A new floating sensor array to detect electric near fields of beating heart preparations

Hofer, Eberhard P.; Keplinger, Franz; Thurner, Thomas; Wiener, Thomas; Sánchez‐Quintana, Damian; Climent, Vicente; Plank, Gernot

doi:10.1016/j.bios.2005.11.010

Cited by 25 publications

(16 citation statements)

References 14 publications

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“…2 B. Electrograms (ϕ e ) were recovered for each grid point at a distance of 60 µm above the tissue [27]. The amplitude ϕ e amp of the biphasic unipolar electrogram, ϕ e , calculated as the difference between its positive and negative peaks, as well as the fractionation index (FI), i.e.…”

Section: Methodsmentioning

confidence: 99%

Electroanatomical Characterization of Atrial Microfibrosis in a Histologically Detailed Computer Model

Campos

Wiener

Prassl

et al. 2013

IEEE Trans. Biomed. Eng.

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Fibrosis is thought to play an important role in formation and maintenance of atrial fibrillation (AF). The propensity of fibrosis to increase AF vulnerability depends not only on its amount, its texture plays a crucial role as well. While the detection of fibrotic tissue patches in the atria with extracellular recordings is feasible based on the analysis of electrogram fractionation, as used in clinical practice to identify ablation targets, the classification of fibrotic texture is a more challenging problem. This study seeks to establish a method for the electro-anatomical characterization of the fibrotic textures based on the analysis of electrogram fractionation. The proposed method exploits the dependency of fractionation patterns on the incidence direction of wavefronts which differs significantly as a function of texture. A histologically detailed computer model of the right atrial isthmus was developed for testing the method. A stimulation protocol was conceived which generated various incidence directions for any given recording site where electrograms were computed. A classification method is derived then for discriminating three types of fibrosis, no fibrosis (control), diffuse and patchy fibrosis. Simulation results showed that electrogram fractionation and amplitudes and their dependency upon incidence direction allow a robust discrimination between different classes of fibrosis. Finally, to minimize the technical effort, sensitivity analysis was performed to identify a minimum number of incidence directions required for robust classification.

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Section: Methodsmentioning

confidence: 99%

Electroanatomical Characterization of Atrial Microfibrosis in a Histologically Detailed Computer Model

Campos

Wiener

Prassl

et al. 2013

IEEE Trans. Biomed. Eng.

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“…The preferred axis of conduction was assumed to be aligned with the y axis, i.e., the main axis of the cylinder. The thin-walled muscle was immersed in a bath of dimensions 11 × 15 × 7 mm 3 to account for bath-loading as it is always present with experimental set-ups employing superfusion [16, 36]. The muscle was positioned 1 mm above the bottom of the bath and centered in the x–y plane.…”

Section: Methodsmentioning

confidence: 99%

“…3). The distance of 60 μm to the surface was chosen to match new contact recording systems for extracellular potentials [16]. Other conduction parameters based on extracellular potentials, such as the amplitude of the biphasic signal ϕ e calculated as the difference between its positive and negative peaks, the time difference between these two peaks T PP and the negative peak of the time derivative were evaluated.…”

Section: Methodsmentioning

confidence: 99%

Influence of ischemic core muscle fibers on surface depolarization potentials in superfused cardiac tissue preparations: a simulation study

Campos

Prassl

Seemann

et al. 2012

Med Biol Eng Comput

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Thin-walled cardiac tissue samples superfused with oxygenated solutions are widely used in experimental studies. However, due to decreased oxygen supply and insufficient wash out of waste products in the inner layers of such preparations, electrophysiological functions could be compromised. Although the cascade of events triggered by cutting off perfusion is well known, it remains unclear as to which degree electrophysiological function in viable surface layers is affected by pathological processes occurring in adjacent tissue. Using a 3D numerical bidomain model, we aim to quantify the impact of superfusion-induced heterogeneities occurring in the depth of the tissue on impulse propagation in superficial layers. Simulations demonstrated that both the pattern of activation as well as the distribution of extracellular potentials close to the surface remain essentially unchanged. This was true also for the electrophysiological properties of cells in the surface layer, where most relevant depolarization parameters varied by less than 5.5 %. The main observed effect on the surface was related to action potential duration that shortened noticeably by 53 % as hypoxia deteriorated. Despite the known limitations of such experimental methods, we conclude that superfusion is adequate for studying impulse propagation and depolarization whereas repolarization studies should consider the influence of pathological processes taking place at the core of tissue sample.

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“…A recent computer study has confirmed this hypothesis [4]. [5]. Unipolar extracellular potentials Φ e were derived with respect to a circular Ag/AgCl reference electrode at the bottom of the tissue bath.…”

Section: Introductionmentioning

confidence: 77%

Circumferential Pacing Reveals Microstructure of Cardiac Tissue Preparations from Small Animals – An Approach to Classify Microfibrosis

Arnold¹,

Wiener²,

Schwarz³

et al. 2012

Biomedical Engineering / Biomedizinische Technik

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Micro-obstacles like microvessels, intercellular clefts and fibrotic layers in cardiac tissue influence the propagation of an excitation wavefront and therefore may lead to arrhythmias. Detection and classification of these structures is challenging because of the small dimensions of the fibrotic inlays and their different spatial characteristics. Our hypothesis is that local recordings of extracellular signals with high spatial resolution can reveal structural properties by applying electrical stimuli around the recording site and analyzing the directional dependence of signal parameters. Myocardial preparations of 5 guinea pigs and 5 rabbits were used. A flexible miniature sensor array comprising 4 electrodes with 50 µm inter-electrode spacing was placed on the tissue preparation to record extracellular potentials. The tissue was paced at varying positions around the sensor array at twice threshold current. For analysis the signal amplitude A and the fractionation index FI (i.e. the number of deflections within the potential waveform) were computed. The evaluated parameters showed the expected directional dependence and therefore enable the classification of the directional dependence of pacing site on extracellular potentials. This could provide the basis to characterize and quantify fibrosis in cardiac tissue by means of pacing techniques and signal analysis.

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A new floating sensor array to detect electric near fields of beating heart preparations

Cited by 25 publications

References 14 publications

Electroanatomical Characterization of Atrial Microfibrosis in a Histologically Detailed Computer Model

Electroanatomical Characterization of Atrial Microfibrosis in a Histologically Detailed Computer Model

Influence of ischemic core muscle fibers on surface depolarization potentials in superfused cardiac tissue preparations: a simulation study

Circumferential Pacing Reveals Microstructure of Cardiac Tissue Preparations from Small Animals – An Approach to Classify Microfibrosis

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