This invention relates to an active capillary capable of being inserted into a body cavity, for example a blood vessel, for use as an active catheter or guide wire in carrying out diagnosis or minimally invasive surgery.
In recent years, minimally invasive surgery has been widely performed to diagnose and treat the affected part in the body without incising the living body on a large scale. Such minimally invasive surgery includes endoscopic surgery comprising inserting a tool or instrument through an already existing opening or pore such as the oral cavity, large intestine or urethra, and keyhole surgery comprising making a minimal hole in a living body tissue for inserting a tool or instrument through the hole.
With the progress in micromachining technology, various microactive mechanisms have been tried to freely control, from the outside, the flexional movement of a medical catheter or guide wire inserted into a blood vessel or a tubular tissue of the living body.
For example, liver cell carcinoma is a target to be treated using a catheter. In the case of a hepatic tumor 20 fed with nutrients by an artery 40, as shown in
Further, on the occasion of insertion of a catheter or guide wire into a cerebral blood vessel branching at an angle greater than 90 degrees, the insertion becomes difficult or even impossible and therefore no successful treatment can be given. In this instance, too, a catheter having flexion mechanisms is desired. However, the conventional active catheters cannot be applied to peripheral blood vessels which are of small diameter.
In the treatment of cerebral aneurysm, the prior art treatment comprises loading a thin metal wire 65 into the aneurysm 70 by means of a manual catheter 60, as shown, for example, in
Meanwhile, Patent Document 1, for instance, describes a prior art active catheter. In this instance, an active catheter is proposed which comprises a plurality of shape memory alloy actuators disposed around an inside tube and the shape memory alloy actuators are electrically heated for flexion.
Such actuators as described in this Patent Document 1 and to be rendered flexible by feeding electricity to the shape memory alloy are indeed thought to be effective in minimally invasive treatment in relatively large diameter blood vessels such as aortas. However, actuator insertion, wiring for electricity feeding and packaging for insulation and waterproofing, among others, make the structure complicated and, accordingly, it is difficult to reduce the diameter.
In Patent Document 2, there is proposed a balloon for medical tubes which is flexible as a result of partial crosslinking treatment in the peripheral direction of the balloon for medical tubes to modify the stretchability distribution.
Such a balloon for medical tubes as shown in Patent Document 2, the flexion of which is controlled by the pressure resulting from pouring a liquid, does not need any particular actuator or any lead wire for feeding electricity but can be made thin to a certain extent although a fluid flow channel for expanding the balloon is needed. However, the balloon expands outwardly on the occasion of flexion and, therefore, the use thereof in a narrow blood vessel is restricted and it is difficult to bend the same with a small radius of curvature.
It is an object of the present invention to provide an active capillary capable of being used in minimally invasive test and treatment within the body and capable of being reduced in diameter with ease.
To accomplish the above object, the present invention provides an active capillary characterized in that it has a double structure comprising a first elastic tube having, at that part thereof to be bent, a plurality of grooves (crenae) with joints left so as to connect the grooves and a film-made second tube and in that the second tube is deformed and the desired flexion is thereby attained by changing the pressure of a fluid within the capillary.
The active capillary may have a constitution such that the second tube is outside the first tube, the front end of the second tube is open, the fluid is a liquid and, when a negative pressure is applied to the liquid, the second tube end works as a valve and is closed.
This valve can be realized by the front end portion of the second tube being in front of the front end portion of the first tube and the front end portion of the second tube working as a valve, or by one of the grooves of the first tube having a greater pitch and the second tube portion corresponding to that groove greater in pitch working as a valve upon application of a negative pressure to the liquid.
A constitution such that the second tube is integrated in close contact with the first tube and the front end of the first and/or second tube is closed may also be employed. In this case, flexion can be attained by applying a negative or positive pressure to the fluid.
Now, referring to the drawings, some typical modes of embodiment of the invention are described.
The structure of an exemplary mode of embodiment of the invention is shown in
In an example of the method of cutting grooves (crenae), the cutting can be carried out by inserting a piano wire into an SEA tube with an outside diameter of 0.88 mm and an inside diameter of 0.75 mm, fixing the whole on a stage, and cutting grooves or crenae using a femtosecond laser while feeding the whole in the axial and rotational directions. The grooves or crenae can be cut by etching as well.
The tube 100 having the structure shown in
The active catheter thus manufactured, when suctioned via a polymer tube attached to the rear end of the flexion mechanisms shown, is bent as shown in
Flexion movements can be realized in the above manner. Physiological saline is used since it is harmless even if it enters the living body through the opening. Any other liquid may be used in lieu of physiological saline for pressure application to the active capillary provided that it is harmless to the living body.
In this way, the Ti—Ni superelastic alloy (SEA) tube is covered with the silicone rubber tube in an open state in the active capillary having the structure shown in
Since the active capillary has a hollow structure and the function thereof as a catheter is thereby secured, the capillary can be used as a microcatheter for infusion of a contrast medium according to need or for passing a microtool for treatment therethrough after arrival at the affected part.
<Another Catheter Structure Example>
A microcatheter structure example is shown in
Like
In the case of the catheter shown in
This structure, too, has openings and therefore the function thereof as a catheter is secured.
While, in
Such a double structure is required at least within the region from the bending part to the front end portion of the catheter.
<Active Guide Wire>
The structure of an active capillary functioning as an active guide wire 300 is shown in
The structure shown in
In the case of the guide wire 300 having such structure, flexion is caused by applying a positive pressure or negative pressure to the inside physiological saline to expand or inwardly depress the silicone rubber tube at that portion of the plurality of grooves (crenae). Upon removal of the pressure on physiological saline, the original morphology is restored.
The direction of flexion of the wrought part having a plurality of grooves (crenae) can be changed by applying a positive pressure (cf.
While, in
While, in
<Morphology of Joints Connecting Grooves (Crenae)>
The flexibility of the active capillary can be varied by changing the length and morphology of each joint connecting the grooves or crenae together in the Ti—Ni superelastic alloy (SEA) tube and enabling flexion of the active capillary. FIGS. 8(a) to 8(d) show four examples of the morphology of such joints for attaining various levels of flexibility without appreciably changing the pitch of grooves or crenae.
Number | Date | Country | Kind |
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2002-348580 | Nov 2002 | JP | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/JP03/14614 | 11/17/2003 | WO | 5/24/2005 |