Catheter having a funnel-shaped occlusion balloon of uniform thickness and methods of manufacture

Field Of The Invention

0001This invention relates to apparatus for removing emboli during vascular interventions and to a method of manufacturing an emboli catheter for use in an interventional procedure. More particularly, the apparatus of the present invention provide a catheter having an occlusion balloon of uniform thickness that facilitates retrograde flow and removes emboli from a treatment vessel via a funnel- shaped taper of the occlusion balloon.

Background of the Invention

0002Today there is a growing need to provide controlled access and vessel management during such procedures as stenting, atherectomy and angioplasty. Generally during these procedures there is a high opportunity for the release of embolic material. The emboli may travel downstream from the occlusion, lodging deep within the vascular bed and causing ischemia. The resulting ischemia may pose a serious threat to the health or life of a patient if the blockage forms in a critical area, such as the heart, lungs, or brain.

0003Several previously known apparatus and methods attempt to remove emboli formed during endovascular procedures by aspirating the emboli out of the vessel of interest using a catheter having an occlusion balloon. These previously known occlusion balloons, however, have various drawbacks, including variability in deployment of the balloon to the desired shape, inefficiency in removing emboli, and/or high cost and complicated processes associated with manufacturing the balloon.

0004<patcit id="pcit0001" dnum="EP0330376A"><text>EP 0 330 376</text></patcit> describes an occlusion catheter comprising an elongated shaft for introduction into a blood vessel, the shaft comprising an annular lumen for communicating with an inflatable occlusion balloon carried on the distal end of the shaft.

0005<patcit id="pcit0002" dnum="US20010044598A1"><text>US 2001/0044598 A1</text></patcit> describes methods and apparatus for removing emboli during an angioplasty, stenting or surgical procedure comprising a catheter having an occlusion element, an aspiration lumen, and a blood outlet port in communication with the lumen, a guide wire having a bell or pear-shaped balloon, a venous return catheter with a blood inlet port, and tubing that couples the blood outlet port to the blood inlet port.

0006In applicant's co-pending U. S. patent publication <patcit id="pcit0003" dnum="US2001044598A1"><text>US 2001/044598 A1, filed October 15, 1999</text></patcit>, applicant describes the use of a bell or pear-shaped occlusion balloon disposed on the distal end of an arterial catheter. The occlusion balloon comprises a compliant material having a variable thickness along its length to provide a bell-shape when inflated. The balloon is affixed to distal end of the catheter so that a distal portion of the balloon extends beyond the distal end of the catheter to provide an atraumatic tip or bumper for the catheter.

0007The balloon of that catheter may be formed using previously known techniques, such as varying the thickness of the balloon wall to achieve the preferred bell-shape in the deployed position. Such processes, however, can lead to variability in the final product due to the manufacturing process. Because variable thickness balloons present greater difficulties during manufacture than balloons having uniform wall thickness, the cost of such balloons may be higher.

0008In view of the foregoing limitations of previously known devices, it would be desirable to provide an apparatus for removing emboli from a vessel comprising an occlusion balloon of uniform thickness to enhance manufacturability of the occlusion balloon.

0009It also would be desirable to provide an apparatus for removing emboli from a vessel comprising an occlusion balloon of uniform thickness to reduce manufacturing cost and enhance product yield.

0010It further would be desirable to provide an apparatus for removing emboli from a vessel comprising a catheter having an occlusion balloon of uniform thickness that facilitates retrograde flow and efficiently removes emboli.

Summary of the Invention

0011In view of the foregoing, it is an object of this invention to provide an apparatus for removing emboli from a vessel comprising an occlusion balloon of uniform thickness to enhance manufacturability of the occlusion balloon.

0012It also is an object of the present invention to provide an apparatus for removing emboli from a vessel comprising an occlusion balloon of uniform thickness to reduce manufacturing cost and enhance product yield.

0013It further is an object of the present invention to provide an apparatus for removing emboli from a vessel comprising a catheter having an occlusion balloon of uniform thickness that facilitates retrograde flow and efficiently removes emboli.

0014According to a first aspect of the present invention there is provided an apparatus for removing emboli from a vessel during an interventional procedure, as defined in claim 1. According to a second aspect of the present invention there is provided a method of manufacturing an emboli catheter for use in an interventional procedure, as defined in claim 12. The foregoing objects of the present invention are accomplished by providing interventional apparatus comprising a catheter having proximal and distal ends, a working lumen extending therethrough and an occlusion balloon having proximal and distal ends disposed on the distal end of the catheter. The occlusion balloon has a contracted state suitable for insertion into a vessel and a deployed state configured to occlude antegrade flow in the vessel.

0015In a preferred embodiment, the catheter comprises an inner layer covered with a layer of flat stainless steel wire braid and a polymer cover. A distal section of the occlusion balloon is melt-bonded to a distalmost end of the inner layer and, optionally, to a distalmost end of the polymer cover to form a substantially seamless transition into the working lumen of the catheter. The proximal end of the occlusion balloon is everted and affixed to the polymer cover to form an inflation chamber between the polymer cover and the balloon.

0016In the deployed state, the occlusion balloon is configured to extend distal of the catheter and provides a funnel-shaped transition into the working lumen of the catheter. A distal edge of the occlusion balloon is configured to be in close proximity with an inner wall of a vessel to facilitate retrograde flow into the working lumen of the catheter and efficiently remove emboli. Additionally, because the occlusion balloon of the present invention comprises a uniform thickness, the balloon may be more reliable, easier to manufacture and more cost-effective than an occlusion balloon having a variable thickness along its length.

0017Preferred methods of making and using the apparatus of the present invention also are disclosed.

Brief Description of the Drawings

0018Further features of the invention, its nature and various advantages will be more apparent from the accompanying drawings and the following detailed description of the preferred embodiments, in which:

0019<figref idref="f0001">FIGS. 1A-1B</figref> are, respectively, side and sectional views of a previously known occlusion balloon in contracted and deployed states;

0020<figref idref="f0001">FIGS. 2A-2B</figref> are, respectively, a schematic view of apparatus in accordance with the present invention and a cross-sectional view along line A--A of <figref idref="f0001">FIG. 2A</figref>;

0021<figref idref="f0002">FIGS. 3A-3B</figref> are side sectional views illustrating a preferred configuration of the distal end of the catheter of <figref idref="f0001">FIG. 2</figref>;

0022<figref idref="f0003">FIGS. 4A-4B</figref> are side sectional views of the occlusion balloon of the present invention in contracted and deployed states, respectively; and

0023<figref idref="f0004">FIG. 5</figref> is a schematic view of apparatus of the present invention being used during an interventional procedure.

Description of the Preferred Embodiments

0024Referring to <figref idref="f0001">FIGS. 1A-1B</figref>, a bell-shaped occlusion balloon, as described in applicant's commonly assigned allowed U.S. patent publication <patcit id="pcit0004" dnum="US2001044598A1"><text>US 2001/044598 A1</text></patcit>, is described. Occlusion balloon 20 is shown in contracted and deployed states in <figref idref="f0001">FIGS. 1A and 1B</figref>, respectively. Balloon 20 is affixed to distal end 26 of catheter 22, for example, by gluing or a melt-bond, so that opening 27 in balloon 20 leads into lumen 28 of catheter 22. Balloon 20 preferably is wrapped and heat treated during manufacture so that distal portion 29 of the balloon extends beyond the distal end of catheter 22 and provides an atraumatic tip or bumper for the catheter. In accordance with manufacturing techniques which are known in the art, occlusion balloon 20 comprises a compliant material, such as polyurethane, latex or polyisoprene which has variable thickness along its length to provide a bell-shape when inflated.

0025As described hereinabove, the variable thickness characteristic of occlusion balloon 20, which is used to deploy the balloon to the preferred bell-shape, presents certain manufacturing challenges. In particular, manufacturing a balloon having a variable wall thickness can lead to reduced yield due to variability of the manufacturing process. Additionally, a variable thickness balloon may be difficult to manufacture and may have a higher cost relative to a balloon having a uniform thickness.

0026Referring now to <figref idref="f0001">FIGS. 2</figref>, a first embodiment of apparatus constructed in accordance with principles of the present invention is described. Apparatus 40 comprises catheter 41 having proximal and distal ends and working lumen 58 extending therethrough. Catheter 41 comprises occlusion balloon 42 having proximal and distal ends affixed to the distal end of catheter 41, and preferably comprises radiopaque marker band 65 disposed at the distal end of catheter 41 to facilitate positioning of the distal end of the catheter.

0027Occlusion balloon 42 comprises a uniform thickness material having a contracted state suitable for insertion into a vessel and a deployed state in which occlusion balloon 42 occludes antegrade flow in the vessel. In the deployed state, occlusion balloon 42 comprises distal taper 66 that is configured to provide a funnel-shaped transition into working lumen 58 so that blood flows in a non-turbulent fashion from a treated vessel into catheter 41. Additionally, distal edge 68 is configured to be in close proximity with an inner wall of a vessel to facilitate blood flow into catheter 41 and efficiently remove emboli.

0028Catheter 41 preferably comprises inner layer 60 of low-friction polymeric material, such as polytetrafluoroethylene ("PTFE"), covered with a layer of flat stainless steel wire braid 61 and polymer cover 62 (e.g., polyurethane, polyethylene, or PEBAX), as shown in <figref idref="f0001">FIG. 2B</figref>. Working lumen 58 is defined as a lumen within an interior surface of inner layer 60. Inflation lumen 63 preferably is disposed within polymer cover 62 so that the inflation lumen does not substantially increase the overall profile of catheter 41.

0029Apparatus 40 preferably further includes proximal hemostatic port 43, e.g., a Touhy-Borst connector, inflation port 44, and blood outlet port 48. Inflation port 44 is coupled to inflation lumen 63, which in turn is coupled to occlusion balloon 42. Proximal hemostatic port 43 and working lumen 58 of catheter 41 are sized to permit interventional devices, such as angioplasty balloon catheters, atherectomy devices and stent delivery systems to be advanced through the working lumen when a guidewire (not shown) is positioned within the working lumen.

0030Blood outlet port 48, which is in fluid communication with working lumen 58, may be coupled to an external aspiration device, e.g., a syringe, to cause blood flow distal of occlusion balloon 42 to flow into working lumen 58. Alternatively, in a preferred embodiment, blood outlet port 48 may be coupled to a venous return catheter to form an arterial-venous shunt suitable for providing retrograde flow in a treatment vessel. This aspiration embodiment comprising an arterial-venous shunt is described in detail in applicant's commonly-assigned, above U.S. patent publication <patcit id="pcit0005" dnum="US2001044598A1"><text>US 2001/044598 A1</text></patcit>.

0031Referring now to <figref idref="f0002">FIGS. 3</figref>, a preferred configuration of catheter 41 and a preferred method for affixing occlusion balloon 42 to the distal end of catheter 41 are described. In <figref idref="f0002">FIG. 3A</figref>, the distal end of catheter 41 is shown from a side sectional view as comprising inner layer 60 covered with a layer of flat stainless steel wire braid 61 and polymer cover 62. Radiopaque marker band 65 preferably is disposed at the distal end of catheter 41 between wire braid 61 and polymer cover 62, as shown in <figref idref="f0002">FIG. 3A</figref>. In accordance with principles of the present invention, occlusion balloon 42 comprises a uniform thickness along its length, as illustrated in <figref idref="f0002">FIGS. 3A-3B</figref>.

0032In a preferred method of manufacture, distal end 50 of occlusion balloon 42 is positioned atop polymer cover 62 near the distal end of catheter 41 and just distal of opening 70 of polymer cover 62, as shown in <figref idref="f0002">FIG. 3A</figref>. Distal end 50 of occlusion balloon 42 then is affixed to polymer cover 62, preferably using a melt-bond or, alternatively, using a biocompatible glue. At this time, proximal end 52 of occlusion balloon 42 extends freely beyond the distal end of catheter 41, as shown in <figref idref="f0002">FIG. 3A</figref>. For purposes of clarifying terminology used herein, although proximal end 52 of occlusion balloon 42 appears situated distal of distal end 50 in <figref idref="f0002">FIG. 3A</figref>, this is because proximal end 52 will subsequently be everted to extend proximal of distal end 50, as described hereinbelow.

0033In a next manufacturing step, distal section 51 of occlusion balloon 42, which is situated just proximal of distal end 50, is melt-bonded to at least one polymeric layer of catheter 41. Distal section 51 of occlusion balloon 42 is melt-bonded to distalmost end 85 of inner layer 60 and, optionally, to distalmost end 87 of polymer cover 62 to form fusion joint 67, as shown in <figref idref="f0002">FIG. 3A</figref>. The melt-bonding of the plurality of polymeric materials at fusion joint 67 provides substantially seamless transition 72 between occlusion balloon 42 and inner layer 60. Additionally, because fusion joint 67 is formed from a plurality of compliant polymeric materials, fusion joint 67 is capable of achieving a flexible range of motion.

0034Proximal end 52 of occlusion balloon 42 then is everted so that it extends proximally and radially outward from catheter 41, as shown in <figref idref="f0002">FIGS. 3B</figref> and <figref idref="f0003">4A</figref>. Proximal end 52 is affixed to polymer cover 62, preferably using a melt-bond or, alternatively, using a biocompatible glue, at a distance between about 10-20 mm proximal of the distal end of catheter 41, as shown in <figref idref="f0003">FIG. 4A</figref>. This creates inflation chamber 74 between polymer cover 62 and an interior surface of balloon 42. Opening 70, which is disposed in a lateral surface of polymer cover 62, is in fluid communication with inflation lumen 63 and inflation chamber 74, as shown in <figref idref="f0002">FIG. 3B</figref>. Proximal end 52 of occlusion balloon 42 may be stretched while it being affixed to polymer cover 62 so that apparatus 40 may achieve a reduced profile in the contracted state.

0035The fusion of occlusion balloon 42 to catheter 41.at fusion joint 67 and subsequent eversion of the balloon creates substantially seamless transition 72 into working lumen 58, as shown in <figref idref="f0002">FIG. 3B</figref>. In accordance with principles of the present invention, the provision of substantially seamless transition 72 may help reduce flow impedance into working lumen 58 and enhance flow within a treated vessel.

0036Referring now to <figref idref="f0003">FIGS. 4A-4B</figref>, deployment of apparatus 40 within vessel V of a patient is described. In <figref idref="f0003">FIG. 4A</figref>, occlusion balloon 42 is shown in a contracted state suitable for percutaneous and transluminal insertion into a patient's vessel. Occlusion balloon 42 is inflated via inflation port 44, inflation lumen 63 and opening 70, and deploys to a predetermined configuration having proximal taper 64 and distal taper 66, as shown in <figref idref="f0003">FIG. 4B</figref>. The predetermined configuration may be determined, for example, using a pre-molding process in accordance with manufacturing techniques that are known in the art. In the deployed state, an outer surface of central section 75, which is formed between proximal and distal tapers 64 and 66, is substantially flush with an inner wall of vessel V. As will be understood by those skilled in the art, the expanded diameter of central section 75 may be sized accordingly for different vessels.

0037Distal edge 68 is defined as a section of occlusion balloon 42 that is formed between central section 75 and distal taper 66. In the deployed state, distal edge 68 is configured to be in close proximity with an inner wall of vessel V to facilitate blood flow into working lumen 58 and efficiently remove emboli.

0038Distal taper 66 provides a funnel-shaped flow transition from distal edge 68 into working lumen 58. Additionally, as described hereinabove, fusion joint 67 provides substantially seamless transition 72 from occlusion balloon 42 into working lumen 58 due to the melt-bond between balloon 42 and inner layer 60 of catheter 41.

0039Referring now to <figref idref="f0004">FIG. 5</figref>, a preferred method for using apparatus 40 of <figref idref="f0001">FIG. 2A</figref> during an interventional procedure, such as balloon angioplasty, is described. In a first step, guidewire 83 is inserted into a patient's vasculature and a distal end of guidewire 83 is disposed just proximal of stenosis S, which is located in vessel V. A dilator (not shown) that is disposed within catheter 41 then is inserted over guidewire 83 to advance catheter 41 to a desired position proximal of stenosis S. When catheter 41 is properly positioned, e.g., as determined under fluoroscopy using radiopaque marker band 65, the dilator may be removed. Occlusion balloon 42 then is inflated via inflation port 44 of <figref idref="f0001">FIG. 2A</figref>, preferably using a radiopaque contrast solution, to occlude antegrade flow in vessel V. Aspiration is provided through working lumen 58 of catheter 41 to cause retrograde flow to occur in vessel V distal of occlusion balloon 42, as illustrated by the arrows in <figref idref="f0004">FIG. 5</figref>.

0040Aspiration may be provided through working lumen 58 via blood outlet port 48 using an external aspiration device, e.g., a syringe, or alternatively using a venous return catheter to form an arterial-venous shunt, as described hereinabove.

0041An interventional instrument, such as conventional angioplasty balloon catheter 80 having balloon 82, may be loaded through hemostatic port 43 and working lumen 58 and positioned within stenosis S, preferably via guidewire 83. Hemostatic port 43 is closed and the angioplasty balloon is actuated to disrupt stenosis S. As seen in <figref idref="f0004">FIG. 5</figref>, emboli E formed during the interventional procedure are directed into working lumen 58 via the retrograde flow established.

0042Occlusion balloon 42 provides a substantially uniform funnel-shaped transition from an inner wall of vessel V into working lumen 58 of catheter 41. Distal edge 68, which is configured to be in close proximity with an inner wall of vessel V, facilitates flow into working lumen 58 and efficiently removes emboli. Additionally, the funnel-shaped transition provided by distal taper 66 and substantially seamless transition 72 into the working lumen via fusion joint 67 improves retrograde flow dynamics into working lumen 58.

0043Advantageously, because the methodutilizes an occlusion balloon having a uniform thickness and relies on pre-molding of the occlusion balloon to obtain the desired deployed shape, a variable thickness occlusion balloon is not required. As noted hereinabove, use of an occlusion balloon having a uniform thickness provides several advantages, including enhanced manufacture, reduced cost and increased reliability.

0044While preferred illustrative embodiments of the invention are described above, it will be apparent to one skilled in the art that various changes and modifications may be made.