Clinical Aspects of Thrombosis Flashcards
Definition of thrombosis
Blood in blood vessel should be fluid
Inappropriate blood coagulation within a vessel
How does appropriate blood coagulation occur?
When blood escapes from a vessel (failure of this results in bleeding)
Types of thrombosis (x2)
What kind of pressure system?
Rich in?
Treatment therefore?
In the arterial circulation High pressure system Platelet rich - anti platelet In the venous circulation Low pressure system Fibrin rich - anticoagulants
Clinical thrombosis - two types and examples
Arterial thrombosis Myocardial infarction Thrombotic stroke Venous thrombosis Leg deep vein thrombosis (MI) Pulmonary embolism (PE)
Thrombosis treatment
AT
VT
Anti platelet drugs
Anticoagulant drugs
Atherosclerotic plaque formation process
- Initial fatty streak
- Plaque enlargement
- Turbulence due to protrusion into lumen and RUPTURE
- Loss of endothelium and adherence to wall
- Fibrin meshwork deposition and red cell entrapment
- More turbulence, more platelet and fibrin deposition
- Thrombus of layers of platelets, fibrin and red cells
- CLOT FORMED
- any structure distal to artery will die
Risk factors for arterial thrombosis
Main
Other
- Family history
- Diabetes mellitus
- Hypertension
- Hyperlipidaemia
- Smoking
- Atrial fibrillation for stroke
- Male sex
- Polycythaemia, gout
- Collagen vascular disease
- Lupus anticoagulant, high FVIII, high fibrinogen
Arterial thrombosis - management and examples
Lifestyle - quit smoking, exercise, diet and weight control
Antithrombotics: primary prevention in patients with atrial fibrillation
Arterial thrombosis treatment options
Anti platelet agents
AT Treatment options - antiplatelet agents
2x
Aspirin:
Irreversible inhibitor of cyclooxygenase (COX1)
Inhibition of production thromboxane
Inhibition lasts platelet lifetime
Risk reduction of non-fatal vascular event by 30%
Risk reduction of fatal vascular event by 15%
Effect will last for a week after stopping it
Clopidogrel
Irreversible ADP mediated platelet inhibition
Inhibition lasts for lifespan
18% decrease in risk of MI
Risk of coronary stent thrombosis/recurrent stroke by 30%
Arterial thrombosis – Treatment options Thrombolysis
Indications and drugs involved and side effect
MI
Stroke within 3 hrs
life threatening PE
Alteplase
Streptokinase
others
Bleeding
Arterial thrombosis – Treatment options - Invasive
Percutaneous coronary intervention - cardiac stenting - use stent to keep passage open
- combined with 3-12 months aspirin + clopidogrel
Coronary artery bypass grafting
Carotid endarterectomy - inject dye to see where blockage is
Arterial thrombosis – Treatment options - REHABILITATION of stroke survivors
Stroke - swallowing, malnutrition, mobilisation
Arterial thrombosis – Treatment options - secondary prevention
Lifestyle
- exercise, smoking cessation, weight control, safe alcohol use
- blood pressure control
- cholesterol lowering
- diabetic control
- antithrombotic therapy in stroke associated with atrial fibrillation
Atrial fibrillation - characteristics
Irregularly irregular heart rhythm 8% > 80 y/os Left atrial thrombus due to stasis of blood in atrium --> clot Embolisation leads to stroke if occurs Impaired cardiac output
AF treatment
DC cardioversion
Heart rate control
Anticoagulation
Heart rate control methods
Beta blockers, Ca channel blocker Digoxin AV junction ablation Anticoagulation
How does AF cause stroke
Blood pools in atria
Blood clot forms due to stasis
Blood clot breaks off
Blood clot travels to brain and blocks a cerebral artery causing stroke
How is it detected in ECG?
Abnormal electric pathways between nodes results in multiple triggers of contraction leading to irregular pattern on ECG
Venous thrombosis
Most begins as?
Low pressure system
Fibrin rich
Treated with anticoagulants
Deep vein thrombosis in the leg
DVT –> ??
Downwards to leg ulcers
DVT –> upwards
PE
Formation of venous thrombosis - virchow
Clotting factors - hypercoagulability
Vessel wall damage
Flow –> stasis
Risk factors for venous thrombosis - 3 types
Definition in terms of risk
VTE is a multifactorial disorder occurring through the interplay of one or more genetic and/or environmental risk factors when a critical thrombotic threshold is reached.
Heritable e.g factor V leiden
Acquired
Mixed
Heritable thrombophilias
Associated with?
Associated with idiopathic VTE at young age
Incidence is 1/10000
Higher with older age
Common in hospitalised (150x) and immobilised patients
VTE - prevention
Risk assessment
Thromboprophylaxis
Adequate hydration
Early mobilisation
VTE - prevention
Prophylaxis
Mechanical
Chemical
Mechanical
- all surgical patients at risk of ate
- graduated elastic compression hosiery
- intermittent pneumatic compression
Chemical - prevents 50-70%
Low molecular weight heparin
Direct oral anticoagulants
VTE - treatment options Acute
Anticoagulation
Thrombolysis
Thrombectomy
Inferior vena cava filter to catch clots
VTE - treatment options Long-term
Anticoagulation
Stockings
Treatment of VTE - duration
3 months of anticoagulants after first event
Provoked events do not need anticoagulation for >3months
Distal DVT does not need anticoagulatory treatment for > 3months
Consider long term anticoagulation after 1st unprovoked thrombosis
Venous Thrombosis - summary
Multifactorial disease
Associated with significant mortality/morbidity
Prevention essential, especially in hospital setting
Treatment mainly with anticoagulants
Optimum duration debated
Associated with increased risk of bleeding
Arterial Thrombosis - summary
Both venous and arterial thrombosis have high morbidity and mortality.
Prevention is essential in both
Treatment is with systemic anticoagulation in venous thrombosis and antiplatelet agents in arterial thrombosis
