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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3676_Библиотеки_им_академика_М_И_Перельмана
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4 Pediatric Cardiac CTA
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4.9.7 Case 4.18
Echo showed stenosis of the pulmonic valve and
the main pulmonary artery (MPA), hypertrophy
of the right ventricle (RV), a large VSD and that
Fig. 4.61 An axial oblique image shows the normal position of the aortic valve (AoV) in relation to the pulmonic
valve (PV), slightly posterior and to the right. The right
atrium (RA), left atrium (LA), and position of the mitral
valve (MV) annulus (white arrow) are seen. The AoV and
MV annuli are in direct continuity as they would be in a
normal heart. The left atrial appendage (LAA) (black
arrow) overlies and partially obscures the mitral annulus
the aortic valve was positioned to overlie the
VSD, findings of tetralogy of Fallot (TOF). As the
aortic arch was not well seen and coronary artery
origins were not identified, cardiac CTA was
requested. See Figs. 4.61, 4.62, 4.63, and 4.64.
Fig. 4.63 In a four-chamber view of the heart, more than
50% of the aortic valve and the ascending aorta (AAo)
arise from the right ventricle (RV) and overlies a membranous ventricular septal defect (VSD) (bracket). The free
wall of the RV is hypertrophied (arrows)
Fig. 4.62 The right ventricular outflow tract (RVOT)
(bracket) is diffusely narrow and the muscular wall is
thickened [RV hypertrophy]. The size of the aortic valve
(AoV) is much larger than the RVOT. The pulmonary outflow (arrow) and the AoV both arise from the right ventricle (RV)
Fig. 4.64 A 3D surface rendered reconstruction shows
the small caliber of the RVOT (dotted lines) and main pulmonary artery (MPA) and the much larger caliber ascending aorta (AAo) and their normal anatomic relationship
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4.9.8 Clinical Presentation
Following birth, a newborn with known D-TGA
experienced hypoxia, with O2 saturation at 85%.
4.9.9 Case 4.19
This newborn infant is known to have D-TGA as
the aortic valve and ascending aorta (AAo) were
noted to arise from the anterior, morphologic
right ventricle (RV) and the pulmonic valve and
main pulmonary artery (MPA) arise from the
posterior morphologic left ventricle above a large
ventricular septal defect (VSD).
A postnatal echo confirms the prenatal find-
ings and raised concern for hypoplasia of the aor-
tic arch. CTA of the heart and great vessels was
requested.
A short axis image at the base of the heart
(the atrioventricular valve plane) shows the
anterior position of the aortic valve position
(white arrow) in relation to the pulmonic valve
position (black arrow) (Fig. 4.66). The pulmonic
valve and the main pulmonary artery (MPA) are
straddle a ventricular septal defect (VSD)
(bracket), but are more committed to the RV
than the LV.
The anterior position of the aortic valve (black
arrow) and posterior position of the mitral valve
(white arrow) indicate that their annuli are not in
continuity as seen in a normal heart.
Fig. 4.65 An axial oblique image shows the anterior
position of the aortic valve (AoV) in relation to the pulmonic valve (PV)
Fig. 4.66 A short axis image at the base of the heart (the
atrioventricular valve plane) shows the anterior position
of the aortic valve position (white arrow) in relation to the
pulmonic valve position (black arrow) and the parallel
course of the ascending aorta (AAo) and the main pulmonary artery (MPA). The pulmonic valve and the MPA
straddle a ventricular septal defect (VSD) (bracket), but
are more committed to the RV than the LV
4 Pediatric Cardiac CTA
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Fig. 4.67 In an attempt to show a four-chamber view of
this heart the right atrial chamber is obscured by the
ascending aorta (AAo) and main pulmonary artery (MPA).
The left atrium (LA), left ventricle (LV), and right ventricle (RV) are seen. The pulmonary valve straddles the VSD
(black bracket) but is more committed to the RV than the
LV.
The RV free wall and outflow tract are thickened
(white bracket)
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Fig. 4.68 A 3D surface rendered image of the heart again
shows the anterior position of the ascending aorta (AAo).
Also note the great arteries are parallel, another indication
of transposition. The left atria appendage (LAA) (arrow)
overlies the base of the left ventricle to the left of the AAo
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4.10 Pulmonary Sling
The phenomena of pulmonary sling occur when
the left pulmonary artery (LPA) origin is anomalous, arising from the proximal right pulmonary
artery (RPA) rather than from the main pulmonary artery (MPA) and courses between the trachea and esophagus. Depending upon the location
of the sling, there may be airway narrowing
associated with anomalous branching of the trachea. An anterior impression on the esophagus is
also present and, in some patients, may be a cause
of dysphasia.
Two types of pulmonary sling are recognized:
Type 1—This is the less common and less
complex form of LPA sling and is associated with
tracheobronchomalacia. The position of the sling
is typically at the level of the aortic arch, approximately T4–T5. As the LPA courses posterior to
the trachea, it may cause extrinsic narrowing.
Type 2—More common and more complex
form of LPA sling and is often seen with long
segment tracheal stenosis due to the presence of
complete tracheal cartilaginous rings. The tracheal and bronchial anomalies are more extensive; the position of the LPA sling is caudal, at
the level of T6–T7 and may involve the bronchus
as well as the distal trachea. There are more often
other cardiovascular and pulmonary abnormalities including right tracheal bronchus, right lung
hypoplasia, persistent left superior vena cava,
and patent ductus arteriosus.
CTA is essential in imaging patients with LPA
sling as definition of the contrast filled blood pool
and air filled tracheobronchial tree are ideally
imaged.
4.10.1 Misplaced Left Pulmonary
Artery Origin
The anomalous origin of the LPA, resulting in the
formation of a sling is believed to occur when
development of the left sixth aortic arch fails and
the left-sided lung buds establish a connection
with branches of the right sixth aortic arch. The
vascular supply of the left lung therefore comes
from the RPA and the vessel passes between the
trachea and the esophagus.
It is possible that the connection between the
right sixth aortic arch and the left lung buds is
made anterior to the trachea. In this case, the origin of the LPA is anomalous, but a sling is not
present.
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4.10.2 Complete Tracheal Rings
The cartilaginous rings of the trachea are normally incomplete, with an interruption in the ring
along the dorsal surface of the trachea. This
results in the normal U-shaped contour of the
anterior trachea and the flattened dorsal surface.
When the tracheal cartilaginous rings are not
interrupted, but completely encircle the lumen of
the trachea, the affected segment is narrowed and
typically has a circular shape. While growth of
the trachea and of complete rings does occur the
affected segment remains small.
4.10.3 Clinical Presentation
A 3-month-old infant with life-long stridor and a
murmur underwent echocardiogram. A secundum
atrial septal defect (ASD) was found, the cause of
the murmur. The origin of the LPA was from the
RPA. CTA was requested to confirm anatomy of
LPA sling and to define tracheobronchial anatomy.
4.10.4 Case 4.20
See Fig. 4.69, 4.70, and 4.71.
Fig. 4.70 A 3D surface rendered reconstruction of the
heart and pulmonary arteries show the origin of the LPA
from the RPA. Though not seen in this reconstruction, the
trachea passes through the space anterior to the proximal
LPA to the right of the aortic arch (dotted ellipse)
Fig. 4.69 The main (MPA) and right (RPA) pulmonary
arteries are normal caliber. The left pulmonary artery
(LPA) arises from the RPA and is severely narrowed
(bracket) as it courses between the carina and the esophagus (dotted ellipse). In this patient, the spine may also
contribute to narrowing of the proximal LPA
Fig. 4.71 A 3D reconstruction of the tracheobronchial
tree and lung tissue is shown. The trachea (T) bifurcates at
the level of the aortic arch (white arrow). The right bron-
chus is normal caliber but supplies only the right upper
lobe. The left bronchus is diffusely small caliber and a
second bifurcation (red arrow) divides to bronchi for the
left upper and lower lobes and the right middle and lower
lobes. The esophagus (E) is also seen
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4.10.5 Case 4.21
Another infant presented with a murmur on a
well-baby checkup. Echocardiography showed
an unusual relationship in the pulmonary artery
origins, raising a question of LPA sling. CTA was
requested to investigate the anatomy.
Fig. 4.72 A coronal oblique MIP image of the branch
pulmonary arteries shows the anomalous origin of the
LPA from the RPA and a circuitous course of the proximal
LPA as it courses from right to left. Axial images showed
the LPA traveling anterior to the trachea; therefore, a sling
was not present
The origin of the left pulmonary artery (LPA)
arises from the superior surface of the right pulmonary artery (RPA) and courses leftward, forming
an acute angle (dotted arrow), perhaps leading to
the murmur heard on physical exam. The ascending aorta (AAo) and aortic arch have been cut
away to show the branch pulmonary arteries.
Fig. 4.73 A 3D surface rendered image of the heart
shows the origin of the left pulmonary artery (LPA) arises
from the superior surface of the right pulmonary artery
(RPA) and courses leftward, forming an acute angle, the
likely source of the murmur heard on physical exam. The
ascending aorta (AAo) and aortic arch have been cut away
to show the branch pulmonary arteries
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4.11 Atrioventricular Septal
Defect
When defects of the interatrial and interventricular septa occur together and affect formation of
the atrioventricular valves, the malformation fits
into the category of atrioventricular septal defects
(AVSD). The term “endocardial cushion defect”
is also used to describe an atrioventricular septal
defect. The malformation involves defects of the
primum segment of the interatrial septum which
abuts the atrial side of the atrioventricular (AV)
valve plane and the membranous segment of the
interventricular septum which touches the ventricular side of the AV valve plane. The muscular
interventricular septum may also be involved to
varying degrees. The annulus of each of the AV
valves, the mitral valve and tricuspid valve,
which normally lie perpendicular to the intraatrial and interventricular septum and in nearly
the same plane may be abnormal.
In the human embryo, a crescent of cardiogenic tissue forms a tube which folds (loops)
upon itself and divides into the atria, left ventricle, and bulbus cordis (right ventricle). Before
septation of the right and left ventricles a ridge of
tissue, the bulboventricular fold, distinguishes
the bulbus cordis from the left ventricle. The
interventricular septum is formed from three
independent tissue sources, muscular, inlet and
outlet components. The muscular portion of the
septum forms from an anterior segment of the
bulboventricular fold, derived from the bulbous
cordis, and grows posteriorly to fuse with the
muscular ventricular segment which is derived
solely from ventricular tissue. Just above the
basal edge of the fused anterior (outlet) and posterior (inlet) muscular interventricular septum is
a space, the interventricular foramen, which
closes as the developing endocardial cushions
(inlet) and conal truncal ridges (outlet) form the
membranous septum and fuse to muscular septal
tissue.
The endocardial cushions are contiguous
across the atrioventricular valve plane; inlet portion of the interventricular membranous segment
from the inferior endocardial cushions and the
superior endocardial cushions extend across the
ostium primum to join the primum segment of
the interatrial septum. The secundum segment
invaginates from the atrial wall, extending to
overlap with the primum segment. This overlapping portion remains open in utero as the foramen ovale and in most hearts fuses to close after
birth.
The atrioventricular valve plane and the
anterolateral mitral and septal tricuspid valve
leaflets are partially derived from tissue of the
endocardial cushions. A defect in valvular tissue
or annulus of either or both AV valves is variable
and may be symmetric (balanced) or asymmetric
(unbalanced). When balanced the common atrioventricular valve may have the appearance of a
dysmorphic valve which opens to both the right
and left ventricles. Alternatively, an unbalanced
common atrioventricular valve may drain primarily to the right ventricle (right dominant) or to the
left ventricle (left dominant).
Approximately 50% of infants born with
Down syndrome have congenital heart disease,
many of them will have and atrioventricular septal defect (45%).
4.11.1 Pearls (•) and Pitfalls (√)
• Examine cardiac CT images in short axis
(SA), horizontal (4 chamber), and vertical (2
chamber) long axes in order to accurately characterize defects of the interatrial and interventricular septae.
√ The short axis view of the atrioventricular valve plane may be helpful in characterizing
malformation of the mitral and tricuspid valves;
however, echocardiography is typically much
better for delineating valve structure.
4.11.2 Clinical Presentation
A full-term newborn with facial features of Down
syndrome, but without suspected congenital heart
disease, was born. Shortly after birth, the baby
developed respiratory distress. Physical exam
revealed a definite murmur; a chest radiograph
and echocardiogram were performed.
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4.11.3 Case Presentation
See Figs. 4.74, 4.75, 4.76, and 4.77.
D.M.E. Bardo
Fig. 4.74 The chest radiograph showed moderate cardiomegaly and increased pulmonary vascular markings
(arrows). Echocardiography revealed small size of the left
ventricle compared to the right and a primum and secundum atrial septal defects (ASD). The aortic arch was not
well visualized and the ductus arteriosus was patent.
Coarctation of the aorta was suspected. Cardiac CTA was
requested to evaluate the aortic arch and to measure relative volumes of the ventricles
Fig. 4.75 A four-chamber view of the heart shows dilation and hypertrabeculation of the right ventricle (RV) and
small volume of the left ventricle (LV). The membranous
segment of the interventricular septum, just below the
atrioventricular valve plane, shows a small defect (open
arrow). Primum (single arrow) and secundum (double
arrow) interatrial and membranous (open arrow) inter-
ventricular septal defects are noted. The atrioventricular
valve plane (dotted line) shows the valves open predominantly to the RV in this patient with an unbalanced AVSD
Fig. 4.76 The membranous interventricular septal defect
(black bracket) is much larger in the short axis plane near
the base of the heart. than was suspected in the 4 chamber
view. Asymmetry of the right (RV) and left (LV) ventricles is also apparent in this view
Fig. 4.77 At the level of the atrioventricular valve plane,
the mitral annulus (white dotted ellipse) and the tricuspid
annulus (black dotted ellipse) shows asymmetry, indicating the patient has an unbalanced atrioventricular septal
defect which has right dominant valve components and
ventricle
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4.11.4 Clinical Presentation
A newborn infant with Down syndrome had a
prenatal diagnosis of atrioventricular septal
defect. She underwent cardiac CTA because of
suspected aortic arch hypoplasia.
4.11.5 Case 4.22 Presentation
See Figs. 4.78, 4.79, 4.80, and 4.81.
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Fig. 4.80 At the level of the atrioventricular valve plane,
the mitral annulus (white dotted ellipse) and the tricuspid
annulus (black dotted ellipse) show symmetry, indicating
the patient has a balanced atrioventricular septal defect, or
co-dominant valve components and ventricles
Fig. 4.78 A four-chamber view of the heart shows that the
right (RV) and left (LV) ventricles are similar in size and that
the plane of the atrioventricular valves (dotted line) opens
symmetrically to both the right (RV) and left (LV) ventricles.
A defect in the membranous portion of the interventricular
septum (bracket) is accompanied by near complete absence
of the interatrial septum. The right (RA) and left (LA) appear
normal size, but the right atrial appendage (RAA) is dilated
Fig. 4.79 In a short axis plane, the symmetry of the right
(RV) and left (LV) ventricles is apparent as is the dilated right
atrial appendage (arrows) which overlies the RV free wall
Fig. 4.81 A 3D surface rendered image shows the right
(RV) and left (LV) ventricles are similar in size, and the
large size of the right atrial appendage (arrows), and the
left atrial appendage (open arrow). The ductus arteriosus
(PDA) is patent and large caliber
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4.12 Partial and Total Anomalous
Pulmonary Venous
Connection
Anomalous pulmonary venous connection occurs
in many different types or combinations and
results in drainage of oxygenated pulmonary
venous blood to the right side of the interatrial
septum, to systemic veins, or to a blind ending
confluence behind the left atrium, without a
direct connection to the heart. Anomalous veins
may drain to structures above the heart (supracardiac), to a cardiac chamber (intracardiac), or
below the heart (infracardiac).
The embryological development of the pulmonary veins begins as the cardinal veins, but
regresses as a common pulmonary vein projects
from the primitive left atrium toward the pulmonary parenchyma and eventually connects with
the parenchymal venous system via four pulmonary veins to the left atrium.
4.12.1 Total Anomalous Pulmonary
Venous Connections
Complete failure of the formation of the common
pulmonary vein from the left atrium therefore
results in total anomalous pulmonary venous
connection (TAPVC). The extent of failed pulmonary vein development varies from persistence of primitive connections to the right rather
than the left atrium (intracardiac), to infracardiac
connections to the inferior vena cava or to the
portal or hepatic veins, or most commonly, to
supracardiac connections, the superior vena cava
or the brachiocephalic veins. In supracardiac and
infracardiac forms of TAPVC, a pulmonary vein
confluence forms behind the left atrium. A vertically oriented vein which drains to the brachiocephalic vein and superior vena cava (SVC) in
supracardiac TAPVC courses anterior or posterior to the left pulmonary artery; when posterior
to the artery and anterior to the left bronchus pulmonary venous blood flow may be obstructed.
When a confluence of pulmonary veins behind
the left atrium drains inferiorly through the dia-
phragmatic hiatus, it is most often to the portal
vein and less commonly to the hepatic veins or
inferior vena cava (IVC). This connection too
may become obstructed (90%), typically as the
draining vein traverses the diaphragmatic hiatus.
A combination of intra, supra, or infracardiac or
mixed TAPVC may also be found.
Occasionally, an insufficient pathway for
drainage or a complete lack of pulmonary parenchymal venous drainage occurs and results in
rapid onset of postnatal pulmonary venous congestion which is incompatible with life. Cardiac
CTA is especially important in imaging these
clinically severely ill infants as the high spatial
resolution capabilities of the modality lend
toward defining the very small caliber venous
structures.
4.12.2 Partial Anomalous Pulmonary
Venous Connection
When only some of the pulmonary venous buds
develop normal connections to the common pulmonary vein and left atrium but other connections are not made normally partial anomalous
pulmonary venous connection (PAPVC) is the
result.
The most commonly detected form of PAPVC
is drainage of some or all of the right pulmonary
veins to the superior vena cava (SVC). This
anomaly typically is associated with a defect at
the superior aspect of the sinus venosus. Though
this type of defect is commonly referred to as a
sinus venosus atrial septal defect (ASD) the terminology is inaccurate as the sinus venosus is not
a component of the interatrial septum. PAPVC of
all or part of the left lung is also possible superiorly via a vertical vein, intracardiac through the
coronary sinus or to the right side of an intraatrial septum. Scimitar syndrome which includes
right-sided PAPVC to the IVC also includes
hypoplasia of the right lung and pulmonary
artery, dextroposition of the heart, and occasionally components of sequestration in the right
lower lobe with abnormal aortopulmonary collateral arteries.
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