Polarization potentials causing pacemaker oversensing.

Pacemaker oversensing with inappropriate inhibition is commonly caused by sensing of either T-waves or polarization potentials, which are difficult to distinguish from one another. Decisive evidence, obtained from telemetered electrograms and subthreshold pacing, is presented to support sensing of the polarization potential alone and the exclusion of the T-wave as the cause of oversensing in a patient.