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Xu CH, Xiong F, Jiang WF, Liu X, Liu T, Qin M. Rotor mechanism and its mapping in atrial fibrillation. Europace 2023; 25:783-792. [PMID: 36734272 PMCID: PMC10062333 DOI: 10.1093/europace/euad002] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2022] [Accepted: 12/28/2022] [Indexed: 02/04/2023] Open
Abstract
Treatment of atrial fibrillation (AF) remains challenging despite significant progress in understanding its underlying mechanisms. The first detailed, quantitative theory of functional re-entry, the 'leading circle' model, was developed more than 40 years ago. Subsequently, in decades of study, an alternative paradigm based on spiral waves has long been postulated to drive AF. The rotor as a 'spiral wave generator' is a curved 'vortex' formed by spin motion in the two-dimensional plane, identified using advanced mapping methods in experimental and clinical AF. However, it is challenging to achieve complementary results between experimental results and clinical studies due to the limitation in research methods and the complexity of the rotor mechanism. Here, we review knowledge garnered over decades on generation, electrophysiological properties, and three-dimensional (3D) structure diversity of the rotor mechanism and make a comparison among recent clinical approaches to identify rotors. Although initial studies of rotor ablation at many independent centres have achieved promising results, some inconclusive outcomes exist in others. We propose that the clinical rotor identification might be substantially influenced by (i) non-identical surface activation patterns, which resulted from a diverse 3D form of scroll wave, and (ii) inadequate resolution of mapping techniques. With rapidly advancing theoretical and technological developments, future work is required to resolve clinically relevant limitations in current basic and clinical research methodology, translate from one to the other, and resolve available mapping techniques.
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Affiliation(s)
- Chang-Hao Xu
- Department of Cardiology, Shanghai Chest Hospital, School of Medicine,
Shanghai Jiao Tong University, 241 Huaihai West Road, Xuhui
District, Shanghai 200030, China
| | - Feng Xiong
- Montreal Heart Institute, Department of Medicine, University of
Montreal, 5000, Bélanger street, Montréal, Québec H1T
1C8, Canada
| | - Wei-Feng Jiang
- Department of Cardiology, Shanghai Chest Hospital, School of Medicine,
Shanghai Jiao Tong University, 241 Huaihai West Road, Xuhui
District, Shanghai 200030, China
| | - Xu Liu
- Department of Cardiology, Shanghai Chest Hospital, School of Medicine,
Shanghai Jiao Tong University, 241 Huaihai West Road, Xuhui
District, Shanghai 200030, China
| | - Tao Liu
- Corresponding authors. Tao Liu, 238 Jiefang Road, Wuchang
District, Wuhan, Hubei 430060, China. Tel: +86 (027) 8804 1911, Fax:+86-(027)-8804-2292.
E-mail address:; Mu Qin, 241 Huaihai
West Road, Xuhui District, Shanghai, 200030, China. Tel: +8621628219902603, Fax:
+862162821105. E-mail address:
| | - Mu Qin
- Corresponding authors. Tao Liu, 238 Jiefang Road, Wuchang
District, Wuhan, Hubei 430060, China. Tel: +86 (027) 8804 1911, Fax:+86-(027)-8804-2292.
E-mail address:; Mu Qin, 241 Huaihai
West Road, Xuhui District, Shanghai, 200030, China. Tel: +8621628219902603, Fax:
+862162821105. E-mail address:
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Martinez-Mateu L, Saiz J, Berenfeld O. Rotors Drift Toward and Stabilize in Low Power Regions in Heterogeneous Models of Atrial Fibrillation. COMPUTING IN CARDIOLOGY 2022; 49:10.22489/cinc.2022.366. [PMID: 37560510 PMCID: PMC10411388 DOI: 10.22489/cinc.2022.366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/11/2023]
Abstract
Atrial fibrillation (AF) afflicts more than 33 million people worldwide. Success of therapy strategies remains poor and better understanding of the arrhythmia and how to device more effective therapies are needed. The aim of this work is to study the role of electric power distributions in rotors and AF dynamics. For this purpose, single cell and tissue simulations were performed to study the effect of ionic currents gradients and fibrosis in rotor's drifting. The root mean square of the ionic (Pion), capacitance (Pc) and electrotonic (Pele) power was computed over action potentials. Single cell simulations were performed for different values of IK1 and ICaL and number of coupled myofibroblasts. Tissue simulations were performed in presence of IK1 and ICaL gradients and diffused fibrosis. Single cell simulations showed that Pion and Pc increased with IK1, while decreased by increasing ICaL. Increasing the number of coupled myofibroblasts reduced Pion and Pc, whereas Pele increased. Finally, in tissue simulations rotors drifted to regions with low power and anchored in regions with higher density of blunted ionic induced power gradients.
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Affiliation(s)
| | - Javier Saiz
- Universitat Politècnica de València, Valencia, Spain
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3
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Salvador-Montañés Ó, Ramirez RJ, Takemoto Y, Ennis SR, Garcia-Iglesias D, Wang S, Wolfer PJ, Jiang J, Mironov SV, Pandit SV, Jalife J, Berenfeld O. Panoramic Endocardial Optical Mapping Demonstrates Serial Rotors Acceleration and Increasing Complexity of Activity During Onset of Cholinergic Atrial Fibrillation. J Am Heart Assoc 2021; 10:e022300. [PMID: 34726079 PMCID: PMC8751940 DOI: 10.1161/jaha.121.022300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background Activation during onset of atrial fibrillation is poorly understood. We aimed at developing a panoramic optical mapping system for the atria and test the hypothesis that sequential rotors underlie acceleration of atrial fibrillation during onset. Methods and Results Five sheep hearts were Langendorff perfused in the presence of 0.25 µmol/L carbachol. Novel optical system recorded activations simultaneously from the entire left and right atrial endocardial surfaces. Twenty sustained (>40 s) atrial fibrillation episodes were induced by a train and premature stimuli protocol. Movies obtained immediately (Initiation stage) and 30 s (Early Stabilization stage) after premature stimulus were analyzed. Serial rotor formation was observed in all sustained inductions and none in nonsustained inductions. In sustained episodes maximal dominant frequency increased from (mean±SD) 11.5±1.74 Hz during Initiation to 14.79±1.30 Hz at Early Stabilization (P<0.0001) and stabilized thereafter. At rotor sites, mean cycle length (CL) during 10 prerotor activations increased every cycle by 0.53% (P=0.0303) during Initiation and 0.34% (P=0.0003) during Early Stabilization. In contrast, CLs at rotor sites showed abrupt decreases after the rotors appearances by a mean of 9.65% (P<0.0001) during both stages. At Initiation, atria‐wide accelerations and decelerations during rotors showed a net acceleration result whereby post‐rotors atria‐wide minimal CL (CLmin) were 95.5±6.8% of the prerotor CLmin (P=0.0042). In contrast, during Early Stabilization, there was no net acceleration in CLmin during accelerating rotors (prerotor=84.9±11.0% versus postrotor=85.8±10.8% of Initiation, P=0.4029). Levels of rotor drift distance and velocity correlated with atria‐wide acceleration. Nonrotor phase singularity points did not accelerate atria‐wide activation but multiplied during Initiation until Early Stabilization. Increasing number of singularity points, indicating increased complexity, correlated with atria‐wide CLmin reduction (P<0.0001). Conclusions Novel panoramic optical mapping of the atria demonstrates shortening CL at rotor sites during cholinergic atrial fibrillation onset. Atrial fibrillation acceleration toward Early Stabilization correlates with the net result of atria‐wide accelerations during drifting rotors activity.
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Affiliation(s)
- Óscar Salvador-Montañés
- Center for Arrhythmia Research Department of Internal Medicine - Cardiology University of Michigan Ann Arbor MI.,Facultad de Medicina Universidad Francisco de Vitoria, Pozuelo de Alarcon Mardid Spain.,Hospital Universitario de Torrejón Mardid Spain
| | - Rafael J Ramirez
- Center for Arrhythmia Research Department of Internal Medicine - Cardiology University of Michigan Ann Arbor MI.,The Department of Physiology and Biophysics Virginia Commonwealth University Richmond VA
| | - Yoshio Takemoto
- Center for Arrhythmia Research Department of Internal Medicine - Cardiology University of Michigan Ann Arbor MI.,Cardiovascular Medicine Gifu Prefectural Tajimi Hospital Tajimi Japan
| | - Steven R Ennis
- Center for Arrhythmia Research Department of Internal Medicine - Cardiology University of Michigan Ann Arbor MI
| | - Daniel Garcia-Iglesias
- Center for Arrhythmia Research Department of Internal Medicine - Cardiology University of Michigan Ann Arbor MI.,Hospital Universitario Central de Asturias Oviedo Spain
| | - Sicong Wang
- Center for Arrhythmia Research Department of Internal Medicine - Cardiology University of Michigan Ann Arbor MI.,Institute for Stem Cell Biology and Regenerative Medicine Stanford University Palo Alto CA
| | - Patrick J Wolfer
- Center for Arrhythmia Research Department of Internal Medicine - Cardiology University of Michigan Ann Arbor MI.,Michigan Technological University Houghton MI
| | - Jiang Jiang
- Center for Arrhythmia Research Department of Internal Medicine - Cardiology University of Michigan Ann Arbor MI
| | - Sergey V Mironov
- Center for Arrhythmia Research Department of Internal Medicine - Cardiology University of Michigan Ann Arbor MI
| | - Sandeep V Pandit
- Center for Arrhythmia Research Department of Internal Medicine - Cardiology University of Michigan Ann Arbor MI
| | - José Jalife
- Center for Arrhythmia Research Department of Internal Medicine - Cardiology University of Michigan Ann Arbor MI.,Centro Nacional de Investigaciones Cardiovasculares Carlos III Madrid Spain
| | - Omer Berenfeld
- Center for Arrhythmia Research Department of Internal Medicine - Cardiology University of Michigan Ann Arbor MI
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Personalized Evaluation of Atrial Complexity of Patients Undergoing Atrial Fibrillation Ablation: A Clinical Computational Study. BIOLOGY 2021; 10:biology10090838. [PMID: 34571716 PMCID: PMC8469429 DOI: 10.3390/biology10090838] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Revised: 08/24/2021] [Accepted: 08/25/2021] [Indexed: 11/17/2022]
Abstract
Simple Summary Atrial fibrillation is a type of arrhythmia that occurs when the electrical activity of the heart in the atrium is not coordinated, and its consequences can be lethal. The driving source that initiates this chaotic activity can be located anywhere in the atrium, but most frequently appears in certain areas such as the pulmonary veins. In this study, we developed a new estimation method to evaluate possible source location and complexity of the arrhythmia using computer simulations. This method represents mathematical descriptions of natural processes that can be used to mimic a real scenario, including specific information such as the atrial anatomy. Here, we identified a specific biomarker the enabled obtaining a foci distribution map and found that elimination of pulmonary vein drivers was associated with a successful long-term ablation outcome. This study could, therefore, help to identify and characterize patients in order to better plan the ablation procedure. Abstract Current clinical guidelines establish Pulmonary Vein (PV) isolation as the indicated treatment for Atrial Fibrillation (AF). However, AF can also be triggered or sustained due to atrial drivers located elsewhere in the atria. We designed a new simulation workflow based on personalized computer simulations to characterize AF complexity of patients undergoing PV ablation, validated with non-invasive electrocardiographic imaging and evaluated at one year after ablation. We included 30 patients using atrial anatomies segmented from MRI and simulated an automata model for the electrical modelling, consisting of three states (resting, excited and refractory). In total, 100 different scenarios were simulated per anatomy varying rotor number and location. The 3 states were calibrated with Koivumaki action potential, entropy maps were obtained from the electrograms and compared with ECGi for each patient to analyze PV isolation outcome. The completion of the workflow indicated that successful AF ablation occurred in patients with rotors mainly located at the PV antrum, while unsuccessful procedures presented greater number of driving sites outside the PV area. The number of rotors attached to the PV was significantly higher in patients with favorable long-term ablation outcome (1-year freedom from AF: 1.61 ± 0.21 vs. AF recurrence: 1.40 ± 0.20; p-value = 0.018). The presented workflow could improve patient stratification for PV ablation by screening the complexity of the atria.
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Kulikov AA, Sapelnikov OV, Uskach TM, Cherkashin DI, Grishin IR, Akchurin RS. Rotor Drivers in Induction and Maintenance of Atrial Fibrillation. RATIONAL PHARMACOTHERAPY IN CARDIOLOGY 2021. [DOI: 10.20996/1819-6446-2021-04-16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Atrial fibrillation is the most common arrhythmia in clinical practice. It is associated with an increased risk of stroke, chronic heart failure, and sudden cardiac death. Our options of restoring and maintaining sinus rhythm have a very limited effect, both in the case of antiarrhythmic and catheter treatment. Catheter ablation has proven to be a more effective approach than antiarrhythmic therapy. The success rate of the procedure reaches 70%. However, radiofrequency ablation is associated with a risk of complications, with 4.5% of patients likely to develop major complications, including tamponade (1.31%), femoral pseudoaneurysm (0.71%), and death (0.15%). Given the generally recognized dominant role of the pulmonary veins in the induction of atrial fibrillation, their electrical isolation has become the recommended tactic of the catheter approach. In the case of patients with paroxysmal form of atrial fibrillation, the success rate of the procedure reaches 87%. Unfortunately, in the case of persistent forms of atrial fibrillation, the effectiveness of the primary procedure decreases to 28% and reaches 51% with repeated interventions. In addition to the anatomically oriented isolation of the pulmonary veins, a number of strategies have been proposed to reach the secondary zones of atrial fibrillation induction. The results of recent studies on the effectiveness of strategies for ablation of rotor regions and their role in the induction and maintenance of AF may lead to the further development of catheter ablation techniques and an individual radiofrequency ablation approach in a particular patient.
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6
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Quah JX, Dharmaprani D, Tiver K, Lahiri A, Hecker T, Perry R, Selvanayagam JB, Joseph MX, McGavigan A, Ganesan A. Atrial fibrosis and substrate based characterization in atrial fibrillation: Time to move forwards. J Cardiovasc Electrophysiol 2021; 32:1147-1160. [PMID: 33682258 DOI: 10.1111/jce.14987] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2020] [Revised: 02/15/2021] [Accepted: 02/22/2021] [Indexed: 12/15/2022]
Abstract
Atrial fibrillation (AF) is the most commonly encountered cardiac arrhythmia in clinical practice. However, current therapeutic interventions for atrial fibrillation have limited clinical efficacy as a consequence of major knowledge gaps in the mechanisms sustaining atrial fibrillation. From a mechanistic perspective, there is increasing evidence that atrial fibrosis plays a central role in the maintenance and perpetuation of atrial fibrillation. Electrophysiologically, atrial fibrosis results in alterations in conduction velocity, cellular refractoriness, and produces conduction block promoting meandering, unstable wavelets and micro-reentrant circuits. Clinically, atrial fibrosis has also linked to poor clinical outcomes including AF-related thromboembolic complications and arrhythmia recurrences post catheter ablation. In this article, we review the pathophysiology behind the formation of fibrosis as AF progresses, the role of fibrosis in arrhythmogenesis, surrogate markers for detection of fibrosis using cardiac magnetic resonance imaging, echocardiography and electroanatomic mapping, along with their respective limitations. We then proceed to review the current evidence behind therapeutic interventions targeting atrial fibrosis, including drugs and substrate-based catheter ablation therapies followed by the potential future use of electro phenotyping for AF characterization to overcome the limitations of contemporary substrate-based methodologies.
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Affiliation(s)
- Jing X Quah
- College of Medicine and Public Health, Flinders University of South Australia, Adelaide, Australia.,Department of Cardiovascular Medicine, Flinders Medical Centre, Adelaide, Australia
| | - Dhani Dharmaprani
- College of Medicine and Public Health, Flinders University of South Australia, Adelaide, Australia.,College of Science and Engineering, Flinders University of South Australia, Adelaide, Australia
| | - Kathryn Tiver
- Department of Cardiovascular Medicine, Flinders Medical Centre, Adelaide, Australia
| | - Anandaroop Lahiri
- Department of Cardiovascular Medicine, Flinders Medical Centre, Adelaide, Australia
| | - Teresa Hecker
- Department of Cardiovascular Medicine, Flinders Medical Centre, Adelaide, Australia
| | - Rebecca Perry
- Department of Cardiovascular Medicine, Flinders Medical Centre, Adelaide, Australia.,UniSA Allied Health and Human Performance, University of South Australia, Adelaide, Australia
| | | | - Majo X Joseph
- Department of Cardiovascular Medicine, Flinders Medical Centre, Adelaide, Australia
| | | | - Anand Ganesan
- College of Medicine and Public Health, Flinders University of South Australia, Adelaide, Australia.,Department of Cardiovascular Medicine, Flinders Medical Centre, Adelaide, Australia
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Filos D, Tachmatzidis D, Maglaveras N, Vassilikos V, Chouvarda I. Understanding the Beat-to-Beat Variations of P-Waves Morphologies in AF Patients During Sinus Rhythm: A Scoping Review of the Atrial Simulation Studies. Front Physiol 2019; 10:742. [PMID: 31275161 PMCID: PMC6591370 DOI: 10.3389/fphys.2019.00742] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 05/28/2019] [Indexed: 11/13/2022] Open
Abstract
The remarkable advances in high-performance computing and the resulting increase of the computational power have the potential to leverage computational cardiology toward improving our understanding of the pathophysiological mechanisms of arrhythmias, such as Atrial Fibrillation (AF). In AF, a complex interaction between various triggers and the atrial substrate is considered to be the leading cause of AF initiation and perpetuation. In electrocardiography (ECG), P-wave is supposed to reflect atrial depolarization. It has been found that even during sinus rhythm (SR), multiple P-wave morphologies are present in AF patients with a history of AF, suggesting a higher dispersion of the conduction route in this population. In this scoping review, we focused on the mechanisms which modify the electrical substrate of the atria in AF patients, while investigating the existence of computational models that simulate the propagation of the electrical signal through different routes. The adopted review methodology is based on a structured analytical framework which includes the extraction of the keywords based on an initial limited bibliographic search, the extensive literature search and finally the identification of relevant articles based on the reference list of the studies. The leading mechanisms identified were classified according to their scale, spanning from mechanisms in the cell, tissue or organ level, and the produced outputs. The computational modeling approaches for each of the factors that influence the initiation and the perpetuation of AF are presented here to provide a clear overview of the existing literature. Several levels of categorization were adopted while the studies which aim to translate their findings to ECG phenotyping are highlighted. The results denote the availability of multiple models, which are appropriate under specific conditions. However, the consideration of complex scenarios taking into account multiple spatiotemporal scales, personalization of electrophysiological and anatomical models and the reproducibility in terms of ECG phenotyping has only partially been tackled so far.
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Affiliation(s)
- Dimitrios Filos
- Lab of Computing, Medical Informatics and Biomedical Imaging Technologies, School of Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | | | - Nicos Maglaveras
- Lab of Computing, Medical Informatics and Biomedical Imaging Technologies, School of Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece
- Department of Industrial Engineering and Management Sciences, Northwestern University, Evanston, IL, United States
| | - Vassilios Vassilikos
- 3rd Cardiology Department, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Ioanna Chouvarda
- Lab of Computing, Medical Informatics and Biomedical Imaging Technologies, School of Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece
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Williams SE, Harrison JL, Chubb H, Whitaker J, Kiedrowicz R, Rinaldi CA, Cooklin M, Wright M, Niederer S, O'Neill MD. Local activation time sampling density for atrial tachycardia contact mapping: how much is enough? Europace 2018; 20:e11-e20. [PMID: 28379525 PMCID: PMC5834039 DOI: 10.1093/europace/eux037] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Accepted: 02/12/2017] [Indexed: 11/25/2022] Open
Abstract
Aims Local activation time (LAT) mapping forms the cornerstone of atrial tachycardia diagnosis. Although anatomic and positional accuracy of electroanatomic mapping (EAM) systems have been validated, the effect of electrode sampling density on LAT map reconstruction is not known. Here, we study the effect of chamber geometry and activation complexity on optimal LAT sampling density using a combined in silico and in vivo approach. Methods and results In vivo 21 atrial tachycardia maps were studied in three groups: (1) focal activation, (2) macro-re-entry, and (3) localized re-entry. In silico activation was simulated on a 4×4cm atrial monolayer, sampled randomly at 0.25–10 points/cm2 and used to re-interpolate LAT maps. Activation patterns were studied in the geometrically simple porcine right atrium (RA) and complex human left atrium (LA). Activation complexity was introduced into the porcine RA by incomplete inter-caval linear ablation. In all cases, optimal sampling density was defined as the highest density resulting in minimal further error reduction in the re-interpolated maps. Optimal sampling densities for LA tachycardias were 0.67 ± 0.17 points/cm2 (focal activation), 1.05 ± 0.32 points/cm2 (macro-re-entry) and 1.23 ± 0.26 points/cm2 (localized re-entry), P = 0.0031. Increasing activation complexity was associated with increased optimal sampling density both in silico (focal activation 1.09 ± 0.14 points/cm2; re-entry 1.44 ± 0.49 points/cm2; spiral-wave 1.50 ± 0.34 points/cm2, P < 0.0001) and in vivo (porcine RA pre-ablation 0.45 ± 0.13 vs. post-ablation 0.78 ± 0.17 points/cm2, P = 0.0008). Increasing chamber geometry was also associated with increased optimal sampling density (0.61 ± 0.22 points/cm2 vs. 1.0 ± 0.34 points/cm2, P = 0.0015). Conclusion Optimal sampling densities can be identified to maximize diagnostic yield of LAT maps. Greater sampling density is required to correctly reveal complex activation and represent activation across complex geometries. Overall, the optimal sampling density for LAT map interpolation defined in this study was ∼1.0–1.5 points/cm2.
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Affiliation(s)
- Steven E Williams
- Division of Imaging Sciences and Biomedical Engineering, King's College London, 4th Floor North Wing, St Thomas' Hospital, 249 Westminster Bridge Road, SE1 7EH London
| | - James L Harrison
- Division of Imaging Sciences and Biomedical Engineering, King's College London, 4th Floor North Wing, St Thomas' Hospital, 249 Westminster Bridge Road, SE1 7EH London
| | - Henry Chubb
- Division of Imaging Sciences and Biomedical Engineering, King's College London, 4th Floor North Wing, St Thomas' Hospital, 249 Westminster Bridge Road, SE1 7EH London
| | - John Whitaker
- Division of Imaging Sciences and Biomedical Engineering, King's College London, 4th Floor North Wing, St Thomas' Hospital, 249 Westminster Bridge Road, SE1 7EH London
| | - Radek Kiedrowicz
- Department of Cardiology, Guy's and St Thomas' NHS Foundation Trust, St Thomas' Hospital, 249 Westminster Bridge Road, SE1 7EH London, UK
| | - Christopher A Rinaldi
- Department of Cardiology, Guy's and St Thomas' NHS Foundation Trust, St Thomas' Hospital, 249 Westminster Bridge Road, SE1 7EH London, UK
| | - Michael Cooklin
- Department of Cardiology, Guy's and St Thomas' NHS Foundation Trust, St Thomas' Hospital, 249 Westminster Bridge Road, SE1 7EH London, UK
| | - Matthew Wright
- Division of Imaging Sciences and Biomedical Engineering, King's College London, 4th Floor North Wing, St Thomas' Hospital, 249 Westminster Bridge Road, SE1 7EH London
| | - Steven Niederer
- Division of Imaging Sciences and Biomedical Engineering, King's College London, 4th Floor North Wing, St Thomas' Hospital, 249 Westminster Bridge Road, SE1 7EH London
| | - Mark D O'Neill
- Division of Imaging Sciences and Biomedical Engineering, King's College London, 4th Floor North Wing, St Thomas' Hospital, 249 Westminster Bridge Road, SE1 7EH London
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9
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Song JS, Kim J, Lim B, Lee YS, Hwang M, Joung B, Shim EB, Pak HN. Pro-Arrhythmogenic Effects of Heterogeneous Tissue Curvature - A Suggestion for Role of Left Atrial Appendage in Atrial Fibrillation. Circ J 2018; 83:32-40. [PMID: 30429429 DOI: 10.1253/circj.cj-18-0615] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND The arrhythmogenic role of complex atrial morphology has not yet been clearly elucidated. We hypothesized that bumpy tissue geometry can induce action potential duration (APD) dispersion and wavebreak in atrial fibrillation (AF). Methods and Results: We simulated a 2D-bumpy atrial model by varying the degree of bumpiness, and 3D-left atrial (LA) models integrated by LA computed tomographic (CT) images taken from 14 patients with persistent AF. We also analyzed wave-dynamic parameters with bipolar electrograms during AF and compared them with LA-CT geometry in 30 patients with persistent AF. In the 2D-bumpy model, APD dispersion increased (P<0.001) and wavebreak occurred spontaneously when the surface bumpiness was greater, showing phase transition-like behavior (P<0.001). The bumpiness gradient 2D-model showed that spiral wave drifted in the direction of higher bumpiness, and phase singularity (PS) points were mostly located in areas with higher bumpiness. In the 3D-LA model, PS density was higher in the LA appendage (LAA) compared with other parts of the LA (P<0.05). In 30 persistent-AF patients, the surface bumpiness of LAA was 5.8-fold that of other LA parts (P<0.001), and exceeded critical bumpiness to induce wavebreak. Wave dynamics complexity parameters were consistently dominant in the LAA (P<0.001). CONCLUSIONS Bumpy tissue geometry promoted APD dispersion, wavebreak, and spiral wave drift in in-silico human atrial tissue, and corresponded to clinical electroanatomical maps.
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10
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Saha M, Roney CH, Bayer JD, Meo M, Cochet H, Dubois R, Vigmond EJ. Wavelength and Fibrosis Affect Phase Singularity Locations During Atrial Fibrillation. Front Physiol 2018; 9:1207. [PMID: 30246796 PMCID: PMC6139329 DOI: 10.3389/fphys.2018.01207] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 08/10/2018] [Indexed: 01/06/2023] Open
Abstract
The mechanisms underlying atrial fibrillation (AF), the most common sustained cardiac rhythm disturbance, remain elusive. Atrial fibrosis plays an important role in the development of AF and rotor dynamics. Both electrical wavelength (WL) and the degree of atrial fibrosis change as AF progresses. However, their combined effect on rotor core location remains unknown. The aim of this study was to analyze the effects of WL change on rotor core location in both fibrotic and non-fibrotic atria. Three patient specific fibrosis distributions (total fibrosis content: 16.6, 22.8, and 19.2%) obtained from clinical imaging data of persistent AF patients were incorporated in a bilayer atrial computational model. Fibrotic effects were modeled as myocyte-fibroblast coupling + conductivity remodeling; structural remodeling; ionic current changes + conductivity remodeling; and combinations of these methods. To change WL, action potential duration (APD) was varied from 120 to 240ms, representing the range of clinically observed AF cycle length, by modifying the inward rectifier potassium current (IK1) conductance between 80 and 140% of the original value. Phase singularities (PSs) were computed to identify rotor core locations. Our results show that IK1 conductance variation resulted in a decrease of APD and WL across the atria. For large WL in the absence of fibrosis, PSs anchored to regions with high APD gradient at the center of the left atrium (LA) anterior wall and near the junctions of the inferior pulmonary veins (PVs) with the LA. Decreasing the WL induced more PSs, whose distribution became less clustered. With fibrosis, PS locations depended on the fibrosis distribution and the fibrosis implementation method. The proportion of PSs in fibrotic areas and along the borders varied with both WL and fibrosis modeling method: for patient one, this was 4.2-14.9% as IK1 varied for the structural remodeling representation, but 12.3-88.4% using the combination of structural remodeling with myocyte-fibroblast coupling. The degree and distribution of fibrosis and the choice of implementation technique had a larger effect on PS locations than the WL variation. Thus, distinguishing the fibrotic mechanisms present in a patient is important for interpreting clinical fibrosis maps to create personalized models.
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Affiliation(s)
- Mirabeau Saha
- IMB, UMR 5251, University of Bordeaux, Pessac, France
- IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux University, Pessac, France
| | - Caroline H. Roney
- Department of Biomedical Engineering, King's College London, London, United Kingdom
| | - Jason D. Bayer
- IMB, UMR 5251, University of Bordeaux, Pessac, France
- IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux University, Pessac, France
| | - Marianna Meo
- IMB, UMR 5251, University of Bordeaux, Pessac, France
- IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux University, Pessac, France
| | - Hubert Cochet
- IMB, UMR 5251, University of Bordeaux, Pessac, France
- IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux University, Pessac, France
| | - Remi Dubois
- IMB, UMR 5251, University of Bordeaux, Pessac, France
- IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux University, Pessac, France
| | - Edward J. Vigmond
- IMB, UMR 5251, University of Bordeaux, Pessac, France
- IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux University, Pessac, France
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11
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Malki G, Zlochiver S. Cardiac spiral wave drifting due to spatial temperature gradients - A numerical study. Med Eng Phys 2018; 61:69-80. [PMID: 30201284 DOI: 10.1016/j.medengphy.2018.08.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Revised: 06/16/2018] [Accepted: 08/26/2018] [Indexed: 01/07/2023]
Abstract
Cardiac rotors are believed to be a major driver source of persistent atrial fibrillation (AF), and their spatiotemporal characterization is essential for successful ablation procedures. However, electrograms guided ablation have not been proven to have benefit over empirical ablation thus far, and there is a strong need of improving the localization of cardiac arrhythmogenic targets for ablation. A new approach for characterize rotors is proposed that is based on induced spatial temperature gradients (STGs), and investigated by theoretical study using numerical simulations. We hypothesize that such gradients will cause rotor drifting due to induced spatial heterogeneity in excitability, so that rotors could be driven towards the ablating probe. Numerical simulations were conducted in single cell and 2D atrial models using AF remodeled kinetics. STGs were applied either linearly on the entire tissue or as a small local perturbation, and the major ion channel rate constants were adjusted following Arrhenius equation. In the AF-remodeled single cell, recovery time increased exponentially with decreasing temperatures, despite the marginal effect of temperature on the action potential duration. In 2D models, spiral waves drifted with drifting velocity components affected by both temperature gradient direction and the spiral wave rotation direction. Overall, spiral waves drifted towards the colder tissue region associated with global minimum of excitability. A local perturbation with a temperature of T = 28 °C was found optimal for spiral wave attraction for the studied conditions. This work provides a preliminary proof-of-concept for a potential prospective technique for rotor attraction. We envision that the insights from this study will be utilize in the future in the design of a new methodology for AF characterization and termination during ablation procedures.
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Affiliation(s)
- Guy Malki
- Department of Biomedical Engineering, Faculty of Engineering, Tel-Aviv University, Ramat-Aviv, Tel-Aviv 69978, Israel
| | - Sharon Zlochiver
- Department of Biomedical Engineering, Faculty of Engineering, Tel-Aviv University, Ramat-Aviv, Tel-Aviv 69978, Israel.
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12
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Calvo D, Filgueiras-Rama D, Jalife J. Mechanisms and Drug Development in Atrial Fibrillation. Pharmacol Rev 2018; 70:505-525. [PMID: 29921647 PMCID: PMC6010660 DOI: 10.1124/pr.117.014183] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Atrial fibrillation is a highly prevalent cardiac arrhythmia and the most important cause of embolic stroke. Although genetic studies have identified an increasing assembly of AF-related genes, the impact of these genetic discoveries is yet to be realized. In addition, despite more than a century of research and speculation, the molecular and cellular mechanisms underlying AF have not been established, and therapy for AF, particularly persistent AF, remains suboptimal. Current antiarrhythmic drugs are associated with a significant rate of adverse events, particularly proarrhythmia, which may explain why many highly symptomatic AF patients are not receiving any rhythm control therapy. This review focuses on recent advances in AF research, including its epidemiology, genetics, and pathophysiological mechanisms. We then discuss the status of antiarrhythmic drug therapy for AF today, reviewing molecular mechanisms, and the possible clinical use of some of the new atrial-selective antifibrillatory agents, as well as drugs that target atrial remodeling, inflammation and fibrosis, which are being tested as upstream therapies to prevent AF perpetuation. Altogether, the objective is to highlight the magnitude and endemic dimension of AF, which requires a significant effort to develop new and effective antiarrhythmic drugs, but also improve AF prevention and treatment of risk factors that are associated with AF complications.
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Affiliation(s)
- David Calvo
- Department of Cardiology, Arrhythmia Unit, Hospital Universitario Central de Asturias and Instituto de Investigación Sanitaria del Principado de Asturias, Oviedo, Spain (D.C.); Fundación Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, Spain (D.F.-R., J.J.); Department of Cardiology, Arrhythmia Unit, Hospital Clínico Universitario San Carlos, Madrid, Spain (D.F.-R.); Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares (CIBERCV), Madrid, Spain (D.F.-R., J.J.); and Center for Arrhythmia Research, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan (J.J.)
| | - David Filgueiras-Rama
- Department of Cardiology, Arrhythmia Unit, Hospital Universitario Central de Asturias and Instituto de Investigación Sanitaria del Principado de Asturias, Oviedo, Spain (D.C.); Fundación Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, Spain (D.F.-R., J.J.); Department of Cardiology, Arrhythmia Unit, Hospital Clínico Universitario San Carlos, Madrid, Spain (D.F.-R.); Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares (CIBERCV), Madrid, Spain (D.F.-R., J.J.); and Center for Arrhythmia Research, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan (J.J.)
| | - José Jalife
- Department of Cardiology, Arrhythmia Unit, Hospital Universitario Central de Asturias and Instituto de Investigación Sanitaria del Principado de Asturias, Oviedo, Spain (D.C.); Fundación Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, Spain (D.F.-R., J.J.); Department of Cardiology, Arrhythmia Unit, Hospital Clínico Universitario San Carlos, Madrid, Spain (D.F.-R.); Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares (CIBERCV), Madrid, Spain (D.F.-R., J.J.); and Center for Arrhythmia Research, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan (J.J.)
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13
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Roney CH, Bayer JD, Cochet H, Meo M, Dubois R, Jaïs P, Vigmond EJ. Variability in pulmonary vein electrophysiology and fibrosis determines arrhythmia susceptibility and dynamics. PLoS Comput Biol 2018; 14:e1006166. [PMID: 29795549 PMCID: PMC5997352 DOI: 10.1371/journal.pcbi.1006166] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Revised: 06/12/2018] [Accepted: 04/30/2018] [Indexed: 11/28/2022] Open
Abstract
Success rates for catheter ablation of persistent atrial fibrillation patients are currently low; however, there is a subset of patients for whom electrical isolation of the pulmonary veins alone is a successful treatment strategy. It is difficult to identify these patients because there are a multitude of factors affecting arrhythmia susceptibility and maintenance, and the individual contributions of these factors are difficult to determine clinically. We hypothesised that the combination of pulmonary vein (PV) electrophysiology and atrial body fibrosis determine driver location and effectiveness of pulmonary vein isolation (PVI). We used bilayer biatrial computer models based on patient geometries to investigate the effects of PV properties and atrial fibrosis on arrhythmia inducibility, maintenance mechanisms, and the outcome of PVI. Short PV action potential duration (APD) increased arrhythmia susceptibility, while longer PV APD was found to be protective. Arrhythmia inducibility increased with slower conduction velocity (CV) at the LA/PV junction, but not for cases with homogeneous CV changes or slower CV at the distal PV. Phase singularity (PS) density in the PV region for cases with PV fibrosis was increased. Arrhythmia dynamics depend on both PV properties and fibrosis distribution, varying from meandering rotors to PV reentry (in cases with baseline or long APD), to stable rotors at regions of high fibrosis density. Measurement of fibrosis and PV properties may indicate patient specific susceptibility to AF initiation and maintenance. PV PS density before PVI was higher for cases in which AF terminated or converted to a macroreentry; thus, high PV PS density may indicate likelihood of PVI success. Atrial fibrillation is the most commonly encountered cardiac arrhythmia, affecting a significant portion of the population. Currently, ablation is the most effective treatment but success rates are less than optimal, being 70% one-year post-treatment. There is a large effort to find better ablation strategies to permanently cure the condition. Pulmonary vein isolation by ablation is more or less the standard of care, but many questions remain since pulmonary vein ectopy by itself does not explain all of the clinical successes or failures. We used computer simulations to investigate how electrophysiological properties of the pulmonary veins can affect rotor formation and maintenance in patients suffering from atrial fibrillation. We used complex, biophysical representations of cellular electrophysiology in highly detailed geometries constructed from patient scans. We heterogeneously varied electrophysiological and structural properties to see their effects on rotor initiation and maintenance. Our study suggests a metric for indicating the likelihood of success of pulmonary vein isolation. Thus either measuring this clinically, or running patient-specific simulations to estimate this metric may suggest whether ablation in addition to pulmonary vein isolation should be performed. Our study provides motivation for a retrospective clinical study or experimental study into this metric.
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Affiliation(s)
- Caroline H. Roney
- IHU Liryc, Electrophysiology and Heart Modeling Institute, foundation Bordeaux Université, F-33600 Pessac- Bordeaux, France
- Division of Imaging Sciences and Biomedical Engineering, King’s College London, London, United Kingdom
| | - Jason D. Bayer
- IHU Liryc, Electrophysiology and Heart Modeling Institute, foundation Bordeaux Université, F-33600 Pessac- Bordeaux, France
- Univ. Bordeaux, IMB UMR 5251, CNRS, F-33400 Talence, France
| | - Hubert Cochet
- IHU Liryc, Electrophysiology and Heart Modeling Institute, foundation Bordeaux Université, F-33600 Pessac- Bordeaux, France
- Hôpital Cardiologique du Haut-L’évêque, Université de Bordeaux, LIRYC Institute: IHU LIRYC ANR-10-IAHU-04 and Equipex MUSIC ANR-11-EQPX-0030, Bordeaux, France
| | - Marianna Meo
- IHU Liryc, Electrophysiology and Heart Modeling Institute, foundation Bordeaux Université, F-33600 Pessac- Bordeaux, France
| | - Rémi Dubois
- IHU Liryc, Electrophysiology and Heart Modeling Institute, foundation Bordeaux Université, F-33600 Pessac- Bordeaux, France
| | - Pierre Jaïs
- IHU Liryc, Electrophysiology and Heart Modeling Institute, foundation Bordeaux Université, F-33600 Pessac- Bordeaux, France
- Hôpital Cardiologique du Haut-L’évêque, Université de Bordeaux, LIRYC Institute: IHU LIRYC ANR-10-IAHU-04 and Equipex MUSIC ANR-11-EQPX-0030, Bordeaux, France
| | - Edward J. Vigmond
- IHU Liryc, Electrophysiology and Heart Modeling Institute, foundation Bordeaux Université, F-33600 Pessac- Bordeaux, France
- Univ. Bordeaux, IMB UMR 5251, CNRS, F-33400 Talence, France
- * E-mail:
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14
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Calvo D, Rubín J, Pérez D, Morís C. Ablation of Rotor Domains Effectively Modulates Dynamics of Human: Long-Standing Persistent Atrial Fibrillation. Circ Arrhythm Electrophysiol 2017; 10:CIRCEP.117.005740. [PMID: 29254947 DOI: 10.1161/circep.117.005740] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 11/03/2017] [Indexed: 12/21/2022]
Abstract
BACKGROUND In human long-standing persistent atrial fibrillation, rotors potentially explain atrial fibrillation maintenance, but their ablation remains controversial. We aimed to explore original phase/frequency mapping methods to locate rotors and track changes induced by their ablation. METHODS AND RESULTS Thirteen patients with long-standing persistent atrial fibrillation (duration, 12-72 months) underwent phase/frequency mapping (Hilbert/Fourier transforms; CARTO-Finder) of the left and right atria (PentaRay catheter). A rotor domain was defined as an area displaying at least 3 consecutive rotations. Ablation was performed by circumferential pulmonary vein isolation plus linear ablation of extrapulmonary rotor domains. We identified 19 rotor domains in 10 patients (1.8±1.1 per patient; 7 in the right atrium versus 12 in the left atrium; 15 extrapulmonary). Overall, rotor domains (9.2±2.2 rotations) displayed higher frequency of activation (6.41 Hz; 95% confidence interval, 6.24-6.57) than nonrotor domains (6.17 Hz; 95% confidence interval, 6.1-6.23; P=0.021), with interatrial frequency gradients established by the spatial location of the rotor domain (P=0.016). Fibrillatory conduction was suggested as a decrease in the frequency of the slower atria after ablation close to main interatrial conduction fascicles (P=0.035). Ablation of rotor domains (ablation line, 3.5±0.9 cm) effectively decreased the frequency of activation in both ipsilateral and contralateral atria (P<0.05 for both), whereas ablation of nonrotor domains did not. Acute conversion to sinus rhythm was observed in 2 patients after ablation of rotor domains. At 1-year follow-up, 70% remained in sinus rhythm (85% out-of-antiarrhythmic drugs). CONCLUSIONS Rotor domains appropriately explain long-standing persistent atrial fibrillation physiology at its frequency content. Their ablation effectively modifies dynamics on restricted ablation.
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Affiliation(s)
- David Calvo
- From the Department of Cardiology, Arrhythmia Unit, Hospital Universitario Central de Asturias, Oviedo, Spain; and Instituto de Investigación Sanitaria del Principado de Asturias, Oviedo, Spain.
| | - José Rubín
- From the Department of Cardiology, Arrhythmia Unit, Hospital Universitario Central de Asturias, Oviedo, Spain; and Instituto de Investigación Sanitaria del Principado de Asturias, Oviedo, Spain
| | - Diego Pérez
- From the Department of Cardiology, Arrhythmia Unit, Hospital Universitario Central de Asturias, Oviedo, Spain; and Instituto de Investigación Sanitaria del Principado de Asturias, Oviedo, Spain
| | - César Morís
- From the Department of Cardiology, Arrhythmia Unit, Hospital Universitario Central de Asturias, Oviedo, Spain; and Instituto de Investigación Sanitaria del Principado de Asturias, Oviedo, Spain
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15
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Green HD, Thomas G, Terry JR. Signal Reconstruction of Pulmonary Vein Recordings Using a Phenomenological Mathematical Model: Application to Pulmonary Vein Isolation Therapy. Front Physiol 2017; 8:496. [PMID: 28769816 PMCID: PMC5511835 DOI: 10.3389/fphys.2017.00496] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 06/28/2017] [Indexed: 12/19/2022] Open
Abstract
Atrial fibrillation (AF), the most prevalent cardiac arrhythmia, is commonly initiated by ectopic beats originating from a small myocardial sleeve extending over the pulmonary veins. Pulmonary vein isolation therapy attempts to isolate the pulmonary veins from the left atrium by ablating tissue, commonly by using radiofrequency ablation. During this procedure, the cardiologist records electrical activity using a lasso catheter, and the activation pattern recorded is used as a guide toward which regions to ablate. However, poor contact between electrode and tissue can lead to important regions of electrical activity not being recorded in clinic. We reproduce these signals through the use of a phenomenological model of the cardiac action potential on a cylinder, which we fit to post-AF atrial cells, and model the bipolar electrodes of the lasso catheter by an approximation of the surface potential. The resulting activation pattern is validated by direct comparison with those of clinical recordings. A potential application of the model is to reconstruct the missing electrical activity, minimizing the impact of the information loss on the clinical procedure, and we present results to demonstrate this.
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Affiliation(s)
- Harry D Green
- College of Engineering, Mathematics and Physical Sciences, University of ExeterExeter, United Kingdom.,Wellcome Trust Centre for Biomedical Modelling and Analysis, University of ExeterExeter, United Kingdom.,Living Systems Institute, University of ExeterExeter, United Kingdom
| | - Glyn Thomas
- Bristol Heart InstituteBristol, United Kingdom
| | - John R Terry
- College of Engineering, Mathematics and Physical Sciences, University of ExeterExeter, United Kingdom.,Wellcome Trust Centre for Biomedical Modelling and Analysis, University of ExeterExeter, United Kingdom.,Living Systems Institute, University of ExeterExeter, United Kingdom.,EPSRC Centre for Predictive Modelling in Healthcare, University of ExeterExeter, United Kingdom
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16
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Atrial arrhythmogenicity of KCNJ2 mutations in short QT syndrome: Insights from virtual human atria. PLoS Comput Biol 2017; 13:e1005593. [PMID: 28609477 PMCID: PMC5487071 DOI: 10.1371/journal.pcbi.1005593] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Revised: 06/27/2017] [Accepted: 05/25/2017] [Indexed: 12/17/2022] Open
Abstract
Gain-of-function mutations in KCNJ2-encoded Kir2.1 channels underlie variant 3 (SQT3) of the short QT syndrome, which is associated with atrial fibrillation (AF). Using biophysically-detailed human atria computer models, this study investigated the mechanistic link between SQT3 mutations and atrial arrhythmogenesis, and potential ion channel targets for treatment of SQT3. A contemporary model of the human atrial action potential (AP) was modified to recapitulate functional changes in IK1 due to heterozygous and homozygous forms of the D172N and E299V Kir2.1 mutations. Wild-type (WT) and mutant formulations were incorporated into multi-scale homogeneous and heterogeneous tissue models. Effects of mutations on AP duration (APD), conduction velocity (CV), effective refractory period (ERP), tissue excitation threshold and their rate-dependence, as well as the wavelength of re-entry (WL) were quantified. The D172N and E299V Kir2.1 mutations produced distinct effects on IK1 and APD shortening. Both mutations decreased WL for re-entry through a reduction in ERP and CV. Stability of re-entrant excitation waves in 2D and 3D tissue models was mediated by changes to tissue excitability and dispersion of APD in mutation conditions. Combined block of IK1 and IKr was effective in terminating re-entry associated with heterozygous D172N conditions, whereas IKr block alone may be a safer alternative for the E299V mutation. Combined inhibition of IKr and IKur produced a synergistic anti-arrhythmic effect in both forms of SQT3. In conclusion, this study provides mechanistic insights into atrial proarrhythmia with SQT3 Kir2.1 mutations and highlights possible pharmacological strategies for management of SQT3-linked AF. Atrial fibrillation (AF) is the most common cardiac arrhythmia, and is characterised by complex and irregular electrical activation of the upper chambers of the heart. One rare, genetic condition associated with increased risk of AF is the short QT syndrome (SQTS), which is caused by mutations in genes involved in normal electrical function of the heart. Underlying mechanisms by which SQTS-related gene mutations facilitate development of arrhythmias in the human atria are not well understood. In this study, sophisticated computer models representing ‘virtual’ human atria, incorporating detailed electrophysiological data at the ‘ion channel’ protein level into both idealised and realistic multi-scale tissue geometries, were used to dissect mechanisms by which two mutations in the KCNJ2 gene responsible for SQTS variant 3 (SQT3) promote initiation and sustenance of arrhythmias. It was found that the D172N and E299V mutations to KCNJ2 accelerated the repolarisation process at the cellular level through distinct mechanisms. This, along with the way the mutations affected heterogeneity in electrical behaviour at the organ level, mediated stability of arrhythmias and response to simulated ion channel block. This study improves understanding of mechanisms underlying increased AF risk associated with D172N and E299V KCNJ2 mutations, and outlines potential therapeutic strategies.
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17
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Barajas-Martinez H, Goodrow RJ, Hu D, Patel P, Desai M, Panama BK, Treat JA, Aistrup GL, Cordeiro JM. Biophysical and molecular comparison of sodium current in cells isolated from canine atria and pulmonary vein. Pflugers Arch 2017; 469:703-712. [PMID: 28243733 DOI: 10.1007/s00424-017-1956-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 02/08/2017] [Accepted: 02/10/2017] [Indexed: 11/25/2022]
Abstract
The collar of the pulmonary vein (PV) is the focal point for the initiation of atrial arrhythmias, but the mechanisms underlying how PV cells differ from neighboring left atrial tissue are unclear. We examined the biophysical and molecular properties of INa in cells isolated from the canine pulmonary sleeve and compared the properties to left atrial tissue. PV and left atrial myocytes were isolated and patch clamp techniques were used to record INa. Action potential recordings from either tissue type were made using high-resistance electrodes. mRNA was determined using quantitative RT-PCR and proteins were determined by Western blot. Analysis of the action potential characteristics showed that PV tissue had a lower Vmax compared with left atrial tissue. Fast INa showed that current density was slightly lower in PV cells compared with LA cells (-96 ± 18.7 pA/pF vs. -120 ± 6.7 pA/pF, respectively, p < 0.05). The recovery from inactivation of INa in PV cells was slightly slower but no marked difference in steady-state inactivation was noted. Analysis of late INa during a 225-ms pulse showed that late INa was significantly smaller in PV cells compared to LA cells at all measured time points into the pulse. These results suggest PV cells have lower density of both peak and late INa. Molecular analysis of Nav1.5 and the four beta subunits showed lower levels of Nav1.5 as well as Navβ1 subunits, confirming the biophysical findings. These data show that a lower density of INa may lead to depression of excitability and predispose the PV collar to re-entrant circuits under pathophysiological conditions.
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Affiliation(s)
- Hector Barajas-Martinez
- Department of Experimental Cardiology, Masonic Medical Research Laboratory, 2150 Bleecker Street, Utica, NY, 13501, USA
| | - Robert J Goodrow
- Department of Experimental Cardiology, Masonic Medical Research Laboratory, 2150 Bleecker Street, Utica, NY, 13501, USA
| | - Dan Hu
- Department of Experimental Cardiology, Masonic Medical Research Laboratory, 2150 Bleecker Street, Utica, NY, 13501, USA
| | - Payal Patel
- Department of Experimental Cardiology, Masonic Medical Research Laboratory, 2150 Bleecker Street, Utica, NY, 13501, USA
| | - Mayurika Desai
- Department of Experimental Cardiology, Masonic Medical Research Laboratory, 2150 Bleecker Street, Utica, NY, 13501, USA
| | - Brian K Panama
- Department of Experimental Cardiology, Masonic Medical Research Laboratory, 2150 Bleecker Street, Utica, NY, 13501, USA
| | - Jacqueline A Treat
- Department of Experimental Cardiology, Masonic Medical Research Laboratory, 2150 Bleecker Street, Utica, NY, 13501, USA
| | - Gary L Aistrup
- Department of Experimental Cardiology, Masonic Medical Research Laboratory, 2150 Bleecker Street, Utica, NY, 13501, USA
| | - Jonathan M Cordeiro
- Department of Experimental Cardiology, Masonic Medical Research Laboratory, 2150 Bleecker Street, Utica, NY, 13501, USA.
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18
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Berenfeld O, Jalife J. Mechanisms of Atrial Fibrillation: Rotors, Ionic Determinants, and Excitation Frequency. Heart Fail Clin 2017; 12:167-78. [PMID: 26968663 DOI: 10.1016/j.hfc.2015.08.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Atrial fibrillation (AF) is the most common cardiac arrhythmia; however, therapy is suboptimal. We review recent data on dynamics of wave propagation during AF and its mechanistic link to the substrate. Data show that the dominant frequency (DF) increase during transition to persistent AF may be explained by rotor acceleration. We discuss how translation of experimentally derived understanding of the rotors may find its way into the clinic, focusing on studies analyzing spatial distribution of DF in the atria of patients with paroxysmal versus persistent AF, and how that knowledge might contribute to improve the outcome of AF ablation procedures.
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Affiliation(s)
- Omer Berenfeld
- Center for Arrhythmia Research, University of Michigan, 2800 Plymouth Road, Ann Arbor, MI 48109, USA.
| | - José Jalife
- Center for Arrhythmia Research, University of Michigan, 2800 Plymouth Road, Ann Arbor, MI 48109, USA
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19
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Berenfeld O. The Major Role of IK1 in Mechanisms of Rotor Drift in the Atria: A Computational Study. CLINICAL MEDICINE INSIGHTS-CARDIOLOGY 2016; 10:71-79. [PMID: 28096699 PMCID: PMC5175588 DOI: 10.4137/cmc.s39773] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Revised: 11/17/2016] [Accepted: 11/20/2016] [Indexed: 12/19/2022]
Abstract
Maintenance of paroxysmal atrial fibrillation (AF) by fast rotors in the left atrium (LA) or at the pulmonary veins (PVs) is not fully understood. This review describes the role of the heterogeneous distribution of transmembrane currents in the PVs and LA junction (PV-LAJ) in the localization of rotors in the PVs. Experimentally observed heterogeneities in IK1, IKs, IKr, Ito, and ICaL in the PV-LAJ were incorporated into models of human atrial kinetics to simulate various conditions and investigate rotor drifting mechanisms. Spatial gradients in the currents resulted in shorter action potential duration, less negative minimum diastolic potential, slower upstroke and conduction velocity for rotors in the PV region than in the LA. Rotors under such conditions drifted toward the PV and stabilized at the less excitable region. Our simulations suggest that IK1 heterogeneity is dominant in determining the drift direction through its impact on the excitability gradient. These results provide a novel framework for understanding the complex dynamics of rotors in AF.
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Affiliation(s)
- Omer Berenfeld
- Center for Arrhythmia Research, Internal Medicine and Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA
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20
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Termination of atrial spiral waves by traction into peripheral non 1:1 conducting regions - A numerical study. Med Eng Phys 2016; 38:1322-1329. [PMID: 27614722 DOI: 10.1016/j.medengphy.2016.08.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Revised: 07/20/2016] [Accepted: 08/28/2016] [Indexed: 11/22/2022]
Abstract
Atrial ablation has been recently utilized to treat atrial fibrillation (AF) by isolation or destruction of arrhythmia drivers. In chronic or persistent AF patients these drivers often consist of one or few rotors at unknown locations, and several ablations are commonly conducted before arrhythmia is terminated. However, the irreversible damage done to the tissue may lead to AF recurrence. We propose an alternative strategy to terminate rotor activity by its attraction into a non 1:1 conducting region. The feasibility of the method was numerically tested in 2D models of chronic AF human atrial tissue. Left-to-right gradients of either acetylcholine (ACh) or potassium conductance were employed to generate regions of 1:1 and non 1:1 conduction, characterized by their dominant frequency (DF) ratios. Spiral waves were established in the 1:1 conducting region and raster scanning was employed using a stimulating probe to attract the spiral wave tip. The probe was then linearly moved towards the boundary between the two regions. Successful attraction of spiral waves to the probe was demonstrated when the probe was <8mm from the spiral wave tip. Maximal traction velocity without loss of anchoring increased in a non-linear way with increasing values of ACh. Success rate of spiral wave termination was over 90% for regional DF ratios of as low as 1:1.2. Given that normally much higher ratios are measured in physiological atrial tissues, we envision this technique to provide a feasible, safer alternative to ablation procedures performed in persistent AF patients.
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21
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Grandi E, Maleckar MM. Anti-arrhythmic strategies for atrial fibrillation: The role of computational modeling in discovery, development, and optimization. Pharmacol Ther 2016; 168:126-142. [PMID: 27612549 DOI: 10.1016/j.pharmthera.2016.09.012] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Atrial fibrillation (AF), the most common cardiac arrhythmia, is associated with increased risk of cerebrovascular stroke, and with several other pathologies, including heart failure. Current therapies for AF are targeted at reducing risk of stroke (anticoagulation) and tachycardia-induced cardiomyopathy (rate or rhythm control). Rate control, typically achieved by atrioventricular nodal blocking drugs, is often insufficient to alleviate symptoms. Rhythm control approaches include antiarrhythmic drugs, electrical cardioversion, and ablation strategies. Here, we offer several examples of how computational modeling can provide a quantitative framework for integrating multiscale data to: (a) gain insight into multiscale mechanisms of AF; (b) identify and test pharmacological and electrical therapy and interventions; and (c) support clinical decisions. We review how modeling approaches have evolved and contributed to the research pipeline and preclinical development and discuss future directions and challenges in the field.
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Affiliation(s)
- Eleonora Grandi
- Department of Pharmacology, University of California Davis, Davis, USA.
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22
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Guillem MS, Climent AM, Rodrigo M, Fernández-Avilés F, Atienza F, Berenfeld O. Presence and stability of rotors in atrial fibrillation: evidence and therapeutic implications. Cardiovasc Res 2016; 109:480-92. [PMID: 26786157 PMCID: PMC4777913 DOI: 10.1093/cvr/cvw011] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2015] [Revised: 12/30/2015] [Accepted: 01/15/2016] [Indexed: 01/08/2023] Open
Abstract
Rotor-guided ablation has opened new perspectives into the therapy of atrial fibrillation (AF). Analysis of the spatio-temporal cardiac excitation patterns in the frequency and phase domains has demonstrated the importance of rotors in research models of AF, however, the dynamics and role of rotors in human AF are still controversial. In this review, the current knowledge gained through research models and patient data that support the notion that rotors are key players in AF maintenance is summarized. We report and discuss discrepancies regarding rotor prevalence and stability in various studies, which can be attributed in part to methodological differences among mapping systems. Future research for validation and improvement of current clinical electrophysiology mapping technologies will be crucial for developing mechanistic-based selection and application of the best therapeutic strategy for individual AF patient, being it, pharmaceutical, ablative, or other approach.
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Affiliation(s)
- María S Guillem
- ITACA, Universitat Politèscnica de València, Valencia, Spain
| | - Andreu M Climent
- Hospital General Universitario Gregorio Marañón, Madrid, Spain Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain
| | - Miguel Rodrigo
- ITACA, Universitat Politèscnica de València, Valencia, Spain
| | - Francisco Fernández-Avilés
- Hospital General Universitario Gregorio Marañón, Madrid, Spain Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain Facultad de Medicina, Universidad Complutense de Madrid, Spain
| | - Felipe Atienza
- Hospital General Universitario Gregorio Marañón, Madrid, Spain Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain Facultad de Medicina, Universidad Complutense de Madrid, Spain
| | - Omer Berenfeld
- Center for Arrhythmia Research, University of Michigan, 2800 Plymouth Road, Ann Arbor, MI 48109, USA
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Abstract
Atrial fibrillation (AF) is the most common sustained cardiac rhythm disorder, and increases in prevalence with increasing age and the number of cardiovascular comorbidities. AF is characterized by a rapid and irregular heartbeat that can be asymptomatic or lead to symptoms such as palpitations, dyspnoea and dizziness. The condition can also be associated with serious complications, including an increased risk of stroke. Important recent developments in the clinical epidemiology and management of AF have informed our approach to this arrhythmia. This Primer provides a comprehensive overview of AF, including its epidemiology, mechanisms and pathophysiology, diagnosis, screening, prevention and management. Management strategies, including stroke prevention, rate control and rhythm control, are considered. We also address quality of life issues and provide an outlook on future developments and ongoing clinical trials in managing this common arrhythmia.
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Hwang M, Song JS, Lee YS, Li C, Shim EB, Pak HN. Electrophysiological Rotor Ablation in In-Silico Modeling of Atrial Fibrillation: Comparisons with Dominant Frequency, Shannon Entropy, and Phase Singularity. PLoS One 2016; 11:e0149695. [PMID: 26909492 PMCID: PMC4766081 DOI: 10.1371/journal.pone.0149695] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 02/02/2016] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Although rotors have been considered among the drivers of atrial fibrillation (AF), the rotor definition is inconsistent. We evaluated the nature of rotors in 2D and 3D in- silico models of persistent AF (PeAF) by analyzing phase singularity (PS), dominant frequency (DF), Shannon entropy (ShEn), and complex fractionated atrial electrogram cycle length (CFAE-CL) and their ablation. METHODS Mother rotor was spatiotemporally defined as stationary reentries with a meandering tip remaining within half the wavelength and lasting longer than 5 s. We generated 2D- and 3D-maps of the PS, DF, ShEn, and CFAE-CL during AF. The spatial correlations and ablation outcomes targeting each parameter were analyzed. RESULTS 1. In the 2D PeAF model, we observed a mother rotor that matched relatively well with DF (>9 Hz, 71.0%, p<0.001), ShEn (upper 2.5%, 33.2%, p<0.001), and CFAE-CL (lower 2.5%, 23.7%, p<0.001). 2. The 3D-PeAF model also showed mother rotors that had spatial correlations with DF (>5.5 Hz, 39.7%, p<0.001), ShEn (upper 8.5%, 15.1%, p <0.001), and CFAE (lower 8.5%, 8.0%, p = 0.002). 3. In both the 2D and 3D models, virtual ablation targeting the upper 5% of the DF terminated AF within 20 s, but not the ablations based on long-lasting PS, high ShEn area, or lower CFAE-CL area. CONCLUSION Mother rotors were observed in both 2D and 3D human AF models. Rotor locations were well represented by DF, and their virtual ablation altered wave dynamics and terminated AF.
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Affiliation(s)
- Minki Hwang
- Division of Cardiology, Yonsei University Health System, Seoul, Republic of Korea
| | - Jun-Seop Song
- Division of Cardiology, Yonsei University Health System, Seoul, Republic of Korea
| | - Young-Seon Lee
- Division of Cardiology, Yonsei University Health System, Seoul, Republic of Korea
| | - Changyong Li
- Division of Cardiology, Yonsei University Health System, Seoul, Republic of Korea
| | - Eun Bo Shim
- Department of Mechanical and Biomedical Engineering, Kangwon National University, Chuncheon, Kangwon-do, Republic of Korea
- * E-mail: (HNP); (EBS)
| | - Hui-Nam Pak
- Division of Cardiology, Yonsei University Health System, Seoul, Republic of Korea
- * E-mail: (HNP); (EBS)
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Filgueiras-Rama D, Jalife J. STRUCTURAL AND FUNCTIONAL BASES OF CARDIAC FIBRILLATION. DIFFERENCES AND SIMILARITIES BETWEEN ATRIA AND VENTRICLES. JACC Clin Electrophysiol 2016; 2:1-3. [PMID: 27042693 DOI: 10.1016/j.jacep.2015.12.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Evidence accumulated over the last 25 years suggests that, whether in the atria or ventricles, fibrillation may be explained by the self-organization of the cardiac electrical activity into rapidly spinning rotors giving way to spiral waves that break intermittently and result in fibrillatory conduction. The dynamics and frequency of such rotors depend on the ion channel composition, excitability and refractory properties of the tissues involved, as well as on the thickness and respective three-dimensional fiber structure of the atrial and ventricular chambers. Therefore, improving the understanding of fibrillation has required the use of multidisciplinary research approaches, including optical mapping, patch clamping and molecular biology, and the application of concepts derived from the theory of wave propagation in excitable media. Moreover, translation of such concepts to the clinic has recently opened new opportunities to apply novel mechanistic approaches to therapy, particularly during atrial fibrillation ablation. Here we review the current understanding of the manner in which the underlying myocardial structure and function influence rotor initiation and maintenance during cardiac fibrillation. We also examine relevant underlying differences and similarities between atrial fibrillation and ventricular fibrillation and evaluate the latest clinical mapping technologies used to identify rotors in either arrhythmia. Altogether, the data being discussed have significantly improved our understanding of the cellular and structural bases of cardiac fibrillation and pointed toward potentially exciting new avenues for more efficient and effective identification and therapy of the most complex cardiac arrhythmias.
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Affiliation(s)
- David Filgueiras-Rama
- Fundación Centro Nacional de Investigaciones Cardiovasculares, Carlos III (CNIC)., Myocardial Pathophysiology Area, Madrid, Spain; Hospital Clínico San Carlos, Cardiology department, Madrid, Spain
| | - José Jalife
- Fundación Centro Nacional de Investigaciones Cardiovasculares, Carlos III (CNIC)., Myocardial Pathophysiology Area, Madrid, Spain; Center for Arrhythmia Research, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, EEUU
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Abstract
Atrial fibrillation (AF) is the most common cardiac arrhythmia; however, therapy is suboptimal. We review recent data on dynamics of wave propagation during AF and its mechanistic link to the substrate. Data show that the dominant frequency (DF) increase during transition to persistent AF may be explained by rotor acceleration. We discuss how translation of experimentally derived understanding of the rotors may find its way into the clinic, focusing on studies analyzing spatial distribution of DF in the atria of patients with paroxysmal versus persistent AF, and how that knowledge might contribute to improve the outcome of AF ablation procedures.
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Affiliation(s)
- Omer Berenfeld
- Center for Arrhythmia Research, University of Michigan, 2800 Plymouth Road, Ann Arbor, MI 48109, USA.
| | - José Jalife
- Center for Arrhythmia Research, University of Michigan, 2800 Plymouth Road, Ann Arbor, MI 48109, USA
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Drifting Through the Beehive. Biophys J 2014; 106:1555-6. [DOI: 10.1016/j.bpj.2014.03.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Accepted: 03/06/2014] [Indexed: 11/20/2022] Open
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