Transient myocardial ischemia among non-STEMI and unstable angina patients treated with invasive versus conservative treatment

Abstract

ventricle not only on the QRS complex, but also on the ST segment. In myocardial infarction a localized slowing of impulse propagation—the periinfarction block refers to an electrocardiographic abnormality caused by delayed activation of the myocardium in the affected region. In this study we simulated the effects of localized changes in impulse propagation on the QRS and ST-segment patterns, using computer modeling. Material and methods: The model defines the geometry of cardiac ventricles analytically as parts of ellipsoids and allows to change the velocity of impulse propagation in the myocardium. The following changes were introduced in anteroseptal and posterolateral locations: intramural electrically inactive area (infarct), encircled by a transmural area with slowed impulse propagation velocity (peri-infarction block). The effects of sole infarct and peri-infarction blocks, as well the effects of their combinations on the QRS complex and the ST segment are presented. Results: A sole intramural infarct caused QRS changes typical for corresponding locations which were further considerably modified by slowed impulse propagation velocity in the surrounding area. Additionally, the areas of slowed impulse propagation velocity in both locations caused ST-segment deviations, shifting the ST segment toward the affected areas. Conclusion: Using computer modeling we showed that the localized slowing in impulse propagation (peri-infarction block) not only modified the QRS complex, but produced also changes in the ST segment that are consistent with changes that are usually interpreted as effect of the “injury current.”