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Thrombosis & embolism


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Basic Science for Optometrists

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Thrombosis & embolism

  1. 1. Thrombosis & Embolism Himal Kandel Institute of Medicine [email_address]
  2. 2. <ul><li>1. Robbins pathologic Basis of Diseases – 2000 </li></ul><ul><li>Pathology of Eye – GOH Naumann </li></ul><ul><li>Ocular Pathology – 5 th Edition </li></ul><ul><li>Muir’s Textbook of Pathology </li></ul><ul><li>Internet </li></ul>Thrombosis Embolism References...
  3. 3. <ul><li>Hemostasis – Basic concepts </li></ul><ul><li>Thrombosis </li></ul><ul><ul><li>Predisposing Factors </li></ul></ul><ul><ul><li>Basic terminologies </li></ul></ul><ul><ul><li>Morphology & Fate of Thrombi </li></ul></ul><ul><li>Embolism </li></ul><ul><ul><li>Introduction ; Terms & Terminologies </li></ul></ul><ul><ul><li>Major Types </li></ul></ul><ul><li>Clinical Correlation to Eye </li></ul><ul><ul><li>Retinal Vein Occlusion </li></ul></ul><ul><ul><li>Types of Embolization </li></ul></ul>Thrombosis Embolism Presentation Layout
  4. 4. Hemostasis <ul><li>Hemostasis is a balance of two opposing forces: clot formation and dissolution </li></ul><ul><li>Major factors involved in Hemostasis: </li></ul><ul><ul><li>Platelets, Vascular endothelium, Coagulation Process – Deposition of Fibrin </li></ul></ul><ul><ul><li>Plasmin / Fibrinolytic system – Digests Fibrin </li></ul></ul>Thrombosis Embolism
  5. 5. The 3 categories are: ( to make the study easy) <ul><ul><ul><ul><li>Primary hemostasis </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Secondary hemostasis </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Tertiary Hemostasis </li></ul></ul></ul></ul>Thrombosis Embolism
  6. 6. <ul><li>Primary hemostasis : This is defined as the formation of the platelet plug. </li></ul><ul><ul><li>Inhibitors </li></ul></ul><ul><ul><li>Natural prostacyclin and nitric oxide , which are released by endothelial cells, and bradykinin. </li></ul></ul><ul><ul><li>Acquired: Aspirin </li></ul></ul><ul><li>Secondary hemostasis : formation of fibrin through the coagulation cascade. </li></ul><ul><ul><li>Inhibitors: Natural : Antithrombin III </li></ul></ul><ul><ul><li>AT binding to thrombin – enhanced by heparin </li></ul></ul><ul><ul><li>(Used to prevent thrombosis) </li></ul></ul>Thrombosis Embolism
  7. 7. <ul><li>Tertiary hemostasis: This is defined as the formation of plasmin for breakdown of the clot. </li></ul><ul><ul><li>Drugs that inhibit fibrinolysis include epsilonaminocaproic acid and tranexamic acid </li></ul></ul>Thrombosis Embolism
  8. 8. Series of overlapping processes after the damage of a blood vessel: <ul><li>1. Vasoconstriction </li></ul><ul><ul><li>Platelets adhere to the damaged wall. </li></ul></ul><ul><ul><li>Release Serotonin </li></ul></ul><ul><ul><li>Thromboxanes </li></ul></ul><ul><li>2.Platelet plug formation </li></ul><ul><ul><li>Release of ADP </li></ul></ul><ul><ul><li>Positive feedback mechanism </li></ul></ul><ul><ul><li>Temporary seal </li></ul></ul><ul><li>3.Coagulation </li></ul><ul><ul><li>Positive feedback mechanism </li></ul></ul><ul><ul><li>Mesh of fibrin – strong </li></ul></ul><ul><ul><li>Formation of Prothrombin activator by extrinsic and intrinsic pathway </li></ul></ul>Thrombosis Embolism
  9. 9. Blood clotting factors: <ul><li>I Fibrinogen </li></ul><ul><li>II Prothrombin </li></ul><ul><li>III Tissue factor </li></ul><ul><li> ( Thromboplastin) </li></ul><ul><li>IV Calcium (Ca ++ ) </li></ul><ul><li>V Labile Factor </li></ul><ul><li>VII Stable factor </li></ul><ul><li>VIII Antihaemophilic globulin </li></ul><ul><li> (A. H. factor A) </li></ul><ul><li>IX Christmas factor </li></ul><ul><li> (A.H. factor B) </li></ul><ul><li>X Stuart Power factor </li></ul><ul><li>XI A.H. factor C </li></ul><ul><li>XII Hageman factor </li></ul><ul><li>XIII Fibrin Stabilising Factor </li></ul><ul><li>N.B.: </li></ul><ul><ul><li>There is no factor VI </li></ul></ul><ul><ul><li>Vit. K is essential for the synthesis of factors : ii vii ix & x </li></ul></ul><ul><ul><li>Their no.s represent the order in which they were discovered. </li></ul></ul>Thrombosis Embolism
  10. 10. Hemostasis Thrombosis Embolism Coagulation Casdcade
  11. 11. <ul><li>4. Fibrinolysis </li></ul><ul><ul><li>Removing blood and healing damaged blood vessels </li></ul></ul><ul><ul><li>Activators </li></ul></ul><ul><ul><li>Plasminogen Plasmin </li></ul></ul><ul><ul><li> Fibrin Breakdown products </li></ul></ul>Thrombosis Embolism
  12. 12. Control Of Coagulation: <ul><li>1. Perfect smoothness of blood vessel lining </li></ul><ul><li>2. Presence of natural anticoagulants like Heparin </li></ul><ul><li>3.Binding to Thrombin to a special thrombin receptor on the cells lining blood vessels. </li></ul>Thrombosis Embolism
  13. 13. Thrombosis <ul><li>Thrombus : an aggregation of blood factors primarily platelets & fibrin with entrapment of cellular elements, frequently causing vascular obstruction at the point of its formation </li></ul><ul><li>Thrombosis : Formation of a solid or a semisolid mass from the constituents of the blood within the vascular system within life. </li></ul>Thrombosis Embolism
  14. 14. Thrombosis <ul><li>Pathogenesis </li></ul><ul><ul><li>Primary influences predisposing to thrombosis </li></ul></ul>Thrombosis Embolism
  15. 15. Endothelial Injury <ul><li>Dominant influence </li></ul><ul><li>Any perturbation in the dynamic balance of the pro and antithrombotic effects of the endothelium can influence local clotting effects </li></ul>Thrombosis Embolism
  16. 16. <ul><li>Endothelial dysfunction d/t hemodynamic stresses of hypertension, turbulent flow over scarred valves, or bacterial endotoxins </li></ul><ul><li>Homocystinuria, Hypercholesterolemia, radiation or products absorbed from cigarette smoke may initiate endothelial injury. </li></ul><ul><li>Thrombosis in cardiac chambers, over ulcerated plaques in atherosclerotic arteries or at traumatic or inflammatory vascular injury - largely d/t endothelial injury. </li></ul>Thrombosis Embolism
  17. 17. Endothelial Enjury <ul><li>Exposure of subendothelial proteins </li></ul><ul><li>Platelets adhesion </li></ul><ul><li>Prevention from blood loss </li></ul>Thrombosis Embolism
  18. 18. Excessive adhesion of platelets - Blockage Thrombosis Embolism
  19. 19. Alterations in Normal Blood Flow ( Turbulence & Stasis) <ul><li>Turbulence </li></ul><ul><ul><li>Arterial & cardiac thrombosis </li></ul></ul><ul><ul><li>- endothelial injury or dysfunction </li></ul></ul><ul><li>Stasis and Turbulence </li></ul><ul><ul><li>Disrupt laminar flow – Platelets into contact with the endothelium </li></ul></ul><ul><ul><li>Prevent the dilution of activated clotting factors </li></ul></ul><ul><ul><li>Retard the inflow of clotting Factor inhibitors </li></ul></ul><ul><ul><li>Promote endothelial cell activation </li></ul></ul>Thrombosis Embolism
  20. 20. Contribution of Turbulence & Stasis to Thrombosis in Clinical Settings: <ul><li>Ulcerated atherosclerotic plaques – sources of turbulence </li></ul><ul><li>Abnormal aortic and arterial dilations (Aneurysms) – Favored sites of Thrombosis </li></ul><ul><li>Myocardial Infarction - regions of non-contractile myocardium – stasis </li></ul><ul><li> : Mural Thrombi </li></ul><ul><li>Mitral valve stenosis – Left arterial dilation </li></ul><ul><li>Hyper-viscosity syndromes cause small vessel stasis </li></ul><ul><li>and in sickle cell anemia deformed RBCs cause vascular occlusions </li></ul>Thrombosis Embolism
  21. 21. Hypercoagulability <ul><li>Less contribution to thrombosis </li></ul><ul><li>Causes : </li></ul><ul><ul><ul><li>Primary (Genetic) </li></ul></ul></ul><ul><ul><ul><li>Secondary (Acquired) </li></ul></ul></ul><ul><li>Inherited causes of Hypercoagulability </li></ul><ul><ul><li>Mutations in the factor v gene and Prothrombin </li></ul></ul><ul><ul><li>Polymorphisms </li></ul></ul><ul><ul><li>Inherited deficiency of anticoagulants such as Antithrombin III, Protein C or protein S </li></ul></ul>Thrombosis Embolism
  22. 22. Significances of inherited disorders: <ul><li>Individually uncommon </li></ul><ul><li>1. Mutations are usually co-inherited </li></ul><ul><ul><ul><li>( a and b together ) > ( a + b) </li></ul></ul></ul><ul><li>2.Higher risk of developing venous thrombosis </li></ul>Thrombosis Embolism
  23. 23. Acquired Thrombotic Diatheses <ul><li>More complicated and multifactorial </li></ul><ul><li>Causes: </li></ul><ul><ul><li>Stasis or venous injury </li></ul></ul><ul><ul><li>Increased hepatic secretion of many coagulation factors and reduced synthesis of antithrombin III </li></ul></ul><ul><ul><li>Release of procoagulant tumour </li></ul></ul>Thrombosis Embolism
  24. 24. Hypercoagulability seen with advancing age: <ul><li>Due to Increased susceptibility to platelet aggregation </li></ul><ul><li>Smoking and obesity promote hypercoagulability by unknown mechanisms. </li></ul>Thrombosis Embolism
  25. 25. Thrombosis <ul><li>Basic Terms and Terminologies: </li></ul><ul><li>Agonal Thrombus : Clot formed in the Heart during the process of dying </li></ul><ul><li>Antemortem Thrombus </li></ul><ul><li>Ball Thrombus </li></ul><ul><li>Milk Thrombus </li></ul><ul><li>Parietal Thrombus </li></ul><ul><li>Fibrin Thrombus </li></ul><ul><li>Hyaline Thrombus </li></ul><ul><li>Infective Thrombus </li></ul><ul><li>Primary Thrombus </li></ul><ul><li>Stratified Thrombus </li></ul><ul><li>Traumatic Thrombus </li></ul>Thrombosis Embolism
  26. 26. Retinal branched vein Thrombosis Thrombosis Embolism
  27. 27. <ul><li>Laminated Thrombus/ mixed Thrombus </li></ul><ul><li>Mural Thrombus </li></ul>Coral Thrombus Organized Thrombus Thrombosis Embolism
  28. 28. <ul><li>Annular Thrombus </li></ul><ul><li>Calcified Thrombus/ Phlebolith </li></ul><ul><li>White Thrombus </li></ul><ul><li>Blood plate / Platelet Thrombus </li></ul>Thrombosis Embolism
  29. 29. Deep Vein Thrombosis <ul><li>formation of a blood clot in a deep vein. </li></ul><ul><li>It commonly affects the leg veins, such as the femoral vein or the popliteal vein or the deep veins of the pelvis. </li></ul>Thrombosis Embolism
  30. 30. Deep Vein Thrombosis <ul><li>SIGNS AND SYMPTOMS </li></ul><ul><ul><li>pain, </li></ul></ul><ul><ul><li>swelling </li></ul></ul><ul><ul><li>redness of the leg and dilatation of the surface veins </li></ul></ul><ul><li>THERAPY </li></ul><ul><ul><li>Anticoagulation is the usual treatment </li></ul></ul>Thrombosis Embolism
  31. 31. PORTAL VEIN THROMBOSIS <ul><li>a form of venous thrombosis affecting the portal vein, which can lead to portal hypertension and reduction in the blood supply to the liver. </li></ul>Thrombosis Embolism
  32. 32. <ul><li>Causes </li></ul><ul><ul><li>pancreatitis, cirrhosis, </li></ul></ul><ul><li>Treatments </li></ul><ul><ul><li>anticoagulants, shunts, bypass surgery, and transplants. </li></ul></ul>Thrombosis Embolism
  33. 33. HEPATIC VEIN THROMBOSIS -Occlusion of hepatic vein Thrombosis Embolism
  34. 34. <ul><li>Symptoms: </li></ul><ul><ul><li>progressive abdominal pain </li></ul></ul><ul><ul><li>hepatomegaly , and later the symptoms of hepatic dysfunction </li></ul></ul><ul><li>Therapy: </li></ul><ul><ul><li>anticoagulant medication </li></ul></ul>Thrombosis Embolism
  35. 35. RENAL VEIN THROMBOSIS <ul><li>formation of a clot or thrombus obstructing the renal vein, leading to a reduction in drainage of the kidney. </li></ul><ul><li>can lead to imbalances in blood clotting factor </li></ul><ul><li>Symptoms </li></ul><ul><ul><li>blood in urine </li></ul></ul>Thrombosis Embolism
  36. 36. General Morphology / Characteristics of Arterial & venous Thrombi Thrombosis Embolism <ul><li>Characteristics </li></ul><ul><li>Arterial/ Cardiac </li></ul><ul><li>Thrombus </li></ul>Venous/Red/Stasis/Phlebo-thrombus <ul><li>Location </li></ul><ul><li>At the site of endothelial injury or turbulence </li></ul>At the sites of Stasis <ul><li>Direction </li></ul><ul><li>Retrograde dir. From pt. of attchment </li></ul>In a directon of blood flow <ul><li>Nature </li></ul><ul><li>Usually Occlusive </li></ul>Almost invariably occlusive <ul><li>Gray – white,Firmly adhered to arterial wall </li></ul><ul><li>Red/stasis thrombus </li></ul>
  37. 37. Thrombosis Embolism <ul><li>Composed </li></ul><ul><li>of: </li></ul><ul><li>Tangled mesh of platelets, fibrin, erythrocytes & degenerating leucocytes </li></ul>More enmeshed erythrocytes Common sites (In descending order) Coronory Arteries Cerebral arteries Femoral arteries Veins of Lower extremities upper extremities Less common : Periprostatic plexus Ovarian and Peri uterine veins
  38. 38. At Autopsy, post mortem clots may be confused for venous thrombi: Thrombosis Embolism Post Mortem Clots Red Thrombi Gelatinous; red cells settled by gravity More enmeshed erythrocytes, under transection reveal vague strands of pale gray fibrin Not attached to the underlying wall Firmer, almost always have a point of attachment
  39. 39. Fate of Thrombus : <ul><li>1. Propagation </li></ul><ul><li>– Accumulation of more platelets and fibrin; vessel obstruction </li></ul><ul><li>2. Embolization </li></ul><ul><li> – Dislodge and travel to other sites </li></ul><ul><li>3. Dissolution – Removed by fibrinolytic activity </li></ul><ul><li>4. Organization and recanalization </li></ul><ul><li> - May induce inflammation and fibrosis </li></ul><ul><li> - Re-establish vascular flow </li></ul>Thrombosis Embolism
  40. 40. Lab Tests to measure Coagulation and Thrombolysis <ul><li>Platelet count </li></ul><ul><li>Bleeding time </li></ul><ul><li>APTT (Activated Partial Thromboplastin Time) </li></ul><ul><ul><li>Measure of intrinsic pathway </li></ul></ul><ul><ul><li>Used to monitor Heparin Therapy </li></ul></ul><ul><li>Prothrombin Time – Used to measure effectiveness of oral anticoagulants like warfarin </li></ul><ul><li>Thrombin Time </li></ul><ul><li>Fibrin Clot Stability </li></ul><ul><li>Measurement of Fibrin degradation Products </li></ul>Thrombosis Embolism
  41. 41. Embolism <ul><li>Embolus: </li></ul><ul><li>detached intravascular solid liquid or gaseous mass that is carried by the blood to a site distant from its point of origin </li></ul><ul><li>Unless otherwise considered – thrombotic in origin </li></ul><ul><li>Results in partial or complete vascular occlusion </li></ul><ul><li>Potential consequence - Infarction </li></ul>Thrombosis Embolism
  42. 42. Thrombosis Embolism
  43. 43. Terms and Terminologies <ul><li>Thromboembolism </li></ul><ul><li>Pulmonary embolism </li></ul><ul><li>Air embolism – after trauma or surgical procedures </li></ul><ul><li>Amniotic Fluid Embolism </li></ul><ul><li>Fat / Oil embolism </li></ul><ul><li>Coronary embolism – of coronary arteries </li></ul><ul><li>Crossed / Paradoxical Embolism </li></ul><ul><li>Direct embolism – in the direction of the blood flow </li></ul><ul><li>Bland embolism – when thrombotic plug is composed of non-septic material </li></ul><ul><li>Bacillary embolism – By aggregation of bacilli. </li></ul><ul><li>Bone marrow embolism : By material from a fractured bone </li></ul><ul><li>Capillary Embolism – Blockage of capillaries with bacteria </li></ul>Thrombosis Embolism
  44. 44. <ul><li>Pulmonary embolism </li></ul><ul><li>Retinal Embolism – Central artery of the retina </li></ul>Thrombosis Embolism
  45. 45. Cerebral embolism- Of a cerebral artery Thrombosis Embolism
  46. 46. Thromboembolism <ul><li>A) Pulmonary thromboembolism </li></ul><ul><ul><li>Incidence : 20 – 25 / 100,000 hospitalized patients </li></ul></ul><ul><ul><ul><li>In 95 % instances, - venous emboli </li></ul></ul></ul><ul><ul><li>Multiple Emboli : Pts. Who had once – high risk of having more. </li></ul></ul><ul><ul><li>60 to 80 % pulmonary emboli are silent – small </li></ul></ul><ul><ul><li>When > 60 % pulmonary circulation is obstructed with emboli, - Right Heart Failure </li></ul></ul>Thrombosis Embolism
  47. 47. <ul><li># Effects: </li></ul><ul><ul><li>Depends upon size </li></ul></ul><ul><ul><li>May occlude main pulmonary artery, impact across the bifurcation (Saddle embolus ) or pass out into smaller branching arterioles </li></ul></ul><ul><li>Embolic Obstruction of : </li></ul><ul><li>Medium sized artery : </li></ul><ul><ul><li>Pulmonary haemorrhage </li></ul></ul><ul><li>Small End-arteriolar pulmonary branches: </li></ul><ul><ul><li>Infarction </li></ul></ul><ul><li>Multiple Emboli : </li></ul><ul><ul><li>Pulmonary hypertension with right heart failure </li></ul></ul>Thrombosis Embolism
  48. 48. Systemic Thromboembolism <ul><li>= within the arterial circulation </li></ul><ul><li>80% arise from intracardiac mural Thrombi </li></ul><ul><li>Major sites : </li></ul><ul><ul><li>Lower extremities (75%) </li></ul></ul><ul><ul><li>Brain (10%) </li></ul></ul><ul><li>Consequences: </li></ul><ul><ul><li>Depends upon: </li></ul></ul><ul><ul><ul><li>Extent of collatoral vascular supply in the affected tissue. </li></ul></ul></ul><ul><ul><ul><li>Tissue’s vulnerability to ischemia </li></ul></ul></ul><ul><ul><ul><li>Caliber of the vessel occluded. </li></ul></ul></ul><ul><li>In General </li></ul><ul><ul><ul><li>Infarction to tissues downstream of the obstructed vessel </li></ul></ul></ul>Thrombosis Embolism
  49. 49. Fat Embolism <ul><li>Fat released by marrow or adipose tissue injury </li></ul><ul><li>90% with severe skeletal injuries </li></ul><ul><li>Fat Embiolism Syndrome: </li></ul><ul><ul><li>Pulmonary insufficiency, neurologic symptoms, anemia and thrombocytopenia </li></ul></ul><ul><ul><li>Symptoms: </li></ul></ul><ul><ul><ul><li>Tachycardia Dyspnea </li></ul></ul></ul><ul><ul><ul><li>Neurological Symptoms: </li></ul></ul></ul><ul><ul><ul><ul><li>Irritaqbility & restlessness </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Delirium to coma </li></ul></ul></ul></ul><ul><li>Pathogenesis </li></ul><ul><ul><li>Mechanical obstruction and biochemical injury </li></ul></ul>Thrombosis Embolism
  50. 50. Air Embolism <ul><li>Can obstruct vascular flow – Distal ischemic Injury </li></ul><ul><li>Entrance </li></ul><ul><ul><li>During Obstetric procedures </li></ul></ul><ul><ul><li>As a consequence of chest wall injury ( Usu. In excess of 100 cc – clinical effect) </li></ul></ul>Thrombosis Embolism
  51. 51. <ul><li>Decompression Sickness </li></ul><ul><ul><li>Exposition to sudden changes in atmospheric pressure </li></ul></ul><ul><ul><li>People at risk: </li></ul></ul><ul><ul><ul><li>Deep sea divers, in unpressurized aircraft in rapid descent (??) </li></ul></ul></ul><ul><li>Bends </li></ul><ul><ul><li>Rapid formation of gas bubbles with in the skeletal muscle & supporting tissues. </li></ul></ul>Thrombosis Embolism
  52. 52. <ul><li>Effects: </li></ul><ul><ul><li>May induce local ischemia in brain, Heart etc. </li></ul></ul><ul><ul><li>oedema in lungs leading to respiratory distress – Chokes </li></ul></ul><ul><ul><li>Haemorrhages and focal atelectasis or emphysema </li></ul></ul><ul><li>Treatment: </li></ul><ul><ul><li>Place the individual in compression chamber ( ??? ) </li></ul></ul><ul><li>Caisson Disease </li></ul><ul><ul><li>More chronic form of decompression sickness </li></ul></ul><ul><ul><li>Persistence of gas emboli in the skeletal system leads to multiple foci of ischemic necrosis </li></ul></ul><ul><ul><li>Common sites: </li></ul></ul><ul><ul><ul><li>Heads of Femur, Tibia and Humeri </li></ul></ul></ul>Thrombosis Embolism
  53. 53. Amniotic Fluid Embolism <ul><li>Grave but uncommon complication of labor & immediate postpartum period </li></ul><ul><li>Underlying Cause : </li></ul><ul><ul><li>Infusion of amniotic fluid or fetal tissue into maternal circulation through a tear in the placental membranes or rupture of uterine veins </li></ul></ul>Thrombosis Embolism
  54. 54. <ul><ul><ul><li>Mortality rate 20 – 40% </li></ul></ul></ul><ul><ul><ul><li>Not managed well </li></ul></ul></ul><ul><ul><ul><li>Onset characterized by sudden severe dyspnea, cyanosis & hypotensive shock followed by Seizures and coma </li></ul></ul></ul><ul><ul><ul><li>Marked pulmonary edema </li></ul></ul></ul><ul><ul><ul><li>Diffuse alveolar damage </li></ul></ul></ul><ul><ul><ul><li>Systemic fibrin thrombi </li></ul></ul></ul>Thrombosis Embolism
  55. 55. Thrombosis Embolism Clinical Correlation to EYE
  56. 56. Thrombosis & Embolism <ul><li>Most common causes of Occlusive Disorders of Retina </li></ul><ul><ul><li>May arise from large vessels of neck or may be cardiac in origin </li></ul></ul><ul><ul><li>Common in pt.s with Hypertension & other cardiovascular diseases </li></ul></ul>Thrombosis Embolism
  57. 57. Retinal Artery Occlusion <ul><li>Usu. Unilateral </li></ul><ul><li>CRAO – Obstruction at Lamina Cribrosa </li></ul><ul><li>BRAO – Lodgement of embolus at bifurcation </li></ul><ul><li>Management </li></ul><ul><ul><li>Rx : Unsatisfactory </li></ul></ul><ul><ul><li>Immediate lowering of IOP by IV mannitol & intermittent ocular massage </li></ul></ul><ul><ul><li>Anticoagulants </li></ul></ul>Thrombosis Embolism
  58. 58. Retinal Vein Occlusion <ul><li>More common than artery occlusion </li></ul><ul><li>CRVO – Non Ischemic ( Venous stasis retinopathy)-75% </li></ul><ul><ul><ul><ul><ul><li>Mild to moderate vision loss </li></ul></ul></ul></ul></ul><ul><ul><ul><li> - Ischemic (Hemorrhagic retinopathy) </li></ul></ul></ul><ul><ul><ul><ul><ul><li>Acute complete occlusion of central retinal vein; marked sudden visual loss </li></ul></ul></ul></ul></ul><ul><ul><ul><li>Treatment : Panretinal Photocoagulation </li></ul></ul></ul><ul><li>BRVO – More Common Than CRVO </li></ul><ul><ul><li>Vision – affected only when macular area is involved </li></ul></ul><ul><ul><ul><li>Treatment : Grid retinal Photocoagulation </li></ul></ul></ul>Thrombosis Embolism
  59. 59. <ul><li>Retinal Vein Thrombosis - central retinal vein elderly; with Glaucoma , Diabetes Mellitus , and Hypertension . </li></ul><ul><li>Symptom: Painless visual loss </li></ul><ul><li>Examination: </li></ul><ul><ul><li>the retinal veins appear distended and tortuous, </li></ul></ul><ul><ul><li>the fundus of the eye appears congested and swollen, </li></ul></ul><ul><ul><li>numerous hemorrhagic areas may be seen on the retina . </li></ul></ul><ul><ul><li>neo-vascularization </li></ul></ul><ul><ul><li>secondary (neovascular) Glaucoma can occur weeks after the occlusion. </li></ul></ul><ul><li>Tests : fluorescein Angiography </li></ul><ul><li>Procedures (such as photocoagulation to remove new vessels formed) can prevent secondary neovascular Glaucoma . </li></ul>Thrombosis Embolism
  60. 60. Embolization In Eye <ul><li>Microemboli are frequent causes of retinal arterial emboli </li></ul><ul><li>Sometimes ophthalmoscopically visible and may provide a clue to the diagnosis of the underlying disease </li></ul><ul><li>Types of Emboli </li></ul><ul><ul><li>1. Calcium Emboli </li></ul></ul><ul><ul><li>2. Cholesterol Emboli </li></ul></ul><ul><ul><li>..... </li></ul></ul>Thrombosis Embolism
  61. 61. <ul><li>Calcium Emboli </li></ul><ul><li>Most commonly arise from the excrescences on heart valves affected with rheumatic heart disease or derived from calcified atheromatous plaques </li></ul><ul><li>Frequently seen after heart and vascular surgery </li></ul><ul><li>Can be recognized as white foci within the arterial channels most commonly in the major branches near the optic nerve </li></ul><ul><li>Calcific emboli within the central artery: </li></ul><ul><ul><li>Not visible ophthalmoscopically </li></ul></ul><ul><ul><li>Visible histopathologically </li></ul></ul>Thrombosis Embolism
  62. 62. 2. Cholesterol Emboli <ul><ul><li>From atheromatous plaques of the carotid artery system </li></ul></ul><ul><ul><li>In the ocular Fundus – Visible ophthalmoscopically; multiple yellow shining flecks within retinal arterioles, particularly concentrated at bifurcations </li></ul></ul><ul><ul><li>Dislodgement further into retinal periphery – Frequent </li></ul></ul>Thrombosis Embolism
  63. 63. 3. Fat Emboli <ul><li>Fat emboli usually occur after fracture of long bones. </li></ul><ul><li>Indirect Traumatic Retinopathy </li></ul><ul><ul><li>An episode of ischemic micro infarction of the retina with cotton wool spots, retinal edema and hemorrhages </li></ul></ul><ul><ul><li>d/t embolization of multiple fragments of bone marrow fat into the central and peripheral branches of the central retinal artery </li></ul></ul>Thrombosis Embolism
  64. 64. 4. Thrombocyte – Fibrin emboli <ul><li>Gray </li></ul><ul><li>Difficult to see ophthalmoscopically </li></ul><ul><li>After myocardial infarction or open heart surgical procedures </li></ul>Thrombosis Embolism
  65. 65. 5. Myxoma Emboli <ul><li>Histopathologically :- Star shaped tumor cells embedded within the mucoid matrix causing occlusion of the vascular lumen </li></ul><ul><li>Should be suspected in young patients who suffer from multiple retinal arterial occlusions </li></ul><ul><li>In young patients; after myocarditis, it is the commonest cause of multiple ischemic infarction </li></ul><ul><li>Mistaken for retinal vasculitis </li></ul>Thrombosis Embolism
  66. 66. Bacterial & Mycotic Emboli: <ul><li>Bacterial </li></ul><ul><ul><li>Have become rare </li></ul></ul><ul><ul><li>Causes : Endocarditis, Septicemia </li></ul></ul><ul><ul><li>Pathognomic Sign : Roth Spot </li></ul></ul><ul><ul><li>Histopathologically, the lesions consist of perivascular accumulation of leucocytes with in surrounding areas of hemorrhages </li></ul></ul><ul><li>Mycotic – also rare </li></ul><ul><ul><li>Complication of long standing intravenous therapy and in immunocompromised patients. </li></ul></ul>Thrombosis Embolism
  67. 67. Experimental and Iatrogenic Emboli <ul><li>Experimental </li></ul><ul><ul><li>Using Latex or Glass spheres </li></ul></ul><ul><ul><li>Injection of air or fibrin </li></ul></ul><ul><li>Iatrogenic </li></ul><ul><ul><li>By tiny metallic foreign bodies derived from heart-lung machines </li></ul></ul><ul><ul><li>Have been discovered in the retinal capillary tree </li></ul></ul><ul><ul><li>Small particulate micro emboli have also been reported after injection of crystalline corticosteroids locally </li></ul></ul>Thrombosis Embolism
  68. 68. In brief… <ul><li>Emboli in the visual system can cause </li></ul><ul><ul><li>amaurosis fugax; </li></ul></ul><ul><ul><li>visual field defects, </li></ul></ul><ul><ul><li>cranial nerve palsies, </li></ul></ul><ul><ul><li>central or branched retinal vessel occlusion, </li></ul></ul><ul><ul><li>hypotensive retinopathy (Venous stasis retinopathy) </li></ul></ul><ul><ul><li>narrowed retinal arterioles, </li></ul></ul><ul><ul><li>neovascularization of the iris, optic disc or neural retina </li></ul></ul><ul><ul><li>& the ocular ischemic syndrome </li></ul></ul>Thrombosis Embolism