74 is adjacent occlusion 36. With reference to FIG. 8, it will be appreciated that tip 74 has passed beyond intima 26 and is disposed between occlusion 36 and adventitia 24 of artery 20. Some methods described in this document may include the step of advancing a crossing device between an occlusion and the adventitia of an artery.

FIG. 9 is an additional view of artery 20 and crossing device 70 shown in the previous figure. In the embodiment of FIG. 9, the distal end of crossing device 70 has been advanced in an axial direction past occlusion 36. Methods described herein may include the step of advancing a crossing device beyond an occlusion. In the embodiment of FIG. 9, crossing device has crossed occlusion 36 by advancing between occlusion 36 and adventitia 24 of wall 22.

It is to be appreciated that other methods of crossing an occlusion are within the spirit and scope of this disclosure. For example, the crossing device 70 may pass through occlusion 36 while remaining disposed inside true lumen 30. In FIG. 9, tip 74 of crossing device 70 is shown residing between intima 26 and adventitia 24 of artery 20. As tip 74 moves in an axial direction between intima 26 and adventitia 24, tip 74 may cause blunt dissection of the layers forming wall 22 of artery 20. Alternatively, tip 74 may cause blunt dissection of the materials comprising the occlusion 36.

In the embodiment of FIG. 9, tip 74 of crossing device 70 is disposed between intima 26 and adventitia 24. When this is the case, fluid communication between proximal segment 32 and distal segment 34 may be achieved by creating an opening through intima 26. Such an opening may be created, for example, using a re-entry device and an orienting device that directs the advancement of the re-entry device toward intima 26.

FIG. 10 is an additional view of artery 20 shown in the previous figure. In the embodiment of FIG. 10, crossing device 70 has been withdrawn from true lumen 30 of artery 20. With reference to FIG. 10, it will be appreciated that guidewire 60 remains in the position formerly occupied by crossing device 70.

The position of guidewire 60 shown in FIG. 10 may be achieved using crossing device 70. Guidewire 60 may be positioned, for example, by first placing crossing device 70 in the position shown in the previous figure, then advancing guidewire 60 through lumen 122 defined by shaft 72 of crossing device 70. Alternately, guidewire 60 may be disposed within lumen 122 while crossing device 70 is advanced beyond occlusion 36.

With guidewire 60 in the position shown in FIG. 10, guidewire 60 may be used to direct other devices between occlusion 36 and adventitia 24. For example, a catheter may be advanced over guidewire 60 until the distal end of the catheter extends between an occlusion and the adventia. After reaching this location, the catheter may be used to dilate the tissue surrounding the catheter. Examples of catheters that may be used to dilate tissue include balloon angioplasty catheters, atherectomy catheters, and stent delivery catheters.

FIG. 11 is an additional view of artery 20 and guidewire 60 shown in the previous figure. In the embodiment of FIG. 11, an orienting device 100 has been advanced over guidewire 60. Orienting device 100 includes a distal shaft 102 comprising a outer wall 128 defining a central lumen 104. A first aperture 130 and a second aperture 132 are also defined by outer wall 128. In the embodiment of FIG. 11, first aperture 130 and second aperture 132 are both in fluid communication with central lumen 104.

In the embodiment of FIG. 11, orienting device 100 has been positioned so that first aperture 130 opens toward intima 26 of artery 20 and second aperture 132 opens toward adventitia 24. In the embodiment of FIG. 11, first aperture 130 and second aperture 132 are longitudinally separated from one another. Orienting device 100 includes a first radiopaque marker that is located between first aperture 130 and second aperture 132. A second radiopaque marker of orienting device 100 is located distally of second aperture 132.

FIG. 12 is an additional view of artery 20 and orienting device 100 shown in the previous figure. In the embodiment of FIG. 12, guidewire 60 has been withdrawn leaving orienting device 100 in the position shown in FIG. 12. With reference to FIG. 12, it will be appreciated that orienting device 100 extends beyond occlusion 36. In FIG. 12, occlusion 36 is shown blocking true lumen 30. Occlusion 36 divides true lumen 30 into a proximal segment 32 and a distal segment 34. When an orienting device in accordance with some embodiments disclosed herein is advanced between the adventitia and the intima of an artery, the orienting device may be used to direct a re-entry device toward true lumen 30. Fluid communication between proximal segment 32 and distal segment 34 may be achieved by re-entering the true lumen with a re-entry device.

FIG. 13 is an enlarged partial cross-sectional view showing a portion of orienting device 100 shown in the previous figure. In the embodiment of FIG. 13, a re-entry device 180 has been advanced into central lumen 104 of orienting device 100. With reference to FIG. 13, it will be appreciated that re-entry device 180 includes a bend 134 near distal end 136 of re-entry device 180.

FIG. 14 is an additional partial cross-sectional view showing a portion of re-entry device 180 and orienting device 100. For purposes of illustration, FIG. 14 is enlarged and simplified relative to the items shown in the previous figure. In the embodiment of FIG. 14, re-entry device 180 is biased to assume a bent shape including a bend 134. Also, in the embodiment of FIG. 14, distal shaft 102 of orienting device 100 is holding re-entry device 180 in a somewhat compressed state. When this is the case, re-entry device 180 can be inserted through first aperture 130 by positioning distal end 136 over first aperture 130 and allowing bend 134 to assume its natural state (i.e., bent at a sharper angle). Re-entry device 180 can be inserted through first aperture 130 until it comes into contact with intima 26.

It the embodiment of FIG. 14, distal end 136 of re-entry device 180 is axially aligned with first aperture 130, however, bend 134 is causing distal end 136 to point away from first aperture 130. When this is the case, distal end 136 may be positioned over first aperture 130 by rotating re-entry device 180 central lumen 104 of orienting device 100.

FIG. 15 is an enlarged partial cross-sectional view showing a portion of re-entry device 180 and orienting device 100 shown in the previous figure. In the embodiment of FIG. 15, re-entry device 180 has been positioned so that a distal portion of reentry device 180 has entered first aperture 130. Intima 26 is shown below first aperture 130 in FIG. 15.

FIG. 16 is an enlarged partial cross-sectional view showing a portion of re-entry device 180 and intima 26. In FIG. 16, re-entry device 180 is shown extending through central lumen 104 and first aperture 130. With reference to FIG. 16, it will be appreciated that re-entry device 180 comprises a distal surface 144 and a probe 146 extending beyond distal surface 144. In the embodiment of FIG. 16, probe 146 of re-entry device 180 is contacting intima 26.

FIG. 17 is an enlarged partial cross-sectional view showing a portion of re-entry device 180. In the embodiment of FIG. 17, probe 146 of re-entry device 180 has pierced intima 26. When this is the case, probe 146 may anchor the distal tip of re-entry device 180 to intima 26. Additionally, the piercing of intima 26 with probe 146 may serve to weaken intima 26.

FIG. 18 is an enlarged partial cross-sectional view showing a portion of re-entry device 180. In the embodiment of FIG. 18, the distal end 136 of re-entry device 180 has been advanced through intima 26. With reference to FIG. 18, it will be appreciated that distal end 136 of re-entry device 180 is disposed in true lumen 30 defined by intima 26.

FIG. 19 is a partial cross-sectional view of re-entry device 180 shown in the previous figure. FIG. 19 has a different scale than the previous figure so that more of the surrounding context is visible in FIG. 19. In FIG. 19, distal end 136 of re-entry device 180 can be seen residing in true lumen 30.

FIG. 20 is an additional view of artery 20 shown in the previous figure. In the embodiment of FIG. 20, orienting device 100 has been withdrawn leaving re-entry device 180 in the position shown in FIG. 20. Devices such as balloon angioplasty catheters, atherectomy catheters, and stent delivery catheters may be advanced over re-entry device 180. In this way, these devices may be used in conjunction with re-entry device 180 to establish a blood flow path between proximal segment 32 of true lumen 30 and distal segment 34 of true lumen 30. This path allows blood to flow around occlusion 36.

FIG. 21 is a partial cross-sectional view of an exemplary re-entry device 280 in accordance with the present detailed description. Re-entry device 280 comprises a tip member 242 that is fixed to a shaft 240 and a coil 248 that is disposed about a distal portion of the shaft 240. Shaft 240 comprises a proximal segment 250 that extends between a proximal end PE and a first tapered segment 252. In the embodiment of FIG. 21, coil 248 extends between first tapered segment 252 and tip member 242.

A first intermediate segment 262 of shaft 240 extends between first tapered segment 252 and a second tapered segment 254. A second intermediate segment 264 of shaft 240 extends between second tapered segment 254 and a third tapered segment 256. A distal segment 260 of shaft 240 extends between third tapered segment 256 and tip member 242. With reference to FIG. 21, it will be appreciated that tip member 242 is fixed to distal segment 260 of shaft 240. In the embodiment of FIG. 21, a probe 246 of re-entry device 280 extends distally beyond a distal surface 244 of tip member 242.

FIG. 22 is a plan view of an exemplary re-entry device 380 in accordance with the present detailed description. Re-entry device 380 comprises a tip member 342 having a distal surface 344. In the embodiment of FIG. 22, distal surface 344 of tip member has a generally convex shape. In some cases, tip member 342 may have a generally hemispherical shape. A probe 346 of re-entry device 380 extends distally beyond distal surface 344. Probe 346 terminates at a distal face 358. In FIG. 22, distal face 358 is shown as a straight line representing a substantially flat surface. With reference to FIG. 22, it will be appreciated that distal face 358 is substantially perpendicular to the longitudinal axis of probe 346.

A number of exemplary dimensions associated with probe 346 are illustrated in FIG. 22. In the embodiment of FIG. 22, probe 346 extends beyond distal surface 344 of tip member 342 by a distance L. Also, in the embodiment of FIG. 22, probe 346 has a diameter DA and tip member 342 has a diameter DB. With reference to FIG. 22, it will be appreciated that diameter DB of tip member 342 is generally greater than diameter DA of probe 346.

In some useful embodiments, diameter DA of probe 346 is between about 0.0020 inches and about 0.0055 inches. In some useful embodiments, diameter DB of tip member 342 is between about 0.008 inches and about 0.035 inches. In some useful embodiments, length L of probe 346 is between about 0.003 inches and about 0.032 inches. In FIG. 22, a coil 348 is shown extending between tip member