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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Annals of biomedical engineering 26 (1998), S. 994-1009 
    ISSN: 1573-9686
    Schlagwort(e): EP catheter mapping ; Simultaneous endocardial mapping ; Noncontact endocardial mapping ; Endocardial potential mapping
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Technik allgemein
    Notizen: 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
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Annals of biomedical engineering 26 (1998), S. 597-607 
    ISSN: 1573-9686
    Schlagwort(e): Electrocardiography ; Cardiac mapping ; Activation ; Electric potential fields ; Excitation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Technik allgemein
    Notizen: Abstract In mapping the electrical activity of the heart, interpolation of electric potentials plays two important roles. First, it permits the estimation of potentials in regions that could not be sampled or where signal quality was poor, and second, it supports the construction of isopotential lines and surfaces for visualization. The difficulty in developing robust interpolation techniques for cardiac applications lies in the abrupt change in potential in the vicinity of the activation wave front. Despite the resulting nonlinearities in spatial potential distributions, simple linear interpolation methods are the current standard and the resulting errors due to aliasing can be large if electrode spacing does not lie on the order of 0.5–2 mm—the thickness of the activation wave front. We have developed a novel interpolation method that is based on two observations specific to the spread of excitation in the heart: (1) that propagation velocity changes smoothly within a region large enough to contain several measurement electrodes and (2) that electrogram morphology varies very little in the neighborhood of each sample point except for a time shift in the potential wave forms. The resulting interpolation scheme breaks the interpolation of one highly nonlinear variable—extracellular potential—into two separate interpolations of variables with much less drastic spatial variation—activation time and electrogram morphology. We have applied this method to potentials originally recorded at 1.5 mm spacing and then subsampled at a range of densities for testing of the interpolation. The results based both on reconstruction of isopotential contour maps and statistical comparison showed significant improvement of this novel approach over standard linear techniques. The applications of the new method include improved determination of electrophysiological parameters such as spatial gradients of potential and the path of cardiac activation and recovery, estimation of electrograms at desired locations, and visualization of electric potential distributions. © 1998 Biomedical Engineering Society. PAC98: 8790+y, 0260Ed, 8710+e
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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