Adhesive-free bonded balloon for a balloon guiding catheter for minimum outer profile

Abstract

The present invention is titled "Adhesive-Free Bonded Balloon for Balloon Guide Catheter with Minimum Outer Profile". The present invention provides a balloon guide catheter having a catheter shaft and a balloon, the catheter shaft having an outer layer made of a refluxable material, the balloon having a bonding interface region with a plurality of perforations defined therein, the balloon being fixed around the outer layer by the refluxable material of the outer layer of the catheter shaft penetrating into the plurality of perforations to form a radially outward reflux bond between the catheter shaft and the balloon without using an adhesive. One or more reflux sheaths made of a refluxable material may also be disposed around the bonding interface region of the balloon and penetrate into the plurality of perforations to form a radially inward reflux bond.

Description

BACKGROUND OF THE INVENTION FIELD OF THE INVENTION

[0001] During the process of using an intravascular catheter to capture and remove thrombi, obstructions, or clots in a blood vessel, a compliant inflatable balloon can be used to block blood flow. The balloon of the balloon guide catheter of the present invention and the outer surface of the catheter shaft are fixed together at one or more binder-free bonding interface regions, thereby minimizing the outer profile / diameter while optimizing the bonding strength.

[0002] Related Art

[0003] Acute ischemic stroke is mainly caused by thrombotic or embolic obstruction (e.g., blockage) in the arteries of the brain. The obstruction is usually caused by a blood clot released from another part of the body, which travels in the antegrade direction (along the normal blood flow direction) through the blood vessel and eventually becomes lodged in the arteries of the nerves and blood vessels, where it blocks blood flow to areas of the brain.

[0004] A procedure called thrombectomy can be used to remove thrombi, obstructions, blockages, or clots lodged in a blood vessel using a mechanical retrieval device. During a thrombectomy procedure or treatment, a physician or interventionalist introduces a guide wire and a microcatheter together through the vasculature within an artery, usually located in the groin or arm, or directly through the carotid artery. The guide wire and the microcatheter are advanced together to a position proximal to the target clot, blockage, or obstruction. Then the guide wire is advanced through the clot, and then the microcatheter. When in a compressed state, a mechanical thrombectomy device can be guided through the lumen of the microcatheter to the target site. When emerging from the microcatheter, the mechanical thrombectomy device usually automatically expands to its initial expanded state. The mechanical thrombectomy device is typically made of a self-expanding biocompatible material such as nitinol. Aspiration through the catheter can be accompanied by or used in place of the mechanical retrieval device to remove the clot.

[0005] During thrombectomy, a balloon guide catheter is typically used to block blood flow by introducing inflation fluid into a compliant inflatable balloon. Combining a compliant inflatable balloon to the outer surface of a catheter shaft during the manufacturing process of a balloon guide catheter has two conflicting criteria, namely minimizing the outer profile / diameter at the bonding interface region where the balloon is mounted to the catheter shaft while maximizing the bonding strength and integrity.

[0006] It is desirable to design an improved balloon guide catheter having a binder-free bonding interface region where the balloon (compliant, semi-compliant, or non-compliant) is fixed to the outer surface of the catheter shaft to achieve optimal bonding strength and integrity while minimizing the outer profile or outer diameter. SUMMARY OF THE INVENTION

[0007] One aspect of the present invention relates to an improved balloon guiding catheter, where the balloon is coupled to the catheter without the use of an adhesive, thereby creating a maximized bond strength and integrity while minimizing the outer profile or outer diameter.

[0008] Another aspect of the present invention relates to a balloon guiding catheter having a catheter shaft and a balloon, the catheter shaft having an outer layer made of a reflowable material, the balloon having a bonding interface region with a plurality of perforations defined therein, and the balloon being fixed around the outer layer by the reflowable material of the outer layer of the catheter shaft penetrating into the plurality of perforations to form a radially outward reflow bond between the catheter shaft and the balloon. The balloon can be fixed to the catheter shaft without the use of an adhesive.

[0009] Another aspect of the present invention relates to a method for assembling a balloon guiding catheter. A plurality of perforations are pierced in the bonding interface region of the balloon, where the balloon can be fixed to the outer layer of the catheter shaft made of a reflowable material at the bonding interface region. The balloon with the plurality of perforations pierced therein is arranged around the outer layer of the catheter shaft. Along the bonding interface region, the reflowable material of the outer layer of the catheter shaft is heated, causing it to penetrate into the plurality of perforations, thereby forming a radially outward reflow bond between the outer layer of the catheter shaft and the balloon. Thus, the balloon can be fixed to the catheter shaft without the use of an adhesive. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The above and other features of the present invention will become more apparent from the following detailed description and the accompanying drawings illustrative of the present invention, where like reference numerals throughout the several views refer to like components, and where:

[0011] Figure 1 is a side view of an exemplary compliant inflatable balloon according to the present invention before being assembled around a catheter shaft, where the compliant inflatable balloon has a proximal bonding interface region and an opposing distal bonding interface region, each bonding interface region having a plurality of perforations defined therethrough;

[0012] Figure 2A is a partial side view of an assembled balloon guiding catheter including Figure 1 the compliant inflatable balloon and a catheter shaft having an outer layer of reflow material that reflows into a plurality of perforations defined in the compliant inflatable balloon, thereby forming a radially outward reflow bond, where the compliant inflatable balloon is depicted in a non-inflated state;

[0013] Figure 2B is Figure 2ALongitudinal cross-sectional view of an assembled balloon guide catheter, showing a radially outward reflux junction formed by permeating an outer layer of reflux material into a plurality of perforations defined in a compliant expandable balloon;

[0014] Figure 3 is Figure 2A radial cross-sectional view of the outer layer of the catheter shaft in;

[0015] Figure 4A is a partial longitudinal cross-sectional view of an alternative configuration, where two reflux sheaths / sleeves are separated from each other in the axial direction to form a 360° radial gap therebetween, and each reflux sheath / sleeve is fixed to the outer layer of the catheter shaft below the respective proximal and distal bonding interface regions of the compliant expandable balloon, where the compliant expandable balloon is shown in a non-expanded state;

[0016] Figure 4B is Figure 4A side view of the assembled catheter of;

[0017] Figure 5A is a partial longitudinal cross-sectional view of another design with a single reflux sheath / sleeve having a cutout or opening defined therein that is aligned with a compliant expandable balloon patch fixed below the catheter shaft, where the compliant expandable balloon is shown in a non-expanded state; and

[0018] Figure 5B is Figure 5A top view of the assembled catheter of. Detailed Description

[0019] The terms "distal" or "proximal" are used below in the description of the position or direction relative to the treating physician or medical interventionist. "Distal" or "distally" is the orientation away from the physician or interventionist or in the direction away from the physician or interventionist. "Proximal" or "proximally" or "at the proximal" is the position closer to the physician or medical interventionist or in the direction toward the physician or medical interventionist. The terms "occlusion", "clot", or "blockage" may be used interchangeably.

[0020] The balloon is typically adhered to the outer surface of the catheter shaft of the assembled balloon guide catheter via an adhesive. Using an adhesive to fix the balloon has several drawbacks: an increased bonding profile and difficulty in controlling / constraining the boundaries within which the adhesive remains. Thus, one aspect of the present invention is to avoid using an adhesive (adhesive-free bonding or non-adhesive bonding), where the compliant expandable balloon is fixed to the outer layer of the catheter shaft without sacrificing bonding integrity or strength.

[0021] During thrombectomy procedures, a balloon guiding catheter is typically employed to block blood flow by introducing an inflation fluid into a compliant, expandable balloon made of an elastic material (such as polyurethane, polymer blend, or latex), rather than by pressurized inflation. The ability of the compliant, expandable balloon to conform to the shape of the vasculature makes it particularly suitable for blocking blood flow. In other applications such as dilating blood vessels or opening obstructions, the balloon guiding catheter may utilize a non-compliant or semi-compliant balloon that is inflated by pressurization rather than using an inflation fluid. Specifically, a non-compliant balloon, typically made of polyester or nylon, expands blood vessels or opens obstructions when inflated at high pressure; while a semi-compliant balloon, made of materials such as Pebax or higher hardness polyurethane, is more compliant than a non-compliant balloon when inflated by pressurization, thus providing greater flexibility during delivery. Regardless of the type of balloon (compliant, semi-compliant, or non-compliant), there are two conflicting criteria for attaching the balloon to the outer surface of the catheter shaft during the manufacturing process, namely minimizing the outer profile / diameter at the attachment interface region where the balloon is mounted to the catheter shaft while maximizing the attachment strength and integrity. By way of example, the balloon guiding catheter of the present invention uses a compliant, expandable balloon to illustrate and describe for blocking blood flow through a blood vessel. It should be understood that the present invention is applicable to any type of balloon (e.g., compliant, semi-compliant, or non-compliant). Figure 1 is a side view of a compliant, expandable balloon sleeve 105 according to the present invention prior to assembly around a catheter shaft. The compliant, expandable balloon 105 has a proximal attachment interface region 110 and an opposing distal attachment interface region 115, wherein the compliant, expandable balloon 105 is capable of being secured around the catheter shaft 125 along the proximal attachment interface region 110 and the distal attachment interface region 115, respectively. Each of the proximal attachment interface region and the distal attachment interface region has a plurality of perforations 120 (e.g., holes, apertures, or openings) therethrough, which are made using, for example, a fine punching tool or other mechanical means. The axial length of each of the proximal attachment interface region 110 and the distal attachment interface region 115 having a plurality of perforations defined therein is preferably from about 2 mm to about 3 mm.

[0022] The compliant, expandable balloon 105 having a plurality of perforations 120 made in each of the proximal attachment interface region 110 and the distal attachment interface region 115 is positioned externally around the catheter shaft 125, as Figure 2A and Figure 2B shown. Figure 3 shows a radial cross-sectional view through an exemplary catheter shaft 125 showing its outer layer 130. The outer layer 130 of the catheter shaft is made of a refluxable material, preferably comprising a medical grade thermoplastic polyurethane (TPU) (e.g., - A material of medical-grade aliphatic polyether-based thermoplastic polyurethane). The catheter shaft 125 can be designed as needed to include any number of one or more inner layers radially inwardly disposed along the outer layer 130.

[0023] Specific regions of the compliant expandable balloon 105, preferably limited to those regions to be bonded to the catheter shaft (e.g., the proximal bonding interface region 110 and the distal bonding interface region 115 of the balloon sleeve; or the periphery of the balloon patch) are heated (e.g., heat and / or laser-generated), such that the outer layer 130 of the catheter shaft 125 flows back / melts and penetrates / bleeds upward through the perforations 120 (holes, apertures, openings), thereby forming a radially outward flowing-back joint therebetween. By way of illustrative example, heated jaws can be applied only around those regions of the compliant expandable balloon to be bonded, thereby restricting the heat to a specific region or distance.

[0024] To further strengthen the bond between the balloon and the catheter shaft, additional steps can be performed sequentially or simultaneously with forming the radially outward flowing-back joint to create supplementary radially inward flowing-back joints using one or more flowing-back sheaths / sleeves made of a flowing-back material (preferably a material including medical-grade thermoplastic polyurethane (TPU)). Preferably, the flowing-back material of the one or more flowing-back sheaths / sleeves is the same as the flowing-back material of the outer layer of the catheter shaft to ensure the flowing-back of both materials when heated at a predetermined temperature. Thus, flowing-back joints are formed both radially inwardly and radially outwardly in the proximal interface bonding region and the distal interface bonding region of the compliant expandable balloon. That is, when heated, the flowing-back / melted outer layer 130 of the catheter shaft 125 penetrates radially outwardly through the perforations 120, forming a radially outward flowing-back joint, while the flowing-back / melted flowing-back sheaths / sleeves 135, 140 penetrate radially inwardly through the perforations 120, thereby forming a radially inward flowing-back joint. The enhanced flowing-back joints (radially inwardly and radially outwardly) generated between the flowing-back / melting of the material for the flowing-back sheaths / sleeves 135, 140 and the outer layer 130 of the catheter shaft 125 entering the perforations 120 on either side of the compliant expandable balloon 105 optimize the bond integrity and strength while minimizing the likelihood of leakage without increasing the outer diameter / external profile.

[0025] In Figure 4A and Figure 4BIn one configuration shown, two return sheaths / sleeves are employed, i.e., one return sheath / sleeve is placed around each of the proximal bonding interface region 110 and the distal bonding interface region 115 of the compliant expandable balloon sleeve 105. That is, the proximal return sheath / sleeve 135 is disposed around the compliant expandable balloon, overlapping / covering the proximal bonding interface region 110, while the distal return sheath / sleeve 140 is positioned around the compliant expandable balloon, overlapping / covering the distal bonding interface region 115. Figure 4B The dashed lines in the side view of Figure 4B respectively depict the proximal edge 109 and the distal edge 114 of the compliant expandable balloon 105 covered by the respective proximal return sheath / sleeve 135 and distal return sheath / sleeve 140. A 360° radial gap 145 is formed between the proximal return sheath / sleeve 135 and the distal return sheath / sleeve 140 that are separated from each other in the axial / longitudinal direction. Preferably, each of the two return sheaths / sleeves is made of the same material as the outer layer 130 of the catheter shaft 125 to ensure return flow when heated at a predetermined temperature. When inflated with inflation fluid, the exposed 360° radial zone of the compliant expandable balloon patch 105 expands through the 360° radial gap 145, thereby forming a radial bulge or radial expansion (e.g., a tire-like shape).

[0026] An alternative design using a single return sheath / sleeve 137 having a cutout or opening 138 defined therein is shown respectively in Figure 5A and Figure 5B the longitudinal cross-sectional view and the top view of Figure 5A . In this configuration, since a single return sheath / sleeve 137 is used, the cutout or opening 138 defined in its axial / longitudinal side extends radially less than 360°. The size (axial / longitudinal and radial / lateral) of the cutout or opening 138 is slightly smaller than the circumference of the compliant expandable balloon patch 105'. During assembly, the single return sheath / sleeve 137 is aligned with and disposed radially outward of the compliant expandable balloon patch 105', thereby exposing the central region of the compliant expandable balloon patch 105' through the cutout or opening 138. When inflated with inflation fluid, the exposed central region of the compliant expandable balloon patch 105' expands through the cutout or opening 138, thereby forming a lateral bulge or lateral expansion.

[0027] For a given intravascular catheter, different aspects, features, designs, and configurations of the present invention can be combined as needed, with the intended goal of enhancing the integrity and strength of the bond between the balloon and the catheter shaft while minimizing the outer profile or outer diameter of the assembled catheter.

[0028] Accordingly, while the fundamental novel features of the invention which are applied to its preferred embodiments have been shown, described, and pointed out, it should be understood that various omissions, substitutions, and changes in form and detail may be made by those skilled in the art without departing from the spirit and scope of the invention. For example, all combinations of components and / or steps that perform substantially the same function in substantially the same manner to achieve the same result are expressly contemplated as being within the scope of the invention. Substitution of components from one described embodiment to another is also fully contemplated and envisioned. It should also be understood that the drawings are not necessarily drawn to scale, but are merely conceptual in nature. Accordingly, the only limitation intended is as indicated by the scope of the appended claims.

[0029] Each published patent, pending patent application, publication, journal article, book, or any other reference cited herein is hereby incorporated by reference in its entirety.

Claims

1. A balloon guiding catheter, comprising: A catheter shaft having an outer layer made of a refluxable material; And A balloon having a bonding interface region with a plurality of perforations defined therein, the balloon penetrating into the plurality of perforations through the refluxable material of the outer layer to form a radially outward reflux bond between the catheter shaft and the balloon to fix around the outer layer of the catheter shaft; Wherein the balloon is fixed to the catheter shaft without an adhesive, Wherein the balloon guiding catheter further comprises: a single reflux sheath made of a refluxable material; the single reflux sheath having an opening defined therein, the opening being aligned with the balloon; and wherein along the periphery of the opening around the bonding interface region of the balloon, the single reflux sheath penetrates into the plurality of perforations of the balloon through the refluxable material of the single reflux sheath to form a radially inward reflux bond to be fixed to the balloon.

2. The balloon guiding catheter according to claim 1, wherein the refluxable material of the outer layer comprises medical grade thermoplastic polyurethane.

3. The balloon guiding catheter according to claim 1, wherein the balloon is a patch or a sleeve.

4. The balloon guiding catheter according to claim 1, wherein the refluxable material of the single reflux sheath is the same as the refluxable material of the outer layer of the catheter shaft.

5. A method for assembling a balloon guiding catheter, the method comprising the steps of: Piercing a plurality of perforations in a bonding interface region of a balloon, at which bonding interface region the balloon can be fixed to an outer layer of a catheter shaft made of a refluxable material; Arranging the balloon with the plurality of perforations pierced around the outer layer of the catheter shaft; and Heating along the bonding interface region such that the refluxable material of the outer layer of the catheter shaft penetrates into the plurality of perforations to form a radially outward reflux bond between the outer layer of the catheter shaft and the balloon; Wherein the balloon is fixed to the catheter shaft without an adhesive, Wherein the method further comprises the steps of: Positioning a single reflux sheath made of a refluxable material covering the bonding interface region disposed around the balloon; The single reflux sheath having an opening defined therein, the opening being aligned with the balloon; And wherein along the periphery of the opening around the bonding interface region of the balloon, by heating the refluxable material of the single reflux sheath, such that it penetrates into the plurality of perforations of the balloon to form a radially inward reflux bond to fix the single reflux sheath to the balloon.

6. The method according to claim 5, wherein the refluxable material of the outer layer comprises medical grade thermoplastic polyurethane.

7. The method according to claim 5, wherein the refluxable material of the single reflux sheath is the same as the refluxable material of the outer layer of the catheter shaft.

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