بسم الله الرحمن الرحيم

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

4. 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.

5. HYPEREMIA • Definition: Increase in blood flow to an organ as 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. - hyperemia 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). - although there is excess blood in the tissue, the blood flow is slow & reduced. • Types: →Localized acute chronic Generalized acute chronic

8. Acute localized venous congestion • Causes:Sudden complete venous obstruction by: thrombosis, ligature, strangulation, or twisting of the pedicle of a movable organ. • Effects: 1- Rapid severe distention of the veins and capillaries which may rupture → hemorrhage. 2- Edema occurs rapidly in the tissues. 3- In intestine: infarction & gangrene may occur

9. Chronic localized venous congestion • Causes:Gradual incomplete venous obstruction by: 1- Venous compression by: a tumor, enlarged lymph node or pregnant uterus. 2- Liver cirrhosis or fibrosis → congestion in mesenteric & splenic veins. 3- Left ventricular failure → congestion of pulmonary veins • Effects:Chronic dilatation of the veins, venules and capillaries proximal to the obstruction resulting in: 1- Edema. 2- Stasis predisposes to thrombosis 3- Gradual opening of the collateral veins. 4- Development of varicoses (e.g. oesophageal varices)

10. Acute generalized venous congestion • Causes: - occurs in acute heart failure • Effects: All viscera show acute congestion (rapid generalized congestion)

11. Chronic generalized venous congestion • Definition:Gradual congestion affecting the whole venous system in the body. • Causes:Right sided heart failure • Effects:1- Hypoxia & cyanosis. 2- Dyspnea (due to pulmonary Congestion). 3- Generalisedoedema. 4- Chronic venous congestion in different organs.

12. Effects of chronic generalized venous congestion • Hypoxia & Cyanosis: - Hypoxia is due to defective oxygenation of blood in the congested lungs. - Cyanosis is due to increased amounts of reduced hemoglobin (due to stasis). • Dyspnea: due to pulmonary congestion. • Generalized edema (cardiac edema). • Effects in different organs.

13. Thrombosis 1- Definition 2- Causes 3- Composition 4- Types 5- Sites 6- Fate 7- N.B.

14. 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.

15. 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

16. Virchow triad in thrombosis

17. Causes of thrombosis 1- Endothelial damage: - This is the most important factor in thrombus formation. - 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.

18. 3- Changes in composition of blood: • ↑ platelets e.g. after operations. • ↑ fibrinogen as in pregnancy. • ↑ R.B.Cs. (polythycaemia) →↑ viscosity of blood→ staisis→ thrombosis. • ↑ W.B.C. as in leukaemia→ ↑ viscosity of blood→ staisis→ thrombosis.

19. 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.

20. Lines of Zhan

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

22. 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.

23. 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

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

25. 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

26. Thrombophlebitis ● Thrombosis is caused by inflammation of venous wall. ● Two types occur: 1- Septic thrombophlebitis: - Occurs in veins draining septic lesions. - e.g.: appendicular vein in case of acute appendicitis. - suppuration of the thrombus causes its softening - fragments of infected thrombus may break away → pyaemia 2-Aseptic thrombophlebitis: - Inflammation is caused by factors other than bacteria. - e.g.: trauma and radiations. - a small fixed aseptic thrombus occurs.

27. Phlebothrombosis • This is thrombosis in non-inflamed veins. • The thrombus may propagate and may fragment causing pulmonary embolism. • Examples include: 1- Thrombosis in varicose veins due to stasis. 2- Thrombosis in calf veins (DVT) in chronic cardiac pts confined to bed (stasis & compression of calf ms). 3- Thrombosis in pelvic & femoral veins after labour or operations (↑platelets, bed recumbence, surgical injury).

28. 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.

29. Fate of thrombi It depends upon its size & whether it is septic or aseptic. ● Septic thrombi: Fragments by proteolytic enzymes into septic emboli → pyaemic abscesses. ● Aseptic Thrombi:may undergo: - Small thrombi is dissolved and absorbed. - Large thrombus undergoes: 1- Organization (fibrosis) 2- Organization & canalization 3- Calcification 4- Fragmentation and embolism.

30. Thrombus: organized & recanalized

31. 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

32. Difference between thrombus and clot:

33. EMBOLISM • DEFINITION • CAUSES & TYPES

34. 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.

35. 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.

36. 1- Detached thrombi (thromboembolism) • Sites of impaction: 1- Pulmonary embolism 2- Portal embolism 3- Systemic embolism 4- Paradoxical embolism i.e.the embolus coming with venous return to be impacted in lung causing pulmonary embolism but instead of that it will pass from right side of heart to its left side through septal defect then pass to systemic circulation.

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.

38. 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

39. 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

40. 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

41. 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

42. 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 no effect Heart failure no effect lung infarction Sudden death

43. Air embolism • Rare and may result from: 1- Injury to the large neck veins. Air is sucked by the negative pressure in the thorax. 2- During cardiothoracic surgery → air may enter veins 3- In criminal abortion → air may pass into uterine veins 4- Caisson’s disease(decompression sickness): - In deep dives, the high pressure increases the amount of gasses dissolved in the blood of the divers. - If decompression is done rapidly, gases esp. nitrogen form emboli in the blood vessels. - Small amount of air is harmless, but 50-100 cc. interferes with cardiac contraction and causes acute heart failure.

44. 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.

45. 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)

46. Acute ischemia • Causes:Sudden complete arterial occlusion by: 1- Thrombosis or embolism. (most common) 2- Surgical ligature of the artery. 3- Twisting of the pedicle of a movable organ e.g. intestinal loop. 4- Arterial spasm as in ergot poisoning. • Effects:depends on the efficiency of collaterals: ● Sudden occlusion of end arteries or arteries with poor collaterals → infarction or gangrene. ● Sudden occlusion of arteries with efficient collaterals may not cause tissue damage.

47. Chronic Ischemia • Causes:Incomplete arterial occlusion by: 1- Atherosclerosis. 2-Pressure on the artery by enlarged lymph node, tumor ... etc. 3- End arteritis oblitrans as in chronic inflammation. • Effects:depends on the efficiency of collaterals: ● With inefficient collaterals: - pain on exercise: angina pectoris, intermittent claudication.. - cellular degeneration, atrophy followed by fibrosis. ● With efficient collaterals no tissue damage occurs.

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

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

50. Infarction • Causes 1- Thrombosis that may occur inside diseased arteries. 2- Embolism. 3- Strangulation or twisting of an organ as in loops of intestine, testes or ovaries.