Quote from JeffTheRN
Threshold is basically the amount of voltage required to achieve the desired effect. example... patient is bradycardic..pacer pads are in place, but no pacer capture is being achieved...turn up the voltage until pacing commences, this is your pacing threshold.
I'm not sure if this is an industry-wide practice, but whenever pacing someone in the ER, the doc orders the # of beats per minute and amount of electricity. You continue increasing electricity, or voltage, until mechanical and electrical capture is achieved (palpable pulse rate and a pacer spike just before every QRS that correlates with desired heart rate) and then increase voltage by 10 millivolts. That's my understanding of threshold.