Progressive Care Nursing Certification (PCCN) Practice Exam

Which leads should be monitored for ST segment changes in a patient with suspected ACS?

1. III or V5

2. II or V1

3. I or aVL

4. II or aVF

The correct answer is: III or V5

Monitoring ST segment changes is crucial in assessing a patient with suspected Acute Coronary Syndromes (ACS) because these changes can indicate myocardial ischemia or infarction. Leads III and V5 provide valuable insights into the inferior and lateral aspects of the heart, respectively. Lead III is particularly useful for detecting changes in the inferior wall by monitoring the electrical activity from the heart's inferior surface. V5, placed in the left anterior chest, is effective for observing the lateral wall of the left ventricle. Changes in the ST segment in these leads can reveal significant ischemic events that are often associated with ACS. In contrast, leads II and V1 primarily capture electrical activity from the inferior leads and the septal area, respectively, and may not be as effective for diagnosing lateral wall ischemia. Likewise, leads I and aVL also focus on the lateral wall of the heart but lack the comprehensive view of both inferior and lateral that leads III and V5 provide. Finally, while leads II and aVF can monitor the inferior wall as well, they do not capture the overall wide range of changes that can occur during ACS as effectively as the first mentioned pair. Thus, monitoring leads III and V5 enhances the ability to detect significant ST segment changes