A dilatation catheter includes an inflation balloon having a variable diameter inflation profile. The balloon has a first inflation profile, in which it exhibits a substantially cylindrical central working profile. The first inflation profile of the balloon is achieved by inflating the balloon to a first inflation pressure. The balloon has a second inflation profile which is achieved by increasing the inflation pressure to a second, higher pressure. In the second inflation profile, a proximal segment and a distal segment of the balloon have a first inflated diameter and a central focal segment, separating the proximal and distal segments, has a second inflated diameter, such that the second inflated diameter is greater than the first inflated diameter.