Abstract:
A laser catheter having a compliant balloon and a plurality of optical fibers extending from a base to a tip of the catheter for plaque removal is disclosed. The laser catheter may include a distal flush lumen extending to the tip. The compliant balloon may extend along a longitudinal axis of the laser catheter and may be positioned radially outward from an inner lumen. A plurality of optical fibers may be positioned between the inner lumen and an outer compliant material jacket. In another embodiment, the compliant balloon may be positioned eccentrically with respect to the inner lumen. The eccentrically positioned compliant balloon may further facilitate removal of plaque within arteries.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
       [0001]    This patent application claims the benefit of U.S. Provisional Patent Application No. 61/041,724, filed Apr. 2, 2008, U.S. Provisional Patent Application No. 61/056,650, filed May 28, 2008, and U.S. Provisional Patent Application No. 61/056,672, filed May 28, 2008. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention is directed generally to catheters, and more particularly to catheters that incorporate lasers for plaque removal. 
       BACKGROUND 
       [0003]    Some conventional catheters include lasers that are intended to ablate plaque in narrowed vessels in the human body, thus re-establishing normal blood flow. These catheters are typically sized to fit within blood vessels in the human body and remove plaque by striking the plaque with laser beams emitted by the lasers. One such catheter is the Turbo Elite laser catheter by Spectranetics of Colorado Springs, Colo., as illustrated in  FIG. 1 . Even though the Turbo Elite catheter is approved by the FDA for this function, the device has had limited applicability and utility due to many short comings, not the least of which is the inability to open up large vessels effectively without requiring an excessive amount of procedure time. The function of the catheter is also limited because the catheter can only remove plaque on contact (or in close proximity) to the laser at the tip of the catheter, thus requiring large catheters to be used to effectively clean the blood vessels. 
         [0004]    Typically, different catheter diameter sizes are manufactured to accommodate the different size blood vessels found in the human body. For instance, catheters may be manufactured in different vessel sizes ranging between 0.9 mm diameter and 2.5 mm diameter. Catheters on the larger end of this range have been used to clean larger vessels more effectively than smaller catheters. Such is the case because the larger tip on a large catheter has a larger diameter from which laser energy may be emitted to contact plaque on the vessel wall. However, conventional catheters typically have tips that are equivalent in diameter to the catheter shaft. Such a configuration has proven problematic because the entry hole must be as large as the site in the vessel from which plaque is to be removed. This is problematic because the necessity for a larger entry hole creates more potential for vessel trauma and related complications. In addition, in small female patients, a catheter that is large enough to complete the surgery often times will simply not fit through vessel at the entry point (the access site). 
         [0005]    An alternative catheter was invented in an attempt to overcome these problems. The alternative catheter, as shown in  FIG. 4 , includes a laser tip positioned eccentrically within the catheter tip. In such a position, the catheter may be rotated within the vessel to create a larger opening in the vessel than a conventional catheter of the same size and having a concentrically positioned laser. While a first glance this device appears to be an improvement over the catheter first described above, this catheter has proven to be somewhat cumbersome and quite time consuming to use. 
       SUMMARY OF THE INVENTION 
       [0006]    This invention is directed to a laser catheter with an operationally adjustable laser target zone. The laser catheter may include one or more optical fibers at a tip of the catheter. The laser catheter may be constructed such that the operational laser target zone is variable, thereby enabling the catheter to be inserted into a vessel of a patient where the tip may be enlarged during the process to effectively remove plaque causing arterial blockages by positioning laser emitting optical fibers closer to the walls of the vessel in a patient. The variability of the operational laser target zone enables plaque to be ablated from a vessel more efficiently and in less time than conventional systems. 
         [0007]    In another embodiment, the laser catheter may be constructed such that the operational laser target zone is variable and amenable to gradual increments in target ablation. The catheter may also be configured such that directional increments in a target zone can be achieved, thereby enabling the catheter to be inserted into a vessel of a patient such that the tip may be shifted from a central location in a vessel lumen by inflating the eccentrically placed balloon on the side of the tip of the catheter. Such a system enables directional ablation in the areas of eccentric plaque build up. The laser catheter also facilitates more effective removal of plaque causing arterial blockages by positioning laser emitting optical fibers closer to the walls of the vessel in a patient. The variability of the operational laser target zone enables plaque to be ablated from a vessel more efficiently and in less time than conventional systems. The variability of the operational laser target zone also enables the laser energy to be directed where it is most needed in the vessels with eccentric plaques. The eccentrically positioned balloon enables a single catheter to be used to treat multiple sized vessels without the need to use multiple sized catheters. 
         [0008]    In one embodiment, the laser catheter may include with an operationally adjustable laser target zone formed from an inner lumen formed by at least one hollow wire and a compliant balloon positioned at least proximate to a tip of the inner lumen such that the compliant balloon is positioned radially outward from the inner lumen. The laser catheter may also include a compliant material jacket positioned radially outward from the compliant balloon that forms an outer housing for the laser catheter at least at the tip and a plurality of optical fibers positioned in the compliant material jacket radially outward from the compliant balloon. The optical fibers may be configured to be placed in communication with at least one laser generator and extend to the tip. The optical fibers terminate at an end of the laser catheter. The laser catheter may also include a distal flush lumen that terminates at a distal end of the laser catheter. The distal flush lumen is eccentrically positioned. 
         [0009]    In another embodiment, the laser catheter may include a compliant balloon positioned at least proximate to a tip of the inner lumen such that the compliant balloon is positioned radially outward from the inner lumen and is positioned eccentrically relative to the inner lumen. The eccentric balloon may be attached to an outer surface of the inner lumen and may extend radially outward therefrom. Alternatively, the eccentric balloon may be attached to the inner lumen and extends radially inward therefrom. A distal flush lumen may be included and may terminate at a distal end of the laser catheter, The distal flush lumen may be eccentrically positioned. 
         [0010]    An advantage of this invention is that the laser catheter has the ability to change the distal catheter tip diameter after introducing the catheter into the vessel while maintaining a relatively small catheter shaft and thus a small vascular entry point and while maintaining the same centric ablative path. In embodiments in which there is an eccentrically positioned balloon, the orientation of the optical fibers within the tip may be changed. Such orientation will allow an operator physician to define and adjust the desired degree of eccentricity for each particular plaque allowing for example a two millimeter laser catheter to be used to ablate eccentric plaque in vessels as big as 3-8 mm in diameter or larger depending on the inflated diameter used. Such configuration significantly enhances the safety of the device and improves the cost effectiveness by enabling a physician to use one catheter to treat more than one vessel size in one operative session. 
         [0011]    Another advantage of this invention is that use of the laser catheter enables one to maintain a relatively small access point sheath size, such as about less than 7 French, whereby each French size is equal to 0.33 mm. 
         [0012]    Yet another advantage of this invention is that the laser catheter improves the ease of use of the device. 
         [0013]    Another advantage of the laser catheter is that with balloon inflations, the outer surface of the compliant material jacket may touch the vessel wall proximal to the laser ablation site, thereby making the tip more reliable in treating a portion of the vessel at the plaque site such that the site is void of blood and increasing the effectiveness of laser ablation. 
         [0014]    Still another advantage of this invention is that the laser catheter may be very useful because of the staggering growth in prevalence of arterial blockages and because of an increasing number of patients with previously implanted stents that have re-occluded due to recurrent plaque. 
         [0015]    Another advantage of this invention is that the laser catheter  10  may be very useful because of the staggering growth in prevalence of arterial blockages, and of increasing number of patients with previously implanted stents that have re-occluded due to recurrent plaque. 
         [0016]    These and other embodiments are described in more detail below. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    The accompanying drawings, which are incorporated in and form a part of the specification, illustrate embodiments of the presently disclosed invention and, together with the description, disclose the principles of the invention. 
           [0018]      FIG. 1  is a perspective view of a conventional catheter. 
           [0019]      FIG. 2  is a partial perspective view of an inner wire lumen of the catheter of  FIG. 1 . 
           [0020]      FIG. 3  is a perspective view of a tip of the catheter of  FIG. 1 . 
           [0021]      FIG. 4  is a diagram of the path of the laser of a catheter with an eccentrically positioned laser. 
           [0022]      FIG. 5  is a cross-sectional view of the catheter of  FIG. 1  in a vessel. 
           [0023]      FIG. 6A  is a cross-sectional side view of a catheter of this invention in a deflated state. 
           [0024]      FIG. 6B  is a cross-sectional end view of a catheter of this invention in a deflated state. 
           [0025]      FIG. 7A  is a cross-sectional side view of a catheter of  FIG. 6A  in an inflated state. 
           [0026]      FIG. 7B  is a cross-sectional end view of a catheter of this invention in a deflated state. 
           [0027]      FIG. 8  is a cross-sectional view of the catheter of  FIG. 6A  taken orthogonal to a longitudinal axis of the catheter with the balloon inflated along section line  8 - 8 . 
           [0028]      FIG. 9  is a cross-sectional view of the catheter of  FIG. 7A  taken orthogonal to a longitudinal axis of the catheter with the balloon deflated along section line  9 - 9 . 
           [0029]      FIG. 10A  is a cross-sectional side view of an alternative catheter of this invention in a deflated state including an eccentric wire lumen and centrally positioned distal flush lumen. 
           [0030]      FIG. 11  is a cross-sectional view of the catheter of  FIG. 10A  taken orthogonal to a longitudinal axis of the catheter with the balloon deflated along section line  11 - 11 . 
           [0031]      FIG. 12  is a cross-sectional side view of a catheter of this invention in a deflated state. 
           [0032]      FIG. 13  is a cross-sectional side view of a catheter of  FIG. 12  in an inflated state. 
           [0033]      FIG. 14  is a cross-sectional view of the catheter of  FIG. 12  taken orthogonal to a longitudinal axis of the catheter with the balloon deflated along section line  14 - 14 . 
           [0034]      FIG. 15  is a cross-sectional view of the catheter of  FIG. 13  taken orthogonal to a longitudinal axis of the catheter with the balloon inflated along section line  15 - 15 . 
           [0035]      FIG. 16  is a cross-sectional view of an alternative catheter of this invention in a inflated state including an eccentric wire lumen and centrally positioned distal flush lumen. 
           [0036]      FIG. 17  is a cross-sectional view of the catheter of  FIG. 16  taken orthogonal to a longitudinal axis of the catheter with the balloon deflated. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0037]    As shown in  FIGS. 6-17 , this invention is directed to a laser catheter  10  with an operationally adjustable laser target zone. The laser catheter  10  may include one or more optical fibers  12  at a distal tip  14  of the catheter  10 . The laser catheter  10  may be constructed such that the operational laser target zone is variable, thereby enabling the catheter  10  to be inserted into a vessel of a patient and then enlarged during the process to effectively remove plaque causing arterial blockages. The variability of the operational laser target zone enables plaque to be ablated from a vessel more efficiently, more safely and in less time than conventional systems. 
         [0038]    The laser catheter  10  may be formed from a flexible, hollow tube  16 , which may be referred to as an inner lumen, as shown in  FIGS. 6A-7B . The hollow tube  16  may be formed from any appropriate material and in any appropriate configuration to provide the necessary support together with the necessary flexibility to be inserted into and manipulated within a vessel of a patient. An example of an appropriate hollow tube  16  is included within the laser catheters sold by The Spectranetics Corporation of Colorado Springs, Colo. The hollow tube  16  may also function as a distal flush lumen  32 , as shown in  FIG. 10 , by allowing fluids to be transported in the voids between a wire and the lumen. A compliant balloon  18 , such as, but not limited to an over the wire or a rapid exchange compliant balloon, may be positioned proximate to a distal tip  14  of the inner lumen  16  such that the compliant balloon  18  is positioned radially outward from the inner lumen  16 . In one embodiment, the compliant balloon  18  may be positioned at or immediately proximate to a distal tip  14  of the inner lumen  16  such that the compliant balloon  18  is positioned radially outward from the inner lumen  16 . The balloon  18  may be any appropriate sized balloon formed from any appropriate material. The balloon distal tip may be a long tapered shoulder or may be a no shoulder design. The balloon  18  may be inflated and deflated with a balloon supply lumen  34 . 
         [0039]    In another embodiment, the compliant balloon  18  may be positioned eccentrically, as shown in  FIGS. 12-17 . In particular, the compliant balloon  18  may be positioned such that the compliant balloon  18  is positioned eccentrically at inner or outer surfaces of a compliant material jacket  20 . The compliant balloon  18  may be of any appropriate shape, including, but not limited to, a crescent shape and other shapes that would facilitate advancement of the compliant balloon into a patient. 
         [0040]    In yet another embodiment, the laser catheter  10  may include an eccentric wire lumen  30 , as shown in  FIGS. 10 and 11 , configured to receive a catheter wire. The eccentric wire lumen  30  may be positioned at an outer surface of the laser catheter  10 . The eccentric wire lumen  30  may have any appropriate size. The eccentric wire lumen may include a distal flush as well. 
         [0041]    The laser catheter  10  may also include a compliant material jacket  20  positioned radially outward from the compliant balloon  18  as shown in  FIGS. 6A ,  7 A,  10 A,  12  and  13 . The compliant material jacket  20  may form an elongated outer housing for the laser catheter  10 . In one embodiment, the inner lumen  16  may be positioned concentrically within the compliant balloon  18 , and the compliant balloon  18  may be positioned concentrically within the compliant material jacket  20 . The compliant material jacket  20  contains the compliant balloon  18  within the laser catheter  10  yet allows the compliant balloon  18  to inflate within a vessel. During use, in one embodiment, the tip  14  may be about two millimeters in diameter in a deflated state and may be inflated such that an outer diameter of the tip  14  is about 4.5 mm or larger when the balloon is maximally inflated. This size range is exemplary only and is not provided as a limitation of the invention. In other embodiments, the size of the tip  14  in the deflated and inflated states may be greater than or less than the size range provided. In the embodiment in which the compliant balloon  18  is positioned eccentrically, as the compliant balloon  18  is inflated, the optical fibers  12  move into an increasingly greater eccentric position, thereby putting the optical fibers  12  in contact with eccentric plaques in larger vessels. 
         [0042]    The laser catheter  10  may include one or more optical fibers  12  positioned in the compliant material jacket  20  that is radially outward from the compliant balloon  18 . The optical fibers  12  may be in communication with at least one laser generator (not shown). In at least one embodiment, the laser catheter  10  may include a plurality of optical fibers  12  positioned within the compliant material jacket  20 . The optical fibers  12  may extend generally parallel to the inner lumen  16  and may be positioned radially outward from the inner lumen  16 . The optical fibers  12  may be positioned circumferentially around the inner lumen  16 . The balloon  18  may be positioned centrally within the circular configuration of the inner lumen  16  or eccentrically within the laser catheter  10  such as eccentrically within or immediately radially outside of a catheter sheath. The optical fibers  12  may be spaced equidistant from each other, spaced random distances from each other, positioned in patterns, or positioned otherwise. The optical fibers  12  may terminate at the tip  14  such that laser beams may be emitted from the optical fibers  12  and strike plaque within vessels in a patient. In another embodiment, the optical fibers  12  may be placed around the wire lumen  16  with the distal flush lumen  32  at the tip  14  of the catheter or at a distance from the tip  14 . 
         [0043]    During use, the catheter  10  of  FIGS. 6A-11  may be inserted into the vessel  36  of a patient. Preferably, the outer diameter of the tip  14  is as small as possible to limit the size of the site at which the catheter  10  is inserted. The catheter may be inserted  10  a sufficient distance to place the tip  14  in very close proximity to plaque within the vessel. The laser may be actuated to emit a laser beam from the optical fibers  12  to ablate the plaque buildup in the vessel. After the initial pass has been completed establishing a lumen, the balloon  18  may be inflated such that the outer surface of the compliant material jacket  20  at least nearly contacts the vessel wall other amount depending on the vessel size and the patient needs. The laser may be actuated further to ablate the plaque buildup in the vessel. This process can be repeated as needed with further balloon inflation and catheter rotational manipulation as deemed necessary for each particular point until all desired plaque removal is achieved. A very good benefit of the laser catheter  10  is that with balloon inflations, the outer surface of the compliant material jacket  20  and therefore some of the optical fibers  12  touch or nearly touch the vessel wall proximal to the laser ablation site, thereby positioning the tip  14  in a more central position within the vessel. Such positioning further enhances plaque ablation by making the vessel at the plaque site more void of blood and increases the effectiveness of the laser ablation. 
         [0044]    In the embodiment in which the compliant balloon  18  is positioned eccentrically, as shown in  FIGS. 12-17 , the catheter may be inserted  10  a sufficient distance to place the tip  14  in very close proximity to plaque within the vessel. The laser may be actuated to emit a laser beam from the optical fibers  12  to ablate the plaque buildup in the vessel. After the initial pass has been completed establishing a lumen, the compliant balloon  18  may be inflated such that the laser tip is pushed away from the center of the lumen  16  and positioned eccentrically within the lumen  16 , thereby positioning the optical fibers  12  in close proximity to eccentrically positioned plaque. 
         [0045]    The foregoing is provided for purposes of illustrating, explaining, and describing embodiments of this invention. Modifications and adaptations to these embodiments will be apparent to those skilled in the art and may be made without departing from the scope or spirit of this invention.