Venous disease Flashcards
What is DVT?
Formation of a thrombus within the deep veins (most commonly of the calf or thigh).
What is the aetiology of DVT?
VIRCHOW’S TRIAD: venous stasis, vessel wall injury and blood hypercoagulability.
What are the risk factors of DVT? (x12)
Oral contraceptive pill, surgery, prolonged immobility, long bone fractures, obesity, pregnancy, dehydration, smoking, polycythaemia, anti-phospholipid syndrome (autoimmune clotting disorder), thrombophilia disorders (such as protein C deficiency), active malignancy.
What is the pathophysiology of DVT?
Clots tend to develop just above and behind a venous valve. When propagation of a thrombus occurs, it expands and grows proximally and across the lumen of the vein. This may lead to occlusion. The thrombus may also embolise and cause a PE.
What is the epidemiology of DVT: Where is the incidence? Prevalence of complications?
Highest in hospitalised patients. Long-term complications of DVT affect 0.5% of population.
What are the symptoms of DVT?
Asymptomatic or lower limb swelling or tenderness. May present with symptoms of PE such as SOB, pleuritic chest pain (worse on breathing), haemoptysis, and tachypnoea.
What are the signs of DVT?
- Phlegmasia cerulea dolens from leg oedema and cyanosis from thrombotic occlusion is uncommon
- Signs of PE such as pleural friction rub, pleural effusion, loud P2 and raised JVP
What is the Wells Clinical Prediction Score? (x9 measures +1)
Considers likelihood of DVT in patients: Lower limb trauma/surgery/immobilisation, >3 days bedridden, surgery within last 4 weeks, tenderness along deep venous system, entire limb swollen, calf at least 3 cm bigger circumference, pitting oedema, dilated collateral superficial veins (non-varicose), and malignancy each score 1 point. Alternative diagnosis more likely than DVT loses 2 points. If total score is more than 3, probability of DVT is high. Between 1 and 2: probability is moderate.
What are the investigations for DVT? (x2 +3)
- Doppler ultrasound is gold standard.
- Bloods: D-dimer are sensitive but not specific.
- ECG, CXR and ABG if there is a suggestion that there might be PE.
How is DVT medically managed? (x3 options)
ANTICOAGULATION. There are several treatment options: Rivaroxaban (direct Factor Xa inhibitor) for 3 weeks initially, Apixaban (direct Factor Xa inhibitor) for 1 week initially, or treat patients with a heparin and add warfarin (adjusting dose of warfarin according to target INR). Heparin can be discontinued once INR is above 2 for >24hrs. There are many other options too. Heparin + warfarin is not recommended first-choice.
How does management differ depending on location of DVT?
Below-the-knee DVT requires anticoagulation for longer.
How are recurrent DVTs treated?
Long-term warfarin/other anticoagulant.
What must be tested before starting warfarin?
INR to optimise the therapeutic effect without risking dangerous side-effects such as bleeding. INR 1.1 or below is normal. An INR range of 2-3 is an effective therapeutic range for people on warfarin.
What must be tested before starting any heparin?
aPTT and sometimes U&Es (as medication may be contraindicated with renal impairment)
How is DVT managed when active anticoagulation is contraindicated and/or high embolization risk?
IVC filter placement to prevent embolus to lungs.
How is DVT prevented? (x3)
Compression stockings, mobilisation, prophylactic heparin e.g., LMWH for immobilised hospital patients.
What are the complications of DVT? (x3)
PE, damage to vein valves and chronic venous insufficiency (post-thrombotic syndrome), venous infarction (with phlegmasia cerulea dolens; infarct denotes obstruction leading to build-up of pressure, cyanosis and oedema).