Vascular Pathology 1 - HTN Vascular Disease, Athero, Aneurysms, Dissection Flashcards
What layer do high pressure arteries have that low pressure veins don’t?
Internal elastic lamina
What is a berry aneurysm? What its rupture cause?
Found in Circle of Willis.
AD PCKD
Rupture = Fatal subarachnoid hemorrhage
What is an AV fistula?
artery»_space; vein.
Commonly due to a developmental defect. May lead to rupture and hemorrhage or to high-output cardiac failure.
What is fibromuscular dysplasia?
Focal thickening of intima and media of med-lg muscluar arteries. Results in stenosis.
What stimuli induce changes in endothelial cell function?
What is the ultimate result?
Stimuli: turbulent blood flow, HTN, complement, bacterial products, viruses, hypoxia, acidosis, tobacco smoke.
Leads to an ACTIVATED STATE
When stimuli are consistently present, the prolonged activated state can lead to ENDOTHELIAL DYSFUNCTION characterized by what three things?
1) Procoagulation
2) Proinflammation
3) Smooth muscle stimulation
What is the stereotypical response to vascular injury?
Intimal Thickening.
How does intimal thickening occur and what is a potential problem with intimal thickning?
Caused by smooth muscle cells from media migrating to the intima and elaborating ECM.
When intima is thickened, potentially AFFECTS BLOOD FLOW.
What are risk factors for essential HTN?
High sodium intake, obesity, stress, smoking, sedentary lifestyle
What normally causes secondary HTN?
Renal or endocrine disorder
What maintains blood volume and vascular tone?
RAS
*Know RAS, aldosterone, ANP function
What vascular morphologic changes occur in HTN?
Hyaline Arteriosclerosis
Hyperplastic Arteriosclerosis
Both result in lumen narrowing
What is Hyaline Arteriosclerosis?
Increased smooth muscle matrix synthesis.»_space;
» Plasma proteins leak across damaged endothelium.»_space;
» PINK (hyaline) thickening of vessel wall and associated lumen narrowing
What is Hyperplastic Arteriosclerosis?
Occurs in severe HTN.
Smooth muscles for concentric lamellations (ONION SKINNING) that result in lumen narrowing.
Onion skinning is associated with what?
The vascular morphologic change associated with Hyperplastic Arteriosclerosis during severe HTN.
What are the three constitutional risk factors associated with atherosclerosis?
Family hx
Age
Gender
What are the four major modifiable risk factors associated with atherosclerosis?
Hyperlipidemia (esp LDL) HTN Smoking DM (other: inflammation, hyperhomocystinemia, metabolic syndrome)
What is the pathogenesis of atherosclerosis?
Chronic injury to endothelium, leading to CHRONIC INFLAMMATION and repair of tissue.
What covers the necrotic core (cell debri, cholesterol crystals, foam cells, calcium) of an atheromatous plaque
Fibrofatty atheroma (soft) with FATTY STREAKS. Covered by fibrous cap (dense collagen fibers, smooth muscle cells, marcophages, foam cells, etc.).
*What is the most common location of atherosclerotic lesions associated with hemodynamic turbulence?
**Openings of exiting vessels, branch points, posterior abdominal aorta.
What are the predominant lipids in atheromatous plaques?
Cholesterol and cholesterol esters.
What secretes IL-1 and why in the inflammatory processes of pathogenesis of atherosclerosis?
Accumulation of cholesterol crystals in macrophages is recognized by inflammasomes and secrete IL-1
What surrounds the necrotic core of an atheromatous plaque?
Zone of inflammatory and smooth muscle cells.
**What are the most common sites of invovlement in atherosclerosis?
**Abdominal aorta > coronary arteries > popliteal arteries > internal carotid arteries > Circle of Willis
What are complications of atherosclerotic plaques?
Rupture and ulceration (leading to thrombosis)
Hemorrhage (following plaque rupture)
Embolism (following plaque rupture)» cholesterol clefts
Aneurysm formation
What is critical stenosis?
When 70% of the arterial lumen is occluded, leading to ISCHEMIA DOWNSTREAM.
What factors can cause some plaques to be more prone to rupture?
- Fibrous cap continually regenerated/remodeled
- Increased inflammation in plaque (inhibits cap reqynthesis»_space; less collegen»_space; weaker)
- Physical stress dt BP chagne or vasoconstriction
What the difference between a true v. false aneurysm.
True - INTACT, but thinned muscular wall at site of dilation
False - defect THROUGH the wall of vessel or heart, communicating with extravascular hematoma
What is an aneurysm?
Abnormal dilation of vessel or heart.
What are the two types of true aneurysms?
Saccular - one side bulges
Fusiform - entire diameter/both sides enlarge
What is a dissection?
Extravasation of blood through intima, forming an intramural hematoma.
Marfan Syndrome is associated with what?
Aneurysm due to defective vascular wall CT (dt defective fibrillin synthesis).
What is tertiary syphilis associated with?
Ischemia of the outer media of thoracic aorta
What three things weaken the vascular wall by ischemia, possibly leading to aneurysm? Which two are most common?
Ischemia of Outer Media: **HTN and Tertiary Syphilis
Ischemia of Inner Media: **atherosclerosis
What is the final result of both ischemic medial damage and Marfan Syndrome?
Cystic Medial Degeneration (elastin degredation)
What is Cystic Medial Degeneration?
Loss of vascular wall elastic tissue or ineffective elastin synthesis leading to CMD, with visible disruption/disorganization of elastin filaments and increased ground substance.
Elastin is no longer highly ordered.
Common Iliac Arteries are associated with what?
Abdominal Aortic Aneurysm
What demographic are AAAs most common in?
Men, smokers, 60s
A 65yoM, smoker, presents with an AAA. What is the common presentation of this?
Pulsating mass in the abdomen.
What causes AAA?
Severe atherosclerosis of the aorta, covered by mural thrombus.
When should an aneurysm be surgically managed?
When it is greater than 5cm in diameter.
What causes a Thoracic Aortic Aneurysm?
Severe HTN.
Less commonly, Marfan Syndrome- congenitla defect of CT synthesis.
What does Thoracic Aortic Aneurysm common present with?
Impingement of lower respiratory tree, esophagus, or recurrent laryngeal nerves.
Aortic valvular insufficiency.
Rupture.
A 45yoM has severe chest pain, radiating to the back between scapulae. Think what?
Aortic dissection/Dissecting hematoma
A patient has Marfan Syndrome. Think:
Aortic Dissection
Cystic medial degeneration»_space; ANEURYSM (i.e. Thoracic Aortic Aneurysm)
What is the primary risk factor for aortic dissection?
What makes someone more at risk?
HTN!
Male, 40-60yo, hypertensive. Marfan
Where is the most common location for a dissection? What type?
Ascending aorta - Type A Dissection
What is the most common cause of death for both Type A and B Dissections?
Rupture
How is type A dissection treated?
Anti-hypertensive therapy and surgical repair of the intimal tear.
What are the 2 most important causes of aortic aneurysms?
HTN and atherosclerosis.
