Described is a medical system for implantation within a patients body. The medical system comprises: an implantable medical device a lead having a proximal end, a distal end and an intermediate portion located between the proximal and distal ends, wherein the proximal end has a connector connecting the lead to the implantable medical device, and the intermediate portion includes a portion having a reduced outer diameter compared to an outer diameter of a remainder of the intermediate portion and an anchoring device for anchoring the lead within the patients body, the anchoring device comprising a sleeve having an inner lumen extending therethrough that accommodates the reduced outer diameter portion of the lead, wherein axial movement of the anchoring device along the lead is limited to within the reduced outer diameter portion of the lead.
