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Results 451 - 500 of 1015
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Gradaus Rainer - - 2002
Early during ventricular fibrillation, the defibrillation threshold may be low, as ventricular fibrillation most probably arises from a localized area with only a few wavefronts and the effects of global ischemia, ventricular dilatation, and sympathetic discharge have not yet fully developed. The purpose of this study was to explore the ...
Koster Rudolph W - - 2002
INTRODUCTION: Sudden cardiac death is a major health problem. Worldwide success of resuscitation from out-of-hospital cardiac arrest is modest, with 5% to 10% survival to hospital discharge. METHODS AND RESULTS: In the chain of survival, early defibrillation (goal <5 min after collapse) is a major determinant of successful outcome of ...
Boriani Giuseppe - - 2002
The role of devices that deliver shock therapy for atrial fibrillation is still debated. Following technical improvements in catheter-based atrial defibrillation, implantable devices have become available either in the form of stand-alone atrial defibrillators or in the form of dual defibrillators. Although preliminary results do not support their use as ...
Lüderitz B - - 2002
The history of cardiac rhythm disorders including antiarrhythmic drugs and electrotherapeutical tools is long and fascinating. In the beginning, there was not simply the anatomy and physiology of the heart, but also analysis of the pulse, which indicates the activity of the heart. Thus, like any other field of medicine, ...
Marketou M E - - 2001
For a patient with idiopathic dilated cardiomyopathy, an implantable defibrillator, and amiodarone induced thyrotoxicosis associated with ventricular fibrillation storm. Medical therapy was ineffective. Thyroidectomy resulted in immediate control of the arrhythmia and permitted reinitiation of amiodarone. At 18-month follow-up, the patient remained euthyroid on amiodarone and ventricular arrhythmia free.
Wang Y - - 2001
Finite-element (FE) modeling has been widely used in studies of bioelectric phenomena of tissues, including ventricular defibrillation. Most FE models, whether built from anatomical atlases or subject-specific tomographic images, treat the myocardium as an isotropic tissue. However, myocardium has been experimentally shown to have significant anisotropy in its resistivities, although ...
Favale S - - 2001
The "EGM width criterion" is a discrimination algorithm that was available in the last generation ICDs. It improved ventricular tachycardia detection by withholding inappropriate therapy deliveries in the presence of narrow QRS tachycardias. The accuracy of the algorithm depends on the optimal settings of the intracardiac EGM source, the "slew ...
Butter C - - 2001
BACKGROUND: Defibrillation thresholds (DFT) with standard implantable cardioverter-defibrillator leads in the right ventricle (RV) may be determined by weak shock field intensity in the myocardium of the left ventricle (LV). Adding a shocking electrode in a coronary vein on the middle of the LV free wall, thereby establishing biventricular defibrillation, ...
Sanders G D - - 2001
BACKGROUND: Clinical trials have shown that implantable cardioverter defibrillators (ICDs) improve survival in patients with sustained ventricular arrhythmias. OBJECTIVE: To determine the efficacy necessary to make prophylactic ICD or amiodarone therapy cost-effective in patients with myocardial infarction. DESIGN: Markov model-based cost utility analysis. DATA SOURCES: Survival, cardiac death, and inpatient ...
Achleitner U - - 2001
BACKGROUND AND OBJECTIVE: Chest compressions before initial defibrillation attempts have been shown to increase successful defibrillation. This animal study was designed to assess whether ventricular fibrillation mean frequency after 90 s of basic life support cardiopulmonary resuscitation (CPR) may be used as an indicator of coronary perfusion and mean arterial ...
Michaud G F - - 2001
According to American Heart Association/American College of Cardiology Practice Guidelines, electrolyte abnormalities, including abnormal serum potassium concentrations, are considered a correctable cause of a life-threatening ventricular arrhythmia. Ventricular defibrillator therapy in this situation is a class III indication, and thought to be ineffective and perhaps harmful, although there are minimal ...
Patwardhan A - - 2001
Cycle periods in ECG during VF are correlated with periods of reentrant activation. The ECGs recorded from different locations on the thorax were contributed to from electrical activations within the heart in approximately inverse proportion of their distance from the recording sites. Similarity in cycle periods between ECGs recorded from ...
Merkely B - - 2001
One of the most important subsystems of implantable cardioverter defibrillator (ICD) is the sensing stage, since it determines the sensitivity and specificity of the device to detect the heart rate and the underlying arrhythmia. This paper aims to investigate a new detection algorithm for ICD, which operates fully automatically. The ...
Hamprecht F A - - 2001
BACKGROUND: Noninvasive prediction of defibrillation success after cardiac arrest and cardiopulmonary resuscitation (CPR) may help in determining the optimal time for a countershock, and thus increase the chance for survival. METHODS: In a porcine model (n=25) of prolonged cardiac arrest, advanced cardiac life support was provided by administration of two ...
Tang W - - 2001
STUDY OBJECTIVE: To compare the effects of biphasic defibrillation waveforms and conventional monophasic defibrillation waveforms on the success of initial defibrillation, postresuscitation myocardial function, and duration of survival after prolonged duration of untreated ventricular fibrillation (VF), including the effects of epinephrine. DESIGN: Prospective, randomized, animal study. SETTING: Animal laboratory and ...
Panchal V R - - 2001
A 70-year-old man with a single-chamber implantable cardioverter defibrillator (ICD) placed for ventricular tachycardia presented with syncope. He was found to have ventricular flutter/fibrillation with capacitor charge time in excess of 1 minute before defibrillation. The excessive charge time was secondary to ICD capacitor malfunction. The generator was explanted and ...
Vardas P E - - 2001
AIMS: To assess the effects of atrial fibrillation duration on the defibrillation threshold in atrial fibrillation patients seconds or minutes after initiation of the arrhythmia. METHODS AND RESULTS: Nineteen patients with recurrent symptomatic atrial fibrillation were evaluated. After programmed induction of atrial fibrillation, the defibrillation threshold was assessed after two ...
Steinberg J S - - 2001
BACKGROUND: Previous retrospective or observational series suggest that many patients with an implantable cardioverter-defibrillator (ICD) will be treated with antiarrhythmic drugs (AADs) to modify the frequency or manifestation of recurrent ventricular arrhythmias. The relative clinical benefit, however, is uncertain, and deleterious interactions can occur. The objective of this clinical investigation ...
Kuisma M - - 2001
Early defibrillation by emergency medical services has been a success story in the treatment of ventricular fibrillation. This success has been followed by recommendations to allow public access to defibrillation equipment. We tracked the changes in incidence of ventricular fibrillation from prospectively collected data from the Helsinki Cardiac Arrest Register. ...
Leng C T - - 2001
The authors devised a nonthoracotomy defibrillation system for a patient with a prosthetic tricuspid valve using existing technology and previously established implantation techniques. Their lead configuration deviates substantially from existing designs in its primary use of a coronary sinus defibrillation coil and a left-sided subcutaneous array to distribute current across ...
Gradaus R - - 2001
INTRODUCTION: Placement of implantable cardioverter defibrillators (ICDs) has been simplified by using the shell of a pectorally implanted ICD as a defibrillation electrode in combination with an endocardial right ventricular defibrillation lead. However, a sufficiently low defibrillation threshold (DFT) cannot be obtained in a few patients. Therefore, alternative approaches were ...
Everett T H - - 2001
Electrical remodeling of atrial fibrillation may account for the increase in atrial defibrillation thresholds over time. The aim of this study was to examine the time course of electrical remodeling and the benefit of early defibrillation on the defibrillation threshold. Twenty-six mongrel dogs weighing 27.6 +/- 3.3 kg were induced ...
Wang N C - - 2001
Investigators who studied ventricular defibrillation by use of optical mapping techniques failed to observe an initial defibrillation event (isoelectric window or quiescent period) shown by electrode mapping studies. This discrepancy has important implications for the mechanisms of defibrillation. The purpose of the present study was to demonstrate an optical equivalent ...
Takatsuki S - - 2001
A 62 year old man was admitted for evaluation of recurrent episodes of syncope. A surface ECG showed frequent repetitive premature ventricular complexes of right ventricular outflow tract origin. Ventricular fibrillation was inducible by programmed electrical stimulation but otherwise cardiac evaluation was unremarkable. A diagnosis of idiopathic ventricular fibrillation was ...
Hauser R G - - 2001
Because it is a lifesaving device, the unexpected failure of an ICD can be catastrophic. We report ICD electronic circuit failure due to electrical overstress damage (EOS) to the high voltage hybird circuit and other electronic components in a series of ICD pulse generator models. Data were obtained from the ...
Amann A - - 2001
Prediction of the success of defibrillation to avoid myocardial injury and performance feedback during CPR requires algorithms to analyze ventricular fibrillation signals. This report reviews investigations on different parameters of ventricular fibrillation electrocardiographic signals, including amplitude, frequency, bispectral analysis, amplitude spectrum area, wavelets, nonlinear dynamics, N(alpha) histograms, and combinations of ...
Malkin R A - - 2001
We present a novel measurement for studying defibrillation mechanisms: the time course of changes in the size of the left ventricular (LV) cavity within 500 ms following defibrillation. Mechanical changes can be linked to electrical mechanisms via an understanding of excitation-contraction coupling. Eight mongrel dogs were internally defibrillated 5-50 seconds ...
Mela T - - 2001
INTRODUCTION: Despite advances in technology, problems with effective ventricular endocardial sensing continue to arise and to result in inappropriate implantable cardioverter defibrillator (ICD) therapies. METHODS AND RESULTS: The patient is a 79-year-old man with ischemic cardiomyopathy and ventricular tachycardia (VT) who received inappropriate ICD therapies due to lead-related noise detection. ...
Ujhelyi M R - - 2001
OBJECTIVE: Determine the effects of hypothermia on defibrillation energy requirements and cardiac electrophysiology. DESIGN: Prospective randomized acute intervention trial. SETTING: Medical center animal laboratory. SUBJECTS: Fifteen domestic farm swine. INTERVENTIONS: Swine were randomized to a hypothermia group (n = 8) or a control group (n = 7). All animals were ...
Sinha S - - 2001
Ventricular fibrillation, the major reason behind sudden cardiac death, is turbulent cardiac electrical activity in which rapid, irregular disturbances in the spatiotemporal electrical activation of the heart make it incapable of any concerted pumping action. Methods of controlling ventricular fibrillation include electrical defibrillation as well as injected medication. Electrical defibrillation, ...
Glikson M - - 2001
Implantable cardioverter defibrillators (ICDs) have evolved from the treatment of last resort to the gold standard therapy for patients at high risk for ventricular tachyarrhythmias. High-risk patients include those who have survived life-threatening arrhythmias, and individuals with cardiac diseases who are at risk for such arrhythmias, but are symptomless. Use ...
Panotopoulos P - - 2001
INTRODUCTION: We prospectively compared the performance of the sensing and detection systems of three leading defibrillator manufacturers: Medtronic, Guidant, and Ventritex. METHODS AND RESULTS: Ventricular fibrillation signal was digitally recorded during defibrillator implantation and subsequently played back sequentially to a Medtronic Micro Jewel II 7223Cx, a Guidant MINI II 1762, ...
de Meester A - - 2001
A 71-year-old man with a history of myocardial infarction and syncopal ventricular tachycardia received an ICD. Progressively, increased defibrillation charge times of the ICD were observed. During a fast ventricular tachycardia, the patient collapsed. The underlying malfunction could be documented by ICD telemetric interrogation. An excessive charge time was recorded ...
Proclemer A - - 2001
AIM: This retrospective four-centre study assessed the current indications for dual-chamber implantable cardioverter defibrillators (ICDs) at implant and during a medium-term follow-up period in a group of patients treated by single-chamber ICD in the pre dual-chamber ICD era. METHODS AND RESULTS: The study population consisted of 153 consecutive patients (127 ...
Huang J - - 2001
BACKGROUND: Little is known about the effects of heart failure (HF) on the defibrillation threshold (DFT) and the characteristics of activation during ventricular fibrillation (VF). METHODS AND RESULTS: HF was induced by rapid right ventricular (RV) pacing for at least 3 weeks in 6 dogs. Another 6 dogs served as ...
Varma N - - 2001
In a patient with a defibrillator system incorporating a lead with integrated bipolar sensing, physical contact between a guidewire (inserted for venous access) and the right ventricular defibrillation coil created sensing artefacts that triggered an inappropriate discharge. The presence of the guidewire in the heart during the discharge resulted in ...
Pavia S - - 2001
The Multicenter Unsustained Tachycardia Trial (MUSTT) demonstrated that electrophysiologic testing (EP)-guided therapy significantly reduces arrhythmic death and cardiac arrest in patients with coronary artery disease, a left ventricular ejection fraction of 40% or less, nonsustained ventricular tachycardia, and inducible ventricular arrhythmia on EP testing-but only if the therapy includes an ...
Dworschak M - - 2001
To study the cause of myocardial injury after elective transvenous insertion of a cardioverter/defibrillator, we measured troponin T (TnT) release in 27 patients. Five patients needing only replacement of the generator with threshold testing served as controls. Compared to the control group, a significant increase in TnT occurred in the ...
Tavernier R - - 2001
OBJECTIVE: To study the outcome of patients with arrhythmogenic right ventricular dysplasia treated with an implantable cardioverter-defibrillator (ICD) for ventricular tachyarrhythmias complicated by haemodynamic collapse. DESIGN: Observational study. SETTING: University hospital. PATIENTS: Nine consecutive patients (eight male, one female; mean (SD) age, 36 (18) years) with arrhythmogenic right ventricular dysplasia ...
Dell'Orfano J T - - 2001
External cardioversion is a technique used electively or emergently to terminate arrhythmias such as atrial fibrillation, ventricular tachycardia, and ventricular fibrillation. There have been several advances made to modern defibrillators, including an improvement in the efficacy of the delivered shock. Biphasic shock waveforms have been shown to be superior to ...
Gazmuri R J - - 2001
Although the inhibition of proton-driven sarcolemmal sodium influx ameliorates ischemic injury in the quiescent myocardium, the effects when ventricular fibrillation is present are largely unknown. We used an isolated rat heart model to investigate whether inhibition of the sodium-hydrogen exchanger isoform-1 (with the benzoylguanidine derivatives HOE-694 and cariporide) with or ...
Tribulova N - - 2001
Ventricular fibrillation (VF) is defined as a sustained, fatal reentrant arrhythmia that never terminates spontaneously and requires artificial electrical defibrillation. For many years it was believed that spontaneous ventricular defibrillation (SVD) appears only in hearts with small muscle mass that cannot continue fibrillating. SVD appears even in humans, and some ...
Connolly S J - - 2000
AIMS: Three randomized trials of implantable cardioverter defibrillator (ICD) therapy vs medical treatment for the prevention of death in survivors of ventricular fibrillation or sustained ventricular tachycardia have been reported with what might appear to be different results. The present analysis was performed to obtain the most precise estimate of ...
Cruz B - - 2000
Countershock of prolonged ventricular fibrillation is usually followed by asystole or a nonperfusing rhythm. Data from three laboratory investigations indicate that administration of epinephrine and cardiopulmonary resuscitation (CPR) preceding countershock of prolonged ventricular fibrillation significantly improves cardiac resuscitation outcome compared with immediate countershock (relative risk reduction of failed resuscitation, 0.61). ...
Tang W - - 2000
Both clinical and experimental studies have demonstrated substantial impairment of ventricular function after resuscitation from cardiac arrest. Indeed, postresuscitation myocardial dysfunction has been implicated as a potentially important mechanism, accounting for fatal outcomes after successful resuscitation in 70% of victims within the first 72 hrs. Recent experimental studies implicated the ...
Shivkumar K - - 2000
Failure to detect ventricular tachycardia and/or ventricular fibrillation by implantable cardioverter defibrillators (ICDs) is a rare but serious problem. We report a case of failure to detect an episode of induced ventricular tachycardia by a dual chamber ICD, due to abbreviation of ventricular detection window secondary to programmed pacing parameters ...
Eynon C A - - 2000
Direct massage of the heart may be performed using a specifically designed device inserted via a limited thoracic incision. The technique is simple to perform and has been shown in experimental studies to be physiologically similar to formal open-chest cardiac massage. Preliminary human studies have been encouraging and pre-hospital and ...
Garcia L A - - 2000
BACKGROUND: Cardiopulmonary resuscitation (CPR) improves survival from cardiac arrest. The interactions between CPR and the new biphasic (BiP) defibrillation waveforms have not been defined. Our purpose was to compare the effect of CPR versus no CPR during BiP and damped sinusoidal (DS) shocks on the termination of ventricular fibrillation (VF) ...
Jekova I - - 2000
The introduction and widening application of automatic external defibrillators (AEDs) present very strong requirements for external ECG signal analysis. Highly accuratc discrimination between shockable and non-shockable rhythms is required, with sensitivity and specificity aimed to approach the maximum values of 100%. We undertook an assessment of the performance of five ...
Page R L - - 2000
BACKGROUND: Passengers who have ventricular fibrillation aboard commercial aircraft rarely survive, owing to the delay in obtaining emergency care and defibrillation. METHODS: In 1997, a major U.S. airline began equipping its aircraft with automated external defibrillators. Flight attendants were trained in the use of the defibrillator and applied the device ...
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