Occlusion-crossing devices

1. An occlusion crossing system, the system comprising:

an outer shaft defining a lumen and a distal opening that is angled relative to a central axis of the outer shaft to form a tapered distal end, and a first engagement region within the lumen; and

an inner shaft extending within the lumen and configured to rotate with respect to the outer shaft, the inner shaft including a distal end having a fluted tip with cutting edges that are configured to extend through the distal opening of the outer shaft, a side-facing optical coherence tomography (OCT) imaging window on a lateral side of the inner shaft at a distal region of the inner shaft, and a second engagement region on an outer surface of the inner shaft configured to engage with the first engagement region to limit a distal movement of the inner shaft within the outer shaft;

wherein when the cutting edges are fully extended distally through the distal opening of the outer shaft, the tapered distal end of the outer shaft is configured to occlude the OCT imaging window at a defined rotational position as the inner shaft is rotated relative to the outer shaft to provide a registration mark for OCT imaging.

2. The system of claim 1 , wherein the outer shaft comprises a backbone region at a distal end portion of the outer shaft that is configured to bias lateral bending of the distal end portion in a plane that includes a midline of the central axis and the tapered distal end.

3. The system of claim 1 , wherein the distal opening of the outer shaft is circumferentially beveled.

4. The system of claim 1 , wherein the inner shaft is configured to be removed proximally from the outer shaft.

5. The system of claim 1 , wherein the second engagement region comprises a ring having a rounded profile.

6. The system of claim 1 , wherein the inner shaft comprises a fiber optic coupled to the OCT imaging window and extending proximally through the inner shaft.

7. The system of claim 1 , further comprising a proximal attachment configured to couple the inner shaft with a rotational driver and an imaging sub-system.

8. The system of claim 1 , wherein the side-facing OCT imaging window is adjacent to the fluted tip.

9. The system of claim 1 , wherein the side-facing OCT imaging window is configured to overlap axially with a first portion of the tapered distal end of the outer shaft to not overlap axially with a second portion of the tapered distal end of the outer shaft, wherein the first portion of the tapered distal end is configured to occlude the OCT imaging window at the defined rotational position.

10. The system of claim 1 , wherein a distal end region of the outer shaft is configured to bend in a predetermined direction when the second engagement region of the inner shaft is driven distally against the first engagement region of the outer shaft.

11. The system of claim 1 , wherein the first engagement region comprises an annular lip.

12. The system of claim 1 , wherein the tapered distal end is shaped to act as a wedge or scoop for facilitating pushing through an occlusion within a blood vessel.

13. An occlusion crossing system, the system comprising:

an outer shaft defining a lumen and a distal opening that is angled relative to a central axis of the outer shaft to form a tapered distal end, a first engagement region within the lumen, and a backbone region at a distal portion of the outer shaft that is configured to bias lateral bending of the distal portion in a plane that includes a midline of the central axis and also includes the tapered distal end; and

an inner shaft extending within the lumen and configured to rotate with respect to the outer shaft, the inner shaft including a distal end having a fluted tip with cutting edges that are configured to extend through the distal opening, a side-facing optical coherence tomography (OCT) imaging window on a lateral side of the inner shaft at a distal region of the inner shaft, and a second engagement region on an outer surface of the inner shaft configured to engage with the first engagement region to limit a distal movement of the inner shaft within the outer shaft;

wherein when the cutting edges are fully extended distally through the distal opening of the outer shaft, the tapered distal end of the outer shaft is configured to occlude the OCT imaging window at a defined rotational position as the inner shaft is rotated relative to the outer shaft while the first engagement region is engaged with the second engagement region to provide a registration mark for OCT imaging indicating the direction of bending.

14. The system of claim 13 , wherein the distal opening of the outer shaft is circumferentially beveled.

15. The system of claim 13 , wherein the inner shaft is configured to be removed proximally from the outer shaft.

16. The system of claim 13 , wherein the inner shaft comprises a fiber optic coupled to the OCT imaging window and extending proximally through the inner shaft.

17. A method of crossing an occlusion in a vessel, the method comprising:

advancing an outer shaft into the vessel distally so that a tapered distal end of the outer shaft, which is defined by an opening of the outer shaft that is angled relative to a central axis of the outer shaft, is driven distally within a lumen of the vessel;

advancing an inner shaft distally into the outer shaft until cutting edges of a fluted distal end of the inner shaft are fully extended out of the opening of the outer shaft beyond the tapered distal end of the outer shaft to a stop position in which the inner shaft is limited from extending distally further from the outer shaft;

imaging the lumen of the vessel though an imaging window on a lateral side of the inner shaft while rotating the inner shaft with respect to the outer shaft in a first direction so that the tapered distal end of the outer shaft occludes the imaging window at a defined rotational position as the inner shaft is rotated relative to the outer shaft to provide a registration mark for the imaging; and

advancing the outer shaft and inner shaft together distally to cross the occlusion while rotating the inner shaft in the first direction.

18. The method of claim 17 , further comprising removing the inner shaft from the outer shaft while the outer shaft remains within the vessel.

19. The method of claim 18 , further comprising inserting a guidewire within the outer shaft after removing the inner shaft.

20. The method of claim 19 , further comprising using the guidewire to perform an atherectomy procedure.