Baby Heart Anatomy Baby Heart Anatomy Vs Adult

SA-CME LEARNING OBJECTIVES

After completing this journal-based SA-CME activeness, participants will be able to:

■ Discuss the importance of prenatal diagnosis of congenital heart disease.
■ Perform a systematic approach to evaluation of the 4-sleeping accommodation view of the fetal heart.
■ Describe the beefcake of the outflow tract views in comparison with CT and MR imaging.

Introduction

Cardiac defects are the most mutual congenital abnormality; they occur in five to nine per 1000 births. L per centum of childhood deaths attributed to congenital malformations are due to congenital heart disease (CHD), and of liveborn infants with CHD 18% die within their first year (1).

Obstetric ultrasonography (Usa) is now considered a routine part of prenatal care; the optimal timing for a single scan is at 18–twenty weeks gestation (2). The goal of the midtrimester scan is to confirm gestational age, evaluate beefcake, and clarify the relationship of the placenta to the neck. Detection of anomalies varies with expertise and, in general, detection of CHD has not been proficient, with prenatal detection rates of only 30%–50% reported in developed countries (iii,4). Medical guild guidelines for performance of obstetric The states at present mandate evaluation of the four-chamber view of the heart and the cardiac outflow tracts in all second- and tertiary-trimester obstetric scans. This is because the detection of CHD has improved from 55%–65% with only a four-chamber evaluation to 80%–84% if outflow tract assessment is included (5,6).

Prenatal detection of CHD should outcome in a pregnancy direction plan. The options for pregnancy direction include continuation of the pregnancy with intent to treat the infant, continuation of pregnancy with planned comfort care and no intervention at birth, or termination. In each case, it is crucial to program the delivery location and method, including when and whether to induce labor, deliver past cesarean section, or use prostaglandin infusion at nascency. In some cases, infants will need emergency intervention and thus every attempt is made to take a controlled delivery in a unit with the necessary facilities to treat critically ill newborns and access to pediatric interventional cardiology and cardiothoracic surgery services (7).

Prenatal diagnosis improves the outcome for fetuses with complex CHD. Tworetzky et al (8) reviewed a cohort of 88 patients with hypoplastic left heart syndrome; 33 patients were prenatally diagnosed, 55 were diagnosed postnatally. The prenatal diagnosis group had less acidosis, tricuspid regurgitation, and ventricular dysfunction and less need for preoperative inotrope. Furthermore, the postoperative bloodshed in the prenatal diagnosis group was 0% compared with 34% for the postnatal diagnosis group (eight). Prenatal detection non merely improves outcome, information technology decreases the cost of care. Jegatheeswaran et al (9) showed that infants with prenatal diagnosis of CHD were sixteen.five times less likely to require emergency transport after nascency. Prenatal transfer costs were $390 per fetus versus $5140 per infant transfer (9). Planned maternal transport to facilities with appropriate resources to manage children with circuitous CHD allows for a controlled commitment. The infant is immediately placed in the care of experts and is thus in the best physiologic condition for intervention (8,x).

What Are the Obstacles to Prenatal Detection?

Prenatal diagnosis of CHD is possible; it has been shown to better outcomes for pregnancies that continue and it decreases costs, but the prenatal detection rate is still not as good as it could be. What are the obstacles that foreclose constructive community-based cardiac screenings? There are socioeconomic factors (eg, equipment types, personnel training and experience, and cost of follow-upwardly studies), technical challenges, (eg, maternal habitus, belatedly gestational age, multiple pregnancy), and a widely held perception that the assessment of the fetal center is hard. Pinto et al (1) identified multiple points in the screening process that were amenable to improvement. They identified improvement of the initial screening test performed in depression-chance populations as the one probable to have the largest population result (1). As in whatsoever sonographic study, the technical parameters should be optimized. Views of the heart should be magnified so that the cardiac structures occupy most of the field of view. The use of several angles of insonation is important to avoid shadowing from side by side structures, and the use of the dedicated fetal repeat setting on the machine is helpful to amend dissimilarity and resolution of small apace moving structures. Color Doppler flow imaging is helpful to confirm flow across a ventricular septal defect (VSD) and across the valves. Besides, the apply of two-dimensional cine clips has been shown to improve the ability to clear cardiac structures every bit normal when compared with assessment with static images alone (xi–13).

If the goal of community-based screenings is to discover cases that may be abnormal and refer them to specialized centers for complete assessment, apply of a checklist to confirm normal beefcake makes sense. A systematic arroyo will allow determination of normal versus abnormal; those idea to exist abnormal can be referred for more detailed evaluation. Table 1 shows an example of such a checklist for the four-sleeping room view.

**Table i: Checklist for 4-Sleeping accommodation View**

Basic versus Complex Scan

In the United States, the images obtained in the bones fetal cardiac examination billed under the Current Procedural Terminology (CPT) code 76805 should include the four-sleeping accommodation view, the left ventricular outflow tract (LVOT) view, and the correct ventricular outflow tract (RVOT) view. These are also the recommended views in the American Institute of Ultrasound in Medicine and International Society of Ultrasound in Obstetrics and Gynecology guidelines (five,6).

Additional cardiothoracic views should be obtained when performing a complex obstetric The states examination (CPT code 78611). These views include the aortic curvation view, bicaval view, iii-vessel view (3VV), iii-vessel trachea view (3VT), and illustration of diaphragmatic integrity (xiv). These volition be illustrated in detail later in the article.

Normal Anatomy: Bones Fetal Cardiac Scan

The standard four-chamber view of the fetal heart is an axial image through the chest, similar to a chest computed tomography (CT) scan or axial images in cardiac magnetic resonance (MR) imaging studies. The principal deviation is that the fetal lungs are non aerated; thus, the heart is in a true axial aeroplane in the fetus but in a more oblique orientation postnatally. The outflow tract views are obtained in nonaxial scan planes, but again the anatomy is the same as that seen countless times a day on chest imaging studies seen past community radiologists.

Detection of all cardiac anatomy is easier on cine clips than on static images. In particular, bedchamber wall wrinkle (ie, ventricular squeeze), pulmonary vein drainage, and atrioventricular (

) valve cess require cine clips.

Situs

To determine situs, check the orientation of the fetal head and spine.

If the fetus is in cephalic presentation with its spine to the maternal left, then the fetal right side is "up" (ie, closest to the maternal abdominal wall) so the cardiac apex should point "downward" and the breadbasket should be "downwards" or left also. In our practise, nosotros obtain a video clip of the four-chamber view extended into the upper abdomen, which shows the tummy and cardiac noon on the same side. A split-screen static epitome can be used for documentation as well (Fig one).

Figure 1. Centric United states of america images of situs solitus in a third-trimester fetus. The images show the fetal abdomen (left) and chest (right) and were obtained using the split-screen feature on the Usa machine. The fetus is in cephalic presentation with the spine to the maternal correct. Thus, the fetal left side is closest to the transducer, which is placed on the maternal intestinal wall. These images assistance confirm situs solitus with the centre and the cardiac apex (arrow) both on the fetal left side.

Situs solitus is used to describe the normal organisation with the cardiac apex and tum on the left. Situs inversus implies correct-left inversion with the cardiac apex and breadbasket on the right and the liver on the left. The term situs cryptic is used to describe annihilation other than normal or complete situs inversus. Situs ambiguous is associated with heterotaxy syndromes that are in turn associated with complex CHD (15).

Eye Position

The normal eye is situated in the midline, noon directed left. A line that bisects the chest from spine to sternum should pass through the left atrium and right ventricle. Subtle cardiac displacement may be credible just when checking this line (Fig 2).

Figure 2. — Effigy 2. Centric US image of the middle of a fetus at 19 weeks gestation. A line drawn to bisect the chest from spine to sternum through the fetal eye at the level of the four-sleeping room view should laissez passer through the left atrium *(LA)* and right ventricle *(RV)*. Large chest masses cause cardiac deportation. Subtle changes in position and centrality may be the first indication of CHD. LV = left ventricle, RA = correct atrium.

Cardiac Centrality

The axis is measured betwixt the line that bisects the breast and a line forth the axis of the ventricular septum. In the second and tertiary trimesters, the axis normally ranges from 30° to 45° (Fig iii). In the first trimester, the range is higher from 34.5° to 56.8° (mean ± standard deviation = 47.6° ± 5.6) (sixteen). An aberrant cardiac axis in the first trimester at the fourth dimension of nuchal translucency measurement is an constructive tool for detection of CHD. In a study by Sinkovskaya et al (17), it performed significantly amend than other sonographic signs, including enlarged nuchal translucency, tricuspid regurgitation, or reversed A-wave in the ductus venosus (reversed flow during atrial wrinkle) used alone or in combination for detection of CHD (17).

Figure 3. — Figure three. Axial The states paradigm of the cardiac axis in a fetus at nineteen weeks gestation. Prototype through the fetal eye at the level of the iv-chamber view shows a white line bisecting the fetal chest from spine to sternum. A ruby line is drawn along the aeroplane of the interventricular septum. The cardiac axis is the angle between the red line and the white line. An abnormal cardiac axis is associated with conotruncal heart illness. True axial orientation is confirmed by the C shape of the rib. If multiple ribs are visible, the scan aeroplane is oblique; nonaxial images may simulate affliction states.

Size

The heart should occupy approximately i-third of the chest. Center area to chest area ratio should be ∼33%, and centre circumference to breast circumference ratio should exist ∼fifty%. These measurements can be hands obtained with the aforementioned calipers equally those used in measurements of the abdominal circumferences. The thoracic circumference measurement includes the peel (18).

Squeeze

The term squeeze refers to the ventricular contraction. This can be assessed simply on cine clips. Right ventricle and left ventricle wall thickness and sleeping accommodation contractility should be comparable. Left ventricular outflow obstacle (eg, critical aortic stenosis) may cause left ventricular dilatation and poor contractility, whereas right ventricular outflow obstruction (eg, pulmonary atresia) may cause right ventricular hypertrophy (nineteen). The septal hypertrophy in diabetes mellitus (DM) cardiomyopathy may be severe enough to reduce the ventricles to slit-similar chambers. (xx). Nomograms are available for heart size, ventricular diameter, and wall thickness (21).

Sleeping room Identification and Symmetry

The left ventricle has a shine interior contour and no septal valve zipper. The correct ventricle has a trabeculated interior. The moderator ring (also known as the septomarginal trabecula) is an important landmark for identification of the right ventricle every bit information technology traverses the cavity nearly the ventricular noon to connect the interventricular septum to the anterior papillary muscle (Fig iv). The septal leaflet of the tricuspid valve attaches to the ventricular septum (Fig iv). With normal embryologic looping, the right ventricle is the anterior ventricle (ie, closest to the chest wall).

Figure 4. U.s. image of ventricles in a fetus at 28 weeks gestation. The right ventricle *(RV)* is identified by the presence of the moderator band (pointer). It should be the anterior ventricle. The left ventricle *(LV)* is smooth-walled.

At the time of the midtrimester browse, the ventricles should be symmetric in size; just in the normal fetal eye, physiologic enlargement of the right atrium (the only cardiac sleeping accommodation that receives the entire cardiac output) and a simultaneous increment in the correct ventricle can be observed later in pregnancy. The width of the right ventricle can exist 1.3 times that of the left ventricle by term (22–24).

The width of the ventricles is measured at the level of the AV valves (Fig 5). The AV valves vest to the ventricle, then the tricuspid valve opens into the correct ventricle, the mitral into the left ventricle. Both ventricles should be apex-forming.

Figure 5. — Effigy 5. US epitome of the sleeping accommodation symmetry of a fetus at 20 weeks gestation. The ventricles should be approximately equal in size and both should be noon-forming. Ventricular diameters tin can exist measured as shown; * shows level of the tricuspid valve and measures the right ventricle *(RV)*; + shows the level of the mitral valve and measures the left ventricle *(LV)*. The atria were symmetric in real fourth dimension. This nonetheless prototype was obtained to measure the ventricular chambers.

The correct atrium receives the systemic veins, superior vena cava (SVC), and inferior vena cava (IVC). The SVC and IVC are not visible on the four-chamber view, only the left atrium is identified by its drainage of the pulmonary veins, which are visible on the 4-bedroom view (Fig 6). The atria should be like in size. With normal fetal circulation, the foramen ovale flap moves from the right atrium into the left atrium as the oxygenated blood from the ductus venosus (which enters the right atrium via the IVC) streams across the foramen ovale to reach the left eye (Fig 7).

Figure 6a. Identification of the atria in a fetus at 21 weeks gestation. LV = left ventricle, RV = right ventricle. **(a)** Axial four-bedroom U.s.a. image shows the left atrium, which is the most posterior sleeping room of the heart. It is identified by the pulmonary veins (white arrows), which drain into information technology; these are visible on the iv-bedroom view. The descending aorta (black arrow) descends to the left of midline. The right atrium *(RA)* drains the SVC and IVC, which are seen on the bicaval view, not the four-chamber view. **(b)** Axial cardiac MR image shows the aforementioned beefcake with the pulmonary veins (arrows) entering the left atrium *(LA)* and the descending aorta *(DA)* touching the LA wall.

Figure 6b. — Effigy 6b. Identification of the atria in a fetus at 21 weeks gestation. LV = left ventricle, RV = right ventricle. **(a)** Axial four-chamber US prototype shows the left atrium, which is the near posterior chamber of the center. It is identified by the pulmonary veins (white arrows), which drain into information technology; these are visible on the four-sleeping accommodation view. The descending aorta (black arrow) descends to the left of midline. The right atrium *(RA)* drains the SVC and IVC, which are seen on the bicaval view, not the four-chamber view. **(b)** Axial cardiac MR paradigm shows the same anatomy with the pulmonary veins (arrows) entering the left atrium *(LA)* and the descending aorta *(DA)* touching the LA wall.

Figure 7. — Effigy 7. Axial US epitome of the foramen ovale in a fetus at nineteen weeks gestation. Iv-chamber view shows the foramen ovale as a well-demarcated defect in the atrial septum (arrowhead). In existent fourth dimension, the foramen ovale flap (pointer) can be seen to move with atrial contraction. The flap may be quite redundant and bulge into the lumen of the left atrium; this is described equally a foramen ovale aneurysm. It is of no particular significance. RA = right atrium, RV = right ventricle.

Septum Appearance

The ventricular septum is about twice the length of the atrial septum (Fig viii). The ventricular septum thins from muscular to bleary; this normal change in thickness tin be misinterpreted as a VSD if the beam traverses from the noon toward the crux of the heart (Fig 9). Use boosted scan planes or color Doppler flow imaging to exclude a VSD at this level, and check the angle of the aorta to the left ventricle and the continuity of the septum and inductive aortic wall on the LVOT view.

Figure 8. — Effigy 8. Axial US epitome (four-sleeping accommodation view) shows relative sizes of the atrial and ventricular septa in a fetus at 19 weeks gestation. The ventricular septum (white line) is approximately twice the length of the atrial septum (cherry line). If these lines announced more equal in length, check carefully for a common atrioventricular valve in atrioventricular septal defect.

Figure 9. — Figure ix. US paradigm of the ventricular septum. Composite images in the same instance viewed from different angles of insonation. In the left image, the septum (pointer) is viewed with the axle parallel to its long centrality; the normal transition from muscular to bleary septum results in signal dropout (arrowheads), which tin exist mistaken for a VSD. In the right image, the angle of insonation is changed so that the beam is perpendicular to the septum (pointer) and shows that it is intact. Color Doppler imaging may as well be used to look for menstruum across any possible VSD.

The atrial septum is thin; the foramen ovale is the normal opening in it that allows passage of oxygenated blood from the right heart to the left. A fetal atrial septal defect (ASD) will exist of the primum blazon, located at the crux of the heart, and unlike the foramen ovale, a septum primum ASD is not covered past a flap. ASD is an extremely difficult diagnosis to make in the fetus.

AV Valve Outset

The AV valves belong to the relevant ventricle. The tricuspid valve is part of the correct ventricle; it is more than apically placed, located a millimeter closer to the apex of the center than the mitral valve, and has a septal leaflet fastened to the interventricular septum (25). The mitral valve is part of the left ventricle and does not have a septal leaflet. Together with the atrial and ventricular septa, the AV valves grade the crux of the centre (Fig 10).

Figure 10. Centric United states image of AV valve offset in a fetus at 19 weeks gestation. Four-sleeping room view shows the normal human relationship of the AV valves. The mitral valve belongs to the left ventricle *(LV)*; the tricuspid valve between the correct atrium *(RA)* and right ventricle is more apically placed. The septum and AV valves together create the crux of the heart.

Expanse Behind the Heart

The descending aorta should be left of midline, touching the left atrium wall. It should be the simply discretely identifiable tubular construction behind the center at the 18–xx-week scan (Fig 11). If there is increased infinite behind the left atrium or another tubular structure there, think about the esophagus, just as it is seen in the azygoesophageal recess on a breast CT image. Fetal swallowing changes the shape and size of the esophagus; therefore, a period of existent-time evaluation should allow confident recognition of the esophagus. Persistent vascular structures posterior to the eye may be seen with anomalous pulmonary venous return or with azygos continuation of the IVC (26). Azygos continuation of the IVC is associated with situs ambiguous and/or heterotaxy syndromes and severe CHD; this manifests as ii vessels of similar size behind the heart (Fig 12). With mod equipment, it is possible to run across the normal azygos vein beside the aorta in the third trimester, but information technology is smaller than the aorta, and the intrahepatic IVC will be present (27) (Fig 13).

Figure 11. — Figure eleven. Axial four-chamber U.s.a. view of the surface area backside the eye in a fetus at nineteen weeks gestation. This view shows a single vessel seen in circular cross section (arrow), left of midline, behind the heart, and closely applied to the left atrial *(LA)* wall. This is the descending aorta. RV = correct ventricle.

Figure 12. Centric US image shows azygos continuation of the IVC in a fetus at 27 weeks gestation. Four-bedroom view in a fetus with situs ambiguous shows the cardiac apex directed to the fetal correct and a right-ascendant, unbalanced atrioventricular septal defect. * = the septum between the larger right ventricle *(RV)* and smaller left ventricle *(LV)*. There are two similar-sized vessels behind the eye: the aorta (arrow) and the enlarged azygos vein (arrowhead), which is the continuation of an interrupted IVC.

Figure 13. — Effigy 13. Normal azygos vein in a fetus at 35 weeks gestation. Axial US four-sleeping accommodation view obtained during a growth follow-up browse shows the normal aorta (arrow). The smaller vessel beside information technology is the normal azygos vein (arrowhead) In this instance, the hepatic veins and IVC were normal, and formal fetal echocardiography helped to confirm normal cardiac anatomy. With modern high-resolution equipment and slender maternal habitus, information technology is not uncommon to see a normal azygos vein in the late third trimester. This example does not demand to be referred to fetal echocardiography. LV = left ventricle, RV = right ventricle.

Rate and Rhythm

Cardiac charge per unit and rhythm tin can be documented using M-mode or pulsed Doppler imaging. For Thou-fashion imaging, the beam is directed through ane atrium and one ventricle to evaluate atrioventricular conduction (Fig 14). To use pulsed Doppler imaging, the sample book is placed about the LVOT, adjacent to where the mitral and aortic valves are in fibrous continuity. Atrial wrinkle results in period toward the ventricle, while ventricular contraction leads to flow away from the ventricle into the aorta. Thus, the Doppler tracing will bear witness the atrial rate to 1 side of baseline and the ventricular charge per unit on the other (Fig 15).

Figure 14. — Figure fourteen. G-style image of heart rate and rhythm. The M-mode cursor is placed so that information technology goes through an atrium and a ventricle. The first movement encountered is the atrial wrinkle *(A)*; a premature atrial contraction *(PAC)* is seen. The ventricle *(V)* normally contracts 1:one in fourth dimension with atrial wrinkle. When there is a blocked PAC, there is a delayed ventricular wrinkle as seen here. This results in an irregular fetal heart charge per unit at auscultation. Cursor placement through both atria or through both ventricles provides data on the atrial or ventricular rate but not atrioventricular conduction. RA = right atrium, RV = correct ventricle.

Figure 15. — Figure xv. Pulsed Doppler epitome of heart charge per unit and rhythm. The Doppler sample book is placed between the left atrium (arrowhead) and left ventricle (arrow). In this example, ventricular contraction *(Five)* results in menstruum out of the ventricle toward the transducer, thus, above the baseline. With atrial contraction *(A)*, the blood moves from the atrium to the ventricle and away from the transducer, shown as beneath the baseline. This allows cess of atrial and ventricular rates and atrioventricular conduction.

Outflow Tract Views

The

LVOT

is formed by the aortic root and torso; it arises in the center of the heart, runs cephalad, forms a tight turn, and descends in the posterior mediastinum. The head and neck vessels arise from the apex of the curve.

Cheque that at that place is an bending between the ventricular septum and the ascending aorta; if absent-minded, look for a

VSD

(Fig sixteen). Brand sure that the vessel exiting the left ventricle does not branch equally it exits the pericardium; that is the branch pattern of the pulmonary artery (

). In transposition of the cracking arteries, there is ventriculoarterial discordance with the aorta arising from the right ventricle and the

arising from the left ventricle.

Figure 16a. Images of LVOT in a fetus at twenty weeks gestation **(a, b)** and an adult cardiac patient **(c)**. **(a)** Long-axis U.s. view shows the vessel exiting the smooth-walled ventricular bedchamber. The left atrium *(LA)* and left ventricle *(LV)* are separated by the mitral valve, and the aorta (pointer) does non branch. Both the anterior and posterior walls of the aorta grade distinct echogenic lines; any signal dropout is suspicious for a VSD. In existent time, this view shows the gristly continuity of the mitral and aortic valves. **(b)** In the same orientation, the ventricular wall (white line) creates an angle with the long centrality of the aorta (ruby-red line). This angle is lost with the gooseneck aortic deformity seen when the aorta is "sprung" anteriorly in the setting of an atrioventricular septal defect. **(c)** LVOT view from adult cardiac MR imaging shows the same anatomy in a format that may be more familiar to radiologists. The mitral and aortic valve leaflets are visible. A = aorta, LA = left atrium, LV = left ventricle.

Figure 16b. Images of LVOT in a fetus at 20 weeks gestation **(a, b)** and an adult cardiac patient **(c)**. **(a)** Long-axis US view shows the vessel exiting the smooth-walled ventricular sleeping room. The left atrium *(LA)* and left ventricle *(LV)* are separated by the mitral valve, and the aorta (arrow) does non branch. Both the inductive and posterior walls of the aorta form distinct echogenic lines; any signal dropout is suspicious for a VSD. In existent fourth dimension, this view shows the fibrous continuity of the mitral and aortic valves. **(b)** In the aforementioned orientation, the ventricular wall (white line) creates an bending with the long axis of the aorta (red line). This angle is lost with the gooseneck aortic deformity seen when the aorta is "sprung" anteriorly in the setting of an atrioventricular septal defect. **(c)** LVOT view from developed cardiac MR imaging shows the same anatomy in a format that may be more familiar to radiologists. The mitral and aortic valve leaflets are visible. A = aorta, LA = left atrium, LV = left ventricle.

Figure 16c. Images of LVOT in a fetus at 20 weeks gestation **(a, b)** and an adult cardiac patient **(c)**. **(a)** Long-centrality U.s. view shows the vessel exiting the smooth-walled ventricular chamber. The left atrium *(LA)* and left ventricle *(LV)* are separated by the mitral valve, and the aorta (arrow) does not branch. Both the anterior and posterior walls of the aorta class distinct echogenic lines; any signal dropout is suspicious for a VSD. In real time, this view shows the fibrous continuity of the mitral and aortic valves. **(b)** In the same orientation, the ventricular wall (white line) creates an bending with the long axis of the aorta (red line). This angle is lost with the gooseneck aortic deformity seen when the aorta is "sprung" anteriorly in the setting of an atrioventricular septal defect. **(c)** LVOT view from adult cardiac MR imaging shows the same beefcake in a format that may be more familiar to radiologists. The mitral and aortic valve leaflets are visible. A = aorta, LA = left atrium, LV = left ventricle.

The

RVOT

is formed past the pulmonary conus and main

. These wrap around the root of the aorta. Equally before long equally the

RVOT

exits the pericardium, it branches; the ductus arteriosus then runs posteriorly toward the spine, and the right

continues to wrap around the aorta.

The left

is present but not visible in this airplane (Fig 17).

Figure 17a. RVOT images. **(a)** Long-axis view shows the other great vessel exiting the centre. Note that the aorta *(A)* is now seen in circular cross section because information technology runs 90° to the main PA. The pulmonary valve (arrowhead) is at the origin of the chief PA from the pulmonary conus. The primary PA divides early such that in this browse plane the ductus arteriosus (curt pointer) runs toward the spine and the right pulmonary artery (long arrow) wraps around the aortic root. **(b)** Adult contrast-enhanced chest CT prototype shows the same beefcake in a format that may be more familiar to radiologists. The aortic root (black A) is "hugged" past the right pulmonary artery *(RPA)*, which arises from the primary PA (arrow). The ductus arteriosus (blue rectangle) connects it to the descending aorta (blue A) in fetal life. Sp = spine.

Figure 17b. RVOT images. **(a)** Long-axis view shows the other great vessel exiting the heart. Notation that the aorta *(A)* is now seen in round cantankerous section considering it runs 90° to the principal PA. The pulmonary valve (arrowhead) is at the origin of the master PA from the pulmonary conus. The main PA divides early on such that in this scan plane the ductus arteriosus (short pointer) runs toward the spine and the right pulmonary artery (long arrow) wraps effectually the aortic root. **(b)** Adult dissimilarity-enhanced chest CT epitome shows the same anatomy in a format that may be more familiar to radiologists. The aortic root (blackness A) is "hugged" past the right pulmonary avenue *(RPA)*, which arises from the main PA (arrow). The ductus arteriosus (blue rectangle) connects it to the descending aorta (blueish A) in fetal life. Sp = spine.

The crisscross sign is used to describe the real-time visualization of the outflow tracts crossing each other as they exit the heart; they are never parallel at the level of the aortic and pulmonary valves. The normal crisscross sign is to be differentiated from the extremely rare pathologic entity of crisscross heart, in which the atria connect with the contralateral ventricles and the ventricular chambers are bundled in a superoinferior fashion. On a cine clip at this level, the aortic and pulmonary valve leaflets should "come and go" throughout the cardiac cycles if they are normal in thickness and mobility. The outflows are perpendicular to each other; if ane is seen in round cross section, the other should exist seen in the long centrality as a tube (Fig 18). Retrieve that the SVC and ascending aorta are shut to each other, only the plane of the LVOT view does not include the SVC. If 2 parallel arteries are seen exiting the heart, the most probable diagnoses are transposition of the nifty arteries or double-outlet correct ventricle. Table 2 shows checklist items for the outflow tract views.

Figure 18a. Outflow tract orientation. **(a)** Coronal enhanced CT epitome shows the aorta *(A)* in round cross section simply the PA in the long axis as the right and left PAs *(RPA*, *LPA)* enter the lungs. The pulmonary vein *(PV)* enters the left atrium *(LA)*. LV = left ventricle. **(b)** Coronal oblique fetal US through the fetal chest is not a standard cardiac view, but it shows the crisscross orientation of the great arteries. The aorta arises from the left ventricle *(LV)* and ascends parallel to the SVC as it descends to drain into the right atrium *(RA)*. The PA is seen in oval cantankerous section every bit it curves around the aortic root. **(c)** Sagittal enhanced CT epitome shows the aortic arch *(A)* in the long centrality and the PA *(P)* in round cross section because the peachy vessels are at 90° to each other.

Figure 18b. Outflow tract orientation. **(a)** Coronal enhanced CT image shows the aorta *(A)* in round cross section simply the PA in the long axis as the right and left PAs *(RPA*, *LPA)* enter the lungs. The pulmonary vein *(PV)* enters the left atrium *(LA)*. LV = left ventricle. **(b)** Coronal oblique fetal U.s.a. through the fetal breast is not a standard cardiac view, but it shows the crisscross orientation of the great arteries. The aorta arises from the left ventricle *(LV)* and ascends parallel to the SVC as information technology descends to drain into the right atrium *(RA)*. The PA is seen in oval cross section as it curves around the aortic root. **(c)** Sagittal enhanced CT paradigm shows the aortic arch *(A)* in the long centrality and the PA *(P)* in circular cantankerous department because the great vessels are at 90° to each other.

Figure 18c. Outflow tract orientation. **(a)** Coronal enhanced CT paradigm shows the aorta *(A)* in circular cross section just the PA in the long axis equally the right and left PAs *(RPA*, *LPA)* enter the lungs. The pulmonary vein *(PV)* enters the left atrium *(LA)*. LV = left ventricle. **(b)** Coronal oblique fetal US through the fetal chest is not a standard cardiac view, only it shows the crisscross orientation of the cracking arteries. The aorta arises from the left ventricle *(LV)* and ascends parallel to the SVC as it descends to drain into the correct atrium *(RA)*. The PA is seen in oval cross section equally information technology curves around the aortic root. **(c)** Sagittal enhanced CT image shows the aortic arch *(A)* in the long axis and the PA *(P)* in circular cross section because the great vessels are at 90° to each other.

**Tabular array two: Checklist for Outflow Tract Views**

Normal Beefcake: Circuitous Fetal Cardiac Scan

Additional cardiothoracic views required for functioning of the complex obstetric United states of america examination (CPT lawmaking 78611) include the aortic arch view, the bicaval view, 3VV, 3VT, and illustration of diaphragmatic integrity.

Aortic Arch View

This is an oblique sagittal view similar to a left anterior oblique angiogram or the sagittal curvation view obtained in CT arteriography (Fig nineteen). The isthmus, after the takeoff of the left subclavian artery, is the narrowest part of the curvation. Unfortunately, this is also the commonest site of coarctation, which is a difficult diagnosis to make in the fetus.

Figure 19. Left parasagittal United states of america image of the aortic arch in a fetus at thirty weeks gestation. The apical curve is small in radius; every bit a result, this view is oft called the processed-pikestaff view. The head and cervix vessels arise from the apex of the arch (1 = innominate artery, 2 = left common carotid artery, 3 = left subclavian avenue). The arrows indicate the aortic isthmus, which is the most common site for coarctation to develop. After uniting with the ductus arteriosus, the vessel continues toward the abdomen equally the descending aorta (arrowheads). This is the same beefcake as seen on Figure 18c.

Bicaval View

The bicaval view is a parasagittal view showing the SVC and IVC entering the right atrium. The SVC and IVC should be similar in size, and it is important to follow the IVC into the liver for some distance to make sure that it is not interrupted as may exist seen in azygos continuation of the IVC, which is associated with heterotaxy syndromes. The right hepatic vein is frequently visible in the liver on this view every bit well (Fig xx).

Figure 20. Bicaval view in a fetus at nineteen weeks gestation. Right parasagittal United states epitome shows the SVC and IVC inbound the right atrium *(RA)*. The hepatic veins (arrow) are visible within the fetal liver. Be careful not to confuse hepatic veins with the IVC if at that place is a question of azygos continuation of the IVC. Hepatic veins are smaller and travel in an oblique course through the liver.

Three-Vessel View

The

3VV

is another way to look at the outflow tracts. It is obtained past sweeping toward the fetal head from the axial four-chamber view. Look for the size of the three vessels seen from correct to left; normally the

SVC

is smaller than the aorta, which is smaller than the

. The ductus arteriosus should be directed posteriorly toward the spine to unite with the descending aorta

(28,29) (Fig 21).

Figure 21a. 3VV and 3VT. A = aorta, P = PA, *Southward* = SVC. **(a)** Coronal enhanced CT image shows the gauge browse planes for the 3VV (red line) and 3VT (blueish line). **(b)** Axial fetal United states of america paradigm shows a normal 3VV with the SVC, the aorta, and the PA as it continues posteriorly into the ductal curvation. **(c)** Axial oblique US prototype shows a normal 3VT with the SVC and the fluid-filled trachea (pointer). The aortic and ductal (PA to ductus arteriosus) arches come together in a V shape to the left of the trachea. Note that the PA is slightly larger than the aorta. **(d)** Color Doppler paradigm at the same level shows that the direction of flow is the same in both great vessels. With duct-dependent CHD, i of the smashing vessels fills retrogradely from the ductus. If this occurs, the direction of flow (ie, colour) in the limbs of the *Five* will differ.

Figure 21b. 3VV and 3VT. A = aorta, P = PA, S = SVC. **(a)** Coronal enhanced CT epitome shows the approximate browse planes for the 3VV (cherry-red line) and 3VT (blue line). **(b)** Axial fetal U.s.a. paradigm shows a normal 3VV with the SVC, the aorta, and the PA equally it continues posteriorly into the ductal arch. **(c)** Centric oblique US image shows a normal 3VT with the SVC and the fluid-filled trachea (arrow). The aortic and ductal (PA to ductus arteriosus) arches come together in a Five shape to the left of the trachea. Note that the PA is slightly larger than the aorta. **(d)** Colour Doppler image at the same level shows that the direction of catamenia is the same in both great vessels. With duct-dependent CHD, ane of the great vessels fills retrogradely from the ductus. If this occurs, the direction of menstruum (ie, color) in the limbs of the V will differ.

Figure 21c. 3VV and 3VT. A = aorta, P = PA, S = SVC. **(a)** Coronal enhanced CT epitome shows the gauge scan planes for the 3VV (scarlet line) and 3VT (bluish line). **(b)** Axial fetal The states image shows a normal 3VV with the SVC, the aorta, and the PA as it continues posteriorly into the ductal curvation. **(c)** Axial oblique US image shows a normal 3VT with the SVC and the fluid-filled trachea (arrow). The aortic and ductal (PA to ductus arteriosus) arches come together in a Five shape to the left of the trachea. Note that the PA is slightly larger than the aorta. **(d)** Color Doppler image at the same level shows that the direction of flow is the same in both smashing vessels. With duct-dependent CHD, one of the great vessels fills retrogradely from the ductus. If this occurs, the direction of menstruum (ie, colour) in the limbs of the *Five* will differ.

Figure 21d. 3VV and 3VT. A = aorta, P = PA, S = SVC. **(a)** Coronal enhanced CT image shows the approximate browse planes for the 3VV (red line) and 3VT (blue line). **(b)** Axial fetal The states image shows a normal 3VV with the SVC, the aorta, and the PA equally it continues posteriorly into the ductal arch. **(c)** Axial oblique US image shows a normal 3VT with the SVC and the fluid-filled trachea (arrow). The aortic and ductal (PA to ductus arteriosus) arches come together in a V shape to the left of the trachea. Note that the PA is slightly larger than the aorta. **(d)** Color Doppler image at the same level shows that the management of flow is the aforementioned in both neat vessels. With duct-dependent CHD, one of the great vessels fills retrogradely from the ductus. If this occurs, the management of flow (ie, color) in the limbs of the V volition differ.

Three-Vessel Trachea View

The

3VT

is a variation of the

3VV

that includes views of the trachea and esophagus. It is obtained by sweeping superior and toward the left from the

3VV

. It shows the confluence of the ductal and aortic arches, which come up together in a V shape with the V open up to the anterior chest wall and separated from the sternum by the thymus. The limbs of the V (the ductal and aortic arches) should be like in size and show catamenia in the same direction. The ductal limb becomes slightly larger than the aortic limb in late pregnancy.

The vertex points left of the trachea, anterior to the spine. There should be no vessels left of the

. A fourth vessel may be seen in this view in the setting of a persistent left

SVC

or in total dissonant pulmonary venous return (TAPVR) superior drainage via a vertical vein (thirty).

Diaphragmatic Integrity

Document that both sides of the diaphragm are continuous anterior to posterior on parasagittal views. This is also best demonstrated on cine clips, which can be obtained at the same time as the longitudinal views of the fetal spine.

Determination

CHD may be isolated but information technology may indicate aneuploidy or a syndrome. When present, aneuploidy and other anomalies determine the prognosis. When isolated, the prognosis is determined by the verbal nature of the abnormalities. A unproblematic VSD volition likely resolve with no intervention, and mild forms of CHD may just crave serial monitoring of the child over time. However, hypoplastic left heart syndrome requires a series of surgical procedures at best and, in some cases, tin can only be managed with cardiac transplantation. Duct-dependent CHD means that at that place is obstruction of either the right- or left-sided circulation with retrograde filling of ane slap-up vessel from the other via the ductus arteriosus. At birth, the normal transition from fetal to postnatal apportionment results in closure of the ductus venosus and ductus arteriosus. Once the ductus arteriosus closes, there is no pick for retrograde filling; the pulmonary and systemic circulations are separated with shutdown of whichever outflow is obstructed. The event is circulatory collapse in the infant.

In any fetal US examination, possible CHD needs to be taken seriously. At the customs level, the sonologist's office is to identify those cases that require additional evaluation. Utilize of the systematic approach outlined in this article should allow more confident determination of normal versus abnormal (Figs 22–25). If the heart does not await normal, refer the patient for expert evaluation. Once an abnormality is confirmed, a personalized pregnancy management plan can exist developed depending on the nature of the lesion and the desires of the family unit.

Figure 22. — Effigy 22. Awarding of the checklist to assess the 4-bedchamber view. Left prototype shows a normal four-sleeping room view. In the correct prototype, the position is rotated, the axis is increased, and neither the atria nor the ventricles are symmetric in size. This four-chamber view is abnormal. The patient needs referral for formal fetal echocardiography. In this case, the final diagnosis was a severe coarctation of the aorta. LV = left ventricle, RA = right atrium, RV = right ventricle.

Figure 23. Application of the checklist to assess the four-chamber view. Left epitome shows a normal four-chamber view. In the correct image, there is loss of ventricular and atrial symmetry; the left atrium and left ventricle are smaller than the right atrium *(RA)* and right ventricle *(RV)*. The left ventricle is not noon-forming (arrowhead = left ventricular noon, arrow = right ventricular apex). Despite the small left heart chambers, the aorta *(A)* is normal and fills via retrograde flow from the ductus arteriosus. This four-chamber view is abnormal, and the patient needs referral for formal fetal echocardiography. In this case, the final diagnosis was hypoplastic left centre syndrome.

Figure 24. Application of the checklist to assess the four-chamber view. Left image shows a normal iv-chamber view. In the right image, there is loss of ventricular symmetry; the left ventricular *(LV)* apex (arrow) wraps effectually that of the correct ventricle (arrowhead). The right ventricular wall (*) is markedly thickened in comparison with that of the LV. This four-chamber view is abnormal. The patient needs referral for formal fetal echocardiography. In this case, the final diagnosis was pulmonary atresia with an intact ventricular septum. RA = right atrium.

Figure 25. Awarding of the checklist to assess the four-sleeping room view. Left epitome shows a normal iv-chamber view. In the right image, the axis is abnormal, and the "crux" of the heart is absent. Instead of the normal offset AV valves, at that place is a single low-slung valve (arrows). Note the VSD (arrowhead) and the lack of the atrial septum and foramen ovale *(?)*. The four-bedroom view is abnormal, and the patient needs referral for formal fetal echocardiography. In this case, the final diagnosis was a balanced atrioventricular septal defect. The abnormal cardiac centrality was detected at the time of nuchal translucency screening. Cell-free fetal deoxyribonucleic acrid (Dna) testing indicated increased risk for trisomy 21. The family opted for termination because of the centre defect, which was diagnosed at 17 weeks gestation.

Presented as an education exhibit at the 2015 RSNA Annual Meeting.

For this periodical-based SA-CME activity, the authors, editor, and reviewers have disclosed no relevant relationships.

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Received: May 2 2016
Revision requested: Aug 5 2016
Revision received: Sept 1 2016
Accepted: Oct 12 2016
Published online: June 02 2017
Published in print: July 2017

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Source: https://pubs.rsna.org/doi/full/10.1148/rg.2017160126