A thermal atherectomy catheter has a tip of high magnetic permeability cylindrical stem with an enlarged head at one end and an enlarged collar at the other end, a coil of wire wrapped about the stem adjacent the head and removed from said collar, a sleeve of ferromagnetic material disposed about the coil and a second sleeve of non-magnetic outer sleeve extending between and of the diameter of the head and collar to define a space between the sleeves whereby the outer sleeve to collar are maintained at a lower temperature than the head.