Thrombosis and embolism Flashcards
Thrombosis
Formation of a solid mass of blood within the circulatory system-solid mass then called a thrombus.
clot=
clot= mass of blood outside the vessel wall
virchows triad explains
how thrombus’ are formed
virchows triad
1) hypercoagable state
2) Blood flow stasis (slowing of blood)
3) Endothelial injury
atheroma
what can cause endothelial damage
atheroma
direct injury
inflammation
atrial thrombosis
- Pale
- Granular
- Lines of Zahn
- Lower cell content
lines of zahn
are a characteristic of thrombi that appear particularly when formed in the heart or aorta. They have visible and microscopic alternating layers (laminations) of platelets mixed with fibrin, which appear lighter and darker layers of red blood cell
Venous thrombus
- Soft
- Gelatinous
- Deep read
- Higher cell content
outline thrombosis and fibrinolysis
- fibringoen is activated to fibrin by thrombin to form platelt plug
- plasminogen is activated by tPA (tissue plasminogen activator) to plasmin
- plasmin disintegrates the clot
4.
fibrin degradation products
e.g. D dimers (detected in blood test)
outcomes/ complications
- Lysis
- Propagate
- Organise
- Recanalize
- embolise
- lysis
- Most likely when thrombi are small
- Complete dissolution of thrombus
- Fibrinolytic system active
- Blood flow re-established
- propagation
- Progressive spread of thrombosis
- Distally in arteries (goes out to the peripheries)
- Proximally in veins (goes more central e.g. heart)
3. Organisation
- Reparative process
- Ingrowth of fibroblasts and capillaries (similar to granulation tissue)
- Lumen remains obstructed
- Recanilization
- Blood flow re-established but usually incompletely
- One or more channels formed through organising thrombus
5. Embolism
- Part of thrombus breaks off
- Travels through the bloodstream
- Lodges at distant site
affect of thrombosis on venous tissue
- Congestion
- Oedema
- Ischaemia
- Infarction
Effects of thrombosis on arterial tissue
- ischaemia
- Infarction
- Depends on the site and collateral circulation
e.g. cerebral A, carotid A,coronary A, mesenteric A, renal A, femoral/iliac/ popliteal A
coronary artery thrombus
histological view of thrombus in coronary A
coronary artery thrombus causing MI
embolism
Blockage of a blood vessel by a solid, liquid or gas at a site distant from its origin
- >90% of emboli are thrombo-emboli
thromboembolism- arteries and veins
- Passes from systemic veins to the lungs- pulmonary thromboembolic
- Pass from the heart pass via the aorta and lodge in the renal mesenteric and other arteries, resulting in bowel ischaemia and renal infarction
- Pass from atheromatous carotid artery to the brain leading to ischaemic stroke
- Pass from atheromatous abdominal aorta to the arteries of the legs leading to acute limb ischaemia
other types of embolism
- Air
- Amniotic fluid
- Nitrogen
- Medical equipment
- Tumour cells
- Fat, bone marrow (bost trauma)
deep vein thrombosis
histological features of PT
Predisposing factors for a DVT
- Immobility/bed rest
- Post- operative
- Pregnancy and post-partum
- Oral contraception
- Severe burns
- Cardiac failure
- Disseminated cancer
Pulmonary thrombus
In most cases, pulmonary embolism is caused by blood clots that travel to the lungs from deep veins in the legs or, rarely, from veins in other parts of the body (deep vein thrombosis)
outcomes of pulmoanry thrombus
1) Massive coiled embolus in main pulmoanry artery sudden death
2) Small embolus lodged in peripheral pulmonary artery Pulmonary infarct
3) Pulmonary hypertension
saddle embolism
pulmonary embolism that straddles the bifurcation of the pulmonary trunk, extending into the left and right pulmonary arteries.
thromboembolism of the foot
ischaemia- gangrene
Thromboembolism from carotid artery
- ischemic stroke
prophylaxis of DVT/ PE
- Identify high risk patient
- Low molecular weight heparin sub-cutaneous
- Mobilise early
- Leg compressions during surgery
- TED stockings
- FLowt tran boots
Treatment of thrombus +/- thromboembolic
- Clot busters
- Intravenous heparin type drugs
- Newer generation NOAC (noval oral anticoagulant)
- Filters in inferior vena cave (devices in left atria to stop thrombus formation etc)
- Embolectomy (lefs etc for acute limb ischaemia)
- Oral warfarin
clot blusters
Streptokinase, alteplase (recombinant tPA)
newer geenration NOAX (noval oral anticoagulants)
- Dabigatran (thrombin)
- Rivaroxaban (anti-factor Xa)
