A spreader for the atrium of the heart is disclosed, particularly for the exposure of the mitral valve, having a thin-walled axially continuous hollow retractor body, the diameter of which expands from a distal edge to a proximal edge. The wall of the retractor body is made of an elastically deformable flat material, preferably of a shape memory metal. At the proximal edge of the retractor body, a receptacle is arranged, into which a fixing rod for positioning and fixing the retractor body can be inserted.
