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Pathophysiology of Acute Coronary Syndrome
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in most of ACS cases syndrome occurs when an
atherosclerotic plaque ruptures, fissures or ulcerates and precipitates thrombus formation.
This results in sudden total or near-total arterial occlusion. Alternatively thrombus may
break off from a ruptured plaque and occlude smaller vessels like coronary
arteries.
* systemic factors and
inflammation also play role in changing haemostatic and coagulation pathways and may
play a part in the initiation of the intermittent thrombosis that is a characteristic of
unstable angina. Inflammatory acute phase proteins, cytokines, chronic infections and
catecholamine surges may enhance production of tissue factor, procoagulant activity or
platelet hyperaggregability.
* in the case of Q wave
Mycardial infarction results in a spreading area of necrosis that reaches epicardium in 4-6
hours – full thickness infarction
* in rare cases may be due
to coronary artery occlusion by embolism, congenital abnormalities, coronary artery spasm and
a wide variety of systemic (particularly inflammatory) diseases
* initially infarcted
muscle is softened leading to an increase in ventricular compliance but, as fibrosis takes
place, compliance of heart muscles decreases
* poor correlation between
angiographic severity of coronary stenosis and chance of acute occlusion
* Other causes of reduced
myocardial blood flow include mechanical obstruction (e.g. air embolus), dynamic obstruction
(e.g. vessel spasm), and infection or inflammation.
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