Certified Rhythm Analysis Technician (CRAT) Practice Exam

The presence of changes in the ST segment and T waves is a well-recognized hallmark of myocardial ischemia on an electrocardiogram (ECG). Myocardial ischemia, which occurs when blood flow to the heart muscle is reduced, leads to specific electrical changes that can be detected during ECG monitoring.

Typically, during ischemia, the ST segment may be depressed or elevated, depending on the type and severity of the ischemic event. Additionally, T wave changes, such as inversion or flattening, often accompany these shifts in the ST segment. These alterations reflect the altered repolarization process in the cardiac cells due to inadequate oxygenation and energy substrate supply.

In contrast, widening of the QRS complex usually indicates issues related to conduction delays in the ventricles, which may not be related specifically to ischemia. Changes in the QRS complex and ST segment could signify various other cardiac conditions, and the prolongation of the PR interval is more indicative of issues in atrial conduction rather than ischemic events. Therefore, recognizing the specific pattern of ST segment and T wave changes is critical in identifying myocardial ischemia accurately.