Dual lumen sheath for arterial access

A sheath assembly for the insertion of a percutaneous pump, the sheath assembly comprising: a tubular sheath body dimensioned for insertion into a blood vessel through a vessel aperture and including: a wall having a proximal end portion, a distal end portion, a longitudinal axis, an outer surface, and an inner surface defining a first lumen substantially parallel to the longitudinal axis, wherein the first lumen is dimensioned to allow passage of a portion of the percutaneous pump; a second lumen disposed within the wall between the inner surface and the outer surface and extending from the proximal end portion to the distal end portion, wherein the second lumen is dimensioned for passage of a guidewire; and a stylet positioned to substantially occlude the second lumen, wherein the stylet has a proximal end releasably secured to the sheath assembly.