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Hu Xiao Sheng - - 2006
AIMS: The purpose of this study was to determine the relationship between pulmonary vein (PV) electrical activation during atrial fibrillation (AF) and after cardioversion into sinus rhythm. METHODS AND RESULTS: Electrograms were recorded using a circular mapping catheter during AF and after cardioversion in 53 PVs from 41 patients. Two ...
Ohmuro Junko - - 2006
Flagellar beating of hyperactivated golden hamster spermatozoa was analyzed in detail using digital image analysis and was compared to that of nonhyperactivated (activated) spermatozoa in order to understand the change in flagellar beating during hyperactivation and the active microtubule sliding that brought about the change in flagellar beating. Hyperactivated flagellar ...
Schmitt Michael W - - 2007
Electrocardiogram (ECG) QT interval prolongation produced by drugs in certain animal models is currently believed to be predictive of cardiac proarrhythmic effects in humans. For this reason, nonclinical assessment of the effects of novel drugs on cardiac repolarization is a regulatory prerequisite for progressing such agents to clinical evaluation. The ...
Hekkala Anna-Mari - - 2006
BACKGROUND: Accurate measurement of the QT interval is important for diagnosing long QT syndrome (LQTS), and in research on determinants of ventricular repolarization time. We tested automatic analysis of QT intervals from multiple ECG leads on chest. METHODS: Eleven healthy volunteers and 10 genotyped LQTS patients were tested at rest ...
Lewis M J - - 2006
The aim of the present study was to quantify the variability of electrocardiographic QT and RR intervals during rest and dynamic physical exercise, and to interpret these variabilities in terms of relative autonomic modulation of the atrial and ventricular myocardium. We also sought to characterize the relationships between QT, heart ...
Newbold Paul - - 2007
We sought to investigate subject specific QT interval correction factors (SSCF) determined at rest and after exercise and to determine the validity of these factors after the administration of a probe drug known to increase heart rate without directly affecting cardiac repolarization. Thirty-two healthy volunteers underwent graded exercise, multiple recordings ...
Knollmann Björn C - - 2007
Transgenic mice have been increasingly utilized to investigate the molecular mechanisms of cardiac arrhythmias, yet the rate dependence of the murine action potential duration and the electrical restitution curve (ERC) remain undefined. In the present study, 21 isolated, Langendorff-perfused, and atrioventricular node-ablated mouse hearts were studied. Left ventricular and left ...
Sasaki Osamu - - 2006
A young woman presented with takotsubo cardiomyopathy after a syncopal attack caused by torsades de pointes. Two-dimensional echocardiography on admission showed left ventricular apical akinesis (ballooning) and basal hyperkinesis, compatible with takotsubo cardiomyopathy. This gradually normalized in 2 months. ECG on admission showed remarkable QT prolongation, U waves, and negative ...
Tucker Ross - - 2006
PURPOSE: To analyze pacing strategies employed during men's world-record performances for 800-m, 5000-m, and 10,000-m races. METHODS: In the 800-m event, lap times were analyzed for 26 world-record performances from 1912 to 1997. In the 5000-m and 10,000-m events, times for each kilometer were analyzed for 32 (1922 to 2004) ...
Baspinar Osman - - 2007
Twelve children with a VDD/DDD pacemaker during 100, 125, 150, 200 ms atrioventricular delays and VVIR pacing, cardiac index was measured at rest and evaluated by endurance time during exercise stress test. The optimal atrioventricular delay, which provides highest cardiac index, was 100 ms in three, 125 ms in two, ...
Perhonen Merja A - - 2006
AIMS: High-intensity physical exercise and competitive sports have been traditionally avoided in long QT syndrome. However, endurance training increases vagal activity and thus may improve cardiac electrical stability in healthy subjects. We hypothesized that controlled submaximal endurance training would not adversely affect ventricular repolarization in asymptomatic carriers of a KCNQ1 ...
Earley Mark J - - 2006
OBJECTIVES: The aim of this study was to validate noncontact mapping (NCM) in the left atrium (LA) during sinus rhythm and atrial fibrillation (AF). BACKGROUND: Understanding the mechanisms of AF is crucial to the development of novel and effective treatments. Noncontact mapping records global electrical activation simultaneously and therefore has ...
Iakobishvili Z - - 2006
AIM: The occurrence of accelerated junctional rhythm during radiofrequency energy delivery at the region of the slow pathway is a well-recognized marker of successful treatment of atrioventricular nodal re-entry tachycardia (AVNRT). Our aim was to evaluate if the quantity and duration of accelerated junctional rhythm during radiofrequency ablation of the ...
Wess Gerhard - - 2006
We reviewed the indications for age and breeds of dogs who received transvenous endocardial artificial pacemaker (AP) implantation (n = 105) and complications and survival thereafter at a single institution over a 6-year period. A third-degree atrioventricular (AV) block (59%) and sick sinus syndrome (SSS; 27%) were the most common ...
Schuettpelz Eric - - 2006
The rate of molecular evolution is not constant across the Tree of Life. Characterizing rate discrepancies and evaluating the relative roles of time and rate along branches through the past are both critical to a full understanding of evolutionary history. In this study, we explore the interactions of time and ...
Krummen David E - - 2006
Periodic electrocardiographic RR intervals are often used to separate atrial flutter (AFl) from atrial fibrillation (AF), but have not yet been validated. We hypothesized that irregularly irregular electrocardiographic RR intervals poorly identify AF from AFl, and that atrial wavefront regularity affects variability in atrioventricular conduction. We studied the electrocardiographic RR ...
Kazemi Babak - - 2006
High-degree atrioventricular (AV) block during AV nodal re-entrant tachycardia (AVNRT) is considered a rare phenomenon. A patient with slow-fast AVNRT and transient high-degree AV block is presented. Electrophysiological manoeuvres identified the site of block in the lower common pathway of the AV node. This arrhythmia was rendered non-inducible after slow ...
Kligfield Paul - - 2006
QT-interval measurements have clinical importance for the electrocardiographic recognition of congenital and acquired heart disease and as markers of arrhythmogenic risk during drug therapy, but software algorithms for the automated measurement of electrocardiographic durations differ among manufacturers and evolve within manufacturers. To compare automated QT-interval measurements, simultaneous paired electrocardiograms were ...
Otomo Kiyoshi - - 2006
Focal left atrial tachycardias (AT) originating from the mitral annulus-aorta (MA-Ao) junction are rare and their mechanisms are unclear. We report a 35-year-old male with successful ablation of an exercise-induced focal AT due to triggered activity originating from the MA-Ao junction. The AT occurred spontaneously during treadmill exercise testing and ...
Eberhardt Frank - - 2006
INTRODUCTION: Sophisticated monitoring of atrial activity is a prerequisite for modern pacemaker therapy. Ideally, near-fields and ventricular far-fields ought to be distinguished by beat-to-beat template analysis of the atrial signal. A prerequisite is that atrial signals are stable under different conditions. METHODS AND RESULTS: A Matlab routine was developed to ...
Williams Gregory C - - 2006
INTRODUCTION: The effect of standing on heart rate and QT is well known but its impact on QTc is less clear. METHODS: Serial supine and standing 12-lead ECGs (seven pairs each day) were recorded from 54 healthy volunteers each day of a three-day period. ECGs were captured digitally and over-read ...
van den Berg Maarten P - - 2006
BACKGROUND: In patients with long-QT syndrome type 3 (LQT3), symptoms occur particularly at rest or during sleep. As to the underlying mechanism, excessive prolongation of the QT interval at slow heart rates probably plays a role. OBJECTIVES: The purpose of the present study was to investigate QT interval prolongation unrelated ...
Nakamoto Tomoko - - 2006
We have recently reported that the atrioventricular (AV) nodal mechanism functions to cancel fluctuation in the atrial excitation interval during a stair-stepping exercise. However, it remained unknown at which level of heart rate (HR) this mechanism started to operate and whether fluctuation in the interval might influence AV conduction over ...
Schmidt Matthias - - 2006
OBJECTIVE: There is controversy whether the measurement of QT dispersion might provide information about the presence and extent of ischaemic myocardium. It was the aim to analyse the diagnostic value of QT dispersion for the detection of myocardial ischaemia in comparison to Tl-201-SPECT. PATIENTS AND METHODS: 100 patients were randomly ...
Lewis M J - - 2006
The post-exercise electrocardiographic QT interval is shortened relative to that at similar heart rates during exercise or pre-exercise rest. This lag in QT adaptation to the recovering heart rate is described as "hysteresis". No previous studies have quantified the influence of ECG electrode placement on hysteresis following physical exercise. Six ...
Grygier M - - 2006
BACKGROUND: There are no reliable non-invasive markers of restenosis after percutaneous transluminal coronary angioplasty (PTCA). The aim of our study was to measure changes in QT interval dispersion after PTCA and to determine whether restenosis subsequently affects QT interval dispersion. METHODS AND RESULTS: Fifty-six consecutive patients - 41 men and ...
St Clair Gibson Alan - - 2006
This article examines how pacing strategies during exercise are controlled by information processing between the brain and peripheral physiological systems. It is suggested that, although several different pacing strategies can be used by athletes for events of different distance or duration, the underlying principle of how these different overall pacing ...
Wu Runze - - 2006
INTRODUCTION: Investigation of relationship between diastolic-interval (DI)-dependent restitution of action potential duration (APD) and alternans of APD has produced conflicting results. We used a novel pacing protocol to determine the role of restitution in alternans by minimizing changes in DI preceding each activation. METHODS: Transmembrane potentials were recorded from right ...
Melzer C - - 2006
AIMS: We prospectively evaluated results from cardiopulmonary exercise testing for chronotropic incompetence (CI) in a cohort of 292 pacemaker patients. In addition, we evaluated comorbidity and antiarrhythmic patient data as indicators of CI. METHODS AND RESULTS: On the basis of exercise stress testing and application of the definition of CI ...
Molnar Janos - - 2006
BACKGROUND: Drug induced QT prolongation may precipitate life threatening cardiac arrhythmias. Evaluation of the QT prolonging effect of new pharmaceutical agents in a 'thorough QT/QTc study' is being mandated by FDA. The purpose of this study was to evaluate an automated 12-lead digital Holter system for a thorough QT/QTc study. ...
Ono Chikako - - 2006
At the time of the first visit to our clinic, an electrocardiographic examination of a 73-year-old female patient revealed ventricular premature contractions (VPCs) with variable coupling intervals that were diagnosed as parasystole. Characteristically many of the parasystoles had no sinus contractions between two consecutive VPCs, which we referred to as ...
Kumagai Koichiro - - 2005
BACKGROUND: Pulmonary vein (PV) isolation using a circular catheter (CC) creates an entrance block from the left atrium (LA) to PV to eliminate paroxysmal atrial fibrillation (PAF). We describe a new approach for PV isolation during distal PV pacing using a basket catheter (BC). The purpose of the present study ...
Chen Annabel A - - 2006
Acute and subacute complete heart block (CHB) are sequelae of alcohol septal ablation (ASA) for obstructive hypertrophic cardiomyopathy. Temporary pacemakers are routinely placed at the time of ASA, but there are no widely accepted guidelines for their management. This study examined acute predictors of subacute CHB in 52 consecutive ASA ...
Walker Bruce D - - 2005
OBJECTIVES: The aim of this study was to develop a diagnostic technique to detect latent long QT syndrome. BACKGROUND: Asymptomatic patients with genetically diagnosed long QT syndrome (LQTS) may have a normal resting QT interval, yet remain at risk for cardiac events. We hypothesized that the QT response during a ...
Kaufman Elizabeth S - - 2005
Patients with congenital long QT syndrome due to potassium channel mutations (LQT1 and LQT2) may elude diagnosis due to normal electrocardiographic findings at rest, yet remain at risk of sudden death during bradycardia or sympathetic stimulation. To test the hypothesis that autonomic maneuvers can unmask long QT syndrome in genetically ...
Brembilla-Perrot Béatrice - - 2005
BACKGROUND: Isoprenaline (isoproterenol) is a beta-adrenergic drug, used to increase the heart rate and, during electrophysiological study, to facilitate the induction of supraventricular (SVT) and ventricular tachycardias (VT). Decrease in heart rate during isoprenaline infusion is a rare phenomenon. The purpose of the study was to evaluate the incidence, the ...
Leftheriotis Dionyssios I - - 2005
AIMS: Stimulation of atrial 5-HT4 receptors is associated with arrhythmias. Their blockade prolongs atrial effective refractory period (ERP), following short runs of atrial fibrillation (AF). The role of 5-HT4 receptors during longer periods of AF is unknown. In this study, we investigated the effects of the selective 5-HT4 receptor stimulation ...
Tomczak Corey R - - 2005
OBJECTIVE: To elucidate the effects of atrioventricular (AV) dyssynchrony on phase I and phase II oxygen uptake (V(O2)) kinetics in chronotropically competent pacemaker patients during exercise of an intensity comparable to activities of daily living. DESIGN: Blinded patients completed sub-ventilatory threshold (VT) work rate (WR) cycle ergometry exercise in random ...
Pappas Loukas K - - 2006
In this report we describe the case of a 56-year-old woman with normal 1:1 AV conduction at rest who developed 2:1 AV block during treadmill exercise testing. Electrophysiological study documented 2:1 AV block proximal to the His bundle with reappearance of 1:1 AV conduction at a higher pacing atrial rate. ...
Surmely Jean-François - - 2005
A 19-year-old woman presented with decreased exercise tolerance 3 years after orthotopic heart transplantation. Exercise capacity was severely reduced, with a maximal workload of 84 W, corresponding to 56% of the predicted value. After exclusion of other causes, insufficient heart rate response to exercise was considered as the major contributor ...
Li Cuilan - - 2005
The primary aim of the present study was to investigate the short-term effects of surgical left cardiac sympathetic denervation (LCSD) on the QT interval and heart rate in patients with congenital long QT syndrome (LQTS). Left cardiac sympathetic denervation was performed in five LQTS patients who had a history of ...
Tsukahara Kimio - - 2005
Congenital long QT syndrome (LQTS) is known to be a critical syndrome associated with a bizarre T wave, prolonged QT interval, and ventricular arrhythmias and is followed by syncope and/or sudden death. Body surface mapping, especially QRST isointegral departure mapping, was used after exercise to assess exercise-induced repolarization changes in ...
Ducroq Joffrey - - 2005
INTRODUCTION: Ziprasidone, an atypical antipsychotic has been shown to be devoid of cardiac adverse effects in spite of its propensity to prolong the QT-interval via a hERG current inhibition. However, the effects of ziprasidone on the action potential (AP) parameters have not been published yet. Moreover, very little information is ...
Takagi Yasuhiro - - 2005
This case report describes a 37-year-old man with manifest atriofascicular and fasciculoventricular connections who developed complete atrioventricular block. After resumption of 1:1 atrioventricular conduction, an electrophysiological study was conducted. During sinus rhythm, manifest ventricular preexcitation was observed and the AH and HV intervals were 80 msec and 50 msec, respectively. ...
Rubio Jose Amador - - 2005
A patient who had been previously diagnosed with congenital complete atrioventricular block (CCAVB) twenty years ago developed atrioventricular (AV) conduction through an accessory pathway (AP). With enhanced sympathetic tone (exercise, isoproterenol), 1:1 conduction down the AP occurred. An electrophysiologic study confirmed a suprahissian AV block and the presence of an ...
Patton Kristen K KK Cardiac Arrhythmia Service and Cardiovascular Research Center, Massachusetts General Hospital, Boston, MA 02114, - - 2005
In the face of increasing evidence of underlying genetic heterogeneity for lone atrial fibrillation (LAF), we undertook a clinical analysis of subjects to identify the phenotypic subsets of this arrhythmia. We evaluated serial patients who presented with LAF between July 5, 2001 and December 19, 2003. Subjects underwent a standardized ...
Lüthje L - - 2005
BACKGROUND: Inappropriate ICD therapy for supraventricular tachycardia (SVT) remains a significant problem. A morphology-based algorithm (Wavelet) compares baseline and tachycardia electrograms (EGM). For this analysis different EGM sources can be programmed. This study evaluates the performance of Wavelet using two different EGM configurations (SVC-Can and RV-Can) for the detection of ...
Scharf Christoph - - 2005
BACKGROUND: During cardiac resynchronization therapy (CRT), cardiac performance is dependent on an optimized atrioventricular delay (AVD). However, the optimal AVD at different heart rates has not been defined yet during CRT. METHOD: The effects of an increase in heart rate by pacing or physical exercise on optimal AVD were studied ...
Castellanos Agustin - - 2005
This article deals with the tracings of a patient having episodes of atrial flutter with 4:1 atrioventricular (AV) block increasing to 8:1 AV block. This phenomenon was attributed to the coexistence of 3-level block due to transverse dissociation with 2:1 AV block in the most proximal level, or first level ...
Li Jian - - 2005
Although after pacing animal and human studies have demonstrated a rate-dependent effect of sotalol on ventricular repolarization, there is little information on the effects of sotalol on ventricular repolarization during exercise. This study attempted to show the effects of sotalol on ventricular repolarization during physiological exercise. Thirty-one healthy volunteers (18 ...
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