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  • 1
    ISSN: 1540-8167
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Noncontact Endocardial Mapping. Introduction: Mapping endocardial activation and repolarization processes is critical to the study of arrhythmias and selection of therapeutic procedures. Previously, we developed methodology for reconstructing endocardial potentials from potentials measured with a noncontact, intracavitary probe. This study further develops and evaluates the ability of the approach to provide detailed information on the spatiotemporal characteristics of the activation process. Specifically, we reconstructed endocardial electrograms and isochrones throughout the activation process over the entire endocardium during a single beat. Methods and Results: Cavity potentials were measured with a 65-electrode probe placed inside an isolated canine left ventricle. Endocardial potentials were measured simultaneously using 52 electrodes. Potentials were acquired during subendocardial pacing from different locations. Computed electrograms at various sites closely resemble the measured electrograms (correlation coefficient 〉 0.9 at 60% of the electrodes). Computed isochrones locate subendocardial pacing sites with 10-mm accuracy. Two pacing sites, 17 mm apart, were resolved. Critical regions, such as areas of isochrone crowding, were accurately reconstructed. Conclusions: Results indicate the applicability of the approach to mapping the cardiac excitation process on a beat-by-beat basis without occluding the ventricle. The ability of locating electrical events (e.g., single or multiple initiation sites) is demonstrated. Importantly, the method is shown to be capable of reconstructing electrograms over the entire endocardium and determining nonuniformities of activation spread (e.g., areas of slow conduction). These capabilities are important to clinical application in the electrophysiology laboratory and experimental studies of arrhythmias in the intact animal.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Annals of biomedical engineering 26 (1998), S. 994-1009 
    ISSN: 1573-9686
    Keywords: EP catheter mapping ; Simultaneous endocardial mapping ; Noncontact endocardial mapping ; Endocardial potential mapping
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract In previous studies, we established methodology for reconstructing endocardial potentials, electrograms and isochrones from a non-contact intracavitary probe during a single beat. The probe was too large to be introduced percutaneously. Here we examine the possibility of similar mapping with a small multielectrode catheter that could be introduced percutaneously and does not expand inside the cavity. Cavity geometry and endocardial potentials were recorded in an isolated canine left ventricle. Simulated catheter probes were introduced into the cavity. Probe potentials were computed from the measured endocardial potentials and perturbed to include measurement noise, geometrical errors, and limited electrode density. Endocardial potentials were then reconstructed from the perturbed probe potentials and compared to the actual measured potentials. Of all probes simulated, a 3.0 mm (9F) catheter that assumes a curved geometry (e.g., a J shape) inside the cavity performed best (better than a larger 7.6 mm cylinder simulating an inflatable probe). Without bending, a straight cylindrical probe of the same size (9F, 3.0 mm) did not perform well. Sixty probe electrodes were needed for accurate reconstruction. The J-probe reconstruction was very robust in the presence of noise (10%) and of geometry errors (3 mm shift, 10° rotation). The results demonstrate the feasibility of accurate single-beat endocardial mapping using a 9F percutaneous multielectrode catheter that assumes a J shape in the cavity without the need for expansion (e.g., into a balloon or a “basket”). The robustness of the procedure to noise and geometrical errors suggests its applicability in the clinical EP laboratory and the possibility of determining probe position in vivo using current imaging modalities. © 1998 Biomedical Engineering Society. PAC98: 8759Wc
    Type of Medium: Electronic Resource
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