CAS

1. FETAL THORAX AND
HEART

2. INTRODUCTION
 Structural cardiac anomalies are estimated to
occur in 8 per 1000 live births
 Given that CHD is the most common birth
defect, one of the major goal of second
trimester ultrasound examination is to evaluate
for cardiac disease

3. INTRODUCTION
 Cardiovascular anomalies are frequently
associated with other congenital anomalies
because the heart begins to develop the 3rd week
after conception and continues to develop until
the end of 8th week
 Since most cardiac abnormalities are found in
patients without associated risk factors, evaluation
of the fetal heart is an important component of a
routine obstetrics ultrasonographic examination

4. INTRODUCTION
 ISUOG guidelines suggest that the fetal
cardiac examination be performed between
18-22 weeks
 Under exceptional condition, it can be
performed earlier, especially in first trimester
screening shows an abnormality or increased
nuchal translucency

5. EXAMINATION OF THE FETAL HEART
 “BASIC” scan – analyzing a four-chamber
view of the fetal heart
 “EXTENDED-BASIC” scan – examine size
and relationship of both arterial outflow tracts
 “FETAL ECHOCARDIOGRAM” – more
detailed sonographic evaluation to be
performed by specialist in prenatal diagnosis
of CHD

6. Before any abnormalities can be described, the
proper technique of fetal heart ultrasound
examination should be discuss

7. FIRST KNOW THE ORIENTATION OF THE
FETUS
1. Presentation and lie of the fetus
2. Supine of prone position
3. SPINE – becomes the point of
reference in determining fetal
orientation

8. Coronal plane
1. Confirn the presence of the heart, stomach and bladder
2. Check the diaphragm
3. Ensure that there is no herniation of the abdominal contents
into the thorax

9. Axial or transverse

10. BASIC SCAN: Four-chamber view
 Is considered one of the most important planes
during fetal cardiac scanning
 It represents the starting plane for the basic
and detailed evaluation of the heart
 Consistently been shown to detect cardiac
defects

11.  Advantages of the four
chamber view include
visualization of the
1. Atria
2. ventricles,
atrioventricular valves
3. atrial and ventricular
septa

12. Scanning Technique
obtain transverse plane of the fetal abdomen
Perfect transverse plane: a
complete fetal rib imaged along
with each of the abdominal
walls
When multiple ribs are imaged
along the lateral abdominal
wall, an oblique rather than a
transverse plane is obtained

13.  From the transverse plane of the fetal
abdomen, slide the transducer towards the
fetal chest, maintaining in transverse plane,
until four chamber view is imaged
 The optimum plane for the visualization of the
four chamber view requires anatomic marker

14. Orientation
 The fetal heart lies almost horizontally in the
thorax with the four-chamber view plane
obtained in almost the same plane as a
transverse plane of the chest
 The fetal rib corresponding to the a four-
chamber view plane of the fetal heart is the
fourth thoracic rib

15. Transverse section of the
fetal thorax at the level of
the four-chamber view
within the amniotic cavity
The apical four-chamber
view (a) can be changed
to a transverse four
chamber view (b) by
translating the probe on
the mother’s abdomen
while maintaining the
section plane unchanged
Orientation

17. Orientation
When the fetal anterior chest wall is closest to the transducer, an
apical four-chamber view is obtained.
In this fetal position, the ultrasound beam is nearly parallel to the
ventricular septum, and it insonates the apical portion of the fetal

18. When the right posterior chest wall is closest to the transducer, a
basal four-chamber is obtained.
In this fetal position, the ultrasound beam enters the fetal chest
inferior to the right shoulder, nearly parallel to the ventricular septum
and it in insonates the base of the fetal heart first

19. When the fetal spine
is neither anterior nor
posterior but closer to
the right or left lateral
walls, a lateral-
chamber view (axial)
is obtained
In this fetal position,
the ultrasound beam
is nearly
perpendicular to the
ventricular septum

21. Anatomic characteristics of the
normal four chamber view
Normal size heart in chest
Transverse plane of the fetal chest with one complete rib on
each side of the fetal lateral chest wall

22. HEART POSITION AND AXIS
 Draw a line from the spine anteriorly to the
sternum anteriorly that bissetcs the chest into
two equal halves
 The heart is divided into two parts:
◦ One part is in the right chest and has about
1/3 of the heart mass
◦ 2nd part is in the left chest has the about 2/3
of the heart mass

23. Heart
Position
and Axis
 The normal cardiac axis points to the left
with an angle of about 45 degrees

24. Heart position and axis

25. Atria equal in size

26. Foramen ovale in midsection of the atrial septum with the
leaflet of foramen ovale in the left atrium, with evidence
of septum premium

27. Two inferior pulmonary veins, seen as slit-like opening in
the posterior wall of the left atrium

28. Presence of the crux of the heart, with the offset aspect of
the atrioventricular valves, which show normal systo-
diatolic excursion

29. Two distint atrioventricular valves
(right side - tricuspid; left side –
mitral) should be seen to open
separately and freely
The septal leaflet of the tricuspid
valve is inserted to the septum
closer to the apex when compared
to the mitral valve
Abnormal alignment of the
atrioventricular valves can be a key
sonographic findings for cardiac
anomalies – atrioventricula septal
defect

30. Two ventricles of similar diameter, with mild prevalence of
the right one, which also shows a rounder appearance
because of the presence of the moderator band. The left
ventricle forms the cardiac apex.

31. Equal thickness of the free ventricular walls, with
normal contractility

32. Intact interventricular septum.

33. Limitations of the Four-chamber view
 There are several defects may not
always demonstrate an abnormal four-
chamber view because:
1. heart defects may only involve the
outflow tracts
2. four-chamber view is obtained at the
level of the ventricles and atria, and not
at the level of the outflow tracts

34. Extended basic screening
4 chamber view + outflow tract

35.  Evaluation of outflow tracts can increase detection
rates for major cardiac malformations
 Four-chamber view of the heart is obtained from
an axial scanning plane across the fetal thorax
 Corresponding views of the left ventricular outflow
tract (LVOT) & right ventricular outflow tracts are
found by angling the transducer toward the fetal
head

36. Four-Chamber view image

37. Abnormalities of the Four-Chamber
View
 This is the result of
underdevelopment of
the left ventricular
chamber, left atrial
chamber, mitral valve
and aortic valve

38. Abnormalities of the Four-Chamber
View
 Abnormal tricuspid
valve of the right
ventricle.
 The valve is displaced
low in the right
ventricular chamber
 Results in changes in
the four chamber view
that include smaller
left atrium, abnormal
valve motion of the
tricuspid valve

39. Abnormalities of the Four-Chamber
View
 Endocardial cushion
defect often seen on
fetuses with down
syndrome
 Presence of
Ventricular and atrial
septal defect; a portion
of the wall dividing the
left and right side of
the heart is missing

40.  Rotational technique
 Sweep technique: described by Yoo,
et al & Tagel, et al and involves
sweeping the transducer beam in a
transverse plane from the level of the
four-chamber view towards the fetal
neck

42. Illustrate abdominal aorta exiting
the left ventricle

43. 1. Superior vena cava
(SVC
2. Cross section of the
Ascending Aorta (AA)
3. full length of the
Main Pulmonary Artery
(PA)
 Illustrate the ascending aorta perpendicular to the main
pulmonary artery.
 If these two vessels are not perpendicular to each other at this
level, then a s serious heart defect - TRANSPOSITION OF THE
GREAT VESSELS is most likely present

44. Transposition of great vessels
 Left ventricles
gives rise to the
pulmonary artery
 Right ventricles
gives rise to aorta
both the pulmonary
artery are parallel to
each other instead of
being perpendicular

45. Tetralogy of Fallot
 Ventricular septal
defect that
straddles the
dilated aorta

46. Illustrate the transverse aortic arch (TA) and the
ductus arteriosus (DA) merging with the thoracic
aorta

47. Summary of all views

48. Left ventricular Outflow Tract

49. Left ventricular Outflow Tract
 Originates entirely form
the LV
 Septo Aortic continuity
 Free movements of the
aortic valves & not
thickened
 No post valvular
dilatation
 No regurgitaton on
color doppler

50. When the LVOT is truly the aorta, it should even be possible to trace the
vessel into its arch, from which the three arteries originate into the neck
Identification of these aortic arch vessels should not be considered as a
routine part of the extended basic cardiac examination
LVOT may help to identify ventricular septal defect and conotruncal
abnormalities that are not seen during basic cardiac examination alone

51. Branches of the aortic arch
1. Brachiocephalic artery
2. Left common carotid artery
3. Left subclavian artery

52. Prone position

54. Right ventricular outflow tract

55. Right ventricular outflow tract
 Originates entirley form RV
 It is anterior to the left aorta
 Free movements of the
valves
 Bifurcates into two after the
origin
 Aorta is seen as ring
 No regurgitation of doppler

56. Fetal lungs
Examination of the lungs is in the same section used for the four chamber view
the fetal heart
At 18-23 weeks, central third of the thoracic area at the level of the four chambe
Of the heart, and the remaining 2/3 by the lungs, that are normally echogenic
This scanning plane can be used for the measurement of thoracic circumferenc

57. Abnormalities of Fetal Lung
CYSTIC ADENOMATOID MALFORMATION (CAM)
 Developmental abnormality arising from an
overgrowth of the terminal respiratory bronchioles
 Bilateral involving all lung tissue, bu majority is
confined to single lung or lobe
 Lesions are either macrocytic (@ least 5 mm in
diameter) or microcytic (< 5 mm in diameter)

58. Prenatal diagnosis on scan demonstrate of a hyperechogenic
pulmonary tumor which is cystic (CAM type 1), mixed (CAM type II),
or solid-microcystic (CAM type III
sporadic abnormality
both microcyctic and macrocystic lesion is associated with shift of
mediastinum
Large cyst Small cyst microcystic

59.  When there is compression of the heart and major
blood vessels in the thorax, fetal hydrops develops.
 Polyhydramnios is a common features and this is a
consequence of decreased fetal lung swallowing of
the amniotic fluid due to esophageal compression,
or increased fluid production by the abnormal
tissue.
 Prognostic factors include major lung compression
causing pulmonary hypoplasia, polyhydramnios
and development of hydrops fetalis

60. Diaphragmatic hernia
 Development of the diaphragm is usually
completed by 9th week of gestation
 In the presence of aefect in diaphragm, there is
herniation of the abdominal viscera into the thorax
about 10-12 weeks, when the intestines return to
the abdominal cavity from the umbilical cord
 Sporadic abnormality

61.  In about 50% of fetuses, there are associated
chromosomal abnormalities (trisomy 18, 13 &
Pallister-Killian syndrome- mosaicism for tetrasomy
12p)
 Other defects ( mainly craniospinal defects,
including spina bifida, hydrocephaly and cardiac
malformations)
 Genetic sydromes (Frynns syndrome, de Lange
syndrome & Marfan’s syndrome)

62. Diaphragm is an echo-free space between the thorax and
abdomen
diaphragmatic hernia can be diagnosed by demonstration of
stomach and intestines (90% of cases) or liver (50%) in the
thorax and associated with mediastinal shift to the opposite
side.
Left diphragmatic
hernia
Right Diaphragmatic hernia

63. Herniated abdominal contents associated with left-sided
diaphragmatic hernia are easy to demonstrate because of the
echo-free fluid filled stomach and small bowel contrast
dramatically with more echogenic fetal lung
Left diphragmatic
hernia
Right Diaphragmatic hernia

64. Right sided hernia is more difficult to identify because of the
echogenecity of the fetal liver is similar to that of the lung, and
visualization of the gall bladder in the right side of the fetal
chest may be the only way of making the diagnosis
Left diphragmatic
hernia
Right Diaphragmatic hernia

65. Abnormalities of Fetal Lung
Pleural effusions
 Unilateral or bilateral
 May be an isolated findings or in association with
generalized edema and ascites
 Infants affected by pleural effusions usually present
in neonatal period with severe, often fatal
respiratory insufficiency

66. Soft tissue
edema
hydrothorax

67. Abnormalities of Fetal Lung
 SEQUESTRATION OF THE LUNGS
 A portion of the lungs withoit connection to the
airways
 The blood suppley to the abnormal lung tissue is
through arteries that arise from the desecnding
aorta rather from the pulmonary artery
 Rare and the prevalence is less that 5% of the
congenital pumonary abnormalities

68. The sequestrated portion of the lung appears as a homogenous,
brightly echogenic mass in the lower lobes of the lungs or in the
upper abdomen (infradiaphragmatic sequestration)
diagnosis is confirmed by color doppler demostartion that the
vascular supply of the sequestered lobe arises from the abdominal
aorta
Aberrant tissue

69. Normal
lung
hydrothorax Sequestered lung

70. THANK YOU!