Patent ID: 8535294

Claim:
A sheath for accessing a patient's vascular system, the sheath having a tubular shaft comprising an interior plastic coating, a wire layer, and an exterior plastic coating, the wire layer comprising at least two flat wire helical coils being made from different metals, wherein at least one flat wire comprises cobalt chromium, all the wires in the wire layer being wound such that all of the wires in the wire layer are non-overlapping and non-touching and wound in the same direction, where most of the length of the sheath is a proximal portion that is stiffer as to its bending characteristic as compared to a shorter distal portion of the sheath that has increased flexibility, the increased flexibility of the distal portion of the sheath being accomplished by having a greater separation between the helical coils in that distal portion as compared to a lesser separation between the helical coils at the longer, proximal portion of the sheath.