Apparatus and methods are described, including identifying a subject as suffering from hypertension. In response to the identifying (a) a radius of curvature of a first set of at least three regions of an arterial wall of the subject is increased at a given longitudinal location, while (b) allowing the first set of regions of the arterial wall to pulsate. A device is implanted inside the artery at the longitudinal location such that the device applies pressure to the arterial wall at a second set of at least three regions of the artery, but does not contact the first set of regions, the first set of regions and the second set of regions alternating with each other. Other embodiments are also described.