ISSN:0268-4705    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Clinical ventricular tachycardia and ventricular fibrillation are associated with a high recurrence rate, and through the 1980s and the early 1990s a variety of therapies have been proposed including the implantable cardioverter defibrillator (ICD). Over the past decade it has been recognized that prospective randomized trials are imperative if the proper role for any therapy is to be defined. The Antiarrhythmic Versus Implantable Defibrillator (AVID) trial recently was concluded and helped define the role of the ICD in high-risk patients. Other trials are studying patients at high risk for sudden death who have not yet had a clinical event. The recently concluded Multicenter Automatic Defibrillator Implantation Trial and CABG Patch Trial helped determine the proper role of the ICD in various pre-event high-risk subsets. These trials are summarized in detail.

ISSN:0268-4705    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Although ventricular tachyarrhythmias usually occur in the setting of definable heart disease, up to 15% of ventricular tachycardias and 10% of ventricular fibrillation occur in patients without heart disease. Of the various clinical entities comprising these idiopathic ventricular tachyarrhythmias, a few well-defined clinical syndromes have been described, such as idiopathic right ventricular outflow tract tachycardia, idiopathic left posterior fascicular ventricular tachycardia, and the right bundle branch block and ST segment elevation syndrome of idiopathic ventricular fibrillation. Many advances have been made in the past few years in our understanding and treatment of idiopathic ventricular tachyarrhythmias, and these advances are the subject of this review.

ISSN:0268-4705    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Atrial fibrillation (AF) is the most commonly encountered arrhythmia that occurs after cardiothoracic surgery. It develops in up to 40% of patients, most frequently in the first few postoperative days. The strongest risk factors for AF are age and male gender. The pathogenesis of this arrhythmia probably involves increased sympathetic activity in the setting of slowed atrial conduction. The development of postoperative AF is associated with an increased morbidity, higher costs, and prolonged hospitalization. The use of prophylactic β-blockers and procainamide reduces the incidence of AF whereas digoxin, verapamil, and amiodarone appear less effective. Once AF occurs, the mainstay of treatment remains rate control, anticoagulation, and restoration of sinus rhythm.

ISSN:0268-4705    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

The medical termsyncopeis derived from the Greek word “synkoptein,‘’ the original meaning of which was “to cut short.‘’ Because it is both a symptom and a sign, the physican may often find the evaluation of syncope a difficult and frustrating endeavor. Over the course of the past decade it has become apparent that transient alterations in autonomic nervous system activity, resulting in hypotension and bradycardia, are common causes of syncope. At the same time it has become apparent that these are a heterogenous group of disorders which, while sharing some characteristics, are nonetheless distinct maladies. This article attempts to briefly review our current understanding of these disorders and suggests guidelines on their diagnosis and management.

ISSN:0268-4705    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Heart rate variability is a recognized tool for the estimation of cardiac autonomic modulations. Recently, several studies have advanced the field of heart rate variability in three areas: 1) in technical modes of electrocardiogram processing and heart rate variability assessment, 2) in physiologic understanding and interpretation, and 3) in clinical and practical use. The most recent technical studies concentrate on the analysis of nonlinear aspects of heart period variations and on coherence between electrocardiogram variability and other physiologic factors such as respiration. Principal physiologic investigations studied the components of heart rate variability attributable to the individual limbs of the autonomic nervous system. It is becoming recognized that behavior and responses to the environment, including the psychosocial environment, play an important role in long-term heart rate variability. Established clinical applications of heart rate variablility are presently restricted to the assessment of risk after myocardial infarction and to the early diagnosis of diabetic neuropathy. Nevertheless, recent studies indicate that heart rate variability might soon become a similarly powerful tool for risk prediction and monitoring of disease progression in congestive heart failure and for monitoring or reinnervation after heart transplantation.

ISSN:0268-4705    

出版商:OVID    

年代:1998

数据来源: OVID

ISSN:0268-4705    

出版商:OVID    

年代:1998

数据来源: OVID

ISSN:0268-4705    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Indications for cardiac pacing in pediatric patients continue to expand. In addition to its traditional use in sinus and atrioventricular nodal disease, applications for cardiac pacing now include treatment of tachyarrhythmias after repair of congenital heart disease, reduction of left ventricular outflow tract obstruction in hypertrophic cardiomyopathy, and prevention of sudden death in the congenital long QT syndrome. Whereas many benefits have been well documented in adults, they remain anecdotal in children. Programmable features such as rate-response and antitachycardia pacing contribute to pacemaker versatility and facilitate the achievement of normal hemodynamics in children requiring long-term pacing therapy.

ISSN:0268-4705    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

The aim of this review is to highlight some relatively new applications of Doppler echocardiography in children. Recent observations of flow dynamics through a restricted orifice have revealed that flow through an opening converges toward the orifice in a series of proximal isovelocity hemispheric surfaces. The flow convergence region can be demonstrated by Doppler echocardiography as a color mosaic on the ventricular side of the mitral valve in the presence of mitral regurgitation and on the left-ventricular side of a ventricular septal defect with left-to-right shunting. The continuity principle dictates that regurgitant flow rate can be calculated as the product of the hemispheric surface area of the flow convergence region and the velocity at that hemispheric surface. Using this principle, investigators have made quantitative flow measurements of mitral regurgitation, ventricular septal defect flow and aortic regurgitation. These studies demonstrate that this new technique of noninvasive quantification has the potential of providing direct measures of regurgitant and shunt flow. However, further validation in the pediatric population is needed before it can be incorporated into routine clinical practice.

ISSN:0268-4705    

出版商:OVID    

年代:1998

数据来源: OVID