Patient Care Technician (PCT) AAH Practice Exam

What is the maximum QRS duration for a PAC?

1. 0.12 seconds

2. 0.08 seconds

3. 0.10 seconds

4. 0.14 seconds

The correct answer is: 0.12 seconds

For a premature atrial contraction (PAC), the maximum QRS duration is typically considered to be 0.12 seconds. This is due to the fact that PACs originate in the atria and, under normal circumstances, the electrical impulse usually passes through the conduction system to the ventricles without significant delay. When the QRS complex is within 0.12 seconds, it indicates that the ventricle is conducting the impulse normally. If the QRS duration exceeds this limit, it may suggest that there is some other conduction abnormality present, but for a typical PAC, the QRS should remain within this duration. In contrast, a duration longer than 0.12 seconds for a PAC could indicate a wider complex rhythm, suggesting a different etiology, such as a premature ventricular contraction (PVC) or other ventricular conduction delays. Therefore, knowing the standard maximum duration for a PAC is crucial for accurately interpreting cardiac rhythms.