Patent Document

FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to methods and apparatus for medical treatment and more particularly to catheters and related methods for vascular and other transluminal interventional procedures. 
       BACKGROUND 
     Treatment of Chronic Total Occlusions 
       [0002]    Total or near-total occlusions in arteries can prevent all or nearly all of the blood flow through the affected arteries. Chronic total occlusions (CTOs) can occur in coronary as well as peripheral arteries. It has been estimated that approximately 10% of all angioplasty procedures are currently undertaken for CTOs. 
         [0003]    In the past, a number of devices have been developed and/or used for the percutaneous interventional treatment of CTOs, such as special guidewires, low-profile balloons, laser emitting wires, atherectomy devices, drills, and drug eluting stents, re-entry catheter, etc. The factor that is most determinative of whether the interventionalist can successfully recannalize a CTO is the interventionalist&#39;s ability (or inability) to advance a suitable guidewire from a position within the true lumen of the artery proximal to the CTO, across the CTO lesion (i.e., either through the lesion or around it), and then back into the true lumen of the artery at a location distal to the lesion. 
         [0004]    In some instances, such as where the occlusive matter is soft or where the occlusion is less than total, the guidewire can simply be pushed through the occlusive matter itself, thereby allowing the guidewire to remain within the artery lumen. However, in other cases, such as where the artery is totally occluded by hard, calcified atherosclerotic plaque, the guidewire may tend to deviate to one side and penetrate through the intima of the artery, thereby creating a neo-lumen called a “subintimal space” (e.g., a penetration tract formed within the wall of the artery between the intima and adventitia). In these cases, the distal end of the guidewire may be advanced to a position distal to the lesion but remains entrapped within the subintimal space. In such instances, it is then necessary to divert or steer the guidewire from the subintimal space back into the true lumen of the artery at a location distal to the CTO lesion. 
       Catheters Useable to Facilitate Reentry into True Lumen 
       [0005]    A number of catheters based devices have been heretofore useable to redirect subintimally entrapped guidewires back into the true lumen of the artery. Included among these are the devices described in U.S. Pat. Nos. 5,830,222 (Makower), 6,068,638 (Makower), 6,159,225 (Makower), 6,190,353 (Makower, et al.), 6,283,951 (Flaherty, et al.), 6,375,615 (Flaherty, et al.), 6,508,824 (Flaherty, et al.), 6,544,230 (Flaherty, et al.), 6,655,386 (Makower et al.), 6,579,311 (Makower), 6,602,241 (Makower, et al.), 6,655,386 (Makower, et al.), 6,660,024 (Flaherty, et al.), 6,685,648 (Flaherty, et al.), 6,709,444 (Makower), 6,726,677 (Flaherty, et al.) and 6,746,464 (Makower) describe a variety of catheters having laterally deployable cannulae (e.g., hollow needles). These catheters are advanced into the subintimal space, over the subintimally entrapped guidewire. Thereafter, the laterally deployable cannula is advanced from the catheter into the true lumen of the blood vessel, downstream of the CTO. A second guidewire is then passed through that laterally deployed cannula and is advanced into the true lumen of the artery. The laterally deployed cannula is then retracted into the catheter and the catheter is removed, along with the original guidewire, leaving just the second guidewire in place. This second guidewire is then useable to facilitate enlargement (e.g., balloon dilation, atherectomy, etc.) and/or stenting of the subintimal space, thereby creating a sub-intimal bypass conduit around the CTO. These types of catheter devices are also useable in many types of interventions, including the delivery of substances (e.g., drugs, biologics, cells, genes, contrast media or other diagnostic or therapeutic substances), articles or devices to target locations within the body, passage of guidewires and/or catheters for accessing target locations, bypassing of obstructions, re-entry into a true lumen of a blood vessel from a subintimal space, etc. Commercially available catheters of this type have been used successfully in the treatment of CTOs in relatively large vessels, such as the femoral artery, popliteal artery, etc. However, their use in coronary vessels and other small vessels has been limited to date due to their relatively large diameter. 
         [0006]    There exists a need in the art for the development of new small diameter catheters that have laterally deployable members (e.g., cannulae, needles, probes, wires, etc.) which may be used to redirecting subintimally entrapped guidewires and/or for other purposes such as delivery of substances, articles or devices to specific target locations within the body. 
       SUMMARY OF THE INVENTION 
       [0007]    In accordance with the present invention there is provided a catheter device comprising an elongate catheter body having a lumen with a distal end opening and a side opening and a tubular member (e.g., a needle or other cannula) that has a lumen and an open distal end. The tubular member is moveable back and forth between (a) a retracted position where the open distal end of the tubular member is within the lumen of the catheter body and (b) an extended position wherein a distal portion of the tubular member is advanced out of the side opening of the catheter body. In some embodiments, the catheter may have only a single lumen and the catheter body may have an outer diameter of less than 0.050 inch. 
         [0008]    Further in accordance with the invention, there is disclosed a method for redirecting a guidewire from a first position within the body of a human or animal subject to a second position within the body of the subject. Such method is performed using a catheter of the type summarized in the immediately preceding paragraph. The proximal end of the guidewire is inserted into the distal end opening of the catheter body and the catheter is advanced over the guidewire while the tubular member is in its retracted position, thereby causing the proximal end of the guidewire to pass through the lumen of the tubular member. Thereafter, the guidewire is retracted to a position where the distal end of the guidewire is proximal to the distal end of the tubular member (or in some cases it may be removed completely). Then, the tubular member to its extended position such that the open distal end of the tubular member is at or in substantial alignment with the second location. Thereafter, the guidewire (or a different guidewire) is advanced out of the open distal end of tubular member and into the second location. 
         [0009]    Further in accordance with the invention, there is provided a method for bypassing an obstruction in a blood vessel (e.g., a chronic total occlusion or other full or partial obstruction). In this method, a guidewire is advanced into the blood vessel such that the distal end of the guidewire becomes positioned within a subintimal space. Thereafter, a catheter device of the type referred to in the two immediately preceding paragraphs is advanced over the guidewire while its hollow needle is in the retracted position. This results in passage of a proximal portion of the guidewire into the lumen of the hollow needle. With the catheter positioned in the subintimal space, the guidewire is then retracted in the proximal direction such that the distal end of the guidewire is within the lumen of the needle. (In some cases, the guidewire may be fully retracted, removed, and another guidewire may be inserted into the lumen of the hollow needle. However, such guidewire exchange is optional and not required, as this catheter is fully functional with a single guidewire, as described herein.) The hollow needle is then advanced to its extended position whereby the open distal end of the needle is within the true lumen of the blood vessel downstream of the obstruction. The guidewire is then advanced from the lumen of the hollow needle into the true lumen of the blood vessel downstream of the obstruction. Because the catheters of the present invention may be of relatively small diameter, some embodiments of such catheters may be used by this method for treatment of coronary CTOs as well as CTO in larger peripheral arteries. 
         [0010]    Further aspects, details and embodiments of the present invention will be understood by those of skill in the art upon reading the following detailed description of the invention and the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a side view of one embodiment of a catheter device of the present invention. 
           [0012]      FIG. 2  is a partial cut away view of the distal end of the catheter device of  FIG. 1 . 
           [0013]      FIG. 2A  is a cross-sectional view through line  2 A- 2 A of  FIG. 2 . 
           [0014]      FIG. 3  is a partial cut away view of the distal end of the catheter device of  FIG. 1  incorporating optional deflector apparatus. 
           [0015]      FIG. 4  is an anatomical diagram showing the histological layers of an artery. 
           [0016]      FIGS. 4A-4G  show steps in a method for using the catheter device of  FIG. 1  to perform a transluminal, catheter-based bypass of a CTO in an artery. 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    In the following detailed description, the accompanying drawings are intended to describe some, but not necessarily all, examples or embodiments of the invention. The contents of this detailed description and accompanying drawings do not limit the scope of the invention in any way. 
         [0018]      FIGS. 1-2A  show an example of a catheter device  10  of the present invention. This catheter device  10  comprises an elongate catheter body  12  (e.g., a catheter shaft) having an atraumatic distal tip  24  on its distal end DE and a handpiece  14  on its proximal end. As seen in the more detailed views of  FIGS. 2 and 2A , some embodiments of the catheter body  12  may comprises a core member  40 , a braid layer  38  surrounding the core member  40  and an outer layer  36  surrounding the braid layer  38 . Possible materials for the components are as follows: core member  40  (HDPE, LLDPE, LDPE, polyimide (PI), Pebax, Nylon, PEEK), braid layer  38  (stainless steel, nitinol, polymeric and/or glass reinforced fibers (e.g. Kevlar), outer layer  36  (HDPE, LLDPE, LDPE, polymide (PI), Pebax, Nylon, PEEK. In the configuration where the needle/hypotube serves as the guidewire the possible dimensions of the resulting components may be as follows: core member  40  (ID=0.020″, OD=0.026″), braid layer  38  (thickness&lt;0.005″), outer layer  36  (thickness&lt;0.005″). Resulting overall shaft profile OD&lt;0.046″). A through lumen  34  extends from a port  16  on the proximal end of the handpiece  14 , through the handpiece  14 , through the catheter body  12 , and through the distal tip member  24 , terminating in a distal end opening. Additionally, a side opening  32  is formed in the catheter body  12  in communication with lumen  34 . 
         [0019]    A tubular member  30  (e.g., a hollow needle or other cannula) having an open distal end  31  is moveable back and forth between a) a retracted position where the open distal  31  end of the tubular member  30  is within the lumen  34  of the catheter body  12  and b) an extended position wherein a distal portion of the tubular member  30  is advanced out of the side opening  32  of the catheter body  12  as seen in the showing of  FIG. 2 . In some embodiments, this tubular member may be formed of elastic or supereleastic material (e.g., nickel-titanium alloy) and a distal portion of this tubular member  30  may be biased to a curved configuration, such as that seen in  FIG. 2 . In the example shown in the drawings, a knob  15  on handpiece  14  may be moved (continuously or incrementally) in the distal direction to cause advancement of the tubular member  30  to its extended position and retracted (continuously or incrementally) in the proximal direction to cause retraction of the tubular member  30  to its retracted position. Optionally, a fixed or adjustable stop apparatus  17  may be included on handpiece  14  or elsewhere to limit the extent to which the tubular member  30  may be advanced (e.g., thereby limiting the length of the portion of the tubular member  30  that extends out of side opening  32  when the tubular member  30  is in its fully extended position). 
         [0020]    In some embodiments, the tubular member  30  may be biased to a curved configuration which causes its distal end  31  to pass out of the side opening  32  as the tubular member  30  is advanced in the distal direction through lumen  34 , as seen in  FIG. 2 . In other embodiments, such as the alternative embodiment shown in  FIG. 3 , a deflector  38  may be deployed to deflect the distal end  31  of the tubular member  30  out of side opening  32 , when desired. In the particular example of  FIG. 2B , the deflector  38  becomes raised when a balloon  36  is inflated by the operator. When the deflector  38  is raised, the distal end  31  of the advancing tubular member  30  will strike the surface of the deflector and will be thereby deflected out of side opening  32 , as seen in  FIG. 2B . 
         [0021]    Optionally, the catheter device  10  may incorporate an orientation indicating element  28  which indicates the radial direction in which, or the trajectory on which, the tubular member  30  will advance from the catheter body 12 . In some embodiments, this orientation indicating element  28  may comprise a marker that is imageable by an imaging apparatus that is located on/in the catheter body  12  or elsewhere (e.g., a fluoroscope or other extracorporeal imaging device). In some embodiments, this orientation indicating element  28  may comprise an imaging apparatus that images the target location to which it is desired to advance the tubular member  30  (e.g., the true lumen of an artery) along with an electronic or physical indicator of the direction in which, or the trajectory on which, the tubular member  30  will advance from the catheter body 12 . Thus, this orientation indicating element  28  provides information which the operator may use to make any necessary adjustments in the position and rotational orientation of the catheter body  12  in situ ensure (or at least increases the probability) that the tubular member  30  will subsequently advance to the intended target location and not some other location. Examples of the various types of orientation elements  28  that may be used include but are not limited to those described in U.S. Pat. Nos. 5,830,222 (Makower), 6,068,638 (Makower), 6,159,225 (Makower), 6,190,353 (Makower, et al.), 6,283,951 (Flaherty, et al.), 6,375,615 (Flaherty, et al.), 6,508,824 (Flaherty, et al.), 6,544,230 (Flaherty, et al.), 6,655,386 (Makower et al.), 6,579,311 (Makower), 6,602,241 (Makower, et al.), 6,655,386 (Makower, et al.), 6,660,024 (Flaherty, et al.), 6,685,648 (Flaherty, et al.), 6,709,444 (Makower), 6,726,677 (Flaherty, et al.) and 6,746,464 (Makower), which are incorporated herein by reference. 
         [0022]    In operation, while the tubular member  30  is in its retracted position, it will be positioned substantially coaxially within lumen  34  of the catheter body  12  such that a guide wire GW may extend from proximal port  16 , through handpiece  14 , though lumen  34  and out of the open distal end of tip member  24 . Thereafter the guidewire GW may be retracted in the proximal direction until the distal end of the guidewire GW is proximal to the distal end  31  of the tubular member  30 . Thereafter, the tubular member  30  may be moved from its retracted position to its extended position, such that a distal portion of the tubular member  30  extends out of side opening  32 . The guidewire GW may then be advanced in the distal direction and out of the open distal end  31  of the tubular member. 
         [0023]    Optionally, an infusion/aspiration port  18  may be in communication with the lumen  34  of the catheter body  12  or the lumen of the tubular member  30  to permit infusion or aspiration of matter through the lumen  34  of the catheter body  12  or the lumen of the tubular member  30 . A Luer fitting or other suitable connector may be provided to facilitate connection of a syringe  20 , solution administration tube or other infusion or aspiration device to port  18 . Also optionally, a valve (e.g., a Tuohy-Borst valve), cap or other closure apparatus (not shown) may be associated with port  16  to deter backflow of fluids out of port  16  when fluids are being infused through port  18 . Port  16  also provides access to the lumen of tubular member  30 . This allows for the insertion of guidewires, mandrels, and fluids through tubular member  30 . 
         [0024]      FIGS. 4-4G  show an example of a procedure in which the above-described catheter device  10  is used to treat a CTO of an artery. 
         [0025]    As specifically shown in  FIG. 4 , the wall of an artery typically consists of three layers, the tunica intima (“intima”), tunica media M (“media”) and the tunica adventitia A (adventitia). In some arteries an internal elastic membrane IEM is disposed between the media M and adventitia A. 
         [0026]    Initially, as shown in  FIG. 4A  and in accordance with techniques well known in the field of interventional cardiology and/or interventional radiology, a guidewire  26  is advanced into a subintimal space adjacent to an obstruction ◯ such that the distal end of the guidewire  26  is within the subintimal space, distal to the obstruction ◯. 
         [0027]    Thereafter, As seen in  FIG. 4B , the catheter  10  of the present invention is advanced over the guidewire GW while the tubular member  30  is in its retracted position within lumen  34  such that the distal end  31  of the tubular member  30  is proximal to side opening  32 . The catheter body  12  is positioned such that the side outlet opening  32  is distal to the obstruction ◯. Before or after such retraction of the guidewire GW, if the optional orientation indicating element  28  is present, it may be used by the operator to make any necessary adjustment of the rotational orientation of the catheter body  12  within the subintimal space to ensure, or to at least increase the probability that, subsequent advancement of the tubular member  30  to its extended position will cause the distal end  31  of the tubular member  30  to enter the true lumen TL of the artery, distal to the obstruction ◯. 
         [0028]    Thereafter, as seen in  FIG. 4C , the tubular member  30  is then advanced out of side opening  32 , through adjacent tissue, and into the true lumen TL of the artery, distal to the obstruction ◯. 
         [0029]    Thereafter, as shown in  FIG. 4D , guidewire GW is advanced through the lumen of tubular member  30 , out of the distal end  31  of the tubular member  30  and into the true lumen TL of the artery. Optionally, in some cases, it may be desirable to remove and exchange the guidewire GW before it is advanced through tubular member  30  and into the true lumen TL of the artery. For example, in some applications a specialized guidewire may be forced into the artery wall to create the subintimal space and to guide the initial advancement of the catheter body  12  into the subintimal space. However, it may be desire to use a different guidewire (e.g., a more flexible guidewire) for reentry into the true lumen. In such cases, the first guidewire may be fully removed in  FIG. 4C  and a second guidewire may then be advanced through the lumen of the tubular member  30  in  FIG. 4D . 
         [0030]    Subsequently, as seen in  FIG. 4E , the tubular member  30  is withdrawn to its retracted position and the catheter  10  is removed, leaving the guidewire GW in place such that it extends through the true lumen TL of the artery proximal to (i.e., upstream of) the obstruction ◯, through the subintimal space, through the reentry tract RT created by advancement of the tubular member  30  in  FIG. 4D  and back into the true lumen TL of the artery distal to (i.e., downstream of) the obstruction ◯. 
         [0031]    One or more tract modifying devices (e.g., balloon catheters, atherectomy catheters, stent delivery catheters, laser catheters, etc.) may then be advanced over the guidewire and used to enlarge (e.g., dilate, debulk, bore, stent, etc.) the subintimal space. For example,  FIG. 4F  shows a balloon catheter  40  having a stent  42  mounted thereon being advanced over the guidewire GW to a position where one end of the stent  42  is in the true lumen TL proximal to the obstruction ◯ and the other end of the stent  42  is in the true lumen TL distal to the obstruction ◯. The balloon of the balloon catheter  40  is then used to dilate the subintimal space and to expand the stent  42 . Thereafter, the balloon is deflated and the balloon catheter  40  is removed, leaving the stent  42  in an expanded configuration and creating a stented, subintimal bloodflow channel around the obstruction ◯ as seen in  FIG. 4G . 
         [0032]    It is to be further appreciated that the invention has been described hereabove with reference to certain examples or embodiments of the invention but that various additions, deletions, alterations and modifications may be made to those examples and embodiments without departing from the intended spirit and scope of the invention. For example, any element or attribute of one embodiment or example may be incorporated into or used with another embodiment or example, unless to do so would render the embodiment or example unsuitable for its intended use. Also, where the steps of a method or process are described, listed or claimed in a particular order, such steps may be performed in any other order unless to do so would render the embodiment or example not novel, obvious to a person of ordinary skill in the relevant art or unsuitable for its intended use. All reasonable additions, deletions, modifications and alterations are to be considered equivalents of the described examples and embodiments and are to be included within the scope of the following claims.

Technology Category: 1