AORTA
ANATOMY
ACUTE AORTIC SYNDROME
AO DISSECTION (AoD)
Presence of tear in intima that results in separation of layers of media and allows blood to flow through the false lumen. This separate or false lumen for blood flow is externally bound only by the outer third of the media and adventitia.
INTRAMURAL HEMATOMA (IMH)
No identifieable direct communication b/n ture and false lumen. characterized by a hyperdense crescent shaped hemorrhage w/n the aortic wall best seen on NECT.
Mechanism: spontaneous rupture of the vasavasorum -> bleeding and hematoma formation w/n aortic wall
IMH can coexist with and progress to AoD
Report the maximal thickness of the aorta in region of IMH
PENETRATING ATHEROSCLEROTIC ULCER (PAU)
Atherosclerotic lesion that penetrates the internal elastic lamina of the Ao wall. 20% of PAUs have no associated IMH presumably bc the medial fibrosis from chronic atherosclotic disease. Rupture risk is directly related to ulcer depth.
AORTIC DISSECTION
REPORTING STANDARDS
01 AORTIC DISSECTION STANDARD REPORTING.pdf
SVS/STS CLASSIFICATION
Location of entry tear determines whether type A or B
Type A: entry tear originates ONLY in zone 0. The distal extent is designated by zone.
Type A9 dissection = dissection w entry tear in zone 0 and extension into zone 9.
Type I: when entry tear origin is not identifiable it will remain indeterminate. These dissections always involve zone (I9).
Type B: any aortic dissection w an entry tear originating in zone 1 or beyond. Type B dissections are further characterized by two subscripts Bp,d (p = proximal zone of involved aorta, d describes distal zone of involved aorta.
B1,9 dissection = proximal involvement of zone 1 and distal extension to zone 9. The primary tear can be anywhere from 1 to 9.
B0,9 dissection = entry tear originated in non zone 0 but extended into zone 0.
Pts w hx of prior TA or type B dissection (repaired or unrepaired) presenting w a new acute dissection should be reported as follows: type of prior repair (if any) and current residual" anatomy.
Medically managed chronic state = acute on chronic Ad or Bp,d
Prior aortic surgery = residual acute on chronic Ad or Bp,d
"residual" infers that the patient has undergone prior surgery.
Complicated vs uncomplicated vs high risk
Uncomplicated: dissection w no evidence of rupture or end-organ malperfusion. Further distinguished by absence of high risk features.
Complicated
CHRONICITY
As the dissection flap ages it becomes thicker and less compliant with a straightened appearance.
SURGICAL REPAIR
Grafts used in open surgical proximal thoracic aorta repairs can be used to replace Ao tissue only or be fashioned directly into a valvular prosthesis (mechanical or biosprosthetic). They are typically made of synthetic polyethylene and rarely homografts (donor tissue). Can also be used to reconstruct arch vessels.
Composite graft = surgical graft fashioned into a valvular prosthesis
Graft appearance:
NECT hyperattenuation compared to native aorta. Difficult to perceive at postcontrast due to blood pool.
Common mimics include circumferential calcification and relative hyperattenuation of the wall in comparison with blood pool in those w anemia.
Typically have smoothly curved morph9ology w straight configuration w accompanied angulations. OFten more redudant and can produce folds. Folds can simuate intimomedial flap on axial images.
Lack normal anatomic landmarks. When used for aortic root repair, almost all grafts are straight and eliminate waist of the sinotubular junction or normal sinuses of Valsalva. When extending to the aortic valve plane
Open surgical techniques:
Inclusion technique: method to control bleeding and prevent graft leaking
The native aorta is incised and then sutured around the graft creating a perigraft potential space b/n the native aorta and graft material.
Accumulation of blood/fluid in the perigraft space can produce tension at anastomosis and increase risk of pseudoaneurysm. This space is typically NOT seen unless the native aorta is calcified.
Interposition technique:
Diseased aorta is excised and replaced with an interposition graft. Though the technique does not specifically create a potential space, they can occur due to residual aortic tissue, adhesions or resolved hematoma.
Carotid-carotid and L carotid-subclavian grafts (LCSG) can be fashioned to connect arch vessels together in a sequential configuration.
LCSG are often accompanied by occlusion of the proximal L subclavian artery origin to rpevent endoleaks which can be performed surgically or more often endovascularly w placement of vascular occluder/plugs.
Occluding devices are disk or dumbell shaped hyperattenuating structures that work by promoting thrombogenesis.
Side-branch grafts: used for purposes of cardiopulmonary bypass cannulation. These grafts can be fastened to the aorta or more peripheral vessles (axilary, innominate, subclavian) when the aorta is not suitable. Can have variable configurations. Distal margins can be tapered or square and there is often suture material, felt, or clips at their apex to clsoe them.
03 POSTOP REPAIR OF ASCENDING AORTA AND AA.pdf02 Ao DISSECTION AND OTHER Ao SYNDROMES ACUTE TO CHRONIC.pdfRSNA CTA OF ACUTE Ao PATH CONDITIONS.pdf