Progressive Care Nursing Certification (PCCN) Practice Exam

Which of the following ECG changes indicates myocardial ischemia?

1. ST-segment elevation

2. ST-segment depression and T-wave elevation

3. Q-wave formation

4. ST-segment depression and T-wave inversion

The correct answer is: ST-segment depression and T-wave inversion

The presence of ST-segment depression and T-wave inversion on an ECG is indicative of myocardial ischemia. These changes reflect a lack of adequate blood supply to the heart muscle, typically caused by conditions like coronary artery disease. ST-segment depression occurs when there is a decrease in the electrical activity of the heart muscle, which signifies that the heart is experiencing stress and not receiving enough oxygen (ischemia). T-wave inversion is often associated with this state as it suggests alterations in the repolarization of the heart muscle cells due to the ischemic environment. In contrast, other options describe variations that might be seen in different cardiac conditions. ST-segment elevation generally indicates acute myocardial infarction (AMI) rather than ischemia, as it reflects active injury rather than reversible ischemic changes. ST-segment depression paired with T-wave elevation is less common and doesn't represent the typical ischemic pattern. Q-wave formation suggests an old myocardial infarction and is a permanent change rather than one indicating current ischemic events. Understanding these different changes on the ECG helps determine the underlying cardiac condition and guides appropriate management strategies.