pigastric region, neck, back, or arms. Some patients will deny chest pain, but describe a long history of tightness, fullness, numbness, or heaviness. Because of the wide variance in presentation, it is quite common for angina to continue unrecognized or ignored for long periods before its cardiac etiology is diagnosed.
             A myocardial infarction is distinguished from angina by its ECG manifestations and its effect on cardiac isoenzyme levels. Changes in these levels produce specific changes in the ECG tracing. The effects of an MI occur within minutes on the ECG. As myocardial injury evolves into necrosis, the ECG readings change drastically. The measurement of blood enzymes also contributes to diagnosis of MI. When myocardial cells are irreversibly damaged, intracellular enzymes leak through the cell membranes and are detectable in the blood. The most sensitive indicator of myocardial damage is a CK isoenzyme, CK-MB. The elevation of
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