Venous thrombosis Flashcards
(49 cards)
What are the key points to remember with regards to the venous system?
- It is a low pressure system
- Thin smooth muscle component in the wall compared to the high pressure arterial system
- Relies a lot on the calf muscles contraction and relaxation to aid in venous return (as doesnt have a lot of muscle in its vessel wall like the arterial to do it on its own) (this is why immobility is a massive risk factor)
- Also contains valves to prevent backflow
What are the 2 main types of venous thromboses ?
- DVT
- PE
Define what DVT, PE and VTE is
- DVT = Deep Venous Thrombosis. A thrombus (clot) formed in the deep venous circulation (usually legs) but can be anywhere
- PE = Pulmonary Embolism. A thrombus (clot) that has embolised (travelled) and lodged in the pulmonary circulation
VTE = Venous Thromboembolic Disease. Covers both DVT and PE.
Define what is meant by the term pulmonary infarction
This is when blood flow & oxygen to the lung tissues is compromised, potentially causing the lung tissue to die
What is the difference between a proximal and a distal DVT ?
- Distal vein thrombosis refers to DVT of the calves
- Proximal vein thrombosis refers to DVT of the popliteal vein or the femoral vein. These thromboses are termed ‘proximal’ because they are closer to the heart
What type of clot forms in venous thrombosis ?
Fibrin rich clot - platelets are NOT activated in these types of clots
What triad of factors typically causes venous thromboses ?
Virchows traid:
- Stasis
- Endothelial (vessel wall) damage
- Hypercoagulability
What happens to the risk of VTE as you get older ?
The risk dramatically increases:
- Young adults 1/10 000 per annum
- Elderly 1/100 per annum
What are the causes of stasis which result in increased risk of VTE ?
- Age
- Marked obesity
- Pregnancy
- Previous VTE/PE
- Trauma/surgery
- Malignancy
- Paralysis e.g. stroke
What are the main causes of vessel wall damage causing increased risk of thrombosis ?
- Age
- Previous DVT/PE
- Vasculitis
What are the factors which cause hypercoagulability resulting in increased venous thrombosis ?
- Age
- Pregnancy & Peurperium
- Oestrogen therapy
- Trauma/surgery
- Malignancy
- Infection
- Thrombophilia
- IBD
What are the signs and symptoms of DVT
- Calf warmth, tenderness, swelling and erythema
- usually presents unilaterally
What are the other ‘differentials’ to consider when someone presents with the clinical features suggestive of a DVT ?
- Popliteal synovial rupture (bakers cyst)
- Superficial thrombophlebitis
- Calf celulitis
What are the signs and symptoms of PE ?
- Sudden SOB
- Sudden, sharp chest pain that may become worse with deep breathing or coughing. (pleuritic chest pain)
- Tachypnoea & Hypoxia
- Tachycardia
- Haemoptysis
- Collapse
- DVT
- Crackles, pleural rub, pleural effusion
How is a DVT diagnosed ?
Initially do a WELLS score
If WELLS score greater than 2 then DVT likely and do:
- 1st line = Venous doppler US if neg do D-dimer
- 2nd line = If D-dimer pos then repeat US, if neg then rule out DVT
- If cant do doppler within 4hrs do d-dimer and give LMWH heparin whilst waiting
If WELLS score 1 or less DVT is unlikely so do:
- 1st line = D-dimer if pos then do a Venous doppler US of the leg
- If you cant do doppler within 4hrs give LMWH
How is a PE diagnosed ?
If a patient presents with signs or symptoms of PE do a CXR initially to rule out other causes and potentially diagnose a PE (note >50% CXR’s in PE are normal)
Do a PE WELLS score
If PE likely (score >4):
- CTPA if neg consider doppler leg US
If unlikely (score ≤4):
- Do D-dimer if pos then do a CTPA
Note if there is any delay in getting CTPA then give patient LMWH & you will have also done baseline bloods & ABG
When should V/Q scan be used over CTPA in PE diagnosis ?
If the patient has an allergy to contrast media or renal impairment
What ECG abnormalities are associated with PE ?
- A large S wave in lead I, a large Q wave in lead III and an inverted T wave in lead III - ‘S1Q3T3’.
- RBBB and right axis deviation are also associated with PE
- sinus tachycardia may also be seen
What is the investigation of PE in pregnant women
- 1st line = ECG & CXR in all patients
- 2nd line in women who have signs and symptoms of a DVT = do bilateral compression duplex U/S if this confirms DVT no further investigation as PE can be assumed and tx started.
- 2nd line if no S/S of DVT = CTPA or V/Q scan (if CXR abnormal then CTPA used in perference otherwise decision is made at local level between the two as below)
The decision to perform a V/Q or CTPA should be taken at a local level after discussion with the patient and radiologist:
- CTPA increases maternal risk of breast cancer
- V/Q increases the risk of childhood cancer
If there is no obvious underlying cause of the PE e.g. surgery, pregnancy, malignancy, immobility etc then what should be done to investigate the underlying cause?
Consider cancer:
- Clinical exam; CXR, PSA, CA125
- CT Abdo/pelvis (best will rule out most things e.g. all cancers rather than one specific cancer)
- Mammogram for women > 40
Check autoantibodies (SLE) - Antinuclear, Anti-Cardiolipin Abs
Thrombophilia screen - Anti-thrombin-III deficiency, Protein C or S deficiency, Factor V Leiden; increased VIII
What is the treatment for venous thrombosis i.e DVT and PE ?
- 1st line = Rivaroxiban (NOAG) (or apixaban)
- 2nd line = LMWH or fondaparinux + warfarin for the long-term treatment
Continue LMWH heparin or fondaparinux for roughly 5 days or when INR is >2 and then continue with just warfarin
Tx usually for 3-6months
1st line - If pregnant use LMWH for the full 6months of prophylactic treatment
1st line for active cancer is now the same as normal VTE management
If patient is haemodynamically unstable (systolic<90) with a PE then consider using thrombolytic therapy using tissue plasminogen activator (tPA) - tenecteplase, otherwise normal anti-coag treatment
Patients who have repeat pulmonary embolisms, despite adequate anticoagulation, may be considered for what?
Inferior vena cava (IVC) filters - these work by stopping clots formed in the deep veins of the leg from moving to the pulmonary arteries.
What are the target ranges for someone being treated with warfarin following a DVT/PE?
- 2.0 -3.0 (2.5) 1st event
- ≥ 3.0 for recurrent events
- 3.5 if recurrent DVT/PE whilst on warfarin
What is post-thrombotic syndrome ?
It is a common complication seen in patients who have had a DVT, it is a clinical syndrome which can result in the following manifestations:
- painful, heavy calves
- pruritus
- swelling/oedema
- varicose veins
- venous ulceration
- eczema
