after oral disopyramide 150 mg 3 times daily ( mean plasma level , 3.0 +/- 0.64 micrograms/ml ) , all patients tolerated 10 minutes of both tilt and tilt plus isoproterenol ( maximum dose , 3 micrograms/min ) without symptoms , hypotension ( mean arterial pressure ; tilt 1 min , 79 +/- 7 mm hg vs tilt 10 min , 77 +/- 8 mm hg , difference not significant ) or bradycardia ( mean heart rate ; tilt 1 min , 81 +/- 12 beats/min vs tilt 10 min , 83 +/- 11 beats/min , difference not significant ) .
C0022245
isoproterenol
C0428977
bradycardia