Radiological features of aortic aneurysm

2. I sincerely thank my
colleague for providing
the slides to me

3. DR.RAMAMOORTHY C
AORTIC ANEURYSM
DR.RAMAMOORTHY C

4. NORMAL VESSEL WALL
 INTIMA:the inner layer,composed of
endothelium,internal elastic lamina,scant intervening
tissue
 MEDIA:the middle layer,composed of
elastin,collagen,smooth muscle cells and extracellular
matrix proteins.
 ADVENTITIA:the outer layer,consists of connective
tissue,carries nerves and vasovasorum

6. ANEURYSM
 Defined as pathological dilatation of segment of a blood
vessel.
 True aneurysm- involves all the three layers of blood vessel.
 Pseudoaneurysm-intimal and medial layers are disrupted
and dilatation is lined by adventitia only or by perivascular
clot.
 Fusiform aneurysm-affects entire circumference of a segment
of the vessel.
 Saccular aneurysm –involves only a portion of circumference
resulting in outpouching of the vessel wall.

8.  morphologic features and extent, presence of
thrombus, relationship to adjacent structures and bra
nches, and signs of impending or acute rupture
 the wall and contents of an aneurysm, including
thrombus, thereby allowing a more accurate
measurement of aneurysm size

9. ETIOLOGY
 ATHEROSCLEROSIS
 CYSTIC MEDIAL NECROSIS
-marfan syndrome
-ehlers-danlos syndrome
-pregnency
-hypertension
-valvular heart disease
 TUBERCULOSIS
 SYPHILIS
 MYCOTIC ANEURYSM
 VASCULITIDES
 SPONDYLOARTHROPATHIES
 TRAUMA
 CONGENITAL

10. THORACIC AORTIC ANEURYSM

11. THORACIC AORTA
 consists of the aortic root, ascending aorta, aortic arch, and descending
thoracic aorta
 aortic root is defined as that part of the ascending aorta that contains
the valve, annulus, and sinuses
 The ascending aorta extends from the root to the origin of the right
brachiocephalic artery.
 the arch, from the right brachiocephalic artery to the attachment of the
ligamentum arteriosum.
 The arch is subdivided into proximal (right brachiocephalic artery to
left subclavian artery) and distal (left subclavian artery to attachment
of the ligamentum arteriosum) segments
 the descending aorta, from the ligamentum arteriosum to the aortic
hiatus in the diaphragm.
 ThorocoabdominalAorta-includes the descending and the abdominal
aorta

13.  Normal thoracic aortic diameter is 2.5 cm
 An aortic diameter greater than 5.0 cm or 2 times than normal
diameter is considered abnormal
 Circumference varies with age,sex,size of the patient and width
of vertebral body,hence presence of TAA should not be
concluded based on measurement of circumference alone.
 the normal diameter of the midascending aorta should always be
less than 4 cm, and that of the descending aorta no more than 3
cm
 The descending aorta should never be larger than ascending
aorta at a given scan level.
 Ratio of coronal diameter of ascending to that of descending
aorta should be 1.5:1.

15.  Involvement of the ascending aorta alone is usually associated
with annuloaortic ectasia, syphilis, postoperative aneurysms (at
the aortic suture line or at the site of aortic cannulation), aortic
valve disease, or infectious or noninfectious aortitis.
 atherosclerosis is a more diffuse process and rarely involves only
the ascending aorta .
 Postoperative ascending aortic pseudoaneurysms can occur at an
aortotomy site, cannulation site for cardiopulmonary bypass, or
needle puncture site or at incompetent suture lines
 Cross-clamping an atherosclerotic ascending aorta may also
cause an iatrogenic aortic dissection or pseudoaneurysm
 Saccular traumatic aneurysms are most common at the aortic
isthmus, whereas those secondary to penetrating ulcers can occur
anywhere in the descending aorta

16. Three-dimensional VR image shows the potential sites of postoperative ascending aortic
pseudoaneurysms. C = clamping site, Cn = cannulation site, G = graft, GA = graft
anastomosis, N = needle puncture site, v = valvulotomy site

18. ANNULOAORTIC ECTASIA
 a condition characterized by dilated sinuses of Valsalva
with effacement of the sinotubular junction producing a
pear-shaped aorta that tapers to a normal aortic arch, is
most commonly associated with Marfan syndrome
 Other causes include homocystinuria, Ehlers-Danlos
syndrome, and osteogenesis imperfecta,idiopathic
 the appearance of the aorta in patients with Marfan
syndrome is identical to that in patients with idiopathic
medial degeneration, there is a striking difference in the
natural history of these two conditions, with both onset
and progression being more rapid in Marfan syndrome

19. Marfan syndrome and annuloaortic ectasia in a 40-year-old man. Contrast-enhanced CT
scan (a) and three-dimensional VR image (b) show a pear-shaped aorta that tapers to a
normal aortic arch, a finding characteristic of Marfan syndrome and annuloaortic ectasia.

20.  When an acute aortic syndrome is suspected (owing
either to clinical signs and symptoms or to chest
radiographic findings), nonenhanced CT is usually
performed first to look for a high-attenuation acute
intramural hematoma.

21. SYPHILITIC AORTITIS
 Syphilitic aortitis causes focal destruction of the
media with loss of elastic and smooth muscle fibers
and scarring, leading to aortic dilatation and
aneurysms.
 The most common site of these TAAs is the ascending
thoracic aorta (36), aortic arch (34%), proximal
descending thoracic aorta (25%), and distal
descending thoracic aorta (5%), aortic sinus(<1%)
 most often asymmetric, as opposed to the symmetric
enlargement seen in annuloaortic ectasia

22.  Syphilitic aneurysms are at high risk for rupture.
 A less common manifestation is narrowing of the
coronary ostia due to subintimal scarring, resulting in
myocardial ischemia; this condition carries a poor
prognosis.
 Dissection is less common.

24. BICUSPID AORTIC VALVE
 the presence of bicuspid aortic valve is an independent
risk factor for TAA formation and not merely
consequence of poststenotic dilatation secondary to
aortic stenosis.
 Although aortic stenosis is a frequent complication of
bicuspid aortic valve , aortic aneurysms associated
with bicuspid aortic valve are not secondary to valve
dysfunction and have been described in the absence of
significant aortic stenosis and aortic insufficiency, in
patients who have undergone successful prosthetic
valve replacement for bicuspid aortic valve

25. Ascending aortic aneurysm and bicuspid aortic valve in a 40-year-old woman. (a, b)
Contrast-enhanced CT scan (a) shows an ascending aortic aneurysm. (b) Oblique axial
image through the plane of the aortic valve shows the bicuspid nature of the valve

26. MYCOTIC ANEURYSM
 Non-syphilitic infection of the arterial wall with
aneurysmal dilatation is referred to as mycotic aneurysm.
 Predisposing factors include contiguous bacterial
endocarditis, atherosclerosis, drug abuse, and aortic
trauma, immunocompromised state.
 usually saccular and contain eccentric thrombus.
 Have tendency to involve the ascending aorta.
 The most common infectious agents are non-hemolytic
Streptococcus, Pneumococcus, Staphylococcus,
Gonococcus, and Salmonella species,tuberculosis

27. Contrast-enhanced CT scan obtained in a 50-year-old man shows a retroesophageal
mediastinal abscess and a mycotic pseudoaneurysm of the descending thoracic aorta
(arrow)

28. NON INFECTIVE AORTITIS
 rheumatoid arthritis, ankylosing spondylitis, giant cell
arteritis, and relapsing polychondritis commonly affect the
ascending aorta.
 In rheumatic fever the involvement can be segmental,
limited to the ascending aorta, involve the abdominal
aorta, or involve the entire aorta.
 Takayasu arteritis commonly affects the aortic arch and its
major branches, with variable involvement of the
abdominal aorta and pulmonary arteries.
 CT features include high attenuation of the thickened
aortic wall with calcifications on nonenhanced scans.
 Arterial enhancement is considered a sign of active disease

29. Takayasu arteritis in a 35-year-old woman. (a, b) Contrast-enhanced CT scans obtained at
the level of the ascending (a) and distal descending (b) aorta show diffuse aortic wall
thickening and an ascending aortic aneurysm

30. POST TRAUMATIC ANEURYSM
 RAPID DECELERATION THEORY-the distal
transverse arch moves forward while the proximal
descending thoracic aorta remains stationary, held
back by the ligamentum arteriosum and the
intercostal vessels .
 OSSEOUS PINCH THEORY- an anteroposterior
compression force results in posteroinferior
displacement of the manubrium, first rib, and medial
clavicle, which impinge on the aorta and compress it
against the thoracic spine posteriorly.

31.  MC SITE OF INJURY- aortic isthmus (90% of cases),
followed by the ascending aorta and the descending
aorta near the diaphragmatic hiatus.
 Chronic pseudoaneurysms develop in 2.5% of patients
who survive the initial trauma.
 These often calcify, may contain thrombus and have
the potential to enlarge progressively, rupturing even
years after the initial trauma.

32. Contrast-enhanced CT scan obtained in a 28-year-old man shows a posttraumatic saccular
pseudoaneurysm at the aortic isthmus (arrow).

33. AORTIC DISSECTION
 Aortic dissection is an abnormal passage of blood into
the media through an intimal tear.
 This produces a false lumen that is separated from the
true lumen by an intimal flap.
 previous aortic dissection with a persistent false
channel may produce aneurysmal dilatation of the
false lumen.

34. Contrast-enhanced axial (a) and oblique sagittal reformatted (b) CT images obtained in a
65-year-old man show a type B aortic dissection with a partially thrombosed false lumen
and a descending TAA.

35. CLINICAL FEATURES
 Ascending Aortic Aneurysm-anterior chest pain, CHF
secondary to AI
 Aortic Arch Aneurysm-Chest pain, dysphagia, hoarseness
 Descending Aortic Aneurysm-back pain
 ThoracoabdominalAortic Aneurysm-back pain,
malperfusion.
 superior vena cava syndrome due to compression of the
superior vena cava
 stridor or dyspnea due to airway compression
 hoarseness due to compression of the recurrent laryngeal
nerve
 dysphagia due to esophageal compression

36. NATURAL HISTORY
 60-75% die within 2 years of diagnosis
 >50% die from rupture
 Symptomatic patients and patients with large
aneurysm have increased risk of rupture

37. CHEST XRAY
 Mediastinal mass or enlarged segment of aorta,often
containing mural calcification.
 Displacement and compression of esophagus or
trachea and bronchi
 Erosion of thoracic vertebrae and posterior ribs

39. COMPUTED TOMOGRAPHY
 Nonenhanced CT is usually performed first to look for
a high-attenuation acute intramural hematoma.
 The contrast-enhanced scanning that follows is the
key part of the CT examination.
 The correct timing of the arrival of contrast material in
the aorta is critical to image quality.
 Approaches to accomplishing this include a timing
bolus or a bolus tracking technique.

40. ECG GATING
 used to reduce motion artifacts, which can mimic
dissection or luminal irregularities.
 significant reduction in motion artifacts for the entire
thoracic aorta,the maximum benefit was seen at the
level of the aortic valve and ascending aorta.
 can facilitate evaluation of the proximal coronary
arteries.
 cases of suspected aortic dissection, it may be useful
for determining coronary artery involvement.

41. Prospective (ECG) gating Retrospective ECG gating
uses forward-looking prediction of R wave
timing
uses backward-looking measurement of R
wave timing
nonspiral acquisition spiral scanning
no table motion during imaging scanning during table motion
uses unique cone beam reconstruction Uses raditional cone beam reconstruction.
x-ray beam is turned on for only a short
portion of diastole, and it is turned off
during the rest of the R-R cycle,
x-ray beam is turned on throughout the R-R
interval
functional information about cardiac valve
motion, wall motion, or ejection fraction is
not available
can provide this functional information.
radiation dose is low (77% lower than for
retrospective gating)
radiation dose to patients is relatively high

42. Model shows retrospective ECG gating versus prospective ECG gating. With retrospective
gating, the intensity-modulated x-ray beam is on for the entirety of the R-R intervals
during imaging. With prospective gating, the x-ray beam is on for about 26% of every other
R-R interval.

43.  In the evaluation of the thoracic aorta for endovascular
repair, craniocaudal coverage should extend from the
neck to the femoral heads. Assessment of access to the
common femoral artery is essential to determine the
feasibility of large-bore sheath access. Knowledge of
the relationship between the aortic aneurysm and the
aortic branches is necessary to assess the adequacy of
the “landing zone” (the aortic segments proximal and
distal to the lesion where the stent extremities will be
positioned)

44.  To ensure an adequate neck for graft attachment, the
following conditions are desirable (25): (a) a minimum
distance of 15 mm from the aneurysm to the left
subclavian artery and to the celiac trunk, (b) a
maximum aortic landing zone diameter of 40 mm, and
(c) the absence of circumferential thrombus or
atheroma within the landing zone. If the lesion is very
close to the left subclavian artery, it may be necessary
to cover the origin of the subclavian artery to ensure an
adequate landing zone; however, patency of both
vertebral arteries must be demonstrated prior to the
procedure

45.  CT SCAN SHOWS
 Exact location and character of aneurysm
 Whether aneurysm affects origin of arch vessels
 Calcification
 Intraluminal thrombi
 Displacement or erosion of adjacent structures
 Perianeurysmal thickening and hemorrhage
 identify complications such as dissection and rupture.

46. Fusiform descending TAA in an 80-year-old man
Contrast material–enhanced CT scan shows an aneurysm containing thrombus (arrow

47. Anatomic Locations of Measurements in a Standard Report Describing the Thoracic Aorta

48.  Double oblique reformatted images obtained
perpendicular to the aortic lumen ( true short-axis
images of the aorta) allow more accurate measurement
of aortic diameter than does relying on axial CT scans,
on which the aorta has an oblique course.

49. Measurement of aortic diameter. (a) Axial contrast-enhanced CT scan of the descending
thoracic aorta indicates an aortic diameter of 23.4 mm (3D = three-dimensional). (b)
Double oblique reformatted CT image of the descending thoracic aorta obtained at the
same level shows the aorta in true cross-section, with a diameter of 18.5 mm (3D = three-
dimensional). The aortic diameter was overestimated on the axial scan, which showed the
aorta coursing obliquely

50. ABDOMINAL AORTIC ANEURYSM
 Disease of elderly people.
 Affects men four times more
common than women.
 Risk increases with
smoking,family history,with
history of peripheral vascular
disease,cardio vascular disease
and hypertension.
 Increase in size at a rate of 1.7 to
2.6 mm per year.
 Larger aneurysms extend more
rapidly than smaller ones.
(LaPlace law)

51. NORMAL SIZE OF AORTA
 Supra celiac aorta: 2.5 to 2.7 cm in men, 2.1 to 2.3 in
women.
 Infrarenal aorta : 2.0 to 2.4 cm in men, 1.7 to 2.2 in
women.

52. SONOGRAPHIC PRINCIPLES
 Maximum diameter is measured from outer edge of the wall
to outer edge of the opposite wall.
 Measurements should be taken perpendicular to the axis of
the lumen.
 With fusiform aneurysm measurement is taken in any
longitudinal plane.
 Transverse scanning is necessary for saccular aneurysm and
measurement is taken in the plane of eccentricity of
aneurysm.
 Completeness of the examination is assessed by seeing celiac
artery or aortic hiatus of diaphragm proximally and aortic
bifurcation distally.

55. COMPUTED TOMOGRAPHY
 CT assessment of aneurysm is necessary if
 the patient is too obese.
 Aneurysm is eccentric and area of eccentricity is not well
seen with ultrasound.
 Patient is acutely symptomatic.
 Suspected inflammatory AAA.
 Aneurysm is suspected of having reached a size at which
treatment is needed.

57. RUPTURE OF ANEURYSM

58. RUPTURE

59.  Elective aneurysm repair has a lower mortality rate (9%) than
does emergent repair (22%); therefore, aneurysms are considered
for repair when they are either symptomatic or exceed 5–6 cm in
diameter.
 median size of rupture-dissection of ascending and descending
aortic aneurysms as 5.9 and 7.2 cm, respectively, and advocated
surgical intervention for ascending TAAs exceeding 5.5 cm and
for descending TAAs exceeding 6. 5 cm.
 Earlier intervention is recommended in patients with Marfan
syndrome and is advocated at an aortic diameter of 5 cm
 An annual growth rate greater than 1 cm is an accepted
indication for surgical repair

60. SYMPTOMS
 Sudden, intense pain in the back or abdomen, possibly
spreading to the groin, buttocks and legs
 Throbbing lump-like mass or sensation in the abdomen
 Abdominal rigidity
 Symptoms of shock, including trembling, dizziness,
sweating, fainting and elevated heart rate
 Nausea and vomiting
 Anxiety
 Pale skin
 Dry mouth and great thirst

61.  aortobronchial fistula which manifests clinically as
hemoptysis and at CT as consolidation in the adjacent
lung due to hemorrhage
 the fistulous communication itself is not commonly seen at
CT
 Most aortobronchial fistulas (90%) occur between the
descending aorta and the left lung .
 aortoesophageal fistula is less common and is usually
associated with hematemesis and dysphagia .
 CT findings include mediastinal hematoma, an intimate
relationship of the aneurysm to the esophagus, and, rarely,
contrast material extravasation into the esophagus

62. Aortobronchial fistula in a 50-year-old man with hemoptysis. Contrast-enhanced CT scan
shows a focal rupture of the descending TAA, consolidation in the adjacent left lower lobe
of the lung, and endobronchial blood in the left lower lobe segmental bronchus (arrow),

63. Aortoesophageal fistula in a 73-year-old
man. Nonenhanced (a, b) and contrast-
enhanced (c) CT scans show an
aortoesophageal fistula and intraesophageal
rupture of a saccular descending TAA. High-
attenuation blood is seen within the
mediastinum in a and within the esophagus
in b.

64. IMAGING
 CT : Advantage
 Speed of examination, widespread availability
 CECT :
 Size of Aneurysmal lumen, presence of active
extravasation, relationship of aneurysm to the
celiac, superior mesentric renal & inferior
mesentric arteries.
 USG :
 Determine the size of aneurysm
 Identify hemoperitoneum
 cannot evaluate entire aorta due to bowel gas

65. CT PROTOCOL
 UECT - 5 mm collimation, Abdomen & pelvis
 CECT - CT Angiography - 90 ml of non inonic
contrast is given as dynamic bolus IV – 3-4 ml / sec
1mm collimation of abdomen and pelvis
 Delayed imaging at portal venous phase (80 sec) 5mm
collimation
 Allergy to iodine – Gadolinium enhanced CT angio
dose of contrast (0.3 to 0.5 mmol/kg)

66.  Imaging findings of A. aneurysm rupture vary from impending
rupture to contained rupture from small aortic leaks with subtle
infiltration of retroperitoneal fat to frank retroperitoneal or intra
peritoneal extra vasation
 UECT
 A retro peritoneal hematoma
 peri aortic blood extension into perirenal spaces
 para renal space or psoas muscle
 Intra peritoneal extension
 CECT
 Active extravasation of contrast noted
 Draped aorta sign
 post wall of aorta is not identifiable or it closely follows the
contour of adjacent vertebral bodies, a consequence of a deficient
aortic wall

70.  Findings predictive of Impending rupture :
 Increased Aneurysm size
 Thrombus and calcification
 Hyperattenuating crescent sign

71. Increased Aneurysm size
 Common finding predictive of rupture
 Common indicator for elective surgical
management is maxi diameter of aneurysm > 5 cm
 Wall tension in A. Aneurysm is proportional to mean
vessel radius. Laplace Law T – PR
 Diameter of > 7 cm with acute aortic syndrome,
high likelihood of aneurysm rupture
 Enlargement ratio of 10 mm or more per year
 Indication for surgical repair.

72. Thrombus & Calcification
 thrombus to lumen ratio decrease with increasing
aneurysm sizes
 Thick circumferential thrombus is protective
against rupture
 Enlargement of patent lumen is indicative of
partial lysis of thrombus, predispose to rupture.
 Focal discontinuity in circumferential wall
calcifications

73. Hyperattenuating cresent sign :
 Earliest & most specific imaging manifestation
 Well defined peripheral crescent of increased
attenuation within the thrombus of a large
abdomen aortic aneurysm
 Best seen in unenhanced CT image
 Internal dissection of blood into either the
peripheral thrombus or aneurysm wall.

75. TAA MIMICS
 DUCTUS DIVERTICULUM
 consists of a convex focal bulge along the anterior
undersurface of the isthmic region of the aortic arch.
 Though Ductus diverticulum is commonly believed to be a
remnant of the closed ductus arteriosus, it has been
suggested that this entity may actually represent a remnant
of the right dorsal aortic root
 Differentiated from pseudoaneurysm by smooth margins
with gently sloping symmetric shoulders and forms obtuse
angles with the aortic wall.
 important to differentiate ductus diverticulum from a
posttraumatic aortic pseudoaneurysm, which most
commonly occurs at the aortic isthmus.

76. DUCTUS DIVERTICULUM
Ductus diverticulum in a 35-year-old man. The entity was seen at CT angiography of the
thoracic aorta. Axial (a) and sagittal reformatted (b) CT images show a focal convex bulge
(arrow) along the anterior aspect of the isthmus. Note the obtuse angles with the aortic
wall, unlike with a pseudoaneurysm

77. AORTIC SPINDLE
 smooth, circumferential bulge below the isthmus in
the first portion of the descending aorta.

78. POST OPERATIVE ASSESSMENT
 The normal postoperative appearance of the thoracic
aorta can be confusing and may mimic disease; hence,
knowledge of surgical details is of paramount
importance
 Aortic grafts may be tissue (porcine) grafts or synthetic
in nature.
 Tissue grafts are indistinguishable from native aortic
tissue at CT, whereas synthetic grafts have a higher
attenuation that is readily seen at nonenhanced CT.

79. Ascending Thoracic Aortic
Aneurysms
 aneurysm is generally resected and replaced with a
prosthetic Dacron tube graft of appropriate size.
 Bentall procedure-Done When the aneurysm involves
the aortic root and is associated with significant aortic
regurgitation by using a tube graft with a prosthetic
aortic valve sewn into one end. The valve and graft are
sewn directly into the aortic annulus, and the coronary
arteries are then reimplanted into the Dacron aortic
graft

80.  After the diseased segment has been excised, an
interposition graft is sewn end to end and vascular
branches (such as coronary arteries) are reimplanted.
Felt rings and pledgets are often used to reinforce the
site of anastomosis and the site of cannula placement.
These objects can mimic pseudoaneurysms on
contrast-enhanced scans but can easily be identified
because of their high attenuation on nonenhanced
scans.

81. Composite aortic graft repair of aneurysm involving the aortic root and ascending thoracic
aorta. The coronary arteries are excised as buttons, and the aneurysm is resected to the
level of the aortic annulus, with sacrifice of the native aortic valve. A prosthetic valve is
attached directly to a Dacron graft, and this composite graft is sewn directly to the annulus.
The native coronary buttons are then reimplanted into the graft

82. Valve-sparing procedure
 when the aortic valve leaflets are structurally normal
and the aortic regurgitation is secondary to dilatation
of the root, a valve-sparing root replacement may be
performed
 .This technique, involves excising the sinuses of
Valsalva while sparing the aortic leaflets, sewing a
Dacron graft to the base of the aortic annulus, and
reimplanting the aortic valve leaflets within the graft
to restore their normal anatomic configuration.

83. Valve-sparing procedure to repair an aneurysm involving the aortic root and ascending
thoracic aorta. The aortic sinuses are excised, but the valve leaflets are not. The leaflets are
then placed within the lumen of a Dacron graft that is then sewn directly to the aortic
annulus. The valve leaflets are then reimplanted within the base of the graft to restore
competency

84. Arch Aneurysms
 To replace the dilated arch with a prosthetic tube graft,
the brachiocephalic vessels must be removed from the
arch before its resection and then reimplanted into the
tube graft arch after its interposition.
 Traditionally, this involved removing and then
reimplanting the brachiocephalic vessels en bloc.
 newer surgical technique using a multilimbed
prosthetic arch graft, to which each arch vessel is in
turn anastomosed individually

85. Repair of an aneurysm involving ascending thoracic aorta and arch by using a multilimbed
prosthetic graft

86. Descending Thoracic Aortic
Aneurysms
Repair of a descending thoracic aortic aneurysm

87. ELEPANT TRUNK TECHNIQUE
 The “elephant trunk” technique is used in patients
with diffuse aneurysmal disease and involves graft
replacement of the ascending aorta and aortic arch
with or without valve replacement.
 The free segment of the graft is left projecting into the
proximal descending aorta, which can then be
repaired at a later date

88. Aortic repair with the elephant trunk technique in a 53-year-old woman. (a) Contrast-
enhanced CT scan shows the “elephant trunk” simulating a dissection flap. Note the felt
strip at the distal aortic anastomosis (arrow). (b) Sagittal reformatted CT image clearly
depicts the distal end of the aortic arch graft dangling into the descending thoracic aorta.

89.  In such cases, an alternative staged surgical approach known as
the “elephant trunk” technique is used.30 The first part of the
surgery is, for the most part, similar to the standard ascending
aneurysm and total arch repair. However, the distal end of the
arch aortic graft is several centimeters longer than the native
arch, so that after the anastomosis is made to the proximal
descending aorta (just distal to the left subclavian artery), the
excess length of the graft is left protruding distally within the
lumen of the descending thoracic aortic aneurysm. In the second
stage of this procedure, the descending or thoracoabdominal
aortic aneurysm is repaired via a standard left thoracotomy.
However, the surgeon cross-clamps the distal end of the existing
elephant trunk (rather than clamping the dilated native aorta),
and the proximal end of the new descending aortic graft is now
anastomosed to the free distal end of the elephant trunk.

90.  Felt rings and pledgets are often used to reinforce the
site of anastomosis and these objects can mimic
pseudoaneurysms on contrast-enhanced scans.
 An inclusion graft is inserted into the aortic lumen,
leaving a potential space between the native aorta and
the graft that may thrombose or even show persistent
blood flow.

91. Contrast material in the perigraft space in a 75-year-old man with an inclusion root graft.
Routine follow-up CT scan shows contrast material (curved arrow) in the space between
the inclusion root graft and the surrounding native aortic wrap, arising from a right
coronary artery “button” anastomosis (straight arrow).

92. LANDING ZONE
 the aortic segments proximal and distal to the
lesion where the stent extremities will be
positioned
 Knowledge of the relationship between the aortic
aneurysm and the aortic branches is necessary to
assess the adequacy of the landing zone.
To ensure an adequate neck for graft attachment,
the following conditions are desirable
 a minimum distance of 15 mm from the aneurysm
to the left subclavian artery and to the celiac trunk
 a maximum aortic landing zone diameter of 40
mm
 the absence of circumferential thrombus or
atheroma within the landing zone.

93.  To ensure an adequate neck for graft attachment, the
following conditions are desirable (25): (a) a minimum
distance of 15 mm from the aneurysm to the left
subclavian artery and to the celiac trunk, (b) a
maximum aortic landing zone diameter of 40 mm, and
(c) the absence of circumferential thrombus or
atheroma within the landing zone. If the lesion is very
close to the left subclavian artery, it may be necessary
to cover the origin of the subclavian artery to ensure an
adequate landing zone; however, patency of both
vertebral arteries must be demonstrated prior to the
procedure

94. ENDOVASCULAR REPAIR
 Endovascular repair of the thoracic aorta is an alternative
surgical procedure in poor surgical candidates or in emergency
situations
 A unique complication of endovascular repair is an endoleak.
 Endoleak is an area of aneurysm that has been excluded by
graft that continues to have blood flow.
 Endoleaks have been divided into four types on the basis of the
source of blood flow

95. TYPES OF ENDOLEAKS
 Type 1:one of the ends of graft is not tightly opposed to
arterial wall allowing blood to enter aneurysmal sac.
 Type 2: retrograde flow into the sac through an aortic
branch
 Type 3:disruption of integrity of graft cauced by fabric
tear.
 Type 4:due to egress of blood through the pores in the
fabric

97. TYPE I LEAK

98. TYPE II LEAK

99. TYPE III LEAK
Type III endoleaks in several locations. Angiographic CT image where with anterior
mediastinal hematoma and a stent located in the ascending aortal arch and the
descending aorta, placed within the aortic aneurysm. The aneurysm is not excluded with
contrast filling of the false and true lumen.

100.  Identification of the correct type of endoleak has important treatment
implications. Type 1 and type 3 endoleaks are repaired immediately, the
former by securing the attachment sites with angioplasty balloons,
stents, or stent-graft extensions and the latter by covering the defect
with a stent-graft extension (45). The management of type 2 endoleak
is controversial, and, although some authors follow up this type of
endoleak as long as the size of the aneurysm does not increase, others
prefer to repair it (45). Type 4 endoleaks are self-limited, require no
treatment, and resolve with normalization of the patient’s coagulation
status (45).
 Aneurysm expansion without endoleak is known as endotension or
type 5 endoleak (45). Although the exact cause of endotension is
unknown, possible causes include an endoleak that cannot be
visualized with traditional imaging techniques, ultrafiltration of blood
across the graft, and thrombus providing an ineffective barrier to
pressure transmission (45).

101.  TTE is not accurate for diagnosing thoracic aneurysms,
and it is particularly limited in its ability to examine
the descending thoracic aorta. TEE is a far more
accurate method for assessing the thoracic aorta and
has become widely used for detection of aortic
dissection. There has been less experience with TEE,
however, in the evaluation of nondissecting thoracic
aneurysms.