sick sinus syndrome is applied to the following arrhythmias providing they are not iatrogenically induced : ( 1 ) sinus bradycardia usually unresponsive to atropine therapy or exercise , ( 2 ) sino-atrial block or arrest with long pauses , and ( 3 ) alternating bradycardia or tachycardia .
C0004259
atropine
C0039231
tachycardia