Deep Vein Thrombosis & Pulmonary Thromboemolism Flashcards
What is a thrombus (2)
- Clot arising in the wrong place (arterial or venous)
* A solid structure arising inappropriately in a fluid system
What is Haemostasis
Physiological process of maintaining vascular integrity
What does a clot consist of (4)
Fibrin
Platelets
Red blood cells
White blood cells
What is one of the functions of the endothelium
• Endothelium protects components of blood being activated
What happens when the endothelium is activated (4)
endothelium exposes collagen, smooth muscle and connective tissue
• When the damage occurs tissue factors VIII and VII that normally circulate the blood inactivated interact with factor X
• Factor X interacts with Factor V to initiate the conversion of prothrombin to thrombin
• This reaction then causes fibrinogen to be converted to fibrin
What happens to fibrin during coagulation (2)
Becomes insoluble
Forms cross links
What components are soluble and what are insoluble
Everything before the production of fibrin is soluble
What does Factor XIII hep do
Helps cross link polymerised fibrin to make it a strong structure
Define White thrombus
white arterial thrombus. This consists of platelets and fibrin, and there is a lack of red blood cells due to the fast flow of the blood preventing the incorporation of red blood cells
Define Red thrombus
red venous thrombus. This consists of red blood cells and fibrin and there are more red blood cells due to the slow flow of blood which allows more red blood cells to be incorporated
Mechanism of arterial thrombus
usually rupture of atherosclerotic plaque
Mechanism of venous thrombous
Combination of Virchows triad especially stasis and hypercoagubility
Location of origin of arterial thrombus (2)
Arteries
left heart chambers
Location of origin of venous thrombosis
Venous valves and venous sinusoids of muscles
Arterial thrombus results in (2)
Ischaemia or Infarction
Venous thrombus results in
back pressure
Diseases associated with arterial thrombus
DVT
PE
Composition go arterial thrombus
Platelets
Fibrin
Composition of venous thrombus
Red blood cells
Fibrin
What is Virchows Triad
3 broad factors that contribute to thrombosis
Stasis
Hypercoagulability
Endothelial damage
What can causes stasis (2)
Immobility
Long haul travel
What can cause acquired hypercoagulability (3)
Pregnancy
Cancer
Sepsis
What can cause endothelial dysfunction (3)
Hypertension
Smoking
High cholesterol
What can cause endothelial damage (3)
Indwelling venous catheters
Trauma
Surgery
How does Pregnancy
Cancer
Sepsis increase hypercoagulability
Increases the production of tissue factor
Embolism
Intravascular material that migrates from its original location to a distal vessel
Thromboemolism
Movement of blood clot along a vessel
Examples of VTE (4)
- Limb deep vein thrombosis (DVT)
- Pulmonary embolism (PE)
- Visceral venous thrombosis
- Intracranial venous thrombosis
Risk Factors of VTE (3)
Surgery
Abdominal/Pelvic malignancies
Oral contraceptive
Signs and Symptoms of DVT (7)
- Unilateral limb swelling
- Persisting discomfort
- Calf tenderness
- Warmth
- Redness- erythema
- Prominent collateral veins
- Unilateral pitting oedema
Diagnosis of suspected DVT (3)
- Clinical assessment and carry out Wells score (pre-test probability sore)
- Blood test: D-dimer if low Wells score
- Imagine: compression ultrasound if positive D-dimer or high pre-test probability score
DVT Wells Score >/=3 (2)
High probability
Imaging- compression US
DVT Wells Score 1 or 2
Intermediate probability
Imaging- compression US
DVT Wells Score =0
Low probability
D-dimer blood test
A negative D-dimer result
means that DVT or PE can be ruled out.
A positive D-dimer result means that
the patient has to undergo further imaging in order to diagnose whether or not he or she has DVT or PE.
What is a D-dimer
Breakdown product of cross-linked fibrin
Symptoms and Signs of PE (5)
- Pleuritic chest pain
- SOB- dyspnoea
- Haemoptysis
- Tachycardia
- Pleural rub on auscultation- usually due to pulmonary infarction
Symptoms and signs of massive pulmonary embolism (7)
- Severe dyspnoea of sudden onset
- Collapse
- Blue lips and tongue- cyanosis
- Tachycardia
- Low blood pressure
- Raised venous jugular pressure
- Sudden death
Diagnosis of PE (4)
Wells Score or Geneva Score
D-dimer blood test
Isotope ventilation/perfusion scan
CT pulmonary angiogram
PE Wells score >/= 6.5 (3)
High probability
Imagine- isotope ventilation/perfusion scan
CT pulmonary angiogram
PE Wells score 4.5-6.0 (3)
Moderate probability
Isotope ventilation/perfusion scan
CT pulmonary angiogram
PE Wells score = 4.0 (2)
Low probability
D-dimer blood test
Potential long-term consequence of pulmonary embolism (2)
- Most recover fully
* Pulmonary arterial hypertension
In a patient with diagnosed VTE it is important to consider (3)
- Was there a clear cause or precipitant- hospital, surgery
- Any symptoms or signs to suggest underlying malignancy
- Consider risk of recurrence
Aims of Treatment of VTE (3)
- Prevent clot extension
- Prevent clot embolism
- Prevent recurrent clot
Treatment options (anticoagulant) IV
Unfractionated heparin
Treatment options (anticoagulant) subcutaneous
low molecular weight heparin
Treatment options enteral
Warfarin and direct oral anticoagulants
What treatment option must be reserved for thrombolysis
massive PE (Alteplase)
Prevention of VTE
- Early mobilisation
- Anti-embolism stockings
- Other mechanical methods of thromboprophylaxis
- Pharmacological thromboprophylaxis
How do you develop a pulmonary infarction after a PE (3)
- Blockage to a branch of the pulmonary artery = increase in pressure within pulmonary vasculature
- Force within bronchial artery may be insufficient to overcome this
- ‘Leakage’ of blood into alveolar space occurs, and leads to infarction
