untreated , syncope occurred at less than or equal to 7 minutes of tilt alone ( 6 patients ) or tilt plus isoproterenol at less than or equal to 3 micrograms/min ( 4 patients ) and was associated with hypotension ( mean arterial pressure , 40 +/- 16 mm hg vs baseline 76 +/- 10 mm hg , p less than 0.001 ) and inappropriate heart rate slowing ( mean heart rate , 59 +/- 39 beats/min vs baseline 88 +/- 18 beats/min , p less than 0.005 ) .
C0022245
isoproterenol
C0428977
heart rate slowing