Abstract:
Improved intravascular balloon catheters for the delivery of embolic agents and devices such as coils to wide-neck aneurysms. In one embodiment, the present invention provides a balloon catheter having a combined guide wire/delivery lumen and a lateral delivery hole. The balloon may comprise a multi-lobed design with the delivery hole disposed between adjacent balloon lobes. The balloon catheter preferably includes a diversion member disposed in the combined lumen to cause the embolic device to divert from the combined lumen, through the delivery hole, and into the wide-neck aneurysm. In another embodiment, the present invention provides a balloon catheter having a shaft including a shaft tube and a co-extending embolic delivery tube. The delivery tube terminates proximal of the distal end of the shaft tube for added flexibility, and the balloon may inflate eccentrically to push the distal opening of the delivery lumen adjacent the opening of the wide-neck aneurysm.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention generally relates to intravascular balloon catheters. More specifically, the present invention relates to intravascular balloon catheters for the delivery of embolic devices and agents to aneurysms.  
         BACKGROUND OF THE INVENTION  
         [0002]    Embolic devices and agents have been proposed for the treatment of vascular diseases and malformations requiring the formation of thrombus. For example, embolic coils have been proposed for the treatment of aneurysms. A currently preferred method of deploying an embolic coil to an aneurysm utilizes an electrolytically detachable guide wire tip or coil commercially available under the trade name GDC (Guglielmi Detachable Coil) available from Boston Scientific Corporation. The GDC system and method of use is substantially described in U.S. Pat. No. 5,354,295 to Guglielmi et al., and other related patents and patent applications.  
           [0003]    Some types of vascular aneurysms have a relatively large opening between the native vascular lumen and the cavity of the aneurysm. For example, aneurysms which have an opening that is the same size or larger than the cavity may be referred to as wide-neck aneurysms. Wide-neck aneurysms are typically difficult to embolize with embolic devices and agents because the embolic material has a tendency to fall out or otherwise exit the aneurysm during delivery. In the case of embolic coils, wide-neck aneurysms are particularly problematic when the neck of the aneurysm is as large or larger than the expanded size of the embolic coil.  
           [0004]    To address this problem, a separate balloon catheter is often utilized to block the neck of the aneurysm during embolic coil delivery to prevent the coil from exiting or protruding out of the aneurysm. Although not intended for use in the treatment of wide-neck aneurisms, U.S. Pat. No. 5,795,331 to Craigg et al., disclose a method and apparatus for delivering an occluding agent into an aneurysm or branch vessel utilizing a balloon catheter. The balloon catheter disclosed by Craigg et al., includes an elongate shaft having a guide wire lumen and one or more delivery lumens for the delivery of an embolic agent. A balloon is disposed about the distal end of the elongate shaft for inflation in the vessel adjacent the aneurysm such that the exit port of the delivery lumen is disposed adjacent to the opening of the aneurysm. In each of the embodiments disclosed by Craigg et al., the portion of the elongate shaft which defines the delivery lumen extends distal of the balloon thereby unnecessarily adding stiffness to the distal end of the catheter and compromising flexibility and navigability thereof. In addition, all of the embodiments disclosed by Craigg et al. utilize delivery lumens which are separate from the guide wire lumen thereby unnecessarily increasing the overall profile of the catheter in situations where the some of the lumens may be combined.  
         SUMMARY OF THE INVENTION  
         [0005]    To address these problems, the present invention provides improved intravascular balloon catheters for the delivery of embolic devices and agents to wide-neck aneurysms. In one embodiment, the present invention provides a balloon catheter having a combined guide wire/delivery lumen and a lateral delivery hole for an embolic device to pass from the combined lumen into the wide-neck aneurysm. The combined lumen reduces the profile of the balloon catheter to provide improved trackability, particularly in small diameter tortuous vasculature. The balloon may comprise a multi-lobed design with the delivery hole disposed between adjacent balloon lobes. The balloon catheter preferably includes a diversion member disposed in the combined lumen to cause the embolic device to divert from the combined lumen, through the delivery hole, and into the opening of the wide-neck aneurysm.  
           [0006]    In another embodiment, the present invention provides a balloon catheter including a shaft having a shaft tube and a co-extending delivery tube. The delivery tube includes a distal opening for the delivery of an embolic agent or device such as a coil. The delivery tube terminates proximal of the distal end of the shaft tube for added flexibility and improved trackability. An inflatable balloon is connected to the distal end of the shaft, and the balloon may inflate eccentrically about the distal end thereof. The eccentric balloon pushes the distal opening of the delivery lumen adjacent the opening of the wide-neck aneurysm. The balloon catheter may include a distal guide wire seal to accommodate a single lumen design. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    FIGS.  1 A- 1 C illustrate longitudinal cross sectional views of a distal portion of a balloon catheter for embolic device delivery in accordance with an embodiment of the present invention;  
         [0008]    [0008]FIGS. 2A and 2B illustrate longitudinal cross sectional views of a distal portion of a balloon catheter for embolic device delivery in accordance with another embodiment of the present invention;  
         [0009]    FIGS.  3 A- 3 D illustrate cross sectional views taken along lines  3 A- 3 A,  3 B- 3 B,  3 C- 3 C and  3 D- 3 D, respectively, in FIG. 2A; and  
         [0010]    [0010]FIG. 4 illustrates the delivery of an embolic coil into a wide-neck aneurysm utilizing the catheter shown in FIGS. 2A and 2B. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0011]    The following detailed description should be read with reference to the drawings in which similar elements in different drawings are numbered the same. The drawings, which are not necessarily to scale, depict illustrative embodiments and are not intended to limit the scope of the invention.  
         [0012]    Refer now to FIG. 1A which illustrates a longitudinal cross sectional view of a distal portion of a balloon catheter  10  for the delivery of an embolic device such as a coil to a wide-neck aneurysm. FIG. 1A illustrates the balloon catheter  10  in the inflated state, FIG. 1 B illustrates the balloon catheter  10  with a guide wire  100  disposed therein, and FIG. 1C illustrates the balloon catheter  10  with an embolic device  200  disposed therein.  
         [0013]    Although described with reference to an embolic coil, those skilled in the art will recognize that the present invention may be utilized to deliver other mechanical embolic devices in addition to chemical embolic agents. Furthermore, although described with reference to wide-neck aneurysms, the present invention may be utilized in the treatment of other vascular diseases and malformations calling for the occlusion of a vascular lumen, opening or cavity, such as may occur in, for example, arteries, veins, aneurysms, vascular shunts, arteriovenous fistulas, etc.  
         [0014]    The balloon catheter  10  includes an elongate shaft  12  having a proximal end and a distal end. An inflatable balloon  14  is connected to the distal end of the elongate shaft  12 . A manifold (not shown) is connected to the proximal end of the elongate shaft  12  to facilitate connection to an inflation device for inflating/deflating the balloon  14 , and to facilitate insertion of the guide wire  100  and/or the embolic device  200 . The elongate shaft  12  and the balloon  14  may comprise conventional designs having conventional dimensions and materials except as described herein.  
         [0015]    The balloon catheter  10  is adapted to be used in combination with a guide wire  100 . The balloon catheter  10  may comprise a fixed-wire type balloon catheter or an over-the-wire type balloon catheter as shown. Over-the-wire type of embodiments of the balloon catheter  10  may incorporate a single lumen design or a multi-lumen design (e.g., side-by-side dual lumen, coaxial lumens, etc.) as shown. In the coaxial multi-lumen design shown, the elongate shaft  12  includes an inner tube  18  disposed in an outer tube  16 . The inner tube  18  is connected to the distal end of the inflatable balloon  14  and defines a combined guide wire/delivery lumen  22  therein. The outer tube  16  is connected to the proximal end of the inflatable balloon  14  and defines an annular inflation lumen  20  therein. The inflation lumen  20  is fluid communication with the interior of the balloon  14  for inflation and deflation thereof.  
         [0016]    In the single lumen design (not shown), the outer tube  16  may be eliminated by connecting both the proximal and distal ends of the inflatable balloon  14  to the inner tube  18  and by providing an inflation port (not shown) through the wall of the inner tube  18  to establish fluid communication between the combined lumen  22  and the interior of the balloon  14 . To facilitate inflation and deflation of the balloon  14 , a guide wire seal (not shown) may be incorporated into the distal end of the inner tube  18  to provide a fluid tight seal about the guide wire  100  disposed therein. The guide wire seal may comprise a gap-type seal or an interference-type seal, both of which inhibit the loss of inflation therethrough and allow free longitudinal and rotational movement of the guide wire  100  therein.  
         [0017]    The balloon catheter  10  includes a delivery hole  24  extending through the wall of the inner tube  18 . The delivery hole  24  allows for the passage of the embolic device  200  from the combined lumen  22  into the aneurysm as illustrated in FIG. 1C. The embolic device  200  may comprise, for example, a GDC embolic device as disclosed in U.S. Pat. No. 5,122,136 to Guglielmi et al., the entire disclosure of which is hereby incorporated by reference. The embolic device  200  generally includes a distally disposed detachable coil  202  and a proximal delivery shaft  204 .  
         [0018]    With the delivery hole  24  disposed adjacent the balloon  14 , the balloon  14  must be arranged to provide a delivery path from the combined lumen  22  to the exterior of the catheter  10  adjacent the opening to the aneurysm. To accommodate the delivery path, the inflatable balloon  14  may incorporate two or more inflation lobes  14 A/ 14 B between which the delivery hole  24  is disposed. The balloon lobes  14 A/ 14 B may extend around the entire circumference of the inner tube  18  or may extend around only a portion thereof as shown. To define the balloon lobes  14 A/ 14 B, half of the circumference of the mid portion of the balloon  14  may be connected to the inner tube  18 . This may be accomplished, for example, by utilizing a conventional single lobe balloon and adhesively tacking a mid portion of the balloon  14  to the outer surface of the inner tube  18 . The delivery hole  24  may then be formed through the mid portion of the balloon  14  and the inner tube  18  connected thereto.  
         [0019]    The balloon catheter  10  may include a diversion member  30  disposed in the combined lumen  22  to facilitate diversion of the embolic device  200  through the delivery hole  24 . Preferably, the diversion member  30  fills the entire cross sectional area of the lumen  22 . The diversion member  30  may include a guide wire passage  32  in the form of a hole, slot, slit, etc. to allow the guide wire  100  to be slidably inserted therethrough. The diversion member  30  may include a proximal inclined face  34  and a distal concave face  36 . The proximal inclined face  34  preferentially directs the embolic device  200  from the combined lumen  22  through the delivery hole  24 . The concave distal face  36  preferentially directs the proximal end of the guide wire  100  through the guide wire passage  32  such that the guide wire  100  may be easily back-loaded into the catheter  10 .  
         [0020]    In preparing the balloon catheter  10  for use, the combined lumen  22  is flushed and the inflation lumen  20  is purged of all air utilizing a syringe connected to the manifold (not shown) at the proximal end of the shaft  12 . The guide wire  100  is then back-loaded into the distal end of the combined lumen  22  such that the proximal end of the guide wire  100  engages the concave distal face  36  of the diversion member  30 . The proximal end of the guide wire  100  is advanced in the proximal direction through the guide wire passage  32  and through the remainder of the elongate shaft  12 , until the distal end of the guide wire  100  is adjacent the distal end of the balloon catheter  10 .  
         [0021]    To position the balloon catheter in the patient&#39;s vascular system, an appropriate guiding catheter (not shown) may be placed in the vascular lumen using conventional techniques. The guide wire  100  and the balloon catheter  10  are then inserted into the guide catheter until the distal tip of the catheter  10  reaches the distal end of the guide catheter. The balloon catheter  10  and guide wire  100  are then alternatively advanced until the balloon  14  is positioned adjacent the aneurysm to be treated. Although shown in the inflated state, the balloon  14  is preferably deflated during navigation through the patient&#39;s vascular system to the desired treatment site. The position of the balloon  14  relative to the aneurysm may be established using conventional radiographic techniques in combination with radiopaque markers (not shown) disposed on the distal end of the catheter  10  adjacent the balloon  14 .  
         [0022]    When the balloon  14  is positioned adjacent the aneurysm to be occluded, the catheter  10  is rotated, if necessary, until the delivery hole  24  is aligned with the neck of the aneurysm. The balloon  14  is then slowly inflated using the inflation device until the balloon lobes  14 A/ 14 B come into contact with the portion of the vascular wall defining the neck of the aneurysm, and the opposite portion of the balloon  14  pushes the delivery hole  24  into close proximity to the opening of the aneurysm. Once inflated, the guide wire  100  may be withdrawn from the catheter  10  in the proximal direction thereby allowing the guide wire passage  32  in the diversion member  30  to close.  
         [0023]    The embolic device  200  is then advanced through the combined lumen  22  and diverted into the delivery hole  24  by virtue of diversion member  30 , until the detachable coil portion  202  is disposed within the aneurysm. The detachment mechanism is activated to release the coil  202  from the shaft  204  of the embolic device  200 . With the detached embolic coil  202  disposed in the aneurysm, the balloon  14  is deflated and the catheter  10  is withdrawn from the patient&#39;s vascular system. In some instances, it may be desirable to maintain the balloon  14  in the inflated state after the embolic coil  202  is deployed in order to allow thrombus formation in the aneurysm to hold the coil  202  therein.  
         [0024]    Refer now to FIGS. 2A and 2B which illustrate longitudinal cross sectional views of a distal portion of a balloon catheter  50  in accordance with an alternative embodiment of the present invention. FIG. 2A illustrates the balloon catheter  50  in the deflated state, and FIG. 2B illustrates the balloon catheter  50  in the inflated state. Except as described herein, the balloon catheter  50  is substantially the same in terms of design, function and use as balloon catheter  10  described previously.  
         [0025]    Balloon catheter  50  includes an elongate shaft  52  having a proximal end and a distal end. A manifold (not shown) is connected to the proximal end of the elongate shaft  52 . An inflatable balloon  54  is connected to the distal end of the elongate shaft  52 . Radiopaque marker bands  76  may be disposed adjacent the proximal, mid, and distal portions of the inflatable balloon  54  to facilitate radiographic placement thereof.  
         [0026]    The elongate shaft  52  includes a shaft tube  56  and a delivery tube  58 . The distal end of the delivery tube  58  terminates proximal of the distal end of the shaft tube  56  to impart additional flexibility to the distal end of the elongate shaft  52 . An outer sleeve member  60  covers a majority of the length of the shaft tube  56  and delivery tube  58 . As best seen in FIG. 3A, a filler material  62  is disposed between the outer sleeve  60  and the tubes  56 / 58 .  
         [0027]    The inflatable balloon  54  includes an inflatable portion  54 A and a non-inflatable portion  54 B. The inflatable portion  54 A is connected at its proximal and distal ends to the shaft tube  56 . The non-inflatable portion  54 B is connected along its entire length to the shaft tube  56  and delivery tube  58  as shown. The inflatable balloon  54  may be connected to the elongate shaft  52  utilizing an adhesive  64  or other connection means known to those skilled in the art. With this arrangement, the balloon  54  inflates eccentrically about the distal portion of the elongate shaft  52  as best seen in FIG. 2B. Those skilled in the art will recognize that the eccentric balloon arrangement may be provided by connecting the balloon  54  to the elongate shaft  52  as shown, or by other suitable means such as disclosed in U.S. Pat. No.  5 , 718 , 683  to Ressemann et al., the disclosure of which is hereby incorporated by reference.  
         [0028]    The delivery tube  58  defines a delivery lumen  66  and a distal delivery hole  68 . The shaft tube  56  defines a common guide wire/inflation lumen  70  which is in fluid communication with the interior of the balloon  54  by way of a plurality of inflation ports  72 . Because the elongate shaft  52  utilizes a common guide wire/inflation lumen  70 , a guide wire seal  74  is provided at the distal end of the shaft tube  56  to provide a fluid tight seal about the guide wire  100  disposed therein. As mentioned previously, the guide wire seal  74  may comprise a gap-type seal or an interference-type seal, both of which provide a fluid tight seal about the guide wire  100  disposed therein and permit relative longitudinal and rotational movement thereof.  
         [0029]    In preparing the balloon catheter  50  for use, the common guide wire/inflation lumen  70  is flushed and the balloon  54  is partially inflated to purge the system of air utilizing an inflation device such as a syringe connected to the manifold (not shown). The guide wire  100  is then advanced through the common guide wire/inflation lumen  70  until the distal end of the guide wire  100  exits the distal end of the guide wire seal  74 . The inflation device is then used to partially inflate the balloon  54  to inspect it for surface abnormalities and/or air bubbles. If air bubbles remain in the balloon  54  or lumen  70 , the guide wire  100  may be pulled back from the guide wire seal  74  and additional inflation fluid may be flushed into the common lumen  70  and balloon  54  to purge all air bubbles therefrom.  
         [0030]    With reference to FIG. 4, the balloon catheter  50  may be positioned in the patient&#39;s vascular system adjacent an aneurysm  400  utilizing an appropriate guiding catheter (not shown) placed in the vascular lumen using conventional techniques. The guide wire  100  and balloon catheter  50  are advanced through the guide catheter and navigated through the patient&#39;s vascular system as described previously until the delivery hole  68  is positioned in the center of the aneurysm  400  as seen in FIG. 4. The position of the balloon  54  and the delivery hole  68  may be confirmed utilizing conventional radiographic techniques in combination with radiopaque markers  76 .  
         [0031]    With the balloon  54  and the delivery hole  68  centered in the opening of the aneurysm  400 , the balloon  54  is inflated thereby occluding the native lumen  302  of the vessel  300  and pushing the delivery hole  68  immediately adjacent the opening of the aneurysm  400 . Prior to inflating the balloon  54 , the catheter  50  may be rotated, if necessary, until the delivery hole  68  is adjacent the opening to the aneurysm  400 .  
         [0032]    Once inflated, the embolic device  200  is advanced through the delivery lumen  66  until the detachable coil portion  202  is disposed within the cavity  402  of the aneurysm  400 . The detachment mechanism is then activated to release the coil  202 . As mentioned previously, it may be desirable to maintain the balloon  54  in the inflated state after the detachable coil  202  is deployed in the cavity  402  in order to allow thrombus formation to hold the coil  202  therein. After the coil  202  is deployed and retained in the aneurysm cavity  402 , the balloon  54  is deflated and the catheter  50  is withdrawn from the patient&#39;s vascular system.  
         [0033]    Those skilled in the art will recognize that the present invention may be manifested in a variety of forms other than the specific embodiments described and contemplated herein. Accordingly, departures in form and detail may be made without departing from the scope and spirit of the present invention as described in the appended claims.