Diseases of Aorta Flashcards
What are the layers of the aorta?
Intima, media, adventitia
Which layer of the aorta is the layer that provides strength?
Adventitia
What are the two major structural proteins of the aorta?
Collagen
Elastin
What layer contains most of the collagen?
Adventitia (layer of strength)
What layer contains most of the elastin?
Media
What happens to the ratio of collagen:elastin as you go down the aorta?
Collagen:elastin increases
What will happen with elastin digestion?
Decreased compliance
What will happen with collagen digestion?
Decreased tensile strength, increased rupture risk
What is the deficiency of Marfan’s syndrome?
Fibrillin
Can lead to dilating disease of aorta
What is the deficiency of Ehler-Danlos?
Collagen
Can lead to dilating disease of the aorta
What is the function of matrix metalloproteinases (MMPs)?
Cause extracellular matrix breakdown, can lead to aneurysms
What is a major source of matrix metalloproteinases (MMPs)?
Inflammatory cells Bacterial infection (hence why some bacterial infections can cause aneurysms) - Maybe could use doxycycline to stop aneurysm growing?
What does the term ‘cystic medial necrosis’ refer to?
The connective tissue degeneration seen in Marfan’s syndrome
Describe a fusiform dilation
Diffuse weakness, circumferential
Spindle shaped
Less chance of rupture due to uniformity
Usually due to cystic medial necrosis, Marfan’s, primary diseases of arterial components
Describe a saccular dilation
Focal weakness, asymmetric
Greater chance of rupture
Usually due to invasion of the arterial wall by inflammatory cells, infective or immune aortitis, mechanical injury
Describe an ectasia
Enlarged aorta, but not yet characterized as aneurysmal
What is the result of dilating disease?
Rupture, hemorrhaage, death
What is the result of constricting disease?
Ischemia
What are major causes of dilating disease of the aorta?
Congenital (Marfans, Ehlers-Danlos, etc.) "Nonspecific" aneurysm - multifactorial Injury - dissection Infection Unusual causes
What is the definition of an aortic aneurysm?
Dilation of an artery >1.5 times its normal diameter
Where do most aneurysms occur?
Infrarenal segment of aorta
What will occur over time to all aneurysms?
Will grow
And risk of rupture is proportional to aneurysm diameter
What are complications of aneurysms?
Rupture
Thrombosis
Embolization
Compression of adjacent structure
When should surgery be performed on aortic aneurysm?
Repair if AAA > 5.5 cm in diameter
What is the definition of a pseudoaneurysm?
Dilation does not involve all layers of the aorta
Essentially a hole in the aorta
What are the two types of pseudoaneurysms?
Penetrating aortic (atherosclerotic) ulcer Infection - "mycotic aneurysm" - mushroom shape
How does an aortic atherosclerotic ulcer form?
Intimal tear
Calcium deposit
Ulcer formation
What infectious organisms commonly cause mycotic aneurysms?
Salmonella
Syphillis
Describe the initial and secondary events of an aortic dissection
Initial - rupture of intima and media, forming a cleavage plane
Secondary even - propagation proximally and distally within the aorta
What are the Stanford type A and B aortic dissections and which is more common?
Type A - more common - involves ascending aorta, younger patients, high mortality
Type B - descending aorta, older patients, hypertension
What is a major complication of the dissection?
Can occlude branch arteries like renal artery
What occurs with a traumatic rupture?
Full thickness rupture with tamponade by periaortic tissues
What are principal consequences of constricting disease of the aorta?
Restricted arterial flow
Reduced organ perfusion
Infarction
Which layer of the aorta does atherosclerosis affect?
Intima
Where is atherosclerosis of the aorta more common?
Abdominal aorta»_space; thoracic aorta
In what patients population will you see aortic atherosclerosis?
Small female smokers
What are clues to abdominal aortic aneurysm?
Abdominal pain (radiates to back) Hypotension Mass in abdomen
