CA1325081C - Vascular graft - Google Patents

Abstract

Abstract A vascular tubular graft of a woven fabric with a single velour outside (external) surface and a smooth interior surface, said outside surface having a plurality of loops, each loop extending around a portion of the circumference thereof and each loop formed by fill yarn positioned about warp yarns.

Description

1325081 i `

Background of_the_Disclosure This invention i5 directed to vaseular grafts of synthetic fibers. Vascular grafts (prothesis) are currently used to replace certain diseased arteries by Joining e~g., by sewing the ends of the vascular tubular grafts to the remaining portions of the artery e.g~, human artery. Operations for this purpose are commonly done by surgeons who first remove the diseased portion of the artery, e~g., blocked by a clot, and the~ implant the graft in its place. Qlternatively, the graft may be used as a bypass around a deseased vessel. Such grafts usually are used -in connecti4n with arteries which carry large blood volum~s e.g., located in the iower body of the human, although it may be used in other part~ of the human body. Grafts which are presently in use ~re of a woven or knitted construction~
Knitted construction grafts tend to be of high porosity and thus bleeding often accornpanies their use. While woven grafts are in wide use, there is still a need for a new and improved woven graft that because of its weave construction is of low porosity, is smooth on the interior of the graft to prevent obstruction thereof by various material carried by the blood in the graft, -and provides a staggered design outer looped surface extendin~
radially around the circumference thereof to allow for the body tissue which grows thereabout after implantation to firMly support it in the body. The graft is also preferably crimped 50 that it will not kink easily during implantation.
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1 325~8 3 Prior Work in the Field The following U.S. Patents may be referred to which show the state of the art: 4,517,687; 4,047,252;
4,501,263; 4,164,045; 4,229,838; 3,316,557; 3,945,052;
~,190,909; 4,304,010; 2,127,903; 4,313,231; 4,208,745;
4,530;113; 4,193,137; 3,254,651; 3,47~,670 and 4,306,318. Patents relating to plastics which may be o interest include 4,250,138 and 4,321,914.
Reference may also be had to the following articles:
"A New woven Double Velour Vascular Prosthesis", Stewart Scott et al, J. Cardiovasc., Surg. 26, 1985 and "Aorto-iliac Reconstruction with Dacron Double Velour", S.M. Lindenauer et al, J. Cardiovasc., Surg., 25, 1984, which also shows the state of the art and the utility of vascular grafts.
Brie Descri~tion of the Disclosure .
The invention is directed to a woven velour synthetic tubular graft (straight or bifurcated) preferably of polyester such as polyethylene terephthalate having a velour structure as its outer surface.
In accordance with one aspect of the invention there is provided a vascular graf~ comprising a seamless tube of crimped woven texturized yarn ~abric, said tube having a complete outer velour surface and a smooth inner surface, said outer velour surface having loops open to receive tissue ingrowth formed of fill ~-yarn, each of said loops extending outside of a plurality of warp yarns. `
In accordance with another aspect of the invention there is provided a hollow tubular graft comprising a single outer woven complete velour fabric fro~. warp yarns and fill yarn, said warp yarns A

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supporting a plurality of first fill yarn portions, said first fill yarn portions being positioned outside of warp yarns to form only outer circumferential loops exclusive of inner circumferential loops with the loops each extending outside of 4 to 8 warp yarns and the adjacent second fill yarn portions woven so they are offset from one another at least one warp yarn, so that adjacent loops along the length of the tubular graft are out of alignment, said loops being substantially transverse to the longitudinal axis of the tube.
In accordance with yet another aspect of the invention there is provided a vascular tubular graft of woven synthetic fibers with a complete velour external surface having a plurality of loops, each loop extending around a portion of the circumference of the graft and each loop formed by fill yarn positioned externally of warp yarns, said loops being substantially transverse of a longitudinal axis of the tubular graft and the warp yarns are in substantially the same direction as the longitudinal axis of the tubular graft.
The grafts are particularly useful in the repair of an artery.
The inner surface of the tubular graft is typically a smooth or plain weave surface.
The velour structure at the outer surface is provided by the fill yarn rather than the warp yarns.
The differentiation between the inner surface (plain weave) and the outer velour surface is accomplished by having the filling yarn interlacing with the warp yarns at different patterns preferably every other pick. For example, if the weaving started with a plain weave, the next ~. .
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,: t interlacing pick is a velour-generating pic~, which extends over a predetermined number of warp ends before interfacing with a single end of warp. The yarn used i5 preferably of polyester and the especially preferred yarn used are rnade by Dupont under the Tradernark D~CRON. Type 56 Dacron yarn is the most preferred for both the fill and warp yarns, howev0r~ comparabl~ yarns and fibers may be used as will be apparent to those s~illed in the art. The yarn rnay be used as textured or untexturi~ed with texturized being preferred. The purposes o~ the outer velour i~
to provide a base for rapid internal human body tissue growt~
about the velour circumfer~ntial loops thus securing the position of the graft and the smooth inner surface is provided to prevent formations of obstructions on the interior wall o~
the graft. In addition, because the velour i5 in the fill position, the proces~ to form radial crimping of the graft will not affect the structure of the velour and will not cau~e the velour loop to fold or Qlongate and thus weaken the graft. In this invention the warp yarn~ run lengthwise in the tuhular graft and are cros~ed by the fill yarn~ The fabric of this invention is tightly woven and of low porosity in order to prevent bleeding through the graft after implantation.
Th~ graft may be a strai~ht tubular shape for connection to a single artery to replace a diseased section, ~r for replacing a three arrn connection i.e., connection to three arteries, the graft may be made in bifurcated forrn~

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~ efore irnplanta~ion, the gra~t is preclotted with the patients blood to make it impervious to bleeding. ~ecause the graft has a srnooth inner surface, it will not pick up excessive clotting material from the blood whi~h i5 likely to be a precursor to an obstructed graft after implantation. ~lso, with the s~ooth inner surface the possibility of a clot forMing in the graft and being r-leased in the blood stream i5 decreased.

~ ee5SrlDtic~n_of_~he_E~rawingg ¦ Fi~. 1 ls a top pl-n vl-w of the woven ~abrlc a~ u--d In accordance with the present invention to show th~ velour outer surface pattern;
Fig. 2 is a sect~onal v~ew taken along line 2-2 of Fig. 1;
Fig. 3 is a tube made of the fabric of Fig. l;
Fig. 4 is view showing the first step in forming circumferential crimp in the fabric tube of Fig. 3;
Fio- 5 i5i ViQW howing th~ second ~tep in forming the crimp in the fabric tube of Fig. 3;
Fig. 6 is view showing thr~ third step in forrning the crimp o~ the tube of Fig. 33 Fig. 7 shows the finished woven external velour graft in traight (tube) forrn of the invention;
Fig. 8 is a section taken along line 7-7 in Fig. 7 in order to ~how t orimp in the outer wal l;

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' ' ' 1325081','' Fig. g i5 a view showing the graft sewn to repair an artery;
and Fig. 10 i5 a view showing the graft of this invention in a bifurcated form.
. ., . ..' De-a~leg-Dessr~t~-o-n-of-t--e-Di~closu-r-Reference should now be made to Figs. 1, ~ and 3 which show the fabric of th~ inv-ntion (Fig. 1) whieh is formed into a tube 21 for use as a graft. In Fig. 1 the warp yarns are shown at Z0-1 and the fill yarn i5 shown having portions Z0-2 and 20-3.
Fill yarn portion Z0-Z is shown in a plain weave pattern with the fill yarn radially interlacing with the warp yarns as shown in an under and over plain weave fashion. The velour in the fabric i5 formed by interlacing of the fill yarn portion ~0-3 which forMs a velour pattern having outside radial loops Z0-4 which ~loat (extend) ov-r fivo warp yarn end- 20-1 as shown.
The next velour loop pattern formed by fill yarn portion Z0-3~ after the ne~t regular weave pattern formed by fill y~rn portion 20-~ is then ~taggered one warp yarn to form the weave pattern of Fig. 1. The weaving is continued one yarn at a time for the entire pattern to form the staggered velour loops 20-4 (see Fig. 3) which is provided around the outer circumference of the tube Z1 formed of the fabric Z0. ~s shown in Fig. 1 the loops Z0-~ preferably extend over 5 warp yarns~
however, in the practice of the invention, loops of fill yar~

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which extend over 4 to ~ warp yarns are quite aceeptable.
In order to form the tube of the invention e.g., Dacron*
brand type 56 yarn ~0 Denier~47 filament is pre~erably used for both the warp yarns and fill yarn. The yarns are preferably te~turized on a standard false'twist texturing machine~ ~fter texturizing, the yarn i5 wrapped ~wound) about one another to form frorn the 50 Denier~47 filament yarn, a 100 Denier~94 filament warp yarn with ~ turns per ineh twist. The fill yarn is sirnilarly fcrmed except it only has 1 to ~ turns per inch of twist. Thereafter the fabric of Figure 1 is woven in a conventional manner u~ing a loom as known in the art. The woven outer ~external) velour fabric Z0 is preferably formed using 160 ends per inch for warp and 130 pichs per inch in the fill position. The tube that is usually formed is about 6 to 38 m~
in diamcter deponding upon the use lntended, howevEr ~t may bc made in various lengths e.g., 90 to 20 cm.
Thereafter the woven tube su~h as shown in Figure 3 i~
washed to removQ oils and other materials using conventional washing agents e.g., a mi~ture of 3 part~ Hyponic*OPS5 agent ~Diamond Shamrock) and 1 part 8yntergist*TER-1 ~Diamond Shamrock) agent mixed with water ~temperature 165F to 180F) in the ratio of 3~ washing agents and 97% water.
During this washing the tube 21 will shrink.
~ fter washing, the woven tube ~1 is placed over a man~rel 30 as shown in Figure 4 in a tight fit. The tube is then wrapDed . 1 , . *trade mark .. .

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`: 1 325081 with a plastic mono~ilament 31 (e.g., nylon, about .015 inches diameter) about 1~ turns per inch. The wrapped tube ~1 i5 ther, placed ir, a machine ~see Figure ~) cornprising two post 5 33-1 and 33-~ holding the mandrel positioned on support 3~. The posts 33-1 and 3Z-1 are both moved as shown by the arrows to compress the tube from both ends from e.g., ~0 to 20 cm. The monofilament 31 is then removed from about the tube ~1.
Thereafter the co~pressed tube is positioned in an oven 36 on the mandrel 30 ar,d held in place by clips 35-1 and 35-~. The tube i5 heated for 30 minutes at Z50F. ~t this time~ the tube is removed from the oven, taken off the mandrel 31 and placed over a smaller diameter mandrel about 1 to 2 mm in diamcter le~s than tha ~lrst mandrel. The product ~5 then streched e-g., by hand to 40 cm in length 50 that the crimp i5 . .`
not as dense. Thereafter, the crimped tube Z1 is again placed in the oven at 2S0F for 30 minutes to forrn the final shape as shown in fig. 7.
Figs. 7 and 8 show the fi~al product aftEr crimping with the looped velo~r outer surface 2~-1 and inner smooth surface 21-Z.
In figure 9 there is shown the graft 21 sewn by surgical thread 41 to an artery 40 after the diseased artery section has been surgically removed. Fig. 10 shows the final product 50 having ~he same weave construction and crimp as the tube shown in Figs.
1 to 9 in a bifurcated form ~Y) for connection to three artery branches e.g., aorta to the left and r1ght iliac arteries. ;~

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~ s is custoMery, the graft is immersed in the blood of the p~tient to preclot it prior to use as shown in Fig. 9.
It is to be understood that other conventional m~thodology may be used to fabricate the graft as wouid be apparent to those skilled in the art.
It is also to be understood that multiple fill yarns instead of a single fill yarn may be used to weave the products of th~
invention. It is also to be understood that in addition to a single fill on a second shuttle of a loom, that multiple fill ..
yarns on a single shuttle or on multiple shuttles may be used to weave the tubeq of the invention. Tho uso of multiple yarns on .
multiple shuttling will afford the opportunity to vary tension and type of yarn from.shuttle to shuttle.
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Claims (16)

1. A vascular graft comprising a seamless tube of crimped woven texturized yarn fabric, said tube having a complete outer velour surface and a smooth inner surface, said outer velour surface having loops open to receive tissue ingrowth formed of fill yarn, each of said loops extending outside of a plurality of warp yarns.

2. The graft of claim 1, in which the fill yarn is also positioned about warp yarns in a plain pattern, said plain pattern being positioned between adjacent fill yarn forming the loops.

3. A hollow tubular graft comprising a single outer woven complete velour fabric from warp yarns and fill yarn, said warp yarns supporting a plurality of first fill yarn portions, said first fill yarn portions being positioned outside of warp yarns to form only outer circumferential loops exclusive of inner circumferential loops with the loops each extending outside of 4 to 8 warp yarns and adjacent second fill yarn portions woven so they are offset from one another at least one warp yarn, so that adjacent loops along the length of the tubular graft are out of alignment, said loops being substantially transverse to the longitudinal axis of the tube.

4. The graft according to claim 1, 2 or 3, in which the yarns are polyester.

5. The graft of claim 3, which is crimped.

6. The graft of claim 3, in which the yarns are texturized.

7. The graft of claim 3, in which the yarns are untexturized.

8. The graft of claim 5, 6 or 7, in which the yarns are polyester.

9. The graft of claim 1, 2 or 3, in which the yarns are polyethylene terephthalate.

10. A vascular tubular graft of woven synthetic fibers with a complete velour external surface and a smooth interior surface, said external surface having a plurality of loops, each loop extending around a portion of the circumference of the graft and each loop formed by fill yarn positioned externally of warp yarns, said loops being substantially transverse to a longitudinal axis of the tubular graft and the warp yarns are in substantially the same direction as the longitudinal axis of the tubular graft.

11. The graft of claim 10, in which each loop along the length of the tubular graft is offset and out of alignment with the next adjacent loop.

12. The graft of claim 1, 2, 3, 5, 6, 7, 10 or 11, which is in a straight or bifurcated form.

13. The graft of claim 10, in which the tubular graft is crimped about its circumference.

14. Use of the graft of claim 1, 2, 3, 5, 6, 7, 10, 11 or 13, in the repair of an artery.

15. Use of the graft of claim 4, in the repair of an artery.

16. Use of the graft of claim 12, in the repair of an artery.