Effect of Propranolol on Normal and Abnormal Sinus Node Function

During the last decade, propranolol has been used clinically in the management of patients with arrhythmias, angina pectoris and hypertension (1–8). However, in man little data are available pertaining to the electrophysiological effects of propranolol on the normal sinus node function. In most of the previous studies the effect of propranolol has been analyzed regarding only one parameter of sinus node function, i.e. the changes in spontaneous cycle length or rate. Despite isolated reports in man, published data on the effects of propranolol on other parameters of sinus node function are limited (9–15). In view of its extensive clinical use in patients with various types of arrhythmias, especially supraventrl- cular tachycardias (SVT), i.e. atrial fibrillation, atrial flutter, or atrial tachycardia, which inherently produce overdrive suppression of the sinus node, it is of clinical importance to learn the effects of propranolol on various parameters of sinus node function, both in patients with normal and abnormal sinus node function. The purpose of this paper is to present our data on the effects of intravenous propranolol on 3 parameters of sinus node function: 1) spontaneous cycle length, 2) sinoatrial conduction time and 3) sinus node recovery time.