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Results 601 - 650 of 1046
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Strobel J S - - 1998
OBJECTIVES: The purpose of this study was to determine if the defibrillation threshold (DFT) is lower during the first few cycles of ventricular fibrillation (VF) than after 10 s of VF and, if so, if the effect is caused by local or global factors. BACKGROUND: The DFT may be low ...
Santini M - - 1998
Low-energy intra-atrial defibrillation is a new therapeutic option for restoring sinus rhythm in patients with atrial fibrillation (AF). The success rate is quite high when right atrium-coronary sinus or right atrium-pulmonary artery electrode configurations are used, although the former is associated with a slightly lower defibrillation threshold. Several issues regarding ...
Minen G - - 1998
A patient with ischemic dilated cardiomyopathy and history of ventricular fibrillation received an implantable cardioverter defibrillator by the nonthoracotomy approach. Four years later, during elective replacement of an exhausted pulse generator, a superior vena caval thrombotic occlusion with collateral circulation through the azygos and emiazygos vein systems was documented. This ...
Naccarelli G V - - 1998
Multiple trials using antiarrhythmic drugs, pharmacologic therapy, and implantable cardioverter defibrillators have been performed in an attempt to improve survival in patients: (1) postmyocardial infarction; (2) with congestive heart failure, with and without nonsustained ventricular tachycardia; and (3) with sustained ventricular tachycardia and those who have survived an out-of-hospital cardiac ...
Goldberger J J - - 1998
INTRODUCTION: Dedicated bipolar sensing has been suggested to be safer than integrated bipolar sensing due to an increased incidence of failure to redetect ventricular fibrillation after an unsuccessful shock with leads that use integrated bipolar sensing. We compared sensing characteristics during ventricular fibrillation of simultaneously recorded dedicated and integrated bipolar ...
Vogel U - - 1998
A 37-year-old Italian male developed a myocardial infarct with subsequent ventricular fibrillation. He was defibrillated seven times with up to 360 Joules. Thirteen days later the patient died of recurrent myocardial infarct due to thrombotic occlusion of the left circumflex coronary artery. At autopsy, necrosis of the right pectoralis muscle ...
Viskin S - - 1998
Different polymorphic ventricular tachyarrhythmias may cause syncope or cardiac arrest in patients with no heart disease: (1) Catecholamine-sensitive polymorphic ventricular tachycardia (VT) presents during childhood: the hallmark is the reproducible provocation of atrial and polymorphic ventricular arrhythmias during exercise, despite a normal QT. Beta-blockers are the treatment of choice. (2) ...
Mushlin A I - - 1998
BACKGROUND: The recently reported Multicenter Automatic Defibrillator Implantation Trial (MADIT) showed improved survival in selected asymptomatic patients with coronary disease and nonsustained ventricular tachycardia. The economic consequences of defibrillator management in this patient population are unknown. METHODS AND RESULTS: Patients were followed up to quantify their use of healthcare services, ...
Vlay S C - - 1998
Successful defibrillation is described in two patients in whom the defibrillating electrode was positioned in the coronary sinus and right ventricular outflow tract as alternative sites. Internal cardiac defibrillation has been successful with single or multiple endocardial electrodes, epicardial patch electrodes, and subcutaneous surface electrodes (patch, array) in varying combinations ...
Gold M R - - 1998
OBJECTIVES: The purpose of this study was to compare defibrillation thresholds with lead systems consisting of an active left pectoral electrode and either single or dual transvenous coils. BACKGROUND: Lead systems that include an active pectoral pulse generator reduce defibrillation thresholds and permit transvenous defibrillation in nearly all patients. A ...
Malkin R A - - 1998
When testing an ICD, there are at least two techniques for inducing ventricular fibrillation: (1) high frequency (approximately equal to 50 Hz) pacing; and (2) a single T wave stimulus. It is generally assumed that these two methods yield similar results. This study directly tested this assumption. In six dogs, ...
Trayanova Natalia - - 1998
The purpose of this paper is to investigate the relationship between cardiac tissue structure, applied electric field, and the transmembrane potential induced in the process of defibrillation. It outlines a general understanding of the structural mechanisms that contribute to the outcome of a defibrillation shock. Electric shocks defibrillate by changing ...
Wilson W R - - 1998
BACKGROUND: Implantable cardioverter-defibrillators have been infrequently used in children as therapy for resuscitated sudden death and syncope due to ventricular arrhythmias unresponsive to antiarrhythmics. METHODS: The medical records of 5 children with implantable cardioverter-defibrillators were retrospectively reviewed. All patients had experienced syncope and 3 (60%) an out-of-hospital cardiac arrest. Underlying ...
Osswald S - - 1998
Transvenous atrial defibrillation with multiple atrial lead systems has been shown to be effective in models without the potential for ventricular arrhythmias. The specific aim of this study was to evaluate the efficacy and safety of transvenous single lead atrial defibrillation in a canine model of ischemic cardiomyopathy. Ten dogs ...
Shkurovich S - - 1998
The inability to detect atrial activity limits implantable ventricular cardioverter defibrillators (ICD) in discriminating tachycardias and can result in inappropriate therapy. This study attempted to detect atrial activity on the wide-spaced bipole signals formed by the high-voltage (HV) leads of the ICD during device implantation and to develop an algorithm ...
Friedman P A - - 1998
Most patients with implantable defibrillators have diminished cardiac function. Progressive heart failure might impair defibrillation efficacy, leading to interpreted device failure. This study sought to determine the effect of ventricular dysfunction on defibrillation energy using a biphasic endocardial system. Eleven dogs were ventricularly paced at 225 pulses/min for 2 weeks ...
Cohen T J - - 1998
Pneumothorax has previously been reported to increase defibrillation thresholds and lead impedance in monophasic systems. This article demonstrates a case using an active can system in which the lead impedance between the right ventricular defibrillation coil and the device improved from 70 omega with pneumothorax to 48 omega after resolution. ...
Runsiö M - - 1998
BACKGROUND: During implantation of cardioverter-defibrillators, repeated inductions of ventricular fibrillation and defibrillation are performed. Little is known about the myocardial metabolism associated with ventricular fibrillation and defibrillation in humans. METHODS: Sixteen patients scheduled for transvenous cardioverter-defibrillator implantation were included in the study. In 10 of the patients, blood samples were ...
Exner D V - - 1998
The follow-up prevalence of electrogram-confirmed spontaneous ventricular tachycardia with a cycle length of >280 ms (53%) exceeds the prevalence of ventricular fibrillation (23%) in patients whose only spontaneous arrhythmia before implantable cardioverter defibrillator implantation was ventricular fibrillation. Antitachycardia pacing therapy safely terminates most (89%) of these slower ventricular tachycardia episodes, ...
Groh W J - - 1998
Implantable cardioverter-defibrillators are commonly used in patients who have life-threatening ventricular arrhythmias. With these implanted electronic devices, bradyarrhythmias and tachyarrhythmias can be recognized promptly and treated with electrical pacing, cardioversion or defibrillation. Implantable cardioverter-defibrillators have been shown to substantially reduce the incidence of sudden cardiac death in patients with known ...
Wolfe D A - - 1998
The safety and efficacy of ICDs have improved significantly in the past few years. Recent evidence supports the value of these devices not only for secondary prevention of sudden cardiac death, but also for primary prevention in post-myocardial infarction patients with poor left ventricular function, unsustained ventricular tachycardia, and inducible ...
Liu Z - - 1998
By ligating the proximate left anterior descend (LAD) of coronary artery and inducing the ventricular fibrillation with electrical stimulation, the preventive effects of electroacupuncture (EA) on ventricular fibrillation were observed. The results showed that the ventricular fibrillation threshold (VFT) of rats with acute ischemic myocardium was raised after acupuncturing some ...
Weiss D N - - 1997
Complete postoperative evaluation of implantable cardioverter-defibrillators (ICDs) before discharge, including arrhythmia induction, has been the standard since their introduction. Whereas the original ICDs provided little telemetered information and used separate pace-sense and defibrillation leads, modern, third-generation devices provide pace-sense function information in addition to other data and are used in ...
Keane D - - 1997
Following the introduction of a transvenous biatrial electrode configuration and a biphasic waveform for internal atrial defibrillation in patients in 1992, it was realized that the standard principles of efficient defibrillation derived from decades of ventricular defibrillation research would not provide painless atrial defibrillation in conscious patients. Over the last ...
Mazer C D - - 1997
Our objective was to develop a universal noninvasive method for VF induction. ICD implantation requires VF induction. Conventional rapid ventricular stimulation may fail to induce VF. Some ICDs can deliver low energy shocks on the T wave to induce VF. We hypothesized that an external dual chamber pacemaker and an ...
Bigger J T JT - - 1997
BACKGROUND: Patients with coronary heart disease, left ventricular dysfunction, and abnormalities on signal-averaged electrocardiograms have an increased risk sudden death. We evaluated the effect on survival of the prophylactic implantation of cardioverter-defibrillators in such patients at the time of coronary-artery bypass surgery. METHODS: Over the course of five years, 37 ...
- - 1997
BACKGROUND: Patients who survive life-threatening ventricular arrhythmias are at risk for recurrent arrhythmias. They can be treated with either an implantable cardioverter-defibrillator or antiarrhythmic drugs, but the relative efficacy of these two treatment strategies is unknown. METHODS: To address this issue, we conducted a randomized comparison of these two treatment ...
Lok N S - - 1997
OBJECTIVES: The objectives of this study were 1) to evaluate the effect of different right atrial electrode locations on the efficacy of low energy transvenous defibrillation with an implantable lead system; and 2) to qualitate and quantify the discomfort from atrial defibrillation shocks delivered by a clinically relevant method. BACKGROUND: ...
Cooper R A - - 1997
BACKGROUND: The ultimate acceptance of a fully automatic atrial defibrillator will depend on the reduction of pain to acceptable levels, requiring a marked decrease in defibrillation thresholds. The purpose of this study was to determine whether atrial defibrillation thresholds can be reduced by sequential shocks delivered through two current pathways. ...
Behrens S - - 1997
Antiarrhythmic drugs, most notably amiodarone, are often used to combat life-threatening tachyarrhythmias simultaneous with implantable cardioverter defibrillators. However, the effects of long-term amiodarone treatment on ventricular fibrillation (VF) vulnerability and the defibrillation threshold (DFT) remain incompletely understood. VF vulnerability and the DFF for monophasic and biphasic shocks were studied in ...
Steinbeck G - - 1997
Patients with a history of sustained ventricular tachyarrhythmias form an extremely inhomogeneous group with respect to presenting arrhythmia, underlying cardiac disease, and therefore, risk of dying suddenly. For subgroups such as ventricular tachycardia in the absence of underlying cardiac disease, radiofrequency catheter ablation offers cure. In others, implantation of a ...
Markewitz A - - 1997
Nonthoracotomy lead systems for implantable cardioverter defibrillators (ICDs) have reduced operative mortality and morbidity as compared to epicardial lead systems but are usually associated with higher defibrillation thresholds (DFTs). The purpose of this prospective randomized trial was to investigate if the second defibrillation electrode in the left subclavian vein can ...
Trappe H J - - 1997
OBJECTIVE: To determine whether patients with life threatening ventricular tachyarrhythmias, impaired left ventricular function, and severe heart failure will benefit from implantable cardioverter-defibrillator (ICD) treatment. DESIGN: 410 patients were followed up after ICD implant. Left ventricular function was assessed by the New York Heart Association (NYHA) functional class of heart ...
Ott P - - 1997
INTRODUCTION: Ventricular dilatation has important electrophysiologic effects, but its effect on ventricular defibrillation threshold (DFT) is unknown. METHODS AND RESULTS: A fluid-filled, latex balloon was placed in the left ventricular cavity of 19 isolated rabbit hearts. In each experiment, an undilated volume (equivalent to a left ventricular end-diastolic pressure of ...
Reddy R K - - 1997
STUDY OBJECTIVE: Electrocardiographic abnormalities are common after transthoracic defibrillation. ECG ST-segment changes are especially problematic after defibrillation and may indicate ischemic or shock-induced cardiac dysfunction after resuscitation. Biphasic defibrillation waveforms, compared with monophasic waveforms, diminish shock-induced cardiac dysfunction in laboratory preparations. This effect has not been validated in human subjects. ...
Xie J - - 1997
BACKGROUND: The fatal outcome of victims after initially successful resuscitation from cardiac arrest has been attributed both to global myocardial ischemia during the interval of cardiac arrest and to the adverse effects of reperfusion. The present study was prompted by earlier experimental observation that the magnitude of myocardial dysfunction was ...
Elabbady T Z - - 1997
Prior to implantation of an atrial defibrillator, its effectiveness should be tested in each patient. A new catheter design for temporary use with electrodes for atrial defibrillation, electrogram sensing, and pacing was tested in this study. Atrial defibrillation thresholds defined using this temporary catheter were compared to the ones defined ...
Geddes L A - - 1997
The term defibrillation threshold is usually understood to mean the shock intensity just enough to defibrillate a specified cardiac chamber (atria or ventricles). With the advent of so many different types of defibrillator, it is important to be able to specify the defibrillation threshold, which has frequently been described by ...
Weil M H - - 1997
After failure of initial external defibrillation, restoration of spontaneous circulation is largely contingent on rapid and effective reversal of myocardial ischemia by both mechanical and pharmacologic means. Despite the introduction of modern cardiopulmonary resuscitation (CPR) more than 35 years ago, its universal acceptance, and its wide implementation, no improvements in ...
Gold M R - - 1997
Transvenous lead systems have become routine for defibrillator placement. However, previous studies of clinical predictors of an adequate nonthoracotomy defibrillation threshold (DFT) evaluated monophasic waveforms or more complex lead systems, including subcutaneous patches. Accordingly, this study is a prospective evaluation of the predictors of an adequate biphasic DFT in 114 ...
Munsif A N - - 1997
The feasibility of achieving both universal application of nonthoracotomy leads and low (< or = 15 J) defibrillation energy requirements by optimizing lead system configuration for use with low-output (<30 J) biphasic shock pulse generators was examined. Sixteen patients (mean age 62 +/- 8 years and mean left ventricular ejection ...
Khalighi K - - 1997
In three patients with a defibrillator system consisting of a Ventak P2 pulse generator and an Endotak C transvenous lead, we observed distortion of intracardiac electrograms following defibrillator shocks for atrial arrhythmias. There was a transient marked widening of the intracardiac ventricular complexes resembling ventricular tachycardia. This phenomenon should be ...
Kerber R E - - 1997
We present a case of open-chest cardiac massage where ventricular fibrillation developed and a direct current shock was required. In the absence of 'surgical' electrode paddles, standard paddle electrodes were used; one small electrode was placed directly on the exposed epicardial surface and the second electrode was placed on the ...
Strohmenger H U - - 1997
OBJECTIVE: This study was designed (1) to investigate the effects of normothermic and hypothermic perfusion on the median frequency of the fibrillating myocardium, and (2) to elucidate whether frequency-guided countershock therapy improves countershock success during the reperfusion phase of cardiac surgery. DESIGN: Prospective, randomized study. SETTING: University hospital cardiac surgery ...
Barron H V - - 1997
Implantable cardioverter defibrillators (ICDs) are very effective in preventing sudden cardiac death. However, debate continues as to whether ICD implantation is superior to amiodarone in prolonging survival in patients with life-threatening ventricular arrhythmias. Of 442 consecutive patients treated with amiodarone, we identified 48 patients with symptomatic ventricular arrhythmias who met ...
Fries R P - - 1997
We studied the possible relation between the frequency of ventricular tachyarrhythmic events and thermal stress in patients with an implantable cardioverter-defibrillator (ICD) living in a locally limited area under homogeneous climatic conditions. The frequency of tachyarrhythmic events was correlated with the thermal stress level according to the "Klima Michel Model," ...
Paradis N A - - 1997
At present, there are only a limited number of objective measures available to clinicians resuscitating patients from cardiac arrest. The electrocardiogram and end-tidal CO2 are easily applied, but the data they produce are of only limited utility in evaluating the efficacy of chest compression and in choosing the sequence of ...
Kudenchuk P J - - 1997
INTRODUCTION: Significant increases in ventricular pacing threshold have been observed following monophasic waveform ventricular defibrillation shocks. High-output pacing is recommended to ensure consistent capture, particularly in pacemaker-dependent patients who are likely to be defibrillated. Whether biphasic waveform defibrillation compounds this problem is not known. The purpose of this prospective study ...
Nisam S - - 1997
Efficacious therapy for chronic coronary patients, known to be at high risk of sudden arrhythmic death, has been a long-lasting challenge for cardiologists. The "Multicenter Automatic Defibrillator Implantation Trial" (MADIT) has demonstrated in a prospective, randomized trial that such patients achieve 54% better survival (p < or = 0.009) when ...
Tomassoni G - - 1997
BACKGROUND: Recent studies have shown that specifically shaped biphasic waveforms can lower energy requirements for ventricular defibrillation. We prospectively compared the defibrillation efficacy of three different biphasic wave shapes incorporated in three commercially available implantable defibrillators. The results led to the development of a second protocol in which the importance ...
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