three or more consecutive impulses at a rate not exceeding the upper limit of the inherent pacemaker; extreme range of impulse formation at the sinoatrial node is between 40 and 180 impulses per minute, that of the atrioventricular junction is normally 40-60 impulses per min, and the normal rate of the ventricular myocardium (idioventricular rhythm) is 20-40 impulses per min.
