DD160857A1 - HAEMODYNAMICALLY OPTIMIZED BIFURCATION PROTHESIS - Google Patents

Abstract

The invention serves the vascular reconstruction in the aortoileofemoralen area. It can be used as a conical tube arterial and venoes in human and veterinary medicine. The aim of the invention is to avoid some biological weaknesses of the vascular bifurcation prosthesis, such as turbulences and dead space zones, by taking account of haemodynamic laws at the aortic division. In the prosthesis, new geometric relationships such as sail formation, cross-sectional ratios and spread angle are taken into account (FIG. 1). By a two-layered structure of the prosthesis, a more optimal healing with retained elasticity is possible.

Description

Title of the Erlebadung '

Hemodynamically optimized bifurcation prosthesis

Field of application of the invention

The invention is generally used in vascular surgery for the reconstruction of the aorto-lexemoral area. It can be used in human medicine and veterinary medicine. This vessel replacement is used as a conical tube in arteries and veins.

Characteristic of the known technical solutions

Artificial blood vessel prostheses are available to the surgeon as seamless § pleated ₉ woven, knitted or knitted tubes of any size »Woven © Prostheses have a relatively low porosity and <thus a high density at implantation« The disadvantage is the lack of Neointimaverarskerung and tendency to premature degenerative changes © Knitted prostheses are characterized by a higher porosity ₈ which allows a better implantation of the prosthesis and a good anchorage of the neointima «The disadvantage is the primary blood loss during implantation, as a preclotting is required * To overcome these disadvantages were to meet _t different materials and technologies used "A new type of prosthesis, the double office or Doppelflor prosthesis from Da'cron represents · (PS 2,744,866)

In order to give the artificial vessels the rigidity, the previous forms were made wavy. "This results in the blood flow - marginal turbulences, which have an adverse effect on the neointima formation. In the previous bifurcation prostheses, the conical taper of the prosthetic limbs and the intersection behavior"

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neglected distally · This cross-sectional change was taken into account in the Cooley bifurcation prosthesis (Cooley, Di Α. - Vascular Surgery 1980) · A hemodynamic weak point is the geometry of the branching site at the aortic bifurcation · The cross-sectional index is 1: 1.2 after the branching. It can be seen that the haemodynamic concept of vascular degeneration virtually requires a tapered prosthesis.

Object of the invention

The invention includes a blood vessel prosthesis made from a biologically inert, non-textile, two-layer flexible polyurethane foam (SXSpur-derm) with predominantly open cells and compacted surface.

The large-pored outer surface absorbs the blood components, thus reducing further blood loss and forming the matrix for the sprouting connective tissue from the vascular environment. Endovasal contains the fine-pored, compacted layer. It prevents major blood losses during implantation, serves as a matrix for the neointima and prevents this Increased ingrowth of fibroblasts and capillaries The object of the invention is to eliminate some biological weak points in the implantation of vascular prostheses, which limit the unlimited clinical applicability, and to produce a haemodynamically more optimal prosthesis. By considering hemodynamic laws at the aortic bifurcation dead space zones and turbulences are to a large extent be avoided (ELg * 1 u Fig. 2). The geometric relationships of the aortic bifurcation, as found in coronary artery exudates of different age groups, were used in the "new prosthesis form." In addition to the "sail formation" (Pig. 1 - 3), the cross - sectional relationships of the vessels are also taken into account 1: 1.2 - 1.3 bz-w · -, 1: 2-3, the prosthetic limbs conical · This is

an abrupt luminal change and thus a hemodynamic inadequacy prevented «

The laminar blood flow is largely retained in this vessel construction. Thus, a haemodynamically conditioned and "controlled" homogeneous and well-nourished neointimal layer can form. Turbulence-related neointimal pillows which can not be sufficiently nourished and thus lead to degeneration and re-occlusion of the prosthesis can not Forming · The bilayer nature of the SYSpur derm (Fig. 4) allows fibroblasts and capillaries to be indwelling from the outside, which are indispensable for healing and permanent puncture of the prosthesis. * The small-pored inner layer serves as a matrix for neointima and prevents greater blood loss implantation »

With this new development, the known deficiency of previously clinically applied vascular prostheses can be eliminated _Θ

Presentation of the essence of the invention

The object of the invention is »to remedy the so-called biological weak points of the alloplastic arterial replacement.» The two-layered structure of the vascular prosthesis wall from SYSpur-derm causes rapid healing due to the large-pore structure of the outer layer (FIG. 4- _β ) _β The small-pored inner wall (FIG B) prevents major blood loss

creates good conditions due to its hemodynamic favorable nature © »to a homogeneous neointimal imageDissection and degeneration processes at the neointima are prevented by fibroblast growth and capillary sprouts due to the highly porous outer wall of the prosthesis environment. Furthermore, it is an object of the invention to provide an artificial blood vessel prosthesis. whose elastic properties can be adapted to those of natural vessels and which take into account the hemodynamic aspects of a branching of vessels. «

According to the invention, a bifurcation prosthesis has been developed, which has a sickle-shaped spur formation, as we

found bodies at the junction. Thus, disturbing turbulences in this branching area, as is the case with the o · g · bifurcated prostheses, are avoided. The two prosthesis legs extend in a short straight line parallel before they separate. The transverse ratio of (1.2 to 1.3 · The prosthesis limbs then run conically towards the periphery · Thus, abrupt, hemodynamically unfavorable, changes in the direction of the bloodstream and larger differences in the lumen are avoided · Considering hemodynamic parameters in the design of a bifurcation prosthesis, turbulences can be avoided to a great extent. The homogeneous, laminar blood flow can form a uniform, well-nourished neointima «

It is also an object of the invention to reduce the late complication rate of the vascular prostheses. The variation possibility of the elastic polyurethane foam in its stratification serves for this. Thus, the airway function of the arteries (longitudinal and radial tensioning) can be maintained and the mechanical function Reduce the stress on the joints · This elasticity of the prosthesis is retained even after ingrowth because the connective tissue and the capillaries can not grow lumen-like in a direct way due to the open-pore structure of the material. .... · ;; ^{': -';} .. ^: \; ^; _: l! _:: ^ v; -.?.

Edge turbulence, as we find it in pleated prostheses, does not occur with the new prosthesis · If the distal anastomosis beyond the inguinal ligament, an additional stiffening of the prosthesis wall is required · A particular advantage of the new vascular prosthesis is the suppleness and elasticity of the suture, In addition, this prosthesis material does not tend to frazzle on the anastomosis sutures.

embodiment

The medial abdominal incision takes place in the patient's supine position, allowing the entire aorta and pelvic

After preparation of the vessels, depending on the local findings, the aorta is severed relatively far proximal to the bifurcation _s but as far as possible after previous occlusion. · Now, the developed bifurcation prosthesis is anastomosed end-to-end with the aorta be used SlSpur-dermstreifen · distal of Verschlusstreckewird proceed in a similar manner, "a distal seam _s to aim before the inguinal ligament as otherwise required because of Okklusionsmöglichkeit an additional" vascular stiffness ". Upon implantation to pay attention to a short "Aortenstamm" _g so that the spreading angle is kept as small as possible · The crescent-shaped spur formation and short segmented leg fixation (Pige 1 u _e 2) is counteracted a large hemodynamically unfavorable spread angle · By rough, large-pored outer surface of the Vascular prosthesis ensures rapid and safe implantation of the implant. After the blood flow has been released, the prostheses will be treated for a short period of time. This will result in bleeding from the prosthesis. The small-pored inner layer will quickly become blocked as a result of coagulation.

In animal experiments, the pulse wave can be visually followed throughout the vascular prosthesis. This elasticity retains the vascular prosthesis even after ingrowth.

Claims (6)

-6- LL a IJ 4 U Entitlement to the invention 1 · The hemodynamically optimized bifurcation vascular prosthesis consists of a biologically inert, two-layered polyurethane foam (SX-lane) with predominantly open cell structure and compact inner vessel surface, characterized in that a crescent-shaped spur is formed at the splitting site and the resulting two prosthesis limbs run parallel to each other in a short-stretched manner and thus given an acute spread angle , is * ' ^: . , '. ^: ':'. '.''.''..:;,;. ·. ',: ^;: -'^:; - ' 2 * bifurcation prosthesis after -V ¹ ^ nMi 1 characterized in that the cross-sectional index of the branching after the age of 1.2-1.3 is taken into account. 3 »bifurcation vascular prosthesis according to 1 and 2, characterized in that the two vessel limbs are seamless and conical, taking into account the aortofemoral index of Ii 2 - 3» 4. bifurcation prosthesis according to T M, v \ Kt 1> 3, characterized in that by their shape turbulence can be avoided and form a homogeneous well-nourished neointima · 5 * bifurcation prosthesis according to VU-n-kt 1 - 4, characterized in that the bilayer nature of the open-pore wall, a good healing of the prosthesis is achieved, the neointima has a small pore matrix and nutritional disorders with subsequent degeneration or * re-closure are avoided · ^; 6 · bifurcated prostheses according to Tu-n ^ t 1 - 5, characterized in that the vascular material can be used arterially, venously and as patch plastic application * See 3 .. "pages drawings