Venous Thromboembolism Flashcards
Thrombosis
Pathological formation of a blood clot within a vessel
Embolism
Rupture of clot from vessel wall
Travels through circulation until obstructed by smaller vessel
Venous thrombi
Red clots
RBCs within a fibrin mesh
Arterial thrombi
White clots
Platelets and fibrin
Majority of DVT originate in
Calf venous sinuses
Pulmonary embolism
3rd most common cause of CV death
Virchow’s Triad- VTE cause
Reduced blood flow (stasis)
Vessel wall disorder
Hypercoagulability
VTE epidemiology
Hereditary 25%
Acquired 50%
Idiopathic 40%
Caused by antithrombin, protein C + S deficiency
Strong Risk Factors VTE
Fracture hip Major trauma Hip/knee replacement Spinal cord injury Major surgery Hospitalisation with acute medical illness
Moderate Risk Factors VTE
Previous VTE Cancer Resp. Failure Thrombophilia Pregnancy Combined pill/HRT
Weak Risk Factors VTE
Bed rest > 3 days Travel Obesity Varicose veins Day-case surgery
DVT Presentation
Unilateral
Pain, swelling, tenderness
Objective diagnosis DVT
Clinical pre-test probability- Well’s score
D-dimer
Radiological assessment
Well’s score DVT
Active cancer within last 6 months Recent immobilisation Recently bedridden Localised tenderness near deep veins Entire leg swollen Pitting oedema
D-dimer DVT
Blood test
Tests for non-specific marker of fibrin formation
Radiological assessment DVT
Usually compression ultrasound
Sometimes venography
CT scan
DVT Complications
Pulmonary embolism
Recurrent VTE
Post-thrombotic syndrome
Post-thrombotic syndrome
Recurrent pain + swelling in leg due to venous hypertension
Due to obstruction + valve damage
30-50% of proximal DVT
Pulmonary Embolism presentation
Pulmonary infarction
Breathlessness
Collapse, shock
PE signs + symptoms
Breathlessness Collapse Tachycardia Crepitations Raised JVP Pleural effusion
PE Diagnosis
Non-diagnostic –> may or may not be present
PE Arterial gases
Hypoxia
Low CO2
often normal
Hampton’s Hump
Peripheral wedge shaped opacity representing pulmonary infarction + atelectasis secondary to a pulmonary embolus
PE Diagnostic tests
CT Pulmonary Angiogram Isotope Lung Echocardiogram Pulmonary angiogram D-dimer Leg ultrasound
DVT, VTE + PE treatment
Start heparin if likely
Once confirmed, continue heparin with warfarin
Stop heparin after minimum 5 days (INR in normal range for 2 days)
Continue warfarin
Low molecular weight heparin
Mainly VTE treatment Safer than unfractioned Half life 4 hours Anti-Xa Anti-thrombin Subcutaenous
Un-fractioned Heparin
90 min half life
Used when rapid reversibility required
IV or subcutaenous
Heparin side effects
Major bleeding
Heparin induced thrombocytopenia- low platelets
Osteoporosis
Specific heparin antagonist
Protamine sulphate
Fondaparinux
18 hours half life
Synthetic pentasaccharide
Unsuitable if renal impairment
Warfarin
Vitamin K antagonist Oral 36 hour hald life Primarily affects INR Teratogenous Major bleeding risk Reduces risk of recurrence during treatment by 90%
DOACs
Dabigatran
Rivaroxaban
Dabigatran
DOA
Acts on thrombin
Rivaroxaban
DOA
Acts on factor Xa
Pregnancy VTE
Use LMWH
Breast feeding VTE
LMWH and warfarin safe
NOT DOACS
Cancer VTE
LMWH
VTE recurrence
Risk after stopping anticoagulants
5% risk year 1
30% risk by 10 years
Thrombolysis
“clot-busting” therapy
Massive PE or life threatening DVT
Inferior vena cava filter
If major contra-indication to anticoagulation
Thrombophilia
laboratory detected predisposition to thrombosis
Thrombophilia heritable causes
Factor V Leiden Prothrombin gene mutation Protein C deficiency Protein S deficiency Antithrombin deficiency
Antiphospholipid Syndrome (APS)
Acquired form thrombophilia
Primary
Secondary to connective tissue disorder e.g. SLE
APS Diagnostic criteria
Thrombosis
Pregnancy morbidity
Lab criteria
