blood vessels Flashcards
Aneurysm
- localized abnormal dilation of a blood vessel or the heart
- over time due to underlying defect in the media of the vessel
Arteriovenous malformations (AVM):
arteries →veins without intervening capillaries
–Tangle, worm-like vascular channels with prominent pulsatile arteriovenous shunting with high blood flow
-Large or multiple AVMs may lead to high output cardiac failure
Fibromuscular dysplasia:
-focal irregular thickening in medium & large muscular arteries (renal, carotid, splanchnic, & vertebral vessels)
–Usually developmental defect, but can arise from trauma etc
-young women
Berry aneurysms
Circle of Willis, AD polycystic kidney dz
–“the worst headache I’ve ever had”
-2% of pop
-90% near major branch points of ant circulation
-diameter 10>mm= 50% risk of bleeding per year
-1/3 rupture due to increase intracranial pressure (stool,orgasm)
-25-50% die w/ 1st rupture
-repeat bleeding common
most common cause of subarachnoid hemorrhage
is rupture of saccular(berry) aneurysm
where do mycotic aneurysms arise from?
(1) embolization of a septic embolus, usually as a complication of infective endocarditis
(2) an extension of an adjacent suppurative process
(3) circulating organisms directly infecting the arterial wall
- rare
what do arteriovenous malformations result from?
–can result from rupture of an arterial aneurysm into the adjacent vein
–penetrating injuries that pierce arteries & veins
–or from inflammatory necrosis of adjacent vessels
-can be surgically generated for hemodialysis
what BP is associated with increased risk of atherosclerosis
diastolic >80mmHg
systolic>139mmHg
secondary HTN
5%
- underlies renal or adrenal disease
- Primary aldosteronism, Cushing syndrome, or pheochromacytoma
- HTN due to renal artery stenosis caused by increased renin
- bruit heard
essential HTN
- idiopathic
- 90-95%
- increases with age and african americans
- Cardiac hypertrophy & heart failure (hypertensive heart dz, HHD), multi-infarct dementia, & renal failure
what do untreated HTN patients die from?
half (½) die of ischemic heart dz (IHD) or congestive heart failure, another third (⅓)die of stroke
malignant HTN
5% rapid ↑BP → death within 1-2 years
Systolic > 200mmHg, diastolic > 120mmHg
–Severe HTN, renal failure, retinal hemorrhages & exudates +/-papilledema
–Often superimposed on pre-existing benign HTN
what is blood pressure a function of?
cardiac output & peripheral vascular resistance, (genetics and environment)
cardiac output
- heart rate X stroke vol
- influenced by blood volume which is regulated by renal sodium
vascular resistance
regulated at level of arterioles;
influenced by neural & hormonal inputs
what are some humoral blood vessel constrictors
- angiotensin II
- catecholamines
- thromboxane
- leukotrienes
- endothelin
what are some blood vessel dilators
- prostaglandins
- NO
- kinins
what are neural blood vessel dilators
-beta-adrenergic
what are neural blood vessel constrictors
-alpha-adrenergic
what is HTN a risk factor for?
Atherosclerosis, CHF, & renal failure
what can HTN cause?
cardiac hypertrophy &heart failure (hypertensive heart disease),multi-infarct dementia, aortic dissection (discussed later in this chapter), &renal failure
what does untreated HTN lead to?
roughly ½ of HTN patients die of ischemic heart disease (IHD) or congestive heart failure (CHF); and another ⅓ die of stroke
what type of HTN is seen in most patients?
Essential HTN 90-95% of cases
what does sustained HTN require?
participation by kidney
Hyaline arteriolosclerosis:
-↑smooth muscle matrix synthesis
-plasma protein leakage
Homogeneou spink (hyaline) thickening of the vessel wall, →luminal narrowing
nephrosclerosisdue to chronic HTN
diffuse impairment of renal blood supply &glomerular scarring
Hyperplastic arteriolosclerosis:
-severe hypertension
Smooth muscle cells form concentric lamellations (“onionskinning”)→ luminal narrowing
malignant hypertension,
- laminations
- fibrinoid deposits
- necrotizing arteriolitis (esp in kidney)
what are two types of ateriolosclerosis
1) hyaline
2) hyperplastic
Mönckeberg medial sclerosis:
> 50yo
calcification of muscular arteries,
internal elastic membrane involved,
no narrowing of lumen,
no clinical significance
what is most frequent & clinically important pattern of Atherosclerosis
“gruel” & “hardening”,
Atheroma
Raised lesion with a soft grumous core of lipid covered by a fibrous cap
what can happen to atherosclerotic plaque?
1) obstruct blood flow
2) rupture and lead to thrombosis
3) increase diffusion distance leading to weakening of wall and aneurysm
what is the morphology of atherosclerotic plaque?
1) fibrous cap
2) necrotic center with foam cells and cholesterol crystals
what are nonmodifiable risk factors for atherosclerosis
1) genetic abnormalities
2) family history
3) increasing age (risk of MI increase 5X between 40 and 60)
4) male gender
what are modifiable risk factors for atherosclerosis
1) hyperlipidemia
2) hypertension
3) smoking
4) diabetes (incidence MI 2x higher)
5) inflammation
what are major contributors to atherosclerosis
1) age
2) hypercholesterolemia
3) metabolic syndrome
what protein predicts cardiovascular risk?
C reactive protein (CRP)
what cytokines are released during atherosclerosis inflammation
1) IL-1
- recruits macrophages and T lymphocytes
what GF are implicated in smooth muscle cell proliferation
1) PDGF
2) fibroblast growth factor
3) TGF-alpha
what are common site of atheromatous plaques in decreasing order of frequency/severity
Abdominal aorta Coronary arteries Popliteal arteries Internal carotid arteries Circle of Willis
Complications of atherosclerotic plaques
1) rupture and ulceration leading to thrombosis
2) hemorrhage
3) embolism
4) aneurysm
what are consequences of atherosclerosis
1) stenosis of lumen= ischemia
2) acute plaque change (thrombus, hemorrhage)
what is critical stenosis of lumen?
approx 70% occluded
what can cause fibrous cap on plaque to rupture?
things that decrease collagen synthesis
1) changes in BP
2) vasoconstriction
what can emboli be composed of?
may be composed of fat droplets, nitrogen bubbles, atherosclerotic debris(cholesterol emboli), tumor fragments, bone marrow, or even foreign bodies
what are 3 clinical complications of atherosclerosis
1) aneurysms and hemorrhage
2) occlusion by thrombus
3) critical stenosis