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Activation time determination by high--resolution unipolar and bipolar extracellular electrograms in the canine heart.

Introduction: To identify the optimal criteria for activation time (AT) determination of bipolar electrograms from normal hearts, a high-resolution cross electrode array comprising 128 unipolar electrodes of 500-um spacing was used to record extracellular potentials from the left ventricular epicard...

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Published in:Journal of Cardiovascular Electrophysiology Vol. 6; no. 3; pp. 174 - 189
Main Authors: Ndrepepa G, Caref EB, Yin H, el-Sherif N, Restivo M
Format: Journal Article
Published: Wiley-Blackwell Mar1995
Online Access:View this record in EBSCOhost
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        10453873
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      dt: Mar1995
      vid: 6
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      pub: Wiley-Blackwell
      place: Malden, Massachusetts
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        atl: Activation time determination by high--resolution unipolar and bipolar extracellular electrograms in the canine heart.
      aug:
        au:
          Ndrepepa G
          Caref EB
          Yin H
          el-Sherif N
          Restivo M
      sug:
        subj:
          Action Potentials Physiology
          Electrocardiography Classification
          Heart Rate Physiology
          Heart Physiology
          Animals
          Dogs
          Electrodes
          Heart Conduction System Physiology
          Male
          Time Factors
          Male
      ab: Introduction: To identify the optimal criteria for activation time (AT) determination of bipolar electrograms from normal hearts, a high-resolution cross electrode array comprising 128 unipolar electrodes of 500-um spacing was used to record extracellular potentials from the left ventricular epicardium of 12 dog hearts. Methods and Results: Recordings were made during broad wavefront propagation (B wave) and local elliptical wavefront propagation (E wave). Characteristics of 863 bipolar electrograms (1-mm spacing) were constructed from unipolar data standardized for differences in polarity, then clarified morphologically. Features for bipolar AT determination were compared to the time of the negative peak of the first temporal derivative of a unipolar electrogram situated mid-way between the bipoles. During B wave, three distinct morphologies were observed: uniphasic (61%), biphasic (23%), and triphasic (16%). Peak voltage of uniphasic and triphasic signals was the best predictor of AT (error: 0.6 ± 0.6 msec and 0.6 ± 0.8 msec, respectively). During E wave, parallel orientation of the bipoles with respect to the direction of impulse propagation wavefront resulted in uniphasic signals (> 99%), while for perpendicular orientation of the bipoles, electrogram morphology was variable. For parallel orientation of the bipoles, peak negative voltage was the best predictor of AT for both longitudinal and transverse propagation, while for perpendicular bipole orientation, peak negative voltage was a less reliable predictor for propagation along both fiber axes. Increasing interpolar distance resulted in a degradation in AT accuracy for B wave (from 0.6 ± 0.6 msec at 1 mm to 1.1 ± 1.2 msec at 7 mm) and for E wave (from 0.4 ± 0.3 msec at 1 mm to 3.1 ± 2.9 msec at 7 mm). Conclusions: (1) The accuracy of bipolar electrograms is sensitive to wavefront direction, bipole orientation, and interpolar distance; (2) peak negative voltage of uniphasic and triphasic signals is a reliable predictor of AT, but only for B wave; (3) a maximum interpolar distance of 2 mm and bipole orientation parallel to the direction of the impulse wavefront are minimally required for accurate determination of AT during impulse propagation initiated near the recording electrodes; and (4) for impulses initiated near the recording site in normal tissue, a biphasic or triphasic morphology almost certainly indicates that the bipolar electrode is oriented perpendicular to the wavefront direction, irrespective of fiber orientation.
      pubtype: Academic Journal
      doctype: Journal Article
      ougenre: Article
    language: English
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