Willard S. Ellis

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BACKGROUND The relation between heterogeneously coupled myocardium and fractionated electrograms is incompletely understood. The purpose of this study was to use a detailed computer model of nonuniformly anisotropic myocardium to test the hypothesis that spatial variation of morphology of electrograms recorded simultaneously from multiple sites increases(More)
INTRODUCTION Atrial fibrillation is not entirely random, but little is known about the spatiotemporal endocardial organization and its surface ECG manifestations. METHODS AND RESULTS In 16 patients with atrial fibrillation (chronic, n = 14), endocardial mapping of the trabeculated, the posteroseptal smooth right atrium, and the coronary sinus was(More)
Although atrial fibrillation is a common arrhythmia, the underlying mechanisms are incompletely understood. Recent studies have determined the role of the crista terminalis in the mechanisms of a simpler arrhythmia, atrial flutter. We hypothesize that as transverse coupling across the crista terminalis increases, the activation pattern that results is less(More)
BACKGROUND Two important signal processing applications in electrophysiology are activation mapping and characterization of the tissue substrate from which electrograms are recorded. We hypothesize that a novel signal-processing method that uses deconvolution is more accurate than amplitude, derivative, and manual activation time estimates. We further(More)
OBJECTIVES This study was directed at developing spatial 62-lead electrocardiogram (ECG) criteria for classification of counterclockwise (CCW) and clockwise (CW) typical atrial flutter (Fl) in patients with and without structural heart disease. BACKGROUND Electrocardiographic classification of CCW and CW typical atrial Fl is frequently hampered by(More)
To further understand the relation between heterogeneously infarcted myocardium and fractionated electrograms, a computer model was used to test the hypothesis that the way electrogram metrics change with electrode location relates to statistical properties of the underlying myocardium. A sheet of Beeler-Reuter elements was coupled with cytoplasmic(More)
Törbel provides an interesting test case for the study of the relationship between inbreeding measured by pedigrees and inbreeding measured by isonymy. At the start of this investigation, we were aware that isonymy could introduce biases into the calculation of the inbreeding coefficient in either direction. However, it was expected that in Switzerland,(More)
A system for calibrating the Respitrace impedance plethysmograph was developed with the capacity to quantitatively verify the accuracy of calibration. LabVIEW software was used on a Macintosh II computer to create a user-friendly environment, with the added benefit of reducing development time. The system developed enabled a research assistant to calibrate(More)