Pathophysiology of Thromosis and Embolism Flashcards
What is stasis?
Stagnation of flow
What is turbulence?
Forceful and unpredictable flow
What are the main causes for defects in blood flow?
Thromboembolism, atheroma, hyperviscosity, spasm, external compression, vasculitis and vascular steal
What are the three components of Virchow’s Triad?
Changes in the blood vessel wall, changes in the blood constituents and changes in the pattern of blood flow
What does Virchow’s Triad represent?
The factors causing thrombosis
What is thrombosis?
Formation of a solid mass from the constituents of blood within the vascular system during life
What causes thrombosis?
Endothelial injury, stasis/turbulent blood flow and hypercoagulability of the blood
What are lines of Zahn?
The alternating structure of RBCs and fibrin that form in a thrombus
What factors does the consequences of the thrombosis depend on?
The site, extent and collateral circulation
What are the common clinical presentations of thrombosis?
DVT, ischaemic limb and MI
What are the outcomes of thrombosis?
Resolution, organisation/recanalization, death and propagation (embolism)
What is an embolism?
Movement of abnormal material in the bloodstream and its impaction in a vessel, blocking its lumen
What is an embolus?
A detached intravascular solid, liquid or gaseous mass
What are the sources of systemic/arterial thromboembolus?
Mural thrombus (MI, left atrial dilation + AF), aortic aneurysms, atheromatous plaques and valvular vegetations
Where can a systemic thromboembolus travel to?
Lower limbs (most common), brain and other organs
What are the consequences of a systemic thromboembolus?
It depends on the vulnerability of the affected tissues to ischaemia, the calibre of the occluded vessel and the collateral circulation but usually infarction occurs
Where does a venous thromboembolus originate from?
From deep venous thrombosis (lower limbs)
Where do venous thromboemboli travel to?
The pulmonary arterial circulation
What are the consequences of pulmonary thromboembolism?
They depend on the size but include: silent emboli, pulmonary haemorrhage/infarction, right heart failure and sudden death
What effect does multiple PE have over time?
Pulmonary hypertension and 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, increasing age, bed rest/immobilisation, obesity and PMH of DVT
What are the features of a fat embolus
It occurs after major fractures and it effects the brain, kidneys and skin
What is the most likely cause for a gas embolus?
Decompression sickness - where nitrogen forms as bubbles which lodge in the capillaries
When do air emboli often occur?
In head and neck wounds, surgery and CV lines
What are the other forms of emboli?
Tumour, trophoblast, septic material, amniotic fluid, bone marrow and foreign bodies
