I stumbled on this document:
in a Google search.
It is quite good and especially useful on those nights when the cardiologists are in bed but you have to provide anesthesia for an emergency and the patient arrives with a pacemaker and no one knows anything about it.
Be sure to read about “magical magnets” on pages 9-12. Here is an excerpt:
Are magnets magic?
This is important to ask this because it is not uncommon in “pacemaker-land” to hear, “Oh, don’t worry about the pacer, just put a magnet on it.” or “If there is a problem, I’ll just put a magnet on it.” When you hear this magical thinking, the next thing you should ask is, if magnets magically solved all pacemaker problems, why don’t they just put a magnet permanently on the pacer? Or better yet, sell a magnet with each pacemaker and have the patient wear the magnet in a special shirt pocket magically precluding all pacemaker problems?
The entire point of a pacemaker’s sensing is to avoid R-on-T. When you select an asynchronous pacing mode such as VOO or DOO, by placing a magnet over the pacer, YOU become the sensor.
The bottom line is this. When YOU put a magnet on the pacer, YOU just took over monitoring this patient’s pacemaker’s sensing function. It is in this situation that an R-on-T from the pacemaker is possible. Stay alert.