WO1994014389A1

WO1994014389A1 - Device for preventing thrombus circulation in vascular ducts

Info

Publication number: WO1994014389A1
Application number: PCT/FR1993/001310
Authority: WO
Inventors: Thierry Darnis; Jacques Gardette
Original assignee: Cardial
Priority date: 1992-12-28
Filing date: 1993-12-28
Publication date: 1994-07-07
Also published as: FR2699810A1; AU5818194A; FR2699810B1

Abstract

A device including a substantially rectilinear axial member or body (3) and two separate groups (4, 5) each including a plurality of flexible arms (6) of substantially the same length arranged in an operative configuration and each extending along a generatrix of a roughly conical tapered envelope coaxial with said axial member, as well as a device (9), located on said axial member, in which the ends of the arms meet. In said operative configuration, the free arm ends (8) roughly define a circle lying in a plane that is substantially perpendicular to the axial member, and corresponding to the periphery of the theoretical base of the tapered envelope.

Description

DEVICE FOR STOPPING THE CIRCULATION OF THROMBUS IN VASCULAR CONDUITS

The invention relates to a device for stopping the circulation of thrombi in vascular ducts.

The state of the art includes all kinds of devices, as described in the documents

US-A-3,334,629, US-A-3,540,431, US-A-4,425,908,

DE-A-3 429 850, DE-A-3 417 738, EP-A-0 270 432, FR-A-2 587 646, FR-A-2 587 901 and FR-A-2 632 848.

These devices are each studied to be able, on the one hand, via a catheter or endoscope, to be introduced into a vascular conduit, having been previously brought into a configuration called folded in a tube and, on the other hand, to be elastically released from said tube in the vascular duct, and adopt a so-called service configuration in which they perform a blood filtration function.

Some of these devices, such as those described in documents EP-A-0 270 432 and FR-A-2 632 848 use two groups of flexible branches.

In accordance with document EP-A-0 270 432, a device has been proposed comprising:

- a substantially straight axial element or filiform body;

- two distinct groups or bundles of flexible branches, each comprising a plurality of said branches, substantially the same length in each group, extending in the service configuration, each along a generatrix of an approximately conical flared envelope, coaxial with said element axial, a means of joining the fixed ends of said branches, located on said axial element, the free ends of said branches, in the service configuration, being located approximately on a circular bearing circle, included in a plane substantially perpendicular to the axial element, corresponding to the periphery of the fictitious base of the flared envelope.

According to document EP-A-0 270 432, on the one hand the two groups of flexible branches are located at a distance one behind the other, with their vertices situated respectively at the two ends of the axial element, and on the other hand, the two concavities, determined by the internal faces of the flared envelopes of the two groups of branches respectively, are oriented in the same direction and in the same direction.

The major drawback of such a filter is its longitudinal size, which is conventionally of the order of two and a half to three times the diameter of the vascular conduit in which it must be implanted, which therefore limits its use to conduits whose length is greater than that of the devices considered.

Furthermore, it is known that such devices are mechanically subjected repeatedly to centripetal compressions and centrifugal expansions, originating from the anatomical movements of the rib cage under the effect of respiration. These movements can cause a migration of the filter, in the direction of the blood flow, and, what is rarer, in the opposite direction of the flow, this migration being able to represent a danger for the patient who receives such a device.

The invention aims to obtain a device which, although comprising two bundles of flexible branches, has, for a given diameter of vascular duct, a shorter length than that of known devices, with nevertheless a stable positioning at least equivalent to that of the latter .

A device according to the present invention is characterized in that, in combination, on the one hand the two concavities of the two groups of branches respectively are inverted and turned one towards the means of joining the other, and on the other hand the two groups are positioned on the axial element with a distance L3, separating the two meeting points of the branches of the two groups respectively, greater than 0, and less than the sum axial dimensions L1 and L2 of the two groups respectively, each axial dimension L1 or L2 being measured between the base of the flared casing and the meeting point of the branches of each group.

A device according to the present invention also provides the following determining advantages.

Its center of inertia being located in the service configuration in the middle of the vena cava, it s' self-center in the latter, not only during its establishment, that is to say by excluding virtually any movement scale capable of altering its filtration capacity, but also during its use, that is to say without having a preferential equilibrium position.

With a preferably thin axial element, it has great flexibility, allowing it to adapt by torsion to any permanent or temporary conformation of the vein in which it is implanted.

It allows any thrombus to be retained, both in the center of the device and on its periphery, to promote natural and / or medicinal fibrinolysis.

And finally, its undifferentiated shape allows it to be implanted, both from above, for example by the jugular vein, and from below, for example the femoral vein. The invention will be better understood with the aid of the description below given by way of nonlimiting example with regard to the appended drawing which schematically represents: - Figure 1: a section in an axial plane of a device according to the invention, FIG. 2: an axial view, that is to say along the axis of the axial element of the device according to FIG. 1,

- Figures 3 and 4: on a larger scale and seen along F, a fastening element in two alternative embodiments. Referring to FIG. 1, we can see a device 1 in service configuration intended to stop the circulation of thrombi (not shown) in a vascular duct 2.

The device comprises: - a body or axial element 3, constituted by an approximately straight rod, particularly fine and flexible,

two separate groups or bundles 4, 5 each comprising a plurality of flexible branches 6 which, in each group, on the one hand, have one fixed 7 with their ends 7, 8 joined by means 9 provided for this purpose, substantially at a point 10 located on the element or body 3 and, on the other hand, in a so-called service configuration each extend substantially along the generatrices of a flared envelope 11, approximately conical coaxial (shown in thin dashed lines ), with that 3a of element 3 and this, according to a generally regular angular arrangement.

From its fixed end 7 to its free end 8, each branch 6 has a relatively long straight part, a curvature towards the axis 3a, and a relatively short straight part.

The flared envelope 11 defined by the branches 6 of each group has an internal face which therefore determines its concavity.

For example, the flexible branches 6 are made of round wire.

Some of the free ends 8 of the flexible branches 6 have local support elements 12 on an internal face 13 of the vascular duct 2, while others have hooking elements 14 in the wall 15, the said vascular duct 2.

Advantageously, at least some of the ends 8 of the branches 6 which are equipped with hooking elements 14A are also equipped with support means 14B limiting the contact pressure between each of said ends 8 and the vascular wall 15 to a predetermined value.

This feature makes it possible to limit the risk of perforation of the wall 15 of the duct 2 which receives the filtering device.

For example, as shown in FIG. 3, at least some of the support means 14B each consist of a support foot created at the level of the hooking element 14A, by local flattening of the wire which constitutes the branch 6 carrying said attachment element.

In another embodiment, represented in FIG. 4, at least some of the support means 14B are produced by the lateral surface of a bent section of the end of the branches 6 equipped with a hooking element 14A.

Also conventionally, the branches 6 ′ of the same group 4, 5 have substantially the same length and, therefore, the free ends 8 of these branches 6 are, in the service configuration of the device, located approximately on a circle which constitutes therefore the periphery of the fictitious base 16 of the flared envelope 11 defined by said branches 6.

In this device, the free ends 8 of the branches of each group 4, 5 thus make it possible to define two distinct circular supports widely spaced from one another in planes perpendicular to the axis of the element 3.

As shown in Figure 2, the two groups 4 and 5 are angularly offset by 30 ° around the axis 3a, and for a given group 4 or 5, the six branches 6 are angularly spaced 60 °, the branches with hooking elements 14A alternating with those without said support elements 12.

For example, the free ends 8 of the branches 6 of the two groups 4, 5 make it possible to define support taps in particular on the vena cava, which are distributed in two series of points, axially separated by a distance which can be between 20 millimeters and 40 millimeters. Each group 4, 5 of flexible branches 6 has, moreover, a determined axial dimension L1, L2, which is measurable between, on the one hand, its base 16 and, on the other hand, the point 10 of meeting of said branches 6 The dimensions L1 and L2 can be either identical or different.

The flexible branches 6 of each group 4, 5 are flexible between, on the one hand, the position in which they give the device its so-called service configuration, represented in FIG. 1, and, on the other hand, a folded position, not shown, in which they extend substantially parallel to each other to give the device its configuration called introduction.

The groups 4, 5 of flexible branches 6 have their concavities facing one another, in opposite directions D1, D2; the concavity of one group 4 is turned towards the means 9 for joining the other group 5, and vice versa.

According to an essential characteristic of the invention, the groups 4, 5 of flexible branches 6 are positioned on the axial element 3, so that the value of the distance L3 which separates the meeting points 10 from their branches 6 on the said element 3 is between: - on the one hand, a significant value greater than zero, - and on the other hand, a value that is less than the sum of the axial dimensions L1, L2 of these two groups 4, 5, in such a way that each group 4, 5 turns its concavity towards the means 9 for joining the branches of the other group 5, 4.

The groups 4, 5 of flexible branches 6: - on the one hand, have approximately equal axial dimensions L1, L2 and,

- on the other hand, are arranged on the axial body 3, so that the meeting point 10 of the flexible branches 6 of each group 4, 5 is located substantially in the plane of the fictitious geometric base 16 of the flared envelope 11 approximately conical coaxial and defined by the branches 6 of the other group 5 or 4.

The flexible branches 6 of each group have in a plane perpendicular to the longitudinal axis of said group a determined angular distribution, in particular substantially regular.

The flexible branches 6 of the groups 4, 5 are, around the longitudinal axis 3a of the axial element 3, offset so that the groups interpenetrate without there being, in service configuration of the device, contact between their branches 6, nor of gene with their displacement of the configuration known as of service to the configuration known as of introduction and, vice versa.

The axial element 3 of the device is flexible, which allows the device to follow the flexion movements of a vascular duct and / or if necessary to adapt to the curved configuration of such a vascular duct.

Of course, the invention is in no way limited to the embodiment described in the present patent application.

Thus, groups 4, 5 can have four, six or eight branches, and thus constitute systems:

- 8 branches / 8 branches - 6 branches / 6 branches (shown in Figure 2)

- 8 branches / 6 branches - 8 branches / 4 branches

- 6 branches / 4 branches.

However, in general, the number of branches will be between six and eight branches for each group 4 or 5.

Similarly, it is conceivable that the flexible branches 6 are not curved but straight.

The material used for the production of this device is, for example, a metallic alloy of medical quality, advantageously, a non-magnetic alloy with around 40% of cobalt, compatible with nuclear magnetic resonance exploration.

The diameter of the wires which constitute the branches 6 can be between 0.30 and 0.5 millimeters, and more advantageously, 0.4 and 0.45 millimeters.

As already said, at least some of the ends of the branches of each group are equipped with hooking elements 14A and, as shown in FIG. 2, the device is equipped with hooking elements oriented in opposite directions, for two branches 6 located in the same axial plane.

The fact that the device according to the invention has two groups of support points, and in particular hooking points, which are inverted, makes it possible to give it exceptional axial stability, both in the direction of blood flow and in the retrograde direction.

The nested double cone architecture of the device according to the invention makes it possible: - on the one hand, to remove the thrombi from the axis of the duct and thereby facilitate their thrombolysis at the wall of the duct and, on the other hand, to have a double filter.

Claims

1) Device (1) intended to stop the circulation of thrombi in the vascular conduits (2), which device comprises: - an element or an axial body (3);

- two separate groups (4,5) each comprising a plurality of flexible branches (6), substantially the same length, extending, in a service configuration, each along a generatrix of a flared envelope (11) approximately conical coaxial with said axial element (3), means (9) for joining the ends of said branches, located on said axial element, the free ends (8) of said branches, in the service configuration, being situated approximately on a circle included in a plane substantially perpendicular to the axial element (3), corresponding to the periphery of the fictitious base (16) of the flared envelope (11), characterized in that, in combination, on the one hand, the two concavities, determined by the internal faces of the flared envelopes of the two groups (4,5) of branches respectively are reversed and turned towards one the means (9) of meeting of the other, and on the other hand the two groups (4,5) are posi tiated on the axial element (3) with a distance L3, separating the two meeting points (10) of the branches (6) of the two groups respectively, greater than 0, and less than the sum of the axial dimensions L1 and L2 of the two groups (4,5) respectively, each axial dimension L1 or L2 being measured between the base (16) of the flared envelope and the meeting point (10) of the branches' (6) of each group.

2) Device (1) according to claim 1, characterized in that some of the free ends (8) of the flexible branches (6) have local support elements (12) on an internal face of the vascular conduit (2). 3) Device (1) according to claim 2, characterized in that certain free ends (8) of the flexible branches (6) have hooking elements (14) in the wall (15) of said vascular duct (2) ).

4) Device (1) according to claim 3, characterized in that the free ends (8) equipped with hooking elements (14A) are oriented in opposite directions, for two branches (6) located in the same axial plane .

5) Device (1) according to claim 3, characterized in that some of the free ends (8) equipped with hooking elements (14A) are also equipped with support means (14B), in order to limit the pressure of contact between said ends (8) and the vascular wall (15).

6) Device (1) according to claim 5, characterized in that at least one support means (14B) consists of a support foot formed at the attachment element (14A), by local flattening of the flexible branch (6) carrying said hooking element (14).

7) Device (1) according to claim 5, characterized in that a support means (14B) consists of a bent section of the flexible branch (6) at said hooking element (14).

8) Device (1) according to any one of claims 1 to 7, characterized in that the flexible branches (6) of a group (4) have a length different from that of the flexible branches (6) of the other group (5).

9) Device (1) 'according to any one of claims 1 to 8, characterized in that each group (4,5) comprises, one independently of the other, four, six, or eight flexible branches (6 ). 10) Device (1) according to claim 9, characterized in that each group (4,5) comprises, one independently of the other, six, or eight flexible branches (6).