Elastic introducer sheath

1. A surgical access device comprising:

a sheath having an expandable section comprised of

a circumferentially continuous inner layer of a biocompatible material;

a non-circumferentially continuous wire structure defining along a length of the expandable section a plurality of first loop portions extending in a first radial direction and a plurality of second loop portions extending in a second radial direction, wherein respective first loop portions longitudinally overlap with respective second loop portions when the expandable section is in a collapsed configuration and wherein a longitudinal gap extends between respective first loop portions and respective second loop portions when the expandable section is in an expanded configuration; and

a non-circumferentially continuous outer layer of a biocompatible material, the outer layer being connected to the wire structure and to the inner layer to form a wall of the expandable section, the outer layer having a longitudinal gap when the expandable section is in the expanded configuration and having an overlap region when the expandable section is in the collapsed configuration.

2. The surgical access device of claim 1 , wherein the wire structure is curved to form a C-shape in a radial direction.

3. The surgical access device of claim 1 , wherein the wire structure has a sinusoid shaped wire pattern along a longitudinal direction.

4. The surgical access device of claim 1 , wherein the wire structure has a square shaped wire pattern along a longitudinal direction.

5. The surgical access device of claim 1 , wherein the sheath further comprises a proximal section having a first outer diameter that is greater than a second outer diameter of the expandable section.

6. The surgical access device of claim 5 , wherein the sheath further comprises a transition section longitudinally positioned between the proximal section and the expandable section, the transition section providing a tapered outer diameter from the first outer diameter of the proximal section to the second outer diameter of the expandable section.

7. The surgical access device of claim 1 , wherein when the expandable section is in the collapsed configuration a first fold in the inner layer is disposed around a first edge of the outer layer.

8. The surgical access device of claim 7 , wherein when the expandable section is in the collapsed configuration a second fold in the inner layer is disposed inward of a second edge of the outer layer.

9. A locally expandable surgical access device comprising:

a sheath having an expandable section comprised of

a curved non-circumferentially continuous wire structure extending along a length of the expandable section, wherein a longitudinal gap is defined between first end portions of the wire structure and opposing second end portions of the wire structure in a collapsed configuration of the expandable section, and wherein a width of the longitudinal gap increases in an expanded configuration of the expandable section;

a non-circumferentially continuous outer layer connected to the wire structure, the outer layer having a longitudinally-extending first edge and a longitudinally extending second edge, wherein a longitudinal gap is defined between the longitudinally extending first and second edges of the outer layer in the expanded configuration of the expandable section and wherein an overlap region of the outer layer is defined between the longitudinally extending first and second edges of the outer layer in the collapsed configuration of the expandable section; and

a circumferentially continuous inner layer connected to the outer layer to form a wall of the expandable section, wherein the inner layer and the outer layer are formed from biocompatible materials.

10. The locally expandable surgical access device of claim 9 , wherein the expandable section is expandable from a first diameter to a second diameter to allow passage of a transcatheter medical device.

11. The locally expandable surgical access device of claim 10 , wherein the expandable section is reducible from the second diameter to a third diameter.

12. The locally expandable surgical access device of claim 11 , wherein the third diameter is equal to the first diameter.

13. The locally expandable surgical access device of claim 9 , the expandable section further comprising a first fold in the inner layer disposed around the first edge of the outer layer in the collapsed configuration of the expandable section.

14. The locally expandable surgical access device of claim 13 , the expandable section further comprising a second fold in the inner layer disposed inward of the second edge of the outer layer in the collapsed configuration of the expandable section.

15. The locally expandable surgical access device of claim 14 , wherein the first fold and the second fold of the inner layer unfold and flatten in the expanded configuration of the expandable section.

16. The locally expandable surgical access device of claim 9 , wherein the wire structure includes a plurality of straight portions and a plurality of curved portions and wherein the first and second end portions are defined by the plurality of curved portions.

17. The locally expandable surgical access device of claim 9 , wherein the wire structure has a sinusoid pattern.

18. The locally expandable surgical access device of claim 9 , wherein the sheath further comprises a proximal section having a first outer diameter that is greater than a second outer diameter of the expandable section.

19. The locally expandable surgical access device of claim 18 , wherein the sheath further comprises a transition section longitudinally positioned between the proximal section and the expandable section, the transition section providing a tapered outer diameter from the first outer diameter of the proximal section to the second outer diameter of the expandable section.