Infusion liquid is expeled distally of an ablation burr (12; 60; 80) for washing a blood vessel lesion (L) being treated by the burr (12; 60; 80). The infusion liquid can be aspirated in a proximate direction to carry the infusion liquid and loose ablated particles of the lesion (L) away from the treatment area. The infusion liquid can be supplied through one or more passages (32; 38; 62; 64) in the burr (12; 60). In the addition to distally extending passages (32; 38; 62; 64), the barr can include transverse passages (36; 58; 62; 64)extending at last partly in a proximate direction, with the distally extending and proximately extending passages sized so that only a minor portion of the infusion liquid is expeled distally.
