WO2009141715A2

WO2009141715A2 - Braided corrugated textile vascular prosthesis and process of producing same

Info

Publication number: WO2009141715A2
Application number: PCT/IB2009/005669
Authority: WO
Inventors: Raul Manuel Esteves De Sousa Fangueiro; Celso José CANCELO CARRILHO; Juliana Antoniassi Luiz; Paula Cristina Martins Pina Marques
Original assignee: Universidade Do Minho
Priority date: 2008-05-21
Filing date: 2009-05-21
Publication date: 2009-11-26
Also published as: PT104067A; PT104067B; WO2009141715A3

Abstract

The present invention relates to a braided corrugated vascular prosthesis with a textile structure consisting of at least two types of biocompatible fibres, of which one is absorbable by the human body, and to the process of producing same using conventional braiding equipment, by combining previously braided biocompatible threads so as to form strings, on a mandrel (4) and a (3), to ensure the necessary diameter and corrugation. The vascular prosthesis is homogeneously impregnated with a substance that promotes sealing. The corrugated structure confers to said prosthesis the necessary elasticity for use in blood vessels. The thus produced prosthesis re-establishes blood flow in damaged segments of a blood vessel, and is particularly useful in vascular surgery.

Description

Tit! E of Invention: VASCULAR PROSTHESIS IN TEXTILE STRUCTURE INTENDED WITH WAVES AND RESPECTIVE

PRODUCTION PROCESS

FIELD OF THE INVENTION

[1] The present invention is directed to a wavy plaited, biocompatible resin impregnated vascular structure vascular prosthesis and its production process. Said process consists in the simultaneous production of a braided structure under a mandrel and a spiral device, with fibers of distinct properties and characteristics, as long as they are biocompatible with the human organism.

[2] Thus, the present invention is applicable as a vascular prosthesis in vascular surgery, particularly in the replacement of and reinforcement of vascular vessels complementing the regenerative process of the organism.

BACKGROUND OF THE INVENTION

[3] Over the past four decades, the development and production of synthetic vascular prostheses has posed enormous challenges in the field of surgery. Over these decades vascular diseases have seen their role increase in importance, both overall and mainly at the clinical level, due to the growing number of patients. Thus, they became more effective due not only to these factors but also to the considerable advances in diagnosis and therapy. Vascular prostheses must necessarily have very specific characteristics. When vascular prostheses were introduced, little attention was paid to the physiological function of the arterial tissue that would be replaced. Thus, metal, glass and ivory tubes were produced in an attempt to replace arteries. However, these products were not successful as implants mainly due to the nature of their surface which favored the formation and growth of blood clots and the lack of malleability / flexibility. Given these limitations, new solutions have been found, namely textile structures. At present textile structures are the materials that are generally used to replace arteries. The most important features of these prostheses are related to the properties of porosity, compatibility and biodegradability. The graft should be microporous to allow stable attachment to vascular cells and stimulate their growth.

[4] WO 92/16166 - Vascular Prosthesis describes a vascular prosthesis that includes a tubular braided structure. This comprises a large number of braided layers wherein each layer includes at least one interlaced yarn extending from that layer to another layer to form a bond. The prosthesis is

CONFIRMATION COPY It consists of a large number of braided layers and may include a considerably non-absorbable first surface layer as well as highly absorbable secondary layers. Thus, the existence of multilayers and non-fully absorbable and partially absorbable material become major disadvantages. The existence of multilayers makes the prosthesis less flexible / malleable, the material of the first layer that is not totally non-absorbable will not allow its full attachment to human tissue and the subsequent layers are not fully absorbable by the human body.

[5] EP 0 612 229 - Tliree-Diniensional Braided Soft Tissue Prosthesis' refers to a soft tissue prosthesis in the form of a three-dimensional braided structure preferably made of a synthetic material, which is preferably thermoplastic. Three-dimensional braided structure is a multilayer braid, although a solid three-dimensional braided structure can also be constructed.The braid includes a large number of layers wherein at least one strand of each layer extends to an adjacent or contiguous layer to connect adjacent layers. Multilayer braiding should preferably include two to ten layers.This prosthesis has several shortcomings such as the use of monomaterial, the existence of multilayers and the absence of roughness on the outside of the prosthesis.

[6] WO 88/00813 discloses human vessel (artery and vein) replacement prostheses, a tubular textile structure, and methods of producing such prostheses. The prosthesis includes a polyester strand braid as a substrate which is compact and undulating to provide a smooth inner surface. The vascular graft also includes an external polypropylene support that wraps around the substrate by melting. The complex production process of this prosthesis and its result do not guarantee the elasticity, flexibility and malleability necessary for the intended application, being desirable to improve the fixation of the prosthesis to the organism, allowing the growth and development of vascular cells.

[7] Furthermore, this document does not refer to the use of biocompatible yarns,

absorbable and non-absorbable, in the production of the prosthesis. The present invention makes use of these wires, which being plaited prior to the production of the prosthesis, thus constituting cords, confer a greater resistance to the prosthesis.

[8] WO 94/06373 discloses a soft tissue prosthesis in the form of a three-dimensional braided structure preferably made of a synthetic material having an inner and an outer surface. This structure should preferably be made in one of three possible forms: solid three-dimensional braid, three-dimensional braid which should have at least one interlaced yarn intended to join contiguous layers or, in the form of a large number of braided layers. can be linked through fusion adhesion, sewn separately or otherwise bonded to form a three-dimensional braided prosthesis. For the development of the prostheses of the present invention mixtures of different yarns or yarns of a single type may be used. It is also possible to use bioabsorbable materials as threads in forming a part of the three-dimensional braid. The existence of multilayers and a ribbed surface make the prosthesis of said patent less flexible, malleable and less capable of adhering to human tissue.

[9] EP 0 910 310 B1 - 'Soft-Tissue Shaped Tubular Prothesis and Methas of Manufacturing' describes an implantable flat-tissue tubular prosthesis which is continuously woven to a seamless tubular product and having variations of diameter along its length. In addition, tubular sections are also formed by a gradual change in the number of selected or unselected warp yarns when the yarns are inserted during the weaving process. For the production of this prosthesis, electronic jaquard looms controlled by software are used. This process is slow, complex and not very flexible (it does not allow the use of various materials or configurations), not allowing to optimize the architecture of the prosthesis, varying the thickness where it is needed.

[10] Artery prostheses generally have several functions that can be matched to occur simultaneously, such as strengthening the external artery wall and establishing blood flow. Thus, in order to obtain maximum effectiveness in the possible functions it is necessary condition that their characteristics are as close as possible to those of the human body.

SUMMARY OF THE INVENTION

[11] The present invention has several advantages over those mentioned above. The biocompatibility of the fibers that make up the prosthesis of a textile structure will allow the artery not to conflict directly with human cells, thus preventing their rejection, as well as allowing the growth of the cells surrounding the prosthesis to be possible to fix in it, thus preventing the displacement of the prosthesis that would be harmful to the patient. The absorbability of one of the fibers reduces the amount of biomaterial in the host, thus leading to a reduction in the rejection phenomenon of a foreign body, as well as reducing the appearance of possible fibroses in human tissue. On the other hand, unabsorbed fiber will support the growth of regenerative blood vessel cells, causing them to structure in a sustained manner. In this way, it is possible to maintain the same blood pressure that is felt in the vessels to which the prosthesis is attached.

[12] The wavy shape of the mandrel + spiral assembly ensures elasticity. required for application as well as some roughness that facilitates some adhesion stability of the prosthesis, which represents a significant improvement over the state of the art.

] The wavy shape together with the fact that it is made of non-absorbable threads allows the prosthesis to be correctly fixed to the body, giving the necessary elasticity that allows the convenient movement of the blood flow and ensures that no harmful movements occur during the vascular movements.] The variation in the thickness of the prosthesis allows it to be used for several

lumen replacement or support applications such as esophagus, intestine, among others.

BRIEF DESCRIPTION OF THE FIGURES

] Fig. 1 - Schematic representation of the braiding used in the production of the braided textile prosthesis with undulations.

] Fig. 2 - Schematic representation of the regular braided structure.

] Fig. 3 - Schematic representation of braided textile vascular prosthesis with

corrugations, where the braiding of biocompatible wires (1) is made using coils (2).

] Fig. 4 - Schematic representation of the spiral shaped device (3).

] Fig. 5 - Schematic representation of the spiral device (3) and the

mandrel (4).

GENERAL DESCRIPTION OF THE INVENTION

The present invention relates to a wavy braided textile prosthesis impregnated with biocompatible resin for replacement of vascular vessels in the human body and its production process. Said process consists in the simultaneous production of a braided structure under a mandrel and a spiral device, with fibers of distinct properties and characteristics, provided that they are biocompatible with the human organism.

In general, the braided vascular prosthesis containing dimples acquires high elasticity and thus greater adaptability to the vascular vessel to which it is attached. Since the prosthesis is composed of two types of textile materials, it ensures the restoration of blood flow from an injured segment (vascular vessel), thus contributing to the patient's recovery.

] The concept of 'multifunctional structure' present in this invention, characterized by the existence of different parts in the prosthesis with different types of fibers.

(raw material), is possible due to the type of technology used to produce it.

] The combination of different types of fibers may be desired to reinforce the structure of the prosthesis after its application as a replacement for an injured arterial segment. Thus, one of the textile materials used in the construction of the prosthesis is absorbed by the body, and the permanent structure is guaranteed by this biocompatible yarn.

[24] Thus, the fibers used in the present invention are biocompatible being a

absorbable and another non-absorbable. Of the group of absorbable fibers, which includes polyglycols, polyamines, polylactic acid (PLA), polyglycol acid (PGA) collagen, alginates, among others, PLGA (poly (lactic-co-acid glycol)) is the preferred fiber. . Of the group of non-absorbable fibers, which include polytetrafluoroethylene (PTFE), polypropylene, polyesters, among others, polyester is preferred. Polyester fiber will form the permanent structure as well as supporting cell growth allowing blood vessel regeneration, while PLGA fiber will not only reduce the amount of biomaterial in the patient avoiding the rejection phenomenon but also allow for the rejection phenomenon. cell growth and proliferation of different cell types. Taking into account the above mentioned factors the preferred composition will be in the ratio of 50% PES / 50% PLGA.

[25] The production sequence of the braided prosthesis begins with the process of winding the different wires to prepare the bobbins that will feed the braider for the production of the strands that will later give rise to the braided prosthesis. In this way a homogeneous cord in terms of fiber distribution is obtained, which is an extremely important factor in ensuring the functioning of the artificial vascular vessel.

[26] The wavy braided vascular prosthesis (Figure 1), impregnated with biocompatible resin, is made from braided cords of two biocompatible raw materials (fibers) (1), one of which is also absorbable by the body.

[27] Table 1 - Characteristics of the cords used and the wavy braided vascular prosthesis

[Table 1]

[Table]

[28] The present invention features, from the production of the cords to the prosthesis, in its production process by braiding technology, a spiral-shaped device (3) and a mandrel (4) used in the moment of production of the braided prosthesis. The mandrel is pre-tensioned with a cord of the same composition so that after the thermal fixation process the corrugated braided prosthesis can be removed. Subsequently, the wavy-shaped braided prosthesis is impregnated with a biocompatible resin. In this impregnation process, the prosthesis receives the mandrel again, but without the spiral device, so that the resin can be applied outside the prosthesis. The mandrel in this case is used so that the weight of the prosthesis with the liquid resin or even so that the application process does not interfere with the mechanical properties. This operation is essential because improper application of the resin may result in a lack of homogeneity of the resin in the prosthesis, as well as filling the inner canal of the prosthesis, thus interfering with its mechanical properties and functionality.

[29] The prosthesis disclosed in the present invention is based on the concept of multifunctional structures where different types of fiber (raw material) are used in different parts of the prosthesis using the braiding technique.

[30] Braiding allows to produce structures with different geometries,

namely different braiding angles depending on the number of coils (2) used, the position of the forming ring at the braiding point and the draft speed. If the number of coils, the position of the forming ring at the braiding point and the drawing speed are properly programmed, the braid angle and thickness can be controlled. Thus, at a higher angle, corresponds to a lower speed, a higher density, and a tighter structure. with less spaces. Increasing the number of coils and keeping the speed constant increases the density of the structure. The angle of formation of the braid is extremely important because it determines some of the characteristics of the vascular prosthesis, namely its porosity.

[31] The braiding direction is flexible and can be horizontal, vertical, bottom to top or inverted.

[32] The combination of different fiber types may be intended for reinforcement of the prosthesis structure after its application as a replacement for an injured vascular vessel. Thus, one of the textile materials used in the construction of the prosthesis is absorbed by the body, and the permanent structure is guaranteed by this biocompatible yarn.

[33] In practical terms the insertion of the different types of fibers can be done

braiding reels or fiber premixing,

plaiting machine or other process used for its production.

[34] The production sequence of the wave-braided prosthesis begins with the

winding process of the different wires, to prepare the coils that will feed the braiding for the production of the strands that, later, will give rise to the braided prosthesis. This results in a homogeneous cord in terms of fiber distribution, which is an extremely important factor in ensuring the functioning of the artificial artery.

[35] The bead produced is further broken down into different coils which will

feed the braiding machine in the production of the braided prosthesis. This cord is then deposited in the braiding process over a mandrel and a spiral for the production of the wavy braided prosthesis.

[36] The braiding component of the vascular prosthesis, object of the present invention, is

It is composed of a set of strands that are distributed by the braiding equipment, usually symmetrically, thus forming a braid with half the wires giving a certain angle and the other half giving the symmetrical angle. Thus, the structure, in diamond, regular or hercules, is composed of twisted wires, with two symmetrical angles. The diamond structure has a 1 by 1 interlacing, that is, the yarn of each coil alternately passes over and under each of the wires that make up the braid. The regular structure has a 2 by 2 intertwining, that is, the yarn of each spool alternately passes over and under two strands of the braid. The Hercules structure has a 3 by 3 interlacing, that is, the wire of each coil alternately passes over and under 3 wires of the braid. The diamond structure, used in the cords, due to its degree of interlacing, presents a greater structural stability when compared to the other structures. For its part, the regular structure used in the prosthesis allows a compromise between porosity and control.

[37] The variation in the thickness of the structure is achieved by varying the number of wires or their linear mass which may vary from 50 to 330 DTex in the braid. Thus, a larger number of wires and a larger linear mass corresponds to a greater thickness.

[38] The present invention is applicable as a vascular prosthesis in vascular surgery, particularly in the replacement of and reinforcement of vascular vessels complementing the regenerative process of the organism.

DETAILED DESCRIPTION OF THE INVENTION

[39] 1. Process for production of vascular prosthesis

The production of the wavy braided vascular prosthesis according to the present invention comprises the following steps:

1.1. Wind the 3-wire polyester yarn in one spool and the PGLA (90% PGA / 10% PLA) yarn in 3 spool and so on until you reach the number needed to complete the desired composition. In this case, a 6-reel plaiting machine being loaded with 3 polyester and 3 PGLA will result in a 50% polyester and 50% PGLA lanyard.

1.2. Twist in diamond structure (Figure 2) the braided strands with 6 coils. The fed yarn will consist of 3 polyester yarns and 3 PGLA yarns (90% PGA / 10% PLA) previously coiled and described in the previous point. In practice, the 6-bobbin cord has half the polyester yarn and the other half PGLA (90% PGA / 10% PGA).

1.3. Wind the cord, made up of 50% polyester and 50% PGLA (90% PGA / 10% PLA), in the number of coils required to feed the braid, 32 in this case.

1.4. Feeding the 32-reel plaiting machine with the 50% polyester / 50% PLGA drawstring to produce a regular braided structure over a 6mm diameter mandrel and a spiral shaped device with an inner diameter of 6.09mm and the outer diameter about 8mm.

[40] The inside diameter of the structure is predefined by the diameter of the mandrel, while the outside diameter is regulated by the density of the threads.

[41] In the actual production process, the mandrel is introduced into the spiral-shaped device and positioned in the plaiting machine just prior to the start of production.

[42] The output or drawing speed is adjusted according to the ratio of gears placed on the machine constant throughout the process. This parameter can be adjusted by varying the gear ratio between the sprockets that make up the gear system. After plaiting the mandrel, it is removed from the plaiting machine.

1.5. The braided spiral and mandrel assembly is then wrapped with the cord produced at the first two points, causing the braided structure to approach the mandrel, and then using a loop at the ends of the wire for attachment to the mandrel.

1.6. Thereafter thermosetting of the assembly prepared according to the previous item in an oven at about 100 ° C for about 10 min.

1.7. The thermosetting assembly is then cooled in a chamber to a temperature of approximately 0 ° C for a period of at least 24 hours.

1.8. After the cooling period, the wire surrounding the assembly is removed and then the braided prosthesis is separated from the mandrel + spiral assembly.

1.9. To finish the production process of the wavy braided vascular prosthesis, a biodegradable and biocompatible resin is applied to chitosan with 2% concentration. Thus, the prosthesis is manually impregnated through a solution containing 2% chitosan to control the porosity of the structure.

Claims

[Claim 1] Wavy braided vascular prosthesis characterized by biocompatible yarn (1), half of which are absorbable materials by the human organism and the other half non-absorbable material, associated with braided cords constituting a tubular villous structure waveform with an impregnated biocompatible resin.

[Claim 2] Wavy braided vascular prosthesis according to the preceding claim, characterized in that the constituent material of the biocompatible yarn absorbable by the human body is selected from the group of synthetic biodegradable polymers, preferably PGLA - (poly (lactic-co)). -glycol acid)).

[Claim 3] Wavy braided vascular prosthesis according to claim 1, characterized in that the biocompatible yarn constituent material not absorbable by the human body is selected from the group of polyesters, preferably the biocompatible polyester.

[Claim 4] Curl-plated vascular prosthesis according to Claims 1 to 3, characterized in that the constituent material of the absorbable threads by the human body is PGLA and the constituent material of the non-absorbable threads is polyester.

[Claim 5] Curl-plaited vascular prosthesis according to claim 1, characterized in that the cords have a regular diamond or hercules structure, preferably diamond.

[Claim 6] Wavy braided vascular prosthesis according to Claim 1, characterized in that the tubular structure resulting from the braiding is regular, diamond or hercules, preferably regular.

[Claim 7] Prosthesis according to claim 1, characterized in that it has a diameter of between 2 and 9 mm.

[Claim 8] Curl-plaited vascular prosthesis according to claim 1, characterized in that the biocompatible resin selected from the set of biocompatible resins is preferably chitosan.

[Claim 9] Wavy plaited vascular prosthesis according to claim 1, characterized in that the biocompatible resin is 2% concentration chitosan.

Braided prosthesis according to claim 1, characterized in that the corrugated biocompatible cords have a density of four corrugations per centimeter.

Prosthesis according to claim 1, characterized in that the biocompatible beads have a thickness of 1.59 mm after thermofixing in their preferred shape, which is obtained from the number of wires and beads and their linear mass. Prosthesis production process as described in the preceding claims, characterized in that it comprises the following steps:

(i) braiding of biocompatible yarns (1), one of which is absorbable, in the composition 50% polyester / 50% PGLA in strands, produced in a braid, capable of having various forms of single strand, multi-strand, hybrid or wick, in any number and linear mass compatible with the braiding process; (ii) braiding the strands in a braid where at the braid formation site a mandrel (4) and a spiral-shaped device (3) have been placed to give the braid a wavy tubular shape; (iii) at the same time as plaiting the mandrel is wrapped with a thread of the same composition with tension applied to the assembly, and the prosthesis is removed after the thermal fixation process; (iv) heat treatment for fixing the assembly obtained by inserting the mandrel (4) into a spiral shaped device (3) and covered with a braided structure; (v) removing the cord surrounding the assembly obtained by inserting the mandrel (4) into a spiral shaped device (4) and covered with a braided structure, as well as the mandrel and spiral device; (vi) application of a biocompatible resin.

Method according to Claim 12, characterized in that the braiding of biocompatible yarns is carried out in a braiding machine having a number of 6 coils or greater.

Method according to the preceding claim, characterized in that the biocompatible yarns (1), of natural or chemical fibers, in the form of single strand, multi-stranded, hybrid, or wick, are multiple in number, of compatible linear length and mass. with the braiding process.

Process according to Claim 12, characterized in that the cord braiding shall be carried out in a braid with a number of coils (2) of not less than 16.

Process according to Claim 12, characterized in that the mandrel (4) is cylindrical in shape and made of inert material with respect to the beads, with a diameter of between 2 and 9 mm, preferably greater than 6 mm, and resistant to heat and chemical treatment. .

Method according to Claim 12, characterized in that the spiral device (4) has an internal diameter of more than 6 mm and a thickness of between 0 and 1 mm with a density of between 2 and 8 turns per centimeter, but in its thickness. preferably 4 turns per centimeter with resistance to heat and chemical treatments.

Prosthesis production process according to the

preceding claims, characterized in that the braiding direction is flexible and is horizontal, vertical, upward or downward.

Method according to Claim 12, characterized in that the heat treatment for fixing the assembly obtained by inserting the mandrel (4) into a spiral-shaped device (3) and covered with a braided structure consists of: (i) heating in a thermal machine having sufficient heat capacity for heat treatment for 10 to 30 minutes at a temperature between 100 and 140 ° C (ii) cooling in a chamber at approximately 0 ° C for a period of at least 24h.

Process according to Claim 12, characterized in that the biocompatible and biodegradable resin, preferably 2% concentration chitosan, is applied homogeneously by dipping or by applying it on the outside with a soft brush.

Use of the braided prosthesis described in claims 1 to 11, characterized in that said prostheses are applied to the

replacement of vascular vessels and their reinforcement.