Aortic Dissection

Posted by e-Medical PPT Wednesday, November 14, 2012
Incidence of 1 in 2000 in US
• Early mortality of 1%/hour for proximal
dissection
• Two theories of formation
– Breach of intimal layer of aorta allows blood to
encroach on a diseased medial layer, creating a false
lumen and intimal flap.
– Rupture of vasa vasorum in medial layer causes local
hematoma causing dissection; no flap is formed. 13%
of autopsy cases cannot identify flap.

Etiology
Medial degeneration
– Chief cause of atraumatic dissections
– Marfan syndrome
• 5-9% of all aortic dissections
• Dissections occur at a young age
• Thoracic aortic aneurysms
• Proximal aortic dissections
– Ehlor’s-Danlos syndrome
– Familial aortic aneurysm
• Mutation of fibrillin-1 gene with loss of elastic fibers
– Nonclassic degeneration associate with age,
hypertension

Peak incidence age 60’s to 70’s
• M:F 2:1
• 72-80% with preexisting hypertension
• Bicuspid aortic valve found in 7-14% of all aortic
dissections
• Associated with Noonan, Turner syndromes
• Vasculitis, especially giant cell
• Reports describe association with cocaine in
young men

Pregnancy and Aortic Dissection
Of aortic dissections in women <40, half
are during pregnancy
• Generally in the third trimester
• Some in postpartum
• Marfan syndrome poses special risk
• Uncertain causality; not fully explained by
increases in BP, CO, blood volume
• Possible reporting bias

Symptoms
Common Manifestations
• Severe “tearing” pain, usually sudden onset
• Migratory pain described in 17% of cases
• Location
– Ascending aorta
• Anterior pain involves ascending aorta in 90% of cases
• Neck, throat, jaw, face
– Descending aorta
• Interscapular pain involves descending aorta in 90% of cases
• Back, abdomen, lower extremity pain

Uncommon Manifestations
• Syncope (9%)
• Congestive heart failure (7%)
– Due to acute aortic regurgitation
• CVA (5%)
• Peripheral neuropathy
• Paraplegia
• Sudden death
• Tamponade (hemopericardium due to rupture)

Dissection Extension
Proximal dissection involves coronary
artery in 1-2% of cases
– Most commonly flap involves right coronary
ostium, causing inferior infarct
– Chest xray may not be sufficient to rule out
dissection
• Distal dissection can extend
– 5-8% of cases involve renal artery
– 3-5% involve mesenteric ischemia/infarction
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