An extensible implantable medical device includes a body defining a lumen extending through the body. The lumen is configured to receive at least a portion of an implantable medical lead. The body includes a non-rectilinearly shaped portion. The non-rectilinearly shaped portion has a first shape spanning a first distance in a relaxed state. The non-rectilinearly shaped portion has a second, more rectilinear, shape spanning a second distance when subjected to a stretching force. The second distance is greater than the first distance. The non-rectilinearly shaped portion returns to the relaxed first shape upon release of the stretching force and is configured to assume the first shape when the lead is inserted into the lumen and no load is placed on the lead or the shaped body portion.