Vascular filter system for cardiopulmonary bypass

ES 2 249 686 T3

DESCRIPTION

Vascular filter system for cardiopulmonary bypass.

The present invention relates to the treatment of vascular disorders by cardiopulmonary bypass surgery. More particularly, the present invention relates to a system that reduces macro and micro-embolization during cardiopulmonary bypass surgery.

A variety of surgical and non-surgical angioplasty procedures have been developed for opening blood vessel obstructions. Balloon angioplasty uses a balloon tip catheter that can be inserted into a stenosed region of the blood vessel. By inflating the balloon, the stenosed region is dilated. Stenting involves permanent implantation of a metal scaffold in the area of ​​the obstruction, followed by balloon dilation. The stent is sometimes delivered over an angioplasty balloon that develops when the balloon is inflated. Another alternative is the local delivery of medication via an infusion catheter. Other techniques, such as atherectomy, have also been proposed. Atherectomy uses a rotating blade to scrape plaque off an arterial wall. Surgery involves removing plaque from the artery or attaching a graft to the artery to bypass the obstructing plaque.

A common problem of all the mentioned techniques is the potential inadvertent release of parts of the plaque or thrombus, resulting in an embolism that can lodge in any part of the vascular system. Such an embolism can be dangerous for the patient and may cause severe impairment of the distal circulatory bed. Depending on the vessel being treated, this may result in stroke, myocardial infarction, or limb ischemia.

Vascular filters or embolism traps for implantation within the vena cava of a patient are disclosed in patent documents US 4727873 and US 4688533. Additionally, there is a large amount of medical literature describing various designs of vascular filters and reporting the clinical and experimental results of their use. See, for example, the article by Eichelter and Schenk entitled "Prophylaxis of Pulmonary Embolism", Archives of Surgery, Vol 97 Aug 1968, pp 348 ff. See also the article by Greenfield et al. Entitled "New intracaval filter that allows continuous flow and resolution of embolisms", Surgery, Vol 73 No. 4, pp 599-606 (1973).

Vascular filters are used, often during a postoperative period, when there is an appreciable risk of the patient suffering a pulmonary embolism resulting from clots generated at the surgical site. Typically, the filter is mounted in the vena cava to collect large emboli that pass from the surgical site to the lungs.

Prior art vascular filters are typically permanently implanted in the venous system of the patient, such that even after the need for the filter has ceased, the filter remains in place for the life of the patient, preventing surgical removal. US-3952747 discloses a stainless steel filter device that is permanently implanted transvenously within the interior of the vena cava. The filter device is designed to treat recurrent pulmonary emboli. US-4873978 discloses a catheter device comprising a catheter body having a retainer mounted at its distal end. The retainer is movable between an open configuration, in which it extends substantially through blood vessels to trap the passing embolism, and a closed configuration where it retains the captured embolism during removal of the catheter. An operable mechanism at the proximal end of the catheter body allows selective opening and closing of the retainer. Typically, the retainer is a collapsible cone having an apex attached to a wire that runs from the distal end to the proximal end of the catheter body.

Permanent implantation may be considered medically undesirable, but has been done since vascular filters are implanted in patients primarily in response to life-threatening situations. Therefore, the potential advantages of permanent vascular filter implantation are often accepted.

Document US-6280432-B1 discloses a modular system comprising a cannula and at least one access port with a clip. The access port provides for the insertion of a therapeutic or diagnostic device into a vessel or cardiac tissue through a single incision, the cannula and part of US 628 04 32 being designed for use with a filter, as per example the one disclosed in document US 5662671.

Regardless of the utility of the above-described procedures, there is still a need for an apparatus and procedure to substantially reduce the risk of embolisms associated with cardiopulmonary bypass surgery. In particular, it would be desirable to provide a device that could be located within the vascular system to collect and remove portions of plaque and thrombus that have become dislodged during a surgical procedure.

The present invention provides a vascular filter system that can be used to address the clinical problem of avoiding embolization associated with cardiovascular bypass surgery that can result in stroke or myocardial infarction, as briefly described herein. precedes.

An object of the present invention is to provide a vascular filter system to reduce macro- and micro-embolization. Another object of the present invention is to provide a vascular filter system that is easily removable from the vascular system, or elsewhere, of a patient when the filter is not needed. Yet another object of the present invention is to provide a vascular filter system that has a configuration that does not require hooks to penetrate and grip the walls of the blood vessel, so that implantation results in less damage to the blood vessel. Yet another object of the invention is to capture a thrombus or embolism generated during a cardiopulmonary procedure. Yet another object of the invention is to provide a filter membrane with holes of varying size to allow distal perfusion when embolic particles are captured.

The present invention relates to a vascular filter system for use in cardiopulmonary bypass,

ES 2 249 686 T3 that can substantially reduce the risk of distal embolization during surgical procedures, while still allowing perfusion of the distal tissue.

According to the present invention a filter system for cardiopulmonary bypass is provided, comprising:

a housing (366) having distal and proximal ends and a hole (380) with a connector at the proximal end that is adapted for connection to at least one hose (360), and a distal member at the distal end having first and second openings (384, 388), wherein the housing (366) is formed within a first lumen (374) adapted to be in fluid communication with the hose or hoses (360) and extending through the distal member to one of the first openings and second (384, 388), and a second lumen (378) extending from port (380) through the distal member to the other of the first and second openings (384, 388), and a vascular filter system (394) comprising a flip-top filter that can be advanced through the orifice (380) of the housing, said vascular filter system (394) comprising (a) a filter membrane support structure, and (b) a filter membrane attached to said filter membrane support structure, said filter membrane having openings, wherein said apertures have a diameter in the range of about 20 to about 300 microns and the diameters of which vary from one another.

The filter membrane may be thin and porous with openings of variable size capable of blocking the embolism. The filter may be attached to the distal end of a guide wire. In an exemplary embodiment of the invention, a thin, flexible perforated membrane is supported by four supports that form a distally extending basket. At least one end of the basket is attached to the guide wire and the other slidable end can be moved to force the membrane to open or close.

In one embodiment, the filter system comprises an apparatus to be inserted into the aorta of a patient, which comprises a lumen in fluid communication with a housing and another lumen that facilitates the advancement of the vascular filter to be placed downstream. into the aorta from the apparatus to capture any thrombus or embolism introduced during the procedure. More particularly, the filter system comprises a housing having distal and proximal ends, wherein the proximal end comprises a connector for connection to the housing. The distal end has a distal member that has two openings. The housing comprises two lumens, the first of which is in fluid communication with the housing and the second of which is in fluid communication with an orifice or port. The lumens each extend into respective openings at the distal end of the housing. Preferably, the distal end of the housing comprises an apertured distal member extending at an angle, preferably about 90 degrees, for insertion into a blood vessel, such as an artery, specifically the aorta.

An advantage of the present invention is that it provides the benefits of filtering and capturing embolism particles, temporarily, during a surgical procedure. Another advantage of the present invention is that it provides a filter membrane with holes of variable size to allow perfusion while capturing embolism particles.

Some embodiments of the present invention will now be described by way of example and with reference to the accompanying drawings, in which:

Figure 1 illustrates a side view, partially in section, of an exemplary embodiment of the present invention, with the filter membrane in an open position.

Figure 2 illustrates a side view, partially in section, of an exemplary embodiment of the present invention illustrated in Figure 1, with the sheath closed.

Figure 3 illustrates a schematic representation of a part of a filter membrane according to the present invention.

Figure 4 illustrates a side view of a core wire according to the present invention.

Figure 5 illustrates a sectional view through section line 5-5 of a portion of a core wire illustrated in Figure 4.

Figure 6 illustrates a sectional side view of a variant basket structure for the exemplary embodiment illustrated in Figure 1.

Figure 7 illustrates a side view, partially in section, of another exemplary embodiment of the present invention.

Figure 8 illustrates a side view, partially in section, of another exemplary embodiment of the present invention.

Figure 9 illustrates a schematic view, partially in section, of another exemplary embodiment of the present invention, in which the distal section of the filter basket is inverted.

Figure 10 illustrates a schematic view, partially in section, of the exemplary embodiment shown in Figure 9, where the filter basket is folded down.

And Figure 11 illustrates a schematic representation of an exemplary embodiment of the invention in which the filter system according to the invention is positioned within the aorta of a patient.

With reference to the drawings, in which Figure 1 shows a sectional side view of a distal end of a guidewire 160 with a filter membrane 170 attached thereto. Figure 1 shows guidewire 160 with a soft, "flexible" tip 162 that can be shaped at its distal end that provides flexibility and maneuverability to guidewire 160. The filter membrane in Figure 1 illustrated in an open position.

Guide wire 160 comprises a core wire 164, extending into flexible tip 162, and a sheath 166. Filter membrane 170 is supported by a basket 169 comprising two or more wires 168 of the filter basket having ends distals 172 and proximal ends 174. The distal ends 172 of the basket wires 168 are secured by a distal opaque radio marker or grip band 176, or other appropriate means, to the core wire 164, and the proximal ends 174 of the basket wires 168 are secured to the band. 178 grip or proximal opaque radio marker, which can be slid over core wire 164, optionally3

ES 2 249 686 T3 te with a polymeric sleeve, such as polyimide or metallic between the core wire 164 and the proximal ends 174. Preferably, the proximal marker 178 is attached to the core wire 164 and a distal marker 176, with a sleeve polymeric or metallic that is slidable on core wire 164.

The flow of blood in Figure 1 is toward the distal end of guidewire 160. As such, the force of the blood flow pushes the deployed filter membrane 170 and helps to hold the filter membrane 170 in the deployed position.

A sheath member 180 is attached to the distal end of sheath 166, with sheath member 180 having a lumen 182 of sufficient diameter and length to receive or slide over proximal marker 178. Sheath 166 and sheath member 180 may be also separate pieces joined together or a continuous and integral structure. Sheath 166 and sheath member 180 are made of a low friction polymeric material, preferably polytetrafluoroethylene, polyethylene, nylon, or polyurethane.

Filter membrane 170 may comprise a number of different metallic and non-metallic permeable membranes with sufficient porosity to facilitate blood flow, but with sufficient small openings to capture embolism. The membrane filter 170 is preferably attached at least in its distal portion 184 to the core wire 164 and / or to the distal ends 172 of the basket wires and, optionally, to the basket wires 168. The remainder of the filter membrane 170 may be unfixed or, preferably, attached to the wires of the basket 168, using an appropriate adhesive. Preferably, the wires of the basket 168 are encapsulated in the membrane 170.

Basket 169 may be somewhat cylindrical in its middle with tapered, tapered proximal portions. Alternatively, the basket 169 may be slightly spherical, optionally with a flat, cylindrical middle portion. Preferably, the basket 169 has a diameter of a length of from about 5 to about 40 mm and from about 2 to about 30 mm, or from about 2 to about 20 mm, at its widest part.

The proximal end of sheath 180 is attached to a control handle or torque device 186 of the guidewire. The control handle 186 has an opening 188 for the core wire 164, so that the sheath 180 can be slidably moved over the core wire 164. For example, when the sheath 180 is moved distally toward the wires 168 of the basket, the filter membrane 170 collapses. In addition, there may be cases where sheath 180 is removed proximally so that other catheters or cardiovascular instruments can be inserted over core wire 164. Control handle 186, which functions as a torque device, also functions primarily to lock sheath 180 from core wire 164 during insertion.

There are a number of known commercially available guide wire torque devices that may be modified to function as a control handle 186 and the modification includes, but is not limited to, providing a slightly larger central lumen.

In Figure 2, sheath 166 and sheath member 180 are shown distally advanced so that the basket wires 168 and filter member 170 are bent against the core wire 164. The distal end 192 of the sheath member 180 may optionally be slightly tapered to provide a better profile for insertion.

In an exemplary embodiment of the present invention, as shown in Figure 3, the filter membrane 170 comprises a polymeric material, such as polyurethane or a silicone elastomer having openings or holes 190 of varying diameter. Alternatively, the filter membrane may comprise woven or non-woven meshes, such as those used in known hemodialysis filters or filters of heart-lung bypass machines. Suitable materials include physiologically acceptable metals or alloys or polymers. The openings or holes 190 may be made in the material by laser drilling or other appropriate processes, or they may be natural openings in the material itself.

The holes 190 of the filter membrane 170, one drawing of which is seen in Figure 3, are preferably only in the conical portion of the filter membrane 170. The holes 190 may vary between about 20 to about 300 microns in diameter, and their diameters may vary from one to the other. Holes 190 may further comprise fibers attached to the circumference of holes 190, which may serve to increase the capture of embolism material. The vertical spacing of rows of holes 190 may be approximately 1.2 to 1.4 times the diameter of the hole and the center-to-center diameter of the holes 190 may vary from approximately 1.4 to 1.6 times the diameter of the hole. , or in an exemplary embodiment, the vertical and horizontal spacing of the holes is such that the center-to-center spacing of the holes varies from about 1.2 to 2.0 times the diameter of the holes. Preferably, the open area of ​​the holes 190 represents from about 10 to 50%, more preferably from about 10 to 40%, of the filter surface. Alternatively, the holes may be spaced non-reportably apart. The mesh should have holes that are large enough to block and capture any micro- and macroembolic particles that may flow downstream from the site where the stenosis or other problem is being treated, but large enough that blood flow is not impeded. The mesh used in the filter device of the present invention may have a hole size of from about 20 to about 300 microns, preferably from 50 to about 150 microns. Furthermore, the size of the filter membrane 170 is such that it allows a firm fit between the filter membrane 170 and an arterial wall. The diameter of the filter membrane 170 will be directly related to the artery being treated, with typical diameters ranging from about 2 to about 40mm, more preferably up to about 20mm.

Referring again to Figures 1 and 2, the basket wires 168 comprise an appropriate physiologically acceptable metal. Stainless steel or nitinol in are considered preferred, although titanium or other metal alloys may be used.

ES 2 249 686 T3

The core wire 164, illustrated in detail in Figure 4, where the proximal and intermediate portions 200 and 202 have a substantially uniform diameter and subsequently the distal portion 204 tapers to a distal point 206. In reality, the distal portion 204 could taper evenly or, more preferably, non-reportably, as shown in Figure 4. A core wire 164 typically has a length of about 250 to 300 cm, with an initial diameter of about 0.23 to 0.97 mm, preferably about 0.36 to 0.46 mm. Distal section 204 is typically about 8-10 cm. With a diameter tapering from about 25 to 127 microns, core wire 164 may optionally have a thin polymeric coating 207 to reduce friction. Preferably, distal point 206 is a flattened solid cylinder, as shown in Figures 4 and 5.

Referring again to FIG. 1, flexible tip 162 preferably comprises a radiopaque coil spring 210 that is fixedly attached, for example by welding, brazing, or soldering, to distal point 206 and optionally to attachment point 208. Optionally, coil spring 210 may have a polymeric or lubricant coating 212.

Figure 6 depicts an alternative design of the filter system of the present invention, in which the wires of the basket 220 are formed in a substantially helical configuration. The filter member 222 covers or encompasses the distal portion of the basket wires 220 and the proximal and distal portions of the basket wires 220 are secured by a proximal radiopaque marking band or clamp 224 and a radio-opaque marking band or clamp 226. distal, respectively. Markers 224 and 226 are attached to or slid onto core wire 228, in the manner described above. Preferably, there are between 4 and 8 wires from basket 220, each rotated from about 45 to about 360 degrees.

Additional embodiments of the present invention are illustrated in Figures 7 and 8. The schematic representation in Figure 7 depicts a filter membrane 280 supported by tie wires 282. The distal ends 284 of tie wires 282 are attached to the distal portion of a tubular member 286. A removable core wire 290 extends through a lumen 292 in tubular member 286 to a distal flexible section 294, where a coil spring 296 surrounds distal portion 298 of guidewire 290 and is attached to distal portion 300. There is a attachment point 302 of solder material or other suitable material on the distal portion of the coil spring 296, where the distal portion 304 of the sheath member 306 is also attached to the core wire 290. The lumen 308 of the sheath member 306 is large enough that the core wire 290 is pulled proximally, or the tubular member 286 is advanced distally, the distal ends 284 of the tie wires 282 move within the lumen 308 and they break down the filter membrane 280.

The removable core wire 250 of the structure shown in Figure 8 comprises a flexible tip 252 where a helical spring 254 encompasses the distal portion 256 of the core wire 250 with a basket wire structure composed of two or more basket wires 258 supporting a filter membrane 260 in the distal portion 262 of the basket frame. The distal ends 264 of the wires of the basket 258 are encompassed by the band or clamp 266 or radio-opaque marker that is fixed to the core wire 250 and to the coil spring 254. The proximal ends 268 of the wires of the basket 258 are fixed to the distal portion of a sheath 270 surrounding core wire 250. Sheath 270 slidably moves on core wire 250 so that when sheath 270 is pulled proximally into core wire 250, filter membrane 250 collapses.

In FIG. 9, a basket 320 comprising 4 to 8 tie wires 322 is secured by a distally attached collar 324 and a proximally slidable collar 326. In the ring 326 it is slidable over the core wire 328. The filter membrane 330 is fixed or disposed on the basket 320, the proximal section 332 of the membrane 330 being open to flow, represented by arrows 334. The distal part 336 of membrane 330 has a proximally extending conical shape 340. The filter may be deployed by, for example, a sheath or tube attached to proximally slidable clamp band 326. The design is intended for embolism perfusion and harvesting. For example, as more emboli are collected, they are collected in the outer areas of the filter, leaving the holes open for perfusion.

The membrane 330 preferably tends holes only in the distal section 336/340, said holes being arranged in the manner described above. It is believed that under substantially normal laminar flow conditions debris or emboli 342 will tend to collect in annular recess 344.

To close and capture emboli, as shown in Figure 10, a slidable ring 326 is moved proximally to collapse basket 320 and membrane 330. This may be done as for example with a sheath 350 or a fixed tubular member or other. instrument that is preferably slidable on the core wire.

The wires, membranes, and other materials in this exemplary embodiment are consistent with those described above.

In the embodiment of the invention shown in Figure 11, a hose 360 ​​is attached to a cardiopulmonary bypass introducer member 362 that is disposed between, and sealably connected, to a blood vessel of a patient, such as the aorta 364. Introducer member 362 comprises a housing 366 with a flexible or rigid flange 368, a distal member 370, and a proximal connecting member 372. Housing 366 comprises at least two lumens, one of which 374 is in fluid communication with lumen 376 of hose 360. Another lumen 378 extends from a port 380 in Y-shaped connector 382 to a distal opening 384 at a distal surface 386 of distal member 370. Lumen 374 terminates its distal opening 388 at distal surface 386.

The lumen 378 preferably comprises a rigid or quasi-rigid sheath 390 that is sealably connected to port 380 by an O-ring 392 or with a comparable sealing member and that extends distally, for example, from about 2 to about 20 cm, from flange dis5

ES 2 249 686 T3 tal 368. A filter system 394, as described in detail above, is inserted through the sheath 396 and positioned downstream of the aorta 364. The filter system 394 may be operatively connected by medium of a guide wire 398 to a handle. The filter system with the captured embolism can be collapsed by pulling the filter system 394 proximally so that the struts 400 contact the distal end 402 of the sheath 386.