Lecture 5.1 - Thrombosis and Embolism
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Questions and Answers

What is the primary factor that prevents platelet thrombi from growing in swift blood flow?

  • The presence of von Willebrand factor/factor VIII complex
  • The absence of endothelial damage
  • The washing away of platelets by the current (correct)
  • The increased coagulation factors in the blood

    • Which of the following is a risk factor for thrombosis due to changes in blood constituents?

  • Hypertension
  • Pregnancy (correct)
  • Surgery
  • Myocardial infarction

    • What is the primary location where thrombosis is more frequent due to slow or turbulent flow?

  • Veins (correct)
  • Capillaries
  • Lymphatic vessels
  • Arteries

    • Which of the following is a situation where endothelial damage can occur, leading to thrombosis?

    <p>After a myocardial infarction</p> Signup and view all the answers

    What is the name of the triad that forms when two or more of the following factors are present: changes in the intimal surface of the vessel, changes in the pattern of blood flow, and changes in the blood constituents?

    <p>Virchow's Triad</p> Signup and view all the answers

    What is the result of endothelial damage in the presence of swift blood flow?

    <p>Platelet thrombi generally don't grow</p> Signup and view all the answers

    Which of the following is a risk factor for thrombosis due to changes in the pattern of blood flow?

    <p>Cardiac failure</p> Signup and view all the answers

    What is the result of the combination of endothelial damage and blood stasis?

    <p>A thrombus will form</p> Signup and view all the answers

    What is the main component of a venous thrombus, apart from RBCs?

    <p>Fibrin</p> Signup and view all the answers

    What is the characteristic appearance of an arterial thrombus?

    <p>Pale with lines of Zahn</p> Signup and view all the answers

    What is the outcome of thrombosis that involves the formation of new channels lined with endothelium?

    <p>Recanalisation</p> Signup and view all the answers

    What is the term for the process by which a part of the thrombus breaks off and embolises?

    <p>Embolisation</p> Signup and view all the answers

    What is the condition under which lysis of the thrombus is more likely to occur?

    <p>When the thrombus is relatively small</p> Signup and view all the answers

    What is the characteristic of a thrombus that forms in the large veins of the lower limbs?

    <p>It is particularly dangerous</p> Signup and view all the answers

    What is the primary risk factor for propagation of thrombosis?

    <p>Original thrombus</p> Signup and view all the answers

    What is the result of ingrowth of fibroblasts and small capillaries in the organisation of thrombosis?

    <p>Lumen remains obstructed</p> Signup and view all the answers

    What is the process by which new vessels form to restore blood flow in thrombosis?

    <p>Recanalisation</p> Signup and view all the answers

    What is the result of fragmentation of the thrombus in thrombosis?

    <p>Embolisation</p> Signup and view all the answers

    What is the clinical effect of thrombosis in the uteroplacental vasculature?

    <p>Recurrent miscarriages</p> Signup and view all the answers

    What is the common clinical effect of thrombosis in the arteries?

    <p>All of the above</p> Signup and view all the answers

    What is the process by which thrombus changes to scar tissue?

    <p>Organisation</p> Signup and view all the answers

    What is the result of thrombosis in the atheromatous carotid arteries?

    <p>Cerebrovascular accident</p> Signup and view all the answers

    Study Notes

    Thrombosis

    • Defined as a solidification of blood contents that forms within the vascular system, resulting in a solid mass in the lumen of the vessels (occluded lumen)

    Virchow's Triad

    • Formed by three factors, with only two necessary to form a thrombus:
      • Changes in the intimal surface of the vessel
      • Changes in the pattern of blood flow (sluggish, turbulent blood flow, etc.)
      • Changes in the blood constituents (e.g., pregnancy, surgery, smokers, inherited thrombophilias)

    Endothelial Damage

    • Occurs in situations including:
      • After myocardial infarction
      • Secondary to haemodynamic stress of hypertension
      • On scarred heart valves
      • After trauma or surgery
      • In inflammation
      • On the surface of atherosclerotic plaques when they break open
    • Platelets adhere to exposed von Willebrand factor/factor VIII complex, and if blood flow is slow, a thrombus will form

    Flow and Thrombosis

    • Abnormal blood flow (slow or turbulent) gives platelets a better chance to stick to the endothelium and clotting factors a chance to accumulate
    • Thrombosis is more frequent in veins due to slower flow and the formation of eddies and pockets of stagnant blood

    Propagation

    • Progressive spread of thrombosis
    • Original thrombus is a risk factor for propagation

    Organisation

    • Ingrowth of fibroblasts and small capillaries (similar to granulation tissue)
    • Lumen remains obstructed
    • Scar formation takes place (thrombus changes to scar tissue)

    Recanalisation

    • Occurs by the ingrowth of new small vessels
    • The new vessels join up to restore blood flow, at least partially

    Embolisation

    • Caused by fragmentation of the thrombus
    • Results in infarction at a distant site
    • Embolisation doesn't happen in veins as the diameter of veins increases as you get closer to the heart, so embolism can still travel through

    Thrombo-emboli

    • From systemic veins: pass to the lungs to form pulmonary emboli
    • From the heart: pass via the aorta to renal, mesenteric, and other arteries
    • From atheromatous carotid arteries: pass to the brain to cause stroke
    • From atheromatous abdominal aorta: pass to arteries of the legs

    Effects of Thrombosis

    • The most common clinical effects include:
      • Occlusion of an artery at the site of the thrombus resulting in ischaemia and infarction
      • Embolisation of part of the thrombus resulting in occlusion of an artery distant to the site of the thrombus
      • Congestion and oedema in the venous bed resulting in pain and sometimes skin ulceration
      • Repeated miscarriages due to thrombosis of the uteroplacental vasculature

    Appearance of Thrombi

    • Arterial:
      • Pale
      • Lines of Zahn (alternating lines of pink and white/yellow)
      • Lower cell content
    • Venous:
      • Soft
      • Red (due to RBCs)
      • Gelatinous
      • Higher cell content

    Outcome of Thrombosis

    • Lysis: the thrombus is dissolved
    • Propagation: the thrombus grows
    • Organisation: the thrombus undergoes fibrous repair and forms a fibrous scar on the wall of the vessel
    • Recanalisation: happens in an occluding thrombus, new channels lined with endothelium run through the occlusion and restore blood flow
    • Embolisation: a part of the thrombus breaks off and embolises

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    Lecture 5.1 - Thrombosis and Embolism PDF

    Description

    Learn about thrombosis, its formation and Virchow's Triad, which consists of three factors that contribute to thrombus formation. Understand the changes in the intimal surface of the vessel and pattern of blood flow that lead to thrombosis.

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