in contrast , isoproterenol was associated with tachycardia and only a slight decline in arterial pressure in the 8 remaining patients with positive electrophysiologic tests and the 18 control subjects , and syncope developed in only 1 of the 8 patients with positive electrophysiologic tests and negative tilt tests ( 13 percent ) and 2 of the 18 control subjects ( 11 percent ) .
C0022245
isoproterenol
C0039231
tachycardia