ISSN:0268-4705    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Antiarrhythmic drug therapy still remains the mainstay in the management of many supraventricular and ventricular arrhythmias. Several studies have recently pointed out the role of orally administered class 1C drugs in terminating atrial fibrillation. These drugs can play an important role in the ambulatory management of selected patients. The electrophysiologic mechanisms of these antiarrhythmic drugs together with their pharmacologic properties and clinical indications are discussed according to the current literature.

ISSN:0268-4705    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Multiple technologic advances in the implantable cardioverter defibrillator (ICD) have resulted in smaller size, easier implantation, and improved detection, therapy, and stored diagnostic information. Advanced dual-chamber ICDs are currently available that allow dual-chamber rate-responsive pacing with mode switching, enhanced detection algorithms, antitachycardia pacing, low-energy cardioversion, high-energy shocks, and extensive diagnostics. Based on improvements in lead systems and improved energy waveforms, almost all devices are being implanted with nonthoracotomy leads in the pectoralis area. The results of recent clinical trials have expanded indications for the ICD for primary and secondary prevention of sudden cardiac death. With advances in capacitor and battery technology coupled with improved lead systems and waveform resulting in lower defibrillation thresholds, it is likely that lower-output, smaller devices will be developed. In the future, ICDs may have expanded indications and may incorporate physiologic sensors to access hemodynamic significance of arrhythmias and algorithms for prediction and prevention of cardiac arrhythmias.

ISSN:0268-4705    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

During the past 10 years there has been a major shift in antiarrhythmic drug development from class I to class III antiarrhythmic agents. The first two class III antiarrhythmic drugs that became available, sotalol and amiodarone, also have potent antiadrenergic actions. Newer antiarrhythmic drugs either block a specific ionic current (eg,dofetilide-induced blockade of the rapidly activating component of the delayed rectifier potassium current) or block multiple ionic channels (eg,ibutilide and azimilide) in order to prolong atrial and ventricular action potentials without other specific pharmacologic effects. Recent data suggest that these new class III antiarrhythmic drugs are highly effective for treating patients with rhythm disorders with an acceptable degree of proarrhythmia. This manuscript reviews the newer class III agents’ effectiveness in treating atrial and ventricular arrhythmias and the recent studies examining drug-induced prolongation of atrial repolarization to prevent or terminate postoperative atrial fibrillation.

ISSN:0268-4705    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Athletes, although the healthiest segment of society, can develop cardiac arrhythmias. Benign bradycardias and atrial and ventricular premature contractions are common and seldom require treatment. Supraventricular tachycardias are less common and are usually not life-threatening, but do require treatment. Ventricular arrhythmias, although uncommon, are life-threatening and require treatment. Most athletes with ventricular arrhythmias have structural cardiac abnormalities, and further competitive play is usually prohibited.Commotio cordis, which is a recently described syndrome of sudden death caused by low-energy chest wall impact, may account for a significant percentage of the sudden deaths in athletes.

ISSN:0268-4705    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Catheter mapping and radiofrequency ablation of postinfarct sustained ventricular tachycardia (VT) remain one of the greatest challenges for the electrophysiologist. Although there were no major breakthroughs during the past year, several refinements and clarifications of existing mapping criteria were published. In addition, initial reports appeared describing new mapping systems and ablation technologies that may significantly impact the way ablation studies are performed as well as the way in which they affect success rates. Uncertainties remain as to how effective catheter ablation will be as a long-term cure for this type of VT. For the foreseeable future, catheter ablation in postinfarct VT will remain adjunctive rather than primary therapy.

ISSN:0268-4705    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

The incidence and risk factors for a variety of arrhythmias differ among men and women. Although symptomatic atrial reentrant tachycardias have a female predominance, the reverse is true for atrial fibrillation. Women have a lower incidence of sudden death. On the other hand, drug-induced torsades de pointes and symptomatic long QT syndrome have a female predominance. The incidence of arrhythmias seem to be increased during pregnancy. The mechanisms of these gender differences are unclear but may be related to hormonal effects and the shorter QT interval in men. Pharmacologic and nonpharmacologic therapy are equally efficacious in men and women.

ISSN:0268-4705    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

The common reasons for removal of pacing and defibrillator leads are infection, malfunction, or design defects such as fracture of J wires in Teletronics Accufix leads (Telectronics Pacing, Englewood, CO), which impose considerable risk for cardiac morbidity and mortality. Chronically implanted leads are fixed to the myocardium by fibrous tissue. Fibrous scar tissue may also encase the lead along its course. Furthermore, fragility of the lead and its tendency to break when extraction force is applied to overcome resistance imparted by the scar tissue add to the challenge of lead extraction. Thus, the extraction of chronically implanted leads is an important issue. Until a few years ago, the only methods available for the removal of chronically implanted leads were traction on the proximal segment of the lead and cardiac surgery. New techniques were developed to extract the leads by a transvenous approach using locking stylets, sheaths, snares, and retrieval baskets. Lead extraction using intravascular countertraction methods has since evolved as a specialty of its own. Progress has also been made in developing other system, such as Excimer laser energy for lead extraction. In this article, we discuss principles, techniques, and experience with these methods of extraction of chronic pacemaker and defibrillator leads.

ISSN:0268-4705    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Recent advances in transducer technology and image processing have led to the development of two techniques for three-dimensional (3-D) echocardiography: 1) 3-D reconstruction and 2) real-time 3-D (RT3-D) volumetric imaging. 3-D reconstruction creates a 3-D data set from a series of two-dimensional (2-D) images. RT3-D echocardiography uses a 2-D matrix phased array transducer with multiple parallel processing to produce real-time volumetric images of the heart. Both technologies produce novel views of congenital heart defects and offer improved quantification of ventricular volume, mass, and function. The main advantage of RT3-D imaging is its ability to capture 3-D data in real time. This avoids the motion artifact inherent with any reconstructive technique and permits analysis of events during a single cardiac cycle; however, at present, RT3-D imaging has poorer image quality and lacks the Doppler capability. Further development in both techniques will allow 3-D echocardiography to have more widespread clinical applicability.

ISSN:0268-4705    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Pulmonary atresia with intact ventricular septum (PA/IVS) is a spectrum of diseases with varying severity of right ventricle hypoplasia and potential for biventricular, univentricular, or hybrid repairs. Pessimistic outcome measures for PA/IVS may give way to optimism with the refinement of early diagnosis and early intervention to encourage right ventricle flow and optimize growth. To this end, PA/IVS has become a focus of innovative interventions (eg,fetal surgery) and new catheter-based and surgical techniques.

ISSN:0268-4705    

出版商:OVID    

年代:1999

数据来源: OVID