What causes pacemaker-mediated tachycardia?

Updated: Oct 11, 2019
  • Author: Daniel M Beyerbach, MD, PhD; Chief Editor: Jeffrey N Rottman, MD  more...
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A premature ventricular contraction (PVC) in a dual-chamber pacemaker may precipitate a pacemaker-mediated tachycardia (PMT). If a PVC is transmitted in a retrograde manner through the atrioventricular node, it may, in turn, depolarize the atria. This atrial depolarization is detected by the atrial sensor, which then stimulates the ventricular leads to fire, hence creating an endless loop.

Although the maximum rate is limited by the pacemaker’s programmed upper limit, the possibility of developing ischemia exists in susceptible patients. This is another opportunity to use a magnet to diagnose and treat the arrhythmia. The magnet will place the pacemaker into asynchronous mode and sensing will be deactivated, thus preventing continuation of the reentrant dysrhythmia.

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