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Zaman J, Baykaner T, Narayan SM. Mapping and Ablation of Rotational and Focal Drivers in Atrial Fibrillation. Card Electrophysiol Clin 2020; 11:583-595. [PMID: 31706467 DOI: 10.1016/j.ccep.2019.08.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Drivers are increasingly studied ablation targets for atrial fibrillation (AF). However, results from ablation remain controversial. First, outcomes vary between centers and patients. Second, it is unclear how best to perform driver ablation. Third, there is a lack of practical guidance on how to identify critical from secondary sites using different AF mapping methods. This article addresses each of these issues.
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Affiliation(s)
- Junaid Zaman
- Stanford University, 780 Welch Road, Suite CJ250F, Stanford, CA 94305, USA; Imperial College London, London, UK
| | - Tina Baykaner
- Department of Medicine/Cardiovascular Medicine, Stanford University, 780 Welch Road, Suite CJ250F, Stanford, CA 94305, USA
| | - Sanjiv M Narayan
- Department of Medicine/Cardiovascular Medicine and Cardiovascular Institute, Stanford University, 780 Welch Road, Suite CJ250F, MC 5773, Stanford, CA 94305, USA.
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Sahli Costabal F, Zaman JAB, Kuhl E, Narayan SM. Interpreting Activation Mapping of Atrial Fibrillation: A Hybrid Computational/Physiological Study. Ann Biomed Eng 2018; 46:257-269. [PMID: 29214421 PMCID: PMC5880222 DOI: 10.1007/s10439-017-1969-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Accepted: 11/23/2017] [Indexed: 11/30/2022]
Abstract
Atrial fibrillation is the most common rhythm disorder of the heart associated with a rapid and irregular beating of the upper chambers. Activation mapping remains the gold standard to diagnose and interpret atrial fibrillation. However, fibrillatory activation maps are highly sensitive to far-field effects, and often disagree with other optical mapping modalities. Here we show that computational modeling can identify spurious non-local components of atrial fibrillation electrograms and improve activation mapping. We motivate our approach with a cohort of patients with potential drivers of persistent atrial fibrillation. In a computational study using a monodomain Maleckar model, we demonstrate that in organized rhythms, electrograms successfully track local activation, whereas in atrial fibrillation, electrograms are sensitive to spiral wave distance and number, spiral tip trajectories, and effects of fibrosis. In a clinical study, we analyzed n = 15 patients with persistent atrial fibrillation that was terminated by limited ablation. In five cases, traditional activation maps revealed a spiral wave at sites of termination; in ten cases, electrogram timings were ambiguous and activation maps showed incomplete reentry. By adjusting electrogram timing through computational modeling, we found rotational activation, which was undetectable with conventional methods. Our results demonstrate that computational modeling can identify non-local deflections to improve activation mapping and explain how and where ablation can terminate persistent atrial fibrillation. Our hybrid computational/physiological approach has the potential to optimize map-guided ablation and improve ablation therapy in atrial fibrillation.
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Zaman JAB, Baykaner T, Schricker AA, Krummen DE, Narayan SM. Mechanistic targets for the ablation of atrial fibrillation. Glob Cardiol Sci Pract 2017; 2017:e201707. [PMID: 28971106 PMCID: PMC5621726 DOI: 10.21542/gcsp.2017.7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
The mechanisms responsible for sustaining atrial fibrillation are a key debate in cardiovascular pathophysiology, and directly influence the approach to therapy including ablation Clinical and basic studies have split AF mechanisms into two basic camps: ‘spatially distributed disorganization’ and ‘localized sources’. Recent data suggest that these mechanisms can also be separated by the method for mapping – with nearly all traditional electrogram analyses showing spatially distributed disorganization and nearly all optical mapping studies showing localized sources We will review this dichotomy in light of these recently identified differences in mapping, and in the context of recent clinical studies in which localized ablation has been shown to impact AF, also lending support to the localized source hypothesis. We will conclude with other concepts on mechanism-based ablation and areas of ongoing research that must be addressed to continue improving our knowledge and treatment of AF.
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Affiliation(s)
- Junaid A B Zaman
- Stanford University, Palo Alto, California.,Imperial College, University of London, United Kingdom
| | - Tina Baykaner
- Stanford University, Palo Alto, California.,University of California, San Diego, California
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Narayan SM, Zaman JAB. Mechanistically based mapping of human cardiac fibrillation. J Physiol 2016; 594:2399-415. [PMID: 26607671 PMCID: PMC4850202 DOI: 10.1113/jp270513] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 11/20/2015] [Indexed: 12/02/2022] Open
Abstract
The mechanisms underpinning human cardiac fibrillation remain elusive. In his 1913 paper ‘On dynamic equilibrium in the heart’, Mines proposed that an activation wave front could propagate repeatedly in a circle, initiated by a stimulus in the vulnerable period. While the dynamics of activation and recovery are central to cardiac fibrillation, these physiological data are rarely used in clinical mapping. Fibrillation is a rapid irregular rhythm with spatiotemporal disorder resulting from two fundamental mechanisms – sources in preferred cardiac regions or spatially diffuse self‐sustaining activity, i.e. with no preferred source. On close inspection, however, this debate may also reflect mapping technique. Fibrillation is initiated from triggers by regional dispersion in repolarization, slow conduction and wavebreak, then sustained by non‐uniform interactions of these mechanisms. Notably, optical mapping of action potentials in atrial fibrillation (AF) show spiral wave sources (rotors) in nearly all studies including humans, while most traditional electrogram analyses of AF do not. Techniques may diverge in fibrillation because electrograms summate non‐coherent waves within an undefined field whereas optical maps define waves with a visually defined field. Also fibrillation operates at the limits of activation and recovery, which are well represented by action potentials while fibrillatory electrograms poorly represent repolarization. We conclude by suggesting areas for study that may be used, until such time as optical mapping is clinically feasible, to improve mechanistic understanding and therapy of human cardiac fibrillation.
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Affiliation(s)
| | - Junaid A B Zaman
- Stanford University, Palo Alto, CA, USA.,Imperial College London, London, UK
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Zaman JA, Baykaner T, Schricker AA, Krummen DE, Narayan SM. Mechanistic targets for the ablation of atrial fibrillation. Glob Cardiol Sci Pract 2015. [DOI: 10.5339/gcsp.2015.67] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
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Abstract
PURPOSE OF REVIEW Rotors have long been postulated to drive atrial fibrillation, but evidence has been limited to animal models. This changed recently with the demonstration using focal impulse and rotor modulation (FIRM) mapping that rotors act as human atrial fibrillation sources. This mechanistic approach to diagnosing the causes of atrial fibrillation in individual patients has been supported by substantially improved outcomes from FIRM-guided ablation, resulting in increased attention to rotors as therapeutic targets. RECENT FINDINGS In this review, we outline the pathophysiology of rotors in animal and in-silico studies of fibrillation, and how this motivated FIRM mapping in humans. We highlight the characteristics of rotors in human atrial fibrillation, now validated by several techniques, with discussion on similar and discrepant findings between techniques. The interventional approaches to eliminate atrial fibrillation rotors are explained and the ablation results in latest studies using FIRM are discussed. SUMMARY We propose that mapping localized sources for human atrial fibrillation, specifically rotors, is moving the field towards a unifying hypothesis that explains several otherwise contradictory observations in atrial fibrillation management. We conclude by suggesting areas of potential research that may reveal more about these critical sites and how these may lead to better and novel treatments for atrial fibrillation.
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Wright M, Narayan SM. Ablation of atrial fibrillation. Trends Cardiovasc Med 2015; 25:409-19. [PMID: 25572010 PMCID: PMC4764083 DOI: 10.1016/j.tcm.2014.11.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Revised: 11/21/2014] [Accepted: 11/24/2014] [Indexed: 01/08/2023]
Abstract
Ablation is increasingly used to treat AF, since recent trials of pharmacological therapy for AF have been disappointing. Ablation has been shown to improve maintenance of sinus rhythm compared to pharmacological therapy in many multicenter trials, although success rates remain suboptimal. This review will discuss several trends in the field of catheter ablation, including studies to advance our understanding of AF mechanisms in different patient populations, innovations in detecting and classifying AF, use of this information to improve strategies for ablation, technical innovations that have improved the ease and safety of ablation, and novel approaches to surgical therapy and imaging. These trends are likely to further improve results from AF ablation in coming years as it becomes an increasingly important therapeutic option for many patients.
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Affiliation(s)
- Matthew Wright
- BHF Centre of Excellence, London, UK; Division of Imaging Sciences and Biomedical Engineering, King׳s College London, King׳s Health Partners, St. Thomas׳ Hospital, London, UK
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Costet A, Bunting E, Grondin J, Gambhir A, Konofagou EE. Atrial electromechanical cycle length mapping in paced canine hearts in vivo. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2015; 62:1277-87. [PMID: 26168174 PMCID: PMC4651183 DOI: 10.1109/tuffc.2014.006932] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Atrial arrhythmias affect millions of people worldwide. Characterization and study of arrhythmias in the atria in the clinic is currently performed point by point using mapping catheters capable of generating maps of the electrical activation rate or cycle length. In this paper, we describe a new ultrasound-based mapping technique called electromechanical cycle length mapping (ECLM) capable of estimating the electromechanical activation rate, or cycle length, i.e., the rate of the mechanical activation of the myocardium which follows the electrical activation. ECLM relies on frequency analysis of the incremental strain within the atria and can be performed in a single acquisition. ECLM was validated in a canine model paced from the left atrial appendage, against pacing rates within the reported range of cycle lengths previously measured during atrial arrhythmias such as atrial fibrillation. Correlation between the global estimated electromechanical cycle lengths and pacing rates was shown to be excellent (slope = 0.983, intercept = 3.91, r(2) = 0.9999). The effect of the number of cardiac cycles on the performance of ECLM was also investigated and the reproducibility of ECLM was demonstrated (error between consecutive acquisitions for all pacing rates: 6.3 ± 4.3%). These findings indicate the potential of ECLM for noninvasively characterizing atrial arrhythmias and provide feedback on the treatment planning of catheter ablation procedures in the clinic.
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Schricker AA, Zaman J. Role of Rotors in the Ablative Therapy of Persistent Atrial Fibrillation. Arrhythm Electrophysiol Rev 2015; 4:47-52. [PMID: 26835100 DOI: 10.15420/aer.2015.4.1.47] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2015] [Accepted: 03/18/2015] [Indexed: 01/17/2023] Open
Abstract
Atrial fibrillation (AF) ablation is increasingly used to maintain sinus rhythm yet its results are sub-optimal, especially in patients with persistent AF or prior unsuccessful procedures. Attempts at improvement have often targeted substrates that sustain AF after it is triggered, yet those mechanisms are debated. Many studies now challenge the concept that AF is driven by self-sustaining disordered wavelets, showing instead that localised drivers (rotors) may drive disorder via a process known as fibrillatory conduction. Novel mapping using wide-area recordings, physiological filtering and phase analysis demonstrates rotors in human AF. Contact mapping with focal impulse and rotor modulation (FIRM) shows that localised ablation at sources can improve procedural success in many populations on long-term follow up and some newer approaches to rotor mapping are qualitatively similar. This review critically evaluates the data on rotor mapping and ablation, which advances our conceptual understanding of AF and holds the promise of substantially improving ablative outcomes in patients with persistent AF.
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Affiliation(s)
- Amir A Schricker
- Department of Cardiovascular Medicine, University of California San Diego Medical Center, San Diego, US
| | - Junaid Zaman
- Department of Cardiovascular Medicine, Stanford Medicine, Stanford, California, US
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Krummen DE, Swarup V, Narayan SM. The role of rotors in atrial fibrillation. J Thorac Dis 2015; 7:142-51. [PMID: 25713729 DOI: 10.3978/j.issn.2072-1439.2014.11.15] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Accepted: 10/23/2014] [Indexed: 11/14/2022]
Abstract
Despite significant advances in our understanding of atrial fibrillation (AF) mechanisms in the last 15 years, ablation outcomes remain suboptimal. A potential reason is that many ablation techniques focus on anatomic, rather than patient-specific functional targets for ablation. Panoramic contact mapping, incorporating phase analysis, repolarization and conduction dynamics, and oscillations in AF rate, overcomes many prior difficulties with mapping AF. This approach provides evidence that the mechanisms sustaining human AF are deterministic, largely due to stable electrical rotors and focal sources in either atrium. Ablation of such sources (Focal Impulse and Rotor Modulation: FIRM ablation) has been shown to improve ablation outcome compared with conventional ablation alone; independent laboratories directly targeting stable rotors have shown similar results. Clinical trials examining the role of stand-alone FIRM ablation are in progress. Looking forward, translating insights from patient-specific mapping to evidence-based guidelines and clinical practice is the next challenge in improving patient outcomes in AF management.
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Affiliation(s)
- David E Krummen
- 1 Department of Medicine/Cardiology, University of California San Diego Medical Center, San Diego, CA and VA San Diego Healthcare System, San Diego, CA 92161, USA ; 2 Arizona Heart Hospital, Phoenix, AZ, USA ; 3 Stanford University, Palo Alto, CA, USA
| | - Vijay Swarup
- 1 Department of Medicine/Cardiology, University of California San Diego Medical Center, San Diego, CA and VA San Diego Healthcare System, San Diego, CA 92161, USA ; 2 Arizona Heart Hospital, Phoenix, AZ, USA ; 3 Stanford University, Palo Alto, CA, USA
| | - Sanjiv M Narayan
- 1 Department of Medicine/Cardiology, University of California San Diego Medical Center, San Diego, CA and VA San Diego Healthcare System, San Diego, CA 92161, USA ; 2 Arizona Heart Hospital, Phoenix, AZ, USA ; 3 Stanford University, Palo Alto, CA, USA
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Swarup V, Baykaner T, Rostamian A, Daubert JP, Hummel J, Krummen DE, Trikha R, Miller JM, Tomassoni GF, Narayan SM. Stability of rotors and focal sources for human atrial fibrillation: focal impulse and rotor mapping (FIRM) of AF sources and fibrillatory conduction. J Cardiovasc Electrophysiol 2014; 25:1284-92. [PMID: 25263408 DOI: 10.1111/jce.12559] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Revised: 09/12/2014] [Accepted: 09/19/2014] [Indexed: 11/29/2022]
Abstract
INTRODUCTION Several groups report electrical rotors or focal sources that sustain atrial fibrillation (AF) after it has been triggered. However, it is difficult to separate stable from unstable activity in prior studies that examined only seconds of AF. We applied phase-based focal impulse and rotor mapping (FIRM) to study the dynamics of rotors/sources in human AF over prolonged periods of time. METHODS We prospectively mapped AF in 260 patients (169 persistent, 61 ± 12 years) at 6 centers in the FIRM registry, using baskets with 64 contact electrodes per atrium. AF was phase mapped (RhythmView, Topera, Menlo Park, CA, USA). AF propagation movies were interpreted by each operator to assess the source stability/dynamics over tens of minutes before ablation. RESULTS Sources were identified in 258 of 260 of patients (99%), for 2.8 ± 1.4 sources/patient (1.8 ± 1.1 in left, 1.1 ± 0.8 in right atria). While AF sources precessed in stable regions, emanating activity including spiral waves varied from collision/fusion (fibrillatory conduction). Each source lay in stable atrial regions for 4,196 ± 6,360 cycles, with no differences between paroxysmal versus persistent AF (4,290 ± 5,847 vs. 4,150 ± 6,604; P = 0.78), or right versus left atrial sources (P = 0.26). CONCLUSIONS Rotors and focal sources for human AF mapped by FIRM over prolonged time periods precess ("wobble") but remain within stable regions for thousands of cycles. Conversely, emanating activity such as spiral waves disorganize and collide with the fibrillatory milieu, explaining difficulties in using activation mapping or signal processing analyses at fixed electrodes to detect AF rotors. These results provide a rationale for targeted ablation at AF sources rather than fibrillatory spiral waves.
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A B Zaman Ma Bm BChir J, Schricker Md A, G Lalani Md G, Trikha Bs R, E Krummen Md D, M Narayan Md PhD S. Focal Impulse And Rotor Mapping (FIRM): Conceptualizing And Treating Atrial Fibrillation. J Atr Fibrillation 2014; 7:1103. [PMID: 27957100 DOI: 10.4022/jafib.1103] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2014] [Revised: 06/29/2014] [Accepted: 07/01/2014] [Indexed: 11/10/2022]
Abstract
Current approaches for the ablation of atrial fibrillation are often effective, but only partially rooted in mechanistic understanding. Accordingly, they are unable to predict whether a given patient will or will not do well, or which lesions sets should or should not be performed - in any given patient. This goal would require clearer mechanistic definition of what sustains AF after it has been triggered (i.e. electrophysiological substrates). There are two schools of thought. The first proposes disorganized activity that self-sustains with no 'driver', and the second describes drivers that then cause disorganization. Interestingly, these mechanisms can be separated in human studies by mapping approach - proponents of the disorganized hypothesis studying small atrial areas at high resolution, and proponents of the driver model studying wide fields-of-view at varying resolutions. Focal impulse and rotor modulation (FIRM) mapping combines a wide field of view with physiologically based signal filtering and phase analysis, and has revealed that human AF is often sustained by rotors. In the CONFIRM Trial, targeting stable AF rotors/sources for ablation improved the single-procedure efficacy for paroxysmal and persistent AF over conventional ablation alone, as now confirmed by independent laboratories. FIRM mapping gives a mechanistic foundation to predict whether any selected lesions should intersect AF sources in any given patient and which mechanisms may cause recurrence. Rotors of varying characteristics have now been shown by many groups. These insights have reinvigorated interest in AF mapping, and rationalizing these findings will likely translate into improved therapy for our patients.
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Affiliation(s)
| | | | | | - Rishi Trikha Bs
- National Heart and Lung Institute, Imperial College London, UK
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Abstract
Atrial fibrillation (AF) is the most common arrhythmia targeted by catheter ablation. Despite significant advances in our understanding of AF, ablation outcomes remain suboptimal, and this is due in large part to an incomplete understanding of the underlying sustaining mechanisms of AF. Recent developments of patient-tailored and physiology-based computational mapping systems have identified localized electrical spiral waves, or rotors, and focal sources as mechanisms that may represent novel targets for therapy. This report provides an overview of Focal Impulse and Rotor Modulation (FIRM) mapping, which reveals that human AF is often not actually driven by disorganized activity but instead that disorganization is secondary to organized rotors or focal sources. Targeted ablation of such sources alone can eliminate AF and, when added to pulmonary vein isolation, improves long-term outcome compared with conventional ablation alone. Translating mechanistic insights from such patient-tailored mapping is likely to be crucial in achieving the next major advances in personalized medicine for AF.
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Affiliation(s)
- Amir A. Schricker
- Department of Medicine/Cardiology, University of California San Diego Medical Center, San Diego, CA 92161, USA
| | - Gautam G. Lalani
- Department of Medicine/Cardiology, University of California San Diego Medical Center, San Diego, CA 92161, USA
| | - David E. Krummen
- Department of Medicine/Cardiology, University of California San Diego Medical Center, San Diego, CA 92161, USA
| | - Sanjiv M. Narayan
- Department of Medicine/Cardiology, University of California San Diego Medical Center, San Diego, CA 92161, USA
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Jarman JWE, Wong T, Kojodjojo P, Spohr H, Davies JER, Roughton M, Francis DP, Kanagaratnam P, O'Neill MD, Markides V, Davies DW, Peters NS. Organizational index mapping to identify focal sources during persistent atrial fibrillation. J Cardiovasc Electrophysiol 2014; 25:355-363. [PMID: 24383919 DOI: 10.1111/jce.12352] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2013] [Revised: 11/17/2013] [Accepted: 12/02/2013] [Indexed: 01/01/2023]
Abstract
INTRODUCTION Localized rotors have been implicated in the mechanism of persistent atrial fibrillation (AF). Although regions of highest dominant frequency (DF) on spectral analysis of the left atrium (LA) have been said to identify rotors, other mechanisms such as wavefront collisions will sporadically also generate an inconsistent distribution of high DF. We hypothesized that if drivers of AF were present, their distinctive spectral characteristics would result more from their temporal stability than their high frequency. METHODS AND RESULTS Ten patients with persistent AF underwent LA noncontact mapping. Following subtraction of far-field ventricular components, noncontact electrograms at 256 sites underwent fast Fourier transform. Mean absolute difference in DF between 5 sequential 7-second segments of AF was defined as the DF variability (DFV) at each site. Mean ratio of the DF and its harmonics to the total power of the spectrum was defined as the organizational index (OI). Mean DFV was significantly lower in organized areas (OI > 1 SD above mean) than at all sites (0.34 ± 0.04 vs 0.46 ± 0.04 Hz; P < 0.001). When organized areas were ablated during wide-area circumferential ablation, AF organized in remote regions (LA appendage ΔOI ablated vs unablated: +0.21 [0.06-0.41] vs -0.04 [-0.14-0.05]; P = 0.005). CONCLUSIONS At sites of organized activation, the activation frequency was also significantly more stable over time. This observation is consistent with the existence of focal sources, and inconsistent with a purely random activation pattern. Ablation of such regions is technically feasible, and was associated with organization of AF in remote atrial regions.
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Affiliation(s)
| | | | - Pipin Kojodjojo
- Imperial College London, UK.,St. Mary's Hospital, Imperial College Healthcare NHS Trust, London, UK
| | | | - Justin E R Davies
- Imperial College London, UK.,St. Mary's Hospital, Imperial College Healthcare NHS Trust, London, UK
| | | | - Darrel P Francis
- Imperial College London, UK.,St. Mary's Hospital, Imperial College Healthcare NHS Trust, London, UK
| | - Prapa Kanagaratnam
- Imperial College London, UK.,St. Mary's Hospital, Imperial College Healthcare NHS Trust, London, UK
| | | | | | - D Wyn Davies
- Imperial College London, UK.,St. Mary's Hospital, Imperial College Healthcare NHS Trust, London, UK
| | - Nicholas S Peters
- Imperial College London, UK.,St. Mary's Hospital, Imperial College Healthcare NHS Trust, London, UK
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Affiliation(s)
- Gautam G. Lalani
- University of California Medical Center, Veterans Affairs San Diego
- Stanford University
| | - Rishi Trikha
- University of California Medical Center, Veterans Affairs San Diego
- Stanford University
| | - David E. Krummen
- University of California Medical Center, Veterans Affairs San Diego
- Stanford University
| | - Sanjiv M. Narayan
- University of California Medical Center, Veterans Affairs San Diego
- Stanford University
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Ciaccio EJ, Biviano AB, Garan H. Comparison of spectral estimators for characterizing fractionated atrial electrograms. Biomed Eng Online 2013; 12:72. [PMID: 23855345 PMCID: PMC3728006 DOI: 10.1186/1475-925x-12-72] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Accepted: 07/10/2013] [Indexed: 12/04/2022] Open
Abstract
Background Complex fractionated atrial electrograms (CFAE) acquired during atrial fibrillation (AF) are commonly assessed using the discrete Fourier transform (DFT), but this can lead to inaccuracy. In this study, spectral estimators derived by averaging the autocorrelation function at lags were compared to the DFT. Method Bipolar CFAE of at least 16 s duration were obtained from pulmonary vein ostia and left atrial free wall sites (9 paroxysmal and 10 persistent AF patients). Power spectra were computed using the DFT and three other methods: 1. a novel spectral estimator based on signal averaging (NSE), 2. the NSE with harmonic removal (NSH), and 3. the autocorrelation function average at lags (AFA). Three spectral parameters were calculated: 1. the largest fundamental spectral peak, known as the dominant frequency (DF), 2. the DF amplitude (DA), and 3. the mean spectral profile (MP), which quantifies noise floor level. For each spectral estimator and parameter, the significance of the difference between paroxysmal and persistent AF was determined. Results For all estimators, mean DA and mean DF values were higher in persistent AF, while the mean MP value was higher in paroxysmal AF. The differences in means between paroxysmals and persistents were highly significant for 3/3 NSE and NSH measurements and for 2/3 DFT and AFA measurements (p<0.001). For all estimators, the standard deviation in DA and MP values were higher in persistent AF, while the standard deviation in DF value was higher in paroxysmal AF. Differences in standard deviations between paroxysmals and persistents were highly significant in 2/3 NSE and NSH measurements, in 1/3 AFA measurements, and in 0/3 DFT measurements. Conclusions Measurements made from all four spectral estimators were in agreement as to whether the means and standard deviations in three spectral parameters were greater in CFAEs acquired from paroxysmal or in persistent AF patients. Since the measurements were consistent, use of two or more of these estimators for power spectral analysis can be assistive to evaluate CFAE more objectively and accurately, which may lead to improved clinical outcome. Since the most significant differences overall were achieved using the NSE and NSH estimators, parameters measured from their spectra will likely be the most useful for detecting and discerning electrophysiologic differences in the AF substrate based upon frequency analysis of CFAE.
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Affiliation(s)
- Edward J Ciaccio
- Department of Medicine, Division of Cardiology, Columbia University Medical Center, 177 Fort Washington Avenue, New York, USA.
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Jones AR, Krummen DE, Narayan SM. Non-invasive identification of stable rotors and focal sources for human atrial fibrillation: mechanistic classification of atrial fibrillation from the electrocardiogram. Europace 2013; 15:1249-58. [PMID: 23449925 DOI: 10.1093/europace/eut038] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
AIMS To develop electrocardiogram (ECG) tools to quantify the number of sources for atrial fibrillation (AF), i.e. spatially stable rotors and focal impulses, and whether they lie in right or left atrium. Intracardiac mapping has recently shown that paroxysmal and persistent AF is sustained by rotors or focal sources that are stable in location and thus targets for limited ablation [focal impulse and rotor modulation (FIRM)] to eliminate AF. Importantly, the numbers and locations of concurrent sources determine both the complexity of AF and the approach for ablation. METHODS AND RESULTS In 36 AF patients (n = 29 persistent, 63 ± 9 years) in the CONventional ablation with or without Focal Impulse and Rotor Modulation (CONFIRM) trial, we developed phase lock (PL) to quantify spatial repeatability of ECG 'F-waves' between leads over time. Phase lock spectrally quantifies the angle θ between F-wave voltages in planes formed by ECG leads I, aVF, and V1 at successive points in time. We compared PL with ECG spectral dominant frequency (DF) and organizational index (OI) to characterize stable rotors and focal sources validated by intracardiac FIRM mapping. Focal impulse and rotor modulation ablation alone at ≤3 sources acutely terminated and rendered AF non-inducible or substantially slowed AF in 31 of 36 patients. Receiver operating characteristics of PL for this endpoint had area under the curve (AUC) = 0.72, and the optimum cut-point (PL = 0.09) had 74% sensitivity, 92% positive predictive value (PPV). Receiver operating characteristics areas for OI and DF were 0.50 and 0.58, respectively. Left (n = 28) or right (n = 3) atrial sources were localized by PL with AUC = 0.85, sensitivity 100%, PPV 30%, and negative predictive value 100%. Spectral DF provided AUC = 0.79. Notably, PL did not comigrate with diagnosis of paroxysmal or persistent AF (P = NS), unlike ECG DF. CONCLUSION The novel metric of ECG PL identifies patients with fewer (≤3) or greater numbers of stable rotors/focal sources for AF, validated by intracardiac FIRM mapping, and localized them to right or left atria. These data open the possibility of using 12-lead ECG analyses to classify AF mechanistically and plan procedures for right- or left-sided FIRM ablation.
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Affiliation(s)
- Aled R Jones
- School of Clinical Medicine, University of Cambridge, Cambridge, UK
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Joshi R, Schricker AA, Krummen DE, Narayan SM. Getting to the core of AF irregularity: are we there yet? J Cardiovasc Electrophysiol 2013; 24:207-9. [PMID: 23252599 PMCID: PMC3746515 DOI: 10.1111/jce.12043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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19
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Narayan SM, Krummen DE, Rappel WJ. Clinical mapping approach to diagnose electrical rotors and focal impulse sources for human atrial fibrillation. J Cardiovasc Electrophysiol 2012; 23:447-54. [PMID: 22537106 DOI: 10.1111/j.1540-8167.2012.02332.x] [Citation(s) in RCA: 268] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
INTRODUCTION The perpetuating mechanisms for human atrial fibrillation (AF) remain undefined. Localized rotors and focal beat sources may sustain AF in elegant animal models, but there has been no direct evidence for localized sources in human AF using traditional methods. We developed a clinical computational mapping approach, guided by human atrial tissue physiology, to reveal sources of human AF. METHODS AND RESULTS In 49 AF patients referred for ablation (62 ± 9 years; 30 persistent), we defined repolarization dynamics using monophasic action potentials (MAPs) and recorded AF activation from 64-pole basket catheters in left atrium and, in n = 20 patients, in both atria. Careful positioning of basket catheters was required for optimal mapping. AF electrograms at 64-128 electrodes were combined with repolarization and conduction dynamics to construct spatiotemporal AF maps. We observed sustained sources in 47/49 patients, in the form of electrical rotors (n = 57) and focal beats (n = 11) that controlled local atrial activation with peripheral wavebreak (fibrillatory conduction). Patients with persistent AF had more sources than those with paroxysmal AF (2.1 ± 1.0 vs 1.5 ± 0.8, P = 0.02), related to shorter cycle length (163 ± 19 milliseconds vs 187 ± 25 milliseconds, P < 0.001). Approximately one-quarter of sources lay in the right atrium. CONCLUSIONS Physiologically guided computational mapping revealed sustained electrical rotors and repetitive focal beats during human AF for the first time. These localized sources were present in 96% of AF patients, and controlled AF activity. These results provide novel mechanistic insights into human AF and lay the foundation for mechanistically tailored approaches to AF ablation.
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Affiliation(s)
- Sanjiv M Narayan
- Veterans' Affairs and University of California Medical Centers, San Diego, CA, USA.
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20
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Forclaz A, Narayan SM, Scherr D, Linton N, Jadidi AS, Nault I, Rivard L, Miyazaki S, Uldry L, Wright M, Shah AJ, Liu X, Xhaet O, Derval N, Knecht S, Sacher F, Jaïs P, Hocini M, Haïssaguerre M. Early temporal and spatial regularization of persistent atrial fibrillation predicts termination and arrhythmia-free outcome. Heart Rhythm 2011; 8:1374-82. [PMID: 21699850 DOI: 10.1016/j.hrthm.2011.05.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2011] [Accepted: 05/09/2011] [Indexed: 11/17/2022]
Abstract
BACKGROUND Termination of persistent atrial fibrillation (AF) is a valuable ablation endpoint but is difficult to anticipate. We evaluated whether temporal and spatial indices of AF regularization predict intraprocedural AF termination and outcome. OBJECTIVE The purpose of this study was to test whether temporospatial organization of AF after pulmonary vein isolation (PVI) predicts whether subsequent stepwise ablation will terminate persistent AF or predict outcome. METHODS In 75 patients with persistent AF, we measured AF cycle length (AFCL), temporal regularity index (TRI, a spectral measure of timing regularity), and spatial regularity index (SRI, cycle-to-cycle variations in spatial vector) between right atrial appendage and proximal and distal coronary sinus before and during stepwise ablation to the endpoint of AF termination. RESULTS AF termination was achieved in 59 patients (79%) by ablation. AF terminated during PVI in 11 patients, who were excluded from analysis. In the remaining 48 patients, TRI and SRI increased during stepwise ablation, as compared with 16 patients without termination (P<.05). AFCL was prolonged in both groups. From receiver operating characteristics analysis of the first 22 patients (training set), a post-PVI TRI increase predicted AF termination in the latter 42 patients (test set) with a positive predictive value of 96%, negative predictive value of 53%, sensitivity of 71%, and specificity of 91%. Results were similar for SRI. After 36 months, higher arrhythmia-free outcome was observed in patients in whom PVI caused temporospatial regularization in AF. CONCLUSIONS Temporal and spatial regularization of persistent AF after PVI identifies patients in whom stepwise ablation subsequently terminates AF and prevents recurrence.
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Ciaccio EJ, Biviano AB, Whang W, Coromilas J, Garan H. A new transform for the analysis of complex fractionated atrial electrograms. Biomed Eng Online 2011; 10:35. [PMID: 21569421 PMCID: PMC3125385 DOI: 10.1186/1475-925x-10-35] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2011] [Accepted: 05/12/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Representation of independent biophysical sources using Fourier analysis can be inefficient because the basis is sinusoidal and general. When complex fractionated atrial electrograms (CFAE) are acquired during atrial fibrillation (AF), the electrogram morphology depends on the mix of distinct nonsinusoidal generators. Identification of these generators using efficient methods of representation and comparison would be useful for targeting catheter ablation sites to prevent arrhythmia reinduction. METHOD A data-driven basis and transform is described which utilizes the ensemble average of signal segments to identify and distinguish CFAE morphologic components and frequencies. Calculation of the dominant frequency (DF) of actual CFAE, and identification of simulated independent generator frequencies and morphologies embedded in CFAE, is done using a total of 216 recordings from 10 paroxysmal and 10 persistent AF patients. The transform is tested versus Fourier analysis to detect spectral components in the presence of phase noise and interference. Correspondence is shown between ensemble basis vectors of highest power and corresponding synthetic drivers embedded in CFAE. RESULTS The ensemble basis is orthogonal, and efficient for representation of CFAE components as compared with Fourier analysis (p ≤ 0.002). When three synthetic drivers with additive phase noise and interference were decomposed, the top three peaks in the ensemble power spectrum corresponded to the driver frequencies more closely as compared with top Fourier power spectrum peaks (p ≤ 0.005). The synthesized drivers with phase noise and interference were extractable from their corresponding ensemble basis with a mean error of less than 10%. CONCLUSIONS The new transform is able to efficiently identify CFAE features using DF calculation and by discerning morphologic differences. Unlike the Fourier transform method, it does not distort CFAE signals prior to analysis, and is relatively robust to jitter in periodic events. Thus the ensemble method can provide a useful alternative for quantitative characterization of CFAE during clinical study.
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Affiliation(s)
- Edward J Ciaccio
- Department of Medicine, Division of Cardiology, Columbia University, USA
| | - Angelo B Biviano
- Department of Medicine, Division of Cardiology, Columbia University, USA
| | - William Whang
- Department of Medicine, Division of Cardiology, Columbia University, USA
| | - James Coromilas
- Department of Medicine, University of Medicine and Dentistry of New Jersey, USA
| | - Hasan Garan
- Department of Medicine, Division of Cardiology, Columbia University, USA
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Classifying fractionated electrograms in human atrial fibrillation using monophasic action potentials and activation mapping: evidence for localized drivers, rate acceleration, and nonlocal signal etiologies. Heart Rhythm 2010; 8:244-53. [PMID: 20955820 DOI: 10.1016/j.hrthm.2010.10.020] [Citation(s) in RCA: 155] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2010] [Accepted: 10/11/2010] [Indexed: 01/10/2023]
Abstract
BACKGROUND Complex fractionated electrograms (CFAEs) detected during substrate mapping for atrial fibrillation (AF) reflect etiologies that are difficult to separate. Without knowledge of local refractoriness and activation sequence, CFAEs may represent rapid localized activity, disorganized wave collisions, or far-field electrograms. OBJECTIVE The purpose of this study was to separate CFAE types in human AF, using monophasic action potentials (MAPs) to map local refractoriness in AF and multipolar catheters to map activation sequence. METHODS MAP and adjacent activation sequences at 124 biatrial sites were studied in 18 patients prior to AF ablation (age 57 ± 13 years, left atrial diameter 45 ± 8 mm). AF cycle length, bipolar voltage, and spectral dominant frequency were measured to characterize types of CFAE. RESULTS CFAE were observed at 91 sites, most of which showed discrete MAPs and (1) pansystolic local activity (8%); (2) CFAE after AF acceleration, often with MAP alternans (8%); or (3) nonlocal (far-field) signals (67%). A fourth CFAE pattern lacked discrete MAPs (17%), consistent with spatial disorganization. CFAE with discrete MAPs and pansystolic activation (consistent with rapid localized AF sites) had shorter cycle length (P <.05) and lower voltage (P <.05) and trended to have higher dominant frequency than other CFAE sites. Many CFAEs, particularly at the septa and coronary sinus, represented far-field signals. CONCLUSION CFAEs in human AF represent distinct functional types that may be separated using MAPs and activation sequence. In a minority of cases, CFAEs indicate localized rapid AF sites. The majority of CFAEs reflect far-field signals, AF acceleration, or disorganization. These results may help to interpret CFAE during AF substrate mapping.
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Ciaccio EJ, Biviano AB, Whang W, Wit AL, Coromilas J, Garan H. Optimized Measurement of Activation Rate at Left Atrial Sites with Complex Fractionated Electrograms During Atrial Fibrillation. J Cardiovasc Electrophysiol 2010; 21:133-43. [PMID: 19793138 DOI: 10.1111/j.1540-8167.2009.01595.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Edward J Ciaccio
- Department of Pharmacology, Columbia University, New York, NY 10032, USA.
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Krummen DE, Peng KA, Bullinga JR, Narayan SM. Centrifugal gradients of rate and organization in human atrial fibrillation. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2009; 32:1366-78. [PMID: 19744279 DOI: 10.1111/j.1540-8159.2009.02525.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
INTRODUCTION Animal studies show that atrial fibrillation (AF) may emanate from sites of high rate and regularity, with fibrillatory conduction to adjacent areas. We used simultaneous mapping to find evidence for potential drivers in human AF defined as sites with higher rate and regularity than surrounding tissue. MATERIALS AND METHODS In 24 patients (age 61+/-10 years; 12 persistent), we recorded AF simultaneously from 32 left atrial bipolar basket electrodes in addition to pulmonary veins (PV), coronary sinus, and right atrial electrodes. We measured AF cycle length (CL) by Fourier transform and electrogram regularity at each electrode, referenced to patient-specific atrial anatomy. RESULTS We analyzed 10,298 electrode-periods. Evidence for potential AF drivers was found in 11 patients (five persistent). In persistent AF, these sites lay at the coronary sinus and left atrial roof but not PVs, while in paroxysmal AF six of nine sites lay at PVs (P<0.05). During ablation, a subset of patients experienced AF CL prolongation or termination with a focal lesion; in each case this lesion mapped to potential driver sites on blinded analysis. Conversely, sequential mapping failed to reveal these sites, possibly due to fluctuations in dominant frequency at driver locations in the context of migratory AF. CONCLUSIONS Simultaneous multisite recordings in human AF reveal evidence for drivers that lie near PVs in paroxysmal but not persistent AF, and were sites where ablation slowed or terminated AF in a subset of patients. The future work should determine if real-time ablation of AF-maintaining regions defined in this fashion eliminates AF.
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Affiliation(s)
- David E Krummen
- University of California San Diego and VA San Diego Healthcare System, San Diego, California 92161, USA.
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25
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Krummen DE, Narayan SM. Mechanisms for the initiation of human atrial fibrillation. Heart Rhythm 2009; 6:S12-6. [DOI: 10.1016/j.hrthm.2009.03.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/31/2008] [Indexed: 01/22/2023]
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Ravi KC, Krummen DE, Tran AJ, Bullinga JR, Narayan SM. Electrocardiographic measurements of regional atrial fibrillation cycle length. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2009; 32 Suppl 1:S66-71. [PMID: 19250115 DOI: 10.1111/j.1540-8159.2008.02229.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND Differences in atrial fibrillation (AF) cycle length (CL) between the left (LA) and right (RA) atrium and coronary sinus (CS) may help separate paroxysmal from persistent AF and identify patients most likely to respond to pulmonary vein isolation, but has not been measured noninvasively. METHODS AND RESULTS We developed methods to estimate regional intraatrial AF CL from the surface electrocardiogram (ECG) in 20 patients with persistent AF and 10 patients with paroxysmal AF prior to ablation. Intraatrial AF CL was measured near the LA appendage, mid-CS, and lateral RA. In simultaneous filtered ECG, AF CL was estimated using autocorrelation. The mean of ECG-derived AF CL in leads V5, I, and aVL was used to estimate LA CL; leads aVF, II, and III for CS CL; and V1, V2, and aVR for RA CL. ECG CL estimates for the LA, CS, and RA had R(2) > 0.91 versus measured CL (all P < 0.001). Though magnitudes of left-versus-right AF CL gradients were small in this series, the ECG predicted the direction of gradients in 62% of measurements (P < 0.05). When the gradient was >10 ms, the direction was accurately predicted in eight of 11 patients. The accuracy of AF CL estimates was not adversely affected by AF type or LA dilatation (< or =40 or >40 mm). The ECG-estimated AF-CL showed high 5-minute temporal stability (P < 0.001 each chamber). CONCLUSIONS Left and right atrial AF CL, and their gradients, can be accurately determined from the ECG using autocorrelation analysis. This approach may be a helpful guide prior to ablation procedures.
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Affiliation(s)
- Krishna C Ravi
- University of California and Veterans Affairs Medical Center, San Diego, California 92161, USA
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Diemberger I, McCready J, Nunn L, Chow AW. Is atrial fibrillation with very short cycle length suitable for ablation? A case report. Europace 2008; 10:1336-9. [DOI: 10.1093/europace/eun189] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Dibs SR, Ng J, Arora R, Passman RS, Kadish AH, Goldberger JJ. Spatiotemporal characterization of atrial activation in persistent human atrial fibrillation: Multisite electrogram analysis and surface electrocardiographic correlations—A pilot study. Heart Rhythm 2008; 5:686-93. [DOI: 10.1016/j.hrthm.2008.01.027] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2007] [Accepted: 01/17/2008] [Indexed: 11/24/2022]
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STILES MARTINK, BROOKS ANTHONYG, JOHN BOBBY, WILSON LAUREN, KUKLIK PAWEL, DIMITRI HANY, LAU DENNISH, ROBERTS-THOMSON ROSSL, MACKENZIE LORRAINE, WILLOUGHBY SCOTT, YOUNG GLENND, SANDERS PRASHANTHAN. The Effect of Electrogram Duration on Quantification of Complex Fractionated Atrial Electrograms and Dominant Frequency. J Cardiovasc Electrophysiol 2008; 19:252-8. [DOI: 10.1111/j.1540-8167.2007.01034.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Narayan SM, Krummen DE. Dynamics factors preceding the initiation of atrial fibrillation in humans. Heart Rhythm 2008; 5:S22-5. [PMID: 18456196 DOI: 10.1016/j.hrthm.2008.01.030] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2007] [Indexed: 11/17/2022]
Affiliation(s)
- Sanjiv M Narayan
- University of California and Veterans Administration Medical Centers, San Diego, California, USA
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Abstract
INTRODUCTION Dominant frequency (DF) analysis of atrial electrograms has been used to characterize atrial fibrillation (AF). The aim of this study was to explore technical issues that may affect the estimation of local activation rate during AF using DF analysis. METHODS AND RESULTS Epicardial atrial electrograms recorded during AF from 10 dogs were used to evaluate the effects of unipolar versus bipolar recordings, bipolar electrode spacing, postrecording processing, far field ventricular depolarizations, ventricular template subtraction, and signal duration on DF analysis. Simulated electrograms were used to evaluate the effect of far field ventricular depolarizations and signal-to-noise ratio. DFs were compared with activation rates obtained by manual marking and the reproducibility of the DFs was evaluated. Bipolar electrograms were found to be preferable to unipolar electrograms. Preprocessing was a necessary step for bipolar signals, but also aided analysis of unipolar recordings. Ventricular far field depolarizations significantly affected DFs. Ventricular template subtraction helped DF analysis in signals with both minimal and significant ventricular components. A recording duration above 2 seconds was required for reliable DF measurements. Signal-to-noise ratios below 13 dB could also affect DF, particularly for signals with significant amplitude and frequency variation. CONCLUSIONS Various factors affect DF analysis. Proper interpretation of DF analysis requires careful evaluation of the AF signals and robust processing techniques.
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Affiliation(s)
- Jason Ng
- Bluhm Cardiovascular Center and the Division of Cardiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA
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