Introduction to bleeding disorders. Flashcards
In haemostatic balance what 2 factors are balance
bleeding (anti-coagulant)
clotting (procoagulant)
what is the first step which results in the activation of a haemostatic plug forming
disruption to the BV wall
what molecule do platelets adhere to
vWF
what molecule does vWF attach to
collagen
what molecule does thrombin activate
fibrin
where does thromboxane synthesis take place
inside the platelet
what is the purpose of thromboxane
contacts blood vessels and activates platelets.
2 important receptors found on the plasma membrane of a platelet.
IIaIIIA- receptor for fibrinogen= platelet aggregation.
IBIX- receptor for vWF=platelet adhesion
aspirin inhibits cycloxygenase, what is the function of cycloxygenase
produce thromboxane.
what molecule does clopidogrel inhibit
ADP
what happens in the extrinsic pathway.
- Tissue factor expressed on injurged cells= damage BV
2. Activates VII-VIIa, this activates X- Xa, this activated prothrombin to thrombin which converts fibrinogen to fibrin.
what happens in the intrinsic pathway
- XIIa-XIIa, which converts XI-XIa, which converts IX-IXa.
2. activates X- Xa, this activated prothrombin to thrombin which converts fibrinogen to fibrin.
what are the procoagulant molecules.
platelets
clotting factors
what are the anticoagulant molecules
Protein C
Protein S- co factor protein C.
Anti-thrombin III
Fibrinolytic system- breaks down the clot when it is no longer needed.
what is the fibrinolytic pathway
Tissue plasminogen factor (TPA) breakdown plasminogen to plasmin.
Plasmin then converts fibrin into a fibrin degradation product.
This happens on the surface of a clot.
TPA use for clot busting in acute MI.
What are the different types of bleeding disorders
congenital acquired platelet vessel wall coagulation defect
What drug can cause abnormal platelet function (Blood thinner)
aspirin
what condition is caused by abnormal interaction between the vessel wall and platelets
von willibrand factor.
what are the major difference between platelet and coagulation defects
platelet defects- affect skin and mucosal membranes and form petichae and bruising on skin
coagulation defects- affect spreading haematoma and haemoarthrosis, affect retroperrtioneal bleeding which is often recurrent and prolonged.
do petichae blache when pressure is applied
no.
Von Willebrand disease is caused by a deficiency in which molecule
platelets
what type of genetic disorder is von willebrand factor
autosomal dominant.
what factor is reduced in von willebrand disease
factor 8 (FVIII)
which blood group has lower levels of von willebrand factor
blood group O
what are common consequences of von willebrand disease
- Mucocutaneous bleeding including menorrhagia
* Postoperative and post partum bleeding
are there different types of von willebrand factor, in terms of disease.
yes there are mild and more severe forms.
what is the treatment that is provided for von willebrand factor disease
Antifibrinolytics: tranexamic acid (important in mouth bleeds)
DDAVP- releases VWF from stores in endothelial cells.
factor concentrates of VWF
vaccination against hepatitis
COCP (combined oral contraceptive pill) for menorrhagia
haemophilllia a is a deficnecy in which factor
factor VII
haemophillia b is a deficnency in whihc factor
factor IX.
what type of genetic inherited disorder are the haemophillias
x-linked.
what is the function of the drug DDAVP
release vWF form endothelial cells.
are there degrees of severity in haemophilia
yes
normal, mild, moderate and severe.
what are the different types of bleeds occur in haemophilia
spontaneous/post traumatic joint bleeding- haemarthorosis. muscle- haemorrhage soft tissue- mouth bleed and intracranial bleed. life threatening bleed in the airways.
what is acute and chronic haemophilic arthropathy- which is a complication of haemophilia
swollen bone deformity
muscle wasting
treatment for haemophilia
Replacement of missing clotting protein DDAVP factor concentrates antifibrinolytic agents vaccine for hep A and hep B
complications of treatment from haemophilia treatment
Infections- Hep A,B,C,G, HIV, paravirus, vCJD.
Inhibitor development (more common in haemophilia A)- patients become resistant to replacement therapy.
How is haemophilia managed
Haemophilia Centres and Comprehensive care Centres.
Multidisciplinary Approach
Home treatment
Patient Education and Social Support
Physiotherapy
Orthopaedic Advice & Treatment
Treatment & Diagnosis of Liver Disease
Specialised Management for HIV Positive Patients
Genetic Counselling & Parental Diagnosis
appropriate investigations if you suspect a bleeding disorder.
Full blood count and blood film Coagulation screen Mixing studies if abnormal results Refer to a haematologist if history suspicious Von Willebrand profile platelet function tests
what conditions does the bleeding /normal coagulation screen show.
Thrombocytopenia Disorder of platelet function vWD Factor XIII deficiency Mild coagulation factor deficiency Vascular disorder Disorder of fibrinolysis: rare
