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Abstract
INTRODUCTION Brugada syndrome (BrS) is an inherited cardiac arrhythmia syndrome characterized by ST-segment elevation in right precordial ECG leads and associated with sudden cardiac death in young adults. The ECG manifestations of BrS are often concealed but can be unmasked by sodium channel blockers and fever. Areas covered: Implantation of a cardioverter defibrillator (ICD) is first-line therapy for BrS patients presenting with prior cardiac arrest or documented VT. A pharmacological approach to therapy is recommended in cases of electrical storm, as an adjunct to ICD and as preventative therapy. The goal of pharmacological therapy is to produce an inward shift to counter the genetically-induced outward shift of ion channel current flowing during the early phases of the ventricular epicardial action potential. This is accomplished by augmentation of ICa using □□adrenergic agents or phosphodiesterase III inhibitors or via inhibition of Ito. Radiofrequency ablation of the right ventricular outward flow tract epicardium is effective in suppressing arrhythmogenesis in BrS patients experiencing frequent appropriate ICD-shocks. Expert commentary: Understanding of the pathophysiology and approach to therapy of BrS has advanced considerably in recent years, but there remains an urgent need for development of cardio-selective and ion-channel-specific Ito blockers for treatment of BrS.
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Affiliation(s)
- Mariana Argenziano
- a Cardiovascular Research , Lankenau Institute for Medical Research , Wynnewood , PA , USA
| | - Charles Antzelevitch
- a Cardiovascular Research , Lankenau Institute for Medical Research , Wynnewood , PA , USA.,b Cardiovascular Research , Lankenau Heart Institute , Wynnewood , PA , USA.,c Department of Medicine and Pharmacology and Experimental Therapeutics , Sidney Kimmel Medical College of Thomas Jefferson University , Philadelphia , PA , USA
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Christov I, Neycheva T, Schmid R, Stoyanov T, Abächerli R. Pseudo-real-time low-pass filter in ECG, self-adjustable to the frequency spectra of the waves. Med Biol Eng Comput 2017; 55:1579-1588. [PMID: 28161875 DOI: 10.1007/s11517-017-1625-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Accepted: 01/25/2017] [Indexed: 11/29/2022]
Affiliation(s)
- Ivaylo Christov
- Institute of Biophysics and Biomedical Engineering, Bulgraian Academy of Sciences, Sofia, Bulgaria.
| | - Tatyana Neycheva
- Institute of Biophysics and Biomedical Engineering, Bulgraian Academy of Sciences, Sofia, Bulgaria
| | - Ramun Schmid
- Biomed Research and Signal Processing, Schiller AG, Baar, Switzerland
| | - Todor Stoyanov
- Institute of Biophysics and Biomedical Engineering, Bulgraian Academy of Sciences, Sofia, Bulgaria
| | - Roger Abächerli
- Lucerne University of Applied Sciences and Arts (HSLU), Horw, Switzerland
- Cardiovascular Research Institute of Basel (CRIB), University Hospital Basel, Basel, Switzerland
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Abstract
Brugada syndrome (BrS) is an inherited cardiac arrhythmia syndrome first described as a new clinical entity in 1992. Electrocardiographically characterized by distinct coved type ST segment elevation in the right-precordial leads, the syndrome is associated with a high risk for sudden cardiac death in young adults, and less frequently in infants and children. The electrocardiographic manifestations of BrS are often concealed and may be unmasked or aggravated by sodium channel blockers, a febrile state, vagotonic agents, as well as by tricyclic and tetracyclic antidepressants. An implantable cardioverter defibrillator is the most widely accepted approach to therapy. Pharmacologic therapy is designed to produce an inward shift in the balance of currents active during the early phases of the right ventricular action potential (AP) and can be used to abort electrical storms or as an adjunct or alternative to device therapy when use of an implantable cardioverter defibrillator is not possible. Isoproterenol, cilostazol, and milrinone boost calcium channel current and drugs like quinidine, bepridil, and the Chinese herb extract Wenxin Keli inhibit the transient outward current, acting to diminish the AP notch and thus to suppress the substrate and trigger for ventricular tachycardia or fibrillation. Radiofrequency ablation of the right ventricular outflow tract epicardium of patients with BrS has recently been shown to reduce arrhythmia vulnerability and the electrocardiographic manifestation of the disease, presumably by destroying the cells with more prominent AP notch. This review provides an overview of the clinical, genetic, molecular, and cellular aspects of BrS as well as the approach to therapy.
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Affiliation(s)
| | - Bence Patocskai
- Masonic Medical Research Laboratory, Utica, NY 13501
- Department of Pharmacology & Pharmacotherapy, University of Szeged, Szeged, Hungary
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Nakagawa M, Ezaki K, Miyazaki H, Ebata Y, Shinohara T, Teshima Y, Yufu K, Takahashi N, Saikawa T. False tendons may be associated with the genesis of J-waves: prospective study in young healthy male. Int J Cardiol 2014; 172:428-33. [PMID: 24507740 DOI: 10.1016/j.ijcard.2014.01.101] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Revised: 12/20/2013] [Accepted: 01/19/2014] [Indexed: 01/14/2023]
Abstract
BACKGROUND Recent studies showed that J-waves are associated with vulnerability to ventricular fibrillation. Recently we reported the association between false tendons (FTs) and J-waves in a retrospective study. METHODS AND RESULTS We prospectively studied 50 young healthy men (mean age 24.6±2.7 years). FTs were detected echocardiographically and classified based on their points of attachment as type 1 (longitudinal type), type 2 (diagonal type), and type 3 (transverse type). J-waves were defined as terminal QRS notching or slurring with ≥0.1 mV. The filtered QRS duration (fQRSd), RMS40, and LAS40 were measured on signal-averaged ECGs. FTs were detected in 37 of the 50 subjects (74%). The incidence of J-waves was significantly higher in subjects with type 1 or type 2 FTs than those with no- or type 3 FTs (61% vs. 26%, p<0.05). The leads with J-waves were closely associated with the location of the FT. While no late potential was recorded in any study subjects, fQRSd and LAS40 were significantly longer in subjects with type 1 or type 2 FTs (p<0.05). Univariate and multivariate logistic regression analysis revealed that only the existence of FTs (type 1 or 2) was an independent predictor of the presence of J-waves. CONCLUSIONS Our results suggest that FTs were related to the genesis of J-waves with conduction delay.
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Affiliation(s)
- Mikiko Nakagawa
- Department of Cardiology and Clinical Examination, Faculty of Medicine, Oita University, 1-1 Idaigaoka, Yufu City, Oita 879-5593, Japan.
| | - Kaori Ezaki
- Department of Cardiology and Clinical Examination, Faculty of Medicine, Oita University, 1-1 Idaigaoka, Yufu City, Oita 879-5593, Japan
| | - Hiroko Miyazaki
- Department of Cardiology and Clinical Examination, Faculty of Medicine, Oita University, 1-1 Idaigaoka, Yufu City, Oita 879-5593, Japan
| | - Yuki Ebata
- Department of Cardiology and Clinical Examination, Faculty of Medicine, Oita University, 1-1 Idaigaoka, Yufu City, Oita 879-5593, Japan
| | - Tetsuji Shinohara
- Department of Cardiology and Clinical Examination, Faculty of Medicine, Oita University, 1-1 Idaigaoka, Yufu City, Oita 879-5593, Japan
| | - Yasushi Teshima
- Department of Cardiology and Clinical Examination, Faculty of Medicine, Oita University, 1-1 Idaigaoka, Yufu City, Oita 879-5593, Japan
| | - Kunio Yufu
- Department of Cardiology and Clinical Examination, Faculty of Medicine, Oita University, 1-1 Idaigaoka, Yufu City, Oita 879-5593, Japan
| | - Naohiko Takahashi
- Department of Cardiology and Clinical Examination, Faculty of Medicine, Oita University, 1-1 Idaigaoka, Yufu City, Oita 879-5593, Japan
| | - Tetsunori Saikawa
- Department of Cardiology and Clinical Examination, Faculty of Medicine, Oita University, 1-1 Idaigaoka, Yufu City, Oita 879-5593, Japan
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Nakagawa M, Tsunemitsu C, Katoh S, Kamiyama Y, Sano N, Ezaki K, Miyazaki H, Teshima Y, Yufu K, Takahashi N, Saikawa T. Effect of ECG filter settings on J-waves. J Electrocardiol 2013; 47:7-11. [PMID: 24369740 DOI: 10.1016/j.jelectrocard.2013.10.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Indexed: 11/25/2022]
Abstract
BACKGROUND While J-waves were observed in healthy populations, variations in their reported incidence may be partly explicable by the ECG filter setting. METHODS We obtained resting 12-lead ECG recordings in 665 consecutive patients and enrolled 112 (56 men, 56 women, mean age 59.3±16.1years) who manifested J-waves on ECGs acquired with a 150-Hz low-pass filter. We then studied the J-waves on individual ECGs to look for morphological changes when 25-, 35-, 75-, 100-, and 150Hz filters were used. RESULTS The notching observed with the 150-Hz filter changed to slurring (42%) or was eliminated (28%) with the 25-Hz filter. Similarly, the slurring seen with the 150-Hz filter was eliminated on 71% of ECGs recorded with the 25-Hz filter. The amplitude of J-waves was significantly lower with 25- and 35-Hz than 75-, 100-, and 150-Hz filters (p<0.0001). CONCLUSIONS The ECG filter setting significantly affects the J-wave morphology.
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Affiliation(s)
- Mikiko Nakagawa
- Department of Cardiology and Clinical Examination, 1-1 Idaigaoka, Yufu City, Oita, Japan.
| | - Chie Tsunemitsu
- Laboratory Medicine, Faculty of Medicine, Oita University, 1-1 Idaigaoka, Yufu City, Oita, Japan
| | - Sayo Katoh
- Laboratory Medicine, Faculty of Medicine, Oita University, 1-1 Idaigaoka, Yufu City, Oita, Japan
| | - Yukari Kamiyama
- Laboratory Medicine, Faculty of Medicine, Oita University, 1-1 Idaigaoka, Yufu City, Oita, Japan
| | - Nario Sano
- Laboratory Medicine, Faculty of Medicine, Oita University, 1-1 Idaigaoka, Yufu City, Oita, Japan
| | - Kaori Ezaki
- Department of Cardiology and Clinical Examination, 1-1 Idaigaoka, Yufu City, Oita, Japan
| | - Hiroko Miyazaki
- Department of Cardiology and Clinical Examination, 1-1 Idaigaoka, Yufu City, Oita, Japan
| | - Yasushi Teshima
- Department of Cardiology and Clinical Examination, 1-1 Idaigaoka, Yufu City, Oita, Japan
| | - Kunio Yufu
- Department of Cardiology and Clinical Examination, 1-1 Idaigaoka, Yufu City, Oita, Japan
| | - Naohiko Takahashi
- Department of Cardiology and Clinical Examination, 1-1 Idaigaoka, Yufu City, Oita, Japan
| | - Tetsunori Saikawa
- Department of Cardiology and Clinical Examination, 1-1 Idaigaoka, Yufu City, Oita, Japan
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Nakagawa M, Ezaki K, Miyazaki H, Wakisaka O, Shinohara T, Teshima Y, Yufu K, Takahashi N, Saikawa T. Electrocardiographic characteristics of patients with false tendon: Possible association of false tendon with J waves. Heart Rhythm 2012; 9:782-8. [DOI: 10.1016/j.hrthm.2011.12.022] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/24/2011] [Indexed: 10/14/2022]
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Abstract
Feedback modules, which appear ubiquitously in biological regulations, are often subject to disturbances from the input, leading to fluctuations in the output. Thus, the question becomes how a feedback system can produce a faithful response with a noisy input. We employed multiple time scale analysis, Fluctuation Dissipation Theorem, linear stability, and numerical simulations to investigate a module with one positive feedback loop driven by an external stimulus, and we obtained a critical quantity in noise attenuation, termed as "signed activation time". We then studied the signed activation time for a system of two positive feedback loops, a system of one positive feedback loop and one negative feedback loop, and six other existing biological models consisting of multiple components along with positive and negative feedback loops. An inverse relationship is found between the noise amplification rate and the signed activation time, defined as the difference between the deactivation and activation time scales of the noise-free system, normalized by the frequency of noises presented in the input. Thus, the combination of fast activation and slow deactivation provides the best noise attenuation, and it can be attained in a single positive feedback loop system. An additional positive feedback loop often leads to a marked decrease in activation time, decrease or slight increase of deactivation time and allows larger kinetic rate variations for slow deactivation and fast activation. On the other hand, a negative feedback loop may increase the activation and deactivation times. The negative relationship between the noise amplification rate and the signed activation time also holds for the six other biological models with multiple components and feedback loops. This principle may be applicable to other feedback systems.
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Affiliation(s)
- Liming Wang
- Center for Mathematical and Computational Biology, Center for Complex Biological Systems, and Department of Mathematics, University of California at Irvine, Irvine, California, United States of America
| | - Jack Xin
- Center for Mathematical and Computational Biology, Center for Complex Biological Systems, and Department of Mathematics, University of California at Irvine, Irvine, California, United States of America
| | - Qing Nie
- Center for Mathematical and Computational Biology, Center for Complex Biological Systems, and Department of Mathematics, University of California at Irvine, Irvine, California, United States of America
- * E-mail:
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García-Niebla J, Serra-Autonel G, de Luna AB. Certain things to bear in mind when recording electrocardiograms in subjects with early repolarization. Am J Cardiol 2010; 105:1202-3. [PMID: 20381678 DOI: 10.1016/j.amjcard.2009.12.027] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2009] [Revised: 12/20/2009] [Accepted: 12/20/2009] [Indexed: 11/17/2022]
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