Arterial and Venous Thrombosis Flashcards
(28 cards)
Arterial thromboses most commonly affect which circulations?
Coronary
Cerebral
Peripheral
Why do plaques not rupture in venous thrombosis?
As it is a low pressure system
Which is activated in venous thrombosis - the coagulation cascade or platelet plug?
Coagulation cascade
What is Virchow’s triad of venous thrombosis?
Stasis
Vessel wall damage
Hypercoaguability
Give some risk factors for venous thrombo-embolism
Age Obesity Pregnancy Puerperium Oestrogen therapy Previous DVT/PT Trauma Malignancy Paralysis Infection Thrombophilia
What is thrombophilia?
A disorder of the haemostatic mechanism predisposing an individual to thrombosis
What are the broad causes of thrombophilia?
Increased coagulation activity
Decreased fibrinolytic activity
Decreased anticoagulant activity
What naturally occurring anticoagulants are found in the blood?
Anti-thrombin
Protein C and protein S
Give some examples of hereditary thrombophilias
Factor V Leiden
Prothrombin 20210 mutation
Antithrombin/protein C/protein S deficiencies
How is hereditary thrombophilia managed?
Short term prophylaxis (during periods of known risk)
Short term anticoagulation (treat events)
Long term anticoagulation (recurrent events)
What is the main cause of acquired thrombophilia?
Anti-phospholipid syndrome
Give some features of anti-phospholipid syndrome
Recurrent thromboses (either arterial/venous)
Recurrent fetal loss
Mild thrombocytopenia
What is the pathogenesis of anti-phospholipid syndrome?
Antibodies causes a change in beta 2 glycoprotein 1 causing activation of primary and secodary haemostasis
Patients with antiphospholipid syndrome will have a prolonged PT/APTT
APTT
What is the main risk factor for an arterial thrombosis?
Atherosclerosis
What occurs in atherosclerosis?
Damage to the endothelium causes recruitment of cholesterol-rich macrophages that form plaques
What occurs when atherosclerotic plaques rupture?
Platelets adhere to the plaque and become activated recruiting more platelets to form a plug
What are the main risk factors for arterial thrombosis?
Hypertension
Smoking
High cholesterol
Diabetes mellitus
What allows platelets to bind to subendothelial collagen?
Glycoprotein 1b
von Willebrand factor
What allows platelets to attach to each other?
Glycoproteins IIb and IIIa
Fibrinogen
Why do platelets alter their shape to stabilise the clot?
To expose more phospholipid on the surface and provide a greater surface area for coagulation
What granules are released by platelets to further stimulate platelet activation?
Thrombin
Thromboxane A2
ADP
How does aspirin work?
Inhibits cyclo-oxygenase preventing production of thromboxane A2
What are the main side effects of aspirin?
Bleeding GI ulceration (due to blocking of prostaglandins)
