A medical equipment as a dilator catheter, a micro catheter or an atherectomy catheter

The invention relates to a medical equipment used for a penetration or dilatation of an occlusive area or a stenotic area in a blood vessel.

A dilator catheter, a micro catheter (very thin in outer diameter) and an atherectomy catheter with an ablative tool have been used for penetration or dilatation of the occlusive area and the stenotic area in the blood vessel as shown by Japanese Laid-open Patent Application No. 7-265319.

The dilatation catheter and the micro catheter are crossed into the blood vessel by a pushing force with the assist of a guide catheter. When the occlusive area and the stenotic area are stiffened, only the guide catheter can disengage these areas upon forcibly pushing them against the diseased area. This makes it difficult for the related art catheters to creat the penetration and the dilatation against the diseased area. An atherectomy catheter, although it is appropriate to use for a hard and calcified area, is ineffective to pass over the soft vascular tissue.

Therefore, it is an object of the invention to overcome the above drawbacks, and provide a high quality medical equipment which is capable of positively creating penetration of a diseased area which resists a dilatation device to cross over after a guide wire has crossed through.

According to the invention there is provided a medical equipment (1, 5) including a hollow shaft body (2, 6) a cylindrical tip portion (3, 7) provided on a distal end of said hollow shaft body (2, 6), and a manipulative grip portion (4) connected to a proximal side portion of said hollow shaft (2, 6);    characterised in that at least one of an inner surface and an outer surface of said hollow shaft body (2, 6), and at least one of an inner surface and outer surface of said tip portion (3, 7) are provided with a screw-like concave or convex streak (75).

The structure is such that the tip portion makes it possible to positively create a penetration against a diseased area which resists a dilatation device to cross through after guide wire has crossed through. This also enables a manipulator to torsionally push the tip portion into the occlusive area in the blood vessel with a smooth manoeuverability.

Preferably the cylindrical tip portion is made of a radiopaque material, and is welded to the hollow shaft body.

Preferably the screw-like concave-convex streak of projection is defined along a plurality of helical winds, a lead length of which is greater than an outer diameter of the hollow shaft body.

Preferably a proximal side portion of the hollow shaft body has a portion smaller in yield strength than any parts of the hollow shaft body.

Preferably a proximal side portion of the hollow shaft body has a diameter-reduced portion diametrically or cross sectionally smaller than or equal to any parts of the hollow shaft body.

Preferably a manipulative grip portion of the hollow shaft body has a transparent portion which makes visible the diameter-reduced portion or a proximal side portion provided on the hollow shaft body to be smaller in yield strength than any parts of the hollow shaft body.

Preferred forms of the present invention are illustrated in the accompanying drawings in which: <ul id="ul0001" list-style="none" compact="compact"><li>Fig. 1 is a plan view of a medical equipment according to a first embodiment of the invention;</li><li>Fig. 2 is a latitudinal cross sectional view taken along the line A-A of Fig. 1;</li><li>Fig. 3 is a latitudinal cross sectional view taken along the line B-B of Fig. 1;</li><li>Fig. 4 is a latitudinal cross sectional view taken along the line C-C of Fig. 1;</li><li>Fig. 5 is a latitudinal cross sectional view taken along the line D-D of Fig. 1;</li><li>Fig. 6 is a latitudinal cross sectional view taken along the line E-E of Fig. 1;</li><li>Fig. 7 is a latitudinal cross sectional view taken along the line F-F of Fig. 1;</li><li>Fig. 8 is a longitudinal cross sectional view of a cylindrical tip portion;</li><li>Fig. 9 is a longitudinal cross sectional view of a main portion of the medical equipment;</li><li>Fig. 10 is an enlarged cross sectional view of the main portion of the medical equipment;</li><li>Fig. 11 is a plan view of a hollow shaft body;</li><li>Fig. 12 is a latitudinal cross sectional view taken along the line A-A of Fig. 11;</li><li>Fig. 13 is a latitudinal cross sectional view taken along the line B-B of Fig. 11;</li><li>Fig. 14 is a latitudinal cross sectional view taken along the line C-C of Fig. 11;</li><li>Fig. 15 is a plan view of a modified medical equipment;</li><li>Fig. 16 is a plan view of the medical equipment;</li><li>Fig. 17 is an enlarged plan view of a main portion of the medical equipment;</li><li>Fig. 18 is a plan view of a medical equipment according to a second embodiment of the invention;</li><li>Fig. 19 is a longitudinal cross sectional view of a main portion of the medical equipment;</li><li>Fig. 20 is a latitudinal cross sectional view taken along the line A-A of Fig. 18;</li><li>Fig. 21 is a latitudinal cross sectional view taken along the line B-B of Fig. 18;</li><li>Fig. 22 is an enlarged side elevational view of of the main portion of the medical equipment;</li><li>Fig. 23 is an enlarged cross sectional view of of a main portion of the medical equipment.</li></ul>

In the following description of the depicted embodiments, the same reference numerals are used for features of the same type.

Referring to Figs. 1 through 17 (except Fig. 15), a medical equipment 1 is provided according to a first embodiment of the invention is described below.

As shown in Figs. 1 through 7, the medical equipment 1 has a hollow shaft body 2 made of a single-wound or plurally wound line coil elements 21 to provide a high flexibility with the hollow shaft body 2. A cylindrical tip portion 3 is welded in one piece to a distal end of the hollow shaft body 2, while a manipulative grip 4 is connected to a proximal side portion of the hollow shaft body 2. The tip portion 3 is made of a radiopaque material to serve as a marker when using the medical equipment 1 displayed on an image monitor (not shown).

As shown in Figs. 11 through 14, the hollow shaft body 2 has eight coil line elements 21 made of a stainless steel metal. The coil line elements 21 are helically wound with its lead length, outer diameter and length dimension in turn as 1. 2 mm, 0.70 mm and approx. 1350 mm. A distal end portion of the hollow shaft body 2 has a diameter-reduced portion 22. at the distal end side defined by grinding an outer surface of the hollow shaft body 2. The diameter-reduced portion 22 measures 0.62 m in outer diameter, and has a straight portion 23 (10 mm in length) and a tapered portion 24 (150 mm in length). As a modification, the hollow shaft body 20 has the straight portion 23 (80 mm in length) and the tapered portion 24 (50 mm in length) as shown in Fig. 15.

It is effective that the hollow shaft body 2 is progressively decreased at its cross sectional area continuously or discontinuously as approaching its distal end portion. It is favorable that the metallic material used for the coil line elements 21 has a tensile strength of more than 120 kgf/mm² to insure a torque transmissibility. A bulge portion may be formed in a middle of the hollow shaft body 2. A convex-concave screw-like projecting streak may be defined on an outer surface of a cylindrical pipe (stainless steel tube), the coil line elements 21 may be made of a Ni-Ti based alloy.

A proximal rear portion of the hollow shaft body 2 has a diameter-reduced portion 25 at a rear side to be 0.62 mm in outer diameter and 85 mm in length as shown in Figs. 5-7. An outer diameter of the diameter-reduced portion 25 at the rear side is determined to be smaller than that of the diameter-reduced portion 22 at the distal end side. This is because a torsional buckling is preferentially induced on the diameter-reduced portion 25 at the proximal rear side. Upon achieving a good screwing efficiency, it is advantageous that the lead length of the coil line elements 21 is greater than the outer diameter of the tip portion 3. The hollow shaft body 2 may be made of a single coil wire tightly wound with no gap appeared between its coil line elements.

The tip portion 3 is in the form of a cylindrical platinum metal, and measures 0.62 mm in outer diameter and approx. 1.0 mm in length. An outer surface of the tip portion 3 inclines at a degree of 1/10 to have a tapered portion 31 to works as an ablative tool (gimlet) against the occlusive area and the stenostic area in the blood vessel. It is necessary for the tapered portion 31 to have a length more than half the entire length of the tip portion 3, and inclining at the rate of 1/9-1/12 inclusive. A concave-convex screw-like projecting streak (not shown) is provided on an inner surface or an outer surface of the tip portion 3. A lead length of the screw-like streak of projection is preferably greater than the outer diameter of the tip portion 3 in achieving a good screwing efficiency.

As shown in Figs. 6 and 9, the hollow shaft body 2 has a tube 26 (350 mm in length) coated along its axial direction extending from the proximal side portion to the diameter-reduced portion 25. A circular protector pipe 27 is firmly interfit into a rear section of the diameter-reduced portion 25. An angular pipe 28 is interfit into the protector pipe 27 at the proximal side portion as shown in Figs. 6, 7, 9 and 10.

In the proximity of a distal end of the tube 26 in which a distal end of the diameter-reduced portion 25 resides as shown in Fig. 9, a diametrically bulged cylinder 29 is placed in one piece to form a tranparent portion 10 so as to render the diameter-reduced portion 25 visible through the tranparent portion 10. It is to be noted that the tube 26 may be notched to formed a window section in which a transparent tube is placed to define the transparent portion 10 on the tube 26. The diameter-reduced portion 25 is visible through the transparent portion 10 with a clearance left to permit the torsional buckling inside the bulged cylinder 29.

As shown in Figs. 1 and 10, the manipulative grip 4 has a protector cylinder 41 and a cylindrical connector 43 in which a diameter-reduced cylinder 42 is interfit into a proximal rear end of the protector cylinder 41. An outer surface of the connector 43 has diametrically opposed fins F. The diameter-reduced cylinder 42 is interfit into an outer surface of the angular pipe 28 so that the manipulative grip 4 rotationally moves in unison with the rear portion of the hollow shaft body 2.

Upon navigating the medical equipment 1 in the blood vessel to ablate a diseased area (e.g., an occlusive area), the manipulative grip portion 4 controls the tip portion 3 to encounter the occlusive area in the coronary artery, and moving in such a way to provide pushing and torsional force with the hollow shaft body 2. The hollow shaft body 2, thus provided with the rotational force, exhibits a good screwing effect at contact points against the diseased area, the blood vessel or the guide device. Depending on the rotational direction of the manipulative grip 4, it is possible to screw the tip portion 3 of the medical equipment 1 into the diseased area, while at the same time, withdrawing the tip portion 3 from the diseased area. Even with no assist of the guide catheter, the manipulative grip 4 makes it possible to cross through the diseased area without forcing the manipulative grip 4 so as to permit a penetration and dilatation for the diseased area under the influence of the Dotter's effect.

The hollow shaft body 2 insures a favorable screwing effect with the increase of the helical pitch length, while the hollow shaft body 2 requires an appropriate tensile-resistant property for the coil line elements 21 to insure a good torque-transmissibility.

As the hollow shaft body 2 increases the flexibility, it becomes easy for the hollow shaft body 2 to follow the curved portion of the blood vessel. When the flexibility extends over the manipulative grip 4, the flexibility decreases the torque-transmissibility for the hollow shaft body 2. In order to avoid this situation, the diameter-reduced portion 22 is provided with the distal end side of the hollow shaft body 2 to progressively decrease its cross sectional area as shown in Figs. 3 and 8. The diameter-reduced portion 22 has a length (160 mm) corresponding to the area which reaches the curved portion when inserted into the curved portion of the blood vessel. This insures the flexibility for the distal end portion of the hollow shaft body 2, while at the same time, increasing the torque-transmissibility for the manipulative grip 4. It is favorable that the diameter-reduced portion 22 extends from 100 mm to 300 mm in length. Under the presence of straight portion 23, it is possible to facilitate the penetration of the diameter-reduced portion 22 into the diseased area.

Due to the tip portion 3 welded in one piece with the hollow shaft body 2, it is possible to insure the physical dimensions and characteristics for the hollow shaft body 2.

Due to the tip portion 3 which has the hollow structure and tapered portion 31 (inclined at the rate of 1/3), it is possible to positively insert the tip portion 3 into the occlusive tissue area in the blood vessel. During this process, a part of the occlusive tissue invades inside the tip portion 3 to enable the manipulator to smoothly penetrate the occlusive tissue area. With a bulged portion provided on the tip portion 3, it is possible to increase the Dotter's effect to favorably dilate the occlusive tissue area after crossing through the occlusive tissue area.

When the occlusive tissue area is stiffened, it may happen that the hollow shaft body 2 has the coil line elements 21 gotten loose or torsionally buckled. In a hollow shaft body 20 devoid of the diameter-reduced portion 25 as a modification form of the invention as as shown in Fig. 15, the torsional buckling likely occurs at the area corresponding to the straight portion 23, the tapered portion 24 and the diameter-reduced portion 25 of Figs. 11-14. When the torsional buckling occurs, it would be troublesome to withdraw the medical equipment 1 so as to put the safety at risk.

As shown in Figs. 16 and 17, the hollow shaft body 2 gets the diameter-reduced portion 25 preferentially buckled to prevent the distal end portion from being buckled inside the blood vessel so as to insure the safety. The transparent portion 10 makes it possible to get the manipulator visually recognize the torsional buckling happen so as to prevent the manipulator from gotten hurt due to fractions of the buckled hollow·shaft body 2.

With this embodiment, the screw thread of the hollow shaft portion is the undulation of the inside and/or outside surface of the stranded helical coil (21) in Figure 8. As regards the tip portion 3, there is also a thread on the inside or outside not illustrated, or the thread may be concave rather convex and projecting. This can introduce detached parts of vascular thrombi when drilling into the thrombi and can bring such parts outside when the device is withdrawn from this patient.

Figs. 18 through 23 show a second embodiment of the invention in which a medical equipment 5 has a tip portion 7 at a distal section of a hollow shaft body 6 while having a manipulative grip 8 at a proximal section of the hollow shaft body 6.

In this instance, the hollow shaft body 6 has a lower resin layer 62 and an upper resin layer 63. The lower resin layer 62 has a polyamide-based elastomer in which a stainless steel braid work 61 is embedded. The upper resin layer 63 has a polyamide-based elastomer coated over an outer surface of the lower resin layer 62. The hollow shaft body 6 measures 0.70 mm in outer diameter and 0.42 mm in inner diameter. The hollow shaft body 6 has a proximal rear end portion covered by a protector tube 64 to form a flexible elongation structure as a whole.

To the distal end of the hollow shaft body 6, a tip portion 7 is firmly connected which is made of a polyamide-based elastomer. The tip portion 7 has an inner diameter identical to that of the lower resin layer 62, and having an outer diameter identical to that of the upper resin layer 63. A rear end portion of the tip portion 7 has a thickness-reduced cylinder 74 interfit into an outer surface of a distal end of the lower resin layer 62 as shown in Fig. 19. It is practical to use an adhesive to secure the thickness-reduced cylinder 74 to the' distal end of the lower resin layer 62.

At the distal end of outer surface of the tip portion 7 and the hollow shaft body 6, a helical streak of a projection (projecting streak) 75 (0.05 mm in height) is formed with its pitch and lead length in turn as 0.5 mm and 1.0 mm. The streak may be concave.

As shown in Figs. 18 and 23, the manipulative grip 8 has a tapered protector cylinder 81 and a cylindrical connector 83 in which a diameter-reduced cylinder 82 is interfit into a proximal rear end of the protector cylinder 81. An outer surface of the connector 83 has the diametrically opposed fins F. The diameter-reduced cylinder 82 is interfit into an outer surface of the protector tube 64 through an adhesive layer 84 so that the manipulative grip 8 rotationally moves in unison with the proximal rear portion of the hollow shaft body 6.

In addition to that the medical equipment 5 according to the second embodiment of the invention works in the same way as the first embodiment has acted, the helical streak of the projection 75 enables the manipulator to torsionally push the tip portion 7 into the occlusive area in the blood vessel with a smooth maneuverability.