Search Results
Results 351 - 400 of 1467
< 3 4 5 6 7 8 9 10 11 12 13 >
Henriques J J CISUC, Departamento de Engenharia Informática, Universidade de Coimbra, Coimbra. - - 2007
An integrated framework for ventricular arrhythmias (VA) assessment, composed of two levels, is proposed in this work. The first level consists of four independent neural networks (NN), designed for specific detection tasks: signal quality, premature ventricular contractions (PVC), ventricular tachycardia (VT) and ventricular fibrillation (VF). Time and frequency domain features, ...
Baumert Mathias - - 2007
Ventricular tachycardia (VT) provokes sudden cardiac death (SCD), which is a major cause of mortality in developed countries. Implantable cardioverter-defibrillators (ICDs) are an efficient therapy for SCD prevention. In this study we analyze heart rate variability (HRV) in data stored by ICDs. In 29 patients exhibiting VT episodes, the last ...
Furukawa Tetsuo - - 2006
Ventricular fibrillation (VF) is most frequent in the very early phase in acute coronary occlusion, and is triggered by the re-entrant mechanism in this phase. An inhomogeneous conduction in the ischemic myocardium would be substrates for re-entry. The aim of this study was to examine the relationship between the severity ...
Bella Paolo Della - - 2006
In recent years several trials demonstrated the efficacy of implantable cardioverter-defibrillation (ICD) therapy in reducing cardiac and total mortality in patients affected by rapid ventricular tachycardia (VT) and/or ventricular fibrillation. Nevertheless, ICD do not prevent arrhythmia recurrences, thus being a palliative and not a curative treatment modality. The tolerance to ...
Bogun Frank - - 2006
OBJECTIVES: The objective of this study was to assess the role of Purkinje fibers in monomorphic, post-infarction ventricular tachycardia (VT). BACKGROUND: Ventricular fibrillation and polymorphic VT in the setting of acute myocardial infarction (MI) may be triggered by ectopy arising from Purkinje fibers. METHODS: From among a group of 81 ...
Corbisiero Raffaele - - 2006
AIMS: Interval- and morphology-based algorithms have been used in modern implantable cardioverter defibrillators (ICDs) to discriminate supraventricular tachycardia (SVT) from other rhythms. A newly developed ICD discrimination algorithm, Rhythm ID (Guidant Corporation, St Paul, MN, USA), uses both interval-based metrics and an electrogram vector timing and correlation (VTC) algorithm in ...
Selvaraj Raja J - - 2007
Steep action potential duration (APD) restitution slopes (>1) and spatial APD restitution heterogeneity provide the substrate for ventricular fibrillation in computational models and experimental studies. Their relationship to ventricular arrhythmia vulnerability in human cardiomyopathy has not been defined. Patients with cardiomyopathy [left ventricular (LV) ejection fraction <40%] and no history ...
Rogers Jack M - - 2007
During ventricular fibrillation (VF), activation waves are fragmented and the heart cannot contract synchronously. It has been proposed that VF waves emanate from stable sources ("mother rotors"). Previously, we used new optical mapping technology to image VF wavefronts from nearly the entire epicardial surface of six isolated swine hearts. We ...
Noujaim Sami F - - 2007
Previous studies have suggested an important role for the inward rectifier K+ current (I K1) in stabilizing rotors responsible for ventricular tachycardia (VT) and fibrillation (VF). To test this hypothesis, we used a line of transgenic mice (TG) overexpressing Kir 2.1-green fluorescent protein (GFP) fusion protein in a cardiac-specific manner. ...
MacGregor John F - - 2006
BACKGROUND: Despite the wide use of antitachycardia pacing (ATP) in patients with implantable cardioverter defibrillators (ICDs), predictors of ATP success remain poorly understood. We hypothesize that the degree of sympathoexcitation, as measured by the sinus cycle length (SCL) shortening during ventricular tachycardia (VT), is a predictor of ATP success. METHODS ...
Assomull Ravi G - - 2006
OBJECTIVES: We studied the prognostic implications of midwall fibrosis in dilated cardiomyopathy (DCM) in a prospective longitudinal study. BACKGROUND: Risk stratification of patients with nonischemic DCM in the era of device implantation is problematic. Approximately 30% of patients with DCM have midwall fibrosis as detected by late gadolinium-enhancement (LGE) cardiovascular ...
Hori Yasuhiko - - 2007
We report here a 75-year-old male with hypertrophic obstructive cardiomyopathy of de novo sustained monomorphic ventricular tachycardia (VT) after successful percutaneous transluminal alcohol septal myocardial ablation (PTSMA). In this case history, the necrotic induced by the PTSMA procedure might represent a region of slow conduction that is a circuit of ...
Hohnloser Stefan H - - 2006
AIMS: The purpose of this study was to assess the incidence, features, and clinical sequelae of 'electrical storm' (ES). METHODS AND RESULTS: This study is a prospectively designed secondary analysis of SHIELD; a randomized trial of azimilide for suppression of ventricular tachycardia/fibrillation (VT/VF) leading to implanted cardioverter defibrillator (ICD) therapies. ...
McLachlan Craig S - - 2007
OBJECTIVE: Ventricular tachycardia (VT), occurring late after myocardial infarction, is an important cause of sudden death. Animal models are useful for the investigation of this arrhythmia. The aim of this study is to develop and characterize a model of late postinfarction monomorphic VT in the rabbit. METHODS AND RESULTS: Myocardial ...
Stokoe Kate S KS Physiological Laboratory, University of Cambridge, Downing Street, Cambridge CB2 3EG, - - 2007
Long QT3 (LQT3) syndrome is associated with incomplete Na+ channel inactivation, abnormal repolarization kinetics and prolonged cardiac action potential duration (APD). Electrophysiological effects of flecainide and quinidine were compared in Langendorff-perfused wild-type (WT), and genetically modified (Scn5a+/Delta) murine hearts modelling LQT3. Extra stimuli (S2) following trains of pacing stimuli (S1) ...
Acosta Helbert - - 2006
This is a case report of a male patient with nonischemic cardiomyopathy who had severely depressed left ventricular systolic function and functional class III congestive heart failure (CHF). He also had left bundle branch block (LBBB) and recurrent ventricular tachycardia (VT). Though the patient's CFH functional class improved after implantation ...
Byrd Israel A - - 2006
OBJECTIVES: Interactions between paced wavefronts and monomorphic ventricular tachycardia (VT) dictate antitachycardia pacing outcomes. We used optical mapping to assess those interactions during single and dual site pacing of rabbit ventricular epicardium. METHODS AND RESULTS: Monomorphic VTs were initiated in six isolated rabbit hearts that were endocardially cryoablated to limit ...
Brodsky Michael A - - 2006
BACKGROUND: In survivors of life-threatening ventricular tachycardia (VT), a history of CHF (HxCHF) before the VT episode may provide different prognostic information than their measured left ventricular ejection fraction (LVEF). METHODS: We evaluated outcomes from patients in the AVID study. Patients were included in the study if they presented with ...
Tsuchiya Takeshi - - 2007
We describe a 17-year-old woman with a structurally normal heart in which short-sustained rapid polymorphic ventricular tachycardias (VTs) were repetitively provoked by an antiarrhythmic agent, pilsicainide, and spontaneously changed into a sustained monomorphic VT. The latter was terminated by verapamil and was shown to be due to reentry by entrainment. ...
Ashikaga Keiichi - - 2006
Idiopathic VT Originating from Posteroseptal Mitral Annulus We describe a 71-year-old man with a ventricular tachycardia (VT) originating from the mitral annulus. A sustained VT was induced by exercise or an isoproterenol administration, but not by pacing. Frequent premature ventricular contractions (PVCs) with the same QRS as the VT were ...
Lim Hong Euy - - 2006
We describe a case of primary lung cancer with myocardial metastasis, documented with electrocardiogram (ECG) mimicking myocardial ischemia and manifesting VT. Metastatic tumor to the myocardium proper is uncommon and difficult to diagnose because of nonspecific signs and symptoms. We observed such ECG changes in this case were initially misinterpreted ...
Yue Yuankun - - 2006
PURPOSE: Ischemic heart disease carries an increased risk of malignant ventricular tachycardia (VT), fibrillation (VF), and sudden cardiac death. Protein kinase C (PKC) epsilon activation has been shown to improve the hemodynamics in hearts subjected to ischemia/reperfusion. However, very little is known about the role of epsilon PKC in reperfusion ...
Pizzuto Matthew F - - 2006
BACKGROUND: Hibernating myocardium develops inhomogeneity in myocardial sympathetic innervation with spontaneous sudden cardiac death (SCD) because of ventricular fibrillation (VF). The triggers and prodromal arrhythmias initiating SCD in this substrate are unknown. METHODS: Swine chronically instrumented with a proximal left anterior descending coronary artery stenosis underwent placement of an implantable ...
Brembilla-Perrot B - - 2006
INTRODUCTION: Supraventricular tachyarrhythmias (SVTA) are an accepted cause of cardiac arrest in patients with Wolff-Parkinson-White syndrome (WPW) and hypertrophic cardiomyopathy but their participation in other conditions is less well understood. The purpose of the study was to examine the role of SVTA in sudden cardiac arrest (SCA) by comprehensive evaluation ...
Nash Martyn P - - 2006
BACKGROUND: The mechanisms that sustain ventricular fibrillation (VF) in the human heart remain unclear. Experimental models have demonstrated either a periodic source (mother rotor) or multiple wavelets as the mechanism underlying VF. The aim of this study was to map electrical activity from the entire ventricular epicardium of human hearts ...
Li Yi-gang - - 2006
BACKGROUND: Recently, substrate mapping (SM) has been described to facilitate catheter ablation of stable and unstable ventricular tachycardia (VT) after myocardial infarction. However, SM is time consuming with potential disadvantages of multiple ablation lines such as impairment of ventricular function or proarrhythmia. The aim of the present study was to ...
Bazan Victor - - 2006
BACKGROUND: Usefulness of 12-lead ECG for predicting an epicardial origin for ventricular tachycardia (VT) arising from the right ventricle (RV) has not been assessed. An epicardial approach is sometimes warranted to eliminate RV VT. OBJECTIVES: The purpose of this study was investigate the hypothesis that specific ECG features identify an ...
Zhou Jing - - 2006
BACKGROUND: The mechanism(s) whereby a discrete area of myocardium in the RVOT becomes arrhythmogenic remains unknown. METHODS: In 13 dogs, a circular catheter was placed in the proximal pulmonary artery (PA) to contact the endovascular circumference of the PA. A 50-msec train of high-frequency stimulation (HFS, 200 Hz), coupled to ...
Watanabe Mari A - - 2006
INTRODUCTION: The aim of this study was to see whether heart rate turbulence (HRT) parameters change preceding imminent ventricular tachyarrhythmias (VT/VF). METHODS AND RESULTS: The Spontaneous Ventricular Tachyarrhythmia Database (Medtronic Version 1.0) consisting of 83 paired (control and pre-VT/VF) sets of 1,000 RR intervals recorded by the Medtronic Jewel Plus ...
Lim Hong Euy - - 2006
A 52-year-old man presented with sudden onset of palpitations and dizziness. Echocardiogram confirmed the diagnosis of isolated noncompaction of ventricular myocardium with moderated systolic dysfunction, and the electrocardiogram (ECG) revealed ventricular tachycardia (VT), of which the focus seemed to match an area of prominent left ventricular noncompaction on the 12-lead ...
Iwai Sei - - 2006
INTRODUCTION: "Idiopathic" ventricular arrhythmias most often arise from the right ventricular outflow tract (RVOT), although arrhythmias from the left ventricular outflow tract (LVOT) are also observed. While previous work has elucidated the mechanism and electropharmacologic profile of RVOT arrhythmias, it is unclear whether those from the LVOT share these properties. ...
Kumagai Koji - - 2006
We report a case in which endocardial radiofrequency (RF) ablation guided by unipolar intracoronary mapping using a guidewire was an effective therapy for treating VT originating from an epicardial site of the left ventricle. A 55-year-old man with dilated cardiomyopathy was referred for treatment of refractory sustained monomorphic VT. The ...
Folino Antonio Franco - - 2006
AIMS: The aims of our study were to evaluate late potential changes during long-term follow-up in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC) and to correlate these results with echocardiographic findings and sustained ventricular tachycardia (VT) occurrence. METHODS AND RESULTS: We studied 31 patients (22 males and 9 females; mean ...
Nagai Takayuki - - 2006
A 20-year-old man was admitted to our hospital for treatment of verapamil sensitive idiopathic left ventricular tachycardia (ILVT). During the electrophysiologic study (EPS), no sustained ventricular tachycardia (VT) could be induced both at baseline and after infusion of isoproterenol. However, sustained clinical VT could be easily induced with single ventricular ...
Satomi Kazuhiro - - 2006
INTRODUCTION: A reentrant circuit within an area of abnormal myocardium is suspected as the origin of ventricular tachycardia (VT) in patients with arrhythmogenic right ventricular dysplasia (ARVD). OBJECTIVES: To examine the relationship between the reentrant circuits of VT and the abnormal electrograms in ARVD, and to assess the feasibility of ...
Bogun Frank - - 2006
OBJECTIVES: The purpose of this study was to identify ventricular tachycardia (VT) isthmus sites by pace-mapping within scar tissue and to identify electrogram characteristics that are helpful in identifying VT isthmus sites during sinus rhythm (SR). BACKGROUND: Pace-mapping has been used in the scar border zone to identify the exit ...
Hayashi Meiso - - 2006
BACKGROUND: Other than bundle branch reentry and interfascicular reentry, monomorphic postmyocardial infarction (post-MI) reentrant ventricular tachycardia (VT) including the His-Purkinje system has not been reported. Verapamil-sensitive idiopathic left VT includes the left posterior Purkinje fibers but develops in patients without structural heart disease. OBJECTIVES: The purpose of this study was ...
Kay Matthew W - - 2006
During ventricular fibrillation (VF), electrical activation waves are fragmented, and the heart cannot contract in synchrony. It has been proposed that VF waves emanate from stable periodic sources (often called "mother rotors"). The objective of the present study was to determine if stable rotors are consistently present on the epicardial ...
Indik Julia H - - 2006
BACKGROUND: For prolonged VF, perfusion of the myocardium by pre-shock chest compressions can improve myocardial readiness for successful defibrillation. Characteristics of the VF waveform correlate with the duration of VF when there is no structural heart disease. A "smart" automated external defibrillator (AED) could therefore analyze the VF waveform, determine ...
Ainsworth Craig D - - 2006
BACKGROUND: Ventricular tachycardia (VT) resulting from arrhythmogenic right ventricular cardiomyopathy (ARVC) may be difficult to differentiate from idiopathic right ventricular outflow tract (RVOT) VT. OBJECTIVES: The purpose of this study was to investigate the hypothesis that QRS characteristics would be different in ARVC because of altered conduction through abnormal myocardium. ...
Daniels David V - - 2006
BACKGROUND: Despite the success of catheter ablation for treatment of idiopathic ventricular tachycardia (VT), occasional patients have been reported in whom VT could not be ablated from the right or left ventricular endocardium or from the aortic sinus of Valsalva (ASOV). METHODS AND RESULTS: In 12 of 138 patients (9%) ...
Saumarez Richard C RC Department of Cardiology, Papworth Hospital, Cambridge, United Kingdom. - - 2006
LQTS may cause sudden cardiac death (SCD), but the mechanisms linking gene mutations to ventricular fibrillation (VF) are unclear. To determine whether ventricular activation delays in congenital long QT syndrome (LQTS) are associated with VF and to describe these delays clinically by measuring activation through ventricular myocardium after a premature ...
Arya Arash - - 2006
BACKGROUND: Some controversies exist regarding the proper treatment of hemodynamically tolerated and slow ventricular tachycardia (VT). We intended to assess the effect of cycle length of first VT episode on total ventricular arrhythmia burden in a cohort of patients with implantable cardioverter-defibrillator (ICD). METHOD: Between March 2000 and March 2005, ...
Ma Fu-sheng - - 2006
BACKGROUND: Verapamil-sensitive, idiopathic left ventricular tachycardia (ILVT) with right bundle branch block configuration and left-axis deviation is known to be due to re-entry mechanism but the exact nature of reentrant circuit in ILVT is not fully elucidated. Radiofrequency (RF) ablation was applied during ventricular tachycardia (VT) and termination of the ...
Schueller Per Otto - - 2006
INTRODUCTION: Recent experimental and clinical trials have provided evidence that increased duration of right ventricular electrogram in response to premature extrastimuli correlates with the risk of ventricular fibrillation in noncoronary heart disease. The aim of the present study was to investigate the duration of the surface QRS complex at short ...
Fukumoto Yoshihiro - - 2006
We here report a case of 71-year-old man with acute extensive anterior myocardial infarction, who was complicated with ventricular tachycardia (VT) even after successful percutaneous coronary intervention. As intravenous administration of nifekalant terminated VT, we started oral administration of amiodarone (day 1). We gave 400 mg of amiodarone a day ...
Jacobson Jason T - - 2006
BACKGROUND: Conventional mapping of ventricular tachycardia (VT) after myocardial infarction is limited in patients with hemodynamically untolerated or noninducible VT. OBJECTIVES: The purpose of this study was to develop a unique strategy using noncontact unipolar mapping to define infarct substrate and VT circuits. METHODS: Dynamic substrate mapping (DSM) was performed ...
Killingsworth Cheryl R - - 2006
INTRODUCTION: Patients with bradycardia can have severe tachyarrhythmias but it is unclear whether bradycardia alone can induce arrhythmias or whether an additional substrate is necessary. While several animal models of ventricular tachycardia (VT) exist, no model has been reported to mimic the clinical condition of spontaneous VT and sudden cardiac ...
Vyas Anant K - - 2006
OBJECTIVES: We evaluated whether statins have anti-arrhythmic effects by exploring the association of statin use with appropriate implantable cardioverter-defibrillator (ICD) therapy for ventricular tachycardia/ventricular fibrillation (VT/VF) in the Multicenter Automatic Defibrillator Implantation Trial (MADIT)-II. BACKGROUND: A few studies have suggested that lipid-lowering drugs may have anti-arrhythmic effects in patients with ...
Peters Stefan - - 2006
Syncopes appear in 10-20% in arrhythmogenic right ventricular dysplasia-cardiomyopathy (ARVD/C). In the majority of cases sustained or non-sustained monomorphic ventricular tachycardias represent the underlying mechanism of syncope. In other cases the mechanism remains unclear. In 37 patients (23 females, mean age 43.6+/-12.8 years) without detectable and inducible monomorphic ventricular tachycardia, ...
< 3 4 5 6 7 8 9 10 11 12 13 >