Impact of electrode placement and configuration on performance of morphological measures of intraventricular electrograms

The authors assess the effect of position of the catheter electrodes on morphology analysis is both unipolar and bipolar configuration. Unfiltered bipolar and unipolar intraventricular electrograms were recorded from an electrode catheter initially positioned in the right ventricular (RV) apex (site 1) of 13 patients during sinus rhythm and induced monomorphic ventricular tachycardia (VT). Sinus rhythm and the identical VT were recorded a second time after repositioning the same electrode catheter within the RV apex (site 2) 0.2-4.4 cm from its original site. Analysis of unipolar electrograms detected 10/10 VTs at both sites, whereas analysis of bipolar electrograms detected 8/10 VTs at site 1 and 9/10 VTs at site 2, but was successful in all ten using a choice of either site 1 or 2. Thus, unipolar electrogram analysis for VT detection is less affected than bipolar electrogram analysis by a change in electrode catheter position but bipolar electrograms can be equally effective with a careful and judicious choice of electrode placement