The present invention provides a handheld device and method for treating an artery having atherosclerosis. The handheld device for treating an artery comprises a handle for holding the device,an effector adapted to the handle for carrying out the treatment on the arteries, said effector having an ablating means, anda feedback controller for controlling process of treatment. Advantageously, the device allows for treating the artery without invasion of the blood vessel lumen, without damaging the tunica intima of the artery, and more importantly, the device can be used for treating early and mid-stage plaque formation in the arterial wall, which goes undetected in routine angiography.
