A medical apparatus, including an insertion tube that includes an outer tube having a proximal end and a distal end configured for insertion into a body cavity, with a radial cutting window opening through a wall of the outer tube in proximity to the distal end. The insertion tube also includes an inner tube, contained in and configured to rotate within the outer tube and including a cutting blade that traverses the radial cutting window opening as the inner tube rotates. The medical apparatus further includes a conductive element disposed over an outer surface of the distal end of the insertion tube, and a conductor running along the insertion tube from the proximal to the distal end and coupled to provide energy to the conductive element.
