摘要:

Sudden cardiac death remains one of the leading causes of death in western societies. Accordingly, the ability to identify patients at high risk of sudden cardiac death is important so that appropriate treatments can be used efficiently. Recently, T wave alternans (TWA) has emerged as a promising new test for such risk stratification. TWA is a heart rate-dependent measure of arrhythmia vulnerability, with maximal predictive accuracy at sustained, regular heart rates of 100 to 120 bpm. In the clinical setting, these conditions may be achieved by either exercise or atrial pacing. TWA has been shown to predict inducibility of ventricular tachycardia with programmed stimulation and also spontaneous arrhythmic events. TWA has been successfully applied to diverse populations, including patients with coronary artery disease, nonischemic cardiomyopathy, congestive heart failure, and implantable defibrillators. Despite these encouraging results, the role of TWA to guide clinical therapy still needs to be elucidated better.

ISSN:0268-4705    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Torsade de pointes ventricular tachyarrhythmia in the long QT syndrome is a prime example of how molecular biology, ion channel, and cellular and organ physiology, coupled with clinical observations, promise to be the future paradigm for advancement of medical knowledge. Both the congenital and the acquired long QT syndrome are caused by abnormalities (intrinsic, acquired, or both) of the ionic currents underlying ventricular repolarization. In this review, the continually unraveling molecular biology of congenital long QT syndrome is discussed. The various pharmacologic agents associated with the acquired long QT syndrome are listed. Although it is difficult to predict which patients are at risk for torsade de pointes, careful assessment of the risk to benefit ratio is important before prescribing drugs known to cause QT prolongation. Thein vivoelectrophysiologic mechanism of torsade de pointes in the long QT syndrome is described, using as a paradigm the anthopleurin-A canine model, a surrogate for LQT3. The characteristic association of torsade de pointes with T-wave alternans and short-long cardiac sequences is discussed, with emphasis on electrophysiologic mechanisms. Finally, the expanding knowledge of genetic mutations other than long QT syndrome associated with polymorphic ventricular tachyarrhythmia is emphasized.

ISSN:0268-4705    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Cardiopulmonary resuscitation developed over the past one half century largely from empiric science and consensus opinions and recommendations. Treatment algorithms and protocols were originally developed to summarize existing recommendations for systematic and regimented use by a heterogenous group of health care providers. Now, resuscitation science and health care teams are focusing on major issues and continuing questions as sudden death rates remain undaunted and the population at risk is rapidly increasing.For the first time, the international resuscitation community has developed an international consensus on Guidelines for Resuscitation and Emergency Cardiac Care. More than 400 basic scientists, clinical trial investigators, and educators defined common priority and scientific areas during the Evidence Evaluation International Meeting in 1999. The science of resuscitation and emergency cardiac care was reviewed for evidence-based support in randomized clinical trials. In 2000, this review was used as a foundation to structure international guidelines. The participants from seven resuscitation councils and foundations realized that regional differences in systems may exist, but the underlying science should be the same. Presented in this article are some of the major issues and controversies discussed in adult advanced cardiac life support, primarily focusing on the major problem of prehospital adult cardiac arrest.

ISSN:0268-4705    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Atrial fibrillation is the most common cardiac arrhythmia in adults. The prevalence of atrial fibrillation rises with age, reaching as high as 9% in those 70 years and older. Currently there are 2.2 million affected people in the United States, with twice the mortality rate of age-matched controls in sinus rhythm. Epidemiologic studies show atrial fibrillation to be responsible for as many as 15% of the total number of strokes, a higher incidence of dementia, cardiac function compromise, and decreased quality of life. Recent studies indicate that rate control and rhythm restoration are equally effective strategies in the treatment of atrial fibrillation, with a trend toward better survival in patients treated for rate control and anticoagulation. Data from several randomized controlled studies on stroke prophylaxis provided consistent evidence of the superiority of adjusted-dose warfarin over aspirin. Guidelines developed by the American College of Cardiology, the American Heart Association, the European Society of Cardiology, and ACCP provide a convenient decision-making framework for the practicing physician. The safety and effectiveness of anticoagulation in clinical practice were found to be equal to those in major trials with rigorous controls. Despite the proven effectiveness and safety of oral anticoagulation for thromboembolism prophylaxis in atrial fibrillation, warfarin remains underused, especially among the elderly (75 years and older), who are at the greatest risk of stroke and would likely benefit the most from prophylactic anticoagulation.

ISSN:0268-4705    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Atrial fibrillation and heart failure are very common cardiac disorders, and both are associated with symptoms, significant morbidity, and mortality. Studies have attempted to determine the prognostic significance of atrial fibrillation in patients with heart failure. Whether atrial fibrillation is an independent risk factor of mortality remains controversial. Multiple trials using either pharmacologic or nonpharmacologic therapies in an attempt to manage atrial fibrillation have been developed. The purposes of this review are to present an overview of atrial fibrillation in patients with heart failure and to discuss the prevalence, prognostic significance, complications, mechanisms, and trials that have formed the therapies presently used.

ISSN:0268-4705    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Several investigators have identified the pulmonary vein as the most common initiator of atrial fibrillation, and isolation of the pulmonary vein from atrial tissue can cure approximately 70% of patients with paroxysmal atrial fibrillation. Ongoing trials of a new device may increase the success rate and decrease the complication rate during the pulmonary vein isolation procedure.

ISSN:0268-4705    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Patients with frequent vasovagal syncope have a poor quality of life and often resist treatment with standard pharmacologic approaches. Clinical vasovagal syncope may be associated with some degree of bradycardia. Studies of temporary pacing during tilt table tests showed that pacing prevented syncope in a little more than half of patients who developed a vasovagal response. Six open-label studies of permanent pacing show that permanent pacemaker therapy is associated with substantial improvement over medical therapy. The roles of specific pacemaker modes have not been determined, although there is some evidence that rate-drop responsiveness helps. The second Vasovagal Pacemaker Study will quantify the true benefits of pacing for vasovagal syncope and assess the role of rate-drop response algorithms.

ISSN:0268-4705    

出版商:OVID    

年代:2003

数据来源: OVID

ISSN:0268-4705    

出版商:OVID    

年代:2003

数据来源: OVID