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بسم الله الرحمن الرحيم

بسم الله الرحمن الرحيم. HEMODYNAMIC DISTURBANCES (Disorders of blood flow). By: Dr. Gehan Mohamed. CIRCULATORY DISTURBANCES. 1- Hyperemia 2- Congestion 3- Thrombosis 4- Embolism. 5- Ischemia 6- Infarction 7- Hemorrhage 8- Edema 9- shock. Learning objectives.

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بسم الله الرحمن الرحيم

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  1. بسم الله الرحمن الرحيم

  2. HEMODYNAMIC DISTURBANCES(Disorders of blood flow) By: Dr. Gehan Mohamed

  3. CIRCULATORY DISTURBANCES 1- Hyperemia 2- Congestion 3- Thrombosis 4- Embolism 5- Ischemia 6- Infarction 7-Hemorrhage 8- Edema 9- shock

  4. Learning objectives • Identify definition,types,causes and effect of both hyperemia & congestion. • Understand definition,causes,composition,types,sites and fate of thrombosis. • Discuss definition,causes,composition,types,sites and fate of emboli. • Understand definition,causes,typesand effect of ischemia. • Discuss definition,causes,types of infarction. • identify definition,causes and types of hemorrhage. • Understand definition,causes,types of edema. • Discuss definition and types of shock.

  5. Hyperemia & Congestion • The terms hyperemia & congestion both indicate: a local increase in volume of blood in a particular tissue. • Hyperemia is an active process resulting from increased arterial blood inflow because of arteriolar dilatation. - The affected tissue is reddened because of engorgement of tissues with oxygenated blood. • Congestion is a passive process resulting from impaired venous outflow from a tissue. - The tissue has a red-blue color due to accumulation of deoxygenated blood.

  6. HYPEREMIA • Definition: Increase in blood flow to an organ as a result of active dilatation of its arterioles. It is an active process, involving change in the muscle tone of the arterioles (active hyperemia). • Types: 1- Physiological: - hyperemia in skeletal muscles during exercise ,in the gut following a meal. 2- Pathological:e.g. in acute inflammation.

  7. VENOUS CONGESTION(Passive Hyperemia) • Definition: Increase in venous blood in an organ as result of obstruction of venous outflow. - the veins, venules, & capillaries in the organ become passively dilated (passive hyperemia). - Types: →Localized acute chronic Generalized acute chronic

  8. Acute localized venous congestion • Causes:Sudden complete venous obstruction by: thrombosis, ligature. • Effects: - Edema may occur in the tissues. - veins and capillaries can rupture → hemorrhage.

  9. Chronic localized venous congestion • Causes:Gradual incomplete venous obstruction by: Venous compression by: a tumor, enlarged lymph node or pregnant uterus. • Effects:Chronic dilatation of the veins, venules and capillaries proximal to the obstruction resulting in: 1- Edema. 2- Stasis predisposes to thrombosis. 3- Development of varicoses.

  10. Acute generalized venous congestion • Causes: - occurs in acute heart failure • Effects: rapid generalized congestion in the all viscera.

  11. Chronic generalized venous congestion • Definition:Gradual congestion affecting the whole venous system in the body. • Causes:Right sided heart failure • Effects:1- Dyspnea (due to pulmonary Congestion). 2- Chronic venous congestion in different organs. 3- Generalized edema.

  12. Thrombosis 1- Definition 2- Causes 3- Composition 4- Types 5- Sites 6- Fate

  13. Definition of thrombosis • Thrombosis is: - The formation of a solid mass (compact mass) - Composed of the blood elements. • In a blood vessel or heart. • In circulating blood. - During life.

  14. Causes of thrombosis There are 3 major factors which predispose to thrombosis (Virchow’s triad) 1- Endothelial damage 2- Slowing & turbulence of blood flow 3- Changes in blood composition

  15. Virchow triad in thrombosis

  16. Causes of thrombosis 1- Endothelial damage: - Endothelial damage may be: Mechanical, inflammatory, or degenerative. The injured endothelium becomes swollen with rough surface. 2- Staisis: There is slowing of blood flow in the heart as in mitral stenosis and in blood vessels as in varicose veins.

  17. 3- Changes in composition of blood: • ↑ platelets e.g. after operations. • ↑ fibrinogen as in pregnancy. • ↑ R.B.Cs. (polycythemia) →↑ viscosity of blood→ stasis→ thrombosis. • ↑ W.B.C. as in leukemia → ↑ viscosity of blood→ stasis→ thrombosis.

  18. Pathogenesis (Mechanism) of thrombosis: - Platelets leave the blood stream, agglutinate and adhere to the damaged endothelium. • They form laminae, which are arranged vertical to the blood stream and called lines of Zhan. - Soon, fibrin accumulates around them with red and white blood cells.

  19. Lines of Zhan

  20. Classification of thrombi • According to the color & composition of thrombi • According to the site of thrombus: • According to presence or absence of bacteria:

  21. According to the color & composition of thrombi: 1- Pale thrombus: formed only of platelets and fibrin. 2- Red thrombus: formed mainly of red cells and fibrin. 3- Mixed thrombus: containing all blood elements.

  22. According to the site of thrombus: 1- Venous thrombus (the most common): formed in veins as in varicose veins and after major abdominal operations. 2- Arterial thrombus: found in atherosclerosis and aneurysm. 3- Cardiac thrombus: found in the heart, either in the heart chambers called mural thrombus or on the heart valves called vegetations. 4- Capillary thrombi

  23. According to presence or absence of bacteria: 1- Septic thrombus: containing pyogenic bacteria. 2- Aseptic thrombi: without bacteria.

  24. 1- Venous thrombosis Thrombosis in veins is more common than other sites because of their slow blood, and thin wall. Thrombosis in veins may be either: • Thrombophlebitis • Phlebothrombosis

  25. 2- Arterial thrombosis ● Less common than venous thrombosis because of the rapid blood flow in the arteries and the thick elastic arterial wall which resists injury. ● Thrombosis occurs in arteries affected by: atherosclerosis, arteritis, & aneurysms (due to stasis, disordered blood flow & roughness of the intima). ● Arterial thrombosis → ischemia →infarction.

  26. Fate of thrombi It depends upon its size & whether it is septic or aseptic. ● Septic thrombi: Fragments by proteolytic enzymes into septic emboli →payaemic abscesses. ● Aseptic Thrombi:may undergo: - Small thrombi is dissolved and absorbed. - Large thrombus undergoes: 1- Organization ,canalization . 2-Calcification. 3- Fragmentation and embolism.

  27. Thrombus: organized & recanalized

  28. Blood Clot • A mass of blood elements formed by transformation of fibrinogen to fibrin, in stagnant blood. • The clot is dark red with a glistening smooth surface, and is not adherent to the vessel wall. • Clotting of blood may be: → Outside the CVS Inside the CVS: During life after death (e.g. in stagnant blood) (postmortem clots) red yellow

  29. Difference between thrombus and clot:

  30. EMBOLISM • DEFINITION • CAUSES & TYPES

  31. Embolism ● Definition Embolus: An insoluble (solid, liquid or gaseous) mass circulating in the blood stream. Embolism:Is the process of impaction of the embolus in a narrow vessel.

  32. Embolism ● Causes & Types: 1- Detached thrombi (thrombo-embolism) 2- Fat embolism: The fat of the bone marrow reaches the circulation after fracture of bones. 3- Air embolism: due to injury of neck & chest veins. 4- Parasitic emboli: e.g. bilharzial worms and ova. 5- Tumor emboli: groups of tumour cells penetrate the wall of blood vessels especially veins. 6- Amniotic fluid embolism during labour.

  33. 1- Detached thrombi (thromboembolism) • Sites of impaction: 1- Pulmonary embolism :the embolus get impacted in pulmonary blood vesseles. 2- Portal embolism : the embolus coming from gastrointestinal organs get impacted in the portal veins . 3- Systemic embolism : here the embolus get impacted in any blood vessel in systemic circulation.

  34. Effects of thromboemboli • Effects depends upon: 1- Size of the embolus. 2- Nature of the embolus (septic or aseptic). 3- State of the collateral circulation in the affected site. • Effects of pulmonary embolism: Big embolusMedium sized embolusSmall embolus

  35. Effects of thromboemboli • Effects depends upon: 1- Size of the embolus. 2- Nature of the embolus (septic or aseptic). 3- State of the collateral circulation in the affected site. • Effects of pulmonary embolism: Big embolusMedium sized embolusSmall embolus Acute Rt sided Heart failure Sudden death

  36. Effects of thromboemboli • Effects depends upon: 1- Size of the embolus. 2- Nature of the embolus (septic or aseptic). 3- State of the collateral circulation in the affected site. • Effects of pulmonary embolism: Big embolusMedium sized embolusSmall embolus Acute Rt sided healthy lung Heart failure no effect Sudden death

  37. Effects of thromboemboli • Effects depends upon: 1- Size of the embolus. 2- Nature of the embolus (septic or aseptic). 3- State of the collateral circulation in the affected site. • Effects of pulmonary embolism: Big embolusMedium sized embolusSmall embolus Acute Rt sided healthy lung congested lung Heart failure no effect lung infarction Sudden death

  38. Effects of thromboemboli • Effects depends upon: 1- Size of the embolus. 2- Nature of the embolus (septic or aseptic). Effects of pulmonary embolism: Big embolusMedium sized embolusSmall embolus Acute Rt sided healthy lung congested lung no effect Heart failure no effect lung infarction Sudden death

  39. Fat embolism • Rarecondition • Causes include: (1)Bone fractures and crush limb injuries. (2) Trauma to adipose tissue (infl. or burns). (3) Trauma to a grossly fatty liver. (4) Major surgery.

  40. Ischemia • Definition: Deficient arterial bloodsupply to an organ or tissue due to partial or complete occlusion of its artery. • Types:Ischemia may be either: 1- Acute ischemia (complete or sudden ischemia) 2- Chronic ischemia (partial or gradual ischemia)

  41. Acute ischemia • Causes:Sudden complete arterial occlusion by: 1- Thrombosis or embolism. (most common) 2- Surgical ligature of the artery. • Effects:: ● Sudden occlusion of arteries→ infarction .

  42. Chronic Ischemia • Causes:Incomplete arterial occlusion by: 1- Atherosclerosis. 2-Pressure on the artery by enlarged lymph node, tumor ... etc. Effects: • pain on exercise: angina pectoris, intermittent claudication. • cellular degeneration, atrophy followed by fibrosis.

  43. Infarction • Definition • Causes • Types • Pathological features • Fate • Examples

  44. Infarction • Definition An infarct is an area of coagulative necrosis (liquefactive in the brain) caused by sudden ischemia.

  45. Infarction • Causes 1- Thrombosis that may occur inside diseased arteries. 2- Embolism.

  46. Types of infarcts: 1- Red infarcts (hemorrhagic): - Occur in vascular organs as the lung, liver and intestine. - The red color is due to hemorrhage in the substance of the infarct. 2- Pale infarcts: - Are more common and occur in firm and less vascular organs as the kidney, heart and spleen. 3- Liquefactive infarcts: - Occur in the brain and spinal cord.

  47. Infarction of the kidney

  48. Infarction of the kidney

  49. Infarction of the spleen

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