An introducer system for use with a pacemaker lead includes a plastic sheath compatible for insertion within a body, a first end configured for insertion into the body with a second end extending out of the body. A central lumen of the sheath is configured to permit introduction of the lead and includes a flexible, kink-resistant section smooth on its outer surface with a helical pleat defining a helical groove enabling a conductor extending from the mapping probe to the pacing system analyzer to be received in the helical groove of the sheath. A mapping probe at the first end of the sheath is connectable to a pacing system analyzer for seeking a location on the myocardial surface of the heart or an endocardial location at which optimal pacing parameters can be achieved prior to implantation of the lead.