A tool for protecting a cardiac stimulating lead from damage upon passing through a hemostasis valve of a vascular introducer in the course of an implantation procedure comprises a splittable, peal-away sheath that is rendered sufficiently rigid by a tool dilator or placement of the lead body within the sheath so that the combination can be forced through a self-closing aperture formed through the hemostatic valve member. The use of the tubular sheath in breaching the self-closing aperture shields the lead electrodes and any covering that may be present from becoming distorted as well as from contamination by silicon oil commonly found in vascular introducers having a hemostasis valve.