Search Results
Results 751 - 800 of 1466
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Shimoike E - - 1999
There have been several reports with respect to idiopathic ventricular tachycardias (VTs) originating from the left ventricular outflow tract (LVOT). A previous report suggested that triggered activity plays a partial role in idiopathic LVOT tachycardia from the electrophysiological as well as the electropharmacological viewpoint. However, the exact role of triggered ...
Kocovic D Z - - 1999
OBJECTIVES: The purpose of this study was to determine the relation of isolated potentials (IPs) recorded during ventricular tachycardia (VT) to reentry circuit sites identified by entrainment. BACKGROUND: Reentry circuits causing VT late after myocardial infarction are complex. Both IPs and entrainment have been useful for identifying successful ablation sites, ...
Lacroix D - - 1999
Ventricular tachycardia (VT) substrates may form in preferential locations and similar electrocardiographic patterns may be observed when ventricular activation starts from a particular site. We examined the role of the posterior inferior process of the left ventricle in the mechanism of VT occurring after inferior wall myocardial infarction. We reviewed ...
Chinushi M - - 1999
A 33 year-old woman was referred to our hospital for further treatment of ventricular tachycardia (VT). During treatment with amiodarone (200 mg/day), clinical VT at the cycle length of 510 ms was induced. During the VT, rapid ventricular pacing was repeated at progressively shorter cycle lengths after a decrement of ...
Jalife J - - 1999
Ventricular fibrillation (VF) is the leading heart rhythm alteration that results in sudden cardiac death, yet the detailed mechanisms of the arrhythmia remain elusive. Fibrillation has been defined as "turbulent" cardiac electrical activity, which conjures up the idea of totally random and disorganized activation of the ventricles. I review theoretical ...
Shimoike E - - 1999
Idiopathic ventricular tachycardia (VT) originating from the left ventricular outflow tract (LVOT) is rare. Previously reported were two cases of LVOT tachycardia which were treated with radiofrequency (RF) catheter ablation through endocardial aortomitral continuity. We report here a case of a repetitive LVOT tachycardia in which the QRS morphology during ...
Mitrani R D - - 1999
INTRODUCTION: Although decreased vagal tone, as measured by heart rate variability is a risk factor for ventricular fibrillation (VF) and sudden cardiac death, it is unknown whether increasing vagal tone has an antiarrhythmic effect. The purpose of this study was to determine whether edrophonium hydrochloride (HCI), a vagomimetic agent, increases ...
Angelos M G - - 1999
OBJECTIVES: Earlier work suggests the in-vivo heart alters its substrate utilization as a function of cardiac work. Previous work has also demonstrated the high oxygen requirements of the heart during ventricular fibrillation (VF). The authors hypothesized that myocardial substrate utilization during VF with perfusion is similar to the normal beating ...
Hohnloser S H - - 1999
OBJECTIVES: The purpose of this study was to determine the prevalence, characteristics and the predictive value of nonsustained ventricular tachycardia (VT) for subsequent death and arrhythmic events after acute myocardial infarction (AMI). BACKGROUND: Nonsustained VT has been linked to an increased risk for sudden death in coronary patients. It is ...
Lacroix D - - 1999
INTRODUCTION: Although direct ventricular tachycardia (VT) surgery has been shown to be effective for treatment of inferior myocardial infarction (MI), the differences in the arrhythmia substrates compared to anterior MI have not been systematically delineated. We sought to compare operative procedures and VT substrates between anterior and inferior MI locations. ...
Delacretaz E - - 1999
INTRODUCTION: In animal models, active cooling of the electrode during radiofrequency (RF) ablation allows creation of larger lesions, presumably by increasing the power that can be delivered without coagulum formation. These RF lesions have not been characterized in human myocardium in regions of infarction and scarring. METHODS AND RESULTS: Cooled-tip ...
Schilling R J - - 1999
BACKGROUND: Catheter ablation of ventricular tachycardia (VT) is limited by difficulty in identifying suitable sites for ablation. This study assesses use of a system capable of simultaneous endocardial mapping of the human left ventricle to map and guide radiofrequency (RF) catheter ablation of VT. METHODS AND RESULTS: A catheter-mounted noncontact ...
Lucron H - - 1999
Between 1980 and 1996, 89 unselected consecutive patients with repaired tetralogy of Fallot (TOF) underwent examination, including a prospective right ventricular programmed stimulation with the same protocol (S1 S2, S3, S4). Age at surgery was 4.2 +/- 3.5 years and age at electrophysiologic study was 10.9 +/- 6.5 years. Follow-up ...
Reddy P C - - 1999
As we approach the new millennium, treatment of survivors of cardiac arrest and prevention of sudden cardiac death (SCD) are the two most important problems confronting contemporary cardiology practice. Sudden cardiac death occurs as a result of ventricular tachycardia (VT) degenerating into ventricular fibrillation (VF). Several major arrhythmia treatment trials ...
Zhang X S - - 1999
Sinus rhythm (SR), ventricular tachycardia (VT) and ventricular fibrillation (VF) belong to different nonlinear physiological processes with different complexity. In this study, we present a novel, and computationally fast method to detect VT and VF, which utilizes a complexity measure suggested by Lempel and Ziv [1]. For a specific window ...
Anderson J L - - 1999
BACKGROUND: The Antiarrhythmics Versus Implantable Defibrillators (AVID) Study compared treatment with implantable cardioverter-defibrillators versus antiarrhythmic drugs in patients with life-threatening ventricular arrhythmias (VAs). AVID maintained a Registry on all patients, randomized or not, with any VA or unexplained syncope who could be considered for either of the treatment strategies. Trial-eligible ...
Stoletniy L N - - 1999
The QT dispersion (QTD) on the surface electrocardiogram is a noninvasive marker of heterogeneity of ventricular repolarization. An increased QTD has been associated with spontaneous ventricular arrhythmias. We investigated the relationship of QTD to inducible reentrant sustained ventricular tachycardia (VT) in 66 patients who underwent programmed electrical stimulation. Thirty-three patients ...
Yamaki M - - 1999
A three-dimensional heart model was constructed to simulate late potentials and ventricular fibrillation (VF). The model consisted of 50,000 discrete elements having a 1.5-mm spatial resolution. Each element represented excitable ventricular tissue, including a conduction system, and was characterized with classical features of the action potential, refractory period, and conduction ...
Ohara T - - 1999
BACKGROUND: The influence of a pharmacologic agent on wavefront dynamics during ventricular fibrillation (VF) in a setting of remodeled and healed myocardial infarction (MI) remains poor explored. We hypothesized that nicotine, by virtue of its complex direct and indirect cardiovascular effects, increases wavefront complexity during VF. Specifically, we sought to ...
Calvert C A - - 1999
OBJECTIVE: To determine whether ventricular late potentials (LP) identified by time-domain analysis (TDA) of the signal-averaged ECG could be identified by three-dimensional frequency-domain analysis (FDA). ANIMALS: 11 dogs (9 of which subsequently died suddenly) with ventricular tachyarrhythmias (10 with ventricular tachycardia) and abnormal TDA of the signal-averaged ECG. PROCEDURE: Signal-averaged ...
Akiyama J - - 1999
Sustained monomorphic ventricular tachycardia (VT) developed in a 58-year-old man with acute myocardial infarction and end-stage renal disease. Amiodarone was effective in preventing VT recurrence. Sustained VT was not induced during an electrophysiologic study. However, VT recurred during accidental hyperkalemia, which was caused by the change of dialysis therapy from ...
Hirao H - - 1999
Idiopathic ventricular tachycardias (VTs) are generally divided into those arising from the right ventricle and those arising from the left ventricle. There has been few reports of two morphologically distinct VT occurring in patients with no apparent structural heart disease. We report a patient with verapamil-sensitive left VT with a ...
Farré J - - 1999
Today, cardiology seems to be driven by mega-trials and meta-analyses. Guidelines published by scientific and professional cardiovascular societies, such as the American Heart Association, the American College of Cardiology, and the European Society of Cardiology, follow the rules of evidence-based medicine. Such evidence is not always sufficiently conclusive to practice ...
Holmberg M - - 1999
In Europe, 40% of all deaths of individuals who are 25-74 years of age are caused by cardiovascular disease. Cardiac disease is the underlying cause in two-thirds of out-of-hospital sudden deaths. The 28-day case fatality rate for the combined population of out-of-hospital coronary artery disease deaths and hospitalized acute myocardial ...
Schaumann A - - 1999
The implantable cardioverter defibrillator (ICD) is accepted as the therapy of choice in preventing sudden cardiac death. Multiple studies, such as Antiarrhythmics Versus Implantable Defibrillators (AVID), the Canadian Implantable Defibrillator Study (CIDS), the Cardiac Arrest Study Hamburg (CASH), and the Multicenter Automatic Defibrillator Implantation Trial (MADIT), have shown a substantial ...
Bogun F - - 1999
INTRODUCTION: Isolated diastolic potentials have been found to be helpful in identifying critical sites for ablation of ventricular tachycardia (VT) in patients with coronary artery disease. However, discrete potentials that occur during systole have not been previously described. The purpose of this study was to determine the significance of discrete ...
Haberl K - - 1999
BACKGROUND: The purpose of this study was to compare differential effects of a segment of slow conduction during ventricular tachycardia (VT) due to depression of the action potential and electrical uncoupling. METHODS AND RESULTS: In 33 Langendorff-perfused rabbit hearts, a ring of anisotropic left ventricular subepicardium was created by a ...
Steinberg J S - - 1999
BACKGROUND: The de novo occurrence of sustained ventricular tachycardia (VT) after CABG has been described, but the incidence, mortality rate, long-term follow-up, and mechanism are not well defined. METHODS AND RESULTS: This prospective study enrolled consecutive patients undergoing CABG at a single institution. Patients were followed up for the development ...
Narayan S M - - 1999
Repolarization alternans (RPA) indicates alternate-beat fluctuations in the temporal or spatial characteristics of the echocardiogram (ECG) STU segment which may represent dispersion in repolarization. Spectral decomposition has revealed microvolt-level RPA which has been found to correlate with ventricular tachycardia (VT) and fibrillation, and is increasingly being used for clinical risk ...
Bogun F - - 1999
INTRODUCTION: The postpacing interval (PPI) has been used to discriminate bystander sites from critical sites within a ventricular tachycardia (VT) reentry circuit, with a PPI that is similar to the VT cycle length (CL) being indicative of a site within the reentry circuit. The purpose of this study was to ...
Lerman B B - - 1999
INTRODUCTION: Adenosine has no direct electrophysiologic function in ventricular tissue, but in the presence of cyclic adenosine monophosphate (cAMP), stimulation exerts a potent antiadrenergic effect. This effect has been exploited in the recognition and treatment of ventricular tachycardia (VT) due to cAMP-mediated triggered activity and automaticity, which are respectively terminated ...
Müller H P - - 1999
The spatial distribution of high-frequency components in magnetic signals during the QRS complex of the human heartbeat was investigated. Cardiomagnetic signals were recorded simultaneously using 49 first-order magnetogradiometer channels of a multi-SQUID system with a low noise power density. The QRS fragmentation score S, as a measure of the fragmentation ...
Maehara K - - 1999
In order to investigate whether increased fine, fractionated signals within the QRS complex can detect arrhythmogenic substrates and how these fine signals link with ventricular mechanical dysfunction, wavelet analysis was performed on averaged QRS complexes obtained from the left precordial lead in 26 patients with idiopatic dilated cardiomyopathy (IDCM) and ...
Sosa E - - 1999
We report a case of a 63-year-old women with Chagas' disease and recurrent, syncopal VT treated by RF catheter ablation in whom endocardial application of RF energy was guided by nonsurgical epicardial mapping. The procedure was undertaken in the electrophysiology laboratory under deep anesthesia. VT was interrupted after 2.4 seconds ...
Singh BN - - 1999
BACKGROUND: The role of antiarrhythmic drug therapy continues to undergo major changes. The change is necessitated by the advent of invasive interventional procedures, such as catheter ablation of arrhythmias and the use of implantable devices for sensing and terminating life-threatening ventricular arrhythmias and symptomatically traublesome supraventricular arrhythmias. Many conventional and ...
Cabo C - - 1998
BACKGROUND: The complete reentrant circuit for ablation of reentrant ventricular tachycardia (VT) in humans can rarely be localized by mapping. As a result, surrogate markers, such as diastolic electrical activity, subsequently confirmed by entrainment, have been used. However, ablation at those sites has had variable efficacy. The reasons for this ...
Shusterman V - - 1998
OBJECTIVES: We hypothesized that neurohormonal activity contributes to the initiation of sustained ventricular tachycardia (VT) as reflected in indices of heart rate variability (HRV). BACKGROUND: Autonomic nervous system activity participates in experimental arrhythmias but clinical studies have been inconsistent. METHODS: Holter electrocardiograms from 53 patients with VT were analyzed. Heart ...
Tanaka S - - 1998
It has been established that treatment with an implantable cardioverter is effective for life-threatening arrhythmia including ventricular tachycardia (VT) and ventricular fibrillation (VF). Although most third and fourth-generation implantable cardioverter defibrillator (ICD) models are effective for the treatment of VT and VF, they often misinterpret supraventricular tachycardia (SVT), and the ...
Kobayashi Y - - 1998
A 31-year-old male with slow ventricular tachycardia (VT) developed a nonsustained VT with prolongation of the JT intervals after injection of contrast medium and saline into the marginal vein of the coronary sinus. The earliest activation site of the VT existed in the epicardium of the left ventricular base. Adenosine ...
Pogwizd S M - - 1998
BACKGROUND: To define the electrophysiological mechanism(s) of inducible and spontaneously occurring ventricular arrhythmias associated with nonischemic cardiomyopathy, 3-dimensional intraoperative mapping from 156 intramural sites was performed in 6 patients with idiopathic dilated cardiomyopathy undergoing cardiac transplantation. METHODS AND RESULTS: Electrode density was sufficient to determine the mechanism for 52 of ...
Nogami A - - 1998
INTRODUCTION: Verapamil-sensitive left ventricular tachycardia (VT) with a right bundle branch block (RBBB) configuration and left-axis deviation has been demonstrated to arise from the left posterior fascicle, and can be cured by catheter ablation guided by Purkinje potentials. Verapamil-sensitive VT with an RBBB configuration and right-axis deviation is rare, and ...
Wang L - - 1998
A technique of fast Fourier transform analysis has been used to derive mean ventricular fibrillation (VF) intervals, and to confirm that these VF intervals predict ventricular refractory periods. Twenty episodes of VF were induced by a rapid ventricular pacing in 12 sheep. VF activations in a 10-second period were simultaneously ...
Tada H - - 1998
We examined 10 patients with idiopathic left ventricular (LV) aneurysm with sustained ventricular tachycardia (VT) (Id-An group), and compared them with those in 16 age- and sex-matched patients who had postinfarction aneurysm and VT (MI-An group) to clarify detailed clinical and electrophysiologic characteristics of idiopathic LV aneurysm. The clinical and ...
Schalij M J - - 1998
BACKGROUND: Localization of early activated endocardial areas during ventricular tachycardia (VT) is mandatory for performance of surgical or radiofrequency catheter interventions. The use of a multielectrode catheter may shorten the procedure time and increase the accuracy of the procedure compared with single-electrode mapping techniques. This study was performed to evaluate ...
Calvert C A - - 1998
High-resolution electrocardiography, often referred to as signal averaged electrocardiography (SAECG), has clinical utility in human medicine for detecting ventricular late potentials (LP) as predictors of future arrhythmic events, specifically reentrant type of ventricular tachycardia (VT). Time-domain analysis of the SAECG is conceptually similar to standard ECG analysis, but the primary ...
Koller M L - - 1998
The restitution kinetics of action potential duration (APD) were investigated in paced canine Purkinje fibers (P; n = 9) and endocardial muscle (M; n = 9), in isolated, perfused canine left ventricles during ventricular fibrillation (VF; n = 4), and in endocardial muscle paced at VF cycle lengths (simulated VF; ...
Sosa E - - 1998
INTRODUCTION: Postinfarction ventricular tachycardia (VT), anteroseptal aneurysm, and ventricular dysfunction are commonly associated and predict a poor long-term prognosis. Surgical left ventricular reconstruction, which includes double plication of the anterior and septal wall, can improve ventricular function. This article analyzes the long-term efficacy of such a procedure to control recurrence ...
Grimm W - - 1998
The Marburg Cardiomyopathy Study (MACAS) is a prospective, observational study designed to determine the value of the following potential noninvasive arrhythmia risk predictors in at least 200 patients with idiopathic dilated cardiomyopathy (IDC) over a 5-year follow-up period: NYHA-class, left ventricular ejection fraction (LVEF), left ventricular end-diastolic diameter, left bundle ...
Harada T - - 1998
OBJECTIVE: To identify target sites for radiofrequency ablation of ventricular tachycardia (VT) by entrainment mapping techniques in patients with arrhythmogenic right ventricular dysplasia. METHODS: Entrainment mapping and radiofrequency ablation of eight VTs was performed in seven patients. Radiofrequency ablation was applied at 31 reentry circuits sites that were classified based ...
Kamakura S - - 1998
BACKGROUND: Idiopathic ventricular tachycardia (VT) is known to arise from the right ventricular (RV) and left ventricular outflow tracts (LVOT). However, reliable noninvasive methods to localize the optimum ablation site for VT have not been reported. METHODS and RESULTS: Body surface maps (BSM) and 12-lead ECGs were investigated in 35 ...
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