L18 Flashcards
3 aortic layers
Intima - biologically active, most internal
Media
Adventitia
Where is collagen in arteries?
Adventitia
Lifelong synthesis and degradation of collagen
Where is elastin in arteries?
Media
Little synthesis after childhood
What is the structure of the proximal aorta?
More elastin
What is the structure of the distal/descending aorta?
Collagen - more stiff
Where most rupture and aneurysms
What collagen diseases would increase likelihood of aneurysm?
Marfan’s - mutate type 2 collagen
Ehlers-Danlos - type 4 collagen
How do MMPs contribute to aneurysm?
= enzymes that degrade ECM
Activate MMPs - increase aneurysm formation
What are the 2 types of dilation?
Ectasia = aortia gets bigger Fusiform - uniform dilation - More predictable Saccular - focal weakness, out-pouching - More dangerous b/c less predictable
What is the normal diameter of the aorta?
2-3 cm
What is the main difference between dilating and constricting disease of the aorta?
Dilating progresses to rupture, hemorrhage or death
Constricting (atherosclerosis) can cause ischemia
Exs of causes of dilated aortas
HTN Bicuspid aortic valve Congenital - Marfan, ED Injury - dissection, intramural hematoma, trauma tearing tether Infection - 3ary syphilis
Where do most aneurysms occur?
Below renal arteries
Do aneurysms every decrease in size?
NO
Always increasing
Risk of rupture proportional to diameter
What type of rupture is most common?
Retroperitoneal rupture b/c aorta is retroperitoneal
What determines the need for surgical treatment of aneurysm?
Rupture rate higher than risk of doing nothing
Larger than 5cm
