Certified Medical-Surgical Registered Nurse Practice Exam

What characteristic on an ECG strip indicates the presence of premature ventricular contractions (PVCs)?

1. An indiscernible PR interval

2. P waves that appear erratic

3. P waves that have a saw tooth configuration

4. A QRS complex followed by a compensatory pause

The correct answer is: A QRS complex followed by a compensatory pause

The presence of premature ventricular contractions (PVCs) on an ECG strip is indicated by a specific characteristic where a QRS complex occurs earlier than expected and is typically followed by a compensatory pause. This compensatory pause represents the heart's attempt to reset its normal rhythm after the premature beat. In PVCs, the QRS complexes are wide and bizarre in shape, reflecting that they originate from the ventricles rather than the atria, which is why the pause is crucial for recognizing this type of dysrhythmia. The irregularity in timing created by the PVC, along with the compensatory pause, allows clinicians to differentiate these events from normal heart rhythms and other types of arrhythmias. This is a key identifying feature of PVCs, helping guide appropriate management and assessment of the patient's cardiac status.