WO1996019159A1

WO1996019159A1 - Artificial valve for a blood vessel

Info

Publication number: WO1996019159A1
Application number: PCT/FR1995/001669
Authority: WO
Inventors: Claude Franceschi; Amine Mohamed Marc Antoine Bahnini
Original assignee: Claude Franceschi; Bahnini Amine Mohamed Marc Ant
Priority date: 1994-12-21
Filing date: 1995-12-14
Publication date: 1996-06-27
Also published as: FR2728457A1; FR2728457B1

Abstract

An artificial valve for a vessel (100) containing blood (104) flowing in a given preferential direction (103). The valve comprises an oblong body (2) with a cross-section that may be expanded from one end (3) to the other end (4), means (5) for attaching a point (34) on the oblong body to a point (106) on the vessel wall (101) so that one end (3) is located upstream (102) in the direction of blood flow relative to the other end (4), and means for causing an increase, should a backflow of blood occur, in the value of a cross-sectional projection of the expandable end (4) of the oblong body (2) onto a plane (6) substantially perpendicular to the longitudinal axis, until said projection is substantially the same as the cross-section of the vessel. The valve may be used as a prosthetic valve in veins.

Description

ARTIFICIAL VALVE FOR BLOOD VESSEL

The present invention relates to artificial valves for blood vessels, that is to say the devices making up for the absence or congenital or acquired dysfunction of the natural valves of the vascular system, finding a particularly advantageous application in the veins but also , in special cases, in the arteries for example at the exit of the heart.

To date, the valves for defective blood vessels have only been the subject of surgical repairs or transplants and the structure of the artificial prostheses proposed allows only an implantation of these prostheses outside the vessels.

The present invention thus aims to achieve an artificial valve which can be implanted directly in the blood vessels without posing operators specific problems, which is of a simple structure and a very low cost price.

More specifically, the subject of the present invention is an artificial valve for a vessel traversed by a blood flow in a given preferential direction, characterized in that it comprises: - an oblong body having a cross section capable of being increasing between its two ends , said oblong body being located in said vessel,

first means for fixing a point of said oblong body with a first point of the interior wall of said vessel so that the end of the smallest section of said oblong body is located upstream, in the preferential direction of circulation of said blood flow, by relative to the other end capable of being of larger section, and

- Means for increasing, when the blood flow tends to flow back into said vessel, the value of the projection, along substantially the longitudinal axis of said vessel, of the section of the end of said oblong body capable of being the largest , on a plane substantially perpendicular to said longitudinal axis, until this projection is substantially equal to the cross section of said vessel.

Other characteristics and advantages of the present invention will appear during the following description given with reference to the drawings annexed by way of illustration, but in no way limiting, in which:

FIGS. 1 and 2 show two cutaway and partially perspective views of a first embodiment of an artificial valve for a blood vessel according to the invention, respectively in two possible states depending on the direction of the blood flow in the vessel, and / 19159 PC17FR95 / 01669

Figures 3 and 4 show two cutaway views and partially in perspective a second embodiment of an artificial valve for blood vessel according to the invention, respectively in two possible states depending on the direction of blood flow in the vessel. It is firstly specified that, although FIGS. 1 to 4 represent two embodiments of an artificial valve for blood vessel according to the invention, in order to simplify the description below and to facilitate its understanding , the same references will designate, in these figures, the same means or elements, whatever the form in which these means or elements have been represented.

Generally, the artificial valve according to FIGS. 1 to 4, for a blood vessel traversed by a blood flow in a given preferential direction comprises an oblong body 2 situated in the blood vessel 100 and having a cross section capable of being increasing between its two ends 3 and 4. The artificial valve further comprises first means 5 for fixing a point 34 of the oblong body 2 with a point 106 of the interior wall 101 of the vessel so that the end 3 of the oblong body 2, of smaller section, ie located upstream 102, in the preferential direction of circulation 103 of the blood flow 104, relative to the other end 4 able to be of larger section, and means for making it grow, when the blood flow 104 tends to flow back, FIGS. 2 and 4, into the vessel 100, the value of the projection, along substantially the longitudinal axis 105 of the vessel, of the section of the end 4 of the oblong body able to be the greatest s large, on a plane 6 substantially perpendicular to the longitudinal axis 105, until this projection is substantially equal to the cross section of said vessel.

Referring more particularly to FIGS. 1 and 2, these figures represent two cutaway and partially perspective views of a first embodiment of an artificial valve 1 for blood vessel 100 capable of being traversed by a blood flow 104 in a preferential meaning given 103.

According to this first embodiment, the oblong body 2 having a cross section capable of being increasing between its two ends is constituted by an envelope 21 whose general shape is that of a substantially conical horn, or similar to this shape. As for the means for making it grow, when the blood flow tends to flow back into the vessel, the value of the projection, along substantially the longitudinal axis 105 of the vessel, of the section of the end 4 of the oblong body capable of being the more large, on a plane 6 substantially perpendicular to this longitudinal axis, until this projection is substantially equal to the cross section of the vessel, they are essentially constituted by the fact that the envelope 21 is made of a relatively flexible material such as plastic or the like such as PTFE, polyurethane, etc.

In an advantageous embodiment, it is possible that the artificial valve 1 according to the embodiment illustrated in FIGS. 1 and 2 further comprises means for keeping at least two points from the interior wall of the envelope 21 so that the opening 22 of the horn, which constitutes the end 4 capable of having the largest section, is always partially open, as illustrated in FIG. 1. These means which have not been specifically illustrated can for example be constituted by elastic means such as "V" leaf springs or the like arranged inside the horn. As for the means 5 for fixing this oblong body 2 in the blood vessel 100 at a point 106 of the interior wall 101 of the vessel so that the end 3 of smallest section is located upstream 102, in the preferred direction of circulation 103 blood flow 104, relative to the other end 4 able to be of larger section, they can for example be constituted by a seam made with biocompatible and non-absorbable threads or the like, for example threads of PTFE, connecting the flexible wall of the horn with the wall of the blood vessel.

In this first embodiment according to FIGS. 1 and 2, the artificial valve 1 can advantageously include second means 7 for fixing the oblong body 2 at at least one second point 108 of the internal wall 101 of the blood vessel, not confused with the first point 106 and so that this second point 108 is located on a straight line substantially parallel to the longitudinal axis 105 of the blood vessel 100 and passing through the first point 106. The implantation of an artificial valve 1 like that illustrated in FIGS. 1 and 2 presents no difficulty for an operator and, when it is installed as shown in these two figures, it operates as follows:

When the blood flow 104 flows in the normal direction 103, the envelope 21 flattens as shown in FIG. 1. The cross section of the oblong body 2 is very small all along the body and does not obstruct the flow of blood flow. On the other hand, if, for reasons which are known to those skilled in the art, the direction of flow of the blood flow 104 tends to reverse as shown in FIG. 2, the latter rushes into the envelope through the opening 22, at the end 4 of the oblong body 2, and swells it, this swelling being essentially due to the pressure difference which then exists between the upstream and the downstream defined under the normal conditions of blood flow.

As, in the case of blood reflux, the opening 22 of the horn has a projection, substantially along the longitudinal axis 105 of the vessel, on a plane 6 substantially perpendicular to the longitudinal axis 105, substantially equal to the cross section of the vessel blood, it almost completely marries the interior wall of the vessel and the swollen envelope thus opposes the blood flow in the opposite direction to the normal direction 103.

In the example illustrated in FIG. 2, the position of the opening 22 when the envelope is inflated by a blood reflux is defined so that it is substantially perpendicular to the axis 105 of the vessel. In this case, the value of its projection as defined above is substantially equal to its real section.

For the artificial valve to obtain the desired result, the blood reflux must rush into the envelope 21 as described above. It is therefore necessary, for safety, the opening 22 of this envelope is never completely closed. The spring means defined above allow this opening to be always partially open and to open completely, or deploy, under the pressure difference between the upstream and downstream defined above, when the flow blood tends to flow in the opposite direction of the preferential direction.

The second means 7 for fixing the oblong body 2 at at least a second point 108 of the internal wall 101 of the blood vessel prevent the envelope from turning over, that is to say that its end 3, normally upstream in the correct direction of blood flow, does not pass downstream of its end 4 and does not prevent normal blood circulation.

FIGS. 3 and 4 show two cutaway and partially perspective views of a second embodiment of the artificial valve 1 for blood vessel 100 capable of being traversed by a blood flow 104 in a given preferential direction 103. In this mode of embodiment, the oblong body 2 having a section capable of being increasing between its two ends 3 and 4 is constituted by an envelope whose general shape is that of a solid horn 3 1

ant / 19159 PC17FR95 / 01669

substantially the shape of an oblique cone whose base 32 is of a section such that, when the blood flow tends to flow back into the vessel, the value of its projection, substantially along the longitudinal axis 105 of the vessel on a plane 6 substantially perpendicular to this longitudinal axis, or substantially equal to the cross section of the vessel. The oblong body 2 is fixed to the inner wall 101 of the blood vessel at a point 106 of this wall, substantially at its point 34 belonging to the base 32 and to the generator 33 of the solid horn 31 which has the shortest length.

In addition, in order to obtain the result described below, the generator 33 of the solid horn 31 which has the shortest length is advantageously greater than the diameter of the blood vessel.

In this second embodiment of the artificial valve according to FIGS. 3 and 4, the means 5 for fixing the oblong body in the blood stream 100 at point 106 of the interior wall 101 of the vessel are rotation fixing means. These means can also be constituted by a seam connecting point 34 of base 32 of the oblique cone with point 1 G of the internal wall of the blood vessel by means of a biocompatible but non-absorbable thread, for example with a PTFE wire.

The implantation of an artificial valve like that illustrated in FIGS. 3 and 4 presents, like the previous one, no difficulty for the operator.

When it is installed as shown in Figures 3 and 4, it works as follows:

When the blood flow 104 flows in the preferential direction 103, the solid cone in the shape of an oblique cone takes a natural position in which it offers the blood flow 104 the lowest pressure drop. This position can be illustrated by that which is represented in FIG. 3.

If the blood flow 104 tends to flow in the opposite direction to the normal direction 103, the pressure difference which exists in this case between the upstream and the downstream as defined above for the normal flow, pivot the solid cone around point 106 and make it take a position like that illustrated in FIG. 4. As, in the case of such a reflux, the value of the projection of the base 32, substantially along the axis longitudinal 105 of the vessel on a plane 6 substantially perpendicular to this longitudinal axis, is substantially equal to the cross section of the vessel, the base 32 of the envelope conforms to the interior wall of the vessel. The envelope then almost completely closes the blood vessel and opposes reflux. In an advantageous embodiment, at least one point of the oblong body 2, for example the fixing point 34 defined above, is also attached by a link 36, for example made of PTFE, to a point 35 outside the blood vessel and belonging to a resistant element. This embodiment has the advantage, in the event that the attachment points give way, of keeping the oblong body in the blood vessel in a determined location and of preventing it from being entrained by the blood flow.

In the first embodiment described above, the means which prevented the envelope from turning over, that is to say which prevented its end 3, normally upstream in the correct direction of blood flow, from passing into downstream from its end 4, were constituted by the fact that the oblong body was fixed to the interior wall of the blood vessel at at least two points 106, 108 located on the same generatrix of the vessel. In this second embodiment, these means are simply constituted by the fact that the length of the generator 33 of the oblique cone is greater than the diameter of the vessel. In this way, if, under the action of blood flow in the normal direction 103, the solid cone tends to rotate around the point 106 of too great an amplitude, the end 3 of the cone abuts against the wall inside 101 of the vessel, preventing the cone from turning over, that is to say its end 3 from being found downstream of its end 4 relative to the normal flow 103 of the blood flow 104.

It should be noted that, unlike heart valves, it is not necessary for such an artificial valve for blood vessel to function by achieving a perfect seal in the direction of preventing blood reflux. All that is required is a relative seal eliminating most of the reflux.

Preferably, in the case where the oblong body 2 is hollow, it is even advantageous for the end 3 of smaller section to have a small orifice 40 to maintain, inside the oblong body 2, a slight blood circulation and thus avoid blood stasis which can lead to clotting or thrombosis.

From the above description, it appears that the artificial valve for blood vessel according to the invention is very advantageous, essentially by the simplicity of its structure, the reliability of its operation and the ease of its installation inside. a blood vessel by remote introduction using a catheter.

Claims

1. Artificial valve for a vessel (100) traversed by a blood flow (104) in a given preferential direction (103), characterized in that it comprises:

- an oblong body (2) having a cross section capable of being increasing between its two ends (3, 4), said oblong body being located in said vessel (100),

- first means (5) for fixing a point (34) of said oblong body with a first point (106) of the interior wall (101) of said vessel so that the end of the smallest section (3) of said oblong body is located upstream (102), in the preferential direction of circulation of said blood flow, with respect to the other end (4) capable of being of larger section, and

- Means for increasing, when the blood flow tends to flow back into said vessel, the value of the projection, along substantially the longitudinal axis (105) of said vessel, of the section of the end (4) of said oblong body (2) able to be the largest, on a plane (6) substantially perpendicular to said longitudinal axis, until this projection is substantially equal to the cross section of said vessel.

2. Valve according to claim 1, characterized in that said oblong body (2) having a cross section capable of being increasing between its two ends consists of an envelope (21) whose general shape is that of a horn substantially conical.

3. Valve according to claim 2, characterized in that said envelope (21) is made of a relatively flexible material.

4. Valve according to claim 3, characterized in that it comprises means for maintaining at least two points of the interior wall of said envelope so that the opening (22) of said horn which constitutes the end ( 4) which is capable of having the largest section is at least partially open.

5. Valve according to claim 4, characterized in that the means for maintaining at least two points of the inner wall of said envelope are constituted by elastic means.

6. Valve according to one of the preceding claims, characterized in that it comprises second means (7) for fixing said oblong body at at least one second point (108) of the interior wall of said vessel, not confused with the first (106) and so that said second point is located on a straight line substantially parallel to the longitudinal axis (105) of said vessel and passing through said first point.

7. Valve according to claim 1, characterized in that said oblong body having a section capable of being increasing between its two ends consists of an envelope whose general shape is that of a solid horn having substantially the shape of a oblique cone (31).

8. Valve according to claim 7, characterized in that said fixing point (34) of said oblong body with the point (106) of the inner wall (101) of said blood vessel (100) is substantially located on the base (32 ) and the shorter length generator (33) of said oblique cone (3 1).

9. Valve according to one of claims 7 and 8, characterized in that the generator of said oblique cone of shorter length (33) is greater than the diameter of said vessel.

10. Valve according to one of claims 7 to 9, characterized in that the first means (5) for fixing said oblong body in said vessel at a first point (106) of the inner wall of said vessel are fixing means in rotation.

1 1. Valve according to one of claims 1 to 10, characterized in that it further comprises a link (36) connecting a point of said oblong body (2) to a point (35) outside the blood vessel (100 ) and belonging to a resistant element.

12. Valve according to one of claims 1 to 1 1, characterized in that said oblong body (2) has an orifice (40) formed at the end (3) of smaller section.