Notes on Aortic Pathology Flashcards
Hypothesis regarding the mechanism of development of aortic dissection :
“1.Genetic predisposition. A genetic diathesis sets the stage for development of an aortic aneurysm or dissection.
2.Medial degeneration. Genetic predisposition results in activation of mechanisms of inflammation, injury to the medial layer of the aorta, loss of smooth muscle cells, and histologic damage by cytokines. As a result, the aortic wall is injured and weakened.
3.Aneurysm formation. The injured aortic wall dilates and an aneurysm is formed. Such dilatation causes excess mechanical stress on the aortic wall.
4.Hypertensive episode. At a moment of extreme exertion or emotion, a spike in blood pressure leads the aortic wall stress to exceed the tensile strength of the aortic tissue.
5.Aortic dissection. The aorta dissects (and/or ruptures). We know from laboratory studies in which we iatrogenically create aortic dissection that dissection occurs and propagates in a split section [11].”
Aortic Landing Zones
Describe Landing Zone 0
Zone 0 (involves the ascending to distal end of the origin of the innominate artery)
Aortic Landing Zones
Describe Landing Zone 1
Zone 1 (involves the origin of the left common carotid; between the innominate and the left carotid)
Aortic Landing Zones
Describe Landing Zone 2
Zone 2 (involves the origin of the left subclavian; between the left carotid and the left subclavian)
Aortic Landing Zones
Describe Landing Zone 3
Zone 3 (involves the proximal descending thoracic aorta down to the T4 vertebral body; the first 2 cm distal to the left subclavian);
Aortic Landing Zones
Describe Landing Zone 4
Zone 4 (the end of zone 3 to the mid-descending aorta – T6)
Aortic Landing Zones
Describe Landing Zone 5
Zone 5 (the mid-descending aorta to the celiac);
Aortic Dissection By Chronicity
- Hyperacute
- Acute
- Subacute
- Chronic
DeBakey Classification
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Type I: Dissection tear originates in the ascending aorta and propagates distally to include the aortic arch and typically the descending aorta
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Type II: Dissection tear is confined only to the ascending aorta
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Type III: Dissection tear originates in the descending thoracic aorta and propagates most often distally
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Type IIIa: Dissection tear is confined only to the descending thoracic aorta
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Type IIIb: Dissection tear originates in the descending thoracic aorta and extends below the diaphragm
Stanford Classification
- Type A: All dissections involving the ascending aorta, irrespective of the site of the intimal tear
- Type B: All dissections that do not involve the ascending aorta (including dissections that involve the aortic arch but spare the ascending aorta)
Suggested imaging surveillance of asymptomatic thoracic aortic aneurysms
- Initial discovery of aneurysm
- Degenerative aneurysm
- Marfan, BAV, Familial
- Loeys-Dietz syndrome
Crawford classification of TAA
Extent 1-5
- Extent I, below the left subclavian to above the celiac axis or opposite the superior mesenteric and above the renal arteries;
- Extent II, below the left subclavian and including the infrarenal abdominal aorta to the level of the aortic bifurcation;
- Extent III, below T6 intercostal space, tapering to just above the infrarenal abdominal aorta to the iliac bifurcation; and
- Extent IV, below T12, tapering to above the iliac bifurcation. Safi et al1 proposed expanding the classification with the addition of
- Extent V, below T6, tapering to just above the renal arteries.
Classification of Endoleaks
Endoleaks are classified by 5 types:
* Type Ia, proximal attachment site endoleak; Type Ib, distal attachment site endoleak;
* Type II, backfilling of the aneurysm sac through branch vessels of the aorta;
* Type III, graft defect or component misalignment;
* Type IV, leakage through the graft wall attributable to endograft porosity; and
* Type V, caused by “endotension,” possibly resulting from aortic pressure transmitted through the graft/thrombus to the aneurysm sac.
Mgmt of Type A and type B Aortic dissections
“A straightforward management approach is suggested in the current guidelines based on whether the AD involves the ascending aorta or not.
- Namely, type A AD is treated by emergent surgery
- while type B AD is managed medically; surgery is reserved for if complications arise.
Complications of Aortic Dissection are defined as:
- (1) failure of medical therapy to control pain or hypertension,
- (2) expanding aortic diameter,
- (3) extension of AD,
- (4) impending or actual rupture, and
- (5) malperfusion syndrome
Acute Type B Aortic Dissection with Arch Extension
Management:
* Uncomplicated
- In summary, uncomplicated cases are managed with medical therapy
“Similar to patients without arch extension, 70% of patients with arch involvement were managed with medical therapy only. Early morality rates were almost identical regardless of involvement of the arch as were long-term mortality even after the adjustments ”
