Aortic dissection ppt

1. AORTIC DISSECTION
● Spontaneous longitudinal separation of aortic intima and adventitia by
circulating blood having gained access to and splittingnthe media and aortic
wall.
● M/c acute emergency condition of aorta
● Incidence: 3/ 1000
● Peak age: 60 years (M:F= 3:1)

2. RISK FACTORS:
● Fusiform aneurysms
● Does not occur in aneurysm less than 5 cm
● Hypertension
● Atherosclerosis of aorta
● Marfans syndrome
● Turners syndrome
● Osteogenesis imperfecta
● Prosthetic valve/. Other cardiovascular procedures
● Corticosteroids
● Family h/o dissection and previous h/o aneurysm

3. ● Acute aortic dissection (AAD) is the prototype and most common of the acute aortic syndromes (AASs),
which include intramural hematoma (IMH), limited intimal tear (LIT), penetrating atherosclerotic ulcer
(PAU), traumatic or iatrogenic aortic dissection, and leaking or ruptured aortic aneurysm.
● This group of diverse diseases affects the aortic wall and is predisposed by underlying abnormalities of the
media or intima or by trauma and instrumentation. They share the clinical manifestation of intense chest or
back pain, which is usually sudden in onset and can extend to the abdomen and pelvis.
● Diagnostic imaging is essential to rapidly confirm and accurately diagnose the type, magnitude, and
complications of AAS

4. Pathophysiology
• Acute aortic dissection (AAD) affects the aortic wall and is commonly initiated
by a tear in the intima, which separates the aortic wall layers in an uneven
fashion.
• It typically dissects along the medial layer plane, creating an intimal-medial
complex that is commonly seen as an endoluminal filling defect flap at
imaging.
• The exact acute dissection plane extension and consequences—including
aortic rupture, side-branch dissection, and organ malperfusion—are unstable
and unpredictable, especially when it involves the ascending aorta (from the
root to the proximal origin of the brachiocephalic artery), primarily owing to
the ascending aorta’s microstructure, local hemodynamics, and mobility
accelerating the immediate rate of complications.
• The aorta becomes relatively immobile in the descending segment,
beginning at the level of the ductus arteriosus (white arrowhead).
Involvement of only the aortic arch or the descending aorta alone has a lower
rate of immediate complications. Nonspecific physiologic reactions include
effusions and fluid collections (blue area indicated by black arrowheads and
yellow area within the pericardial sac)

5. Classification
• Anatomic classification of aortic dissections. The Stanford system classifies lesions as type A if the ascending aorta is involved,
anywhere from the root to the proximal origin of the brachiocephalic artery. All other lesions are considered Stanford type B. The
DeBakey system classifies lesions on the basis of the location of the initiating intimal tear and the pattern of extension.
• DeBakey type I and II lesions involve the ascending aorta, with type II lesion involvement limited to the ascending aorta. DeBakey
type III lesions are subdivided into type IIIa if the lesion involves only the descending aorta and extension is limited to above the
diaphragm and type IIIb if the lesion involves only the descending aorta but extends to below the diaphragm. STJ = sinotubular
junction.

6. Diagnostic and Prognostic CT Findings in Acute Aortic Syndromes (AASs)

7. Findings Comments

8. Imaging features:
True lumen • Usually smaller and oval/ semiround
• In continuity with the undissected portions of aorta
• Higher conscentration of contrast
False lumen Specific cobweb sign- slender linear areas of low
attenuation = residual ribbons of media
Beak sign- wedge of hematoma creating space for
propogation of false lumen in cross sectional imaging

9. Diagnostic imaging
● Diagnostic imaging is essential to rapidly confirm and accurately diagnose the type, magnitude,
and complications of AAS.
● Whenever AAS is suspected, noncontrast CT from the base of the neck to below the lesser
trochanters is needed to image the entire aorta, the proximal segments of the arch branches, and
the proximal segments of the iliofemoral arteries, Followed by postcontrast imaging in the
arterial phase with the same precontrast anatomic coverage.
● electrocardiographically gated imaging of the thoracic aorta and heart in the arterial phase is
recommended for comprehensive evaluation and minimizing cardiac and pulsation motion
artifact

10. a. Coronal CT angiogram at the ascending aorta level shows an acute Stanford type A aortic lesion with dissection flap
extending from the aortic root (black arrowhead) to the aortic arch, There is a large and circumferential adventitial
hematoma compressing the main pulmonary artery (white arrowhead) and extending to the central pulmonary arteries
b. Axial noncontrast CT image at the mid–ascending aorta level shows crescentic near-circumferential hyperattenuation
of the ascending aorta (white arrowhead) and descending aorta at the same level, which is consistent with IMH. The
IMH in the descending aorta displaces an intimal calcified atherosclerotic plaque (black arrowhead) into the aortic
lumen, compared with a normally positioned calcified plaque in the noninvolved aortic wall at the same level.

11. c. Axial oblique CT angiogram at the level of the proximal ascending aorta shows a large but focal area of
outward-ballooning aortic wall (arrowhead) arising near the sinotubular junction with mass effect on the left
atrium – LIT.
d. Axial CT angiogram at the level of the hiatus shows a localized area of aortic wall
thickening (arrowhead) and ulcerlike remodeling, consistent with a PAU

13. a. Axial CT angiogram at the level of the carina shows a complex acute aortic injury (white
arrowhead) at the level of the ductus arteriosus, with pseudoaneurysms and a posterior
descending aortic rupture with slow-flow active extravasation (arrow) and hemothorax.

14. CT angiogram shows an acute type A
dissection (black arrowhead) from the
aortic root to the distal arch with a
dissection flap and an intimal tear in
the LSA (white arrowhead), which
had been accessed for the
endovascular AAA repair.
CT angiogram approximately 12 hours
after endovascular repair of the LSA tear
shows markedly decreased size of the
false lumen in the ascending aorta
(black arrowhead) and a well expanded
LSA stent (white arrowhead) without
evidence of a residual flap or tear.

15. a & c. Stanford type A AAD
b & d. Stanford type B AAD

16. Spectrum of AAD lumina and dissection flaps showing 1–7 and 8–14 show variable morphologies seen in AAD with
variable size and caliber of the false and true lumina. The prognostic impact may relate to increasing complexity of
dissection along the continuum (long black arrow), the presence of thrombus in the false lumen, and the extent of
dissected intima circumference.

18. Axial CT angiogram at the level of the carina shows a ruptured
descending aortic aneurysm (black arrowhead) with a large periaortic
hematoma and clotting areas of left hemothorax (white arrowheads).

19. Volume-rendered image shows the relation of the true and false lumina, the dissection
plane (top two arrowheads), complications such as marked hypoperfusion of the left kidney (white
oval), and termination of the dissection at the iliofemoral arteries (arrowhead in insets).

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21. Longitudinal progression imaging changes in aortic dissection