patients having either or both of the following anomalies are used : 1 ) persistent sinus bradycardia ( sinus cycle length greater than 1000 msec ) , or documented episodes of sinoatrial block or arrest and/or 2 ) maximum corrected sn recovery time of longer than 525 msec before and after atropine .
C0037188
sinoatrial block
C0004259
atropine