Venous Thromboembolism Flashcards
Pathogenesis Epidemiology Clinical features Diagnosis Management (36 cards)
What is a thrombosis?
pathological clot (thrombus) formation within a blood vessel.
What is an embolism?
clot which breaks off and travels through circulation until it gets obstructed by a smaller vessel
What do venous thrombi look like?
Red clots
What do arterial thrombi look like?
White clots
What are the main examples of venous thromboembolism (VTE)
DVT - deep vein thrombosis
Pulmonary embolism
Venous thrombosis at other sites such as axillary vein
Other causes of embolism - fat, amniotic fluid
Where can you get a DVT?
Distal - confined to calf veins
Proximal - involve popliteal vein or above
What are the 3 causes of VTE?
Reduced blood flow (stasis)
vessel wall disorder
hypercoagulability
How does someone get VTE? (3 ways)
heritable - 25%
acquired - 50%
idiopathic - 40%
many inherited and acquired
What are some genetic RF for VTE?
Factor V leiden
Protein C and S deficiency
Antithrombin deficiency
Elevated factor VIII, IX, XI
What are some strong acquired RF for VTE?
Hip/pelvis fracture
hip/knee replacement
major trauma
spinal cord injury
What are some moderate RF for VTE?
Previous VTE cancer respiratory failure pregnancy HRT central veous line thrombophilia
What are some weak RF for VTE?
bed rest > 3 days
travel related thrombosis
obesity
varicose veins
How does DVT present itself?
Unilateral swelling warmth ipsilateral oedema superficial venous dilation palpable cord which is the thrombosed vein tenderness pain
Why is objective diagnosis for VTE so important?
Over 75% patients with suspected VTE are negative on inspection
Drugs to treat have serious side effects
What are some examples of differential diagnoses?
ruptured Baker's cyst (popliteal) cellulitis compression of iliac veins musculo-tendinous trauma lymphoedema
How do you diagnose DVT?
In this order:
- Clinical pre test probability where give a score based on presentation features and history (likelihood)
- D-dimer levels check as usually raised in VTE but also pregnancy, infection, inflammation
- Radiological assessment - compression ultrasound non invasive, venography is looking for calf DVT, CT
What are some complications of DVT?
pulmonary embolism
extension of clot
post-thrombotic syndrome (recurrent pain and swelling, venous hypertension)
How does a pulmonary embolism present?
tachycardia and tachypnoea isolated breathlessness hypotension shock pleuritic chest pain hypoxia CXR normal, maybe pleural effusion often non-diagnostic
What are some differential diagnoses for pulmonary embolism?
Pneumonia/bronchitis asthma anxiety acute coronary syndrome pneumothorax lung cancer pericardial tamponade
How do you diagnose pulmonary embolism?
CT pulmonary angiogram isotope lung scan chest x ray echocardiogram pulmonary angiogram leg ultrasound D-dimer
What is the traditional basic treatment for DVT and PE?
Do blood tests and start heparin unless there is a contraindication (usually LMWH), confirm diagnosis with 24hrs and if confirmed continue heparin and start warfarin, stop heparin after 5 days min. when INR is in therapeutic range and continue warfarin while monitoring, review at 3 months
What is LMWH?
Low molecular weight heparin Safer than UFH more predictable anticoagulant response no monitoring needed so easier subcutaneous admin
What is UFH?
Unfractionated heparin
IV admin
monitor by APTT
used where rapid reversibility is important as has short half life
What site does heparin work on?
Factor Xa and thrombin
