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Takasugi N, Endo S, Takasugi M, Tochibora R, Yoshida A, Watanabe T, Kawaguchi T, Yamada Y, Kanamori H, Ushikoshi H, Okura H. Roles of Atrial Arrhythmias in Triggering Torsade de Pointes in Patients With Acquired Long QT Syndrome. Circ Arrhythm Electrophysiol 2024; 17:e012675. [PMID: 39234741 DOI: 10.1161/circep.123.012675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Accepted: 08/13/2024] [Indexed: 09/06/2024]
Abstract
BACKGROUND Little is known about the role of atrial arrhythmias (AAs) in triggering Torsade de Pointes (TdP) in patients with long QT syndrome (LQTS). The aim of this study was to examine the contribution of AAs to the development of TdP in acquired LQTS patients. METHODS The initiation patterns of 81 episodes of TdP obtained from 34 consecutive acute acquired LQTS patients (14 men, median age, 69 years; median QTc, 645.5 ms) with documented TdP were analyzed. The initiation mode of TdP was divided into 3 categories: (1) preceding short-long sequence (SLS); (2) sudden R-on-T phenomenon without preceding SLS; and (3) increased atrial rate. The patients were divided into 2 groups based on the presence or absence of AAs-induced TdP; AAs-induced (n=18) and non-AAs-induced (n=16) groups. The association of clinical/ECG characteristics and TdP frequency after initiating conventional therapy with AAs-induced TdP was evaluated. The groups were compared using the Mann-Whitney U test or Fisher exact test. RESULTS AAs-induced group comprised 52.9% (18/34) of the patients studied. TdP was preceded by AAs-initiated SLSs in 41.2% (14/34) of the patients and was directly induced by R-on-T AAs (AAs coincidentally encountered a vulnerable repolarizing region during the T wave) in 23.5% (8/34). AAs triggered 48 (59.3%) of the 81 TdP episodes. AAs initiated SLSs in 67.8% (40/59) of the SLS-induced TdP episodes. R-on-T AAs accounted for 23.5% (19/81) of the TdP episodes. AAs-induced group experienced TdP after initiating therapy more frequently than non-AAs-induced group (2.5 versus 1 event, P=0.008). AAs-induced group exhibited macroscopic T-wave alternans more frequently than non-AAs-induced group (6 versus 0 event, P=0.02). CONCLUSIONS AAs play a key role in triggering TdP in more than half of patients with acute acquired LQTS and can increase TdP frequency after initiating therapy. Thus, AAs are not benign but rather can be life-threatening in patients with acute acquired LQTS.
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Affiliation(s)
- Nobuhiro Takasugi
- Gifu University Hospital (N.T., S.E., R.T., A.Y., T.W., T.K., Y.Y., H.K., H.U., H.O.)
| | - Susumu Endo
- Gifu University Hospital (N.T., S.E., R.T., A.Y., T.W., T.K., Y.Y., H.K., H.U., H.O.)
| | | | - Ryota Tochibora
- Gifu University Hospital (N.T., S.E., R.T., A.Y., T.W., T.K., Y.Y., H.K., H.U., H.O.)
| | - Akihiro Yoshida
- Gifu University Hospital (N.T., S.E., R.T., A.Y., T.W., T.K., Y.Y., H.K., H.U., H.O.)
| | - Takatomo Watanabe
- Gifu University Hospital (N.T., S.E., R.T., A.Y., T.W., T.K., Y.Y., H.K., H.U., H.O.)
| | - Tomonori Kawaguchi
- Gifu University Hospital (N.T., S.E., R.T., A.Y., T.W., T.K., Y.Y., H.K., H.U., H.O.)
| | - Yoshihisa Yamada
- Gifu University Hospital (N.T., S.E., R.T., A.Y., T.W., T.K., Y.Y., H.K., H.U., H.O.)
| | - Hiromitsu Kanamori
- Gifu University Hospital (N.T., S.E., R.T., A.Y., T.W., T.K., Y.Y., H.K., H.U., H.O.)
| | - Hiroaki Ushikoshi
- Gifu University Hospital (N.T., S.E., R.T., A.Y., T.W., T.K., Y.Y., H.K., H.U., H.O.)
| | - Hiroyuki Okura
- Gifu University Hospital (N.T., S.E., R.T., A.Y., T.W., T.K., Y.Y., H.K., H.U., H.O.)
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Badura K, Buławska D, Dąbek B, Witkowska A, Lisińska W, Radzioch E, Skwira S, Młynarska E, Rysz J, Franczyk B. Primary Electrical Heart Disease-Principles of Pathophysiology and Genetics. Int J Mol Sci 2024; 25:1826. [PMID: 38339103 PMCID: PMC10855675 DOI: 10.3390/ijms25031826] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Revised: 01/27/2024] [Accepted: 01/28/2024] [Indexed: 02/12/2024] Open
Abstract
Primary electrical heart diseases, often considered channelopathies, are inherited genetic abnormalities of cardiomyocyte electrical behavior carrying the risk of malignant arrhythmias leading to sudden cardiac death (SCD). Approximately 54% of sudden, unexpected deaths in individuals under the age of 35 do not exhibit signs of structural heart disease during autopsy, suggesting the potential significance of channelopathies in this group of age. Channelopathies constitute a highly heterogenous group comprising various diseases such as long QT syndrome (LQTS), short QT syndrome (SQTS), idiopathic ventricular fibrillation (IVF), Brugada syndrome (BrS), catecholaminergic polymorphic ventricular tachycardia (CPVT), and early repolarization syndromes (ERS). Although new advances in the diagnostic process of channelopathies have been made, the link between a disease and sudden cardiac death remains not fully explained. Evolving data in electrophysiology and genetic testing suggest previously described diseases as complex with multiple underlying genes and a high variety of factors associated with SCD in channelopathies. This review summarizes available, well-established information about channelopathy pathogenesis, genetic basics, and molecular aspects relative to principles of the pathophysiology of arrhythmia. In addition, general information about diagnostic approaches and management is presented. Analyzing principles of channelopathies and their underlying causes improves the understanding of genetic and molecular basics that may assist general research and improve SCD prevention.
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Affiliation(s)
- Krzysztof Badura
- Department of Nephrocardiology, Medical University of Lodz, Ul. Zeromskiego 113, 90-549 Lodz, Poland (S.S.)
| | - Dominika Buławska
- Department of Nephrocardiology, Medical University of Lodz, Ul. Zeromskiego 113, 90-549 Lodz, Poland (S.S.)
| | - Bartłomiej Dąbek
- Department of Nephrocardiology, Medical University of Lodz, Ul. Zeromskiego 113, 90-549 Lodz, Poland (S.S.)
| | - Alicja Witkowska
- Department of Nephrocardiology, Medical University of Lodz, Ul. Zeromskiego 113, 90-549 Lodz, Poland (S.S.)
| | - Wiktoria Lisińska
- Department of Nephrocardiology, Medical University of Lodz, Ul. Zeromskiego 113, 90-549 Lodz, Poland (S.S.)
| | - Ewa Radzioch
- Department of Nephrocardiology, Medical University of Lodz, Ul. Zeromskiego 113, 90-549 Lodz, Poland (S.S.)
| | - Sylwia Skwira
- Department of Nephrocardiology, Medical University of Lodz, Ul. Zeromskiego 113, 90-549 Lodz, Poland (S.S.)
| | - Ewelina Młynarska
- Department of Nephrocardiology, Medical University of Lodz, Ul. Zeromskiego 113, 90-549 Lodz, Poland (S.S.)
| | - Jacek Rysz
- Department of Nephrology, Hypertension and Family Medicine, Medical University of Lodz, Ul. Zeromskiego 113, 90-549 Lodz, Poland
| | - Beata Franczyk
- Department of Nephrocardiology, Medical University of Lodz, Ul. Zeromskiego 113, 90-549 Lodz, Poland (S.S.)
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Porta-Sánchez A, Mazzanti A, Tarifa C, Kukavica D, Trancuccio A, Mohsin M, Zanfrini E, Perota A, Duchi R, Hernandez-Lopez K, Jáuregui-Abularach ME, Pergola V, Fernandez E, Bongianino R, Tavazzani E, Gambelli P, Memmi M, Scacchi S, Pavarino LF, Franzone PC, Lentini G, Filgueiras-Rama D, Galli C, Santiago DJ, Priori SG. Unexpected impairment of INa underpins reentrant arrhythmias in a knock-in swine model of Timothy syndrome. NATURE CARDIOVASCULAR RESEARCH 2023; 2:1291-1309. [PMID: 38665938 PMCID: PMC11041658 DOI: 10.1038/s44161-023-00393-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Accepted: 11/15/2023] [Indexed: 04/28/2024]
Abstract
Timothy syndrome 1 (TS1) is a multi-organ form of long QT syndrome associated with life-threatening cardiac arrhythmias, the organ-level dynamics of which remain unclear. In this study, we developed and characterized a novel porcine model of TS1 carrying the causative p.Gly406Arg mutation in CACNA1C, known to impair CaV1.2 channel inactivation. Our model fully recapitulated the human disease with prolonged QT interval and arrhythmic mortality. Electroanatomical mapping revealed the presence of a functional substrate vulnerable to reentry, stemming from an unforeseen constitutional slowing of cardiac activation. This signature substrate of TS1 was reliably identified using the reentry vulnerability index, which, we further demonstrate, can be used as a benchmark for assessing treatment efficacy, as shown by testing of multiple clinical and preclinical anti-arrhythmic compounds. Notably, in vitro experiments showed that TS1 cardiomyocytes display Ca2+ overload and decreased peak INa current, providing a rationale for the arrhythmogenic slowing of impulse propagation in vivo.
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Affiliation(s)
- Andreu Porta-Sánchez
- Novel Arrhythmogenic Mechanism Program, Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain
| | - Andrea Mazzanti
- Novel Arrhythmogenic Mechanism Program, Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain
- Molecular Cardiology, IRCCS Istituti Clinici Scientifici Maugeri, Pavia, Italy
- Department of Molecular Medicine, University of Pavia, Pavia, Italy
| | - Carmen Tarifa
- Novel Arrhythmogenic Mechanism Program, Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain
| | - Deni Kukavica
- Novel Arrhythmogenic Mechanism Program, Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain
- Molecular Cardiology, IRCCS Istituti Clinici Scientifici Maugeri, Pavia, Italy
- Department of Molecular Medicine, University of Pavia, Pavia, Italy
| | - Alessandro Trancuccio
- Novel Arrhythmogenic Mechanism Program, Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain
- Molecular Cardiology, IRCCS Istituti Clinici Scientifici Maugeri, Pavia, Italy
- Department of Molecular Medicine, University of Pavia, Pavia, Italy
| | - Muhammad Mohsin
- Molecular Cardiology, IRCCS Istituti Clinici Scientifici Maugeri, Pavia, Italy
| | | | | | | | - Kevin Hernandez-Lopez
- Novel Arrhythmogenic Mechanism Program, Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain
| | | | - Valerio Pergola
- Novel Arrhythmogenic Mechanism Program, Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain
- Department of Advanced Biomedical Sciences, University of Naples Federico II, Naples, Italy
| | - Eugenio Fernandez
- Novel Arrhythmogenic Mechanism Program, Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain
| | - Rossana Bongianino
- Novel Arrhythmogenic Mechanism Program, Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain
- Molecular Cardiology, IRCCS Istituti Clinici Scientifici Maugeri, Pavia, Italy
| | - Elisa Tavazzani
- Molecular Cardiology, IRCCS Istituti Clinici Scientifici Maugeri, Pavia, Italy
| | - Patrick Gambelli
- Molecular Cardiology, IRCCS Istituti Clinici Scientifici Maugeri, Pavia, Italy
| | - Mirella Memmi
- Molecular Cardiology, IRCCS Istituti Clinici Scientifici Maugeri, Pavia, Italy
| | - Simone Scacchi
- Department of Mathematics, University of Milan, Milano, Italy
| | | | - Piero Colli Franzone
- Novel Arrhythmogenic Mechanism Program, Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain
- Molecular Cardiology, IRCCS Istituti Clinici Scientifici Maugeri, Pavia, Italy
- Department of Molecular Medicine, University of Pavia, Pavia, Italy
- AVANTEA, Cremona, Italy
- Department of Advanced Biomedical Sciences, University of Naples Federico II, Naples, Italy
- Department of Mathematics, University of Milan, Milano, Italy
- Department of Mathematics, University of Pavia, Pavia, Italy
- Department of Pharmacology, University of Bari, Bari, Italy
- Cardiovascular Institute, Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdISSC), Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares, Madrid, Spain
| | | | - David Filgueiras-Rama
- Novel Arrhythmogenic Mechanism Program, Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain
- Cardiovascular Institute, Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdISSC), Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares, Madrid, Spain
| | | | - Demetrio Julián Santiago
- Novel Arrhythmogenic Mechanism Program, Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain
| | - Silvia G. Priori
- Novel Arrhythmogenic Mechanism Program, Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain
- Molecular Cardiology, IRCCS Istituti Clinici Scientifici Maugeri, Pavia, Italy
- Department of Molecular Medicine, University of Pavia, Pavia, Italy
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Pappone C, Ciconte G, Vicedomini G, Anastasia L, Santinelli V. Epicardial arrhythmogenic substrate in long QT syndrome. Heart Rhythm 2023; 20:1782-1784. [PMID: 38040481 DOI: 10.1016/j.hrthm.2023.07.054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 07/05/2023] [Accepted: 07/08/2023] [Indexed: 12/03/2023]
Affiliation(s)
- Carlo Pappone
- Arrhythmia and Electrophysiology Center, IRCCS Policlinico San Donato, San Donato Milanese, Milan, Italy; Vita-Salute San Raffaele University, Milan, Italy; Institute of Molecular and Translational Cardiology (IMTC), San Donato Milanese, Milan, Italy.
| | - Giuseppe Ciconte
- Arrhythmia and Electrophysiology Center, IRCCS Policlinico San Donato, San Donato Milanese, Milan, Italy; Vita-Salute San Raffaele University, Milan, Italy; Institute of Molecular and Translational Cardiology (IMTC), San Donato Milanese, Milan, Italy
| | - Gabriele Vicedomini
- Arrhythmia and Electrophysiology Center, IRCCS Policlinico San Donato, San Donato Milanese, Milan, Italy
| | - Luigi Anastasia
- Arrhythmia and Electrophysiology Center, IRCCS Policlinico San Donato, San Donato Milanese, Milan, Italy; Vita-Salute San Raffaele University, Milan, Italy; Institute of Molecular and Translational Cardiology (IMTC), San Donato Milanese, Milan, Italy
| | - Vincenzo Santinelli
- Arrhythmia and Electrophysiology Center, IRCCS Policlinico San Donato, San Donato Milanese, Milan, Italy
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Tsumoto K, Shimamoto T, Aoji Y, Himeno Y, Kuda Y, Tanida M, Amano A, Kurata Y. Theoretical prediction of early afterdepolarization-evoked triggered activity formation initiating ventricular reentrant arrhythmias. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2023; 240:107722. [PMID: 37515880 DOI: 10.1016/j.cmpb.2023.107722] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 07/02/2023] [Accepted: 07/14/2023] [Indexed: 07/31/2023]
Abstract
BACKGROUND AND OBJECTIVE Excessive prolongation of QT interval on ECGs in patients with congenital/acquired long QT syndrome and heart failure is a sign suggesting the development of early afterdepolarization (EAD), an abnormal repolarization in the action potential of ventricular cardiomyocytes. The development of EAD has been believed to be a trigger for fatal tachyarrhythmia, which can be a risk for sudden cardiac death. The role of EAD in triggering ventricular tachycardia (VT) remains unclear. The aim of this study was to elucidate the mechanism of EAD-induced triggered activity formation that leads to the VT such as Torsades de Pointes. METHODS We investigated the relationship between EAD and tachyarrhythmia initiation by constructing homogeneous myocardial sheet models consisting of the mid-myocardial cell version of a human ventricular myocyte model and performing simulations of excitation propagation. RESULTS A solitary island-like (clustering) occurrence of EADs in the homogeneous myocardial sheet could induce a focal excitation wave. However, reentrant excitation, an entity of tachyarrhythmia, was not able to be triggered regardless of the EAD cluster size when the focal excitation wave formed a repolarization potential difference boundary consisting of only a convex surface. The discontinuous distribution of multiple EAD clusters in the ventricular tissue formed a specific repolarization heterogeneity due to the repolarization potential difference, the shape of which depended on EAD cluster size and placed intervals. We found that the triggered activity was formed in such a manner that the repolarization potential difference boundary included a concave surface. CONCLUSIONS The formation of triggered activity that led to tachyarrhythmia required not only the occurrence of EAD onset-mediated focal excitation wave but also a repolarization heterogeneity-based specific repolarization potential difference boundary shape formed within the tissue.
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Affiliation(s)
- Kunichika Tsumoto
- Department of Physiology II, Kanazawa Medical University, Uchinada 920-0293, Japan.
| | - Takao Shimamoto
- Department of Bioinformatics, College of Life Sciences, Ritsumeikan University, Kusatsu 525-8577, Japan
| | - Yuma Aoji
- Department of Bioinformatics, College of Life Sciences, Ritsumeikan University, Kusatsu 525-8577, Japan
| | - Yukiko Himeno
- Department of Bioinformatics, College of Life Sciences, Ritsumeikan University, Kusatsu 525-8577, Japan
| | - Yuhichi Kuda
- Department of Physiology II, Kanazawa Medical University, Uchinada 920-0293, Japan
| | - Mamoru Tanida
- Department of Physiology II, Kanazawa Medical University, Uchinada 920-0293, Japan
| | - Akira Amano
- Department of Bioinformatics, College of Life Sciences, Ritsumeikan University, Kusatsu 525-8577, Japan
| | - Yasutaka Kurata
- Department of Physiology II, Kanazawa Medical University, Uchinada 920-0293, Japan.
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Van Den Abeele R, Hendrickx S, Van Nieuwenhuyse E, Dunnink A, Panfilov AV, Vos MA, Wülfers EM, Vandersickel N. Directed graph mapping shows rotors maintain non-terminating and focal sources maintain self-terminating Torsade de Pointes in canine model. Front Physiol 2023; 14:1201260. [PMID: 37565147 PMCID: PMC10411729 DOI: 10.3389/fphys.2023.1201260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Accepted: 06/28/2023] [Indexed: 08/12/2023] Open
Abstract
Torsade de Pointes is a polymorphic ventricular tachycardia which is as yet incompletely understood. While the onset of a TdP episode is generally accepted to be caused by triggered activity, the mechanisms for the perpetuation is still under debate. In this study, we analysed data from 54 TdP episodes divided over 5 dogs (4 female, 1 male) with chronic atrioventricular block. Previous research on this dataset showed both reentry and triggered activity to perpetuate the arrhythmia. 13 of those TdP episodes showed reentry as part of the driving mechanism of perpetuating the episode. The remaining 41 episodes were purely ectopic. Reentry was the main mechanism in long-lasting episodes (>14 beats), while focal sources were responsible for maintaining shorter episodes. Building on these results, we re-analysed the data using directed graph mapping This program uses principles from network theory and a combination of positional data and local activation times to identify reentry loops and focal sources within the data. The results of this study are twofold. First, concerning reentry loops, we found that on average non-terminating (NT) episodes (≥10 s) show significantly more simultaneous reentry loops than self-terminating (ST) TdP (<10 s). Non-terminating episodes have on average 2.72 ± 1.48 simultaneous loops, compared to an average of 1.33 ± 0.66 for self-terminating episodes. In addition, each NT episode showed a presence of (bi-)ventricular loops between 10.10% and 69.62% of their total reentry duration. Compared to the ST episodes, only 1 in 4 episodes (25%) showed (bi-)ventricular reentry, lasting only 7.12% of its total reentry duration. This suggests that while focal beats trigger TdP, macro-reentry and multiple simultaneous localized reentries are the major drivers of long-lasting episodes. Second, using heatmaps, we found focal sources to occur in preferred locations, instead of being distributed randomly. This may have implications on treatment if such focal origins can be disabled reliably.
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Affiliation(s)
- Robin Van Den Abeele
- Biophysics Group, Department of Physics and Astronomy, Faculty of Sciences, Ghent University, Ghent, Belgium
| | - Sander Hendrickx
- Biophysics Group, Department of Physics and Astronomy, Faculty of Sciences, Ghent University, Ghent, Belgium
| | - Enid Van Nieuwenhuyse
- Biophysics Group, Department of Physics and Astronomy, Faculty of Sciences, Ghent University, Ghent, Belgium
| | - Albert Dunnink
- Department of Medical Physiology, University Medical Center Utrecht, Utrecht, Netherlands
| | - Alexander V. Panfilov
- Biophysics Group, Department of Physics and Astronomy, Faculty of Sciences, Ghent University, Ghent, Belgium
- Laboratory of Computational Biology and Medicine, Ural Federal University, Yekaterinburg, Russia
- World-Class Research Center “Digital Biodesign and Personalized Healthcare”, Sechenov University, Moscow, Russia
| | - Marc A. Vos
- Department of Medical Physiology, University Medical Center Utrecht, Utrecht, Netherlands
| | - Eike M. Wülfers
- Biophysics Group, Department of Physics and Astronomy, Faculty of Sciences, Ghent University, Ghent, Belgium
| | - Nele Vandersickel
- Biophysics Group, Department of Physics and Astronomy, Faculty of Sciences, Ghent University, Ghent, Belgium
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DG-Mapping: a novel software package for the analysis of any type of reentry and focal activation of simulated, experimental or clinical data of cardiac arrhythmia. Med Biol Eng Comput 2022; 60:1929-1945. [DOI: 10.1007/s11517-022-02550-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Accepted: 02/13/2022] [Indexed: 01/24/2023]
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Odening KE, van der Linde HJ, Ackerman MJ, Volders PGA, ter Bekke RMA. OUP accepted manuscript. Eur Heart J 2022; 43:3018-3028. [PMID: 35445703 PMCID: PMC9443984 DOI: 10.1093/eurheartj/ehac135] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2021] [Revised: 02/23/2022] [Accepted: 03/03/2022] [Indexed: 11/13/2022] Open
Abstract
An abundance of literature describes physiological and pathological determinants of cardiac performance, building on the principles of excitation–contraction coupling. However, the mutual influencing of excitation–contraction and mechano-electrical feedback in the beating heart, here designated ‘electromechanical reciprocity’, remains poorly recognized clinically, despite the awareness that external and cardiac-internal mechanical stimuli can trigger electrical responses and arrhythmia. This review focuses on electromechanical reciprocity in the long-QT syndrome (LQTS), historically considered a purely electrical disease, but now appreciated as paradigmatic for the understanding of mechano-electrical contributions to arrhythmogenesis in this and other cardiac conditions. Electromechanical dispersion in LQTS is characterized by heterogeneously prolonged ventricular repolarization, besides altered contraction duration and relaxation. Mechanical alterations may deviate from what would be expected from global and regional repolarization abnormalities. Pathological repolarization prolongation outlasts mechanical systole in patients with LQTS, yielding a negative electromechanical window (EMW), which is most pronounced in symptomatic patients. The electromechanical window is a superior and independent arrhythmia-risk predictor compared with the heart rate-corrected QT. A negative EMW implies that the ventricle is deformed—by volume loading during the rapid filling phase—when repolarization is still ongoing. This creates a ‘sensitized’ electromechanical substrate, in which inadvertent electrical or mechanical stimuli such as local after-depolarizations, after-contractions, or dyssynchrony can trigger abnormal impulses. Increased sympathetic-nerve activity and pause-dependent potentiation further exaggerate electromechanical heterogeneities, promoting arrhythmogenesis. Unraveling electromechanical reciprocity advances the understanding of arrhythmia formation in various conditions. Real-time image integration of cardiac electrophysiology and mechanics offers new opportunities to address challenges in arrhythmia management.
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Affiliation(s)
| | - Henk J van der Linde
- Janssen Research & Development, Division of Janssen Pharmaceutica N.V., Beerse, Belgium
| | - Michael J Ackerman
- Department of Cardiovascular Medicine, Division of Heart Rhythm Services (Windland Smith Rice Genetic Heart Rhythm Clinic), Mayo Clinic, Rochester, MN, USA
- Department of Pediatric and Adolescent Medicine, Division of Pediatric Cardiology, Mayo Clinic, Rochester, MN, USA
- Department of Molecular Pharmacology & Experimental Therapeutics (Windland Smith Rice Sudden Death Genomics Laboratory), Mayo Clinic, Rochester, MN, USA
| | - Paul G A Volders
- Department of Cardiology, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University Medical Center+, P. Debyelaan 25, 6229 HX, Maastricht, The Netherlands
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Smoczyńska A, Aarnink EW, Dunnink A, Bossu A, van Weperen VYH, Meijborg VMF, Beekman HDM, Coronel R, Vos MA. Interplay between temporal and spatial dispersion of repolarization in the initiation and perpetuation of torsades de pointes in the chronic atrioventricular block dog. Am J Physiol Heart Circ Physiol 2021; 321:H569-H576. [PMID: 34355987 DOI: 10.1152/ajpheart.00945.2020] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Ventricular arrhythmias, consisting of single ectopic beats (sEB), multiple EB (mEB), and torsades de pointes (TdP, defined as ≥5 beats with QRS vector twisting around isoelectric line) can be induced in the anesthetized chronic atrioventricular block (CAVB) dog by dofetilide (IKr blocker). The interplay between temporal dispersion of repolarization, quantified as short-term variability (STV), and spatial dispersion of repolarization (SDR) in the initiation and perpetuation of these arrhythmias remains unclear. Five inducible (≥3 TdPs/10 min) CAVB dogs underwent one mapping experiment and were observed for 10 min from the start of dofetilide infusion (0.025 mg/kg, 5 min). An intracardiac decapolar electrogram (EGM) catheter and 30 intramural cardiac needles in the left ventricle (LV) were introduced. STVARI was derived from 31 consecutive activation recovery intervals (ARIs) on the intracardiac EGM, using the formula: [Formula: see text]. The mean SDR3D in the LV was determined as the three-dimensional repolarization time differences between the intramural cardiac needles. Moments of measurement included baseline (BL) and after dofetilide infusion before first 1) sEB (occurrence at 100 ± 35 s), 2) mEB (224 ± 96 s), and 3) non-self-terminating TdP (454 ± 298 s). STVARI increased from 2.15 ± 0.32 ms at BL to 3.73 ± 0.99 ms* before the first sEB and remained increased without further significant progression to mEB (4.41 ± 0.45 ms*) and TdP (5.07 ± 0.84 ms*) (*P < 0.05 compared with BL). SDR3D did not change from 31 ± 11 ms at BL to 43 ± 13 ms before sEB but increased significantly before mEB (68 ± 7 ms*) and to TdP (86 ± 9 ms*+) (+P < 0.05 compared with sEB). An increase in STV contributes to the initiation of sEB, whereas an increase in SDR is important for the perpetuation of non-self-terminating TdPs.NEW & NOTEWORTHY This study compared two well-established electrophysiological parameters, being temporal and spatial dispersion of repolarization, and provided new insights into their interplay in the arrhythmogenesis of torsades de pointes arrhythmias. Although it confirmed that an increase in temporal dispersion of repolarization contributes to the initiation of single ectopic beats, it showed that an increase in spatial dispersion of repolarization is important for the perpetuation of non-self-terminating torsades de pointes arrhythmias.
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Affiliation(s)
- Agnieszka Smoczyńska
- Department of Medical Physiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Errol W Aarnink
- Department of Medical Physiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Albert Dunnink
- Department of Medical Physiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Alexandre Bossu
- Department of Medical Physiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Valerie Y H van Weperen
- Department of Medical Physiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Veronique M F Meijborg
- Department of Clinical and Experimental Cardiology, Academic Medical Center, Amsterdam, The Netherlands.,Netherlands Heart Institute, Holland Heart House, Utrecht, The Netherlands
| | - Henriëtte D M Beekman
- Department of Medical Physiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - R Coronel
- Department of Clinical and Experimental Cardiology, Academic Medical Center, Amsterdam, The Netherlands
| | - Marc A Vos
- Department of Medical Physiology, University Medical Center Utrecht, Utrecht, The Netherlands
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10
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Abstract
Atrial fibrillation (AF), the common sustained arrhythmia in clinical practice, has major public health implications due to its associated morbidity and increased mortality. The AF epidemic is due to the burgeoning elderly population and the identification of novel risk factors, for example, genetics. Since the diagnosis of AF has a major impact on the clinical assessment and management of patients with inherited arrhythmia syndromes, improved understanding of the cause and pathogenesis of AF has provided important insights into the underlying pathophysiological mechanisms of this common arrhythmia and identified potential mechanism-based therapies.
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Affiliation(s)
- Baha'a Al-Azaam
- Division of Cardiology, Department of Medicine, University of Illinois at Chicago, 820 S Wood Street, Suite 920S, Chicago, IL 60612, USA; Division of Cardiology, Department of Pharmacology, University of Illinois at Chicago, 820 S Wood Street, Suite 920S, Chicago, IL 60612, USA
| | - Dawood Darbar
- Division of Cardiology, Department of Medicine, University of Illinois at Chicago, 820 S Wood Street, Suite 920S, Chicago, IL 60612, USA; Division of Cardiology, Department of Pharmacology, University of Illinois at Chicago, 820 S Wood Street, Suite 920S, Chicago, IL 60612, USA; Department of Medicine, Jesse Brown Veterans Administration, 820 S Wood Street, Suite 920S, Chicago, IL 60612, USA.
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11
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Himel HD, Cupelli M, Boutjdir M, El-Sherif N. Voltage/Calcium Uncoupling Underlies Sustained Torsade de Pointes Ventricular Tachyarrhythmia in an Experimental Model of Long QT Syndrome. Front Physiol 2021; 12:617847. [PMID: 33584347 PMCID: PMC7876465 DOI: 10.3389/fphys.2021.617847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 01/12/2021] [Indexed: 11/23/2022] Open
Abstract
Background Clinical experience showed that the majority of Torsade de Pointes (TdP) ventricular tachyarrhythmia (VT) in patients with long QT syndrome (LQTS) are self-terminating (ST), but the few that are non-self-terminating (NST) are potentially fatal. A paramount issue in clinical arrhythmology is to understand the electrophysiological mechanism of ST vs. NST TdP VT. Methods We investigated the electrophysiological mechanism of ST vs. NST TdP VT in the guinea pig Anthopleurin-A experimental model of LQTS, a close surrogate model of congenital LQT3. We utilized simultaneous optical recordings of membrane voltage (Vm) and intracellular calcium (Cai) and a robust analytical method based on spatiotemporal entropy difference (Ed) to investigate the hypothesis that early Vm/Cai uncoupling during TdP VT can play a primary role in perpetuation of VT episodes. Results We analyzed a total of 35 episodes of TdP VT from 14 guinea pig surrogate models of LQTS, including 23 ST and 12 NST VTs. Ed values for NST VT were significantly higher than Ed values for ST VT. Analysis of wave front topology during the early phase of ST VT showed the Cai wave front following closely Vm wave front consistent with a lower degree of Ed. In contrast, NST VT was associated with uncoupling of Vm/Cai wave fronts during the first 2 or 3 cycles of VT associated with early wave break propagation pattern. Conclusions Utilizing a robust analytical method we showed that, in comparison to ST TdP VT, NST VT was consistently predated by early uncoupling of Vm/Cai that destabilized wave front propagation and can explain a sustained complex reentrant excitation pattern.
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Affiliation(s)
- Herman D Himel
- Veterans Affairs New York Harbor Healthcare System, Brooklyn, NY, United States
| | - Michael Cupelli
- Veterans Affairs New York Harbor Healthcare System, Brooklyn, NY, United States.,Downstate Medical Center, State University of New York, Brooklyn, NY, United States
| | - Mohamed Boutjdir
- Veterans Affairs New York Harbor Healthcare System, Brooklyn, NY, United States.,Downstate Medical Center, State University of New York, Brooklyn, NY, United States.,School of Medicine, New York University, New York, NY, United States
| | - Nabil El-Sherif
- Veterans Affairs New York Harbor Healthcare System, Brooklyn, NY, United States.,Downstate Medical Center, State University of New York, Brooklyn, NY, United States
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12
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Piktel JS, Wilson LD. Translational Models of Arrhythmia Mechanisms and Susceptibility: Success and Challenges of Modeling Human Disease. Front Cardiovasc Med 2019; 6:135. [PMID: 31552276 PMCID: PMC6748164 DOI: 10.3389/fcvm.2019.00135] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Accepted: 08/27/2019] [Indexed: 01/10/2023] Open
Abstract
We discuss large animal translational models of arrhythmia susceptibility and sudden cardiac death, focusing on important considerations when interpreting the data derived before applying them to human trials. The utility of large animal models of arrhythmia and the pros and cons of specific translational large animals used will be discussed, including the necessary tradeoffs between models designed to derive mechanisms vs. those to test therapies. Recent technical advancements which can be applied to large animal models of arrhythmias to better elucidate mechanistic insights will be introduced. Finally, some specific examples of past successes and challenges in translating the results of large animal models of arrhythmias to clinical trials and practice will be examined, and common themes regarding the success and failure of translating studies to therapy in man will be discussed.
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Affiliation(s)
| | - Lance D. Wilson
- Department of Emergency Medicine, Emergency Care Research Institute and Heart and Vascular Research Center, MetroHealth Campus of Case Western Reserve University, Cleveland, OH, United States
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13
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Smoczynska A, Beekman HD, Vos MA. The Increment of Short-term Variability of Repolarisation Determines the Severity of the Imminent Arrhythmic Outcome. Arrhythm Electrophysiol Rev 2019; 8:166-172. [PMID: 31576205 PMCID: PMC6766692 DOI: 10.15420/aer.2019.16.2] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Ventricular remodelling can make the heart more susceptible to ventricular arrhythmias like torsades de pointes. Understanding the underlying mechanisms of initiation of ventricular arrhythmias and the determining factors for its severity has the potential to uncover new interventions. Beat-to-beat variation of repolarisation, quantified as short-term variability of repolarisation (STV), has been identified as an important factor contributing to arrhythmogenesis. This article provides an overview of experimental data about STV in relation to the initiation of torsades de pointes in a canine model of complete chronic atrioventricular block susceptible to torsades de pointes arrhythmias. Furthermore, it explores STV in relation to the severity of the arrhythmic outcome.
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Affiliation(s)
- Agnieszka Smoczynska
- Department of Medical Physiology, University Medical Center Utrecht Utrecht, the Netherlands
| | - Henriëtte Dm Beekman
- Department of Medical Physiology, University Medical Center Utrecht Utrecht, the Netherlands
| | - Marc A Vos
- Department of Medical Physiology, University Medical Center Utrecht Utrecht, the Netherlands
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14
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El-Sherif N, Turitto G, Boutjdir M. Acquired Long QT Syndrome and Electrophysiology of Torsade de Pointes. Arrhythm Electrophysiol Rev 2019; 8:122-130. [PMID: 31114687 PMCID: PMC6528034 DOI: 10.15420/aer.2019.8.3] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Accepted: 04/04/2019] [Indexed: 12/16/2022] Open
Abstract
Congenital long QT syndrome (LQTS) has been the most investigated cardiac ion channelopathy. Although congenital LQTS remains the domain of cardiologists, cardiac electrophysiologists and specialised centres, the much more frequently acquired LQTS is the domain of physicians and other members of healthcare teams required to make therapeutic decisions. This paper reviews the electrophysiological mechanisms of acquired LQTS, its ECG characteristics, clinical presentation, and management. The paper concludes with a comprehensive review of the electrophysiological mechanisms of torsade de pointes.
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Affiliation(s)
- Nabil El-Sherif
- SUNY Downstate Medical CenterNY, US
- VA NY Harbor Healthcare SystemNY, US
| | - Gioia Turitto
- Weill Cornell Medical College, NewYork-Presbyterian Brooklyn Methodist HospitalNY, US
| | - Mohamed Boutjdir
- SUNY Downstate Medical CenterNY, US
- VA NY Harbor Healthcare SystemNY, US
- NYU School of MedicineNew York NY, US
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15
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Himel HD, Cupelli M, Gantt M, Boutjdir M, El-Sherif N. Role of spatial dispersion of repolarization in reentry around a functional core versus reentry around a fixed anatomical core. Ann Noninvasive Electrocardiol 2019; 24:e12647. [PMID: 30896072 DOI: 10.1111/anec.12647] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Revised: 01/16/2019] [Accepted: 01/17/2019] [Indexed: 11/27/2022] Open
Abstract
INTRODUCTION Successful initiation of spiral wave reentry in the neonatal rat ventricular myocyte (NRVM) monolayer implicitly assumes the presence of spatial dispersion of repolarization (DR), which is difficult to quantify. We recently introduced a NRVM monolayer that utilizes anthopleurin-A to impart a prolonged plateau to the NRVM action potential. This was associated with a significant degree of spatial DR that lends itself to accurate quantification. METHODS AND RESULTS We utilized the monolayer and fluorescence optical mapping of intracellular calcium transients (FCai ) to systematically study and compare the contribution of spatial dispersion of the duration of FCai (as a surrogate of DR) to induction of spiral wave reentry around a functional core versus reentry around a fixed anatomical obstacle. We show that functional reentry could be initiated by a premature stimulus acting on a substrate of spatial DR resulting in a functional line of propagation block. Subsequent wave fronts circulated around a central core of functional obstacle created by sustained depolarization from the circulating wave front. Both initiation and termination of spiral wave reentry around an anatomical obstacle consistently required participation of a region of functional propagation block. This region was similarly based on spatial DR. Spontaneous termination of spiral wave reentry also resulted from block in the functional component of the circuit obstacle, usually preceded by beat-to-beat slowing of propagation. CONCLUSIONS The study demonstrates the critical contribution of DR to spiral wave reentry around a purely functional core as well as reentry around a fixed anatomical core.
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Affiliation(s)
| | - Michael Cupelli
- VA New York Harbor VA Healthcare System, Brooklyn, NY.,Downstate Medical Center, State University of New York, Brooklyn, NY
| | - Martin Gantt
- VA New York Harbor VA Healthcare System, Brooklyn, NY
| | - Mohamed Boutjdir
- VA New York Harbor VA Healthcare System, Brooklyn, NY.,Downstate Medical Center, State University of New York, Brooklyn, NY.,New York University School of Medicine, New York, NY
| | - Nabil El-Sherif
- VA New York Harbor VA Healthcare System, Brooklyn, NY.,Downstate Medical Center, State University of New York, Brooklyn, NY
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16
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Li GL, Saguner AM, Fontaine GH, Frank R. Fragmented endocardial signals and early afterdepolarizations during torsades de pointes tachycardia. Cardiol J 2018; 27:54-61. [PMID: 30009377 DOI: 10.5603/cj.a2018.0070] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Revised: 07/08/2018] [Accepted: 07/08/2018] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Bradycardia-induced torsade de pointes (TdP) tachycardia in patients with spontaneous high-degree atrioventricular block (AVB) is common. The aim of this study was to analyze endocardial recordings during TdP in spontaneous high-degree AVB in humans to better understand the electrophysiological mechanisms underlying this phenomenon. METHODS The study group consisted of 5 patients with typical episodes of TdP during spontaneous high-degree AVB. A standard (USCI) temporary bipolar endocardial catheter positioned at the apex of the right ventricle (RV) and bipolar chest leads from two precordial leads V1 and V4 were used to record the tracings during TdP. RESULTS The presence of a wide spectrum of fragmentations was noted on endocardial electrograms (EGMs), which were invisible on the surface electrocardiogram (ECG) tracing. Endocardial signals indicated that TdP started in the proximity of the RV apex, since the local EGM began prior to the QRS complex on the surface ECG. Early afterdepolarizations (EADs) were observed in 2 out of 5 cases confirming a common opinion about the mechanism of TdP. However, this phenomenon was not observed in 3 other patients suggesting that the arrhythmia was the result of a different mechanism originating in proximity to the RV apex. CONCLUSIONS This work demonstrated early endocardial signals in the RV apex during TdP associated with high-degree AVB in humans, and exhibits a spectrum of fragmented signals in this area occurring on a single or multiple beats. These fragmentations indicate areas of poor conduction and various degrees of intramyocardial block, and therefore a new mechanism of TdP tachycardia in some patients with spontaneous high-degree AVB.
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Affiliation(s)
- Guo-Liang Li
- Arrhythmia Unit, Department of Cardiovascular Medicine, First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi, P.R. China. .,Institut de Cardiologie, Unité de Rythmologie, Groupe Hospitalier Pitié-Salpêtrière, Paris, France.
| | - Ardan M Saguner
- Department of Cardiology, University Heart Center Zurich, Switzerland
| | - Guy H Fontaine
- Institut de Cardiologie, Unité de Rythmologie, Groupe Hospitalier Pitié-Salpêtrière, Paris, France
| | - Robert Frank
- Institut de Cardiologie, Unité de Rythmologie, Groupe Hospitalier Pitié-Salpêtrière, Paris, France
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17
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El-Sherif N, Turitto G, Boutjdir M. Acquired long QT syndrome and torsade de pointes. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2018; 41:414-421. [PMID: 29405316 DOI: 10.1111/pace.13296] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Revised: 12/13/2017] [Accepted: 12/22/2017] [Indexed: 01/08/2023]
Abstract
Since its initial description by Jervell and Lange-Nielsen in 1957, the congenital long QT syndrome (LQTS) has been the most investigated cardiac ion channelopathy. Although congenital LQTS continues to remain the domain of cardiologists, cardiac electrophysiologists, and specialized centers, the by far more frequent acquired drug-induced LQTS is the domain of all physicians and other members of the health care team who are required to make therapeutic decisions. This report will review the electrophysiological mechanisms of LQTS and torsade de pointes, electrocardiographic characteristics of acquired LQTS, its clinical presentation, management, and future directions in the field.
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Affiliation(s)
- Nabil El-Sherif
- Downstate Medical Center, State University of New York, New York, NY, USA.,VA NY Harbor Healthcare System, New York, NY, USA
| | - Gioia Turitto
- New York-Presbyterian Brooklyn Methodist Hospital, New York, NY, USA
| | - Mohamed Boutjdir
- Downstate Medical Center, State University of New York, New York, NY, USA.,VA NY Harbor Healthcare System, New York, NY, USA.,NYU School of Medicine, New York, NY, USA
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18
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Boukens BJ, Meijborg VMF, Belterman CN, Opthof T, Janse MJ, Schuessler RB, Coronel R, Efimov IR. Local transmural action potential gradients are absent in the isolated, intact dog heart but present in the corresponding coronary-perfused wedge. Physiol Rep 2018; 5:e13251. [PMID: 28554962 PMCID: PMC5449556 DOI: 10.14814/phy2.13251] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Revised: 03/20/2017] [Accepted: 03/20/2017] [Indexed: 11/24/2022] Open
Abstract
The left ventricular (LV) coronary‐perfused canine wedge preparation is a model commonly used for studying cardiac repolarization. In wedge studies, transmembrane potentials typically are recorded; whereas, extracellular electrical recordings are commonly used in intact hearts. We compared electrically measured activation recovery interval (ARI) patterns in the intact heart with those recorded at the same location in the LV wedge preparation. We also compared electrically recorded and optically obtained ARIs in the LV wedge preparation. Five Langendorff‐perfused canine hearts were paced from the right atrium. Local activation and repolarization times were measured with eight transmural needle electrodes. Subsequently, left ventricular coronary‐perfused wedge preparations were prepared from these hearts while the electrodes remained in place. Three electrodes remained at identical positions as in the intact heart. Both electrograms and optical action potentials were recorded (pacing cycle length 400–4000 msec) and activation and repolarization patterns were analyzed. ARIs found in the subepicardium were shorter than in the subendocardium in the LV wedge preparation but not in the intact heart. The transmural ARI gradient recorded at the cut surface of the wedge was not different from that recorded internally. ARIs recorded internally and at the cut surface in the LV wedge preparation, both correlated with optically recorded action potentials. ARI and RT gradients in the LV wedge preparation differed from those in the intact canine heart, implying that those observations in human LV wedge preparations also should be extrapolated to the intact human heart with caution.
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Affiliation(s)
- Bastiaan J Boukens
- Department of Biomedical Engineering, George Washington University, Washington, District of Columbia.,Department of Medical Biology, University of Amsterdam, Amsterdam, The Netherlands
| | - Veronique M F Meijborg
- Department of Experimental and Clinical Cardiology, University of Amsterdam, Amsterdam, The Netherlands.,Netherlands Heart Institute, Holland Heart House, Utrecht, The Netherlands
| | - Charly N Belterman
- Department of Experimental and Clinical Cardiology, University of Amsterdam, Amsterdam, The Netherlands.,Institut LIRYC, Electrophysiology and Heart Modeling Institute, fondation Bordeaux Université, Pessac- Bordeaux, France
| | - Tobias Opthof
- Department of Experimental and Clinical Cardiology, University of Amsterdam, Amsterdam, The Netherlands.,Department of Medical Physiology, University of Utrecht, Utrecht, The Netherlands
| | - Michiel J Janse
- Department of Experimental and Clinical Cardiology, University of Amsterdam, Amsterdam, The Netherlands
| | | | - Ruben Coronel
- Department of Experimental and Clinical Cardiology, University of Amsterdam, Amsterdam, The Netherlands.,Institut LIRYC, Electrophysiology and Heart Modeling Institute, fondation Bordeaux Université, Pessac- Bordeaux, France
| | - Igor R Efimov
- Department of Biomedical Engineering, George Washington University, Washington, District of Columbia.,Institut LIRYC, Electrophysiology and Heart Modeling Institute, fondation Bordeaux Université, Pessac- Bordeaux, France
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19
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Vandersickel N, Bossu A, De Neve J, Dunnink A, Meijborg VM, van der Heyden MA, Beekman JD, De Bakker JM, Vos MA, Panfilov AV. Short-Lasting Episodes of Torsade de Pointes in the Chronic Atrioventricular Block Dog Model Have a Focal Mechanism, While Longer-Lasting Episodes Are Maintained by Re-Entry. JACC Clin Electrophysiol 2017; 3:1565-1576. [DOI: 10.1016/j.jacep.2017.06.016] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Accepted: 06/01/2017] [Indexed: 10/18/2022]
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20
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Leybaert L, Lampe PD, Dhein S, Kwak BR, Ferdinandy P, Beyer EC, Laird DW, Naus CC, Green CR, Schulz R. Connexins in Cardiovascular and Neurovascular Health and Disease: Pharmacological Implications. Pharmacol Rev 2017; 69:396-478. [PMID: 28931622 PMCID: PMC5612248 DOI: 10.1124/pr.115.012062] [Citation(s) in RCA: 171] [Impact Index Per Article: 24.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Connexins are ubiquitous channel forming proteins that assemble as plasma membrane hemichannels and as intercellular gap junction channels that directly connect cells. In the heart, gap junction channels electrically connect myocytes and specialized conductive tissues to coordinate the atrial and ventricular contraction/relaxation cycles and pump function. In blood vessels, these channels facilitate long-distance endothelial cell communication, synchronize smooth muscle cell contraction, and support endothelial-smooth muscle cell communication. In the central nervous system they form cellular syncytia and coordinate neural function. Gap junction channels are normally open and hemichannels are normally closed, but pathologic conditions may restrict gap junction communication and promote hemichannel opening, thereby disturbing a delicate cellular communication balance. Until recently, most connexin-targeting agents exhibited little specificity and several off-target effects. Recent work with peptide-based approaches has demonstrated improved specificity and opened avenues for a more rational approach toward independently modulating the function of gap junctions and hemichannels. We here review the role of connexins and their channels in cardiovascular and neurovascular health and disease, focusing on crucial regulatory aspects and identification of potential targets to modify their function. We conclude that peptide-based investigations have raised several new opportunities for interfering with connexins and their channels that may soon allow preservation of gap junction communication, inhibition of hemichannel opening, and mitigation of inflammatory signaling.
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Affiliation(s)
- Luc Leybaert
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Paul D Lampe
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Stefan Dhein
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Brenda R Kwak
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Peter Ferdinandy
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Eric C Beyer
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Dale W Laird
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Christian C Naus
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Colin R Green
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Rainer Schulz
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
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El-Sherif N, Turitto G, Boutjdir M. Congenital Long QT syndrome and torsade de pointes. Ann Noninvasive Electrocardiol 2017; 22. [PMID: 28670758 DOI: 10.1111/anec.12481] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Accepted: 05/19/2017] [Indexed: 12/19/2022] Open
Abstract
Since its initial description by Jervell and Lange-Nielsen in 1957, the congenital long QT syndrome (LQTS) has been the most investigated cardiac ion channelopathy. A prolonged QT interval in the surface electrocardiogram is the sine qua non of the LQTS and is a surrogate measure of the ventricular action potential duration (APD). Congenital as well as acquired alterations in certain cardiac ion channels can affect their currents in such a way as to increase the APD and hence the QT interval. The inhomogeneous lengthening of the APD across the ventricular wall results in dispersion of APD. This together with the tendency of prolonged APD to be associated with oscillations at the plateau level, termed early afterdepolarizations (EADs), provides the substrate of ventricular tachyarrhythmia associated with LQTS, usually referred to as torsade de pointes (TdP) VT. This review will discuss the genetic, molecular, and phenotype characteristics of congenital LQTS as well as current management strategies and future directions in the field.
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Affiliation(s)
- Nabil El-Sherif
- Downstate Medical Center, State University of New York, Brooklyn, NY, USA.,VA NY Harbor Healthcare System, Brooklyn, NY, USA
| | - Gioia Turitto
- NewYork-Presbyterian Brooklyn Methodist Hospital, New York, NY, USA
| | - Mohamed Boutjdir
- Downstate Medical Center, State University of New York, Brooklyn, NY, USA.,VA NY Harbor Healthcare System, Brooklyn, NY, USA.,NYU School of Medicine, New York, NY, USA
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22
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Osadchii OE. Role of abnormal repolarization in the mechanism of cardiac arrhythmia. Acta Physiol (Oxf) 2017; 220 Suppl 712:1-71. [PMID: 28707396 DOI: 10.1111/apha.12902] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
In cardiac patients, life-threatening tachyarrhythmia is often precipitated by abnormal changes in ventricular repolarization and refractoriness. Repolarization abnormalities typically evolve as a consequence of impaired function of outward K+ currents in cardiac myocytes, which may be caused by genetic defects or result from various acquired pathophysiological conditions, including electrical remodelling in cardiac disease, ion channel modulation by clinically used pharmacological agents, and systemic electrolyte disorders seen in heart failure, such as hypokalaemia. Cardiac electrical instability attributed to abnormal repolarization relies on the complex interplay between a provocative arrhythmic trigger and vulnerable arrhythmic substrate, with a central role played by the excessive prolongation of ventricular action potential duration, impaired intracellular Ca2+ handling, and slowed impulse conduction. This review outlines the electrical activity of ventricular myocytes in normal conditions and cardiac disease, describes classical electrophysiological mechanisms of cardiac arrhythmia, and provides an update on repolarization-related surrogates currently used to assess arrhythmic propensity, including spatial dispersion of repolarization, activation-repolarization coupling, electrical restitution, TRIaD (triangulation, reverse use dependence, instability, and dispersion), and the electromechanical window. This is followed by a discussion of the mechanisms that account for the dependence of arrhythmic vulnerability on the location of the ventricular pacing site. Finally, the review clarifies the electrophysiological basis for cardiac arrhythmia produced by hypokalaemia, and gives insight into the clinical importance and pathophysiology of drug-induced arrhythmia, with particular focus on class Ia (quinidine, procainamide) and Ic (flecainide) Na+ channel blockers, and class III antiarrhythmic agents that block the delayed rectifier K+ channel (dofetilide).
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Affiliation(s)
- O. E. Osadchii
- Department of Health Science and Technology; University of Aalborg; Aalborg Denmark
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Shah AJ, Hocini M, Denis A, Derval N, Sacher F, Jais P, Haissaguerre M. Polymorphic Ventricular Tachycardia/Ventricular Fibrillation and Sudden Cardiac Death in the Normal Heart. Card Electrophysiol Clin 2016; 8:581-591. [PMID: 27521091 DOI: 10.1016/j.ccep.2016.04.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Primary electrical diseases manifest with polymorphic ventricular tachycardia (PMVT) and ventricular fibrillation (VF) and along with idiopathic VF contribute to about 10% of sudden cardiac deaths (SCDs) overall. These disorders include long QT syndrome, Brugada syndrome, catecholaminergic polymorphic ventricular tachycardia, short QT syndrome, and early repolarization syndrome. This article reviews the clinical electrophysiological management of PMVT/VF in a structurally normal heart affected with these disorders.
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Affiliation(s)
- Ashok J Shah
- Cardio Vascular Services, South Consulting Suites, Peel Health Campus, 110 Lakes Road, Mandurah, Western Australia 6210, Australia.
| | - Meleze Hocini
- Department of Electrophysiology and Cardiac Pacing, Hôpital Cardiologique du Haut Lévêque, Avenue de Magellan, Pessac Cedex 33604, France
| | - Arnaud Denis
- Department of Electrophysiology and Cardiac Pacing, Hôpital Cardiologique du Haut Lévêque, Avenue de Magellan, Pessac Cedex 33604, France
| | - Nicolas Derval
- Department of Electrophysiology and Cardiac Pacing, Hôpital Cardiologique du Haut Lévêque, Avenue de Magellan, Pessac Cedex 33604, France
| | - Frederic Sacher
- Department of Electrophysiology and Cardiac Pacing, Hôpital Cardiologique du Haut Lévêque, Avenue de Magellan, Pessac Cedex 33604, France
| | - Pierre Jais
- Department of Electrophysiology and Cardiac Pacing, Hôpital Cardiologique du Haut Lévêque, Avenue de Magellan, Pessac Cedex 33604, France
| | - Michel Haissaguerre
- Department of Electrophysiology and Cardiac Pacing, Hôpital Cardiologique du Haut Lévêque, Avenue de Magellan, Pessac Cedex 33604, France.
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25
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Madhvani RV, Angelini M, Xie Y, Pantazis A, Suriany S, Borgstrom NP, Garfinkel A, Qu Z, Weiss JN, Olcese R. Targeting the late component of the cardiac L-type Ca2+ current to suppress early afterdepolarizations. ACTA ACUST UNITED AC 2016; 145:395-404. [PMID: 25918358 PMCID: PMC4411259 DOI: 10.1085/jgp.201411288] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Early afterdepolarizations (EADs) associated with prolongation of the cardiac action potential (AP) can create heterogeneity of repolarization and premature extrasystoles, triggering focal and reentrant arrhythmias. Because the L-type Ca(2+) current (ICa,L) plays a key role in both AP prolongation and EAD formation, L-type Ca(2+) channels (LTCCs) represent a promising therapeutic target to normalize AP duration (APD) and suppress EADs and their arrhythmogenic consequences. We used the dynamic-clamp technique to systematically explore how the biophysical properties of LTCCs could be modified to normalize APD and suppress EADs without impairing excitation-contraction coupling. Isolated rabbit ventricular myocytes were first exposed to H2O2 or moderate hypokalemia to induce EADs, after which their endogenous ICa,L was replaced by a virtual ICa,L with tunable parameters, in dynamic-clamp mode. We probed the sensitivity of EADs to changes in the (a) amplitude of the noninactivating pedestal current; (b) slope of voltage-dependent activation; (c) slope of voltage-dependent inactivation; (d) time constant of voltage-dependent activation; and (e) time constant of voltage-dependent inactivation. We found that reducing the amplitude of the noninactivating pedestal component of ICa,L effectively suppressed both H2O2- and hypokalemia-induced EADs and restored APD. These results, together with our previous work, demonstrate the potential of this hybrid experimental-computational approach to guide drug discovery or gene therapy strategies by identifying and targeting selective properties of LTCC.
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Affiliation(s)
- Roshni V Madhvani
- Division of Molecular Medicine, Department of Anesthesiology, Department of Medicine (Cardiology), Department of Physiology, Department of Integrative Biology and Physiology, Cardiovascular Research Laboratory, and Brain Research Institute, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA 90095
| | - Marina Angelini
- Division of Molecular Medicine, Department of Anesthesiology, Department of Medicine (Cardiology), Department of Physiology, Department of Integrative Biology and Physiology, Cardiovascular Research Laboratory, and Brain Research Institute, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA 90095
| | - Yuanfang Xie
- Department of Pharmacology, University of California, Davis, Davis, CA 95616
| | - Antonios Pantazis
- Division of Molecular Medicine, Department of Anesthesiology, Department of Medicine (Cardiology), Department of Physiology, Department of Integrative Biology and Physiology, Cardiovascular Research Laboratory, and Brain Research Institute, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA 90095
| | - Silvie Suriany
- Division of Molecular Medicine, Department of Anesthesiology, Department of Medicine (Cardiology), Department of Physiology, Department of Integrative Biology and Physiology, Cardiovascular Research Laboratory, and Brain Research Institute, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA 90095
| | - Nils P Borgstrom
- Division of Molecular Medicine, Department of Anesthesiology, Department of Medicine (Cardiology), Department of Physiology, Department of Integrative Biology and Physiology, Cardiovascular Research Laboratory, and Brain Research Institute, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA 90095
| | - Alan Garfinkel
- Division of Molecular Medicine, Department of Anesthesiology, Department of Medicine (Cardiology), Department of Physiology, Department of Integrative Biology and Physiology, Cardiovascular Research Laboratory, and Brain Research Institute, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA 90095 Division of Molecular Medicine, Department of Anesthesiology, Department of Medicine (Cardiology), Department of Physiology, Department of Integrative Biology and Physiology, Cardiovascular Research Laboratory, and Brain Research Institute, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA 90095 Division of Molecular Medicine, Department of Anesthesiology, Department of Medicine (Cardiology), Department of Physiology, Department of Integrative Biology and Physiology, Cardiovascular Research Laboratory, and Brain Research Institute, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA 90095
| | - Zhilin Qu
- Division of Molecular Medicine, Department of Anesthesiology, Department of Medicine (Cardiology), Department of Physiology, Department of Integrative Biology and Physiology, Cardiovascular Research Laboratory, and Brain Research Institute, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA 90095 Division of Molecular Medicine, Department of Anesthesiology, Department of Medicine (Cardiology), Department of Physiology, Department of Integrative Biology and Physiology, Cardiovascular Research Laboratory, and Brain Research Institute, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA 90095
| | - James N Weiss
- Division of Molecular Medicine, Department of Anesthesiology, Department of Medicine (Cardiology), Department of Physiology, Department of Integrative Biology and Physiology, Cardiovascular Research Laboratory, and Brain Research Institute, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA 90095 Division of Molecular Medicine, Department of Anesthesiology, Department of Medicine (Cardiology), Department of Physiology, Department of Integrative Biology and Physiology, Cardiovascular Research Laboratory, and Brain Research Institute, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA 90095 Division of Molecular Medicine, Department of Anesthesiology, Department of Medicine (Cardiology), Department of Physiology, Department of Integrative Biology and Physiology, Cardiovascular Research Laboratory, and Brain Research Institute, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA 90095
| | - Riccardo Olcese
- Division of Molecular Medicine, Department of Anesthesiology, Department of Medicine (Cardiology), Department of Physiology, Department of Integrative Biology and Physiology, Cardiovascular Research Laboratory, and Brain Research Institute, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA 90095 Division of Molecular Medicine, Department of Anesthesiology, Department of Medicine (Cardiology), Department of Physiology, Department of Integrative Biology and Physiology, Cardiovascular Research Laboratory, and Brain Research Institute, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA 90095 Division of Molecular Medicine, Department of Anesthesiology, Department of Medicine (Cardiology), Department of Physiology, Department of Integrative Biology and Physiology, Cardiovascular Research Laboratory, and Brain Research Institute, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA 90095 Division of Molecular Medicine, Department of Anesthesiology, Department of Medicine (Cardiology), Department of Physiology, Department of Integrative Biology and Physiology, Cardiovascular Research Laboratory, and Brain Research Institute, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA 90095
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Winter J, Shattock MJ. Geometrical considerations in cardiac electrophysiology and arrhythmogenesis. Europace 2015; 18:320-31. [PMID: 26585597 DOI: 10.1093/europace/euv307] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Accepted: 08/14/2015] [Indexed: 11/14/2022] Open
Abstract
The rate of repolarization (RRepol) and so the duration of the cardiac action potential are determined by the balance of inward and outward currents across the cardiac membrane (net ionic current). Plotting action potential duration (APD) as a function of the RRepol reveals an inverse non-linear relationship, arising from the geometric association between these two factors. From the RRepol-APD relationship, it can be observed that a longer action potential will exhibit a greater propensity to shorten, or prolong, for a given change in the RRepol (i.e. net ionic current), when compared with one that is initially shorter. This observation has recently been used to explain why so many interventions that prolong the action potential exert a greater effect at slow rates (reverse rate-dependence). In this article, we will discuss the broader implications of this simple principle and examine how common experimental observations on the electrical behaviour of the myocardium may be explained in terms of the RRepol-APD relationship. An argument is made, with supporting published evidence, that the non-linear relationship between the RRepol and APD is a fundamental, and largely overlooked, property of the myocardium. The RRepol-APD relationship appears to explain why interventions and disease with seemingly disparate mechanisms of action have similar electrophysiological consequences. Furthermore, the RRepol-APD relationship predicts that prolongation of the action potential, by slowing repolarization, will promote conditions of dynamic electrical instability, exacerbating several electrophysiological phenomena associated with arrhythmogenesis, namely, the rate dependence of dispersion of repolarization, APD restitution, and electrical alternans.
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Affiliation(s)
- James Winter
- Cardiovascular Division, The Rayne Institute, 4th Floor, Lambeth Wing, St Thomas' Hospital, King's College London, London SE1 7EH, UK
| | - Michael J Shattock
- Cardiovascular Division, The Rayne Institute, 4th Floor, Lambeth Wing, St Thomas' Hospital, King's College London, London SE1 7EH, UK
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Orphan nuclear receptor Nur77 affects cardiomyocyte calcium homeostasis and adverse cardiac remodelling. Sci Rep 2015; 5:15404. [PMID: 26486271 PMCID: PMC4613907 DOI: 10.1038/srep15404] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Accepted: 09/21/2015] [Indexed: 12/22/2022] Open
Abstract
Distinct stressors may induce heart failure. As compensation, β-adrenergic stimulation enhances myocardial contractility by elevating cardiomyocyte intracellular Ca2+ ([Ca2+]i). However, chronic β-adrenergic stimulation promotes adverse cardiac remodelling. Cardiac expression of nuclear receptor Nur77 is enhanced by β-adrenergic stimulation, but its role in cardiac remodelling is still unclear. We show high and rapid Nur77 upregulation in cardiomyocytes stimulated with β-adrenergic agonist isoproterenol. Nur77 knockdown in culture resulted in hypertrophic cardiomyocytes. Ventricular cardiomyocytes from Nur77-deficient (Nur77-KO) mice exhibited elevated diastolic and systolic [Ca2+]i and prolonged action potentials compared to wild type (WT). In vivo, these differences resulted in larger cardiomyocytes, increased expression of hypertrophic genes, and more cardiac fibrosis in Nur77-KO mice upon chronic isoproterenol stimulation. In line with the observed elevated [Ca2+]i, Ca2+-activated phosphatase calcineurin was more active in Nur77-KO mice compared to WT. In contrast, after cardiac pressure overload by aortic constriction, Nur77-KO mice exhibited attenuated remodelling compared to WT. Concluding, Nur77-deficiency results in significantly altered cardiac Ca2+ homeostasis and distinct remodelling outcome depending on the type of insult. Detailed knowledge on the role of Nur77 in maintaining cardiomyocyte Ca2+ homeostasis and the dual role Nur77 plays in cardiac remodelling will aid in developing personalized therapies against heart failure.
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Abstract
In the last decade, there have been considerable advances in the understanding of the pathophysiology of malignant ventricular tachyarrhythmias (VT) and sudden cardiac death (SCD). Over 80% of SCD occurs in patients with organic heart disease. However, approximately 10%-15% of SCD occurs in the presence of structurally normal heart, and the majority of these patients are young. In this group of patients, changes in genes encoding cardiac ion channels produce modifications of the function of the channel resulting in an electrophysiological substrate of VT and SCD. Collectively, these disorders are referred to as cardiac ion channelopathies. The four major syndromes in this group are: the long QT syndrome (LQTS), the Brugada syndrome (BrS), the short QT syndrome (SQTS), and the catecholaminergic polymorphic ventricular tachycardia (CPVT). Each of these syndromes includes multiple subtypes with different and sometimes complex cardiac ion channel genetic abnormalities. Many are associated with other somatic and neurological abnormalities besides the risk of VT and SCD. The current management of cardiac ion channelopathies can be summarized as follows: (1) in symptomatic patients, the implantable cardioverter defibrillator (ICD) is the only viable option; (2) in asymptomatic patients, risk stratification is necessary, followed by either the ICD, pharmacotherapy, or a combination of both. A genotype-specific approach to pharmacotherapy requires a thorough understanding of the molecular-cellular basis of arrhythmogenesis in cardiac ion channelopathies as well as the specific drug profile.
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Winter J, Lee AW, Niederer S, Shattock MJ. Vagal modulation of dispersion of repolarisation in the rabbit heart. J Mol Cell Cardiol 2015; 85:89-101. [DOI: 10.1016/j.yjmcc.2015.05.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Revised: 05/08/2015] [Accepted: 05/13/2015] [Indexed: 10/23/2022]
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Kim JJ, Němec J, Li Q, Salama G. Synchronous systolic subcellular Ca2+-elevations underlie ventricular arrhythmia in drug-induced long QT type 2. Circ Arrhythm Electrophysiol 2015; 8:703-12. [PMID: 25722252 PMCID: PMC4472565 DOI: 10.1161/circep.114.002214] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Accepted: 02/11/2015] [Indexed: 12/19/2022]
Abstract
BACKGROUND Repolarization delay is a common clinical problem, which can promote ventricular arrhythmias. In myocytes, abnormal sarcoplasmic reticulum Ca(2+)-release is proposed as the mechanism that causes early afterdepolarizations, the cellular equivalent of ectopic-activity in drug-induced long-QT syndrome. A crucial missing link is how such a stochastic process can overcome the source-sink mismatch to depolarize sufficient ventricular tissue to initiate arrhythmias. METHODS AND RESULTS Optical maps of action potentials and Ca(2+)-transients from Langendorff rabbit hearts were measured at low (150×150 μm(2)/pixel) and high (1.5×1.5 μm(2)/pixel) resolution before and during arrhythmias. Drug-induced long QT type 2, elicited with dofetilide inhibition of IKr (the rapid component of rectifying K+ current), produced spontaneous Ca(2+)-elevations during diastole and systole, before the onset of arrhythmias. Diastolic Ca(2+-)waves appeared randomly, propagated within individual myocytes, were out-of-phase with adjacent myocytes, and often died-out. Systolic secondary Ca(2+-)elevations were synchronous within individual myocytes, appeared 188±30 ms after the action potential-upstroke, occurred during high cytosolic Ca(2+) (40%-60% of peak-Ca(2+)-transients), appeared first in small islands (0.5×0.5 mm(2)) that enlarged and spread throughout the epicardium. Synchronous systolic Ca(2+-)elevations preceded voltage-depolarizations (9.2±5 ms; n=5) and produced pronounced Spatial Heterogeneities of Ca(2+)-transient-durations and action potential-durations. Early afterdepolarizations originating from sites with the steepest gradients of membrane-potential propagated and initiated arrhythmias. Interestingly, more complex subcellular Ca(2+)-dynamics (multiple chaotic Ca(2+)-waves) occurred during arrhythmias. K201, a ryanodine receptor stabilizer, eliminated Ca(2+)-elevations and arrhythmias. CONCLUSIONS The results indicate that systolic and diastolic Ca(2+)-elevations emanate from sarcoplasmic reticulum Ca(2+)-release and systolic Ca(2+)-elevations are synchronous because of high cytosolic and luminal-sarcoplasmic reticulum Ca(2+), which overcomes source-sink mismatch to trigger arrhythmias in intact hearts.
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Affiliation(s)
- Jong J Kim
- From the Department of Bioengineering (J.J.K., G.S.), and Department of Medicine, Heart and Vascular Institute (J.J.K., J.N., Q.L., G.S.), University of Pittsburgh, PA; and Tsinghua University School of Medicine, China (Q.L)
| | - Jan Němec
- From the Department of Bioengineering (J.J.K., G.S.), and Department of Medicine, Heart and Vascular Institute (J.J.K., J.N., Q.L., G.S.), University of Pittsburgh, PA; and Tsinghua University School of Medicine, China (Q.L)
| | - Qiao Li
- From the Department of Bioengineering (J.J.K., G.S.), and Department of Medicine, Heart and Vascular Institute (J.J.K., J.N., Q.L., G.S.), University of Pittsburgh, PA; and Tsinghua University School of Medicine, China (Q.L)
| | - Guy Salama
- From the Department of Bioengineering (J.J.K., G.S.), and Department of Medicine, Heart and Vascular Institute (J.J.K., J.N., Q.L., G.S.), University of Pittsburgh, PA; and Tsinghua University School of Medicine, China (Q.L).
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Shimizu W. Where does heterogeneity exist in ventricular tachyarrhythmias? Heart Rhythm 2015; 12:1304-5. [PMID: 25744614 DOI: 10.1016/j.hrthm.2015.02.034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Indexed: 11/19/2022]
Affiliation(s)
- Wataru Shimizu
- Department of Cardiovascular Medicine, Nippon Medical School, Tokyo, Japan.
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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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Vijayakumar R, Silva JNA, Desouza KA, Abraham RL, Strom M, Sacher F, Van Hare GF, Haïssaguerre M, Roden DM, Rudy Y. Electrophysiologic substrate in congenital Long QT syndrome: noninvasive mapping with electrocardiographic imaging (ECGI). Circulation 2014; 130:1936-1943. [PMID: 25294783 DOI: 10.1161/circulationaha.114.011359] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
BACKGROUND Congenital Long QT syndrome (LQTS) is an arrhythmogenic disorder that causes syncope and sudden death. Although its genetic basis has become well-understood, the mechanisms whereby mutations translate to arrhythmia susceptibility in the in situ human heart have not been fully defined. We used noninvasive ECG imaging to map the cardiac electrophysiological substrate and examine whether LQTS patients display regional heterogeneities in repolarization, a substrate that promotes arrhythmogenesis. METHODS AND RESULTS Twenty-five subjects (9 LQT1, 9 LQT2, 5 LQT3, and 2 LQT5) with genotype and phenotype positive LQTS underwent ECG imaging. Seven normal subjects provided control. Epicardial maps of activation, recovery times, activation-recovery intervals, and repolarization dispersion were constructed. Activation was normal in all patients. However, recovery times and activation-recovery intervals were prolonged relative to control, indicating delayed repolarization and abnormally long action potential duration (312±30 ms versus 235±21 ms in control). Activation-recovery interval prolongation was spatially heterogeneous, with repolarization gradients much steeper than control (119±19 ms/cm versus 2.0±2.0 ms/cm). There was variability in steepness and distribution of repolarization gradients between and within LQTS types. Repolarization gradients were steeper in symptomatic patients (130±27 ms/cm in 12 symptomatic patients versus 98±19 ms/cm in 13 asymptomatic patients; P<0.05). CONCLUSIONS LQTS patients display regions with steep repolarization dispersion caused by localized action potential duration prolongation. This defines a substrate for reentrant arrhythmias, not detectable by surface ECG. Steeper dispersion in symptomatic patients suggests a possible role for ECG imaging in risk stratification.
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Affiliation(s)
- Ramya Vijayakumar
- Cardiac Bioelectricity and Arrhythmia Center, Washington University in St. Louis, Saint Louis, MO.,Department of Biomedical Engineering, Washington University in St. Louis, Saint Louis, MO
| | - Jennifer N A Silva
- Cardiac Bioelectricity and Arrhythmia Center, Washington University in St. Louis, Saint Louis, MO.,Division of Pediatric Cardiology, Washington University School of Medicine/St. Louis Children's Hospital, St. Louis, MO
| | - Kavit A Desouza
- Cardiovascular diseases, Mount Sinai St. Luke's Roosevelt, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Robert L Abraham
- Department of Medicine and the Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN
| | | | - Frederic Sacher
- Bordeaux University Hospital, LIRYC institute, Pessac, France
| | - George F Van Hare
- Cardiac Bioelectricity and Arrhythmia Center, Washington University in St. Louis, Saint Louis, MO.,Division of Pediatric Cardiology, Washington University School of Medicine/St. Louis Children's Hospital, St. Louis, MO
| | | | - Dan M Roden
- Department of Medicine and the Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN
| | - Yoram Rudy
- Cardiac Bioelectricity and Arrhythmia Center, Washington University in St. Louis, Saint Louis, MO.,Department of Biomedical Engineering, Washington University in St. Louis, Saint Louis, MO.,Division of Pediatric Cardiology, Washington University School of Medicine/St. Louis Children's Hospital, St. Louis, MO.,Department of Medicine (Cardiology), Washington University School of Medicine/Barnes-Jewish Hospital, St. Louis, MO
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Analysis of Unipolar Electrograms in Rabbit Heart Demonstrated the Key Role of Ventricular Apicobasal Dispersion in Arrhythmogenicity. Cardiovasc Toxicol 2014; 14:316-28. [DOI: 10.1007/s12012-014-9254-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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36
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Chen YH, Pai CW, Huang SW, Chang SN, Lin LY, Chiang FT, Lin JL, Hwang JJ, Tsai CT. Inactivation of Myosin binding protein C homolog in zebrafish as a model for human cardiac hypertrophy and diastolic dysfunction. J Am Heart Assoc 2013; 2:e000231. [PMID: 24047589 PMCID: PMC3835223 DOI: 10.1161/jaha.113.000231] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Background Sudden cardiac death due to malignant ventricular arrhythmia is a devastating manifestation of cardiac hypertrophy. Sarcomere protein myosin binding protein C is functionally related to cardiac diastolic function and hypertrophy. Zebrafish is a better model to study human electrophysiology and arrhythmia than rodents because of the electrophysiological characteristics similar to those of humans. Methods and Results We established a zebrafish model of cardiac hypertrophy and diastolic dysfunction by genetic knockdown of myosin binding protein C gene (mybpc3) and investigated the electrophysiological phenotypes in this model. We found expression of zebrafish mybpc3 restrictively in the heart and slow muscle, and mybpc3 gene was evolutionally conservative with sequence homology between zebrafish and human mybpc3 genes. Zebrafish with genetic knockdown of mybpc3 by morpholino showed ventricular hypertrophy with increased myocardial wall thickness and diastolic heart failure, manifesting as decreased ventricular diastolic relaxation velocity, pericardial effusion, and dilatation of the atrium. In terms of electrophysiological phenotypes, mybpc3 knockdown fish had a longer ventricular action potential duration and slower ventricular diastolic calcium reuptake, both of which are typical electrophysiological features in human cardiac hypertrophy and heart failure. Impaired calcium reuptake resulted in increased susceptibility to calcium transient alternans and action potential duration alternans, which have been proved to be central to the genesis of malignant ventricular fibrillation and a sensitive marker of sudden cardiac death. Conclusions mybpc3 knockdown in zebrafish recapitulated the morphological, mechanical, and electrophysiological phenotypes of human cardiac hypertrophy and diastolic heart failure. Our study also first demonstrated arrhythmogenic cardiac alternans in cardiac hypertrophy.
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Affiliation(s)
- Yau-Hung Chen
- Department of Chemistry, Tamkang University, Taipei, Taiwan
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Mazeh N, Haines DE, Kay MW, Roth BJ. A Simplified Approach for Simultaneous Measurements of Wavefront Velocity and Curvature in the Heart Using Activation Times. Cardiovasc Eng Technol 2013; 4:520-534. [PMID: 24772193 DOI: 10.1007/s13239-013-0158-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The velocity and curvature of a wave front are important factors governing the propagation of electrical activity through cardiac tissue, particularly during heart arrhythmias of clinical importance such as fibrillation. Presently, no simple computational model exists to determine these values simultaneously. The proposed model uses the arrival times at four or five sites to determine the wave front speed (v), direction (θ), and radius of curvature (ROC) (r0). If the arrival times are measured, then v, θ, and r0 can be found from differences in arrival times and the distance between these sites. During isotropic conduction, we found good correlation between measured values of the ROC r0 and the distance from the unipolar stimulus (r = 0.9043 and p < 0.0001). The conduction velocity (m/s) was correlated (r = 0.998, p < 0.0001) using our method (mean = 0.2403, SD = 0.0533) and an empirical method (mean = 0.2352, SD = 0.0560). The model was applied to a condition of anisotropy and a complex case of reentry with a high voltage extra stimulus. Again, results show good correlation between our simplified approach and established methods for multiple wavefront morphologies. In conclusion, insignificant measurement errors were observed between this simplified approach and an approach that was more computationally demanding. Accuracy was maintained when the requirement that ε (ε = b/r0, ratio of recording site spacing over wave fronts ROC) was between 0.001 and 0.5. The present simplified model can be applied to a variety of clinical conditions to predict behavior of planar, elliptical, and reentrant wave fronts. It may be used to study the genesis and propagation of rotors in human arrhythmias and could lead to rotor mapping using low density endocardial recording electrodes.
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Affiliation(s)
- Nachaat Mazeh
- Department of Cardiovascular Medicine, Beaumont Health System, Royal Oak, MI, USA
| | - David E Haines
- Department of Cardiovascular Medicine, Oakland University William Beaumont School of Medicine, Royal Oak, MI, USA
| | - Matthew W Kay
- Department of Electrical and Computer Engineering, George Washington University, Washington, DC, USA
| | - Bradley J Roth
- Department of Physics, Oakland University, Rochester, MI, USA
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Han C, Pogwizd SM, Killingsworth CR, Zhou Z, He B. Noninvasive cardiac activation imaging of ventricular arrhythmias during drug-induced QT prolongation in the rabbit heart. Heart Rhythm 2013; 10:1509-15. [PMID: 23773986 DOI: 10.1016/j.hrthm.2013.06.010] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2012] [Indexed: 11/18/2022]
Abstract
BACKGROUND Imaging myocardial activation from noninvasive body surface potentials promises to aid in both cardiovascular research and clinical medicine. OBJECTIVE To investigate the ability of a noninvasive 3-dimensional cardiac electrical imaging technique for characterizing the activation patterns of dynamically changing ventricular arrhythmias during drug-induced QT prolongation in rabbits. METHODS Simultaneous body surface potential mapping and 3-dimensional intracardiac mapping were performed in a closed-chest condition in 8 rabbits. Data analysis was performed on premature ventricular complexes, couplets, and torsades de pointes (TdP) induced during intravenous administration of clofilium and phenylephrine with combinations of various infusion rates. RESULTS The drug infusion led to a significant increase in the QT interval (from 175 ± 7 to 274 ± 31 ms) and rate-corrected QT interval (from 183 ± 5 to 262 ± 21 ms) during the first dose cycle. All the ectopic beats initiated by a focal activation pattern. The initial beat of TdPs arose at the focal site, whereas the subsequent beats were due to focal activity from different sites or 2 competing focal sites. The imaged results captured the dynamic shift of activation patterns and were in good correlation with the simultaneous measurements, with a correlation coefficient of 0.65 ± 0.02 averaged over 111 ectopic beats. Sites of initial activation were localized to be ~5 mm from the directly measured initiation sites. CONCLUSIONS The 3-dimensional cardiac electrical imaging technique could localize the origin of activation and image activation sequence of TdP during QT prolongation induced by clofilium and phenylephrine in rabbits. It offers the potential to noninvasively investigate the proarrhythmic effects of drug infusion and assess the mechanisms of arrhythmias on a beat-to-beat basis.
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Affiliation(s)
- Chengzong Han
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota
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40
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Ventricular repolarization gradient and electrocardiogram characteristics of Tako-Tsubo cardiomyopathy. Heart Rhythm 2012; 10:78-9. [PMID: 22985661 DOI: 10.1016/j.hrthm.2012.09.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Indexed: 11/20/2022]
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de Lange E, Xie Y, Qu Z. Synchronization of early afterdepolarizations and arrhythmogenesis in heterogeneous cardiac tissue models. Biophys J 2012; 103:365-73. [PMID: 22853915 DOI: 10.1016/j.bpj.2012.06.007] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2012] [Revised: 06/05/2012] [Accepted: 06/07/2012] [Indexed: 02/05/2023] Open
Abstract
Early afterdepolarizations (EADs) are linked to both triggered arrhythmias and reentrant arrhythmias by causing premature ventricular complexes (PVCs), focal excitations, or heterogeneous tissue substrates for reentry formation. However, a critical number of cells that synchronously exhibit EADs are needed to result in arrhythmia triggers and substrates in tissue. In this study, we use mathematical modeling and computer simulations to investigate EAD synchronization and arrhythmia induction in tissue models with random cell-to-cell variations. Our major observations are as follows. Random cell-to-cell variations in action potential duration without EAD presence do not cause large dispersion of refractoriness in well-coupled tissue. In the presence of phase-2 EADs, the cells may synchronously exhibit the same number of EADs or no EADs with a very small dispersion of refractoriness, or synchronize regionally to result in large dispersion of refractoriness. In the presence of phase-3 EADs, regional synchronization leads to propagating EADs, forming PVCs in tissue. Interestingly, even though the uncoupled cells exhibit either no EAD or only a single EAD, when these cells are coupled to form a tissue, more than one PVC can occur. When the PVCs occur at different locations and time, multifocal arrhythmias are triggered, with the foci shifting in space and time in an irregular manner. The focal arrhythmias either spontaneously terminate or degenerate into reentrant arrhythmias due to heterogeneities and spatiotemporal chaotic dynamics of the foci.
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Affiliation(s)
- Enno de Lange
- Cardiovascular Research Laboratory, Department of Medicine (Cardiology), David Geffen School of Medicine, University of California, Los Angeles, California, USA.
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Izumi D, Chinushi M, Iijima K, Furushima H, Hosaka Y, Hasegawa K, Aizawa Y. The peak-to-end of the T wave in the limb ECG leads reflects total spatial rather than transmural dispersion of ventricular repolarization in an anthopleurin-A model of prolonged QT interval. Heart Rhythm 2012; 9:796-803. [DOI: 10.1016/j.hrthm.2011.11.046] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2011] [Indexed: 11/29/2022]
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Janse MJ, Coronel R, Opthof T, Sosunov EA, Anyukhovsky EP, Rosen MR. Repolarization gradients in the intact heart: transmural or apico-basal? PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2012; 109:6-15. [PMID: 22446189 DOI: 10.1016/j.pbiomolbio.2012.03.001] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Revised: 02/17/2012] [Accepted: 03/06/2012] [Indexed: 01/31/2023]
Abstract
Controversies regarding the genesis of the T wave in the electrocardiogram and the role of midmural M cells in the intact heart include: In normal, intact canine and human hearts there is no significant transmural gradient in repolarization times. The T wave results primarily from apico-basal differences in repolarization times. Also, in the intact heart there is no midmural region of prolonged action potential duration. This contrasts with isolated preparations, such as the wedge preparation or myocardial slices or disaggregated myocytes in which M cells, with action potentials longer than those of endocardial and epicardial myocardium, can be found. This disparity in action potential duration probably results from partial uncoupling of myocardial cells in the regions where measurements are made, e.g., the cut surface of a wedge preparation. In regions of a wedge where cellular coupling is normal, or in isolated myocardial bundles or sheets, no evidence for M cells is detected. In some wedge preparations, a drug-induced large transmural repolarization gradient, involving M cells, can lead to Torsade de Pointes, possibly caused by so-called phase two reentry. In contrast, when a gradient of repolarization times of more than 100 ms was created in intact hearts, no evidence for reentry was found and no spontaneous arrhythmias occurred. In conclusion, in the intact heart, M cells appear not to contribute to repolarization gradients and arrhythmias. Furthermore, no significant repolarization gradients between endocardium and epicardium exist. The T wave in the body surface electrocardiogram is caused by apico-basal and anterior-posterior differences in repolarization times.
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Affiliation(s)
- Michiel J Janse
- The Experimental Cardiology Group, Heart Centre, Academic Medical Centre, Amsterdam, The Netherlands
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Vaseghi M, Lux RL, Mahajan A, Shivkumar K. Sympathetic stimulation increases dispersion of repolarization in humans with myocardial infarction. Am J Physiol Heart Circ Physiol 2012; 302:H1838-46. [PMID: 22345568 DOI: 10.1152/ajpheart.01106.2011] [Citation(s) in RCA: 101] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The sympathetic nervous system is thought to play a key role in genesis and maintenance of ventricular arrhythmias. The myocardial effect of sympathetic stimulation on myocardial repolarization in humans is poorly understood. The purpose of this study was to evaluate the effects of direct and reflex sympathetic stimulation on ventricular repolarization in patients with postinfarct cardiomyopathy (ICM). The effects of direct sympathetic stimulation were assessed using isoproterenol, while those of reflex sympathetic stimulation were assessed with nitroprusside infusion in ICM patients (n = 5). Five patients without cardiomyopathy were also studied. Local repolarization was measured from intracardiac electrograms that were used to calculate the activation recovery interval (ARI), a surrogate of action potential duration. Isoproterenol significantly increased heterogeneity in repolarization in patients with ICM; the decrease in ARI from baseline was 72.9 ± 9.1 ms in more viable regions, 64.5 ± 8.9 ms in the scar, and 54.9 ± 9.1 ms in border zones (P = 0.0002 and 0.014 comparing normal and scar to border zones, respectively). In response to nitroprusside, the ARI at the border zones decreased significantly more than either scar or surrounding viable myocardium, which showed an increase in ARI (P = 0.014 and 0.08 comparing normal tissue and scar to border zones, respectively). Furthermore, isoproterenol increased ARI dispersion by 70%, while nitroprusside increased ARI dispersion by 230% when ICM patients were compared to those with structurally normal hearts (P = 0.0015 and P < 0.001, respectively). In humans, both direct and reflex sympathetic stimulations increase regional differences in repolarization. The normal tissue surrounding the scar appears denervated. Dispersion of ARI in response to sympathetic stimulation is significantly increased in patients with ICM.
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Affiliation(s)
- Marmar Vaseghi
- University of Califonia, Los Angeles, Cardiac Arrhythmia Center, Los Angeles, CA 90095-1679, USA
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Saucerman JJ. Cardiac biexcitability: Two ways to catch a wave. Heart Rhythm 2012; 9:123-4. [DOI: 10.1016/j.hrthm.2011.09.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2011] [Indexed: 11/25/2022]
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Affiliation(s)
- Stanley Nattel
- Department of Medicine and Research Center, Montreal Heart Institute and Université de Montréal, Montreal, Quebec, Canada
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Wilson LD, Jennings MM, Rosenbaum DS. Point: M cells are present in the ventricular myocardium. Heart Rhythm 2011; 8:930-3. [DOI: 10.1016/j.hrthm.2011.01.026] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2010] [Accepted: 01/11/2011] [Indexed: 10/18/2022]
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The contribution of ventricular apicobasal and transmural repolarization patterns to the development of the T wave body surface potentials in frogs (Rana temporaria) and pike (Esox lucius). Comp Biochem Physiol A Mol Integr Physiol 2011; 159:39-45. [DOI: 10.1016/j.cbpa.2011.01.016] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2010] [Revised: 01/14/2011] [Accepted: 01/17/2011] [Indexed: 11/16/2022]
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Tsvetkova AS, Kibler NA, Nuzhny VP, Shmakov DN, Azarov JE. Acute effects of pacing site on repolarization and haemodynamics of the canine ventricles. Europace 2011; 13:889-96. [PMID: 21421575 DOI: 10.1093/europace/eur053] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
AIMS To determine the repolarization duration gradients in different ventricular regions at atrial and ventricular pacing and to test the hypothesis that acute haemodynamic response to ventricular pacing is related to the lead position with respect to repolarization gradients. METHODS AND RESULTS Repolarization durations estimated as activation-recovery intervals (ARIs) were measured from unipolar electrograms recorded in the subepicardial (Epi), mid-myocardial (Mid), and subendocardial (Endo) layers of the apical and basal parts of the right ventricle (RV) and left ventricle (LV) of 15 healthy dogs under atrial and ventricular pacing. Cardiac haemodynamic variables were measured as well. At atrial pacing, ARIs were shorter in Epi than in the innermost layers (P< 0.05) in the RV apex and LV base, but not in the LV apex and RV base. Activation-recovery intervals increased from apex to base and from base to apex in RV and LV, respectively (P ≤ 0.05). At apical or basal pacing of RV and LV, repolarization gradients decayed. The dispersion of repolarization increased at LV apical pacing and preserved at RV apical pacing. The pump function of a ventricle was altered dramatically at pacing of the area with the shorter ARIs and to a lesser degree at pacing of the area with the longer ARIs (P ≤ 0.051). CONCLUSION The transmural and apicobasal differences in repolarization durations were heterogeneously distributed at atrial pacing. The acute haemodynamic response of the individual ventricle was better with pacing of the region with the longest repolarization suggesting a promising criterion for the lead position selection on the basis of ARIs measurements.
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Affiliation(s)
- Alena S Tsvetkova
- Laboratory of Cardiac Physiology, Institute of Physiology, Komi Science Center, Ural Division, Russian Academy of Sciences, 50 Pervomayskaya St., Syktyvkar, 167982 Russia
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Antzelevitch C, Dumaine R. Electrical Heterogeneity in the Heart: Physiological, Pharmacological and Clinical Implications. Compr Physiol 2011. [DOI: 10.1002/cphy.cp020117] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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