Common supraventricular tachycardias: mechanisms and management.

Supraventricular tachycardias (SVTs) are common. Reentry is the most common of the underlying mechanisms. The most frequently observed narrow QRS complex SVTs are atrioventricular nodal reentrant tachycardia and atrioventricular reentrant tachycardia using an accessory pathway. All reentrant tachycardias share certain characteristics that distinguish them from automatic or triggered tachycardias. These characteristics include unidirectional block, delayed conduction, and recovery of excitability within an intact circuit. The characteristics of the reentrant circuit and the physiology of the pathways can be used to define treatments that may be efficacious and/or may have potential risk. Differentiation of SVTs is possible with careful application of monitoring, history taking, and electrophysiologic interventions such as programmed stimulation.

Dysrhythmia update. Differential diagnosis of supraventricular tachycardia in an elderly man.

An 82-year-old man was admitted to the hospital with a narrow complex tachycardia. This article presents his case history, examples of the dysrhythmia, and a differential diagnosis approach to identifying the source of the tachycardia. The mechanism of the tachycardia is described and diagrammed and the follow-up care of the patient presented.

Radiofrequency catheter ablation for supraventricular tachycardias: Part I.

Ablative therapy in the treatment of arrhythmias is an exciting development of the last decade. Although direct-current, high-energy shock can be effective treatment for many supraventricular tachycardias, clinicians are concerned about potential problems associated with its use. Drug therapy for arrhythmias has been inadequate, ineffective, poorly tolerated and fraught with toxic or proarrhythmic reactions. Because of its relative technical ease, high success rate and low complication rate, RFCA remains the therapeutic procedure of choice for patients with atrioventricular nodal reentrant supraventricular tachycardia. Other catheter ablation techniques such as laser, cryocatheter and microwave catheter are still being tested.

Sotalol hydrochloride (Betapace): a new antiarrhythmic drug.

Sotalol hydrochloride (Betapace), recently released by the Food and Drug Administration for general use, is used to treat a variety of ventricular and supraventricular tachyarrhythmias. The drug's dominant action is the result of combined nonselective beta-adrenergic antagonism (Class II effect) and monophasic action potential duration prolongation in all cardiac tissues (Class III effect). It causes less left ventricular depression than propranolol and has a low incidence of toxicity. It is a useful addition to the antiarrhythmic drug armamentarium. This article reviews the drug's pharmacokinetic, pharmacodynamic and electrophysiologic properties, clinical uses and potential side effects. Reports on the drug's use as an antianginal and antihypertensive agent are also discussed.

Radiofrequency catheter ablation of supraventricular tachycardias: clinical consideration and nursing care.

Radiofrequency catheter ablation is rapidly gaining acceptance as the treatment of choice for many types of symptomatic supraventricular tachycardia (SVT). Introduced in humans in 1987, the procedure has been met with enthusiasm because of its relative safety and high success rate in curing SVT. The typical patient with SVT can be both diagnosed and cured during the same electrophysiology study (EPS). Complications are few, with the majority of patients discharged in less than 48 hours. Nursing care centers on pre- and postprocedural teaching, assessing the effects of radiofrequency energy and implementing nursing orders to prevent postablation complications.

Idiosyncratic supraventricular tachycardia after epidural anesthesia.

During pregnancy, stress and vigorous exercise often result in pronounced tachycardia. Generally, a vagal stimulatory effort will interrupt the episode; however, intrapartum supraventricular tachycardia may not respond to vagal stimulation, necessitating drug therapy. This article is a case report of idiosyncratic supraventricular tachycardia following initiation of epidural analgesia; use of epinephrine was part of the test dose protocol. Adenosine, chosen for the lack of hypotensive effect associated with verapamil, was administered intravenously with immediate results. Fetal monitoring via scalp electrode provided evidence of fetal well-being during and after the episode.

Radiofrequency catheter ablation for supraventricular tachycardia.

Radiofrequency catheter-mediated ablation is a recently developed technique of achieving cure of certain rhythm disorders, notably supraventricular tachycardia. In less than a decade, it has evolved from a theoretic concept to first line therapy for many patients, including those in the pediatric age group. The most common types of arrhythmias amenable to catheter ablation include supraventricular tachycardia due either to an accessory pathway or A-V nodal reentry and atrial fibrillation with a rapid ventricular response refractory to medical therapy. Before the development of the technique, the only therapeutic options included either lifelong antiarrhythmic drugs or open heart surgery. The initial experiences with catheter ablative techniques used direct current shocks of up to 400 J, delivered to an intracardiac catheter from a standard defibrillator. This energy source has largely been replaced by radiofrequency current because of the substantially lower morbidity and greater efficacy. The treatment of patients with these tachyarrhythmias is evolving from a palliative approach to a curative one. With the current worldwide experience, complications are relatively rare and do not appear to differ from those associated with routine electrophysiologic testing or cardiac catheterization. The success rate is high, usually exceeding a 90% efficacy, but is dependent on the skill and experience of the operator. The technique, arrhythmias amenable to treatment, and the nursing implications before, during, and after the procedure are discussed in this article.