Search Results
Results 351 - 400 of 1291
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Larroude Charlotte E - - 2006
BACKGROUND: QT dynamics parameters are used only in sinus rhythm. However, because many patients with paroxysmal atrial fibrillation undergo antiarrhythmic treatment that changes QT, developing methods for measuring QT dynamics during atrial fibrillation is important. OBJECTIVES: The purpose of this study was to evaluate whether QT dynamics in atrial fibrillation ...
Alvarado-Serrano Carlos - - 2006
We propose novel indices of ventricular repolarization intervals, the JTp/JT, Tpe/JTp and Tpe/JT ratios. These indices have been compared with the duration of the ventricular repolarization intervals and other ratios in 17 normal subjects and 17 patients with old myocardial infarction. In the intervals and other ratios, the best separation ...
Karp Jeffrey M - - 2006
BACKGROUND: Long QT syndrome (LQTS) is associated with life-threatening cardiac arrhythmias causing syncope and sudden cardiac death, frequently precipitated by physical or psychological stress. TYPES OF STUDIES REVIEWED: The authors did a literature review of data published in peer-reviewed medical and dental journals. They also extracted epidemiologic information, correlations between ...
Okmen Ertan - - 2006
Coronary ischemia augments inhomogeneity in ventricular repolarization. Decrease in the QT dispersion (QTd) following restoration of coronary blood flow to the ischemic myocardium by successful percutaneous coronary intervention (PCI) is an expected outcome. The purpose of the study was to seek whether glycoprotein IIb/IIIa (GP IIb/IIIa) inhibition has additional beneficial ...
Furukawa Yoshio - - 2006
BACKGROUND: Recent studies have demonstrated that increased QT interval variability (QTV) is associated with a greater susceptibility to ventricular arrhythmias and that patients with prior myocardial infarction (MI) were prone to ventricular arrhythmias during the daytime. The goal of the present study was to investigate the circadian variation of the ...
Schillaci Giuseppe - - 2006
BACKGROUND: QT interval prolongation on the surface electrocardiogram (ECG) predicts cardiovascular complications in high-risk subjects, but its prognostic role in uncomplicated hypertension has been understudied. METHODS: For up to 13 years (average, 5.3 years), we followed up 2110 white patients with initially untreated essential hypertension (mean +/- SD age, 49 ...
Isbister Geoffrey K - - 2006
Although clinical trials of the antipsychotic amisulpride revealed no cardiac adverse effects, four patients with severe cardiac toxicity after overdose were reported to Australian poisons information centres in 2004-2005. All four had QT prolongation over 500 ms, two had rate-dependent bundle branch block, two developed torsades de pointes, and one ...
Boineau John P - - 2006
Although the ventricular muscle band (VMB) is formed by one continuous band of myocardium and there is some evidence to suggest that it may contract sequentially along its course from the right ventricle, through the septum, then along its basoapical left ventricular spiral, the structure is not activated in this ...
Fish Jeffrey M JM Masonic Medical Research Laboratory, Utica, NY 13501-1787, USA. - - 2006
Dimethyl lithospermate B (dmLSB) is an extract of Danshen, a traditional Chinese herbal remedy, which slows inactivation of INa, leading to increased inward current during the early phases of the action potential (AP). We hypothesized that this action would be antiarrhythmic in the setting of Brugada syndrome. The Brugada syndrome ...
Obreztchikova Maria N - - 2006
OBJECTIVE: Cardiac memory (CM) is characterized by an altered T-wave morphology, which reflects altered repolarization gradients. We hypothesized that the delayed rectifier currents, I(Kr) and I(Ks), might contribute to these repolarization changes. METHODS: We studied conscious, chronically instrumented dogs paced from the postero-lateral left ventricular (LV) wall at rates 5-10% ...
Schenck John B - - 2006
Hypothyroidism can manifest with myriad cardiac abnormalities, often consisting of a combination of morphologic and functional changes. Low voltage, sinus bradycardia, and slowed conduction are usually found on electrocardiography. We describe a patient with severe hypothyroidism who presented with presyncope, prolongation of the QT interval, and polymorphic ventricular tachycardia (torsades ...
De Mello Walmor C WC Department of Pharmacology, Medical Sciences Campus, School of Medicine, San Juan, PR 00936-5067, USA. - - 2006
The effect of chronic administration of eplerenone on cardiac remodelling and electrical properties was investigated in the failing heart of cardiomyopathic hamsters (TO-2) at five months of age. Two-month-old hamsters were treated with eplerenone (200 mg/kg/day) administered into the chow for a period of three months. Measurements of membrane potential ...
Karakaya Osman - - 2007
Isolated coronary ectatic but otherwise normal epicardial coronary arteries are an infrequent angiographic finding. We sought to determine whether coronary artery ectasia (CAE) may alter QT-interval duration and dispersion. The study population consisted of 24 patients with isolated CAE and otherwise normal epicardial coronary arteries (group 1) and sex- and ...
Nash Martyn P - - 2006
Steep action potential duration (APD) restitution has been shown to facilitate wavebreak and ventricular fibrillation. The global APD restitution properties in cardiac patients are unknown. We report a combined clinical electrophysiology and computer modelling study to: (1) determine global APD restitution properties in cardiac patients; and (2) examine the interaction ...
Narayan Sanjiv M - - 2006
T-wave alternans (TWA) reflects beat-to-beat fluctuations in the electrocardiographic T-wave, and is associated with dispersion of repolarization and the mechanisms for sudden cardiac arrest (SCA). This review examines the bench-to-bedside literature that, over decades, has linked alternans of repolarization in cellular, whole-heart, and human studies with spatial dispersion of repolarization, ...
Vukajlovic Dejan D - - 2006
BACKGROUND: It has been shown that mortality risk in patients after myocardial infarction could be estimated by heart rate turbulence (HRT), a short-term change in heart rate after ventricular premature beat (VPB), presumably caused by baroreceptor mechanism. We sought to determine whether pharmacological blockade with atropine, or augmentation of vagal ...
Carlsson Leif - - 2006
This study evaluated the effects of the novel antiarrhythmic agent AZD7009 on atrial and ventricular repolarization and on the Na+-current system, using Vmax as an index. Anesthetized dogs were infused with AZD7009 or azimilide to produce three pseudo steady-state plasma concentrations in vivo. Microelectrode techniques were used to record action ...
Kalisnik Jurij M - - 2006
BACKGROUND: Altered autonomic regulation precipitates cardiac arrhythmias and increases the risk of sudden cardiac death. This risk is further increased by changes in ventricular repolarization. Autonomic regulation is deranged in patients after myocardial on-pump revascularization. We aimed to clarify how off-pump coronary artery bypass grafting (CABG) affects postoperative cardiac autonomic ...
Zhang Yanzhou - - 2006
An increase in spatial dispersion of ventricular refractory periods reflects inhomogeneity of ventricular refractoriness and is associated with an increased risk of life-threatening ventricular arrhythmias. Spatial dispersion in ventricular refractoriness is determined by the differences in refractory periods of myocytes in epicardium, mid-myocardium and endocardium. Prolongation of ventricular repolarisation with ...
Ahmed Najeeb - - 2006
Long QT syndrome (LQTS) can be asymptomatic-identifiable as an incidental finding on electrocardiogram-or it can present with palpitation, syncope, seizures, or sudden cardiac death. LQTS is characterized by a prolonged QT interval, which can be associated with a specific form of polymorphic ventricular tachycardia known as torsade de pointes. Other ...
Wang Lan - - 2006
The effects of amiodarone on transmural dispersion of ventricular effective refractory periods (ERPs) in the normal and hypertrophic canine heart were investigated in vivo. By using the programmed stimulation protocol, the ERPs of epicardium (Epi), midmyocardium (Mid) and endocardium (Endo) were measured by inserting specially-designed electrodes into the three myocardial ...
Vrtovec Bojan - - 2006
QTc interval prolongation is associated with increased mortality rates in patients with advanced heart failure. We investigated the predictive value of prolonged QTc interval in 567 patients with heart failure who were undergoing coronary artery bypass graft surgery The patients were in New York Heart Association class III or IV, ...
Savelieva Irina - - 2006
Ivabradine is a novel heart-rate-lowering agent that acts specifically on the sinoatrial node by selectively inhibiting the I(f) current, which is the current predominantly responsible for the slow diastolic depolarization of pacemaker cells. Unlike many rate-lowering agents, ivabradine reduces heart rate in a dose-dependent manner both at rest and during ...
Walls J - - 2006
Atrioventricular block has been described in association with cases of long QT syndrome and mortality is increased in this subgroup. We describe an infant with congenital QT prolongation and atrioventricular block with normal cardiac function, leading to the initial diagnosis of long QT syndrome. She subsequently developed dilated cardiomyopathy requiring ...
Bluzaite Ina - - 2006
The aim of the article is to review the literature data about the significance and problems of the QT dispersion and heart rate variability in sudden death risk stratification in patients with coronary heart disease. QT dispersion is defined as the difference between the longest and the shortest QT intervals ...
Cerrone M - - 2006
The recently discovered hereditary channelopathy, the Short QT Syndrome (SQTS), is an important advance in clinical and molecular cardiology that has opened new doors for investigating the manner in which alterations in excitability and action potential morphology may facilitate the occurrence of ventricular fibrillation. In this brief review we address ...
Owecki M M Department of Endocrinology, Metabolism and Internal Medicine, Poznan University of Medical Sciences, PoznaƄ, Poland. - - 2006
Overt hyperthyroidism and hypothyroidism exert a major effect on cardiac function and on ECG. The influence of subclinical hyperthyroidism on the circulatory system is still under debate. Few studies examined the effect of thyroid hormones on ventricular repolarization measured by corrected QT interval (QTc). Longer QTc is associated with increased ...
Lu Sheng S Dept. of Medicine, Weill Med. Coll. of Cornell Univ., New York, NY, - - 2006
QT dispersion (QTD) is thought to represent the regional nonuniformity of ventricular repolarization and can serve as a prognostic marker for vulnerability to ventricular arrhythmias and risk for sudden cardiac death (SCD). In this study, we used an in vivo swine model to investigate the change of QT-peak dispersion before ...
Brisinda Donatella - - 2006
Magnetocardiography (MCG) is the recording of the magnetic field (MF) generated by cardiac electrophysiological activity. Because it is a contactless method, MCG is ideal for noninvasive cardiac mapping of small experimental animals. The aim of this study was to assess age-related changes of cardiac intervals and ventricular repolarization (VR) maps ...
Fish Jeffrey M JM Masonic Medical Research Laboratory, Utica, New York 13501-1787, - - 2005
Resynchronization therapy involving right ventricular endocardial and left ventricular epicardial pacing improves cardiac output, quality of life, and New York Heart Association functional class in patients with congestive heart failure. Although a great deal of attention has been directed at showing the mechanical benefits and in fine-tuning the biventricular pacing ...
Lazzerini Pietro Enea - - 2006
Cardiovascular involvement is common in connective tissue diseases (CTD), with relevant implications in terms of morbidity and mortality. Rhythm disturbances, i.e. conduction defects and tachyarrhythmias, represent a frequent clinical manifestation of CTD-associated cardiovascular damage and a possible cause of sudden death. The underlying arrhythmogenic mechanisms are probably multiple and intriguing, ...
Grzywacz Francis W - - 2006
Patients with advanced cardiomyopathy develop prolongations in ventricular myocyte action potential duration that are reflected by prolongations of QT intervals on surface electrocardiograms. Recent studies demonstrate that the placement of a left ventricular (LV) assist device, which induces profound cardiac decompression, acutely increases QT intervals within hours. The goal of ...
Ozkan S?leyman - - 2005
OBJECTIVE: Life-threatening arrhythmias and sudden death remain to be serious late complications after correction of tetralogy of Fallot. The aim of this study was to detect ventricular arrhythmia incidence and to find out the relationship between ventricular arrhythmia and the transannular and infundibular patch repair techniques to correct tetralogy of ...
Papadopoulos Christodoulos E - - 2006
INTRODUCTION: The aim of the present study was to evaluate a possible association between QT dispersion (QTd) and the amount of viable and scarred myocardial tissue after revascularization in patients with coronary artery disease and impaired left ventricular (LV) function. METHODS: Twenty-two patients with ischemic LV dysfunction underwent dobutamine stress ...
Nakai Kenji - - 2006
BACKGROUND: QT dispersion reveals heterogeneities in the repolarization time in the three-dimensional (3D) structure of the ventricular myocardium. In this study, we report on a 3D function map of recovery time (RT) dispersions as measured by 64-channel magnetocardiography (MCG). METHODS: MCG were simultaneously recorded in 29 controls and 21 patients ...
Ueda Hiroyasu - - 2006
BACKGROUND: QT dispersion is increased in acute myocardial infarction (AMI), but the relation of QT dispersion to left ventricular (LV) function has not yet been fully elucidated. The purpose of this study was to evaluate the relationship between QT dispersion and LV function in patients with successful coronary stenting in ...
Brugada Ramon - - 2005
The QT interval on an electrocardiogram signifies the time required for the heart to repolarize after depolarization. It has long been appreciated that a long QT interval predisposes patients to life-threatening ventricular arrhythmia. Short QT syndrome is a newly described disease characterized by a shortened QT interval and by episodes ...
Christidis D D Section of Public Health, Panhellenic Association for Continual Medical Research (PACMeR), Thoma Pashidi 31, TK 45445 Ioannina, Athens, Greece. - - 2006
Sudden unexplained/unexpected death (SUDEP) in epilepsy is a major cause of death accounting for 7-17% of the mortality among epileptic patients. Prolongation of QT-interval has been issued as a major mechanism in SUDEP since it is associated with fatal cardiac arrhythmias. This condition may be further precipitated by anti-epileptic treatment. ...
Kosar Feridun - - 2006
A reduction in QT dispersion (QTd) has been previously shown in patients receiving thrombolytics and undergoing coronary artery bypass grafting (CABG). The purpose of the present study was to investigate changes occurring in corrected QT intervals or QT dispersion after CABG and concomitant aneurysmectomy in the same session. The study ...
Yue Arthur M - - 2005
BACKGROUND: The ability to determine spatial and dynamic changes in ventricular repolarization may help to understand arrhythmogenic mechanisms in humans. We hypothesized that noncontact mapping could be used to investigate global activation-repolarization coupling in the human ventricle during steady state and premature extrastimulation. METHODS AND RESULTS: Activation-recovery intervals (ARIs) determined ...
Costantini Danny L DL Program in Cardiovascular Research, The Hospital for Sick Children, Toronto, Ontario M5G 1X8, - - 2005
Rhythmic cardiac contractions depend on the organized propagation of depolarizing and repolarizing wavefronts. Repolarization is spatially heterogeneous and depends largely on gradients of potassium currents. Gradient disruption in heart disease may underlie susceptibility to fatal arrhythmias, but it is not known how this gradient is established. We show that, in ...
Bjerregaard Preben - - 2005
Short QT syndrome (SQTS) is an inheritable primary electrical disease of the heart, discovered in 1999. It is characterized by an abnormally short QT interval (<300 ms) and a propensity to atrial fibrillation and sudden cardiac death (SCD). Like in the case of long QT syndrome there is more than ...
Lankipalli Ramarao S - - 2005
Long QT syndrome is a disease of delayed ventricular repolarization. It manifests clinically as recurrent syncope and sudden cardiac death caused by an atypical form of polymorphic ventricular tachycardia known as torsades de pointes (TdP). Evidence obtained from the studies using the rabbit left and right ventricular wedge preparations indicates ...
Wong K Y K - - 2005
To find out what spectrum of cardiac abnormalities are found in those stroke survivors who can be deemed to be at high cardiac risk by their having long QT. 202 patients with good recovery from a cerebrovascular event occurring at least one month previously were recruited into a prospective epidemiological ...
Borggrefe Martin M 1st Department of Medicine-Cardiology, University Hospital Mannheim, Faculty of Clinical Medicine of the University of Heidelberg, 68167 Mannheim, Germany. - - 2005
The short QT syndrome is a new congenital entity associated with familial atrial fibrillation and/or sudden death or syncope. Three different gain-of-function mutations in genes encoding for cardiac potassium channels (KCNH2, KCNQ1, and KCNJ2) have been identified up to now to cause short QT syndrome. The syndrome is characterized electrocardiographically ...
Yue Arthur M - - 2005
OBJECTIVES: This study was aimed at evaluating global characteristics of electrical restitution in the human ventricle using noncontact mapping. BACKGROUND: Steep action potential restitution (slope >1) and conduction velocity (CV) restitution have been linked with propensity to ventricular fibrillation, but clinical measurement of global electrical restitution had not been feasible. ...
Chang Gwo-Jyh - - 2006
We studied the electrophysiological and antiarrhythmic actions of HA-7 [N-benzyl-7-methoxy-2,3,4,9-tetrahydrofuro[2,3-b]quinoline-3,4-dione], a furoquinoline alkaloid derivative, in guinea pig heart preparations. In the perfused whole heart model, HA-7 caused a prolongation in the basic cycle length, ventricular repolarization time, and the atrioventricular (AV) nodal Wenckebach cycle length and prolonged the refractory period ...
Ueda Norihiro - - 2006
Although long QT syndrome (LQTS) and coronary occlusion-reperfusion (O/R) are arrhythmogenic, they affect ventricular action potential duration (APD) differently. In contrast to the prolonged APD in LQTS, ischemia abbreviates APD after a transient prolongation. Thus we hypothesized that the dynamic interactive effects of ischemia and LQTS on APD and its ...
Pristipino Christian - - 2005
To assess the changes in electrical stability markers in patients with previous myocardial infarction after very late reopening of the infarct-related artery, we studied QT dispersion, corrected-QT dispersion, and late potentials before and 1, 3, and 6 months after an attempt at late percutaneous coronary intervention (PCI) in 31 consecutive ...
Koller Marcus L - - 2005
BACKGROUND: Restitution kinetics and alternans of ventricular action potential duration (APD) have been shown to be important determinants of cardiac electrical stability. In this study, we tested the hypothesis that APD restitution and alternans properties differ between normal and diseased human ventricular myocardium. METHODS AND RESULTS: Monophasic action potentials were ...
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