1
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Mirloup A, Berthomé Y, Riché S, Wagner P, Hanser F, Laurent A, Iturrioz X, Llorens-Cortes C, Karpenko J, Bonnet D. Alared: Solvatochromic and Fluorogenic Red Amino Acid for Ratiometric Live-cell Imaging of Bioactive Peptides. Chemistry 2024:e202401296. [PMID: 38641990 DOI: 10.1002/chem.202401296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2024] [Accepted: 04/17/2024] [Indexed: 04/21/2024]
Abstract
To fill the need for environmentally sensitive fluorescent unnatural amino acids able to operate in the red region of the spectrum, we have designed and synthesized Alared, a red solvatochromic and fluorogenic amino acid derived from the Nile Red chromophore. The new unnatural amino acid can be easily integrated into bioactive peptides using classical solid-phase peptide synthesis. The fluorescence quantum yield and the emission maximum of Alared-labeled peptides vary in a broad range depending on the peptide's environment, making Alared a powerful reporter of biomolecular interactions. Due to its red-shifted absorption and emission spectra, Alared-labeled peptides could be followed in living cells with minimal interference from cellular autofluorescence. Using ratiometric fluorescence microscopy, we were able to track the fate of the Alared-labeled peptide agonists of the apelin G protein-coupled receptor upon receptor activation and internalization. Due to its color-shifting environmentally sensitive emission, Alared allowed for distinguishing the fractions of peptides that are specifically bound to the receptor or unspecifically bound to different cellular membranes.
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Affiliation(s)
- Antoine Mirloup
- University of Strasbourg Faculty of Pharmacy, Laboratory for Therapeutic Innovation, FRANCE
| | - Yann Berthomé
- University of Strasbourg Faculty of Pharmacy, Laboratory for Therapeutic Innovation, Faculté de Pharmacie, 67401, Illkirch, FRANCE
| | - Stéphanie Riché
- National Centre for Scientific Research, Laboratory for Therapeutic Innovation, Faculté de Pharmacie, 67401, Illkrich, FRANCE
| | - Patrick Wagner
- University of Strasbourg Faculty of Pharmacy, Laboratory for Therapeutic Innovation, Faculté de Pharmacie, 67401, Illkrich, FRANCE
| | - Fabien Hanser
- University of Strasbourg Faculty of Pharmacy, Laboratory for Therapeutic Innovation, Faculté de Pharmacie, 67401, FRANCE
| | - Arthur Laurent
- University of Strasbourg Faculty of Pharmacy, Laboratory for Therapeutic Innovation, Faculté de Pharmacie, 67401, FRANCE
| | | | - Catherine Llorens-Cortes
- INSERM, Laboratory of Central Neuropeptides in the Regulation of Body Fluid Homeostasis and Cardiovascular Functions, FRANCE
| | - Julie Karpenko
- University of Strasbourg Faculty of Pharmacy, Laboratory for Therapeutic Innovation, Faculté de Pharmacie, 67401, Illkrich, FRANCE
| | - Dominique Bonnet
- Centre National de la Recherche Scientifique, Faculté de Pharmacie, 74 route du Rhin, 67401, Illkirch, FRANCE
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2
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Hanser F, Marsol C, Valencia C, Villa P, Klymchenko AS, Bonnet D, Karpenko J. Nile Red-Based GPCR Ligands as Ultrasensitive Probes of the Local Lipid Microenvironment of the Receptor. ACS Chem Biol 2021; 16:651-660. [PMID: 33733725 DOI: 10.1021/acschembio.0c00897] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The local lipid microenvironment of transmembrane receptors is an essential factor in G protein coupled receptor (GPCR) signaling. However, tools are currently missing for studying endogenously expressed GPCRs in primary cells and tissues. Here, we introduce fluorescent environment-sensitive GPCR ligands for probing the microenvironment of the receptor in living cells using fluorescence microscopy under no-wash conditions. We designed and synthesized antagonist ligands of the oxytocin receptor (OTR) by conjugating a high-affinity nonpeptidic OTR ligand PF-3274167 to the environment-sensitive fluorescent dye Nile Red. The length of the polar PEG spacer between the pharmacophore and the fluorophore was adjusted to lower the nonspecific interactions of the probe while preserving a strong fluorogenic response. We demonstrated that the new probes embed into the lipid bilayer in the vicinity of the receptor and convey information about the local polarity and the lipid order via the wavelength-shifting emission of the Nile Red fluorophore.
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Affiliation(s)
- Fabien Hanser
- Laboratoire d’Innovation Thérapeutique, UMR7200 CNRS/Université de Strasbourg, Strasbourg Drug Discovery and Development Institute (IMS), 74 route du Rhin, 67401 Illkirch-Graffenstaden, France
| | - Claire Marsol
- Laboratoire d’Innovation Thérapeutique, UMR7200 CNRS/Université de Strasbourg, Strasbourg Drug Discovery and Development Institute (IMS), 74 route du Rhin, 67401 Illkirch-Graffenstaden, France
- Plate-forme de chimie biologique intégrative de Strasbourg (PCBiS), UMS 3286 CNRS/Université de Strasbourg, Strasbourg Drug Discovery and Development Institute (IMS), ESBS Pôle API, Bld Sébastien Brant, 67412 Illkirch-Graffenstaden, France
| | - Christel Valencia
- Plate-forme de chimie biologique intégrative de Strasbourg (PCBiS), UMS 3286 CNRS/Université de Strasbourg, Strasbourg Drug Discovery and Development Institute (IMS), ESBS Pôle API, Bld Sébastien Brant, 67412 Illkirch-Graffenstaden, France
| | - Pascal Villa
- Plate-forme de chimie biologique intégrative de Strasbourg (PCBiS), UMS 3286 CNRS/Université de Strasbourg, Strasbourg Drug Discovery and Development Institute (IMS), ESBS Pôle API, Bld Sébastien Brant, 67412 Illkirch-Graffenstaden, France
| | - Andrey S. Klymchenko
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS/Université de Strasbourg, 74 route du Rhin, 67401 Illkirch-Graffenstaden, France
| | - Dominique Bonnet
- Laboratoire d’Innovation Thérapeutique, UMR7200 CNRS/Université de Strasbourg, Strasbourg Drug Discovery and Development Institute (IMS), 74 route du Rhin, 67401 Illkirch-Graffenstaden, France
| | - Julie Karpenko
- Laboratoire d’Innovation Thérapeutique, UMR7200 CNRS/Université de Strasbourg, Strasbourg Drug Discovery and Development Institute (IMS), 74 route du Rhin, 67401 Illkirch-Graffenstaden, France
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Pfeifer B, Seger M, Hintermüller C, Hanser F, Modre R, Tilg B, Trieb T, Kremser C, Roithinger FX, Hintringer F, Fischer G. Computationally Efficient Noninvasive Cardiac Activation Time Imaging. Methods Inf Med 2018. [DOI: 10.1055/s-0038-1634024] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Summary
Objective:
The computer model-based computation of the cardiac activation sequence in humans has been recently subject of successful clinical validation. This method is of potential interest for guiding ablation therapy of arrhythmogenic substrates. However, computation times of almost an hour are unattractive in a clinical setting. Thus, the objective is the development of a method which performs the computation in a few minutes run time.
Methods:
The computationally most expensive part is the product of the lead field matrix with a matrix containing the source pattern on the cardiac surface. The particular biophysical properties of both matrices are used for speeding up this operation by more than an order of magnitude. A conjugate gradient optimizer was developed using C++ for computing the activation map.
Results:
The software was tested on synthetic and clinical data. The increase in speed with respect to the previously used Fortran 77 implementation was a factor of 30 at a comparable quality of the results. As an additional finding the coupled regularization strategy, originally introduced for saving computation time, also reduced the sensitivity of the method to the choice of the regularization parameter.
Conclusions:
As it was shown for data from a WPW-patient the developed software can deliver diagnostically valuable information at a much shorter span of time than current clinical routine methods. Its main application could be the localization of focal arrhythmogenic substrates.
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4
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Hanser F, Pfeifer B, Seger M, Hintermüller C, Modre R, Tilg B, Trieb T, Berger T, Roithinger FX, Hintringer F, Fischer G. A Signal Processing Pipeline for Noninvasive Imaging of Ventricular Preexcitation. Methods Inf Med 2018. [DOI: 10.1055/s-0038-1634001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Summary
Objectives:
Noninvasive imaging of the cardiac activation sequence in humans could guide interventional curative treatment of cardiac arrhythmias by catheter ablation. Highly automated signal processing tools are desirable for clinical acceptance. The developed signal processing pipeline reduces user interactions to a minimum, which eases the operation by the staff in the catheter laboratory and increases the reproducibility of the results.
Methods:
A previously described R-peak detector was modified for automatic detection of all possible targets (beats) using the information of all leads in the ECG map. A direct method was applied for signal classification. The algorithm was tuned for distinguishing beats with an adenosine induced AV-nodal block from baseline morphology in Wolff-Parkinson-White (WPW) patients. Furthermore, an automatic identification of the QRS-interval borders was implemented.
Results:
The software was tested with data from eight patients having overt ventricular preexcitation. The R-peak detector captured all QRS-complexes with no false positive detection. The automatic classification was verified by demonstrating adenosine-induced prolongation of ventricular activation with statistical significance (p <0.001) in all patients. This also demonstrates the performance of the automatic detection of QRS-interval borders. Furthermore, all ectopic or paced beats were automatically separated from sinus rhythm. Computed activation maps are shown for one patient localizing the accessory pathway with an accuracy of 1 cm.
Conclusions:
The implemented signal processing pipeline is a powerful tool for selecting target beats for noninvasive activation imaging in WPW patients. It robustly identifies and classifies beats. The small beat to beat variations in the automatic QRS-interval detection indicate accurate identification of the time window of interest.
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5
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Fischer G, Hanser F, Seger M, Hintermüller C, Modre-Osprian R, Trieb T, Tilg B, Pfeifer B. Atrial and Ventricular Myocardium Extraction Using Model-based Techniques. Methods Inf Med 2018. [DOI: 10.1055/s-0038-1634032] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Summary
Objectives:
This paper presents an efficient approach for extracting myocardial structures from given atrial and ventricular blood masses to enable non-invasive estimation of electrical excitation in human atria and ventricles.
Methods:
Based on given segmented atrial and ventricular blood masses, the approach constructs the myocardial structure directly, in the case that the myocardium can be detected in the volume data, or by using mean model information, in the case that the myocardium cannot be seen in the volume data due to image modalities or artefacts. The approach employs mathematical and gray-value morphology operations. Regulated by the spatial visibility of the myocardial structure in the medical image data especially the atrial myocardium needs to be estimated repeatedly using the a-priori knowledge given by the anatomy.
Results:
The approach was tested using eight patient data sets. The reconstruction process yielded satisfying results with respect to an efficient generation of a volume conductor model which is essential when trying to implement the estimation of electrical excitation in clinical application.
Conclusion:
The approach yields ventricular and atrial models that qualify for cardiac source imaging in a clinical setting.
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6
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Hanser F, Seger M, Netzer M, Osl M, Modre-Osprian R, Schreier G, Baumgartner C, Pfeifer B, Wurz M. An Epidemiological Modeling and Data Integration Framework. Methods Inf Med 2018; 49:290-6. [DOI: 10.3414/me09-02-0025] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2009] [Accepted: 03/08/2010] [Indexed: 11/09/2022]
Abstract
Summary
Objectives: In this work, a cellular automaton software package for simulating different infectious diseases, storing the simulation results in a data warehouse system and analyzing the obtained results to generate prediction models as well as contingency plans, is proposed. The Brisbane H3N2 flu virus, which has been spreading during the winter season 2009, was used for simulation in the federal state of Tyrol, Austria.
Methods: The simulation-modeling framework consists of an underlying cellular automaton. The cellular automaton model is parameterized by known disease parameters and geographical as well as demographical conditions are included for simulating the spreading. The data generated by simulation are stored in the back room of the data warehouse using the Talend Open Studio software package, and subsequent statistical and data mining tasks are performed using the tool, termed Knowledge Discovery in Database Designer (KD3).
Results: The obtained simulation results were used for generating prediction models for all nine federal states of Austria.
Conclusion: The proposed framework provides a powerful and easy to handle interface for parameterizing and simulating different infectious diseases in order to generate prediction models and improve contingency plans for future events.
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Kienast R, Stöger M, Handler M, Hanser F, Baumgartner C. Alterations of field potentials in isotropic cardiomyocyte cell layers induced by multiple endogenous pacemakers under normal and hypothermal conditions. Am J Physiol Heart Circ Physiol 2014; 307:H1013-23. [DOI: 10.1152/ajpheart.00097.2014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The use of autonomous contracting randomly grown cardiomyocyte monolayers cultivated on microelectrode arrays (MEAs) represents an accepted experimental setting for preclinical experimental research in the field of cardiac electrophysiology. A dominant pacemaker forces a monolayer to adhere to a regular and synchronized contraction. Randomly distributed multiple pacemakers interfere with this dominant center, resulting in more or less frequent changes of propagation direction. This study aims to characterize the impact of changing propagation directions at single electrodes of the MEA on the four intrinsic parameters of registered field potentials (FPs) FPrise, FPMIN, FPpre, and FPdur and conduction velocity (CV) under normal and hypothermal conditions. Primary cultures of chicken cardiomyocytes ( n = 18) were plated directly onto MEAs and FPs were recorded in a temperature range between 37 and 29°C. The number and spatiotemporal distribution of biological and artificial pacemakers of each cell layer inside and outside of the MEA registration area were evaluated using an algorithm developed in-house. In almost every second myocardial cell layer, interfering autonomous pacemakers were detected at stable temperatures, showing random spatial distributions with similar beating rates. Additionally, a temperature-dependent change of the dominant pacemaker center was observed in n = 16 experiments. A significant spread-direction-dependent variation of CV, FPrise, FPMIN, and FPpre up to 14% could be measured between different endogenous pacemakers. In conclusion, based on our results, disregarding the spatial origin of excitation may lead to misinterpretations and erroneous conclusions of FP parameters in the verification of research hypotheses in cellular electrocardiology.
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Affiliation(s)
- R. Kienast
- Institute of Electrical and Biomedical Engineering, University for Health Sciences, Medical Informatics and Technology, Hall in Tyrol, Austria; and
| | - M. Stöger
- Institute of Electrical and Biomedical Engineering, University for Health Sciences, Medical Informatics and Technology, Hall in Tyrol, Austria; and
- Division of Internal Medicine III/Cardiology, Medical University Innsbruck, Innsbruck, Austria
| | - M. Handler
- Institute of Electrical and Biomedical Engineering, University for Health Sciences, Medical Informatics and Technology, Hall in Tyrol, Austria; and
| | - F. Hanser
- Institute of Electrical and Biomedical Engineering, University for Health Sciences, Medical Informatics and Technology, Hall in Tyrol, Austria; and
| | - C. Baumgartner
- Institute of Electrical and Biomedical Engineering, University for Health Sciences, Medical Informatics and Technology, Hall in Tyrol, Austria; and
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8
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Seger M, Hanser F, Dichtl W, Stuehlinger M, Hintringer F, Trieb T, Pfeifer B, Berger T. Non-invasive imaging of cardiac electrophysiology in a cardiac resynchronization therapy defibrillator patient with a quadripolar left ventricular lead. Europace 2014; 16:743-9. [DOI: 10.1093/europace/euu045] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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9
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Kienast R, Stöger M, Handler M, Fischer G, Hanser F, Baumgartner C. Detection of Multiple Pacemaker Centers in Cardiomyocyte Cell Layers for Estimating Wavefront Propagation Patterns. BIOMED ENG-BIOMED TE 2013; 58 Suppl 1:/j/bmte.2013.58.issue-s1-G/bmt-2013-4178/bmt-2013-4178.xml. [PMID: 24042803 DOI: 10.1515/bmt-2013-4178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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10
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Kienast R, Fischer G, Stöger M, Handler M, Hanser F, Baumgartner C. A system for analysing thermal induced effects of propagation direction dependent features in field potentials of cardiomyocyte monolayers using multi-electrode arrays. J Electrocardiol 2013. [DOI: 10.1016/j.jelectrocard.2013.05.118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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11
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Pfeifer B, Hanser F, Seger M, Fischer G, Modre-Osprian R, Tilg B. Patient-specific volume conductor modeling for non-invasive imaging of cardiac electrophysiology. Open Med Inform J 2008; 2:32-41. [PMID: 19415133 PMCID: PMC2666958 DOI: 10.2174/1874431100802010032] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2008] [Revised: 01/29/2008] [Accepted: 02/24/2008] [Indexed: 11/22/2022] Open
Abstract
We propose a general workflow to numerically estimate the spread of electrical excitation in the patients' hearts. To this end, a semi-automatic segmentation pipeline for extracting the volume conductor model of structurally normal hearts is presented. The cardiac electrical source imaging technique aims to provide information about the spread of electrical excitation in order to assist the cardiologist in developing strategies for the treatment of cardiac arrhythmias. The volume conductor models of eight patients were extracted from cine-gated short-axis magnetic resonance imaging (MRI) data. The non-invasive estimation of electrical excitation was compared with the CARTO maps. The development of a volume conductor modeling pipeline for constructing a patient-specific volume conductor model in a fast and accurate way is one essential step to make the technique clinically applicable.
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Affiliation(s)
- B Pfeifer
- Institute of Biomedical Signal Processing and Imaging, University for Health Sciences, Medical Informatics and Technology (UMIT), Hall i.T., Austria
| | - F Hanser
- Research Division for Pervasive Health, University for Health Sciences, Medical Informatics and Technology (UMIT), Hall i.T. Austria
| | - M Seger
- Institute of Biomedical Signal Processing and Imaging, University for Health Sciences, Medical Informatics and Technology (UMIT), Hall i.T., Austria
| | - G Fischer
- Institute of Biomedical Signal Processing and Imaging, University for Health Sciences, Medical Informatics and Technology (UMIT), Hall i.T., Austria
| | | | - B Tilg
- Institute of Biomedical Signal Processing and Imaging, University for Health Sciences, Medical Informatics and Technology (UMIT), Hall i.T., Austria
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12
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Pfeifer B, Seger M, Hanser F, Hintermüller C, Fischer G, Mühlthaler H, Tilg B. A training whole-heart model for simulating propagation and ECG patterns. Biomed Signal Process Control 2007. [DOI: 10.1016/j.bspc.2007.06.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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13
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Pfeifer B, Fischer G, Hanser F, Seger M, Hintermüller C, Modre-Osprian R, Trieb T, Tilg B. Atrial and ventricular myocardium extraction using model-based techniques. Methods Inf Med 2006; 45:19-26. [PMID: 16482366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
OBJECTIVES This paper presents an efficient approach for extracting myocardial structures from given atrial and ventricular blood masses to enable non-invasive estimation of electrical excitation in human atria and ventricles. METHODS Based on given segmented atrial and ventricular blood masses, the approach constructs the myocardial structure directly, in the case that the myocardium can be detected in the volume data, or by using mean model information, in the case that the myocardium cannot be seen in the volume data due to image modalities or artefacts. The approach employs mathematical and gray-value morphology operations. Regulated by the spatial visibility of the myocardial structure in the medical image data especially the atrial myocardium needs to be estimated repeatedly using the a-priori knowledge given by the anatomy. RESULTS The approach was tested using eight patient data sets. The reconstruction process yielded satisfying results with respect to an efficient generation of a volume conductor model which is essential when trying to implement the estimation of electrical excitation in clinical application. CONCLUSION The approach yields ventricular and atrial models that qualify for cardiac source imaging in a clinical setting.
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Affiliation(s)
- B Pfeifer
- Institute for Biomedical Signal Processing and Imaging, University for Health Sciences, Medical Informatics and Technology (UMIT), Eduard-Wallnöfer-Zentrum 1, 6060 Hall in Tirol, Austria.
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14
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Seger M, Fischer G, Modre R, Messnarz B, Hanser F, Tilg B. Lead field computation for the electrocardiographic inverse problem--finite elements versus boundary elements. Comput Methods Programs Biomed 2005; 77:241-252. [PMID: 15721652 DOI: 10.1016/j.cmpb.2004.10.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2003] [Revised: 08/18/2004] [Accepted: 10/28/2004] [Indexed: 05/24/2023]
Abstract
In order to be able to solve the inverse problem of electrocardiography, the lead field matrix (transfer matrix) has to be calculated. The two methods applied for computing this matrix, which are compared in this study, are the boundary element method (BEM) and the finite element method (FEM). The performance of both methods using a spherical model was investigated. For a comparable discretization level, the BEM yields smaller relative errors compared to analytical solutions. The BEM needs less computation time, but a larger amount of memory. Inversely calculated myocardial activation times using either the FEM or BEM computed lead field matrices give similar activation time patterns. The FEM, however, is also capable of considering anisotropic conductivities. This property might have an impact for future development, when also individual myocardial fiber architecture can be considered in the inverse formulation.
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Affiliation(s)
- M Seger
- Institute for Biomedical Signal Processing and Imaging, University for Health Sciences, Medical Informatics and Technology, Innrain 98, 6020 Innsbruck, Austria.
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15
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Fischer G, Pfeifer B, Seger M, Hintermüller C, Hanser F, Modre R, Tilg B, Trieb T, Kremser C, Roithinger FX, Hintringer F. Computationally efficient noninvasive cardiac activation time imaging. Methods Inf Med 2005; 44:674-86. [PMID: 16400376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
OBJECTIVE The computer model-based computation of the cardiac activation sequence in humans has been recently subject of successful clinical validation. This method is of potential interest for guiding ablation therapy of arrhythmogenic substrates. However, computation times of almost an hour are unattractive in a clinical setting. Thus, the objective is the development of a method which performs the computation in a few minutes run time. METHODS The computationally most expensive part is the product of the lead field matrix with a matrix containing the source pattern on the cardiac surface. The particular biophysical properties of both matrices are used for speeding up this operation by more than an order of magnitude. A conjugate gradient optimizer was developed using C++ for computing the activation map. RESULTS The software was tested on synthetic and clinical data. The increase in speed with respect to the previously used Fortran 77 implementation was a factor of 30 at a comparable quality of the results. As an additional finding the coupled regularization strategy, originally introduced for saving computation time, also reduced the sensitivity of the method to the choice of the regularization parameter. CONCLUSIONS As it was shown for data from a WPWpatient the developed software can deliver diagnostically valuable information at a much shorter span of time than current clinical routine methods. Its main application could be the localization of focal arrhythmogenic substrates.
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Affiliation(s)
- G Fischer
- Institute for Biomedical Signal Processing and Imaging, University for Health Sciences, Medical Informatics and Technology (UMIT), Innsbruck, Austria.
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16
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Fischer G, Hanser F, Pfeifer B, Seger M, Hintermüller C, Modre R, Tilg B, Trieb T, Berger T, Roithinger FX, Hintringer F. A signal processing pipeline for noninvasive imaging of ventricular preexcitation. Methods Inf Med 2005; 44:508-15. [PMID: 16342917] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
OBJECTIVES Noninvasive imaging of the cardiac activation sequence in humans could guide interventional curative treatment of cardiac arrhythmias by catheter ablation. Highly automated signal processing tools are desirable for clinical acceptance. The developed signal processing pipeline reduces user interactions to a minimum, which eases the operation by the staff in the catheter laboratory and increases the reproducibility of the results. METHODS A previously described R-peak detector was modified for automatic detection of all possible targets (beats) using the information of all leads in the ECG map. A direct method was applied for signal classification. The algorithm was tuned for distinguishing beats with an adenosine induced AV-nodal block from baseline morphology in Wolff-Parkinson-White (WPW) patients. Furthermore, an automatic identification of the QRS-interval borders was implemented. RESULTS The software was tested with data from eight patients having overt ventricular preexcitation. The R-peak detector captured all QRS-complexes with no false positive detection. The automatic classification was verified by demonstrating adenosine-induced prolongation of ventricular activation with statistical significance (p <0.001) in all patients. This also demonstrates the performance of the automatic detection of QRS-interval borders. Furthermore, all ectopic or paced beats were automatically separated from sinus rhythm. Computed activation maps are shown for one patient localizing the accessory pathway with an accuracy of 1 cm. CONCLUSIONS The implemented signal processing pipeline is a powerful tool for selecting target beats for noninvasive activation imaging in WPW patients. It robustly identifies and classifies beats. The small beat to beat variations in the automatic QRS-interval detection indicate accurate identification of the time window of interest.
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Affiliation(s)
- G Fischer
- Institute for Biomedical Signal Processing and Imaging, University for Health Sciences, Medical Informatics and Technology, Hall i T, Austria.
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17
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Modre R, Tilg B, Fischer G, Hanser F, Messnarz B, Seger M, Hintringer F, Roithinger FX. Ventricular surface activation time imaging from electrocardiogram mapping data. Med Biol Eng Comput 2004; 42:146-50. [PMID: 15125142 DOI: 10.1007/bf02344624] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Non-invasive imaging of cardiac electrophysiology provides a non-invasive way of obtaining information about electrical excitation. An iterative algorithm based on a general regularisation scheme for non-linear, ill-posed problems in Hilbert scales was applied to the electrocardiographic inverse problem, imaging the ventricular surface activation time (AT) map. This method was applied to electrocardiographic data from a 31-year-old healthy volunteer and a 24-year-old patient suffering from a Wolff-Parkinson-White (WPW) syndrome. The objective was to evaluate non-invasive AT imaging of an autonomous sinus rhythm and to quantify the localisation error of non-invasive AT imaging by localising the accessory pathway of the WPW syndrome and a pacing site for left ventricle pacing. The distances between the invasive and non-invasive localisation of the pacing site and the accessory pathway were 8 mm and 5 mm. The clinical case presented, shows that this non-invasive AT imaging approach may enable the reconstruction of single focal events with sufficient accuracy for potential clinical application.
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Affiliation(s)
- R Modre
- Institute for Medical Signal Processing & Imaging, University for Health Informatics & Technology Tyrol, Innsbruck, Austria.
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Berger T, Hintringer F, Pachinger O, Roithinger F, Hanser F, Fischer G, Modre R, Tilg B. P-272 Prolonged P-wave duration on the 65-lead ECG in heart failure patients: Effect of atrial electrical remodeling — heralding atrial fibrillation? Europace 2003. [DOI: 10.1016/eupace/4.supplement_2.b130-b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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Berger T, Hintringer F, Dichtl W, Pachinger O, Roithinger F, Hanser F, Fischer G, Modre B, Tilg B. P-415 Impact of biventricular pacing on ventricular repolarization in patients with congestive heart failure. Europace 2003. [DOI: 10.1016/eupace/4.supplement_2.b164] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Affiliation(s)
- T. Berger
- Dep. of Cardiology, University Hospital Innsbruck
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Austria
| | - F. Hintringer
- Dep. of Cardiology, University Hospital Innsbruck
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Austria
| | - W. Dichtl
- Dep. of Cardiology, University Hospital Innsbruck
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Austria
| | - O. Pachinger
- Dep. of Cardiology, University Hospital Innsbruck
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Austria
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Fischer G, Modre R, Tilg B, Seger M, Hanser F, Messnarz B, Schocke M, Kremser C, Berger T, Roithinger F, Hintringer F. NICHTINVASIVE VISUALISIERUNG VON VENTRIKULÄRER PRÄEXZITATION DURCH KOPPLUNG VON MRI & 65-KANAL-EKG-DATEN. BIOMED ENG-BIOMED TE 2003. [DOI: 10.1515/bmte.2003.48.s1.126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Seger M, Hayn D, Fischer G, Hanser F, Pfeifer B, Hintringer F, Roithinger F, Kremser C, Schocke M, Messnarz B, Modre R, Hintermüller C, Schreier G, Tilg B. eHeart – EINE SIMULATIONSUMGEBUNG ZUR BERECHNUNG DES NAH- UND FERNFELDES. BIOMED ENG-BIOMED TE 2003. [DOI: 10.1515/bmte.2003.48.s1.10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Modre R, Fischer G, Hintringer F, Roithinger F, Schocke M, Kremser C, Hanser F, Seger M, Messnarz B, Pfeifer B, Hintermüller C, Tilg B. KOPPLUNG VON KERNSPIN-TOMOGRAPHIE UND EKG-MAPPING ZUR AKTIVIERUNGSSEQUENZBESTIMMUNG DES HERZENS. BIOMED ENG-BIOMED TE 2003. [DOI: 10.1515/bmte.2003.48.s1.94] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Seely JF, Brown CM, Holland GE, Hanser F, Wise J, Weaver JL, Korde R, Viereck RA, Grubb R, Judge DL. Calibration of an extreme-ultraviolet transmission grating spectrometer with synchrotron radiation. Appl Opt 2001; 40:1623-1630. [PMID: 18357156 DOI: 10.1364/ao.40.001623] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The responsivity of an extreme-ultraviolet transmission grating spectrometer with silicon photodiode detectors was measured with synchrotron radiation. The spectrometer was designed to record the absolute radiation flux in a wavelength bandpass centered at 30 nm. The transmission grating had a period of 200 nm and relatively high efficiencies in the +1 and the -1 diffraction orders that were dispersed on either side of the zero-order beam. Three photodiodes were positioned to measure the signals in the zero order and in the +1 and -1 orders. The photodiodes had aluminum overcoatings that passed the desired wavelength bandpass centered at 30 nm and attenuated higher-order radiation and wavelengths longer than approximately 80 nm. The spectrometer's responsivity, the ratio of the photodiode current to the incident radiation power, was determined as a function of the incident wavelength and the angle of the spectrometer with respect to the incident radiation beam. The spectrometer's responsivity was consistent with the product of the photodiode responsivity and the grating efficiency, both of which were separately measured while removed from the spectrometer.
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Modre R, Tilg B, Fischer G, Hanser F, Messnarz B, Wach P, Pachinger O, Hintringer F, Berger T, Abou-Harb M, Schocke M, Kremser C, Roithinger F. Stability of Activation Time Imaging From Single Beat Data Under Clinical Conditions. BIOMED ENG-BIOMED TE 2001. [DOI: 10.1515/bmte.2001.46.s2.213] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Tilg B, Fischer G, Modre R, Hanser F, Messnarz B, Wach P, Pachinger O, Hintringer F, Berger T, Abou-Harb M, Schocke M, Kremser C, Roithinger F. Feasibility of activation time imaging within the human atria and ventricles in the catheter laboratory. BIOMED ENG-BIOMED TE 2001. [DOI: 10.1515/bmte.2001.46.s2.223] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Messnarz B, Tilg B, Modre R, Hanser F, Fischer G, Wach P. Comparison of Transmembrane and Epicardial Potential Patterns Reconstructed by a Linear Inverse Approach. BIOMED ENG-BIOMED TE 2001. [DOI: 10.1515/bmte.2001.46.s2.147] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Hanser F, Tilg B, Fischer G, Modre R, Messnarz B, Wach P, Berger T, Pachinger O, Hintringer F, Roithinger F. ECG Signal Subtraction for Cardiac Source Imaging. BIOMED ENG-BIOMED TE 2001. [DOI: 10.1515/bmte.2001.46.s2.76] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Roithinger F, Fischer G, Modre R, Hanser F, Messnarz B, Wach P, Pachinger O, Hintringer F, Berger T, Schocke M, Kremser C, Abou-Harb M, Tilg B. Clinical Assessment of Atrial Activation - Current Methods and Future Perspectives. BIOMED ENG-BIOMED TE 2001. [DOI: 10.1515/bmte.2001.46.s2.226] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Hanser F, Koller W, Schurrer F. Treatment of laser-induced thermal acoustics in the framework of discrete kinetic theory. Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics 2000; 61:2065-73. [PMID: 11046498 DOI: 10.1103/physreve.61.2065] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/1999] [Revised: 09/03/1999] [Indexed: 11/07/2022]
Abstract
The physics behind the laser-induced thermal acoustics technique is dealt with on a microscopic level. A discrete velocity model of the Boltzmann equation for inelastically interacting gas mixtures in the presence of two counterpropagating laser beams is established. The collisional scheme for the model is developed by taking into account elastic and inelastic interactions between the gas particles, on the one hand, and the interactions between monochromatic laser photons and gas particles, on the other hand. The formation and evolution of laser-pulse-driven thermal and density gratings are simulated by numerically solving the discrete kinetic equations based on the fractional step method. Numerical results are provided for a wide scope of Knudsen numbers.
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Affiliation(s)
- F Hanser
- Institute for Theoretical Physics, Technical University Graz, Petersgasse 16, A-8010 Graz, Austria
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