CVS 1 Flashcards
Compare and contrast haemostasis and thrombosis.
Haemostasis occurs when there is damage to a blood vessel. It involves the formation of a solid plug from the constituents of blood. It stops loss of blood from the circulation at the site of injury. It is physiological (ie. it’s a good thing)
Thrombosis occurs when there is inappropriate activation of haemostasis:
– platelets and the coagulation system interact with the vessel wall to form a solid plug (=thrombus) in the blood vessel
– the process overwhelms the capacity of the fibrinolytic system and coagulation inhibitors
• A thrombus is made up of the same components as a haemostatic plug ie. platelets, fibrin and red blood cells
• Thrombosis is pathological
Explain the importance of Virchow triad
describes the three major predisposing factors to thrombus formation
Define embolism
Embolism is the occlusion of a vessel by undissolved material that is transported in the blood stream
Define ischaemia and infarction.
Ischaemia: tissue dysfunction due to interference with blood flow (supply or drainage) to a tissue. It is reversible
Infarction: tissue death (necrosis) due to interference with blood flow (supply or drainage)
to a tissue. It is irreversible
List the components of Virchows triad and example of each
Endothelial Injury- atherosclerosis
Abnormal blood flow- stasis Hypercoagulability- alterations in coag factors
Outline the important complications of myocardial infarction.
Ventricular fibrillation- presents as cardiac arrest
arrhythmia- usually in inferior MIs because the pacemaker cells are supplied by the right coronary artery
haemopericardium- leads to cardiac tamponade
rupture of interventricular septum
mitral valve regurgitation due to rupture of the papillary muscle
mural thrombus
pericarditis
ventricular aneurysms
Describe the aetiology and effects of medium-sized pulmonary emboli and understand the importance of venous thromboembolism prevention
transportation of thrombus in the bloodstream which then impacts in a pulmonary artery
VTE is important to prevent thrombi.
list common types of emboli
PE DVT Pelvis Arm RV
describe how thrombi may cause clinical effects
Cause sudden occlusion of an artery leading to infarction and ischaemia
explain how mechanism how atherosclerosis causes stable angina
Gradual enlargement of a stable plaque leading to luminal stenosis
Explain how atherosclerosis causes MI
Sudden plaque disruption and thrombosis in a vulnerable plaque
Explain how atherosclerosis can lead to ischaemic stroke.
- Most commonly, an atherosclerotic plaque in an internal carotid artery ruptures and thrombus forms on the surface of the plaque
- Part of the thrombus embolises and occludes one of the cerebral arteries resulting in a stroke
difference between clot and thrombus
Thrombus- RBCs and platelets, form within the CVS, forms in flowing blood
Clot- RBCs no platelets, form outside of CVS, form in stationary blood.
what determines the stability of the plaque x2
– smooth muscle cells (produce fibrous cap that stabilises the plaque)
– inflammatory cells (digest the fibrous cap and kill smooth muscle cells
and destabilise the plaque)
what are acute coronary syndromes?
A spectrum of clinical conditions which occur when there is a sudden severe reduction in myocardial perfusion - ischaemia or infarction
typically there is erosion or rupture of the plaque with overlying thrombosis, often accompanied by marked spasm of the vessel
