Blood Vessels Flashcards
Localized abnormal dilation of a blood vessel or the heart?
– Not present at birth, but develop over time due to underlying defect in the MEDIA of the vessel
Aneurysms
– Arteriovenous shunting: arteries →veins WITHOUT intervening capillaries
– Tangle, WORM-like vascular channels with prominent pulsatile arteriovenous shunting with high blood flow
Arteriovenous malformations (AVM)
Large or multiple AVMs may shunt blood from arterial to venous circulation, which forces heart to pump additional volume leading to?
High-output cardiac failure
Focal irregular THICKENING in medium & large muscular arteries (renal, carotid, splanchnic, & vertebral vessels)
– Usually developmental defect, but can arise from TRAUMA etc
Fibromuscular dysplasia
Which type of aneurysms involve the circle of Willis and AD polycystic kidney?
Berry aneurysms
Which type of aneurysms involve “the worst headache I’ve ever had”?
Berry aneurysms
Facts on Berry aneurysms:
• ~?% of population has saccular aneurysms
• About ?% saccular found near major BRANCH points of the anterior circulation
- Most frequent cause of clinically significant ? is rupture of saccular (berry) aneurysm
- Aneurysms > ?mm in diameter ~ 50% risk of bleeding per year
- ~? of ruptures associated with acute increases in intracranial pressure
– Straining at stool or Sexual orgasm - ?% die with first rupture
- ? bleeding common in survivors
- 2%
- 90%
- subarachnoid
hemorrhage (SAH) - 10 mm
- 1/3
- 25-50%
- Repeat
Which type of aneurysms originate 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
Mycotic aneurysms
Which type of aneurysm bulges from one side of an artery. A neck leads to it?
Saccular (berry) aneurysm
Which type of aneurysm can involve more than one artery. It is over 2.5 cm wide?
Giant aneurysm
Which type of aneurysm bulges from all sides of an artery. It rarely has a neck?
Fusiform aneurysm
Which type of aneurysm bulges from all sides of an artery. It rarely has a neck?
Fusiform aneurysm
– 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
Arteriovenous malformations (AVM)
AVM:
• surgically generated arteriovenous
fistulas provide vascular access for what?
chronic hemodialysis
Facts on Fibromuscular Dysplasia:
- Cause = ?
- ? degree relatives have ↑ incidence; especially common in ?
- Medial and intimal hyperplasia leads to ?
- ? due to fibromuscular dysplasia of RENAL arteries
- ? on angiography due to mkd attenuation of adjacent media
- Can develop aneurysms that may rupture
- unkn, probably developmental
- First; young women
- Luminal stenosis
- Renovascular HTN
- “string of beads”
What kind of cells have:
– Ability to proliferate
– synthesize collagen, elastin & proteoglycans
– Elaborate growth factors & cytokines
– Vasoconstriction &/or dilation
- Also involved with NL vascular repair and atherosclerosis
Vascular smooth muscle cells
What is the stereotypical response of a vessel wall to any insult?
Intimal thickening
Associated with endothelial cell dysfunction or loss, stimulates smooth muscle cell
recruitment and proliferation, and associated matrix synthesis
Intimal thickening
What type of cells are motile, undergo cell division, acquire new
biosynthetic capabilities?
Neointimal smooth muscle cells
The initial event following vascular injury is?
Endothelial cell activation
What is the basal state for endothelial cells?
Non-adhesive, non thrombogenic surface
What does the “activated state” for endothelial cells involve?
- Increased expression of procoagulants, adhesion molecules, and proinflammatory factors
- Altered expression of chemokines, cytokines, and growth factors
What brings about the activated state of endothelial cells?
- Turbulent flow
- HYPERTENSION
- Cytokines
- Complement
- Bacterial products
- LIPID PRODUCTS
- Advanced glycation end-products
- Hypoxia, acidosis
- Viruses
- CIGARETTE SMOKE
What are the steps for the response to vascular injury?
- Recruitment of smooth muscle cells or smooth muscle precursor cells to the intima
- Smooth muscle cell mitosis
- Elaboration of extracellular matrix
Hypertensive Vascular Disease
- Major risk factor in ?
- Sustained diastolic > ? mmHg or sustained systolic > ? mmHg are associated with increased risk of atherosclerosis
- 29% of population is hypertensive based on these numbers
- atherosclerosis
- 89
- 139
Which disease?
- underlying RENAL OR ADRENAL dz,
- ~5% of population
Secondary HTN
Which diseases are associated with Secondary HTN?
- Primary aldosteronism, Cushing syndrome, or pheochromacytoma
Secondary HTN:
- Hypertension secondary to ? is caused by increased production of RENIN from the ischemic kidney; a ? can be heard on auscultation of the affected kidneys
- renal artery stenosis
- bruit
Type of Hypertension that is idiopathic and involves 90-95% of the population?
Essential HTN
Essential HTN:
- Prevalence and vulnerability increases with ? and with which race?
- Age
- African - American
Complications of Essential HTN bring about?
- Cardiac hypertrophy and heart failure (hypertensive heart dz, HHD), multi-infarct dementia, and renal
failure
Essential HTN:
What do untreated HTN patients die of?
Half (1/2) die of ischemic heart dz (IHD) or congestive heart failure
- Another third (1/3) die of stroke
Which type of HTN involved with 5% of pop and rapid increase in BP and results in death within 1-2 years?
Malignant HTN (rare)
What is the systolic and diastolic for Malignant HTN?
- Systolic >200 mmHg
- Diastolic > 120 mmHg
What type of HTN involved with
– Severe HTN, renal failure, retinal hemorrhages & exudates +/- papilledema
– Often superimposed on pre-existing benign HTN
Malignant HTN
Table 11-1
Type of HTN that Accounts for 90% to 95% of all cases?
Essential HTN
Table 11-1
Causes of Renal Secondary HTN
•Acute glomerulonephritis •Chronic renal disease •Polycystic disease •Renal artery stenosis •Renal vasculitis •Renin-producing tumors
Table 11-1
Causes of Endocrine Secondary HTN
- Adrenocortical hyperfunction (Cushing syndrome, primary aldosteronism, congenital adrenal hyperplasia, licorice ingestion)
- Exogenous hormones (glucocorticoids, estrogen [including pregnancy-induced and oral contraceptives], sympathomimetics and tyramine-containing foods, monoamine oxidase inhibitors)
- Pheochromocytoma •Acromegaly •Hypothyroidism (myxedema) •Hyperthyroidism (thyrotoxicosis) •Pregnancy-induced
Table 11-1
Causes of Cardiovascular Secondary HTN?
- Coarctation of aorta •Polyarteritis nodosa •Increased intravascular volume •Increased cardiac output
- Rigidity of the aorta
Table 11-1
Causes of Neurologic Secondary HTN?
- Psychogenic
- Increased intracranial pressure
- Sleep apnea
- Acute stress, including surgery
BP is a function of?
- Both are influenced by multiple genetic and environmental factors
cardiac output & peripheral vascular resistance
Definition: Heart rate and stroke vol (which is strongly influenced by blood
volume which is regulated by renal sodium excretion or resorption)
Cardiac output
Definition:
regulated at level of arterioles; influenced by neural and hormonal inputs
Vascular resistance
Equation for BP
Cardiac Output X Peripheral Resistance
Cardiac output is affected by?
- Blood volume
- Sodium
- Mineralocorticoids
- Atrial natriuretic peptide - Cardiac factors
- Heart rate
- Contractility
Peripheral resistance is affected by?
1. Humoral factors A. Constrictors - Angiotensin II - Catecholamines - Thromboxane - Leukotrienes - Endothelin
B. Dilators
- Prostaglandins
- Kinins
- NO
- Neural Factors
A. Constrictors
- alpha- adrenergic
B. Dilators
- beta- adrenergic
- Local Factors
- Autoregulation
- pH, hypoxia
Blood Pressure Regulation
• Bld volume and vascular tone modified & maintained by ?
• In states of low volume or low peripheral resistance, or a decreased glomerular
filtration rate, ? is released by juxtaglomerular cells in the afferent arterioles
in the kidneys
• Renin cleaves circulating angiotensinogen to form ?
• Angiotensin I is cleaved to form angiotensin II by ACE (angiotensin- converting
enzyme)
- Angiotensin II is a potent but short-lived vasoconstrictor
- Angiotensin II also stimulates adrenal cortex to release ?, causing renal reabsorption of sodium and water
- Resistance and volume are increased, raising blood pressure
• The volume expansion induces myocardial release of ?,
leading to Na+ excretion and diuresis, as well as vasodilation—thus lowering blood pressure
•renin-angiotensin-
aldosterone system
- renin
- angiotensin I
- aldosterone
- atrial natriuretic peptide
HTN occasionally controlled by a ? gene DO, or is secondary to
? dz, ? dz, or other ? DO
- single
- renal, adrenal, other endocrine
Sustained HTN requires participation of the ?
kidney
HTN causes degenerative changes in the walls of large and medium arteries, that can lead to ?
Aortic dissection and/or cerebrovascular hemorrhage
What are 2 forms of small blood vessel bz?
- Hyaline arteriolosclerosis
2. Hyperplastic arteriolosclerosis
Homogeneous pink thickening and nephrosclerosis are associated with?
Hyaline arteriolosclerosis
Severe HTN, concentric lamellations (“onion skinning”), and necrotizing arteriolitis are associated with?
Hyperplastic arteriolosclerosis
What type of arteriolosclerosis?
- ↑smooth muscle matrix synthesis
- Plasma protein leakage across damaged endothelium
- Homogeneous pink (hyaline) thickening of the vessel wall, → luminal narrowing
- In nephrosclerosis due to chronic HTN, arteriolar narrowing of hyaline
arteriosclerosis → diffuse impairment of renal blood supply and glomerular scarring
Hyaline arteriolosclerosis
- Occurs in severe hypertension
- Smooth muscle cells form concentric lamellations (“onion skinning”) → luminal narrowing
- In malignant hypertension, laminations are accompanied by fibrinoid deposits and
vessel wall necrosis (necrotizing arteriolitis) , particularly in the kidney
Hyperplastic arteriolosclerosis
characterized by mild to moderate increase of blood pressure and an asymptomatic period of several years before the inevitable onset of symptoms and end-organ damage (hence, the condition is not truly benign).
Benign HTN
characterized by marked increase of blood pressure and rapid progression over a few weeks to end-organ failure.
Malignant HTN
Atherosclerosis underlies the pathogenesis of ?, ?, and ? vascular dz
coronary, cerebral, and peripheral vascular dz
Atherosclerosis:
• Extremely common, especially in the developed world
- “causes more morbidity and mortality (roughly ? of all deaths) in the Western world than any other disorder”
- ? responsible for almost ¼ of all deaths in US
- ? highest ischemic heart dz mortality; 3-5X US, 7-12X Japan
- half
- Myocardial infarction
- Soviet Union
Atherosclerosis:
• Prevalence and extent of disease is related to multiple risk factors,
which have ? (rather than additive) effect (see Table 11-2)
• 40-60yo incidence ↑?X; death rates from ischemic heart dz ↑each
decade
•? women are somewhat protected
– atheroprotective effect of ESTROGEN if started early postmenopausal, otherwise no benefit
•? is a major risk factor even in absence of other
factors, it is sufficient to initiate lesion development
• ? syndrome: assoc with central obesity
- INSULIN RESISTANCE, HTN, dyslipidemia (↑LDL, ↓HDL), HYPERCOAGULOBILITY, and pro-inflammatory state may contribute to endothelial dysfunction and/or thrombosis
- synergistic
- 5
- Premenopausal
- Hypercholesterolemia
- Metabolic Syndrome
Major Risk Factors for Atherosclerosis:
Nonmodifiable (Constitutional)/ HEREDITARY
- Between ages 40 and 60, incidence of MI increases five-fold
- Genetic abnormalities
- Family history
- Increasing age
- Male gender
Major Risk Factors for Atherosclerosis: Modifiable (ACQUIRED)
- Incidence of MI 2X as high in patients with DM than in those without
- Hyperlipidemia •Hypertension •Cigarette smoking •Diabetes
* Inflammation
What predicts cardiovascular risk?
C Reactive Protein (CRP)
Pathogenesis of Atherosclerosis:
What are the 2 types of endothelial injury and dysfunction?
- Hemodynamic turbulence
2. Circulating lipids
Pathogenesis of Atherosclerosis: Endothelial injury and dysfunction
Hemodynamic turbulence:
- Most lesions tend to occur at ?— due to flow disturbances normally seen in these locations
openings of exiting vessels, branch points, posterior
abdominal aorta
Pathogenesis of Atherosclerosis: Endothelial injury and dysfunction
Circulating lipids:
- Lipids in atheromatous plaques are predominantly cholesterol and cholesterol esters
- Accumulate in the ?, are taken up by macrophages and partially oxidized
- This modified LDL further accumulates within ? and ? cells,
forming ? cells and a lesion known as a ? - This stimulates an inflammatory response to accumulation of this toxic form of LDL
- intima
- macrophages
- smooth muscle
- foam
- “fatty streak”
Steps to the Arterial Response to Injury
- Chronic endothelial “injury”
- Hyperlipidemia
- Hypertension
- Smoking
- Homocysteine
- Hemodynamic factors
- Toxins
- Viruses
- Immune reactions - Endothelial dysfunction (e.g., increased permeability, leukocyte adhesion), monocyte adhesion and emigration
- Macrophage activation, smooth muscle recruitment **
- Macrophages and smooth muscle cells engulf lipid **
- Smooth muscle proliferation, collagen and other extracellular matrix deposition, extracellular lipid
Pathogenesis of Atherosclerosis: Inflammation
- Accumulation of cholesterol crystals within macrophages is recognized by the
inflammasome, which leads to ? secretion - More macrophages and ? are recruited and activated
- Inflammatory cytokines further activate endothelial cells, and growth factors stimulate
smooth muscle cells to migrate to the intima and proliferate
- IL-1
- T-lymphocytes
Pathogenesis of Atherosclerosis: Smooth muscle proliferation and matrix deposition
- Several growth factors are implicated in SMOOTH MUSCLE CELL PROLIFERATION, including ? (released by
locally adherent platelets) as well as macrophages, endothelial cells, and smooth muscle cells,?
growth factor, and ? - Proliferating smooth muscle cells synthesize extracellular matrix (ECM), including collagen
- Due to the intimal expansion from foam cells and extrace llular lipid, recruited inflammatory and smooth muscle cells and increased ECM, an ? is formed
- Over time, a soft fibrofatty plaque becomes cove red with a fibrous cap (dense collagen fibers). The center of the plaque is ?, containing lipid, debris, foam cells and
thrombus, SURROUNDED BY A ZONE OF INFLAMMATORY AND SMOOTH MUSCLE CELLS.
- PDGF
- fibroblast
- transforming growth factor-α (TGF- α)
- atheromatous plaque
- necrotic
Common sites of involvement for atherosclerosis in decreasing order of frequency/severity of involvement
- Abdominal aorta
- Coronary arteries
- Popliteal arteries
- Internal carotid arteries
- Circle of Willis
What are some complications of atherosclerotic plaques?
- Rupture and ulceration
- May lead to thrombosis - Hemorrhage
- May follow plaque rupture - Embolism
- May follow plaque rupture - Aneurysm formation
What are the consequences of atherosclerosis?
- Stenosis of the arterial lumen
2. Acute plaque change
How much has to be occluded to be considered critical stenosis?
70%
Consequences of atherosclerosis: Acute Plaque Change
- An acute thrombus may form over the plaque, occluding the artery. This may occur secondary to?
- Rupture of the plaque
2. Erosion or ulceration of the plaque surface
Emboli: may be composed of fat droplets, nitrogen bubbles, ? , tumor fragments, bone
marrow, or even foreign bodies. Emboli travel through the blood until
they encounter vessels too small to permit further passage, causing
partial or complete vascular occlusion.
atherosclerotic debris (cholesterol emboli)
“localized abnormal dilation of a blood vessel, or the heart,
that may be congenital or acquired”
Aneurysm
an INTACT (but thinned) muscular wall at the site of dilation
“True” aneurysm
DEFECT through the wall of the vessel, or heart, COMMUNICATING with an extravascular hematoma that
freely communicates with the intravascular space (“pulsating
hematoma”)
“False” aneurysm (pseudo-aneurysm)
• An ? arises when blood enters a defect in the arterial
wall and tunnels between its layers
arterial dissection
– Dissections are often, but not always, aneurysmal (see later)
– Both true and false aneurysms as well as dissections can rupture, often with
catastrophic consequences
An aneurysm may occur whenever the connective tissue of the
vascular wall is weakened, whether by acquired or congenital conditions:
- Defective vascular wall connective tissue
- ? syndrome (defective fibrillin synthesis), Ehlers-Danlos syndrome, scurvy… - Net degradation of vascular wall connective tissue
- Inflammatory conditions (such as atherosclerosis) lead to ↑ matrix metalloprotease (MMP) - Weakening of the vascular wall by ?
- ? → ischemia of inner media
- ? → ischemia of outer media
- ? → ischemia of outer media (thoracic aorta)
- Marfan
-
- ischemia
- Atherosclerosis
- Hypertension
- Tertiary syphilis
- Obliterative endarteritis (characteristic of late- stage syphilis) shows a predilection for small vessels, including those of the
vasa vasorum of the thoracic aorta. This leads to ischemic injury of the aortic media and aneurysmal dilation, which
sometimes involves the aortic valve annulus (aortic valve regurgitation).
Aneurysm:
Loss of vascular wall elastic tissue, or ineffective elastin synthesis, leads to ?, with disrupted and disorganized elastin filaments and increased ground substance (proteoglycans)
cystic medial degeneration
Aneurysm:
Cystic medial degeneration is a final common result of different conditions, including ? and ?
ischemic medial damage and Marfan syndrome
Aneurysm:
The two most important causes of aortic aneurysms are ?
atherosclerosis and hypertension
Aneurysm:
Mycotic aneurysms: can originate from?
– SEPTIC EMBOLI (usually complication of INFECTIVE ENDOCARDITIS)
– Extension of an adjacent SUPPURATIVE PROCESS
– CIRCULATING ORGANISMS DIRECTLY infecting the arterial wall
Abdominal Aortic Aneurysm (AAA):
Are typically due to ?
atherosclerosis
Abdominal Aortic Aneurysm (AAA):
Where do they occur?
Occur in the abdominal aorta, usually below the renal arteries, and often involve the common iliac arteries