Symptomatic ischemic heart disease is associated with reduction reached 65% or more of one or
more.

Most acute M.I are caused by preexisting atherosclerosis with thrombosis.

Myocardial necrosis begins within 20 to 40 minutes of time of coronary artery
occlusion.

The myocardial infarctstypically begin with subepicardial region,

subendocardial region,.it's the last area to receive blood from branches of the epicardial coronary
arteries.

The infarct usually reach the full size within 3 to 6 hours,

occlusion of left anterior descending coronary artery
cause infarction of anterior and basal areas of left ventricle.

occlusion of the right
coronary artery is responsible for most infarcts involving the posterior and basal
portions of left ventricle.

occlusion of more proximal
segments of the coronary arteries products larger infarcts involving the full
thickness of myocardium

occlusion of more distal arterial branches cause large zone of infarcts,

long standing coronary atherosclerosis, collateral circulation
may develop over time in response to chronic ischemia, this collateral increase the size
of infarct.

with M.I for the first 18 hours no changes
are evident on gross examination ,

Microscopically: Coagulative necrosis become apparent by about 12 to 18 hours in MI

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