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Elfouly T, Alouani A. Harnessing the Heart's Magnetic Field for Advanced Diagnostic Techniques. SENSORS (BASEL, SWITZERLAND) 2024; 24:6017. [PMID: 39338762 PMCID: PMC11435997 DOI: 10.3390/s24186017] [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: 08/15/2024] [Revised: 09/05/2024] [Accepted: 09/14/2024] [Indexed: 09/30/2024]
Abstract
Heart diseases remain one of the leading causes of morbidity and mortality worldwide, necessitating innovative diagnostic methods for early detection and intervention. An electrocardiogram (ECG) is a well-known technique for the preliminary diagnosis of heart conditions. However, it can not be used for continuous monitoring due to skin irritation. It is well known that every body organ generates a magnetic field, and the heart generates peak amplitudes of about 10 to 100 pT (measured at a distance of about 3 cm above the chest). This poses challenges to capturing such signals. This paper reviews the different techniques used to capture the heart's magnetic signals along with their limitations. In addition, this paper provides a comprehensive review of the different approaches that use the heart-generated magnetic field to diagnose several heart diseases. This research reveals two aspects. First, as a noninvasive tool, the use of the heart's magnetic field signal can lead to more sensitive advanced heart disease diagnosis tools, especially when continuous monitoring is possible and affordable. Second, its current use is limited due to the lack of accurate, affordable, and portable sensing technology.
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Affiliation(s)
- Tarek Elfouly
- Department of Electrical and Computer Engineering, Tennessee Technological University, Cookeville, TN 38505, USA
| | - Ali Alouani
- Department of Electrical and Computer Engineering, Tennessee Technological University, Cookeville, TN 38505, USA
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Brisinda D, Fenici P, Fenici R. Clinical magnetocardiography: the unshielded bet-past, present, and future. Front Cardiovasc Med 2023; 10:1232882. [PMID: 37636301 PMCID: PMC10448194 DOI: 10.3389/fcvm.2023.1232882] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Accepted: 06/23/2023] [Indexed: 08/29/2023] Open
Abstract
Magnetocardiography (MCG), which is nowadays 60 years old, has not yet been fully accepted as a clinical tool. Nevertheless, a large body of research and several clinical trials have demonstrated its reliability in providing additional diagnostic electrophysiological information if compared with conventional non-invasive electrocardiographic methods. Since the beginning, one major objective difficulty has been the need to clean the weak cardiac magnetic signals from the much higher environmental noise, especially that of urban and hospital environments. The obvious solution to record the magnetocardiogram in highly performant magnetically shielded rooms has provided the ideal setup for decades of research demonstrating the diagnostic potential of this technology. However, only a few clinical institutions have had the resources to install and run routinely such highly expensive and technically demanding systems. Therefore, increasing attempts have been made to develop cheaper alternatives to improve the magnetic signal-to-noise ratio allowing MCG in unshielded hospital environments. In this article, the most relevant milestones in the MCG's journey are reviewed, addressing the possible reasons beyond the currently long-lasting difficulty to reach a clinical breakthrough and leveraging the authors' personal experience since the early 1980s attempting to finally bring MCG to the patient's bedside for many years thus far. Their nearly four decades of foundational experimental and clinical research between shielded and unshielded solutions are summarized and referenced, following the original vision that MCG had to be intended as an unrivaled method for contactless assessment of the cardiac electrophysiology and as an advanced method for non-invasive electroanatomical imaging, through multimodal integration with other non-fluoroscopic imaging techniques. Whereas all the above accounts for the past, with the available innovative sensors and more affordable active shielding technologies, the present demonstrates that several novel systems have been developed and tested in multicenter clinical trials adopting both shielded and unshielded MCG built-in hospital environments. The future of MCG will mostly be dependent on the results from the ongoing progress in novel sensor technology, which is relatively soon foreseen to provide multiple alternatives for the construction of more compact, affordable, portable, and even wearable devices for unshielded MCG inside hospital environments and perhaps also for ambulatory patients.
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Affiliation(s)
- D. Brisinda
- Dipartimento Scienze dell'invecchiamento, ortopediche e reumatologiche, Fondazione Policlinico Universitario Agostino Gemelli, IRCCS, Rome, Italy
- School of Medicine and Surgery, Catholic University of the Sacred Heart, Rome, Italy
- Biomagnetism and Clinical Physiology International Center (BACPIC), Rome, Italy
| | - P. Fenici
- School of Medicine and Surgery, Catholic University of the Sacred Heart, Rome, Italy
- Biomagnetism and Clinical Physiology International Center (BACPIC), Rome, Italy
| | - R. Fenici
- Biomagnetism and Clinical Physiology International Center (BACPIC), Rome, Italy
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Goldenthal IL, Ciaccio EJ, Sciacca RR, Garan H, Biviano AB. Increased body mass index, age, and left atrial size are associated with altered intracardiac atrial electrograms in persistent atrial fibrillation patients. J Interv Card Electrophysiol 2021; 62:569-577. [PMID: 33432475 DOI: 10.1007/s10840-020-00933-5] [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: 04/15/2020] [Accepted: 12/27/2020] [Indexed: 11/26/2022]
Abstract
BACKGROUND There are limited studies evaluating whether atrial fibrillation (AF) patients with increased BMI, age, and left atrial (LA) size have altered intracardiac electrogram (EGM) morphology. METHODS We analyzed left atrial intracardiac EGMs acquired during invasive electrophysiology study in 54 patients with AF. EGM correlations were assessed among AF risk factors including age, left atrial size, and BMI. RESULTS BMI correlated positively with DF (r2 = 0.17, p = 0.009) and MP (r2 = 0.16, p = 0.01) with dominant frequency (DF) and mean spectral profile (MP) greater among obese individuals. Age was negatively associated with mean amplitude (r2 = 0.42, p < 0.001) and width (r2 = 0.32, p < 0.001); age was positively correlated with MP (r2 = 0.24, p < 0.001). LA size was negatively correlated with mean amplitude (r2 = 0.18, p = 0.03) and width (r2 = 0.23, p = 0.01); LA size was positively correlated with DF (r2 = 0.22, p = 0.01) and MP (r2 = 0.23, p = 0.01). Mean amplitude and width were decreased among subjects with a severely enlarged LA; DF and MP were increased in those with severely enlarged LA. The associations with BMI and LA size remained significant in multiple regression models that included age, male gender, time since AF diagnosis, and LVEF. CONCLUSIONS EGM morphology of AF patients with increased BMI, older age, and an enlarged LA possessed decreased amplitude and decreased width and increased DF and MP. These findings suggest that atrial remodeling due to increased age, LA size, and BMI is associated with differences in local atrial activation, decreased refractoriness, and more heterogeneous activation. These novel findings point out clinical risk factors for atrial fibrillation that may affect electrogram characteristics.
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Affiliation(s)
- Isaac L Goldenthal
- Internal Medicine, Division of Cardiology, Columbia University Irving Medical Center, 622 W 168th St, New York, NY, 10032, USA
| | - Edward J Ciaccio
- Internal Medicine, Division of Cardiology, Columbia University Irving Medical Center, 622 W 168th St, New York, NY, 10032, USA
| | - Robert R Sciacca
- Internal Medicine, Division of Cardiology, Columbia University Irving Medical Center, 622 W 168th St, New York, NY, 10032, USA
| | - Hasan Garan
- Internal Medicine, Division of Cardiology, Columbia University Irving Medical Center, 622 W 168th St, New York, NY, 10032, USA
| | - Angelo B Biviano
- Internal Medicine, Division of Cardiology, Columbia University Irving Medical Center, 622 W 168th St, New York, NY, 10032, USA.
- Columbia University Irving Medical Center, 161 Fort Washington Ave #546, New York, NY, 10032, USA.
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Her AY, Shin ES, Zhou Q, Wierzbinski J, Vidal-Lopez S, Saleh A, Kim YH, Garg S, Jung F, Brachmann J. Magnetocardiography detects left atrial dysfunction in paroxysmal atrial fibrillation. Clin Hemorheol Microcirc 2019; 72:353-363. [PMID: 30958336 DOI: 10.3233/ch-180528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Magnetocardiography (MCG) is a non-invasive technique and to characterize the magnetic field, a pseudo-current conversion was used. The role of MCG in detecting left atrial (LA) dysfunction in patients with paroxysmal atrial fibrillation (PAF) is unknown. OBJECTIVE The aim of this study was to evaluate LA function using MCG in patients with PAF and healthy subjects, to identify possible indices to diagnose PAF. METHODS We enrolled a total of 70 subjects including 26 healthy volunteers (group 1) and 22 marathon runners (group 2) who did not exhibit any cardiac abnormalities, and 22 patients with PAF (group 3) which was documented by electrocardiography (ECG). Spatiotemporal activation graph (STAG) in base-apex and left-right direction was reconstructed. The maximum value of LA pseudo-current under rest and peak exercise were measured between the end of the P wave and beginning of the Q wave. RESULTS LA pseudo-current increase at peak exercise in PAF patients was significantly lower than in healthy volunteers and marathon runners (0.4±0.3 pT in group 3 vs. 0.8±0.3 pT in group 1 vs. 1.1±0.5 pT in group 2, p < 0.001). PAF patients had less pseudo-current increase in STAG at peak exercise than healthy volunteers and marathon runners (46% of 26 PAF patients, 81% of 22 healthy subjects vs. 81% of 22 marathon runners, p = 0.002). Sensitivity, specificity, and the area under the receiver-operator characteristics curve of LA pseudo-current increase at peak exercise for differentiating PAF patients from healthy subjects were 77%, 92%, and 0.896. CONCLUSIONS MCG can provide important non-invasive information for detecting LA dysfunction in PAF patients. Therefore, MCG may help in differentiating PAF patients from healthy subjects.
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Affiliation(s)
- Ae-Young Her
- Department of Internal Medicine, Division of Cardiology, Kangwon National University School of Medicine, Chuncheon, South Korea
| | - Eun-Seok Shin
- Division of Cardiology, Ulsan Medical Center, Ulsan Hospital, Ulsan, South Korea
| | - Qing Zhou
- Department of Medical II., Coburg Hospital, Coburg, Germany
| | - Jan Wierzbinski
- Department of Cardiology, Asklepios Hospital Harburg, Hamburg, Germany
| | | | - Ahmed Saleh
- Department of Medical II., Coburg Hospital, Coburg, Germany
| | - Yong Hoon Kim
- Department of Internal Medicine, Division of Cardiology, Kangwon National University School of Medicine, Chuncheon, South Korea
| | - Scot Garg
- East Lancashire Hospitals NHS Trust, Blackburn, Lancashire, UK
| | - Friedrich Jung
- Institute for Clinical Hemostasiology and Transfusion Medicine, University of Saarland, Saarbrücken, Germany
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Oladapo BI, Zahedi SA, Chaluvadi SC, Bollapalli SS, Ismail M. Model design of a superconducting quantum interference device of magnetic field sensors for magnetocardiography. Biomed Signal Process Control 2018. [DOI: 10.1016/j.bspc.2018.07.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Guida G, Sorbo AR, Fenici R, Brisinda D. Predictive value of unshielded magnetocardiographic mapping to differentiate atrial fibrillation patients from healthy subjects. Ann Noninvasive Electrocardiol 2018; 23:e12569. [PMID: 29947446 DOI: 10.1111/anec.12569] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Revised: 05/07/2018] [Accepted: 05/23/2018] [Indexed: 01/24/2023] Open
Abstract
BACKGROUND P-wave duration, its dispersion and signal-averaged ECG, are currently used markers of vulnerability to atrial fibrillation (AF). However, since tangential atrial currents are better detectable at the body surface as magnetic than electric signals, we investigated the accuracy of magnetocardiographic mapping (MCG), recorded in unshielded clinical environments, as predictor of AF occurrence. METHODS MCG recordings, in sinus rhythm (SR), of 71 AF patients and 75 controls were retrospectively analyzed. Beside electric and magnetic P-wave and PR interval duration, two MCG P-wave subintervals, defined P-dep and P-rep, were measured, basing on the point of inversion of atrial magnetic field (MF). Eight parameters were calculated from inverse solution with "Effective Magnetic Dipole (EMD) model" and 5 from "MF Extrema" analysis. Discriminant analysis (DA) was used to assess MCG predictive accuracy to differentiate AF patients from controls. RESULTS All but one (P-rep) intervals were significantly longer in AF patients. At univariate analysis, three EMD parameters differed significantly: in AF patients, the dipole-angle-elevation angular speed was lower during P-dep (p < 0.05) and higher during P-rep (p < 0.001) intervals. The space-trajectory during P-rep and the angle-dynamics during P-dep were higher (p < 0.05), whereas ratio-dynamics P-dep was lower (p < 0.01), in AF. At DA, with a combination of MCG and clinical parameters, 81.5% accuracy in differentiating AF patients from controls was achieved. At Cox-regression, the angle-dynamics P-dep was an independent predictor of AF recurrences (p = 0.037). CONCLUSIONS Quantitative analysis of atrial MF dynamics in SR and the solution of the inverse problem provide new sensitive markers of vulnerability to AF.
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Affiliation(s)
- Gianluigi Guida
- Biomagnetism and Clinical Physiology International Center, Catholic University of Sacred Heart, Rome, Italy
| | - Anna Rita Sorbo
- Biomagnetism and Clinical Physiology International Center, Catholic University of Sacred Heart, Rome, Italy
| | - Riccardo Fenici
- Biomagnetism and Clinical Physiology International Center, Catholic University of Sacred Heart, Rome, Italy
| | - Donatella Brisinda
- Biomagnetism and Clinical Physiology International Center, Catholic University of Sacred Heart, Rome, Italy
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Mäntynen V, Lehto M, Parikka H, Montonen J. Noninvasive mapping reveals recurrent and suddenly changing patterns in atrial fibrillation-a magnetocardiographic study. Physiol Meas 2018; 39:025006. [PMID: 29271352 DOI: 10.1088/1361-6579/aaa3bb] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE To study noninvasive magnetocardiographic (MCG) mapping of ongoing atrial fibrillation (AF) and, for the possible mapping patterns observed, to develop simplified but meaningful descriptors or parameters, providing a possible basis for future research and clinical use of the mappings. APPROACH MCG mapping with simultaneous ECG was recorded during arrhythmia in patients representing a range of typical, clinically classical atrial arrhythmias. The recordings were assessed using MCG map animations, and a method to compute magnetic field map orientation (MFO) and its time course was created to facilitate presentation of the findings. All the data were segmented into four categories of ECG waveform regularity. MAIN RESULTS In visual observation of the MCG animations, an abundance of clear spatial and temporal patterns with regularity were found, often perceived as rotations of the map. This rotation and its sudden reversals of direction were distinctly present in the time course of the MFO. The shortest segments with consistent rotation lasted for some hundreds of milliseconds, i.e. a couple of cycles, but segments lasting for tens of seconds were observed as well. In the ECG, all four categories of regularity were present. The rotation of the MFO was observed in all patients under study and regardless of the ECG categories. Further, a change in ECG category during a measurement was frequently, but not always, found to be simultaneous with a change in the rotation pattern of the MFO. Utilization of spatial information of MCG mapping could enable detection of both regularities and instantaneous phenomena during AF. SIGNIFICANCE Cardiac mapping may offer a useful noninvasive means to study the mechanisms of AF, including superior temporal resolution.
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Affiliation(s)
- Ville Mäntynen
- BioMag Laboratory, HUS Medical Imaging Center, University of Helsinki and Helsinki University Hospital, PO Box 340, FI-00029 HUS, Finland. Department of Neuroscience and Biomedical Engineering, Aalto University, Espoo, Finland, PO Box 12200, FI-00076 AALTO, Finland
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Patel R, Sengottuvel S, Gireesan K, Janawadkar MP, Radhakrishnan TS. Designing a Low-Cost, Single-Supply ECG System for Suppression of Movement Artifact from Contaminated Magnetocardiogram. SLAS Technol 2018; 23:463-469. [PMID: 29447023 DOI: 10.1177/2472630318759063] [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] [Indexed: 11/16/2022]
Abstract
Measurement of the late potentials and His-bundle activity is crucial for many clinical studies using the noncontact and noninvasive magnetocardiography (MCG) technique; these weak signals are extracted by averaging many cardiac cycles aligned using the R-peak of the cardiac cycle identified using an electrocardiography (ECG) lead. ECG is measured simultaneously with MCG using a conventional dual-supply ECG amplifier, which requires either two separate batteries or a single battery with a switching voltage inverter circuit for its proper operation. The ECG circuitry based on two separate batteries requires a relatively large voltage supply (-18 to +18 V). The single-supply (low voltage: 0-9 V) ECG circuitry may be implemented using a switching voltage inverter; however, this mode of operation introduces switching noise in the system. The objective of the present work is to overcome these problems by carefully designing a low-voltage, single-supply ECG system, which can be used simultaneously with the MCG setup without introducing a significant level of additional noise in the MCG measurement system.
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Affiliation(s)
- Rajesh Patel
- 1 SQUIDs and Applications Section, Condensed Matter Physics Division, Materials Science Group, Indira Gandhi Centre for Atomic Research, HBNI, Kalpakkam, India
| | - S Sengottuvel
- 1 SQUIDs and Applications Section, Condensed Matter Physics Division, Materials Science Group, Indira Gandhi Centre for Atomic Research, HBNI, Kalpakkam, India
| | - K Gireesan
- 1 SQUIDs and Applications Section, Condensed Matter Physics Division, Materials Science Group, Indira Gandhi Centre for Atomic Research, HBNI, Kalpakkam, India
| | - M P Janawadkar
- 1 SQUIDs and Applications Section, Condensed Matter Physics Division, Materials Science Group, Indira Gandhi Centre for Atomic Research, HBNI, Kalpakkam, India
| | - T S Radhakrishnan
- 1 SQUIDs and Applications Section, Condensed Matter Physics Division, Materials Science Group, Indira Gandhi Centre for Atomic Research, HBNI, Kalpakkam, India
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Gusev NA, Vetoshko PM, Kuzmichev AN, Chepurnova DA, Samoilova EV, Zvezdin AK, Korotaeva AA, Belotelov VI. Ultra-Sensitive Vector Magnetometer for Magnetocardiographic Mapping. BIOMEDICAL ENGINEERING-MEDITSINSKAYA TEKNIKA 2017. [DOI: 10.1007/s10527-017-9705-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Tse G, Chan YWF, Keung W, Yan BP. Electrophysiological mechanisms of long and short QT syndromes. IJC HEART & VASCULATURE 2017; 14:8-13. [PMID: 28382321 PMCID: PMC5368285 DOI: 10.1016/j.ijcha.2016.11.006] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Accepted: 11/19/2016] [Indexed: 12/21/2022]
Abstract
The QT interval on the human electrocardiogram is normally in the order of 450 ms, and reflects the summated durations of action potential (AP) depolarization and repolarization of ventricular myocytes. Both prolongation and shortening in the QT interval have been associated with ventricular tachy-arrhythmias, which predispose affected individuals to sudden cardiac death. In this article, the molecular determinants of the AP duration and the causes of long and short QT syndromes (LQTS and SQTS) are explored. This is followed by a review of the recent advances on their arrhythmogenic mechanisms involving reentry and/or triggered activity based on experiments conducted in mouse models. Established and novel clinical risk markers based on the QT interval for the prediction of arrhythmic risk and cardiovascular mortality are presented here. It is concluded by a discussion on strategies for the future rational design of anti-arrhythmic agents.
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Affiliation(s)
- Gary Tse
- Department of Medicine and Therapeutics, Chinese University of Hong Kong, Hong Kong, SAR, PR China
| | - Yin Wah Fiona Chan
- Department of Psychology, School of Biological Sciences, University of Cambridge, Cambridge, United Kingdom
| | - Wendy Keung
- Stem Cell & Regenerative Medicine Consortium, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong, SAR, PR China
| | - Bryan P Yan
- Department of Medicine and Therapeutics, Chinese University of Hong Kong, Hong Kong, SAR, PR China
- Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, VIC, Australia
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Tse G, Yan BP, Chan YWF, Tian XY, Huang Y. Reactive Oxygen Species, Endoplasmic Reticulum Stress and Mitochondrial Dysfunction: The Link with Cardiac Arrhythmogenesis. Front Physiol 2016; 7:313. [PMID: 27536244 PMCID: PMC4971160 DOI: 10.3389/fphys.2016.00313] [Citation(s) in RCA: 108] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Accepted: 07/11/2016] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND Cardiac arrhythmias represent a significant problem globally, leading to cerebrovascular accidents, myocardial infarction, and sudden cardiac death. There is increasing evidence to suggest that increased oxidative stress from reactive oxygen species (ROS), which is elevated in conditions such as diabetes and hypertension, can lead to arrhythmogenesis. METHOD A literature review was undertaken to screen for articles that investigated the effects of ROS on cardiac ion channel function, remodeling and arrhythmogenesis. RESULTS Prolonged endoplasmic reticulum stress is observed in heart failure, leading to increased production of ROS. Mitochondrial ROS, which is elevated in diabetes and hypertension, can stimulate its own production in a positive feedback loop, termed ROS-induced ROS release. Together with activation of mitochondrial inner membrane anion channels, it leads to mitochondrial depolarization. Abnormal function of these organelles can then activate downstream signaling pathways, ultimately culminating in altered function or expression of cardiac ion channels responsible for generating the cardiac action potential (AP). Vascular and cardiac endothelial cells become dysfunctional, leading to altered paracrine signaling to influence the electrophysiology of adjacent cardiomyocytes. All of these changes can in turn produce abnormalities in AP repolarization or conduction, thereby increasing likelihood of triggered activity and reentry. CONCLUSION ROS plays a significant role in producing arrhythmic substrate. Therapeutic strategies targeting upstream events include production of a strong reducing environment or the use of pharmacological agents that target organelle-specific proteins and ion channels. These may relieve oxidative stress and in turn prevent arrhythmic complications in patients with diabetes, hypertension, and heart failure.
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Affiliation(s)
- Gary Tse
- Li Ka Shing Faculty of Medicine, School of Biomedical Sciences, University of Hong KongHong Kong, China
- Department of Medicine and Therapeutics, Faculty of Medicine, Chinese University of Hong KongHong Kong, China
| | - Bryan P. Yan
- Department of Medicine and Therapeutics, Faculty of Medicine, Chinese University of Hong KongHong Kong, China
- Department of Epidemiology and Preventive Medicine, Monash UniversityMelbourne, VIC, Australia
| | - Yin W. F. Chan
- Department of Psychology, School of Biological Sciences, University of CambridgeCambridge, UK
| | - Xiao Yu Tian
- Faculty of Medicine, School of Biomedical Sciences, Chinese University of Hong KongHong Kong, China
| | - Yu Huang
- Faculty of Medicine, School of Biomedical Sciences, Chinese University of Hong KongHong Kong, China
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Tse G, Sun B, Wong ST, Tse V, Yeo JM. Anti-arrhythmic effects of hypercalcemia in hyperkalemic, Langendorff-perfused mouse hearts. Biomed Rep 2016; 5:301-310. [PMID: 27588173 PMCID: PMC4998139 DOI: 10.3892/br.2016.735] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Accepted: 05/31/2016] [Indexed: 12/25/2022] Open
Abstract
The present study examined the ventricular arrhythmic and electrophysiological properties during hyperkalemia (6.3 mM [K+] vs. 4 mM in normokalemia) and anti-arrhythmic effects of hypercalcemia (2.2 mM [Ca2+]) in Langendorff-perfused mouse hearts. Monophasic action potential recordings were obtained from the left ventricle during right ventricular pacing. Hyperkalemia increased the proportion of hearts showing provoked ventricular tachycardia (VT) from 0 to 6 of 7 hearts during programmed electrical stimulation (Fisher's exact test, P<0.05). It shortened the epicardial action potential durations (APDx) at 90, 70, 50 and 30% repolarization and ventricular effective refractory periods (VERPs) (analysis of variance, P<0.05) without altering activation latencies. Endocardial APDx and VERPs were unaltered. Consequently, ∆APDx (endocardial APDx-epicardial APDx) was increased, VERP/latency ratio was decreased and critical intervals for reexcitation (APD90-VERP) were unchanged. Hypercalcemia treatment exerted anti-arrhythmic effects during hyperkalemia, reducing the proportion of hearts showing VT to 1 of 7 hearts. It increased epicardial VERPs without further altering the remaining parameters, returning VERP/latency ratio to normokalemic values and also decreased the critical intervals. In conclusion, hyperkalemia exerted pro-arrhythmic effects by shortening APDs and VERPs. Hypercalcemia exerted anti-arrhythmic effects by reversing VERP changes, which scaled the VERP/latency ratio and critical intervals.
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Affiliation(s)
- Gary Tse
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong, SAR, P.R. China
| | - Bing Sun
- Department of Cardiology, Tongji University Affiliated Tongji Hospital, Shanghai 200065, P.R. China
| | | | - Vivian Tse
- Department of Physiology, McGill University, Montreal, Quebec H3G 1Y6, Canada
| | - Jie Ming Yeo
- School of Medicine, Imperial College London, London SW7 2AZ, UK
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Tse G, Lai ETH, Yeo JM, Tse V, Wong SH. Mechanisms of Electrical Activation and Conduction in the Gastrointestinal System: Lessons from Cardiac Electrophysiology. Front Physiol 2016; 7:182. [PMID: 27303305 PMCID: PMC4885840 DOI: 10.3389/fphys.2016.00182] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Accepted: 05/06/2016] [Indexed: 12/12/2022] Open
Abstract
The gastrointestinal (GI) tract is an electrically excitable organ system containing multiple cell types, which coordinate electrical activity propagating through this tract. Disruption in its normal electrophysiology is observed in a number of GI motility disorders. However, this is not well characterized and the field of GI electrophysiology is much less developed compared to the cardiac field. The aim of this article is to use the established knowledge of cardiac electrophysiology to shed light on the mechanisms of electrical activation and propagation along the GI tract, and how abnormalities in these processes lead to motility disorders and suggest better treatment options based on this improved understanding. In the first part of the article, the ionic contributions to the generation of GI slow wave and the cardiac action potential (AP) are reviewed. Propagation of these electrical signals can be described by the core conductor theory in both systems. However, specifically for the GI tract, the following unique properties are observed: changes in slow wave frequency along its length, periods of quiescence, synchronization in short distances and desynchronization over long distances. These are best described by a coupled oscillator theory. Other differences include the diminished role of gap junctions in mediating this conduction in the GI tract compared to the heart. The electrophysiology of conditions such as gastroesophageal reflux disease and gastroparesis, and functional problems such as irritable bowel syndrome are discussed in detail, with reference to ion channel abnormalities and potential therapeutic targets. A deeper understanding of the molecular basis and physiological mechanisms underlying GI motility disorders will enable the development of better diagnostic and therapeutic tools and the advancement of this field.
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Affiliation(s)
- Gary Tse
- Li Ka Shing Faculty of Medicine, School of Biomedical Sciences, University of Hong KongHong Kong, China
| | - Eric Tsz Him Lai
- Li Ka Shing Faculty of Medicine, School of Biomedical Sciences, University of Hong KongHong Kong, China
| | - Jie Ming Yeo
- School of Medicine, Imperial College LondonLondon, UK
| | - Vivian Tse
- Department of Physiology, McGill UniversityMontreal, QC, Canada
| | - Sunny Hei Wong
- Department of Medicine and Therapeutics, Institute of Digestive Disease, LKS Institute of Health Sciences, Chinese University of Hong KongHong Kong, China
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Tse G, Lai ETH, Yeo JM, Yan BP. Electrophysiological Mechanisms of Bayés Syndrome: Insights from Clinical and Mouse Studies. Front Physiol 2016; 7:188. [PMID: 27303306 PMCID: PMC4886053 DOI: 10.3389/fphys.2016.00188] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 05/10/2016] [Indexed: 12/11/2022] Open
Abstract
Bayés syndrome is an under-recognized clinical condition characterized by inter-atrial block (IAB). This is defined electrocardiographically as P-wave duration > 120 ms and can be categorized into first, second and third degree IAB. It can be caused by inflammatory conditions such as systemic sclerosis and rheumatoid arthritis, abnormal protein deposition in cardiac amyloidosis, or neoplastic processes invading the inter-atrial conduction system, such as primary cardiac lymphoma. It may arise transiently during volume overload, autonomic dysfunction or electrolyte disturbances from vomiting. In other patients without an obvious cause, the predisposing factors are diabetes mellitus, hypertensive heart disease, and hypercholesterolemia. IAB has a strong association with atrial arrhythmogenesis, left atrial enlargement (LAE), and electro-mechanical discordance, increasing the risk of cerebrovascular accidents as well as myocardial and mesenteric ischemia. The aim of this review article is to synthesize experimental evidence on the pathogenesis of IAB and its underlying molecular mechanisms. Current medical therapies include anti-fibrotic, anti-arrhythmic and anti-coagulation agents, whereas interventional options include atrial resynchronization therapy by single or multisite pacing. Future studies will be needed to elucidate the significance of the link between IAB and atrial tachyarrhythmias in patients with different underlying etiologies and optimize the management options in these populations.
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Affiliation(s)
- Gary Tse
- Li Ka Shing Faculty of Medicine, School of Biomedical Sciences, University of Hong KongHong Kong, China
| | - Eric Tsz Him Lai
- Li Ka Shing Faculty of Medicine, School of Biomedical Sciences, University of Hong KongHong Kong, China
| | - Jie Ming Yeo
- School of Medicine, Imperial College LondonLondon, UK
| | - Bryan P. Yan
- Department of Medicine and Therapeutics, The Chinese University of Hong KongHong Kong, China
- Department of Epidemiology and Preventive Medicine, Monash UniversityMelbourne, VIC, Australia
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