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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 ...
Barold H S - - 1997
This case describes ventricular proarrhythmia as a result of a synchronized internal atrial defibrillation shock in a 29-year-old man with Ebstein's anomaly referred for radiofrequency ablation of a right posterior accessory pathway. During the electrophysiologic study, atrial fibrillation was induced and 3/3 msec shocks of various strengths were delivered between ...
Fotuhi P C - - 1997
OBJECTIVES: We investigated the impact of an inactive endocardial lead on the 50% effective dose (ED50%) for successful ventricular defibrillation. BACKGROUND: The presence of abandoned epicardial mesh patch electrodes detrimentally affects the defibrillation efficacy of an endocardial lead system. It is not known whether abandoned endocardial electrodes produce a similar ...
Behrens S - - 1997
OBJECTIVES: This study investigated the effects of acute global ischemia on the vulnerable window, the upper limit of vulnerability and the defibrillation threshold. BACKGROUND: Myocardial ischemia, an important factor for arrhythmogenesis and sudden death, may affect the inducibility of ventricular fibrillation by T wave shocks as well as the defibrillation ...
Dorian P - - 1997
Electrical storm is defined as recurrent, hemodynamically destabilizing ventricular tachycardia or ventricular fibrillation occurring two or more times in a 24 h period, and usually requiring electrical cardioversion or defibrillation. Recent advances in the understanding of the pathogenesis of this serious arrhythmia and in its pharmacological management have improved the ...
Martin D J - - 1997
INTRODUCTION: The upper limit of vulnerability (ULV) is the shock strength at or above which ventricular fibrillation cannot be induced when delivered in the vulnerable period. It correlates acutely with the acute defibrillation threshold (DFT) and can be determined with a single episode of fibrillation. The goal of this prospective ...
Strohmenger H U - - 1997
OBJECTIVE: The purpose of this study was to assess from the ventricular fibrillation ECG signal whether certain amplitude parameters, or frequency parameters derived using fast Fourier transform analysis, are predictive of countershock success (defined as a stable supraventricular rhythm following countershock). DESIGN: Retrospective, descriptive study. SETTING: Emergency medical service at ...
Peralta A O - - 1997
OBJECTIVE: Evaluation of the impact of undersensing on VF detection time and the relationship of undersensing to the programmed shock energy. BACKGROUND: Failure to reconfirm an ongoing arrhythmia due to undersensing by a noncommitted ICD might prolong the time to therapy. METHODS: We measured initial detection times and redetection times ...
Murakawa Y - - 1997
OBJECTIVES: We tested whether a new class III drug (MS-551) administered during ventricular fibrillation (VF) could decrease the defibrillation threshold (DFT) in anesthetized canine hearts. BACKGROUND: Pretreatment with class III antiarrhythmic agents is known to enhance electrical defibrillation efficacy. METHODS: In a preliminary study (n = 10), we ascertained the ...
Link M S - - 1997
OBJECTIVES: This study evaluates the hypothesis that in patients with syncope of unknown origin, inducible ventricular arrhythmias are specific arrhythmias and therefore should be appropriately treated. BACKGROUND: Although syncope is a common clinical entity, the evaluation and treatment of patients with syncope without a clear etiology are not well defined. ...
Dorian P - - 1997
INTRODUCTION: Drugs which primarily prolong cardiac refractoriness decrease defibrillation voltage and energy requirements in animals and man. The effect of such drugs on ventricular fibrillation itself is not well understood. We hypothesized that tedisamil, an investigational antiarrhythmic drug which blocks Ito and IK repolarizing potassium channels, would increase organization of ...
Herlitz J - - 1997
AIM: To describe rhythm changes during the initial phase of resuscitation from ventricular fibrillation in relation to the interval between collapse and defibrillation, to survival and to bystander-initiated cardiopulmonary resuscitation (CPR). PATIENTS: All patients who suffered out-of-hospital cardiac arrest between 1980 and 1992, who were reached by the emergency medical ...
Luceri R M - - 1997
The use of transvenous ICD systems and the recent advances in atrial defibrillation techniques have heightened interest in internal defibrillation. However, most shocks for induced or spontaneous arrhythmias in patients without devices are still delivered transthoracically using high energy. We describe the history of temporary internal defibrillation techniques and report ...
Ayers G M - - 1997
Episodes of sustained atrial fibrillation have long been effectively treated with external, transthoracic defibrillation. Despite concomitant, postcardioversion therapy with antiarrhythmic agents, patients will frequently have additional episodes of atrial fibrillation requiring either repeat external cardioversion or treatment with either pharmacologic or additional nonpharmacologic therapies. The limited long-term efficacy of different ...
Fromm R E RE - - 1997
INTRODUCTION: sudden cardiac death is an important cause of mortality in the United States today. A major determinant of survival from sudden cardiac death is rapid defibrillation. Communities with high rates of bystander cardiopulmonary resuscitation (CPR) and early defibrillation enjoy the highest survival rates from out-of-hospital cardiac arrest. First responders ...
Moss A J - - 1996
BACKGROUND: Unsustained ventricular tachycardia in patients with previous myocardial infarction and left ventricular dysfunction is associated with a two-year mortality rate of about 30 percent. We studied whether prophylactic therapy with an implanted cardioverter-defibrillator, as compared with conventional medical therapy, would improve survival in this high-risk group of patients. METHODS: ...
Bardy G H - - 1996
BACKGROUND: The most important factor for improving out-of-hospital ventricular fibrillation survival rates is early defibrillation. This can be achieved if small, lightweight, inexpensive automatic external defibrillators are widely disseminated. Because automatic external defibrillator size and cost are directly affected by defibrillation waveform shape and because of the favorable experience with ...
Carlson M D - - 1996
External electrical atrial defibrillation was developed in the early 1960s. Direct current electrical external shocks convert atrial fibrillation to sinus rhythm in the majority of patients. Although much has been learned about the mechanisms of the arrhythmia and those responsible for successful external direct current atrial defibrillation, the technique has ...
Venditti F J FJ - - 1996
BACKGROUND: Reports have demonstrated a circadian variation in the incidence of acute myocardial infarction, ventricular arrhythmias, and sudden cardiac death. We tested the hypothesis that a similar circadian variation exists for defibrillation energy requirements in humans. METHODS AND RESULTS: We reviewed the time of defibrillation threshold (DFT) measurements in 134 ...
Santini M - - 1996
New technologic development of implantable cardioverter-defibrillators (ICDs) keeps up with the exponential increase of their use for primary and secondary prevention of sudden cardiac death. The first-generation ICD with limited shock capability alone could be considered adequate in most cardiac arrest victims, but it was not suitable for sudden death ...
Capucci A - - 1996
In considering alternatives to the implantable cardioverter-defibrillator (ICD) in patients with malignant ventricular arrhythmias, both pharmacologic and nonpharmacologic therapies are available. Unfortunately, both pharmacologic methods (even when therapy is individualized and optimized) and nonpharmacologic methods (including coronary revascularization and radiofrequency or surgical ablation) yield long-term results that are unacceptable for ...
Heisel A - - 1996
Atrial fibrillation (AF), the most common arrhythmia resulting in hospital admission, is a major health problem. The limited efficacy of antiarrhythmic drugs to control this rhythm disorder and their potential proarrhythmic risk led to the development of new techniques to ameliorate the treatment of AF. Transvenous atrial defibrillation using endocardial ...
Auricchio A - - 1996
A major problem in patients with cardioverter-defibrillators is to determine reliably the mechanism for spontaneous implantable cardioverter-defibrillator (ICD) discharges. Electrogram storage in ICD devices is comparable to that in permanent Holter monitors. Stored bipolar electrograms obtained from the sensing or shocking lead system contain a wide variety of different information. ...
Ujhelyi M R - - 1996
Hypertonic saline solution may enhance cardiac conduction via the fast inward sodium channel and alter transmembrane Ca+2 conductance via the sodium-calcium exchanger. Evidence suggests that both Ca+2 conductance and myocardial conduction velocity may affect ventricular defibrillation. Since hypertonic saline solution solutions (ie, sodium bicarbonate) may be administered to patients who ...
Isbruch F M - - 1996
Adequate sensing is a basic requirement for appropriate therapy with ICDs. Integrated sense pace defibrillation leads, which facilitate ICD implantation, show a close proximity of sensing and defibrillation electrodes that might affect the sensing signal amplitude by the high currents of internal defibrillation. In 99 patients, we retrospectively examined two ...
Bardy G H - - 1996
OBJECTIVES: The purpose of this study was to prospectively examine in a multicenter study the methods of use, efficacy and complications of a unipolar cardioverter-defibrillator in patients at risk for sudden cardiac death. BACKGROUND: Implantation of cardioverter-defibrillators in the pectoral region offers a significant opportunity to improve the management of ...
Dunbar S B - - 1996
OBJECTIVE: To examine the relationships among personal factors (demographic variables and trait optimism); situational factors (ejection fraction, functional status, history of sudden cardiac arrest); coping and appraisal processes; and mood disturbance in patients hospitalized for recurrent ventricular dysrhythmia before the insertion of an implantable cardioverter defibrillator (ICD). DESIGN: Descriptive and ...
Le Tourneau T - - 1996
We report a case of pericardial constriction associated with defibrillator patches developing 4.5 years after implantation. This constriction was related to the presence of a large pericardial mass that had developed above the defibrillator patch. This mass, which had a calcified superior border, suggested former hematoma associated with pericardial fibrosis. ...
Jalife J - - 1996
Ventricular fibrillation is the most important cause of cardiac electrical instability leading to sudden death. Fibrillation is believed to be associated with complex three-dimensional (3-D) spatio-temporal patterns of electrical excitation of the myocardium. However, to this date, such patterns have not been directly observed or characterized, and little is known ...
Yu J C - - 1996
The aim of this study was to examine the effect of ventricular fibrillation and a subsequent defibrillation shock on ventricular excitability and refractoriness in human beings. We studied 16 consecutive patients with implantable cardioverter-defibrillators undergoing follow-up studies. The pre- and post-shock pacing threshold, ventricular effective refractory period, monophasic action potential ...
Fredman C S - - 1996
This report describes a modified defibrillation technique used successfully in a patient with an implanted epicardial cardioverter defibrillator who developed refractory ventricular fibrillation. During operative testing at the time of generator replacement, two episodes of intractable ventricular fibrillation were terminated by using a combined internal (epicardial)-external (transthoracic) defibrillation system that ...
Saksena S - - 1996
Implantable cardioverter-defibrillators (ICDs) are an important nonpharmacological option in the treatment of malignant ventricular arrhythmias. Technological advances in current devices permit nonthoracotomy implantation with transvenous lead systems using biphasic shocks. Decreasing device size has resulted in pectoral implantation. Battery longevity is still short in comparison with that of pacemakers. Lead ...
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