Search Results
Results 451 - 500 of 1291
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Yamada Satsuki - - 2005
Cardiac diseases are the leading cause of death in population. Diagnostic tests to detect cardiac dysfunction at an early stage of the disease are desirable. The major focus has been centered on tests evaluating the perfusion of the heart with imaging techniques or detecting alterations in electrical or mechanical function ...
Kies Susan J - - 2005
Long QT syndrome is a malfunction of cardiac ion channels resulting in impaired ventricular repolarization that can lead to a characteristic polymorphic ventricular tachycardia known as torsades de pointes. Stressors, by increasing sympathetic tone, and drugs can provoke torsade de pointes, leading to syncope, seizures, or sudden cardiac death in ...
Santoro A - - 2005
The task of dialysis therapy is, amongst other things, to remove excess potassium (K+) from the body. The need to achieve an adequate K+ removal with the risk of cardiac arrhythmias due to sudden intra-extracellular K+ gradient advises the distribution of the removal throughout the dialysis session instead of just ...
Bonnemeier Hendrik - - 2005
Beta-adrenergic blockers exert significant antiarrhythmic activity during ischemia and reperfusion. To further explore the beneficial effects conferred by alpha-1-adrenoceptor blockade on ventricular repolarization dynamicity in the acute phase of myocardial infarction (AMI), we compared carvedilol with metoprolol in the setting of primary percutaneous coronary intervention (PCI). In a prospective study, ...
Clayton Richard H - - 2005
The initiation of re-entrant cardiac arrhythmias is associated with increased dispersion of repolarisation, but the details are difficult to investigate either experimentally or clinically. We used a computational model of cardiac tissue to study systematically the association between action potential duration (APD) dispersion and susceptibility to re-entry. We simulated a ...
Satoh T T Department of Electronic Informatics, Hosei University, Tokyo 184-8584, - - 2005
This paper describes a method for accurate and stable measurement of ECG QT intervals. ECG signals from multiple leads are decomposed into orthogonal signals by the algebraic method of singular value decomposition. Major orthogonal signal components are then selected and root total power signal is formed. The root total power ...
Pittenger Basil - - 2004
Carvedilol has been shown to improve survival and morbidity in patients with heart failure. It has been demonstrated that carvedilol use is associated with dose-dependent reduction in QT dispersion (QTd) independent of the cause of heart failure, suggesting that reduction in QTd may be a mechanism by which carvedilol improves ...
Mulay Dnyaneshwar V - - 2004
BACKGROUND: This study sought to find out QT dispersion in healthy individuals and patients of acute myocardial infarction and to find correlation, if any, between QT dispersion and the incidence of ventricular arrhythmias in acute myocardial infarction. METHODS AND RESULTS: QT dispersion was calculated from a 12-lead electrocardiogram in 100 ...
Li Yang - - 2004
AIM: To investigate the effects of chronic treatment with imidapril on the electrophysiologic heterogeneous change of the noninfarcted myocardium of rabbits after myocardial infarction and the mechanism of its antiarrhythmic efficacy. METHODS: Rabbits with left coronary artery ligation were prepared and allowed to recover for 8 weeks. Myocytes were isolated ...
Barletta Giuseppe - - 2004
BACKGROUND: Ventricular repolarization abnormalities can represent a trigger for lethal arrhythmias in hypertrophic cardiomyopathy (HCM). We sought to assess whether multiparametric computerized surface ECG analysis identifies repolarization abnormalities in HCM patients, and whether this approach allows identification of patients with syncope. METHODS: In 28 HCM patients and 102 healthy subjects ...
Musialowicz Tadeusz - - 2004
OBJECTIVES: Midlatency auditory-evoked potentials (MLAEPs) may provide an objective measure of depth of sedation. The aim of this study was to evaluate MLAEPs for measuring sedation in cardiac surgery patients. DESIGN: Prospective study. SETTING: Intensive care unit of a university hospital. PARTICIPANTS: Twenty-two patients scheduled for elective coronary artery bypass ...
Stuth Eckehard A E - - 2004
BACKGROUND: Droperidol is useful for postoperative sedation in infants and children after cardiac surgery because it provides sedation and akinesia with minimal respiratory depression. However, droperidol has been associated with QT prolongation and ventricular arrhythmias. We investigated, if neuroleptanalgesic doses of droperidol led to QT prolongation and cardiac arrhythmias in ...
Smetana Peter - - 2004
INTRODUCTION: Amiodarone is an effective antiarrhythmic drug, but it has serious side effects and conducted trials did not support its prophylactic use in survivors of acute myocardial infarction. It is possible that the prophylactic use of the drug has not been tested effectively. To optimize therapy outcome, markers of drug ...
Zhang Henggui - - 2004
The rapid delayed rectifier K(+) current, I(Kr), plays a key role in repolarisation of cardiac ventricular action potentials (APs). In recent years, a novel clinical condition denoted the short QT syndrome (SQTS) has been identified and, very recently, gain in function mutations in the gene encoding the pore-forming sub-unit of ...
Yue Arthur M - - 2004
BACKGROUND: Noncontact mapping (NCM) has not been validated as a clinical technique to measure ventricular repolarization. We used NCM to determine repolarization characteristics by analysis of reconstructed unipolar electrograms (UEs) at the same sites as monophasic action potential (MAP) recordings in the human ventricle. METHODS AND RESULTS: MAPs were recorded ...
Ueda Hiroyasu - - 2004
BACKGROUND: Nicorandil, a potassium channel opener, is used for the treatment of angina pectoris and has a pharmacologic preconditioning effect. This study evaluated whether intravenous nicorandil reduces QT dispersion and prevents bradyarrhythmia during percutaneous transluminal coronary angioplasty (PTCA) of the right coronary artery. METHODS: A historical cohort study on the ...
Pueyo Esther - - 2004
A new method is proposed to evaluate the dynamics of QT interval adaptation in response to heart rate (HR) changes. The method considers weighted averages of RR intervals (RR) preceding each cardiac beat to express RR interval history accounting for the influence on repolarization duration. A global optimization algorithm is ...
Kaneko Yoshiaki - - 2004
INTRODUCTION: The aim of this study was to examine the electrophysiologic characteristics of the normal left interventricular septum (LIVS). METHODS AND RESULTS: We explored the LIVS in search of endocardial potentials following ventricular electrograms during sinus rhythm in 28 patients without structural heart disease. In all patients, low-frequency (mean amplitude: ...
Nishida Kunihiro - - 2004
INTRODUCTION: Myocardial cooling can induce J point elevation (Osborn wave) as seen on ECG of the Brugada syndrome by activating transient outward current (Ito) and causing a spike-and-dome configuration of the monophasic action potential (MAP) in the ventricular epicardium in isolated canine ventricular wedge preparations. We determined the effect of ...
Roche Frédéric - - 2004
Myocardial repolarization has been evaluated in patients with anorexia nervosa (AN) with conflicting results. The authors postulated that dynamic alterations in QT interval adaptation could characterize these patients. This study compared QT dynamicity along RR intervals from 24-hour ECG data of patients with and without AN. Twenty-five patients (23 women) ...
Lang Christopher C E - - 2004
BACKGROUND: Congestive heart failure is a common condition with high mortality. Many of these deaths are sudden and unexpected. Ventricular action potential, surface repolarization (QT interval), and dispersion of repolarization are prolonged in the failing heart, contributing to arrhythmogenesis and sudden death. We studied the relationship between QT and heart ...
Yildirim H - - 2004
BACKGROUND AND OBJECTIVE: To determine if there is any significant difference between the effects of desflurane, isoflurane and sevoflurane on the QT interval, QT dispersion, heart rate corrected QT interval and QTc dispersion of the electrocardiogram. METHODS: The study was conducted in a prospective, double blind and randomized manner in ...
Nahshoni Eitan - - 2004
QT and RR intervals' fluctuations are implicated in the development of malignant arrhythmias. Recent research has quantified repolarization lability using stochastic and linear methods. However, QT-RR intervals are nonlinearly coupled. To this end, QT and RR intervals were extracted from twenty four patients with acute myocardial infarction (AMI) and 13 ...
Poelzing Steven - - 2004
Recently, we found that repolarization heterogeneities between subepicardial and midmyocardial cells can form a substrate for reentrant ventricular arrhythmias in failing myocardium. We hypothesized that the mechanism responsible for maintaining transmural action potential duration heterogeneities in heart failure is related to intercellular uncoupling from downregulation of cardiac gap junction protein ...
Boriani Giuseppe - - 2004
BACKGROUND: The effects of atrial internal cardioversion on QT interval and QT dispersion (parameters associated with increased risk of ventricular tachyarrhythmias) are unknown. We investigated changes in QT interval, QTc and QT dispersion immediately after shock delivery for internal cardioversion in patients with chronic persistent atrial fibrillation. METHOD: Twenty-two patients ...
Anderson Keith J - - 2004
OBJECTIVE: To determine if increased QT interval dispersion (corrected and not corrected for heart rate) is associated with perioperative silent myocardial ischemia or postoperative adverse cardiovascular events. DESIGN: Blinded retrospective observational study. SETTING: University hospital. PARTICIPANTS: One hundred eighty-one perioperative patients receiving general anesthesia for elective major vascular or orthopedic ...
Ueda Hiroyasu - - 2004
BACKGROUND: Because nicorandil, a potassium channel opener, has a cardioprotective effect and attenuates reperfusion injury in patients with acute myocardial infarction (AMI), intravenous nicorandil should reduce arrhythmic mortality and QT dispersion in patients with AMI. OBJECTIVES: The purpose of this study was to evaluate whether intravenous nicorandil reduces the occurrence ...
Nemec Jan - - 2004
INTRODUCTION: The heart rate dependence of QT interval duration is abnormal in patients with congenital long QT syndrome. Patients with LQT1 have a defective I(Ks) current, a major determinant of QT response to heart rate. METHODS AND RESULTS: We studied the heart rate dependence of QT interval duration in different ...
Ueda Kazuo - - 2004
Hyperpolarization-activated cyclic nucleotide-gated channel 4 gene HCN4 is a pacemaker channel that plays a key role in automaticity of sinus node in the heart, and an HCN4 mutation was reported in a patient with sinus node dysfunction. Expression of HCN4 in the heart is, however, not confined to the sinus ...
Kosmala Wojciech - - 2004
BACKGROUND: In recent years QT dispersion (QTd) in post-infarct patients was estimated in many studies, but still little is known about its association with the presence of dysfunctional but viable myocardium. AIM: We investigated the relation between dispersion of QT interval and myocardial viability in patients after acute myocardial infarction ...
Stilli Donatella - - 2004
In normal rats, we analysed the arrhythmogenic role of intrinsic action potential duration (APD) heterogeneity. In each animal, ventricular arrhythmic events (VAEs) occurring spontaneously and during the exposure to an acute social challenge were telemetrically recorded. Action potentials were recorded from isolated left ventricular myocytes, at a pacing rate of ...
Oikarinen Lasse - - 2004
Left ventricular hypertrophy is a risk factor for cardiovascular mortality, including sudden cardiac death. Experimentally, left ventricular hypertrophy delays ventricular conduction and prolongs action potential duration. Electrocardiographic QRS duration and QT interval measures reflect these changes, but whether these measures can further stratify risk in patients with electrocardiographic left ventricular ...
Foglia Pietro E G - - 2004
BACKGROUND: Potassium and magnesium depletion prolongs the duration of the action potential of the cardiomyocyte, which predisposes to ventricular arrhythmias. In addition, potassium or magnesium depletion might impair cardiac performance and facilitate coronary artery thrombosis. METHODS: Continuous 24-h ambulatory electrocardiographic monitoring, treadmill exercise testing and echocardiography were assessed in 21 ...
Nahshoni Eitan - - 2004
QT dispersion (QTd) is a measure of interlead variations of the surface 12-lead electrocardiogram (ECG). Increased QTd, found in various cardiac diseases, reflects cardiac instability and is associated with increased risk for cardiac death. Research suggests a link between antipsychotics, ECG abnormalities (QT prolongation) and increased sudden cardiac mortality rates. ...
Insulander Per - - 2004
INTRODUCTION: A positive chronotropic effect of beta2 stimulation is well known. Case reports of ventricular arrhythmias during beta2-inhalation therapy have been published. The aim of this study was to asses the overall electrophysiologic effects of the beta2-agonist salbutamol. METHODS AND RESULTS: Electrophysiologic and hemodynamic variables were measured in 10 healthy ...
Bountioukos Manolis - - 2004
QT dispersion is prolonged in numerous cardiac diseases, representing a general repolarization abnormality. To evaluate the influence of viable myocardium on QT dispersion in patients with severely depressed left ventricular (LV) function due to coronary artery disease. 103 patients with ischemic cardiomyopathy (LV ejection fraction [EF]: 25+/-6%) were studied. Patients ...
Cheng Jian-hua - - 2004
Delayed rectifier K+ current (IK) is the major outward current responsible for ventricular repolarization. Two components of IK (IKr and IKs) have been identified in many mammalian species including humans. IKr plays a pivotal role in normal ventricular repolarization. A prolongation of action potential duration (APD) under a variety of ...
Henriksen Jens H - - 2004
BACKGROUND/AIMS: Earlier studies have shown a prolonged frequency-adjusted Q-T interval (QTc>0.440 s(1/2)) in a substantial fraction of patients with cirrhosis. The effect of beta-blockade on QTc is unknown, and its determination was the aim of the study. METHODS: Seventeen patients with cirrhosis received 80 mg propranolol orally during a haemodynamic ...
Tian Xiao-Li - - 2004
Mutations in the cardiac sodium channel gene SCN5A are responsible for type-3 long QT disease (LQT3). The genesis of cardiac arrhythmias in LQT3 is multifaceted, and the aim of this study was to further explore mechanisms by which SCN5A mutations lead to arrhythmogenesis in vivo. We engineered selective cardiac expression ...
Liu Nian - - 2004
To elucidate the mechanism of arrhythmia in healed myocardial infarction (HMI), the changes of action potential duration (APD), transient outward potassium current (Ito), delayed rectifier potassium current (IK) and inward rectifier potassium current (IK1) of left ventricular myocytes in non-infarcted zone of HMI were investigated. Rabbits were randomly assigned into ...
Nahshoni Eitan - - 2004
BACKGROUND: QT dispersion (QTd) is the maximal interlead difference in QT interval on the surface 12-lead electrocardiogram (ECG). An increase in QTd is found in various cardiac diseases and reflects cardiac autonomic imbalance. It has recently been associated with increased anxiety levels, thereby predisposing affected individuals to fatal heart disease. ...
Jain Hitender - - 2004
BACKGROUND: QT dispersion (QTd) has evoked a lot of interest in recent years as regards the basic concept of dispersion of repolarization, which it is supposed to reflect on a surface ECG, as being a marker or substrate for arrhythmogenesis. QTd has been shown to be high in patients with ...
Bányász Tamás - - 2004
The goal of this paper is two fold. First, we attempt to review the reports available on the role of I(Ks) in myocardial repolarization. Based on theoretical considerations and experimental results, it seems reasonable to assume that I(Ks)blockade will lengthen the action potential. However, results obtained with I(Ks) blockers, like ...
Macfarlane Peter W - - 2004
The West of Scotland Coronary Prevention Study (WOSCOPS) provided baseline electrocardiograms (ECGs) on 6,595 men without a previous myocardial infarction who were followed for a mean of 4.9 years during which time all events, cardiovascular or otherwise, were recorded. Half of the study group was treated with a lipid lowering ...
Wang Lexin - - 2004
Assessment of the spatial dispersion of ventricular refractory periods has become an important part of electrophysiological study in both experimental and clinical settings, because inhomogeneity of ventricular refractoriness is associated with an increased risk of life-threatening ventricular arrhythmias. Previous animal studies in dog and sheep have demonstrated that local ventricular ...
Kittnar O - - 2004
The aim of the study was to detect the changes of QT dispersion (QTd) due to cardiotoxicity of tricyclic antidepressant dosulepin. Electrocardiographic and vectorcardiographic recordings were obtained using Cardiag 112.2 diagnostic system from 28 psychiatric outpatients treated with prophylactic doses of dosulepin and compared to those obtained from 37 healthy ...
Brisinda Donatella - - 2004
INTRODUCTION: Magnetocardiographic (MCG) mapping is increasingly used for the non-invasive study of coronary artery disease (CAD), cardiomyopathy (CMP) and arrhythmias. MCG study of small animals with ischemia or CMP would provide useful experimental models for the interpretation of abnormal human patterns. The aim of this study was to assess the ...
Bonnemeier Hendrik - - 2003
BACKGROUND: Complete coronary artery reperfusion in acute myocardial infarction (AMI) has been shown to significantly improve survival. Electrical stability may be the decisive mechanism for this beneficial effect. Because electrical stability is largely dependent on ventricular repolarization, we sought to determine the impact of a modern reperfusion strategy (ie, direct ...
Schimpf Rainer - - 2003
INTRODUCTION: A congenital short QT interval constitutes a new primary electrical abnormality associated with syncope and/or sudden cardiac death. We report on the initial use of implantable cardioverter defibrillator (ICD) therapy in patients with inherited short QT interval and discuss sensing abnormalities and detection issues. METHODS AND RESULTS: In five ...
Yamaguchi Masato - - 2003
QT dispersion (QTD) on 12-lead ECGs has been proposed as a marker of malignant ventricular tachyarrhythmias, and increased QTD has been reported in long QT syndrome (LQTS). On the other hand, it has been demonstrated that transmural dispersion is associated with ventricular tachyarrhythmias in an experimental model. However, the precise ...
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