IL106577A - Intravenous filter - Google Patents

Description

AN INTRAVENOUS FILTER Inventors: Edward Shifrin Isaak Portnoy Solomon Zelmanov Gennady Nickelshpur Baruch Morag Field of Invention The present invention relates to intravenous filters placed inside a vein, especially in the inferior vena cava or iliac vein, to keep emboli out of the lungs.

Background of the Invention There are intravenous filters known which, like an umbrella, fold up before being delivered by an introducer and unfold inside the vein when they are brought in the working position.

Said filters are manufactured on an industrial level from metal wire with a resilient or memory effect, such as stainless steel, titanium or nitinol, see: Greenfield filters, "Medi-tech, Inc." filters, "Boston Scientific Corp." See also U.S. Pat. No. 4,817,600 and U.S. Pat. No. 5,059,205. Each of said filters is a bundle of metal wire segments rigidly interconnected, at least in one or two points, by soldering, welding or by a lock.

' Such filters are not entirely reliable as the rigid connection of separate elements can break down under the blood flow aggressive conditions, so some filter fragments may get into the heart.

Besides, such filters, when folded up, have an outer diameter of at least 3...5 mm, so an introducer of a considerable diameter (5...8 mm) is required for their insertion. Therefore the filter insertion procedure becomes more complicated and likely to injure the patient.

There are also known filters of the "Bird's nest" or "Collapsible basket" type U.S. Pat. No. 4,494,531 and U.S. Pat. No. 4,619,246. Such filters are manufactured, for instance, by "Cook, Inc.", USA.

These filters are also produced on an industrial level as a bundle of rigidly interconnected filaments and placed in the vein by a simple unfolding ("Collapsible basket") or by a mechanical entangling of wires into a bundle immediately in the vein ("Bird's nest"). In the latter-case the danger of injury to the vein walls increases as said walls are subjected to considerable loads. For the insertion of such filters a great diameter introducer is also required which makes the procedure more complicated and likely to injure the patient.

Recently there appeared filters made of plastic or a biologically decaying material compatible with human tissues .

Said filter designs are similar to those disclosed above and have the same drawbacks.

The Prior Art Most similar to the present invention are filters made from one or two metal wires with a resilient or memory effect, such as filters disclosed in PCT patent applications Numbers WO 9216163, WO 9211823, WO 9104716; European patent applications Numbers EP121 47, EP323333 and French patent application Number 2645731.

Said filters' common drawback is that they start to acquire the required shape immediately after withdrawing from the introducer, which causes errors in the filter positioning relative to a certain vein area. It is virtually impossible to correct the position of such a filter after its unfolding.

An object of the present invention is to provide a technology for producing and inserting, as well as designing of filters which permits the guidance of an introducer into a patient's vein by a percutaneous injection, provides high accuracy in the filters positioning and the patient's safety.

Summary of the Invention The present invention relates to an intravenous filter produced from a single piece of material shaped as a wire, band, plate, filament or tube of metal, plastic or any other biologically inert material, and formed as a three-dimensional spiral with coils having the same or opposite directions for insertion into a vein lumen and the filter is placed into an introducer cavity or capsule disposable within said introducer, prior to insertion into a vein lumen.

The filter is produced from a piece of wire, plate or strip formed of metal or a metal alloy having a resilient or memory effect or of plastic , such as a piece of a plastic tube or a Gore-tex filament.

The filter is made of a piece of material having in its cross section a round, rectangular, square, tubular or other shape different from the round one.

The filter can be made in the vein itself from filaments of a quickly solidifying, biologically inert material .

The filter can be made in the vein itself from a plastic tube subsequently filled with a quickly solidifying, biologically inert material which imparts the tube the predetermined filter shape and size.

The filter can be made of metal and coated with an indifferent antithrombotic material such as Gore-tex. The plastic filter is made radio-opaque such as by coating it wholly or in part with a thin film (amalgam) of metal or introducing special additives into the filter material. The filter blank is first put into the required shape and subsequently straightened and inserted into the introducer cavity or capsule placed in said cavity. The capsule is made of a soluble, biologically compatible material such as frozen, biologically compatible liquid, such as a solution of glucose or blood plasm of the patient itself, or gas such as carbon dioxide- converted into a solid state. When the capsule with the filter are withdrawn from the introducer, it is positioned i a certain vein area. Thereafter the filter and capsule material is acted on by the blood flow temperature and/or a short-time pulse of electric current. Thereby the filter is separated from the capsule and put into the required shape.

When the filter without the capsule is removed from the introducer cavity, its material is acted on mechanically or otherwise to move it progressively to the insertion area while the distal end of the introducer can describe a designed three-dimensional trajectory.

When the filter is made from a plastic tube, such as Gore-tex, reinforced by a metal member with a memory effect, and the structure can be additionally reinforced by pumping, through an introducer channel, a quickly solidifying elastic material into the tube.

To put the filter into the final shape, it can be acted on by a short-time electromagnetic pulse (for a metal or metal coated filter) or by introducing inside the filter an introducer inflatable balloon until the filter material solidifies (for a filter of plastic or quickly solidifying material). According to said method the filter is formed as a three-dimensional spiral with coils having the same or opposite directions, or as a spherical or ellipsoid bundle of entangled wire, strip, filament or tube.

The filter is formed as a three-dimensional spiral, including a straight middle portion extending approximately along the vein axis, the ends of said portion go over to tow cylindrical spirals with coils having opposite directions .

The filter can be formed as a three-dimensional spiral with coils having different diameters and the same direction, the outer surface of said coils forming a one sheet hyperboloid of revolution.

And it is also possible, according to said method, to form the filter as a piece of a strip or tube with through cuts and/or perforations. In this case the strip is bent finally forming a curved surface parallel or perpendicular to the longitudinal axes of said cuts and perforations.

The tube disposed between said cuts are made integral at least by one bridge.

Said blank is finally formed as a three-dimensional curved surface with an annular bridge oriented substantially along the vein longitudinal axis, and the tabs are bent and extend from the ring in the longitudinal and/or lateral direction.

The filter can be made from a perforated strip bent as a curved surface, the latter being shaped as a one sheet hyperboloid of revolution.

Other advantages and features of the present invention will be apparent from the following detailed description of five embodiments thereof presented in conjunction with the accompanying drawings.

Brief Description of the Drawings FIG. 1-4 - is a side view of filters made from a single piece of a strip; FIG. 5-6 - are versions of positioning the filters in a capsule inside the introducer; FIG. 7-8 - is the procedure of the intravenous filter insertion in the vein; FIG. 9-16 - is the external view of a filter blank made from a piece of a strip, or of a plate, side view of the filters and their placement inside the introducer; FIG. 17-19 - is the process of inserting a filter made from wire, filament or tube by means of a computerized introducer; FIG. 20-21 - are design versions of a filter made from a tube or strip; FIG. 22 - is the filter insertion by means of an introducer with an inflated balloon; FIG. 23-24 - is the design and insertion of a filter made from a plastic tube, reinforced with an element having a memory effect and strengthened by a quickly solidifying filler.

Detailed Description of the Drawings Below the following embodiments of the present invention are presented: Embodiment 1 The intravenous filter (1 ) is made in a familiar manner from a metal strip (2) [FIG. 1 - 3 ] or wire (3) [FIG. 4] and the filter material is subjected to a known treatment (mechanical working, hardening etc.) to impart a resilient or memory effect.

The finished filter is straightened in a special device under certain conditions (temperature, pressure) and then frozen in a solution of glucose or liquid carbon dioxide (not shown in the drawings) in such a manner, that the straightened filter is found inside a piece of frozen liquid or gas shaped as a cylindrical capsule (4) of a certain size with rounded ends. It is also possible to freeze in together with filter the distal end (5) of guide (6) of the introducer (7) [FIG. 5, 6]. As a capsule material the blood plasm can be employed as well, said plasm being taken from the patient whom the intravenous filter is to be inserted. The capsule and the guide are placed in the introducer (7) cavity. Thereafter said introducer is inserted into the vein (8) by puncture and guided to a required vein area [FIG.7].

The entire manipulation is performed under a monitor control. It is also possible to introduce into the vein only the introducer (7) without the capsule (4) and guide (6), which are inserted in the introducer (7) channel after its delivery into the vein (8). In this case the capsule (4) becomes more reliable as" it may be kept, before use, in a special package inside a usual refrigerator or Dewar vessel (thermos).

When the introducer (7) is anchored in the required area, the capsule (4) is removed from said introducer (7) by means of the guide (6). The capsule position in the vein (8) required area is carefully checked and fixed, and thereafter an interval is made. During said interval the capsule material decays under the action of the blood flow temperature in the vein (8).

It is also possible to accelerate the capsule decay by applying a pulse of electric current fed through a metal guide (6). Under the action of the blood flow temperature in the vein (8), the capsule (4) gradually dissolves, and the filter (1), under the action of its material resilient or memory effect, acquires its required shape and fills the vein (8) lumen, preventing the emboli passage [FIG.8].

Since the process is delayed, it is possible to correct, if necessary, the filter (1 ) position in the vein (8).

Then the introducer (7) and the guide (6) are removed from the vein (8) in a known manner. It is also possible to coat the filter metal by an indifferent antithrombotic material such as Gore-tex.

Embodiment 2 The intravenous filter (1 ) is made in a familiar manner from a plate or a piece of a strip with through slots (9) and/or perforations (10) [FIG. 9, 10, 11]. Thus the blank acquires the form of a solid (11) or perforated (12) bridge with tabs (13) extending from it. Said tabs can be disposed in a parallel relationship [FIG. 9,10] and/or at an angle A to each other [FIG. 11 ].

As a filter material, a thin metal strip or foil can be used.

The filter blank is thereafter coiled and treated to impart a resilient or memory effect to it. Subsequently the filter blank is tightly rolled up into a coil (14) and frozen (not shown in the drawings). Thus a capsule (4) is formed. Said capsule with the filter (1) rolled up into a coil (14) is inserted into the introducer (7) [FIG. 16]. The coil formed by rolling up the blank [FIG.11] has a smaller diameter than a coil of any other blank, as the tabs and the bridge in the coil are coaxial. All the other manipulations with the introducer (7) are carried out in the same way as in Embodiment 1. The filters described in Embodiment 2 can be also covered with an antithrombotic material such as Gore-tex.

Embodiment 3 The intravenous filter (1 ) can be also made in the vein (8) itself by delivering a wire, filament or a thin tube (15) to the desired vein area by a special introducer (16) , equipped with a pivoting nozzle (17) [FIG. 17 - 19].

The filter material is fed to the desired area from an extendible pivoting nozzle (17) of the introducer (16), inserted into the vein before. This operation is controlled by a computer (18) [FIG. 19], and nozzle (17) moves along a designed trajectory, so that a bundle of entangled filament, wire or thin tube is formed in the vein (8), said bundle having the predetermined parameters.

It is also possible to feed into the tube (15) of the filter (1 ) a quickly solidifying, biologically inert material which, after its solidification, imparts the desired shape and stiffness to the filter (1 ).

It is further possible to make the filter (1) in the desired area of the vein (8) by extruding from the nozzle (17) a filament of a liquid, quickly solidifying, biologically inert material. After solidification the filament forms a bundle shaped as an ellipsoid.

To improve the filter (1) shaping from a quickly solidifying filament, an inflated balloon (19) can be introduced inside the filter, said balloon being disposed in a supplementary channel (20) of the introducer (7) [FIG. 20] .

When the filter shaping is completed, the balloon (19) is removed. Thereafter the introducer (7) is as well removed from the vein (8) in a usual manner.

Embodiment 4 The filter (1 ) is made of plastic tubes or filaments [FIG. 21, 22], such as Gore-tex.

The tube material is made radio-opaque by coating it with a thin film (amalgam) of metal or introducing atoms of metal into said material. The filter (1) can be made of such a tube with previously notched ends (21) [FIG. 21] extending along the tube axis. The tube (15) is inserted into the introducer (7) cavity and the latter is introduced into the vein (8) in an above-mentioned manner. The tube (15) is released and positioned relative to the vein (8). Thereafter, by a short-time electromagnetic pulse from an electromagnet disposed inside the tube (15) at the distal end (5) (not shown in the drawings) of a guide (6), the notched ends (21 ) of the tube (15) are opened. As a result, the tabs (22) formed at the tube (15) ends abut on the vein walls, converting the tube into an intravenous filter (1 ) [FIG.21 ]. All the other manipulations with the introducer are carried out as described above.

It is also possible to make the filter (1) from a combination of tubes (23) and filaments (24) produced from plastic with a metal coating.

The filter can be shaped, for instance, as a one sheet hyperboloid of revolution [FIG. 22]. Such a filter is inserted and anchored as described above.

Embodiment 5 The filter (1) is made of a plastic tube (25) such as Gore-tex reinforced by a metal element (26) with a memory effect. The tube outer surface is made rough.

The filter is inserted into the introducer (7) cavity and introduced into the vein (8) as described above. The filter (1 ) placed in the vein (8), acquires, due to the memory effect, the desired form, being pressed against the inner surface of the vein (8) by the rough surface (27) of the tube (25) [FIG. 23, 24]. To strengthen the filter (1 ), a quickly solidifying, biologically inert material (28) is introduced into the channel (29) of the tube (25).

All the other manipulations with the filter (1) and introducer (7) are performed as described above.

The application of the present invention allows the insertion of an introducer by puncture and provides a highly accurate filter positioning, and moreover, gives the following advantages: 1. The quantity production of cheap filters can be launched using the existing processes and materials. 2. Effective operation of filters which do not injure the vein walls when the vein narrows or expands, as the filters are anchored to the vein walls not by hooks but only due to the roughness of the outer surface and resilience of the filters . 3. Simultaneous insertion of several filters that can be disposed in a common introducer and be of different designs and purposes . 4. According to the present invention, the method permits the construction of smaller filters, for example for iliac veins (see No 27 of Claims), which broadens the possibility for its use.

In the description of the specific embodiment of the invention shown in the drawings specific terms are used. However every term specifies all equivalent members operating likewise and used to solve the same problems as the present invention.

Above a description of the method and design preferred embodiments are given. However, many improvements, changes and additions of equivalent members may be made without depriving the present invention of its advantages as cited in the claims below.

Claims (4)

1. Claims 1. An intravenous filter produced from a single piece of material shaped as a wire, strip, plate, filament or tube of metal, plastic or other biologically inert material, and formed as a three-dimensional spiral with coils having the same or opposite directions for insertion into a vein lumen and the filter is placed into an introducer cavity or capsule disposable within said introducer, prior to insertion into a vein lumen.

2. An intravenous filter made according to claim 1 and formed as a spherical or ellipsoid bundle of entangled wire, strip, filament or tube.

3. A filter according to claim 1, formed as a three-dimensional spiral, including a straight middle portion extending approximately along the vein axis, the ends of said portion go over to two cylindrical spirals with coils having opposite directions.

4. A filter according to claim 1 , formed as a three-dimensional spiral with coils having different diameters and the same direction, the outer surface of said coils forming a one sheet hyperboloid of revolution . A filter according to claim 1 or $. made from a metal wire or strip. A filter according to claim 1 or ¾ made of a plastic filament or tube, such as a Gore-tex filament or tube. An intravenous filter made according to claim 1 from a blank formed as a strip or tube with through cuts and/or per orations. An intravenous filter according to claim 7 , wherein the blank is made from a piece of a strip or tube with through cuts, open from one side, the tabs disposed between said cuts being made integral at least by one bridge . An intravenous filter according to claim g , wherein the blank is made from a piece of a strip bent as a curved surface with a generatrix parallel or perpendicular to the long axis of said cuts. An intravenous filter according to claim % wherein the blank is formed as a piece of a strip, plate or tube, the tabs, formed by said cuts, being parallel or at an angle to each other, and the ends of said tabs form the filter bearing surface. A filter according to claim 1 or JL made from a metal wire or strip. A filter according to claim 1 or 3. made of a plastic filament or tube, such as a Gore-tex filament or tube. An intravenous filter made according to claim 1 from a blank formed as a strip or tube with through cuts and/or per orations. An intravenous filter according to claim 7 , wherein the blank is made from a piece of a strip or tube with through cuts, open from one side, the tabs disposed between said cuts being made integral at least by one bridge . An intravenous filter according to claim , wherein the blank is made from a piece of a strip bent as a curved surface with a generatrix parallel or perpendicular to the long axis of said cuts. An intravenous filter according to claim % wherein the blank is formed as a piece of a strip, plate or tube, the tabs, formed by said cuts, being parallel or at an angle to each other, and the ends of said tabs form the filter bearing surface. 1. A filter according to claims 8 and 9 , made as a three-dimensional curved surface, formed by an annular bridge v/ith bent tabs extending from said bridge, the ring of said bridge being oriented substantially along the vein longitudinal axis, and the tabs extend from said ring substantially in the longitudinal and/or lateral direction. 12. A filter according to claim 7 made from a piece of a perforated strip bent as a curved surface, the latter being shaped as a one sheet hyperboloid ^of revolution .