Controlled tissue ablation techniques

Apparatus and methods are described, including a method for use with tissue of a renal nerve (770) passing longitudinally within a wall of a renal artery (8) of a subject. Using one or more stimulating electrodes (850a, 850b) disposed within the renal artery, the tissue is stimulated by passing a stimulating current through the wall of the renal artery. Using a sensor (26), a rate of change of blood pressure of the subject is sensed, following the start of the stimulation of the tissue. In response to the rate of change, it is decided whether to ablate the tissue, and in response to deciding to ablate the tissue, the tissue is ablated. Other applications are also described.