MHD: Vascular disease Flashcards
What are the layers of the vascular wall from inside-out?
Intima, media, adventitia
Where are elastic lamina found in the vascular wall?
The IEL is found interior to the media layer and the EEL is found exterior to the media layer
What is the vaso vasorum?
Small vessels that provide oxygen to the vessel wall. Particularly important in large vessels.
What is the vascular response to injury?
Intimal thickening
Describe the mechanism of intimal thickening?
Smooth muscle cells enter intima, mitose to expand intimal layer.
Extracellular matrix production also increases
What is the general definition of arteriosclerosis?
Hardening of the arteries due to thickening and loss of elasticity
What are the morphologic variants of arteriosclerosis?
Atherosclerosis
Monckeberg’s medial calcific sclerosis
Arteriosclerosis (due to hypertension)
What vessels are mainly affected by atherosclerosis?
Large elastic arteries (aorta, carotid, iliac) and muscular arteries (coronary, popliteal)
What are the major risk factors for atherosclerosis
Non-modifiable: genetic, family history, age, male gender
Modifiable: hyperlipidemia, hypertension, cigarette smoking, diabetes mellitus, inflammation
What is the definition of atherosclerosis?
Chronic inflammatory response of the arterial wall to endothelial injury
What is an atheroma?
accumulation of degenerative material (cell debris, cholesterol crystals, foam cells, calcium) in the tunica intima with a fibrous cap
Describe the morphology of an atheroma
Atheromas only effect part of the circumference of the vessel wall, leading to decreased medial thickness and ischemia
What complications are associated with atheroma/plaque formation?
Rupture/ulceration/erosion Emobli Hemorrhage Weakened media --> aneurysm Calcification Thrombosis
On histology, how do you identify an atherosclerotic embolus?
Cholesterol crystals appear like white needles on histological slides
What are the clinical complications associated with atherosclerosis?
MI, cerebral ischemia, peripheral vascular disease, aneurysms
Describe the pathogenesis of Monckeberg’s medial calcific sclerosis
Calcific depositions form in the tunica media
Vessels are not obstructed, so lumenal size is preserved
What is hyaline arteriolosclerosis?
Hypertension induced sclerosis of the arterioles often seen in brain and kidneys
-Seen as homogenous pink thickening of vessels with lumenal narrowing
What is hyperplastic arteriolosclerosis?
Due to severe acute hypertension
Gives onion skin appearance of vessels due to smooth muscle cells with reduplicated membranes. Lumens narrow progressively.
What is an aneurysm?
Localized abnormal dilatation of a blood vessel
What is the difference between a true (saccular) aneurysm and a false aneurysm?
A true aneurysm involves the outpouching of a vessel wall whereas a false aneurysm is caused by a ruptured vessel wall leading to a hematoma
What is a dissection?
A tear in the tunica intima leads to blood flowing into the media splaying apart layers to form a blood filled channel
What genetic conditions are associated with increased risk for aneurysms due to poor intrinsic quality of vascular wall connective tissue?
Marfan syndrome (fibrillin defect) Ehlers Danlos (type III collagen defect)
What conditions can cause ischemia leading to increased risk for aneurysm?
Atherosclerosis, hypertension, syphillis
What is cystic medial degeneration?
Degradation of the elastin found within the tunica media and loss of smooth muscle cells
What enzymes play a key role in the formation of abdominal aortic aneurysms?
Matrix metalloproteinases
What is the classical location of an AAA?
Between the renal arteries and the aortic bifurcation
How does diameter of AAA influence the risk of rupture?
Rupture risk increases with increasing diameter. There is a 25% chance of rupture per year with a diameter > 6cm
What are the causes of an aortic dissection?
Hypertension, connective tissue disorders, bicuspid aortic valves
What are the two classifications of aortic dissection?
A: in the Ascending (proximal) aorta
B: in the Bottom (descending) aorta
Which type of aortic dissection is more serious?
Type A is more serious than B, usually requires surgical treatment
What is vasculitis?
Inflammation of blood vessels
Can be due to infectious pathogen or immune-mediated
