Pathophysiology of thrombosis and embolism 1 Flashcards
Normal blood flow is ________
Laminar
What is stasis?
Stagnation of flow
What is turbulence?
Forceful and unpredictable flow
What are the causes of thromboembolism?
Thromboembolism (common)
Atheroma
Hyperviscosity
Spasm
External compression
Vasculitis
Vascular steal
What are the factors in virchows traid that contribute to formation of blood clot?
Changes in the blood vessel wall
changes in the blood constituents
Changes in the pattern of blood flow.
What is thrombosis?
Formation of solid mass from the constituents of blood within the vascular system during life
What is an example of a disease that changes in the vessel wall can cause?
Atheromatous coronary artery
What is the pathogenesis of thrombosis?
Endothelial injury
Stasis or turbulent blood flow
Hypercoagulability of the blood
What can thrombosis cause?
Turbulent blood flow can cause Fibrin deposition and Platelet clumping
Loss of intimal cells leading to denuded plaque
Collagen exposed causing platelets to adhere
Fibrin meshwork causing RBCs to be trapped
How does hypercholesterolaemia relate to thrombosis?
It increases the risk of atherosclerosis which is a major underlying cause of thrombotic events
What is the relationship between atheroma and thrombosis?
Virchows traid plays a crucial role in the development of arterial thrombosis on atheromatous plaques.
What can changes in blood constituents cause?
Hyper viscosity
Post-traumatic hypercoagubility
What can turbulence cause?
Atheromatous plaque
Aortic aneurysm
What can stasis lead to?
It is one of the factors that contribute to its development of economy class syndrome.
Who are at a risk of developing deep vein thrombosis?
Post op patients due to low mobility after surgery
What do the consequences of thrombosis depend on?
Site
Extent
Collateral circulation
What is embolism?
Movement of abnormal material in the bloodstream and its impaction in a vessel, blocking its lumen.
What is embolus?
Detached intravascular solid, liquid or gaseous mass
Factors causing embolism depend on type of embolus
What are most emboli?
Dislodged thrombi which can cause thromboembolism
What are the sources of systemic/arterial thromboembolism?
- Mural thrombus which is associated with MI or left atrial dilation and AF
- Aortic aneurysms
- Atheromatous plaques
- Valvular vegetations
- Venous thrombi which can lead to a paradoxical emboli
What sites does systemic thromboembolism travel to?
Lower limbs (most common), brain and other organs
What are the consequences of systemic thromboembolism
dependent on?
Vulnerability of affected tissue to ischaemia
Calibre of occluded vessel
Collateral circulation but usually infarction occurs.
Where does venous thromboembolism
originate from?
Deep venous thromboses (lower limbs)
It is the most common form of thromboembolic disease
Where does Venous thromboembolism travel to?
Pulmonary arterial circulation
What is venous thromboembolism dependant on?
Size, it may occlude main pulmonary artery, bifurcation (saddle embolus), smaller arteries.
What are the consequences of pulmonary thromboembolism depend on?
Size of embolus: silent, pulmonary haemorrhage/infarction, right heart failure, sudden death
What does multiple pulmonary embolism cause over time?
Pulmonary hypertension
Right ventricular failure
What are the risk factors for DVT and pulmonary thromboembolism?
- Cardiac failure
- Severe trauma/burns
- Post-Op/Post-partum
- Nephrotic syndrome
- Disseminated malignancy
- Oral contraceptive
- age
- Bed rest/ immobilisation
- Obesity
- Past medical history of DVT
What are the prophylaxis given to surgical patients at risk of DVT and pulmonary thromboembolism?
TEDS and S/C heparin
What can major fractures cause?
Syndrome of fat embolism
The brain, kidneys and skin are affected
