A method is provided, comprising: (1) applying an excitatory current to renal nerve fibers of a subject； (2) determining a change in a parameter of the subject in response to the excitatory current, the parameter being a fastest rate of increase in arterial pressure during a systolic upstroke of an arterial pressure wave of the subject； (3) in response to the change, deciding whether to ablate the renal nerve fibers； and (4) in response to the deciding, applying ablation energy to the renal nerve fibers. Other embodiments are also described.
