1
|
Rennison JH, Van Wagoner DR. Dysregulated Ca2+ cycling in atrial fibrillation. Eur Heart J 2023; 44:2495-2497. [PMID: 37012620 PMCID: PMC10344643 DOI: 10.1093/eurheartj/ehad099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 04/05/2023] Open
Affiliation(s)
- Julie H Rennison
- Department of Cardiovascular & Metabolic Sciences, Cleveland Clinic, M/S ND-50, 9500 Euclid Avenue, Cleveland, OH 44195, USA
| | - David R Van Wagoner
- Department of Cardiovascular & Metabolic Sciences, Cleveland Clinic, M/S ND-50, 9500 Euclid Avenue, Cleveland, OH 44195, USA
| |
Collapse
|
2
|
Alrabghi G, Liu Y, Hu W, Hancox JC, Zhang H. Human atrial fibrillation and genetic defects in transient outward currents: mechanistic insights from multi-scale computational models. Philos Trans R Soc Lond B Biol Sci 2023; 378:20220166. [PMID: 37122220 PMCID: PMC10150223 DOI: 10.1098/rstb.2022.0166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2023] Open
Abstract
Previous studies have linked dysfunctional Ito arising from mutations to KCND3-encoded Kv4.3 and KCND2-encoded Kv4.2 to atrial fibrillation. Using computational models, this study aimed to investigate the mechanisms underlying pro-arrhythmic effects of the gain-of-function Kv4.3 (T361S, A545P) and Kv4.2 (S447R) mutations. Wild-type and mutant Ito formulations were developed from and validated against experimental data and incorporated into the Colman et al. model of human atrial cells. Single-cell models were incorporated into one- (1D) and two-dimensional (2D) models of atrial tissue, and a three-dimensional (3D) realistic model of the human atria. The three gain-of-function mutations had similar, albeit quantitatively different, effects: shortening of the action potential duration; lowering the plateau membrane potential, abbreviating the effective refractory period (ERP) and the wavelength (WL) of atrial excitation at the tissue level. Restitution curves for the WL, the ERP and the conduction velocity were leftward shifted, facilitating the conduction of atrial excitation waves at high excitation rates. The mutations also increased lifespan and stationarity of re-entry in both 2D and 3D simulations, which further highlighted a mutation-induced increase in spatial dispersion of repolarization. Collectively, these changes account for pro-arrhythmic effects of these Kv4.3 and Kv4.2 mutations in facilitating AF. This article is part of the theme issue 'The heartbeat: its molecular basis and physiological mechanisms'.
Collapse
Affiliation(s)
- Ghadah Alrabghi
- Biological Physics Group, Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK
- Department of Physics, Faculty of Science, University of Jeddah, 21959 Jeddah, Saudi Arabia
| | - Yizhou Liu
- Biological Physics Group, Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK
| | - Wei Hu
- Biological Physics Group, Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK
| | - Jules C Hancox
- Biological Physics Group, Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK
- School of Physiology, Pharmacology and Neuroscience, Medical Sciences Building, University Walk, Bristol BS8 1TD, UK
| | - Henggui Zhang
- Biological Physics Group, Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK
- Key Laboratory of Medical Electrophysiology of Ministry of Education and Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, Southwest Medical University, 646099 Luzhou, People's Republic of China
| |
Collapse
|
3
|
Hartley A, Shalhoub J, Ng FS, Krahn AD, Laksman Z, Andrade JG, Deyell MW, Kanagaratnam P, Sikkel MB. Size matters in atrial fibrillation: the underestimated importance of reduction of contiguous electrical mass underlying the effectiveness of catheter ablation. Europace 2021; 23:1698-1707. [PMID: 33948648 PMCID: PMC8576280 DOI: 10.1093/europace/euab078] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Accepted: 03/22/2021] [Indexed: 11/13/2022] Open
Abstract
Evidence has accumulated over the last century of the importance of a critical electrical mass in sustaining atrial fibrillation (AF). AF ablation certainly reduces electrically contiguous atrial mass, but this is not widely accepted to be an important part of its mechanism of action. In this article, we review data showing that atrial size is correlated in many settings with AF propensity. Larger mammals are more likely to exhibit AF. This is seen both in the natural world and in animal models, where it is much easier to create a goat model than a mouse model of AF, for example. This also extends to humans-athletes, taller people, and obese individuals all have large atria and are more likely to exhibit AF. Within an individual, risk factors such as hypertension, valvular disease and ischaemia can enlarge the atrium and increase the risk of AF. With respect to AF ablation, we explore how variations in ablation strategy and the relative effectiveness of these strategies may suggest that a reduction in electrical atrial mass is an important mechanism of action. We counter this with examples in which there is no doubt that mass reduction is less important than competing theories such as ganglionated plexus ablation. We conclude that, when considering future strategies for the ablative therapy of AF, it is important not to discount the possibility that contiguous electrical mass reduction is the most important mechanism despite the disappointing consequence being that enhancing success rates in AF ablation may involve greater tissue destruction.
Collapse
Affiliation(s)
- Adam Hartley
- National Heart and Lung Institute,Imperial College London, London, UK
| | - Joseph Shalhoub
- National Heart and Lung Institute,Imperial College London, London, UK
| | - Fu Siong Ng
- National Heart and Lung Institute,Imperial College London, London, UK
| | - Andrew D Krahn
- Division of Cardiology, University of British Columbia, 740 Hillside Ave, Vancouver, BC V8T 1Z4, Canada
| | - Zachary Laksman
- Division of Cardiology, University of British Columbia, 740 Hillside Ave, Vancouver, BC V8T 1Z4, Canada
| | - Jason G Andrade
- Division of Cardiology, University of British Columbia, 740 Hillside Ave, Vancouver, BC V8T 1Z4, Canada
| | - Marc W Deyell
- Division of Cardiology, University of British Columbia, 740 Hillside Ave, Vancouver, BC V8T 1Z4, Canada
| | | | - Markus B Sikkel
- Division of Cardiology, University of British Columbia, 740 Hillside Ave, Vancouver, BC V8T 1Z4, Canada
- Division of Medical Sciences, University of Victoria, Victoria, Canada
| |
Collapse
|
4
|
van Staveren LN, de Groot NMS. Exploring Refractoriness as an Adjunctive Electrical Biomarker for Staging of Atrial Fibrillation. J Am Heart Assoc 2020; 9:e018427. [PMID: 33238778 PMCID: PMC7763798 DOI: 10.1161/jaha.120.018427] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Patients diagnosed with the same subtype of atrial fibrillation according to our current classification system may differ in symptom severity, severity of the arrhythmogenic substrate, and response to antiarrhythmic therapy. Hence, there is a need for an electrical biomarker as an indicator of the arrhythmogenic substrate underlying atrial fibrillation enabling patient‐tailored therapy. The aim of this review is to investigate whether atrial refractoriness, a well‐known electrophysiological parameter that is affected by electrical remodeling, can be used as an electrical biomarker of the arrhythmogenic substrate underlying atrial fibrillation. We discuss methodologies of atrial effective refractory period assessment, identify which changes in refractoriness‐related parameters reflect different degrees of electrical remodeling, and explore whether these parameters can be used to predict clinical outcomes.
Collapse
|
5
|
Yamaji H, Higashiya S, Murakami T, Hina K, Kawamura H, Murakami M, Kamikawa S, Hirohata S, Kusachi S. Efficacy of an Adjunctive Electrophysiological Test-Guided Left Atrial Posterior Wall Isolation in Persistent Atrial Fibrillation Without a Left Atrial Low-Voltage Area. Circ Arrhythm Electrophysiol 2020; 13:e008191. [PMID: 32660260 DOI: 10.1161/circep.119.008191] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Electrical remodeling precedes structural remodeling. In adjunctive left atrial (LA) low-voltage area (LVA) ablation to pulmonary vein isolation of atrial fibrillation (AF), LA areas without LVA have not been targeted for ablation. We studied the effect of adjunctive LA posterior wall isolation (PWI) on persistent AF without LA-LVA according to electrophysiological testing (EP test). METHODS We examined consecutive patients with persistent AF with (n=33) and without (n=111) LA-LVA. Patients without LA-LVA were randomly assigned to EP test-guided (n=57) and control (n=54) groups. In the EP test-guided group, an adjunctive PWI was performed in those with positive results (PWI subgroup; n=24), but not in those with negative results (n=33). The criteria for positive EP tests were an effective refractory period ≤180 ms, effective refractory period>20 ms shorter than the other sites, and/or induction of AF/atrial tachycardia (AT) during measurements. LVA ablation was performed in the patients with LA-LVA. RESULTS During the follow-up period (62±33 weeks), the EP test-guided group had significantly lower recurrence rates (19%,11/57 versus 41%, 22/54, P=0.012) and higher Kaplan-Meier AF/AT-free survival curve rates than the control group (P=0.01). No significant differences in the recurrence and AF/AT-free survival curve rates between the PWI (positive EP test) and non-PWI (negative EP test) subgroups were observed. Therefore, PWI for positive EP tests reduced the AF/AT recurrence in the EP test-guided group. A stepwise Cox proportional hazard analyses identified EP test-guided ablation as a factor reducing the recurrence rate. The recurrence rates in the LA-LVA ablation group and EP test-guided group were similar. CONCLUSIONS This pilot study proposed that an EP test-guided adjunctive PWI of persistent AF without LA-LVA potentially reduced AF/AT recurrences. The results suggest that there is an AF substrate in the LA with altered electrophysiological function even when there is no LA-LVA. Graphic Abstract: A graphic abstract is available for this article.
Collapse
Affiliation(s)
- Hirosuke Yamaji
- Heart Rhythm Center, Okayama Heart Clinic, Takeda 54-1, Naka-Ku, Japan (H.Y., S. Higashiya, T.M., K.H., H.K., M.M., S. Kamikawa, S. Kusachi)
| | - Shunichi Higashiya
- Heart Rhythm Center, Okayama Heart Clinic, Takeda 54-1, Naka-Ku, Japan (H.Y., S. Higashiya, T.M., K.H., H.K., M.M., S. Kamikawa, S. Kusachi)
| | - Takashi Murakami
- Heart Rhythm Center, Okayama Heart Clinic, Takeda 54-1, Naka-Ku, Japan (H.Y., S. Higashiya, T.M., K.H., H.K., M.M., S. Kamikawa, S. Kusachi)
| | - Kazuyoshi Hina
- Heart Rhythm Center, Okayama Heart Clinic, Takeda 54-1, Naka-Ku, Japan (H.Y., S. Higashiya, T.M., K.H., H.K., M.M., S. Kamikawa, S. Kusachi)
| | - Hiroshi Kawamura
- Heart Rhythm Center, Okayama Heart Clinic, Takeda 54-1, Naka-Ku, Japan (H.Y., S. Higashiya, T.M., K.H., H.K., M.M., S. Kamikawa, S. Kusachi)
| | - Masaaki Murakami
- Heart Rhythm Center, Okayama Heart Clinic, Takeda 54-1, Naka-Ku, Japan (H.Y., S. Higashiya, T.M., K.H., H.K., M.M., S. Kamikawa, S. Kusachi)
| | - Shigeshi Kamikawa
- Heart Rhythm Center, Okayama Heart Clinic, Takeda 54-1, Naka-Ku, Japan (H.Y., S. Higashiya, T.M., K.H., H.K., M.M., S. Kamikawa, S. Kusachi)
| | - Satoshi Hirohata
- Department of Medical Technology, Okayama University Graduate School of Health Sciences, Japan (S. Hirohata, S. Kusachi)
| | - Shozo Kusachi
- Heart Rhythm Center, Okayama Heart Clinic, Takeda 54-1, Naka-Ku, Japan (H.Y., S. Higashiya, T.M., K.H., H.K., M.M., S. Kamikawa, S. Kusachi).,Department of Medical Technology, Okayama University Graduate School of Health Sciences, Japan (S. Hirohata, S. Kusachi)
| |
Collapse
|
6
|
Alzahrani T, McCaffrey J, Mercader M, Solomon A. Rate Versus Rhythm Control in Patients with Normal to Mild Left Atrial Enlargement: Insights from the AFFIRM Trial. J Atr Fibrillation 2019; 11:2067. [PMID: 31139272 DOI: 10.4022/jafib.2067] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2017] [Revised: 08/19/2017] [Accepted: 09/14/2017] [Indexed: 12/19/2022]
Abstract
Background Atrial fibrillation is the most commonly encountered sustained arrhythmia and is associated with significant morbidity and mortality. Several trials have demonstrated that no mortality benefit exists when choosing a rhythm-control strategy over a rate-control strategy, with some trials suggesting an increase in mortality. Using the AFFIRM trial database we sought to determine the effect of rhythm control strategy in patients with normal or mild atrial enlargement. Methods AFFIRM Trial database was used to evaluate the effect of rhythm-control strategy compared to rate-control strategy in a subgroup of patients with normal to mild left atrial (LA) enlargement. The primary outcome measures of this study were all-cause mortality, cardiovascular mortality, non-cardiovascular mortality, and hospitalization/ED visit. Results We identified a subgroup of subjects from the AFFIRM trial with normal or mild LA enlargement (n=2022 of 4060 total subjects). Subjects in the rhythm-control group(n= 1022) had an increased risk of all-cause mortality by 34% (RR 1.34, 95% CI 1.08-1.67; P=0.007) and hospitalization/ED visits by 10% (RR 1.10, 95% CI 1.05-2.16; P=<0.001) compared to rate control group(n= 1000). Conclusion This study demonstrated that rhythm-control strategy increases the risk of mortality and hospitalization in a subgroup of patients with normal to mild atrial enlargement compared to rate-control strategy. Amiodarone use in this subgroup of patients likely drove these findings.
Collapse
Affiliation(s)
- Talal Alzahrani
- Division of Cardiology, Department of Medicine, George Washington University, Washington, DC
| | - James McCaffrey
- Division of Cardiology, Department of Medicine, George Washington University, Washington, DC
| | - Marco Mercader
- Division of Cardiology, Department of Medicine, George Washington University, Washington, DC
| | - Allen Solomon
- Division of Cardiology, Department of Medicine, George Washington University, Washington, DC
| |
Collapse
|
7
|
Scacciatella P, Jorfida M, Biava LM, Meynet I, Zema D, D’Ascenzo F, Pristipino C, Cerrato P, Giustetto C, Gaita F. Insertable cardiac monitor detection of silent atrial fibrillation in candidates for percutaneous patent foramen ovale closure. J Cardiovasc Med (Hagerstown) 2019; 20:290-296. [DOI: 10.2459/jcm.0000000000000790] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
|
8
|
Gunes H, Sokmen A, Kaya H, Gungor O, Kerkutluoglu M, Guzel FB, Sokmen G. Evaluation of Atrial Electromechanical Delay to Predict Atrial Fibrillation in Hemodialysis Patients. ACTA ACUST UNITED AC 2018; 54:medicina54040058. [PMID: 30344289 PMCID: PMC6174336 DOI: 10.3390/medicina54040058] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Revised: 08/20/2018] [Accepted: 08/23/2018] [Indexed: 11/16/2022]
Abstract
Background and objective: Prevalence of atrial fibrillation is higher in hemodialysis patients as compared to the general population. Atrial electromechanical delay is known as a significant predictor of atrial fibrillation. In this study, we aimed to reveal the relationship between atrial electromechanical delay and attacks of atrial fibrillation. Materials and methods: The study included 77 hemodialysis patients over 18 years of age giving written consent to participate in the study. The patients were divided into two groups based on the results of 24-h Holter Electrocardiogram (Holter ECG) as the ones having attacks of atrial fibrillation and the others without any attack of atrial fibrillation. Standard echocardiographic measurements were taken from all patients. Additionally, atrial conduction times were measured by tissue Doppler technique and atrial electromechanical delays were calculated. Results: Intra- and interatrial electromechanical delay were found as significantly lengthened in the group of patients with attacks of atrial fibrillation (p = 0.03 and p < 0.001 respectively). The optimal cut-off time for interatrial electromechanical delay to predict atrial fibrillation was >21 ms with a specificity of 79.3% and a sensitivity of 73.7% (area under the curve 0.820; 95% confidence interval (CI), 0.716⁻0.898). In the multivariate logistic regression model, interatrial electromechanical delay (odds ratio = 1.230; 95% CI, 1.104⁻1.370; p < 0.001) and hypertension (odds ratio = 4.525; 95% CI, 1.042⁻19.651; p = 0.044) were also associated with atrial fibrillation after adjustment for variables found to be statistically significant in univariate analysis and correlated with interatrial electromechanical delay. Conclusions: Interatrial electromechanical delay is independently related with the attacks of atrial fibrillation detected on Holter ECG records in hemodialysis patients.
Collapse
Affiliation(s)
- Hakan Gunes
- Department of Cardiology, Sutcu Imam University, 46040 Kahramanmaras, Turkey.
| | - Abdullah Sokmen
- Department of Cardiology, Sutcu Imam University, 46040 Kahramanmaras, Turkey.
| | - Hakki Kaya
- Department of Cardiology, Cumhuriyet University, 58140 Sivas, Turkey.
| | - Ozkan Gungor
- Department of Nephrology, Sutcu Imam University, 46040 Kahramanmaras, Turkey.
| | - Murat Kerkutluoglu
- Department of Cardiology, Sutcu Imam University, 46040 Kahramanmaras, Turkey.
| | - Fatma Betul Guzel
- Department of Nephrology, Sutcu Imam University, 46040 Kahramanmaras, Turkey.
| | - Gulizar Sokmen
- Department of Cardiology, Sutcu Imam University, 46040 Kahramanmaras, Turkey.
| |
Collapse
|
9
|
Attuel G, Gerasimova-Chechkina E, Argoul F, Yahia H, Arneodo A. Multifractal Desynchronization of the Cardiac Excitable Cell Network During Atrial Fibrillation. I. Multifractal Analysis of Clinical Data. Front Physiol 2018; 8:1139. [PMID: 29632492 PMCID: PMC5880174 DOI: 10.3389/fphys.2017.01139] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Accepted: 12/24/2017] [Indexed: 12/19/2022] Open
Abstract
Atrial fibrillation (AF) is a cardiac arrhythmia characterized by rapid and irregular atrial electrical activity with a high clinical impact on stroke incidence. Best available therapeutic strategies combine pharmacological and surgical means. But when successful, they do not always prevent long-term relapses. Initial success becomes all the more tricky to achieve as the arrhythmia maintains itself and the pathology evolves into sustained or chronic AF. This raises the open crucial issue of deciphering the mechanisms that govern the onset of AF as well as its perpetuation. In this study, we develop a wavelet-based multi-scale strategy to analyze the electrical activity of human hearts recorded by catheter electrodes, positioned in the coronary sinus (CS), during episodes of AF. We compute the so-called multifractal spectra using two variants of the wavelet transform modulus maxima method, the moment (partition function) method and the magnitude cumulant method. Application of these methods to long time series recorded in a patient with chronic AF provides quantitative evidence of the multifractal intermittent nature of the electric energy of passing cardiac impulses at low frequencies, i.e., for times (≳0.5 s) longer than the mean interbeat (≃ 10-1 s). We also report the results of a two-point magnitude correlation analysis which infers the absence of a multiplicative time-scale structure underlying multifractal scaling. The electric energy dynamics looks like a "multifractal white noise" with quadratic (log-normal) multifractal spectra. These observations challenge concepts of functional reentrant circuits in mechanistic theories of AF, still leaving open the role of the autonomic nervous system (ANS). A transition is indeed observed in the computed multifractal spectra which group according to two distinct areas, consistently with the anatomical substrate binding to the CS, namely the left atrial posterior wall, and the ligament of Marshall which is innervated by the ANS. In a companion paper (II. Modeling), we propose a mathematical model of a denervated heart where the kinetics of gap junction conductance alone induces a desynchronization of the myocardial excitable cells, accounting for the multifractal spectra found experimentally in the left atrial posterior wall area.
Collapse
Affiliation(s)
- Guillaume Attuel
- Geometry and Statistics in Acquisition Data, Centre de Recherche INRIA, Talence, France
| | | | - Francoise Argoul
- Laboratoire Ondes et Matières d'Aquitaine, Université de Bordeaux, Centre National de la Recherche Scientifique, UMR 5798, Talence, France
| | - Hussein Yahia
- Geometry and Statistics in Acquisition Data, Centre de Recherche INRIA, Talence, France
| | - Alain Arneodo
- Laboratoire Ondes et Matières d'Aquitaine, Université de Bordeaux, Centre National de la Recherche Scientifique, UMR 5798, Talence, France
| |
Collapse
|
10
|
ICaL and Ito mediate rate-dependent repolarization in rabbit atrial myocytes. J Physiol Biochem 2017; 74:57-67. [DOI: 10.1007/s13105-017-0603-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Accepted: 12/04/2017] [Indexed: 01/01/2023]
|
11
|
Avula UMR, Noonavath M, Wan E. Gender Differences in Atrial Fibrillation. GENDER AND THE GENOME 2017. [DOI: 10.1089/gg.2016.0002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Affiliation(s)
- Uma Mahesh R. Avula
- Department of Medicine, Division of Cardiology, Columbia University, New York, New York
| | - Meghana Noonavath
- Department of Medicine, Division of Cardiology, Columbia University, New York, New York
| | - Elaine Wan
- Department of Medicine, Division of Cardiology, Columbia University, New York, New York
| |
Collapse
|
12
|
Avula U, Noonavath M, Wan E. Review Article: Gender Differences in Atrial Fibrillation. GENDER AND THE GENOME 2017. [DOI: 10.1177/247028971700100101] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
|
13
|
Nair GM, Nery PB, Redpath CJ, Sadek MM, Birnie DH. Electrophysiological abnormalities in subjects with lone atrial fibrillation – Too little, too late? Indian Pacing Electrophysiol J 2016; 16:149-151. [PMID: 27979372 PMCID: PMC5153427 DOI: 10.1016/j.ipej.2016.11.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Accepted: 11/29/2016] [Indexed: 11/23/2022] Open
|
14
|
Abstract
BACKGROUND The mechanism(s) of how atrial fibrillation (AF) sustains itself in the first 24 hours is not well understood. OBJECTIVE We sought to investigate the role of autonomic remodeling in the first 24 hours of AF simulated by rapid atrial pacing (RAP). METHODS Forty-eight rabbits were divided into 6 groups. One group (n = 8) was euthanized after baseline recordings. Another group (n = 8) did not receive RAP during the 24-hour period to serve as controls. In the other 4 groups, rabbits were euthanized after RAP for 4, 8, 12, or 24 hours (n = 8 for each). Before and after designated hours of RAP, atrial effective refractory period, heart rate variability, and left vagal and sympathetic nerve activity (VNA and SNA, respectively) were determined. The right and left atrial tissues were obtained for immunocytochemical analysis for growth-associated protein 43 (GAP43), tyrosine hydroxylase (TH), and choline acetyltransferase (ChAT). RESULTS RAP resulted in progressively shortened atrial effective refractory period and slower heart rate. In the first 12 hours of RAP, both SNA and VNA progressively increased. Then, VNA remained stably elevated but SNA began to attenuate. The high-frequency component and low-frequency/high-frequency ratio of heart rate variability followed the trend of VNA and SNA, respectively. The density of GAP43-positive, ChAT-positive, and TH-positive neural elements in the right and left atria was progressively higher with RAP. CONCLUSIONS AF resulted in progressive autonomic remodeling, manifesting as nerve sprouting, sympathetic and vagal hyperinnervation. Autonomic remodeling may play an important role in sustaining AF in the first 24 hours.
Collapse
|
15
|
FONTENLA ADOLFO, SALGUERO RAFAEL, MARTINEZ-FERRER JOSEB, RODRIGUEZ ANIBAL, ALZUETA JAVIER, GARCIA ENRIQUE, BASTERRA NURIA, ROMERO RAFAEL, CONCHA JOAQUINFERNANDEZDELA, VIÑOLAS XAVIER, VILLACASTIN JULIAN, LOPEZ-GIL MARIA, ARRIBAS FERNANDO. Atrial Rate-Responsive Pacing and Incidence of Sustained Atrial Arrhythmias in Patients with Implantable Cardioverter Defibrillators. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2016; 39:548-56. [DOI: 10.1111/pace.12856] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Revised: 03/05/2016] [Accepted: 03/09/2016] [Indexed: 11/30/2022]
Affiliation(s)
- ADOLFO FONTENLA
- Cardiology Department; University Hospital 12 de Octubre; Madrid Spain
| | - RAFAEL SALGUERO
- Cardiology Department; University Hospital 12 de Octubre; Madrid Spain
| | | | - ANIBAL RODRIGUEZ
- Cardiology Department; University Hospital of Canarias; San Cristóbal de La Laguna Santa Cruz de Tenerife Spain
| | - JAVIER ALZUETA
- Cardiology Department; Hospital Virgen de la Victoria; Malaga Spain
| | - ENRIQUE GARCIA
- Cardiology Department; University Hospital of Vigo; Vigo Spain
| | - NURIA BASTERRA
- Cardiology Department; Hospital of Navarra; Pamplona Spain
| | - RAFAEL ROMERO
- Cardiology Department; Hospital Nuestra Señora de la Candelaria; Santa Cruz de Tenerife Spain
| | | | - XAVIER VIÑOLAS
- Cardiology Department; Hospital Santa Creu i Sant Pau; Barcelona Spain
| | | | - MARIA LOPEZ-GIL
- Cardiology Department; University Hospital 12 de Octubre; Madrid Spain
| | - FERNANDO ARRIBAS
- Cardiology Department; University Hospital 12 de Octubre; Madrid Spain
| |
Collapse
|
16
|
Lee YS, Hwang M, Song JS, Li C, Joung B, Sobie EA, Pak HN. The Contribution of Ionic Currents to Rate-Dependent Action Potential Duration and Pattern of Reentry in a Mathematical Model of Human Atrial Fibrillation. PLoS One 2016; 11:e0150779. [PMID: 26964092 PMCID: PMC4795605 DOI: 10.1371/journal.pone.0150779] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Accepted: 02/17/2016] [Indexed: 11/19/2022] Open
Abstract
Persistent atrial fibrillation (PeAF) in humans is characterized by shortening of action potential duration (APD) and attenuation of APD rate-adaptation. However, the quantitative influences of particular ionic current alterations on rate-dependent APD changes, and effects on patterns of reentry in atrial tissue, have not been systematically investigated. Using mathematical models of human atrial cells and tissue and performing parameter sensitivity analysis, we evaluated the quantitative contributions to action potential (AP) shortening and APD rate-adaptation of ionic current remodeling seen with PeAF. Ionic remodeling in PeAF was simulated by reducing L-type Ca2+ channel current (ICaL), increasing inward rectifier K+ current (IK1) and modulating five other ionic currents. Parameter sensitivity analysis, which quantified how each ionic current influenced APD in control and PeAF conditions, identified interesting results, including a negative effect of Na+/Ca2+ exchange on APD only in the PeAF condition. At high pacing rate (2 Hz), electrical remodeling in IK1 alone accounts for the APD reduction of PeAF, but at slow pacing rate (0.5 Hz) both electrical remodeling in ICaL alone (-70%) and IK1 alone (+100%) contribute equally to the APD reduction. Furthermore, AP rate-adaptation was affected by IKur in control and by INaCa in the PeAF condition. In a 2D tissue model, a large reduction (-70%) of ICaL becomes a dominant factor leading to a stable spiral wave in PeAF. Our study provides a quantitative and unifying understanding of the roles of ionic current remodeling in determining rate-dependent APD changes at the cellular level and spatial reentry patterns in tissue.
Collapse
Affiliation(s)
- Young-Seon Lee
- Yonsei University Health System, Seoul, Republic of Korea
| | - Minki Hwang
- Yonsei University Health System, Seoul, Republic of Korea
| | - Jun-Seop Song
- Yonsei University Health System, Seoul, Republic of Korea
| | - Changyong Li
- Yonsei University Health System, Seoul, Republic of Korea
| | - Boyoung Joung
- Yonsei University Health System, Seoul, Republic of Korea
| | - Eric A. Sobie
- Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
- * E-mail: (HNP); (EAS)
| | - Hui-Nam Pak
- Yonsei University Health System, Seoul, Republic of Korea
- * E-mail: (HNP); (EAS)
| |
Collapse
|
17
|
Left atrial reverse remodeling and prevention of progression of atrial fibrillation with atrial resynchronization device therapy utilizing dual-site right atrial pacing in patients with atrial fibrillation refractory to antiarrhythmic drugs or catheter ablation. J Interv Card Electrophysiol 2014; 40:245-54. [DOI: 10.1007/s10840-014-9931-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Accepted: 06/08/2014] [Indexed: 10/25/2022]
|
18
|
Violi F, Pastori D, Pignatelli P, Loffredo L. Antioxidants for prevention of atrial fibrillation: a potentially useful future therapeutic approach? A review of the literature and meta-analysis. Europace 2014; 16:1107-16. [DOI: 10.1093/europace/euu040] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
|
19
|
Loose S, Mueller J, Wettwer E, Knaut M, Ford J, Milnes J, Ravens U. Effects of IKur blocker MK-0448 on human right atrial action potentials from patients in sinus rhythm and in permanent atrial fibrillation. Front Pharmacol 2014; 5:26. [PMID: 24624083 PMCID: PMC3940943 DOI: 10.3389/fphar.2014.00026] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Accepted: 02/12/2014] [Indexed: 11/30/2022] Open
Abstract
Selective blockers of the Kv1.5 channel have been developed for the treatment of atrial fibrillation (AF), but little is known how these atrial-selective drugs affect human action potentials (APs). Therefore we have investigated the Kv1.5 blocker MK-0448 (N-{6-[(1S)-1-(4-fluorophenyl)-2,2-di(pyridin-3-yl)ethyl]pyridin-2-yl}methanesulfon- amide) in right atrial trabeculae from patients in sinus rhythm (SR), permanent AF (>6 months), and intermittent AF. MK-0448 blocked Kv1.5 current in an expression system and concentration-dependently elevated the plateau phase of atrial APs. In SR preparations stimulated at 1 Hz, MK-0448 (3 μM) shortened action potential duration at 90% of repolarization (APD90) and effective refractory period (ERP), but in permanent AF preparations, MK-0448 prolonged APD90 and ERP. The effects of MK-0448 in intermittent AF resembled those in SR preparations. Block of IKs is probably more prominent in AF because of reduced repolarization reserve due to AF-induced remodeling.
Collapse
Affiliation(s)
- Simone Loose
- Department of Pharmacology and Toxicology, Medical Faculty Carl Gustav Carus, Dresden University of Technology Dresden, Germany
| | - Judith Mueller
- Department of Pharmacology and Toxicology, Medical Faculty Carl Gustav Carus, Dresden University of Technology Dresden, Germany
| | - Erich Wettwer
- Department of Pharmacology and Toxicology, Medical Faculty Carl Gustav Carus, Dresden University of Technology Dresden, Germany
| | - Michael Knaut
- Clinic for Cardiac Surgery, Heart Center Dresden Dresden, Germany
| | | | | | - Ursula Ravens
- Department of Pharmacology and Toxicology, Medical Faculty Carl Gustav Carus, Dresden University of Technology Dresden, Germany
| |
Collapse
|
20
|
Atrial fibrillation: A progressive atrial myopathy or a distinct disease? Int J Cardiol 2014; 171:126-33. [DOI: 10.1016/j.ijcard.2013.12.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Revised: 10/09/2013] [Accepted: 12/10/2013] [Indexed: 02/06/2023]
|
21
|
|
22
|
Perego M, Skert S, Santilli RA. Analysis of the atrial repolarization wave in dogs with third-degree atrioventricular block. Am J Vet Res 2013; 75:54-8. [PMID: 24370246 DOI: 10.2460/ajvr.75.1.54] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To characterize the electrocardiographic features of the atrial repolarization (Ta) wave in dogs with third-degree atrioventricular (AV) block. SAMPLE ECGs of 36 dogs with third-degree AV block and no identifiable structural heart diseases. PROCEDURES Standard 12-lead ECGs were acquired with a digital system, and measurements were manually edited. RESULTS A Ta wave was detectable in all dogs for at least 1 ECG lead. The Ta wave had negative polarity in leads I, II, III, and aVF and positive polarity in leads aVL and aVR, with a mean electrical axis of -114.26°. Mean duration and mean amplitude of the Ta wave in lead II were 140.2 milliseconds and -0.09 mV, respectively, with the ratio for the Ta-to-P wave duration of 2.3 and the ratio of Ta-to-P wave amplitude of -0.35. Significant correlations were found between the Ta wave duration and duration of the P-Ta interval, Ta wave amplitude and the ECG lead, Ta wave duration and body weight, and duration of the P-Ta interval and atrial rate. Measurements of the Ta wave were repeatable. CONCLUSIONS AND CLINICAL RELEVANCE Measurements of the Ta wave in dogs with third-degree AV block were repeatable. The values for the Ta wave reported here can be used as reference values for dogs with AV conduction disturbances and an echocardiographically normal atrial size. Further studies are needed to validate these results in dogs with structural heart diseases.
Collapse
Affiliation(s)
- Manuela Perego
- Cardiology Division, Clinica Veterinaria Malpensa, Viale Marconi 27, Samarate (VA) Italy
| | | | | |
Collapse
|
23
|
Franz MR, Jamal SM, Narayan SM. The role of action potential alternans in the initiation of atrial fibrillation in humans: a review and future directions. Europace 2013; 14 Suppl 5:v58-v64. [PMID: 23104916 DOI: 10.1093/europace/eus273] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
This review highlights the role of atrial monophasic action potential duration (APD) in understanding atrial electrical properties in paroxysmal, persistent, and permanent atrial fibrillation (AF) states. Alternans of APD and rate maladaptation in a spatially divergent way appear mechanistically involved in AF initiation, development, and persistence. The underlying pathophysiology warrants further investigation.
Collapse
Affiliation(s)
- Michael R Franz
- Cardiology Division, VA Medical Center, 50 Irving Street NW, Washington, DC 20422, USA.
| | | | | |
Collapse
|
24
|
Voigt N, Heijman J, Trausch A, Mintert-Jancke E, Pott L, Ravens U, Dobrev D. Impaired Na⁺-dependent regulation of acetylcholine-activated inward-rectifier K⁺ current modulates action potential rate dependence in patients with chronic atrial fibrillation. J Mol Cell Cardiol 2013; 61:142-52. [PMID: 23531443 DOI: 10.1016/j.yjmcc.2013.03.011] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/24/2012] [Revised: 02/07/2013] [Accepted: 03/11/2013] [Indexed: 01/23/2023]
Abstract
Shortened action-potential duration (APD) and blunted APD rate adaptation are hallmarks of chronic atrial fibrillation (cAF). Basal and muscarinic (M)-receptor-activated inward-rectifier K(+) currents (IK1 and IK,ACh, respectively) contribute to regulation of human atrial APD and are subject to cAF-dependent remodeling. Intracellular Na(+) ([Na(+)]i) enhances IK,ACh in experimental models but the effect of [Na(+)]i-dependent regulation of inward-rectifier K(+) currents on APD in human atrial myocytes is currently unknown. Here, we report a [Na(+)]i-dependent inhibition of outward IK1 in atrial myocytes from sinus rhythm (SR) or cAF patients. In contrast, IK,ACh activated by carbachol, a non-selective M-receptor agonist, increased with elevation of [Na(+)]i in SR. This [Na(+)]i-dependent IK,ACh regulation was absent in cAF. Including [Na(+)]i dependence of IK1 and IK,ACh in a recent computational model of the human atrial myocyte revealed that [Na(+)]i accumulation at fast rates inhibits IK1 and blunts physiological APD rate dependence in both groups. [Na(+)]i-dependent IK,ACh augmentation at fast rates increased APD rate dependence in SR, but not in cAF. These results identify impaired Na(+)-sensitivity of IK,ACh as one potential mechanism contributing to the blunted APD rate dependence in patients with cAF. This article is part of a Special Issue entitled "Na(+) Regulation in Cardiac Myocytes".
Collapse
Affiliation(s)
- Niels Voigt
- Institute of Pharmacology, Faculty of Medicine, University Duisburg-Essen, 45122 Essen, Germany
| | | | | | | | | | | | | |
Collapse
|
25
|
Nodari S, Triggiani M, Campia U, Dei Cas L. Omega-3 Polyunsaturated Fatty Acid Supplementation: Mechanism and Current Evidence in Atrial Fibrillation. J Atr Fibrillation 2012; 5:718. [PMID: 28496797 DOI: 10.4022/jafib.718] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Revised: 04/21/2012] [Accepted: 06/18/2012] [Indexed: 11/10/2022]
Abstract
Atrial fibrillation (AF) is the most prevalent arrhythmia and is associated with considerable morbidity and mortality. Available pharmacologic antiarrhythmic therapies are often ineffective in preventing the recurrence of AF, possibly because these drugs target a single pathophysiological mechanism. Given their beneficial effects on ventricular arrhythmias, omega-3 polyunsaturated fatty acids (n-3 PUFAs) have recently been investigated as possible candidates in the treatment of supraventricular arrhythmias. In this review, we explore the current understanding of the antiarrhythmic effects attributed to n-3 PUFAs including direct modulation of ionic channels, improvement of membrane fluidity, anti-inflammatory and antifibrotic effects, and modulation of sympatho-vagal balance. We will then focus on the results of epidemiologic studies exploring the associations between nutritional intake of n3 PUFAs and the incidence of AF, and will review the findings of the clinical trials investigating the effects of n-3 PUFAs supplementation in the prophylaxis of AF and in the prevention of its recurrences.
Collapse
Affiliation(s)
- Savina Nodari
- Department of Experimental and Applied Medicine-Section of Cardiovascular Diseases, University of Brescia, Brescia, Italy
| | - Marco Triggiani
- Department of Experimental and Applied Medicine-Section of Cardiovascular Diseases, University of Brescia, Brescia, Italy
| | - Umberto Campia
- Northwestern University Feinberg School of Medicine, Chicago (IL), US
| | - Livio Dei Cas
- Department of Experimental and Applied Medicine-Section of Cardiovascular Diseases, University of Brescia, Brescia, Italy
| |
Collapse
|
26
|
Grubitzsch H, Haverkamp W. Atrial Remodelling : Role in Atrial Fibrillation Ablation. J Atr Fibrillation 2012; 5:691. [PMID: 28496795 DOI: 10.4022/jafib.691] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Revised: 11/02/2012] [Accepted: 11/23/2012] [Indexed: 12/19/2022]
Abstract
There have been considerable advances in understanding the relationship of atrial fibrillation (AF) and atrial remodelling suggesting that remodelling states have a significant impact on treatment results. Therefore, we reviewed the literature about the role of atrial remodelling in AF treatment, focussing on AF ablation. Atrial fibrillatory activity, dominant frequencies (DF), complex fractionated atrial electrograms (CFAE) as well as function, volume, and fibrosis of the - especially left - atrium are most important characteristics for electrical, contractile, and structural remodelling predicting success of AF treatment. In particular, the results of AF ablation, either using catheter-based or surgical techniques, predominantly depend on the degree of structural remodelling, namely dilatation and fibrosis of the left atrium. The available data suggest that recognizing parameters of remodelling as predictors for AF treatment facilitates differentiation between patients who may or may not benefit from the procedure and individualization of AF treatment by adapting lesion sets, by ablating additional targets, by reducing left atrial size, or by applying extended pharmacological treatment.
Collapse
Affiliation(s)
| | - Wilhelm Haverkamp
- Medizinische Klinik mit Schwerpunkt Kardiologie, Campus Virchow-Klinikum, Charité - Universit?tsmedizin Berlin, Berlin, Germany
| |
Collapse
|
27
|
Genetic suppression of atrial fibrillation using a dominant-negative ether-a-go-go-related gene mutant. Heart Rhythm 2011; 9:265-72. [PMID: 21907172 DOI: 10.1016/j.hrthm.2011.09.008] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/02/2011] [Accepted: 09/02/2011] [Indexed: 12/31/2022]
Abstract
BACKGROUND Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia. Gene therapy-dependent modulation of atrial electrophysiology may provide a more specific alternative to pharmacological and ablative treatment strategies. OBJECTIVE We hypothesized that genetic inactivation of atrial repolarizing ether-a-go-go-related gene (ERG) K(+) currents using a dominant-negative mutant would provide rhythm control in AF. METHODS Ten domestic swine underwent pacemaker implantation and were subjected to atrial burst pacing to induce persistent AF. Animals were then randomized to receive either AdCERG-G627S to suppress ERG/I(Kr) currents or green fluorescent protein (AdGFP) as control. Adenoviruses were applied using a novel hybrid technique combining atrial virus injection and epicardial electroporation to increase transgene expression. RESULTS In pigs treated with AdCERG-G627S, the onset of persistent AF was prevented (n = 2) or significantly delayed compared with AdGFP controls (12 ± 2.1 vs. 6.2 ± 1.3 days; P < .001) during 14-day follow-up. Effective refractory periods were prolonged in the AdCERG-G627S group compared with AdGFP animals (221.5 ± 4.7 ms vs. 197.0 ± 4.7 ms; P < .006). Impairment of left ventricular ejection fraction (LVEF) during AF was prevented by AdCERG-G627S application (LVEF(CERG-G627S) = 62.1% ± 4.0% vs. LVEF(GFP) = 30.3% ± 9.1%; P < .001). CONCLUSION Inhibition of ERG function using atrial AdCERG-G627S gene transfer suppresses or delays the onset of persistent AF by prolongation of atrial refractoriness in a porcine model. Targeted gene therapy represents an alternative to pharmacological or ablative treatment of AF.
Collapse
|
28
|
Centurion OA. Atrial Fibrillation in the Wolff-Parkinson-White Syndrome. J Atr Fibrillation 2011; 4:287. [PMID: 28496688 DOI: 10.4022/jafib.287] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2010] [Revised: 08/19/2010] [Accepted: 04/14/2011] [Indexed: 11/10/2022]
Abstract
Since the advent of catheter ablation for atrial fibrillation (AF) aiming the pulmonary veins a few years ago, there has been an overwhelming interest and a dramatic increase in AF investigation. AF has a different dimension in the context of the Wolff-Parkinson-White (WPW) syndrome. Indeed, AF may be a nightmare in a young person that has an accessory pathway (AP) with fast anterograde conduction. It may be life-threatening if an extremely rapid ventricular response develops degenerating into ventricular fibrillation. Therefore, it is very important to know the mechanisms involved in the development of AF in the WPW syndrome. There are several possible mechanisms that may be involved in the development of AF in the WPW syndrome, namely, spontaneous degeneration of atrioventricular reciprocating tachycardia into AF, the electrophysiological properties of the AP, the effects of AP on atrial architecture, and intrinsic atrial muscle vulnerability. Focal activity, multiple reentrant wavelets, and macroreentry have all been implicated in AF, perhaps under the further influence of the autonomic nervous system. AF can also be initiated by ectopic beats originating from the pulmonary veins, and elsewhere. Several studies demonstrated a decrease incidence of AF after successful elimination of the AP, suggesting that the AP itself may play an important role in the initiation of AF. However, since AF still occurs in some patients with the WPW syndrome even after successful ablation of the AP, there should be other mechanisms responsible for the development of AF in the WPW syndrome. There is a clear evidence of an underlying atrial muscle disease in patients with the WPW syndrome. Atrial myocardial vulnerability has been studied performing an atrial endocardial catheter mapping during sinus rhythm, and analizing the recorded abnormal atrial electrograms. This review analizes the available data on this singular setting since AF has a reserved prognostic significance in patients with the WPW syndrome, and has an unusually high incidence in the absence of any clinical evidence of organic heart disease.
Collapse
Affiliation(s)
- Osmar Antonio Centurion
- Division of Electrophysiology and Arrhythmias, Cardiovascular Institute, Sanatorio Migone-Battilana. Asuncion, Paraguay, Departamento de Cardiologia, Primera Catedra de Clínica Médica, Universidad Nacional de Asuncion
| |
Collapse
|
29
|
Schotten U, Verheule S, Kirchhof P, Goette A. Pathophysiological mechanisms of atrial fibrillation: a translational appraisal. Physiol Rev 2011; 91:265-325. [PMID: 21248168 DOI: 10.1152/physrev.00031.2009] [Citation(s) in RCA: 852] [Impact Index Per Article: 65.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Atrial fibrillation (AF) is an arrhythmia that can occur as the result of numerous different pathophysiological processes in the atria. Some aspects of the morphological and electrophysiological alterations promoting AF have been studied extensively in animal models. Atrial tachycardia or AF itself shortens atrial refractoriness and causes loss of atrial contractility. Aging, neurohumoral activation, and chronic atrial stretch due to structural heart disease activate a variety of signaling pathways leading to histological changes in the atria including myocyte hypertrophy, fibroblast proliferation, and complex alterations of the extracellular matrix including tissue fibrosis. These changes in electrical, contractile, and structural properties of the atria have been called "atrial remodeling." The resulting electrophysiological substrate is characterized by shortening of atrial refractoriness and reentrant wavelength or by local conduction heterogeneities caused by disruption of electrical interconnections between muscle bundles. Under these conditions, ectopic activity originating from the pulmonary veins or other sites is more likely to occur and to trigger longer episodes of AF. Many of these alterations also occur in patients with or at risk for AF, although the direct demonstration of these mechanisms is sometimes challenging. The diversity of etiological factors and electrophysiological mechanisms promoting AF in humans hampers the development of more effective therapy of AF. This review aims to give a translational overview on the biological basis of atrial remodeling and the proarrhythmic mechanisms involved in the fibrillation process. We pay attention to translation of pathophysiological insights gained from in vitro experiments and animal models to patients. Also, suggestions for future research objectives and therapeutical implications are discussed.
Collapse
Affiliation(s)
- Ulrich Schotten
- Department of Physiology, University Maastricht, Maastricht, The Netherlands.
| | | | | | | |
Collapse
|
30
|
DE VOS CEESB, PISON LAURENT, PISTERS RON, SCHOTTEN ULRICH, CHERIEX EMILEC, PRINS MARTINH, DELHAAS TAMMO, CRIJNS HARRYJ, TIELEMAN ROBERTG. Atrial Fibrillatory Wall Motion and Degree of Atrial Remodeling in Patients with Atrial Fibrillation: A Tissue Velocity Imaging Study. J Cardiovasc Electrophysiol 2009; 20:1374-81. [DOI: 10.1111/j.1540-8167.2009.01628.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
31
|
Sridhar A, Nishijima Y, Terentyev D, Khan M, Terentyeva R, Hamlin RL, Nakayama T, Gyorke S, Cardounel AJ, Carnes CA. Chronic heart failure and the substrate for atrial fibrillation. Cardiovasc Res 2009; 84:227-36. [PMID: 19567484 DOI: 10.1093/cvr/cvp216] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
AIMS We sought to define the underlying mechanisms for atrial fibrillation (AF) during chronic heart failure (HF). METHODS AND RESULTS Preliminary studies showed that 4 months of HF resulted in irreversible systolic dysfunction (n = 9) and a substrate for sustained inducible AF (>3 months, n = 3). We used a chronic (4-month) canine model of tachypacing-induced HF (n = 10) to assess atrial electrophysiological remodelling, relative to controls (n = 5). Left ventricular fractional shortening was reduced from 37.2 +/- 0.83 to 13.44 +/- 2.63% (P < 0.05). Left atrial (LA) contractility (fractional area change) was reduced from 34.9 +/- 7.9 to 27.9 +/- 4.23% (P < 0.05). Action potential durations (APDs) at 50 and 90% repolarization were shortened by approximately 60 and 40%, respectively, during HF (P < 0.05). HF-induced atrial remodelling included increased fibrosis, increased I(to), and decreased I(K1), I(Kur), and I(Ks) (P < 0.05). HF induced increases in LA Kv channel interacting protein 2 (P < 0.05), no change in Kv4.3, Kv1.5, or Kir2.3, and reduced Kir2.1 (P < 0.05). When I(Ca-L) was elicited by action potential (AP) clamp, HF APs reduced the integral of I(Ca) in control myocytes, with a larger reduction in HF myocytes (P < 0.05). I(CaL) measured with standard voltage clamp was unchanged by HF. Incubation of myocytes with N-acetylcysteine (a glutathione precursor) attenuated HF-induced electrophysiological alterations. LA angiotensin-1 receptor expression was increased in HF. CONCLUSION Chronic HF causes alterations in ion channel expression and ion currents, resulting in attenuation of the APD and atrial contractility and a substrate for persistent AF.
Collapse
Affiliation(s)
- Arun Sridhar
- Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
32
|
Michael G, Xiao L, Qi XY, Dobrev D, Nattel S. Remodelling of cardiac repolarization: how homeostatic responses can lead to arrhythmogenesis. Cardiovasc Res 2008; 81:491-9. [PMID: 18826964 DOI: 10.1093/cvr/cvn266] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Cardiac action potentials (APs) are driven by ionic currents flowing through specific channels and exchangers across cardiomyocyte membranes. Once initiated by rapid Na(+) entry during phase 0, the AP time course is determined by the balance between inward depolarizing currents, carried mainly by Na(+) and Ca(2+), and outward repolarizing currents carried mainly by K(+). K(+) currents play a major role in repolarization. The loss of a K(+) current can impair repolarization, but there is a redundancy of K(+) currents so that when one K(+) current is dysfunctional, other K(+) currents increase to compensate, a phenomenon called 'repolarization reserve'. Repolarization reserve protects repolarization under conditions that increase inward current or reduce outward current, threatening the balance that governs AP duration. This protection comes at the expense of reduced repolarization reserve, potentially resulting in unexpectedly large AP prolongation and arrhythmogenesis, when an additional repolarization-suppressing intervention is superimposed. The critical role of appropriate repolarization is such that cardiac rhythm stability can be impaired with either abnormally slow or excessively rapid repolarization. In cardiac disease states such as heart failure and atrial fibrillation (AF), changes in ion channel properties appear as part of an adaptive response to maintain function in the face of disease-related stress on the cardiovascular system. However, if the stress is maintained the adaptive ion channel changes may themselves lead to dysfunction, in particular cardiac arrhythmias. The present article reviews ionic remodelling of cardiac repolarization, and focuses on how potentially adaptive repolarization changes with congestive heart failure and AF can have arrhythmogenic consequences.
Collapse
Affiliation(s)
- Georghia Michael
- Department of Medicine, Montreal Heart Institute, 5000 Belanger Street East, Montreal, Quebec, Canada H1T 1C8
| | | | | | | | | |
Collapse
|
33
|
Abstract
Atrial fibrillation (AF) is the most common encountered sustained arrhythmia in clinical practice. The last decade the result of large 'rate' versus 'rhythm' control trials have been published that have changed the current day practise of AF treatment. It has become clear that rate control is at least equally effective as a rhythm control strategy in ameliorating morbidity as well as mortality. Moreover, in each individual patient the risk of thromboembolic events should be assessed and antithrombotic treatment be initiated. There have also been great advances in understanding the mechanisms of AF. Experimental studies showed that as a result of electrical and structural remodelling of the atria, 'AF begets AF'. Pharmacological prevention of atrial electrical remodelling has been troublesome, but it seems that blockers of the renin angiotensin system, and perhaps statins, may reduce atrial structural remodelling by preventing atrial fibrosis. Clinical studies demonstrated that the pulmonary veins exhibit foci that can act as initiator and perpetuator of the arrhythmia. Isolation of the pulmonary veins using radiofrequency catheter ablation usually abolishes AF. The most promising advances in the pharmacological treatment of AF include atrial specific antiarrhythmic drugs and direct thrombin inhibitors. In the present review we will describe the results of recent experimental studies, discuss the latest clinical trials, and we will focus on novel treatment modalities.
Collapse
Affiliation(s)
- Y Blaauw
- Department of Cardiology, University Hospital Maastricht, Maastricht, The Netherlands
| | | |
Collapse
|
34
|
Kojodjojo P, Peters NS, Davies DW, Kanagaratnam P. Characterization of the electroanatomical substrate in human atrial fibrillation: the relationship between changes in atrial volume, refractoriness, wavefront propagation velocities, and AF burden. J Cardiovasc Electrophysiol 2007; 18:269-75. [PMID: 17318996 DOI: 10.1111/j.1540-8167.2007.00723.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
INTRODUCTION Progressive remodeling occurs in experimental models of AF whereby slowing of conduction, shortening of refractoriness, and atrial dilatation are associated with an increased vulnerability to atrial fibrillation (AF). This study investigates the relative changes in atrial geometry and electrophysiology with increasing AF burden in humans. METHODS AND RESULTS Patients undergoing ablation of AF or left-sided accessory pathways were recruited. Atrial volumes were determined by echocardiography. Wavefront propagation velocities (WPV), specifically in the direction of activation, were calculated from pre-ablation activation (Carto) maps of both atria. Dispersion, adaptation of, and effective refractoriness (ERP) were measured at 3 sites. A composite arrhythmogenic index (Atrial Volume/WPV x ERP) was derived to compare the degree of electroanatomical remodeling with AF burden. Fifty-nine patients (22 paroxysmal AF, 19 recurrent persistent AF, and 18 controls) were recruited. AF subjects had slower right atrial WPV (P = 0.01), but no difference in left atrial WPV compared with controls. ERP was reduced globally (P < 0.05), with increased dispersion (P < 0.05). WPV and ERP did not distinguish between patients with paroxysmal or persistent AF. Biatrial volumes were greater only in patients with persistent AF (P < 0.01). There was a stepwise increase in the AI with increasing AF burden (P < 0.0001). CONCLUSION An arrhythmogenic substrate exists in human AF, characterized by globally decreased refractoriness with greater dispersion, slower right atrial conduction, and atrial dilatation. Persistence of AF is not accompanied by any further electrical remodeling, but only atrial dilatation. The degree of electroanatomical remodeling is associated with the clinical pattern of AF.
Collapse
Affiliation(s)
- Pipin Kojodjojo
- St. Mary's Hospital, Imperial College, London, United Kingdom
| | | | | | | |
Collapse
|
35
|
Hashimoto N, Yamashita T, Fujikura N, Tsuruzoe N. NIP-141, a multiple ion channel blocker, terminates aconitine-induced atrial fibrillation and prevents the rapid pacing-induced atrial effective refractory period shortening in dogs. ACTA ACUST UNITED AC 2007; 9:246-51. [PMID: 17350982 DOI: 10.1093/europace/eum018] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
AIMS NIP-141 is a novel multiple ion channel blocker with atrial selective effects. In this study, we examined the effects of NIP-141 on aconitine-induced atrial fibrillation (AF) and rapid atrial pacing-induced atrial effective refractory period (ERP) shortening in dogs. METHODS AND RESULTS Aconitine AF was induced by the application of aconitine on the right appendage. NIP-141 (10 mg/kg) converted AF to sinus rhythm in 5 of 6 dogs. The Na(+) channel blockers disopyramide (1 mg/kg) and phenytoin (10 mg/kg) also terminated AF, but the I(Kr) blocker (d-sotalol; 4 mg/kg) and a Ca(2+) channel blocker (verapamil; 0.3 mg/kg) did not terminate AF in this model. To clarify the mechanism of AF termination, we examined the effects on ERP and conduction time, but NIP-141 (10 mg/kg) had no significant effects. In a short-term rapid atrial pacing model, NIP-141 (2.5 mg/kg/10 min, followed by 0.033 mg/kg/min) prevented atrial ERP shortening. We also found NIP-141 bound to Na(+) channel site 2 receptor and L-type Ca(2+) channel, but not to Na(+) channel site 1 receptor using radioligands binding assay. CONCLUSION NIP-141 terminated AF in aconitine-induced AF and prevented the atrial remodelling by short-term rapid pacing in dogs, possibly via the blocking of Na(+) and Ca(2+) channels.
Collapse
Affiliation(s)
- Norio Hashimoto
- Biological Research Laboratories, Nissan Chemical Industries Ltd, 1470 Shiraoka, Minamisaitama, Saitama 349-0294, Japan.
| | | | | | | |
Collapse
|
36
|
da Cunha DNQ, Hamlin RL, Billman GE, Carnes CA. n-3 (omega-3) polyunsaturated fatty acids prevent acute atrial electrophysiological remodeling. Br J Pharmacol 2006; 150:281-5. [PMID: 17179952 PMCID: PMC2013901 DOI: 10.1038/sj.bjp.0706977] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND AND PURPOSE Recent reports suggest that n-3 (omega-3) polyunsaturated fatty acids (PUFAs) may reduce atrial fibrillation (AF). Reduction of the atrial effective refractory period (ERP) is believed to be an important early remodeling event that favors the development and perpetuation of AF. We hypothesized that n-3 PUFAs would attenuate early atrial electrophysiolgical remodeling in a canine model of acute atrial tachypacing. EXPERIMENTAL APPROACH Adult dogs of either sex received n-3 PUFAs (n=6), n-6 PUFAs (n=6), or saline (n=6) infused over 1 h. After a stable ERP was established, treatment was initiated concurrently with 6 h of rapid atrial pacing (400 b.p.m.). Serial right atrial ERPs were measured during rapid atrial pacing, and induction of atrial tachyarrhythmias was attempted at the conclusion of each study. KEY RESULTS There was no change in P wave duration or in the PQ, QRS, QT or QTc intervals in any of the treatment groups. N-3 PUFA treatment significantly reduced the shortening of atrial ERP, compared to both control groups (P<0.05). In separate experiments, the same n-3 PUFA infusion was given to dogs remaining in normal sinus rhythm. During sinus rhythm, n-3 PUFA infusion did not alter any electrocardiogram (ECG) parameter or the atrial ERP. CONCLUSIONS AND IMPLICATIONS We conclude that acute n-3 PUFA treatment prevents acute atrial electrophysiological remodeling during high rate activity, which may minimize the self-perpetuation of AF.
Collapse
Affiliation(s)
- D N Q da Cunha
- Department of Veterinary Biosciences, The Ohio State University Columbus, OH, USA
| | - R L Hamlin
- Department of Veterinary Biosciences, The Ohio State University Columbus, OH, USA
| | - G E Billman
- Department of Physiology and Cell Biology, The Ohio State University Columbus, OH, USA
- Davis Heart and Lung Research Institute, The Ohio State University Columbus, OH, USA
| | - C A Carnes
- College of Pharmacy, The Ohio State University Columbus, OH, USA
- Davis Heart and Lung Research Institute, The Ohio State University Columbus, OH, USA
- Author for correspondence:
| |
Collapse
|
37
|
Opthof T, Den Ruijter HM. Omega-3 polyunsaturated fatty acids (PUFAs or fish oils) and atrial fibrillation. Br J Pharmacol 2006; 150:258-60. [PMID: 17179951 PMCID: PMC2013891 DOI: 10.1038/sj.bjp.0706978] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Affiliation(s)
- T Opthof
- Department of Experimental and Clinical Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
| | | |
Collapse
|
38
|
Childers R. Electrophysiology of the electrocardiographic changes of atrial fibrillation. J Electrocardiol 2006; 39:S174-9. [PMID: 17015065 DOI: 10.1016/j.jelectrocard.2006.05.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2006] [Accepted: 05/31/2006] [Indexed: 10/24/2022]
Abstract
The history of atrial fibrillation is described in terms of its electrocardiographic delineation, characteristics and clinical associations. The variant configurations are described and their relationship to rhythm duration and cardioversion success. The inter-relationship of fibrillation with flutter and their diagnostic differences are reviewed. The electrophysiologic basis of atrial remodeling is exemplified, together with its relationship to failure of rate adaptation of the atrial refractory period. Electric countershock causes an acute abbreviation of the atrial refractory period as does the induction of hyperthyroidism in the experimental animal. Current theories of the mechanism of fibrillation and the issue of originating pulmonary venous foci are reviewed. The lack of protection from ventricular fibrillation that exists with preexcitation via an accessory pathway is discussed in terms of the teleological role of orthograde downstream refractory periods.
Collapse
Affiliation(s)
- Rory Childers
- Section of Cardiology, Department of Medicine, University of Chicago, Chicago, Illinois 60637, USA.
| |
Collapse
|
39
|
Bollmann A, Husser D, Mainardi L, Lombardi F, Langley P, Murray A, Rieta JJ, Millet J, Olsson SB, Stridh M, Sörnmo L. Analysis of surface electrocardiograms in atrial fibrillation: techniques, research, and clinical applications. ACTA ACUST UNITED AC 2006; 8:911-26. [PMID: 17043067 DOI: 10.1093/europace/eul113] [Citation(s) in RCA: 140] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Atrial fibrillation (AF) is the most common arrhythmia encountered in clinical practice. Neither the natural history of AF nor its response to therapy is sufficiently predictable by clinical and echocardiographic parameters. The purpose of this article is to describe technical aspects of novel electrocardiogram (ECG) analysis techniques and to present research and clinical applications of these methods for characterization of both the fibrillatory process and the ventricular response during AF. Atrial fibrillatory frequency (or rate) can reliably be assessed from the surface ECG using digital signal processing (extraction of atrial signals and spectral analysis). This measurement shows large inter-individual variability and correlates well with intra-atrial cycle length, a parameter which appears to have primary importance in AF maintenance and response to therapy. AF with a low fibrillatory rate is more likely to terminate spontaneously and responds better to antiarrhythmic drugs or cardioversion, whereas high-rate AF is more often persistent and refractory to therapy. Ventricular responses during AF can be characterized by a variety of methods, which include analysis of heart rate variability, RR-interval histograms, Lorenz plots, and non-linear dynamics. These methods have all shown a certain degree of usefulness, either in scientific explorations of atrioventricular (AV) nodal function or in selected clinical questions such as predicting response to drugs, cardioversion, or AV nodal modification. The role of the autonomic nervous system for AF sustenance and termination, as well as for ventricular rate responses, can be explored by different ECG analysis methods. In conclusion, non-invasive characterization of atrial fibrillatory activity and ventricular response can be performed from the surface ECG in AF patients. Different signal processing techniques have been suggested for identification of underlying AF pathomechanisms and prediction of therapy efficacy.
Collapse
Affiliation(s)
- Andreas Bollmann
- Department of Cardiology, Otto-von-Guericke-University Magdeburg, Leipziger Str. 44, 39120 Magdeburg, Germany.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
40
|
Childers R. Teaching electrocardiogram interpretation. J Electrocardiol 2006; 39:426-9. [PMID: 16895774 DOI: 10.1016/j.jelectrocard.2006.01.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2005] [Accepted: 01/19/2006] [Indexed: 11/28/2022]
|
41
|
Holmqvist F, Stridh M, Waktare JEP, Sörnmo L, Roijer A, Meurling CJ. Indices of Electrical and Contractile Remodeling During Atrial Fibrillation in Man. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2006; 29:512-9. [PMID: 16689848 DOI: 10.1111/j.1540-8159.2006.00386.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND Atrial electrical and contractile remodeling have been demonstrated to coincide during atrial fibrillation (AF) in experimental studies. We explored whether electrical and contractile remodeling correlate in man and explored its clinical implications. METHODS Forty-nine patients with persistent AF were studied. Electrical remodeling was assessed noninvasively using spectral analysis to estimate the average fibrillatory rate (AFR). Atrial contractility was assessed by transesophageal echocardiography (TEE) measurement of left atrial appendage outflow velocity (LAAOV). RESULTS The AFR was 403+/-43 fibrillations per minute (fpm) and the LAAOV was 0.27+/-0.14 m/s. A significant correlation was found between AFR and LAAOV (r=-0.47, P=0.001). In patients with a LAAOV>or=0.25 m/s, the AFR was 387+/-48 fpm compared to 419+/-31 fpm among patients with LAAOV<0.25 m/s (P<0.01). CONCLUSIONS This study demonstrates that indices of electrical and contractile remodeling are strongly correlated in persistent AF in man. The interindividual overlap, however, is too large to allow predictions of LAAOV based on fibrillatory frequency alone.
Collapse
|
42
|
Brembilla-Perrot B, Beurrier D, Houriez P, Suty-Selton C, Nippert M, Claudon O, Andronache M, Ernst Y, Khaldi E, Belhakem H, Popovic B, Terrier de la Chaise A, Louis P. Electrophysiologic characteristics of atria in patients without heart disease. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2006; 28:1066-72. [PMID: 16221265 DOI: 10.1111/j.1540-8159.2005.00240.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND The significance of atrial fibrillation or tachycardia (AF) induction remains debatable. Some believe that the presence of heart disease (HD) increases the sensitivity and decreases the specificity of programmed atrial stimulation (PAS). There are few data in patients without HD. The purpose of the study was to evaluate the results of PAS in asymptomatic patients without HD and in those with documented spontaneous AF, but without HD, to know the diagnosis value of the technique. METHODS A total of 4,900 PAS were consecutively performed. The control group (I, N=67) was defined by the absence of preexcitation syndrome, dizziness/syncope, hypertension, history of tachycardia, or other documented HD together with a normal 2D echocardiogram and 24-hour Holter monitoring. They were compared to a group (II) of 54 patients with documented paroxysmal AF and without HD. PAS used one and two extrastimuli, delivered during sinus rhythm and two drive rates (600, 400 ms). Atrial-effective refractory periods (ARP), their adaptation to cycle length, and conduction times were noted. AF induction was defined as the induction of AF lasting more than 1 minute. RESULTS Group I patients (1.4% of 4,900) were younger than group II (51 +/- 17 vs 65 +/- 11 years, P < 0.001). A single extrastimulus never induced sustained AF in group I, but did so in 11 group II patients (20%); sustained AF was induced by two extrastimuli in 15 group I patients (22%) and in 31 group II patients (57%) (P < 0.001). There were no ARP and conduction time differences in group I patients with and without inducible AF, but there was a longer sinus cycle length in patients with inducible AF (977 +/- 164 vs 838 +/- 141 ms, P < 0.02). There were no electrophysiological differences in group II patients with and without inducible AF. No group I patient developed spontaneous AF (follow-up 4 +/- 2 years). The sensitivity of PAS with one extrastimulus was 20% and the specificity 100%; the sensitivity of PAS with two extrastimuli was 57% and the specificity 78%. CONCLUSION Sustained AF was not induced by one extrastimulus in control patients without symptoms, nor heart disease, but sustained AF was induced by two extrastimuli in 22% of these patients. The induction of a sustained AF by two extrastimuli should be interpreted cautiously, particularly in patients with a relative sinus bradycardia. However, the sensitivity of PAS with one extrastimulus was very low and two extrastimuli were required in patients with spontaneous AF to induce the tachycardia. Other electrophysiological parameters were not useful to differentiate patients with and without inducible AF.
Collapse
|
43
|
Meurling CJ, Roijer A, Waktare JEP, Holmqvist F, Lindholm CJ, Ingemansson MP, Carlson J, Stridh M, Sörnmo L, Olsson SB. Prediction of sinus rhythm maintenance following DC-cardioversion of persistent atrial fibrillation - the role of atrial cycle length. BMC Cardiovasc Disord 2006; 6:11. [PMID: 16533393 PMCID: PMC1431563 DOI: 10.1186/1471-2261-6-11] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2005] [Accepted: 03/13/2006] [Indexed: 11/12/2022] Open
Abstract
Background Atrial electrical remodeling has been shown to influence the outcome the outcome following cardioversion of atrial fibrillation (AF) in experimental studies. The aim of the present study was to find out whether a non-invasively measured atrial fibrillatory cycle length, alone or in combination with other non-invasive parameters, could predict sinus rhythm maintenance after cardioversion of AF. Methods Dominant atrial cycle length (DACL), a previously validated non-invasive index of atrial refractoriness, was measured from lead V1 and a unipolar oesophageal lead prior to cardioversion in 37 patients with persistent AF undergoing their first cardioversion. Results 32 patients were successfully cardioverted to sinus rhythm. The mean DACL in the 22 patients who suffered recurrence of AF within 6 weeks was 152 ± 15 ms (V1) and 147 ± 14 ms (oesophagus) compared to 155 ± 17 ms (V1) and 151 ± 18 ms (oesophagus) in those maintaining sinus rhythm (NS). Left atrial diameter was 48 ± 4 mm and 44 ± 7 mm respectively (NS). The optimal parameter predicting maintenance of sinus rhythm after 6 weeks appeared to be the ratio of the lowest dominant atrial cycle length (oesophageal lead or V1) to left atrial diameter. This ratio was significantly higher in patients remaining in sinus rhythm (3.4 ± 0.6 vs. 3.1 ± 0.4 ms/mm respectively, p = 0.04). Conclusion In this study neither an index of atrial refractory period nor left atrial diameter alone were predictors of AF recurrence within the 6 weeks of follow-up. The ratio of the two (combining electrophysiological and anatomical measurements) only slightly improve the identification of patients at high risk of recurrence of persistent AF. Consequently, other ways to asses electrical remodeling and / or other variables besides electrical remodeling are involved in determining the outcome following cardioversion.
Collapse
Affiliation(s)
- Carl J Meurling
- Department of Cardiology, Lund University Hospital, SE-221 85 Lund, Sweden
| | - Anders Roijer
- Department of Cardiology, Lund University Hospital, SE-221 85 Lund, Sweden
| | | | - Fredrik Holmqvist
- Department of Cardiology, Lund University Hospital, SE-221 85 Lund, Sweden
| | - Carl J Lindholm
- Department of Cardiology, Lund University Hospital, SE-221 85 Lund, Sweden
| | - Max P Ingemansson
- Department of Cardiology, Lund University Hospital, SE-221 85 Lund, Sweden
| | - Jonas Carlson
- Department of Cardiology, Lund University Hospital, SE-221 85 Lund, Sweden
| | - Martin Stridh
- Department of Applied Electronics, Lund Institute of Technology, Lund, Sweden
| | - Leif Sörnmo
- Department of Applied Electronics, Lund Institute of Technology, Lund, Sweden
| | - S Bertil Olsson
- Department of Cardiology, Lund University Hospital, SE-221 85 Lund, Sweden
| |
Collapse
|
44
|
Burashnikov A, Antzelevitch C. Role of repolarization restitution in the development of coarse and fine atrial fibrillation in the isolated canine right atria. J Cardiovasc Electrophysiol 2005; 16:639-45. [PMID: 15946365 PMCID: PMC1479890 DOI: 10.1046/j.1540-8167.2005.40689.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
INTRODUCTION Although the role of action potential duration restitution (APD-R) in the initiation and maintenance of ventricular fibrillation (VF) has been the subject of numerous investigations, its role in the generation of atrial fibrillation (AF) is less well studied. The cellular and ionic basis for coarse versus fine AF is not well delineated. METHODS AND RESULTS We measured APD-R during acetylcholine-mediated AF as well as during pacing (standard and dynamic protocols) in crista teriminalis, pectinate muscle, superior vena cava, and appendage of isolated canine arterially perfused right atria (n = 15). Transmembrane action potential (TAP), pseudo-ECG, and isometric tension development were simultaneously recorded. Acetylcholine flattened APD-R measured by both standard and dynamic protocols, but promoted induction of AF. AF was initially coarse, converting to fine within 3-15 minutes of AF. Coarse, but not fine AF was associated with dramatic fluctuations in tension development, reflecting wide variations in intracellular calcium activity ([Ca(2+)](i)). During coarse AF, APD-R data displayed a cloud-like distribution pattern, with a wide range of maximum APD-R slope (from 1.21 to 0.35). A maximum APD-R slope >1 was observed only in crista terminalis (3/10). The APD-R relationship was relatively linear and flat during fine AF. Reduction of [Ca(2+)](i) was associated with fine AF whereas augmentation of [Ca(2+)](i) with coarse AF. CONCLUSIONS Our data indicate that while APD-R may have a limited role in the maintenance of coarse AF, it is unlikely to contribute to the maintenance of fine AF and that [Ca(2+)](i) dynamics determine the degree to which AF is coarse or fine.
Collapse
|
45
|
Schoonderwoerd BA, Van Gelder IC, Van Veldhuisen DJ, Van den Berg MP, Crijns HJGM. Electrical and Structural Remodeling: Role in the Genesis and Maintenance of Atrial Fibrillation. Prog Cardiovasc Dis 2005; 48:153-68. [PMID: 16271942 DOI: 10.1016/j.pcad.2005.06.014] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Atrial fibrillation (AF) and congestive heart failure (CHF) are 2 frequently encountered conditions in clinical practice. Both lead to changes in atrial function and structure, an array of processes known as atrial remodeling. This review provides an overview of ionic, electrical, contractile, neurohumoral, and structural atrial changes responsible for initiation and maintenance of AF. In the last decade, many studies have evaluated atrial remodeling due to AF or CHF. Both conditions often coexist, which makes it difficult to distinguish the contribution of each. Because of atrial stretch in the setting of hypertension or CHF, atrial remodeling frequently occurs long before AF arises. Alternatively, AF may lead to electrical remodeling, that is, shortening of refractoriness due to the high atrial rate itself. In many experimental AF or rapid atrial pacing studies, the ventricular rate was uncontrolled. In those studies, atrial stretch due to CHF may have interfered with the high atrial rate to produce a mixed type of electrical and structural remodeling. Other studies have dissected the individual role of AF or atrial tachycardia from the role CHF plays in atrial remodeling. Atrial fibrillation itself does not lead to structural remodeling, whereas this is frequently produced by hypertension or CHF, even in the absence of AF. Primary and secondary prevention programs should tailor treatment to the various types of remodeling.
Collapse
Affiliation(s)
- Bas A Schoonderwoerd
- Department of Cardiology, Thoraxcenter, University Medical Center Groningen, University of Groningen, RB Groningen, The Netherlands.
| | | | | | | | | |
Collapse
|
46
|
Jayam VK, Dong J, Vasamreddy CR, Lickfett L, Kato R, Dickfeld T, Eldadah Z, Dalal D, Blumke DA, Berger R, Halperin HR, Calkins H. Atrial Volume Reduction Following Catheter Ablation of Atrial Fibrillation and Relation to Reduction in Pulmonary Vein Size: An Evaluation Using Magnetic Resonance Angiography. J Interv Card Electrophysiol 2005; 13:107-14. [PMID: 16133837 DOI: 10.1007/s10840-005-0215-3] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2004] [Accepted: 04/14/2005] [Indexed: 11/30/2022]
Abstract
INTRODUCTION Catheter ablation to achieve pulmonary vein (PV) isolation has become an increasingly used treatment strategy for patients with atrial fibrillation (AF). The purpose of this study was to evaluate the impact of segmental isolation of PVs on volume of left atrium and its relation to the decrease in the size of the pulmonary veins. METHODS Gadolinium enhanced Magnetic Resonance Angiography (MRA) was performed in 51 AF patients before and 6 approximately 8 weeks post PV isolation, using cooled radio-frequency (RF) energy. Three-dimensional reconstruction with maximum intensity projections and multiplanar reformations was performed. Oblique coronal projections were used to measure the ostial size of PVs. Three orthogonal dimensions of LA chamber were measured and computed to assess the volume of the left atrium. RESULTS The mean LA volume decreased by 15.7% after ablation (p<0.001). The mean PV ostial diameter decreased by 11%, from 18.3+/-0.8 mm to 16.7+/-1.0 mm (p=0.005). Moderate PV stenosis was noted in two veins out of the 192 veins analyzed. There was a significant correlation between changes in the size of PV ostium to that of the LA. CONCLUSIONS Catheter ablation of AF using a segmental PV isolation approach results in a significant reverse remodeling in the left atrium. Significant stenosis of PVs appears to be rare after the segmental isolation procedure.
Collapse
Affiliation(s)
- Vinod K Jayam
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21287-0409, USA
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
47
|
Chandra P, Rosen TS, Herweg B, Plotnikov AN, Danilo P, Rosen MR. Atrial gradient as a potential predictor of atrial fibrillation. Heart Rhythm 2005; 2:404-10. [PMID: 15851344 DOI: 10.1016/j.hrthm.2004.12.027] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2004] [Accepted: 12/29/2004] [Indexed: 10/25/2022]
Abstract
OBJECTIVES We tested the utility and comparability of the atrial gradient and atrial ERP as early markers of electrical remodeling and a propensity to atrial fibrillation (AF). BACKGROUND Pacing at physiologic rates from the left atrium alters the atrial gradient and is associated with atrial tachyarrhythmias. At these physiologic rates, there is no change in the atrial effective refractory period (ERP). METHODS Sixty-one chronically instrumented mongrel dogs in complete heart block were paced from the left or right atrium at 400 to 900 bpm for 46 +/- 3 days. Dogs were monitored weekly and electrophysiologic studies conducted to determine changes in the atrial gradient, ERP, and rhythm. RESULTS Rapid atrial pacing was associated with concordant decreases in atrial gradient, ERP, and occurrence of AF. Incidence of AF increased with increasing pacing rate. Although there ultimately was an equal incidence of AF with left atrial and right atrial pacing, the onset of AF occurred earlier with left atrial pacing. As expected, ERP decreased in both atria. Animals with long control ERP did not fibrillate. CONCLUSIONS Rapid pacing induces changes in atrial gradient, which can be used as a noninvasive marker of electrical remodeling. AF is accompanied by decreases in atrial gradient and ERP, and the incidence is highest in dogs with short control ERP.
Collapse
Affiliation(s)
- Parag Chandra
- Department of Pharmacology, College of Physicians and Surgeons of Columbia University, New York, New York 10032, USA
| | | | | | | | | | | |
Collapse
|
48
|
Saksena S, Skadsberg ND, Rao HB, Filipecki A. Biatrial and Three-Dimensional Mapping of Spontaneous Atrial Arrhythmias in Patients with Refractory Atrial Fibrillation. J Cardiovasc Electrophysiol 2005; 16:494-504. [PMID: 15877620 DOI: 10.1111/j.1540-8167.2005.40531.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
INTRODUCTION While atrial fibrillation (AF) initiation in the pulmonary veins has been well-studied, simultaneous biatrial and three-dimensional noncontact mapping (NCM) has not been performed. We hypothesized that these two techniques would provide novel information on triggers, initiation, and evolution of spontaneous AF and permit study of different AF populations. METHODS AND RESULTS The origin of atrial premature beats (APBs), onset of spontaneous AF and its evolution were analyzed in 50 patients with AF in the presence or absence of structural heart disease (SHD) and in different AF presentations (group A: Persistent, group B: Paroxysmal). In 45 patients, spontaneous APBs in the right atrium (RA; n = 60) and left atrium (LA; n = 25) with similar regional distributions regardless of heart disease status were demonstrated. In total, 22 patients (44%) had > or =2 disparate regional origins. Biatrial regional foci were seen with equal frequency in patients with SHD (31%), without SHD (40%), in group A (32%), and in group B (36%). Biatrial mapping and NCM showed organized monomorphic atrial tachyarrhythmias arising in the RA (17), septum (17), or LA (21) and were classified as atrial flutter (RA = 34, LA = 8), macro-reentrant atrial tachycardia (RA = 1, LA = 3) or focal atrial tachycardia (RA = 2, LA = 7). Their regional distribution was more extensive in patients with SHD and persistent AF compared with patients without SHD or paroxysmal AF. Simultaneous biatrial tachycardias were observed only in group A patients and those with SHD. CONCLUSIONS Simultaneous biatrial and NCM permits successful AF mapping in different AF populations and demonstrates a biatrial spectrum of spontaneous triggers and tachycardias. Organized monomorphic tachycardias with multiple unilateral or biatrial locations are commonly observed in human AF. Patients with heart disease or persistent AF have a more extensive distribution as well as simultaneous coexistence of multiple tachycardias during AF.
Collapse
Affiliation(s)
- Sanjeev Saksena
- Electrophysiology Research Foundation, Warren, New Jersey, USA
| | | | | | | |
Collapse
|
49
|
Opthof T. Prediction of atrial fibrillation: Role of the atrial gradient. Heart Rhythm 2005; 2:411-2. [PMID: 15851345 DOI: 10.1016/j.hrthm.2005.01.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- Tobias Opthof
- Experimental and Molecular Cardiology Groups, Academic Medical Center, Amsterdam, The Netherlands and Department of Medical Physiology, University Medical Center Utrecht, Utrecht, The Netherlands.
| |
Collapse
|
50
|
Tieleman RG, Van Gelder IC, Bosker HA, Kingma T, Wilde AAM, Kirchhof CJHJ, Bennekers JH, Bracke FALE, Veeger NJGM, Haaksma J, Allessie MA, Crijns HJGM. Does flecainide regain its antiarrhythmic activity after electrical cardioversion of persistent atrial fibrillation? Heart Rhythm 2005; 2:223-30. [PMID: 15851308 DOI: 10.1016/j.hrthm.2004.11.014] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2004] [Accepted: 11/11/2004] [Indexed: 10/25/2022]
Abstract
OBJECTIVES The purpose of this study was to evaluate the hypothesis that presumed reversion of electrical remodeling after cardioversion of atrial fibrillation (AF) restores the efficacy of flecainide. BACKGROUND Flecainide loses its efficacy to cardiovert when AF has been present for more than 24 hours. Most probably, the loss is caused by atrial electrical remodeling. Studies suggest electrical remodeling is completely reversible within 4 days after restoration of sinus rhythm (SR). METHODS One hundred eighty-one patients with persistent AF (median duration 3 months) were included in this prospective study. After failure of pharmacologic cardioversion by flecainide 2 mg/kg IV (maximum 150 mg in 10 minutes) and subsequent successful electrical cardioversion, we performed intense transtelephonic rhythm monitoring three times daily for 1 month. In case of AF recurrence, a second cardioversion by flecainide was attempted as soon as possible. RESULTS AF recurred in 123 patients (68%). Successful cardioversion by flecainide occurred only when SR had been maintained for more than 4 days (7/51 patients [14%]). Failure to cardiovert was associated with a prolonged duration of the recurrent AF episode and concurrent digoxin use. Multivariate logistic regression confirmed that successful cardioversion was determined by digoxin use (odds ratio [OR] 0.093, P = .047) and by the interaction between the duration of SR and the (inverse) duration of recurrent AF (OR 6.499, P < .001). When flecainide was administered within 10 hours after AF onset and the duration of SR was greater than 4 days, the success rate was 58%. CONCLUSIONS Flecainide recovers its antiarrhythmic action after cardioversion of AF. However, successful pharmacologic cardioversion occurs only after SR has lasted at least 4 days and is expected only for recurrences having duration of a few hours. Immediate pharmacologic cardioversion of AF recurrence may be a worthwhile strategy for management of persistent AF.
Collapse
|