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Qian S, Monaci S, Mendonca-Costa C, Campos F, Gemmell P, Zaidi HA, Rajani R, Whitaker J, Rinaldi CA, Bishop MJ. Additional coils mitigate elevated defibrillation threshold in right-sided implantable cardioverter defibrillator generator placement: a simulation study. Europace 2023; 25:euad146. [PMID: 37314196 PMCID: PMC10265967 DOI: 10.1093/europace/euad146] [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] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Accepted: 05/13/2023] [Indexed: 06/15/2023] Open
Abstract
AIMS The standard implantable cardioverter defibrillator (ICD) generator (can) is placed in the left pectoral area; however, in certain circumstances, right-sided cans may be required which may increase defibrillation threshold (DFT) due to suboptimal shock vectors. We aim to quantitatively assess whether the potential increase in DFT of right-sided can configurations may be mitigated by alternate positioning of the right ventricular (RV) shocking coil or adding coils in the superior vena cava (SVC) and coronary sinus (CS). METHODS AND RESULTS A cohort of CT-derived torso models was used to assess DFT of ICD configurations with right-sided cans and alternate positioning of RV shock coils. Efficacy changes with additional coils in the SVC and CS were evaluated. A right-sided can with an apical RV shock coil significantly increased DFT compared to a left-sided can [19.5 (16.4, 27.1) J vs. 13.3 (11.7, 19.9) J, P < 0.001]. Septal positioning of the RV coil led to a further DFT increase when using a right-sided can [26.7 (18.1, 36.1) J vs. 19.5 (16.4, 27.1) J, P < 0.001], but not a left-sided can [12.1 (8.1, 17.6) J vs. 13.3 (11.7, 19.9) J, P = 0.099). Defibrillation threshold of a right-sided can with apical or septal coil was reduced the most by adding both SVC and CS coils [19.5 (16.4, 27.1) J vs. 6.6 (3.9, 9.9) J, P < 0.001, and 26.7 (18.1, 36.1) J vs. 12.1 (5.7, 13.5) J, P < 0.001]. CONCLUSION Right-sided, compared to left-sided, can positioning results in a 50% increase in DFT. For right-sided cans, apical shock coil positioning produces a lower DFT than septal positions. Elevated right-sided can DFTs may be mitigated by utilizing additional coils in SVC and CS.
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Affiliation(s)
- Shuang Qian
- Department of Biomedical Engineering, School of Imaging Sciences and Biomedical Engineering, Kings College London, 4th North Wing, St Thomas’ Hospital, London SE1 7EH, UK
| | - Sofia Monaci
- Department of Biomedical Engineering, School of Imaging Sciences and Biomedical Engineering, Kings College London, 4th North Wing, St Thomas’ Hospital, London SE1 7EH, UK
| | - Caroline Mendonca-Costa
- Department of Biomedical Engineering, School of Imaging Sciences and Biomedical Engineering, Kings College London, 4th North Wing, St Thomas’ Hospital, London SE1 7EH, UK
| | - Fernando Campos
- Department of Biomedical Engineering, School of Imaging Sciences and Biomedical Engineering, Kings College London, 4th North Wing, St Thomas’ Hospital, London SE1 7EH, UK
| | - Philip Gemmell
- Department of Biomedical Engineering, School of Imaging Sciences and Biomedical Engineering, Kings College London, 4th North Wing, St Thomas’ Hospital, London SE1 7EH, UK
| | - Hassan A Zaidi
- Department of Biomedical Engineering, School of Imaging Sciences and Biomedical Engineering, Kings College London, 4th North Wing, St Thomas’ Hospital, London SE1 7EH, UK
| | - Ronak Rajani
- Department of Cardiology, Guy’s and St Thomas’ Hospital, Westminster Bridge Rd, London SE1 7EH, UK
| | - John Whitaker
- Department of Biomedical Engineering, School of Imaging Sciences and Biomedical Engineering, Kings College London, 4th North Wing, St Thomas’ Hospital, London SE1 7EH, UK
- Department of Cardiology, Guy’s and St Thomas’ Hospital, Westminster Bridge Rd, London SE1 7EH, UK
| | - Christopher A Rinaldi
- Department of Biomedical Engineering, School of Imaging Sciences and Biomedical Engineering, Kings College London, 4th North Wing, St Thomas’ Hospital, London SE1 7EH, UK
- Department of Cardiology, Guy’s and St Thomas’ Hospital, Westminster Bridge Rd, London SE1 7EH, UK
| | - Martin J Bishop
- Department of Biomedical Engineering, School of Imaging Sciences and Biomedical Engineering, Kings College London, 4th North Wing, St Thomas’ Hospital, London SE1 7EH, UK
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Qian S, Monaci S, Mendonca-Costa C, Campos F, Gemmell P, Zaidi S, Rajani R, Whitaker J, Rinaldi C, Bishop M. In-silico optimisation of ICD defibrillation efficacy by modifying lead/can configurations using a cohort of high-resolution whole-torso heart models. Europace 2022. [DOI: 10.1093/europace/euac053.449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Abstract
Funding Acknowledgements
Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Medical Research Council, UK
Background
ICD is an effective direct therapy against VT/VF by applying a strong electrical shock across the heart between the shocking coil and can. Conventionally, patients will have a shocking coil inside the right ventricle (RV) and a can at the upper left chest. However, due to infections or other conditions, the can may need to place towards the right chest. The placement of the RV coil may also vary in different cases, for example avoiding scar. However, it is unclear how defibrillation efficacy may be altered by these unavoidable modifications to conventional lead/can configurations and whether optimisation may be possible.
Purpose
To compare defibrillation efficacy of modifications of ICD configurations in a cohort of whole-torso models.
Methods
A cohort of 15 whole torso models was generated from high resolution CT data and contrast CT cardiac scans, including 5 dilated cardiomyopathy (DCM), 5 hypertrophic cardiomyopathy (HCM) and 5 structurally normal patients (Fig A). Transvenous ICDs were represented by a shocking coil inside the RV (near apex) and a (ground) can at the upper left chest as default settings. Configurations were then varied by moving the can to the right chest, moving the RV coil up the mid-septum or adding extra grounds (Superior Vena Cava (SVC) coil, coronary sinus (CS) coil (Fig A)). Defibrillation-strength shocks were applied to all models (Fig B). DFTs and mean electrical field were evaluated across the whole heart as well as specific LV, RV, RV insertion regions, along with overall impedance.
Results
Shifting the can from left to right significantly increased DFT for the whole heart (23 J vs 15 J, P=0.03) and LV (25 J vs 17 J, P=0.03) (Fig C) and reduced the mean electrical field. Moving the RV coil further up the septum did not significantly alter DFT (Fig D), but did reduce mean electrical field for all regions and reduce impedance significantly. Additional separate coils significantly reduced DFT for all regions (Fig D) by increasing mean electrical field, whilst adding both coils significantly reduced DFT the most (whole heart: 15 J vs 6 J, P=0.03) (Fig E). Impedance was increased significantly by adding SVC coil, but reduced significantly by adding CS coil. Adding both coils increased impedance slightly.
Conclusions
Although a right-sided can increases DFT by over 50%, additional leads (grounds) may mitigate this increase by increasing mean electrical field. Moving the RV coil closer to the mid-septum reduces DFT slightly, but also reduces mean electrical field and impedance significantly.
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Affiliation(s)
- S Qian
- King’s College London, London, United Kingdom of Great Britain & Northern Ireland
| | - S Monaci
- King’s College London, London, United Kingdom of Great Britain & Northern Ireland
| | - C Mendonca-Costa
- King’s College London, London, United Kingdom of Great Britain & Northern Ireland
| | - F Campos
- King’s College London, London, United Kingdom of Great Britain & Northern Ireland
| | - P Gemmell
- King’s College London, London, United Kingdom of Great Britain & Northern Ireland
| | - S Zaidi
- King’s College London, London, United Kingdom of Great Britain & Northern Ireland
| | - R Rajani
- Guy’s & St Thomas’ NHS Foundation Trust, London, United Kingdom of Great Britain & Northern Ireland
| | - J Whitaker
- Guy’s & St Thomas’ NHS Foundation Trust, London, United Kingdom of Great Britain & Northern Ireland
| | - C Rinaldi
- Guy’s & St Thomas’ NHS Foundation Trust, London, United Kingdom of Great Britain & Northern Ireland
| | - M Bishop
- King’s College London, London, United Kingdom of Great Britain & Northern Ireland
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Elliott MK, Costa CM, Whitaker J, Gemmell P, Mehta VS, Sidhu BS, Gould J, Williams SE, O'Neill M, Razavi R, Niederer S, Bishop MJ, Rinaldi CA. Effect of scar and pacing location on repolarization in a porcine myocardial infarction model. Heart Rhythm O2 2022; 3:186-195. [PMID: 35496454 PMCID: PMC9043407 DOI: 10.1016/j.hroo.2022.01.008] [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] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Background The effect of chronic ischemic scar on repolarization is unclear, with conflicting results from human and animal studies. An improved understanding of electrical remodeling within scar and border zone tissue may enhance substrate-guided ablation techniques for treatment of ventricular tachycardia. Computational modeling studies have suggested increased dispersion of repolarization during epicardial, but not endocardial, left ventricular pacing, in close proximity to scar. However, the effect of endocardial pacing near scar in vivo is unknown. Objective The purpose of this study was to investigate the effect of scar and pacing location on local repolarization in a porcine myocardial infarction model. Methods Six model pigs underwent late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) imaging followed by electroanatomic mapping of the left ventricular endocardium. LGE-CMR images were registered to the anatomic shell and scar defined by LGE. Activation recovery intervals (ARIs), a surrogate for action potential duration, and local ARI gradients were calculated from unipolar electrograms within areas of late gadolinium enhancement (aLGE) and healthy myocardium. Results There was no significant difference between aLGE and healthy myocardium in mean ARI (304.20 ± 19.44 ms vs 300.59 ± 19.22 ms; P = .43), ARI heterogeneity (23.32 ± 11.43 ms vs 24.85 ± 12.99 ms; P = .54), or ARI gradients (6.18 ± 2.09 vs 5.66 ± 2.32 ms/mm; P = .39). Endocardial pacing distance from scar did not affect ARI gradients. Conclusion Our findings suggest that changes in ARI are not an intrinsic property of surviving myocytes within scar, and endocardial pacing close to scar does not affect local repolarization.
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Affiliation(s)
- Mark K Elliott
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
- Department of Cardiology, Guy's and St Thomas' NHS Foundation Trust, London, United Kingdom
| | - Caroline Mendonca Costa
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
| | - John Whitaker
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
- Department of Cardiology, Guy's and St Thomas' NHS Foundation Trust, London, United Kingdom
| | - Philip Gemmell
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
| | - Vishal S Mehta
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
- Department of Cardiology, Guy's and St Thomas' NHS Foundation Trust, London, United Kingdom
| | - Baldeep S Sidhu
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
- Department of Cardiology, Guy's and St Thomas' NHS Foundation Trust, London, United Kingdom
| | - Justin Gould
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
- Department of Cardiology, Guy's and St Thomas' NHS Foundation Trust, London, United Kingdom
| | - Steven E Williams
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
| | - Mark O'Neill
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
- Department of Cardiology, Guy's and St Thomas' NHS Foundation Trust, London, United Kingdom
| | - Reza Razavi
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
| | - Steven Niederer
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
| | - Martin J Bishop
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
| | - Christopher A Rinaldi
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
- Department of Cardiology, Guy's and St Thomas' NHS Foundation Trust, London, United Kingdom
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Mendonca Costa C, Gemmell P, Elliott MK, Whitaker J, Campos FO, Strocchi M, Neic A, Gillette K, Vigmond E, Plank G, Razavi R, O'Neill M, Rinaldi CA, Bishop MJ. Determining anatomical and electrophysiological detail requirements for computational ventricular models of porcine myocardial infarction. Comput Biol Med 2022; 141:105061. [PMID: 34915331 PMCID: PMC8819160 DOI: 10.1016/j.compbiomed.2021.105061] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 11/04/2021] [Accepted: 11/20/2021] [Indexed: 12/01/2022]
Abstract
BACKGROUND Computational models of the heart built from cardiac MRI and electrophysiology (EP) data have shown promise for predicting the risk of and ablation targets for myocardial infarction (MI) related ventricular tachycardia (VT), as well as to predict paced activation sequences in heart failure patients. However, most recent studies have relied on low resolution imaging data and little or no EP personalisation, which may affect the accuracy of model-based predictions. OBJECTIVE To investigate the impact of model anatomy, MI scar morphology, and EP personalisation strategies on paced activation sequences and VT inducibility to determine the level of detail required to make accurate model-based predictions. METHODS Imaging and EP data were acquired from a cohort of six pigs with experimentally induced MI. Computational models of ventricular anatomy, incorporating MI scar, were constructed including bi-ventricular or left ventricular (LV) only anatomy, and MI scar morphology with varying detail. Tissue conductivities and action potential duration (APD) were fitted to 12-lead ECG data using the QRS duration and the QT interval, respectively, in addition to corresponding literature parameters. Paced activation sequences and VT induction were simulated. Simulated paced activation and VT inducibility were compared between models and against experimental data. RESULTS Simulations predict that the level of model anatomical detail has little effect on simulated paced activation, with all model predictions comparing closely with invasive EP measurements. However, detailed scar morphology from high-resolution images, bi-ventricular anatomy, and personalized tissue conductivities are required to predict experimental VT outcome. CONCLUSION This study provides clear guidance for model generation based on clinical data. While a representing high level of anatomical and scar detail will require high-resolution image acquisition, EP personalisation based on 12-lead ECG can be readily incorporated into modelling pipelines, as such data is widely available.
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Affiliation(s)
- Caroline Mendonca Costa
- Department of Biomedical Engineering, School of Biomedical Engineering & Imaging Sciences, King's College London, UK.
| | - Philip Gemmell
- Department of Biomedical Engineering, School of Biomedical Engineering & Imaging Sciences, King's College London, UK
| | - Mark K Elliott
- Department of Biomedical Engineering, School of Biomedical Engineering & Imaging Sciences, King's College London, UK
| | - John Whitaker
- Department of Biomedical Engineering, School of Biomedical Engineering & Imaging Sciences, King's College London, UK
| | - Fernando O Campos
- Department of Biomedical Engineering, School of Biomedical Engineering & Imaging Sciences, King's College London, UK
| | - Marina Strocchi
- Department of Biomedical Engineering, School of Biomedical Engineering & Imaging Sciences, King's College London, UK
| | | | - Karli Gillette
- Gottfried Schatz Research Center, Biophysics, Medical University of Graz, Austria; Medical University of Graz, Austria and BioTechMed, Graz, Austria
| | - Edward Vigmond
- Institut de Rythmologie et de modélisation cardiaque (LIRYC), University of Bordeaux, France
| | - Gernot Plank
- Medical University of Graz, Austria and BioTechMed, Graz, Austria
| | - Reza Razavi
- Department of Biomedical Engineering, School of Biomedical Engineering & Imaging Sciences, King's College London, UK
| | - Mark O'Neill
- Department of Cardiology, Guy's and St Thomas' Hospital, London, UK
| | - Christopher A Rinaldi
- Department of Biomedical Engineering, School of Biomedical Engineering & Imaging Sciences, King's College London, UK; Department of Cardiology, Guy's and St Thomas' Hospital, London, UK
| | - Martin J Bishop
- Department of Biomedical Engineering, School of Biomedical Engineering & Imaging Sciences, King's College London, UK
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Gemmell P, Passini E, Rodriguez B, Burton F, Smith G. Investigations of iPS Cell-Derived Cardiomyocyte Electrophysiology Using an Experimentally Calibrated Population of Models. J Pharmacol Toxicol Methods 2017. [DOI: 10.1016/j.vascn.2017.09.114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Gemmell P, Burrage K, Rodríguez B, Quinn TA. Rabbit-specific computational modelling of ventricular cell electrophysiology: Using populations of models to explore variability in the response to ischemia. Prog Biophys Mol Biol 2016; 121:169-84. [PMID: 27320382 PMCID: PMC5405055 DOI: 10.1016/j.pbiomolbio.2016.06.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Accepted: 06/13/2016] [Indexed: 11/04/2022]
Abstract
Computational modelling, combined with experimental investigations, is a powerful method for investigating complex cardiac electrophysiological behaviour. The use of rabbit-specific models, due to the similarities of cardiac electrophysiology in this species with human, is especially prevalent. In this paper, we first briefly review rabbit-specific computational modelling of ventricular cell electrophysiology, multi-cellular simulations including cellular heterogeneity, and acute ischemia. This mini-review is followed by an original computational investigation of variability in the electrophysiological response of two experimentally-calibrated populations of rabbit-specific ventricular myocyte action potential models to acute ischemia. We performed a systematic exploration of the response of the model populations to varying degrees of ischemia and individual ischemic parameters, to investigate their individual and combined effects on action potential duration and refractoriness. This revealed complex interactions between model population variability and ischemic factors, which combined to enhance variability during ischemia. This represents an important step towards an improved understanding of the role that physiological variability may play in electrophysiological alterations during acute ischemia.
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Affiliation(s)
- Philip Gemmell
- Department of Computer Science, University of Oxford, Oxford, UK
| | - Kevin Burrage
- Department of Computer Science, University of Oxford, Oxford, UK; School of Mathematical Sciences and ARC Centre of Excellence, ACEMS, Queensland University of Technology, Brisbane, Australia
| | - Blanca Rodríguez
- Department of Computer Science, University of Oxford, Oxford, UK
| | - T Alexander Quinn
- Department of Physiology and Biophysics, Dalhousie University, 5850 College St, Lab 3F, Halifax, NS B3H 4R2, Canada; School of Biomedical Engineering, Dalhousie University, 5850 College St, Lab 3F, Halifax, NS B3H 4R2, Canada.
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Muszkiewicz A, Britton OJ, Gemmell P, Passini E, Sánchez C, Zhou X, Carusi A, Quinn TA, Burrage K, Bueno-Orovio A, Rodriguez B. Variability in cardiac electrophysiology: Using experimentally-calibrated populations of models to move beyond the single virtual physiological human paradigm. Prog Biophys Mol Biol 2015; 120:115-27. [PMID: 26701222 PMCID: PMC4821179 DOI: 10.1016/j.pbiomolbio.2015.12.002] [Citation(s) in RCA: 104] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Revised: 11/24/2015] [Accepted: 12/02/2015] [Indexed: 01/13/2023]
Abstract
Physiological variability manifests itself via differences in physiological function between individuals of the same species, and has crucial implications in disease progression and treatment. Despite its importance, physiological variability has traditionally been ignored in experimental and computational investigations due to averaging over samples from multiple individuals. Recently, modelling frameworks have been devised for studying mechanisms underlying physiological variability in cardiac electrophysiology and pro-arrhythmic risk under a variety of conditions and for several animal species as well as human. One such methodology exploits populations of cardiac cell models constrained with experimental data, or experimentally-calibrated populations of models. In this review, we outline the considerations behind constructing an experimentally-calibrated population of models and review the studies that have employed this approach to investigate variability in cardiac electrophysiology in physiological and pathological conditions, as well as under drug action. We also describe the methodology and compare it with alternative approaches for studying variability in cardiac electrophysiology, including cell-specific modelling approaches, sensitivity-analysis based methods, and populations-of-models frameworks that do not consider the experimental calibration step. We conclude with an outlook for the future, predicting the potential of new methodologies for patient-specific modelling extending beyond the single virtual physiological human paradigm.
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Affiliation(s)
- Anna Muszkiewicz
- Department of Computer Science, University of Oxford, Parks Road, Oxford OX1 3QD, United Kingdom
| | - Oliver J Britton
- Department of Computer Science, University of Oxford, Parks Road, Oxford OX1 3QD, United Kingdom
| | - Philip Gemmell
- Clyde Biosciences Ltd, West Medical Building, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Elisa Passini
- Department of Computer Science, University of Oxford, Parks Road, Oxford OX1 3QD, United Kingdom
| | - Carlos Sánchez
- Center for Computational Medicine in Cardiology (CCMC), Institute of Computational Science, Università della Svizzera italiana, Lugano, Switzerland
| | - Xin Zhou
- Department of Computer Science, University of Oxford, Parks Road, Oxford OX1 3QD, United Kingdom
| | | | - T Alexander Quinn
- Department of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Kevin Burrage
- Department of Computer Science, University of Oxford, Parks Road, Oxford OX1 3QD, United Kingdom; Mathematical Sciences, Queensland University of Technology, Queensland 4072, Australia; ACEMS, ARC Centre of Excellence for Mathematical and Statistical Frontiers, Queensland University of Technology, Queensland 4072, Australia
| | - Alfonso Bueno-Orovio
- Department of Computer Science, University of Oxford, Parks Road, Oxford OX1 3QD, United Kingdom
| | - Blanca Rodriguez
- Department of Computer Science, University of Oxford, Parks Road, Oxford OX1 3QD, United Kingdom.
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Gemmell P, Burrage K, Rodriguez B, Quinn TA. Population of computational rabbit-specific ventricular action potential models for investigating sources of variability in cellular repolarisation. PLoS One 2014; 9:e90112. [PMID: 24587229 PMCID: PMC3938586 DOI: 10.1371/journal.pone.0090112] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [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: 08/19/2013] [Accepted: 01/29/2014] [Indexed: 11/18/2022] Open
Abstract
Variability is observed at all levels of cardiac electrophysiology. Yet, the underlying causes and importance of this variability are generally unknown, and difficult to investigate with current experimental techniques. The aim of the present study was to generate populations of computational ventricular action potential models that reproduce experimentally observed intercellular variability of repolarisation (represented by action potential duration) and to identify its potential causes. A systematic exploration of the effects of simultaneously varying the magnitude of six transmembrane current conductances (transient outward, rapid and slow delayed rectifier K+, inward rectifying K+, L-type Ca2+, and Na+/K+ pump currents) in two rabbit-specific ventricular action potential models (Shannon et al. and Mahajan et al.) at multiple cycle lengths (400, 600, 1,000 ms) was performed. This was accomplished with distributed computing software specialised for multi-dimensional parameter sweeps and grid execution. An initial population of 15,625 parameter sets was generated for both models at each cycle length. Action potential durations of these populations were compared to experimentally derived ranges for rabbit ventricular myocytes. 1,352 parameter sets for the Shannon model and 779 parameter sets for the Mahajan model yielded action potential duration within the experimental range, demonstrating that a wide array of ionic conductance values can be used to simulate a physiological rabbit ventricular action potential. Furthermore, by using clutter-based dimension reordering, a technique that allows visualisation of multi-dimensional spaces in two dimensions, the interaction of current conductances and their relative importance to the ventricular action potential at different cycle lengths were revealed. Overall, this work represents an important step towards a better understanding of the role that variability in current conductances may play in experimentally observed intercellular variability of rabbit ventricular action potential repolarisation.
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Affiliation(s)
- Philip Gemmell
- Department of Computer Science, University of Oxford, Oxford, United Kingdom
| | - Kevin Burrage
- Department of Computer Science, University of Oxford, Oxford, United Kingdom
- School of Mathematical Sciences, Queensland University of Technology, Brisbane, Australia
| | - Blanca Rodriguez
- Department of Computer Science, University of Oxford, Oxford, United Kingdom
| | - T. Alexander Quinn
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NS, Canada
- * E-mail:
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Gemmell P, Burrage K, Rodriguez B, Quinn T. Exploring the parameter space of a rabbit ventricular action potential model to investigate the effect of variation on action potential and calcium transients. Annu Int Conf IEEE Eng Med Biol Soc 2011; 2010:2662-5. [PMID: 21096193 DOI: 10.1109/iembs.2010.5626617] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Computational models for cardiomyocyte action potentials (AP) often make use of a large parameter set. This parameter set can contain some elements that are fitted to experimental data independently of any other element, some elements that are derived concurrently with other elements to match experimental data, and some elements that are derived purely from phenomenological fitting to produce the desired AP output. Furthermore, models can make use of several different data sets, not always derived for the same conditions or even the same species. It is consequently uncertain whether the parameter set for a given model is physiologically accurate. Furthermore, it is only recently that the possibility of degeneracy in parameter values in producing a given simulation output has started to be addressed. In this study, we examine the effects of varying two parameters (the L-type calcium current (I(CaL)) and the delayed rectifier potassium current (I(Ks))) in a computational model of a rabbit ventricular cardiomyocyte AP on both the membrane potential (V(m)) and calcium (Ca(2+)) transient. It will subsequently be determined if there is degeneracy in this model to these parameter values, which will have important implications on the stability of these models to cell-to-cell parameter variation, and also whether the current methodology for generating parameter values is flawed. The accuracy of AP duration (APD) as an indicator of AP shape will also be assessed.
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