Method for laminating ePTFE to a Nitinol braid with a smooth outer diameter
The laminating method of ePTFE liners onto a nitinol braid structure addresses the need for smaller arterial incisions and reduced thrombogenic risks in intracardiac blood pumps by forming a laminated sheath with a smooth inner and conformal outer surface.
Patent Information
- Application Number
- JP2025502856
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-07-22
- Filing Date
- 2023-07-21
- Publication Date
- 2025-07-30
AI Technical Summary
Existing expandable introducer sheaths for intracardiac blood pumps require improvements to reduce the arterial incision size and minimize thrombogenic risks during medical device insertion.
A method of laminating expanded polytetrafluoroethylene (ePTFE) liners onto a nitinol braid structure using an expandable silicone tube, where the inner and outer ePTFE liners are laminated to the nitinol structure by expanding the silicone tube within a heating die, followed by cooling and depressurization to form a laminated expandable sheath.
The method reduces the required arterial incision size and minimizes thrombogenic risks by creating a laminated sheath with a smooth inner surface and conformal outer surface, reducing hemodynamic thrombosis and insertion force.
Smart Images
Figure 2025524695000001_ABST
Abstract
Description
Technical Field
[0001] Cross - Reference to Related Applications
[0001] This application claims the benefit and priority of U.S. Provisional Patent Application No. 63 / 391,384, filed on July 22, 2022, which is hereby incorporated by reference herein.
[0002] Technical Field
[0002] Describes a method of attaching ePTFE to a Nitinol structure such as an expandable sheath.
Background Art
[0003] Background
[0003] Intracardiac heart pump assemblies can be introduced into the heart surgically or percutaneously and used to deliver blood from one location in the heart or circulatory system to another location in the heart or circulatory system. For example, when placed within the heart, an intracardiac pump can pump blood from the left ventricle of the heart into the aorta or from the inferior vena cava into the pulmonary artery. The intracardiac pump can be powered by a motor (and associated drive cable) located outside the patient's body or an on - board motor located within the patient's body. Some intracardiac blood pump systems can operate in parallel with the native heart to supplement cardiac output and partially or completely remove the load on the components of the heart. Examples of such systems include devices of the IMPELLA® family (Abiomed, Inc., Danvers Mass.).
[0004]
[0004] In one common approach, an intracardiac blood pump is inserted via the femoral artery using an introducer sheath, which can be a detachable introducer sheath, by a catheter procedure. The sheath can alternatively be inserted at other locations such as the femoral vein or any other route for delivery of the pump to assist either the left or right side of the heart.
[0005]
[0005] The introducer sheath can be inserted into the femoral artery by arteriotomy to create an insertion path for the pump assembly. Then, a portion of the pump assembly is advanced intra-arterially through the lumen of the introducer sheath. The required size of the arteriotomy is a strong concern. Accordingly, expandable introducer sheaths have been developed to reduce the arterial incision opening required to accommodate the sheath and the medical device passing through it. Accordingly, further improvements to expandable introducer sheaths are still sought.
Summary of the Invention
Means for Solving the Problems
[0006] Brief Summary
[0006] Described herein is a method for laminating a liner of expanded polytetrafluoroethylene (ePTFE) onto the surface of an expandable tube that can be made of nitinol or braided nitinol. Both ePTFE and nitinol are well-known materials and are not detailed herein. The method provides an expandable silicone tube that, when expanded, contacts one of an inner ePTFE liner and / or an outer ePTFE liner to a heating die that laminates the ePTFE liner to the expandable tube.
[0007]
[0007] In one aspect, a method for manufacturing an expandable sheath is described. According to one aspect of this method, an expandable tubular structure is disposed within an outer liner. An inner liner is inserted into the expandable tubular structure. The expandable tubular structure having the inner liner and the outer liner is disposed on an inflatable silicone tube. The inflatable silicone tube is disposed within a heating die that is either between the inflatable silicone tube and the inner liner or outside of the outer liner. The silicone tube is expanded, thereby laminating the inner liner and the outer liner to the expandable tubular structure by bringing one of the inner liner or the outer liner into contact with the heating tube. Thereafter, the heating die is cooled and the silicone tube is depressurized and contracted. The laminated expandable sheath is removed from the die and the inflatable silicone tube.
[0008]
[0008] In one aspect, each of the inner liner and the outer liner is expanded polytetrafluoroethylene (ePTFE). In a further aspect, thermoplastic polyurethane is applied to the inner surface of the outer liner or the outer surface of the inner liner.
[0009]
[0009] In one aspect, the expandable tubular structure is made from braided nitinol wire.
[0010]
[0010] In a further aspect, pressurizing the inflatable silicone tube brings the inner liner and the outer liner into contact with the inner surface of the braided structure and the inner surface of the heating die, respectively. In the above aspect, the inflatable silicone tube has a free outer diameter that is smaller than the inner diameter of the inner liner. In a further aspect, the inflatable silicone tube is configured to expand to an outer diameter that brings one of the inner liner or the outer liner into contact with the heating die. In one aspect, the inflatable silicone tube is positioned inside the inner liner.
[0011]
[0011] In one aspect, the heating die is located outside the outer liner. In an alternative aspect, the heating die is located inside the inner liner. In one aspect, the heating die is brought to a temperature of 110 °C. In one aspect, the expandable silicone tube has a soft durometer from about 10 Shore A to about 50 Shore A. In one aspect, the inner liner of the laminated expandable sheath has an irregular surface that conforms to the contour of the braided structure. In another aspect, the outer liner of the laminated expandable sheath has a smooth surface. In a further aspect, the laminated expandable sheath includes an inner liner, an outer liner, and an expandable tubular frame structure between the inner liner and the outer liner.
[0012]
[0012] Also described is an expandable laminated sheath having an expandable tubular frame structure with an inner surface and an outer surface, an expanded polytetrafluoroethylene inner liner laminated to the inner surface of the expandable braided tubular structure made of nitinol, and an expanded polytetrafluoroethylene outer liner laminated to the outer surface of the expandable braided tubular structure made of nitinol, the expandable laminated sheath being formed by inserting an expandable silicone tube into the inner liner and expanding the silicone tube until either the inner surface of the inner liner or the outer surface of the outer liner contacts a heating die.
[0013]
[0013] In one aspect, either the outer surface of the inner liner or the inner surface of the outer liner is coated with thermoplastic polyurethane. In one aspect, the expandable tubular frame is a braided structure made of nitinol. In one aspect, the inner liner and the outer liner are formed from expanded polytetrafluoroethylene (ePTFE).
[0014] Brief Description of the Drawings
[0014] Aspects of the subject matter to be described are shown in the drawings.
Brief Description of the Drawings
[0015]
Figure 1
[0015] Shown is a cross-section of a nitinol structure having inner and outer ePTFE liners.
Figure 2
[0016] Shows a cross-section of a heating die according to one aspect of the present technology.
Figure 3
[0017] Shows a cross-section of a silicone tube according to one aspect of the present technology.
Figure 4
[0018] Shows an assembly of the structures shown in FIGS. 1-3 that can be used to fabricate an ePTFE laminate nitinol structure.
Figure 5
[0019] Shows how a silicone tube is used to laminate an ePTFE liner to a nitinol braid in one aspect of the present technology.
Figure 6
[0020] Shows how the inner ePTFE liner is laminated to the inner diameter of the nitinol braid while the outer ePTFE liner remains smooth according to one aspect of the present technology.
Figure 7
[0021] Shows how the outer ePTFE liner is laminated to the outer diameter of the nitinol braid while the inner ePTFE liner remains smooth according to one aspect of the present technology.
Figure 8
[0022] A flowchart according to one aspect of the method described herein.
Best Mode for Carrying Out the Invention
[0016] Detailed Description
[0023] Embodiments of the present disclosure will be described in detail with reference to the drawings in which like reference numerals identify similar or identical elements. It should be understood that the disclosed embodiments are merely examples of the present disclosure that can be implemented in various forms. To avoid obscuring the present disclosure with unnecessary detail, well-known functions or structures will not be described in detail. Accordingly, the specific structural and functional details disclosed herein should not be construed as limiting, but rather as a representative basis for the claims and as a basis for teaching those skilled in the art to adopt the present disclosure in substantially any appropriately detailed structure in a variety of ways.
[0017]
[0024] In one aspect, an ePTFE liner is attached to the inner surface of the tubular frame. In another aspect, a primer is formed between the ePTFE liner and the inner surface of the lumen defined by the tubular frame. In another aspect, the introducer sheath assembly has an outer ePTFE liner formed on the outer surface of the tubular frame. In another aspect, the introducer sheath assembly has inner and outer ePTFE liners formed on both the inner and outer surfaces of the tubular frame. The tubular frame can be made of braided nitinol wire. Nitinol is a well-known alloy of nickel and titanium, and nickel and titanium are in approximately equal proportions.
[0018]
[0025] Referring to FIG. 1, an expandable sheath structure 100 is shown having a nitinol structure 110 with an inner ePTFE liner 120 and an outer ePTFE liner 130. Each of the nitinol structure 110, the inner ePTFE liner 120, and the outer ePTFE liner 130 is a tube.
[0019]
[0026] In one aspect, the nitinol structure is a braided nitinol wire structure having the following characteristics, which are given by way of example and not limitation. i. The nitinol structure has an outer diameter (OD) of from about 3.9 to about 4.1 mm, and the nitinol structure is formed from a braid of hard nitinol wire having a diameter of from about 75 μm to about 125 μm. The nitinol can be SE508 nitinol. In one aspect, the braid is combined or wound in a 48-end 2x2 braid pattern having a braiding angle of from about 34° to about 40° under a pressure of from about 16.5 PPI to about 17.6 PPI (pounds per square inch) with respect to a pin of about 4.15 mm using an active temperature (Af) of from about 10° C. to about 20° C. ii. Thermoplastic polyurethane (TPU) primer (the coating amount is about 20 mg to about 60 mg for a Nitinol braid with a length of 150 cm). In one example, the hardness is about 75 Shore A, the specific gravity is about 1.1 to about 1.4 SG, and the tensile strength at 50% elongation is about 100 psi to about 650 psi. The ultimate elongation of the material is about 350% to about 750%. The properties of Nitinol and polyurethane are well known, and these are examples of the properties of these materials suitable for the structures described in the claims. As used herein, "about" means ±10% of the stated value.
[0020]
[0027] Each of the inner and outer ePTFE liners has the following characteristics, which are given by way of example and not limitation. i. Each ePTFE liner has an inner diameter (ID) of about 3.9 mm to about 4.1 mm, each ePTFE liner has a thickness of about 0.040 mm to about 0.060 mm, the density is about 0.4 g / cc, and the tensile strength at 50% elongation is about 0.15 to about 0.45 N / mm. ii. TPU OD seal (the coating amount can be about 30 mg to about 75 mg for an ePTFE liner with a length of 150 cm). In one example, the hardness is about 42 - 73 Shore A, it has a specific gravity of about 0.96 SG to about 1.04 SG, and the tensile strength at 50% elongation can be about 130 psi to about 455 psi. The ultimate elongation of this material can be about 500% to about 626%.
[0021]
[0028] The properties of ePTFE are well known, and these are examples of the properties of materials suitable for the structures described in the claims.
[0022]
[0029] Referring to FIG. 2, this drawing shows a heating die 200 that defines an inner diameter approximately equal to the target final outer diameter of an expandable sheath having an inner ePTFE liner 120 and an outer ePTFE liner 130 laminated on a Nitinol structure. In one aspect, the target final outer diameter is about 4.5 mm to about 4.6 mm.
[0023]
[0030] Referring to FIG. 3, this drawing shows a silicon tube 300A having a free outer diameter smaller than the inner diameter of the inner ePTFE liner 120 but configured to expand under internal pressure up to an outer diameter 300B larger than the diameter of the inner ePTFE liner 120. As used herein, the free outer diameter is the outer diameter of the silicon tube when it is in an unexpanded state. Preferably, the expandable silicon tube has an outer diameter (OD) of about 3.0 mm to about 3.8 mm and an inner diameter (ID) of about 1.0 mm to about 3.3 mm. In one example, the hardness is from about 10 Shore A to about 50 Shore A, and the internal pressure of the expandable silicon tube is from about 1.6 psi to about 7 psi. In one aspect, the heating die 200 is configured to reach from about 90° C. to about 150° C. in about 2 minutes to 20 minutes. The heating die 200 is cooled by "heat off" for about 5 minutes to about 20 minutes, an air flow for about 1 minute to about 10 minutes, and water cooling for about 1 minute to about 5 minutes.
[0024]
[0031] Referring to FIG. 4, an assembly of an inner ePTFE liner 120 and an outer ePTFE liner 130 with a Nitinol braid 110 sandwiched therebetween is shown. The expandable silicon tube 300A is located inside the inner ePTFE liner 120, and the heating die 200 is located outside the outer ePTFE liner 130. According to this method, the heating die 200 is set to a temperature of 110° C., the Nitinol structure (having the inner and outer ePTFE liners) is loaded onto the expandable silicon tube, and then slid into the heating die 200.
[0025]
[0032] Referring to FIG. 5, a partial cross-sectional view of the assembly shown in FIG. 4 with the silicon tube 300B in an expanded state is shown. The structure (the Nitinol structure 110 between the inner ePTFE liner 120 and the outer ePTFE liner 130) is pressed against the inner surface of the heating die 200. Since silicon has a soft durometer (e.g., from Shore 10A to about 50A), the silicon tube 300B is pushed up against the Nitinol braid 110, laminating the inner ePTFE liner 120 to the inner diameter of the Nitinol braid structure 110.
[0026]
[0033] Referring to FIG. 6, a partial cross-sectional view of the assembly after removal from the tool (the tool being a heating die and an expandable silicone tube) is shown. The assembly is removed by contracting (depressurizing) the expandable silicone tube. The inner ePTFE liner 120 has an irregular surface that conforms to the contour of the braided nitinol structure 110. The outer ePTFE liner 130 has a smooth surface. The inner surface of the assembly is washed with saline during use. Therefore, the inner surface may not prolong the risk of hemodynamic thrombosis. The inner surface also reduces the contact surface area with the devices passed through the structure and reduces the insertion force required for those devices.
[0027]
[0034] FIG. 7 is an alternative embodiment of the content shown in FIG. 6. The structure of FIG. 7 is fabricated by providing a heating die (not shown) inside the inner diameter of the inner ePTFE liner 120. An expandable silicone tube is disposed on the outer diameter of the structure and applies pressure to the outer ePTFE liner 130 during expansion. The resulting structure has a smooth inner ePTFE liner 120 and a conformal outer ePTFE liner 130. The textured outer ePTFE coating diameter poses a risk of thrombogenicity due to low surface shear rates, low velocities, and regions of blood recirculation.
[0028] FIG. 8 illustrates a method for manufacturing the expandable sheath structure described herein. First, in step 501, a Nitinol braided structure is slid or disposed within an outer ePTFE liner. In step 502, an inner ePTFE liner is slid or disposed within the Nitinol braided structure. In step 503, the assembly of the Nitinol braided structure and the inner and outer ePTFE liners is slid or inserted onto an expandable silicone tube such that the expandable silicone tube is disposed within the lumen of the assembly. In step 504, the assembly inserted onto the silicone tube is disposed within a heating die such that the heating die surrounds the assembly. In step 505, the expandable silicone tube is pressurized and expanded to force the inner ePTFE liner into contact with the inner surface of the Nitinol braided structure and to push the Nitinol braided structure into forced contact with and against the inner surface of the outer ePTFE liner and the heating die 200. Thus, pressurizing the expandable silicone tube enables laminating the inner and outer ePTFE liners to the inner surface of the braided structure and the outer surface of the braided structure, respectively, to form the expandable sheath structure. In step 506, the heating die is cooled. In step 507, the silicone tube is depressurized and the expandable silicone tube is contracted. In step 508, the laminated expandable sheath structure is removed from the die and the expandable silicone tube.
[0029] Described herein are: i) sliding an expandable tubular structure within an outer liner; ii) sliding an inner liner within the expandable tubular structure; iii) inserting an assembly of the expandable tubular structure, the inner liner, and the outer liner onto an inflatable silicone tube; iv) placing the assembly with the inflatable silicone tube within a heating die; v) pressurizing the inflatable silicone tube to form an expandable sheath, expanding the inflatable silicone tube, and laminating the inner liner and the outer liner to the inner surface and the outer surface of the expandable tubular structure, respectively; vi) cooling the heating die; vii) depressurizing the silicone tube, thereby contracting the inflatable silicone tube; and viii) removing the laminated expandable sheath from the die and the inflatable silicone tube, a method for manufacturing an expandable sheath.
[0030] In the above method, each of the inner liner and the outer liner is expanded polytetrafluoroethylene (ePTFE). In any of the above aspects, thermoplastic polyurethane is applied to the inner surface of the outer liner. In any of the above aspects, thermoplastic polyurethane is applied to the outer surface of the inner liner. In any of the above aspects, the expandable tubular structure is made of braided nitinol wire. In any of the above aspects, pressurizing the expandable silicone tube can bring the inner liner and the outer liner into contact with the inner surface of the expandable tubular structure and the inner surface of the heating die, respectively. In any of the above aspects, the expandable silicone tube has a free outer diameter smaller than the inner diameter of the inner liner. In any of the above aspects, the expandable silicone tube is configured to expand to an outer diameter that brings one of the inner liner or the outer liner into contact with the heating die. In any of the above aspects, the expandable silicone tube is located inside the inner liner. In any of the above aspects, the heating die is located outside the outer liner. In any of the above aspects, the heating die is located inside the inner liner. In the above aspect, the heating die is brought to a temperature of 110 °C. In any of the above aspects, the expandable silicone tube can have a soft durometer from about 10 Shore A to about 50 Shore A. In any of the above aspects, the inner liner of the laminated expandable sheath has an irregular surface that conforms to the contour of the expandable tubular structure. In any of the above aspects, the outer liner of the laminated expandable sheath can have a smooth surface. In any of the above aspects, the laminated expandable sheath can include an inner liner, an outer liner, and an expandable tubular structure between the inner liner and the outer liner.
[0031] This specification also describes an expandable laminated sheath having an expandable tubular frame structure with an inner surface and an outer surface, an expanded polytetrafluoroethylene inner liner laminated to the inner surface of the expandable tubular frame structure made of nitinol, and an expanded polytetrafluoroethylene outer liner laminated to the outer surface of the expandable tubular structure. In any of the above aspects, this expandable type can be formed by inserting an expandable silicone tube into the inner liner and expanding the silicone tube until either the inner surface of the inner liner or the outer surface of the outer liner contacts a heating die. According to the above aspect, either the outer surface of the inner liner or the inner surface of the outer liner is coated with thermoplastic polyurethane. According to the above aspect, the expandable tubular frame is a nitinol structure formed from braided nitinol wire. In any of the above aspects, the inner liner and the outer liner can be formed from expanded polytetrafluoroethylene (ePTFE).
[0032]
[0035] Those skilled in the art will understand that it is also possible to make certain modifications to the present disclosure without departing from the scope of the present disclosure, with reference to the above content and various drawings. Although some embodiments of the present disclosure have been illustrated, the present disclosure is intended to be broad in scope as permitted by the art and to be read in a similar manner to this specification, and thus the present disclosure is not intended to be limited to those drawings. Therefore, the above description should not be construed as limiting, but should be construed as merely illustrative of specific embodiments. Those skilled in the art will envision other modifications included within the scope and spirit of the claims appended hereto.
Claims
**Claim 1** A method for manufacturing an expandable sheath, comprising: sliding an expandable tubular structure into an outer liner; sliding an inner liner into the expandable tubular structure; inserting an assembly of the expandable tubular structure, the inner liner, and the outer liner onto an inflatable silicone tube; placing the assembly with the inflatable silicone tube into a heating die; pressurizing the inflatable silicone tube to form the expandable sheath, expanding the inflatable silicone tube, and laminating the inner liner and the outer liner to the inner surface and the outer surface of the expandable tubular structure, respectively; cooling the heating die; depressurizing the silicone tube to thereby contract the inflatable silicone tube; and removing the laminated expandable sheath from the die and the inflatable silicone tube. A method comprising the above steps. **Claim 2** The method according to claim 1, wherein each of the inner liner and the outer liner is expanded polytetrafluoroethylene (ePTFE). **Claim 3** The method according to claim 1 or 2, wherein a thermoplastic polyurethane is applied to the inner surface of the outer liner. **Claim 4** The method according to claim 1 or 2, wherein a thermoplastic polyurethane is applied to the outer surface of the inner liner. **Claim 5** The method according to any one of claims 1 to 4, wherein the expandable tubular structure is made of braided nitinol wire. **Claim 6** The method according to any one of claims 1 to 5, wherein pressurizing the inflatable silicone tube causes the inner liner and the outer liner to contact the inner surface of the expandable tubular structure and the inner surface of the heating die, respectively. **Claim 7** The method according to any one of claims 1 to 6, wherein the inflatable silicone tube has a free outer diameter smaller than the inner diameter of the inner liner. **Claim 8** The method according to any one of claims 1 to 7, wherein the inflatable silicone tube is configured to expand to an outer diameter that causes one of the inner liner or the outer liner to contact the heating die. **Claim 9** The method according to any one of claims 1 to 8, wherein the inflatable silicone tube is located inside the inner liner. **Claim 10** The method according to any one of claims 1 to 8, wherein the heating die is located outside the outer liner. **Claim 11** The method according to any one of claims 1 to 8, wherein the heating die is located inside the inner liner.
12. The method according to any one of claims 1 to 11, wherein the heating die is brought to a temperature of 110 °C.
13. The method according to any one of claims 1 to 12, wherein the expandable silicone tube has a soft durometer from about 10 Shore A to about 50 Shore A.
14. The method according to any one of claims 1 to 13, wherein the inner liner of the laminated expandable sheath has an irregular surface that conforms to the contour of the expandable tubular structure.
15. The method according to any one of claims 1 to 14, wherein the outer liner of the laminated expandable sheath has a smooth surface.
16. The method according to any one of claims 1 to 15, wherein the laminated expandable sheath includes the inner liner, the outer liner, and the expandable tubular structure between the inner liner and the outer liner.
17. An expandable tubular frame structure having an inner surface and an outer surface, An expanded polytetrafluoroethylene inner liner laminated to the inner surface of the expandable tubular frame structure made of nitinol, An expanded polytetrafluoroethylene outer liner laminated to the outer surface of the expandable tubular structure An expandable laminated sheath comprising: An expandable laminated sheath formed by inserting an expandable silicone tube into the inner liner and expanding the silicone tube until either the inner surface of the inner liner or the outer surface of the outer liner contacts a heating die.
18. The expandable laminated sheath according to claim 17, wherein either the outer surface of the inner liner or the inner surface of the outer liner is coated with thermoplastic polyurethane.
19. The expandable laminated sheath according to claim 17 or 18, wherein the expandable tubular frame is a nitinol structure formed from braided nitinol wire.
20. The expandable laminated sheath according to any one of claims 17 to 19, wherein the inner liner and the outer liner are formed from expanded polytetrafluoroethylene (ePTFE).