Patent Publication Number: US-2017361073-A1

Title: Balloon catheter with centralized vent hole

Description:
PRIORITY DATA AND INCORPORATION BY REFERENCE 
     This application claims benefit of priority to U.S. Provisional Patent Application No. 60/752,878 filed Dec. 23, 2005 which is incorporated by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present invention relates generally to balloon catheter assemblies for use in angioplasty and stent delivery procedures. In particular, the present invention provides a system and method for delivery of a balloon catheter to a stenosed blood vessel and inflation of the dilation balloon to expand a stent implant and/or the stenosed blood vessel. 
     BACKGROUND ART 
     A large number of balloon catheters have been devised for angioplasty and stent delivery procedures. Commonly a guide wire is first introduced percutaneously into the patient&#39;s vascular system, advanced and then steered to the site of a stenosis. A dilation balloon or catheter is then advanced over the guide wire until the balloon is positioned within the stenosis so that on inflation, the balloon will compress the stenosis by dilatation of the blood vessel to thereby re-establish a more adequate blood flow path past the stenosis. To facilitate even compression pressure distribution along the length of the stenosed lesion, it is preferred that the dilation balloon be centered relative to the stenosis so as to fully engage the lesion. 
     Balloon dilation catheters have also been utilized in stent delivery in which the stent is disposed about the balloon and inflated into place at the stenosis. Catheter operators seek accurate deployment of the stent directly on the diseased tissue of the vessel in order to avoid stent migration to either side of the diseased tissue thereby avoiding or minimizing the chance of leaving some of the diseased tissue untreated. Accurate stent deployment is also desirable in order to avoid adversely affecting healthy tissue. 
     Stent misplacements may occur because of specific inflation dynamics experienced by the expandable balloon when deploying the stent. Known stent delivery catheters inflate the balloon portion of the catheter preferentially from either the distal or proximal end of the balloon. During inflation, the expanding balloon may form an unsymmetrical growth or inflation wave that may be said to drive or plow the stent so that it opens progressively from one end to the other along the front of the inflation wave. The wave may sometimes cause the stent to disengage prematurely from the balloon. This form of balloon inflation is referred to as “end-to end” preferential inflation. End-to-end balloon inflation may further cause a deploying stent to displace longitudinally away from its intended delivery site, thereby potentially ineffectively treating the diseased lesion within the patient&#39;s vasculature. 
     Known balloon dilation catheters used in connection with stent deployment and/or other applications are shown and described in several U.S. Patents including: U.S. Pat. Nos. 6,136,011; 5,908,448; 5,226,880; 5,176,619; 4,811,737; 5,409,495; 5,334,148; 5,169,386; and 3,939,820. In U.S. Pat. No. 6,592,568, described is one inflation technique for medial inflation of the balloon using an intermediate balloon inside a stent delivering dilation balloon to concentrate a bolus of fluid medially for distribution through the dilation balloon. The intermediate balloon can either be rupturable or otherwise provide a controlled fluid leak to release fluid into the dilation balloon. This technique, however, adds complexity to the procedure by requiring controlled bursting or leakage of an intermediate balloon. 
     Another complex stent delivery and deployment device is shown and described in U.S. Pat. No. 6,203,558 in which a stent is disposed about an inflation balloon. The inflation balloon is disposed about a catheter assembly having an inner shaft and an outer shaft. The inflation balloon is inflated from its proximal end by the delivery of a pressurized fluid flowing between the inner and outer shafts. The deployment device also includes an expandable securement device disposed about the inner shaft and disposed within the inflation balloon. The inner shaft has a single lumen for carrying a guide wire and fluid for expanding the securement device. To expand the securement member, fluid is discharged from the single lumen through a valve disposed along the inner shaft and centrally located within the securement member. For example, see FIG. 34 of the &#39;558 Patent. The expanded securement member secures the engagement between the inflation balloon and the stent. 
     Another patent, U.S. Pat. No. 6,648,854, also discloses a single lumen balloon tipped catheter for inflating a balloon having an operating pressure of about one atmosphere. The catheter effectively utilizes a single lumen to carry both a guide wire and inflation fluid. However, where balloons having higher operating pressures are utilized, a single lumen device may not be sufficient to provide the adequate pressure for inflating the balloon. 
     DISCLOSURE OF INVENTION 
     A preferred embodiment according to the present invention provides a catheter assembly for engaging a stenosis. The assembly includes a catheter including a wall having a proximal end and a distal end along a longitudinal axis. The wall preferably has an interior surface and an exterior surface, in which the interior surface defines a first lumen and a second lumen spaced apart and disposed about the longitudinal axis. The wall preferably defines an opening extending between the interior surface and the exterior surface. The opening is in communication with the first lumen to define a flow path having an angle incident to the longitudinal axis. The exterior surface further preferably includes a first radiopaque and/or radiographic marker; and a second radiopaque and/or radiographic marker spaced apart from one another along the longitudinal axis so as to be substantially equidistant from the opening. The assembly also preferably includes a balloon having a first end and a second end defining a holding volume therebetween. The first end and the second ends are preferably sealed about the exterior surface. The opening is disposed within the holding volume thereby placing the first lumen in sealed fluid communication with the holding volume. The first and second ends of the balloon are further preferably spaced substantially equidistantly about the opening along the longitudinal axis. 
     Applicant recognizes that it is desirable to have an apparatus and method for centrally locating the dilation balloon catheter assembly within a stenosed region to ensure proper engagement between the stenosis and the dilation balloon. The catheter assembly can be combined with a stent to form a stenosis treatment device. More specifically, the stent can be disposed about the balloon to engage the stent with a stenosis. It is desirable to have an apparatus and method for medial inflation of a dilation balloon to evenly expand the stent. Preferably, proper medial inflation and location of the dilation balloon in the stenosed region forms a “dog bone” shape. The “dog bone” shape results as the stenosis compresses evenly on the central portion of the dilated balloon and/or stent. This balloon inflation dynamic can limit stent migration along the balloon and thereby minimize any misplacement in stent deployment. Accordingly, it is desirable to provide for consistent medial inflation of the dilation balloon such that the balloon expands evenly and radially from a central point, thus avoiding uneven distortions in the dilation balloon as it is inflated. 
     In another preferred embodiment, the first marker and the second marker are disposed within the holding volume. In addition, at least one of the first marker and the second marker are radiopaque and/or radiographic. Moreover, the exterior surface of the wall of the catheter defines a first diameter outside the holding volume and a second diameter inside the holding volume. Preferably, the second diameter is smaller than the first diameter and the catheter includes a taper portion between the first and second diameter. 
     Another preferred embodiment according to the present invention provides a fluid delivery device. The fluid delivery device can include an elongated member having a proximal end and a distal end defining a first lumen and a second lumen spaced apart along a longitudinal axis. The first lumen is preferably configured to convey a fluid, and the member preferably has an opening disposed between the proximal and distal ends in fluid communication with the lumen. The delivery device further preferably includes a first radiopaque and/or radiographic marker and a second radiopaque and/or radiographic marker. The first marker and the second marker are preferably disposed along the longitudinal axis and spaced from one another so as to be substantially equidistant from the opening. 
     Another preferred embodiment according to the present invention provides a method of engaging a stenosis with an inflatable member having a first end and a second end in which the inflatable member has disposed therein at least a portion of a tubular member having a first radiopaque and/or radiographic marker and a second radiopaque and/or radiographic marker spaced along a longitudinal axis of the tubular member. The method preferably includes locating the first and second markers equidistantly about a portion of the stenosis such that the inflatable member is substantially centered along the length of the portion of the stenosis. The method further preferably includes: flowing a fluid in a channel of the tubular member along the longitudinal axis and introducing a sufficient amount of the fluid into the inflatable member through an opening of the tubular member to expand the inflatable member substantially radially and engage the stenosis. Another embodiment further includes disposing a stent about the inflatable member such that introducing a sufficient amount of fluid into the inflatable member further engages the stent with the stenosis. 
     Another preferred embodiment provides a method of dilating a stenosis in which the method can be achieved by locating a first marker of a catheter assembly to one side of a portion of a stenosis and locating a second marker on the opposite side of the portion such that the first and second markers are generally equidistant from the portion of the stenosis. The method further includes disposing a fluid fill opening of an inflatable member generally equidistant between the first and second markers, and expanding the inflatable member via the fluid fill opening substantially equally longitudinally and radially about the central region to engage and apply an expansion force to the portion. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate a preferred embodiment of the invention, and, together with the general description given above and the detailed description given below, serve to explain the features of the invention. 
         FIG. 1  is an illustrative perspective view of an embodiment of a balloon catheter assembly. 
         FIG. 1A  is an isometric view of the proximal end of the assembly of  FIG. 1 . 
         FIG. 1B  is a geometric plan view of the assembly of  FIG. 1 . 
         FIG. 2  is a detailed portion of the distal end of the assembly of  FIG. 1 . 
         FIG. 2A  is a detailed portion of the assembly of  FIG. 2 . 
         FIG. 3  is a cross-sectional detail of the assembly of  FIG. 2 . 
         FIG. 3A  is perspective view of a portion of the assembly of  FIG. 2 . 
         FIG. 4  is an illustrative example of the assembly of  FIG. 1  used in a stenosis treatment procedure. 
     
    
    
     MODE(S) FOR CARRYING OUT THE INVENTION 
       FIG. 1  shows a preferred embodiment of a catheter assembly  10  for engaging a stenosis. More specifically, the catheter assembly  10  can be configured for angioplasty procedures in which an inflatable member or balloon  12  is introduced into a blood vessel for engagement with a diseased portion of the blood vessel such as, for example, a stenosis or for engagement with an implantable prosthesis such as, for example, a stent or stent-graft. The catheter assembly  10  can be further configured for introducing an implant or stent (not shown) into the blood vessel to treat the stenosis. The stent can be disposed about the balloon  12  and the catheter assembly  10  can deliver and position the stent in engagement with the stenosis for implantation. Alternatively, the stent can be delivered to the stenosis independently of the catheter assembly  10 . The catheter assembly  10  can subsequently engage the stent at the stenosis site and inflate the balloon  12  to expand the stent for engagement with the stenosis. 
     Generally, the catheter assembly  10  includes a catheter  20  having a proximal portion  24  a distal portion  22 . The catheter  20  preferably is an elongated tubular member having a wall  21  forming a exterior surface  23  and an interior  25  surface (not shown) defining a longitudinal axis III-III. The catheter  20  is preferably formed by extrusion of a thermoplastic material such as, for example, PEBAX 7300® thermoplastic material with a gel content of 9 percent or less compounded with 10 percent Bismuth Subcarbonate. Preferably disposed at the proximal portion  24  is a connector  26  having a first port  28  for introducing a guide wire into the catheter  20  and a second port  30  for introducing a fluid. Disposed at the distal portion  22  of the catheter  20  is the dilation balloon  12 . The dilation balloon  12  is preferably disposed about the distal portion  22  of the catheter  20  so as to locate an opening  36  in the catheter  20  within the holding volume  18  of the balloon  12 . Fluid is exchanged between the balloon  12  and the catheter  20  through the opening  36  to inflate and deflate the balloon  12 . To assist an operator in locating the balloon  12  along a stenosis or other targeted region, the catheter  20  can include first and second, preferably radiographic and/or radiopaque, markers  38 ,  40  along the distal portion  22  inside the holding volume  18  of the balloon  12 . 
     The balloon  12  of catheter assembly  10  preferably has a first end  14 , a second end  16  to define the holding volume  18  therebetween. The first and second ends  14 ,  16  can be disposed about the catheter  20 . Preferably, the first end  14  and second end  16  of the balloon  12  are sealed about the catheter  20  so as to enclose a distal portion  22  of the catheter  20  within the holding volume  18  in a fluid tight manner. For example, the first and second ends  14 ,  16  can be thermally bonded to the exterior surface  23  of the catheter  20  to form a fluid tight seal. Alternative bonding techniques can be used to seal the ends  14  and  16  to the catheter  20  such as, for example, laser or adhesive bonding techniques. In addition, the balloon  12  can be coupled to the catheter  20  in any other manner to enclose the distal portion  22  of the catheter  20  within the holding volume  18  in a fluid tight manner. The balloon  12  is preferably constructed from a nylon material, such as, Nylon 12 or Nylon 11, or alternatively from other suitable thermoplastic polymers such as, for example, polyether block amide (PEBA), polyethylene, polyethylene terephthalate (PET). Moreover, the balloon can be a composite material balloon formed from a combination of Nylon and other polymers or a combination of ultra high molecular weight polyethylene by itself or with PET. Preferably, the balloon  12  defines a sufficient strength in an inflated state so as to dilate or expand a stent or blood vessel. 
     One technique for forming the balloon  12  includes blow molding a Nylon or PET tube under heat in a mold to form the desired shape, for example, a circular cylindrical body with two conical tapered ends. The formed balloon  12  can be disposed over and thermally bonded to the catheter  20 . U.S. Pat. No. 5,755,690 describes one method for forming a multiple layer high strength balloon for dilation catheter in which a parison, of orientable semicrystalline polymer such as, for example PET, is disposed within a mold with one end of the parison sealed and the other end secured to a fluid source such as, for example, a gas. The parison is axially drawn and radially expanded within the mold to form an expanded balloon. The expanded balloon can then be exposed to a heat step in order to increase crystallinity in the balloon for dimensional stability. The balloon can then be removed from the mold and disposed about the catheter and thermally bonded thereto. Alternatively to thermally bonding the balloon  12 , an adhesive can be employed to bond the balloon  12  to the catheter  20 . 
     The distal portion  22  and the proximal portion  24  of the catheter  20  are preferably formed as a unitary construction joined together by a transition section  46 . Alternatively, the distal portion  22  and the proximal portion  24  can be distinct elements mechanically joined together by the transition  46 . Preferably, the outer diameter of the proximal portion  24  is larger than the outer diameter of the distal portion  22  of the catheter  20 . The transition section  46  is preferably tapered from the proximal portion  24  to the distal portion  22 . Alternatively, transition section  46  can have a constant diameter to join the proximal portion  24  to the distal portion  22  thereby forming a step transition from the proximal portion  24  to the distal portion  22 . 
     The connector  26  disposed at the proximal end  24  of the catheter  20  can be coupled to the catheter  20  by any suitable techniques such as, for example, interference fit, thread connection or press fit. The connector  26  is preferably disposed proximal of the balloon  12 . The connector  26  is configured for introducing a fluid, guide wire or any other instrumentation into the catheter  20 . Specifically, the connector  26  includes a first port  28  configured for receipt of a guide wire (not shown) to be inserted along the vein or artery of the patient. The catheter assembly  10  can be disposed about the guide wire so that an operator can guide the assembly  10  along the wire to locate the assembly to a desired location relative to the stenosis within the vein or artery. More specifically and preferably, the balloon  12  can be generally centered across the stenosed lesion. The first port  28  is preferably aligned parallel to or coaxial with the longitudinal axis III-III of the catheter  20 . 
     The connector  26  can further include a second port  30  configured to connect to a fluid source (not shown). The fluid source can be, for example, a syringe or other pump/vacuum device for delivery of a fluid. The fluid is preferably a liquid and can be, for example, a dye, a saline solution or any other contrast fluid to inflate the balloon  12 . Shown in  FIG. 1A  is another embodiment of the connector  26 . The second port  30  can be configured for receipt of a syringe as a fluid source to inject and withdraw fluid through the assembly  10 . The second port  30  of  FIG. 1  is preferably in fluid communication with the first port  28  within the connector  26 , however the connector  26  can be configured so as to isolate the fluids from the second port  30  with the first port  28 . The port  30  can form an angle incident with the catheter  20 . Preferably, the port  30  forms an acute angle incident to the longitudinal axis III-III of the catheter  20  in the direction of fluid flow moving distally away from an operator. During a procedure, the fluid is preferably introduced into the second port  30  and further into the catheter  20 . The fluid is discharged from an opening  36  in the distal portion  22  of the catheter  20  and into the holding volume  18  to expand the balloon  12 . Preferably, the fluid is introduced into the balloon  12  to expand the balloon radially from the opening  36 , along and about the longitudinal axis III-III. The port  30  can also be used to extract fluid from and deflate the balloon  12 . Fluid can be drawn from the balloon  12  into the catheter  20  preferably through the opening  36  and returned to the fluid source via the connector  26  and port  30 . 
       FIG. 1  and  FIG. 1B  show the balloon  12  in an inflated state with  FIG. 1B  providing particular geometric relationships of the assembly  10 . In the inflated state, the balloon  12  is shown as a substantially tubular or cylindrical member along the longitudinal axis III-III. In a plane perpendicular to the longitudinal axis III-III, the balloon  12  defines a cross-sectional section that is preferably circular, however other cross-sections are possible such as, for example, oval, multi-lobed or other polygons. The width w (preferably the diameter) of the balloon  12 , as seen in  FIG. 1B , can range from about 1 millimeter to about 40 millimeters, preferably range from about 1 millimeter to about 26 millimeters and even more preferably range from about 3 millimeters to about 20 millimeters, and the length l of the balloon  12  can range from about 10 millimeters to about 120 millimeters. Each end of the balloon  12  is preferably conical so as to preferably defines a cone angle a relative to a line parallel to the longitudinal axis III-III. The cone angle can range from about five degrees (5°) to about thirty degrees (30°) depending upon the length l of the balloon. The dimensions A, B and C of the catheter  20  can vary along with the width w and length l of the balloon  12 . More specifically, dimension A measured from the first preferably radiopaque and/or radiographic marker  38  to the second preferably radiopaque and/or radiographic marker  40  can be of any suitable length and preferably any one of about, 10 millimeters, 15 millimeters, 20 millimeters, 30 millimeters, 40 millimeters, 60 millimeters, 80 millimeters, 100 millimeters, to about 120 millimeters in length. Dimension B, measured from the transition section  46  to the connector  26  can preferably be of any suitable length and preferably, any one of about, 40 centimeters, 75 centimeters, 115 centimeters, 130 centimeters, to about 140 centimeters in length. Dimension C measured from the transition section  46  to the second marker  40  can preferably be any one of about, 10 millimeters, 15 millimeters, to about 20 millimeters in length. 
     Referring again to  FIG. 1 , the catheter assembly  10  can also include a deflator  32  that is preferably a sliding member  32  disposed about the outer surface  23  of the catheter  20 . The sliding member  32  can be permitted to slide along the catheter  20  between the distal and proximal portions  22 ,  24 . The sliding member  32  can be configured to assist in deflating the balloon member  18  by passing over the balloon  12  to displace any fluid and/or air in the holding volume  18 . The sliding member  32  can include a central channel through which the balloon  12  and the catheter  20  can pass. The body of the sliding member  32  is preferably substantially spool shaped to provide a low profile and easy handling for the operator; however, other geometries are possible permitting manual manipulation. The catheter assembly  10  can also include a removable cap  34 . The cap  34  can engage and disengage from the balloon  12  and the distal portion  22  of catheter  22  to protect the balloon  12  from damage when not in use. 
       FIG. 2  shows an enlarged view of the distal portion  22  of the catheter  20  sealed within the balloon  12 . The distal portion  22  of the catheter  20  further includes the opening  36 . Preferably, first and second ends  14 ,  16  of the balloon  12  are secured about the catheter  20  so as to be equidistantly spaced from the opening  36  and thus place the opening  36  in a substantially central location within the holding volume  18  of the balloon  12 . Any fluid introduced into the catheter  20  can be discharged through the opening  36  to inflate the balloon  12  from an initial deflated state or volume (not shown) to a substantially inflated state or volume (as shown in  FIG. 2 ). 
     Shown in  FIG. 2A  is the plan view detail of the opening  36 . The opening  36  is preferably rectangular and elongated in the direction of the longitudinal axis III-III so as to deliver and evacuate a sufficient volume of fluid to respectively inflate and deflate the balloon  12 . The opening  36  can further include a chamfer or transition  37  from the interior of the catheter  20  to the outer surface  23 , and the edges of the opening  36  along the outer surface  23  are preferably rounded to assist in achieving the desired flow characteristics. Where, for example, the opening  36  is rectangular, the dimensions of opening  36  can measure about 0.2 centimeters in length and about 0.02 centimeters in width. Generally, opening  36  can have any dimensioned geometry and transition characteristics such as, for example, a substantially circular, oval or polygonal, so long as the desired flow characteristics are obtained for the rapid inflation and deflation of the balloon  12 . Preferably the opening  36  is dimensioned and configured in a manner that provides for the inflation and deflation of the balloon  12  within a time period that minimizes the time for which the blood vessel may be occluded by the balloon  12 . As described above, the dimensions of the catheter  20  can vary with the dimensions of the balloon  12 . Accordingly, the dimensions of the opening  36  and the balloon  12  can be such as to define a relationship over various configurations of the catheter  20 . Specifically, in one preferred embodiment, the area of the opening  36  and the fully expanded holding volume  18  of the balloon  12  can define a ratio of area to volume. This ratio can be constant over the various configurations of the catheter  20 . Alternatively, the ratio of the area of the opening  36  and the fully expanded holding volume  18  of the balloon  12  can be variable over the various configurations of the catheter  20 . 
     The centralized location of the opening  36  shown in  FIG. 2  relative to the balloon  12  can provide a fluid distribution within the balloon  12  to facilitate the even and radial expansion of the balloon  12  from the deflated state to the inflated state. More specifically, the fluid discharging from the substantially central point within the holding volume  18  of the balloon  12  engages interior surfaces of the balloon equally radially and evenly along the direction of the longitudinal axis III-III. Thus, uneven concentrations of fluid or waves which can distort the shape of the balloon  12  are minimized or otherwise avoided. This can ensure that a target area (e.g., stenosis or stent) is engaged fully and evenly by the balloon  12  or stent to produce the preferable “dog bone” shape the balloon  12 . In a case where the balloon  12  is being used to implant a stent, the centralized expansion of the balloon  12  can ensure that the stent is expanded substantially evenly along its length. 
     The distal portion  22  of the catheter  20  further includes the first marker  38  and the second marker  40  disposed on the exterior surface  23  of the catheter  20 . Preferably, the markers  38 ,  40  are made of a radiopaque and/or radiographic material such as, for example, 18 Karat Gold, platinum, tantalum, BaSO 4 , Iridium to make the catheter  20  or at least the distal portion  22  visible under fluoroscopic observation. The markers  38 ,  40  can be used by an operator to guide the catheter assembly  10  under fluoroscopic observation to a desired location within the blood vessel. The first and second radiopaque and/or radiographic markers  38 ,  40  are preferably spaced apart and located along the longitudinal axis III-III such that the markers are equidistantly spaced from the opening  36 . More preferably, the markers  38 ,  40  are disposed within the holding volume  18 . Because the first and second ends  14 ,  16  of the balloon  12  are also preferably centered about the opening  36 , the first and second markers  38 ,  40  can facilitate the centering of the balloon  12  with respect to the target area. In particular, a clinician can utilize the radiopaque markers  38 ,  40  under fluoroscopic observation to center the opening  36  along the length of the target area, such as a stenosed lesion, and because of the fixed relation of the balloon ends  14 ,  16  to the opening  36 , the balloon is thereby preferably centered with respect to the target region for properly engaging the length of the target region. 
     Shown in  FIG. 3  is a cross-sectional view of a portion of the distal portion  22  of the catheter  20 . The interior surface  25  of the wall  21  forming the catheter  20  can further define a first channel or lumen  42 , preferably parallel to the longitudinal axis III-III. The lumen  42  can extend from the distal portion  22  into the proximal portion  24  of catheter  20  for communication with the second port  30  of the connector  26  in order to exchange a fluid, preferably a liquid, between the balloon  12  and the fluid source for inflation/deflation of the balloon  12 . The inner diameter of the lumen  42  is dimensioned to provide a sufficient flow of fluid given the delivery pressures from the fluid source such as, for example, a syringe. The inner diameter of the first lumen  42  can remain constant over the entire length of the catheter  20  or alternatively, the inner diameter of the first lumen  22  can change over the length of the catheter  20 . The lumen  42  is preferably offset from the centerline longitudinal axis III-III of the catheter  20 . 
     To facilitate fluid exchange between the balloon  12  and the catheter  20 , the lumen  42  is in fluid communication with the holding volume  18  via the opening  36  shown in  FIGS. 2 and 3 . More specifically, the opening  36  is positioned relative to the lumen  42  so as to define a fluid path having an angle incident to the longitudinal axis III-III. Fluid conveyed along the lumen  42  can be discharged from the opening  36  and into the holding volume  18  to expand the balloon  12 . Preferably, the flow path is substantially orthogonal to the longitudinal axis III-III to radially disperse the fluid from a substantially central portion of the holding volume  18 . Alternatively, the opening  36  can be positioned and configured so as to define a fluid path having an acute angle with longitudinal axis III-III so long as the fluid path can be dispersed from a substantially central portion of the holding volume  18 . 
     Shown in  FIG. 3A  is an end view of the catheter  20 . Preferably, the cross-section of the first lumen  42  is substantially rectangular and more preferably is crescent shape to convey an adequate flow of fluid to and from the holding volume  18 . The first lumen  42  can be dimensioned and configured so as to adequately fit within the overall size constraints of the catheter  20  such as, for example, the outer diameter of the catheter  20  and the demands on cross-sectional area of the catheter  20  to accommodate any additional lumen. The cross-sectional area of the lumen  42  can define other geometries such as substantially circular, for example, so long as the lumen  42  is dimensioned to convey the adequate fluid flow. In a preferred embodiment, the lumen  42  is sealed at the distal end so as to provide a sufficient discharge pressure at the opening  36  to promote the even radial expansion of the balloon  12 . Generally, the balloon  12  is rated for an operational pressure ranging from about 4 atmosphere (atm.) to about 8 atmosphere (atm.) and is more preferably about 8 atm., which corresponds to an operational delivery pressure of about 125 psi. Depending on the size of the balloon  12 , the balloon  12  can further be configured for rated burst pressures ranging from about 8 atm. to about 16 atm. Alternatively, the lumen  42  can have multiple discharge openings so long as a sufficient discharge pressure is provided at the opening  36 . 
     Fluid in the holding volume  18  can be drawn through the opening  36  and into the lumen  42  to deflate the balloon  12 . In addition to facilitating the radial expansion of the balloon  12 , the central positioning of the opening  36  relative to the holding volume  18  can maximize the time for which the opening  36  remains patent as fluid is drawn through the opening  36  and the balloon  12  collapses about the distal end  22  of the catheter  20  and eventually over opening  36 . Accordingly, the positioning of the opening  36  can control the efficiency of deflation of the balloon  12 . The efficiency of balloon deflation can define the time required to deflate the balloon  12  thereby defining the period that an inflated balloon  12  blocks or restricts the flow of blood through the blood vessel. Generally, it is desired that the time period for which the expansion of balloon  12  blocks blood flow through the blood vessel be minimized. 
     The catheter  20  shown in  FIG. 3  preferably includes a second channel or lumen  44  distinctly defined by the wall  21  extending parallel to the longitudinal axis III-III and the first lumen  42 . The second lumen  44  is dimensioned and configured to receive a guide wire upon which the catheter assembly  10  can translate. The second lumen  44  separates the guide wire from the fluid flow in the lumen  42 , thereby eliminating interference with the flow or pressure characteristics of the fluid by the presence of the guide wire. Preferably, the second lumen  44  extends from the distal end to the proximal end of the catheter  29  for communication with the first port  28  of the connector  26 . The second lumen  44  is preferably dimensioned and configured to receive the guide wire from the port  28 . The guide wire can be a conventional surgical guide wire such as, for example, stainless steel type  302  or  304  having an outer diameter of about 0.25 millimeter. The first and second lumen  42 ,  44  can alternatively be defined by distinct tube members within a single larger catheter tube (not shown). 
     The inner diameter of the second lumen  44  can remain constant over the entire length of the catheter  20  or alternatively, the inner diameter of the second lumen  44  can change over the length of the catheter  20  to accommodate space demands on the overall cross-sectional area of the catheter  20 . Preferably, the overall cross-sectional area of the catheter  20  remains constant over the various configurations of the catheter  20  discussed above. Alternatively, the overall cross-sectional area of the catheter  20  can vary proportionally with any one or more of the dimensions defining the catheter  20  such as, for example, the catheter&#39;s overall length or the lengths A, B or C described above. Shown in  FIG. 3A  is the cross-section of the lumen  44  as being substantially circular to provide the guide wire a substantially smooth wall through which to pass. Alternatively, other geometries are possible such as rectangular, oval or any other configuration so long as the lumen  44  is dimensioned to permit passage of the guide wire. 
     The second lumen  44  is preferably offset from the centerline longitudinal axis III-III of the catheter  20  to accommodate the dimension and configuration of the first lumen  42  for the delivery of the proper operating pressure for inflating the balloon  12 . The catheter can be dimensioned to accommodate additional lumen to provide channels for the insertion of other fluids or devices such as, for example, a third lumen to carry a temperature probe (not shown). 
     Shown in  FIG. 4  is an illustrative depiction of a stent delivery procedure in which the preferred embodiment of the catheter assembly  10  described above is locating and positioning a stent  50  along a stenosis  60  for expansion of the stenosed lesion and blood vessel  62 . The catheter assembly  10  is preferably disposed about a guide wire  52 , and an operator using the assembly  10  under fluoroscopy observation can align the balloon  10  and the stent  50  with the stenosis and further identify a portion of the stenosis  60  to which a direct expansion force using the balloon  12  of the assembly  10  can be applied. Preferably, the identified portion is the central portion of the stenosis  60 . Accordingly, the operator slides the catheter assembly  10  along the guide wire  52  to align the radiopaque markers  38 ,  40  equidistantly about the central portion of the stenosis  60  and thereby align a substantially central region of the balloon  12  with the central portion of the stenosis. 
     A contrast fluid can be channeled along the catheter  20  and introduced into the holding volume  18  of the balloon  12  through the opening  36  to fully dilate the balloon  12  and the stent  50  as shown. The preferably fixed centralized relation of the opening  36  to the markers  38 ,  40  aligns the opening  36  with the identified portion of the stenosis to be expanded, and with the opening  36  being preferably centrally located in the holding volume  18 , the balloon  12  and stent  50  are preferably evenly and radially expanded about the central region of the balloon  12  into engagement with the stenosis to apply expansion forces at least to the identified portion. 
     The various configurations of the catheter assembly  10  described herein provide numerous advantages in the performing angioplasty and stent delivery procedures. The catheter  20  preferably includes two spaced apart lumen for separately carrying a guide wire and an inflation fluid. The separately dedicated lumen can facilitate delivery of the inflation fluid at the proper operating pressure to expand the inflation balloon  12  by minimizing or eliminating interference of the guide wire with the fluid flow or delivery pressure. The opening  36  of catheter  20  is preferably disposed centrally within the holding volume  18  to facilitate central and localized fluid delivery within the holding volume  18  to promote even radial expansion of the balloon  12 . The even radial expansion of the balloon  12  can ensure proper engagement between the balloon  12  and the stent or stent graft so as to evenly radially expand the stent device and prevent migration of the stent device along the balloon  12 . In addition, the centralized location of the opening  36  relative to the holding volume  18  can increase the efficiency of the balloon deflation by maximizing the patency of the opening  36  to withdraw fluid from the balloon  12  while minimizing the time balloon remains in an expanded state to occlude the blood vessel being treated. In addition, the markers  38 ,  40  are preferably located within the holding volume  18  and relative to the opening  36  of the catheter  20  to provide the necessary visual indicators to center the balloon  12  relative to the target area or region. The radiopaque and/or radiographic markers  38 ,  40  assist in properly locating the balloon and/or stent or stent graft relative to the center of a target region or center. 
     While the present invention has been disclosed with reference to certain embodiments, numerous modifications, alterations and changes to the described embodiments are possible without departing from the sphere and scope of the present invention, as defined in the appended claims. Accordingly, it is intended that the present invention not be limited to the described embodiments, but that it has the full scope defined by the language of the following claims, and equivalents thereof. As used herein, the singular form of “a,” “an,” and “the” include the plural referents unless specifically defined as only one.