atherosclerosis dr: wael h.mansy, md assistant professor college of pharmacy king saud university
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ATHEROSCLEROSISATHEROSCLEROSIS
Dr: Wael H.Mansy, MDAssistant Professor
College of Pharmacy
King Saud University
ATHEROSCLEROSISATHEROSCLEROSIS
Atherosclerosis derives from “greek”:
– “sclerosis” = hardening - thickening– “athere” = lipid accumulation
•An inflammatory disease in which immune mechanisms interact with metabolic risk factors to initiate, propagate and activate lesions in the arterial wall.
ATHEROSCLEROSISATHEROSCLEROSIS
Atherosclerosis is the “MOST IMPORTANT KILLER” in developed world
The WHO estimates that nearly 45% of the Western world population will die due to a complicación atherosclerosis.
In USA causes close to 1 million deaths p/y
ATHEROSCLEROSISATHEROSCLEROSIS RISK FACTORS TO ATHEROSCLEROSIS
Dyslipidemia: Hypercholesterolemia Low levels of H.D.L. High Levels of L.D.L. Or V.L.D.L. Mixed
Systemic Hypertension
Tobacco smoking ( 70% Death rate & increase 3 to 5 fold risk of CAD)
Diabetes M. Type I or II
Obesity
ATHEROSCLEROSISATHEROSCLEROSIS RISK FACTORS TO ATHEROSCLEROSIS
Modifiable:
The 5 major risk factors plus Hyperuricemia High Na, Fat & Calories intake Physical Inactivity Increased Fibrinogen plasma levels Insulin Resistant States Type “A” personality (stress junkies) Post-menopausal state
ATHEROSCLEROSISATHEROSCLEROSIS RISK FACTORS TO ATHEROSCLEROSIS
Non-Modifiable:
Genetic defects Male gender (?) Aging (?) Increase of:
Lipoprotein (a) Plasminogen Activator Inhibitor-1 Homcysteine
Virus (C.M.V.???) Microbial pathogens (Chlamydia???) Auto-immune inflammatory diseases
ATHEROSCLEROSISATHEROSCLEROSIS ARTERIAL ANATOMY
Three main layers:
Intima: Single layer of endothelial cells
Media: Smooth Muscle Cells (SMC) & connective tissue elements
Adventitia: S.M.C., fibroblast & glycosaminoglycans
Separating these layers, exist the internal and external elastic lamina.
The Endothelium Maintains Vascular Health
Dilatation Growth inhibition Constriction Antithrombotic Growth promotion Anti-inflammatory Prothrombotic Antioxidant Proinflammatory
Pro-oxidant
Endothelial Dysfunction
Increased:
– adhesiveness to leukocytes/platelets
– permeability
– procoagulant properties
– formation of vasoactive molecules,
cytokines, and growth factors.
= Inflammation
ATHEROSCLEROSISATHEROSCLEROSIS
Steps in atherosclerosis development
Fatty streak
Fibrous plaque
Atherosclerotic plaque (Atheroma)
Calcification plaque
Complication of atherosclerotic plaques.
ATHEROSCLEROSISATHEROSCLEROSIS
Fatty streak:
Represents the initial lesion
Results from abnormal accumulation of lipoproteins in the intima layer
Mainly localized at arterial bifurcations
ATHEROSCLEROSISATHEROSCLEROSIS Fibrous plaque:
Is the most characteristic lesion of Atherosclerosis, is composed of:
Monocytes
Macrophages
S.M.C.
“Foam cells”
*** Lipid-rich “Necrotic core”.
ATHEROSCLEROSISATHEROSCLEROSIS Atherosclerotic plaque:
Proliferation at the intima layer of: S.M.C. Macrophages “Foam cells” Conective Tissue elements
Collagen type I Elastin Fibers Glycosaminoglycans Cholesterol uptake
Calcium deposits
Complication of the plaque
ATHEROSCLEROSISATHEROSCLEROSIS COMPLICATED PLAQUE:
Ulceration Acute thrombosis with oclussion Disloging and peripheral embolism
Thrombosis Acute ischemia/necrosis
Growth Chronic ischemia
Necrosis Aneurysm development
ATHEROSCLEROSISATHEROSCLEROSIS Hyperlipidemia injury the endothelium by:
Induction of Growth factors synthesis by endothelial cells
Increasing Monocytes attachment and migration to sub-endothelial level
Increasing LDL uptake by SMC and Macrophages to develop Foam cells
Oxidation and release of toxic products increasing endothelial injury.
ATHEROSCLEROSISATHEROSCLEROSIS Rheologic forces are more marked at arterial
bifurcations Chronic mechanical damage to endothelial
cells leads to:
Increase LDL permeability
Increase Platelet adhesivity
Increase Monocytes adhesivity
Increase synthesis & release of cytokines, vasoactive substances so-on.
Decrease synthesis & release of anti-platelet & anti-adhesivity substances.
ATHEROSCLEROSISATHEROSCLEROSIS Monocytes
Subendothelial level
Macrophages
Take LDL
“Foam cells”
ATHEROSCLEROSISATHEROSCLEROSIS Monocytes-Macrophages-Foam cells
Synthesis and release of:
LDL oxidizing products Lysosomal enzymes Oxygen Free radicals Growth Factors (PDGF, PAF, EGF) Extracellular matrix synthesis Cytokines (TNFα, IL-1)
ATHEROSCLEROSISATHEROSCLEROSIS SMOOTH MUSCLE CELLS
From the “media” to the “intima” layer
Migrates Proliferates Turns into “Foam cells” Synthesis of connective tissue elements Synthesis of Growth factors Synthesis of Cytokines Synthesis of Vasoactive substances
ATHEROSCLEROSISATHEROSCLEROSIS PLATELETS
Adhesion and aggregation with:
Release of granular content
Growth factors & Cytokines Lypooxygenase pathway products Vasoactive substances
Thrombus formation
These enhance chemotaxis and proliferation of S.M.C. & Monocytes
ATHEROSCLEROSISATHEROSCLEROSIS Fibrinogen role:
Fibrinogen increase blood viscosity
Increases platelets & Monocytes attachment to endothelium
Conversion to fibrin that causes: Endothelial cell disorganization Provides an adsorptive surface to LDL Induces SMC proliferation
Fibrinopeptides causes: Increase in vascular permeability Chemotactic activity Proliferation activity Vasoconstriction.
ATHEROSCLEROSISATHEROSCLEROSIS
Insulin Resistance States:
Increase synthesis of LDL.
Increase uptake of LDL by SMC
Growth factor activity
Aggravation of Hypertension
ATHEROSCLEROSISATHEROSCLEROSIS Complications of atherosclerotic
plaques
SLOW GROWING WITH OCCLUSION
ACUTE THROMBOSIS
NECROSIS & ANURYSM DEVELOPMENT AND RUPTURE
DISLOGING AND PERIPHERAL EMBOLISM
ATHEROSCLEROSISATHEROSCLEROSIS CLINICAL SYNDROMES
ASYMPTOMATIC
ACUTE ISCHEMIA WITH NECROSIS
CHRONIC ISCHEMIA WITH ARTERIAL INSUFFICIENCY SYNDROMES
ACUTE PERIPHERAL EMBOLISM
ATHEROSCLEROSISATHEROSCLEROSIS CLINICAL SYNDROME DEPENDS UPON THE
ARTERY AFFECTED.
Carotid arteries
Coronary arteries
Abdominal aorta
Renal arteries
Mesenteric arteries
Lower limb arteries
ATHEROSCLEROSISATHEROSCLEROSIS PREVENTION & TREATMENT
Reducing or controlling modifiable risk factors:
Dyslipidemia Hypertension Tobacco smoking Diabetes Mellitus Obesity Hyperuricemia High Na, Fat & Calories intake Physical Inactivity Increased Fibrinogen plasma levels Insulin Resistant States Type “A” personality Post-menopausal state
ATHEROSCLEROSISATHEROSCLEROSIS PREVENTION & TREATMENT
Reducing or controlling modifiable risk factors:
Dyslipidemia T.Chol= < 200mg/dl LDL = < 150mg/dl HDL = > 60mg/dl
Hypertension ( < 140/90mmHg) Tobacco smoking D. Mellitus (Gluc. < 127mg/dl Obesity (B.M.I. < 25 )
ATHEROSCLEROSISATHEROSCLEROSIS PREVENTION & TREATMENT
Stabilization or regression of developed lesions:
HMGCoA inhibitors ACE inhibitors Calcium Channel blockers
Reduction risk of thrombosis:
Primary: Aspirin 80 mg/day
Secondary: Ticlopidine Clopidogrel
ATHEROSCLEROSISATHEROSCLEROSIS PREVENTION & TREATMENT
Antioxidant Vitamin supplementation Vit. C. Vit. E
Estrogen replacement after menopause
Under research:
Cytokines Growth factor antagonists Antisense oligonucleotides Angiogenesis-blocking drugs Smooth muscle cell hyperplasia-blocking drugs