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Zaman JAB, Grace AA, Narayan SM. Future Directions for Mapping Atrial Fibrillation. Arrhythm Electrophysiol Rev 2022; 11:e08. [PMID: 35734143 PMCID: PMC9194915 DOI: 10.15420/aer.2021.52] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Accepted: 11/08/2021] [Indexed: 01/14/2023] Open
Abstract
Mapping for AF focuses on the identification of regions of interest that may guide management and - in particular - ablation therapy. Mapping may point to specific mechanisms associated with localised scar or fibrosis, or electrical features, such as localised repetitive, rotational or focal activation. In patients in whom AF is caused by disorganised waves with no spatial predilection, as proposed in the multiwavelet theory for AF, mapping would be of less benefit. The role of AF mapping is controversial at the current time in view of the debate over the underlying mechanisms. However, recent clinical expansions of mapping technologies confirm the importance of understanding the state of the art, including limitations of current approaches and potential areas of future development.
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Affiliation(s)
- Junaid AB Zaman
- Keck School of Medicine, University of Southern California, Los Angeles, CA, US
| | - Andrew A Grace
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Sanjiv M Narayan
- Cardiovascular Institute and Department of Medicine, Stanford University, CA, US
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Reddy SA, Calvert PA, D'Errico L, Williams L, Grace AA. 28 days later: a traumatic pacing indication and the role of cardiac imaging as the pathologist. Eur Heart J Cardiovasc Imaging 2021; 22:e75. [PMID: 33164052 DOI: 10.1093/ehjci/jeaa283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
| | - Patrick A Calvert
- Royal Papworth Hospital, Cambridge Biomedical Campus, Cambridge CB2 0AY, UK
| | - Luigia D'Errico
- Royal Papworth Hospital, Cambridge Biomedical Campus, Cambridge CB2 0AY, UK
| | - Lynne Williams
- Royal Papworth Hospital, Cambridge Biomedical Campus, Cambridge CB2 0AY, UK
| | - Andrew A Grace
- Royal Papworth Hospital, Cambridge Biomedical Campus, Cambridge CB2 0AY, UK
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Reddy SA, Nethercott SL, Khialani BV, Grace AA, Martin CA. Management of arrhythmias in pulmonary hypertension. J Interv Card Electrophysiol 2021; 62:219-229. [DOI: 10.1007/s10840-021-00988-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Accepted: 03/28/2021] [Indexed: 12/24/2022]
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Abstract
Adenosine was identified in 1929 and immediately recognised as having a potential role in therapy for arrhythmia because of its negative chronotropic and dromotropic effects. Adenosine entered mainstream use in the 1980s as a highly effective agent for the termination of supraventricular tachycardia (SVT) involving the atrioventricular node, as well as for its ability to unmask the underlying rhythm in other SVTs. Adenosine has subsequently been found to have applications in interventional electrophysiology. While considered a safe agent because of its short half-life, adenosine may provoke arrhythmias in the form of AF, bradyarrhythmia and ventricular tachyarrhythmia. Adenosine is also associated with bronchospasm, although this may reflect irritant-induced dyspnoea rather than true obstruction. Adenosine is linked to numerous pathologies relevant to arrhythmia predisposition, including heart failure, obesity, ischaemia and the ageing process itself. This article examines 90 years of experience with adenosine in the light of new European Society of Cardiology guidelines for the management of SVT.
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Affiliation(s)
- Gareth DK Matthews
- Cambridge University NHS Foundation Trust, Cambridge, UK; Royal Papworth Hospital NHS Foundation Trust, Cambridge, UK
| | - Andrew A Grace
- Royal Papworth Hospital NHS Foundation Trust, Cambridge, UK; Department of Biochemistry, University of Cambridge, Cambridge, UK
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Bhar-Amato J, Finlay M, Santos D, Orini M, Chaubey S, Vyas V, Taggart P, Grace AA, Huang CLH, Ben Simon R, Tinker A, Lambiase PD. Pharmacological Modulation of Right Ventricular Endocardial-Epicardial Gradients in Brugada Syndrome. Circ Arrhythm Electrophysiol 2019; 11:e006330. [PMID: 30354290 DOI: 10.1161/circep.118.006330] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background We explored the hypothesis that increased cholinergic tone exerts its proarrhythmic effects in Brugada syndrome (BrS) through increasing dispersion of transmural repolarization in patients with spontaneous and drug-induced BrS. Methods BrS and supraventricular tachycardia patients were studied after deploying an Ensite Array in the right ventricular outflow tract and a Cardima catheter in the great cardiac vein to record endo and epicardial signals, respectively. S1-S2 restitution curves from the right ventricular apex were conducted at baseline and after edrophonium challenge to promote increased cholinergic tone. The local unipolar electrograms were then analyzed to study transmural conduction and repolarization dynamics. Results The study included 8 BrS patients (5 men:3 women; mean age, 56 years) and 8 controls patients with supraventricular tachycardia (5 men:3 women; mean age, 48 years). Electrophysiological studies in controls demonstrated shorter endocardial than epicardial right ventricular activation times (mean difference: 26 ms; P<0.001). In contrast, patients with BrS showed longer endocardial than epicardial activation time (mean difference: -15 ms; P=0.001). BrS hearts, compared with controls, showed significantly larger transmural gradients in their activation recovery intervals (mean intervals, 20.5 versus 3.5 ms; P<0.01), with longer endocardial than epicardial activation recovery intervals. Edrophonium challenge increased such gradients in both controls (to a mean of 16 ms [ P<0.001]) and BrS (to 29.7 ms; P<0.001). However, these were attributable to epicardial and endocardial activation recovery interval prolongations in control and BrS hearts, respectively. Dynamic changes in repolarization gradients were also observed across the BrS right ventricular wall in BrS. Conclusions Differential contributions of conduction and repolarization were identified in BrS which critically modulated transmural dispersion of repolarization with significant cholinergic effects only identified in the patients with BrS. This has important implications for explaining the proarrhythmic effects of increased vagal tone in BrS, as well as evaluating autonomic modulation and epicardial ablation as therapeutic strategies.
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Affiliation(s)
- Justine Bhar-Amato
- University College London, United Kingdom (J.B.-A., D.S., M.O., P.T., P.D.L.)
| | - Malcolm Finlay
- Barts Heart Centre, London, United Kingdom (M.F., V.V., R.B.S., P.D.L.).,Queen Mary's College London, United Kingdom (M.F., A.T.)
| | - Diogo Santos
- University College London, United Kingdom (J.B.-A., D.S., M.O., P.T., P.D.L.)
| | - Michele Orini
- University College London, United Kingdom (J.B.-A., D.S., M.O., P.T., P.D.L.)
| | | | - Vishal Vyas
- Barts Heart Centre, London, United Kingdom (M.F., V.V., R.B.S., P.D.L.)
| | - Peter Taggart
- University College London, United Kingdom (J.B.-A., D.S., M.O., P.T., P.D.L.)
| | - Andrew A Grace
- Cambridge University, United Kingdom (A.A.G., C.L.-H.H.)
| | | | - Ron Ben Simon
- University College London, United Kingdom (J.B.-A., D.S., M.O., P.T., P.D.L.).,Barts Heart Centre, London, United Kingdom (M.F., V.V., R.B.S., P.D.L.)
| | - Andrew Tinker
- Queen Mary's College London, United Kingdom (M.F., A.T.)
| | - Pier D Lambiase
- University College London, United Kingdom (J.B.-A., D.S., M.O., P.T., P.D.L.).,Barts Heart Centre, London, United Kingdom (M.F., V.V., R.B.S., P.D.L.)
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6
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Finlay M, Bhar-Amato J, Ng KE, Santos D, Orini M, Vyas V, Taggart P, Grace AA, Huang CLH, Lambiase PD, Tinker A. Autonomic modulation of the electrical substrate in mice haploinsufficient for cardiac sodium channels: a model of the Brugada syndrome. Am J Physiol Cell Physiol 2019; 317:C576-C583. [PMID: 31291141 DOI: 10.1152/ajpcell.00028.2019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
A murine line haploinsufficient in the cardiac sodium channel has been used to model human Brugada syndrome: a disease causing sudden cardiac death due to lethal ventricular arrhythmias. We explored the effects of cholinergic tone on electrophysiological parameters in wild-type and genetically modified, heterozygous, Scn5a+/- knockout mice. Scn5a+/- ventricular slices showed longer refractory periods than wild-type both at baseline and during isoprenaline challenge. Scn5a+/- hearts also showed lower conduction velocities and increased mean increase in delay than did littermate controls at baseline and blunted responses to isoprenaline challenge. Carbachol exerted limited effects but reversed the effects of isoprenaline with coapplication. Scn5a+/- mice showed a reduction in conduction reserve in that isoprenaline no longer increased conduction velocity, and this was not antagonized by muscarinic agonists.
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Affiliation(s)
- Malcolm Finlay
- William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom
| | - Justine Bhar-Amato
- Institute of Cardiovascular Science, University College London, London, United Kingdom
| | - Keat-Eng Ng
- William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom
| | - Diogo Santos
- Institute of Cardiovascular Science, University College London, London, United Kingdom
| | - Michele Orini
- Institute of Cardiovascular Science, University College London, London, United Kingdom
| | - Vishal Vyas
- William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom
| | - Peter Taggart
- Institute of Cardiovascular Science, University College London, London, United Kingdom
| | - Andrew A Grace
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Christopher L-H Huang
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom
| | - Pier D Lambiase
- Institute of Cardiovascular Science, University College London, London, United Kingdom
| | - Andrew Tinker
- William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom
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Dorn T, Kornherr J, Parrotta EI, Zawada D, Ayetey H, Santamaria G, Iop L, Mastantuono E, Sinnecker D, Goedel A, Dirschinger RJ, My I, Laue S, Bozoglu T, Baarlink C, Ziegler T, Graf E, Hinkel R, Cuda G, Kääb S, Grace AA, Grosse R, Kupatt C, Meitinger T, Smith AG, Laugwitz KL, Moretti A. Interplay of cell-cell contacts and RhoA/MRTF-A signaling regulates cardiomyocyte identity. EMBO J 2018; 37:e98133. [PMID: 29764980 PMCID: PMC6003642 DOI: 10.15252/embj.201798133] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Revised: 03/29/2018] [Accepted: 04/04/2018] [Indexed: 12/13/2022] Open
Abstract
Cell-cell and cell-matrix interactions guide organ development and homeostasis by controlling lineage specification and maintenance, but the underlying molecular principles are largely unknown. Here, we show that in human developing cardiomyocytes cell-cell contacts at the intercalated disk connect to remodeling of the actin cytoskeleton by regulating the RhoA-ROCK signaling to maintain an active MRTF/SRF transcriptional program essential for cardiomyocyte identity. Genetic perturbation of this mechanosensory pathway activates an ectopic fat gene program during cardiomyocyte differentiation, which ultimately primes the cells to switch to the brown/beige adipocyte lineage in response to adipogenesis-inducing signals. We also demonstrate by in vivo fate mapping and clonal analysis of cardiac progenitors that cardiac fat and a subset of cardiac muscle arise from a common precursor expressing Isl1 and Wt1 during heart development, suggesting related mechanisms of determination between the two lineages.
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Affiliation(s)
- Tatjana Dorn
- Klinik und Poliklinik Innere Medizin I, Klinikum rechts der Isar - Technical University of Munich, Munich, Germany
| | - Jessica Kornherr
- Klinik und Poliklinik Innere Medizin I, Klinikum rechts der Isar - Technical University of Munich, Munich, Germany
| | - Elvira I Parrotta
- Klinik und Poliklinik Innere Medizin I, Klinikum rechts der Isar - Technical University of Munich, Munich, Germany
- Department of Experimental and Clinical Medicine, Medical School, University of Magna Grecia, Catanzaro, Italy
| | - Dorota Zawada
- Klinik und Poliklinik Innere Medizin I, Klinikum rechts der Isar - Technical University of Munich, Munich, Germany
| | - Harold Ayetey
- Wellcome Trust - Medical Research Council Stem Cell Institute, University of Cambridge, Cambridge, UK
- Papworth Hospital NHS Foundation Trust, Cambridge, UK
| | - Gianluca Santamaria
- Department of Experimental and Clinical Medicine, Medical School, University of Magna Grecia, Catanzaro, Italy
| | - Laura Iop
- Klinik und Poliklinik Innere Medizin I, Klinikum rechts der Isar - Technical University of Munich, Munich, Germany
| | - Elisa Mastantuono
- Institute of Human Genetics, Klinikum rechts der Isar - Technical University of Munich, Munich, Germany
| | - Daniel Sinnecker
- Klinik und Poliklinik Innere Medizin I, Klinikum rechts der Isar - Technical University of Munich, Munich, Germany
- DZHK (German Centre for Cardiovascular Research) - partner site Munich Heart Alliance, Munich, Germany
| | - Alexander Goedel
- Klinik und Poliklinik Innere Medizin I, Klinikum rechts der Isar - Technical University of Munich, Munich, Germany
- DZHK (German Centre for Cardiovascular Research) - partner site Munich Heart Alliance, Munich, Germany
| | - Ralf J Dirschinger
- Klinik und Poliklinik Innere Medizin I, Klinikum rechts der Isar - Technical University of Munich, Munich, Germany
| | - Ilaria My
- Klinik und Poliklinik Innere Medizin I, Klinikum rechts der Isar - Technical University of Munich, Munich, Germany
| | - Svenja Laue
- Klinik und Poliklinik Innere Medizin I, Klinikum rechts der Isar - Technical University of Munich, Munich, Germany
| | - Tarik Bozoglu
- Klinik und Poliklinik Innere Medizin I, Klinikum rechts der Isar - Technical University of Munich, Munich, Germany
| | | | - Tilman Ziegler
- Klinik und Poliklinik Innere Medizin I, Klinikum rechts der Isar - Technical University of Munich, Munich, Germany
| | - Elisabeth Graf
- Institute of Human Genetics, Klinikum rechts der Isar - Technical University of Munich, Munich, Germany
| | - Rabea Hinkel
- Klinik und Poliklinik Innere Medizin I, Klinikum rechts der Isar - Technical University of Munich, Munich, Germany
- DZHK (German Centre for Cardiovascular Research) - partner site Munich Heart Alliance, Munich, Germany
- IPEK Institute for Cardiovascular Prevention, Klinikum der Universität München - Ludwig-Maximillians-Universität, Munich, Germany
| | - Giovanni Cuda
- Department of Experimental and Clinical Medicine, Medical School, University of Magna Grecia, Catanzaro, Italy
| | - Stefan Kääb
- Medizinische Klinik und Poliklinik I, Klinikum der Universität München - Ludwig-Maximillians-Universität, Munich, Germany
| | - Andrew A Grace
- Papworth Hospital NHS Foundation Trust, Cambridge, UK
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Robert Grosse
- Pharmacology Institute, Philipps University Marburg, Marburg, Germany
| | - Christian Kupatt
- Klinik und Poliklinik Innere Medizin I, Klinikum rechts der Isar - Technical University of Munich, Munich, Germany
- DZHK (German Centre for Cardiovascular Research) - partner site Munich Heart Alliance, Munich, Germany
| | - Thomas Meitinger
- Institute of Human Genetics, Klinikum rechts der Isar - Technical University of Munich, Munich, Germany
| | - Austin G Smith
- Wellcome Trust - Medical Research Council Stem Cell Institute, University of Cambridge, Cambridge, UK
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Karl-Ludwig Laugwitz
- Klinik und Poliklinik Innere Medizin I, Klinikum rechts der Isar - Technical University of Munich, Munich, Germany
- DZHK (German Centre for Cardiovascular Research) - partner site Munich Heart Alliance, Munich, Germany
| | - Alessandra Moretti
- Klinik und Poliklinik Innere Medizin I, Klinikum rechts der Isar - Technical University of Munich, Munich, Germany
- DZHK (German Centre for Cardiovascular Research) - partner site Munich Heart Alliance, Munich, Germany
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Martin CA, Curtain JP, Gajendragadkar PR, Begley DA, Fynn SP, Grace AA, Heck PM, Salaunkey K, Virdee MS, Agarwal S. Improved outcome and cost effectiveness in ablation of persistent atrial fibrillation under general anaesthetic. Europace 2018; 20:935-942. [DOI: 10.1093/europace/eux057] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023] Open
Affiliation(s)
- Claire A Martin
- Electrophysiology Department, Papworth Hospital NHS Foundation Trust, Papworth Everard, Cambridge CB23 3RE, UK
| | - James P Curtain
- Electrophysiology Department, Papworth Hospital NHS Foundation Trust, Papworth Everard, Cambridge CB23 3RE, UK
| | - Parag R Gajendragadkar
- Electrophysiology Department, Papworth Hospital NHS Foundation Trust, Papworth Everard, Cambridge CB23 3RE, UK
| | - David A Begley
- Electrophysiology Department, Papworth Hospital NHS Foundation Trust, Papworth Everard, Cambridge CB23 3RE, UK
| | - Simon P Fynn
- Electrophysiology Department, Papworth Hospital NHS Foundation Trust, Papworth Everard, Cambridge CB23 3RE, UK
| | - Andrew A Grace
- Electrophysiology Department, Papworth Hospital NHS Foundation Trust, Papworth Everard, Cambridge CB23 3RE, UK
| | - Patrick M Heck
- Electrophysiology Department, Papworth Hospital NHS Foundation Trust, Papworth Everard, Cambridge CB23 3RE, UK
| | - Kiran Salaunkey
- Electrophysiology Department, Papworth Hospital NHS Foundation Trust, Papworth Everard, Cambridge CB23 3RE, UK
| | - Munmohan S Virdee
- Electrophysiology Department, Papworth Hospital NHS Foundation Trust, Papworth Everard, Cambridge CB23 3RE, UK
| | - Sharad Agarwal
- Electrophysiology Department, Papworth Hospital NHS Foundation Trust, Papworth Everard, Cambridge CB23 3RE, UK
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9
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Grace AA, Matthews GD. Phenotypic Landscape and Risk Management in Long QT Syndrome. J Am Coll Cardiol 2018; 71:1672-1675. [DOI: 10.1016/j.jacc.2018.02.040] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2018] [Accepted: 02/20/2018] [Indexed: 11/24/2022]
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Martin CA, Curtain JP, Gajendragadkar PR, Begley DA, Fynn SP, Grace AA, Heck PM, Virdee MS, Agarwal S. Ablation of Complex Fractionated Electrograms Improves Outcome in Persistent Atrial Fibrillation of Over 2 Year's Duration. J Atr Fibrillation 2018; 10:1607. [PMID: 29988240 DOI: 10.4022/jafib.1607] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Revised: 02/23/2018] [Accepted: 02/24/2018] [Indexed: 11/10/2022]
Abstract
Aim There is controversy and sparse data on whether substrate based techniques in addition to pulmonary vein isolation (PVI) confer benefit in the catheter ablation of persistent atrial fibrillation (AF), especially if long standing. We performed an observational study to assess whether substrate based ablation improved freedom from atrial arrhythmia. Methods A total of 286 patients undergoing first ablation procedures for persistent AF with PVI only(n = 79), PVI plus linear ablation(n = 85), or PVI plus complex fractionated electrogram (CFAE) and linear ablation(n = 107) were followed. Primary end point was freedom from atrial arrhythmia at one year. Results Mean duration of pre-procedure time in AF was 28+/-27 months.There were no differences in baseline characteristics between groups except a higher proportion of patients with a severely dilated LA in those receiving PVI+CFAEs+lines. Freedom from atrial arrhythmia was higher with a PVI+CFAE+lines strategy then for PVI alone (HR 1.56, 95% CI: 1.04-2.34, p=0.032) but was not higher with PVI+lines. Benefit of substrate modification was conferred for preprocedure times in AF of over 30 months. The occurrence of atrial tachycardia was higher when lines were added to the ablation strategy (HR 0.08, 95% CI: 0.01-0.59, p=0.014). Freedom from atrial arrhythmia at 1 year was higher with lower patient age, use of general anaesthetic (GA), normal or mildly dilated left atrium and decreasing time in AF. Conclusions In patients with long standing persistent AF of over 30 months duration,CFAE ablation resulted in improved freedom from atrial arrhythmia. Increased freedom from atrial arrhythmia occurs in patients who are younger and have smaller atria, and with GA procedures. Linear ablation did not improve outcome and resulted in a higher incidence of atrial tachycardia.
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Affiliation(s)
- Claire A Martin
- Papworth Hospital NHS Foundation Trust, Papworth Everard, Cambridge CB23 3RE, UK
| | - James P Curtain
- Papworth Hospital NHS Foundation Trust, Papworth Everard, Cambridge CB23 3RE, UK
| | | | - David A Begley
- Papworth Hospital NHS Foundation Trust, Papworth Everard, Cambridge CB23 3RE, UK
| | - Simon P Fynn
- Papworth Hospital NHS Foundation Trust, Papworth Everard, Cambridge CB23 3RE, UK
| | - Andrew A Grace
- Papworth Hospital NHS Foundation Trust, Papworth Everard, Cambridge CB23 3RE, UK
| | - Patrick M Heck
- Papworth Hospital NHS Foundation Trust, Papworth Everard, Cambridge CB23 3RE, UK
| | - Munmohan S Virdee
- Papworth Hospital NHS Foundation Trust, Papworth Everard, Cambridge CB23 3RE, UK
| | - Sharad Agarwal
- Papworth Hospital NHS Foundation Trust, Papworth Everard, Cambridge CB23 3RE, UK
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Li M, Hothi SS, Salvage SC, Jeevaratnam K, Grace AA, Huang CLH. Arrhythmic effects of Epac-mediated ryanodine receptor activation in Langendorff-perfused murine hearts are associated with reduced conduction velocity. Clin Exp Pharmacol Physiol 2018; 44:686-692. [PMID: 28316073 PMCID: PMC5488224 DOI: 10.1111/1440-1681.12751] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Revised: 03/05/2017] [Accepted: 03/07/2017] [Indexed: 12/19/2022]
Abstract
Recent papers have attributed arrhythmic substrate in murine RyR2‐P2328S hearts to reduced action potential (AP) conduction velocities (CV), reflecting acute functional inhibition and/or reduced expression of sodium channels. We explored for acute effects of direct exchange protein directly activated by cAMP (Epac)‐mediated ryanodine receptor‐2 (RyR2) activation on arrhythmic substrate and CV. Monophasic action potential (MAP) recordings demonstrated that initial steady (8 Hz) extrinsic pacing elicited ventricular tachycardia (VT) in 0 of 18 Langendorff‐perfused wild‐type mouse ventricles before pharmacological intervention. The Epac activator 8‐CPT (8‐(4‐chlorophenylthio)‐2′‐O‐methyladenosine‐3′,5′‐cyclic monophosphate) (VT in 1 of 7 hearts), and the RyR2 blocker dantrolene, either alone (0 of 11) or with 8‐CPT (0 of 9) did not then increase VT incidence (P>.05). Both progressively increased pacing rates and programmed extrasystolic (S2) stimuli similarly produced no VT in untreated hearts (n=20 and n=9 respectively). 8‐CPT challenge then increased VT incidences (5 of 7 and 4 of 8 hearts respectively; P<.05). However, dantrolene, whether alone (0 of 10 and 1 of 13) or combined with 8‐CPT (0 of 10 and 0 of 13) did not increase VT incidence relative to those observed in untreated hearts (P>.05). 8‐CPT but not dantrolene, whether alone or combined with 8‐CPT, correspondingly increased AP latencies (1.14±0.04 (n=7), 1.04±0.03 (n=10), 1.09±0.05 (n=8) relative to respective control values). In contrast, AP durations, conditions for 2:1 conduction block and ventricular effective refractory periods remained unchanged throughout. We thus demonstrate for the first time that acute RyR2 activation reversibly induces VT in specific association with reduced CV.
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Affiliation(s)
- Mengye Li
- Physiological Laboratory, University of Cambridge, Cambridge, United Kingdom
| | - Sandeep S Hothi
- Physiological Laboratory, University of Cambridge, Cambridge, United Kingdom
| | - Samantha C Salvage
- Physiological Laboratory, University of Cambridge, Cambridge, United Kingdom.,Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Kamalan Jeevaratnam
- Faculty of Health and Medical Sciences, VSM Building, University of Surrey, Guildford, United Kingdom
| | - Andrew A Grace
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Christopher L-H Huang
- Physiological Laboratory, University of Cambridge, Cambridge, United Kingdom.,Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
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Valli H, Ahmad S, Sriharan S, Dean LD, Grace AA, Jeevaratnam K, Matthews HR, Huang CLH. Epac-induced ryanodine receptor type 2 activation inhibits sodium currents in atrial and ventricular murine cardiomyocytes. Clin Exp Pharmacol Physiol 2017; 45:278-292. [PMID: 29027245 PMCID: PMC5814738 DOI: 10.1111/1440-1681.12870] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Revised: 09/23/2017] [Accepted: 09/27/2017] [Indexed: 12/16/2022]
Abstract
Acute RyR2 activation by exchange protein directly activated by cAMP (Epac) reversibly perturbs myocyte Ca2+ homeostasis, slows myocardial action potential conduction, and exerts pro‐arrhythmic effects. Loose patch‐clamp studies, preserving in vivo extracellular and intracellular conditions, investigated Na+ current in intact cardiomyocytes in murine atrial and ventricular preparations following Epac activation. Depolarising steps to varying test voltages activated typical voltage‐dependent Na+ currents. Plots of peak current against depolarisation from resting potential gave pretreatment maximum atrial and ventricular currents of −20.23 ± 1.48 (17) and −29.8 ± 2.4 (10) pA/μm2 (mean ± SEM [n]). Challenge by 8‐CPT (1 μmol/L) reduced these currents to −11.21 ± 0.91 (12) (P < .004) and −19.3 ± 1.6 (11) pA/μm2 (P < .04) respectively. Currents following further addition of the RyR2 inhibitor dantrolene (10 μmol/L) (−19.91 ± 2.84 (13) and −26.6 ± 1.7 (17)), and dantrolene whether alone (−19.53 ± 1.97 (8) and −27.6 ± 1.9 (14)) or combined with 8‐CPT (−19.93 ± 2.59 (12) and −29.9 ± 2.5(11)), were indistinguishable from pretreatment values (all P >> .05). Assessment of the inactivation that followed by applying subsequent steps to a fixed voltage 100 mV positive to resting potential gave concordant results. Half‐maximal inactivation voltages and steepness factors, and time constants for Na+ current recovery from inactivation in double‐pulse experiments, were similar through all the pharmacological conditions. Intracellular sharp microelectrode membrane potential recordings in intact Langendorff‐perfused preparations demonstrated concordant variations in maximum rates of atrial and ventricular action potential upstroke, (dV/dt)max. We thus demonstrate an acute, reversible, Na+ channel inhibition offering a possible mechanism for previously reported pro‐arrhythmic slowing of AP propagation following modifications of Ca2+ homeostasis, complementing earlier findings from chronic alterations in Ca2+ homeostasis in genetically‐modified RyR2‐P2328S hearts.
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Affiliation(s)
- Haseeb Valli
- Physiological Laboratory, University of Cambridge, Cambridge, UK
| | - Shiraz Ahmad
- Physiological Laboratory, University of Cambridge, Cambridge, UK
| | - Sujan Sriharan
- Physiological Laboratory, University of Cambridge, Cambridge, UK
| | - Lydia D Dean
- Physiological Laboratory, University of Cambridge, Cambridge, UK
| | - Andrew A Grace
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Kamalan Jeevaratnam
- Physiological Laboratory, University of Cambridge, Cambridge, UK.,Faculty of Health and Medical Sciences, University of Surrey, Guildford, Surrey, UK.,PU-RCSI School of Medicine, Perdana University, Serdang, Selangor Darul Ehsan, Malaysia
| | - Hugh R Matthews
- Physiological Laboratory, University of Cambridge, Cambridge, UK
| | - Christopher L-H Huang
- Physiological Laboratory, University of Cambridge, Cambridge, UK.,Department of Biochemistry, University of Cambridge, Cambridge, UK
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13
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Ahmad S, Valli H, Salvage SC, Grace AA, Jeevaratnam K, Huang CLH. Age-dependent electrocardiographic changes in Pgc-1β deficient murine hearts. Clin Exp Pharmacol Physiol 2017; 45:174-186. [PMID: 28949414 PMCID: PMC5814877 DOI: 10.1111/1440-1681.12863] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Revised: 07/06/2017] [Accepted: 09/19/2017] [Indexed: 01/08/2023]
Abstract
Increasing evidence implicates chronic energetic dysfunction in human cardiac arrhythmias. Mitochondrial impairment through Pgc-1β knockout is known to produce a murine arrhythmic phenotype. However, the cumulative effect of this with advancing age and its electrocardiographic basis have not been previously studied. Young (12-16 weeks) and aged (>52 weeks), wild type (WT) (n = 5 and 8) and Pgc-1β-/- (n = 9 and 6), mice were anaesthetised and used for electrocardiographic (ECG) recordings. Time intervals separating successive ECG deflections were analysed for differences between groups before and after β1-adrenergic (intraperitoneal dobutamine 3 mg/kg) challenge. Heart rates before dobutamine challenge were indistinguishable between groups. The Pgc-1β-/- genotype however displayed compromised nodal function in response to adrenergic challenge. This manifested as an impaired heart rate response suggesting a functional defect at the level of the sino-atrial node, and a negative dromotropic response suggesting an atrioventricular conduction defect. Incidences of the latter were most pronounced in the aged Pgc-1β-/- mice. Moreover, Pgc-1β-/- mice displayed electrocardiographic features consistent with the existence of a pro-arrhythmic substrate. Firstly, ventricular activation was prolonged in these mice consistent with slowed action potential conduction and is reported here for the first time. Additionally, Pgc-1β-/- mice had shorter repolarisation intervals. These were likely attributable to altered K+ conductance properties, ultimately resulting in a shortened QTc interval, which is also known to be associated with increased arrhythmic risk. ECG analysis thus yielded electrophysiological findings bearing on potential arrhythmogenicity in intact Pgc-1β-/- systems in widespread cardiac regions.
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Affiliation(s)
- Shiraz Ahmad
- Physiological Laboratory, University of Cambridge, Cambridge, United Kingdom
| | - Haseeb Valli
- Physiological Laboratory, University of Cambridge, Cambridge, United Kingdom
| | - Samantha C Salvage
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Andrew A Grace
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Kamalan Jeevaratnam
- Physiological Laboratory, University of Cambridge, Cambridge, United Kingdom.,Faculty of Health and Medical Sciences, University of Surrey, Guildford, Surrey, United Kingdom.,PU-RCSI School of Medicine, Perdana University, Selangor Darul Ehsan, Malaysia
| | - Christopher L-H Huang
- Physiological Laboratory, University of Cambridge, Cambridge, United Kingdom.,Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
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14
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Derangeon M, Montnach J, Cerpa CO, Jagu B, Patin J, Toumaniantz G, Girardeau A, Huang CLH, Colledge WH, Grace AA, Baró I, Charpentier F. Transforming growth factor β receptor inhibition prevents ventricular fibrosis in a mouse model of progressive cardiac conduction disease. Cardiovasc Res 2017; 113:464-474. [PMID: 28339646 DOI: 10.1093/cvr/cvx026] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 02/16/2017] [Indexed: 01/12/2023] Open
Abstract
Aims Loss-of-function mutations in SCN5A, the gene encoding NaV1.5 channel, have been associated with inherited progressive cardiac conduction disease (PCCD). We have proposed that Scn5a heterozygous knock-out (Scn5a+/-) mice, which are characterized by ventricular fibrotic remodelling with ageing, represent a model for PCCD. Our objectives were to identify the molecular pathway involved in fibrosis development and prevent its activation. Methods and results Our study shows that myocardial interstitial fibrosis occurred in Scn5a+/- mice only after 45 weeks of age. Fibrosis was triggered by transforming growth factor β (TGF-β) pathway activation. Younger Scn5a+/- mice were characterized by a higher connexin 43 expression than wild-type (WT) mice. After the age of 45 weeks, connexin 43 expression decreased in both WT and Scn5a+/- mice, although the decrease was larger in Scn5a+/- mice. Chronic inhibition of cardiac sodium current with flecainide (50 mg/kg/day p.o) in WT mice from the age of 6 weeks to the age of 60 weeks did not lead to TGF-β pathway activation and fibrosis. Chronic inhibition of TGF-β receptors with GW788388 (5 mg/kg/day p.o.) in Scn5a+/- mice from the age of 45 weeks to the age of 60 weeks prevented the occurrence of fibrosis. However, current data could not detect reduction in QRS duration with GW788388. Conclusion Myocardial fibrosis secondary to a loss of NaV1.5 is triggered by TGF-β signalling pathway. Those events are more likely secondary to the decreased NaV1.5 sarcolemmal expression rather than the decreased Na+ current per se. TGF-β receptor inhibition prevents age-dependent development of ventricular fibrosis in Scn5a+/- mouse.
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Affiliation(s)
- Mickael Derangeon
- INSERM, UMR1087, l'institut du thorax, quai Moncousu, Nantes F-44000, France.,CNRS, UMR6291, quai Moncousu, Nantes F-44000, France.,Université de Nantes, quai Moncousu, Nantes F-44000, France
| | - Jérôme Montnach
- INSERM, UMR1087, l'institut du thorax, quai Moncousu, Nantes F-44000, France.,CNRS, UMR6291, quai Moncousu, Nantes F-44000, France.,Université de Nantes, quai Moncousu, Nantes F-44000, France
| | - Cynthia Ore Cerpa
- INSERM, UMR1087, l'institut du thorax, quai Moncousu, Nantes F-44000, France.,CNRS, UMR6291, quai Moncousu, Nantes F-44000, France.,Université de Nantes, quai Moncousu, Nantes F-44000, France
| | - Benoit Jagu
- INSERM, UMR1087, l'institut du thorax, quai Moncousu, Nantes F-44000, France.,CNRS, UMR6291, quai Moncousu, Nantes F-44000, France.,Université de Nantes, quai Moncousu, Nantes F-44000, France
| | - Justine Patin
- INSERM, UMR1087, l'institut du thorax, quai Moncousu, Nantes F-44000, France.,CNRS, UMR6291, quai Moncousu, Nantes F-44000, France.,Université de Nantes, quai Moncousu, Nantes F-44000, France
| | - Gilles Toumaniantz
- INSERM, UMR1087, l'institut du thorax, quai Moncousu, Nantes F-44000, France.,CNRS, UMR6291, quai Moncousu, Nantes F-44000, France.,Université de Nantes, quai Moncousu, Nantes F-44000, France
| | - Aurore Girardeau
- INSERM, UMR1087, l'institut du thorax, quai Moncousu, Nantes F-44000, France.,CNRS, UMR6291, quai Moncousu, Nantes F-44000, France.,Université de Nantes, quai Moncousu, Nantes F-44000, France
| | - Christopher L H Huang
- The Section of Cardiovascular Biology, Departments of Biochemistry and Physiology, University of Cambridge, Downing street, Cambridge CB23EG, UK
| | - William H Colledge
- The Section of Cardiovascular Biology, Departments of Biochemistry and Physiology, University of Cambridge, Downing street, Cambridge CB23EG, UK
| | - Andrew A Grace
- The Section of Cardiovascular Biology, Departments of Biochemistry and Physiology, University of Cambridge, Downing street, Cambridge CB23EG, UK
| | - Isabelle Baró
- INSERM, UMR1087, l'institut du thorax, quai Moncousu, Nantes F-44000, France.,CNRS, UMR6291, quai Moncousu, Nantes F-44000, France.,Université de Nantes, quai Moncousu, Nantes F-44000, France
| | - Flavien Charpentier
- INSERM, UMR1087, l'institut du thorax, quai Moncousu, Nantes F-44000, France.,CNRS, UMR6291, quai Moncousu, Nantes F-44000, France.,Université de Nantes, quai Moncousu, Nantes F-44000, France.,CHU Nantes, Alexis Ricordeau, Nantes F-44000, France
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Mellor G, Panizo JG, Baran J, Begley D, Heck PM, Fynn SP, Grace AA. 39Application of the novel ‘shanghai’ diagnostic criteria for brugada syndrome reduces the number of diagnoses with low risk of arrhythmic events in index cases. Europace 2017. [DOI: 10.1093/europace/eux283.048] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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16
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Valli H, Ahmad S, Chadda KR, Al-Hadithi ABAK, Grace AA, Jeevaratnam K, Huang CLH. Age-dependent atrial arrhythmic phenotype secondary to mitochondrial dysfunction in Pgc-1β deficient murine hearts. Mech Ageing Dev 2017; 167:30-45. [PMID: 28919427 PMCID: PMC5652526 DOI: 10.1016/j.mad.2017.09.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Revised: 08/24/2017] [Accepted: 09/13/2017] [Indexed: 12/19/2022]
Abstract
INTRODUCTION Ageing and several age-related chronic conditions including obesity, insulin resistance and hypertension are associated with mitochondrial dysfunction and represent independent risk factors for atrial fibrillation (AF). MATERIALS AND METHODS Atrial arrhythmogenesis was investigated in Langendorff-perfused young (3-4 month) and aged (>12 month), wild type (WT) and peroxisome proliferator activated receptor-γ coactivator-1β deficient (Pgc-1β-/-) murine hearts modeling age-dependent chronic mitochondrial dysfunction during regular pacing and programmed electrical stimulation (PES). RESULTS AND DISCUSSION The Pgc-1β-/- genotype was associated with a pro-arrhythmic phenotype progressing with age. Young and aged Pgc-1β-/- hearts showed compromised maximum action potential (AP) depolarization rates, (dV/dt)max, prolonged AP latencies reflecting slowed action potential (AP) conduction, similar effective refractory periods and baseline action potential durations (APD90) but shortened APD90 in APs in response to extrasystolic stimuli at short stimulation intervals. Electrical properties of APs triggering arrhythmia were similar in WT and Pgc-1β-/- hearts. Pgc-1β-/- hearts showed accelerated age-dependent fibrotic change relative to WT, with young Pgc-1β-/- hearts displaying similar fibrotic change as aged WT, and aged Pgc-1β-/- hearts the greatest fibrotic change. Mitochondrial deficits thus result in an arrhythmic substrate, through slowed AP conduction and altered repolarisation characteristics, arising from alterations in electrophysiological properties and accelerated structural change.
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Affiliation(s)
- Haseeb Valli
- Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, CB2 3EG, United Kingdom
| | - Shiraz Ahmad
- Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, CB2 3EG, United Kingdom
| | - Karan R Chadda
- Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, CB2 3EG, United Kingdom; Faculty of Health and Medical Sciences, University of Surrey, GU2 7AL, Guildford, Surrey, United Kingdom
| | - Ali B A K Al-Hadithi
- Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, CB2 3EG, United Kingdom
| | - Andrew A Grace
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QW, United Kingdom
| | - Kamalan Jeevaratnam
- Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, CB2 3EG, United Kingdom; Faculty of Health and Medical Sciences, University of Surrey, GU2 7AL, Guildford, Surrey, United Kingdom; PU-RCSI School of Medicine, Perdana University, 43400, Serdang, Selangor Darul Ehsan, Malaysia
| | - Christopher L-H Huang
- Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, CB2 3EG, United Kingdom; Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QW, United Kingdom.
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17
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Jeevaratnam K, Chadda KR, Salvage SC, Valli H, Ahmad S, Grace AA, Huang CLH. Ion channels, long QT syndrome and arrhythmogenesis in ageing. Clin Exp Pharmacol Physiol 2017; 44 Suppl 1:38-45. [PMID: 28024120 PMCID: PMC5763326 DOI: 10.1111/1440-1681.12721] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Revised: 12/18/2016] [Accepted: 12/19/2016] [Indexed: 01/08/2023]
Abstract
Ageing is associated with increased prevalences of both atrial and ventricular arrhythmias, reflecting disruption of the normal sequence of ion channel activation and inactivation generating the propagated cardiac action potential. Experimental models with specific ion channel genetic modifications have helped clarify the interacting functional roles of ion channels and how their dysregulation contributes to arrhythmogenic processes at the cellular and systems level. They have also investigated interactions between these ion channel abnormalities and age-related processes in producing arrhythmic tendency. Previous reviews have explored the relationships between age and loss-of-function Nav 1.5 mutations in producing arrhythmogenicity. The present review now explores complementary relationships arising from gain-of-function Nav 1.5 mutations associated with long QT3 (LQTS3). LQTS3 patients show increased risks of life-threatening ventricular arrhythmias, particularly after 40 years of age, consistent with such interactions between the ion channel abnormailities and ageing. In turn clinical evidence suggests that ageing is accompanied by structural, particularly fibrotic, as well as electrophysiological change. These abnormalities may result from biochemical changes producing low-grade inflammation resulting from increased production of reactive oxygen species and superoxide. Experimental studies offer further insights into the underlying mechanisms underlying these phenotypes. Thus, studies in genetically modified murine models for LQTS implicated action potential recovery processes in arrhythmogenesis resulting from functional ion channel abnormalities. In addition, ageing wild type (WT) murine models demonstrated both ion channel alterations and fibrotic changes with ageing. Murine models then suggested evidence for interactions between ageing and ion channel mutations and provided insights into potential arrhythmic mechanisms inviting future exploration.
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Affiliation(s)
- Kamalan Jeevaratnam
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK.,School of Medicine, Perdana University-Royal College of Surgeons Ireland, Serdang, Selangor Darul Ehsan, Malaysia
| | - Karan R Chadda
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK.,Physiological Laboratory, University of Cambridge, Cambridge, UK
| | | | - Haseeb Valli
- Physiological Laboratory, University of Cambridge, Cambridge, UK
| | - Shiraz Ahmad
- Physiological Laboratory, University of Cambridge, Cambridge, UK
| | - Andrew A Grace
- Division of Cardiovascular Biology, Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Christopher L-H Huang
- Physiological Laboratory, University of Cambridge, Cambridge, UK.,Division of Cardiovascular Biology, Department of Biochemistry, University of Cambridge, Cambridge, UK
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18
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Ahmad S, Valli H, Edling CE, Grace AA, Jeevaratnam K, Huang CLH. Effects of ageing on pro-arrhythmic ventricular phenotypes in incrementally paced murine Pgc-1β -/- hearts. Pflugers Arch 2017; 469:1579-1590. [PMID: 28821956 PMCID: PMC5691113 DOI: 10.1007/s00424-017-2054-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Revised: 08/02/2017] [Accepted: 08/03/2017] [Indexed: 01/07/2023]
Abstract
A range of chronic clinical conditions accompany cardiomyocyte energetic dysfunction and constitute independent risk factors for cardiac arrhythmia. We investigated pro-arrhythmic and arrhythmic phenotypes in energetically deficient C57BL mice with genetic ablation of the mitochondrial promoter peroxisome proliferator-activated receptor-γ coactivator-1β (Pgc-1β), a known model of ventricular arrhythmia. Pro-arrhythmic and cellular action potential (AP) characteristics were compared in intact Langendorff-perfused hearts from young (12–16 week) and aged (> 52 week), wild-type (WT) and Pgc-1β−/− mice. Simultaneous electrocardiographic and intracellular microelectrode recordings were made through successive trains of 100 regular stimuli at progressively incremented heart rates. Aged Pgc-1β−/− hearts displayed an increased incidence of arrhythmia compared to other groups. Young and aged Pgc-1β−/− hearts showed higher incidences of alternans in both AP activation (maximum AP upshoot velocity (dV/dt)max and latency), recovery (action potential duration (APD90) and resting membrane potential (RMP) characteristics compared to WT hearts. This was particularly apparent at lower pacing frequencies. These findings accompanied reduced (dV/dt)max and increased AP latency values in the Pgc-1β−/− hearts. APs observed prior to termination of the protocol showed lower (dV/dt)max and longer AP latencies, but indistinguishable APD90 and RMPs in arrhythmic compared to those in non-arrhythmic hearts. APD restitution analysis showed that Pgc-1β−/− and WT hearts showed similar limiting gradients. However, Pgc-1β−/− hearts had shortened plateau AP wavelengths, particularly in aged Pgc-1β−/− hearts. Pgc-1β−/− hearts therefore show pro-arrhythmic instabilities attributable to altered AP conduction and activation rather than recovery characteristics.
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Affiliation(s)
- Shiraz Ahmad
- Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, CB2 3EG, UK.
| | - Haseeb Valli
- Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, CB2 3EG, UK
| | - Charlotte E Edling
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, Surrey, GU2 7AL, UK
| | - Andrew A Grace
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QW, UK
| | - Kamalan Jeevaratnam
- Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, CB2 3EG, UK
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, Surrey, GU2 7AL, UK
- PU-RCSI School of Medicine, Perdana University, 43400, Serdang, Selangor Darul Ehsan, Malaysia
| | - Christopher L-H Huang
- Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, CB2 3EG, UK.
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QW, UK.
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19
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Steullet P, Cabungcal JH, Coyle J, Didriksen M, Gill K, Grace AA, Hensch TK, LaMantia AS, Lindemann L, Maynard TM, Meyer U, Morishita H, O'Donnell P, Puhl M, Cuenod M, Do KQ. Oxidative stress-driven parvalbumin interneuron impairment as a common mechanism in models of schizophrenia. Mol Psychiatry 2017; 22:936-943. [PMID: 28322275 PMCID: PMC5491690 DOI: 10.1038/mp.2017.47] [Citation(s) in RCA: 234] [Impact Index Per Article: 33.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Revised: 12/21/2016] [Accepted: 01/17/2017] [Indexed: 02/08/2023]
Abstract
Parvalbumin inhibitory interneurons (PVIs) are crucial for maintaining proper excitatory/inhibitory balance and high-frequency neuronal synchronization. Their activity supports critical developmental trajectories, sensory and cognitive processing, and social behavior. Despite heterogeneity in the etiology across schizophrenia and autism spectrum disorder, PVI circuits are altered in these psychiatric disorders. Identifying mechanism(s) underlying PVI deficits is essential to establish treatments targeting in particular cognition. On the basis of published and new data, we propose oxidative stress as a common pathological mechanism leading to PVI impairment in schizophrenia and some forms of autism. A series of animal models carrying genetic and/or environmental risks relevant to diverse etiological aspects of these disorders show PVI deficits to be all accompanied by oxidative stress in the anterior cingulate cortex. Specifically, oxidative stress is negatively correlated with the integrity of PVIs and the extracellular perineuronal net enwrapping these interneurons. Oxidative stress may result from dysregulation of systems typically affected in schizophrenia, including glutamatergic, dopaminergic, immune and antioxidant signaling. As convergent end point, redox dysregulation has successfully been targeted to protect PVIs with antioxidants/redox regulators across several animal models. This opens up new perspectives for the use of antioxidant treatments to be applied to at-risk individuals, in close temporal proximity to environmental impacts known to induce oxidative stress.
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Affiliation(s)
- P Steullet
- Centre for Psychiatric Neuroscience, Department of Psychiatry, Lausanne University Hospital, Prilly-Lausanne, Switzerland
| | - J-H Cabungcal
- Centre for Psychiatric Neuroscience, Department of Psychiatry, Lausanne University Hospital, Prilly-Lausanne, Switzerland
| | - J Coyle
- Laboratory for Psychiatric and Molecular Neuroscience, Harvard Medical School, McLean Hospital, Belmont, MA, USA
| | - M Didriksen
- Synaptic transmission H. Lundbeck A/S, Valby, Denmark
| | - K Gill
- Departments of Neuroscience, Psychiatry and Psychology, University of Pittsburgh, Pittsburgh, PA, USA
| | - A A Grace
- Departments of Neuroscience, Psychiatry and Psychology, University of Pittsburgh, Pittsburgh, PA, USA
| | - T K Hensch
- Center for Brain Science, Department of Molecular Cellular Biology, Harvard University, Cambridge, MA USA,FM Kirby Neurobiology Center, Department of Neurology, Boston Children’s Hospital, Harvard Medical School, Boston, MA, USA
| | - A-S LaMantia
- George Washington Institute for Neuroscience, The George Washington University, Washington, DC, USA
| | - L Lindemann
- F. Hoffmann-La Roche, Roche Pharmaceutical and Early Development, Neuroscience, Opthalmology & Rare Disease (NORD) DTA, Discovery Neuroscience, Roche Innovation Center Basel, Basel, Switzerland
| | - T M Maynard
- George Washington Institute for Neuroscience, The George Washington University, Washington, DC, USA
| | - U Meyer
- Institute of Pharmacology and Toxicology, University of Zurich-Vetsuisse, Zurich, Switzerland
| | - H Morishita
- Center for Brain Science, Department of Molecular Cellular Biology, Harvard University, Cambridge, MA USA,FM Kirby Neurobiology Center, Department of Neurology, Boston Children’s Hospital, Harvard Medical School, Boston, MA, USA,Department of Psychiatry, Neuroscience, and Ophthalmology, Friedman Brain Institute, Mindich Child Health and Development Institute, Icahn School of Medicine at Mount Sinai, NY, USA
| | - P O'Donnell
- Neuroscience and Pain Research Unit, BioTherapeutics Research and Development, Pfizer, Cambridge, MA, USA
| | - M Puhl
- Laboratory for Psychiatric and Molecular Neuroscience, Harvard Medical School, McLean Hospital, Belmont, MA, USA
| | - M Cuenod
- Centre for Psychiatric Neuroscience, Department of Psychiatry, Lausanne University Hospital, Prilly-Lausanne, Switzerland
| | - K Q Do
- Centre for Psychiatric Neuroscience, Department of Psychiatry, Lausanne University Hospital, Prilly-Lausanne, Switzerland,Center for Psychiatric Neuroscience, Department of Psychiatry, Lausanne University Hospital, Prilly-Lausanne CH-1008, Switzerland. E-mail:
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20
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Krystal JH, Abi-Dargham A, Akbarian S, Arnsten AFT, Barch DM, Bearden CE, Braff DL, Brown ES, Bullmore ET, Carlezon WA, Carter CS, Cook EH, Daskalakis ZJ, DiLeone RJ, Duman RS, Grace AA, Hariri AR, Harrison PJ, Hiroi N, Kenny PJ, Kleinman JE, Krystal AD, Lewis DA, Lipska BK, Marder SR, Mason GF, Mathalon DH, McClung CA, McDougle CJ, McIntosh AM, McMahon FJ, Mirnics K, Monteggia LM, Narendran R, Nestler EJ, Neumeister A, O’Donovan MC, Öngür D, Pariante CM, Paulus MP, Pearlson G, Phillips ML, Pine DS, Pizzagalli DA, Pletnikov MV, Ragland JD, Rapoport JL, Ressler KJ, Russo SJ, Sanacora G, Sawa A, Schatzberg AF, Shaham Y, Shamay-Tsoory SG, Sklar P, State MW, Stein MB, Strakowski SM, Taylor SF, Turecki G, Turetsky BI, Weissman MM, Zachariou V, Zarate CA, Zubieta JK. Constance E. Lieber, Theodore R. Stanley, and the Enduring Impact of Philanthropy on Psychiatry Research. Biol Psychiatry 2016; 80:84-86. [PMID: 27346079 PMCID: PMC6150945 DOI: 10.1016/j.biopsych.2016.05.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Revised: 05/09/2016] [Accepted: 05/09/2016] [Indexed: 10/21/2022]
Affiliation(s)
- JH Krystal
- Department of Psychiatry and Neuroscience, Yale University School of Medicine, New Haven, Connecticut; Behavioral Health Services, Yale New Haven Hospital, New Haven, Connecticut; Clinical Neuroscience Division, VA Connecticut Healthcare System, West Haven, Connecticut; Departments of Psychiatry and Radiology, Columbia University, New York, New York.
| | - A Abi-Dargham
- The New York State Psychiatric Institute, New York, New York
| | - S Akbarian
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, New York
| | - AFT Arnsten
- Department of Psychiatry and Neuroscience, Yale University School of Medicine, New Haven, Connecticut; Child Study Center, Yale University School of Medicine, New Haven, Connecticut
| | - DM Barch
- Departments of Psychology and Radiology, Washington University in St. Louis, St. Louis, Missouri
| | - CE Bearden
- Departments of Psychiatry and Psychology and the Brain Research Institute, Semel Institute for Neuroscience and Human Behavior, University of California at Los Angeles, Los Angeles, California
| | - DL Braff
- Department of Psychiatry, University of California San Diego, San Diego, California
| | - ES Brown
- Department of Psychiatry, The University of Texas Southwestern Medical Center, Dallas, Texas
| | - ET Bullmore
- Department of Psychiatry and Behavioral and Neuroscience Institute, University of Cambridge, Cambridge, United Kingdom; ImmunoPsychiatry, GlaxoSmithKline, Cambridge, United Kingdom
| | - WA Carlezon
- Department of Psychiatry and Neuroscience, Harvard Medical School, McLean Hospital, Belmont, Massachusetts
| | - CS Carter
- Department of Psychiatry and Behavioral Sciences, Imaging Research Center, and Center for Neuroscience, University of California at Davis, Davis, California
| | - EH Cook
- Institute of Juvenile Research, Department of Psychiatry, University of Illinois at Chicago, Chicago, Illinois
| | - ZJ Daskalakis
- Temerty Centre for Therapeutic Brain Intervention, Mood and Anxiety Division Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
| | - RJ DiLeone
- Department of Psychiatry, Yale University, New Haven, Connecticut
| | - RS Duman
- Department of Psychiatry and Neuroscience, Yale University School of Medicine, New Haven, Connecticut
| | - AA Grace
- Departments of Neuroscience, Psychiatry, and Psychology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - AR Hariri
- Department of Psychology & Neuroscience, Duke University, Durham, North Carolina
| | - PJ Harrison
- Department of Psychiatry, University of Oxford, Oxford, United Kingdom
| | - N Hiroi
- Departments of Psychiatry and Behavioral Sciences, Neuroscience, and Genetics, Albert Einstein College of Medicine, Bronx, New York
| | - PJ Kenny
- Department of Pharmacology & Systems Therapeutics, Icahn School of Medicine at Mount Sinai, New York, New York
| | - JE Kleinman
- Genetic Neuropathology Section, Lieber Institute for Brain Development, and Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - AD Krystal
- Department of Psychiatry and Behavioral Sciences, Duke University School of Medicine, Durham, North Carolina
| | - DA Lewis
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - BK Lipska
- Human Brain Collection Core, Division of Intramural Research Programs, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland
| | - SR Marder
- Semel Institute for Neuroscience, University of California at Los Angeles, Los Angeles, California; VA Desert Pacific Mental Illness Research, Education, and Clinical Center, Los Angeles, California
| | - GF Mason
- Departments of Radiology & Biomedical Imaging and Psychiatry, Yale University, School of Medicine, New Haven, Connecticut
| | - DH Mathalon
- Department of Psychiatry, University of California at San Francisco, San Francisco, California; Psychiatry Service, San Francisco VA Medical Center, San Francisco, California
| | - CA McClung
- Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - CJ McDougle
- Massachusetts General Hospital and MassGeneral Hospital for Children, Lurie Center for Autism, Lexington, Massachusetts; Department of Psychiatry, Harvard Medical School, Boston, Massachusetts
| | - AM McIntosh
- Division of Psychiatry, University of Edinburgh, Edinburgh, United Kingdom
| | - FJ McMahon
- Human Genetics Branch and Genetic Basis of Mood and Anxiety Disorders Section, National Institute of Mental Health, Intramural Research Program, Bethesda, Maryland
| | - K Mirnics
- Department of Psychiatry, Vanderbilt University, Nashville, Tennessee
| | - LM Monteggia
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, Texas
| | - R Narendran
- Departments of Radiology and Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - EJ Nestler
- Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, New York
| | - A Neumeister
- Mitsubishi Tanabe Pharma Development America, Inc., Jersey City, New Jersey
| | - MC O’Donovan
- MRC Centre for Neuropsychiatric Genetics and Genomics, Cardiff University, Cardiff, United Kingdom
| | - D Öngür
- Department of Psychiatry, McLean Hospital, Harvard Medical School, Belmont, Massachusetts
| | - CM Pariante
- Departments of Psychology and Neuroscience, Institute of Psychiatry, King’s College London, London, United Kingdom; Psychiatry and Immunology Lab & Perinatal Psychiatry, The Maurice Wohl Clinical Neuroscience Institute, London, United Kingdom
| | - MP Paulus
- Laureate Institute for Brain Research, Tulsa, Oklahoma
| | - G Pearlson
- Departments of Psychiatry and Neurobiology, Yale University and Olin Neuropsychiatric Research Center, Hartford, Connecticut
| | - ML Phillips
- Department of Psychiatry, Western Psychiatric Institute and Clinic, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - DS Pine
- National Institute of Mental Health, Intramural Research Program, Bethesda, Maryland
| | - DA Pizzagalli
- Department of Psychiatry, Harvard Medical School, Boston, Massachusetts; McLean Imaging Center, McLean Hospital, Belmont, Massachusetts
| | - MV Pletnikov
- Departments of Neuroscience and Molecular and Comparative Pathobiology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - JD Ragland
- Department of Psychiatry and Behavioral Sciences, Imaging Research Center, University of California at Davis, Sacramento, California
| | - JL Rapoport
- Child Psychiatry Branch, Division of Intramural Research, National Institute of Mental Health, Bethesda, Maryland
| | - KJ Ressler
- Department of Psychiatry, McLean Hospital, Harvard Medical School, Belmont, Massachusetts
| | - SJ Russo
- Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, New York
| | - G Sanacora
- Department of Psychiatry, Yale University, New Haven, Connecticut
| | - A Sawa
- Department of Psychiatry, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - AF Schatzberg
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, California
| | - Y Shaham
- Behavioral Neuroscience Branch, NIDA-IRP, Baltimore, Maryland
| | - SG Shamay-Tsoory
- Department of Psychology, University of Haifa, Mount Carmel, Haifa, Israel
| | - P Sklar
- Division of Psychiatric Genomics, Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, New York
| | - MW State
- Department of Psychiatry, University of California at San Francisco, San Francisco, California
| | - MB Stein
- Departments of Psychiatry and Family Medicine & Public Health, School of Medicine, University of California at San Diego, La Jolla, California
| | - SM Strakowski
- Department of Psychiatry, Dell Medical School, University of Texas at Austin, Austin, Texas
| | - SF Taylor
- Department of Psychiatry, University of Michigan, Ann Arbor, Michigan
| | - G Turecki
- Department of Psychiatry, McGill University, Montreal, Canada
| | - BI Turetsky
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - MM Weissman
- New York State Psychiatric Institute & Department of Psychiatry, College of Physicians and Surgeons of Columbia University, New York, New York
| | - V Zachariou
- Fishberg Department of Neuroscience, Mount Sinai School of Medicine, New York, New York
| | - CA Zarate
- Experimental Therapeutics and Pathophysiology Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland
| | - JK Zubieta
- Department of Psychiatry, University Neuropsychiatric Institute, University of Utah Health Sciences Center, Salt Lake City, Utah
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Knops RE, Brouwer TF, Barr CS, Theuns DA, Boersma L, Weiss R, Neuzil P, Scholten M, Lambiase PD, Leon AR, Hood M, Jones PW, Wold N, Grace AA, Olde Nordkamp LRA, Burke MC. The learning curve associated with the introduction of the subcutaneous implantable defibrillator. Europace 2015; 18:1010-5. [PMID: 26324840 PMCID: PMC4927061 DOI: 10.1093/europace/euv299] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Accepted: 08/10/2015] [Indexed: 02/02/2023] Open
Abstract
Aims The subcutaneous implantable cardioverter defibrillator (S-ICD) was introduced to overcome complications related to transvenous leads. Adoption of the S-ICD requires implanters to learn a new implantation technique. The aim of this study was to assess the learning curve for S-ICD implanters with respect to implant-related complications, procedure time, and inappropriate shocks (IASs). Methods and results In a pooled cohort from two clinical S-ICD databases, the IDE Trial and the EFFORTLESS Registry, complications, IASs at 180 days follow-up and implant procedure duration were assessed. Patients were grouped in quartiles based on experience of the implanter and Kaplan–Meier estimates of complication and IAS rates were calculated. A total of 882 patients implanted in 61 centres by 107 implanters with a median of 4 implants (IQR 1,8) were analysed. There were a total of 59 patients with complications and 48 patients with IAS. The complication rate decreased significantly from 9.8% in Quartile 1 (least experience) to 5.4% in Quartile 4 (most experience) (P = 0.02) and non-significantly for IAS from 7.9 to 4.8% (P = 0.10). Multivariable analysis demonstrated a hazard ratio of 0.78 (P = 0.045) for complications and 1.01 (P = 0.958) for IAS. Dual-zone programming increased with experience of the individual implanter (P < 0.001), which reduced IAS significantly in the multivariable model (HR 0.44, P = 0.01). Procedure time decreased from 75 to 65 min (P < 0.001). The complication rate and procedure time stabilized after Quartile 2 (>13 implants). Conclusion There is a short and significant learning curve associated with physicians adopting the S-ICD. Performance stabilizes after 13 implants.
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Affiliation(s)
| | | | | | | | | | - Raul Weiss
- Ohio State University, Columbus, OH, USA
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Looi KL, Gajendragadkar PR, Khan FZ, Elsik M, Begley DA, Fynn SP, Grace AA, Heck PM, Virdee M, Agarwal S. Cardiac resynchronisation therapy: pacemaker versus internal cardioverter-defibrillator in patients with impaired left ventricular function. Heart 2014; 100:794-9. [PMID: 24691411 DOI: 10.1136/heartjnl-2014-305537] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
OBJECTIVE Studies have shown beneficial effects of cardiac resynchronisation therapy (CRT) on mortality among patients with heart failure. However the incremental benefits in survival from CRT with a defibrillator (CRT-D) are unclear. The choice of appropriate device remains unanswered. METHOD This is a single-centre observational study in a tertiary cardiac centre. Patients (n=500) implanted with a CRT device with pacing alone (CRT-P) (n=354) and CRT-D (n=146) were followed for at least 2 years (mean 29 months, SD 14 months). The primary end point was all-cause mortality. RESULTS A total of 116 deaths (23.2%) were recorded: 88 (24.8%) and 28 (19.2%), in the CRT-P and CRT-D groups, respectively. At 1 year there was a trend favouring CRT-D (HR 0.54, 95% CI 0.27 to 1.07, p=0.08) but this was attenuated by the 2nd year and became insignificant at the end of follow-up (HR 0.76, 95% CI 0.50 to 1.170, p=0.21). There was no survival benefit from having an internal cardioverter-defibrillator if patients were deemed non-responders to CRT. 27% of the CRT-P patients with ischaemic cardiomyopathy met indications for potential internal cardioverter-defibrillator implantation for primary prevention. These were older patients with poorer baseline function in comparison with CRT-D patients with devices for primary prevention. Once these differences were adjusted for, there was no difference in outcome between the groups. CONCLUSIONS CRT-D did not offer additional survival advantage over CRT-P at longer-term follow-up, as the clinical benefit of a defibrillator attenuated with time. Further work is needed to define which subset of patients benefit from CRT-D.
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Affiliation(s)
- Khang-Li Looi
- Papworth Hospital NHS Foundation Trust, , Cambridge, UK
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Matthews GDK, Currie CE, Grace AA, Huang CLH. 18 Metabolically Compromised Murine PGC-1B(-/-) Hearts Show Decreased action Potential Duration and Increased Arrhythmia with Adrenergic Challenge. Heart 2014. [DOI: 10.1136/heartjnl-2013-305297.18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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25
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Grace AA, Narayan SM, O'Neill MD. Atrial fibrillation and heart failure. Preface. Heart Fail Clin 2013; 9:xv. [PMID: 24054486 DOI: 10.1016/j.hfc.2013.08.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Affiliation(s)
- Andrew A Grace
- Department of Biochemistry, University of Cambridge, Hopkins Building, Tennis Court Road, CB2 1QW, UK; Papworth Hospital, Cambridge CB23 3RE, UK.
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King JH, Wickramarachchi C, Kua K, Du Y, Jeevaratnam K, Matthews HR, Grace AA, Huang CLH, Fraser JA. Loss of Nav1.5 expression and function in murine atria containing the RyR2-P2328S gain-of-function mutation. Cardiovasc Res 2013; 99:751-9. [PMID: 23723061 DOI: 10.1093/cvr/cvt141] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
AIMS Recent studies reported slowed conduction velocity (CV) in murine hearts homozygous for the gain-of-function RyR2-P2328S mutation (RyR2(S/S)) and associated this with an increased incidence of atrial and ventricular arrhythmias. The present experiments determined mechanisms contributing to the reduced atrial CV. METHODS AND RESULTS The determinants of CV were investigated in murine RyR2(S/S) hearts and compared with those in wild-type (WT) and slow-conducting Scn5a(+/-) hearts. Picrosirius red staining demonstrated increased fibrosis only in Scn5a(+/-) hearts. Immunoblot assays showed similar expressions of Cx43 and Cx40 levels in the three genotypes. In contrast, Nav1.5 expression was reduced in both RyR2(S/S) and Scn5a(+/-) atria. These findings correlated with intracellular microelectrode and loose-patch-clamp studies. Microelectrode measurements showed reduced maximum rates of depolarization in Scn5a(+/-) and RyR2(S/S) atria compared with WT, despite similar diastolic membrane potentials. Loose-patch-clamp measurements demonstrated reduced peak Na(+) currents (INa) in the Scn5a(+/-) and RyR2(S/S) atria relative to WT, with similar normalized current-voltage relationships. In WT atria, reduction in INa could be produced by treatment with high extracellular Ca(2+), caffeine, or cyclopiazonic acid, each expected to produce an acute increase in [Ca(2+)]i. CONCLUSION RyR2(S/S) atria show reduced levels of Nav1.5 expression and Na(+) channel function. Reduced Na(+) channel function was also observed in WT atria, following acute increases in [Ca(2+)]i. Taken together, the results suggest that raised [Ca(2+)]i produces both acute and chronic inhibition of Na(+) channel function. These findings may help explain the relationship between altered Ca(2+) homeostasis, CV, and the maintenance of common arrhythmias such as atrial fibrillation.
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Affiliation(s)
- James H King
- Physiological Laboratory, University of Cambridge, UK
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27
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Matthews GDK, Guzadhur L, Sabir IN, Grace AA, Huang CLH. Action potential wavelength restitution predicts alternans and arrhythmia in murine Scn5a(+/-) hearts. J Physiol 2013; 591:4167-88. [PMID: 23836691 PMCID: PMC3779110 DOI: 10.1113/jphysiol.2013.254938] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Reductions in cardiac action potential wavelength, and the consequent wavebreak, have been implicated in arrhythmogenesis. Tachyarrhythmias are more common in the Brugada syndrome, particularly following pharmacological challenge, previously modelled using Scn5a+/− murine hearts. Propagation latencies and action potential durations (APDs) from monophasic action potential recordings were used to assess wavelength changes with heart rate in Langendorff-perfused wild-type (WT) and Scn5a+/− hearts. Recordings were obtained from right (RV) and left (LV) ventricular, epicardial and endocardial surfaces during incremental pacing, before and following flecainide or quinidine challenge. Conduction velocities (θ′), action potential wavelengths (λ′= APD ×θ′), and their corresponding alternans depended non-linearly upon diastolic interval (DI). Maximum θ′ was lower in Scn5a+/− RV epicardium than endocardium. Flecainide further reduced θ′, accentuating this RV conduction block. Quinidine reduced maximum θ′ in WT and caused earlier conduction failure in the RV of both Scn5a+/− and WT. Use of recovery wavelengths (λ′0= DI ×θ′) rather than DI, provided novel λ restitution plots of λ′ against λ′0, which sum to a basic cycle distance permitting feedback analysis. λ′ restitution gradient better correlated with alternans magnitude than either APD or θ restitution gradient. The large differences in θ′ and APD restitution contrasted with minor differences in maximum λ′ between epi- and endocardia of untreated hearts, and quinidine-treated WT hearts. Strikingly, all regions and conditions converged to a common instability point, implying a conserved relationship. Flecainide or quinidine decreased the pacing rates at which this occurred, through reducing basic cycle distance, in the Scn5a+/− RV epicardium, directly predictive of its arrhythmic phenotype.
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Affiliation(s)
- Gareth D K Matthews
- G. D. K. Matthews: Physiological Laboratory, University of Cambridge, Downing Street, Cambridge CB2 3EG, UK.
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Martin CA, Siedlecka U, Kemmerich K, Lawrence J, Cartledge J, Guzadhur L, Brice N, Grace AA, Schwiening C, Terracciano CM, Huang CLH. Reduced Na(+) and higher K(+) channel expression and function contribute to right ventricular origin of arrhythmias in Scn5a+/- mice. Open Biol 2013; 2:120072. [PMID: 22773948 PMCID: PMC3390792 DOI: 10.1098/rsob.120072] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Accepted: 05/11/2012] [Indexed: 12/17/2022] Open
Abstract
Brugada syndrome (BrS) is associated with ventricular tachycardia originating particularly in the right ventricle (RV). We explore electrophysiological features predisposing to such arrhythmic tendency and their possible RV localization in a heterozygotic Scn5a+/− murine model. Nav1.5 mRNA and protein expression were lower in Scn5a+/− than wild-type (WT), with a further reduction in the RV compared with the left ventricle (LV). RVs showed higher expression levels of Kv4.2, Kv4.3 and KChIP2 in both Scn5a+/− and WT. Action potential upstroke velocity and maximum Na+ current (INa) density were correspondingly decreased in Scn5a+/−, with a further reduction in the RV. The voltage dependence of inactivation was shifted to more negative values in Scn5a+/−. These findings are predictive of a localized depolarization abnormality leading to slowed conduction. Persistent Na+ current (IpNa) density was decreased in a similar pattern to INa. RV transient outward current (Ito) density was greater than LV in both WT and Scn5a+/−, and had larger time constants of inactivation. These findings were also consistent with the observation that AP durations were smallest in the RV of Scn5a+/−, fulfilling predictions of an increased heterogeneity of repolarization as an additional possible electrophysiological mechanism for arrhythmogenesis in BrS.
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Affiliation(s)
- Claire A Martin
- Physiological Laboratory, University of Cambridge, Downing Site, Cambridge CB2 3EG, UK.
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29
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Looi KL, Lee ASY, Cole K, Agarwal S, Heck PM, Begley DA, Grace AA, Virdee M, Fynn SP. Conscious sedation and analgesia use in cardiac device implantation. Int J Cardiol 2013; 168:561-3. [PMID: 23452883 DOI: 10.1016/j.ijcard.2013.01.167] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Accepted: 01/13/2013] [Indexed: 01/21/2023]
Affiliation(s)
- Khang-Li Looi
- Department of Cardiology, Papworth Hospital NHS Foundation Trust, Cambridge CB23 3RE, United Kingdom.
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Abstract
During the past few years, the development of effective, empirical technologies for treatment of cardiac arrhythmias has exceeded the pace at which detailed knowledge of the underlying biology has accumulated. As a result, although some clinical arrhythmias can be cured with techniques such as catheter ablation, drug treatment and prediction of the risk of sudden death remain fairly primitive. The identification of key candidate genes for monogenic arrhythmia syndromes shows that to bring basic biology to the clinic is a powerful approach. Increasingly sophisticated experimental models and methods of measurement, including stem cell-based models of human cardiac arrhythmias, are being deployed to study how perturbations in several biologic pathways can result in an arrhythmia-prone heart. The biology of arrhythmia is largely quantifiable, which allows for systematic analysis that could transform treatment strategies that are often still empirical into management based on molecular evidence.
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Affiliation(s)
- Andrew A Grace
- Department of Biochemistry, University of Cambridge, Cambridge, UK.
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31
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Jeevaratnam K, Rewbury R, Zhang Y, Guzadhur L, Grace AA, Lei M, Huang CLH. Frequency distribution analysis of activation times and regional fibrosis in murine Scn5a+/- hearts: the effects of ageing and sex. Mech Ageing Dev 2012; 133:591-9. [PMID: 22968175 PMCID: PMC3466423 DOI: 10.1016/j.mad.2012.07.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2011] [Revised: 07/17/2012] [Accepted: 07/31/2012] [Indexed: 12/21/2022]
Abstract
Both Brugada Syndrome (BrS) and progressive cardiac conduction defect (PCCD) are associated respectively with diffuse and discrete alterations in conduction pathways affected by ageing and sex. This study assessed for contributions of such processes to the mechanism of conduction changes in Scn5a+/− and WT hearts stratified by age (3 and 12 months) and sex. In vivo electrocardiographic chest-lead assessment demonstrated greater incidences of bundle branch block in all Scn5a+/− mice compared to WT. Frequency analysis of right ventricular (RV) epicardial activation obtained from a 64-channel multi-electrode array demonstrated greater prominence of late conducting components in Scn5a+/− compared to WT male, and in male compared to female Scn5a+/− following stratification by genotype and sex. Similar differences were observed between old male Scn5a+/− and young male Scn5a+/−, old female Scn5a+/−, and old male WT, following stratification by genotype, age and sex. These findings directly correlated with histomorphometric assessment of regional fibrosis in both septa and free walls preferentially involving the RV. We demonstrate complex alterations in conduction distributions suggesting a conversion of normal to slow-conducting tissue, modulated by ageing and sex, coupled with fibrosis in Scn5a+/− hearts. These features suggest an overlap between pathophysiological processes related to BrS and PCCD in Scn5a+/− hearts.
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Affiliation(s)
- Kamalan Jeevaratnam
- Physiological Laboratory, University of Cambridge, Downing Street, Cambridge CB2 3EG, United Kingdom.
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32
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Behr ER, January C, Schulze-Bahr E, Grace AA, Kääb S, Fiszman M, Gathers S, Buckman S, Youssef A, Pirmohamed M, Roden D. The International Serious Adverse Events Consortium (iSAEC) phenotype standardization project for drug-induced torsades de pointes. Eur Heart J 2012; 34:1958-63. [PMID: 22752616 DOI: 10.1093/eurheartj/ehs172] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Affiliation(s)
- Elijah R Behr
- Cardiovascular Research Center, St George's University of London, London SW17 0RE, UK.
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33
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Guzadhur L, Jiang W, Pearcey SM, Jeevaratnam K, Duehmke RM, Grace AA, Lei M, Huang CLH. The Age-dependence of atrial arrhythmogenicity in Scn5a+/−murine hearts reflects alterations in action potential propagation and recovery. Clin Exp Pharmacol Physiol 2012; 39:518-27. [DOI: 10.1111/j.1440-1681.2012.05706.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Laila Guzadhur
- Physiological Laboratory; University of Cambridge; Cambridge; UK
| | - Wenhui Jiang
- Medical College of Xi'an Jiaotong University; Xi'an; China
| | - Sarah M Pearcey
- Physiological Laboratory; University of Cambridge; Cambridge; UK
| | | | - Rudy M Duehmke
- Physiological Laboratory; University of Cambridge; Cambridge; UK
| | - Andrew A Grace
- Department of Biochemistry; University of Cambridge; Cambridge; UK
| | - Ming Lei
- Institute of Cardiovascular Sciences; University of Manchester; Manchester; UK
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Martin CA, Siedlecka U, Kemmerich K, Lawrence J, Cartledge J, Guzadhur L, Brice N, Grace AA, Schwiening C, Terracciano CM, Huang CLH. E Right ventricular origin of arrhythmias in Scn5a+/− mice is due to reduced Na+ and higher K+ channel expression and function. Heart 2012. [DOI: 10.1136/heartjnl-2012-301877a.5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Musumeci M, Maccari S, Sestili P, Signore M, Molinari P, Ambrosio C, Stati T, Colledge WH, Grace AA, Catalano L, Marano G. Propranolol enhances cell cycle-related gene expression in pressure overloaded hearts. Br J Pharmacol 2012; 164:1917-28. [PMID: 21615725 DOI: 10.1111/j.1476-5381.2011.01504.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND AND PURPOSE Cell cycle regulators are regarded as essential for cardiomyocyte hypertrophic growth. Given that the β-adrenoceptor antagonist propranolol blunts cardiomyocyte hypertrophic growth, we determined whether propranolol alters the expression of cell cycle-related genes in mouse hearts subjected to pressure overload. EXPERIMENTAL APPROACH Pressure overload was induced by transverse aortic constriction (TAC), whereas the expression levels of 84 cell cycle-related genes were assayed by real-time PCR. Propranolol (80 mg·kg(-1) ·day(-1) ) was administered in drinking water for 14 days. KEY RESULTS Two weeks after surgery, TAC caused a 46% increase in the left ventricular weight-to-body weight (LVW/BW) ratio but no significant changes in cell cycle gene expression. Propranolol, at plasma concentrations ranging from 10 to 140 ng·mL(-1) , blunted the LVW/BW ratio increase in TAC mice, while significantly increasing expression of 10 cell cycle genes including mitotic cyclins and proliferative markers such as Ki67. This increase in cell cycle gene expression was paralleled by a significant increase in the number of Ki67-positive non-cardiomyocyte cells as revealed by immunohistochemistry and confocal microscopy. β-Adrenoceptor signalling was critical for cell cycle gene expression changes, as genetic deletion of β-adrenoceptors also caused a significant increase in cyclins and Ki67 in pressure overloaded hearts. Finally, we found that metoprolol, a β(1) -adrenoceptor antagonist, failed to enhance cell cycle gene expression in TAC mice. CONCLUSIONS AND IMPLICATIONS Propranolol treatment enhances cell cycle-related gene expression in pressure overloaded hearts by increasing the number of cycling non-cardiomyocyte cells. These changes seem to occur via β(2) -adrenoceptor-mediated mechanisms.
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Affiliation(s)
- Marco Musumeci
- Department of Pharmacology, National Institute of Health, Rome, Italy
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Tse G, Hothi SS, Grace AA, Huang CLH. Ventricular arrhythmogenesis following slowed conduction in heptanol-treated, Langendorff-perfused mouse hearts. J Physiol Sci 2012; 62:79-92. [PMID: 22219003 PMCID: PMC10717265 DOI: 10.1007/s12576-011-0187-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2011] [Accepted: 11/28/2011] [Indexed: 10/14/2022]
Abstract
Arrhythmogenic effects of slowed action potential conduction produced by the gap junction and sodium-channel inhibitor heptanol (0.1-2 mM) were explored in Langendorff-perfused mouse hearts. Monophasic action potential recordings showed that 2 mM heptanol induced ventricular tachycardia in the absence of triggered activity arising from early or after-depolarizations during regular 8 Hz pacing and programmed electrical stimulation (PES). It also increased activation latencies and ventricular effective refractory periods (VERPs), but did not alter action potential duration (APD), thereby reducing local critical intervals for re-excitation given by APD(90) - VERP. Bipolar electrogram recordings showed that 2 mM heptanol increased electrogram duration (EGD) and ratios of EGDs obtained at the longest to those obtained at the shortest S1S2 intervals studied during PES, suggesting increased dispersion of conduction velocities. These findings show, for the first time in the mouse heart, that slowed conduction induces reversible arrhythmogenic effects despite repolarization abnormalities expected to reduce arrhythmogenicity.
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Affiliation(s)
- Gary Tse
- Section of Cardiovascular Biology, Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QW UK
| | - Sandeep S. Hothi
- The Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, CB2 3EG UK
- Addenbrooke’s Hospital, Hills Road, Cambridge, CB2 0QQ UK
| | - Andrew A. Grace
- Section of Cardiovascular Biology, Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QW UK
| | - Christopher L. -H. Huang
- Section of Cardiovascular Biology, Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QW UK
- The Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, CB2 3EG UK
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Wu J, Zhang Y, Zhang X, Cheng L, Lammers WJ, Grace AA, Fraser JA, Zhang H, Huang CLH, Lei M. Altered sinoatrial node function and intra-atrial conduction in murine gain-of-function Scn5a+/ΔKPQ hearts suggest an overlap syndrome. Am J Physiol Heart Circ Physiol 2012; 302:H1510-23. [PMID: 22287583 PMCID: PMC3330789 DOI: 10.1152/ajpheart.00357.2011] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Mutations in SCN5A, the gene encoding the pore-forming subunit of cardiac Na+ channels, cause a spectrum of arrhythmic syndromes. Of these, sinoatrial node (SAN) dysfunction occurs in patients with both loss- and gain-of-function SCN5A mutations. We explored for corresponding alterations in SAN function and intracardiac conduction and clarified possible mechanisms underlying these in an established mouse long QT syndrome type 3 model carrying a mutation equivalent to human SCN5A-ΔKPQ. Electrophysiological characterizations of SAN function in living animals and in vitro sinoatrial preparations were compared with cellular SAN and two-dimensional tissue models exploring the consequences of Scn5a+/ΔKPQ mutations. Scn5a+/ΔKPQ mice showed prolonged electrocardiographic QT and corrected QT intervals confirming long QT phenotypes. They showed frequent episodes of sinus bradycardia, sinus pause/arrest, and significantly longer sinus node recovery times, suggesting compromised pacemaker activity compared with wild-type mice. Electrocardiographic waveforms suggested depressed intra-atrial, atrioventricular node, and intraventricular conduction in Scn5a+/ΔKPQ mice. Isolated Scn5a+/ΔKPQ sinoatrial preparations similarly showed lower mean intrinsic heart rates and overall slower conduction through the SAN to the surrounding atrium than did wild-type preparations. Computer simulations of both single SAN cells as well as two-dimensional SAN-atrial models could reproduce the experimental observations of impaired pacemaker and sinoatrial conduction in terms of changes produced by both augmented tail and reduced total Na+ currents, respectively. In conclusion, the gain-of-function long QT syndrome type 3 murine Scn5a+/ΔKPQ cardiac system, in overlap with corresponding features reported in loss-of-function Na+ channel mutations, shows compromised SAN pacemaker and conduction function explicable in modeling studies through a combination of augmented tail and reduced peak Na+ currents.
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Affiliation(s)
- Jingjing Wu
- Department of Cardiovascular Diseases, Union Hospital, Huazhong University of Sciences and Technology, Wuhan, Peoples' Republic of China
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Gurung IS, Medina-Gomez G, Kis A, Baker M, Velagapudi V, Neogi SG, Campbell M, Rodriguez-Cuenca S, Lelliott C, McFarlane I, Oresic M, Grace AA, Vidal-Puig A, Huang CLH. Deletion of the metabolic transcriptional coactivator PGC1β induces cardiac arrhythmia. Cardiovasc Res 2011; 92:29-38. [PMID: 21632884 PMCID: PMC3172981 DOI: 10.1093/cvr/cvr155] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Revised: 05/17/2011] [Accepted: 05/26/2011] [Indexed: 01/23/2023] Open
Abstract
AIMS Peroxisome proliferator-activated receptor-γ coactivators PGC1α and PGC1β modulate mitochondrial biogenesis and energy homeostasis. The function of these transcriptional coactivators is impaired in obesity, insulin resistance, and type 2 diabetes. We searched for transcriptomic, lipidomic, and electrophysiological alterations in PGC1β(-/-) hearts potentially associated with increased arrhythmic risk in metabolic diseases. METHODS AND RESULTS Microarray analysis in mouse PGC1β(-/-) hearts confirmed down-regulation of genes related to oxidative phosphorylation and the electron transport chain and up-regulation of hypertrophy- and hypoxia-related genes. Lipidomic analysis showed increased levels of the pro-arrhythmic and pro-inflammatory lipid, lysophosphatidylcholine. PGC1β(-/-) mouse electrocardiograms showed irregular heartbeats and an increased incidence of polymorphic ventricular tachycardia following isoprenaline infusion. Langendorff-perfused PGC1β(-/-) hearts showed action potential alternans, early after-depolarizations, and ventricular tachycardia. PGC1β(-/-) ventricular myocytes showed oscillatory resting potentials, action potentials with early and delayed after-depolarizations, and burst firing during sustained current injection. They showed abnormal diastolic Ca(2+) transients, whose amplitude and frequency were increased by isoprenaline, and Ca(2+) currents with negatively shifted inactivation characteristics, with increased window currents despite unaltered levels of CACNA1C RNA transcripts. Inwardly and outward rectifying K(+) currents were all increased. Quantitiative RT-PCR demonstrated increased SCN5A, KCNA5, RYR2, and Ca(2+)-calmodulin dependent protein kinase II expression. CONCLUSION PGC1β(-/-) hearts showed a lysophospholipid-induced cardiac lipotoxicity and impaired bioenergetics accompanied by an ion channel remodelling and altered Ca(2+) homeostasis, converging to produce a ventricular arrhythmic phenotype particularly during adrenergic stress. This could contribute to the increased cardiac mortality associated with both metabolic and cardiac disease attributable to lysophospholipid accumulation.
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Affiliation(s)
- Iman S. Gurung
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3EG, UK
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, UK
| | - Gema Medina-Gomez
- Metabolic Research Laboratories, University of Cambridge, Level 4, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, CB2 0QQ, UK
| | - Adrienn Kis
- Metabolic Research Laboratories, University of Cambridge, Level 4, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, CB2 0QQ, UK
| | - Michael Baker
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, UK
| | - Vidya Velagapudi
- VTT Technical Research Centre of Finland, Tietotie 2, PO Box 1000, Espo,Finland
| | - Sudeshna Guha Neogi
- Genomics CoreLab, NIHR-Cambridge Biomedical Research Centre, University of Cambridge, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, UK
| | - Mark Campbell
- Metabolic Research Laboratories, University of Cambridge, Level 4, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, CB2 0QQ, UK
| | - Sergio Rodriguez-Cuenca
- Metabolic Research Laboratories, University of Cambridge, Level 4, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, CB2 0QQ, UK
| | - Christopher Lelliott
- Metabolic Research Laboratories, University of Cambridge, Level 4, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, CB2 0QQ, UK
| | - Ian McFarlane
- Genomics CoreLab, NIHR-Cambridge Biomedical Research Centre, University of Cambridge, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, UK
| | - Matej Oresic
- VTT Technical Research Centre of Finland, Tietotie 2, PO Box 1000, Espo,Finland
| | - Andrew A. Grace
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, UK
| | - Antonio Vidal-Puig
- Metabolic Research Laboratories, University of Cambridge, Level 4, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, CB2 0QQ, UK
| | - Christopher L.-H. Huang
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3EG, UK
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, UK
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Martin CA, Grace AA, Huang CLH. Refractory dispersion promotes conduction disturbance and arrhythmias in a Scn5a (+/-) mouse model. Pflugers Arch 2011; 462:495-504. [PMID: 21779762 PMCID: PMC3170477 DOI: 10.1007/s00424-011-0989-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2011] [Revised: 06/10/2011] [Accepted: 06/15/2011] [Indexed: 11/29/2022]
Abstract
Accentuated right ventricular (RV) gradients in action potential duration (APD) have been implicated in the arrhythmogenicity observed in Brugada syndrome in studies assuming that ventricular effective refractory periods (VERPs) vary in concert with APDs. The present experiments use a genetically modified mouse model to explore spatial heterogeneities in VERP that in turn might affect conduction velocity, thereby causing arrhythmias. Activation latencies, APDs and VERPs recorded during programmed S1S2 protocols were compared in RV and left ventricular (LV) epicardia and endocardia of Langendorff-perfused wild-type (WT) and Scn5a+/− hearts. Scn5a+/− and WT hearts showed similar patterns of shorter VERPs in RV than LV epicardia, and in epicardia than endocardia. However, Scn5a+/− hearts showed longer VERPs, despite shorter APD90s, than WT in all regions examined. The pro- and anti-arrhythmic agents flecainide and quinidine increased regional VERPs despite respectively decreasing and increasing the corresponding APD90s particularly in Scn5a+/− RV epicardia. In contrast, Scn5a+/− hearts showed greater VERP gradients between neighbouring regions, particularly RV transmural gradients, than WT (9.1 ± 1.1 vs. 5.7 ± 0.5 ms, p < 0.05, n = 12). Flecainide increased (to 21 ± 0.9 ms, p < 0.05, n = 6) but quinidine decreased (to 4.5 ± 0.5 ms, p < 0.05, n = 6) these gradients, particularly across the Scn5a+/− RV. Finally, Scn5a+/− hearts showed greater conduction slowing than WT following S2 stimuli, particularly with flecainide administration. Rather than arrhythmogenesis resulting from increased transmural repolarization gradients in an early, phase 2, reentrant excitation mechanism, the present findings implicate RV VERP gradients in potential reentrant mechanisms involving impulse conduction slowed by partial refractoriness.
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Affiliation(s)
- Claire A Martin
- Physiological Laboratory, University of Cambridge, Downing Site, Cambridge, CB2 3EG, UK.
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Zumhagen S, Grace AA, O'Connor S, Löher A, Köbe J, Eckardt L, Schulze-Bahr E. Totally subcutaneous implantable cardioverter defibrillator with an alternative, right parasternal, electrode placement. Pacing Clin Electrophysiol 2011; 35:e254-7. [PMID: 21401656 DOI: 10.1111/j.1540-8159.2011.03043.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The totally subcutaneous implantable cardioverter-defibrillator (S-ICD) is an entirely novel defibrillation device that avoids the direct contact of device electrodes with the heart and the cardiovascular system. Here, we present a particular case of a young woman with congenital long-QT syndrome in which we implanted the electrode alternatively, right parasternally. This decision was based on the thoracic anatomy of the patient and on findings of a model of S-ICD electrodes in an adult torso. In conclusion, in some patients an alternative subcutaneous electrode position may be carefully considered but should not be taken to outweigh the standard left-sided placement.
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Affiliation(s)
- Sven Zumhagen
- Institute for Genetics of Heart Diseases, University Hospital Münster, Münster, Germany.
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Abstract
Repolarization Gradients in Brugada Syndrome.Introduction: Brugada syndrome (BrS) is associated with loss of Na+ channel function and increased risks of a ventricular tachycardia exacerbated by flecainide but reduced by quinidine. Previous studies in nongenetic models have implicated both altered conduction times and repolarization gradients in this arrhythmogenicity. We compared activation latencies and spatial differences in action potential recovery between different ventricular regions in a murine Scn5a+/− BrS model, and investigated the effect of flecainide and quinidine upon these. Methods and Results: Langendorff-perfused wild-type and Scn5a+/− hearts were subjected to regular pacing and a combination of programmed electrical stimulation techniques. Monophasic action potentials were recorded from the right (RV) and left ventricular (LV) epicardium and endocardium before and following flecainide (10 μM) or quinidine (5 μM) treatment, and activation latencies measured. Transmural repolarization gradients were then calculated from the difference between neighboring endocardial and epicardial action potential durations (APDs). Scn5a+/− hearts showed decreased RV epicardial APDs, accentuating RV, but not LV, transmural gradients. This correlated with increased arrhythmic tendencies compared with wild-type. Flecainide increased RV transmural gradients, while quinidine decreased them, in line with their respective pro- and antiarrhythmic effects. In contrast, Scna5+/− hearts showed slowed conduction times in both RV and LV, exacerbated not only by flecainide but also by quinidine, in contrast to their differing effects on arrhythmogenesis. Conclusion: We use a murine genetic model of BrS to systematically analyze LV and RV action potential kinetics for the first time. This establishes a key role for accentuated transmural gradients, specifically in the RV, in its arrhythmogenicity. (J Cardiovasc Electrophysiol, Vol. 21, pp. 1153-1159)
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Affiliation(s)
- Claire A Martin
- Physiological Laboratory, University of Cambridge, Downing Site, Cambridge, United Kingdom.
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Martin CA, Guzadhur L, Grace AA, Lei M, Huang CLH. Mapping of reentrant spontaneous polymorphic ventricular tachycardia in a Scn5a+/- mouse model. Am J Physiol Heart Circ Physiol 2011; 300:H1853-62. [PMID: 21378142 PMCID: PMC3094090 DOI: 10.1152/ajpheart.00034.2011] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Two major mechanisms have been postulated for the arrhythmogenic tendency observed in Brugada Syndrome (BrS): delays in conduction or increased heterogeneities in repolarization. We use a contact mapping system to directly investigate the interacting roles of these two mechanisms in arrhythmogenesis using a genetic murine model for BrS for the first time. Electrograms were obtained from a multielectrode recording array placed against the left ventricle and right ventricle (RV) of spontaneously beating Langendorff-perfused wild type (WT) and Scn5a+/− mouse hearts. Scn5a+/− hearts showed activation waves arriving at the epicardial surface consistent with slowed conduction, which was exacerbated in the presence of flecainide. Lines of conduction block across the RV resulting from premature ventricular beats led to the formation of reentrant circuits and polymorphic ventricular tachycardia. WT hearts showed an inverse relationship between activation times and activation recovery intervals measured at the epicardial surface, which resulted in synchronicity of repolarization times. In contrast, Scn5a+/− hearts, despite having smaller mean activation recovery intervals, demonstrated a greater heterogeneity compared with WT. Isochronal maps showed that their normal activation recovery interval gradients at the epicardial surface were disrupted, leading to heterogeneity in repolarization times. We thus directly demonstrate the initiation of arrhythmia in the RV of Scn5a+/− hearts. This occurs as a result of the combination of repolarization heterogeneities leading to lines of conduction block and unidirectional conduction, with conduction slowing allowing the formation of reentrant circuits. The repolarization heterogeneities may also be responsible for the changing pattern of block, leading to the polymorphic character of the resulting ventricular tachycardia.
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Affiliation(s)
- Claire A Martin
- Physiological Laboratory, University of Cambridge, Cambridge, UK.
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Jeevaratnam K, Poh Tee S, Zhang Y, Rewbury R, Guzadhur L, Duehmke R, Grace AA, Lei M, Huang CLH. Delayed conduction and its implications in murine Scn5a(+/-) hearts: independent and interacting effects of genotype, age, and sex. Pflugers Arch 2010; 461:29-44. [PMID: 21127902 PMCID: PMC3016216 DOI: 10.1007/s00424-010-0906-1] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2010] [Revised: 10/29/2010] [Accepted: 11/12/2010] [Indexed: 11/28/2022]
Abstract
We explored for relationships between SCN5A haploinsufficiency, implicated in clinical arrhythmogenicity, and right ventricular (RV) conduction disorders in Langendorff-perfused, male and female, and young (3 months) and old (>12 month old) Scn5a+/− and wild type (WT) hearts. The investigated conditions of genotype, age, and sex affected latencies but not repolarization time courses of RV monophasic action potentials. This prompted examination of the patterns of RV epicardial activation, its dispersion, and their interrelationships as possible arrhythmic mechanisms using a 64-channel, multi-electrode array. Mean ventricular activation times (T*MEAN), spatial dispersions (D*S) between recording channels/cardiac cycle, and maximum activation times (T*MAX) representing the slowest possible conduction in any given heart were all higher in old male Scn5a+/− compared with young male and old female Scn5a+/− and old male WT. Temporal dispersions (D*T) of recording channels were similarly higher in old male Scn5a+/− compared with old male WT. All groupings of D*T, D*S, and T*MAX nevertheless linearly correlated with T*MEAN, with indistinguishable slopes. The variates explored thus influence D*T, D*S, and T*MAX through actions on T*MEAN. These findings in turn correlated with increased levels of fibrosis in young male, young female, and old male Scn5a+/− compared with the corresponding WTs. We thus demonstrate for the first time independent and interacting effects of genotype, age, and sex on epicardial conduction and its dispersions at least partially attributable to fibrotic change, resulting in the greatest effects in old male Scn5a+/− in an absence of alterations in repolarization time courses. This directly implicates altered depolarization in the clinical arrhythmogenicity associated with Scn5a+/−.
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Affiliation(s)
- Kamalan Jeevaratnam
- Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, UK.
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Abstract
Progressive cardiac conduction disease (PCCD), a source of considerable morbidity, comprises a heterogeneous group of conditions resulting from genetic predisposition, environmental modifiers, and other physiologic determinants, including aging. The genetic factors include numerous mutations and variants within the cardiac sodium channel gene, SCN5A. The electrocardiographic phenotype has variable penetrance and is associated with appearances ranging from an isolated conduction disorder to an association with tachyarrhythmias and clinically significant cardiomyopathy. A heterozygotic Scn5a mouse model provides evidence that PCCD may lead to cardiac remodeling consistent with clinical observations in addition to slowing of intracardiac conduction. PCCD has also been associated with the altered expression of genes encoding other proteins involved in impulse propagation, including those responsible for Ca2+- activated ion channels and cytoskeletal components, both in the presence or absence of structural abnormalities.
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Affiliation(s)
- Claire A Martin
- The Physiology Department, University of Cambridge, Downing Site, Cambridge CB2 3EG, UK
| | - Christopher L-H Huang
- The Physiology Department, University of Cambridge, Downing Site, Cambridge CB2 3EG, UK
| | - Andrew A Grace
- Department of Biochemistry, University of Cambridge, Downing Site, CB2 1QW, UK; Department of Cardiology, Papworth Hospital, Cambridge CB23 3RE, UK
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Martin CA, Grace AA, Huang CLH. Spatial and temporal heterogeneities are localized to the right ventricular outflow tract in a heterozygotic Scn5a mouse model. Am J Physiol Heart Circ Physiol 2010; 300:H605-16. [PMID: 21097662 PMCID: PMC3044044 DOI: 10.1152/ajpheart.00824.2010] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Ventricular tachycardia (VT) in Brugada Syndrome patients often originates in the right ventricular outflow tract (RVOT). We explore the physiological basis for this observation using murine whole heart preparations. Ventricular bipolar electrograms and monophasic action potentials were recorded from seven epicardial positions in Langendorff-perfused wild-type and Scn5a+/− hearts. VT first appeared in the RVOT, implicating it as an arrhythmogenic focus in Scn5a+/− hearts. RVOTs showed the greatest heterogeneity in refractory periods, response latencies, and action potential durations, and the most fractionated electrograms. However, incidences of concordant alternans in dynamic pacing protocol recordings were unaffected by the Scn5a+/− mutation or pharmacological intervention. Conversely, particularly at the RVOT, Scn5a+/− hearts showed earlier and more frequent transitions into discordant alternans. This was accentuated by flecainide, but reduced by quinidine, in parallel with their respective pro- and anti-arrhythmic effects. Discordant alternans preceded all episodes of VT. The RVOT of Scn5a+/− hearts also showed steeper restitution curves, with the diastolic interval at which the gradient equaled one strongly correlating with the diastolic interval at which discordant alternans commenced. We attribute the arrhythmic tendency within the RVOT to the greater spatial heterogeneities in baseline electrophysiological properties. These, in turn, give rise to a tendency to drive concordant alternans phenomena into an arrhythmogenic discordant alternans. Our findings may contribute to future work investigating possible pharmacological treatments for a disease in which the current mainstay of treatment is implantable cardioverter defibrillator implantation.
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Affiliation(s)
- Claire A Martin
- Physiological Laboratory, Department of Biochemistry, University of Cambridge, Downing Site, Cambridge CB2 3EG, UK.
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Sabir IN, Ma N, Jones VJ, Goddard CA, Zhang Y, Kalin A, Grace AA, Huang CLH. Alternans in genetically modified langendorff-perfused murine hearts modeling catecholaminergic polymorphic ventricular tachycardia. Front Physiol 2010; 1:126. [PMID: 21423368 PMCID: PMC3059940 DOI: 10.3389/fphys.2010.00126] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2010] [Accepted: 07/29/2010] [Indexed: 11/23/2022] Open
Abstract
The relationship between alternans and arrhythmogenicity was studied in genetically modified murine hearts modeling catecholaminergic polymorphic ventricular tachycardia (CPVT) during Langendorff perfusion, before and after treatment with catecholamines and a β-adrenergic antagonist. Heterozygous (RyR2p/s) and homozygous (RyR2s/s) RyR2-P2328S hearts, and wild-type (WT) controls, were studied before and after treatment with epinephrine (100 nM and 1 μM) and propranolol (100 nM). Monophasic action potential recordings demonstrated significantly greater incidences of arrhythmia in RyR2p/s and RyR2s/s hearts as compared to WTs. Arrhythmogenicity in RyR2s/s hearts was associated with alternans, particularly at short baseline cycle lengths. Both phenomena were significantly accentuated by treatment with epinephrine and significantly diminished by treatment with propranolol, in full agreement with clinical expectations. These changes took place, however, despite an absence of changes in mean action potential durations, ventricular effective refractory periods or restitution curve characteristics. Furthermore pooled data from all hearts in which arrhythmia occurred demonstrated significantly greater alternans magnitudes, but similar restitution curve slopes, to hearts that did not demonstrate arrhythmia. These findings thus further validate the RyR2-P2328S murine heart as a model for human CPVT, confirming an alternans phenotype in common with murine genetic models of the Brugada syndrome and the congenital long-QT syndrome type 3. In contrast to these latter similarities, however, this report demonstrates the dissociation of alternans from changes in the properties of restitution curves for the first time in a murine model of a human arrhythmic syndrome.
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Affiliation(s)
- Ian N Sabir
- Physiological Laboratory, Department of Physiology, Development and Neuroscience, University of Cambridge Cambridge, UK.
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Matthews GDK, Martin CA, Grace AA, Zhang Y, Huang CLH. Regional variations in action potential alternans in isolated murine Scn5a (+/-) hearts during dynamic pacing. Acta Physiol (Oxf) 2010; 200:129-46. [PMID: 20384594 DOI: 10.1111/j.1748-1716.2010.02138.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
AIM clinical observations suggest that alternans in action potential (AP) characteristics presages breakdown of normal ordered cardiac electrical activity culminating in ventricular arrhythmogenesis. We compared such temporal nonuniformities in monophasic action potential (MAP) waveforms in left (LV) and right ventricular (RV) epicardia and endocardia of Langendorff-perfused murine wild-type (WT), and Scn5a(+/-) hearts modelling Brugada syndrome (BrS) for the first time. METHODS a dynamic pacing protocol imposed successively incremented steady pacing rates between 5.5 and 33 Hz. A signal analysis algorithm detected sequences of >10 beats showing alternans. Results were compared before and following the introduction of flecainide (10 microm) and quinidine (5 microm) known to exert pro- and anti-arrhythmic effects in BrS. RESULTS sustained and transient amplitude and duration alternans were both frequently followed by ventricular ectopic beats and ventricular tachycardia or fibrillation. Diastolic intervals (DIs) that coincided with onsets of transient (tr) or sustained (ss) alternans in MAP duration (DI*) and amplitude (DI') were determined. Kruskal-Wallis tests followed by Bonferroni-corrected Mann-Whitney U-tests were applied to these DI results sorted by recording site, pharmacological conditions or experimental populations. WT hearts showed no significant heterogeneities in any DI. Untreated Scn5a (+/-) hearts showed earlier onsets of transient but not sustained duration alternans in LV endocardium compared with RV endocardium or LV epicardium. Flecainide administration caused earlier onsets of both transient and sustained duration alternans selectively in the RV epicardium in the Scn5a (+/-) hearts. CONCLUSION these findings in a genetic model thus implicate RV epicardial changes in the arrhythmogenicity produced by flecainide challenge in previously asymptomatic clinical BrS.
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Affiliation(s)
- G D K Matthews
- Physiological Laboratory, University of Cambridge, Cambridge
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Jeevaratnam K, Zhang Y, Guzadhur L, Duehmke RM, Lei M, Grace AA, Huang CLH. Differences in sino-atrial and atrio-ventricular function with age and sex attributable to the Scn5a+/- mutation in a murine cardiac model. Acta Physiol (Oxf) 2010; 200:23-33. [PMID: 20331542 DOI: 10.1111/j.1748-1716.2010.02110.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIM To investigate the interacting effects of age and sex on electrocardiographic (ECG) features of Scn5a(+/-) mice modelling Brugada syndrome. METHODS Recordings were performed on anaesthetized wild-type (WT) and Scn5a(+/-) mice and differences attributable to these risk factors statistically stratified. RESULTS Scn5a(+/-) exerted sex-dependent effects upon sino-atrial function that only became apparent with age. RR intervals were greater in old male than in old female Scn5a(+/-). Atrio-ventricular (AV) conduction was slower in young female mice, whether WT and Scn5a(+/-), than the corresponding young male WT and Scn5a(+/-). However, PR intervals lengthened with age in male but not in female Scn5a(+/-) giving the greatest PR intervals in old male Scn5a(+/-) compared with either old male WT or young male Scn5a(+/-) mice. In contrast, PR intervals were similar in old female Scn5a(+/-) and in old female WT. QTc was prolonged in Scn5a(+/-) compared with WT, and female Scn5a(+/-) compared with female WT. Age-dependent alterations in durations of ventricular repolarization relative to WT affected male but not female Scn5a(+/-). Thus, T-wave durations were greater in old male Scn5a(+/-) compared with old male WT, but indistinguishable between old female Scn5a(+/-) and old female WT. Finally, analysis for combined interactions of genotype, age and sex demonstrated no effects on P wave and QRS durations and QTc intervals. CONCLUSION We demonstrate for the first time that age, sex and genotype exert both independent and interacting ECG effects. The latter suggest alterations in cardiac pacemaker function, atrio-ventricular conduction and ventricular repolarization greatest in ageing male Scn5a(+/-).
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Affiliation(s)
- K Jeevaratnam
- Physiological Laboratory, University of Cambridge, Cambridge, UK
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Dautova Y, Zhang Y, Grace AA, Huang CLH. Experimental Physiology -Research Paper: Atrial arrhythmogenic properties in wild-type andScn5a+/− murine hearts. Exp Physiol 2010; 95:994-1007. [DOI: 10.1113/expphysiol.2010.053868] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Martin CA, Zhang Y, Grace AA, Huang CLH. In vivo studies of Scn5a+/- mice modeling Brugada syndrome demonstrate both conduction and repolarization abnormalities. J Electrocardiol 2010; 43:433-9. [PMID: 20638671 PMCID: PMC3712183 DOI: 10.1016/j.jelectrocard.2010.05.015] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2010] [Indexed: 12/02/2022]
Abstract
Objectives We investigate the extent to which the electrocardiographic (ECG) properties of intact Scn5a+/− mice reproduce the corresponding clinical Brugada syndrome phenotype and use this model to investigate the role of conduction and repolarization abnormalities in the arrhythmogenic mechanism. Methods and Results The ECGs were obtained from anesthetized wild-type and Scn5a+/− mice, before and after administration of the known pro- and antiarrhythmic agents flecainide and quinidine. The ECG intervals were measured and their dispersions calculated. Scn5a+/− hearts showed ventricular arrhythmias, ST elevation, and conduction disorders including increased QT dispersion, accentuated by flecainide. Quinidine did not cause ventricular arrhythmias but exerted variable effects on ST segments and worsened conduction abnormalities. Conclusions The ECG features in an Scn5a+/− mouse establish it as a suitable model for Brugada syndrome and demonstrate abnormal conduction and repolarization phenomena. Altered QT dispersion, taken to indicate increased transmural repolarization gradients, may be useful in clinical risk stratification.
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Affiliation(s)
- Claire A Martin
- Physiological Laboratory, University of Cambridge, Cambridge, United Kingdom.
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