Global comparisons between contact and noncontact mapping techniques in the right atrium: Role of cavitary probe size

In the right atrium (RA) we globally investigated: (1) the properties of no ncontact electrograms measured by multielectrode cavitary probes, (2) the f eatures of endocardial electrograms computed from the noncontact probe elec trograms, and (3) the impact of the probe size on both the noncontact and t he computed electrograms. We deployed a custom catheter in the dog RA, whic h consisted of a cylindrical probe with 64 electrodes on its surface, for m easuring noncontact cavitary electrograms, and a concentric endocardial bas ket carrying an additional array of 64 electrodes, for measuring contact en docardial electrograms (the "gold standard"). Both a 5-mm- and a 10-mm-diam probe (P5 and P10, respectively) were sequentially tested in the same RA o f one dog. Unipolar electrograms from both the probe and the basket were si multaneously acquired during normal as well as during paced rhythms (n grea ter than or equal to 24 protocols per probe). Boundary element method and n umeric regularization were applied to compute endocardial electrograms at t he basket electrode locations. We found that non contact electrograms were attenuated and smoothed, and this effect was exaggerated with the small pro be. Computed endocardial electrograms more accurately reconstructed importa nt amplitude distribution and morphological features; peak-to-peak amplitud e error, 35% for P5 and 34% for P10. Activation and spatial errors of compu ted endocardial electrograms were 8.8 +/- 6.8 ms and 5.1 +/- 6.1 mm for P5, respectively, and 6.0 +/- 5.5 ms and 3.2 +/- 4.4 mm for P10, respectively. In conclusion, global RA activation may be delineated directly from noncon tact cavitary electrograms alone, but may be affected by volume attenuation , smoothing, and probe size. Accurate endocardial electrograms, however, ca n be successfully computed from noncontact electrograms acquired with small probes and be used to reconstruct both electrogram amplitude and detailed morphology. (C) 2001 Biomedical Engineering Society.