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Biermann Jürgen - - 2011
Transgenic rabbits expressing loss-of-function pore mutants of the human gene KCNQ1 (K(v)LQT1-Y315S) have a Long QT-Syndrome 1 (LQT1) phenotype. We evaluated for the first time the effect of nicorandil, an opener of ATP-sensitive potassium channels, and of isoproterenol on cardiac action potential duration and heart rate dependent dispersion of repolarisation ...
Laursen Morten - - 2011
The minipig represents an attractive experimental animal within cardiovascular research due to its extensive similarities to the human heart in terms of anatomy and physiology. Although minipigs have been used for cardiovascular research for decades no thorough characterization of the minipig cardiac electrophysiology has been performed. Therefore, we have for ...
Osadchii Oleg E - - 2010
Hypokalemia is a common biochemical finding in cardiac patients and may represent a side effect of diuretic therapy or result from endogenous activation of renin-angiotensin system and high adrenergic tone. Hypokalemia is independent risk factor contributing to reduced survival of cardiac patients and increased incidence of arrhythmic death. Animal studies ...
Myles Rachel C - - 2010
Although transmural heterogeneity of action potential duration (APD) is established in single cells isolated from different tissue layers, the extent to which it produces transmural gradients of repolarization in electrotonically coupled ventricular myocardium remains controversial. The purpose of this study was to examine the relative contribution of intrinsic cellular gradients ...
Nagaoka Iori - - 2010
We aimed to examine the validity of heart rate (HR) at rest before β-blocker therapy as a risk factor influencing cardiac events (ventricular fibrillation, torsades de pointes, or syncope) in long QT type 2 (LQT2) patients. In 110 genetically confirmed LQT2 patients (45 probands), we examined the significance of variables ...
Chow Sheryl L - - 2012
Contrast media (CM) exposure is associated with a substantial risk of arrhythmias and nephrotoxicity. These adverse effects may be exacerbated in high-risk conditions such as heart failure, although no studies have evaluated newer CM agents in this population. This study evaluated the electrophysiologic and renal effects of two newer CM ...
Haugaa Kristina Hermann - - 2010
BACKGROUND: Long-QT syndrome (LQTS) is characterized by prolonged myocardial action potential duration. The longest action potential duration is reported in the endomyocardium and midmyocardium. Prolonged action potential duration in LQTS may cause prolonged cardiac contraction, which can be assessed by strain echocardiography. We hypothesized that myocardial contraction is most prolonged ...
Saiz Javier - - 2011
Dofetilide is a class-III drug that inhibits the rapid component of the delayed potassium current ( I(Kr)). Experimental studies have shown that the different layers of ventricular muscle present differences in action potential duration (APD) and different responses to class III agents. It has been suggested that it contributes to ...
Childers Rory - - 2010
Torsades de pointes (TdP) is a particular variant of ventricular arrhythmia associated with the long QT syndrome. The background of the latter is essentially 2-fold: patients under treatment with QT-prolonging drugs and subjects with congenital ionopathies. A third category is composed of subjects with both of these backgrounds. The fundamental ...
Hampel Regina - - 2010
Epidemiological studies have shown that ambient particulate matter (PM) and changes in air temperature are associated with increased cardiopulmonary events. We hypothesized that patients with previous myocardial infarction (MI) experience changes in heart rate (HR) and repolarization parameters, such as Bazett-corrected QT interval (QTc), and T-wave amplitude (Tamp), in association ...
Nakamura Hiroko - - 2010
Repolarization of cardiac action potentials is regulated by several types of K(+) currents. The present study examined the presence and functional significance of rapid delayed rectifier (I(Kr)) in left and right atrial myocytes of mouse heart, using whole-cell patch-clamp method. The functional role of ultrarapid delayed rectifier (I(Kur)) in the ...
Zünkler Bernd J - - 2010
Torsades de pointes (TdP) is a life-threatening form of ventricular arrhythmia that occurs under conditions of delayed cardiac repolarization indicated by prolonged QT intervals in ECG recordings. The main mechanism of QT prolongation and TdP is block of the rapid component of the cardiac delayed rectifier K(+) current (I(Kr)), which ...
Peng Yi - - 2011
This study is aimed to investigate the nonlinear dynamic properties of the fluctuations in ventricular repolarization, heart rate and their correlation during acute myocardial ischemia. From 13 ECG records in long-term ST-T database, 170 ischemic episodes were selected with the duration of 34 s to 23 min 18 s, and two 5-min episodes ...
Tisdale James E - - 2011
Progesterone Effects on Ventricular Action Potential. Introduction: Females are at increased risk for torsades de pointes (TdP). Some evidence suggests that progesterone may protect against TdP, but few data exist regarding the effects of progesterone on cardiac repolarization. We determined the effects of progesterone alone and in combination with estradiol on ...
Bacharova Ljuba - - 2010
The contributions of reduced conduction velocity (CV) and prolonged action potential duration (APD) to QT interval prolongation and T wave and T vector loop morphology in left ventricular hypertrophy (LVH) were studied using an analytical computer model. Three types of anatomic LVH were simulated: concentric and eccentric hypertrophy, and left ...
Purtell Kerry - - 2010
Inherited Long QT Syndrome (LQTS), a cardiac arrhythmia that predisposes to the often lethal ventricular fibrillation, is commonly linked to mutations in KCNQ1. The KCNQ1 voltage-gated K(+) channel α subunit passes ventricular myocyte K(+) current that helps bring a timely end to each heart-beat. KCNQ1, like many K(+) channel α ...
Shimizu Wataru - - 2010
This review article sought to describe patterns of repolarization on the surface electrocardiogram in inherited cardiac arrhythmias and to discuss how the knowledge of genetic makeup and cellular data can affect the analysis based on the data derived from the experimental studies using arterially perfused canine ventricular wedge preparations. Molecular ...
Baumert Mathias - - 2011
The aim of this study was to assess cardiac ventricular repolarization in patients with postural tachycardia syndrome (POTS) and further the possible link between ventricular repolarization and sympathetic nervous system activity. We recorded body surface ECGs together with plasma noradrenaline (NE) spillover, and muscle sympathetic nerve activity (MSNA) in twelve ...
Whitted Anthony D - - 2010
Acute stressor states are associated with a homeostatic activation of the hypothalamic-pituitary-adrenal axis. A hyperadrenergic state follows and leads to a dyshomeostasis of several intra- and extracellular cations, including K, Mg, and Ca. Prolongation of myocardial repolarization and corrected QT interval (QTc) of the ECG are useful biomarkers of hypokalemia ...
Hage Fadi G - - 2010
BACKGROUND: Coronary artery disease (CAD) is the predominant cause of sudden cardiac death in the general population, and sudden cardiac death is the leading cause of mortality in end-stage renal disease (ESRD). HYPOTHESIS: QT-interval prolongation is an independent prognosticator in ESRD. METHODS: We reviewed clinical, electrocardiographic, stress test, and coronary ...
Barta Kitti - - 2010
QT interval (QT) and QT dispersion (QTd) are electrocardiograph (ECG) parameters for the evaluation of myocardial repolarization. The inhomogeneity of ventricular repolarization is associated with ventricular arrhythmias. An increased QT, QTd, and increased incidence of nocturnal cardiac rhythm disturbances have been described in patients with obstructive sleep apnea (OSA), while ...
Van den Branden Ben - - 2010
Torsade de pointes (TdP), a ventricular tachycardia (VT) with the peaks of QRS complexes twisting around the iso-electric baseline and progressive amplitude and polarity variations, is mostly associated with long (congenital or acquired) QT syndromes (LQTS) and long coupling intervals of the initiating complex. We describe a patient with variant, ...
Manini Alex F - - 2010
Poisoning is the second leading cause of injury-related fatality in the USA and the leading cause of cardiac arrest in victims under 40 years of age. The study objective was to define the electrocardiographic (ECG) predictors of adverse cardiovascular events (ACVE) complicating suspected acute poisoning (SAP). This was a case-control ...
Panyasing Yaowalak - - 2010
Cardiac hypertrophy is an independent risk factor for torsades de pointes (TdP), a polymorphic ventricular tachycardia that is often drug-induced, that may evolve into ventricular fibrillation and sudden death. Therefore this study was designed to determine if right (RVH), left (LVH), or biventricular (BVH) hypertrophy increases susceptibility to drug-induced TdP. ...
Izumi Daisuke - - 2010
Bepridil (a multiple channel blocker) may markedly prolong the QT interval and induce polymorphic ventricular tachyarrhythmias (VTA). We compared the transmural ventricular repolarization characteristics and inducibility of polymorphic VTA after administration of bepridil versus the pure I(Kr) blocker, E-4031, each administered to five open-chest dogs. We used plunge needle electrode ...
Nordin C - - 2010
Recent clinical studies show that hypoglycaemia is associated with increased risk of death, especially in patients with coronary artery disease or acute myocardial infarction. This paper reviews data from cellular and clinical research supporting the hypothesis that acute hypoglycaemia increases the risk of malignant ventricular arrhythmias and death in patients ...
Surges Rainer - - 2010
Sudden unexpected death in epilepsy (SUDEP) is probably caused by periictal cardiorespiratory alterations such as central apnea, bradyarrhythmia, and neurogenic pulmonary edema. These alterations may occur in people with epilepsy and vary in duration and severity. Seizure-related ventricular tachyarrhythmias have also been hypothesized to be involved in SUDEP, but compelling ...
Liao Duanping - - 2010
The mechanisms for the relationship between particulate pollution and cardiac disease are not fully understood. We examined the effects and time course of exposure to fine particulate matter < or = 2.5 microm in aerodynamic diameter (PM(2.5)) on ventricular repolarization of 106 nonsmoking adults who were living in communities in ...
Akar F G - - 2010
Pathophysiological remodeling of cardiac function occurs at multiple levels, spanning the spectrum from molecular and sub-cellular changes to those occurring at the organ-system levels. Of key importance to arrhythmias are changes in the electrophysiological substrate at the tissue level. In this manuscript, we provide an overview of mechanisms by which ...
Occhetta Eraldo - - 2010
AIMS: The evoked QT interval can be detected beat by beat through an implanted pacing system. The correlation between the right ventricular paced QT interval and the left ventricular systolic interval is not known. The aim of our study was to collect data on the correlation between QT and systolic ...
Chiale Pablo A - - 2010
AIMS: "Cardiac memory" refers to abnormal T waves (TW) appearing after transient periods of altered ventricular depolarization. The aim of the study was to test the hypothesis that in the presence of abnormal TW, short periods of tailored ventricular pacing (VP) can be followed by normalization of ventricular repolarization. METHODS: ...
Ohkubo Kimie - - 2011
The long QT syndrome (LQTS) is occasionally complicated by impaired atrioventricular (AV) conduction. This form of LQTS can manifest before birth or during neonatal life, and no previous report has demonstrated LQTS complicated by impaired AV conduction in elderly patient. This case report describes an elderly patient with an acquired ...
Yu Fei F Department of Biomedical Engineering and Division of Cardiovascular Medicine, University of Southern California, Los Angeles, CA 90089, - - 2010
Zebrafish is an emerging model system for cardiac conduction and regeneration. Zebrafish heart regenerates after 20% ventricular resection within 60 days. Whether cardiac conduction phenotype correlated with cardiomyocyte regeneration remained undefined. Longitudinal monitoring of the adult zebrafish heart (n = 12) was performed in terms of atrial contraction (PR intervals), ...
McKechnie Kyle - - 2010
PURPOSE: To describe a case of ventricular tachycardia after co-administration of ondansetron and dimenhydrinate to a child with occult congenital QT prolongation. CLINICAL FEATURES: A previously healthy 11-yr-old girl presented for surgical excision of a thyroglossal duct cyst under general anesthesia. Induction and maintenance of anesthesia were unremarkable, and the ...
Mozos Ioana - - 2010
Chronic myocardial infarction (CMI) may create, due to structural heterogeneity, abnormal electrophysiological substrates which trigger re-entrant life-threatening ventricular arrhythmias. METHODS: Electrical instability is assessed using body surface mapping (BSM) [multipolar isointegral QRST maps (mp I(QRST))] and 12-lead ECG (QT dispersion: QTd: the difference between maximal and minimal QT interval). The ...
Kijtawornrat Anusak - - 2010
The short QT syndrome (SQTS) is characterized by a short QT interval resulting from accelerated ventricular repolarization, and may be associated with ventricular fibrillation but not torsades de pointes. There are abundant data on the adverse effects of long QT, but knowledge of SQTS is sparse. The aim of this ...
Hakim Parvez - - 2010
1. Flecainide and quinidine exert contrasting pro-arrhythmic and anti-arrhythmic effects in mouse hearts containing the loss-of-function, Scn5a(+/-), and the gain-of-function, Scn5a(+/DeltaKPQ), mutations in their sodium channel alpha-subunits. 2. The following properties were accordingly compared in wild-type and Scn3b(-/-) hearts modelling modifications in the beta-subunit, before and after introduction of either ...
Roche Michel - - 2010
Delayed ventricular repolarization is associated with rare, but often fatal, polymorphic tachyarrhythmias named Torsades de Pointes. ICH S7B guideline recommends an integrated approach for cardiovascular preclinical evaluation of new drug candidates, including action potential assays (as a Purkinje fiber test) but also proarrhythmia models. The aim of this preliminary study ...
Glukhov Alexey V AV Department of Biomedical Engineering, Washington University, St Louis, MO 63130, - - 2010
Transmural dispersion of repolarization has been shown to play a role in the genesis of ventricular tachycardia and fibrillation in different animal models of heart failure (HF). Heterogeneous changes of repolarization within the midmyocardial population of ventricular cells have been considered an important contributor to the HF phenotype. However, there ...
Watanabe Hiroshi - - 2010
Short QT syndrome (SQTS) is characterized by an abnormally short QT interval and sudden death. Due to the limited number of cases, the characteristics of SQTS are not well understood. It has been reported recently that early repolarization is associated with idiopathic ventricular fibrillation and the QT interval is short ...
Zimerman L I - - 2010
The cardiovascular electrophysiologic basis for the action of pyridostigmine, an acetylcholinesterase inhibitor, has not been investigated. The objective of the present study was to determine the cardiac electrophysiologic effects of a single dose of pyridostigmine bromide in an open-label, quasi-experimental protocol. Fifteen patients who had been indicated for diagnostic cardiac ...
Holm Hilma - - 2010
Electrocardiographic measures are indicative of the function of the cardiac conduction system. To search for sequence variants that modulate heart rate, PR interval and QRS duration in individuals of European descent, we performed a genome-wide association study in approximately 10,000 individuals and followed up the top signals in an additional ...
Nahshoni Eitan - - 2010
In the present, preliminary, naturalistic study, cardiac ventricular late potentials (LPs), were measured in 33 physically healthy schizophrenia patients (13 - females and 26 - males, age - 45.5+/-8.8years) maintained on typical and atypical antipsychotic agents. These LPs represent delayed ventricular activation that might predispose to fatal ventricular arrhythmias and ...
Nakajima Tadashi - - 2010
The postpartum period is associated with an increased risk of fatal ventricular tachyarrhythmias in patients with congenital long QT syndrome (LQTS). We describe a 20-year-old female with LQTS who experienced aborted cardiac arrest during the postpartum period. Genetic screening identified a KCNE1 D85N variant, which has been reported to be ...
Makarov Leonid - - 2010
BACKGROUND: Twenty-four hour ambulatory electrocardiogram (AECG) monitoring is an established technique for integrated assessment of heart rhythm; however, comprehensive description of serial changes in cardiac electrophysiology over the first days of life in humans is lacking. The aim of this study was to determine the patterns of circadian heart rhythm ...
Kanu Uche - - 2010
Cardiac action potential duration alternans is characterized by a beat-to-beat alternation in action potential waveform. Its presence has been putatively linked to the onset of lethal cardiac arrhythmias. Previous studies, which have been limited to cardiac Purkinje fibers, have shown that closed-loop alternans control techniques, which apply a succession of ...
Walfridsson Håkan - - 2010
BACKGROUND: AZD0837 is an investigational oral anticoagulant that is bioconverted to its active form, AR-H067637, a selective direct thrombin inhibitor. OBJECTIVES: The objectives of the present study were to investigate if there are any clinically relevant adverse effects of intravenous AZD0837 on cardiac conduction, refractoriness and repolarization, and to study ...
Kozmann Gy?rgy - - 2010
To improve malignant arrhythmia risk stratification, the causal and random components of spatiotemporal dynamics of heart rate (RR distances), ventricular depolarization sequence, and repolarization disparity were studied based on body surface potential map records taken for 5 minutes, in resting, supine position on 14 healthy subjects (age range, 20-65 years) ...
Watanabe Ichiro - - 2010
A 46-year-old man with type II Brugada electrocardiogram pattern changed to a type I Brugada type electrocardiogram pattern by class I antiarrhythmic drug (pilsicainide) underwent electrophysiologic study. Ventricular fibrillation was induced by double extrastimuli from the right ventricular (RV) apex. Monophasic action potentials (MAPs) were then recorded from the high ...
Fossa Anthony A - - 2010
Historically, the heart rate corrected QT (QTc) interval has been the standard method to assess for impaired ventricular repolarization, particularly for drug development. However, QTc does not reflect changes in autonomic state or QT-RR hysteresis which can also affect the interpretation of arrhythmogenic risk. With the advent of more accurate ...
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