2. ANATOMY
• The aorta is the ultimate conduit, carrying, in an average lifetime,
almost 200 million litres of blood to the body.
• It is divided by the diaphragm into the thoracic and abdominal
aorta .
• The aortic wall is composed histologically of three layers:
• a thin inner tunica intima lined by the endothelium;
• a thick tunica media characterized by concentric sheets of elastic
and collagen fibres with the border zone of the lamina elastica
interna and -externa, as well as smooth muscle cells; it gives
elasticity to aorta and
• the outer tunica adventitia containing mainly collagen, vasa
vasorum, and lymphatics. Gives tensile strength
3.
4. PHYSIOLOGY
• The aortic wall pressure – diameter relation is
nonlinear , a more distensible component at lower
pressure and stiffer component at higher pressure ,
with transition at 80 mm Hg .
• The pressure diameter curve becomes less steep with
ageing because
• 1) increase in collagen to elastin ratio
• 2) progressively disordered medial elastic fibres and
lamellae
• 3) an increase in aortic wall thickness with deposition
of collagen and calcification of elastic fibres
• 4) atherosclerotic changes leading to wall stiffness
5. • In healthy adults, aortic diameters do not usually
exceed 40 mm and taper gradually downstream.
• They are variably influenced by several factors
including age, gender, body size [height, weight, body
surface area (BSA)] and blood pressure.
• In this regard, the rate of aortic expansion is about 0.9
mm in men and 0.7 mm in women for each decade of
life.
• This slow but progressive aortic dilation over mid-to-
late adulthood is thought to be a consequence of
ageing, related to a higher collagen-to-elastin ratio,
along with increased stiffness and pulse pressure.
11. What are the risk factors for aortic
aneurysm?
• Some of the same risk factors for heart attack also
increase the risk of aortic aneurysm, including:
• Atherosclerosis (plaque in the artery walls)
• High blood pressure
• Diabetes
• High cholesterol
• Smoking
• Heredity
• Bicuspid aortic valve
• Injury or infection also can cause an aneurysm to
develop if the aorta walls weaken as a result.
13. Etiology and pathogenesis
• Genetic - marfans, vascular ehler danlos syd, FTAA,
Loeys-Dietz syd , BAV, turners syd
• Degenerative
• Atherosclerotic
• Mechanical
• Inflammatory
• Infectious
• Cystic medial degeneration is basic pathology in many
conditions – degeneration and fragmentation of elastic
fibres , loss of smooth muscle cell ,increase in
deposition of collagen and replacement with interstitial
cysts .
14. Clinical manifestations
• While aortic diseases may be clinically silent in
many cases, a broad range of symptoms may be
related to different aortic diseases:
• Acute deep, aching or throbbing chest or
abdominal pain that can spread to the back,
buttocks, groin or legs, suggestive of AD or
other AAS, and best described as ‘feeling of
rupture’.
• Cough, shortness of breath, or difficult or
painful swallowing in large TAAs.
•
15. • Constant or intermittent abdominal pain or
discomfort, a pulsating feeling in the
abdomen, or feeling of fullness after minimal
food intake in large AAAs.
• Stroke, transient ischaemic attack, or
claudication secondary to aortic
atherosclerosis.
• Hoarseness due to left laryngeal nerve palsy
in rapidly progressing lesions.
17. • Thoracic aortic aneurysm is a virulent,
potentially lethal disease.
• It is also a predominantly silent disease.
• This combination of circumstances cries out
for discovery of biomarkers for this disease—
blood tests that can detect aneurysms in the
general population, monitor the progress of
an aneurysm, and predict complications in
those patients known to be affected.
18.
19. Diagnosis and sizing
• The aorta is a complex geometric structure
and several measurements are useful to
characterize its shape and size .
• If feasible, diameter measurements should be
made perpendicular to the axis of flow of the
aorta.
20. • First, no imaging modality has perfect resolution and the
precise depiction of the aortic walls depends on whether
appropriate electrocardiogram (ECG) gating is employed.
• Also, reliable detection of aortic diameter at the same
aortic segment over time requires standardized
measurement; this includes similar determination of edges
(inner-to-inner, or leading edge-to-leading edge, or outer-to-outer diameter
measurement, according to the imaging modality).
• Whether the measurement should be done during systole
or diastole has not yet been accurately assessed, but
diastolic images give the best reproducibility.
21. • Inter- and intra-observer variability of CT for AAA are
approximately 5 mm and 3 mm, respectively.
• Thus, any change of >5 mm on serial CT can be considered
a significant change, but smaller changes are difficult to
interpret.
• Compared with CT, ultrasound systematically
underestimates AAA dimensions by an average of 1–3 mm.
• It is recommended that the identical imaging technique be
used for serial measurements and that all serial scans be
reviewed before making therapeutic decisions.
22. • Transthoracic echocardiography
• Echocardiographic evaluation of the aorta is a
routine part of the standard echocardiographic
examination.
• Although transthoracic echocardiography (TTE) is
not the technique of choice for full assessment of
the aorta.
• Transthoracic echocardiography also permits
assessment of the aortic valve, which is often
involved in diseases of the ascending aorta.
23. • Transthoracic echocardiography is an excellent
imaging modality for serial measurement of
maximal aortic root diameters, for evaluation
of aortic regurgitation, and timing for elective
surgery in cases of TAA.
24. • Abdominal ultrasound
• Abdominal ultrasound remains the mainstay
imaging modality for abdominal aortic
diseases because of its ability to accurately
measure the aortic size, to detect wall lesions
such as mural thrombus or plaques, and
because of its wide availability, painlessness,
and low cost.
25. • Computed tomography plays a central role in the
diagnosis, risk stratification, and management of aortic
diseases.
• Its advantages over other imaging modalities include
the short time required for image acquisition and
processing, the ability to obtain a complete 3D dataset
of the entire aorta, and its widespread availability.
• Electrocardiogram (ECG)-gated acquisition protocols
are crucial in reducing motion artefacts of the aortic
root and thoracic aorta.
• High-end MSCT scanners (16 detectors or higher) are
preferred for their higher spatial and temporal
resolution compared with lower-end devices.
26.
27. Natural history
• TAA are relatively indolent with growth rate of
0.1-0.2 cm/year and marked individual variability.
• Mean rate of rupture or dissection –
• 2% /year for <5 cm
• 3% /year for 5- 5.9 cm
• 7% /year for > 6 cm
• Risk factors for increased growth and rupture –
• Older age , female sex, COPD , HTN, smoking
,pain, aortic dissection and family history .
28. Management
• Principles of medical therapy
• The main aim of medical therapy in this condition
is to reduce shear stress on the diseased segment
of the aorta by reducing blood pressure and
cardiac contractility.
• Cessation of smoking is important
• Moderate physical activity probably prevents the
progression of aortic atherosclerosis but data are
sparse.
• competitive sports should be avoided in patients
with an enlarged aorta.
29. • In chronic conditions, blood pressure should be
controlled below 140/90 mm Hg, with lifestyle changes
and use of antihypertensive drugs, if necessary.
• An ideal treatment would be the one that reverses the
formation of an aneurysm.
• In patients with Marfan syndrome, prophylactic use of
beta-blockers, angiotensin-converting enzyme (ACE)
inhibitor, and angiotensin II receptor blocker seem to
be able to reduce either the progression of the aortic
dilation or the occurrence of complications.
30. Open vs. EVAR
• Open Surgical Repair
– Longer Recovery Time
– Longer Hospital Stay
– 90% Long Term Success
– Younger patients typically
• EVAR
– Shorter length of stay
– Reduction in blood loss
– Reduction in OR Time
– ICU utilization reduced
– Reduced 30 d
morbidity/mortality
– Older patients typically
– Needs long-term follow-up
– May need secondary procedures
for endoleaks
31. EVAR
• EVAR is performed by retrograde transarterial
advancement of a large delivery device (up to 24 F) carrying
the collapsed self-expandable stent-graft.
• Either TOE or IVUS can be helpful in identifying the correct
position of the guide wire within the TL.
• When the target position is reached, the blood pressure is
reduced—either pharmacologically (nitroprusside or
adenosine, ,80 mm Hg systolic) or using rapid right
ventricular pacing—to avoid downstream displacement,
and the stent-graft is then deployed.
• Completion angiography is performed to detect any
proximal Type I endoleak (an insufficient proximal seal),
which usually mandates immediate treatment.
32.
33.
34. Abdominal aortic aneurysm
• It is defined by increase in size > 3 cm
• Most common form of aortic aneurysm
• Infra-renal 80%
• M : F - 5:1
38. Diagnosis and sizing
• Abdominal ultrasound have high accuracy and
a sensitivity and specificity of almost 100% in
detecting AAA.
• It is prefered over CT in screening.
• Many recommend use of ultrasound for f/u of
small AAA and CT/ MRI for larger AAA.
39. Natural history
• Average rate of expansion is 0.2 to 0.3 cm/year
• 1 year risk of rupture –
• 10-20% for aaa 6-7 cm
• 20-40% for aaa 7-8 cm
• 30-50% for aaa > 8 cm
• 5 year risk of rupture –
• 5% for 3-4 cm
• 10-20% for 4-5.5 cm
• 30-40% for 5.5-6.0 cm
• >80% for > 7 cm
41. Abdominal endovascular aortic repair
• Endovascular aortic repair is performed to prevent infrarenal AAA
rupture.
• Similarly to TEVAR, careful pre-procedural planning by contrast-
enhanced CT is essential.
• The proximal aortic neck (defined as the normal aortic segment
between the lowest renal artery and the most cephalad extent of
the aneurysm) should have a length of at least 10–15 mm and
should not exceed 32 mmin diameter.
• Angulation above 60 degree of the proximal neck increases the risk
of device migration and endoleak.
• The ilio-femoral axis has to be evaluated by CT, since large delivery
devices (14–24 F) are being used.
42. • Currently several stent-grafts are available, mostly
comprising a self-expanding nitinol skeleton covered
with a polyester or polytetrafluroethylene membrane.
• To provide an optimal seal, the stent-graft diameter
should be oversized by 10–20% according to the aortic
diameter at the proximal neck.
• Bifurcated stent-grafts are used in most cases; tube
grafts may only be used in patients with localized
pseudoaneurysms of the infrarenal aorta.
43. Evaluation for EVAR
Contraindications for EVAR
Short of proximal neck
Thrombus present in proximal landing zone
Conical proximal neck
Greater than 120º angulations of the proximal
neck
Critical inferior mesenteric artery
Significant iliac occlusion
Torture of iliac vessels
46. Classification of Endoleaks
I: Attachment site leaks
A. Proximal end of endograft
B. Distal end of endograft
C. Iliac occluder ( plug )
II. Branch leaks ( without attachment side connection )
A. Simple or to-and-fro (from only 1 patient branch)
B. Complex or flow-through ( with 2 or more patient branches).
III. Graft defect
A. Junction leak or modulator disconnect
B. Fabric disruption ( midgraft hole )
IV. Graft wall ( fabric ) porosity ( <30 days after graft placement )
47.
48.
49.
50.
51. Surgery
• Ascending aorta
• Themain principle of surgery for ascending aortic
aneurysms is that of preventing the risk of dissection or
rupture by restoring the normal dimension of the
ascending aorta.
• If the aneurysm is proximally limited to the sinotubular
junction and distally to the aortic arch, resection of the
aneurysm and supra-commissural implantation of a
tubular graft is performed under a short period of
aortic clamping, with the distal anastomosis just below
the aortic arch.
52. • If the aneurysm extends proximally below the
sinotubular junction and one or more aortic
sinuses are dilated, the surgical repair is guided
by the extent of involvement of the aortic
annulus and the aortic valve.
• Surgical mortality for isolated elective
replacement of the ascending aorta (including
the aortic root) ranges from 1.6–4.8% and is
dependent largely on age and other well-known
cardiovascular risk factors at the time of
operation.
53. • Descending aorta
• The surgical approach to the descending aorta is
a left thoracotomy between the fourth and
seventh intercostal spaces, depending on the
extension of the aortic pathology .
• Established methods for operation of the
descending aorta include the left heart bypass
technique, the partial bypass, and the operation
in deep hypothermic circulatory arrest.
54. • Thoraco-abdominal aorta
• When the disease affects both the descending thoracic
and abdominal aorta, the surgical approach is a left
thoracotomy extended to paramedian laparotomy.
• Therisk of paraplegia after thoraco-abdominal repair is
in the range of 6–8%.
• Measures to reduce this include permissive systemic
hypothermia (34degree C), reattachment of distal
intercostal arteries between T8 and L1, and the pre-
operative placement of cerebrospinal fluid drainage.
55. • Abdominal aorta
• Open abdominal aortic repair usually involves a
standardmedian laparotomy, but may also be
performed through a left retroperitoneal approach.
• The aneurysmal aorta is replaced either by a tube or
bifurcated graft, according to the extent of aneurysmal
disease into the iliac arteries.
• Theexcluded aneurysmis not resected, but is closed
over the graft, which has a haemostatic effect and
ensures that the duodenum is not in contact with the
graft, as this may lead to erosion and a possible
subsequent aorto-enteric fistula.
56.
57. EVAR VS OSR
• For a subset of AAA patients, all being
anatomically and physiologically eligible for
both conventional EVAR and open repair, a
head-to-head comparison of the two
techniques was prompted
58. • In individuals considered fit for conventional surgery, EVAR
was associated with lower short-term mortality than OSR.
• All-cause mortality with EVAR was significantly lower than
that with OSR in the short term, with the benefit
disappearing in the intermediate and long term.
• Operative complications, QoL and sexual dysfunction were
generally comparable between EVAR and OSR.
• However, there was a slightly higher incidence of
pulmonary complications in the OSR group compared with
the EVAR group.
59. • EVAR was associated with a higher reintervention rate than
OSR.
• Most reinterventions with EVAR, however, were catheter-
based interventions associated with low mortality.
• In individuals considered unfit for open surgery, the results
of a single trial found no short- or long-term benefits of
EVAR over no intervention with regard to all-cause
mortality, but individual outcomes may differ and individual
preferences should always be taken into account.
65. Recommendation for Medical Treatment
of Patients With Thoracic Aortic Diseases
• Class I
• Stringent control of hypertension, lipid profile
optimization, smoking cessation, and other
atherosclerosis risk-reduction measures should
be instituted for patients with small aneurysms
not requiring surgery, as well as for patients who
are not considered surgical or stent graft
candidates. (LOE: C)
66. Recommendations for Asymptomatic
Patients With Ascending Aortic Aneurysm
• Class I
• 1. Asymptomatic patients with degenerative thoracic aneurysm,
chronic aortic dissection, intramural hematoma, penetrating
atherosclerotic ulcer, mycotic aneurysm, or pseudoaneurysm, who
are otherwise suitable candidates and for whom the ascending
aorta or aortic sinus diameter is 5.5 cm or greater should be
evaluated for surgical repair. (LOE: C)
• 2. Patients with Marfan syndrome or other genetically mediated
disorders (vascular Ehlers- Danlos syndrome, Turner syndrome,
bicuspid aortic valve, or familial thoracic aortic aneurysm and
dissection) should undergo elective operation at smaller diameters
(4.0 to 5.0 cm depending on the condition) to avoid acute
dissection or rupture. (LOE: C)
67. • 3. Patients with a growth rate of more than
0.5 cm/y in an aorta that is less than 5.5 cm in
diameter should be considered for operation.
(LOE: C)
• 4. Patients undergoing aortic valve repair or
replacement and who have an ascending
aorta or aortic root of greater than 4.5 cm
should be considered for concomitant repair
of the aortic root or replacement of the
ascending aorta. (LOE: C)
68. • Class IIa
• 1. Elective aortic replacement is reasonable for patients with
Marfan syndrome, other genetic diseases, or bicuspid aortic valves,
when the ratio of maximal ascending or aortic root area (Π r2) in
cm2 divided by the patient’s height in meters exceeds 10. (LOE: C)
• 2. It is reasonable for patients with Loeys-Dietz syndrome or a
confirmed TGFBR1 or TGFBR2 mutation to undergo aortic repair
when the aortic diameter reaches 4.2 cm or greater by
transesophageal echocardiogram (internal diameter) or 4.4 to 4.6
cm or greater by computed tomographic imaging and/or magnetic
resonance imaging (external diameter). (LOE: C)
69. Recommendation for Symptomatic Patients With
Thoracic Aortic Aneurysm
• Class I
• 1. Patients with symptoms suggestive of
expansion of a thoracic aneurysm should be
evaluated for prompt surgical intervention
unless life expectancy from comorbid
conditions is limited or quality of life is
substantially impaired. (LOE: C)
70. Recommendations for Aortic Arch
Aneurysms
• Class IIa
• 1. For thoracic aortic aneurysms also involving the proximal
aortic arch, partial arch replacement together with ascending
aorta repair using right subclavian/ axillary artery inflow and
hypothermic circulatory arrest is reasonable. (LOE: B)
• 2. Replacement of the entire aortic arch is reasonable for acute
dissection when the arch is aneurysmal or there is extensive
aortic arch destruction and leakage. (LOE: B)
• 3. Replacement of the entire aortic arch is reasonable for
aneurysms of the entire arch, for chronic dissection when the
arch is enlarged, and for distal arch aneurysms that also involve
the proximal descending thoracic aorta. (LOE: B)
71. • 4.For patients with low operative risk in whom an isolated
degenerative or atherosclerotic aneurysm of the aortic arch is
present, operative treatment is reasonable for asymptomatic
patients when the diameter of the arch exceeds 5.5 cm. (LOE: B)
• 5. For patients with isolated aortic arch aneurysms less than 4.0 cm
in diameter, it is reasonable to reimage using computed
tomographic imaging or magnetic resonance imaging, at 12-month
intervals, to detect enlargement of the aneurysm. (LOE: C)
• 6. For patients with isolated aortic arch aneurysms 4.0 cm or
greater in diameter, it is reasonable to reimage using computed
tomographic imaging or magnetic resonance imaging, at 6-month
intervals, to detect enlargement of the aneurysm. (LOE: C)
72. Recommendations for Descending Thoracic Aorta and
Thoraco-abdominal Aortic Aneurysms
• Class I
• 1. For patients with chronic dissection, particularly if
associated with a connective tissue disorder, but
without significant comorbid disease, and a descending
thoracic aortic diameter exceeding 5.5 cm, open
repair is recommended. (LOE: B)
• 2. For patients with degenerative or traumatic
aneurysms of the descending thoracic aorta exceeding
5.5 cm, saccular aneurysms, or postoperative
pseudoaneurysms, endovascular stent grafting should
be strongly considered when feasible. (LOE: B)
73. • 3. For patients with thoracoabdominal aneurysms, in
whom endovascular stent graft options are limited and
surgical morbidity is elevated, elective surgery is
recommended if the aortic diameter exceeds 6.0 cm,
or less if a connective tissue disorder such as Marfan or
Loeys-Dietz syndrome is present. (LOE: C)
• 4. For patients with thoracoabdominal aneurysms and
with end-organ ischemia or significant stenosis from
atherosclerotic visceral artery disease, an additional
revascularization procedure is recommended. (LOE: B)
75. Advances in Diagnosis and
Treatment Envisioned for the Near Future
• One may fairly expect to see the following major
advances in diagnosis and treatment of aortic
diseases in the relatively near future:
• Population screening will be improved, first by
general recognition in the medical community of
the familial patterns of aortic disease and then by
novel (genetic) mass screening techniques.
• • Selection criteria for surgical intervention will
go beyond symptoms and size.
76. • We anticipate that the following modalities may be
applied:
• Biomarkers that indicate impending rupture or dissection
may come into play (including potential RNA expression
indexes).
• Mechanical properties of the aorta (distensibility and wall
tension) may be assessed noninvasively and applied as
intervention criteria.
• Imaging modalities (including positron emission
tomography) may be found to be predictive of aneurysm
“activity” and guide timing of surgery.
77. • • Stent therapies may advance to achieve truly
durable results (in contradistinction to currently
disappointing lack of effectiveness in preventing
death or rupture).
• This may require shifts in the design of
endovascular prostheses.
• • Genetic elucidation of these diseases will
advance even further, permitting enhanced
understanding of the pathophysiology of
aneurysm disease and improved diagnosis.
•
78. • Understanding of genetic alterations resulting in aneurysms
may suggest avenues to pharmacologic therapy (with
conventional drugs designed to shortcircuit the mechanism
of aneurysm formation and progression).
• In particular, we look forward to seeing whether the
angiotensin receptor blocker drug losartan meets its high
expectations.
• Understanding of genetic alterations may ultimately permit
gene therapy in children or adults to prevent the
development or progression of aortic diseases.
