Abstract:
A puncture resistant balloon catheter device and a method of using the device is described. The device is a balloon catheter having a puncture resistant cover disposed over the balloon. The cover is capable of moving between a deflated state and an expanded state. The cover inhibits piercing of the balloon surface that may occur during delivery and deployment of a stent in a body lumen.

Description:
RELATED APPLICATIONS  
       [0001]     This application claims the benefit of priority from U.S. Provisional Application Ser. No. 60/780,147 filed Mar. 8, 2006, which is incorporated herein by reference. 
     
    
     TECHNICAL FIELD  
       [0002]     The invention generally relates to a balloon catheter having a puncture resistant covering.  
       BACKGROUND  
       [0003]     When a stent graft is implanted within a main body lumen having an aneurysm, the graft preferably does not occlude any side branch vessels. For example, if a renal artery or pulmonary artery is occluded by a stent graft, the blood supplied by these arteries to the vital organs would be stopped, thereby causing damage to the organ tissues. Accordingly, it is preferable that the stent graft include holes or fenestrations which are aligned with the side branch openings. Such alignment of the fenestration with the side branch enables blood to continue to flow into these branches.  
         [0004]     The fenestration generally forms a tight seal with the side branched opening. A lack of a tight seal may cause blood to leak out of the stent graft and into the gap between the stent graft and main body lumen. Such leakage can cause the aneurysm in the main body lumen to continue to be pressurized. Accordingly, a small balloon expandable stent may be implanted within the side branch vessel to create a tight seal at the site of the fenestration and vessel.  
         [0005]     Conventional balloon catheters may be used to maneuver through the fenestration of the stent graft and deploy a stent. However, conventional balloon catheters are prone to puncture during the delivery and deployment of the stent. For example, current fenestrations typically employ a rim of wire, which contacts the surface of the balloon and potentially results in damage and rupture of the balloon. Additionally, expansion of the balloon expandable stent typically involves the proximal end of the stent disposed within the stent graft. In order to connect the stent to the graft, the stent may be balloon expanded such that the struts at the proximal end of the stent will flare. However, this flaring may cause the struts to penetrate the balloon and puncture it.  
         [0006]     In addition, many arteries contain calcified lesions that may be sharp. Expansion of such arterial walls require large dilation pressures that conventional balloon catheters may not possess. Furthermore, even if expansion of such calcified arterial walls is possible, the sharp calcified lesions may rupture the balloon, thereby requiring another balloon catheter to be inserted and the procedure repeated.  
       SUMMARY  
       [0007]     Accordingly, a punctured resistant balloon catheter is provided. Although the inventions described below may be useful for increasing the control, accuracy and ease of placement during deployment of the prosthesis, the claimed inventions may also solve other problems.  
         [0008]     In a first aspect, a puncture resistant balloon catheter is provided comprising a catheter comprising a distal end, a shaft extending along a longitudinal axis of the catheter, and an inflation lumen extending therethrough. An inflatable balloon is disposed over the shaft of the catheter. A puncture resistant cover is disposed over the balloon. The cover extends circumferentially around the longitudinal axis of the catheter. The cover inhibits piercing of the balloon and is adapted to be movable between a deflated state and an inflated state.  
         [0009]     In a second aspect, a method of breaking up calcified lesions within a body lumen is provided. A puncture resistant balloon catheter comprising a catheter, an inflatable balloon, and a puncture resistant cover disposed over the balloon is provided. A wire guide is fed through the patient&#39;s skin. The wire guide is then fed through a wire guide lumen of the catheter. The balloon catheter is advanced over the wire guide towards the body lumen having the calcified lesions. Upon reaching the calcified region, the balloon is inflated. Inflation of the balloon transforms the cover from the deflated configuration to an inflated configuration. The cover in the inflated configuration breaks up the calcified lesions, and the cover inhibits piercing of the balloon by the calcified lesions.  
         [0010]     In a third aspect, a method of deploying within a branched body lumen a side branch balloon expandable stent through a fenestration of a graft is provided. A puncture resistant balloon catheter is provided comprising a catheter. The catheter comprises a distal end, a wire guide lumen and an inflation lumen extending therethrough. An inflatable balloon is disposed over the catheter. The balloon extends from the distal end of the catheter. A puncture resistant cover is disposed over the balloon. The cover extends circumferentially around the longitudinal axis of the catheter. The cover is adapted to be movable between a deflated state and an inflated state and the cover inhibits puncture of the balloon. A side branch balloon expandable stent is also provided. The stent is disposed over the puncture resistant cover. The puncture resistant balloon catheter is advanced over a wire guide. The balloon is in a deflated state. The puncture resistant balloon catheter is advanced into the graft, and the fenestration of the graft is aligned with the side branch vessel. The puncture resistant balloon catheter is then fed through the fenestration of the graft and into the branched body lumen. Fluid is passed through the inflation lumen to inflate the balloon. The inflation of the balloon causes the cover to transform from the deflated state to the expanded state. The cover exerts an outward force to expand the stent against one or more walls of the branched body lumen. In its expanded state, the stent has a distal end extending within the branched body lumen and a proximal end extending through the fenestration of the graft.  
         [0011]     Additional details and advantages of the invention are described below and shown in the drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]     Embodiments will now be described by way of example with reference to the accompanying drawings, in which:  
         [0013]      FIG. 1  is a perspective view of a puncture resistant balloon catheter;  
         [0014]      FIG. 2  is a blown-up perspective view of the puncture resistant balloon catheter of  FIG. 1 ;  
         [0015]      FIG. 3  is a cross-sectional view of the puncture resistant balloon catheter in an inflated configuration;  
         [0016]      FIG. 4  is a cross-sectional of the puncture resistant balloon catheter in a deflated configuration;  
         [0017]      FIG. 5  is a perspective view of a main lumen with an aneurysm and a healthy branch lumen;  
         [0018]      FIG. 6  is a perspective view of a stent graft implanted in the aneurysm of the main lumen;  
         [0019]      FIG. 7  is a perspective view of a balloon expandable stent implanted within the side branched body lumen;  
         [0020]      FIG. 8  is a side view of the stent graft;  
         [0021]      FIG. 9  is a blown up view of  FIG. 8  showing the fenestration; and  
         [0022]      FIG. 10  is a cross-sectional view taken along the longitudinal axis of the puncture resistant balloon catheter in an expanded state. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0023]     The embodiments are described with reference to the drawings in which like elements are referred to by like numerals. The relationship and functioning of the various elements of the embodiments are better understood by the following detailed description. However, the embodiments as described below are by way of example only, and the invention is not limited to the embodiments illustrated in the drawings. It should also be understood that the drawings are not to scale and in certain instances details have been omitted, which are not necessary for an understanding of the embodiments, such as conventional details of fabrication and assembly.  
         [0024]     An exemplary puncture resistant balloon catheter  100  is shown in  FIG. 1 .  FIG. 1  shows the balloon catheter  100  with the balloon  110  in its expanded state. The balloon  110  is disposed over the catheter  130  and extends along the longitudinal axis of the catheter  130 . The visible portion of the balloon  110  is shown with tapered ends  115  and  116 . The tapered ends  115  and  116  extend outward from within the armored ribbon coil  120  toward the surface of the catheter  130 . A blown-up view of tapered end  115  is shown in  FIG. 2 . The balloon  110  may be formed from any suitable polymeric material known to those of ordinary skill in the art, including polyethylene terephthalate (PET) and nylon.  
         [0025]     The majority of the balloon  110  may be secured within an armored coil  120 , as shown in  FIGS. 1 and 2 . The armored coil  120  may be a puncture resistant covering that may be used to protect the balloon surface from inadvertent puncture during delivery and deployment of a balloon expandable stent within a fenestrated stent graft. The procedure will be described in more detail below.  
         [0026]     The armored coil  120  is shown in  FIGS. 1 and 2  as a ribbon coil that overlies the balloon  110 . The ribbon material may be any suitable puncture resistant material, including stainless steel, nitinol, and palladium. The thickness and width of the armored coil  120  may be dependent upon a variety of factors, including the type of balloon and catheter utilized. In this example, the ribbon material preferably has a thickness ranging from about 0.0001 inches to about 0.0020 inches. The ribbon material preferably has a width ranging from about 0.010 inches to about 0.040 inches. Generally, the ribbon material may have a thickness, width and material properties that are sufficiently thin to undergo expansion when the balloon is inflated and undergo deflation when the balloon is deflated. The result is an angioplasty balloon  110  that may be fitted within the armored coil  120 . In this example, the armored coil  120  is shown as a ribbon coil that may be pre-wound to the size and shape of the balloon  110  in its expanded state. The ribbon coil may be pre-wound onto a specifically shaped mandrel. Preferably, the armored coil  120  is in the shape of a ribbon coil as shown in  FIGS. 1 and 2 . Such a geometry provides a balloon catheter  100  assembly that may be flexible as the catheter  100  is maneuvered through the vasculature. Although not shown, the armored coil  120  may be formed from a thin and continuous tubular metal foil or sleeve. Other shapes of the armored coil  120  are contemplated and may be utilized depending on the specific application the balloon catheter  100  is to be used in.  
         [0027]      FIG. 3  shows a cross-section of the puncture resistant balloon catheter  100  of  FIGS. 1 and 2 . The balloon  110  is shown inflated and secured within the armored coil  120 . The balloon  110  becomes inflated when inflation fluid is passed through the inflation lumen  310 , which extends within the shaft of the catheter  130 . As shown, the balloon  10  is fitted within the armored coil  120  such that virtually no gap may be present. Such a fitting may help to reinforce the balloon  110 .  
         [0028]      FIG. 4  depicts a cross-sectional view of the balloon  110  and armored coil  120  in a collapsed, deflated configuration. As shown in  FIG. 4 , the coil  120  in the deflated configuration may be bent and folded. The balloon  110  and armored coil  120  are shown as one thickness in order to emphasize the tight fit between them. In this example, the deflated configuration has a series of folding blades  450  circumferentially oriented about the shaft of the catheter  130 . The folding blades  450  of the armored coil  120  may be folded by a process similar to the folding process utilized for angioplasty balloons, which is known to one of ordinary skill in the art. Although not shown in  FIG. 4 , the folding blades  450  may also be wrapped around the catheter as in a conventional balloon catheter.  
         [0029]     The folding arrangement enables the puncture resistant balloon catheter  100  to retain a small profile during delivery to the target site. The folding arrangement shown in  FIG. 4  may be characterized by a fold radius, R. Suitable values of the fold radius, R, may be dependent upon many factors, including the thickness of the armored coil  120  and the diameter of the catheter  130 . Additionally, the fold radius, R, may be selected such that the formed creases  455  are large enough for the balloon  110  to properly expand upon inflation fluid passing into the inflation lumen  410 . Nonetheless, because the armored coil  120  is thin with respect to the balloon  110 , and the balloon  110  is robust, some plastic deformation may be tolerated at the creases  455 . In this example, the fold radius R preferably ranges from about 0.002 inches to about 0.010 inches.  
         [0030]     Still referring to  FIG. 4 , when fluid is passed into the inflation lumen  410 , the balloon  110  and armored coil  120  may inflate together to produce the configuration shown in  FIG. 3 .  FIG. 3  indicates that the folding blades  450  are unfolded upon inflation. There is virtually no gap between the inner surface of the armored coil  120  and the outer surface of the balloon  110 . Both surfaces may be in contact to produce a configuration in which the balloon  110  is firmly secured within the armored coil  120 .  
         [0031]     A method of fabrication for the balloon catheter  100  will now be discussed. As mentioned and shown in  FIGS. 1 and 2 , a preferred embodiment uses a ribbon coil as the armored coil  120 , in which the balloon  110  is secured inside the ribbon coil. The thin ribbon coil may be pre-wound to the size and shape of the balloon  110 . The armored coil  120  is then placed inside a blow forming mold. The coils of the armored coil  120  may touch the walls of the mold. At this point, a parison of the balloon  110  is placed within the armored coil  120 . The parison of the balloon  110  is stretch blow molded inside the armored coil  120  in the conventional manner known to one of ordinary skill in the art. The stretch blow molding blows the balloon  110  out to the interior diameter of the armored coil  120 . An adhesive could be applied to the interior surface of the coil so that the coil  120  and balloon  110  adhere together. This adhesive could be a heat activated glue such as a hot melt glue, cyanoacrylate or any other suitable adhesive known to one of ordinary skill in the art. The result is a balloon catheter  100  in which the armored coil  120  encompasses the entire balloon  110 . In this embodiment, the natural resting size of the armored coil  120  is the expanded state. The balloon will expand to the natural resting size of the armored coil  120 . Upon deflation, the balloon transforms into the pleated folding arrangement, shown in  FIG. 4 . Because of the relatively thin metal of the ribbon coil  120  as compared to the balloon  110 , the armored coil  120  correspondingly collapses into the pleated folding arrangement, shown in  FIG. 4 .  
         [0032]     The armored coil  120  disposed over the balloon catheter  100  may enable high pressure dilating forces. Typical dilating pressures of non-reinforced angioplasty balloons may range from about 15 atmospheres to about 20 atmospheres. Conventional reinforced balloons with fiber or woven Dacron embedded in the balloon material may have dilating pressures of about 50 atmospheres. The addition of a high tensile strength armor such as armored coil  120  disposed over a polymeric balloon such as balloon  110  has the ability to allow dilation pressures as high as about 100 atmospheres.  
         [0033]     The ability of the armored coil  120  to reinforce the balloon  110  and allow such high dilating pressures renders the balloon catheter  100  conducive in lumens with highly calcified lesions. Typically, calcifications have the potential for damaging the balloon material of conventional angioplasty balloon catheters. As a result, the balloon inflation procedure may have to be repeated several times before the calcified lesion or blockage will yield. The calcified lesions that need to be expanded in the lumens are generally hard. When a lumen is expanded, the calcified lesions may crack, forming a calcification with sharp edges. The armored coil  120  protects the balloon  110  during expansion of lumens with calcified lesions. This enables balloon expansion of calcified lumens to occur relatively quickly and effectively, without the risk of having to repeat the procedure multiple times because of a balloon puncture.  
         [0034]     The armored coil  120  may also protect the balloon  110  from puncture during the implantation of a balloon expandable stent through an opening of a fenestrated graft and into a side branch artery or vessel. A typical implantation procedure may now be described.  
         [0035]      FIG. 5  shows a main lumen  500  and a branch lumen  510 . The main lumen  500  has an aneurism, or weakness, which exists where the branch lumen  510  joins the main lumen  500 . A stent graft  530 , as shown in  FIG. 6 , maybe implanted within the main lumen  500 . Thus, blood flows through the stent graft  530  to alleviate pressure and potential rupture of the weakened wall of the main lumen  500 . The stent graft  530  includes a hole or orifice (i.e., fenestration  520 ) which can be aligned with the branch lumen  510  to allow blood flow to continue through the branch lumen  510  and into the healthy side branch vessels that supply blood to the visceral organs. A blown-up view of the fenestration  520  of the stent graft  530  is shown in  FIGS. 8 and 9 .  
         [0036]     Preferably, there is a tight seal around the fenestration  520  to ensure that blood does not leak out of the space between the stent graft  530  and the wall of the main lumen  500 . If blood is allowed to leak into the aneurysm around the area of the fenestration  520 , then the aneurysm may continue to be pressurized and a continued risk of rupture may exist. Forming such a seal requires positioning a balloon expandable stent  550  in the branch lumen  510  so that the stent  550  connects the branch lumen  510  to the stent graft  530 .  
         [0037]     Accordingly, after the stent graft  530  is placed within the main lumen  500  and the fenestration  520  is aligned with the branch lumen  510 , the balloon expandable stent  550  may be delivered and deployed. As a result of expansion of the stent  550 , it becomes attached to the stent graft  530  through the fenestration  520 . Radiopaque markers  925  ( FIG. 9 ) assist with the alignment of the stent  550  into the fenestration  520 . The puncture resistant balloon catheter  100  is used to deliver and deploy the balloon expandable stent  550 , which is disposed over the armored coil  120 . With the stent  550  loaded over the armored coil  120 , the puncture resistant balloon catheter  100  may be advanced over a wire guide  810  ( FIG. 10 ) and into the stent graft  530  ( FIG. 6 ). The balloon catheter  100  is maneuvered into the stent graft  530  and then partially through the fenestration  520 . Passing inflation fluid through the inflation lumen  310  ( FIG. 3 ) causes the balloon  110  and armored coil  120  to expand from the deflated state to the inflated state. The inflation of the balloon  110  enables the armored coil  120  to expand, which in turn allows the stent  550  to expand within the branch lumen  510 , as shown in  FIG. 7 . The distal end of the stent  550  is disposed within the branch lumen  510 . The proximal end of the stent  550  may be flared. The flare acts to anchor the stent  550  against the fenestration  520 . At this stage, the stent  550  may be sealed against the fenestration  520  of the stent graft  530  so that blood may flow into the branch lumen  510  without leaking into the aneurysm region.  
         [0038]     During implantation of the balloon expandable stent  550  using the balloon catheter  100 , there are several instances in the implantation procedure where the balloon  110  may be protected from puncture by the armored coil  120 . For example, as the balloon catheter  100  is maneuvered through the fenestration  520  to implant the stent  550 , the fenestration  520  may puncture the balloon  110 .  FIGS. 8 and 9  show the fenestration  520  in greater detail.  FIG. 9  shows a nitinol circumferential ring of wire  910  that is sutured to the graft material around the fenestration  520 . The nitinol circumferential ring of wire  910  strengthens the fenestration  520 , allowing for a more stable fixation when the balloon expandable stent  550  is connected. A lack of wire  910  may cause the positions of the fenestration  520  to be less reliable and may make it more difficult to seal the stent  550 . As the balloon catheter  100  is maneuvered through the fenestration  520  to deploy the stent  550 , preferably with the assistance of radiopaque markers  925  ( FIG. 9 ), the nitinol circumferential ring of wire  910  may contact the surface of the balloon  110 , thereby potentially rupturing a conventional balloon. The armored coil  120  may prevent the wire  910  from damaging and potentially rupturing the balloon  110 .  
         [0039]     Additionally, balloon puncture may occur as the balloon expandable stent  550  is being inflated within the branch lumen  510 . More specifically, the proximal end of the balloon  110  is preferably flared in order to ensure a tight seal between the stent graft  530  and the branch lumen  510 . This flaring process may turn some of the ends of the struts of the stent  550  inward. Such a configuration may penetrate and rupture the balloon  110 . Accordingly, the armored coil  120  may prevent the flared struts of the expanded stent  550  from rupturing the balloon  110 .  
         [0040]      FIG. 10  shows the puncture resistant balloon catheter  100  in an expanded state.  FIG. 10  is a cross-sectional view of the balloon catheter  100  along its longitudinal axis. With the aid of a wire guide  810  through a wire guide lumen  320 , a portion of the balloon catheter  100  may be maneuvered through the fenestration  520  and thereafter be expanded to deploy a distal portion of the stent  550  within the branched lumen  510 . The stent  550  may be delivered using a delivery sheath to keep it from being expanded. The delivery sheath can be withdrawn before expanding the stent  550 . With the delivery sheath withdrawn, the stent  550  is shown expanded and disposed over the armored coil  120 . The stent  550  is expanded by inflating balloon  110 . The balloon  110  becomes inflated when inflation fluid is passed through the inflation lumen  310 . In this example, the armored coil  120  also covers the tapered end  115  of the balloon  110 . The armored coil  120  is formed with tapered ends  114 ,  119  that may conform with the tapered ends  115  of the balloon  110 . Additionally, a portion of the interior of the armor coil  120  may be coated with an adhesive  565  to further secure the armored coil  120  to the surface of the balloon  110 . The inflation of the balloon  110  may enable the armored coil  120  to expand, which in turn may allow the stent  550  to expand within branched lumen  510 . The armored coil  120  may protect the balloon  110  from puncturing during the implantation of the stent  550 .  
         [0041]     The above figures and disclosure are intended to be illustrative and not exhaustive. This description will suggest many variations and alternatives to one of ordinary skill in the art. All such variations and alternatives are intended to be encompassed within the scope of the attached claims. Moreover, the advantages described herein are not necessarily the only advantages of the invention, and not all of the described advantages will be necessarily achieved with every embodiment of the invention. Those familiar with the art may recognize other equivalents to the specific embodiments described herein which equivalents are also intended to be encompassed by the attached claims.