Deep Vein Thrombosis and Pulmonary Thromboembolism Flashcards
What is the incidence of DVT?
1 in 1000 per annum
What is the case fatality rate of venous thromboembolism?
1-5%
What is the incidence of PE?
3000-5000 per annum
What percentage of autopsies reveal a PE?
20% of autopsies
What are the components of Virchow’s Triad?
Stasis
Vessel damage
Hypercoagulability
What are examples of presentations of venous thromboembolism?
Limb DVT Pulmonary embolism Visceral venous thrombosis Intracranial venous thrombosis Superficial thrombophlebitis
What are the features of venous thrombus?
Red thrombus - fibrin and red cells
Results in back pressure
Principally due to stasis and hypercoagulability
What are the features of arterial thrombus?
White clot - platelets and fibrin
Results in ischaemia and infarction
Principally secondary to atherosclerosis
What is the presentation of DVT?
Unilateral limb swelling Persisting discomfort Calf tenderness Warmth Erythema May also be clinically silent
What are the potential long-term consequences of DVT?
Post-phlebitic syndromes
e.g. swelling, discomfort, pigmentation, ulceration
What is the presentation of PE?
Pleuritic chest pain Dyspnoea Haemoptysis Tachycardia Pleural rub on auscultation
What is the presentation of massive PE?
Severe dyspnoea of sudden onset Collapse Central cyanosis Tachycardia Hypotension Raised JVP Altered heart sounds May cause sudden death
What are the potential long-term consequences of PE?
Most recover fully
May result in pulmonary hypertension
What are the risk factors for venous thromboembolism?
Increasing age Tissue trauma Immobility Obesity Smoking Systemic disease e.g. cancer Genetics e.g. heritable thrombophilia Pregnancy Exogenous oestrogen e.g. OCP, HRT
What is the most prevalent heritable thrombophilia?
Factor V Leiden
What is the link between VTE and travel?
Relative risk increased by 2-3
Increased risk in short, tall or overweight people, and in women on the OCP
How is DVT diagnosed?
Clinical assessment
D-dimer
Compression ultrasound
How is a d-dimer test useful?
Negative result is more useful as it will rule out DVT
Positive result will not confirm DVT but will indicate need for more investigation
How is PE diagnosed?
Clinical assessment
D-dimer in unlikely patients
Isotope ventilation/perfusion scan
CT pulmonary angiogram
How can VTE be prevented in hospital?
Early mobilisation
Anti-embolism stockings
Daily injections of low molecular weight heparin
What pressures are provided by anti-embolism stockings?
18mmHg at the ankle
14mmHg at the mid-calf
8mmHg at the upper thigh
Result in maximal femoral blood flow velocity of 139% of the baseline
When are graduated compression stockings useful?
Prevention of DVT Chronic venous insufficiency Varicose veins Oedema Lymphoedema Prevention of post-phlebitic syndrome
What is the treatment of VTE?
Low molecular weight heparin for 5 or more days then oral anticoagulant (warfarin) for at least 3 months
Thrombolysis for massive PE
Vena caval filter
