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ATHEROSCLEROSIS

ATHEROSCLEROSIS. Atherosclerosis is a specific form of arteriosclerosis (thickening & hardening of arterial walls) affecting primarily the intima of large and medium-sized arteries and is characterized by the presence of fibrofatty plaques known as atheromas.

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ATHEROSCLEROSIS

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  1. ATHEROSCLEROSIS • Atherosclerosis is a specific form of arteriosclerosis (thickening & hardening of arterial walls) affecting primarily the intima of large and medium-sized arteries and is characterized by the presence of fibrofatty plaques known as atheromas. • The term atherosclerosis is derived from athero (meaning porridge) referring to the soft lipid-rich material in the centre of atheroma, and sclerosis (scarring) referring to connective tissue in the plaques.

  2. Atherosclerosis ( contd ) “ While mental disease is our greatest socio – economic problem, cancer our greatest enigma , arthritis and rheumatism our greatest crippler , and accidents our greatest disgrace , atherosclerosis is by far our greatest killer” . - Holman et al.

  3. Risk Factors in Atherosclerosis Major risk factors 1) Major Constitutional risk factors: i. Age ii. Sex iii. Genetic factors iv. Familial and racial factors 2) Major Acquired risk factors: i. Hyperlipidaemia ii. Hypertension iii. Diabetes mellitus iv. Smoking v. Hyperhomocysteinemia

  4. Risk Factors in Atherosclerosis Minor Risk Factors: 1. Environmental influences 2. Obesity 3. Hormones: Oestrogen deficiency, oral contracep. 4. Physical inactivity 5. Stressful life 6. Infections (C. pneumoniae, Herpes virus, CMV) 7. Homocystinuria 8. Role of Alcohol

  5. ROLE OF HYPERLIPIDEMIA IN ATHEROGENESIS • Hyperlipidemia induces production of superoxide and other O2 free radicals. • With chronic hyperlipidemia lipoproteins accumulates within the intima at sight of endothelial permeability.

  6. ROLE OF HYPERLIPIDEMIA IN ATHEROGENESIS • Oxidized LDL has the following effects which may contribute to atheroma formation : a)It is easily phagocytosed by macrophages to form foam cells. b)It is chemotatic for monocytes. c)It increases monocyte adhesion. d)It inhibits the motility of macrophages which are alerady in the lesion.

  7. ROLE OF HYPERLIPIDEMIA IN ATHEROGENESIS e)Stimulates release of growth factors and cytokines. f)It is cytotoxic to endothelial cells and smooth muscle cells. g)It induces production of antibodies to itself.

  8. Schematic diagram of hypothetical sequence of cellular interactions in atherosclerosis

  9. Pathogenesis of Atherosclerosis

  10. PATHOGENESIS OF ATHEROSCLEROSIS

  11. MORPHOLOGY OF ATHEROSCLEROSIS • SITE : In the descending order of frequency Descending abdominal artery, coronary artery, Popliteal artery, Descending thorasic artery, Internal carotid artery, Circle of Willis, Arteries of upper limb and mesentry ( least severe ) • SISE : 0.5 cm to 1.5 cm yellow brown colour protruding into the lumen

  12. MILD ADVANCED

  13. ATHEROMATOUS PLAQUE

  14. COMPLICATIONS IN THE ATHEROMATOUS PLAQUE • HAEMORRHAGE INTO THE PLAQUE • ATHEROEMBLISM • ULCERATION AND THROMBOSIS ON THE PLAQUE • CALCIFICATION • ANEURYSM FORMATION

  15. COMPLICATIONS DUE TO ATHEROSCLEROSIS • ISCHEMIC COMPLICATIONS : I.H.D. , CERRBROVASCULAR ACCIDENTS, INFARCTION GANGRENE OF GIT AND LIMBS ETC, • ATHEROEMBOLIM • ANEURYSM FORMATION WITH ITS COMPLICATIONS.

  16. ARTERIO-SCLEROSIS • GENERIC term for ANYTHING which HARDENS arteries • Atherosclerosis (99%) • Mönckeberg medial calcific sclerosis (1%) • Arteriolosclerosis, involving small arteries and arterioles, generally regarded as NOT strictly being part of atherosclerosis, but more related to hypertension and/or diabetes

  17. FATTY STREAKS

  18. FUN THINGS TO FIND: Lumen, Fibrous cap (fibrous plaque), Lipid core, External Elastic Membrane thinning/destruction, Calcification, Neovascularization

  19. Most abdominal aortic aneurysms (AAA) occur between the renal arteries and the bifurcation of the aorta

  20. Basic processes in atherosclerosis used with permission from M.J. Davies Atlas of Coronary Artery Disease 1998 Lippincott-Raven Publishers

  21. Stage I monocyte adhesion/migration Stage II foam cells (lipid containing macrophages) in intima Stage III appearance of extracellular lipid used with permission from M.J. Davies Atlas of Coronary Artery Disease 1998 Lippincott-Raven Publishers American Heart Association plaque nomenclature

  22. Stage IV Core formation (extracellular lipid coalescing into the center of the plaque) Stage VI Thrombosis Stage V Fibrous Cap and Core formation (fully formed lipid core and well developed cap of fibrous tissue seperating the core from the lumen)

  23. Stable angina. Eccentric coronary stenosis used with permission from M.J. Davies Atlas of Coronary Artery Disease 1998 Lippincott-Raven Publishers

  24. 75% 50% 95% 75% • Relationship between reduction in diameter and cross-sectional area • angiographic view (diameter) • histologic view (cross-sectional area) Arnett EN, Isner JM, Redwood DR, et al. Ann Intern Med 1979;91:350

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