haemostasis and thrombosis Flashcards
What pathway does activated partial thromboplastin time (APTT) involve?
intrinsic
How can disorders of coagulation and haemostasis arise
Inherited-single gene mutations
acquired
How can platelets be affected
bnormal number of platelets
Abnormal function of platelets
Or both
What pathway does prothrombin time (PT) involve?
extrinsic
In what direction does thrombosis progress in veins
proximally
In what direction does thrombosis spread in arteries
distally
What 2 clotting screening tests are there
prothrombin time (PT)
Activated partial thromboplastin time (APTT)
What 2 genetically determined conditions increase risk of thrombosis
Factor V Leiden
Protein C deficiency
What activates Inactive FXIII
Thrombin IIa
What are DVT and PE collectively known as
Venous thromboembolism(VTE)
What are lines of Zahn
characteristic of thrombi that appear particularly when formed in the heart or aorta
What are some characteristics of arterial thrombi
Pale/red
granular
lines of Zahn
What are some examples of direct Xa inhibitors
Rivaroxaban
apixaban
edoxaban
What are some mechanical methods to prevent deep vein thrombosis - DVT
Anti-embolism stockings
intermittent pneumatic compression
foot impulse devices
What are some risk factors for arterial thrombosis(8)
Age
smoking
obesity
hypertension
atherosclerosis
diabetes
south asian
hypercholesterolaemia
What are some risk factors for VTE (Venous thromboembolism)(5)
age
malignancy
trauma
pregnancy
immobility
What are the 2 types of thrombosis
arterial and venous
What are the 3 classes of fibrinolytic drugs
Tissue plasminogen activator (t-PA)
Streptokinase
urokinase
What are the 3 components of virchow’s triad
Endothelial injury
hypercoagulability
stasis (pooling) of blood flow
What are the 3 stages of haemostasis
Primary haemostasis
secondary haemostasis
dissolution of clot and vessel repair (fibrinolysis)
What are the 4 core components of haemostasis
Vessel wall
platelets
coagulation system
fibrinolytic system
What are the most common thrombosis disorders
Deep vein thrombosis (DVT)
Pulmonary embolism(PE)
What are the different blood tests that can be done for haemostasis
full blood count
prothrombin time(PT)
activated partial thromboplastin time(APTT)
What are the different severities of pulmonary embolisms
Massive PE
major PE
Minor PE
What are the different types of embolism that can occur
Air
Nitrogen
fat
amniotic fluid (only in pregnancies)
What are the effects of arterial thrombosis
Ischaemia and infarction
What are the effects of venous thrombosis
Congestion
oedema
haemorrhage
What are the most common type of emboli
thrombo-emboli
What are the problems with warfarin
Need monitoring of INR with frequent blood tests
Dose sensitive
What can inhibit tissue factor in extrinsic coagulation pathway
Tissue factor pathway inhibitor
What clotting cascade affected in haemophilia
Intrinsic pathway
What coagulation inhibititors do endothelial cells produce
NO (nitric oxide)
Prostacyclin
what condition can arise from recurrent minor Pulmonary embolism
pulmonary hypertension
What do endothelial cells secrete in blood vessel wall injury
Von Willebrand factors
What does activated partial thromboplastin time measure
Instrinsic pathway
What does antithrombin III inhibit
Thrombin and FXa
What does the prothrombin time test measure
Extrinsic clotting pathway
What factors are cleaved by Protein C
Factor Va and VIIIa
What is a embolism
Blockage of a blood vessel by a solid,liquid or gas at a site distant from its origin
What is a major pulmonary embolism
Medium sized vessels blocked
What is a minor Pulmonary embolism
Small peripheral pulmonary arteries blocked
What is an example of a direct thrombin inhibitor
Dabigatran
What is DIC (disseminated intravascular coagulation)
Blood clots form throughout the body blocking small blood vessels
What is haemarthrosis
condition that arises due to bleed into joint cavity
What is included in the balance in haemostasis
Procoagulant factors
anticoagulant factors
What is leukocytosis
white blood cell count is above normal range in blood, is a sign of inflammatory response
What is massive pulmonary embolism
60% reduction in blood flow due to embolism
What is primary haemostasis
Formation of unstable platelet plug
what is pulmonary thromboembolism
blood clot lodged in artery in lung hence blocking blood flow to part of lung
What is sagittal sinus thrombosis
presence of blood clot in dural venous sinuses
what is secondary haemostasis
stabilisation of plug with fibrin in blood coagulation system
What is the characteristic of thrombosis of the femoral artery
White bloodless limb
what is the D-Dimer test
Blood test that can be used to diagnose thrombosis by measuring levels of D-Dimer in the blood
What is the function of warfarin
Inhibit hepatic synthesis of Factor II,VII,IX and X
It is a vitamin K antagonist hence inhibit production of Vitamin K dependant clotting factors
What is the process of platelet plug formation
Platelets adhere to subendothelial structures via von Willebrand factors
platelets adhere to one another and the plug is held by insoluble fibrin
What is the Well’s Score ?
Scoring system that assesses probability of PE with given presentations
What is the Well’s Score ?
Scoring system that assesses probability of PE with given presentations
What is thrombophilia
Imbalance in blood clotting proteins or clotting factors
what is thrombosis
Formation of a solid mass of blood clot within circulatory system
What is treatment for classic Haemophillia
Recombinant FVIII
What is treatment for VTE
IV heparin
warfarin
direct oral anticoagulants
What is Virchow’s triad
three broad categories of factors that contribute to thrombosis
What occurs in DIC(Disseminated intravascular coagulation)
clotting cascade accelerated
clotting factors consumed faster than they can be replaced
What occurs in lysis stage of thrombosis
Complete dissolution of thrombus
fibrinolytic systems become active
What occurs in organisation stage of thrombosis
Growth of fibroblasts and capillary proliferation
What occurs in propagation stage of thrombosis
Progressive spread of thrombosis
What occurs in recanalisation stage of thrombosis
One or more channels form through the thrombus
blood flow becomes re-established
What occurs in thrombotic thrombocytopaenic purpura
Platelet masses form in small vessels leading to a haemorrage and purpura
What scoring system used to assess probability of DVT
Wells score
Where can a embolism from aorta travel to
Renal
mesenteric
Where can an embolism from carotid arteries travel to
brain
Where can embolism of abdominal aorta travel to
Legs
where does purpuric (small blood vessels) bleeding occur
kidney
skin
brain
gut
heart
Why do we need anti-thrombotics
Prevent arteries and capillaries being constantly blocked
Inhibit strokes and heart attacks
