Diseases of the blood vessels Flashcards
What is meant by arteriosclerosis?
- It is the thickening & loss of elasticity of arterial walls.
What are the different types of arteriosclerosis?
1) Atherosclerosis: The most frequent, occur in large vessels
2) Monckeberg medial calcific sclerosis (calcific deposit in medium vessels usually in individuals >50 years old)
3) Arteriolosclerosis (Affects small arteries and arterioles)
What is meant by atherosclerosis?
- A slowly progressive disease
- Characterized by intimal lesions “atheromas”, obstructing the vascular lumen, weakening the underlying media
- Characterized by the thickening of the tunica intima and narrowing of the tunica media and the lumen
What are the modifiable risk factors of atherosclerosis?
1) Hyperlipidemia
2) Hypertension
3) Cigarette smoking
4) Diabetes
5) Inflammation
Describe the pathogenesis of atherosclerosis
1) Endothelial injury
2) Accumulation of fat (LDL and Cholesterol)
- When the LDL enters the tunica intima it will be oxidized activating the monocytes via the scavenger receptor in the macrophages engulfing them and forming “foamy cells”
3) Fat accumulation will lead to an inflammatory response
- Increasing the permeability of vessels, adhesion of cells, & activation of thrombosis, The lipid accumulation in the macrophages will also release inflammatory cytokines and recruit smooth muscle cells to proliferate
What are the causes of endothelial injury?
1) Hyperlipidemia
2) Hypertension
3) Smoking
4) Homocysteine
5) Toxins
6) Viruses
7) Immune reactions
Describe the morphology of atherosclerotic vessels
- The key feature in atherosclerosis is the thickening of the intimal layer and lipid accumulation
1) In the early stage it appears as FAINTLY YELLOW STREAKS (LINES) along the vessel
- These yellow streaks are composed of foamy macrophages and they are only minimally raised
2) ATHEROMATOUS PLAQUES, with time the streaks will accumulate forming raised (this raise will cause turbulane), fibrous plaques that looks WHITISH-GREY, ELEVATED, BUTTON-LIKE, WITH A IRREGULAR CIRCULAR DEMARCATION, that eventually could lead to the formation of thrombus
3) ULCERATIONS, CALCIFICATIONS & OSSIFICATIONS of the atheromatous plaque
What are the constituents of an atheromatous plaque
- It is a raised focal lesion
- It has a soft, yellow, grumous core of lipids consisting of (cholesterol and cholesterol ester mainly):
1) Cells
- Smooth muscle cells
- Macrophages
- T-cells
2) ECM:
- Collagen
- Elastic fibers
- Proteoglycans
3) Intra- and extracellular lipids (including cholesterol crystals), covered by a FIRM, WHITE FIBROUS CAP (formed by the SMC, Macrophages, Collagen, Elastin, and Proteoglycans)
- All of these accumulated substances will narrow the lumen & tunica media, and thicken the tunica intima
What are the factors that can complicate the atheromatous plaque?
- People with atherosclerosis are more vulnerable to ischemia and thrombosis, due to the the turbulent flow and the narrowing of the lumen
1) Calcification (dystrophic “calcification in the injured tissue”, increased loss of elasticity)
2) Rupture (releasing its thrombogenic contents), Ulceration, or erosion
3) Hemorrhage
4) Atheroembolism
5) Aneurysm formation (weakness of the wall due to the atrophy of the underlying media and loss of elasticity)
What are the complications of an atheromatous plaque?
1) Stroke
- Embolic (Forms in a distant body part)
- Thrombotic (Occurs in the same vessel)
2) Coronary artery disease
3) Peripheral artery disease
4) Aneurysm
5) Renal artery stenosis
What is an aneurysm?
- It is the abnormal dilatation/bulging of a blood vessel
- It can be congenital or acquired (like atherosclerosis)
What are the different types of aneurysm?
1) True aneurysm:
- Abnormal dilatation of all BV layers (intima, media, and adventitia)
2) False aneurysm:
- RUPTURE of the blood vessel wall, the blood is CONTAINED outside by an ADHERENT EXTRAVASCULAR TISSUE forming a Hematoma
3) Dissecting aneurysm:
- INJURY in the endothelium where the blood SEEPS between the layers of the BV
What are the causes of acquired true aneurysms?
1) Atherosclerosis
2) Hypertension
3) Infections (like Syphilis)
4) Trauma
What is meant by abdominal aortic aneurysm (AAA)?
- Due to atherosclerosis, in the infra-diaphragmatic aorta and infra-renal, it mainly occurs in a fusiform fashion (both sides are dilated) and in some cases as saccular (one side of the vessel is dilated)
What are the clinical presentations/consequences of Abdominal Aortic Aneurysm?
- It might be asymptomatic (discovered accidentally)
1) Obstruction of a vessel branching causing ischemia
2) Can be presented as an abdominal mass (often palpable)
3) It can rupture leading to massive hemorrhage
4) It might impinge on an adjacent structure (like compressing the ureter)
What is meant by a syphilitic (luetic) aneurysm?
- Aneurysm due to infection
- Occurs due to a complication of the tertiary stage of syphilis, involving the vasa vasorum of the (AORTIC ARCH, THORACIC AORTA, AND THE AORTIC ANNULUS)
1) Begins as an inflammatory process in the adventitia of the vasa vasorum, causing an obliterative endarteritis (obstructing the vasa vasorum due to inflammation) then:
2) Narrows the lumen
3) Ischemic injury and destruction of the media
4) Aneurysmal dilatation of the aorta occurs
- Healing of the lesion occurs by fibrosis, giving a wrinkled appearance to the intima (TREE BARKING)
What are the causes of aortic dissection?
- Blood seeps between the layers of the vessel
1) Hypertension (major risk factor)
2) Connective tissue abnormalities (like Marfan syndrome)
3) Iatrogenic (due to complications of the arterial cannulation during diagnostic tests)
4) Rarely in pregnancy
What is the clinical significance of aortic dissection?
- Affected by the location, Proximal ones are more dangerous than peripheral ones
1) Sudden onset of severe sharp, stabbing chest pain
2) Cold legs
3) Dyspnea
4) Syncope/collapse due to sudden changes in BP
What is meant by hypertension?
- Sustained elevation of BP, it is the major risk factor for atherosclerosis, congestive heart failure, and renal failure
What are the risk factors of hypertension?
1) Hereditary
2) Race (more in African Americans)
3) Gender (More in Males and postmenopausal women)
4) Age
5) Obesity
6) Diet
7) Smoking
8) Use of oral contraceptive
What are the types of hypertension in terms of clinical features?
1) Benign
- Mild elevation within a modest level, it can be primary or secondary, and it is stable for years-decads, leading to the progressive narrowing of the arterioles, it is compatible with long life
2) Malignant
- Rapidly rising BP that often leads to end-organ damage, seen in 5% of HTN patients, the diastolic pressure is usually above 120mm Hg.
What is the pathogenesis of hypertension?
- It involves both environmental and genetic factors
1) Defects in renal sodium homeostasis
- Inadequate sodium excretion
- Salt and water retention
- Increase in plasma and ECF volume
- Increase in CO = increased BP
2) Functional vasoconstriction
- Increases the vascular reactivity
- Increases the TPR = increased BP
3) Defects in the vascular smooth muscle growth and structure
- Increases the vascular wall thickness
- Increases the TPR = Increased BP
Describe the morphology of hypertension
- Causes degenerative changes and atherosclerosis in large arteries, however in small arteries:
1) Hyaline arteriosclerosis
- Deposition of acellular hyalinized material, narrowing the lumen, usually in benign hypertension, which might cause ischemia after several years
2) Hyperplastic arteriosclerosis (layers of smooth muscles)
- Due to the hyperplasia of the smooth muscles
- The injury will activate Smooth muscle proliferation giving an ONION appearance
3) Necrotizing arteriolitis
- In malignant hypertension
- Necrosis in the vessel wall (only dead tissue is seen)
- Accompanied by fibrinoids deposits (fibrin deposits)
What are the complications of hypertension?
1) CVS
- Aortic dissection
- Hypertrophy
- Coronary heart disease
2) Brain
- Hemorrhage
- Infarction leading to stroke
3) Eye
Due to the narrowing of the lume:
- Microinfarcts (pale/yellow/whitish-cotton wool spots)
- Superficial hemorrhages (flame shape)
4) Kidney injury
