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McCann A, Luca A, Pascale P, Pruvot E, Vesin JM. Novel spatiotemporal processing tools for body-surface potential map signals for the prediction of catheter ablation outcome in persistent atrial fibrillation. Front Physiol 2022; 13:1001060. [PMID: 36246141 PMCID: PMC9557152 DOI: 10.3389/fphys.2022.1001060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Accepted: 09/08/2022] [Indexed: 11/13/2022] Open
Abstract
Background: Signal processing tools are required to efficiently analyze data collected in body-surface-potential map (BSPM) recordings. A limited number of such tools exist for studying persistent atrial fibrillation (persAF). We propose two novel, spatiotemporal indices for processing BSPM data and test their clinical applicability through a comparison with the recently proposed non-dipolar component index (NDI) for prediction of single-procedure catheter ablation (CA) success rate in persAF patients.Methods: BSPM recordings were obtained with a 252-lead vest in 13 persAF patients (8 men, 63 ± 8 years, 11 ± 13 months sustained AF duration) before undergoing CA. Each recording was divided into seven 1-min segments of high signal quality. Spatiotemporal ventricular activity (VA) cancellation was applied to each segment to isolate atrial activity (AA). The two novel indices, called error-ratio, normalized root-mean-square error (ERNRMSE) and error-ratio, mean-absolute error (ERABSE), were calculated. These indices quantify the capacity of a subset of BSPM vest electrodes to accurately represent the AA, and AA dominant frequency (DF), respectively, on all BSPM electrodes over time, compared to the optimal principal component analysis (PCA) representation. The NDI, quantifying the fraction of energy retained after removal of the three largest PCs, was also calculated. The two novel indices and the NDI were statistically compared between patient groups based on single-procedure clinical CA outcome. Finally, their predictive power for univariate CA outcome classification was assessed using receiver operating characteristic (ROC) analysis with cross-validation for a logistic regression classifier.Results: Patient clinical outcomes were recorded 6 months following procedures, and those who had an arrhythmia recurrence at least 2 months post-CA were defined as having a negative outcome. Clinical outcome information was available for 11 patients, 6 with arrhythmia recurrence. Therefore, a total of 77 1-min AA-BSPM segments were available for analysis. Significant differences were found in the values of the novel indices and NDI between patients with arrhythmia recurrence post-ablation and those without. ROC analysis showed the best CA outcome predictive performance for ERNRMSE (AUC = 0.77 ± 0.08, sensitivity = 76.2%, specificity = 84.8%).Conclusion: Significant association was found between the novel indices and CA success or failure. The novel index ERNRMSE additionally shows good predictive power for single-procedure CA outcome.
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Affiliation(s)
- Anna McCann
- Applied Signal Processing Group, Department of Electrical Engineering, Swiss Federal Institute of Technology, Lausanne, Switzerland
- *Correspondence: Anna McCann,
| | - Adrian Luca
- Service of Cardiology, Lausanne University Hospital, Lausanne, Switzerland
| | - Patrizio Pascale
- Service of Cardiology, Lausanne University Hospital, Lausanne, Switzerland
| | - Etienne Pruvot
- Service of Cardiology, Lausanne University Hospital, Lausanne, Switzerland
| | - Jean-Marc Vesin
- Applied Signal Processing Group, Department of Electrical Engineering, Swiss Federal Institute of Technology, Lausanne, Switzerland
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Prigent G, Aminian K, Rodrigues T, Vesin JM, Millet GP, Falbriard M, Meyer F, Paraschiv-Ionescu A. Indirect Estimation of Breathing Rate from Heart Rate Monitoring System during Running. SENSORS 2021; 21:s21165651. [PMID: 34451093 PMCID: PMC8402314 DOI: 10.3390/s21165651] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 07/23/2021] [Accepted: 08/12/2021] [Indexed: 11/16/2022]
Abstract
Recent advances in wearable technologies integrating multi-modal sensors have enabled the in-field monitoring of several physiological metrics. In sport applications, wearable devices have been widely used to improve performance while minimizing the risk of injuries and illness. The objective of this project is to estimate breathing rate (BR) from respiratory sinus arrhythmia (RSA) using heart rate (HR) recorded with a chest belt during physical activities, yielding additional physiological insight without the need of an additional sensor. Thirty-one healthy adults performed a run at increasing speed until exhaustion on an instrumented treadmill. RR intervals were measured using the Polar H10 HR monitoring system attached to a chest belt. A metabolic measurement system was used as a reference to evaluate the accuracy of the BR estimation. The evaluation of the algorithms consisted of exploring two pre-processing methods (band-pass filters and relative RR intervals transformation) with different instantaneous frequency tracking algorithms (short-term Fourier transform, single frequency tracking, harmonic frequency tracking and peak detection). The two most accurate BR estimations were achieved by combining band-pass filters with short-term Fourier transform, and relative RR intervals transformation with harmonic frequency tracking, showing 5.5% and 7.6% errors, respectively. These two methods were found to provide reasonably accurate BR estimation over a wide range of breathing frequency. Future challenges consist in applying/validating our approaches during in-field endurance running in the context of fatigue assessment.
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Affiliation(s)
- Gaëlle Prigent
- Laboratory of Movement Analysis and Measurement, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland; (K.A.); (T.R.); (M.F.); (A.P.-I.)
- Correspondence:
| | - Kamiar Aminian
- Laboratory of Movement Analysis and Measurement, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland; (K.A.); (T.R.); (M.F.); (A.P.-I.)
| | - Tiago Rodrigues
- Laboratory of Movement Analysis and Measurement, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland; (K.A.); (T.R.); (M.F.); (A.P.-I.)
| | - Jean-Marc Vesin
- Applied Signal Processing Group, Institute of Electrical Engineering of the Swiss Federal Institute of Technology, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland;
| | - Grégoire P. Millet
- Institute of Sport Sciences, University of Lausanne, 1015 Lausanne, Switzerland; (G.P.M.); (F.M.)
| | - Mathieu Falbriard
- Laboratory of Movement Analysis and Measurement, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland; (K.A.); (T.R.); (M.F.); (A.P.-I.)
| | - Frédéric Meyer
- Institute of Sport Sciences, University of Lausanne, 1015 Lausanne, Switzerland; (G.P.M.); (F.M.)
| | - Anisoara Paraschiv-Ionescu
- Laboratory of Movement Analysis and Measurement, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland; (K.A.); (T.R.); (M.F.); (A.P.-I.)
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McCann A, Vesin JM, Pruvot E, Roten L, Sticherling C, Luca A. ECG-Based Indices to Characterize Persistent Atrial Fibrillation Before and During Stepwise Catheter Ablation. Front Physiol 2021; 12:654053. [PMID: 33859573 PMCID: PMC8042333 DOI: 10.3389/fphys.2021.654053] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Accepted: 03/05/2021] [Indexed: 11/13/2022] Open
Abstract
Background: Consistently successful patient outcomes following catheter ablation (CA) for treatment of persistent atrial fibrillation (pers-AF) remain elusive. We propose an electrocardiogram (ECG) analysis designed to (1) refine selection of patients most likely to benefit from ablation, and (2) examine the temporal evolution of AF organization indices that could act as clinical indicators of ongoing ablation effectiveness and completeness. Method: Twelve-lead ECG was continuously recorded in 40 patients (61 ± 8 years) during stepwise CA (step-CA) procedures for treatment of pers-AF (sustained duration 19 ± 11 months). Following standard pre-processing, ECG signals were divided into 10-s epochs and labeled according to their temporal placement: pre-PVI (baseline), dur-PVI (during pulmonary vein isolation), and post-PVI (during complex-fractionated atrial electrograms and linear ablation). Instantaneous frequency (IF), adaptive organization index (AOI), sample entropy (SampEn) and f-wave amplitude (FWA) measures were calculated and analyzed during each of the three temporal steps. Temporal evolution of these measures was assessed using a statistical test for mean value transitions, as an indicator of changes in AF organization. Results were then compared between: (i) patients grouped according to step-CA outcome; (ii) patients grouped according to type of arrhythmia recurrence following the procedure, if applicable; (iii) within the same patient group during the three different temporal steps. Results: Stepwise CA patient outcomes were as follows: (1) left-atrium (LA) terminated, not recurring (LTN, n = 8), (2) LA terminated, recurring (LTR, n = 20), and (3) not LA terminated, all recurring at follow-up (NLT, n = 12). Among the LTR and NLT patients, recurrence occurred as AF in seven patients and atrial tachycardia or atrial flutter (AT/AFL) in the remaining 25 patients. The ECG measures indicated the lowest level of organization in the NLT group for all ablation steps. The highest organization was observed in the LTN group, while the LTR group displayed an intermediate level of organization. Regarding time evolution of ECG measures in dur-PVI and post-PVI recordings, stepwise ablation led to increases in AF organization in most patients, with no significant differences between the LTN, LTR, and NLT groups. The median decrease in IF and increase in AOI were significantly greater in AT/AFL recurring patients than in AF recurring patients; however, changes in the SampEn and FWA parameters were not significantly different between types of recurrence. Conclusion: Noninvasive ECG measures, though unable to predict arrhythmia recurrence following ablation, show the lowest levels of AF organization in patients that do not respond well to step-CA. Increasing AF organization in post-PVI may be associated with organized arrhythmia recurrence after a single ablation procedure.
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Affiliation(s)
- Anna McCann
- Applied Signal Processing Group, Swiss Federal Institute of Technology, Lausanne, Switzerland
| | - Jean-Marc Vesin
- Applied Signal Processing Group, Swiss Federal Institute of Technology, Lausanne, Switzerland
| | - Etienne Pruvot
- Service of Cardiology, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Laurent Roten
- Department of Cardiology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | | | - Adrian Luca
- Service of Cardiology, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
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Abstract
Mathematical modeling of nystagmus oscillations is a technique with applications in diagnostics, treatment evaluation, and acuity testing. Modeling is a powerful tool for the analysis of nystagmus oscillations but quality assessment of the input data is needed in order to avoid misinterpretation of the modeling results. In this work, we propose a signal quality metric for nystagmus waveforms, the normalized segment error (NSE). The NSE is based on the energy in the error signal between the observed oscillations and a reconstruction from a harmonic sinusoidal model called the normalized waveform model (NWM). A threshold for discrimination between nystagmus oscillations and disturbances is estimated using simulated signals and receiver operator characteristics (ROC). The ROC is optimized to find noisy segments and abrupt waveform and frequency changes in the simulated data that disturb the modeling. The discrimination threshold, 𝜖, obtained from the ROC analysis, is applied to real recordings of nystagmus data in order to determine whether a segment is of high quality or not. The NWM parameters from both the simulated dataset and the nystagmus recordings are analyzed for the two classes suggested by the threshold. The optimized 𝜖 yielded a true-positive rate and a false-positive rate of 0.97 and 0.07, respectively, for the simulated data. The results from the NWM parameter analysis show that they are consistent with the known values of the simulated signals, and that the method estimates similar model parameters when performing analysis of repeated recordings from one subject.
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Short-term reproducibility of parameters characterizing atrial fibrillatory waves. Comput Biol Med 2020; 117:103613. [DOI: 10.1016/j.compbiomed.2020.103613] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 01/04/2020] [Accepted: 01/07/2020] [Indexed: 11/21/2022]
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Paliakaitė B, Petrėnas A, Henriksson M, Skibarkienė J, Kubilius R, Sörnmo L, Marozas V. Atrial fibrillation frequency tracking in ambulatory ECG signals: The significance of signal quality assessment. Comput Biol Med 2018; 102:227-233. [PMID: 30236913 DOI: 10.1016/j.compbiomed.2018.08.027] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Revised: 08/27/2018] [Accepted: 08/27/2018] [Indexed: 11/16/2022]
Abstract
An approach to atrial fibrillation (AF) frequency tracking in long-term ambulatory ECG recordings is presented, comprising f-wave extraction, dominant atrial frequency (DAF) tracking, and signal quality assessment. Since poor signal quality is commonly encountered in ambulatory monitoring, a recently proposed index is employed to assess f-wave signal quality in a database containing 38 patients with permanent AF. The index ensures that DAF outliers, typically associated with poor-quality segments, are excluded from further analysis. 40% of all 5-s signal segments were excluded from the database due to poor quality. The exclusion of DAF outliers significantly reduces the standard deviation of the frequency estimates (p≤0.01), allowing more reliable evaluation of the difference between day- and night-time DAF. The results show that signal quality assessment plays a central role in DAF tracking, and therefore should be employed in ambulatory monitoring.
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Affiliation(s)
- Birutė Paliakaitė
- Biomedical Engineering Institute, Kaunas University of Technology, Kaunas, Lithuania.
| | - Andrius Petrėnas
- Biomedical Engineering Institute, Kaunas University of Technology, Kaunas, Lithuania
| | - Mikael Henriksson
- Department of Biomedical Engineering and Center for Integrative Electrocardiology (CIEL), Lund University, Lund, Sweden
| | - Jurgita Skibarkienė
- Hospital of Lithuanian University of Health Sciences Kaunas Clinics, Kaunas, Lithuania
| | - Raimondas Kubilius
- Hospital of Lithuanian University of Health Sciences Kaunas Clinics, Kaunas, Lithuania
| | - Leif Sörnmo
- Department of Biomedical Engineering and Center for Integrative Electrocardiology (CIEL), Lund University, Lund, Sweden
| | - Vaidotas Marozas
- Biomedical Engineering Institute, Kaunas University of Technology, Kaunas, Lithuania; Department of Electronics Engineering, Kaunas University of Technology, Kaunas, Lithuania
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Henriksson M, García-Alberola A, Goya R, Vadillo A, Melgarejo-Meseguer FM, Sandberg F, Sörnmo L. Changes in f-wave characteristics during cryoballoon catheter ablation. Physiol Meas 2018; 39:105001. [PMID: 30183676 DOI: 10.1088/1361-6579/aadf1d] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE Changes in ECG-derived parameters are studied in atrial fibrillation (AF) patients undergoing cryoballoon catheter ablation. APPROACH Parameters characterizing f-wave frequency, morphology by phase dispersion, and amplitude are estimated using a model-based statistical approach. These parameters are studied before, during, and after ablation, as well as for AF type (paroxysmal/persistent). Seventy-seven (49/28 paroxysmal/persistent) AF patients undergoing de novo catheter ablation are included in the study, out of which 31 (16/15 paroxysmal/persistent) were in AF during the whole procedure. A signal quality index (SQI) is used to identify analyzable segments. MAIN RESULTS f-wave frequency decreased significantly during ablation (p = 0.001), in particular after ablation of the inferior right pulmonary vein (p < 0.05). Frequency and phase dispersion differed significantly between paroxysmal and persistent AF (p = 0.001 and p < 0.05, respectively). SIGNIFICANCE This study demonstrates that a decrease in f-wave frequency can be distinguished during catheter ablation. The use of an SQI ensures reliable analysis and produces results significantly different from those obtained without an SQI.
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Affiliation(s)
- Mikael Henriksson
- Department of Biomedical Engineering and Center of Integrative Electrocardiology, Lund University, Lund, Sweden
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Fallet S, Lemay M, Renevey P, Leupi C, Pruvot E, Vesin JM. Can one detect atrial fibrillation using a wrist-type photoplethysmographic device? Med Biol Eng Comput 2018; 57:477-487. [PMID: 30218408 DOI: 10.1007/s11517-018-1886-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 08/17/2018] [Indexed: 10/28/2022]
Abstract
This study aims at evaluating the potential of a wrist-type photoplethysmographic (PPG) device to discriminate between atrial fibrillation (AF) and other types of rhythm. Data from 17 patients undergoing catheter ablation of various arrhythmias were processed. ECGs were used as ground truth and annotated for the following types of rhythm: sinus rhythm (SR), AF, and ventricular arrhythmias (VA). A total of 381/1370/415 10-s epochs were obtained for the three categories, respectively. After pre-processing and removal of segments corresponding to motion artifacts, two different types of feature were derived from the PPG signals: the interbeat interval-based features and the wave-based features, consisting of complexity/organization measures that were computed either from the PPG waveform itself or from its power spectral density. Decision trees were used to assess the discriminative capacity of the proposed features. Three classification schemes were investigated: AF against SR, AF against VA, and AF against (SR&VA). The best results were achieved by combining all features. Accuracies of 98.1/95.9/95.0 %, specificities of 92.4/88.7/92.8 %, and sensitivities of 99.7/98.1/96.2 % were obtained for the three aforementioned classification schemes, respectively. Graphical Abstract Atrial fibrillation detection using PPG signals.
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Affiliation(s)
- Sibylle Fallet
- Swiss Federal Institute of Technology, Lausanne, Switzerland.
| | - Mathieu Lemay
- Swiss Center for Electronics and Microtechnology (CSEM), Neuchâtel, Switzerland
| | - Philippe Renevey
- Swiss Center for Electronics and Microtechnology (CSEM), Neuchâtel, Switzerland
| | - Célestin Leupi
- Arrhythmia Unit, Heart and Vascular Department, Lausanne University Hospital, Lausanne, Switzerland
| | - Etienne Pruvot
- Arrhythmia Unit, Heart and Vascular Department, Lausanne University Hospital, Lausanne, Switzerland
| | - Jean-Marc Vesin
- Swiss Federal Institute of Technology, Lausanne, Switzerland
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Buttu A, Vesin JM, Van Zaen J, Ballabeni P, Pascale P, Forclaz A, Bisch L, Rollin A, Maury P, Roten L, Pruvot E. A High Baseline Electrographic Organization Level Is Predictive of Successful Termination of Persistent Atrial Fibrillation by Catheter Ablation. JACC Clin Electrophysiol 2016; 2:746-755. [PMID: 29759754 DOI: 10.1016/j.jacep.2016.05.017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Revised: 05/03/2016] [Accepted: 05/12/2016] [Indexed: 10/20/2022]
Abstract
OBJECTIVES This study sought to investigate whether the level of organization of electrocardiographic (ECG) signals based on novel indexes is predictive of persistent atrial fibrillation (pAF) termination by catheter ablation (CA). BACKGROUND Whether the level of ECG organization in pAF is correlated with the restoration of sinus rhythm by CA remains unknown. METHODS Thirty consecutive patients who underwent stepwise CA for pAF (sustained duration 19 ± 11 months) were included in the study (derivation cohort). ECG lead V6 was placed on the patients' back (V6b) to improve left atrial (LA) recording. Two novel ECG indexes were computed using an adaptive harmonic frequency tracking scheme: 1) the adaptive organization index (AOI), which quantifies the cyclicity of AF harmonic oscillations; and 2) the adaptive phase index (API), which quantifies the phase coupling between the harmonic components. Index cutoff values predictive of procedural AF termination were then tested on a validation cohort of 8 consecutive patients. RESULTS In the derivation cohort, CA terminated AF in 21 patients within the LA (70%; left-terminated [LT] group), whereas CA did not terminate AF in 9 patients (30%; non-left-terminated [NLT] group). LT patients displayed a higher ECG organization level at baseline than the NLT patients, with the best separation achieved by AOI and API computed on lead V1 (area under the curve [AUC] = 0.94 and AUC = 0.88, respectively; p < 0.05) and API on lead V6b (AUC = 0.83; p < 0.05). Similar results were obtained for both AOI and API in the validation cohort. CONCLUSIONS Patients in whom pAF terminated within the LA exhibited a higher level of atrial ECG organization, which was suggestive of a limited number of LA drivers than that of patients in whom the pAF could not be terminated by CA.
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Affiliation(s)
- Andréa Buttu
- Applied Signal Processing Group, Lausanne Federal Institute of Technology, Lausanne, Switzerland
| | - Jean-Marc Vesin
- Applied Signal Processing Group, Lausanne Federal Institute of Technology, Lausanne, Switzerland
| | - Jérôme Van Zaen
- Applied Signal Processing Group, Lausanne Federal Institute of Technology, Lausanne, Switzerland
| | - Pierluigi Ballabeni
- Clinical Research Centre and Institute of Social and Preventive Medicine, Lausanne University Hospital, Lausanne, Switzerland
| | - Patrizio Pascale
- Service of Cardiology, Lausanne University Hospital, Lausanne, Switzerland
| | - Andrei Forclaz
- Service of Cardiology, Lausanne University Hospital, Lausanne, Switzerland
| | - Laurence Bisch
- Service of Cardiology, Lausanne University Hospital, Lausanne, Switzerland
| | - Anne Rollin
- Service of Cardiology, Centre Universitaire de Rangueuil, Toulouse, France
| | - Philippe Maury
- Service of Cardiology, Centre Universitaire de Rangueuil, Toulouse, France
| | - Laurent Roten
- Department of Cardiology, Inselspital, Bern University Hospital, Bern, Switzerland
| | - Etienne Pruvot
- Service of Cardiology, Lausanne University Hospital, Lausanne, Switzerland.
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Luca A, Buttu A, Pruvot E, Pascale P, Bisch L, Vesin JM. Nonlinear analysis of right atrial electrograms predicts termination of persistent atrial fibrillation within the left atrium by catheter ablation. Physiol Meas 2016; 37:347-59. [PMID: 26863592 DOI: 10.1088/0967-3334/37/3/347] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The termination of long-standing persistent atrial fibrillation (LS-pAF) can be achieved by stepwise catheter ablation (step-CA) within the left atrium (LA). Our study aims to applying complexity measures derived from nonlinear time series analysis in order to characterize LS-pAF in terms of organization and to identify patients in whom AF can be terminated from those in whom AF cannot be terminated by step-CA within the LA. A total of 33 consecutive patients (age 61 ± 7 years, sustained AF duration 19 ± 11 months) with LS-pAF underwent step-CA. The organization of right bipolar electrograms before and during the ablation procedure was assessed using the coarse-grained correlation dimension. LS-pAF was terminated into sinus rhythm or atrial tachycardia in 22 patients during step-CA within the LA (left terminated patients-LT). In 11 patients the ablation procedure failed to terminate AF within LA (not left terminated patients-NLT). The statistical analysis of the estimated coarse-grained correlation dimension revealed that a higher right atrial (RA) organization before step-CA was associated to AF termination within the LA. During the ablation procedure, the level of RA organization displayed distinctive evolution between LT and NLT patients with a significant organization increase before AF termination for the LT patients.
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Affiliation(s)
- Adrian Luca
- Applied Signal Processing Group, Swiss Federal Institute of Technology, Lausanne, Switzerland
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