Bleeding disorders Flashcards
Haemophilia types?
A and B
Haemophilia type A
Defect in F8 gene causing reduced FVIII (haemophilia A)
Haemophilia type B
Defect in F9 gene causing reduced FIX (haemophilia B)
Haemophilia genetics
Sex-linked recessive inheritance (on X chromosome)
Sx of Haemophilia
Coagulation pathway disorder
- Mild or severe bleeding depending on factor level (Soft tissue and joint, CNS, GI bleeds)
- Chronic arthropathy (bleeding in joint leads to inflammation)
Mx of haemophilia
- Recombinant factor concentrate (synthetic factor 8 & 9)
- prophylaxis every 2-3 weeks
normal roles of vwf?
- VWF mediates PLT adhesion to collagen
- stabilises coagulation Factor VIII in the plasma
Mild Von Willebrand disease cause
- Defective primary haemostasis
Mild Von Willebrand disease sx
- Epistaxis
- easy bruising
- traumatic skin bleeding
Severe Von Willebrand disease cause
- Additional coagulation pathway
- defect due to low FVIII
Von Willebrand disease tests?
- Long aPTT in moderate or severe VWD (when FVIII level is low)
- reduced plasma VWF activity
- reduced plasma FVIII activity
Management of VWD?
I. Tranexamic acid
II. DDAVP/Desmopressin
III. VWF/FVIII concentrate
Tranexamic acid
Reduces clot break-down
antifibrinolytic
DDAVP/Desmopressin
- Releases endogenous FVIII and VWF
- only works once, temporary release
Bleeding disorders acquired causes
- Abnormal synthesis
- Abnormal function
- Dilution
- Consumption
Potential causes of abnormal synthesis leading to acquired bleeding disorders?
- Liver disease
- Vitamin K deficiency (coagulation factors II, VII, IX, X)
- Warfarin
Potential causes of abnormal function leading to acquired bleeding disorders?
- Heparin and direct acting oral anticoagulants*
- Renal failure (platelet dysfunction)
- Anti-platelet drugs
Potential causes of dilution leading to acquired bleeding disorders?
- Massive transfusion
* Cardiopulmonary bypass
Potential causes of consumption leading to acquired bleeding disorders?
(Thrombotic microangiopathies )
• Disseminated intravascular coagulation*
• Thrombocytopenia in sepsis
Liver damage and clotting?
I. ↓Synthesis of most clotting factors, fibrinogen and coagulation regulators
II. ↓PLT number
III. Biliary obstruction gives vit K malabsorption
IV. Hyperfibrinolysis
Vit K role?
needed for synthesis of Factors II, VII, IX and X
Disseminated intravascular coagulation (DIC) causes
I. Sepsis II. Major trauma III. Obstetric emergencies (pre-eclampsia, amniotic fluid embolism, retained POC) IV. Advanced malignancy
Disseminated intravascular coagulation (DIC) pathophysiology
I. Pro-coagulant stimulus + loss of regulatory pathways –> Widespread activation of coagulation pathway
II. Fibrin/platelet rich
microvascular thrombi and Multiorgan failure
III. Platelet, fibrinogen and
coag factor consumption and bleeding
Management of DIC
• Fresh frozen plasma
• Platelet transfusion
• Fibrinogen concentrate or
cryoprecipitate
Thrombotic thrombocytopenic purpura (TTP) Sx?
- onset fever, malaise, arthralgia
- Bleeding
• Variable neurological features
• Chest pain
• Jaundice + abdo pain
Thrombotic thrombocytopenic purpura (TTP) cause?
Caused by anti-ADAMTS13 antibodies
Thrombotic thrombocytopenic purpura (TTP) pathology?
anti-ADAMTS13 antibodies-> Reduced proteolysis of VWF -> Circulating ultra-high molecular weight VWF multimers -> Platelet agglutination in ‘high shear’ vessels, microvascular, thrombosis, platelet consumption, mechanical haemolysis
Diagnosis of TTP
Blood film is diagnostic: smashed in half
PLT reduced and Hb reduced
Mx of TTP?
PLASMA EXCHANGE or II. Supportive care • RBC transfusion • Aspirin and LMW heparin • Iv corticosteroids Rituximab
DVT
- first investigation?
- secondary Ix?
- Wells score for DVT diagnosis
- I. Score >1=
- DVT likely
- Doppler USS
II. Score 1 or less:
- DVT unlikely
- D dimer test
- Doppler USS if high
DVT complications?
Post-thrombotic syndrome:
- Chronic swelling and aching
- Venous eczema and ulcers
PE complication?
Chronic thromboembolic pulmonary hypertension (CTPH)
- 0.5-5% of treated clots replaced by fibrous tissue
- Progressive Pulmonary HTN and RHF
3 conditions that increase the risk of DVT?
- Antithrombin deficiency
- Factor V Leiden
- antiphospholipid syndrome
Antithrombin deficiency mx
- Long term anticoagulation
- short term AT
concentrate
Factor V Leiden pathology?
Reduces inactivation of Factor V by activated protein C
Management of anti phospholipid syndrome?
- If thrombotic, long term anticoagulation (plus antiplatelet agent if arterial thrombosis)
Immediate Management of DVT and PE?
- Fast acting anticoagulant minimum 3 months
- (Rivaroxaban or LMW heparin)
long term Management of DVT and PE?
anticoagulation:
- Rivaroxaban,
- warfarin.
- LMWH in cancer or pregnancy
2 types of Anti-thrombotic drugs
- Anti-platelet drugs
2. Anti-coagulant drugs
Anti platelet drugs used for?
Treatment/prevention arterial thrombosis
eg ACS
Anti coagulant drugs used for?
treatment/prevention venous thrombosis or low pressure vessel thrombosis
eg DVT, PE, CVA in AF
NICE guidlines for VTE thromboprophylaxis
All patients at risk of VTE should:
• Mobilise early
• Receive pharmaceutical thromboprophylaxis (eg enoxaparin 40 mg once daily)
mech of action of heparin
• Increases activity of natural anticoagulant
antithrombin
• Inhibits active clotting factors esp. Factors IIa
(thrombin) and Xa
Route of UF heparin
IV
Route of LMW heparin
SC
Metabolism of UF heparin
Renal
Metabolism of LMW heparin
Renal
Half life of UF heparin
1-2hours
Half life of LMW heparin
4-6 hours
Reversal of UF heparin
Protamine iv 1mg/100 IU heparin in last hr (max 40mg)
Reversal of LMW heparin
Protamine iv 1mg/100 IU heparin in last hr (max 40mg)
Direct oral anticoagulant (DOAC) example?
rivaroxaban
Rivaroxaban mech of action
- Factor Xa inhibitor
* Reduces thrombin generation
Rivaroxaban use?
I. VTE prevention after knee/hip replacement
II. Stroke prevention in non-valvular AF
III. Acute and long term treatment of DVT
Rivaroxaban half life?
8 hours
Rivaroxaban metabolised by
75% liver metabolised,
25% renal excreted
Rivaroxaban reversal?
Specialist products (APCC, specific reversal agents) for severe bleeding
Warfarin mech of action?
Inhibits vitamin K metabolism (factors 2,7,9,10)
Warfarin uses?
I. when DOACs are unsafe
II. Long term VTE
III. Stroke prevention in AF
IV. With anti-platelet agent, to prevent arterial thrombosis
when are DOACs unsafe
- Mechanical heart valves,
- Antiphosphoilipid syndrome,
- CKD
Warfarin half life
Plasma half life ~36 hours
Warfarin metabolised by
liver
Warfarin reversal
- Vitamin K if INR >8.0 for mild bleeding
- Vitamin K factor concentrate (eg Octaplex) plus Vit K for severe bleeding