Venous Thrombosis Flashcards
What is a VTE?
Involves a blood clot (thrombus) developing in the circulation, usually secondary to blood stagnation or hypercoagulable states
When a thrombus develops in a deep vein, it is called a..
DVT
What’s a PE?
Once a thrombus has developed, it can travel (embolise) from the deep veins, through the right side of the heart and into the lungs, where it becomes lodged in the pulmonary arteries
If the patient has a septal defect in their heart, the thrombus can pass through to the ______ side of the heart and into the systemic circulation. If it travels to the brain, it can cause a large ______
If the patient has a septal defect in their heart, the thrombus can pass through to the left side of the heart and into the systemic circulation. If it travels to the brain, it can cause a large stroke
Risk factors for DVT/PE
Immobility
Recent surgery
Long haul travel
Pregnancy
Hormone therapy with oestrogen
Malignancy
Polycythaemia
Systemic lupus erythematosus
Thrombophilia
What are Thrombophilias?
Conditions that predispose patients to develop blood clots
Give examples of Thrombophilias
Antiphospholipid syndrome
Factor V Leiden
Antithrombin deficiency
Protein C or S deficiency
Hyperhomocysteinaemia
Prothombin gene variant
Activated protein C resistance
What does VTE prophylaxis?
Low molecular weight heparin (LMWH), such as enoxaparin
Anti-embolic compression stockings
Contraindications to VTE prophylaxis
Active bleeding or existing anticoagulation with warfarin or a DOAC
Contraindications to anti-embolic compression stockings
Peripheral arterial disease
DVTs are almost always..
Unilateral
Bilateral DVTs suggest..
Chronic venous insufficiency or heart failure
What does the clinical picture show?
DVT
The calf circumference is measured 10cm below the tibial tuberosity. __________ difference is significant
More than a 3cm
Consider a ______________ (e.g., shortness of breath and chest pain) in patients with features of a DVT
Pulmonary embolism
What is a Well’s score?
Predicts the risk of a patient presenting with symptoms having a DVT or PE. It includes risk factors (e.g., recent surgery) and clinical findings (e.g., unilateral calf swelling over 3cm greater than the other leg).
The Wells score is used when considering deep vein thrombosis. The outcome decides the next step..
Likely: perform a leg vein ultrasound
Unlikely: perform a d-dimer, and if positive, perform a leg vein ultrasound
_______________ is the usual first-line imaging investigation for a pulmonary embolism
CT pulmonary angiogram (CTPA)
In DVT/PE, repeat negative ultrasound scans after 6-8 days if the patient has a..
Positive D-dimer and the Wells score suggests a DVT is likely
Initial management of DVT/PE
Apixaban or rivaroxaban
LMWH (alternative)
Consider catheter-directed thrombolysis in patients with a symptomatic iliofemoral DVT and symptoms <14 days
Long term coagulation of DVT/PE
DOACs - c.i severe renal impairment, antiphospholipid syndrome and pregnancy
Warfarin - 1st line in antiphospholipid syndrome
LMWH - 1st line pregnancy
Long term anti-coagulation is continued for..
3 months with a reversible cause (then review)
3-6 months in active cancer (then review)
Long-term for unprovoked VTE, recurrent VTE or an irreversible underlying cause (e.g., thrombophilia)
When are inferior vena cava filters used?
Used in those unsuitable for anticoagulation or where a PE has occurred whilst already on anticoagulation
When patients have their first VTE without a clear cause, NICE recommend..
Reviewing the medical history, baseline blood results and physical examination for evidence of cancer
In patients with an unprovoked DVT or PE that are not going to continue anticoagulation beyond 3-6 months, NICE recommend considering testing for..
Antiphospholipid syndrome
Hereditary thrombophilias
What is Budd-Chiari Syndrome?
Obstruction to the outflow of blood from the liver caused by thrombosis in the hepatic veins or inferior vena cava
Budd-Chiari Syndrome is associated with..
Hypercoagulable states (e.g., myeloproliferative disorders)
BCS presents with a classic triad of:
Abdominal pain
Hepatomegaly
Ascites
___________ is the usual imaging investigation for establishing the diagnosis of Budd-Chiari syndrome
Doppler ultrasonography
Tx for Budd-Chiari syndrome
Anticoagulation (LMWH and warfarin)
Endovascular procedures (thrombolysis or angioplasty)
Transjugular intrahepatic portosystemic shunt (TIPS)
Liver transplant
What is Virchow’s triad?
Stasis
Vessel wall
Hypercoagulability
Potential mechanisms of thrombophilia
Increased coagulation activity
– Platelet plug formation
– Fibrin clot formation
Decreased fibrinolytic activity
Decreased anticoagulant activity
Potential deficiencies in Hereditary thrombophilia
Factor V Leiden
Prothrombin 20210 mutation
Antithrombin deficiency
Protein C deficiency
Protein S deficiency
______________ has a stronger risk factor for thrombosis than
the hereditary thrombophilias
Acquired Thrombophilia - Antiphospholipid antibody syndrome
Hypercoagulability is associated with..
Release of tissue factor, raised
VWF and factor VIII
Pathogenesis antiphospholipid antibodies
Conformational change in β2 glycoprotein 1 (a protein
with unknown function in health) which leads to activation of both primary and secondary haemostasis and vessel wall
abnormalities
What is antiphospholipid syndrome?
Acquired disorder characterised by a predisposition to both venous and arterial thromboses, recurrent fetal loss and thrombocytopenia
APS may occur as a primary disorder or secondary to other conditions, most commonly..
SLE
Antiphospholipid syndrome causes a paradoxical rise in..
APTT - this is due to an ex-vivo reaction of the lupus anticoagulant autoantibodies with phospholipids involved in the coagulation cascade
Venous/arterial thrombosis
Recurrent miscarriages
Livedo reticularis
Pre-eclampsia, pulmonary hypertension
APS
Ix for APS
Anticardiolipin antibodies
Anti-beta2 glycoprotein I (anti-beta2GPI) antibodies
Lupus anticoagulant
Thrombocytopenia
Prolonged APTT
Mx for APS in primary thromboprophylaxis
Low-dose aspirin
Mx for APS in secondary thromboprophylaxis
Initial venous thromboembolic events: lifelong warfarin with a target INR of 2-3
Recurrent venous thromboembolic events: lifelong warfarin; if occurred whilst taking warfarin then consider adding low-dose aspirin, increase target INR to 3-4
Arterial thrombosis should be treated with lifelong warfarin with target INR 2-3
