define thrombus.
- solid mass formed within circulatory system
- whereas a clot is a mass of blood outside the vessel wall in damaged vasculature.
how is a thrombus formed?
- virchow’s triad : abnormality in vessel wall, blood flow or blood components.
stasis and turbulent blood flow are 2 problems with blood flow. define them.
- stasis is the slowing of blood due to narrowing, immobility or low blood pressure.
- turbulent flow disrupted flow due to defects in wall and heart valves, T-Fib or area of dead cardiac muscle.
what could cause a hypercoaguable state of blood?
- smoking.
- pregnancy.
- post operative.
- cancer.
- Covid-19.
- genetic : anti-thrombin iii deficiency.
differentiate between arterial and venous thrombi.
- arterial are pale, granular, low cell content whereas venous thrombi are soft, gelatinous, deep red with high cell content.
name some outcomes or complications of thrombosis.
- lysis : breakdown of thrombus usually when small resulting in complete dissolution and blood flow back.
- propagate : spread of thrombosis, distally in arteries, proximally in veins.
- organise : reparative, ingrowth of fibroblasts and capillaries, lumen obstructed.
- recanalise : channels through thrombus to re-establish blood flow incompletely.
- embolise : part of thrombus breaks and travels through blood stream and lodges at distant site.
what are some effects of venous thrombosis on tissue.
- congestion.
- oedema.
- ischaemia.
- infarction.
what are some effects of arterial thrombosis on tissue.
- ischaemia.
- infarction.
- depends on collateral circulation.
define an embolism.
blockage of blood vessel by solid, liquid or gas at a distant site from origin. mostly thrombo-emboli.
name some common sites of thrombosis.
name a further complication of each.
- veins : DVT often leads to pulmonary embolism.
- heart : MI, fragments into aorta and lodged in cerebral arteries leading to ischaemic stroke.
- carotid artery : atherosclerotic plaque may lead to emboli and ischaemic strokes.
- abdominal aorta : plaque or aneurysm with thrombus developing to emboli leading to acute limb ischaemia.
define DVT and name some predisposing factors.
- deep vein thrombosis : blood clot in a vein. If embolised may lead to pulmonary embolism.
- immobility, post-operative, pregnancy, cardiac failure.
what are some complications of pulmonary thrombo-emboli?
- if found in main pulmonary artery sudden death.
- small embolus in peripheral pulmonary artery pulmonary infarct.
- multiple repeated emboli cause pulmonary hypertension.
do you know of any other types of emboli?
- air, amniotic fluid, tumour cells, fat and bone marrow post trauma.
- air bubble secondary to pulling out of cannulation.
- fat emboli usually secondary to trauma.
how would you prevent thrombosis and thromboembolism?
- identify high risk patients.
- heparin sub-cutaneously.
- aspirin.
- leg compression stockings or flow-tron boots.
what features would lead for you to suspect DVT?
- well’ score of 2 or more : immobility, local tenderness, swelling, previous DVT etc.
- D-dimers in blood.
- anticoagulant therapy.
how would you treat DVT?
- clot busters and thrombo-lysis if stable.
- CT or USS for DVT.
- oral warfarin.
- heparin.
- devices in left atria to stop thrombus forming.
- embolectomy.
