WO1998002112A1 - Extensible filtering sheath for surgical use for vena cava or large blood vessels - Google Patents

Abstract

The invention discloses an extensible filtering sheath for surgical use for vena cava or large blood vessels. It consists of a sheath (2) formed by two radially extensible hollow tubular elements (5, 6), with a malleable, semirigid and self-extensible latticed wall, mutually linked by two peripheral longitudinal bars arranged to open up into a cone shape across the treated vessel, to form a filtering grid when one of these two elements, the supporting element (5) expands radially, the second expandable element remains compressed, but is shaped to be expanded subsequently so as to stop the filtering by completely clearing the passage of the treated vessel. It is generally useful for filtering or decreasing the blood flow to avoid certain necrotic lesions in tissues due to circulatory disorders caused by excessively high blood pressure, by thrombosis or clotting, and in particular for limiting the risks of infarction caused by the obstruction of the myocardium vessel by a clot or a foreign body carried by the blood circulating in the vena cava.

Description

 EXTENSIBLE FILTER SHEATH FOR SURGICAL USE FOR CELLAR VEIN OR LARGE BLOOD VESSELS

The present invention relates to an extensible filter sheath for surgical use for vena cava or large blood vessels.

It is generally intended to filter or reduce the blood flow to avoid certain necrotic tissue damage due to circulatory disorders caused by too high blood pressure, by thrombosis or embolism, and in particular to limit the risks of infarction caused by the obliteration of a myocardial vessel by a clot or a foreign body carried by the blood circulating in the vena cava.

The devices used to date generally consist of self-expanding filters formed of fibers 1 (Figure 1) connected by one of their ends and opening into an umbrella when the filter is released once brought to the chosen location. These prostheses are previously compressed to be introduced into a tube mounted at the end of a catheter, then expelled from it once in place, the elasticity of the constituent material ensuring their radial extension.

This type of filter has a number of drawbacks. Indeed, it is very difficult to position with precision and, not only does it tend to migrate after its installation, but it often gets in the way at the time of installation. In addition, in most cases, its action must be removed after a certain time, which requires its extraction. Very often this requires a heavy surgical intervention to be able to directly access the vessel concerned.

The device according to the present invention eliminates all these drawbacks. Indeed, it makes it possible to obtain filters for blood vessels presenting a zero risk of migration, while facilitating precise positioning as well as easy decommissioning and without operation. These filters can in no case get across the vessel and simultaneously ensure the expansion of the latter thereby facilitating the flow of blood flow. Finally, the installation is carried out through a hole with a diameter substantially smaller than that necessary for existing systems.

It consists of a sheath formed by two radially expandable hollow tubular elements, with a semi-rigid self-expanding or malleable lattice wall, interconnected by longitudinal peripheral bars arranged so as to deviate in a cone across the vessel blood to be treated, to form a filtration grid when one of these two elements, the maintenance element undergoes radial expansion, the second expandable element remaining in the compressed state, but being configured to allow its subsequent expansion in order to remove the filtration by completely freeing the passage in the treated vessel.

In the appended schematic drawings, given by way of nonlimiting examples of embodiments of the subject of the invention: FIG. 1 (already cited) represents a filter for blood vessels of the type currently used. 2 shows before expansion, side view, a filter sheath according to the invention mounted on an inflatable balloon used to cause the expansion of the holding element, Figure 3 shows in the same conditions the sheath after expansion of the 'holding element, Figure 4 shows the expansion of the second element to remove the filtering effect and Figures 5 and 6 illustrate two alternative embodiments of the filter sheath.

The device, FIGS. 2 to 6, consists of a tubular sheath 2 formed by a portion of hollow cylinder of circular section, and the wall of which consists of a trellis or grating made of malleable semi-rigid material arranged so as to allow said sheath to extend radially under the effect of internal pressure and to keep the shape thus obtained. The internal pressure is caused for example by means of an inflatable balloon 3 mounted at the end of a catheter 4 according to a known technique.

The sheath 2 is subdivided into three elements. one of the ends, the holding element 5, which is the longest in order to prevent any risk of migration, has an expandable trellis structure and has the role of ensuring good attachment of the device to the chosen location inside the vessel, as well as the dilation of the latter. During installation, only this element is placed on the balloon 3 to undergo expansion. At the other end, a second element 6, normally shorter, but with the same structure as the previous one, will remain compressed during installation. Between the two, the filter element 7 proper consisting of longitudinal peripheral bars 8. When the holding element is expanded by the inflation of the balloon 3, because the second element 6 does not undergo expansion, these bars open in cone across the blood vessel to form a grid ensuring the desired filtration ( figure 3).

To remove the effect of the device and completely free the passage in the treated vessel, it suffices to subject the second element 6 to an expansion in the same manner as to ensure the placement of the sheath 2 in the vessel, that is i.e. using an inflatable balloon 3 'mounted at the end of a catheter 4, and inserted inside this second element, which is configured to allow it, which eliminates the need for surgical intervention ( figure 4).

The sheath 2 will preferably be in one piece and produced by laser EDM from a block of metal such as stainless steel or tantalum, or by laser engraving or machining of a thin-walled metal tube . The trellis constituting the two expandable elements 5, 6 will for example consist of longitudinal elongated elements connected to each other by annular elements arranged in staggered rows, but may have any configuration allowing an adjustable extension as a function of the pressure applied.

The filter bars 8 will advantageously have a width close to 20/10 mm, the width of the elongated elements 9 forming the lattice being of the order of 13/10 mm.

The sheath 2 will preferably be manufactured in expanded form, then "crushed" on the inflatable balloon 3. According to an alternative embodiment, the sheath 2 consists of a central retaining element 5 connected by two sets of filter bars 8 to two expandable terminal elements 6 '(FIG. 6).

According to another alternative embodiment, the sheath 2 is self-expanding and produced in expanded form in a flexible material or with shape memory. For its positioning, it is compressed radially and introduced into a hollow tube of small diameter mounted at the end of a catheter and expelled from said tube by an appropriate means when it is in the chosen location.

The expansion of the terminal element (s) (6, 6 ′) is temporarily prevented by virtue of one or more resorbable wires with long resorption time, which allows this or these terminal element (s) to return to their initial shape after a time. more or less long, depending on the number of wires, without any intervention.

In order to facilitate the movement of the sheath 2 during its installation, the free end of the second extensible element 6 (and, where appropriate, that of the other end element 6 ') may be cut at an angle ( figure 5).

For certain applications, the sheath 2 may include integrated fastening means, directed radially towards the outside so as to sink into the internal wall of the vessel under the effect of the pressure of the inflatable element 3, thus preventing all possibilities of moving the device.

The particular structure of the sheath 2 allows it to be used as an anchoring element for a prosthesis tubular, in particular in the case of aneurysm of the abdominal aorta in the vicinity of the departures of the renal arteries. In this case, the entire sheath is expanded

The particular structure of the sheath 2 makes it possible to use it as an anchoring element of a tubular vascular prosthesis in the case of aneurysm in the vicinity of venous or arterial diversions, and very particularly for an aneurysm of the abdominal aorta located near departures of the renal arteries.

In this case, the entire sheath 2 is expanded once brought to the appropriate location, so that the longitudinal peripheral bars 8 are at the location of the branch (s) to allow easy passage of blood, the retaining element 5 being applied against the walls of a healthy part of the vessel to ensure attachment, and the short element 6, oriented towards the aneurysm serving as support for the vascular prosthesis.

The junction of the sheath 2 and the prosthesis can be carried out by means of an internal or external cylindrical annular piece or by fixing elements such as hooks, provided for this purpose on the short element 6.

In order to prevent the endothelium of the vessels from entering the interior of the retaining element 5 through the meshes of the mesh, the latter will advantageously be covered with a flexible film of synthetic material such as polyurethane, silicone or polyester.

To facilitate the operations of setting up and annihilating the filtering, the sheaths 2 will advantageously include radio-opaque markers consisting of X-rays, and made up of layers of a heavy metal such as tantalum, titanium or gold deposited by electrolytic means. These layers may have a thickness close to 0.1 mm.

The positioning of the various constituent elements gives the object of the invention a maximum of useful effects which had not, to date, been obtained by similar devices.

Claims

1 °. Extensible filter sheath for surgical use for vena cava or large blood vessels, intended to filter or reduce the blood flow of important veins and arteries and in particular of the vena cava, in order to limit circulatory disorders caused by excessive blood pressure high, or the risks of infarction caused by the obliteration of a myocardial vessel by a clot or a foreign body carried by the blood circulating in said sheath (2) being self-expanding, or of the type intended to be place by means of an inflatable balloon (3) mounted on a catheter, and consisting of a portion of cylindrical tube which can extend radially and keep the shape thus obtained, characterized in that it is formed of two elements (5 , 6) of different lengths having a wall with an expandable lattice structure radially connected together by longitudinal peripheral bars (8) arranged so as to move apart r in cone across the blood vessel to form a filtration grid, when the longer of these two elements, the holding element (5), undergoes radial expansion, the short element (6) not undergoing expansion. 2 °. Sheath according to claim 1, characterized in that it is made of semi-rigid malleable material, the short element (6) being configured to allow the insertion of an inflatable balloon (3 ') mounted at the end a catheter (4) to cause its expansion in order to suppress filtration by completely freeing the passage in the treated vessel. 3 °. Sheath according to claim 2, characterized in that it is manufactured in expanded form, then "crushed" on the inflatable balloon (3). 4 °. Sheath according to claim 1, characterized in that it is self-expanding and produced in expanded form in a flexible material or with shape memory so as to be able to carry out its positioning by compressing it radially and introducing it in a small diameter hollow tube mounted at the end of a catheter, then driving it out of said tube when it is in the chosen location, the expansion of the short element (6) being temporarily prevented by to one or more resorbable yarns with a long resorption time, so that it returns to its initial shape after a more or less long time depending on the number of yarns, without any intervention. 5 °. Sheath according to any one of the preceding claims, characterized in that the holding element (5) is dimensioned to simultaneously secure the device at the chosen location inside the vessel preventing any migration, as well as the dilation of said vessel. 6 °. Sheath according to any one of the preceding claims, characterized in that it is in one piece and produced by electroerosion from a block of metal such as stainless steel. 7 °. Sheath according to any one of the preceding claims, characterized in that it consists of a central holding element (5) connected by two sets of bars (8) of filtration to two short expansible short elements (6, 6 '). 8 °. Sheath according to any one of the preceding claims, characterized in that the filter bars (8) have a width close to 20/10 of a millimeter, the width of the elongated elements (9) forming the trellis being of the order of 13/10 of a millimeter. 9 ^e . Sheath according to any one of the preceding claims, characterized in that the free ends of the short element (s) (6, 6 ') radially expandable are cut at an angle so as to facilitate movement of the sheath (2) during its implementation. 10 °. Sheath according to any one of the preceding claims, characterized in that it comprises integrated hooking means, directed radially outwards so as to sink into the internal wall of the vessel under the effect of the pressure of the inflatable balloon (3), thus preventing any possibility of movement of the device. 11 °. Sheath according to any one of the preceding claims, characterized in that the holding element (5) is covered with a flexible film of synthetic material so as to prevent the endothelium of the vessels from entering inside. through the mesh of the trellis. 12 °. Sheath according to any one of the preceding claims, characterized in that it comprises radio-opaque marks consisting of longitudinal or annular points or bands visible by X-rays, and made up of layers of a heavy metal such as tantalum , titanium or gold deposited electrolytically, these layers having a thickness close to 0.1 m. 13 °. Extensible sheath for surgical use for blood vessels, intended to serve as an anchoring element for a tubular vascular prosthesis in the case of aneurysm in the vicinity of venous or arterial diversions, and more particularly for an aneurysm of the abdominal aorta located near the outlets of the renal arteries, said sheath (2) being self-expanding, or of the type intended to be placed by means of an inflatable balloon (3) mounted on a catheter, and consisting of a portion of cylindrical tube can extend radially and keep the shape thus obtained, characterized in that it is formed of two elements (5, 6) of different lengths having a wall with a radially expandable lattice structure, interconnected by bars (8) longitudinal peripherals allowing an easy passage of blood towards arterial diversions or coming from venous diversions, the longer of these two elements, the May element ntien (5), being intended to be applied against the walls of a healthy part of the vessel to ensure attachment, the short element (6) being oriented towards the aneurysm and serving as a support for said vascular prosthesis. 14 °. Extensible sheath according to claim 13, characterized in that the short element (6) comprises fixing elements allowing the junction of the sheath (2) and the vascular prosthesis. 15 °. Extensible sheath according to claim 13, characterized in that the junction of the sheath (2) and the vascular prosthesis is carried out by means of an internal or external cylindrical annular piece 16 °. Extensible sheath according to claim 13, characterized in that the junction of the sheath (2) and the vascular prosthesis is carried out by means of hooks.