Deep vein thrombosis and thromboembolism Flashcards
(34 cards)
Define Thrombosis
A solid mass formed IN the circulation from the constituents of the blood during life
(thrmobus is a clot in a BV essentially that results from a complex series of events involving coagulation factors, platelets, red blood cells and vessel wall)
What are fragments of thrombi called?
Emboli
What is the difference between a thrombus in the arterial and venous circulation
Arterial circulation = High pressure and platelet rich
Venous circulation = Low pressure and fibrin rich
What can result from an arterial thrombus in the coronary circulation
Myocardial ischaemia or infarction
What can result from an arterial thrombus in the cerebral circulation
Transient Ischaemic Attack (TIA) or Stroke
What can result from an arterial thrombus in the peripheral vascular circulation
Peripheral vascular disease (PVD) - claudication, rest pain and gangrene
Risk factors of arterial thrombosis
(Similar to that of atherosclerosis) Smoking Hypertension Diabetes Hyperlipidemia Obesity/sedentary lifetsyle Stress
Pathophysiology of arterial thrombosis
- Result of an atheroma that forms in areas of turbulent blood flow such as the bifurcation of arteries
- Platelets adhere to the damaged vascular endothelium and aggregate in response to ADP and thromboxane A2
- Plaque rupture leads to the exposure of blood containing factor VIIa to tissue factor within the plaque which may trigger blood coagulation and lead to thrombus formation
- This can result in complete occlusion of the vessel or embolisation that produces distal obstruction
Diagnosis of arterial thrombosis
Myocardial infarction History Cardiac enzymes Cerebrovascular accident Peripheral vascular disease
Diagnosis of arterial thrombosis myocardial infarction
STEMI ECG Diagnosed on presentation ST elevation Tall T waves LBBB T wave inversion and pathological Q waves follow
Diagnosis of arterial thrombosis Cerebrovascular accident
History and examination
CT/MRI scan
Diagnosis of arterial thrombosis peripheral vascular disease
History and examination
Ultrasound and angiogram
Prevention of arterial thrombosis
- COX inhibitor e.g. ASPIRIN which inhibits platelet aggregation
- P2Y12 inhibitor e.g. CLOPIDOGREL which inhibits ADP from binding to the P2Y12 receptor
- DIPYRAMIDOLE inhibits phosphordiesterase-mediated breakdown of cyclic AMP which prevents platelet activation
Prevention (and treatment) of MI from arterial thrombosis
• ASPIRIN - inhibits platelet function as COX inhibitor
• Thrombolytic therapy:
- STREPTOKINASE
- TISSUE PLASMINOGEN ACTIVATOR which generates plasmin and degrades fibrin clot
Prevention (and treatment) of stroke from arterial thrombosis
- ASPIRIN or CLOPIDOGREL
- TISSUE PLASMINOGEN ACTIVATOR (for brain attack, only have a narrow window)
- Treat risk factors
Clinical presentation of DVT
Often progresses to pulmoary embolism before presenting.
Classical features include:
Limb pain and tenderness along the lines of the deep veins, pain/swelling of the calf, increase in skin temperature, pitting oedema.
Resembles cellulitis
Aetiology of DVT
Thrombotic risk factors
Surgery, immobility, leg fracture, oral contraceptive pill
Genetic or acquired causes
What is more concerning:
DVT in calf below the knee or above the knee
Above the knee is potentially fatal and occurs in the proximal leg vein.
Genetic cause of DVT
Factor V Leiden
PT20210A
Acquired causes of DVT
Anti-phospholipid syndrome
Lupus anticoagulant
Hyperhomocysteinaemia
Risk factors of DVT
Age (higher) Pregnancy Synthetic oestrogen Trauma Surgery (especially pelvic or orthopaedic) Past DVT Cancer Obesity Immobility
DVT pathophysiology
Formation of the thrombus in the deep vein.
This can embolise and often flows up into the pulmonary circulation as a pulmonary embolism
Diagnosis of DVT
Ultrasound (compression Ultras = find popliteal vein, if can squash it shut then NO DVT and vice versa)
D-dimers (plasma)
Contrast venography
What is D-dimer
Type of fibrinogen degradation product that is released into the circulation when a clot begins to dissolve
