Pressure sensing guidewires and methods of use

1. A pressure sensing guidewire having a distal end and a proximal end, the pressure sensing guidewire comprising:

a first tubular member having a distal portion and a proximal portion, the distal portion forming a distal cap having an inner surface;

a second tubular member disposed within the first tubular member, the second tubular member having a constant diameter over its length and comprising a plurality of flexibility-enhancing slots formed therein;

an optical pressure sensor disposed within the distal cap, wherein the optical pressure sensor includes a Fabry-Perot pressure sensor; and

a polymer fiber optic cable extending proximally from the optical pressure sensor and through the second tubular member, the optical pressure sensor disposed at a distal end of the polymer fiber optic cable;

wherein the second tubular member limits radial movement of the polymer fiber optic cable relative to the first tubular member and thus protects the optical pressure sensor from contacting the inner surface of the distal cap when the pressure sensing guidewire is subjected to bending.

2. The pressure sensing guidewire of claim 1 , wherein the polymer fiber optic cable extends proximally to a proximal end of the pressure sensing guidewire.

3. The pressure sensing guidewire of claim 1 , wherein the polymer fiber optic cable extends proximally and is operably connected to a glass fiber optic that extends proximally to a proximal end of the pressure sensing guidewire.

4. The pressure sensing guidewire of claim 1 , wherein the distal cap includes one or more apertures permitting blood to enter an interior of the distal cap.

5. The pressure sensing guidewire of claim 1 , wherein the distal portion of the tubular member includes a shapeable structure.

6. The pressure sensing guidewire of claim 1 , wherein the second tubular member extends proximally from the distal cap.

7. The pressure sensing guidewire of claim 6 , further comprising a coil disposed over at least a portion of the second tubular member.

8. The pressure sensing guidewire of claim 6 , further comprising a polymer sleeve disposed over at least a portion of the second tubular member.

9. A pressure sensing guidewire having a distal end and a proximal end, the pressure sensing guidewire comprising:

a first tubular member having a distal portion and a proximal portion;

a constant diameter cylindrical second tubular member extending distally from the distal portion of the first tubular member, the second tubular member having a proximal end, a distal end and a plurality of slots formed therein;

a distal cap extending distally from the distal end of the second tubular member;

an optical pressure sensor disposed within the distal cap, wherein the optical pressure sensor includes a Fabry-Perot pressure sensor; and

a polymer fiber optic cable extending proximally from the optical pressure sensor;

wherein the optical pressure sensor is disposed within the distal cap at a position that is less than 3 centimeters from the distal end of the pressure sensing guidewire, and wherein the optical pressure sensor is constrained from contacting the distal cap by the second tubular member constraining radial movement of the polymer fiber optic cable relative to the first tubular member.

10. The pressure sensing guidewire of claim 9 , wherein the polymer fiber optic cable extends proximally to a proximal end of the pressure sensing guidewire.

11. The pressure sensing guidewire of claim 9 , wherein the polymer fiber optic cable extends proximally and is operably connected to a glass fiber optic that extends proximally to a proximal end of the pressure sensing guidewire.

12. The pressure sensing guidewire of claim 9 , wherein the distal cap includes one or more apertures permitting blood to enter an interior of the distal cap.

13. The pressure sensing guidewire of claim 9 , further comprising a coil disposed over at least a portion of the second tubular member.

14. The pressure sensing guidewire of claim 9 , further comprising a polymer sleeve disposed over at least a portion of the second tubular member.

15. A method of using a guidewire including a first tubular member having a distal portion and a proximal portion, the distal portion forming a distal cap having an inner surface, an optical pressure sensor disposed within the distal portion of the first tubular member and a polymer fiber optic cable extending proximally from the optical pressure sensor, wherein the optical pressure sensor includes a Fabry-Perot pressure sensor, the optical pressure sensor constrained against contacting the inner surface of the distal cap via a constant diameter cylindrical second tubular member disposed within the first tubular member with the polymer fiber optic cable extending therethrough, the constant diameter cylindrical second tubular member comprising a plurality of flexibility-enhancing slots formed therein, the method comprising:

advancing the guidewire through a patient's vasculature to a position proximate a lesion;

measuring a pressure proximal the lesion;

advancing the guidewire through the lesion such that the pressure sensor is distal the lesion; and

measuring a pressure distal the lesion.

16. The method of claim 15 , wherein measuring a pressure proximal the lesion precedes advancing the guidewire through the lesion.

17. The method of claim 15 , further comprising, subsequent to advancing the guidewire through the lesion, withdrawing the guidewire prior to measuring a pressure proximal the lesion.

18. The method of claim 15 , wherein advancing the guidewire through the lesion comprises advancing the guidewire through the lesion such that a distal end of the guidewire extends past the lesion a distance of less than 3 centimeters.

19. The method of claim 15 , wherein the guidewire includes a shapeable distal portion, and the method further comprises shaping the shapeable distal portion prior to advancing the guidewire through a patient's vasculature to a position proximate a lesion.