JP2001293084A - Intravascular filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an intravascular filter capable of thoroughly collecting the accumulated ablated pieces of embolus without blocking blood flow and capable of being inserted into a slender blood vessel, in an expansion treatment of the constricted part of a blood vessel. SOLUTION: A flexible shape memory alloy wire which has a straight shape at a temperature lower than a blood flow temperature in a blood vessel is inserted into a filtration bag being made of a flexible filtration film and having an opening at one end, and the opening of the filtration bag is bonded to the rear part of the shape memory alloy wire. The shape memory alloy wire is subjected to shape memory treatment at the blood flow temperature as a transformation point so that the bonded part of the opening of the filtration bag may be transformed into a toroidal opening line in order to expand the opening of the filtration bag so as to form a circle to contact with the inner wall of a blood vessel, and so that at least the front part from the toroidal opening line may be transformed into a plurality of toroidal holding lines which stretch so as to be tunnel like in order to hold the filtration bag at a predetermined position with it abutted on the blood vessel inner wall. The filtration film of the filtration bag allows blood corpuscles to pass through without damaging them and does not allow delated pieces of the embolus which are so large that they may cause an infarct in a peripheral blood vessel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to the treatment of vascular narrowing due to the accumulation of emboli such as fat emboli and thrombus in blood vessels. It relates to an intravascular filter for preventing the danger of causing it.

[0002]

2. Description of the Related Art For example, when a balloon catheter is inserted into a stenosis part of a blood vessel and the balloon is inflated to perform dilatation treatment of the stenosis part, emboli such as fat emboli and thrombus which accumulate on the stenosis part may cause blood flow. If the emboli are separated and left undisturbed, the flakes of the embolus may flow along the blood flow to the periphery of the blood vessel, causing a serious danger of infarction of the peripheral blood vessels.

Therefore, in order to prevent the above danger, conventionally, another balloon is inflated at an appropriate position on the downstream side of the blood flow from the blood vessel constriction to block the inside of the blood vessel. The method of blocking the circulation to the peripheral blood vessels and sucking the embolus exfoliated piece through the catheter after the treatment was adopted. However, in this method, the peripheral blood vessels are in an ischemic state by the block balloon, and thus the stenosis dilation treatment is performed. Has to be completed in a short time.

Further, instead of the block balloon of the above example, a bundle of several shape memory alloy wires is subjected to a shape memory process in advance so as to transform into a basket-shaped filter in which each alloy wire is interlaced, and this alloy wire bundle is used. A method has been proposed in which a filter is transformed into a basket-type filter at a predetermined position in a blood vessel and blood is passed through the filter, but the embolus strip is collected as a filter in the filter. Can hardly be recovered, and in order to guide several alloy wires through the catheter to a predetermined position, the catheter must be considerably thick, so that it can be used in a thin blood vessel. In addition, there is a danger of causing complications, and there is a problem that it becomes difficult to pass through a catheter at a site where a curve of a blood vessel is tight due to arteriosclerosis or the like.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an intravascular filter capable of sufficiently recovering an embolus detachment piece and accommodating it in a catheter and introducing it into a thin blood vessel. I do.

[0006]

As a means for achieving the above object, the present invention provides a flexible shape memory alloy wire which is linear at a temperature lower than the blood flow temperature in a blood vessel and comprises a flexible filter membrane. One end of the filter bag is inserted into the filter bag having an opening from the opening, and the opening of the filter bag is joined to the rear portion of the shape memory alloy wire. In order to expand the opening of the filter bag into a circular shape in contact with the inner wall of the blood vessel, the joined portion of the opening of the filter bag is in the annular opening line, and the filter bag is in contact with the inner wall of the blood vessel to hold the filter bag in a predetermined position from the annular opening line. At least the anterior portion is shape-memory treated so as to be transformed into a plurality of annular holding lines continuous in a tunnel shape, and the filter membrane of the filter bag can pass through without breaking blood cells and cause infarction in peripheral blood vessels. Emboli stripped And it shall not pass through the piece, we propose a blood vessel filter.

As the above-mentioned "shape memory alloy wire" in the present invention, a nickel-titanium alloy wire, a nickel-aluminum alloy wire, and various other wires are used, and the thickness is appropriately selected according to the application. However, the diameter is generally 0.025 to 0.5 mm. As the "filtration membrane", a net of an ultrafine synthetic filament, a perforated film of synthetic resin or rubber, a nonwoven fabric of an ultrafine synthetic fiber, an ultrafiltration membrane and other various materials are used.

Regarding the specific size of the mesh or the permeation hole of the filter membrane, the size of red blood cells is usually 7 to 10 microns or less (white blood cells are deformable and can be considered to be red blood cells or less). It has been reported that the minimum size of an embolus strip that flows to the periphery during dilation of a vascular constriction is 50 to 100 microns. Therefore, the mesh or permeation hole of the filter membrane is theoretically larger than 10 microns of red blood cells. The range is smaller than 50 μm. But,
In general, red blood cells may be broken when passing through a non-wide perforation hole. Therefore, in order to allow for safe passage and to sufficiently capture dangerous embolus detachment pieces, the diameter is preferably about 20 to 40 microns as an example.

Further, the "annular opening line" which is transformed from the shape memory alloy wire includes a wire of one spiral in a spiral winding and one ring-shaped wire. The “annular holding wire” includes a plurality of continuous spiral windings having substantially the same diameter and a plurality of continuous ring-shaped wires having substantially one diameter.

As a specific modification of the shape memory alloy wire, the above-mentioned "annular opening wire" is made into a single spiral wire, and subsequently, the "annular holding wire" is made into a spiral multiple winding wire or a plurality of ring-shaped wires. There is an example or an example in which the “annular opening line” is one ring-shaped line, and the “annular holding line” is subsequently a plurality of spiral windings or a plurality of ring-shaped lines. Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, a front end of an operation line (2) made of a flexible and elongated steel wire has a blood flow temperature (32) in a blood vessel.
(° C. or more), a flexible, shape-memory alloy wire (3) that is linear at a lower temperature is connected in a line, and the alloy wire (3)
With the transformation point at 32 ° C., as shown in FIG. 3 (a), the portion (P) at the rear of the annular opening line is wound into one spiral.
Continuing with that, the shape holding process is performed so that the predetermined portion (Q) of the annular holding wire from the first end to the front end is transformed into the three spirals having the same diameter as the one spiral and the alloy wire (3 ) Is inserted through the opening (6) into a vertically long filtration bag (4) (FIG. 2 (b)) having an opening (6) consisting of a flexible net filter membrane (5) having a mesh of about 40 microns, As shown in FIG. 3 (c), the semi-rim of the edge of the opening (6) of the filter bag (4) is joined to the annular opening line scheduled portion (P) of the alloy wire (3). Thus, an intravascular filter (1) before metamorphosis is formed.

[0012] In this case, the length (P) of the predetermined annular opening line of the alloy wire (3) is equal to the length of the opening (6) of the filter bag (4).
It is designed to almost match the half rim of the. (7) is a pressing piece provided at the front end of the alloy wire (3). The length of the filter bag (4) is designed such that when the alloy wire (3) is inserted, the entire alloy wire (3) can be included in a straight line.

A filter (1) as shown in FIG.
Is heated to 32 ° C., the predetermined annular opening (P) of the shape memory alloy wire (3) is transformed into a single spiral spiral opening (P ′), and as shown in FIG. At the same time, the half edge of the opening (6) of the filter bag (4) is spirally expanded and the remaining free half edge is shirred (8).
In addition, the opening line (P ') is moved while the predetermined portion (Q) of the annular holding line is transformed into a triple spiral annular holding line (Q') continuous in a three-turn spiral shape in the filter bag (4). The rear part of the filter bag (4) is expanded in a cylindrical shape, and a half of the bag (4) corresponding to the shirring (8) is bumped as a surplus part (9).

If the shirring (8) is formed in the filter bag (4) during the transformation, there is a possibility that the embolus may pass through the shirring (8). In order to prevent this, for example, another shape memory alloy wire is joined to the rim of the shirring (8), and the alloy wire uses the blood flow temperature as a transformation point to form the shirring (8) portion. It is advisable to take appropriate measures such as closing the rim of the device.

In another embodiment shown in FIG. 2, at a temperature lower than the blood flow temperature, as shown in FIG. 2 (a), the predetermined annular opening line (Pa) of the shape memory alloy wire (3a) is formed by a pair of wires. Are connected to each other at a straight line, and the annular holding line portion (Qa) is a straight line having the same dimensions as above.
Two split lines are connected in a line, and at the blood flow temperature, as shown in FIG.
A ring-shaped annular opening line (P
a ′), the above-mentioned scheduled portion (Qa) is transformed into a double ring-shaped annular holding line (Qa ′) in which the two halves are each opened in a circle and both circles are continuous in a tunnel shape. Shape memory processing.

[0016] Such an alloy wire (3a) is passed through a through hole of about 20
A microfiber flexible ultrafiltration membrane (5a) is inserted into a filtration bag (4a) composed of a filtration membrane (5a), and the entire edge of the opening (6a) of the filtration bag (4a) is placed in the same manner as in FIG. As described above, the pre-transformation endovascular filter (1) is obtained by joining the above-mentioned alloy wire (3a) to the halved line of the predetermined portion (Pa) of the annular opening line, with other structures being substantially the same as the above example. .

As an example, an example in which dilation treatment of a vascular stenosis is performed using the intravascular filter (1a) shown in FIG. 2 will be described. In FIG. 3 (a), a guide wire (D) is inserted into a narrow portion (C) formed by an embolus (B) in a blood vessel (A), and the wire (D) is used as a guide for a flexible filter supply catheter. (E) is inserted to a point slightly beyond the stenosis (C).

After the wire (D) is pulled out, the pre-transformation filter (1a) shown in FIG. 2C is inserted into the catheter E as shown in FIG. Push forward. In the meantime, preferably, for example, physiological saline or the like cooled below the transformation point (32 ° C.) is sent into the catheter (E) to suppress the transformation of the shape memory alloy wire (3a).

When the filter (1a) is pushed into the bloodstream from the tip of the catheter (E), the filter (1a) is transformed as shown in FIG. Expands the opening (6a) of the filter bag (4a) in a circular shape and abuts on the inner wall of the blood vessel (A), and the double ring-shaped annular holding line (Qa ') similarly covers the rear part of the filter bag (4a). The filter bag (4a) expands in a circular shape and abuts on the inner wall of the blood vessel, so that the opening line (Pa ') and the holding line (Qa') are formed.
Is held in place against the blood flow, and the holding line (Q
a ') prevents the opening line (Pa') from falling down due to the blood flow and supports the opening (6a) of the filter bag in a normal posture.

In this state, the catheter (E) is pulled out, and instead, the operation line (2a) of the filter (1a) is used as a guide for the balloon catheter (F) as shown in FIG.
Is inserted, the balloon (G) at the distal end is advanced to the stenosis part (C), and then the balloon (G) is inflated to expand the stenosis part as shown in FIG.

After expansion, as shown in FIG.
When contracted and pulled out, a considerable amount of the accumulated embolus (B) is peeled off and flows with the blood flow into the filter bag (4a), where the blood passes through the filter membrane (5a), but the embolus is removed. (B) The peeled pieces are collected as filter residue in the filter bag (4a).

Next, using the operation line (2a) of the filter (1a) as a guide, a flexible delivery catheter (H), which is slightly thicker than the catheter (E), is inserted. As described above, the operation line (2a) is pulled to draw the filter bag (4a) containing the peeled pieces into the catheter (H), and is pulled out together with the catheter (H).

As still another embodiment of the intravascular filter of the present invention, before transformation, a front end portion of a linear shape memory alloy wire inserted into the filtration bag is slidably penetrated through the front end of the filtration bag. The guide line can be protruded from the front end of the filter supply catheter so as to be used as guide means when the filter is inserted into a predetermined position.

[0024]

According to the blood vessel filter of the present invention, it can be easily inserted into a thin blood vessel or a blood vessel which is bent due to arteriosclerosis or the like, and the blood can freely pass through the filter bag after transformation. However, large embolus strips that may cause infarction in peripheral blood vessels can be collected as a filter, so that by installing the filter in the blood vessel, the treatment of the vascular stenosis is sufficiently performed over time. Will be able to do it. Moreover, in the intravascular filter of the present invention, when the shape memory alloy wire is transformed in the blood vessel, the annular opening line and the annular holding line expand the filter bag into a circular shape and abut on the inner wall of the blood vessel, whereby the filtration is performed. While holding the bag in place against the blood flow, the annular holding line is supported in a substantially upright position so that the annular opening line does not fall down, so that the embolus detachment piece can be reliably taken up and collected. .

[Brief description of the drawings]

FIG. 1 is a front view of a part of a shape memory alloy wire used in an embodiment of the present invention. (B) It is a front view of the filtration bag used for this example. (C) A partially omitted front view of the intravascular filter of the present example. (D) Slope view of the intravascular filter after transformation.

FIG. 2 is a front view of a shape memory alloy wire used in another embodiment of the present invention. (B) It is a front view of the filtration bag used for this example. (C) It is a front view of the intravascular filter of this example. (D) Slope view of the intravascular filter after transformation. (E) A schematic slant view of the shape memory alloy wire after transformation.

FIG. 3 is a schematic cross-sectional view of an example used for treatment of a vascular stenosis, in which (a) a filter supply catheter is inserted. (B) It is an approximate line sectional view at the time of supply of an intravascular filter. (C) It is an approximate line sectional view in the state where an intravascular filter was transformed. (D) A schematic cross-sectional view in a state where a balloon catheter is inserted. (E) It is an approximate line sectional view in the state where a balloon was inflated. (F) It is an approximate line sectional view at the time of collection of an embolus separation piece. (G) A schematic cross-sectional view when the filter bag is taken out.

[Explanation of symbols]

 1, 1a Intravascular filter 3, 3a Shape memory alloy wire 4, 4a Filtration bag 5, 5a Filter membrane 6, 6a Opening P ', Pa' Annular opening line Q ', Qa' Annular holding line A, Aa blood vessel

Continued on the front page F term (reference) 4C060 MM25 4C077 BB02 FF04 KK06 KK11 NN01 4D006 GA06 HA21 JA30A JA70A MA02 MA22 MA40 PB09 PB70 PC41 4D064 AA29 BQ02

Claims (1)

[Claims] 1. A flexible shape memory alloy wire, which is linear at a temperature lower than the blood flow temperature in a blood vessel, is inserted into a filter bag having one end opening made of a flexible filter from the opening, and
The opening of the filter bag is joined to the rear of the shape memory alloy wire, and the shape memory alloy wire is used to expand the opening of the filter bag into a circular shape in contact with the inner wall of a blood vessel with the blood flow temperature as a transformation point. A plurality of annular holding portions where at least the front portion from the annular opening line is continuous in a tunnel shape so that the joined portion of the filter bag opening portion is in the annular opening line and the filter bag is in contact with the inner wall of the blood vessel and is held at a predetermined position. The filter membrane of the filter bag passes through without breaking blood cells and does not pass through embolus strips of a size that may cause infarction in peripheral blood vessels. A blood vessel filter.