The inventions described in this patent application include i) a torqueable introducer sheath which is useable in conjunction with a transvascular passageway forming catheter to effect precise rotational control of the catheter; ii) an anchorable guide catheter which is useable in conjunction with an intravascular imaging catheter and a transvascular passageway-forming catheter to effect precise positioning and aiming of the passageway-forming catheter; iii) a passageway forming catheter having a torqueable proximal portion to facilitate precise rotational positioning of the distal portion of the catheter; iv) a deflectable-tipped passageway forming catheter, v) various markers and other apparatus useable in conjunction with any of the passageway-forming catheters to facilitate precise positioning and aiming of the catheter, and vi) an apparatus which may be formed within a catheter to prevent a member, apparatus of flow of material from being inadvertently advanced through a lumen of the catheter.