An introducer system for implantation of pacemaker leads into the venous system of the human heart through the coronary sinus is comprised of a flexible, elongate, outer elongate element having a first shape or bias along a portion. The first shape on the outer element may be prebiased or may be initially straight and subsequently biased once deployed in the body chamber. A flexible, elongate, telescopic inner elongate element has a second shape or bias on its distal portion and has the first shape or bias on a more proximal portion. The inner elongate element is telescopically disposed in the outer sheath. The outer and inner elongate elements are rotatable with respect to each other, such that when the inner elongate element is distally extended from the outer sheath, there exists an angular orientation between the inner and outer sheaths which is congruent, when there is at least partial alignment between the distal portion of the outer elongate element and the more proximal portion of the inner sheath, both having the first shape or bias. This results in the rotation of the distal second shape or curve of the inner elongate element into a predetermined three dimensional location.