**4. Doppler imaging**

**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

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

**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.

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

"V"-shaped confluence on the right of the spine.

132 Congenital Anomalies - From the Embryo to the Neonate

in interrupted aortic arch (**Figure 24C**).

ductus arteriosus dilatation.

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

*Pulsed Doppler* sonography is an adjunct to evaluate the cardiac rhythm, but also the blood flows at the level of various arteria or venous vascular sites and valves.

B-flow and classic power Doppler display in some cases greater sensitivity in imaging cardiovascular blood flow, but they are not routinely used.

**5. 4D spatiotemporal image correlation (STIC)**

hemodynamic parameters, such as cardiac output [51].

**6. Cardiac function**

**7. Efficiency of the fetal cardiac scan**

with the anterior origin of the two outflow tracts (C).

for training and interpretations, the technique is not routinely used.

Volume datasets obtained with 4D STIC ultrasonography allow the evaluation of virtual planes not available for direct visualization with 2D technique, and facilitates the reconstruction of the spatial relationships between the cardio-vascular structures (**Figure 27**). This technology has the potential to increase the CHD detection rate by decreasing the dependency on sonographer skills and experience. However, due to the expensive costs and lack of specialists

Congenital Abnormalities of the Fetal Heart http://dx.doi.org/10.5772/intechopen.74077 135

In selected cases, it may offer important information as the comprehensive assessment of complex CHD cases [47–50] and the evaluation of cardiac function and quantification of fetal

It should be considered for suspected structural or functional cardiac anomalies [18, 19]. Some *qualitative* markers are identified during standard scanning: cardiomegaly, atrioventricular valve regurgitation, and hydrops. The *quantitative* assessment of heart function includes the study of myocardial movement such as tissue Doppler, myocardial/ventricular strain, strain

**Figure 27.** Double outlet right ventricle in 4D STIC. Axial planes show the origin of the great vessels (A) and the communication of the pulmonary artery with the left ventricle, due to a septal defect (B). Oblique longitudinal plane

Although the most frequent congenital malformations, CHDs are among the most frequently missed [18, 55]. The efficiency of the cardiac scan is reported with great variation, depending

rate imaging, fractional shortening and the myocardial performance index [52–54].

**Figure 25.** The upper image presents the normal appearance of ductus venosus in 2D color Doppler imaging. (A–C): Agenesis of ductus venosus: with hepatic (A), caval (B) and cardiac (C) drainage. UV, umbilical vein; IVC, inferior vena cava; H, heart; HV, hepatic veins; UA, umbilical artery; PV, portal vein; Ao, aorta.

**Figure 26.** Applications of color and spectral Doppler. (A): Critical aortic stenosis with dysplastic left ventricle (\*), atretic valve and aortic regurgitation (arrow, (B)). (C): Same case, tricuspid regurgitation, pulsed Doppler evaluation. (D): Atrioventricular valves regurgitation associated with cardiomegaly. (E): Same case, spectral Doppler evaluation of atrioventricular flow.
