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Bergquist J, Rupp L, Zenger B, Brundage J, Busatto A, MacLeod RS. Body Surface Potential Mapping: Contemporary Applications and Future Perspectives. HEARTS 2021; 2:514-542. [PMID: 35665072 PMCID: PMC9164986 DOI: 10.3390/hearts2040040] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/01/2023] Open
Abstract
Body surface potential mapping (BSPM) is a noninvasive modality to assess cardiac bioelectric activity with a rich history of practical applications for both research and clinical investigation. BSPM provides comprehensive acquisition of bioelectric signals across the entire thorax, allowing for more complex and extensive analysis than the standard electrocardiogram (ECG). Despite its advantages, BSPM is not a common clinical tool. BSPM does, however, serve as a valuable research tool and as an input for other modes of analysis such as electrocardiographic imaging and, more recently, machine learning and artificial intelligence. In this report, we examine contemporary uses of BSPM, and provide an assessment of its future prospects in both clinical and research environments. We assess the state of the art of BSPM implementations and explore modern applications of advanced modeling and statistical analysis of BSPM data. We predict that BSPM will continue to be a valuable research tool, and will find clinical utility at the intersection of computational modeling approaches and artificial intelligence.
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Affiliation(s)
- Jake Bergquist
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT 84112, USA
- Scientific Computing and Imaging Institute, University of Utah, Salt Lake City, UT 84112, USA
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT 84112, USA
| | - Lindsay Rupp
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT 84112, USA
- Scientific Computing and Imaging Institute, University of Utah, Salt Lake City, UT 84112, USA
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT 84112, USA
| | - Brian Zenger
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT 84112, USA
- Scientific Computing and Imaging Institute, University of Utah, Salt Lake City, UT 84112, USA
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT 84112, USA
- School of Medicine, University of Utah, Salt Lake City, UT 84112, USA
| | - James Brundage
- School of Medicine, University of Utah, Salt Lake City, UT 84112, USA
| | - Anna Busatto
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT 84112, USA
- Scientific Computing and Imaging Institute, University of Utah, Salt Lake City, UT 84112, USA
| | - Rob S. MacLeod
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT 84112, USA
- Scientific Computing and Imaging Institute, University of Utah, Salt Lake City, UT 84112, USA
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT 84112, USA
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Meo M, Bonizzi P, Bear LR, Cluitmans M, Abell E, Haïssaguerre M, Bernus O, Dubois R. Body Surface Mapping of Ventricular Repolarization Heterogeneity: An Ex-vivo Multiparameter Study. Front Physiol 2020; 11:933. [PMID: 32903614 PMCID: PMC7438571 DOI: 10.3389/fphys.2020.00933] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Accepted: 07/10/2020] [Indexed: 12/15/2022] Open
Abstract
Background Increased heterogeneity of ventricular repolarization is associated with life-threatening arrhythmia and sudden cardiac death (SCD). T-wave analysis through body surface potential mapping (BSPM) is a promising tool for risk stratification, but the clinical effectiveness of current electrocardiographic indices is still unclear, with limited experimental validation. This study aims to investigate performance of non-invasive state-of-the-art and novel T-wave markers for repolarization dispersion in an ex vivo model. Methods Langendorff-perfused pig hearts (N = 7) were suspended in a human-shaped 256-electrode torso tank. Tank potentials were recorded during sinus rhythm before and after introducing repolarization inhomogeneities through local perfusion with dofetilide and/or pinacidil. Drug-induced repolarization gradients were investigated from BSPMs at different experiment phases. Dispersion of electrical recovery was quantified by duration parameters, i.e., the time interval between the peak and the offset of T-wave (TPEAK-TEND) and QT interval, and variability over time and electrodes was also assessed. The degree of T-wave symmetry to the peak was quantified by the ratio between the terminal and initial portions of T-wave area (Asy). Morphological variability between left and right BSPM electrodes was measured by dynamic time warping (DTW). Finally, T-wave organization was assessed by the complexity of repolarization index (CR), i.e., the amount of energy non-preserved by the dominant eigenvector computed by principal component analysis (PCA), and the error between each multilead T-wave and its 3D PCA approximation (NMSE). Body surface indices were compared with global measures of epicardial dispersion of repolarization, and with local gradients between adjacent ventricular sites. Results After drug intervention, both regional and global repolarization heterogeneity were significantly enhanced. On the body surface, TPEAK-TEND was significantly prolonged and less stable in time in all experiments, while QT interval showed higher variability across the interventions in terms of duration and spatial dispersion. The rising slope of the repolarization profile was steeper, and T-waves were more asymmetric than at baseline. Interventricular shape dissimilarity was enhanced by repolarization gradients according to DTW. Organized T-wave patterns were associated with abnormal repolarization, and they were properly described by the first principal components. Conclusion Repolarization heterogeneity significantly affects T-wave properties, and can be non-invasively captured by BSPM-based metrics.
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Affiliation(s)
- Marianna Meo
- Institute of Electrophysiology and Heart Modeling (IHU Liryc), Foundation Bordeaux University, Pessac-Bordeaux, France.,University of Bordeaux, CRCTB, Bordeaux, France.,INSERM, CRCTB, U1045, Bordeaux, France
| | - Pietro Bonizzi
- Department of Data Science and Knowledge Engineering, Maastricht University, Maastricht, Netherlands
| | - Laura R Bear
- Institute of Electrophysiology and Heart Modeling (IHU Liryc), Foundation Bordeaux University, Pessac-Bordeaux, France.,University of Bordeaux, CRCTB, Bordeaux, France.,INSERM, CRCTB, U1045, Bordeaux, France
| | - Matthijs Cluitmans
- Department of Cardiology, Cardiovascular Research Institute Maastricht, Maastricht University Medical Center, Maastricht, Netherlands
| | - Emma Abell
- Institute of Electrophysiology and Heart Modeling (IHU Liryc), Foundation Bordeaux University, Pessac-Bordeaux, France.,University of Bordeaux, CRCTB, Bordeaux, France.,INSERM, CRCTB, U1045, Bordeaux, France
| | - Michel Haïssaguerre
- Institute of Electrophysiology and Heart Modeling (IHU Liryc), Foundation Bordeaux University, Pessac-Bordeaux, France.,University of Bordeaux, CRCTB, Bordeaux, France.,INSERM, CRCTB, U1045, Bordeaux, France.,Bordeaux University Hospital (CHU), Electrophysiology and Ablation Unit, Pessac, France
| | - Olivier Bernus
- Institute of Electrophysiology and Heart Modeling (IHU Liryc), Foundation Bordeaux University, Pessac-Bordeaux, France.,University of Bordeaux, CRCTB, Bordeaux, France.,INSERM, CRCTB, U1045, Bordeaux, France
| | - Rémi Dubois
- Institute of Electrophysiology and Heart Modeling (IHU Liryc), Foundation Bordeaux University, Pessac-Bordeaux, France.,University of Bordeaux, CRCTB, Bordeaux, France.,INSERM, CRCTB, U1045, Bordeaux, France
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The Electrophysiological Substrate of Early Repolarization Syndrome: Noninvasive Mapping in Patients. JACC Clin Electrophysiol 2019; 3:894-904. [PMID: 29130071 DOI: 10.1016/j.jacep.2016.12.017] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Background The early repolarization (ER) pattern is a common ECG finding. Recent studies established a definitive clinical association between ER and fatal ventricular arrhythmias. However, the arrhythmogenic substrate of ER in the intact human heart has not been characterized. Objectives To map the epicardial electrophysiological (EP) substrate in ER syndrome patients using noninvasive Electrocardiographic Imaging (ECGI), and to characterize substrate properties that support arrhythmogenicity. Methods Twenty-nine ER syndrome patients were enrolled, 17 of which had a malignant syndrome. Characteristics of the abnormal EP substrate were analyzed using data recorded during sinus rhythm. The EP mapping data were analyzed for electrogram morphology, conduction and repolarization. Seven normal subjects provided control data. Results The abnormal EP substrate in ER syndrome patients has the following properties: (1) Abnormal epicardial electrograms characterized by presence of J-waves in localized regions; (2) Absence of conduction abnormalities, including delayed activation, conduction block, or fractionated electrograms; (3) Marked abbreviation of ventricular repolarization in areas with J-waves. The action potential duration (APD) was significantly shorter than normal (196±19 vs. 235±21 ms, p<0.05). Shortening of APD occurred heterogeneously, leading to steep repolarization gradients compared to normal control (45±17 vs.7±5 ms/cm, p<0.05). Premature ventricular contractions (PVCs) were recorded in 2 patients. The PVC sites of origin were closely related to the abnormal EP substrate with J-waves and steep repolarization gradients. Conclusions Early Repolarization is associated with steep repolarization gradients caused by localized shortening of APD. Results suggest association of PVC initiation sites with areas of repolarization abnormalities. Conduction abnormalities were not observed.
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Yang T, Yu L, Jin Q, Wu L, He B. Activation recovery interval imaging of premature ventricular contraction. PLoS One 2018; 13:e0196916. [PMID: 29906289 PMCID: PMC6003683 DOI: 10.1371/journal.pone.0196916] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2018] [Accepted: 04/23/2018] [Indexed: 01/23/2023] Open
Abstract
Dispersion of ventricular repolarization due to abnormal activation contributes to the susceptibility to cardiac arrhythmias. However, the global pattern of repolarization is difficult to assess clinically. Activation recovery interval (ARI) has been used to understand the properties of ventricular repolarization. In this study, we developed an ARI imaging technique to noninvasively reconstruct three-dimensional (3D) ARI maps in 10 premature ventricular contraction (PVC) patients and evaluated the results with the endocardial ARI maps recorded by a clinical navigation system (CARTO). From the analysis results of a total of 100 PVC beats in 10 patients, the average correlation coefficient is 0.86±0.05 and the average relative error is 0.06±0.03. The average localization error is 4.5±2.3 mm between the longest ARI sites in 3D ARI maps and those in CARTO endocardial ARI maps. The present results suggest that ARI imaging could serve as an alternative of evaluating global pattern of ventricular repolarization noninvasively and could assist in the future investigation of the relationship between global repolarization dispersion and the susceptibility to cardiac arrhythmias.
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Affiliation(s)
- Ting Yang
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN, United States of America
| | - Long Yu
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN, United States of America
| | - Qi Jin
- Department of Cardiology, Shanghai Ruijin Hospital, Shanghai, China
| | - Liqun Wu
- Department of Cardiology, Shanghai Ruijin Hospital, Shanghai, China
| | - Bin He
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN, United States of America
- Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, PA, United States of America
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Rudic B, Chaykovskaya M, Tsyganov A, Kalinin V, Tülümen E, Papavassiliu T, Dösch C, Liebe V, Kuschyk J, Röger S, El-Battrawy I, Akin I, Yakovleva M, Zaklyazminskaya E, Shestak A, Kim S, Chmelevsky M, Borggrefe M. Simultaneous Non-Invasive Epicardial and Endocardial Mapping in Patients With Brugada Syndrome: New Insights Into Arrhythmia Mechanisms. J Am Heart Assoc 2016; 5:JAHA.116.004095. [PMID: 27930354 PMCID: PMC5210320 DOI: 10.1161/jaha.116.004095] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Background The underlying mechanisms of Brugada syndrome (BrS) are not completely understood. Recent studies provided evidence that the electrophysiological substrate, leading to electrocardiogram abnormalities and/or ventricular arrhythmias, is located in the right ventricular outflow tract (RVOT). The purpose of this study was to examine abnormalities of epicardial and endocardial local unipolar electrograms by simultaneous noninvasive mapping in patients with BrS. Methods and Results Local epicardial and endocardial unipolar electrograms were analyzed using a novel noninvasive epi‐ and endocardial electrophysiology system (NEEES) in 12 patients with BrS and 6 with right bundle branch block for comparison. Fifteen normal subjects composed the control group. Observed depolarization abnormalities included fragmented electrograms in the anatomical area of RVOT endocardially and epicardially, significantly prolonged activation time in the RVOT endocardium (65±20 vs 38±13 ms in controls; P=0.008), prolongation of the activation‐recovery interval in the RVOT epicardium (281±34 vs 247±26 ms in controls; P=0.002). Repolarization abnormalities included a larger area of ST‐segment elevation >2 mV and T‐wave inversions. Negative voltage gradient (−2.5 to −6.0 mV) between epicardium and endocardium of the RVOT was observed in 8 of 12 BrS patients, not present in patients with right bundle branch block or in controls. Conclusions Abnormalities of epicardial and endocardial electrograms associated with depolarization and repolarization properties were found using NEEES exclusively in the RVOT of BrS patients. These findings support both, depolarization and repolarization abnormalities, being operative at the same time in patients with BrS.
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Affiliation(s)
- Boris Rudic
- Department of Medicine, University Medical Center Mannheim, Mannheim, Germany .,German Center for Cardiovascular Research (DZHK), Partner Site Heidelberg/Mannheim, Mannheim, Germany
| | | | - Alexey Tsyganov
- Petrovsky National Research Center of Surgery, Moscow, Russia
| | | | - Erol Tülümen
- Department of Medicine, University Medical Center Mannheim, Mannheim, Germany.,German Center for Cardiovascular Research (DZHK), Partner Site Heidelberg/Mannheim, Mannheim, Germany
| | - Theano Papavassiliu
- Department of Medicine, University Medical Center Mannheim, Mannheim, Germany.,German Center for Cardiovascular Research (DZHK), Partner Site Heidelberg/Mannheim, Mannheim, Germany
| | - Christina Dösch
- Department of Medicine, University Medical Center Mannheim, Mannheim, Germany.,German Center for Cardiovascular Research (DZHK), Partner Site Heidelberg/Mannheim, Mannheim, Germany
| | - Volker Liebe
- Department of Medicine, University Medical Center Mannheim, Mannheim, Germany.,German Center for Cardiovascular Research (DZHK), Partner Site Heidelberg/Mannheim, Mannheim, Germany
| | - Jürgen Kuschyk
- Department of Medicine, University Medical Center Mannheim, Mannheim, Germany.,German Center for Cardiovascular Research (DZHK), Partner Site Heidelberg/Mannheim, Mannheim, Germany
| | - Susanne Röger
- Department of Medicine, University Medical Center Mannheim, Mannheim, Germany.,German Center for Cardiovascular Research (DZHK), Partner Site Heidelberg/Mannheim, Mannheim, Germany
| | - Ibrahim El-Battrawy
- Department of Medicine, University Medical Center Mannheim, Mannheim, Germany.,German Center for Cardiovascular Research (DZHK), Partner Site Heidelberg/Mannheim, Mannheim, Germany
| | - Ibrahim Akin
- Department of Medicine, University Medical Center Mannheim, Mannheim, Germany.,German Center for Cardiovascular Research (DZHK), Partner Site Heidelberg/Mannheim, Mannheim, Germany
| | | | - Elena Zaklyazminskaya
- Petrovsky National Research Center of Surgery, Moscow, Russia.,Pirogov Russian National Research Medical University, Moscow, Russia
| | - Anna Shestak
- Petrovsky National Research Center of Surgery, Moscow, Russia
| | - Stanislav Kim
- Petrovsky National Research Center of Surgery, Moscow, Russia
| | | | - Martin Borggrefe
- Department of Medicine, University Medical Center Mannheim, Mannheim, Germany.,German Center for Cardiovascular Research (DZHK), Partner Site Heidelberg/Mannheim, Mannheim, Germany
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6
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Kolomeyets NL, Roshchevskaya IM. The electrical resistivity of a segment of the tail, lungs, liver, and intercostal muscles of the grass snake during in vivo cooling. Biophysics (Nagoya-shi) 2016. [DOI: 10.1134/s0006350916050110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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de Luna AB, Zareba W, Fiol M, Nikus K, Birnbaum Y, Baranowski R, Goldwasser D, Kligfield P, Piotrowicz R, Breithardt G, Wellens H. Negative T wave in ischemic heart disease: a consensus article. Ann Noninvasive Electrocardiol 2015; 19:426-41. [PMID: 25262662 DOI: 10.1111/anec.12193] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND For many years was considered that negative T wave in ischemic heart disease represents ischemia and for many authors located in subepicardial area. METHODS We performed a review based in the literature and in the experience of the authors commenting the real significance of the presence of negative T wave in patients with ischemic heart disease. RESULTS The negative T wave may be of primary or secondary type. Negative T wave observed in ischemic heart disease are of primary origin, therefore not a consequence of abnormal repolarization pattern. The negative T wave of ischemic origin presents the following characteristics: (1) are symmetrical and of variable deepness; (2) present mirror patterns; (3) starts in the second part of repolarization; and (4) may be accompanied by positive or negative U wave. The negative T wave of ischemic origin may be seen in the following clinical settings: (1) postmyocardial infarction due to a window effect of necrotic zone and (2) as a consequence of reperfusion in case of aborted MI when the artery has opened spontaneously, or after fibrinolysis, PCI, or coronary spasm. CONCLUSION Acute ongoing ischemia do not cause negative T wave. This pattern appears when the ongoing ischemia is vanishing or in the chronic phase. In all these cases the cause of negative T wave is not located in the subepicardial area. Furthermore, positive exercise testing is expressed by ST depression never by isolated negative T wave. There are many circumstances that may present negative T wave outside ischemic heart disease and that have been discussed in this paper.
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Affiliation(s)
- Antonio Bayés de Luna
- Santa Creu i Sant Pau Hospital, Cardiovascular Research Center, CSIC-ICCC, Barcelona, Spain
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8
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Computer modelling of beat-to-beat repolarization heterogeneity in human cardiac ventricles. Biomed Signal Process Control 2014. [DOI: 10.1016/j.bspc.2014.08.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Kozmann G, Tuboly G, Tarjányi Z, Szathmáry V, Švehlíková J, Tyšler M. Model interpretation of body surface potential QRST integral map variability in arrhythmia patients. Biomed Signal Process Control 2014. [DOI: 10.1016/j.bspc.2013.06.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Abstract
Late I Na is an integral part of the sodium current, which persists long after the fast-inactivating component. The magnitude of the late I Na is relatively small in all species and in all types of cardiomyocytes as compared with the amplitude of the fast sodium current, but it contributes significantly to the shape and duration of the action potential. This late component had been shown to increase in several acquired or congenital conditions, including hypoxia, oxidative stress, and heart failure, or due to mutations in SCN5A, which encodes the α-subunit of the sodium channel, as well as in channel-interacting proteins, including multiple β subunits and anchoring proteins. Patients with enhanced late I Na exhibit the type-3 long QT syndrome (LQT3) characterized by high propensity for the life-threatening ventricular arrhythmias, such as Torsade de Pointes (TdP), as well as for atrial fibrillation. There are several distinct mechanisms of arrhythmogenesis due to abnormal late I Na, including abnormal automaticity, early and delayed after depolarization-induced triggered activity, and dramatic increase of ventricular dispersion of repolarization. Many local anesthetic and antiarrhythmic agents have a higher potency to block late I Na as compared with fast I Na. Several novel compounds, including ranolazine, GS-458967, and F15845, appear to be the most selective inhibitors of cardiac late I Na reported to date. Selective inhibition of late I Na is expected to be an effective strategy for correcting these acquired and congenital channelopathies.
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Birnbaum Y, Bayés de Luna A, Fiol M, Nikus K, Macfarlane P, Gorgels A, Sionis A, Cinca J, Barrabes JA, Pahlm O, Sclarovsky S, Wellens H, Gettes L. Common pitfalls in the interpretation of electrocardiograms from patients with acute coronary syndromes with narrow QRS: a consensus report. J Electrocardiol 2012; 45:463-75. [DOI: 10.1016/j.jelectrocard.2012.06.011] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2012] [Indexed: 11/26/2022]
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12
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Fereniec M, Stix G, Kania M, Mroczka T, Janusek D, Maniewski R. Risk assessment of ventricular arrhythmia using new parameters based on high resolution body surface potential mapping. Med Sci Monit 2011; 17:MT26-33. [PMID: 21358612 PMCID: PMC3524725 DOI: 10.12659/msm.881436] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Background The effective screening of myocardial infarction (MI) patients threatened by ventricular tachycardia (VT) is an important issue in clinical practice, especially in the process of implantable cardioverter-defibrillator (ICD) therapy recommendation. This study proposes new parameters describing depolarization and repolarization inhomogeneity in high resolution body surface potential maps (HR BSPM) to identify MI patients threatened by VT. Material/Methods High resolution ECGs were recorded from 64 surface leads. Time-averaged HR BSPMs were used. Several parameters for arrhythmia risk assessment were calculated in 2 groups of MI patients: those with and without documented VT. Additionally, a control group of healthy subjects was studied. To assess the risk of VT, the following parameters were proposed: correlation coefficient between STT and QRST integral maps (STT_QRST_CORR), departure index of absolute value of STT integral map (STT_DI), and departure index of absolute value of T-wave shape index (TSI_DI). These new parameters were compared to known parameters: QRS width, QT interval, QT dispersion, Tpeak-Tend interval, total cosines between QRS complex and T wave, and non-dipolar content of QRST integral maps. Results STT_DI, TSI_DI, STT_QRST_CORR, QRS width, and QT interval parameters were statistically significant (p≤0.05) in arrhythmia risk assessment. The highest sensitivity was found for the STT_DI parameter (0.77) and the highest specificity for TSI_DI (0.79). Conclusions Arrhythmia risk is demonstrated by both abnormal spatial distribution of the repolarization phase and changed relationship between depolarization and repolarization phases, as well as their prolongation. The proposed new parameters might be applied for risk stratification of cardiac arrhythmia.
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Affiliation(s)
- Malgorzata Fereniec
- Nalecz Institute of Biocybernetics and Biomedical Engineering PAS, Warsaw, Poland
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13
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Martin CA, Zhang Y, Grace AA, Huang CLH. In vivo studies of Scn5a+/- mice modeling Brugada syndrome demonstrate both conduction and repolarization abnormalities. J Electrocardiol 2010; 43:433-9. [PMID: 20638671 PMCID: PMC3712183 DOI: 10.1016/j.jelectrocard.2010.05.015] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2010] [Indexed: 12/02/2022]
Abstract
Objectives We investigate the extent to which the electrocardiographic (ECG) properties of intact Scn5a+/− mice reproduce the corresponding clinical Brugada syndrome phenotype and use this model to investigate the role of conduction and repolarization abnormalities in the arrhythmogenic mechanism. Methods and Results The ECGs were obtained from anesthetized wild-type and Scn5a+/− mice, before and after administration of the known pro- and antiarrhythmic agents flecainide and quinidine. The ECG intervals were measured and their dispersions calculated. Scn5a+/− hearts showed ventricular arrhythmias, ST elevation, and conduction disorders including increased QT dispersion, accentuated by flecainide. Quinidine did not cause ventricular arrhythmias but exerted variable effects on ST segments and worsened conduction abnormalities. Conclusions The ECG features in an Scn5a+/− mouse establish it as a suitable model for Brugada syndrome and demonstrate abnormal conduction and repolarization phenomena. Altered QT dispersion, taken to indicate increased transmural repolarization gradients, may be useful in clinical risk stratification.
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Affiliation(s)
- Claire A Martin
- Physiological Laboratory, University of Cambridge, Cambridge, United Kingdom.
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14
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Ghosh S, Avari JN, Rhee EK, Woodard PK, Rudy Y. Noninvasive electrocardiographic imaging (ECGI) of a univentricular heart with Wolff-Parkinson-White syndrome. Heart Rhythm 2008; 5:605-8. [PMID: 18325851 DOI: 10.1016/j.hrthm.2007.12.018] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2007] [Accepted: 12/14/2007] [Indexed: 11/17/2022]
Affiliation(s)
- Subham Ghosh
- Cardiac Bioelectricity and Arrhythmia Center, Washington University, St Louis, MO 63130-4899, USA
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15
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Ghanem RN. Noninvasive electrocardiographic imaging of arrhythmogenesis: insights from modeling and human studies. J Electrocardiol 2007; 40:S169-73. [PMID: 17993317 DOI: 10.1016/j.jelectrocard.2007.06.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2007] [Accepted: 06/07/2007] [Indexed: 10/22/2022]
Abstract
BACKGROUND Sudden cardiac death remains the leading cause of death, claiming more than 1000 lives per day in the United States alone. Noninvasive means to diagnose rhythm disorders of the heart have relied heavily on the 12-lead electrocardiogram and, to a lesser extent, on higher-resolution body-surface mapping. These lack sensitivity and specificity due to the smoothing effect of the torso volume conductor. In contrast, noninvasive electrocardiographic imaging (ECGI) reconstructs potentials, electrograms, and activation sequences directly on the heart surface from body-surface electrocardiograms and has been applied in animal as well as clinical studies. This presentation summarizes the application of ECGI for imaging epicardial arrhythmogenic substrates and associated properties, in particular, dispersion of myocardial repolarization, fractionated electrograms, and heterogeneous multipolar potential distributions. METHODS Electrocardiographic imaging was evaluated in a canine model of temperature-induced dispersion of myocardial repolarization through localized warming and cooling and in 3 patients with preserved left ventricular ejection fraction (>or=50%) undergoing open heart surgery. Noninvasively reconstructed epicardial potentials, electrograms (and derived measures), as well as activation sequences were compared with their measured counterparts. RESULTS Epicardial measures of dispersion of repolarization (activation recovery intervals [ARIs] and QRST integrals) accurately reflected the underlying repolarization properties: prolonged ARIs and increased QRST (warming), shortened ARIs and decreased QRST (cooling), and gradients of adjacent prolonged and shortened ARIs (increased and decreased QRST) during simultaneous warming and cooling. In open-heart surgery patients, ECGI reflected the underlying arrhythmogenic substrate by noninvasively reconstructing fractionated electrograms (cross-correlation with measured electrograms = 0.72 +/- 0.25), regions of heterogeneous multipolar potential distributions, and areas of slow conduction. CONCLUSION These studies demonstrate that ECGI can capture and localize noninvasively important electrophysiologic properties of the heart. Its clinical significance lies in mapping arrhythmogenic substrates, evaluation and guidance of therapy, and risk stratification.
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Affiliation(s)
- Raja N Ghanem
- Medtronic Cardiac Rhythm Disease Management, Minneapolis, MN, USA.
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16
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Wang Y, Schuessler RB, Damiano RJ, Woodard PK, Rudy Y. Noninvasive electrocardiographic imaging (ECGI) of scar-related atypical atrial flutter. Heart Rhythm 2007; 4:1565-7. [PMID: 17996498 DOI: 10.1016/j.hrthm.2007.08.019] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2007] [Accepted: 08/15/2007] [Indexed: 10/22/2022]
Affiliation(s)
- Yong Wang
- Cardiac Bioelectricity and Arrhythmia Center, Washington University in St. Louis, St. Louis, Missouri 63130-4899, USA
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Wang Y, Cuculich PS, Woodard PK, Lindsay BD, Rudy Y. Focal atrial tachycardia after pulmonary vein isolation: noninvasive mapping with electrocardiographic imaging (ECGI). Heart Rhythm 2007; 4:1081-4. [PMID: 17675084 PMCID: PMC2078529 DOI: 10.1016/j.hrthm.2007.04.014] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2007] [Accepted: 04/13/2007] [Indexed: 11/15/2022]
Affiliation(s)
- Yong Wang
- Cardiac Bioelectricity and Arrhythmia Center (CBAC), Washington University in St Louis, St Louis, Missouri
| | - Phillip S. Cuculich
- Cardiovascular Division, Washington University School of Medicine, St. Louis, Missouri
| | - Pamela K. Woodard
- Cardiac Bioelectricity and Arrhythmia Center (CBAC), Washington University in St Louis, St Louis, Missouri
- Malinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri
| | - Bruce D. Lindsay
- Cardiac Bioelectricity and Arrhythmia Center (CBAC), Washington University in St Louis, St Louis, Missouri
- Cardiovascular Division, Washington University School of Medicine, St. Louis, Missouri
| | - Yoram Rudy
- Cardiac Bioelectricity and Arrhythmia Center (CBAC), Washington University in St Louis, St Louis, Missouri
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Shimizu W. Effects of sympathetic stimulation on various repolarization indices in the congenital long QT syndrome. Ann Noninvasive Electrocardiol 2006; 7:332-42. [PMID: 12431311 PMCID: PMC7027645 DOI: 10.1111/j.1542-474x.2002.tb00182.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Sympathetic stimulation or catecholamines modulate ventricular repolarization and provoke ventricular tachyarrhythmias in a variety of heart diseases and conditions. Among those, the congenital form of long QT syndrome (LQTS) has long been known to be a Rosetta stone for sympathetic-related ventricular tachyarrhythmias. Recent experimental studies employing arterially-perfused ventricular wedge preparations as well as some clinical studies have greatly advanced our knowledge of the cellular mechanism of the T wave and the various repolarization indices in the ECG, as well as the effect of sympathetic stimulation on these repolarization indices under normal and long QT conditions. Differences in the time course of repolarization of the three predominant cell types, the epicardial, midmyocardial (M), and endocardial cells, across the ventricular wall give rise to voltage gradients responsible for the inscription of normal T waves as well as the manifestation of abnormal T waves in the congenital LQTS. The data from the wedge experiments suggest that the repolarization time of the longest M cell action potential determines the Q-Tend interval, while that of the epicardial action potential determines the Q-Tpeak interval. Therefore, Tpeak-end interval in the ECG may provide an index of transmural dispersion of repolarization (TDR). In this review article, sympathetic stimulation with isoproterenol or epinephrine infusion is demonstrated to modulate differentially these repolarization indices in the ECG as well as the action potentials of the three cells between the LQT1, LQT2, and LQT3 syndromes both experimentally and clinically, explaining the differences in the sensitivity of genotypes of congenital LQTS to sympathetic stimulation.
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Affiliation(s)
- Wataru Shimizu
- Division of Cardiology, Department of Internal Medicine, National Cardiovascular Center, 5-7-1 Fujishiro-dai, Suita, Osaka, 565-8565 Japan.
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Jia P, Ramanathan C, Ghanem RN, Ryu K, Varma N, Rudy Y. Electrocardiographic imaging of cardiac resynchronization therapy in heart failure: observation of variable electrophysiologic responses. Heart Rhythm 2006; 3:296-310. [PMID: 16500302 PMCID: PMC2030622 DOI: 10.1016/j.hrthm.2005.11.025] [Citation(s) in RCA: 126] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2005] [Accepted: 11/22/2005] [Indexed: 11/30/2022]
Abstract
BACKGROUND Cardiac resynchronization therapy (CRT) for congestive heart failure patients with delayed left ventricular (LV) conduction is clinically beneficial in approximately 70% of patients. Unresolved issues include patient selection, lead placement, and efficacy of LV pacing alone. Being an electrical approach, detailed electrical information during CRT is critical to resolving these issues. However, electrical data from patients have been limited because of the requirement for invasive mapping. OBJECTIVES The purpose of this study was to provide observations and insights on the variable electrophysiologic responses of the heart to CRT using electrocardiographic imaging (ECGI). METHODS ECGI is a novel modality for noninvasive epicardial mapping. ECGI was conducted in eight patients undergoing CRT during native rhythm and various pacing modes. RESULTS In native rhythm (six patients), ventricular activation was heterogeneous, with latest activation in the lateral LV base in three patients and in the anterolateral, midlateral, or inferior LV in the remainder of patients. Anterior LV was susceptible to block and slow conduction. Right ventricular pacing improved electrical synchrony in two of six patients. LV pacing in three of four patients involved fusion with intrinsic excitation resulting in electrical resynchronization similar to biventricular pacing. Although generally electrical synchrony improved significantly with biventricular pacing, it was not always accompanied by clinical benefit. CONCLUSION Results suggest that (1) when accompanied by fusion, LV pacing alone can be as effective as biventricular pacing for electrical resynchronization; (2) right ventricular pacing is not effective for resynchronization; and (3) efficacy of CRT depends strongly on the patient-specific electrophysiologic substrate.
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Affiliation(s)
- Ping Jia
- Cardiac Bioelectricity Research and Training Center, Case Western Reserve University, Cleveland, Ohio
| | - Charulatha Ramanathan
- Cardiac Bioelectricity Research and Training Center, Case Western Reserve University, Cleveland, Ohio
| | - Raja N. Ghanem
- Cardiac Bioelectricity Research and Training Center, Case Western Reserve University, Cleveland, Ohio
| | - Kyungmoo Ryu
- Cardiac Bioelectricity Research and Training Center, Case Western Reserve University, Cleveland, Ohio
| | - Niraj Varma
- Cardiac Bioelectricity Research and Training Center, Case Western Reserve University, Cleveland, Ohio
- University Hospitals of Cleveland, Cleveland, Ohio
| | - Yoram Rudy
- Cardiac Bioelectricity and Arrhythmia Center, Washington University in St. Louis, St. Louis, Missouri
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20
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Hintermüller C, Seger M, Pfeifer B, Fischer G, Modre R, Tilg B. Sensitivity- and effort-gain analysis: multilead ECG electrode array selection for activation time imaging. IEEE Trans Biomed Eng 2006; 53:2055-66. [PMID: 17019870 DOI: 10.1109/tbme.2006.881797] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Methods for noninvasive imaging of electric function of the heart might become clinical standard procedure the next years. Thus, the overall procedure has to meet clinical requirements as an easy and fast application. In this paper, we propose a new electrode array which improves the resolution of methods for activation time imaging considering clinical constraints such as easy to apply and compatibility with routine leads. For identifying the body-surface regions where the body surface potential (BSP) is most sensitive to changes in transmembrane potential (TMP), a virtual array method was used to compute local linear dependency (LLD) maps. The virtual array method computes a measure for the LLD in every point on the body surface. The most suitable number and position of the electrodes within the sensitive body surface regions was selected by constructing effort gain (EG) plots. Such a plot depicts the relative attainable rank of the leadfield matrix in relation to the increase in number of electrodes required to build the electrode array. The attainable rank itself was computed by a detector criterion. Such a criterion estimates the maximum number of source space eigenvectors not covered by noise when being mapped to the electrode space by the leadfield matrix and recorded by a detector. From the sensitivity maps, we found that the BSP is most sensitive to changes in TMP on the upper left frontal and dorsal body surface. These sensitive regions are covered best by an electrode array consisting of two L-shaped parts of approximately 30 cm x 30 cm and approximately 20 cm x 20 cm. The EG analysis revealed that the array meeting clinical requirements best and improving the resolution of activation time imaging consists of 125 electrodes with a regular horizontal and vertical spacing of 2-3 cm.
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Affiliation(s)
- Christoph Hintermüller
- Institute of Biomedical Engineering, University of Health Sciences, Medical Informatics and Technology, Eduard Wallnöfer Zentrum I, 6060 Hall i. Tyrol, Austria.
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21
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22
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Berger T, Hanser F, Hintringer F, Poelzl G, Fischer G, Modre R, Tilg B, Pachinger O, Roithinger FX. Effects of Cardiac Resynchronization Therapy on Ventricular Repolarization in Patients with Congestive Heart Failure. J Cardiovasc Electrophysiol 2005; 16:611-7. [PMID: 15946359 DOI: 10.1046/j.1540-8167.2005.40496.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
INTRODUCTION Biventricular pacing has been shown to improve the clinical status of patients with congestive heart failure, but little is known about its influence on ventricular repolarization. The aim of our study was to evaluate the effect of biventricular pacing on ECG markers of ventricular repolarization in patients with congestive heart failure. METHODS AND RESULTS Twenty-five patients with congestive heart failure, sinus rhythm (SR), and complete LBBB (6 females; age 61 +/- 8 years; NYHA class II-III; echocardiographic ejection fraction 21 +/- 5%; QRS > or = 130 ms) underwent permanent biventricular DDDR pacemaker implantation. A high-resolution 65-lead body-surface ECG recording was performed at baseline and during right-, left-, and biventricular pacing, and the total 65-lead root mean square curve of the QRST complex and the interlead QT dispersion were assessed. The QRS duration was increased during right (RV)- and left ventricular (LV) pacing (127 +/- 26% and 117 +/- 40%; P < 0.05), as compared to SR (100%) and biventricular pacing (93 +/- 16%; ns). The QTc interval was increased during RV and LV pacing (112 +/- 12% and 114 +/- 14%; P < 0.05) as compared to SR (100%) or biventricular pacing (99 +/- 12%). There was no effect on JT interval during all pacing modes. The T(peak-end) interval was increased during right (120 +/- 34%; P < 0.01) and LV pacing (113 +/- 29%; P < 0.05) but decreased during biventricular pacing (81 +/- 19%; P < 0.01). A similar effect was found for the T(peak-end) integral and the T(peak) amplitude. QT dispersion was increased during right ventricular (129 +/- 16 ms; P < 0.05) and decreased during biventricular pacing (90 +/- 12 ms; P < 0.01), as compared to SR (114 +/- 22 ms). CONCLUSIONS Using a high-resolution surface ECG, biventricular pacing resulted in a significant reduction of ECG markers of ventricular dispersion of repolarization.
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Affiliation(s)
- Thomas Berger
- Innsbruck Medical University, Clinical Division of Cardiology, A-6020 Innsbruck, Austria
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23
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Messnarz B, Seger M, Modre R, Fischer G, Hanser F, Tilg B. A comparison of noninvasive reconstruction of epicardial versus transmembrane potentials in consideration of the null space. IEEE Trans Biomed Eng 2004; 51:1609-18. [PMID: 15376509 DOI: 10.1109/tbme.2004.828038] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We compare two source formulations for the electrocardiographic forward problem in consideration of their implications for regularizing the ill-posed inverse problem. The established epicardial potential source model is compared with a bidomain-theory-based transmembrane potential source formulation. The epicardial source approach is extended to the whole heart surface including the endocardial surfaces. We introduce the concept of the numerical null and signal space to draw attention to the problems associated with the nonuniqueness of the inverse solution and show that reconstruction of null-space components is an important issue for physiologically meaningful inverse solutions. Both formulations were tested with simulated data generated with an anisotropic heart model and with clinically measured data of two patients. A linear and a recently proposed quasi-linear inverse algorithm were applied for reconstructions of the epicardial and transmembrane potential, respectively. A direct comparison of both formulations was performed in terms of computed activation times. We found the transmembrane potential-based formulation is a more promising source formulation as stronger regularization by incorporation of biophysical a priori information is permitted.
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Affiliation(s)
- Bernd Messnarz
- University for Health Informatics and Technology, Tyrol, Innsbruck, Austria.
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24
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Narayan SM, Bhargava V. Temporal and Spatial Phase Analyses of the Electrocardiogram Stratify Intra-Atrial and Intra-Ventricular Organization. IEEE Trans Biomed Eng 2004; 51:1749-64. [PMID: 15490822 DOI: 10.1109/tbme.2004.827536] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
We hypothesized that electrocardiogram (ECG) spatial phase analysis would define a spectrum of intracardiac organization from atrial fibrillation (AF), nonisthmus-dependent and isthmus-dependent atrial flutter (AFL) to supraventricular tachycardias (SVT), and similarly for ventricular arrhythmias. We analyzed arrhythmia ECGs of 33 patients with isthmus (n = 9) and nonisthmus (n = 5) dependent AFL and SVT: atrial (n = 3), atrioventricular nodal (n = 3), and orthodromic reciprocating (n = 3) tachycardias, as well as AF (n = 5), ventricular tachycardia (monomorphic, VT-MM; n = 7), and fibrillation (VF; n = 3). ECG spatial phase was considered coherent when the correlation coefficient of an atrial (or ventricular) template to its ECG over time maintained a constant relationship in XY, XZ, and YZ planes. Regularity was quantified spectrally from ECG and correlation series. Spatial coherence occurred in 9/9 cases of isthmus--but only 1/5 of cases of nonisthmus-dependent AFL (p < 0.01; chi2). All showed one dominant spectral peak (temporal coherence). In AF, spatial phase was inconsistent in all planes and spectra were broad band. Temporal and spatial coherence occurred in other SVT. VT-MM maintained spatial phase and a single spectral peak, while VF displayed neither. Our conclusions are that temporal and spatial phase analysis from the ECG stratifies intra-atrial and intra-ventricular organization and reveals subtle variability lost on visual inspection.
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Affiliation(s)
- Sanjiv M Narayan
- Cardiology Department, Veterans' Administration Medical Center, San Diego, CA 92161, USA.
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25
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26
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Trudel MC, Dubé B, Potse M, Gulrajani RM, Leon LJ. Simulation of QRST Integral Maps With a Membrane-Based Computer Heart Model Employing Parallel Processing. IEEE Trans Biomed Eng 2004; 51:1319-29. [PMID: 15311816 DOI: 10.1109/tbme.2004.827934] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The simulation of the propagation of electrical activity in a membrane-based realistic-geometry computer model of the ventricles of the human heart, using the governing monodomain reaction-diffusion equation, is described. Each model point is represented by the phase 1 Luo-Rudy membrane model, modified to represent human action potentials. A separate longer duration action potential was used for the M cells found in the ventricular midwall. Cardiac fiber rotation across the ventricular wall was implemented via an analytic equation, resulting in a spatially varying anisotropic conductivity tensor and, consequently, anisotropic propagation. Since the model comprises approximately 12.5 million points, parallel processing on a multiprocessor computer was used to cut down on simulation time. The simulation of normal activation as well as that of ectopic beats is described. The hypothesis that in situ electrotonic coupling in the myocardium can diminish the gradients of action-potential duration across the ventricular wall was also verified in the model simulations. Finally, the sensitivity of QRST integral maps to local alterations in action-potential duration was investigated.
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Affiliation(s)
- Marie-Claude Trudel
- Institute of Biomedical Engineering, Université de Montréal, Montréal, Canada
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Smetana P, Batchvarov VN, Hnatkova K, Camm AJ, Malik M. Ventricular gradient and nondipolar repolarization components increase at higher heart rate. Am J Physiol Heart Circ Physiol 2004; 286:H131-6. [PMID: 12946934 DOI: 10.1152/ajpheart.00479.2003] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Differences in action potential duration reflect differences in ion channel properties. These properties also determine rate dependence of action potential duration, and transmural dispersion was confirmed experimentally to increase with cycle length. While several electrocardiographic indexes characterizing repolarization abnormalities have been proposed, studies of their heart rate dependence are missing. This study therefore investigated rate relationship of two repolarization descriptors, namely, the so-called total cosine of the QRS-T angle (TCRT), proposed to characterize global repolarization heterogeneity, and the so-called relative T wave residuum (TWR), linked to regional repolarization dispersion. During 24-h holter recordings in 60 healthy subjects (27 males), a 12-lead ECG was obtained every 30 s. RR intervals, QT intervals, and TCRT and TWR were calculated in each ECG and averaged over RR interval bins ranging from 550 to 1,150 ms in 10-ms steps. Women had uniformly greater TCRT and TWR values than men did over the entire range of investigated RR intervals. Whereas the TCRT in both sexes showed marked rate dependence with higher values at long RR intervals (550 vs. 1,150 ms: women, 0.46 +/- 0.31 vs. 0.76 +/- 0.18, P = 9 x 10(-7); men, 0.08 +/- 0.45 vs. 0.49 +/- 0.35, P = 9 x 10(-8)), the rate dependence of TWR was more marked in women than in men, showing higher values at shorter RR intervals (550 ms vs. 1,150 ms: women: 0.29 +/- 0.14% vs. 0.08 +/- 0.06%, P = 2 x 10(-8); men: 0.14 +/- 0.12% vs. 0.04 +/- 0.02%, P = 2 x 10(-15)). This suggests that both global and regional repolarization heterogeneity are increased at faster heart rates. Whereas in women at all heart rates the sequence of repolarization more closely replicates the sequence of depolarization, localized repolarization is more heterogeneous than in men especially at fast heart rates.
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Affiliation(s)
- Peter Smetana
- Department of Cardiological Sciences, St. George's Hospital Medical School, Cranmer Terrace, London SW17 0RE, UK
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28
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Ghanem RN, Ramanathan C, Jia P, Rudy Y. Heart-surface reconstruction and ECG electrodes localization using fluoroscopy, epipolar geometry and stereovision: application to noninvasive imaging of cardiac electrical activity. IEEE TRANSACTIONS ON MEDICAL IMAGING 2003; 22:1307-18. [PMID: 14552584 PMCID: PMC2034496 DOI: 10.1109/tmi.2003.818263] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
To date there is no imaging modality for cardiac arrhythmias which remain the leading cause of sudden death in the United States (> 300000/yr.). Electrocardiographic imaging (ECGI), a noninvasive modality that images cardiac arrhythmias from body surface potentials, requires the geometrical relationship between the heart surface and the positions of body surface ECG electrodes. A photographic method was validated in a mannequin and used to determine the three-dimensional coordinates of body surface ECG electrodes to within 1 mm of their actual positions. Since fluoroscopy is available in the cardiac electrophysiology (EP) laboratory where diagnosis and treatment of cardiac arrhythmias is conducted, a fluoroscopic method to determine the heart surface geometry was developed based on projective geometry, epipolar geometry, point reconstruction, b-spline interpolation and visualization. Fluoroscopy-reconstructed hearts in a phantom and a human subject were validated using high-resolution computed tomography (CT) imaging. The mean absolute distance error for the fluoroscopy-reconstructed heart relative to the CT heart was 4 mm (phantom) and 10 mm (human). In the human, ECGI images of normal cardiac electrical activity on the fluoroscopy-reconstructed heart showed close correlation with those obtained on the CT heart. Results demonstrate the feasibility of this approach for clinical noninvasive imaging of cardiac arrhythmias in the interventional EP laboratory.
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Affiliation(s)
- Raja N Ghanem
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA
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29
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Finley MR, Lillich JD, Gilmour RF, Freeman LC. Structural and functional basis for the long QT syndrome: relevance to veterinary patients. J Vet Intern Med 2003; 17:473-88. [PMID: 12892298 DOI: 10.1111/j.1939-1676.2003.tb02468.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Long QT syndrome (LQTS) is a condition characterized by prolongation of ventricular repolarization and is manifested clinically by lengthening of the QT interval on the surface ECG. Whereas inherited forms of LQTS associated with mutations in the genes that encode ion channel proteins are identified only in humans, the acquired form of LQTS occurs in humans and companion animal species. Often, acquired LQTS is associated with drug-induced block of the cardiac K+ current designated I(Kr). However, not all drugs that induce potentially fatal ventricular arrhythmias antagonize I(Kr), and not all drugs that block I(Kr), are associated with ventricular arrhythmias. In clinical practice, the extent of QT interval prolongation and risk of ventricular arrhythmia associated with antagonism of I(Kr) are modulated by pharmacokinetic and pharmacodynamic variables. Veterinarians can influence some of the potential risk factors (eg, drug dosage, route of drug administration, presence or absence of concurrent drug therapy, and patient electrolyte status) but not all (eg, patient gender/genetic background). Veterinarians need to be aware of the potential for acquired LQTS during therapy with drugs identified as blockers of HERG channels and I(Kr).
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Affiliation(s)
- Melissa R Finley
- Department of Anatomy and Physiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506-5802, USA
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30
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Swynghedauw B, Baillard C, Milliez P. The long QT interval is not only inherited but is also linked to cardiac hypertrophy. J Mol Med (Berl) 2003; 81:336-45. [PMID: 12750820 DOI: 10.1007/s00109-003-0437-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2003] [Accepted: 03/07/2003] [Indexed: 11/26/2022]
Abstract
This review focuses on the molecular determinants of the duration of the QT interval as measured on by electrocardiography in normal subjects and during cardiac hypertrophy and failure. (a) In control conditions, on a single cell, the shape and duration of the action potential is the result of a balance between different ion currents which in turn were determined by the number of functional channels. On multicellular preparations the QT duration also represents the repolarization time; nevertheless it is modified by the transmural gradients. On body-surface electrocardiography the duration of the QT interval depends also of an additional factor: the spatial three-dimensional projection of the electrical waves vectors, which makes any determination of the epicardial dispersion by measuring QT interval dispersion questionable. (b) The enhanced action potential duration is well documented in cardiac hypertrophy and heart failure and is usually caused by a reduction in outward current densities in most of the species except mice. Among these currents I(tO) is the most frequently altered, especially in humans. Such an altered current density is caused by a diminished expression of the genes encoding either the ion channel subunits or regulatory proteins, such as KChIP2. In addition, hypertrophy modifies or even reverses the transmural gradient. In human and rats hypertensive cardiopathy is associated with a prolongation of the QT interval duration. The reduction in I(tO) is likely to be adaptive; it participates in the slowing of the cardiac cycle and reflects the fetal genetic reprogramming. Recent data also suggest that a reduction in the transient outward K(+) current density triggers protein synthesis through an activation of the calcineurin pathways. Thus a prolongation of the QT interval is not only inherited or drug-induced; it is also an essential component of the adaptive process in chronic mechanical overload. It is fundamentally incorrect to measure QT dispersion on a surface electrocardiography, but the mean QT interval may provide information concerning the progression of the disease, just as, and with the same restrictions, in the case of the quantification of V(max).
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Affiliation(s)
- Bernard Swynghedauw
- U572-INSERM, Lariboisière Hospital, 41 Bd de la Chapelle, 75475 Paris Cedex 10, France.
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Shimizu W, Noda T, Takaki H, Kurita T, Nagaya N, Satomi K, Suyama K, Aihara N, Kamakura S, Sunagawa K, Echigo S, Nakamura K, Ohe T, Towbin JA, Napolitano C, Priori SG. Epinephrine unmasks latent mutation carriers with LQT1 form of congenital long-QT syndrome. J Am Coll Cardiol 2003; 41:633-42. [PMID: 12598076 DOI: 10.1016/s0735-1097(02)02850-4] [Citation(s) in RCA: 142] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
OBJECTIVES This study was designed to test the hypothesis that epinephrine infusion may be a provocative test able to unmask nonpenetrant KCNQ1 mutation carriers. BACKGROUND The LQT1 form of congenital long QT syndrome is associated with high vulnerability to sympathetic stimulation and appears with incomplete penetrance. METHODS The 12-lead electrocardiographic parameters before and after epinephrine infusion were compared among 19 mutation carriers with a baseline corrected QT interval (QTc) of > or =460 ms (Group I), 15 mutation carriers with a QTc of <460 ms (Group II), 12 nonmutation carriers (Group III), and 15 controls (Group IV). RESULTS The mean corrected Q-Tend (QTce), Q-Tpeak (QTcp), and Tpeak-end (Tcp-e) intervals among 12-leads before epinephrine were significantly larger in Group I than in the other three groups. Epinephrine (0.1 microg/kg/min) increased significantly the mean QTce, QTcp, Tcp-e, and the dispersion of QTcp in Groups I and II, but not in Groups III and IV. The sensitivity and specificity of QTce measurements to identify mutation carriers were 59% (20/34) and 100% (27/27), respectively, before epinephrine, and the sensitivity was substantially improved to 91% (31/34) without the expense of specificity (100%, 27/27) after epinephrine. The mean QTce, QTcp, and Tcp-e before and after epinephrine were significantly larger in 15 symptomatic than in 19 asymptomatic mutation carriers in Groups I and II, and the prolongation of the mean QTce with epinephrine was significantly larger in symptomatic patients. CONCLUSIONS Epinephrine challenge is a powerful test to establish electrocardiographic diagnosis in silent LQT1 mutation carriers, thus allowing implementation of prophylactic measures aimed at reducing sudden cardiac death.
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Affiliation(s)
- Wataru Shimizu
- Division of Cardiology, Department of Internal Medicine, National Cardiovascular Center, 5-7-1 Fujishiro-dai, Suita, Osaka 565-8565, Japan.
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Rana BS, Band MM, Ogston S, Morris AD, Pringle SD, Struthers AD. Relation of QT interval dispersion to the number of different cardiac abnormalities in diabetes mellitus. Am J Cardiol 2002; 90:483-7. [PMID: 12208406 DOI: 10.1016/s0002-9149(02)02518-3] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Three studies have clearly shown that a prolonged QT dispersion (QTD) is the best predictor of cardiac death in patients with type 2 diabetes mellitus (DM). This was originally believed to be because QTD identified electrical inhomogeneity, but recent data suggests that this is unlikely. The alternative possibility is that QTD is a convenient identifier of hidden but lethal cardiac abnormalities. We explored whether the latter possibility is true by examining exactly what spectrum of cardiac abnormalities, if any, are over-represented in diabetics with a prolonged QTD. Two hundred nineteen patients with type 2 DM who had been first diagnosed with DM 3 to 6 years previously underwent intensive cardiac examinations. Patients with prolonged QTD had a significantly increased incidence of myocardial ischemia and left ventricular (LV) hypertrophy, and to a lesser extent, autonomic dysfunction. The main independent determinant of a prolonged QTD was ischemia, as seen on both ambulatory ST-segment monitoring (p <0.001) and Duke score on treadmill testing (p <0.001). It was also observed that QTD increased progressively as the number of different cardiac abnormalities increased (p <0.001). These studies suggest that QTD is a useful, general prescreening test to select diabetics for more detailed cardiac examinations (especially for ischemia and LV hypertrophy), and that if cardiac examinations were targeted by way of QTD screening, then a high incidence of hidden but treatable cardiac abnormalities could be found.
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Affiliation(s)
- Bushra S Rana
- Department of Clinical Pharmacology and Therapeutics, Ninewells Hospital, Dundee, United Kingdom
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Shimizu W, Tanabe Y, Aiba T, Inagaki M, Kurita T, Suyama K, Nagaya N, Taguchi A, Aihara N, Sunagawa K, Nakamura K, Ohe T, Towbin JA, Priori SG, Kamakura S. Differential effects of beta-blockade on dispersion of repolarization in the absence and presence of sympathetic stimulation between the LQT1 and LQT2 forms of congenital long QT syndrome. J Am Coll Cardiol 2002; 39:1984-91. [PMID: 12084597 DOI: 10.1016/s0735-1097(02)01894-6] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVES This study compared the effects of beta-blockade on transmural and spatial dispersion of repolarization (TDR and SDR, respectively) between the LQT1 and LQT2 forms of congenital long QT syndrome (LQTS). BACKGROUND The LQT1 form is more sensitive to sympathetic stimulation and more responsive to beta-blockers than either the LQT2 or LQT3 forms. METHODS Eighty-seven-lead, body-surface electrocardiograms (ECGs) were recorded before and after epinephrine infusion (0.1 microg/kg body weight per min) in the absence and presence of oral propranolol (0.5-2.0 mg/kg per day) in 11 LQT1 patients and 11 LQT2 patients. The Q-T(end) interval, the Q-T(peak) interval and the interval between T(peak) and T(end) (T(p-e)), representing TDR, were measured and averaged from 87-lead ECGs and corrected by Bazett's method (corrected Q-T(end) interval [cQT(e)], corrected Q-T(peak) interval [cQT(p)] and corrected interval between T(peak) and T(end) [cT(p-e)]). The dispersion of cQT(e) (cQT(e)-D) was obtained among 87 leads and was defined as the interval between the maximum and minimum values of cQT(e). RESULTS Propranolol in the absence of epinephrine significantly prolonged the mean cQT(p) value but not the mean cQT(e) value, thus decreasing the mean cT(p-e) value in both LQT1 and LQT2 patients; the differences with propranolol were significantly larger in LQT1 than in LQT2 (p < 0.05). The maximum cQT(e), minimum cQT(e) and cQT(e)-D were not changed with propranolol. Propranolol completely suppressed the influence of epinephrine in prolonging the mean cQT(e), maximum cQT(e) and minimum cQT(e) values, as well as increasing the mean cT(p-e) and cQT(e)-D values in both groups. CONCLUSIONS Beta-blockade under normal sympathetic tone produces a greater decrease in TDR in the LQT1 form than in the LQT2 form, explaining the superior effectiveness of beta-blockers in LQT1 versus LQT2. Beta-blockers also suppress the influence of sympathetic stimulation in increasing TDR and SDR equally in LQT1 and LQT2 syndrome.
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Affiliation(s)
- Wataru Shimizu
- Division of Cardiology, Department of Internal Medicine, National Cardiovascular Center, Suita, Osaka, Japan.
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Ashikaga T, Nishizaki M, Arita M, Yamawake N, Fujii H, Kishi Y, Isobe M, Hiraoka M. Opening of K(ATP) channel attenuates the increase in QT dispersion produced by the first balloon inflation during coronary angioplasty. Circ J 2002; 66:469-72. [PMID: 12030342 DOI: 10.1253/circj.66.469] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Increased QT dispersion predicts the occurrence of lethal ventricular arrhythmias complicating percutaneous transluminal coronary angioplasty (PTCA). Moreover, these arrhythmias occur more frequently at the first balloon inflation. Activation of the K(ATP) channel may influence QT dispersion and ventricular arrhythmias during coronary angioplasty, so 40 consecutive patients with stable angina were randomized to receive 3 mg/h of nicorandil infusion or placebo and QT dispersion and the incidence of ventricular ectopy were investigated before and throughout PTCA. There were no significant differences in QT dispersion at baseline between the nicorandil group (42+/-8 ms) and placebo (42+/-12ms). At the first balloon inflation, the QT dispersion in the nicorandil group (51+/-13 ms) was significantly less than that observed with placebo (76+/-16ms, p<0.001). However, the QT dispersion at the second inflation was similar in both groups (nicorandil: 45+/-12ms; placebo: 52+/-14ms). Ventricular ectopy was observed in 1 patient receiving nicorandil and 5 patients in the placebo group during the first inflation, and none in the nicorandil and 1 patient in the placebo group during the second balloon inflation. Activation of the K(ATP) channel may inhibit the development of ventricular arrhythmias during PTCA, particularly at the first balloon inflation.
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Affiliation(s)
- Takashi Ashikaga
- Department of Cardiology, Yokohama Minami Kyosai Hospital, Kanagawa, Japan.
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