Certified EkG technician (CET) Practice Exam

The presence of which characteristic on an EKG tracing can indicate a previous myocardial infarction?

1. ST elevation

2. Pathologic Q waves

3. Regular T waves

4. Flat P waves

The correct answer is: Pathologic Q waves

Pathologic Q waves on an EKG tracing are indicative of a previous myocardial infarction (MI). When a myocardial infarction occurs, it can cause damage to the heart muscle, leading to changes in the electrical conduction of the heart. As a result, these pathologic Q waves can develop due to the necrotic tissue that is associated with a past heart attack. These Q waves are considered pathologic when they are deeper and wider than normal, reflecting the extent of myocardial damage. Their presence often suggests that the area of the heart corresponding to those leads has experienced significant ischemia or infarction in the past. In contrast, ST elevation generally indicates an acute MI or ongoing ischemia rather than a previous event. Regular T waves may merely reflect normal cardiac function, while flat P waves are non-specific and can be associated with various conditions but do not specifically indicate a prior myocardial infarction. Thus, the identification of pathologic Q waves serves as a reliable marker for recognizing a past myocardial infarction on an EKG.