USE OF CHOLINERGIC DRUGS IN PAROXYSMAL SUPRAVENTRICULAR TACHYCARDIA

Abstract
The effectiveness and usefulness of methacholine chloride in terminating attacks of paroxysmal tachycardia of supraventricular origin have become well established since Starr's introductory report in 1933.1 The distressing occurrence of varying degrees of heart block following the original injections of 100 mg. or more was largely overcome by the use of doses of 20 to 40 mg.2 Even these smaller doses often evoked unpleasant cholinergic effects. This led to the introduction of neostigmine as a substitute for3 or adjuvant to4 methacholine. Both agents are capable of evoking drastic effects by their action on the autonomic nervous system. Their proper use requires a clear understanding of their pharmacodynamic activity. Standard textbooks that deal with the treatment of acute attacks of supraventricular tachycardia almost invariably mention the use of both methacholine and neostigmine, as well as the commoner methods of therapy, such as various forms of vagal stimulation