Apparatus and methods for recannalization, valve repair and replacement
A scaffold is mounted on a balloon of a balloon catheter. The scaffold has closed cells which deform upon balloon expansion and generate forces that cause struts or other components of the scaffold to deflect outwardly to a diameter that is greater than the inflated diameter balloon. The deflected struts apply forces to fracture plaque of other hardened lesions and also form an annular gap surrounding the balloon to provide for bypass flow of blood or other body fluids. A sheath may be located over the deflected struts to protect adjacent tissue structures from the deflected struts and/or to further define the gap.
1. A scaffold comprising:
a tubular body configured to be carried over a balloon on a balloon catheter, said body including a plurality of deformable closed cells arranged in axial columns and circumferential rings, wherein axially adjacent cells are connected at axial connection points and circumferentially adjacent cells are connected at circumferential connection points; and
deformable struts extending between the axial connection points within at least some of the deformable cells, wherein each strut includes a first segment and a second segment which meet at configured so that a mid-portion of the strut deflects radially outwardly as the cell axially shortens as the tubular body is radially expanded by the balloon, wherein the mid-portion is biased to open radially outwardly as the strut is axially compressed by the axial shortening of the cell, wherein the mid-portion of the strut includes a force distribution pad comprising an open frame having a first circumferentially oriented beam attached to an inner end of the first segment of the deformable strut and a second circumferentially oriented beam attached to an inner end of the second segment of the deformable strut, wherein remote ends of each deformable strut segment are attached to the axial attachment points of the cell, and wherein each circumferentially oriented beam torques about its axis as the tubular body is radially expanded by the balloon and the deformable strut deflects radially outwardly.
2. A scaffold as in claim 1 , wherein the deformable struts are distributed uniformly over one or more circumferential regions of the tubular body.
3. A scaffold as in claim 1 , wherein the deformable struts are distributed uniformly over one or more axial regions of the tubular body.
4. A scaffold as in claim 1 , wherein the deformable struts are distributed uniformly over the entire tubular body.
5. A scaffold as in claim 1 , wherein the cells in one or more circumferential regions of the tubular body do not have the deformable struts therein.
6. A scaffold as in claim 1 , wherein the cells in a first circumferential region of a first end of the tubular body and in a second circumferential region of a second end of the tubular body do not have the deformable struts therein.
7. A scaffold as in claim 1 , wherein the cells are diamond-shaped.
8. A scaffold as in claim 1 , wherein the cells are defined by adjacent separate rings.
9. A scaffold as in claim 1 , wherein the cells are defined by adjacent zig-zag rings.
10. A scaffold as in claim 1 , wherein the open frame is rectangular or circular.
11. A scaffold as in claim 1 , wherein the ends of each segment of the deformable strut which are attached to the axial connection points are bifurcated.
12. A scaffold as in claim 1 , further comprising a sheath disposed coaxially over at least a portion of the tubular body.
13. An assembly comprising:
a scaffold as in claim 1 ; and
a balloon catheter having proximal and distal ends and a balloon disposed near the distal end thereof, wherein the scaffold is disposed over the balloon.
14. An assembly as in claim 13 , further comprising a sheath disposed coaxially over the scaffold and attached to the catheter at locations distal to the balloon and proximal to the balloon.