Andreas Klotz

Removal of CPR Artifacts From the Ventricular Fibrillation ECG by Adaptive Regression on Lagged Reference Signals

Removing cardiopulmonary resuscitation (CPR)-related artifacts from human ventricular fibrillation (VF) electrocardiogram (ECG) signals provides the possibility to continuously detect rhythm changes and estimate the probability of defibrillation success. This could reduce ldquohands-offrdquo analysis times which diminish the cardiac perfusion and deteriorate the chance for successful defibrillations. Our approach consists in estimating the CPR part of a corrupted signal by adaptive regression on lagged copies of a reference signal which correlate with the CPR artifact signal. The algorithm is based on a state-space model and the corresponding Kalman recursions. It allows for stochastically changing regression coefficients. The residuals of the Kalman estimation can be identified with the CPR-filtered ECG signal. In comparison with ordinary least-squares regression, the proposed algorithm shows, for low signal-to-noise ratio (SNR) corrupted signals, better SNR improvements and yields better estimates of the mean frequency and mean amplitude of the true VF ECG signal. The preliminary results from a small pool of human VF and animal asystole CPR data are slightly better than the results of comparable previous studies which, however, not only used different algorithms but also different data pools. The algorithm carries the possibility of further optimization.

Noncommutative Approximation: Inverse-Closed Subalgebras and Off-Diagonal Decay of Matrices

We investigate two systematic constructions of inverse-closed subalgebras of a given Banach algebra or operator algebra

Strong corruption of electrocardiograms caused by cardiopulmonary resuscitation reduces efficiency of two-channel methods for removing motion artefacts in non-shockable rhythms

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CPR Artifact Removal in Ventricular Fibrillation ECG Signals Using Gabor Multipliers

, both of which are inspired by classical principles of approximation theory. The first construction requires a closed derivation or a commutative automorphism group on

Density of sampling and interpolation in reproducing kernel Hilbert spaces

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Norm-controlled inversion in smooth Banach algebras, I

and yields a family of smooth inverse-closed subalgebras of

Full length article: Spectral invariance of Besov-Bessel subalgebras

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ELIMINATION OF CPR-ARTEFACTS IN VF-ECGs BY TIME FREQUENCY METHODS

that resemble the usual Hölder–Zygmund spaces. The second construction starts with a graded sequence of subspaces of

A new concept of variable bandwidth

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Reduction of CPR artifacts in the ventricular fibrillation ECG by coherent line removal

and yields a class of inverse-closed subalgebras that resemble the classical approximation spaces. We prove a theorem of Jackson–Bernstein type to show that in certain cases both constructions are equivalent.These results about abstract Banach algebras are applied to algebras of infinite matrices with off-diagonal decay. In particular, we obtain new and unexpected conditions of off-diagonal decay that are preserved under matrix inversion.