Abstract:
:Recent studies have shown that ventricular myocardium is composed of at least 3 electrophysiologically distinct cell types: epicardial, endocardial, and M cells. Action potentials recorded from epicardial and M cells, unlike those recorded from endocardium, display a spike-and-dome morphology, the result of a prominent transient outward current-mediated phase 1. M cells are distinguished from endocardial and epicardial cells by the ability of their action potential to prolong disproportionately in response to a slowing of rate and/or to agents with class III actions. This intrinsic electrical heterogeneity contributes to the inscription of the electrocardiogram as well as to the development of a variety of cardiac arrhythmias. The transmural dispersion of repolarization is in large part responsible for the inscription of the J wave and T wave of the electrocardiogram. Because full repolarization of epicardium defines the peak of the T wave and that of the M cells, the end of the T wave, the interval between the peak and the end of the T wave provides a valuable index of transmural dispersion of repolarization. Differences in the response of the 3 cell types to pharmacologic agents and/or pathophysiological states often results in amplification of intrinsic electrical heterogeneities, thus providing a substrate as well as a trigger for the development of reentrant arrhythmias, including torsade de pointes (TdP) commonly associated with the long QT syndrome (LQTS) and the polymorphic ventricular tachycardia/fibrillation encountered in patients with the Brugada syndrome. Early repolarization of the epicardial action potential results in abnormal abbreviation of action potential duration due to an all-or-none repolarization at the end of phase 1 of the epicardial action potential. The loss of the action potential dome in epicardium but not endocardium gives rise to a large dispersion of repolarization across the ventricular wall, resulting in a transmural voltage gradient that manifests in the electrocardiogram as an ST segment elevation (or idiopathic J wave). Under these conditions, heterogeneous repolarization of the epicardial action potential gives rise to phase 2 reentry, which provides an extrasystole capable of precipitating ventricular tachycardia/fibrillation (or rapid TdP). Experimental models displaying these phenomena show electrocardiographic characteristics similar to those of the Brugada syndrome as well as those encountered during acute ischemia. Transmural dispersion of repolarization is also greatly amplified in LQTS. Disproportionate prolongation of the M-cell action potential contributes to the development of long QT intervals, wide-based or notched T waves, and a large transmural dispersion of repolarization, which provides the substrate for the development of a polymorphic ventricular tachycardia closely resembling torsade de pointes. An early afterdepolarization-induced triggered beat is thought to provide the extrasystole that precipitates TdP. Pharmacologic models of the LQT1, LQT2 and LQT3 forms of LQTS mimic the distinctive electrocardiographic, electrophysiologic, and pharmacologic responses observed in patients with these 3 different genetic syndromes. In LQTS, as in the Brugada syndrome, a mutation in an ion channel gene (in some cases the same gene--SCN5A) is responsible for the development of a large transmural dispersion of repolarization, which serves to provide the arrhythmogenic substrate tha can lead to sudden death.
journal_name
J Electrocardioljournal_title
Journal of electrocardiologyauthors
Antzelevitch C,Yan GX,Shimizu Wdoi
10.1016/s0022-0736(99)90074-2keywords:
subject
Has Abstractpub_date
1999-01-01 00:00:00pages
158-65eissn
0022-0736issn
1532-8430journal_volume
32 Supplpub_type
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journal_title:Journal of electrocardiology
pub_type: 杂志文章,评审
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更新日期:2019-01-01 00:00:00
abstract::Considerable efforts have been invested recently to improve electrocardiographic (ECG) classification accuracy for left ventricular hypertrophy (LVH). This study examines how LVH classification accuracy is influenced by (1) the selection of an echocardiographic standard for LVH, (2) LVH severity level in the test grou...
journal_title:Journal of electrocardiology
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abstract::The electrocardiogram (ECG) remains the most immediately accessible and widely used diagnostic tool for guiding emergency treatment strategies. The ECG recorded during acute myocardial ischemia is of diagnostic, therapeutic, and prognostic significance. In patients with myocardial ischemia as a result of decreased blo...
journal_title:Journal of electrocardiology
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更新日期:2010-03-01 00:00:00
abstract::Different genetic types of the long QT syndrome (LQTS) are associated with distinct ECG manifestations, which relate to the type and magnitude of ion channel dysfunction. The QTc duration does not differentiate LQTS types, and therefore other static and dynamic ECG parameters reflecting changes in T wave morphology ar...
journal_title:Journal of electrocardiology
pub_type: 杂志文章,评审
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更新日期:2006-10-01 00:00:00
abstract::Sources of error in averaging for late ventricular potentials include variations in the magnitude and timing of late potentials as well as variability in the temporal alignment of successive cardiac cycles during averaging. Since these errors can both attenuate high frequency signals and add artifactual components to ...
journal_title:Journal of electrocardiology
pub_type: 杂志文章
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更新日期:1987-10-01 00:00:00
abstract:INTRODUCTION:The right ventricular myocardial infarction (RVMI) has traditionally been mainly related to inferior wall ST elevation myocardial infarction (STEMI). This study assessed the RVMI electrocardiographic (ECG-RVMI) signs in relationship to ECG-based STEMI localization and to the infarct related artery in patie...
journal_title:Journal of electrocardiology
pub_type: 杂志文章
doi:10.1016/j.jelectrocard.2016.08.001
更新日期:2016-01-01 00:00:00
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journal_title:Journal of electrocardiology
pub_type: 杂志文章
doi:10.1016/0022-0736(89)90037-x
更新日期:1989-07-01 00:00:00
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journal_title:Journal of electrocardiology
pub_type: 杂志文章
doi:10.1054/jelc.2001.23358
更新日期:2001-04-01 00:00:00
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journal_title:Journal of electrocardiology
pub_type: 杂志文章
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更新日期:1984-10-01 00:00:00
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journal_title:Journal of electrocardiology
pub_type: 杂志文章
doi:10.1016/j.jelectrocard.2015.08.026
更新日期:2016-01-01 00:00:00
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journal_title:Journal of electrocardiology
pub_type: 杂志文章
doi:10.1016/s0022-0736(99)90032-8
更新日期:1999-01-01 00:00:00
abstract::The authors present an original method for the discrimination of patients prone to ventricular tachycardia. The wavelet transform, which is a new time-scale technique suitable for transient signal detection, was applied to bipolar unfiltered X, Y, Z signal-averaged electrocardiograms in 20 postinfarction patients with...
journal_title:Journal of electrocardiology
pub_type: 杂志文章
doi:10.1016/0022-0736(93)90052-f
更新日期:1993-10-01 00:00:00
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journal_title:Journal of electrocardiology
pub_type: 杂志文章
doi:10.1016/j.jelectrocard.2011.03.010
更新日期:2011-07-01 00:00:00
abstract:BACKGROUND:Data are limited on long-term associations of favorable cardiovascular risk profile (i.e., low-risk) and changes in risk profile with ECG abnormality development. METHODS:The Chicago Healthy Aging Study (CHAS) involved re-examination of 1395 participants, ages 65-84 years in 2007-10, free of baseline major ...
journal_title:Journal of electrocardiology
pub_type: 杂志文章
doi:10.1016/j.jelectrocard.2018.06.015
更新日期:2018-01-01 00:00:00
abstract::Controlled physical training has been shown to be a valuable therapeutic addition to a pharmacological treatment in patients with chronic heart failure (CHF). It is speculated that repeated physical training can improve the autonomic modulation of the cardiovascular system in patients with CHF. The present study evalu...
journal_title:Journal of electrocardiology
pub_type: 杂志文章,随机对照试验
doi:10.1016/j.jelectrocard.2012.01.002
更新日期:2012-05-01 00:00:00
abstract::A His bundle electrogram was obtained in a 70 year old male with syncopal episodes. A split bundle of His deflection was recorded. After the intravenous administration of phentolamine, a marked shortening of the H-H' interval was observed. This signifies an improvement in conduction at the bundle of His level. ...
journal_title:Journal of electrocardiology
pub_type: 杂志文章
doi:10.1016/s0022-0736(78)80147-2
更新日期:1978-10-01 00:00:00
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journal_title:Journal of electrocardiology
pub_type: 杂志文章
doi:10.1016/s0022-0736(78)80107-1
更新日期:1978-04-01 00:00:00
abstract::Extra AV nodal Wenckebach periodicity was diagnosed in seven patients. The most frequent form of this conduction abnormality was an exit block. The underlying block was localized in the sinoatrial junction and in the atria in two patients; the AV junction and the ventricle were the site of the Wenckebach periodicity i...
journal_title:Journal of electrocardiology
pub_type: 杂志文章
doi:10.1016/s0022-0736(81)80003-9
更新日期:1981-07-01 00:00:00
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journal_title:Journal of electrocardiology
pub_type: 杂志文章
doi:10.1016/j.jelectrocard.2015.02.005
更新日期:2015-07-01 00:00:00
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journal_title:Journal of electrocardiology
pub_type: 杂志文章
doi:10.1054/jelc.2003.50010
更新日期:2003-01-01 00:00:00
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journal_title:Journal of electrocardiology
pub_type: 杂志文章
doi:10.1054/jelc.2000.20299
更新日期:2000-01-01 00:00:00
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journal_title:Journal of electrocardiology
pub_type: 杂志文章
doi:10.1016/s0022-0736(76)80021-0
更新日期:1976-01-01 00:00:00
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journal_title:Journal of electrocardiology
pub_type: 杂志文章
doi:10.1016/s0022-0736(78)80098-3
更新日期:1978-04-01 00:00:00
abstract::Successful curative treatment of right atrial tachycardia (AT) can be obtained provided detailed catheter activation mapping of the target site for radiofrequency energy application has been accomplished. However, right AT mapping may be difficult with a single roving catheter due to infrequent presence or noninducibi...
journal_title:Journal of electrocardiology
pub_type: 杂志文章
doi:10.1016/s0022-0736(98)90298-9
更新日期:1998-01-01 00:00:00
abstract::Exercise testing was evaluated in 51 patients with critical left coronary artery disease (LCA) documented by coronary arteriography within two weeks of their bicycle ergometer (26 patients) or treadmill (25 patients) electrocardiographic study. Adequate tests, as defined by the patient having reached 85% of predicted ...
journal_title:Journal of electrocardiology
pub_type: 杂志文章
doi:10.1016/s0022-0736(79)80057-6
更新日期:1979-07-01 00:00:00
abstract:BACKGROUND:QRS-duration predicts mortality in patients with heart failure and, to a lesser extent, the general population. However, in patients with diabetes, its prognostic significance is unknown. To better understand how QRS-duration relates to mortality among those with diabetes, we explored survival as a function ...
journal_title:Journal of electrocardiology
pub_type: 杂志文章
doi:10.1016/j.jelectrocard.2019.11.053
更新日期:2020-01-01 00:00:00
abstract::The electrocardiogram (ECG) is a relatively insensitive tool for the detection of right ventricular hypertrophy (RVH), but some criteria have high specificity. The recommended ECG screening criteria for RVH are not sufficiently sensitive or specific for screening for mild RVH in adults without clinical cardiovascular ...
journal_title:Journal of electrocardiology
pub_type: 杂志文章,评审
doi:10.1016/j.jelectrocard.2017.09.004
更新日期:2018-01-01 00:00:00
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journal_title:Journal of electrocardiology
pub_type: 杂志文章
doi:10.1016/j.jelectrocard.2009.07.018
更新日期:2009-11-01 00:00:00
abstract::Thoracic electromaps were recorded before and after sublingual nitroglycerin (NG) in 26 subjects 15 and 30 days after acute myocardial infarction (MI), in order to evaluate the effect of the drug on injury potentials. Ten patients with documented left ventricular aneurysm were also studied 5 to 46 months after acute M...
journal_title:Journal of electrocardiology
pub_type: 杂志文章
doi:10.1016/s0022-0736(81)81007-2
更新日期:1981-10-01 00:00:00
abstract::In a patient with the sick sinus syndrome and near syncope a prolonged sinus pause was documented and reproduced thereafter during sustained deep inspiration. Administration of intravenous atropine abolished this phenomenon, most probably indicating a hyperresponsiveness of the sinus node and AV junction to a vagotoni...
journal_title:Journal of electrocardiology
pub_type: 杂志文章
doi:10.1016/s0022-0736(86)80012-7
更新日期:1986-01-01 00:00:00