Effect of reference electrode on intracardiac electrograms: Close indifferent electrode vs Wilson central terminal

Tasuku Yamamoto; Masateru Takigawa; Takatoshi Shigeta; Claire A Martin; Junji Yamaguchi; Miki Amemiya; Takashi Ikenouchi; Miho Negishi; Iwanari Kawamura; Kentaro Goto; Takuro Nishimura; Tomomasa Takamiya; Susumu Tao; Shinsuke Miyazaki; Masahiko Goya; Tetsuo Sasano

doi:10.1016/j.hrthm.2024.03.002

Effect of reference electrode on intracardiac electrograms: Close indifferent electrode vs Wilson central terminal

Heart Rhythm. 2024 Mar 7:S1547-5271(24)00237-6. doi: 10.1016/j.hrthm.2024.03.002. Online ahead of print.

Authors

Tasuku Yamamoto¹, Masateru Takigawa², Takatoshi Shigeta¹, Claire A Martin³, Junji Yamaguchi¹, Miki Amemiya¹, Takashi Ikenouchi¹, Miho Negishi¹, Iwanari Kawamura¹, Kentaro Goto⁴, Takuro Nishimura¹, Tomomasa Takamiya¹, Susumu Tao¹, Shinsuke Miyazaki⁴, Masahiko Goya¹, Tetsuo Sasano¹

Affiliations

¹ Department of Cardiovascular Medicine, Tokyo Medical and Dental University Hospital, Tokyo, Japan.
² Department of Cardiovascular Medicine, Tokyo Medical and Dental University Hospital, Tokyo, Japan; Division of Advanced Arrhythmia Research, Tokyo Medical and Dental University Hospital, Tokyo, Japan. Electronic address: teru.takigawa@gmail.com.
³ Department of Cardiology, Royal Papworth Hospital, Cambridge, United Kingdom; Department of Medicine, University of Cambridge, Cambridge, United Kingdom.
⁴ Department of Cardiovascular Medicine, Tokyo Medical and Dental University Hospital, Tokyo, Japan; Division of Advanced Arrhythmia Research, Tokyo Medical and Dental University Hospital, Tokyo, Japan.

PMID: 38460753
DOI: 10.1016/j.hrthm.2024.03.002

Abstract

Background: 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.

Objective: 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.

Methods: 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.

Results: 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).

Conclusion: 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.

Keywords: Bipolar; Electrograms; Mapping; Unipolar; Voltage.