mm. Greater effusions usually occur as a component of hydrops, as one of the earliest findings, and are also associated with cardiac structural abnormality, arrhythmia and an increased incidence of chromosomal

• *Heart rate and the regularity* of the rhythm is assessed based on the cardiac cycle length measured using M-mode or pulsed Doppler interrogation. Most common arrhythmias are transient and without clinical relevance, as brief episodes, less than 1–2 minutes of a

anomaly, atrioventricular valve and pulmonary venous obstruction.

abnormal atrioventricular valves (**Figure 11**).

postabortum (C and D), penetrating the ventricular wall (C).

122 Congenital Anomalies - From the Embryo to the Neonate

anomalies (**Figure 12**) [32, 33].

bradycardic, tachycardic or irregular heart rhythm.

**Figure 8.** Discordance of the cardiac ventricles, with enlarged right ventricle and dilated coronary sinus (CS), in the presence of persistent left superior vena cava.

*Irregular cardiac rhythm* represents the most common rhythm anomaly and is almost always associated with isolated premature atrial contractions (PACs). Frequently blocked PACs will result in bradyarrhythmia that can mimic bradycardia (**Figure 13**). In rare cases, irregular rhythm may progress to supraventricular tachycardia.

**Figure 9.** Multiple VSDs, apical and membranous, unapparent in certain 4CV incidence at gray-scale and color Doppler evaluation (A), but present in nearby planes, as the cardiac sweep is conducted (B). The entire interventricular septum must be carefully swept.

*Fetal bradycardia* represents a persistently slower heart rate, of less than 100–120 beats/min. More concerning is the observation of sustained bradycardia induced by sinus bradycardia, atrial bigeminy and complete heart block. Heart block is frequently associated with maternal anti-Ro autoantibodies and CHD and the most common condition is an unbal-

Congenital Abnormalities of the Fetal Heart http://dx.doi.org/10.5772/intechopen.74077 125

**Figure 11.** Atrioventricular septal defect. A large defect (open arrow) is present in the area where normally crux cordis

anced atrioventricular septal defect associated with left isomerism.

**Figure 12.** Foramen ovale aneurysm (red arrow) in a case where pericarditis is associated.

is identified.

**Figure 10.** Multiple VSDs, apical and muscular, inapparent in gray-scale evaluation. (A): Apparently normal ventricular septum in apical and (B): lateral four-chamber view. (C–E): Muscular VSDs diagnosed using color Doppler in lateral four-chamber view—open arrows.

**Figure 11.** Atrioventricular septal defect. A large defect (open arrow) is present in the area where normally crux cordis is identified.

**Figure 9.** Multiple VSDs, apical and membranous, unapparent in certain 4CV incidence at gray-scale and color Doppler evaluation (A), but present in nearby planes, as the cardiac sweep is conducted (B). The entire interventricular septum

**Figure 10.** Multiple VSDs, apical and muscular, inapparent in gray-scale evaluation. (A): Apparently normal ventricular septum in apical and (B): lateral four-chamber view. (C–E): Muscular VSDs diagnosed using color Doppler in lateral

must be carefully swept.

124 Congenital Anomalies - From the Embryo to the Neonate

four-chamber view—open arrows.

*Fetal bradycardia* represents a persistently slower heart rate, of less than 100–120 beats/min. More concerning is the observation of sustained bradycardia induced by sinus bradycardia, atrial bigeminy and complete heart block. Heart block is frequently associated with maternal anti-Ro autoantibodies and CHD and the most common condition is an unbalanced atrioventricular septal defect associated with left isomerism.

**Figure 12.** Foramen ovale aneurysm (red arrow) in a case where pericarditis is associated.

*Fetal tachycardia* implies atrial and ventricular rates above 180 bpm. Fetal anemia, hypoxia, infections, and maternal thyrotoxicosis may induce this condition. The main causes of fetal tachycardia are supraventricular tachycardia (**Figure 14**), the most common cause, with atrioventricular re-entry due to a fast conducting accessory pathway), sinus tachycardia, and atrial flutter (with atrial rate 300–500 bpm and only every second or third atrial beat conducted across the atrioventricular node, resulting in ventricular rates of 150–250 bpm). The use of echocardiography is important to differentiate these conditions and their hemodynamic impact, because the severe conditions may lead to low cardiac output, hydrops and fetal demise.

• *Coronary sinus*, may be demonstrated by fine sweeping caudally from the 4CV (**Figure 8**).

Given all these information, the 4CV is much more than a simple count of cardiac chambers, but certain abnormalities, especially involving great vessels, cannot be detected at the 4CV level alone [35]. Recent revised and updated guidelines and recommendations from several professional bodies [18, 36, 37] plead for the routinely screening evaluation of the outflow tract views along the 4CV, based on strong medical evidence regarding the prenatal detection of CHD [38–40].

sub-aortic septal defect that is frequently associated with overriding. A good example

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• The *aortic valve* cusps should open freely, disappearing in systole and not thickened. Aortic dysplastic and stenotic valves do not fully open this will decrease the blood flow into the aorta. Aortic stenosis impairs the left ventricular development, leading to hypo-

**Figure 15.** Tetralogy of Fallot. Inapparent four-chamber view (A and B) with increased cardiac axis (C). Septal defect with septoaortic discontinuity and aortic root overriding at the level of mixing flows form ventricles (D). Diminutive

stenotic pulmonary artery is identified in right outflow tract view (E) and three-vessel and trachea view (F).

of this condition is present in tetralogy of Fallot cases (**Figure 15**).

**Figure 14.** Tachyarrhythmia and measurement of cardiac rhythm using pulsed Doppler.

plastic left heart syndrome (**Figure 16**).

	- *Septoaortic continuity*, should be visualized as a continuous line between ventricular septum and aortic wall. The discontinuity of this structure is seen in the presence of a

**Figure 13.** Fetal bradyarrhythmia, M-mode and pulsed Doppler evaluation. Premature atrial contractions (PACs, highlighted with arrows) are blocked, resulting in bradycardic irregular cardiac rhythm. Normal values for the mechanical PR interval by pulsed Doppler interrogation at the mitral-aortic region in prediction of heart block risk.

**Figure 14.** Tachyarrhythmia and measurement of cardiac rhythm using pulsed Doppler.

*Fetal tachycardia* implies atrial and ventricular rates above 180 bpm. Fetal anemia, hypoxia, infections, and maternal thyrotoxicosis may induce this condition. The main causes of fetal tachycardia are supraventricular tachycardia (**Figure 14**), the most common cause, with atrioventricular re-entry due to a fast conducting accessory pathway), sinus tachycardia, and atrial flutter (with atrial rate 300–500 bpm and only every second or third atrial beat conducted across the atrioventricular node, resulting in ventricular rates of 150–250 bpm). The use of echocardiography is important to differentiate these conditions and their hemodynamic impact, because the severe conditions may lead to low cardiac output, hydrops and fetal demise. • *Coronary sinus*, may be demonstrated by fine sweeping caudally from the 4CV (**Figure 8**). Given all these information, the 4CV is much more than a simple count of cardiac chambers, but certain abnormalities, especially involving great vessels, cannot be detected at the 4CV level alone [35]. Recent revised and updated guidelines and recommendations from several professional bodies [18, 36, 37] plead for the routinely screening evaluation of the outflow tract views along the 4CV, based on strong medical evidence regarding the

**3. Left ventricular outflow tract (LVOT)** is visualized cranially from the 4CV plane and directed toward the fetal right shoulder. In this five-chamber view, the ascending aorta appears arising from the left ventricle (**Figure 1(3)**), with no proximal *transversal branching*,

• *Septoaortic continuity*, should be visualized as a continuous line between ventricular septum and aortic wall. The discontinuity of this structure is seen in the presence of a

**Figure 13.** Fetal bradyarrhythmia, M-mode and pulsed Doppler evaluation. Premature atrial contractions (PACs, highlighted with arrows) are blocked, resulting in bradycardic irregular cardiac rhythm. Normal values for the mechanical PR interval by pulsed Doppler interrogation at the mitral-aortic region in prediction of heart block risk.

allowing for its differentiation from the main pulmonary artery.

prenatal detection of CHD [38–40].

126 Congenital Anomalies - From the Embryo to the Neonate

sub-aortic septal defect that is frequently associated with overriding. A good example of this condition is present in tetralogy of Fallot cases (**Figure 15**).

• The *aortic valve* cusps should open freely, disappearing in systole and not thickened. Aortic dysplastic and stenotic valves do not fully open this will decrease the blood flow into the aorta. Aortic stenosis impairs the left ventricular development, leading to hypoplastic left heart syndrome (**Figure 16**).

**Figure 15.** Tetralogy of Fallot. Inapparent four-chamber view (A and B) with increased cardiac axis (C). Septal defect with septoaortic discontinuity and aortic root overriding at the level of mixing flows form ventricles (D). Diminutive stenotic pulmonary artery is identified in right outflow tract view (E) and three-vessel and trachea view (F).

**Figure 16.** Aortic stenosis. Abnormal left ventricle with atretic inlet and fibroelastosis (A), stenotic aortic root (B) and aortic arch in axial (C) and longitudinal (D) views.

and **C**), with PSV higher than the aortic flow. A post-stenotic dilatation of the proximal pulmonary artery may be seen (**Figure 17D**). A variable degree of hypoplastic right ventricle with hypertrophic wall, dilatation of the right atrium, and tricuspid insufficiency may be present, while congestive heart failure and hydrops may occur in severe stenosis.

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**Figure 17.** Pulmonary stenosis. (A): Dysplastic pulmonary valves, with incomplete opening and doming; (B): reversed and turbulent flow in the RVOT; (C): post-stenotic increased velocities in pulmonary artery course; (D): post-stenotic

• *Spatial relationship* evaluation should note crossing of aorta at a right angle and characteristic early transversal branching of the pulmonary artery (**Figure 1(4)**). In the absence of these ultrasound features, transposition of the great arteries should be suspected

**5. Three-vessel and trachea view (3VTV)** is obtained sliding cranially in the upper thorax during cardiac sweep (**Figure 1(5)**). Superior vena cava (SVC) on the right side, the aortic arch and ductal arch, anterior and to the left of the aorta, are visualized. The approximately equal arterial arches form a *"V"-shaped confluence* toward the descending aorta, in the left

This view may be altered with regard to several features. Their width may be discrepant, as due to aortic coarctation, where the aortic isthmus is significantly smaller than the arterial duct (**Figure 19**). However, this diagnosis is challenging and affected by high rates of false-positive diagnoses. Thus, to improve detection, a multiple-criteria prediction model is adopted, as a combination of isthmic/duct and ventricular diameters ratios and Z-scores,

Another abnormality of 3VTV plane is represented by the impossibility to identify all the three vessels. One of the arterial arches may not be seen, as in the presence of an interrupted aortic arch (**Figure 20**), or more than three vessels may be present, as in persistent

The superior vena cava may be identified contralateral, on the left side, as in the persistent

of the spine. This plane is also used for thymus evaluation [41].

visualization of CoA shelf and isthmic flow disturbance [42, 43].

left superior vena cava (**Figure 21**).

of left superior vena cava (**Figure 8**).

(**Figure 18**).

dilatation.

	- The pulmonary *valve cusps* should have a similar aspect as described for the aortic valves. The dysplastic stenotic valves may appear thickened and with incomplete opening during systole (doming) (**Figure 17A**) and determine pulmonary stenosis.
	- The approximately equal *width* of the two outflow tracts should be noted. Pulmonary stenosis may be associated with valvular stenosis, total anomalous pulmonary venous drainage, septal defects, supravalvular aortic stenosis, Noonan syndrome and tetralogy of Fallot. On color and pulsed Doppler investigation, pulmonary stenosis cases display turbulent or retrograde flow in and increased velocities distal to the valve (**Figure 17B**

**Figure 17.** Pulmonary stenosis. (A): Dysplastic pulmonary valves, with incomplete opening and doming; (B): reversed and turbulent flow in the RVOT; (C): post-stenotic increased velocities in pulmonary artery course; (D): post-stenotic dilatation.

and **C**), with PSV higher than the aortic flow. A post-stenotic dilatation of the proximal pulmonary artery may be seen (**Figure 17D**). A variable degree of hypoplastic right ventricle with hypertrophic wall, dilatation of the right atrium, and tricuspid insufficiency may be present, while congestive heart failure and hydrops may occur in severe stenosis.


• *The width* of the aorta should be approximately equal with the pulmonary artery. Unbalanced blood flows through the outflow tracts as in Fallot Tetralogy, determine a larger aorta, because the aortic root receives blood from both ventricles due to overriding (**Figure 15D** and **E**). Valvular dysplasia and aortic arch stenosis/coarctation (**Figure 16**)

**Figure 16.** Aortic stenosis. Abnormal left ventricle with atretic inlet and fibroelastosis (A), stenotic aortic root (B) and

**4. Right ventricular outflow tract (RVOT)** and short axis view are visualized cranially from the LVOT plane (**Figure 1(4)**), where the main pulmonary artery root arises from the anterior right ventricle with a short and straight course and soon *branching* into a large vessel, the ductus arteriosus directed straight posteriorly toward the descending aorta as an extension

• The pulmonary *valve cusps* should have a similar aspect as described for the aortic valves. The dysplastic stenotic valves may appear thickened and with incomplete open-

• The approximately equal *width* of the two outflow tracts should be noted. Pulmonary stenosis may be associated with valvular stenosis, total anomalous pulmonary venous drainage, septal defects, supravalvular aortic stenosis, Noonan syndrome and tetralogy of Fallot. On color and pulsed Doppler investigation, pulmonary stenosis cases display turbulent or retrograde flow in and increased velocities distal to the valve (**Figure 17B**

ing during systole (doming) (**Figure 17A**) and determine pulmonary stenosis.

of the main artery, and the smaller pulmonary arteries directed laterally.

determine a smaller aortic caliber.

aortic arch in axial (C) and longitudinal (D) views.

128 Congenital Anomalies - From the Embryo to the Neonate

This view may be altered with regard to several features. Their width may be discrepant, as due to aortic coarctation, where the aortic isthmus is significantly smaller than the arterial duct (**Figure 19**). However, this diagnosis is challenging and affected by high rates of false-positive diagnoses. Thus, to improve detection, a multiple-criteria prediction model is adopted, as a combination of isthmic/duct and ventricular diameters ratios and Z-scores, visualization of CoA shelf and isthmic flow disturbance [42, 43].

Another abnormality of 3VTV plane is represented by the impossibility to identify all the three vessels. One of the arterial arches may not be seen, as in the presence of an interrupted aortic arch (**Figure 20**), or more than three vessels may be present, as in persistent left superior vena cava (**Figure 21**).

The superior vena cava may be identified contralateral, on the left side, as in the persistent of left superior vena cava (**Figure 8**).

**Figure 18.** Transposition of the great arteries. (A): Emergence of the vessel arising from the left ventricle, showing early branching (B) that suggest pulmonary outflow tract. (C): Emergence of the vessel arising from the right ventricle with no evident branching in the transversal plane. (D): Sagittal view of the thorax showing branching characteristic to aortic arch of the vessel arising from the anterior ventricle in gray scale and after power Doppler is applied (E). (F): Parallel course of the great vessels.

**Figure 20.** Interrupted aortic arch. (A): The ventricular discordance is not present, because of the septal defect, not evident in four-chamber views, but sub-aortic, when the entire septum is swept. (B): Enlarged pulmonary trunk (yellow arrow), and thin aorta (white arrow) in 3VT view. (C): Discontinuity of aortic arch in upper mediastinum axial planes.

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**Figure 21.** Persistent left superior vena cava (PLSCV), indicated with arrow in duplex gray-scale (A) and color Doppler

(B) evaluation.

**Figure 19.** Discrepancy between the large right ventricle, pulmonary root and arterial duct and the diminutive left ventricle, aortic arch and isthmus in aortic coarctation. Calculations for mitral and tricuspid valves (A), arterial arches (B), isthmus and ductus (C).

Absence of a normal "V"-sign confluence of the arterial arches can be used to detect aortic arch abnormalities: right aortic arch, double aortic arch (**Figure 22**) and interrupted aortic arch (**Figure 20**).

#### **6. Aortic and ductal arches views**

• *The aortic* and *ductal arches* are visualized in longitudinal planes aligned with the respective ventricular outflow tracts. Aorta origins from the middle of the heart, with a typical "hook" shape, with the neck vessels arising longitudinally (**Figure 23A**).

**Figure 20.** Interrupted aortic arch. (A): The ventricular discordance is not present, because of the septal defect, not evident in four-chamber views, but sub-aortic, when the entire septum is swept. (B): Enlarged pulmonary trunk (yellow arrow), and thin aorta (white arrow) in 3VT view. (C): Discontinuity of aortic arch in upper mediastinum axial planes.

Absence of a normal "V"-sign confluence of the arterial arches can be used to detect aortic arch abnormalities: right aortic arch, double aortic arch (**Figure 22**) and interrupted aortic

**Figure 19.** Discrepancy between the large right ventricle, pulmonary root and arterial duct and the diminutive left ventricle, aortic arch and isthmus in aortic coarctation. Calculations for mitral and tricuspid valves (A), arterial arches

**Figure 18.** Transposition of the great arteries. (A): Emergence of the vessel arising from the left ventricle, showing early branching (B) that suggest pulmonary outflow tract. (C): Emergence of the vessel arising from the right ventricle with no evident branching in the transversal plane. (D): Sagittal view of the thorax showing branching characteristic to aortic arch of the vessel arising from the anterior ventricle in gray scale and after power Doppler is applied (E). (F): Parallel

• *The aortic* and *ductal arches* are visualized in longitudinal planes aligned with the respective ventricular outflow tracts. Aorta origins from the middle of the heart, with a typical

"hook" shape, with the neck vessels arising longitudinally (**Figure 23A**).

arch (**Figure 20**).

(B), isthmus and ductus (C).

course of the great vessels.

130 Congenital Anomalies - From the Embryo to the Neonate

**6. Aortic and ductal arches views**

**Figure 21.** Persistent left superior vena cava (PLSCV), indicated with arrow in duplex gray-scale (A) and color Doppler (B) evaluation.

**Figure 22.** Right aortic arch (RAA) types. RAA and left ductus, forming a "U" shape of the arterial arches confluence as an almost complete vascular ring (A and B). Note the aorta coursing to the right of the spine, on the same side with superior vena cava (A), and a visible vascular incomplete ring behind the trachea. Double aortic arch, color Doppler evaluation (C and D) with complete vascular ring between the aortic branches. RAA with right ductus (E and F), described before with normal heart [44], duplex mode evaluation. Both arterial arches are directed to the right of the spine, resulting a "V"-shaped confluence on the right of the spine.

• *Superior and inferior vena cava views*/caval long-axis view/bicaval view is found longitudinally on the right of the spine, in line with the superior and inferior vena cava confluence with the right atrium (**Figure 23C**). The normal aspect is altered in fetal isomerism,

**Figure 24.** Pathologic aortic and ductal arches in longitudinal view. (A): Aortic coarctation with stenotic isthmus (arrow); (B): pulmonary valvular stenosis, with irregular course and stenotic ductal areas; (C and D): interrupted aortic arch, with

Congenital Abnormalities of the Fetal Heart http://dx.doi.org/10.5772/intechopen.74077 133

*Color Doppler* and *high definition directional power flow* sonography allows for a better understanding of the cardio-vascular anatomy and function [18, 45, 46], particularly in detecting regurgitation, small septal defects and first trimester anatomic and physiological features of heart, as presented below. The ductus venosus appearance, flow and connections depend on the Doppler identification and interrogation of this small vascular structure. Agenesis of ductus venosus was associated with a high incidence of cardio-vascular and genetic abnor-

*Pulsed Doppler* sonography is an adjunct to evaluate the cardiac rhythm, but also the blood

B-flow and classic power Doppler display in some cases greater sensitivity in imaging cardio-

flows at the level of various arteria or venous vascular sites and valves.

vascular blood flow, but they are not routinely used.

interrupted inferior vena cava or persistent left superior vena cava.

ascending aorta that fails to curve, but courses straight cranially (C), and heavily enlarged ductal arch (D).

**4. Doppler imaging**

malities (**Figures 25** and **26**).

**Figure 23.** Aortic (A) and ductal (B) arches in longitudinal view. Note the differences mentioned in the text, regarding the origin, curvature and branching. (C): Bicaval view. IVC, inferior vena cava; SVC, superior vena cava; RA, right atrium.

A diminutive caliber accompanied by an altered shape may be present in aortic arch coarctation (**Figure 24A**) or stenosis (**Figure 16D**). Also, the course of the arch may be misshaped and interrupted, with lack of communication with the descending aorta, as in interrupted aortic arch (**Figure 24C**).

The vessel may appear irregular and thin, as in pulmonary stenosis (**Figure 24B**), or heavily dilated, as in aortic arch stenosis or interruption (**Figure 24D**). The ductus may be absent, as is usually in the most frequent variant of absent pulmonary valve syndrome-associated with tetralogy of Fallot. Another type of the syndrome—accompanied by tricuspid atresia, is characterized by a normal or narrowed ductus arteriosus, along the dysplastic right ventricle. Contrarily, the isolated type of absent pulmonary valve syndrome, with intact ventricular septum, associates a severe right ventricular hypertrophy with pulmonary artery and ductus arteriosus dilatation.

**Figure 24.** Pathologic aortic and ductal arches in longitudinal view. (A): Aortic coarctation with stenotic isthmus (arrow); (B): pulmonary valvular stenosis, with irregular course and stenotic ductal areas; (C and D): interrupted aortic arch, with ascending aorta that fails to curve, but courses straight cranially (C), and heavily enlarged ductal arch (D).

• *Superior and inferior vena cava views*/caval long-axis view/bicaval view is found longitudinally on the right of the spine, in line with the superior and inferior vena cava confluence with the right atrium (**Figure 23C**). The normal aspect is altered in fetal isomerism, interrupted inferior vena cava or persistent left superior vena cava.
