4. EMBRYOLOGY
• The aortic arches are a
series of paired arterial
channels encircling the
embryonic pharynx
• They:
– Develop in the 4th week
– Supply the developing
pharyngeal arches
– Arise from the aortic
sac
– Run dorsally, embedded
in the mesenchyme of
the pharyngeal arches
and
– Terminate in the right
and left dorsal aortae
5. • Develop in a craniocaudal
sequence
• There are potentially six pairs,
but the fifth pair is poorly
developed and disappears soon
after formation
• Not all the 6 pairs present at the
same time. By the time the 6th
aortic arches are formed, the 1st
& 2nd have disappeared Aortic
--sac
7. First Pair
• Largely disappear
• Dorsal part persists as
the maxillary arteries
which supply the ear,
teeth and muscles of the
eyes and face
• May give rise to the
external carotid artery
The first arch is obliterated before
the 6th arch is formed
8. Second Pair
• Largely disappear
• Dorsal part persists
as the hyoid and
stapedial arteries
9. Third Pair
• Proximal part:
forms the
common
carotid arteries
• Distal part:
joins the dorsal
aortae to form
the internal
carotid arteries
10. Fourth Pair
• RIGHT:
Becomes the
proximal part of
the right
subclavian artery
• LEFT: Forms
part of the arch
of aorta
12. Sixth Pair
• RIGHT:
• Proximal part: persists as
the proximal part of the
right pulmonary artery
• Distal part: degenerates
• LEFT:
• Proximal part: persists as
the proximal part of the left
pulmonary artery
• Distal part: forms ductus
arteriosus, a shunt between
pulmonary artery and
dorsal aorta
13. Arch of Aorta
Derived as:
• Proximal segment
from aortic sac
• Middle segment from
the left 4th aortic arch
• Distal segment from
the left dorsal aorta
14. Subclavian Artery
• The right subclavian
artery formed from the:
Right 4th aortic arch
Right dorsal aorta &
Right 7th
intersegmental artery
• The left subclavian
artery formed from the
left 7th intersegmental
artery
15. AORTIC ARCH
ANOMALIES
Left Arch With Aberrant Right
Subclavian Artery
Right Aortic Arch
Double Aortic Arch
Interrupted Aortic Arch
Cervical Arch
Coarctation
Pseudocoarctation
•
17. Aortic isthmus
Narrowing of fetal aorta distal to
Lt
• Subclavian.Disappears after 2
months.
Aortic spindle
Fusiform enlargement of aorta
just beyond the ductus.
NORMAL ANATOMY
18. • Ductus diverticulum
Focal bulge along anteromedial
aspect of aortic isthmus(33%
infants &9% of adults.
A classic ductus diverticulum has
smooth uninterrupted margins &
gently slopping symmetric
shoulders.
May persist into adulthood.
NORMAL ANATOMY
20.
Most common arch anamoly.
Not a true ring
usually asymptomatic.
Pushes trachea and esophagus
forward
Produces oblique shadow above
aortic arch on frontal film
Origin of RSCA may be dilated –
called kommerells diverticulum.
21. Notice that there is a
left arch, but the
right subclavian
artery is the last
brachiocephalic
artery to branch off
the arch
22. There is a dilated
vessel that compresses
the esophagus and it
originates from the left-
sided aorta, i.e. an
aberrant right
subclavian artery
23. Double Aortic Arch
•
• General considerations
–Most common vascular ring
Caused by persistence of R and L
4th branchial arches.
–Rarely associated with congenital
heart disease
•Vascular ring produces tracheal
and/or esophageal compression
24. Passes on both sides of trachea
Joins posteriorly behind esophagus
Right arch is larger and higher
Left arch is smaller and lower
Barium swallow shows bilateral impressions on
frontal view
Posterior impression on lateral view
Angiogram is characteristic
26. On the left axial images and
posterior view of volume rendered
reconstruction.
Findings are:
four vessel sign
double arch
right arch higher and larger
esophagus and trachea are
completely encircled
27. The narrowing of the
trachea is seen on the
axial images, but better
appreciated on the MPR
and Volume Rendered
image.
28. Occasionally the double
arch can have an atretic
segment.
You should not confuse it
for a right arch.
The left arch is just very
small and there is still a
four vessel sign.
DOUBLE ARCH WITH ATRETIC SEG
29. the left a dominant right arch
and a small left arch.
The atretic segment is marked
by the arrow.
Notice the four vessel sign.
30. On a posterior
view the
interruption is
nicely
demonstrated.
Remember that
there is still a ring,
so there is still
obstruction.
33. RIGHT ARCH WITH MIRROR
IMAGING
Secondary to interruption of left arch just distal
to ductus arteriosus . Mirror imaging of normal
left arch.
Associated with congenital heart disease 98% of
time. Most commonly with TOF &truncus.
Mostly asymptomatic because there s no vascular
ring.
34. • Right Arch Mirror Image
• This is the mirror-image variety of the
left arch.
• On the left a 2 year old girl with
wheezing and coughing.
On the axial image there is a right
arch
On the volume rendered image there
is mirror image branching of the
brachiocephalic arteries, no aberrant
subclavian artery
37. Right Arch with Aberrant left
subclavian
.Usually occur as isolated anomaly
The ligamentum ductus arteriosus between the left
subclavian artery and the left pumonary artery
completes the ring.
If this ligament is very short, there will be a lot of
compression
38. CT axial image shows right arch
with an aberrant left
subclavian.artery
39. Posterior oblique view of volume
rendered image to show the
aberrant left subclavian artery.
40. On the axial image there is a
right arch with the left
subclavian artery that comes
off on the posterior side and
runs behind the trachea and
the esophagus.
The compression of the
trachea is demonstrated on the
volume rendered view
41. INNOMINATE ARTERY
COMPRESSION SYNDROM
The compression in the
innominate artery
compression syndrome is
located on the right anterior
side and at the level of the
thoracic inlet.
This is much higher than in
the double arch or Right
Aortic Arch with Aberrant left
subclavian
42. Innominate artery compression
syndrome
• .
.
The findings are:
• anterior compression of the trachea
• brachiocephalic (innominate) artery
located more to the left and
compresses the trachea
43. INTERRUPTED AORTIC ARCH
Lack of luminal continuity between
ascending and descending aorta.
Most common asso cardiac defect are PDA
&VSD.
44. Type A occurs,
result of abnormal regression of the left fourth
aortic arch after ascension of the left subclavian
artery to its expected position.
Type B occurs,
when the left fourth aortic arch regresses before
normal ascension of the left subclavian
artery to its expected position.
Type C occurs,
when the ventral portion of the left third aortic
arch and left fourth aortic arch involute, and
there is a persistent ductus caroticus, a structure
that normally regresses
Regarding Embryology
47. 3-day-old male neonate with type B
interrupted aortic arch,
large aortopulmonary
window,
pulmonary sling.
Coronal gradient-recalled echo “white
blood” MR
image shows abnormal communication
between
ascending aorta (AA)
main pulmonary artery
(MPA), so-called aortopulmonary window
(APW).
48. MR image shows innominate artery
(IA) and left
common carotid artery (LCCA) arising
from proximal
aortic arch in V configuration
49. A, Coronal maximum-intensity-projection
gadolinium-enhanced 3D MR angiography image
shows apparent interruption (INT) of aortic arch
between left common carotid artery (LCCA) and
left
subclavian artery (LSCLA). Right pulmonary artery
(RPA) is seen. PDA = patent ductus arteriosus,
DA = descending thoracic aorta.
2-day-old female neonate with Down
syndrome, right aortic arch with left
descending
thoracic aorta and hypoplastic
retroesophageal
segment, ventricular septal defect, and
bilateral
superior venae cavae.
50. Type C -interruption
occurs between
innominate and left
common carotid arteries.
Patent ductus arteriosus
provides blood flow to
left common carotid, left
subclavian,
and descending thoracic
arteries.
51. Volume-rendered image
confirms presence of
hypoplastic retroesophageal
aortic segment (REA)
on closer inspection. Patent
ductus arteriosus (PDA)
also supplies blood flow to
descending thoracic aorta
(DA). MPA = main pulmonary
artery.
52. General Consideration:
Usually asymptomatic
May present as pulsating supraclavicular mass
May produce vascular ring & compress airway
Embryogenesis uncertain
Over 80% are right-sided
CERVICAL AORTIC ARCH
53. Right-sided cervical aortic arches
Right apical mass-like density
Absence of aortic knob on left
Aorta descends on the left
Displace the trachea and esophagus forward
Branching may be normal or mirror-image
Imaging Findings Right-sided lesions
57. General consideration
l classification
o Infantile or preductal form
o Adult or juxtaductal form
l Adult Form
o Adult or juxtaductal
(postductal) form is more
common
o Usually localized
o Area of coarctation is just
beyond the origin of LSCA at level
of ductus
58. l Infantile Form
Infantile, preductal form = diffuse
type
Long, tubular segment of narrowed aorta
From just distal to innominate to level of
ductus
Intra cardiac defects (VSD,ASD, deformed
mitral valve) present in 50% of diffuse type
Also patent ductus arteriosis
Bicuspid aortic valve (most
common associated defect seen in 75-
80%)
59. Clinical Findings–
Infancy
Severe CHF most common from 2nd to 6th
week of life
Weak or absent leg pulses
Lower BP in the legs than in the arms
RV hypertrophy because RV assumes most
of the cardiac output during fetal life in these
patients
l Clinical Findings-Children and Adults
Differential pulses in arms (bounding) and
legs (weak)
LVH
65. The findings are:
Large thymus which is normal
for a 2 month old.
Striking discrepancy between
diameter of ascending and
descending aorta.
The diagnosis is coarctation,
which is nicely demonstrated on
the posterior view of the
reconstruction.
66. MRI OF COARCTATION
Spin echo sequences
• Mainstay of morphological diagnosis
• Provides highest contrast resolution limited
temporal resolution
• Blood in black with internal structures
contrast against signal void of heart
chambers.
70. 1. Reduction of luminal diameter greater
than 50% at any age
2. Upper body hypertension over
150mmHg
in young infant ( not in heart failure )
3. CoA with congestive heart failure
at any age
Indications for operation
•
71. PSEUDOCOARCTATION
• ARCH BUCKLED AT LIG. ARTERIOSUM
• MOST OFTEN DISCOVERED AS A
MEDIASTINAL MASS ON PA CHEST
RADIOGRAPH
• LOOK FOR KINK OF DESCENDING AORTA
ON LATERAL CHEST DIOGRAPH
• MEASUREMENT OF GRADIENT ACROSS
KINK MAY BE NECESSARY TO
DIFFERENTIATE FROM COARCTATION
