An implantable lead for sensing mechanical activity of a human heart has an insulating polymeric tube extending from a proximal end to a distal end of the lead, an electrical conductor provided in the lumen of the polymeric tube, and a sensor connected to the conductor at the distal end thereof. The polymeric tube is provided with a conductive surface layer along the inner face between the polymeric tube and the electrical conductor, the conductive surface layer being in electrical contact with this conductor. Accumulation of electrical charges between the electric conductor and the polymeric tube is thereby prevented.
