Atherosclerosis
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Atherosclerosis

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Atherosclerosis Atherosclerosis Presentation Transcript

  • Atherosclerosis
  • Introduction
    • A disease of the intima of large arteries
    • Major degenerative disease of arteries
    • Atherosclerotic lesions produce luminal narrowing, thrombosis, embolization, and occulation.
    • Characterized by local accumulation of lipid in the vessel wall located either in the extracellular matrix or inside foam cells.
  • Thories of atherogenesis
    • Lipid insudation hypothesis
    • Encrustation hypothesis
    • Monoclonal hypothesis
    • Infectious hypothesis
    • Intima cell mass hypothesis
    • Injury hypothesis
  • Pathology
  • Pathologic hallmark
    • Atherosclerotic plaque
    • Major components of plaque : smooth muscle cells, connective tissue (matrix), lipid, and inflammatory cells (predominantly macrophages)
    • The presence of lipid within these lesions is a prominent distinguishing feature in comparison to other arteriopathies.
  • Position of lesion
    • commonly involved the infrarenal abdominal aorta, iliofemoral arteries (especially the superficial femoral artery), popliteal arteries, carotid bifurcation, and proximal coronary arteries
    • Upper extremity vessels, as well as the common carotid, renal, and mesenteric arteries (beyond their origins), are also usually spared.
    • Major
      • Hyperlipidemia
      • Cigarette smoking
      • Hypertension
      • Diabetes
      • Positive family history
      • Hyperfibrinogenemia
      • Age
      • Homocysteinemia
    Risk Factors
    • Studies have demonstrated a strong positive correlation between atherosclerotic cardiovascular disease and elevated total and LDL cholesterol and an equally strong negative correlation with HDL levels.
    Hypercholesterolemia
  • Cigarette smoking
    • The mechanism for the effects of smoking is likely to involve direct toxicity of tobacco metabolites on the vascular endothelium, probably by creating oxidant stress .
  • Hypertension
    • another important independent risk factor for coronary atherosclerosis, with a continuous increase in relative risk associated with each increment of pressure .
  • Diabetes
    • Diabetic patients are also at markedly increased risk for atherosclerosis, often manifesting a particularly virulent form of the disease, leading to higher rates of myocardial events, stroke, and amputation.
  • Risk Factors
    • Minor
      • Obesity
      • Excessive alcohol use
      • Sedentary lifestyle
      • Male gender
      • Hypercoagulable status
      • Race
  • Clinical presentation
    • Arterial insufficiency
    • Aneurysm formation
    • embolism
  • Peripheral arterial insufficiency
    • Atherosclerotic plagues become large enough to narrow the arterial lumen and cause atherosclerosis occlusion
  • Definition
    • a complex, chronic inflammatory process that affects the elastic and muscular arteries.
    • Atherosclerotic plaques continuous progression and secondary thrombosis cause stricture or obstruction of arteries and often results in chronic or acute ischemic symptoms of lower limbs
    • Atherosclerotic plaques are dynamic lesions that may undergo progression or regression over time. Similarly, the underlying arterial wall also undergoes adaptive remodeling.
    • Arterial enlargement is a well-established feature of atherosclerosis and often results in relative preservation of luminal area until plaque volume reaches a threshold size (approximately 40% stenosis) beyond which compensation fails and lumen narrowing becomes progressive.
    Pathophysiology
  • Type
    • Intermittent claudication
    • Decreased amplitude of the pulses
    • Pallor of foot on elevation
    • Ischemic rest pain
    • Ulceration/ nonhealing of wounds
    • Atrophy and gangrene
    • Low ankel-brachial index (ABI)
    Clinical manifestation
  • Intermittent claudication
    • Pain or fatigue in muscles of the lower extremity caused by walking and relieved by rest
    • Typically,symptoms are completely relieved after 2-5 minutes of inactivity
    • Reproducible
    • Does not occur at rest
    • Commonly occurs in the calf muscles
  • Ischemic rest pain
    • Caused by ischemic neuritis and tissue necrosis
    • Indicate an advanced stage of ischemia
    • Localized to the vicinity of an ischemic ulcer or pregangrenous toe
    • Aggravated by elevation of the extremity
    • Relieved sometimes when patients stand erect, as gravity aids the delivery of arterial blood
  • Ankel-brachial index (ABI)
    • Determined by dividing the pressure obtained at the ankle by the brachial arterial pressure
    • Normally, the ABI is 1.0 or greater
    • A value below 1.0 indicates occlusive disease proximal to the point of measurement
    • Rest pain usually appears when the ratio is 0.3 or lower
    • Noninvasive Hemodynamic Assessment
      • segmental pressure technique
      • Exercise (treadmill) testing
      • Limb plethysmography
    • Doppler and Duplex Ultrasonography
    • Computed tomography angiography (CTA)
    • Magnetic resonance angiography (MRA)
    • Digital subtraction angiography (DSA)
    Diagnosis
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  • Treatment
  • Nonoperative treatment
    • Lipid-lowering therapy
    • Antiaggregation therapy
      • Low MW dextrans:500ml iv qd
      • Aispirin
    • Antispasmodic,nacotic and artery dilated drugs
      • Morphine and dolantin
      • Sympathetic nerve blocker such as phentolamine
      • PGE1
    • Thrombolytic therapy
      • urokinase
  • Endovascular therapy
    • Percutaneous transluminal angiography(PTA)
      • The classic approach is to advance a guide (or a long sheath) across the stenosis over the previously placed guide wire; the vascular stent is then passed through the guide and positioned at the lesion, the guide is withdrawn, and the stent is deployed
  • Surgical treatment
    • Endarterectomy
    • Angioplasty
    • Bypass grafting
    • Lumbar sympathectomy
    • Amputation
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