An introducer sheath includes an elongated outer sheath and an elongated inner sheath coaxially disposed within the outer sheath. The elongated outer sheath includes an outer sheath wall extending circumferentially about a longitudinal axis of the outer sheath to an extent greater than 180° and less than 360° to define an outer sheath slot. The elongated inner sheath includes an inner sheath wall extending circumferentially about a longitudinal axis of the inner sheath to an extent greater than the difference between 360° and the circumferential extent of the outer sheath wall, and less than 360° to define an inner sheath slot. The inner sheath is rotatable relative to the outer sheath to form an enclosed lumen when the outer and inner sheath slots are not aligned, and to form an open slot along the entire length of the introducer sheath when the outer and inner sheath slots are aligned.
