Systems and methods for delivering a stent to a body lumen
A stent delivery system configured to deliver a stent to a target region of a body lumen may include a catheter; a stent associated with the catheter, the stent having a first region and a second region; a balloon associated with the catheter, the balloon having a first balloon portion associated with the catheter proximate the first region of the stent and a second balloon portion associated with the catheter proximate the second region of the stent; and a sheath about the stent and the balloon, the sheath maintaining the stent in an undeployed configuration for delivery to a target region of a body lumen. The sheath may comprise a first sheath region configured to split at a first pressure thereby permitting the first region of the stent to assume a deployed configuration, a second sheath region configured to split at a second pressure thereby permitting the second region of the stent to assume a deployed configuration, the second pressure being greater than the first pressure and the first pressure being insufficient to cause the second region of the sheath to split, a split-stopping structure between the first and second sheath regions, the split-stopping structure being configured to prevent a split from propagating from the first sheath region to the second sheath region at the first pressure.
1. Method for delivering a stent to a target region of a body lumen, the method comprising:
positioning a stent delivery system at the target region of the body lumen, the delivery system comprising a stent associated with a balloon catheter and a sheath maintaining the stent in an undeployed configuration;
inflating a first balloon portion to a first pressure so as to cause the sheath to split at a first region of the sheath, the first balloon portion being proximate a first region of the stent, said splitting of the first region of the sheath permitting the first region of the stent to expand to a deployed configuration;
preventing propagation of the split from the first region of the sheath to a second region of the sheath at the first pressure with a split-stopping structure of the sheath, said split-stopping structure being between the first and second regions of the sheath; and
inflating a second balloon portion to a second pressure so as to cause the sheath to split at the second region of the sheath until the split at the second region of the sheath reaches the split-stopping structure of the sheath, the second pressure being greater than the first pressure and the first pressure being insufficient to cause the second region of the sheath to split, the second balloon portion being proximate a second region of the stent, said splitting of the second region of the sheath permitting the second region of the stent to expand to a deployed configuration.
2. The method of claim 1 , wherein the step of inflating the first balloon portion causes a proximal end of the sheath to split.
3. The method of claim 2 , wherein the proximal end of the sheath splits along a pre-formed slit.
4. The method of claim 1 , wherein the step of inflating the first balloon portion causes a distal end of the sheath to split.
5. The method of claim 4 , wherein the distal end of the sheath splits along a pre-formed slit.
6. The method of claim 1 , wherein said first balloon portion has at least one of greater compliance and greater diameter relative to the second balloon portion.
7. The method of claim 6 , wherein the first and second balloon portions comprise separate balloons.
8. The method of claim 7 , wherein the first balloon portion and the second balloon portion each has its own inflating assembly.
9. The method of claim 6 , wherein the first balloon portion and the second balloon portion comprise a single balloon structure.
10. The method of claim 1 , further comprising removing the catheter and the sheath from the body lumen.
11. A stent delivery system configured to deliver a stent to a target region of a body lumen, the system comprising:
a catheter, the catheter including a balloon at its distal end;
a stent associated with the catheter about the balloon, the stent having a first region and a second region; and
a sheath about the stent and the balloon, the sheath maintaining the stent in an undeployed configuration for delivery to a target region of a body lumen, the sheath comprising
a first sheath region configured to split at a first pressure thereby permitting the first region of the stent to assume a deployed configuration,
a second sheath region configured to split at a second pressure thereby permitting the second region of the stent to assume a deployed configuration, the second pressure being greater than the first pressure and the first pressure being insufficient to cause the second region of the sheath to split, and
a split-stopping structure between the first and second sheath regions, the split-stopping structure being configured to prevent a split from propagating from the first sheath region to the second sheath region at the first pressure, the split-stopping structure comprising a region having a modified orientation of polymer molecules relative to the first and second sheath regions.
12. The system of claim 11 , wherein the balloon has a first balloon portion proximate the first region of the stent and a second balloon portion proximate the second region of the stent.
13. The system of claim 12 , wherein the first balloon portion is configured to inflate at the first pressure and the second balloon portion is configured to inflate at the second pressure, the second pressure being greater than the first pressure.
14. The system of claim 12 , wherein said first balloon portion has at least one of greater compliance and greater diameter relative to the second balloon portion.
15. The system of claim 14 , wherein the first and second balloon portions comprise separate balloons.
16. The system of claim 15 , wherein the first balloon portion and the second balloon portion each has its own inflating assembly.
17. The system of claim 14 , wherein the first balloon portion and the second balloon portion comprise a single balloon.
18. The system of claim 12 , wherein the first sheath region comprises a proximal end of the sheath configured to split distally when the first balloon portion is inflated to the first pressure until the split reaches the split-stopping structure of the sheath.
19. The system of claim 18 , wherein the second sheath region comprises a distal end of the sheath configured to split proximally when the second balloon portion is inflated to the second pressure at least until the split reaches the split-stopping structure of the sheath.
20. The system of claim 12 , wherein the first sheath region comprises a distal end of the sheath being configured to split proximally when the first balloon portion is inflated until the split reaches the split-stopping structure of the sheath.
21. The system of claim 20 , wherein the second sheath region comprises a proximal end of the sheath configured to split distally when the second balloon portion is inflated to the second pressure at least until the split reaches the split-stopping structure of the sheath.
22. The system of claim 11 , wherein the split-stopping structure comprises a pre-formed aperture in the sheath.
23. The system of claim 11 , wherein the split-stopping structure comprises a circumferential band having a thickened cross-section.
24. The system of claim 11 , wherein the catheter and the sheath are configured to be removed from a patient's cardiovascular system after the stent achieves a deployed configuration.
25. The system of claim 11 , wherein the difference between the second pressure and the first pressure is a measurable difference.
26. The system of claim 25 , wherein the difference between the second pressure and the first pressure is at least 1 atmosphere.
27. The system of claim 11 , wherein the first pressure is about 3 to 4 atmospheres, and the second pressure is about 8 to 10 atmospheres.
28. The system of claim 11 , wherein at least one of the first region of the sheath and the second region of the sheath has a pre-formed slit.
29. The system of claim 11 , wherein a deployed configuration of the stent comprises the first region of the stent having a flared geometry and the second region of the stent having a substantially cylindrical geometry.