ottava lezione disturbi dell’emostasi

1. ottava lezione disturbi dell’emostasi

2. classificazione dei disordini emorragici • difetto coagulativo • difetto piastrinico • difetto parete vascolare

6. difetto coagulativo Cause congenite Malattia di von Willebrand; Emofilia A (deficit fattore VIII); Emofilia B (deficit fattore IX); Deficit qualitativi o quantitativi del fibrinogeno; Emofilia C (deficit fattore XI); Deficit di fattore VII; Deficit di fattore XII, V, XIII, X e II; Deficit combinati di fattori V + VIII, VII + VIII, VIII + IX.

7. difetto coagulativo • Cause acquisite • Deficit vitamina K • Insufficienza epatica • Coagulazione intravascolare disseminata (CID) • Deficit di fibrinogeno • 1. terapia con L-asparaginasi • 2. morso di serpente • Anticorpi anticoagulanti circolanti (anti-fattore VIII) • 1. tumori • 2. LES • 3. idiopatici • 4. post-partum

8. fattore di von Willebrand Factor (vWF) • sintetizzato nei megacariociti e nelle cellule endoteliali • (MW 230.000 kD) • formazione di multimeri a livello plasmatico • (MW 1x106 - 10x106 kD) • . • carrier del fattore VIII a livello plasmatico • multimeri ad alto peso molecolare • molto efficaci nel mediare l’adesione piastrinica • preponderanti nelle cellule endoteliali e nel subendotelio;

9. Struttura vWF

12. vonWillebrand Disease vonWillebrand Disease (VWD) is the most common inherited bleeding disorder, with an estimated incidence as high as 1 in 100 to 1000. Classification: There are three main types of VWD. 1. Type I - by far the most common form. Inheritance is autosomal dominant. Most patients are heterozygotes. Mild to moderate decrease in plasma VWF concentrations. Most patients have mild disease with excessive bleeding after surgery or trauma. 2. Type II - Rare, patients have normal levels but dysfunctional VWF, leading to decreased VWF activity. IIa - deficiency in high and medium molecular weight VWF due to either inability to secrete them from the megakaryocyte or endothelial cell or due to proteolysis as soon as they enter the circulation. IIb - also a deficiency in high molecular weight VWF, but due to inappropriate binding of VWF to platelets. 3. Type III - Severe decrease in plasma VWF levels. Most individuals are the offspring of two Type I patients and therefore homozygous.

13. Options for therapy: 1. Cryoprecipitate(which is rich in VWF) or Factor VIII concentrates (which contain some high molecular weight VWF) For minor bleeding such as epistaxis, a single dose may suffice. Perioperatively, either must be given twice a day until 48 - 72 hours post-op 2. DDAVP (desmopressina) Triples the plasma VWF in normal patients and in those with mild VWD. Not effective in Type III, because there is no VWF to begin with. Should do trial to ensure that patient will respond before actually using DDAVP for treatment. Effects last 2-3 days before tachyphylaxis can occur 3. Note: Aspirin is totally contraindicated in patients with VWD because of inhibitory effect on platelet aggegration. This would exacerbate VWD. There is an acquired form of VWD, which occurs when antibodies inhibit VWF or when tumors (such as lymphoid tumors) that adsorb VWF on to their surface are present.

14. Malattia di von Willebrandt I.Epidemiology A .Most common inherited bleeding disorder B.Mild bleeding disorder (often undiagnosed) C.Autosomal dominant disorder II.Pathophysiology A.Von Willebrand factor mediates platelet adhesion B.vWF Deficiency results in mucocutaneous bleeding III.Symptoms and Signs A.Severe Menorrhagia (common presentation in women) B.Postpartum Hemorrhage several days after delivery IV.Labs A.Lab Results vary over time in each patient B.Partial Thromboplastin Time (PTT) prolonged C.Bleeding Time prolonged V.Management A.Synthetic hormone arginine vasopressin (DDAAVP) 1.Indicated for surgery or trauma B.Cryoprecipitate

15. I. Review - Factor VIII(FVIII): Factor VIII is the precursor to Factor VIIIa, which catalyzes the activation of Factor IX to IXa. Protein C and Protein S function to inactivate Factor VIIIa. FVIII normally circulates in the plasma bound to vonWillebrand Factor. This association has several functions including protecting FVIII from proteolysis, enhancing FVIII synthesis, and concentrating FVIII at the site of active hemostasis. FVIII is a dimer with A,B,and C domains on each monomer. When activated, it becomes a trimer which has lost most of the B domain. II. Hemophilia A A. Inheritance is X-linked recessive. B. Incidence is 1 in 5000 live male births. C. Mechanism - quantitative deficiency in the synthesis of FVIII

16. D. Clinical features 1. Suspect hemophilia in any male who has history of extensive bleeding after trauma or spontaneous bleeding into joints and muscles. 2. Excessive bleeding at time of circumcision 3. Severity of bleeding depends on level of FVIII Severe hemophilia - FVIII < 1% - at risk for spontaneous hemorrhages and soft tissue bleeds. Moderate hemophilia- FVIII 1-5% Mild hemophilia- FVIII > 5% - little risk for spontaneous bleeds but may bleed excessively following surgery or trauma. E. Lab abnormalities 1. Prolongation of aPTT (variable with degree of hemophilia) 2. Decreased FVIII acitvity 3. Normal vonWillebrand Factor and Ristocetin cofactor 4. Normal bleeding time

17. F. Management 1. Avoid aspirin 2. Mild hemophilia - prophylaxis with desmopressin (DDAVP) before dental procedures or minor surgery. Desmopressin induces release of stored FVIII and vonWillebrand Factor. If the increase in FVIII activity is not sufficient, administer FVIII concentrates. Antifibrinolytics such as aminocaproic acid may be helpful. For major surgery, give FVIII concentrates perioperatively. 3. Moderate and Severe hemophilia - give FVIII concentrate at the earliest sign of bleeding. Desmopressin will not be helpful because these patients do not have enough stored FVIII. 4. The amount of FVIII to give depends on the severity of the bleed. Major bleeding or surgery - 50-100% replacement Hemarthroses - 25% replacement For major bleeding, treat for 10 days. To prevent hemarthosis induced joint destruction, some propose prophylactic FVIII concentrates three times a week to maintain trough levels of FVIII activity between 1-3%.

20. Il fattore VIII ricombinante è disponibile per • Prima priorità - Pazienti mai precedentemente trattati • Seconda priorità - Pazienti HCV e HIV negativi • Terza priorità - Pazienti con infezione da HIV • Quarta priorità - Pazienti con infezione da HCV

21. III. Factor VIII Inhibitors A. Acquired, not inherited B. They are antibodies that neutralize FVIII and can either be alloantibodies against exogenous FVIII or autoantibodies. C. They are a serious complication of FVIII treatment in the severe hemophiliac population where the incidence of developing an inhibitor is 15-20%.. D. Inhibitors can also occur in non-hemophiliac patients in the setting of: 1. Idiopathic conditions - i.e. otherwise normal elderly individuals. 2. Autoimmune disorders such as systemic lupus erythematosus, rheumatoid arthritis, etc. 3. Malignancies such as lymphoproliferative disorders, lymphomas, and solid tumors. 4. Drug reactions to penicillin, chloramphenicol, phenytoin, etc. 5. Pregnancy and the postpartum state

22. E. Risk factors for development of antibodies 1. Severity of hemophilia: Patients with severe hemophilia are at much higher risk because they are exposed to more FVIII therapy. 2. Age of the patient and degree of FVIII exposure: 15 -20% of heavily treated hemophiliac children develop antibodies by the age of 20. 3. Genetic defect that results in the absence of synthesis of FVIII protein: These patients are at greater risk for developing antibodies after treatment with FVIII concentrates. F. Characteristics of FVIII antibodies 1. The majority of FVIII inhibitors are IgG antibodies, more specifically of the IgG4 subclass. 2. There are two main types of antibodies Type I antibodies - seen in classic hemophiliacs. Their inhibition of FVIII follows linear kinetics. Type II antibodies - these are the autoantibodies and they exhibit a more complex pattern of inhibition. 3. Antibodies are identified by their ability to neutralize FVIII at 37 degrees Celcius after incubation for 2-3 hours.

23. G. Diagnosis 1. Clinical suspicion a. Whenever classic hemophiliacs show a decreased response to FVIII replacement therapy, screen for FVIII inhibitor. b. Acquired inhibitors should be suspected when non-hemophiliac patients present with spontaneous hematomas with sudden, life-threatening bleeds. 2. Laboratory information a. aPTT - will be prolonged and will not correct upon mixing patient's plasma with normal plasma. b. However, the presence of FVIII inhibitor can be confirmed by adding inhibitor plasma with normal plasma and then assaying all the residual clotting factors in the normal plasma. c. Quantification of the inhibitor can be done with the Bethesda Assay

24. H. Characteristics of patients - Grouped as low responders or high responders 1. Low responders are patients who usually have low titers of inhibitor (less than 10 BU), which does not increase after challenge with FVIII. Therefore, these patients do not show significant anamnestic response with subsequent FVIII treatments. 2. High responders are mostly hemophiliacs who develop a high titer of inhibitor when challenged with FVIII.

25. I. Management • Low responders • a. Mild bleeding episodes - options include: • Prothrombin complexes - contain all Vitamin K-dependent clotting • factors (II, VII, IX, X, and thrombin) • Activated prothrombin complexes - contain activated clotting factors • Recombinant FVIII • The first two are bypass agents because they do not contain FVIII. • Other bypass agents include Factor VIIa and Factor IXa, which • bypass the necessity for FVIII mediated activation of FIX. However, • these two are under clinical trials currently and may be associated • with increased risk of thrombosis. • b. Severe bleeding - options include: • High dose human Factor VIII • Porcine Factor VIII (see above) • Factor VIIa or another by pass agent

26. High responders a. Mild bleeding episodes - considerations include: Avoiding FVIII products to prevent an anamnestic response, which would preclude this treatment from being a treatment option in the event of future bleeding episodes. b. Severe bleeding episodes Use human or porcine FVIII until an anamnestic response occurs, after which a bypass agent must be used instead. 5. Alternative therapies a. Immunosuppressive agents to control antibody production Corticosteroids Cyclophosphamide Azithoprine b. Intravenous gamma globulin - in the hope that some antibodies in this pooled sample may be directed against the inhibitor c. Induction of immune tolerance to suppress inhibitor formation by administration of FVIII on a continuous basis.

27. Factor IX Deficiency I. Review - Factor IX(FIX): Factor IX is the precursor to Factor IXa, which is a Vitamin K-dependent serine protease that catalyzes the activation of Factor X to Xa FIX normally circulates in the plasma in an inactive form. Factor VIIIa plays a role in the enzymatic activation of FIX to FIXa. FIX can also be activated directly by Tissue Factor - Factor VIIa complex in the extrinsic pathway. FIXa is a serine protease. II. Hemophilia B (Christmas Disease) A. Inheritance is X-linked recessive. B. Incidence is 1 in 30,000 live male births. C. Mechanism - quantitative deficiency in the synthesis of FIX

28. D. Clinical features - identical to Hemophilia A 1. Suspect hemophilia in any male who has history of extensive bleeding after trauma or spontaneous bleeding into joints or muscles. 2. Bleeding at time of circumcision 3. Severity of bleeding depends on level of FIX Severe hemophilia - FIX < 1% - at risk for spontaneous hemorrhages and soft tissue bleeds. Moderate hemophilia - FIX 1-5% Mild hemophilia - FIX > 5% - little risk for spontaneous bleeds but may bleed excessively following surgery or trauma. E. Lab abnormalities 1. Prolongation of aPTT (variable with degree of hemophilia) 2. Decreased FIX acitvity 3. Normal bleeding time and thrombin time.

31. F. Management 1. Avoid aspirin 2. Mild hemophilia - Antifibrinolytics such as aminocaproic acid may be helpful. For major surgery, give FIX concentrates perioperatively. For surgery, the FIX activity should be maintained between 30-60%. Higher levels may lead to thrombosis (see below). 3. Moderate and Severe hemophilia - give FIX concentrate at the earliest sign of bleeding. 4. Available forms of FIX FIX concentrates Prothrombin complex - contains the inactive Vitamin K-dependent clotting factors Activated prothrombin complex - contains the active Vitamin K-dependent clotting factors. Fresh frozen plasma - contains FIX. Limited by the fact that unless exchange transfusion is done, sufficient FFP cannot be given to patients with severe hemophilia to raise FIX levels sufficiently in order to prevent or control bleeding episodes.

32. CID (Coagulazione Intravascolare Disseminata) • A. Infection • B. Neoplastic disease • 1. Mucin-Secreting adenocarcinoma • 2. Promyelocytic Leukemia • 3. Prostate Cancer • 4. Lung Cancer • C. Tissue Damage • 1. Trauma • 2. Surgery (e.g. Prostate Surgery) • 3. Heat Stroke • 4. Burn injury • 5. Dissecting aneurysm • D. Obstetrical Complication • 1. Abruptio Placentae • 2. Amniotic Fluid Embolism • 3. Retained fetal products • 4. Eclampsia • E. Immunologic Disorders • 1. Immune complex disorders • 2. Allograft rejection • 3. Incompatible blood transfusion • 4. Anaphylaxis • F. Metabolic • 1. Diabetic Ketoacidosis • G. Miscellaneous • 1. Shock • 2. Snake Bite • 3. Cyanotic Congenital Heart Disease • 4. Fat embolism • 6. Cavernous Hemangioma

34. esami di laboratorio della CID: • PT allungato • aPTT allungato • d-dimero aumentato • fibrinogeno ridotto • piastrine ridotte terapia della CID: • rimuovere la causa • AT-III • plasma • eparina • anti-fibrinolitici

35. difetto parete vascolare • aumentata fragilita’ vascolare • porpora non-trombocitopenica • cause: • A. Eta’ (porpora senile) • B. Farmaci • C. Deficit vitamina C • D. Infezioni • D. Malattie del collagene (vasculiti) • E. Paraproteinemia (amiloidosi, crioglobulinemia) • F. Telangectasia emorragica ereditaria • G. deposizione da immunocomplessi • malattia da siero • porpora di Henoch-Schonlein

36. Causes of thrombocytosis • Secondary or reactive thrombocytosis • Infection (acute and chronic) • Inflammatory disorders (eg Kawasaki's disease) • Chronic iron deficiency • Acute or chronic blood loss • Tissue damage from trauma or surgery • Medicines (steroids) • Splenectomy • Malignancy (Hodgkin's disease, solid tumours) • Rebound from chemotherapy • Primary thrombocytosis • Essential thrombocytosis • Chronic myeloid leukaemia • Polycythaemia vera • Myelofibrosis • Myelodysplastic syndromes

38. Trombocitopenia: 1) aumentata distruzione/aumentato consumo 2) ridotta produzione 3) pseudopiastrinopenia (conteggio EDTA, citrato, eparina)

39. 1. Drug induced Thrombocytopenia (heparin) 2. Idiopathic Thrombocytopenic Purpura (ITP) 3. Vasculitis 4. Autoimmune Hemolytic Anemia 5. Chronic Lymphocytic Leukemia (CLL) 6. Systemic Lupus Erythematosus (SLE) 7. Lymphoma 8. Human Immunodeficiency Virus (HIV) 9. Cytomegalovirus (CMV) 10. Herpes Virus infection Immune-Mediated 1. Prosthetic heart valves 2. Thrombotic Thrombocytopenic Purpura (TTP) 3. Sepsis 4. Disseminated Intravascular Coagulation (DIC) 5. Hemolytic Uremic Syndrome (HUS) 6. Hemorrhage with extensive transfusion 7. Hypersplenism Non-immune Mediated trombocitopenia da aumentata distruzione

40. a. Leukemia b. Histiocytosis c. Lymphoma d. Myelofibrosis e. Storage disease f. Neuroblastoma g. Granulomatosis h. Osteopetrosis 1.Infiltrative process Acquired a. Alcoholism b. Megaloblastic anemia b. Radiation c. Infection d. Medications e. Aplastic Anemia 2.Suppression of Megakaryocytes 1. Thrombocytopenia-absent radii (TAR syndrome) 2. Fanconi's Anemia 3. Wiskott-Aldrich syndrome (x-linked condition) 4. May-Hegglin anomaly 5. Congenital amegakaryocytic thrombocytopenia Hereditary trombocitopenia da ridotta produzione

41. alterazioni qualitative delle piastrine • Hereditary defects • Defects of platelet adhesion • Bernard-Soulier disease ("giant platelets syndrome") • Von Willebrand's disease • Defects of platelet secretion • Storage-pool disease. • Gray-platelet disease: • Defects of platelet aggregation • Thrombasthenia (Glanzmann's disease) • Acquired defects: • NSAID • aspirin (permanently inhibits cyclooxygenase) • non-aspirin NSAID (temporarily block cyclo-oxygenase)

42. arteriosa venosa piastrine aterosclerosi fattori della coagulazione ipercoagulabilita’ trombosi

44. Stato trombofilico • trombosi in eta’ giovanile (< 50 anni) • familiarita’ per trombosi • trombosi ricorrenti • trombosi in sedi insolite • gravidanze ripetutamente complicate da aborti

45. Factor V Leiden Deficiency (APCR) Prothrombin 20210 Hyperhomocysteinemia cause frequenti Antithrombin III deficiency Protein C Deficiency Protein S Deficiency Factor VIII Increased Fibrinolysis Dysfibrinogenemia cause meno frequenti Pregnancy Estrogens Surgery Trauma Infection or Sepsis Malignancy Myeloproliferative disorder Hyperlipidemia Homocystinuria Lupus Inhibitor (LAC) Antiphospholipid Antibodies (ACL) Nephrotic Syndrome Oral Contraceptives Estrogen Replacement therapy tamoxifen primari (ereditari) secondari

46. Activated Protein C Resistance (Factor V Leiden) • A. Inheritance - autosomal dominant • B. Epidemiology • 1. Estimated to occur in 25-40% of patients with family history of thrombosis. • 2. It also occurs in 3-5% of apparently normal individuals. • C. Mechanism: the arginine at position 506 is substituted with glutamine. • This renders FVa resistant to cleavage by APC. • D. Clinical Features • 1. Mean onset of DVT: 44 in heterozygotes, 31 in homozygotes; • 2. Increased risk of venous thrombosis and pulmonary embolism. Venous thrombosis • occurs most frequently in the deep veins of the lower extremities. • 3.Thrombosis may be precipitated by surgery, trauma, pregnancy, OCP use, or infection. • 4. Arterial thrombosis is not increased.

47. Thrombophilic StatusRelative Risk of DVT Normal 1 Oral contraceptive (OCP) use 4 Factor V Leiden, heterozygous 5 to 7 Factor V Leiden, heterozygous + OCP 30 to 35 Factor V Leiden, homozygous 80 Factor V Leiden, homozygous + OCP >100 Prothrombin Gene Mutation, heterozygous 3 Prothrombin Gene Mutation, homozygous ??? Prothrombin Gene Mutation, heterozygous + OCP 16 Protein C deficiency, heterozygous 7 Protein C deficiency, homozygous Severe DVT at birth Protein S deficiency, heterozygous 6 Protein S deficiency, homozygous Severe DVT at birth Antithrombin deficiency, heterozygous 5 Antithrombin deficiency, homozygous lethal prior to birth Hyperhomocysteinemia 2 to 4 Hyperhomocyst + Factor V Leiden, heterozygous 20

49. Management • A.High Risk Indications for life-long Anticoagulation • 1.Two or more spontaneous thrombotic events • 2.One spontaneous life-threatening event (PE) • 3.One spontaneous event with high risk cause • a. Antiphospholipid Syndrome • b. Antithrombin III deficiency • c. More than one inherited abnormality • B.Moderate Risk Indications for event-based prophylaxis • 1.One event with known provocative stimulus

50. piastrine plasma derivati del plasma fattori ricombinanti inibitori della fibrinolisi vitamina K eparina dicumarolici attivatori del plaminogeno anti-aggreganti piastrinici Farmaci per il controllo dell’emostasi procoagulanti anticoagulanti