System and methods for treating a bifurcation

1. A system for treating a bifurcated vessel, the system comprising:

a first delivery catheter comprising a first expandable member carrying a first stent collapsed onto the first expandable member, wherein the first expandable member is configured to deliver the collapsed first stent, wherein the first stent is expanded by expansion of the first expandable member, wherein the first stent has a sidewall having a sidehole;

a second delivery catheter comprising a second expandable member having a working length with a proximal portion and a distal portion, the second expandable member carrying a second stent collapsed onto the distal portion of the working length of the second expandable member, wherein the second expandable member is configured to deliver the collapsed second stent, wherein the second stent is expanded by expansion of the second expandable member, wherein the proximal portion of the working length of the second expandable member remains uncovered by the second stent during delivery of the first expandable member and second expandable member to the bifurcated vessel,

wherein the second delivery catheter extends through the sidehole while the first stent remains collapsed on the first expandable member,

wherein the second expandable member is distal to the first expandable member prior to and during delivery of the first expandable member and the second expandable member to the bifurcated vessel,

wherein the second delivery catheter is proximally retractable relative to the first expandable member,

wherein the proximal portion of the working length of the second expandable member is disposed under a proximal portion of the collapsed first stent during radial expansion of the second expandable member, and

wherein radial expansion of the second expandable member simultaneously expands the second stent, the sidehole, and the proximal portion of the collapsed first stent, while the second expandable member is slidably disposed under the proximal portion of the collapsed first stent and without expansion of a distal portion of the collapsed first stent.

2. The system of claim 1 , wherein the distal second expandable member has a cross-sectional profile smaller than a cross-sectional profile of the first expandable member.

3. The system of claim 1 , wherein the first stent is crimped onto the first expandable member and the second stent is crimped onto the second expandable member.

4. The system of claim 3 , wherein the first stent is non-uniformly crimped to the first expandable member.

5. The system of claim 4 , wherein the second radially expandable stent is uniformly crimped to the second expandable member.

6. The system of claim 1 , wherein the first expandable member or the second expandable member comprises a balloon.

7. The system of claim 1 , wherein each of the first delivery catheter and the second delivery catheter comprise an inflation lumen.

8. The system of claim 1 , wherein each of the first delivery catheter and the second delivery catheter comprise a guidewire lumen.

9. The system of claim 1 , wherein radial expansion of the second expandable member simultaneously expands the second stent along its full length, the sidehole, and the proximal portion of the collapsed first stent without expansion of the distal portion of the collapsed first stent.

10. The system of claim 1 , wherein the first catheter comprises a first radiopaque marker proximal to the first expandable member, wherein the second catheter comprises a second radiopaque marker proximal to the second expandable member, and wherein proximal retraction of the second delivery catheter relative to the first expandable member disposes the second expandable member under the proximal portion of the first stent when the first and second radiopaque markers are axially aligned with one another.