An implantable medical device comprising a housing, a set of active fixation tines (103) attached to a distal end (114) of the housing, the fixation tines each having a proximal end attached to the distal end of the housing, and a free distal end for engaging tissue； wherein the fixation tines are configured to be moveable between an extended position in which the free distal ends of the tines are distal of the distal end of the housing, and an engaged position in which the free distal ends of the tines are proximal of the distal end of the housing.
