Patient Care Technician (PCT) AAH Practice Exam

What indicates an Atrial Pace on an ECG?

1. Spike after the QRS complex

2. Spike before the QRS complex only

3. Spike before the P wave

4. Irregular spikes with no identifiable pattern

The correct answer is: Spike before the P wave

An Atrial Pace on an ECG is indicated by a spike that occurs before the P wave. This spike represents the electrical impulse generated by the pacemaker in the atrium, which triggers atrial depolarization. In a properly functioning heart, the P wave follows the electrical activity generated by the atrial pacemaker. When the spike appears before the P wave, it shows that the pacing originates in the atria, as the pacemaker is responsible for initiating the electrical signal that prompts the heart to contract. This timing is essential to differentiate an atrial pacemaker from other types of pacing where the spike might occur at different intervals related to the cardiac cycle. The presence of spikes after or coinciding with the QRS complex generally indicates ventricular pacing, while irregular spikes with no identifiable pattern do not provide the definitive timing needed to classify the pacing activity. Therefore, the spike appearing specifically before the P wave is the identifying characteristic of Atrial Pace on an ECG.