Robbins - Ch 11 Flashcards
The basic constituents of the walls of blood vessels are 1 and 2 admixed with a variety of extracellular matrix, including elastin, collagen, and 3.
- Endothelial cells
- Smooth muscles
- Glycosaminoglycans
What are the three layers that make up arteries and veins?
Intima, media, and adventitia. These layers are most distinct in arteries.
which vessels are the principal points of physiologic resistance to blood flow?
Arterioles
1 is a vascular anomaly that is characterized by saccular outpouching, that typically occurs in the circle of willis, and has an association with autosomal dominant polycystic kidney disease. The single biggest worry of this anomaly is 2.
- Berry aneurysm
2. Rupture can cause fatal subarachnoid hemorrhage
T or F: A-V fistulas is always due to developmental defect.
False. It’s most commonly a developmental defect, but may arise secondary to inflammation, trauma or rupture.
A-V fistulas come to clinical concern when _
- rupture that can lead to subarachnoid hemorrhage
- Large or multiple AV fistulas can produce clinically significant effects by shunting blood from arterial to the venous circulation forcing heart to pump more and leading to high output cardiac failure
1 is a focal irregular thickening in medium and large muscular arteries, classically presents as 2, can also occur in _3_vessels. First degree relatives are at increased risk. On x-ray they appear as 4. Prevalence is common in 5.
- Fibromuscular dysplasia.
- Renal artery stenosis
- Carotid, splanchnic, vertebral
- Beads on a string
- young women
Endothelial cells normally maintain a nonthrombogenic surface under normal conditions but become activated due to certain stimuli. Name some stimuli that which can lead to an activated endothelial cell.
- Turbulent blood flow
- HTN
- Complement, bacterial product, lipid product, glycation end product
- Virus
- Hypoxia, acidosis
- Components of tobacco smoke
When endothelial cell become activated due to a stimuli, what changes are seen?
- expression of adhesion molecules
- Expression of procoagulants and anticoagulants
- expression of vasoactive factors, growth factors, chemokines, cytokines
What is meant by endothelial dysfunction?
Normally, endothelial cells can cycle between basal and activated states, to respond to various stimuli but when certain stimuli are consistently present, the prolonged activated state can lead to endothelial dysfunction characterized by procoagulation, proinflammation, and smooth muscle stimulation
_ is the stereotypical response of the vessel wall to any insult.
Intimal thickening, potentially affecting blood flow.
Sustained diastolic pressure above _ mmHg or sustained systolic pressure above _ mmHg is considered hypertension and is at increased risk of atheroscleortic disease.
89 and 139. Makes up about 30% of the population
90-95% of HTN are 1 and 5% are _ 2_
- Idiopathic or essential
2. secondary HTN due to underlying renal or adrenal disease, renal artery stenosis, or other.
Risk factors for essential HTN include:
- High Na intake
- stress
- obesity
- smoking
- physical inactivity
Blood pressure is a function of 1 and 2, both of which are influenced by multiple genetic and environmental factors, and is modified and maintained by the 3
- Cardiac output (CO)
- Peripheral vascular resistance (PVR)
Mean arterial pressure (MAP) = CO x TPR
- renin-angiotensin-aldosterone system (RAAS)
CO is a function of _ and _.
Stroke volume (SV) and heart rate (HR)
The most important determinant of stroke volume is 1, which is rgulatd through 2 homeostatis
- filling pressure
2. Sodium
Heart rate and myocardial contractility is mainly regulated by _ and _ systems which also have important effects on vascular tone.
alpha and beta adrenergic systems
Peripheral vascular resistance is regulated predomiantly at the level of which vessels and by what?
arterioles by neural and hormonal inputs
What are some vasodilactors and vasoconstrictors?
Vasodilators: kinins, prostaglandins, and NO)
Vasoconstrictors: angII, catecholamines, and endothelin
In states of low volume, or low peripheral resistance, or a decreased glomerular filtration rate, 1 is released by 2 in the _ 3_ arterioles in the kidney
- renin
- JG cells
- afferent
Describe some of the roles of vascular smooth muscle cells.
- Migrate and proliferate in response to mediators
- Elaborate cytokines and growth factors
- Synthesize and remodel extracellular matrix
- Cause vasoconstriction or dilation in response to physiologic or pharmacologic stimuli
what is neointima?
Injured endothelium and underlying vessel wall heals by stimulating smooth muscle cell ingrowth and exracellular matrix production leading to intimal thickening
This type of hypertension is characterized by systolic pressure more than 200 mm Hg, diastolic pressure more than 120 mm Hg, can lead to renal failure, retinal hemorrhage and if is left untreated can lead to death in 1 to 2 years.
Malignant hyertension
Blood volume is affected by what factors?
- Sodium
- Mineralocorticoids (aldosterone)
- Natriuretic factors that induce Na excretion
What is Liddle syndrome?
Gain of function mutation in an epithelial Na channel protein that increase distal tubular reabsorption of Na in response to aldosterone. —> secondary hypertension
Hypertension is associated with what two forms of small arteriolar disease?
Hyaline ateriolosclerosis and hyperplastic arteriolosclerosis
Describe the pathology of hyaline arteriolosclerosis
Endothelial cell injury with plasma leakage into arteriolar walls and increased smooth muscle cell matrix synthesis. Appears as diffuse pink hyaline on thickened arteriolar wall –> luminal stenosis
_ is usually seen in malignant hypertension and appears as concentric laminated (onion skin) arteriolar thickening with basement membrane and smooth muscle cell proliferation
Hyperplastic arteriolosclerosis
The intimal thickening as seen in hyaline arteriolosclerosis is made up or _
amorphous numerous plasma proteins that have leaked through.
The most common cause of secondary hypertension is _
Primary hyperaldosteronism due to a gene defect affecting enzymes involved in aldosterone metabolism.
Factors that are though to be contributory to essential hypertension include:
- Genetic factors that which alters net sodium reabsorption
- reduced renal Sodium excretion –> increase in fluid volume –> increase CO, peripheral vasoconstriction –> elevated BP. “resetting of pressure natriuresis” at the expense of increase BP
- Vasoconstrictive influences such as increased peripheral resistance
- Environmental factors such as smoking, obesity, physical inactivity, heavy salt intake
In _ due to chronic HTN, the arteriolar narrowing of hyaline arteriosclerosis causes diffuse impairment of renal blood supply and cause diffuse impairment of renal blood supply and glomerular scarring
Nephrosclerosis
The onion-skin like thickening as seen in hyperplastic arteriolosclerosis is accompanied by 1 deposits and vessel wall necrosis (necrotizing arteriolitis), particularly seen in 2
- fibrinoid
2. Kidney
Hardening of arteries is termed as
arteriosclerosis, characterized by wall thickening and loss of elasticity.
what are the three general patterns of arteriosclerosis?
- Arteriolosclerosis which affects small arteries and arterioles and may cause ischemic injury via hyaline or hyperplastic changes
- Monckeberg medial sclerosis: calcification of walls of muscular arteries typically involving internal elastic membrane. do not encroach lumen and so not significant
- Atherosclerosis - hardening and most clinically important
Atherosclerosis is a slowly progressive disease of which vessels?
large to medium sized muscular and elastic arteries.
What is atheromas?
Aka atheromatous or atherosclerotic plaques that protrude into vessel lumens. It consists of a raised lesion with a soft grumous core of lipid (mainly cholesterol) covered by a fibrous cap.
How does atherosclerosis cause pathology?
- Mechanically disrupt flow
- Plaque rupture leading to vessel thrombosis
- Weakening the underlying vessel wall and leading to aneurysm formation
What are the 4 major/classic risk factors leading to ahterosclerosis?
- Hyperlipidemia (esp LDL)
- HTN
- Smoking
- Diabetes
What are some nonmodifiable (constitutional) risk factors for atherosclerosis?
- Genetic abnormalities (hypercholesterolemia)
- Age (increased risk with age) between 40-60 risk of MI increase 5x.
- Gender: male more than women. Women more at risk after menopause (
Up to 20% of all cardiovascular events occur in the absence of major risk factors. Describe some of the additional risk factors.
- Inflammation (linked to atherosclerotic plaque formation/rupture). CRP can be measured as a marker
- hyperhomocystinemia (serum levels correlate with coronary atherosclerosis, peripheral vascular disease stroke and venous thrombosis)
- Metabolic syndrome (central obesity-insulin resistance, dyslipidemia, HTN) hypercoagulability.
- Lipoproteins: an altered form of LDL
- Hemostatic factors (Factor V leiden, elevated plasminogen activator inhibitor 1, platelet derived factors, thrombin etc)
Early lesions composed of intimal collections of foamy macrophages and smooth muscles cells that gently protrude into the vascular lumen is known as _
fatty streak
In the pathogenesis of atherosclerosis, describe the response to injury model.
Views atherosclerosis as a chronic inflammatory and healing response of arterial wall to endothelial injury. Lesion progression occurs through interaction of modified lipoproteins, monocytes-derived macrophages, and T lymphocytes with endothelial cells and smooth muscle cells of the arterial wall.
Explain the sequence of events in the atherosclerosis progression.
- Endothelial injury and dysfunction, causing increased vascular permeability, leukocytes, adhesion, and thrombosis
- Accumulation of lipoproteins
- Monocyte adhesion to endothelium then migration to intima and transformation into macrophages and foam cells
- Platelet adhesion
- Factor released from activated platelets, macrophages, and vascular wall cells, inducing smooth muscle cell recruitment
- Smooth muscle cell proliferation, EC matrix production and recruitment of T cells
- Lipid accumulation
The two most important causes of endothelial dysfunction are
- Hemodynamic disturbances (plaque formation usually occur at openings of exiting vessels, branch points, posterior abd aorta due to flow disturbance that’s normally seen in these locations.
- Circulating lipids (increased LDL, decreased HDL and increased abnormal lipoproteins) (Hypercholesterolemia) -lipids taken up by macrophages and oxidized and modified and accumulates within macrophages –> foam cells –> secretes Il-1 –>recruits more macrophages and T cells.
In descending order, the most extensively involved vessels are_
- lower abd aorta
- Coronary arteries
- popliteal arteries
- internal carotid arteries
- circle of willis
Morphologically, atherosclerotic plaques have what three principal components?
- Smooth muscle cells, macrophages, and T cells
- Extracellular matrix, including collagen, elastic fibers, and proteoglycans
- intracellular and extracellular lipid
Atherosclerotic plaques are susceptible to what clinically important pathologic changes?
- Rupture, ulceration, or erosion –> thrombosis
- Hemorrhage into a plaque
- Atheroembolism
- Aneurysm formation
Consequences of atherosclerotic disease include:
- Atherosclerotic stenosis
- Acute plaque change
- Thrombosis
- Vasoconstriction
- Vessel wall weakening
Critical stenosis is the stage at which the occlusion is sufficiently severe to produce tissue ischemia and typically occurs at when occlusion produces _% decrease in luminal cross sectional area.
70
What is acute plaque changes?
Plaque erosion, frank rupture, or hemorrhage into the plaque, which expands the plaque volume and can increase luminal stenosis
1 Plaques that are at increased risk of rupture and is characterized by large deformable atheromatous cores, thin fibrous caps, and/or increased inflammatory cell content. Whereas 2 have a core that is characterized by minimal atheromatous cores and thicker, well collagenized fibrous caps with little inflammation.
- vulnerable plaques
2. Stable plaques
what is a true aneurysm?
Saccular (one side) or fusiform (both sides) dilation of all three vessel wall layers
What is a false aneurysm/pseudoaneurysm?
An extravascular hematoma that communicates with the intravascular space (pulsating hematoma)
what is a arterial dissection?
when blood enters the arterial wall as a hematoma dissecting between layers. Often are aneurysmal, but not always
Aneurysm can occur whenever the connective tissue of the vascular wall is weakened, whether by acquired or congenital conditions. List and explain some factors that can lead to vascular weakening.
- Defective vascular wall connective tissue as seen in 1. marfan syndrome due to defective fibrillin synthesis; 2. Loeys-Dietz syndrome mutation in TGF-beta receptors leading to defective synthesis of elastin and collagens I and III; 3. Ehlers Danlos syndrome (defective collagen type III; 4. Scurvy vit C deficiency leading to poor collagen cross linking
- Imbalance of college degradation and synthesis, esp increased MMP, decreased TIMPs. Example in AAA, local production of cytokines (IL4, and 10) stimulate release of elastolytic MMP from macrophages
- loss of smooth muscle cells or synthesis of noncollagenous or nonelastic extracellular matrix (poor O2 diffusion due to increased diameter by which O2 must diffuse leading to degenerative changes of the media (cystic medial degeneration).
Explain how syphilis is implicated in aneurysm formation
Tertiary syphilis characterized by obliterative endarteritis shows predilection for small vessels including those of vasa vasorum. this leads to ischemic injury of the media and thus aneurysmal dilation
what are the two most important causes of aortic aneurysm?
atherosclerosis and HTN
Aneurysms due to infection are called 1, and can originate 2, 3, and_4.
- Mycotic aneurysm
- embolization of a septic embolus usually a complication of endocarditis
- extension of an adj suppurative process
- By circulating organisms
Abdominal aortic aneurysm (AAA) typical occur due to _
atherosclerosis. Frequently in male smokers over 50.
Although they’re uncommon, inflammatory AAA accounts for 5-10% of all AAA and occur in younger patients. Explain how these appear morphologically
Pt usually presents with back pain and elevated inflammatory markers like CRP. Grossly they are characterized by dense abundant lymphoplasmacytic inflammation with many macrophages associated with dense perioartic scarring that can extend into the anterior retroperirtoneum.
Pts with immunoglobulin G4 (IgG4)-related disease are also develop inflammatory AAA. Explain how the aneurysm arise and why it’s important to identify these aneurysm promptly.
Affected individual have aortitis and periaortitis that weaken the wall sufficiently and can give rise to aneurysms. Recognition is important since it responds well to steroid therapy
What complications are associated with AAA?
- rupture into peritoneal cavity —> fatal hemorrhage
- obstruction of a vessel branching off from the aorta
- Embolism from atheroma or mural thrombus
- impringement on another structure (ureter or verebrae
Risk of rupture of AAA is directly related to size. What size is at greater risk rupture?
6cm or larger
What sized AAA requires aggressive usually by surgical bypass with prosthetic grafts.
5cm or larger
What signs and symptoms do patients with thoracic aortic aneurysm present with?
- respiratory difficulties due to encroachment on lungs and airway
- difficulty swallowing
- persistent cough
- pain caused by erosion of bone
- cardiac disease as aortic aneurysm leads to aortic valve dilation with valvular insufficiency or narrowing of coronary ostia
- rupture