AXIALLY COMPRESSIBLE FLARED STENTS AND APPARATUS AND METHODS FOR DELIVERING THEM

1 . A stent comprising a tubular member including first and second ends defining a longitudinal axis therebetween and a plurality of cells disposed between the first and second ends, the tubular member being expandable from a contracted condition to an enlarged condition, the stent comprising:

a first flaring portion configured to flare outwardly when the stent is expanded from the contracted condition to the enlarged condition; and

a second main portion adjacent the first portion, the second portion comprising a plurality of bands of cells connected to one another such that the main portion is axially compressible when the stent is expanded from the contracted condition to the enlarged condition.

2 . The stent of claim 1 , wherein the first flaring portion has a radial strength less than the main portion.

3 . The stent of claim 1 , wherein adjacent bands of cells of the main portion are only intermittently connected to one another.

4 . The stent of claim 1 , wherein each of the bands of cells of the main portion comprises axial segments connected by alternating curved segments around a circumference of the stent, and wherein a plurality of links extend between opposing curved segments of adjacent bands of cells to connect the adjacent bands of cells.

5 . The stent of claim 4 , wherein the links extend between only some of the opposing curved segments of adjacent bands of cells.

6 . The stent of claim 4 , wherein the links extend between only every other set of opposing curved segment of adjacent bands of cells.

7 . The stent of claim 4 , wherein at least one set of unconnected opposing curved segments is disposed between opposing curved segments connected by links.

8 . The stent of claim 1 , wherein the first flaring portion comprises:

a first set of cells disposed at the first end, the first set of cells comprising first axial segments in the contracted condition; and

a second set of cells disposed adjacent the first set of cells, the second set of cells comprising second axial segments in the contracted condition,

wherein the first axial segments transition to extend at least partially circumferentially in the expanded configuration, and the second axial segments transition to extend at least partially radially outwardly in the expanded configuration.

9 . The stent of claim 8 , wherein a ratio of a diameter of the first flaring portion to the second main portion in the enlarged condition is between about 1.1 and 1.8.

10 . The stent of claim 1 , wherein the first flaring portion is connected to the second main portion by a plurality of connectors comprising curvilinear segments having a thickness and a width, at least one of the thickness and the width being thinner than segments comprising the first flaring portion.

11 . A stent comprising a tubular member including first and second ends defining a longitudinal axis therebetween and a plurality of cells disposed between the first and second ends, the tubular member being expandable from a contracted condition to an enlarged condition through an intermediate condition, the stent comprising:

a first flaring portion configured to flare outwardly when the stent is expanded from the contracted condition to the intermediate condition, the first flaring portion comprising a first set of cells at the first end and a second set of cells adjacent the first set of cells, the second set of cells comprising segments extending substantially axially in the contracted condition;

a second main portion adjacent the first flaring portion, the second main portion comprising a plurality of bands of cells; and

a plurality of links intermittently extending between adjacent bands of cells of the second main portion to allow axial compression or expansion of the adjacent bands of cells when the stent is expanded from the contracted condition to the expanded condition.

12 . The stent of claim 11 , wherein a ratio of a diameter of the first end portion to the second end in the intermediate condition is between about two and five.

13 . The stent of claim 12 , wherein a ratio of a diameter of the first end portion to the second end in the enlarged condition is between about 1.1 and 1.8.

14 . An apparatus for treating an ostium communicating between a main body lumen and a branch body lumen, comprising:

an elongate member comprising a proximal end, a distal end sized for introduction into the main body lumen and the branch body lumen;

a first expandable member on the distal end, the first expandable member being expandable from a collapsed configuration to a generally spherical expanded configuration;

a second expandable member on the distal end adjacent the first expandable member, the second expandable member being expandable from a collapsed configuration to a substantially cylindrical expanded configuration; and

a stent on the distal end over the first and second expandable members, the stent comprising a first flaring portion overlying a portion of the first expandable member, and a second main portion overlying the second expandable member, the second main portion being axially compressible during expansion of at least one of the first and second expandable members.

15 . The apparatus of claim 14 , wherein the first expandable member comprises a semi-compliant or substantially compliant balloon.

16 . The apparatus of claim 15 , wherein the second expandable member comprises a balloon that is less compliant than the first expandable member.

17 . The apparatus of claim 15 , wherein the second expandable member comprises a substantially non-compliant balloon.

18 . The apparatus of claim 17 , wherein the first and second expandable members require respective inflation pressures to expand to the expanded configuration, and wherein the inflation pressure of the first expandable member is less than the inflation pressure of the second expandable member.

19 . The apparatus of claim 14 , wherein the first expandable member is expandable independently of the second expandable member using an inflation pressure that is less than an inflation pressure necessary to expand the second expandable member.

20 . The apparatus of claim 14 , wherein the first flaring portion of the stent comprises:

a first set of cells disposed at the first end;

a second set of cells disposed adjacent the first set of cells, and

a plurality of flexible connectors connecting the second set of cells to the second portion of the stent,

wherein the second set of cells comprises struts connected to curved segments, the curved segments having a lower yield strength than the struts.

21 . The apparatus of claim 20 , wherein the struts are directed from a generally axial orientation towards a generally radially outward orientation when the first expandable member is expanded.

22 . The apparatus of claim 20 , wherein the struts are directed from the generally radially outward orientation in the flared condition towards a circumferential orientation when the second expandable member is expanded.

23 . The apparatus of claim 20 , the first set of cells comprising struts that extend substantially axially when the stent is in a contracted condition, the first end portion flaring such that the struts are directed towards a circumferential orientation in the flared condition.

24 . The apparatus of claim 20 , wherein the connectors comprise curvilinear segments having a thickness and a width, at least one of the thickness and the width being thinner than segments comprising the first end portion.

25 . The apparatus of claim 14 , further comprising a source of inflation media communicating with an interior of the first expandable member for delivering first and second predetermined volumes into the first expandable member to partially and fully expand the first expandable member, respectively.

26 . The apparatus of claim 25 , wherein the source of inflation media comprises a syringe comprising a barrel including inflation media therein and a plunger, the barrel comprising first and second markers such that, when the plunger is depressed successively to the first and second markers, the first and second predetermined volumes are delivered into the interior of the first expandable member, respectively.

27 . A method for expanding a stent, comprising:

providing a stent on one or more expandable members, the stent comprising first and second ends, a first flaring portion, and a second main portion connected to the first flaring portion;

expanding an expandable member to flare the first flaring portion;

expanding an expandable member to expand the second main portion to an enlarged condition, thereby causing the second main portion to shorten axially.

28 . A method for delivering a stent within an ostium communicating between a main body lumen and a branch body lumen, the stent comprising first and second ends, a first flaring portion, and a second main portion, the method comprising:

introducing the stent into the main body lumen with the stent in a contracted condition;

flaring the first flaring portion to a first expanded size;

advancing the stent into the ostium with the first flaring portion flared;

expanding the stent such that the second main portion expands within the branch body lumen; and

expanding the stent further such that the first flaring portion expands to a second expanded size greater than the first expanded size, wherein the second main portion foreshortens when at least one of the second main portion expands within the branch body lumen and the first flaring portion expands to the second expanded size.