Interior liner for tubes, pipes, and blood conduits

Inactive Publication Date: 2012-12-06
CAMPBELL CAREY V +4
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0008]The present invention is an interior liner for tubes, pipes and blood conduits comprising a tubular form circumferentially distensible and conformable whereby the first circumference of the interior liner (the initial circumference of the liner at zero pressure) may be distended by the application of pressure causing the first circumference to be increased to a larger circumference. The qualities of being circumferentially distensible under pressure and conformable allow the interior liner to be placed into another pipe or tube and be circumferentially distended under pressure until the interior liner is smoothly conforming without gross wrinkles to the interior surface of the other pipe or tube even if that surface represents a rough, irregular, damaged or otherwise non-uniform topography. The use of a porous polymer to construct the interior liner enhances its ability to conform.
[0012]Particularly for applications relating to use as a liner for blood conduits, it is preferred that the interior liner have a second circumference beyond which it is not readily distensible and minimal recoil. For many of these applications, it may also be preferred that the liner have a wall thickness of 0.25 mm or less.

Problems solved by technology

Such grafts presently have a useful life expectancy often limited by the number of times they can be cannulated due to damage caused to the graft wall by the needles.
Repeated cannulation in the same region results in fluid leakage through the graft.
Such a liner may also inhibit tissue growth that often leads to unacceptable narrowing of the flow cross section.
These commercially available porous PTFE vascular Grafts have specific disadvantages as interior liners.
The Impra Grafts do not have such a reinforcement and so may be circumferentially distended, however, these grafts will recoil significantly on release of the distending force and therefore must be retained in place by the use of mechanical means such as balloon expandable metal stents.
The disadvantages of presently available vascular graft materials for use as intraluminal grafts are well documented.

Method used

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  • Interior liner for tubes, pipes, and blood conduits
  • Interior liner for tubes, pipes, and blood conduits
  • Interior liner for tubes, pipes, and blood conduits

Examples

Experimental program
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example 1

[0040]This example describes an interior liner of the present invention useful primarily as a liner for blood conduits. It was made to require distension by a balloon catheter, to have a second circumference and to have minimal recoil. Having helically-wrapped layers of porous PTFE film applied in opposing directions, it is described in appearance by FIG. 2. It was manufactured according to the procedure described by the flow chart of FIG. 4.

[0041]To make this particular interior liner, a 3 mm inside diameter, longitudinally extruded and expanded porous PTFE tube was obtained. This tube had a wall thickness of about 0.25 mm and a fibril length of about 25 microns. The tube was fitted coaxially onto a 3 mm diameter stainless steel mandrel as described by step 1 of FIG. 4.

[0042]Next, a length of porous PTFE film was obtained that had been cut to a width of 5.1 cm. This film had a thickness of about 0.02 mm, a density of 0.2 g / cc and a fibril length of about 70 microns. Thickness was m...

example 2

[0051]This example also appears as described by FIG. 2 and was made with the same process and materials as that of Example 1, except for the following differences. The 3 mm inside diameter, longitudinally extruded and expanded tube of 0.25 mm wall thickness described by step 1, was replaced with an otherwise identical tube having a 0.10 mm wall thickness and a 30 micron fibril length. The porous PTFE film of step 2 was of 2.5 cm width rather than the 5.1 cm width. Likewise the mandrel about which the film was helically wrapped in step 2 was of 10 mm diameter rather than 12 mm diameter. The heat treatment described by step 3 was performed at 380° C. for 11 minutes rather than 12 minutes. In step 8 the larger mandrel used was of 10 mm rather than 8 mm diameter. Finally, in step 11, only about 5 kg of force was required to tension the tube to cause it to conform to the 3.2 mm diameter mandrel. The resulting interior liner was distensible at normal human blood pressures and consequently...

example 3

[0056]An example was made which was circumferentially distensible up to a second circumference; however, process step 9 intended to better resist recoil following the release of the distending force was omitted. The physical appearance of this example is also described by FIG. 2.

[0057]This example was made from the same materials and by the same method as Example 1 with the omission of step 9 of FIG. 4. The film-covered porous PTFE tube of step 8 was removed from the 8 mm diameter mandrel per step 10, after which about 8 kg tension was applied to the ends of the tube adequate to cause the tube to assume the 3.2 mm diameter of the mandrel according to step 11.

[0058]An interior liner made according to this description was subjected to heat sterilization in an air convection oven at about 145° C. for 15 minutes. Steam was not used. The inside diameter was determined to be 3.7 mm using a tapered, smooth-finished, graduated stainless steel mandrel.

[0059]Percentage recoil for the heat ste...

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Abstract

A tube which circumferentially distends from its initial circumference upon the application of a circumferentially distending force such as applied by an internal pressure, and which exhibits minimal recoil following the removal of the circumferentially distending force. The tube preferably has a second circumference larger than the initial circumference which remains substantially unchanged by further increasing force once it has been achieved. Because of the distensible circumference and minimal recoil of the tube, the tube is useful as a liner for pipes and vessels and particularly for pipes and vessels having irregular internal surfaces to which the tube can smoothly conform. The tube is preferably made from porous PTFE with thin walls, in which form it is particularly useful as a liner for both living and prosthetic blood vessels and to line anastomoses between living and prosthetic blood vessels.

Description

RELATED APPLICATIONS[0001]The present application is a Continuation of copending U.S. patent application Ser. No. 08 / 499,423 filed Jul. 7, 1995.FIELD OF INVENTION[0002]This invention relates to the field of interior liners for pipes and tubes and particularly to liners for blood conduits.BACKGROUND OF THE INVENTION[0003]There exists a need for a liner to provide a new interior surface lining for pipes and tubes in various applications. A liner having a smaller circumference than the inner circumference of the tube or pipe intended to be lined could be easily located axially within that pipe or tube. If such a liner were circumferentially distensible by the application of an internal pressure it could be expected to conform to the topography of the inner surface of the pipe or tube during use even if that surface were rough and irregular. Alternatively, an inflatable balloon could be used to circumferentially distend the liner to cause it to conform to the interior surfaces of the tu...

Claims

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Application Information

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IPC IPC(8): A61F2/82A61F2/06A61B17/12A61F2/00A61F2/92B29C48/00B29C48/07B29C48/09B29C48/15B29C48/21B29C53/58B29C55/24B29C63/34F16L11/12
CPCA61B17/12022A61F2220/0075A61B17/12118A61F2/07A61F2/92A61F2002/30289A61F2230/0091B29C47/00B29C47/0019B29C47/0023B29C47/0042B29C47/02B29C53/58B29C55/24B29C63/34B29K2027/18B29K2105/04B29K2995/0072B29L2023/007F16L11/12A61F2/90A61F2002/075B29C47/0064B29C47/065A61F2210/0076A61F2220/0008A61B17/12109B29C48/15B29C48/00B29C48/07B29C48/09B29C48/0012B29C48/0021B29C48/21
InventorCAMPBELL, CAREY V.LAGUNA, ALVARO J.LEWIS, JAMES D.MAYRAND, MARK E.MYERS, DAVID J.
OwnerCAMPBELL CAREY V