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Acute Aortic Syndrome

last updated: October 26, 2016

Acute Aortic Syndrome types:​

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  • penetrating atherosclerotic ulcer

    • occurs predominantly in descending aorta​

    • atheromatous plaques ulcerate and disrupt the internal elastic lamina

    • 4.6% of aortic dissections 

    • risk factors: elderly (average 72 yrs old), males (70%), HTN (95%), COPD (24%), smoking (77%)

    • concomitant abdominal aortic aneurysm found in 61% of patients

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  • intramural hematoma

    • rupture of the vaso vasorum​

    • hemorrhage within aortic media

    • cause result in aortic dissection or rupture

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  • aortic dissection

    • intimal tear causing intima, medial or adventitial separation​

    • seen in cystic medial necrosis or cystic medial degeneration

      • autosomal dominant disorder of large arteries​

      • associated with Marfan syndrome and massive baclofen overdose as well as other hereditary connective tissue disorders

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  • aortic aneurysm leak and rupture

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  • traumatic aortic transection

Pathophysiology:

The pathology of aortic dissection is a primary intimal tear that allows blood to enter the aortic media, extending proximally and distally into the aortic wall and displacing the intima inward. This entry tear typically occurs at sites of greatest wall tension, notably within a few centimeters of the aortic valve or close to the attachment site of the ligamentum arteriosum. The intima and inner part of the aortic media form the intimomedial flap, and the outer part of the aortic media and adventitia form the outer boundary of the false lumen (also known as a false channel). The true lumen is directly connected to the lumen of the unaffected aorta and usually experiences high-velocity flow. The false lumen communicates with the true lumen through the intimal tear and experiences slower, turbulent blood flow. Re-entry tears are usually present in the intima, creating additional communication between the true and false lumens in the distal aorta. 

Risk Factors:

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Hypertension

  • adds to the mechanical strains and shearing forces along the aortic wall

  • long-standing hypertension is also associated with increased stiffness of the aortic media, which may introduce additional interlaminar shearing stresses and further contribute to the development of aortic dissection

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Atherosclerotic disease

  • through the development of a penetrating atherosclerotic ulcer 

  • However, atherosclerosis is not a typical cause of aortic dissection. Dissection in patients with severe atherosclerosis tends to be limited by fibrosis and calcification, but the relationship between an atheroma and the location of aortic dissection is not clear in most patients

 

connective tissue disorders

  • Marfan syndrome

  • Ehlers-Danlos syndrome

 

bicuspid aortic valve

 

aortitis

 

aortic coarctation

 

iatrogenically

  • aortic surgery

  • catheterization

  • placement of intra-aortic balloon pumps

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