The invention relates to a device for detaching parietal thrombi from a blood vessel, having a catheter along the catheter longitudinal extent of which at least one catheter section is provided, wherein the attributable catheter outer diameter of said catheter section can be changed by a means, and, in the attributable catheter wall of said catheter section, at least one wall opening is provided, which completely passes through the catheter wall, transversely with respect to the catheter longitudinal extent. The invention is characterized in that the catheter wall along the at least one catheter section is made of a resiliently deformable material, in that the catheter can be transferred, by the means which causes an external constraint acting on the catheter, from a state with a relatively small catheter outer diameter to a state with a relatively large catheter outer diameter, by way of a resilient change in shape, wherein the means is designed as a displacement body which can be introduced into the at least one catheter section, and in that with the omission of the external constraint the catheter autonomously assumes the state with the relatively small catheter outer diameter, due to the resilient resetting forces inherent in the material.
