Abstract:
An ultrasonic device and method for removing obstructive matter from an anatomical structure or passageway (e.g., blood vessel). The device comprises an elongate pliable catheter having a distal tip member attached to the distal end thereof, and an ultrasound transmission member which extends longitudinally therethrough to carry ultrasound from the proximal end of the catheter to the distal tip member. The distal tip member has a concave indentation formed in the distal surface thereof, and at least one inlet passageway extending therethrough in communication with a catheter lumen to facilitate suctioning of severed matter which becomes located within the concave indentation of the distal tip. The device may further incorporate means for infusing fluid (e.g., irrigation fluid, medicaments) separately or concurrently with the aspiration of the severed obstructive matter.

Description:
RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 08/387,996 filed on Feb. 13, 1995, now U.S. Pat. No. 5,916,192, which is a continuation-in-part of U.S. application Ser. No. 08/094,416, filed Jul. 19, 1993 now U.S. Pat. No. 5,397,301 which is a division of application Ser. No. 07/640,190 filed Jan. 11, 1991, now U.S. Pat. No. 5,304,115 and a continuation in part of U.S. Pat. application Ser. No. 08/255,513 filed Jun. 8, 1994, now U.S. Pat. No. 5,474,530 which is a division of application Ser. No. 07/911,651, filed Jul. 10, 1992, and issued on Jun. 28, 1994 as U.S. Pat. No. 5,324,255. 
    
    
     FIELD OF THE INVENTION 
     The present invention pertains generally to medical equipment and more particularly to an atherectomy catheter having an ultrasound transmission member extending therethrough such that ultrasonic energy may be delivered to the distal end of the catheter to facilitate the atherectomy procedure. 
     BACKGROUND OF THE INVENTION 
     The prior art has included a number of ultrasonic catheters which are insertable into the mammalian body and usable to deliver ultrasonic energy for purposes of ablating obstructive material from anatomical cavities or passageways, or for other therapeutic purposes. 
     Examples of ultrasonic treatment catheters and related apparatus include those described in U.S. Pat. No. 3,433,226 (Boyd), U.S. Pat. No. 3,823,717 (Pohlman, et al.), U.S. Pat. No. 4,808,153 (Parisi), U.S. Pat. No. 4,936,281 (Stasz), U.S. Pat. No. 3,565,062 (Kuris), U.S. Pat. No. 4,924,863 (Sterzer), U.S. Pat. No. 4,870,953 (Don Michael, et al.), U.S. Pat. No. 4,920,954 (Alliger, et al.), U.S. Pat. No. 5,267,954 (Nita), as well as other patent publications W087-05739 (Cooper), W089-06515 (Bernstein, et al.), W090-0130 (Sonic Needle Corp.), EP316789 (Don Michael, et al.), DE3,821,836 (Schubert) and DE2,438,648 (Pohlman). 
     Additionally, ultrasound transmitting catheters may be utilized to deliver ultrasonic energy to mammalian blood vessels for the purpose of preventing or reversing vasospasm, as described in U.S. Pat. No. 5,324,255. 
     The prior art has also included a number of atherectomy devices which are insertable into blood vessels and usable to cut, shave or otherwise sever obstructive matter from the walls of the blood vessel. Such atherectomy devices typically include aspiration channels for suctioning the severed matter from the lumen of the blood vessel. Examples of atherectomy devices which have heretofore been know include those described in U.S. Pat. Nos. 5,100,423 (Fearnot), 
     Additionally, U.S. Pat. No. 4,808,153 (Parisi) has described a device for removing placque from arteries wherein a hollow tip member is mounted on the distal end of a tubular catheter, and an ultrasound source is connected to the proximal end of the catheter to cause the entire catheter, including the distal tip, to undergo vibratory movement. Such vibratory movement of the hollow distal tip member ostensibly creates heat which serves to emulsify obstructive matter which is located on the walls of an artery adjacent the vibrating hollow tip member. The emulsified matter is subsequently suctioned or withdrawn, in the proximal direction, through the hollow tip member and through the lumen of the catheter. 
     Although the device described in U.S. Pat. No. 4,808,153 (Perisi) is purportedly useable to remove obstructive matter from the walls of a blood vessel, the device disclosed in such prior United States Patent is believed to be of less than optimal design for all intravascular applications. Accordingly, there remains a need for a new ultrasonic angioplasty catheter capable of utilizing ultrasound-induced vibratory motion to sever or separate obstructive matter from the walls of blood vessels or other anatomical passageways, and which includes means for promptly removing the severed or separated matter from the lumen of the blood vessel or anatomical passageway. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, there is provided an ultrasonic device and method for removing obstructive matter from an anatomical cavity or passageway, such as a blood vessel. The device of the present invention generally comprises an elongate pliable catheter body having a distal tip member attached to the distal end thereof. An ultrasound transmission member, such as a metal wire, extends longitudinally through the catheter body to transmit ultrasonic vibratory movement from the proximal end of the catheter body, to the distal tip member. In this regard, the proximal end of the ultrasound transmission member is connectable to an ultrasonic transducer or other ultrasound generating device. The ultrasound transmission member is substantially unattached to the catheter body, such that the ultrasound transmission member may vibrate or move independent of the catheter body. The distal tip member may be attached to the distal end of the catheter body such that, ultrasonic vibratory movement transmitted to the distal tip member may also cause a distal portion of the catheter body to vibrate or move. A concave indentation is formed on the distal face of the distal tip member, and at least one aspiration passageway extends longitudinally through the distal tip member, from the distal face thereof to the proximal end thereof, in communication with a lumen of the catheter body such that matter which becomes located within the concave indentation of the distal tip member may be aspirated, in the proximal direction, through the aspiration passageway and through the catheter body. The ultrasonic device of the foregoing character insertable into the desired anatomical cavity or passageway (e.g., blood vessel) and advance to a point where the distal tip member is adjacent a quantity of obstructive matter to be removed. Thereafter, ultrasonic energy is passed through the ultrasound transmission member to the distal tip member, thereby causing ultrasonic vibratory movement of the distal tip member. The catheter is then further advanced such that the concave indentation in the distal face of the distal tip member comes in contact with the obstructive matter, and the ultrasonic vibratory movement of the distal tip member causes the obstructive matter to be separated or severed thereby. The separated or severed obstructive matter is then aspirated through the aspiration passageways, and through the catheter, thereby effecting complete removal of such matter. 
     Further in accordance with the invention, the elongate pliable catheter body of the ultrasonic device of the foregoing character may comprise an outer tube having a hollow lumen of a lumenal diameter, and an inner tube having an outer surface of an outer diameter. The inner tube is disposed within the lumen of the outer tube, and the distal ends of both tubes are affixed or positioned in abutment with the distal tip member. The aspiration passageway(s) of the distal tip member is in communication with the lumen of the inner tube, such that severed particles of obstructive matter may be suctioned through the aspiration passageway and through the lumen of the inner tube. Additional fluid infusion passageways may be formed through the distal tip member, in communication with the lumenal surface of the outer tube. In this regard, irrigation fluid, medicaments or other fluid may be infused through such lumenal space and out of the outlet passageway(s) formed in the distal tip member. 
     Further in accordance with the invention, there is provided a method of removing obstructive matter from an anatomical passageway, said method comprising the steps of: 
     a) providing an ultrasonic catheter device which comprises: 
     an elongate pliable catheter body having a proximal end, a distal end, and at least one lumen extending longitudinally therethrough; 
     a distal tip member attached to the distal end of said catheter body, said distal tip member having a distal surface, a concave indentation being formed in said distal surface; 
     an ultrasound transmission member extending longitudinally through said catheter body to transmit ultrasound from an ultrasound source located adjacent the proximal end of said catheter body, through said catheter body, to said distal tip member; 
     at least one aspiration passageway extending longitudinally through said distal tip member from the proximal surface thereof to the distal surface thereof, said aspiration passageway being in communication with a lumen of said catheter such that matter which becomes located within the concave indentation of said distal tip member may be aspirated, in the proximal direction, through said passageway and through said lumen of said catheter. 
     b) inserting said catheter body into said anatomical passageway wherein said obstructive matter is located; 
     c) advancing said catheter body to a point where said distal tip member is located adjacent the obstructive matter to be removed; 
     d) passing ultrasound through said ultrasound transmission member through said distal tip member, thereby causing said distal tip member to undergo ultrasonic vibratory movement; 
     e) advancing said catheter body such that the concaved distal surface of said distal tip member comes into contact with said obstructive matter, and such that the ultrasonic vibratory movement of said distal tip member facilitates severance of a portion of said obstructive matter; and 
     f) causing a severed portion of said obstructive matter to be aspirated in the proximal direction, through said aspiration passageway, and through a lumen of said catheter body. 
     Additionally the method may include the step of infusing irrigation fluid or medicaments into the region where the obstructive matter is located. Such infusion of irrigation fluid or medicaments may occur separately from, or contemporaneously with, the severing, separation and/or removal of the obstructive matter. 
     Further objects and advantages of the present invention will become apparent to those skilled in the art upon reading and understanding of the following detailed description and the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1, is an elevation view of a preferred ultrasound angioplasty-atherectomy catheter of the present invention. 
     FIG. 2, is an enlarged longitudinal sectional view of a proximal portion of the catheter shown in FIG.  1 . 
     FIG. 3, is an enlarged longitudinal sectional view of a distal portion of the catheter shown in FIG.  1 . 
     FIGS. 4 a - 4   c,  is a step-by-step illustration of a presently preferred method for performing ultrasonic angioplasty-atherectomy using the catheter of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The following detailed description of and the accompanying drawings are provided for purposes of describing and illustrating presently preferred embodiments of the invention only, and are not intended to limit the scope of the following claims in any way. 
     As shown in the drawings, the presently preferred ultrasonic atherectomy catheter  10  of the present invention comprises an elongate pliable catheter body  12  having at least one hollow lumen  14  extending longitudinally therethrough. A distal tip member  16  is mounted within or on the distal end of the catheter body  12 . A proximal connector assembly  18  is mounted on or connected to the proximal end of the catheter body  12  to facilitate connection of the catheter device  10  to an ultrasound transducer or other device capable of generating ultrasonic vibratory movement. In the embodiment shown, the catheter body  12  is formed of an outer tube  20  having an outer tube lumen  22  extending longitudinally therethrough, and an inner tube  24  which has an inner tube lumen  26  extending longitudinally therethrough. The inner tube  24  is preferably positioned co-axially within the lumen  22  of the outer tube  20 , such that an annular peripheral portion of the outer tube lumen  22  surrounds the outer surface  28  of the inner tube  24 . 
     The outer tube  20  and inner tube  24  are concomitantly connected or held in abutment with the distal tip member  16 , such that the respective distal ends of the outer  20  and inner  24  tubes are securely held in their desired coaxial positions. In the embodiment shown, the distal tip member  16  comprises a generally cylindrical rigid body having an annular shoulder  30  formed around the proximal surface thereof, so as to define a generally cylindrical inner region  32  which protrudes in the proximal direction from the center of the distal tip member  16 . The diameter D 1  of the cylindrical central projection  32  is substantially the same as the inner diameter of the distal end of the inner tube  24 , and the distal end of the inner tube  24  is fitted over the central projection  32 , with the distal tip of the inner tube abutting against shoulder  30 . The outer diameter D 2  of the remaining portion of the tip member  16  is substantially the same of the inner diameter of the outer tube  20 , such that the remaining body of the distal tip members  16  may be securely fitted within the distal end of the outer tube  20 , as shown. Adhesive, heat fusing techniques, or other fusion method may be utilized to securely hold the distal tip member  16  within the distal end of the outer tube  20 . Similarly, adhesive, heat fusing or other fusion technique may be utilized to securely hold the distal end of the inner tube  24  in contact with the central projection  32  on the proximal end of the distal tip member  16 . 
     The frontal surface of the distal tip member  16  is provided with a concave indentation  34 . 
     A guidewire passage bore  37  is formed longitudinally through the center of the distal tip member  16 , and a guidewire tube  36  extends therethrough. The distal end of the guidewire tube  36  opens through a distal guidewire aperture formed in the center of the concave indentation  34 , at the distal end of the catheter  10 . The proximal end of the guidewire tube  36  is affixed within or about a proximal guidewire passage aperture  38 . In the embodiment shown in the drawings, the proximal guidewire aperture  38  is formed in the sidewall of the outer tube  20 , at a location approximately 10-30 cm from the distal end DE of the catheter body  12 . A corresponding passage hole or opening  40  is formed in the wall of the inner tube  24 , to permit the guidewire tube  36  to exit therethrough. Such passage or opening  40  in the wall of the inner tube  24  is fused or sealed about the outer surface of the guidewire tube  36 , thereby preventing fluid leakage through the passage or opening  40 , about the guidewire tube  36 . It will be appreciated that the specific embodiment shown in the drawings is a “monorail” type of catheter, wherein the guidewire tube  36  extends through only the distal-most portion of the catheter body  12 . Alternative “over the wire” embodiments of the invention may also be provided wherein the guidewire tube  36  extends longitudinally through the entire catheter body  12 , and wherein the proximal end of the guide wire tube  36  is affixed to or opens through a guidewire entry aperture or sidearm located in the proximal connector assembly  18  of the catheter device  10 . 
     In the “monorail” embodiment shown in the drawings, a guidewire GW, such as a standard cardiovascular guidewire of the type commonly used in modern clinical medicine having an outer diameter of 0.008-0.025 inches, may be inserted into the guidewire bore  37 , and the catheter device  10  may then be advanced in the distal direction over the guidewire GW such that the proximal end of the guidewire GW will emerge through the proximal guidewire aperture  38 . In this manner, the catheter device  10  may be advanced over a prepositioned guidewire in accordance with standard cardiovascular catheterization technique. 
     An ultrasound transmission member  50  extends longitudinally through the lumen  26  of the inner tube  24  and is connected or held in abutment, at its distal end, with the distal tip member  16 . The proximal end of the ultrasound transmission member  50  is connected to or held in abutment with a sonic connector  52  which is formed on or extends from the proximal connector assembly  18 . When an ultrasound transducer, or other device capable of generating ultrasonic vibratory movement is connected to the sonic connector  52 , the ultrasonic vibratory movement emitted thereby is transmitted through the ultrasound transmission member  50 , to the distal tip member  16 . 
     In the preferred embodiment, the ultrasound transmission member  50  is preferably formed of a metal alloy, or other material, which exhibits superelastic properties within the range of operating temperatures normally encountered by the ultrasound transmission member  50  during use. One suitable superelastic material usable to form the ultrasound transmission member  50  is a nickel-titanium alloy having 50.8 atomic percent nickel, balance titanium. 
     The preferred proximal connector assembly  18  comprises a distal portion  60 , a proximal portion  62 , and a sonic connector housing portion  63 . The distal portion  60  comprises a tubular hard plastic tube having a fluid/debris aspiration sidearm  62  extending at an angle therefrom. An aperture or opening  64  is formed in the rigid tubular body of the distal portion  60  such that fluid/debris may be aspirated from the lumen  22  of the outer tube  20 , through aspiration sidearm  62 , via hole or aperture  64 . A distal nut  66  and pliable plastic sleeve  68  are attached about the outer surface of the proximal portion of the outer tube  20 , thereby securely fastening the outer tube  20  to the distal  30  portion  60  of the proximal connector assembly  18 . 
     As shown in FIG. 2, the outer tube  20  and inner tube  24  extend longitudinally through the distal portion  60  of the proximal connector assembly  18 , to a point adjacent the proximal nut  68  which conjoins the proximal portion  62  to the distal portion  60 . At that location, the distal end of the outer tube  20  is fused, or compressively held in contact with, the outer surface of the inner tube  24 , so as to prevent fluid within the lumen  22  of the outer tube  20 , from leaking in the proximal direction beyond the location of second nut  68 . The proximal portion  62  of the proximal connector assembly  18  comprises a rigid tubular plastic body, and the lumen  26  of the inner tube  24  extends and opens into the inner bore  70  of the proximal portion  62 , as shown. A fluid infusion sidearm  72  extends from the rigid tubular body of the proximal portion  62 , to permit infusion of fluid into the bore  70  of the proximal portion  62 , and into and through the lumen  26  of the inner tube  24 . 
     The sonic connector  52  of the proximal connector assembly  18  is housed within a connector housing  63 , which connector housing  63  is threadably mounted on the proximal end of the proximal portion  62 . A pliable plastic tube  74  extends through the sonic connector housing  63 , and protrudes partially into the hollow inner bore  70  of the proximal portion  62 , as shown. The ultrasound transmission member  50  extends from the sonic connector  52 , through the pliable plastic tube  74 , through the hollow inner bore  70  of the proximal portion  62 , and into the lumen  26  of the inner tube  24 . Such ultrasound transmission member  50  then continues longitudinally though the lumen of the inner tube  24 , to its distal end which, as described above, is affixed to or held in abutting contact with the distal tip member  16  of the catheter device  10 . 
     O-rings  80 ,  82  are positioned within a threaded frontal cavity  84 , formed in the distal portion of the sonic connector housing  63 . The proximal end of the proximal portion  62  is threaded, and is received within the threaded frontal bore  84  of the sonic connector housing  63  such that O-rings  80 ,  82  are compressed thereby. In this regard, pressure is exerted by O-rings  80 ,  82  inwardly  35  against the outer surface of plastic tube  74 , thereby stabilizing and holding the plastic tube  74  in a centralized position. The outer diameter of the ultrasound transmission member  50  is only slightly smaller than the inner diameter of the plastic tube  74  such that the plastic tube  74  will limit possible side to side movement of the adjacent portion of the ultrasound transmission member  50 , while allowing the ultrasound transmission member  50  to freely move longitudinally back and forth. Such limitation on side-to-side vibratory movement of the ultrasound transmission member  50 , within the region of the plastic tube  74 , serves to minimize the likelihood of fracture or breakage of the ultrasound transmission member  50 , in the critical region closest to the point of connection to the ultrasound transducer or other ultrasound source. 
     Thus, as shown in the step-wise illustration of FIGS. 4 a - 4   c,  the catheter shown in FIGS. 1-3 may be initially inserted, over a prepositioned guidewire GW having a preferred diameter of 0.008-0.025 inches, into an anatomical passageway such as a blood vessel BV wherein a quantity of atherosclerotic plaque or other obstructive matter OM is located. The guidewire GW is initially advanced through the obstructive matter OM, and the catheter device  10  is advanced to a point where the distal end DE of the catheter body  12  is immediately adjacent the obstructive matter OM (FIG. 4 a ). 
     Thereafter, an ultrasound transducer/generator or other source of ultrasonic energy attached to the sonic connector  52  is energized so as to pass ultrasonic energy through the ultrasound transmission member  50 , to the distal tip member  16 , thereby causing the distal tip member  16  to undergo ultrasonic vibratory movement. The catheter body  12  is subsequently advanced such that the vibrating peripheral edges of the concave indentation  34  of the vibrating tip member  16  cut into or separate the obstructive matter OM. As the vibrating peripheral edge of the concave distal tip member  16  severs or cuts away particles or quantities of the obstructive matter OM, the severed particles or quantities of obstructive matter may be aspirated through debris aspiration apertures  48 , through debris/fluid aspiration pathways  46 , through lumen  22 , and out of the aspiration sidearm  62  located on proximal connector  18  (FIG. 4 b ). This will typically be accomplished by attaching a suction source to aspiration sidearm  62 . A collection vessel may also be provided to collect the debris or other matter received through aspiration, to permit such matter to be subsequently analyzed for variation of the type and quantity of obstructive matter OM removed. 
     Also, apart from or during the procedure, quantities of irrigation fluid, medicaments, or other fluid may be infused through infusion sidearm  72 , through lumen  26 , through infusion outlet passageways  42 , and out of infusion outlet apertures  44 . 
     After the device  10  has been utilized to remove a sufficient amount of the obstructive matter OM to restore patency to the blood vessel BV or other anatomical passageway, the guidewire GW may be withdrawn and the catheter body  12  may be withdrawn from the body, thereby leaving the blood vessel BV in a restored state of improved patency. 
     It will be appreciated that the present invention has been described herein with reference to certain presently preferred embodiments of the invention, and no effort has been made to exhaustively describe all possible physical embodiments of the invention, or all possible components which may be utilized to practice the invention. In this regard, various modifications, additions, deletions and alterations may be made to the above-described embodiments without departing from the intended spirit and scope of the invention. Accordingly, it is intended that all such additions, deletions modifications and alterations be included within the scope of the following claims.