Abstract: In a coiled wire medical lead structure, such as a transvenous, endocardial cardiac pacemaker and/or cardioverter/defibrillator lead, an improved mechanical structure for strengthening the lead to enable its intact removal by traction after a period of chronic implant, one or more normally relaxed, nonextensible filaments loosely contained within the insulating sheath and having proximal and distal ends mechanically coupled to the connector and electrode shank, respectively, of the lead operate as means for restraining the stretching of the lead body to a stretched length exceeding the relaxed, predetermined length by an amount sufficient to allow the lead to be stretched without breaking in its normal usage and during removal by traction. In certain embodiments, the filament may take the form of a loosely woven fabric sheath formed in a tubular shape and fitted in the space between the lead body outer sheath and one or more coiled wire conductors.