thrombus and emboli Flashcards
terminology - thrombus
stationary solid blood clot that can form outside the vessel, in the wall or in the lumen
terminology - haemorrhage
blood leaving a damaged vessel
terminology - exsanguination
extreme blood loss caused by traumatic injury often resulting in death if blood not replaced within a few minutes
terminology - coagulation
the process
of forming a clot (a thrombus)
terminology - hypercoagulability
having an increased likelihood of clots
terminology - haemostasis
cessation of bleeding and free flow of blood without any clots
rudolf virchow coined the terms…
thrombosis + embolism
virchows triad
- Three factors predispose patients to thrombosis.
- They are stasis, hypercoagulability, and vascular endothelium
- These are commonly referred to as Virchow’s triad.
- if factors intersect they increase risk of thrombosis occuring
Virchow’s Triad
endothelial injury caused by trauma
- injury
- venepuncture
virchow’s triad
endothelial injury caused by pathology
- cellulitis
- thrombophlebitis
- artherosclerosis
virchow’s triad
endothelial injury exacerbated by
- inflammation
- infection
- toxins from cigarettes
virchow’s triad
blood stasis - blood flow can become
turbulent/impaired blood flow
virchow’s triad
blood stasis causes - arterial thrombus
- atrial fibrillation
- athersclerotic plaques
- aortic aneurysm
all lead to turbulent flow - arterial thrombus
virchow’s triad
blood stasis causes - venous thrombus
- mural thrombus after cardiac arrest
- mitral valve stenosis
- polycythaemia
leads to stasis of blood - venous thrombus
arterial vs veinous thrombi
virchow’s triad
lines of zhan
- characteristic of thrombi
- have layers, with lighter layers of platelets and fibrin, and darker layers of red blood cells.
- they are more present on thrombi formed with faster blood flow, more so on thrombi from the heart and aorta.
- they are only seen on thrombi formed before death.
virchow’s triad
hypercoagualability also called
thrombophilia
causes of hypercoagulability
- Trauma
- major surgery
- pregnancy
- inherited thrombophilia
- infection
hypercoagulability states
fate of thrombus - progression that a blood clot goes through while it is present in the body
- Dissolved by fibrinolysis
- Propagation into a larger clot
- Recanalization into the wall which will re-establish patency of the lumen or use of another pathway
- Dislodged and embolization
what is an embolism?
detached intravascular solid, liquid or gaseous mass that is carried by the blood to another site
pulmonary embolism
- cause - venous thrombus embolus from deep leg vein
- common in hospitalised patients and those at home who are immobile
- Often there are multiple emboli
fat embolism
gas embolism
- small volume of air trapped in coronary artery during bypass surgery
- chest wall injury
- obstetric procedures
- decompression sickness - caissons disease
amniotic fluid embolism
- during labour or immediate post partum period
- infusion of amniotic fluid or fetal tissue into maternal circulation via tear in placental membranes or rupture of uterine veins
