ST segment elevation and other ECG findings in myocardial infarction
The ST segment is isoelectric under normal conditions, since after ventricular depolarization the ventricular myocytes are at the plateau phase (phase 2). During this period the ventricular cells have similar voltages, so that no voltage gradient exists. In certain pathophysiologic conditions the ST segment can change from baseline. The most important cause for changes in the ST segment is myocardial ischemia and myocardial infarction. Evaluation for the presence of myocardial ischemia or myocardial infarction is one of the most important uses of the ECG.