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Hyper-elastic, high strength dilatation balloon made from multi-block copolymers

a copolymer and balloon technology, applied in the field of balloons, can solve the problems of stenosis that requires treatment, polymer materials with a relatively low yield point, and follow the original stress-strain curve, and achieve high elastic recovery, low profile, and high hoop strength

Inactive Publication Date: 2005-06-02
MEDTRONIC VASCULAR INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention relates to a new type of dilatation balloon that has low profile, high hoop strength, high elasticity, and high elastic recovery. The balloons are made from a special type of polymer called a multiblock copolymer, which has unique mechanical properties. The balloons can be used in various applications such as angioplasty and stent delivery. The invention also includes a process for producing the polymeric extrudate used for the balloons. The technical effects of the invention include improved balloon performance and durability.

Problems solved by technology

Often, however, a stenosis requires treatment with multiple balloon inflations.
These polymeric materials have a relatively low yield point.
However, since this realignment is permanent, the balloon will not follow its original stress-strain curve on the subsequent inflation-deflation cycles.
Despite the use of high strength engineering polymers, access to highly occluded vessels and lesions in small vessels is still limited.
Dilatation balloons currently available do not have a proper balance of competing properties.
While balloons made from polyethylene terephthalate (PET) can have lower profile than other balloons, such as polyamide copolymer balloons, the PET balloon is stiff, has a higher modulus, and therefore has inferior trackability.
While balloons made from polyamide copolymers have better trackability than PET balloons due to their lower modulus, they have higher profiles thus limiting their application.
Furthermore, in attempting to produce low profile balloons by wrapping the balloon, the wrapping process often serves to reduce the burst strength of the balloon.
An additional disadvantage is that dilatation balloons are not highly elastic.
In the event that a patient has multiple lesions, a new catheter is used for each lesion thus adding to the cost and time of the procedure.

Method used

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  • Hyper-elastic, high strength dilatation balloon made from multi-block copolymers
  • Hyper-elastic, high strength dilatation balloon made from multi-block copolymers
  • Hyper-elastic, high strength dilatation balloon made from multi-block copolymers

Examples

Experimental program
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Effect test

example 1

[0078] A polymeric extrudate was formed as a tubular preform for a dilatation balloon. A multiblock copolymer was used as the base material. A triblock copolymer was used having the structure (C-E-C), wherein C and E denote poly(cyclohexylethylene) (PCHE) and hydrogenated butadiene, respectively. The butadiene block is a mixture of 1-2 and 1-4 addition, which upon hydrogenation, results in a block of random poly(ethylene) (PE) and poly(ethylethylene) (PEE). The triblock copolymer is described in detail in U.S. Pat. No. 6,455,656 B2; U.S. Pat. No. 6,451,924 B1; U.S. Pat. No. 6,426,390 B1; and U.S. Pat. No. 6,376,621 B1, all of which are incorporated herein in their entireties by reference. The triblock polymer was dissolved in dioctylphthalate (DOP), where the polymer concentration was about 75 wt. %, thus creating a gel. The gel was extruded at a temperature just below the order-disorder transition temperature. The gel was subsequently drawn to 400%. The extruded and drawn samples w...

example 2

[0079] Following a similar procedure, a pentablock copolymer was extruded having structure (C-E-C-E-C), wherein C and E denote poly(cyclohexylethylene) (PCHE) and hydrogenated butadiene, respectively. The butadiene block is a mixture of 1-2 and 1-4 addition, which upon hydrogenation, results in a block of random poly(ethylene) (PE) and poly(ethylethylene) (PEE). The polymer is described in U.S. Pat. No. 6,455,656 B2; U.S. Pat. No. 6,451,924 B1; U.S. Pat. No. 6,426,390 B1; and U.S. Pat. No. 6,376,621 B1. For Deborah numbers between 0.1 and 100, the macroscopic microdomain alignment was perpendicular, and a transverse alignment was also seen for Deborah numbers between 10 and 100. Similar mechanical responses were measured for the pentablock copolymer as the triblock copolymer, except the pentablock copolymer was found to have superior strength-elasticity balance as compared with the triblock extrudate.

[0080] Following a similar procedure, one can produce tubular preforms comprising ...

example 3

[0082] Following a similar procedure as Example 1, a pentablock copolymer having molecular weight of about 65 kg / mole and comprising about 60 wt. % of the poly(cyclohexylethylene) block and about 10 wt. % of the poly(ethylethylene) block was mixed with dioctylphthalate to form a gel having about 75 wt. % polymer. The gel was extruded and the extrudate was pre-strained or aligned by hand. The elasticity and elastic recovery of the sample was studied using a tensile machine. FIGS. 6A and 6B show the stress vs. strain (hysteresis) curves. The curves show that the material is highly elastic and substantially recovers from strains of about 4, 10, 18 and 40% without permanent deformation. FIG. 6A shows no failure of the material until strains of about 120%.

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Abstract

A self-wrapping dilatation balloon comprising a multiblock copolymer having high elasticity and elastic recovery from nominal strains greater than about 30% is described. Also described herein, is a polymeric extrudate for making a dilatation balloon comprising a multiblock copolymer having tensile strength in the range of about 50 MPa to about 450 MPa, strain at break in the range of about 50% to about 600% and substantially complete elastic recovery from nominal strains of at least about 30%. The extrudate has phase-separated microdomains that are macroscopically aligned in parallel, perpendicular, transverse or a combination thereof. Also described herein is a process for producing a polymeric extrudate for use as a dilatation balloon. The process comprises extruding a multiblock copolymer mixture or composition to form an extrudate. The extruding is done such that the extrudate has phase-separated microdomains that are macroscopically aligned in parallel, perpendicular, transverse or a combination thereof. After extrusion, the process optionally comprises the steps of drawing and coagulating the extrudate.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] The present application claims the benefit of U.S. Provisional Patent Application No. 60 / 495,711, filed Aug. 18, 2003, which is incorporated herein in its entirety for all purposes.BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to the field of balloon dilatation. Specifically, the present invention relates to balloons for dilatation applications and a process for manufacturing the balloons. [0004] 2. Related Art [0005] Surgical procedures employing balloons and medical devices incorporating those balloons (i.e. balloon catheters) are becoming more common and routine. These procedures, such as angioplasty procedures, are conducted when it becomes necessary to expand or open narrow or obstructed openings in blood vessels and other passageways in the body to increase the flow through the obstructed areas. For example, in the technique of Percutaneous Transluminal Coronary Angioplasty (PTCA...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): A61L29/04A61L29/00A61M25/00B29C47/00B29C55/04B29C55/12B29C71/00B65D1/00
CPCA61L29/04A61L29/049Y10T428/1352C08L53/00
Inventor VARMA, ASHISHCHAFFIN, KIMBERLY A.
Owner MEDTRONIC VASCULAR INC
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