Flashcards in Embolism Deck (16):
What is the definition of an embolus?
A detached solid, liquid or gaseous mass within the circulation that is transported to a site distant to its origin
What are the 3 main types of emboli?
Solid, liquid and gas
List the types of solid emboli
thrombo-emboli (a blood clot that breaks free in the blood stream)
athero-emboli (atherosclerotic plaque that breaks off)
tumour emboli (metastasis)
bone marrow emboli (broken long bone fracture → marrow into the vessels forming an embolism)
foreign body emboli (e.g. infection - fungi from a dirty needle enters the circulation and forms a colony, breaks loose)
List the types of liquid emboli
fat emboli (escape from bone marrow or injury to subcutaneous tissues)
amniotic fluid emboli
List the types of gas emboli
air emboli (from injury to the lung or accidentally injected into blood stream)
nitrogen emboli (perfused from tissues)
What are the sources of emboli in the systemic circulation?
Where do embolisms originating in the systemic circulation usually end up?
Small vessels in the lower limbs (because in arterial circulation blood vessels get smaller further away from the heart)
Where do embolisms originating from the venous circulation usually end up?
Usually travel through the R heart and end up in the lungs (pulmonary embolism). If they are in the portal venous system they will end up in the liver.
What are the effects of a pulmonary embolus?
- Stops blood from R heart going into the lung
- Increased pressure in R ventricle (can't unload the blood to the lungs)
- Ventilation-perfusion mismatch (not enough perfusion, less oxygen transfer to blood)
- Extent of the effects depend on the anatomical location of the embolism:
1. Main pulmonary artery at bifurcation: can cause acute right heart failure and sudden death
2. Large branch: can cause pulmonary haemorrhage and infarct
3. Smaller branch: can have no effect, or can cause pulmonary haemorrhage and infarct
4. Multiple smaller branches: causes chronic pulmonary hypertension and R heart failure
Name the sites where solid emboli are involved.
Systemic "arterial" circulation
Venous system (which is associated with the pulmonary arterial system and portal system)
What happens to an embolus?
- develop superimposed thrombosis (thrombus develops on top of the embolus)
- becomes organised and re-canalised (incorporated into vessel wall causing narrowing of the lumen)
Where do tumour, bone marrow and foreign body emboli usually occur?
Where will a solid embolism in the lymphatic circulation end up?
What are the effects of fat embolism?
- Mechanical obstruction
- Fat is toxic to endothelium so it will set off inflammatory reaction (can also set off coagulation cascade)
- Fat embolism syndrome (pulmonary insufficiency, neuro symptoms, petechial rash, thrombocytopenia)
How do amniotic fluid emboli occur? What are the effects?
- During childbirth the uterine veins may rupture
- Contents from amniotic sack enter the veins
- Biochemical effects and mechanical blockage
- Same as fat embolism syndrome (resp, neuro and petechial rash symptoms)