Beetner, D. G., and R. M. Arthur, "Direct Inference of the Spectra of Pericardial Potentials Using the Boundary-Element Method," Annals of Biomedical Engineering, vol. 27, pp. 498-507, 1999.

Abstract

New methods, based on Tikhonov regularization, were developed to directly infer the magnitude and phase of pericardial potentials. These methods were tested in an adult-male torso model using measured human epicardial potentials. With 1% noise added to body-surface potentials, regularization with an optimal parameter at each frequency from 1-100 Hz gave an average relative error (RE) in inferred spectral magnitudes of 0.44. Regularization with composite-residual-smoothing-operator (CRESO) parameter increased RE slightly to 0.47. With 10% additive noise, 10 mm overestimation of heart radius, and a 10 mm error in heart position, the average CRESO parameter from 1-100 Hz gave an average RE of 0.71. Performance was frequency dependent. The smallest REs occurred at low frequencies. With 1% noise, optimal regularization gave average REs of 0.20, 0.40, and 0.53 in the 1-15, 15-46, and 46-100 Hz bands, respectively. Direct inference of spectral magnitudes was more accurate than Fourier transformation of inferred time-domain waveforms. Results suggest that when heart size and location are not known, minimum REs in spectral estimates are found using an overestimated heart size and a regularization parameter which is the average value over the frequency band of interest.

Key words: Inverse electrocardiology, frequency components, human data, Tikhonov regularization