Various embodiments of an endovascular sheath include a shaft portion with an interior lumen and an exit opening. The sheath may be introduced into a blood vessel along a guidewire that has already been placed within the vessel (typically via a Seldinger needle technique). Along the shaft is an opening that permits exit of a second guidewire introduced into the sheath lumen. The sheath may include, within the lumen, one or more features that encourage exit of the second guidewire through the opening at an optimal angle. A secondary lumen carries a stiffening wire for procedures involving tortuous vascular anatomy.
