Apparatus and method for crossing a position along a tubular body structure

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Remote endarterectomy is a procedure by which a single incision is made at one position along a blood vessel to provide access to the blood vessel by some type of ring stripper. The remote endarterectomy procedure is often accomplished when the blood vessel is totally occluded. The ring stripper, which typically consists of a ring at the end of a long thin handle, is typically passed between the tunica intima (also called the intimal layer) and the tunica media under fluoroscopic guidance thus dissecting the intimal layer and the occlusion from the remainder of the vessel wall to a position distal of the occlusion. The ring stripper is then removed and a remote cutter, such as described in U.S. Pat. No. 5,843,102, can be used to transect the separated intimal layer distally of the occlusion. This permits the intimal layer and the occlusion to be removed through the single incision proximal of the occlusion.

One of the problems with conventional remote endarterectomy procedures occurs because removing the intimal layer and obstruction tends to pull sections of the intimal layer away from the remainder of the vessel wall at the point of transection. This leaves flaps of the transected intimal layer partially obstructing the lumen of the vessel. The intimal layer flaps interfere with the passage of a guidewire to a position distal of the transected intimal layer. Guidewires are used for many purposes, such as to guide passage of a balloon, stent or other endoluminal prosthesis into position to secure the intimal layer flaps outwardly against the remainder of the vessel wall. However, the obstruction caused by the intimal layer flaps tends to deflect the guidewire into the natural dissection plane between the tunica intima and the tunica media. Guidewire placement can occasionally be a tedious and time consuming procedure for the surgeon. If the guidewire enters this natural dissection plane, it may travel distally along the plane, giving the surgeon are impression that the true lumen has been accessed when in fact the surgeon has created a false lumen. This can also create damage to the vessel, forcing conversion to conventional bypass surgery. If it is not possible to pass the guidewire past the intimal lining flaps, the surgeon may be forced to make a separate incision past the transected intimal layer and use this second opening into the vessel to permit the guidewire to be passed retrograde through the second incision, through the vessel and out through the first incision. At times it may be required that the vessel be opened up surgically at the end point and treat the intimal lining flap surgically. Both of these latter two options largely negate the advantages of the remote endarterectomy procedure.

PCT publication WO 00/18323 discloses apparatus for guiding a guidewire between the intimal and adventitial layers of a blood vessel wall, past an occlusion and back into the main lumen distal of the occlusion. The device, however, lacks structure which would help maintain the end of the catheter body between the intimal and adventitial layers. It also lacks structure which would limit the distance the guidewire could extend through the device and into the blood vessel. In addition to lacking any recognition of the desirability of such structure, the reference fails to recognize the desirability for the use of a contrast medium to ensure the guidewire has properly accessed the distal lumen.

The present invention provides an assembly and method by which a guidewire can be positioned across a vascular occlusion prior to removal of the occlusion. This eliminates the problems associated with guidewire placement following removal of a total occlusion by a remote endarterectomy procedure. The invention is not limited to endarterectomy procedures nor is it limited to blood vessels. The invention may be used with vascular structures, including arteries and veins in various locations such as iliac, SFA, renal, coronary, SV bypass grafts and the like, as well as non-vascular tubular body structures, such as bile ducts and the esophagus. The invention may be used to cross total or partial occlusions or to cross an unoccluded position along a hollow body structure. However, for ease of discussion, the invention will usually be discussed in terms of crossing a total vascular occlusion in conjunction with a remote endarterectomy procedure.

A first aspect of the invention is directed to an assembly comprising an elongate member delivery assembly and a flexible elongate member, typically a hollow needle, comprising distal and proximal portions. The elongate member delivery assembly includes an elongate body defining an axis and a laterally-extending layer-separation guide at the distal end of the body. The guide is sized and shaped to guide the distal end of the delivery assembly between the layers of a tubular body structure. The guide helps to ensure the device stays between the chosen layers so to help prevent inadvertent puncturing or other damage to the wall. The needle delivery assembly further comprises an elongate member-redirecting surface positioned and oriented to cause the tip portion of a distally moving elongate member to be redirected to move in a direction at an angle to the axis. Thus, the tip portion of the elongate member may be directed by the assembly into the wall of a tubular body structure, along the wall between the layers of the wall, past a position (such as an obstruction) in the tubular body structure (such as a blood vessel), and back through at least one of the wall layers to enter the interior of the tubular body structure distally of the position.

The separation guide may have a width of preferably about 2-8 times, and more preferably about 4 times, as wide as the elongate body. The separation guide may have a curved cross-sectional shape. The needle delivery assembly may have a proximal end adapter at the proximal end of the body. The proximal end adapter may have a component for selecting the maximum movement of the elongate member through the lumen of the body in a distal direction. The separation guide may be moveable between a laterally retracted state and a laterally extended state to permit the assembly to be used percutaneously. The elongate body may include a hollow outer sheath, from which the separation guide extends, and an elongate member support element housed within the outer sheath and at least partly defining an elongate member pathway, the elongate member support element comprising the elongate member-redirecting surface.

A second aspect of the invention is directed to a method for crossing a position along a tubular body structure, such as a vascular occlusion, comprising selecting a position-crossing assembly comprising a flexible elongate member and an elongate member delivery assembly. The delivery assembly comprises an elongate body, a laterally-extending separation guide and an elongate member-redirecting surface positioned and oriented to cause the tip portion of a distally moving elongate member to be redirected to move in a direction at an angle to the axis of the body. The method further includes positioning the laterally-extending separation guide between layers of the wall of the tubular body structure; passing the guide between layers from a position proximal of a position within the blood vessel interior to a position distal of the position, typically past an obstruction; and then driving the elongate member along the axis in a distal direction against the deflecting surface thereby deflecting the tip portion causing the tip portion to pass through at least one wall layer and into the interior of the hollow body structure.

The method may include adjusting the maximum distance the elongate member may extend distally past the elongate member-redirecting surface. The method may also include injecting a detectable substance through the elongate member and into a blood vessel interior following the driving step to ensure the tip is properly positioned, typically within the vessel interior distal of an occlusion. The selecting step may further comprise choosing a laterally-extending, vascular tunica-separation guide having a shape which defines a curved tunicae-separation plane, the plane sized to generally follow the curvature of the blood vessel. The positioning step may be carried out percutaneously; the positioning step may comprise changing the state of the tunica-separation guide from a laterally-retracted state to a laterally-extended state to aid percutaneous placement. It should be noted that although the invention has been described in terms of use in permitting a guidewire to cross an occlusion, it could be used when a vessel is not totally occluded or in situation where the vessel is not occluded at all.

Other features and advantages of the invention will appear from the following description in which the preferred embodiments and methods are set forth in detail in conjunction with the accompanying drawings.

FIG. 1 is an overall view of a vascular occlusion-crossing assembly made according to the invention;

FIG. 2 is an exploded isometric view of the assembly of FIG. 1 in which the hollow needle is shown removed from the needle delivery assembly;

FIG. 3 is a cross-sectional view of the handle of FIG. 1 with a proximal portion of the hollow needle passing therethrough;

FIG. 3A is a view similar to that of FIG. 3 but with length of the handle increased by rotating the rear handle relative to the front handle;

FIG. 4 is an enlarged isometric view of the distal portion of the assembly of FIG. 1;

FIG. 5 is a view similar to that of FIG. 4 but sting the tip of the needle passing through the separation guide to view two different extents;

FIG. 5A is a cross-sectional taken along line 5 A- 5 A of FIG. 5 illustrating the curved shape of the separation guide along a plane perpendicular to the axis of the elongate body;

FIG. 6 is a greatly enlarged cross-sectional view of a blood vessel with a total occlusion within the blood vessel interior, the three layers of the blood vessel wall being shown by separate cross hatching;

FIG. 7 shows the distal portion of the assembly of FIG. 1 after the needle-redirecting surface has entered the blood vessel wall at an entrance position proximal of the occlusion (shown in FIG. 6 ), and after passing between the tunica intima and tunica media to position distal of the total occlusion; also shown is the tip of the hollow needle having been redirected by the needle-redirecting surface of the separation guide to pass through the tunica intima and into the distal lumen distal of the occlusion; also shown is a guidewire passing through the hollow needle and into the distal lumen;

FIGS. 8A and 8B show the distal end of an alternative embodiment of the needle delivery assembly of FIGS. 1 and 4, showing the separation guide in laterally-retracted and laterally-extended states, respectively;

FIG. 9 is an enlarged side view of the proximal and distal ends of an alternative embodiment of the assembly of FIG. 1;

FIG. 10 is a cross-sectional view of the assembly of FIG. 9;

FIG. 10A is a view similar to that of FIG. 10 but with the guidewire support element rotated 180° and the guidewire moved distally and deflected by the deflecting surface on the guidewire support element to pass out an opening in the outer sheath;

FIG. 11 is a side cross-sectional view of the guidewire support element assembly of FIG. 9 including the guidewire support element of FIG. 10 and the rear handle body of FIG. 9;

FIG. 12 is an isometric view of a tip element of the needle delivery assembly of FIG. 9 separated from the hollow outer sheath and with the guidewire support element and guidewire removed;

FIG. 12A is a longitudinal cross-sectional view of the tip element of FIG. 12;

FIG. 12B is a cross-sectional view taken along line 12 B- 12 B of FIG. 12A; and

FIG. 13 is a perspective view of portions of the handle of FIG. 9 .

FIGS. 1 and 2 illustrate a vascular occlusion-crossing assembly 2 made according to the invention. Assembly 2 includes a needle delivery assembly 4 which houses a hollow needle 6 or other elongate member.

Needle delivery assembly 4 includes a handle 8 , see FIGS. 3 and 3A, as its proximal end adapter. Handle 8 includes a front handle body 10 and a rear handle body 12 . Front and rear handle bodies are threadably mounted to one another at threads 14 so that the length 16 of a bore 18 extending through the handle can be adjusted by the user; the purposes of this feature will be discussed in more detail below. Rear handle body 12 has a recess 20 at the proximal end of bore 18 sized to accommodate the Luer fitting 22 at the proximal portion 24 of hollow needle 6 . Hollow needle 6 includes a hollow needle shaft 26 extending from Luer fitting 22 to a sharpened tip 28 at a tip portion 30 of needle 6 . Needle 6 is hollow to permit both a passage of a guidewire, or other elongate structures, and/or a contrast fluid therethrough, the use of which is discussed below. Hollow needle 6 also permits the flow of blood back through the needle to provide an indication to the user when an artery is located.

FIGS. 4, 5 and 5 A illustrate the construction of a vascular tunicae-separation guide 32 extending from a hollow, elongated body 34 at the distal end 36 of assembly 4 . Guide 32 is preferably sized and shaped and constructed to generally follow the curvature of the blood vessel with which it is to be used. As shown in FIG. 5A, taken along a plane oriented perpendicular to the axis 38 of the elongate body 34 , separation guide 32 has a generally curved shape with an average radius of curvature R of about 3 mm to 15 mm and more preferably about 6 mm to 8 mm for vascular use. Radius R is chosen according to the radius of the vessel or other tubular structure. Also, the maximum width DI of separation guide 32 is preferably about 2 to 8 times, and typically about 4 times, the width D 2 of elongate body 34 . The curved or circumferential width W of separation guide 32 is measured along an arc and this is longer than straight-line width DI. Circumferential width W is preferably about ¼ to ½ of the circumference of the blood vessel, or other tubular body structure, with which it is to be used. The appropriate sizing and shaping of separation guide 32 helps to ensure that the distal end 32 of needle delivery assembly 4 is properly guided along the dissection plane between two of the three tunicae intima 16 , tunica media 42 and tunica adventitia 14 , illustrated in FIGS. 6 and 7, of the blood vessel wall 46 of blood vessel 48 .

In use, access through blood vessel wall 46 is made to provide access into proximal lumen 50 located proximal of a total occlusion 52 within blood vessel 48 . Separation guide 32 is inserted into vessel wall 46 at entrance point 53 within proximal lumen 50 and into a dissection plane, typically between tunica intima 40 and tunica adventitia 44 . Separation guide 32 is then advanced to a position distal of the intended core transection point, in this case distal of total occlusion 52 , as suggested in FIG. 7 . Hollow needle shaft 26 of hollow needle 6 is then passed through hollow body 34 where it is directed into distal lumen 54 at angle 56 to axis 38 by a needle-redirecting surface 58 . Surface 58 is formed by the distal end of elongate body 34 as the body curves at an angle to axis 38 so that the tip portion 30 of hollow needle shaft 26 passes out of the opening 60 at the distal end of body 34 adjacent to separation guide 32 . Angle 56 is about 0° to 90° , and is preferably about 30° to 60° , and is more preferably about 45° . To ensure tip 28 is at the desired position, in this case within distal lumen 54 , contrast media is then flushed under fluoroscopic imaging through Luer fitting 32 . This helps to ensure the true lumen, that is, distal lumen 54 , has been accessed as opposed to a false lumen within vessel wall 46 or a region external of blood vessel 48 .

It is typically desirable to limit the distance tip 28 can extend past opening 60 so to help prevent tip 28 from passing completely through blood vessel 48 . To do so, the user typically first inserts hollow needle 6 into delivery assembly 4 until Luer fitting 22 is properly housed within recess 20 . This occurs prior to placing assembly 2 within the patient. This indicates the maximum distance tip 28 can extend from opening 60 at distal end 36 . See the dashed line position of tip 28 of FIG. 5 . The user then rotates front and rear handle bodies 10 , 12 relative to one another thus causing the length 16 of bore 18 to increase until tip 28 is at a desired distance from opening 60 . See the solid line position of tip 28 of FIG. 5 . At this point hollow needle 6 is typically removed from assembly 4 and then separation guide 32 is positioned distally of occlusion 52 as discussed above and shown in FIG. 7 . Hollow needle 6 is then reintroduced fully into assembly 4 so that tip 28 is deflected by surface 58 , passes through tunica intima 40 and enters distal lumen 54 . Once tip 28 has been confirmed to be properly positioned, typically with the aid of a contrast media, a guidewire 62 is passed through hollow needle shaft 26 until the tip 64 of guidewire 62 is positioned within distal lumen 54 . Guidewire 62 is then anchored relative to needle delivery assembly 4 to permit hollow needle 6 to be removed from blood vessel 48 . The desired result of providing a guidewire crossing total occlusion 52 within blood vessel 48 has now been achieved. At this point the surgeon may proceed with any one of several diagnostic or therapeutic procedures. For example, a section of intimal layer 40 with occlusion 52 therein may be removed by remote endarterectomy; after which guidewire 62 can be used to help place any balloon, stent, lining or other endovascular device into vessel 48 .

The materials from which the components of assembly 2 may be made include any of a number of biocompatible materials. For example body 34 and guide 32 may be made of polymers, metals and ceramics, or a combination thereof, such as stainless steel or Nitinol, while handle 8 will typically be made of one or more polymers. Needle shaft 26 is typically made of Nitinol, stainless steel or polymers, or a combination thererof, e.g. a stainless steel body with a Nitinol tip.

FIGS. 8A and 8B illustrate the distal end of an alternative embodiment of the invention, specially designed for percutaneous use. Vascular tunicae-separation guide 32 A can assume a laterally-retracted state shown in FIG. 8A and a laterally-extended state shown in FIG. B. Separation guide 32 A includes a pair of laterally outwardly extending, flexible guide members 66 which tend to assume the laterally extended state of FIG. 8 B. To assume the laterally-retracted state of FIG. 8A, the user pulls on a pair of pull wires 68 which pull a portion of each guide member 66 back into body 34 A of the needle delivery assembly for percutaneous introduction into proximal lumen 50 of blood vessel 48 . Alternatively, guide member 66 could be made of a shape memory material which would assume a laterally-extended state of FIG. 8B either by virtue of being heated to, for example, body temperature or in some other manner. It is preferred that guide member 66 be sufficiently flexible so to permit them to generally follow the natural dissection plane between the tunica layers of the blood vessel. It should be noted that the straight-line and circumferential widths of guide 32 A corresponding to widths D 1 and W of the embodiment of FIGS. 5 and 5A are the same when guide 32 A is in the FIG. 8B state. One or more fluoroscopically visible, or other remotely visible, markers are preferably used on guide 32 A to help ensure proper orientation of the guide within the patient so that the needle is properly directed into the vessel lumen.

A further embodiment of the invention is disclosed in FIGS. 9-13. In this embodiment elongated body 34 B includes both a hollow outer sheath 70 , extending from front handle body 10 B, and a elongated guidewire support element 72 , housed within sheath 70 . See FIG. 11 . Guidewire support element 72 is secured to and extends from rear handle body 12 B. Vascular tunica-separation guide 32 B, shown best in FIGS. 12, 12 A and 12 B, is made as part of a tip element 74 secured to and extending from hollow outer sheath 70 . Guidewire support element 72 and rear handle body 12 together constitute guidewire support element assembly 76 . Assembly 76 is typically oriented in one of two rotary orientations, 180° apart, as shown in FIGS. 10 and 10A. The orientation of FIG. 10 is used when assembly 2 B is being passed between tunica intima 40 and tunica media 42 or between tunica media 42 and tunica adventitia 44 . This orientation helps to create a smooth tissue deflecting surface 78 , shown in FIG. 10, during this procedure. Once properly in position, rear handle body 12 is pulled proximally so pins 80 , extending from front handle body 10 B, become disengaged from slots 82 formed in rear handle body 12 B; rear handle body 12 B is then rotated 1800 and then moved distally to seat pin 80 within the opposite slot 84 . At this position, needle re-deflecting surface 58 B has become oriented with opening 60 B so to permit guidewire 62 B, or other flexible elongate member, to pass through opening 60 B and enter distal lumen 54 .

Corresponding elements of the various embodiments have been referred to with reference numerals so they are not separately described. The common methods of use of the embodiment have also not been separately discussed.

Other modifications can be made through the disclosed embodiment without departing from the subject of the invention as defined in the following claims.

Any and all patents, patent applications and printed publications referred to above are incorporated by reference.