{Reference Type}: Journal Article
{Title}: Effect of reference electrode on intracardiac electrograms: Close indifferent electrode vs Wilson central terminal.
{Author}: Yamamoto T;Takigawa M;Shigeta T;Martin CA;Yamaguchi J;Amemiya M;Ikenouchi T;Negishi M;Kawamura I;Goto K;Nishimura T;Takamiya T;Tao S;Miyazaki S;Goya M;Sasano T;
{Journal}: Heart Rhythm
{Volume}: 21
{Issue}: 8
{Year}: 2024 Aug 7
{Factor}: 6.779
{DOI}: 10.1016/j.hrthm.2024.03.002
{Abstract}: <B>BACKGROUND: </B>Unipolar electrograms (uni-EGMs) are an essential part of intracardiac mapping. Although Wilson central terminal (WCT) is conventionally used as a reference for signals, avoidance of contamination by far-field and nonphysiologic signals is challenging.<BR><B>OBJECTIVE: </B>The aim of the study was to explore the impact of an intracardiac indifferent reference electrode close to the recording electrodes, in lieu of WCT, on electrograms.<BR><B>METHODS: </B>Sinus node activation was mapped in patients undergoing catheter ablation by a multielectrode array with a close indifferent electrode (CIE) embedded in the distal end of the catheter shaft. An equal number of points was sequentially acquired at each site with use of CIE as a reference first and subsequently with WCT. Uni-EGMs, bipolar EGMs, and the earliest activation area (defined as the area activated in the first 10 ms of the beat) were compared between CIE- and WCT-based activation maps.<BR><B>RESULTS: </B>Seventeen patients (61 ± 18 years; 76% male) were studied. Uni-EGM voltages acquired with CIE were significantly larger than (n = 11) or comparable to (n = 4) those acquired with WCT. When points from the entire cohort were analyzed altogether, unipolar voltages and their maximum negative dV/dT and bipolar voltages recorded with CIE were significantly larger than those recorded with WCT (2.36 [1.42-3.79] mV vs 1.96 [1.25-3.03] mV, P < .0001; 0.40 [0.18-0.77] mV/s vs 0.35 [0.15-0.71] mV/s, P < .0001; and 1.46 [0.66-2.81] mV vs 1.33 [0.54-2.64] mV, P < .0001, respectively). The earliest activation area was significantly smaller in CIE-based activation maps than in WCT-based ones (0.3 [0.7-1.4] cm2 vs 0.6 [1.0-1.8] cm2, P = .01).<BR><B>CONCLUSIONS: </B>CIE-based maps were associated with an approximately 20% increase in unipolar voltage and may highlight the origin of a focal activation more clearly than WCT-based ones.