Wildhaber, Reto
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Wildhaber, Reto
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Publikation Intracoronary ECG ST-segment shift remission time during reactive myocardial hyperemia. A new method to assess hemodynamic coronary stenosis severity(American Physiological Society, 01.10.2024) Bigler, Marius Reto; Kieninger-Gräfitsch, Andrea; Rohla, Miklos; Corpateaux, Noé; Waldmann, Frédéric; Wildhaber, Reto; Häner, Jonas; Seiler, ChristianFractional flow reserve (FFR) measurements are recommended for assessing hemodynamic coronary stenosis severity. Intracoronary ECG (icECG) is easily obtainable and highly sensitive in detecting myocardial ischemia due to its close vicinity to the myocardium. We hypothesized that the remission time of myocardial ischemia on icECG after a controlled coronary occlusion accurately detects hemodynamically relevant coronary stenosis. This retrospective, observational study included patients with chronic coronary syndrome undergoing hemodynamic coronary stenosis assessment immediately following a strictly 1-min proximal coronary artery balloon occlusion with simultaneous icECG recording. icECG was used for a beat-to-beat analysis of the ST-segment shift during reactive hyperemia immediately following balloon deflation. The time from coronary balloon deflation until the ST-segment shift reached 37% of its maximum level, i.e., icECG ST-segment shift remission time (τ-icECG in seconds), was obtained by an automatic algorithm. τ-icECG was tested against the simultaneously obtained reactive hyperemia FFR at a threshold of 0.80 as a reference parameter. From 120 patients, 139 icECGs (age, 68 ± 10 yr old) were analyzed. Receiver operating characteristic (ROC) analysis of τ-icECG for the detection of hemodynamically relevant coronary stenosis at an FFR of ≤0.80 was performed. The area under the ROC curve was equal to 0.621 (P = 0.0363) at an optimal τ-icECG threshold of 8 s (sensitivity, 61%; specificity, 67%). τ-icECG correlated inversely and linearly with FFR (P = 0.0327). This first proof-of-concept study demonstrates that τ-icECG, a measure of icECG ST segment-shift remission after a 1-min coronary artery balloon occlusion accurately detects hemodynamically relevant coronary artery stenosis according to FFR at a threshold of ≥8 s.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Technical characterization of single-lead ECG signals from 4 different smartwatches and its potential clinical implications(Elsevier, 2023) Knecht, Sven; Waldmann, Frédéric; Kuhn, Raffael; Mannhart, Diego; Kühne, Michael; Sticherling, Christian; Badertscher, Patrick; Wildhaber, Reto01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Real-time feature extraction from electrocochleography with impedance measurements during cochlear implantation using linear state-space models(IEEE, 2023) Andonie, Raphael R.; Wimmer, Wilhelm; Wildhaber, Reto; Caversaccio, Marco; Weder, Stefan01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Intracoronary ECG ST-segment shift remission time during reactive coronary hyperemia (tau-icECG): a new approach to assess hemodynamic coronary stenosis severity(Oxford University Press, 2023) Kieninger-Graefitsch, Andrea; Bigler, Marius Reto; Waldmann, Frédéric; Wildhaber, Reto; Seiler, ChristianCoronary pressure-derived fractional flow reserve (FFR) measurements are recommended for hemodynamic coronary stenosis assessment. Given temporary paralysis of the coronary microcirculation during hyperemia, pressure is, in theory, directly related to coronary flow. Pressure drop during hyperemia across a coronary stenosis, thus, provides an estimate of its restrictive effect on flow. FFR during reactive hyperemia induced by a proximal, 1-minute coronary artery balloon occlusion has been shown non-inferior to FFR as obtained by adenosine-induced hyperemia. Intracoronary ECG (icECG) is more sensitive in detecting myocardial ischemia than the surface ECG, and can be easily obtained.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Algorithm for real-time analysis of intracoronary electrocardiogram(Frontiers, 07.09.2022) Bigler, Marius Reto; Kieninger-Gräfitsch, Andrea; Waldmann, Frédéric; Seiler, Christian; Wildhaber, RetoSince its first implementation in 1985, intracoronary (ic) electrocardiogram (ECG) has shown ample evidence for its diagnostic value given the higher sensitivity for myocardial ischemia detection in comparison to surface ECG. However, a lack of online systems to quantitatively analyze icECG in real-time prevents its routine use. The present study aimed to develop and validate an autonomous icECG analyzing algorithm.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Onset detection of pulse-shaped bioelectrical signals using linear state space models(De Gruyter, 02.09.2022) Waldmann, Frédéric; Baeriswyl, Christof; Andonie, Raphael; Wildhaber, RetoBioelectrical signals are often pulse-shaped with superimposed interference signals. In this context, accurate identification of features such as pulse onsets, peaks, amplitudes, and duration is a frequent problem. In this paper, we present a versatile method of rather low computational complexity to robustly identify such features in real-world signals. For that, we take use of two straight-line models fit to the observations by minimizing a quadratic cost term, and then identify desired features by tweaked likelihood measures. To demonstrate the idea and facilitate access to the method, we provide examples from the field of cardiology.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Windowed state space filters for peak interference suppression in neural spike sorting(IEEE, 2022) Wildhaber, Reto; Baeriswil, Christof; Bertrand, Alexander04B - Beitrag KonferenzschriftPublikation Signal analysis using local polynomial approximations(IEEE, 2020) Wildhaber, Reto; Ren, Elizabeth; Waldmann, Frederic; Loeliger, Hans-AndreaLocal polynomial approximations represent a versatile feature space for time-domain signal analysis. The parameters of such polynomial approximations can be computed by efficient recursions using autonomous linear state space models and often allow analytical solutions for quantities of interest. The approach is illustrated by practical examples including the estimation of the delay difference between two acoustic signals and template matching in electrocardiogram signals with local variations in amplitude and time scale.04B - Beitrag KonferenzschriftPublikation Toward a novel semi‐invasive activation mapping tool for the diagnosis of supraventricular arrhythmias from the esophagus(Wiley, 2019) Sweda, Romy; Wildhaber, Reto; Mortier, Simone; Bruegger, Dominik; Niederhauser, Thomas; Goette, Josef; Jacomet, Marcel; Tanner, Hildegard; Haeberlin, AndreasSupraventricular arrhythmia diagnosis using the surface electrocardiogram (sECG) is often cumbersome due to limited atrial signal quality. In some instances, use of esophageal electrocardiography (eECG) may facilitate the diagnosis. Here, we present a novel approach to reconstruct cardiac activation maps from eECG recordings.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Windowed state-space filters for signal detection and separation(IEEE, 2018) Wildhaber, Reto; Zalmai, Nour; Jacomet, Marcel; Loeliger, Hans-AndreaThis paper introduces a toolbox for model-based detection, separation, and reconstruction of signals that is especially suited for biomedical signals, such as electrocardiograms (ECGs) or electromyograms (EMGs). The modeling is based on autonomous linear state space models (LSSMs), which are localized with flexible windows. The models are fit to observations by minimizing the squared error while the use of LSSMs leads to efficient recursive error computations and minimizations. Multisection windows enable complex models, and per-sample weights enable multistage processing or adaptive smoothing. This paper is motivated by, and intended for, practical applications, for which several examples and tabulated cost computations are given.01A - Beitrag in wissenschaftlicher Zeitschrift