What electrical event is indicated when a spike precedes the QRS in a paced rhythm?

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Multiple Choice

What electrical event is indicated when a spike precedes the QRS in a paced rhythm?

A spike before the QRS in a rhythm that is paced shows the pacemaker delivering a stimulus to the heart. That pacing spike is the device’s electrical impulse, and when a QRS follows, it means the impulse successfully captured the ventricle and caused depolarization. In other words, the heart is being paced. If you compare with the other patterns, an atrial tachycardia would not show a pacing spike driving the QRS; a junctional rhythm has little or no clear P waves and its QRS originates differently; sinus rhythm shows normal P waves before each QRS without any pacing spike.

A spike before the QRS in a rhythm that is paced shows the pacemaker delivering a stimulus to the heart. That pacing spike is the device’s electrical impulse, and when a QRS follows, it means the impulse successfully captured the ventricle and caused depolarization. In other words, the heart is being paced.

If you compare with the other patterns, an atrial tachycardia would not show a pacing spike driving the QRS; a junctional rhythm has little or no clear P waves and its QRS originates differently; sinus rhythm shows normal P waves before each QRS without any pacing spike.

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