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Effects of 60-Hertz notch filtering on local abnormal ventricular activities

  • Author Footnotes
    1 Drs Zhou and Jiang contributed equally to this work.
    Xiaoxiong Zhou
    Footnotes
    1 Drs Zhou and Jiang contributed equally to this work.
    Affiliations
    The First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
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  • Author Footnotes
    1 Drs Zhou and Jiang contributed equally to this work.
    Yunqiu Jiang
    Footnotes
    1 Drs Zhou and Jiang contributed equally to this work.
    Affiliations
    Section of Cardiovascular Diseases, Heart Rhythm Institute, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma

    Cardiac Arrhythmias Section, Heart Center, Beijing Chao-yang Hospital, Capital Medical University, Beijing, China
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  • Daniel Sohinki
    Affiliations
    Division of Cardiology, Medical College of Georgia, Augusta, Georgia
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  • Wei Liu
    Affiliations
    School of Computer Science and Technology, Xi’an University of Posts and Telecommunications, Xi’an, China
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  • Sunny S. Po
    Correspondence
    Address reprint requests and correspondence: Dr Sunny S. Po, 800 Stanton L. Young Blvd, Suite 5400, Oklahoma City, Oklahoma, USA 73104.
    Affiliations
    Section of Cardiovascular Diseases, Heart Rhythm Institute, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
    Search for articles by this author
  • Author Footnotes
    1 Drs Zhou and Jiang contributed equally to this work.
Published:September 07, 2020DOI:https://doi.org/10.1016/j.hrthm.2020.08.022

      Background

      It is known that electrical signals can be affected by notch filtering.

      Objective

      We sought to investigate the effect of 60-Hz notch filtering on local abnormal ventricular activities (LAVA) in patients undergoing ventricular tachycardia ablation.

      Methods

      To ensure catheter stability, only patients undergoing ablation using Stereotaxis mapping catheters were enrolled. Catheter stability was judged by the display on the electroanatomic map and the morphology of the bipolar and unipolar electrograms of the ablation catheter. At sites recording stable LAVA, 60-Hz notch filtering was applied. The duration, amplitude, and morphology of LAVA were compared before and after filtering. The area under LAVA was used to analyze the amplitude of continuous LAVA.

      Results

      A total of 110 LAVA potentials recorded from 13 patients were analyzed. Notch filtering significantly affected the LAVA morphology and reduced their amplitude (the sum of the absolute value of the largest positive and negative voltages before filtering: 0.267 mV [0.191–0.395 mV]; after filtering: 0.172 mV [0.112–0.266 mV]; P < .001). At least 2 high-frequency components were introduced into the LAVA by filtering at 33 sites. The area under continuous LAVA was reduced by 28% from 24.64 cm2 (16.20–33.45 cm2) to 17.53 cm2 (10.52–23.82 cm2) (P < .001). The duration of continuous LAVA was reduced by 12% from 79.2 ms (55.0–93.0 ms) to 69.5 ms (53.0–88.5 ms) (P < .001).

      Conclusion

      Notch filtering can distort LAVA by reducing their amplitude, changing their morphology, and shortening their duration, leading to potential false positives and negatives. Mitigating the 60-Hz noise should focus on eliminating the source of noise, not applying notch filtering.

      Keywords

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