Electrophysiology of beta blockers in supraventricular arrhythmias

Abstract

β-adrenergic blocking agents are efficacious in the treatment of patients with a variety of supraventricular tachycardias, based directly on their capacity to counter the effects of β-adrenergic stimulation on sinus and atrioventricular nodal tissue. Specifically, β blockers depress sinus node automaticity and inhibit atrioventricular nodal function by prolonging refractoriness and slowing conduction. Supraventricular arrhythmias that depend on these structures either for perpetuation or for conduction to the ventricles are predictably sensitive to β blockade. These arrhythmias include sinus tachycardia, sinoatrial reentrant, atrioventricular nodal reentrant (dual pathway) and atrioventricular reciprocating (concealed bypass tract) tachycardias, as well as atrial flutter and fibrillation, β blockers may also be used, in selected patients, to inhibit catecholamine-facilitated accessory pathway function by prolonging refractoriness. β blockers offer particular clinical advantages, including an acceptable side-effect profile, titratable effect, varied pharmacology and reasonable concordance between efficacy of parenteral and oral dosage forms. The key element in the most effective use of these drugs appears to be an accurate arrhythmia diagnosis that allows for the most appropriate application of a reliable treatment form.