What causes pacemaker oversensing?

Updated: Oct 11, 2019
  • Author: Daniel M Beyerbach, MD, PhD; Chief Editor: Jeffrey N Rottman, MD  more...
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Oversensing occurs when a pacer incorrectly senses noncardiac electrical activity and is inhibited from pacing. This may result in a heart rate lower than the preset rate. This form of output failure may be due to muscular activity (particularly of the diaphragm or pectoralis muscles), electromagnetic interference (EMI) (from magnetic resonance imaging [MRI]), or fractured lead insulation. Oversensing is one condition that is diagnosable and treatable with magnet application. As mentioned before, magnet application will convert the pacemaker to asynchronous mode, and it will then operate at the preset rate.

Of note, it has been reported that cellular phones held within 10 cm of the pulse generator may elicit this response. [64]

Individual implantable cardioverter-defibrillator (ICD) manufacturers also have recommendations for unsafe devices that may interact with the ICD (eg, Medtronic’s “Electromagnetic Compatibility Guide” [65] ).

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