DE2461370A1 - POROESE VASCULAR PROSTHESIS - Google Patents

Description

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L.R. Sauvage and J.F. Sturgeon

Porous yascular prosthesis.

The invention relates to a porous vascular prosthesis that completely and can heal quickly into the human body. In particular, this prosthesis is intended to replace arteries in the serve human body. The prosthesis according to the invention has a structure such that it can quickly attach to the tissue around the implant, so that cells grow quickly can, and that rapid formation of the inner surface can take place, originally from clotted blood exists, with the fibrous layer being covered with an endothelium in the completely ingrown state.

Numerous deaths are due to the fact that 'the current of arterial blood to distant tissues will. Bypass prostheses can promote blood flow to the more distant tissues and therefore clinical There is a need for particularly good arterial prostheses. It is estimated that there are over 1/2 million deaths annually in the United States of America, which caused

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are gentle due to decreased blood flow in the coronary arteries, and that more than half of such arteries could be replaced by prostheses.

An arterial prosthesis is made of a material that is foreign to the body's biological system. With the label "To heal" is used here to describe a biological process that naturally takes place in the body, whatever the prosthesis of an ingrown fibrous tissue is surrounded, so that the The prosthesis is completely encapsulated by the body tissue. Complete healing is the optimal condition for a prosthesis in the final healed state. This condition is characterized by the presence of ingrown fibrous Tissues on the inner and outer walls of the prosthesis in contiguous layers, with an endothelium covering the whole inner surface coated. The inner surface that is in contact with the in an optimally healed vascular prosthesis Blood is an endothelial coating, not a fibrous one coating. Apparently the blood flowing past on this surface only clots normally when this inner surface is completely consists of an endothelium »The critical important protection of the vascular prosthesis against a sudden thrombotic Inclusion or occlusion is therefore only achieved with complete healing "

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The incomplete healing of porous arterial prostheses makes it necessary to consider various circumstances. Originally, the wall of a porous arterial prosthesis is usually provided with clotted blood in order to make the wall impermeable to blood. In this method, a thrombus is generated in the open areas or interspaces or in the fiber strands and the like, as a result of which these openings are closed. The inner surface of such a prosthesis is ^v originally very thrombogenic in this state. In the case of incomplete healing, the inner surface remains thrombogenic as such, so that thrombic growths and inclusions can arise when blood flows slowly through it. It is also always possible that a thrombus is released from an incompletely healed arterial prosthesis and can lead to an infarction in distant locations.

Experiments have already been carried out on animals to heal of implanted arterial prostheses. For example, in the magazine "Annals of Surgery" Vol * 135 » Page 332 (1952) and Vol * 142, pages 624-632 (1955) attempts Dogs described. It was found that a permeable wall of a tissue made of Vinyon "N" an arterial The prosthesis contained pibroblasts and capillaries that had penetrated the prosthesis. These formed a line that was finally lined

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with a flattened cellular layer that is indistinguishable was from an endothelial lining of an artery. It is known, however, that a person cannot heal takes place as quickly as with a dog. Although healing in the human body is a natural process, it has been but found that the known arterial prostheses seldom heal completely in the human body * Taking into account From the results of the above-mentioned experiments on dogs, it was assumed that the penetration of fibroblasts in the human body did not happen to the inner circumference of the prosthesis. if the prostheses of that time were used,

Subsequent studies on prostheses with different structures that were implanted in the human body could not provide any information as to whether an arterial prosthesis heals in the same way in the human body as in the body of a dog. According to the magazine "Archives of Surchery", ¹ vol. 89, pages 757-782

themselves
(Nov. 1964) can / form an endothelium in the human body if the prosthesis consists of a usually knotted, smooth, non-velor-shaped dacron. According to the magazine "Annals of Surchery" Vol. 16I, pages 73-82 (Jan. 1965), complete healing of the inner wall in such prostheses rarely takes place.

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The magazine "Annals of Surchery" Vol. 175, No. 1, Pages " 118-127 (Jan. 1972) reports that twenty-three arterial Prostheses with six different structures in the human body were never completely healed into the tissue, and that the inner wall was not completely healed either, with the exception of the first 10 mm from the suture from where the Pannus had grown onto the surface.

and other reports indicate that the structures the previous arterial prostheses only allowed incomplete or ineffective healing in the human body. The critical question remains whether arterial prostheses heal in the same way in the human body can, as in dogs, and which structures of such arterial prostheses are important for complete healing in the promote human body.

Reference has also been made to earlier work on the Healing of non-vascular prostheses. Investigations. ·, The Interface between non-vascular prostheses and living tissue, described in the journal "J, Biomedical Materials Research Symposium "Vol. I, pp. 169-178 (1971). There is the use of a velor made of rayon, nylon 66 or dacron on impermeable layers of polyvinylchloride, SiIastic or polyurethane for the walls of the intestines, for the skin

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and described for the urinary bladder. Allegedly, adhesion of the prosthesis to the living tissue is achieved by a layer of fine fibers into which pibroblasts can immigrate. Through this a uniform layer of intertwined collagen fibers and fibers made of plastic is created. It was claimed that this process succeeds in achieving a permanent bond between the inert material and the living tissue. It 1st also known that non-porous elements, such as cages and seated Rings, on prostheses of the aortic valves, which with a Vev

lour were coated with Dacron, the formation of thrombi and systemic embolism was reduced. Although these prostheses are not porous and therefore no conclusion can be drawn that porous arterial prostheses have completely healed, later observations have confirmed these conclusions, e.g. according to the journal "Surgery", Vol. 70, No. 6, pages 9 ^ o ~ 953 · Accordingly, the adherence of the exterior of an arterial prosthesis to living tissues contributes significantly to the healing process. References to the improved healing of arterial prostheses with new structures are given by L ₉ R. Sauvage et al. has been given, describing the behavior of porous arterial prostheses with an outer surface made of velor. According to the magazine "Surgery" vol. 70, no. 6, pages 9 * io-953 (December 1971) it was known that such a structure improves the healing of the inner wall of arterial prostheses *. That was noticed on one

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aortofemoral bypass prosthesis in a human body after 182 days «Later, unpublished experiments have shown that when replacing a femoral artery with an auxillary artery with a diameter of 8 mm complete healing after a residence of 21 months in the human body with the formation of an endothelial surface only discontinuously and in speckled form on those more distant from the suture Bodies had taken place «These attempts seem to confirm that the healing of porous arterial prostheses in the human body depends on the migration of the surrounding cells, e.g. the pibroblasts, through the walls of the prosthesis.

In the journal "Surgery", Vol. 72, No. 6, pages 888-896 (Dec. 1972) is the healing of open three-dimensional microporous Mesh made of polyurethane as lining of the inner surface of sewn together knotted prostheses made of Dacron described in the bodies of dogs »with prostheses of this kind Diameters of 8 and 11 mm healed faster and more completely in dogs one as a prosthesis made of knotted dacron with a surface made of velor only on the inside.

M. E. DeBakey, M.D. has reported on the behavior of arterial Prostheses with a wall made of knotted dacron with an inner surface made of velor. However, it is not known whether

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In these attempts a complete healing of the entire inner surface has been established pointed out that complete healing of arterial prostheses in the human body is the result of penetration from surrounding cells into the wall of the prosthesis, e.g. the penetration of fibroblasts. The previously known prostheses but did not have such a structure as to permit rapid and complete healing of the entire inner surface of the arterial Prosthesis in the human body made possible. So there remain the difficulties of incomplete healing, ζ «Β. when replacing arteries with a small diameter, e.g. Coronary arteries, and certain well-known ... prostheses have limited benefits. Also the well-known arterial prostheses medium and larger diameters, which generally remain open longer, tend to have thrombotic inclusions to build*

Attempts to manufacture ideal arterial prostheses minor and larger diameter have shown that the cells migrate on the fibers, and that the rapid and complete Incorporation of the entire inner surface of an arterial prosthesis in the human body depends on fibers going outwards protrude against the surrounding cells that these fibers surface must form for the cells to migrate through the wall of the prosthesis, and that fibers also develop inwards.

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have to stretch. With these findings in mind, the arterial prostheses of the present invention are fibrous Structure «They contain an outer wall surface with relatively long, tightly juxtaposed fibers, which facilitate the connection with the surrounding tissue and the cells from the surrounding tissue lead to the main fibers, which are the essential component of the relatively thin Wall of the prosthesis. On the inner surface of the wall shorter, closely spaced pasers are provided, which a thin, originally consisting of a thrombus Anchoring a layer that is made before application to make the prosthesis impermeable to blood, and which is a proportionate one promote rapid and complete healing of the inner surface by forming a large number of pathways for cell ingrowth into the thrombic layer.

The presence of such fibers on the inner and outer surface of the prosthesis and the relatively thin wall enable the critical period of time during which the inner wall is thrombogenic to be shortened. This also shortens the period of time during which the prosthesis can be occluded by a thrombus when the flow velocity of the blood through the prosthesis is slow. «The inside and outside provided passages as part of the thin wall also reduce the dimensions of the spaces between the

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separate fibers so that the porosity is reduced, no blood can pass through the wall and at the same time the wall change is accelerated by fibrous cells as these fibrous cells move continuously from the external tissues into the thrombic layer.

Object of the invention is a new and improved vascular Prosthesis "Another object of the invention is a porous arterial prosthesis with such a structure of the wall, that a faster and more complete healing of the entire inner surface takes place, and that with it the danger of a thrombotic closure after implantation of the prosthesis in the human body only exists for a short period of time.

Another object of the invention is a porous, thin-walled arterial prosthesis with an internal fibrous surface which anchored to the thrombus and with a fibrous main wall and external surfaces that facilitate migration of the surrounding Accelerate cells through the wall so that the thrombus can be replaced and a relatively quick complete one Healing of the surface on which the blood flows is reached *

Yet another object of the invention is a thin-walled, tubular arterial prosthesis made of knotted specific material,

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so that long, closely spaced fibrous There are loops that extend against the surrounding tissue, and relatively short, closely spaced apart arranged fibrous loops that protrude into the bloodstream »This causes the migration of the surrounding Cells are conveyed through the wall of the prosthesis and it is time to remodel the original thrombic inner surface shortened and a fibrous layer which is completely covered with an endothelium is "formed"

These and other objects are achieved according to the invention by a porous vascular prosthesis that is initially in use Contains clotted blood in the interstices, so that the prosthesis for an interim period after implantation is impermeable »The prosthesis can take the form of a thin knotted wall have with spaced apart, relatively long, outwardly protruding loops to promote the migration of the surrounding cells through the wall and to shorten the time it takes to connect the prosthesis to the surrounding tissue * The knotted wall also has relatively short loops which are arranged at short distances from one another and which protrude inwards and the thrombus anchor against removal by the flowing blood. The inner and outer loops and tissue guide the cells

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through the wall to the thrombus and accelerate a relatively rapid transformation of the same with formation a fibrous layer that is completely covered with an endothelium.

For example, the figures show some embodiments the invention.

It shows:

1 is a schematic perspective view on an enlarged scale of a porous, tubular vascular Prosthesis with fibers that extend outward and with fibers that extend inward;

Fig. 2a is a plan view of a small part of the surface of a prosthesis according to Fig. 1 and shows a pattern of the knotted Backing with outer and inner fibers in the form of loops;

Figure 2b is a side view of the prosthesis of Figure 2a showing the outer loops extending outward and the shorter, inwardly protruding loops;

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Fig. 3 from the front, the pattern of Fig. 2a and the outer and the inner loops;

FIGS. 4a to ¹ Ie in side view of a wall according to the invention the prosthesis in the timing of the Einheilens, Fig. 4a shows the prosthesis in the freshly prepared state.

Fig. 4b shows the prosthesis with the thrombus in the spaces between the neighboring lasers so that it is impermeable to blood.

Fig. 4c shows the first phase of healing, with the cells from the surrounding tissue having started along to wander the outer fiber loops against the actual wall.

Fig. 4d shows a later phase of healing, wherein the cells from the surrounding tissues have migrated along the fibers to the inner fibers and have begun replace the thrombus with a fibrous layer of tissue.

Fig. 4e shows a completely healed prosthesis, in which the thrombus is completely replaced by a fibrous tissue and with the entire layer of the fibrous tissue is covered with an endothelium; and

- • j-

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Pig. 5a and 5b on an enlarged scale plan views of parts of the prior art external surface of vascular prostheses.

Fig. 5c is a corresponding plan view of an inventive vascular prosthesis and shows the considerably smaller spaces between the pasers of the latter compared to those in prior art prostheses.

Fig. 1 shows a section of a pcrous, tubular vascular prosthesis 10 according to the invention. The prosthesis 10 has a large number of uniformly and juxtaposed fibers 11 extending outwardly from the Main fabric 13, a large number of evenly arranged and closely spaced fibers 14 extends from the main fabric 13 inwards into the cavity 15 of the Prosthesis 10. The fibers 11, 13 and 14 form a relatively thin wall 12 with fibrous inner and outer surfaces.

In relation to the inwardly protruding fibers 14 are the outer Fibers 11 so long that they extend outwards to the surrounding tissue 1.6 extend, as FIG. 4c shows. The length of these outer fibers 11 accelerates the connection of the fabric 16

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with the prosthesis 10 and anchors it in the receiving body. Further, the outer fibers (Fig. ¹ Ic ¹ Ie) 11 form surfaces to which the surrounding cells 17, such as fibroblasts, from the surrounding tissue 16 to the inner fibers may lh migrate along the filaments 13. The shortness of the inner fibers I ¹ I in combination with the length of the outer fibers 11 and the main body 13 ensure such a structure that the wall 12 is relatively thin and relatively many narrow spaces 18 (Fig. 5c) between a large number of fibers has on. If, therefore, the prosthesis contains "like blood" before implantation, only a relatively small amount of a thrombus 19 (FIG. ¹ Jb) is required to make the spaces 18 of the prosthesis 10 impermeable to blood. Furthermore, since the wall 12 is thin , so the thickness of the entire layer of the thrombus in the spaces 18 and between the fibers 11, 13 and 14 is very small. The short inner fibers I ¹ I anchor the thrombus 19 and accelerate a rapid and complete healing of the inner surface 22 ( Fig. ¹ Ic) of the prosthesis, since they offer a larger number of paths for guiding the cells 17 from the environment through the fibers 13 to the thrombus 19 of the inner spaces 18. The migrating cells 17 replace the thrombus 19 in the spaces 18 by a fibrous tissue Since there is only a small amount of the thrombus 19 on the inner side of the wall, because the spaces 18 are only small and the wall 12 is only thin, so w earth

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24 6 7 370

-Ib-

a faster complete healing achieved because original only a small amount of the thrombus 19 is present. After complete healing, the inner surface 22 is complete covered by an endothelial layer 23 (Pig. ^ e). The combination of the inner and outer pasers 11 and I ^ with the Main fabric 13 shortens the critical period of time during which the inner surface 22 is thrombogenic, thus also reducing the amount of time during which the prosthesis / prosthesis is thrombotic closed can be when the flow rate of blood through the interior 15 in the direction of the arrow after Pig. ^ e decreased will.

A preferred embodiment 30 of the prosthesis IO according to the invention is porous and tubular. It is shown on an enlarged scale in FIGS. 2a, 2b and 3 and shows the way in which the knotting can take place. The prosthesis 30 has a wall 32 with a main fabric 33. Loops 33a "which extend outwards and form the outer circumference of the tubes according to Pig" .1 are connected. The outer surface of the main fabric 32 is formed by the loops 33a and numerous outer fibers or loops 31, which are arranged evenly at a close distance from one another and protrude over the wall 32 for a distance 3 * 1 (FIG. 3) »This distance J> k is approximately equal to the thickness of the wall part 32 from the knotted loops 33a.

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The inner surface of the wall 32 has loops 33a. Numerous inner fibers or loops 37 at regular and close intervals protrude from one another in the interior 15 over a distance 38 (Pig. 3) in front of which is substantially shorter than the length 3 ¹ I of the outer loops 31 or the thickness 38 of the wall 32.

ir

According to FIGS. 2a, 2b and 3, the prosthesis 30 in the preferred embodiment outer loops 31 on with a Length 3 ^ of about 150 microns, inner loops 37 of length 38 of about 50 microns and a thickness 36 of about 150 to 200 Microns so that the total wall thickness of wall 32 is less than 500 microns. The diameter of the main fabric 33 becomes like this chosen that the prosthesis 30 has a sufficient number of knotted loops 33a and therefore only in an amount of water

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less than about 2500 cm / min. per cm at a pressure of 120 mm Hg. The diameter 15 of the prosthesis 30 is dependent on the artery it is supposed to replace and can be between about 3 now for coronary arteries up to about 35 mm for the aorta of the thorax be.

According to FIGS. 1 and 2a, the prosthesis 30 has about half as much outer loops 31 like inner loops 37. For example, in prostheses with a very small diameter, the Cells 17 of the surrounding tissue 16 more easily to the loops 33ct

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hike. The prosthesis 30 can also have a different ratio of Number of outer loops 31 to the number of inner loops 37, if only it is ensured that the migration of the cells 17 from the surrounding tissue 16 against the interior 15 can take place relatively quickly, so that the prosthesis 30 is anchored relatively quickly in the surrounding tissue.

The wall 32 of the prosthesis 30 can consist of a velor fabric with the loops 33a, the outer loops 31 and the inner loops 37 · In particular, such a velor fabric characterized in that the loops 33a extend in the direction of the longitudinal axis of the prosthesis, and that the inner and outer Grind 37 and 31 at angles up to 90 ° to the plane of the wall 32 stick out.

¹ to ¹ show that a prosthesis according to the invention according to FIGS. 2a, 2b and 3 heals quickly and optimally. It can be seen that the fibrous tissue grows into the inner and outer surfaces of the wall 32 of the prosthesis 30, with an endothelial layer 23 completely covering the entire inner surface 22. It should be noted that the dimensions 3 ^, 36 and 38 are not in are shown in the same relationship as shown above "

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The Pig. Ma shows the wall 32 of the prosthesis 30, which consists of the

Main fabric 33 consists, which the inner loops 37 and the

outer 'loops 31 carries. The prosthesis 30 is porous opposite

Blood, as it has spaces 18 between fibers 31, 33a and 37. ·

Prior to implantation of the prosthesis 30 in the human body, the prosthesis is provided with coagulated Blufc, as shown in FIG. ^L \ b it shows. A thrombus 19 is formed in each space 1-8 and along the inner and outer surfaces of the wall 32. The closure of the spaces 18 by the thrombus prevents the blood from passing through the wall 32 after implantation.

Fig. I | c shows the prosthesis 30 in an early stage of healing after implantation. As long as the thrombus 19 is not replaced by fibrous tissue during healing and as long as the inner surface 22 is not yet covered by an endothelial layer 23, the prosthesis 30 is thrombogenic. The structure of the prosthesis 30 enables a relatively rapid healing because the migration of the surrounding cells 17 along the outer loops 31 can take place quickly. The length 3 ¹ J (Fig. 3) of the outer loops 31 promotes the migration of the cells 17 along the. Loops 31 to the main fabric 33 and offers

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a continuous fibrous path to the inner loops 37 " The ingrowing cells 17 anchor the prosthesis in the surrounding Tissue and promote further migration of the cells 17 into the wall 32 »

Healing is continued according to FIG. 4. The surrounding tissue 16 becomes more closely connected with the outer loops 31, and a larger number of cells 17 migrate to the inner fibers 37. The relatively thin wall 32 and the small quantity and small size The cells 17 continue to replace the thrombus 19 on the inner surface 22 and in the spaces 18 in the wall 32 of the prosthesis 30 bis, as shown in FIG. hey it shows in the final stage of the thrombus Einheilens 19 more located in or on the prosthesis 30th The final stage of healing is characterized by the formation of an endothelial layer 23 on the inner surface 22, as a result of which the prosthesis has not become thrombogenic.

The prosthesis 30 may be made by knotting, for example, on a typical, not shown machine for tying jersey. In this case, a flat fabric with the desired axial length of the prostheses 30 can first be knotted with a width such that when the sides of the fabric are connected

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by means of the seam 21 (Pig. 1) a tube according to FIG. 1 with the desired Diameter is made. The seam 21 can be made by sewing the sides together in a conventional manner

Sewing machine. '> ■ -

The tricot knotting machine can use a thread 33 with a

Polyester fiber diameter from 8 to 15 microns from Dacron / process. In the As a rule, a four-thread yarn is used, although FIGS. 2a and 2b only show a three-thread yarn 33. The knotting machine is operated so that the outer loops 31 and the inner loops 37 are formed between the loops 33a, for example 20 to 35 outer loops per centimeter and 18 to inner loops per centimeter can be formed. How nice That is, the diameter of the yarn and its density should be so selected for a prosthesis 30 of a given diameter be that under a pressure of 120 mm Hg no more than about

3 2

2500 cm / min. step through each cm of the wall.

After the prosthesis 30 has been knotted and sewn together, it can be in can usually be processed further, e.g. in the axial direction be compressed or processed in the heat so that unimaged transverse waves arise.

Porous arterial prostheses according to the invention were made from a rectangular piece of velor knotted from dacron

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and had the following properties:

Total wall thickness 12 1500 microns

Length (3 ¹ J) of outer loops 33a 430 "Length (38) of inner loops 430"

Porosity against water 4200-5200 cnr per cm

per minute at 120 mm Hg *

D: arch knife of thread 33 10-12 microns

inner diameter 6 mm

Number of outer and inner 20-35 / cm

Loops towards the

Wales

Number of inner and outer

Loops towards the

Course 18-33 / cm

Qualitative studies with these prostheses in animals have shown a very rapid healing. Ten of these sewn together

human

Prostheses were implanted in different / patients in situations where no other reasonable prosthesis could be used. These ten dentures were used for at least 1 year implanted, seven remained open. The three prostheses that required thrombectomy are now open. While After the thrombectomy, it was found that the outer wall was well connected to the surrounding tissue. That they are not against surrounding tissue had migrated and that no fluid had accumulated along the prosthesis. The inner one Lining forming fabric was thin »

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Although the prostheses described above had thicker walls, longer loops and more porous than according to the preferred embodiment of the invention, the favorable ones show Results on patients that the structure of the prosthesis according to the invention allows optimal healing in the human body enables and accelerates; The example aims at the invention

not limit. Prostheses according to the invention can also be applied to others Art, e.g. by knotting on a tube knotting machine. Other forms of vascular prostheses can also be used can be used according to the invention.

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Claims (4)

Claims ! »J Vascular prosthesis, characterized in that it consists of at least one tubular main tissue, at least one outer tissue connected to the main tissue with outwardly protruding fibers and at least one inner tissue connected to the main tissue with inwardly protruding fibers. 2. Porous prosthesis according to claim!, Characterized characterized in that the main fabric consists of a knitted fabric, and that the outer and inner fabrics are made of consist of a velor with outwardly or inwardly protruding loops. 3 «prosthesis according to claim 1 or 2, characterized in that the outwardly protruding Pipes or loops have a length of about 150 microns that the inwardly protruding strands or loops have a length of about 50 microns, that the main tissue has a thickness of 150 to 200 microns, and that the wall of the prosthesis is less passes less than about 2500 cnr water per minute per cm. 509827/0286 4. Prosthesis according to one of claims 1 to 3, characterized characterized in that their overall wall is less than about 500 microns thick that the outer ones Pipes or loops are longer than the inner fibers or loops, and that the outer and inner fibers or loops arranged at short distances from one another. C. are net. 5 »Prosthesis according to one of claims 1 to ή, characterized marked that it is made from a flat knitted fabric consists, which is sewn together by a longitudinal seam to form a tube. 509827/0286