In order to identify generic mechanisms for altering the ECG during ischemia, we explored changes in the action potential propagation during different ischemic conditions using simple cellular models. Based on the Beeler-Reuter and Lou-Rudy I cellular models, we developed a ventricular tissue model for probing how alterations in shape and propagation of action potential distorted the theoretical ECG signal. If arrhythmias are a characteristic of acute ischemia, the changes in ST segment duration and T wave shape seems to be related with chronic ischemia and presence of the unexcitable medium. During different stages of ischemia, the changes in theoretical ECG indicated possibilities for detecting the relation between cellular changes and external measurement of the electrical activity of the heart.
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