COMPARISON OF SENSING BEHAVIOR OF UNIPOLAR AND BIPOLAR ELECTRODES

This evaluation compares the sensing of pacemakers programmed to uni- and bipolar mode, especially with respect to the sensing behaviour in the atrial channel. 15 sophisticated dual-chamber pacing systems with programmable polarity in each channel together with real-time telemetry were included in this prospective project. The mean intracardiac signal size recorded unipolar tip and bipolar in the ventricle was the same. The mean signal size in the atrium recorded from the tip of the lead (unipolar tip) was always larger than the bipolar signal. The difference was statistically significant, mean difference was 10-14%. Interferences through muscle potentials could be provoked during unipolar sensing, they led either to triggering and inhibition of the pacemaker or resulted in asynchronous reversion. Pacemaker-mediated tachycardias could be provoked in the atrium during uni- and bipolar sensing conditions. Results: Bioelectrical behaviour with respect to sensing of the intracardiac signals is comparable in uni- and bipolar lead configuration. Bipolar sensing is especially beneficial in the atrial channel, since interferences through muscle noise, far-field signals and EMI are reduced to a minimum. A differential programming to prevent or terminate pacemaker-induced tachycardias utilizing the option unipolar versus bipolar is not available.