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Barka ND, Smith JW, Shoyama FM, Howard BT. Intracardiac Induced Ventricular Fibrillation for the Euthanasia of Sheep. JOURNAL OF THE AMERICAN ASSOCIATION FOR LABORATORY ANIMAL SCIENCE : JAALAS 2023; 62:464-469. [PMID: 37673664 PMCID: PMC10597332 DOI: 10.30802/aalas-jaalas-23-000062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Revised: 07/27/2023] [Accepted: 07/28/2023] [Indexed: 09/08/2023]
Abstract
Euthanasia is the humane termination of an animal's life and an important consideration for scientists, veterinarians, regulators, and others contemplating investigations involving animals. Techniques for euthanasia must induce the most rapid, painless, and distress-free death possible. This study investigated the effectiveness of direct current induction of ventricular fibrillation for the euthanasia of sheep after a primary study in which artifacts or chemical contamination from injectable euthanasia agents were undesirable. Female crossbred adult sheep (Ovis aries; n = 12) under deep isoflurane general anesthesia were instrumented with electrophysiology catheters to induce ventricular fibrillation for euthanasia. Data regarding invasive arterial blood pressure, expired airway gases, limb lead electrocardiograms, and pulse oximetry were collected and assessed just prior to, immediately after, and at 5, 10, 15, and 20min after energy delivery. In all animals, a single 10-s application of 9V of direct current to the right ventricular endocardium via the electrophysiology catheter induced persistent ventricular fibrillation. Arterial blood pressure (mean ± 1 SD) immediately after fibrillation induction was 22.9±4.5mmHg, with negligible difference between systolic and diastolic pressures. The lack of differential pressure continued through the end of the monitoring period. Arterial blood pressure reached an initial nadir at 1??0.5min after fibrillation induction, peaked (40.8±11.1mmHg) due to a vasoconstrictive reflex at 3min after induction, and returned to a static uniform pressure (20.4±17.8mmHg) with mildly increased variability due to reflexive diaphragmatic contractions at 10min after induction. The use of 9V direct current for the induction of ventricular fibrillation via an electrophysiology catheter is a reliable method of euthanasia in sheep.
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O'Shea C, Holmes AP, Yu TY, Winter J, Wells SP, Correia J, Boukens BJ, De Groot JR, Chu GS, Li X, Ng GA, Kirchhof P, Fabritz L, Rajpoot K, Pavlovic D. ElectroMap: High-throughput open-source software for analysis and mapping of cardiac electrophysiology. Sci Rep 2019; 9:1389. [PMID: 30718782 PMCID: PMC6362081 DOI: 10.1038/s41598-018-38263-2] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Accepted: 12/21/2018] [Indexed: 02/04/2023] Open
Abstract
The ability to record and analyse electrical behaviour across the heart using optical and electrode mapping has revolutionised cardiac research. However, wider uptake of these technologies is constrained by the lack of multi-functional and robustly characterised analysis and mapping software. We present ElectroMap, an adaptable, high-throughput, open-source software for processing, analysis and mapping of complex electrophysiology datasets from diverse experimental models and acquisition modalities. Key innovation is development of standalone module for quantification of conduction velocity, employing multiple methodologies, currently not widely available to researchers. ElectroMap has also been designed to support multiple methodologies for accurate calculation of activation, repolarisation, arrhythmia detection, calcium handling and beat-to-beat heterogeneity. ElectroMap implements automated signal segmentation, ensemble averaging and integrates optogenetic approaches. Here we employ ElectroMap for analysis, mapping and detection of pro-arrhythmic phenomena in silico, in cellulo, animal model and in vivo patient datasets. We anticipate that ElectroMap will accelerate innovative cardiac research and enhance the uptake, application and interpretation of mapping technologies leading to novel approaches for arrhythmia prevention.
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Affiliation(s)
- Christopher O'Shea
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK
- EPSRC Centre for Doctoral Training in Physical Sciences for Health, School of Chemistry, University of Birmingham, Birmingham, UK
- School of Computer Science, University of Birmingham, Birmingham, UK
| | - Andrew P Holmes
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK
- Institute of Clinical Sciences, University of Birmingham, Birmingham, UK
| | - Ting Y Yu
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK
| | - James Winter
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK
| | - Simon P Wells
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK
- Department of Physiology, University of Melbourne, Melbourne, Australia
| | - Joao Correia
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Birmingham, UK
| | - Bastiaan J Boukens
- Amsterdam UMC, University of Amsterdam, Department of Anatomy and Physiology, Amsterdam, The Netherlands
| | - Joris R De Groot
- Amsterdam UMC, University of Amsterdam, Heart Center, Department of Cardiology, Amsterdam, The Netherlands
| | - Gavin S Chu
- Department of Cardiovascular Sciences, University of Leicester, Leicester, UK
- NIHR Leicester Biomedical Research Centre, Glenfield Hospital, Leicester, UK
| | - Xin Li
- Department of Cardiovascular Sciences, University of Leicester, Leicester, UK
| | - G Andre Ng
- Department of Cardiovascular Sciences, University of Leicester, Leicester, UK
- NIHR Leicester Biomedical Research Centre, Glenfield Hospital, Leicester, UK
| | - Paulus Kirchhof
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK
- Department of Cardiology, UHB NHS Trust, Birmingham, UK
| | - Larissa Fabritz
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK
- Department of Cardiology, UHB NHS Trust, Birmingham, UK
| | - Kashif Rajpoot
- School of Computer Science, University of Birmingham, Birmingham, UK.
| | - Davor Pavlovic
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK.
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Walton RD, Bernus O. Towards Depth-Resolved Optical Imaging of Cardiac Electrical Activity. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 859:405-23. [DOI: 10.1007/978-3-319-17641-3_16] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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Bishop MJ, Burton RAB, Kalla M, Nanthakumar K, Plank G, Bub G, Vigmond EJ. Mechanism of reentry induction by a 9-V battery in rabbit ventricles. Am J Physiol Heart Circ Physiol 2014; 306:H1041-53. [PMID: 24464758 DOI: 10.1152/ajpheart.00591.2013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Although the application of a 9-V battery to the epicardial surface is a simple method of ventricular fibrillation induction, the fundamental mechanisms underlying this process remain unstudied. We used a combined experimental and modelling approach to understand how the interaction of direct current (DC) from a battery may induce reentrant activity within rabbit ventricles and its dependence on battery application timing and duration. A rabbit ventricular computational model was used to simulate 9-V battery stimulation for different durations at varying onset times during sinus rhythm. Corresponding high-resolution optical mapping measurements were conducted on rabbit hearts with DC stimuli applied via a relay system. DC application to diastolic tissue induced anodal and cathodal make excitations in both simulations and experiments. Subsequently, similar static epicardial virtual electrode patterns were formed that interacted with sinus beats but did not induce reentry. Upon battery release during diastole, break excitations caused single ectopics, similar to application, before sinus rhythm resumed. Reentry induction was possible for short battery applications when break excitations were slowed and forced to take convoluted pathways upon interaction with refractory tissue from prior make excitations or sinus beats. Short-lived reentrant activity could be induced for battery release shortly after a sinus beat for longer battery applications. In conclusion, the application of a 9-V battery to the epicardial surface induces reentry through a complex interaction of break excitations after battery release with prior induced make excitations or sinus beats.
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Affiliation(s)
- Martin J Bishop
- Department of Biomedical Engineering, King's College London, London, United Kingdom
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Taylor TG, Venable PW, Booth A, Garg V, Shibayama J, Zaitsev AV. Does the combination of hyperkalemia and KATP activation determine excitation rate gradient and electrical failure in the globally ischemic fibrillating heart? Am J Physiol Heart Circ Physiol 2013; 305:H903-12. [PMID: 23873793 DOI: 10.1152/ajpheart.00184.2013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Ventricular fibrillation (VF) in the globally ischemic heart is characterized by a progressive electrical depression manifested as a decline in the VF excitation rate (VFR) and loss of excitability, which occur first in the subepicardium (Epi) and spread to the subendocardium (Endo). Early electrical failure is detrimental to successful defibrillation and resuscitation during cardiac arrest. Hyperkalemia and/or the activation of ATP-sensitive K(+) (KATP) channels have been implicated in electrical failure, but the role of these factors in ischemic VF is poorly understood. We determined the VFR-extracellular K(+) concentration ([K(+)]o) relationship in the Endo and Epi of the left ventricle during VF in globally ischemic hearts (Isch group) and normoxic hearts subjected to hyperkalemia (HighK group) or a combination of hyperkalemia and the KATP channel opener cromakalim (HighK-Crom group). In the Isch group, Endo and Epi values of [K(+)]o and VFR were compared in the early (0-6 min), middle (7-13 min), and late (14-20 min) phases of ischemic VF. A significant transmural gradient in VFR (Endo > Epi) was observed in all three phases, whereas a significant transmural gradient in [K(+)]o (Epi > Endo) occurred only in the late phase of ischemic VF. In the Isch group, the VFR decrease and inexcitability started to occur at much lower [K(+)]o than in the HighK group, especially in the Epi. Combining KATP activation with hyperkalemia only shifted the VFR-[K(+)]o curve upward (an effect opposite to real ischemia) without changing the [K(+)]o threshold for asystole. We conclude that hyperkalemia and/or KATP activation cannot adequately explain the heterogeneous electrical depression and electrical failure during ischemic VF.
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Affiliation(s)
- Tyson G Taylor
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah
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Swift LM, Asfour H, Posnack NG, Arutunyan A, Kay MW, Sarvazyan N. Properties of blebbistatin for cardiac optical mapping and other imaging applications. Pflugers Arch 2012; 464:503-12. [PMID: 22990759 DOI: 10.1007/s00424-012-1147-2] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Accepted: 08/20/2012] [Indexed: 11/27/2022]
Abstract
Blebbistatin is a recently discovered myosin II inhibitor. It is rapidly becoming a compound of choice to reduce motion artifacts during cardiac optical mapping, as well as to study cell motility and cell invasion. Although blebbistatin has a number of advantages over other electromechanical uncouplers, many of its properties have yet to be addressed. Here we describe several methodological issues associated with the use of blebbistatin, including its spectral properties, reversibility, and its effect on tissue metabolic state. We show that if precautions are not taken, perfusion with blebbistatin may result in blebbistatin precipitate that accumulates in the vasculature. Although such precipitate is fluorescent, it is not detectable within wavelength bands that are typically used for transmembrane voltage fluorescence imaging (i.e., emission wavelengths >600 nm). Therefore, blockage of the microcirculation by blebbistatin may cause data misinterpretation in studies that use voltage-sensitive dyes. Blebbistatin may also impact imaging of green fluorophores due to the spectral shift it causes in endogenous tissue fluorescence. 3D excitation-emission matrices of blebbistatin in precipitate form and in various solutions (DMSO, water, and 1 % aqueous albumin) revealed significant changes in the fluorescence of this molecule in different environments. Finally, we examined the reversibility of blebbistatin's uncoupling effect on cardiac contraction. Our findings provide important new information about the properties of this myosin II inhibitor, which will aid in the proper design and interpretation of studies that use this compound.
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Affiliation(s)
- Luther M Swift
- Department of Pharmacology and Physiology, The George Washington University Medical Center, 2300 Eye Street, Washington, DC 20037, USA
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Taylor TG, Venable PW, Shibayama J, Warren M, Zaitsev AV. Role of KATP channel in electrical depression and asystole during long-duration ventricular fibrillation in ex vivo canine heart. Am J Physiol Heart Circ Physiol 2012; 302:H2396-409. [PMID: 22467302 PMCID: PMC3378304 DOI: 10.1152/ajpheart.00752.2011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Accepted: 03/22/2012] [Indexed: 11/22/2022]
Abstract
Long-duration ventricular fibrillation (LDVF) in the globally ischemic heart is characterized by transmurally heterogeneous decline in ventricular fibrillation rate (VFR), emergence of inexcitable regions, and eventual global asystole. Rapid loss of both local and global excitability is detrimental to successful defibrillation and resuscitation during cardiac arrest. We sought to assess the role of the ATP-sensitive potassium current (I(KATP)) in the timing and spatial pattern of electrical depression during LDVF in a structurally normal canine heart. We analyzed endo-, mid-, and epicardial unipolar electrograms and epicardial optical recordings in the left ventricle of isolated canine hearts during 10 min of LDVF in the absence (control) and presence of an I(KATP) blocker glybenclamide (60 μM). In all myocardial layers, average VFR was the same or higher in glybenclamide-treated than in control hearts. The difference increased with time of LDVF and was overall significant in all layers (P < 0.05). However, glybenclamide did not significantly affect the transmural VFR gradient. In epicardial optical recordings, glybenclamide shortened diastolic intervals, prolonged action potential duration, and decreased the percentage of inexcitable area (all differences P < 0.001). During 10 min of LDVF, asystole occurred in 55.6% of control and none of glybenclamide-treated hearts (P < 0.05). In three hearts paced after the onset of asystole, there was no response to LV epicardial or atrial pacing. In structurally normal canine hearts, I(KATP) opening during LDVF is a major factor in the onset of local and global inexcitability, whereas it has a limited role in overall deceleration of VFR and the transmural VFR gradient.
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Affiliation(s)
- Tyson G Taylor
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, 84112-5000, USA
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Kong W, Ideker RE, Fast VG. Intramural optical mapping of V(m) and Ca(i)2+ during long-duration ventricular fibrillation in canine hearts. Am J Physiol Heart Circ Physiol 2012; 302:H1294-305. [PMID: 22268104 DOI: 10.1152/ajpheart.00426.2011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Intramural gradients of intracellular Ca(2+) (Ca(i)(2+)) Ca(i)(2+) handling, Ca(i)(2+) oscillations, and Ca(i)(2+) transient (CaT) alternans may be important in long-duration ventricular fibrillation (LDVF). However, previous studies of Ca(i)(2+) handling have been limited to recordings from the heart surface during short-duration ventricular fibrillation. To examine whether abnormalities of intramural Ca(i)(2+) handling contribute to LDVF, we measured membrane voltage (V(m)) and Ca(i)(2+) during pacing and LDVF in six perfused canine hearts using five eight-fiber optrodes. Measurements were grouped into epicardial, midwall, and endocardial layers. We found that during pacing at 350-ms cycle length, CaT duration was slightly longer (by ≃10%) in endocardial layers than in epicardial layers, whereas action potential duration (APD) exhibited no difference. Rapid pacing at 150-ms cycle length caused alternans in both APD (APD-ALT) and CaT amplitude (CaA-ALT) without significant transmural differences. For 93% of optrode recordings, CaA-ALT was transmurally concordant, whereas APD-ALT was either concordant (36%) or discordant (54%), suggesting that APD-ALT was not caused by CaA-ALT. During LDVF, V(m) and Ca(i)(2+) progressively desynchronized when not every action potential was followed by a CaT. Such desynchronization developed faster in the epicardium than in the other layers. In addition, CaT duration strongly increased (by ∼240% at 5 min of LDVF), whereas APD shortened (by ∼17%). CaT rises always followed V(m) upstrokes during pacing and LDVF. In conclusion, the fact that V(m) upstrokes always preceded CaTs indicates that spontaneous Ca(i)(2+) oscillations in the working myocardium were not likely the reason for LDVF maintenance. Strong V(m)-Ca(i)(2+) desynchronization and the occurrence of long CaTs during LDVF indicate severely impaired Ca(i)(2+) handling and may potentially contribute to LDVF maintenance.
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Affiliation(s)
- Wei Kong
- Department of Biomedical Engineering, University of Alabama, Birmingham, 35294, USA
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Lou Q, Li W, Efimov IR. The role of dynamic instability and wavelength in arrhythmia maintenance as revealed by panoramic imaging with blebbistatin vs. 2,3-butanedione monoxime. Am J Physiol Heart Circ Physiol 2011; 302:H262-9. [PMID: 22037192 DOI: 10.1152/ajpheart.00711.2011] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Unlike other excitation-contraction uncouplers, blebbistatin has few electrophysiological side effects and has gained increasing acceptance as an excitation-contraction uncoupler in optical mapping experiments. However, the possible role of blebbistatin in ventricular arrhythmia has hitherto been unknown. Furthermore, experiments with blebbistatin and 2,3-butanedione monoxime (BDM) offer an opportunity to assess the contribution of dynamic instability and wavelength of impulse propagation to the induction and maintenance of ventricular arrhythmia. Recordings of monophasic action potentials were used to assess effects of blebbistatin in Langendorff-perfused rabbit hearts (n = 5). Additionally, panoramic optical mapping experiments were conducted in rabbit hearts (n = 7) that were sequentially perfused with BDM, then washed out, and subsequently perfused with blebbistatin. The susceptibility to arrhythmia was investigated using a shock-on-T protocol. We found that 1) application of blebbistatin did not change action potential duration (APD) restitution; 2) in contrast to blebbistatin, BDM flattened APD restitution curve and reduced the wavelength; and 3) incidence of sustained arrhythmia was much lower under blebbistatin than under BDM (2/123 vs. 23/99). While arrhythmias under BDM were able to stabilize, the arrhythmias under blebbistatin were unstable and terminated spontaneously. In conclusion, the lower susceptibility to arrhythmia under blebbistatin than under BDM indicates that blebbistatin has less effects on arrhythmia dynamics. A steep restitution slope under blebbistatin is associated with higher dynamic instability, manifested by the higher incidence of not only wave breaks but also wave extinctions. This relatively high dynamic instability leads to the self-termination of arrhythmia because of the sufficiently long wavelength under blebbistatin.
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Affiliation(s)
- Qing Lou
- Department of Biomedical Engineering, Washington University, St. Louis, Missouri 63130-4899, USA
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Clayton RH, Nash MP, Bradley CP, Panfilov AV, Paterson DJ, Taggart P. Experiment-model interaction for analysis of epicardial activation during human ventricular fibrillation with global myocardial ischaemia. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2011; 107:101-11. [PMID: 21741985 DOI: 10.1016/j.pbiomolbio.2011.06.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2011] [Accepted: 06/22/2011] [Indexed: 11/25/2022]
Abstract
We describe a combined experiment-modelling framework to investigate the effects of ischaemia on the organisation of ventricular fibrillation in the human heart. In a series of experimental studies epicardial activity was recorded from 10 patients undergoing routine cardiac surgery. Ventricular fibrillation was induced by burst pacing, and recording continued during 2.5 min of global cardiac ischaemia followed by 30 s of coronary reflow. Modelling used a 2D description of human ventricular tissue. Global cardiac ischaemia was simulated by (i) decreased intracellular ATP concentration and subsequent activation of an ATP sensitive K⁺ current, (ii) elevated extracellular K⁺ concentration, and (iii) acidosis resulting in reduced magnitude of the L-type Ca²⁺ current I(Ca,L). Simulated ischaemia acted to shorten action potential duration, reduce conduction velocity, increase effective refractory period, and flatten restitution. In the model, these effects resulted in slower re-entrant activity that was qualitatively consistent with our observations in the human heart. However, the flattening of restitution also resulted in the collapse of many re-entrant waves to several stable re-entrant waves, which was different to the overall trend we observed in the experimental data. These findings highlight a potential role for other factors, such as structural or functional heterogeneity in sustaining wavebreak during human ventricular fibrillation with global myocardial ischaemia.
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Affiliation(s)
- R H Clayton
- Department of Computer Science, University of Sheffield, Regent Court, 211 Portobello S14DP, UK.
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Provost J, Gurev V, Trayanova N, Konofagou EE. Mapping of cardiac electrical activation with electromechanical wave imaging: an in silico-in vivo reciprocity study. Heart Rhythm 2011; 8:752-9. [PMID: 21185403 PMCID: PMC3100212 DOI: 10.1016/j.hrthm.2010.12.034] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2010] [Accepted: 12/19/2010] [Indexed: 10/18/2022]
Abstract
BACKGROUND Electromechanical wave imaging (EWI) is an entirely noninvasive, ultrasound-based imaging method capable of mapping the electromechanical activation sequence of the ventricles in vivo. Given the broad accessibility of ultrasound scanners in the clinic, the application of EWI could constitute a flexible surrogate for the 3-dimensional electrical activation. OBJECTIVE The purpose of this report is to reproduce the electromechanical wave (EW) using an anatomically realistic electromechanical model, and establish the capability of EWI to map the electrical activation sequence in vivo when pacing from different locations. METHODS EWI was performed in 1 canine during pacing from 3 different sites. A high-resolution dynamic model of coupled cardiac electromechanics of the canine heart was used to predict the experimentally recorded electromechanical wave. The simulated 3-dimensional electrical activation sequence was then compared with the experimental EW. RESULTS The electrical activation sequence and the EW were highly correlated for all pacing sites. The relationship between the electrical activation and the EW onset was found to be linear, with a slope of 1.01 to 1.17 for different pacing schemes and imaging angles. CONCLUSION The accurate reproduction of the EW in simulations indicates that the model framework is capable of accurately representing the cardiac electromechanics and thus testing new hypotheses. The one-to-one correspondence between the electrical activation and the EW sequences indicates that EWI could be used to map the cardiac electrical activity. This opens the door for further exploration of the technique in assisting in the early detection, diagnosis, and treatment monitoring of rhythm dysfunction.
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Affiliation(s)
- Jean Provost
- Department of Biomedical Engineering, Columbia University, New York, NY, USA
| | - Viatcheslav Gurev
- Department of Biomedical Engineering and Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD, USA
| | - Natalia Trayanova
- Department of Biomedical Engineering and Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD, USA
| | - Elisa E. Konofagou
- Department of Biomedical Engineering, Columbia University, New York, NY, USA
- Department of Radiology, Columbia University, New York, NY, USA
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Zheng Y, Wei D, Fang Z, Zhu X. Influences of sites and protocols on inducing ventricular fibrillation: A computer simulation study. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2010; 2010:2005-8. [PMID: 21097216 DOI: 10.1109/iembs.2010.5627858] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
In cardiac electrophysiological study, several electrical stimulation protocols have been employed to induce ventricular fibrillations (VF). In addition, sites of inducing may have different impacts on inducing results as well as different inducing protocols. To study whether VF inducing method is determinant of induced outcome, we simulated VFs induced with different protocols at different sites based on the Wei-Harumi whole heart model. Simulations showed that only certain combinations of pacing protocols and sites could induce sustainable VFs, which had similar frequency distributions. This result suggested that the interactions between protocols and sites determine the odds of successful inducing but once the VF was induced, the pattern was solely determined by inner cardiac properties.
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Affiliation(s)
- Yi Zheng
- Department of Electronic Engineering, Fudan University, Shanghai, China.
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Venable PW, Taylor TG, Shibayama J, Warren M, Zaitsev AV. Complex structure of electrophysiological gradients emerging during long-duration ventricular fibrillation in the canine heart. Am J Physiol Heart Circ Physiol 2010; 299:H1405-18. [PMID: 20802138 DOI: 10.1152/ajpheart.00419.2010] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Long-duration ventricular fibrillation (LDVF) in the globally ischemic heart is a common setting of cardiac arrest. Electrical heterogeneities during LDVF may affect outcomes of defibrillation and resuscitation. Previous studies in large mammalian hearts have investigated the role of Purkinje fibers and electrophysiological gradients between the endocardium (Endo) and epicardium (Epi). Much less is known about gradients between the right ventricle (RV) and left ventricle (LV) and within each chamber during LDVF. We studied the transmural distribution of the VF activation rate (VFR) in the RV and LV and at the junction of RV, LV, and septum (Sep) during LDVF using plunge needle electrodes in opened-chest dogs. We also used optical mapping to analyze the Epi distribution of VFR, action potential duration (APD), and diastolic interval (DI) during LDVF in the RV and LV of isolated hearts. Transmural VFR gradients developed in both the RV and LV, with a faster VFR in Endo. Concurrently, large VFR gradients developed in Epi, with the fastest VFR in the RV-Sep junction, intermediate in the RV, and slowest in the LV. Optical mapping revealed a progressively increasing VFR dispersion within both the LV and RV, with a mosaic presence of fully inexcitable areas after 4-8 min of LDVF. The transmural, interchamber, and intrachamber VFR heterogeneities were of similar magnitude. In both chambers, the inverse of VFR was highly correlated with DI, but not APD, at all time points of LDVF. We conclude that the complex VFR gradients during LDVF in the canine heart cannot be explained solely by the distribution of Purkinje fibers and are related to regional differences in the electrical depression secondary to LDVF.
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Affiliation(s)
- Paul W Venable
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah 84112-5000, USA
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