the tilt test alone ( i.e. , without isoproterenol ) induced symptomatic bradycardia or hypotension in 1 of the 9 patients with positive electrophysiologic tests ( 11 percent ) , 4 of the 15 patients with negative electrophysiologic tests ( 27 percent ) , and none of the controls .
C0022245
isoproterenol
C0428977
bradycardia