Diagnosis: NSR w/ acute inferior infarct

Discussion: Note the deep Q waves in the inferior leads along w/ ST segment elevation and T wave inversions in the same leads. Often times an inferior MI is felt not as chest pain but as GI symptoms, due to the way the pain is refferred. ST segment elevation is a mark of injury while the Q wave is a mark of actually dead tissue. If this had been an old infarct there would be no ST seg elevation (or at least not this much), only Q waves.

The way I understand it, the ST segment elevation during acute myocardial injury can be explained as follows: In the normal non ischemic heart the ST segment represents that period in systole when the ventricles are contracted and all the ventrcular myocardium has depolarized, such that all the muscle is now positively charged relative to the resting state. Since all the muscle is "positive" there is no "less positive" area in the ventricles for charge to flow towards, so we see no current movement and a nice flat line on the EKG. Myocardial injury creates a "less positive" area for current to flow towards. The way I think of it is that if tissue is injured, during systole it can't generate the same amount of inward current flow as regular healthy tissue and so can't get as positive as surrounding tissue. Thus during the ST seg, current will flow from surrounding healthy tissue towards the injured area and cause a positive deflection in those leads measuring current flow towards the injured area. In this case the inferior leads.