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Jelvehgaran P, O'Hara R, Prakosa A, Chrispin J, Boink GJJ, Trayanova N, Coronel R, Oostendorp T. Computational Re-Entry Vulnerability Index Mapping to Guide Ablation in Patients With Post-Myocardial Infarction Ventricular Tachycardia. JACC Clin Electrophysiol 2022:S2405-500X(22)00848-9. [PMID: 36752477 DOI: 10.1016/j.jacep.2022.10.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 09/07/2022] [Accepted: 10/03/2022] [Indexed: 12/02/2022]
Abstract
BACKGROUND Ventricular tachycardias (VTs) in patients with myocardial infarction (MI) are often treated with catheter ablation. However, the VT induction during this procedure does not always identify all of the relevant activation pathways or may not be possible or tolerated. The re-entry vulnerability index (RVI) quantifies regional activation-repolarization differences and can detect multiple regions susceptible to re-entry without the need to induce the arrhythmia. OBJECTIVES This study aimed to further develop and validate the RVI mapping in patient-specific computational models of post-MI VTs. METHODS Cardiac magnetic resonance imaging data from 4 patients with post-MI VTs were used to induce VTs in a computational electrophysiological model by pacing. The RVI map of a premature beat in each patient model was used to guide virtual ablations. We compared our results with those of clinical ablation in the same patients. RESULTS Single-site virtual RVI-guided ablation prevented VT induction in 3 of 9 cases. Multisite virtual ablations guided by RVI mapping successfully prevented re-entry in all cases (9 of 9). Overall, virtual ablation required 15-fold fewer ablation sites (235.5 ± 97.4 vs 17 ± 6.8) and 2-fold less ablation volume (5.34 ± 1.79 mL vs 2.11 ± 0.65 mL) than the clinical ablation. CONCLUSIONS RVI mapping allows localization of multiple regions susceptible to re-entry and may help guide VT ablation. RVI mapping does not require the induction of arrhythmia and may result in less ablated myocardial volumes with fewer ablation sites.
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Gottlieb LA, Dekker LRC, Coronel R. The Blinding Period Following Ablation Therapy for Atrial Fibrillation: Proarrhythmic and Antiarrhythmic Pathophysiological Mechanisms. JACC Clin Electrophysiol 2021; 7:416-430. [PMID: 33736761 DOI: 10.1016/j.jacep.2021.01.011] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 01/14/2021] [Accepted: 01/17/2021] [Indexed: 02/01/2023]
Abstract
Atrial fibrillation (AF) causes heart failure, ischemic strokes, and poor quality of life. The number of patients with AF is estimated to increase to 18 million in Europe in 2050. Pharmacological therapy does not cure AF in all patients. Ablative pulmonary vein isolation is recommended for patients with drug-resistant symptomatic paroxysmal AF but is successful in only about 60%. In patients in whom ablative therapy is successful on the long term, recurrence of AF may occur in the first weeks to months after pulmonary vein ablation. The early recurrence (or delayed cure) of AF is not understood but forms the basis for the generally accepted 3-month blinding (or blanking) period after ablation therapy, which is not included in the evaluation of the eventual success rate of the procedures. The underlying pathophysiological processes responsible for early recurrence and the delayed cure are unknown. The implicit assumption of the blinding period is that the AF mechanism in this period is different from the ablation-targeted AF mechanism (ectopy from the pulmonary veins). In this review, we evaluate the temporary and long-lasting pro- and antiarrhythmic effects of each of the pathophysiological processes and interventions (necrosis, ischemia, oxidative stress, edema, inflammation, autonomic nervous activity, tissue repair, mechanical remodeling, and use of antiarrhythmic drugs) occurring in the blinding period that can modulate AF mechanisms. We propose that stretch-reducing ablation scar is a permanent antiarrhythmic mechanism that develops during the blinding period and is the reason for delayed cure.
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Affiliation(s)
- Lisa A Gottlieb
- Electrophysiology and Heart Modelling Institute, University of Bordeaux, Pessac, France; Department of Experimental Cardiology, Amsterdam University Medical Centre, Academic Medical Centre, Amsterdam, the Netherlands
| | - Lukas R C Dekker
- Department of Electrical Engineering, University of Technology, Eindhoven, the Netherlands; Cardiology Department, Catharina Hospital, Eindhoven, the Netherlands.
| | - Ruben Coronel
- Electrophysiology and Heart Modelling Institute, University of Bordeaux, Pessac, France; Department of Experimental Cardiology, Amsterdam University Medical Centre, Academic Medical Centre, Amsterdam, the Netherlands
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Coronel R, Potse M, Haïssaguerre M, Derval N, Rivaud MR, Meijborg VMF, Cluitmans M, Hocini M, Boukens BJ. Why Ablation of Sites With Purkinje Activation Is Antiarrhythmic: The Interplay Between Fast Activation and Arrhythmogenesis. Front Physiol 2021; 12:648396. [PMID: 33833689 PMCID: PMC8021688 DOI: 10.3389/fphys.2021.648396] [Citation(s) in RCA: 5] [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: 12/31/2020] [Accepted: 03/03/2021] [Indexed: 12/27/2022] Open
Abstract
Ablation of sites showing Purkinje activity is antiarrhythmic in some patients with idiopathic ventricular fibrillation (iVF). The mechanism for the therapeutic success of ablation is not fully understood. We propose that deeper penetrance of the Purkinje network allows faster activation of the ventricles and is proarrhythmic in the presence of steep repolarization gradients. Reduction of Purkinje penetrance, or its indirect reducing effect on apparent propagation velocity may be a therapeutic target in patients with iVF.
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Affiliation(s)
- Ruben Coronel
- Department of Experimental Cardiology, Amsterdam Cardiovascular Sciences, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands.,IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, Bordeaux, France
| | - Mark Potse
- IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, Bordeaux, France.,UMR5251 Institut de mathématiques de Bordeaux, Talence, France.,Carmen Team, Inria Bordeaux - Sud-Ouest, Talence, France
| | - Michel Haïssaguerre
- IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, Bordeaux, France
| | - Nicolas Derval
- IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, Bordeaux, France
| | - Mathilde R Rivaud
- Department of Experimental Cardiology, Amsterdam Cardiovascular Sciences, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
| | - Veronique M F Meijborg
- Department of Experimental Cardiology, Amsterdam Cardiovascular Sciences, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
| | - Matthijs Cluitmans
- Department of Experimental Cardiology, Amsterdam Cardiovascular Sciences, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
| | - Mélèze Hocini
- IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, Bordeaux, France
| | - Bastiaan J Boukens
- Department of Medical Biology, Amsterdam Cardiovascular Sciences, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
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Campos FO, Orini M, Taggart P, Hanson B, Lambiase PD, Porter B, Rinaldi CA, Gill J, Bishop MJ. Characterizing the clinical implementation of a novel activation-repolarization metric to identify targets for catheter ablation of ventricular tachycardias using computational models. Comput Biol Med 2019; 108:263-275. [PMID: 31009930 PMCID: PMC6538827 DOI: 10.1016/j.compbiomed.2019.03.018] [Citation(s) in RCA: 7] [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] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Revised: 03/08/2019] [Accepted: 03/19/2019] [Indexed: 11/24/2022]
Abstract
Identification of targets for catheter ablation of ventricular tachycardias (VTs) remains a significant challenge. VTs are often driven by re-entrant circuits resulting from a complex interaction between the front (activation) and tail (repolarization) of the electrical wavefront. Most mapping techniques do not take into account the tissue repolarization which may hinder the detection of ablation targets. The re-entry vulnerability index (RVI), a recently proposed mapping procedure, incorporates both activation and repolarization times to uncover VT circuits. The method showed potential in a series of experiments, but it still requires further development to enable its incorporation into a clinical protocol. Here, in-silico experiments were conducted to thoroughly assess RVI maps constructed under clinically-relevant mapping conditions. Within idealized as well as anatomically realistic infarct models, we show that parameters of the algorithm such as the search radius can significantly alter the specificity and sensitivity of the RVI maps. When constructed on sparse grids obtained following various placements of clinical recording catheters, RVI maps can identify vulnerable regions as long as two electrodes were placed on both sides of the line of block. Moreover, maps computed during pacing without inducing VT can reveal areas of abnormal repolarization and slow conduction but not directly vulnerability. In conclusion, the RVI algorithm can detect re-entrant circuits during VT from low resolution mapping grids resembling the clinical setting. Furthermore, RVI maps may provide information about the underlying tissue electrophysiology to guide catheter ablation without the need of inducing potentially harmful VT during the clinical procedure. Finally, the ability of the RVI maps to identify vulnerable regions with specificity in high resolution computer models could potentially improve the prediction of optimal ablation targets of simulation-based strategies. Safe and accurate detection of targets for catheter ablation remains a challenge. We conducted a thorough assessment of the Re-entry Vulnerability Index (RVI). Parameters of the algorithm can alter the specificity and sensitivity of RVI maps. When constructed on sparse grids RVI maps could still detect arrhythmogenic sites. In absence of arrhythmia, RVI maps revealed abnormal sites, but not vulnerability.
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Affiliation(s)
- Fernando O Campos
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
| | - Michele Orini
- The Heart Hospital, University College London, London, United Kingdom; Institute of Cardiovascular Science, University College London, London, United Kingdom
| | - Peter Taggart
- The Heart Hospital, University College London, London, United Kingdom; Institute of Cardiovascular Science, University College London, London, United Kingdom
| | - Ben Hanson
- Department of Mechanical Engineering, University College London, London, United Kingdom
| | - Pier D Lambiase
- Institute of Cardiovascular Science, University College London, London, United Kingdom; Electrophysiology Department, Barts Heart Centre, St Bartholomew's Hospital, London, United Kingdom
| | - Bradley Porter
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom; Department of Cardiology, Guys and St Thomas' NHS Trust, London, United Kingdom
| | | | - Jaswinder Gill
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom; Department of Cardiology, Guys and St Thomas' NHS Trust, London, United Kingdom
| | - Martin J Bishop
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom. https://kclpure.kcl.ac.uk/portal/martin.bishop.html
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Boukens BJ, Walton R, Meijborg VM, Coronel R. Transmural electrophysiological heterogeneity, the T-wave and ventricular arrhythmias. Progress in Biophysics and Molecular Biology 2016; 122:202-14. [DOI: 10.1016/j.pbiomolbio.2016.05.009] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 04/21/2016] [Accepted: 05/03/2016] [Indexed: 01/05/2023]
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Hill YR, Child N, Hanson B, Wallman M, Coronel R, Plank G, Rinaldi CA, Gill J, Smith NP, Taggart P, Bishop MJ. Investigating a Novel Activation-Repolarisation Time Metric to Predict Localised Vulnerability to Reentry Using Computational Modelling. PLoS One 2016; 11:e0149342. [PMID: 26934736 PMCID: PMC4775046 DOI: 10.1371/journal.pone.0149342] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Accepted: 01/29/2016] [Indexed: 11/19/2022] Open
Abstract
Exit sites associated with scar-related reentrant arrhythmias represent important targets for catheter ablation therapy. However, their accurate location in a safe and robust manner remains a significant clinical challenge. We recently proposed a novel quantitative metric (termed the Reentry Vulnerability Index, RVI) to determine the difference between activation and repolarisation intervals measured from pairs of spatial locations during premature stimulation to accurately locate the critical site of reentry formation. In the clinic, the method showed potential to identify regions of low RVI corresponding to areas vulnerable to reentry, subsequently identified as ventricular tachycardia (VT) circuit exit sites. Here, we perform an in silico investigation of the RVI metric in order to aid the acquisition and interpretation of RVI maps and optimise its future usage within the clinic. Within idealised 2D sheet models we show that the RVI produces lower values under correspondingly more arrhythmogenic conditions, with even low resolution (8 mm electrode separation) recordings still able to locate vulnerable regions. When applied to models of infarct scars, the surface RVI maps successfully identified exit sites of the reentrant circuit, even in scenarios where the scar was wholly intramural. Within highly complex infarct scar anatomies with multiple reentrant pathways, the identified exit sites were dependent upon the specific pacing location used to compute the endocardial RVI maps. However, simulated ablation of these sites successfully prevented the reentry re-initiation. We conclude that endocardial surface RVI maps are able to successfully locate regions vulnerable to reentry corresponding to critical exit sites during sustained scar-related VT. The method is robust against highly complex and intramural scar anatomies and low resolution clinical data acquisition. Optimal location of all relevant sites requires RVI maps to be computed from multiple pacing locations.
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Affiliation(s)
- Yolanda R. Hill
- Department of Biomedical Engineering, Division of Imaging Sciences & Biomedical Engineering, King’s College London, London, United Kingdom
| | - Nick Child
- Department of Biomedical Engineering, Division of Imaging Sciences & Biomedical Engineering, King’s College London, London, United Kingdom
| | - Ben Hanson
- Department of Mechanical Engineering, University College London, London, United Kingdom
| | - Mikael Wallman
- Department of Systems and Data Analysis, Franhofer-Chalmers Centre, Gothenburg, Sweden
| | - Ruben Coronel
- Academic Medical Center, Amsterdam, Netherlands
- L’Institut de RYthmologieet de Modelisation Cardiaque (LIRYC), Fondation Universite Bordeaux, Bordeaux, France
| | - Gernot Plank
- Institute of Biophysics, Medical University of Graz, Graz, Austria
| | | | - Jaswinder Gill
- Department of Cardiology, Guys and St Thomas’ Hospital, London, United Kingdom
| | - Nicolas P. Smith
- Department of Biomedical Engineering, Division of Imaging Sciences & Biomedical Engineering, King’s College London, London, United Kingdom
- Department of Engineering, University of Auckland, Auckland, New Zealand
| | - Peter Taggart
- Department of Cardiovascular Sciences, University College London, London, United Kingdom
| | - Martin J. Bishop
- Department of Biomedical Engineering, Division of Imaging Sciences & Biomedical Engineering, King’s College London, London, United Kingdom
- * E-mail:
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Opthof T, Janse MJ, Meijborg VMF, Cinca J, Rosen MR, Coronel R. Dispersion in ventricular repolarization in the human, canine and porcine heart. Prog Biophys Mol Biol 2016; 120:222-35. [PMID: 26790342 DOI: 10.1016/j.pbiomolbio.2016.01.007] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Revised: 01/06/2016] [Accepted: 01/07/2016] [Indexed: 11/12/2022]
Abstract
Dispersion in repolarization is important for the genesis of the T wave, and for the induction of reentrant arrhtyhmias. Because the T wave differs across species our intent here is to review the epicardial, endocardial and transmural repolarization patterns contributing to repolarization in whole hearts from man, dog and pig. The major points we emphasize are: transmural repolarization time gradients are small and are directed from endocardium (early) to epicardium (late) in dog and human and from epicardium to endocardium in pig; the right ventricle tends to repolarize before the left ventricle and this difference is larger in dog than in pig; a negative relation between the activation times and the repolarization times is rare in man, and absent in dog and pig. Given the above, a large dispersion in repolarization between two myocardial areas does not lead to arrhythmias without a premature beat. Moreover, an arrhythmic substrate can be identified by a metric composed of activation times and repolarization times, the reentry vulnerability index, RVI.
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Affiliation(s)
- Tobias Opthof
- Department of Clinical and Experimental Cardiology, Heart Center Amsterdam, The Netherlands; Department of Medical Physiology, University Medical Center Utrecht, The Netherlands.
| | - Michiel J Janse
- Department of Clinical and Experimental Cardiology, Heart Center Amsterdam, The Netherlands
| | - Veronique M F Meijborg
- Department of Clinical and Experimental Cardiology, Heart Center Amsterdam, The Netherlands
| | - Juan Cinca
- Cardiology Service, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain
| | - Michael R Rosen
- Department of Pharmacology, College of Physicians and Surgeons, Columbia University, New York, USA
| | - Ruben Coronel
- Department of Clinical and Experimental Cardiology, Heart Center Amsterdam, The Netherlands; IHU Institut de Rythmologie en Modélisation Cardiaque, Fondation Bordeaux Université, France
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Child N, Bishop MJ, Hanson B, Coronel R, Opthof T, Boukens BJ, Walton RD, Efimov IR, Bostock J, Hill Y, Rinaldi CA, Razavi R, Gill J, Taggart P. An activation-repolarization time metric to predict localized regions of high susceptibility to reentry. Heart Rhythm 2015; 12:1644-53. [PMID: 25863160 DOI: 10.1016/j.hrthm.2015.04.013] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [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: 10/22/2014] [Indexed: 11/25/2022]
Abstract
BACKGROUND Initiation of reentrant ventricular tachycardia (VT) involves complex interactions between front and tail of the activation wave. Recent experimental work has identified the time interval between S2 repolarization proximal to a line of functional block and S2 activation at the adjacent distal side as a critical determinant of reentry. OBJECTIVES We hypothesized that (1) an algorithm could be developed to generate a spatial map of this interval ("reentry vulnerability index" [RVI]), (2) this would accurately identify a site of reentry without the need to actually induce the arrhythmia, and (3) it would be possible to generate an RVI map in patients during routine clinical procedures. METHODS An algorithm was developed that calculated RVI between all pairs of electrodes within a given radius. RESULTS The algorithm successfully identified the region with increased susceptibility to reentry in an established Langendorff pig heart model and the site of reentry and rotor formation in an optically mapped sheep ventricular preparation and computational simulations. The feasibility of RVI mapping was evaluated during a clinical procedure by coregistering with cardiac anatomy and physiology of a patient undergoing VT ablation. CONCLUSION We developed an algorithm to calculate a reentry vulnerability index from intervals between local repolarization and activation. The algorithm accurately identified the region of reentry in 2 animal models of functional reentry. The clinical application was demonstrated in a patient with VT and identified the area of reentry without the need of inducing the arrhythmia.
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Affiliation(s)
- Nicholas Child
- Division of Imaging Sciences, King's College London, London, United Kingdom.
| | - Martin J Bishop
- Division of Imaging Sciences, King's College London, London, United Kingdom
| | - Ben Hanson
- Department of Mechanical Engineering, University College London, London, United Kingdom
| | - Ruben Coronel
- Academic Medical Center, Amsterdam, The Netherlands; L'Institut de RYthmologieet de Modelisation Cardiaque (LIRYC), Fondation Université Bordeaux, Bordeaux, France
| | | | - Bastiaan J Boukens
- Department of Biomedical Engineering, George Washington University, Washington, DC
| | - Richard D Walton
- L'Institut de RYthmologieet de Modelisation Cardiaque (LIRYC), Fondation Université Bordeaux, Bordeaux, France; INSERM, Universite de Bordeaux, Centre Recherche, Cario-Thoracique de Bordeaux U1045, Bordeaux, France
| | - Igor R Efimov
- L'Institut de RYthmologieet de Modelisation Cardiaque (LIRYC), Fondation Université Bordeaux, Bordeaux, France; Department of Biomedical Engineering, George Washington University, Washington, DC; Department of Biomedical Engineering, Washington University, St Louis, Missouri
| | - Julian Bostock
- Department of Cardiology, Guy's and St Thomas' Hospital, London, United Kingdom
| | - Yolanda Hill
- Division of Imaging Sciences, King's College London, London, United Kingdom
| | | | - Reza Razavi
- Division of Imaging Sciences, King's College London, London, United Kingdom
| | - Jaswinder Gill
- Division of Imaging Sciences, King's College London, London, United Kingdom
| | - Peter Taggart
- Department of Cardiovascular Sciences, University College London, London, United Kingdom
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Opthof T, Sutton P, Coronel R, Wright S, Kallis P, Taggart P. The Association of Abnormal Ventricular Wall Motion and Increased Dispersion of Repolarization in Humans is Independent of the Presence of Myocardial Infarction. Front Physiol 2012; 3:235. [PMID: 22783201 PMCID: PMC3388480 DOI: 10.3389/fphys.2012.00235] [Citation(s) in RCA: 12] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2011] [Accepted: 06/11/2012] [Indexed: 11/13/2022] Open
Abstract
Abnormal ventricular wall motion is a strong clinical predictor of sudden, arrhythmic, cardiac death. Dispersion in repolarization is a prerequisite for the initiation of re-entrant arrhythmia. We hypothesize that regionally decreased wall motion is associated with heterogeneity of repolarization. We measured local activation times, activation-recovery intervals (ARIs, surrogate for action potential duration), and repolarization times using a multielectrode grid at nine segments on the left ventricular epicardium in 23 patients undergoing coronary artery surgery. Regional wall motion was simultaneously assessed using intraoperative transesophageal echocardiography. Three groups were discriminated: (1) Patients with normal wall motion (n = 11), (2) Patients with one or more hypokinetic segments (n = 6), (3) Patients with one or more akinetic or dyskinetic segments (n = 6). The average ARI was similar in all groups (251 ± 3.7 ms, ±SEM). Dispersion of ARIs between the nine segments was significantly increased in the hypokinetic (84 ± 7.4 ms, p < 0.005) and akinetic/dyskinetic group (94 ± 3.5 ms, p < 0.0005) compared with the normal group (49 ± 5.1 ms), independent from the presence of myocardial infarction. Repolarization heterogeneity occurred primarily in the normally contracting regions of the hearts with abnormal wall motion. An almost maximal increased dispersion of repolarization was observed when there was only a single hypokinetic segment. We conclude that inhomogeneous wall motion abnormality of even moderate severity is associated with increased repolarization inhomogeneity, independent from the presence of infarction.
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Affiliation(s)
- Tobias Opthof
- Experimental Cardiology Group, Center for Heart Failure Research, Academic Medical Center Amsterdam, Netherlands
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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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