GB2460444A

GB2460444A - A catheter having vibrating control or guide wires to reduce friction

Info

Publication number: GB2460444A
Application number: GB0809811A
Authority: GB
Inventors: Simon Cary Barnard; John Charles Cooke
Original assignee: COCATALYST Ltd
Current assignee: COCATALYST Ltd
Priority date: 2008-05-30
Filing date: 2008-05-30
Publication date: 2009-12-02
Also published as: GB0809811D0

Abstract

A medical or surgical device, intended to provide remote access to internal organs for diagnostic and therapeutic purposes, comprising: a catheter3and guide wire or wires4to facilitate introduction of the catheter3transluminally into a living being and control wires to operate the surgical instruments or diagnostic devices where the guide wire4and/or control wires are caused to vibrate in either an axial direction or transverse direction such that the frictional resistance to relative movement between the catheter3and the guide wires4and/or the control wires is significantly reduced. The vibration in the wires may be in the range 1 KHz to 10 MHz and is preferably in the ultrasonic range.

Description

Field

The present invention relates to guide wires, catheters and elongate devices used in the vessels, ducts, and lumens of a living being, and more particularly to a system for facilitating the operation, delivery and exchange of such catheters, devices, and guide wires at various locations within the body of a living being.

Background

As will be appreciated by those skilled in the art, various medical procedures involve the use of catheters and guide wires that are inserted into various locations within a living being. By way of example, for the treatment of some vascular diseases, such as atherosclerosis, it is common practice to insert an instrument (e.g., catheter, guide wire, etc.) into a vessel to perform a procedure that reduces or eliminates a restriction or stenosis. Such procedures, known as percutaneous catheterization intervention (PCI), typically involve several steps. To begin, an initial puncture is created in a vessel that is typically remote from the stenosis. Next, a guide wire is inserted through the puncture and threaded into the vessel. A guiding catheter is then advanced in to the patients arteries. A guide wire is then advanced through the guiding catheter and, for the treatment of coronary disease, into the patients coronary arteries. The guide wire is manoeuvred by advancing and rotating the distal tip, which normally has an asymmetric "J' shape imposed on it to enable the selection of various branches of the coronary vasculature. Once the wire is in the desired position, a diagnostic or therapeutic catheter, which has a lumen or other means adapted to receive the guide wire, is then guided along the wire to the desired location.

In the course of a typical PCI, for example, an angioplasty procedure, the catheter has a distally mounted balloon that can be placed, in a deflated condition, within the stenosis, and then inflated to dilate the narrowed lumen of the blood vessel. Such balloon dilation therapy is generally referred to as percutaneous transluminal angioplasty (PTA). Percutaneous transluminal coronary angioplasty (PTCA) is used when the treatment is more specifically employed in vessels of the heart. PTCA is used to open coronary arteries that have been occluded by a build-up of cholesterol fats or atherosclerotic plaque. The balloon at the distal end of the catheter is inflated, causing the site of the stenosis to widen. In some cases, a stent, a cylindrically shaped device formed from wire(s) or a metal tube, is placed at the site of the restriction to act as a prosthesis that provides support to the body lumen. In addition to angioplasty and stealing procedures, other diagnostic and therapeutic procedures require the use of wires and catheters, such as drug delivery, embolic protection, angiography, atherectomy, imaging and other treatments known in the art.

During these procedures, the guide wire plays an important role in guiding the diagnostic or therapeutic device (e.g., catheter) to the desired location in the patients body. For example, one difficulty that can be encountered in the procedure is the inability to cross the lesion or stenosis with the distal end of the guide wire. This can be the result of a variety of situations, including a tight stenotic lesion with insufficient lumen patency to allow passage of a guide wire. In other instances, the vessel can be completely blocked as in the case of a chronic total occlusion (CTO). In cases such as these, the physician may need to utilize a different guide wire and thus replace an in-situ wire with another having different construction, structure or properties, e.g., floppy-tip design or shape, stiffness, etc. The need to withdraw an already placed guide wire also occurs when the distal tip of the guide wire needs to be reshaped to pass a blockage or navigate into the desired vessel. Because of this, there exists a need for the physician to be able to exchange guide wires while supporting a pre-positioned guide wire to facilitate crossing of a difficult lesion.

The manner in which the catheter interacts with the guide wire during the procedure can have significant impact on the timing, ease of use, and ultimate success of the procedure. In particular, high frictional resistance between the guide wire and the catheter can severely affect ease of insertion and withdrawal of the guide wire and the catheter. Similarly, the frictional resistance between the control wire(s) moving within the catheter and the catheter itself can reduce tactile feedback to the operator, especially when the catheter is long and has been required to follow a tortuous path as may be necessary in PTCA.

Brief Summary of the invention

Against this background, the object of the present invention is to eliminate or significantly reduce the level of friction encountered between the guide wire(s) and catheter and the control wire(s) and catheter. The inventive catheter system described in this document achieves a significant reduction in friction by means of a period action applied to the guide wire(s) and/or the control wire(s) within the catheter. More preferably, this periodic action is applied to achieve a resonant vibration within the guide wire(s) and/or control wire(s) within the catheter. Most preferably, the frequency of the periodic action is in the ultrasonic range (greater than 20 KHz). The periodic action within the guide wire(s) or control wire(s) is enabled either by direct mechanical connection to an electro-mechanical actuator (e.g. a piezo-electric device) or more preferably by excitation of the magnetostrictive material (e.g. Ni-Ti alloy, known as Nitinol) of the guide wire(s) and/or control wire(s) by means of an electro-magnetic field generated by a coil system surrounding the guide wire(s) and/or control wire(s) and positioned at the adistal end of the catheter. At lower frequencies of oscillation (1 KHz to KHz), the guide wire(s) and/or control wire(s) will be forced into a predominantly axial vibration.

At higher frequencies, (1 MHz to 10 MHz), dependent on their diameter, the guide wire(s) and/or control wire(s) will be forced into a predominantly transverse vibration. Most preferably, the catheter system will be excited using a combination of frequencies to excite vibration in both axes, to minimise friction between the guide wire(s) and/or the control wire(s) and the catheter.

It will be appreciated that the features mentioned above and those yet to be explained below may be used not only in the combination specified in each case, but also in other combinations or alone, without departing from the scope of the present invention as will be clear to a person skilled in the art.

Brief description of the drawings within the patent document Figure 1 shows a diagrammatic partial section view of the first configuration of the ultrasonically actuated guide wire arrangement, where the magnetostrictive wire material is excited by a fluctuating electromagnetic field at the adistal or proximal end of the catheter system. The diagram shows a partial, truncated view of the catheter and guide wire system without control wires where the ends of the guide wire have been omitted.

Figure 2 shows a diagrammatic partial section view of the second configuration of the of the ultrasonically actuated guide wire arrangement, where the wire is excited by direct mechanical contact between the wire and an electro-mechanical (e.g. piezo-electric) actuator at the adistal or proximal end of the catheter system. The diagram shows a partial, truncated view of the catheter and guide wire system without control wires where the ends of the guide wire have been omitted.

Figure 3 shows a diagrammatic partial section view of the first configuration of the ultrasonically actuated control wire arrangement, where the magnetostrictive wire material is excited by a fluctuating electromagnetic field at the adistal or proximal end of the catheter system. The diagram shows a partial, truncated view of the catheter and control wire system where the guide wires and end of the catheter have been omitted.

Figure 4 shows a diagrammatic partial section view of the second configuration of the of the ultrasonically actuated control wire arrangement, where the wire is excited by direct mechanical contact between the wire and an electro-mechanical (e.g. piezo-electric) actuator at the adistal or proximal end of the catheter system. The diagram shows a partial, truncated view of the catheter and control wire system where the guide wires and end of the catheter have been omitted.

Figure 5 shows a diagrammatic partial section view of a more complex ultrasonic actuation system comprising two electro-magnetic excitation coils and corresponding ultrasonic signal generation and amplification units; one for high frequency oscillation and one for lower frequency oscillation. The coils are configured to excite mechanical vibration in the magnetostrictive wire at the adistal end of the catheter system. The diagram shows a partial, truncated view of the catheter and guide wire system without control wires where the ends of the guide wire have been omitted.

Detailed description of the invention

A first embodiment of the novel catheter system according to the invention is shown in FIG. 1. The system consists of an ultrasonic signal generator and amplification unit 1, an electromagnetic coil 2 at the adistal or proximal end of the catheter system, arranged to surround the guide wire 4 and to create strong electromagnetic fields in the guide wire 4, a catheter tube 3, surrounding the guide wire 4. Within the guide wire 4 is a section of magnetostrictive material 5 such as Nitinol. The ultrasonic generator and amplifier 1, converts 50/60 Hz mains alternating current into an ultrasonic frequency oscillating electrical signal in the range 20 KHz to 10 MHz and amplifies it to a maximum power intensity of 100 Watts, creating a matching high frequency electromagnetic field in the coil 2 and exciting the section of magnetostrictive (e.g. Ni-Ti alloy such as Nitinol) material 5 within the guide wire 4. The resultant mechanical vibration of the guide wire 4 within the catheter tube 3 significantly reduces frictional resistance between the guide wire and the catheter due to the ultrasound-induced friction reduction effect.

A second embodiment of the novel catheter system according to the invention is shown in FIG. 2.

The system consists of an ultrasonic signal generator and amplification unit 1, an electro-mechanical transducer 6, at the adistal or proximal end of the catheter system and based on the piezo-electric principle, mechanically connected to the guide wire 8 by a ultrasonic horn 7. The guide wire 8 is surrounded by the catheter tube 3. The ultrasonic generator and amplifier 1, converts 50/60 Hz mains alternating current into an ultrasonic frequency oscillating electrical signal in the range 20 KHz to 10 MHz and amplifies it to a maximum power intensity of 100 Watts, creating a matching high frequency mechanical vibration in the transducer 6 and exciting the vibration in the ultrasonic horn 7 such that the guide wire 8 is forced into ultrasonic oscillation. The resultant mechanical vibration of the guide wire 8 within the catheter tube 3 significantly reduces frictional resistance between the guide wire and the catheter due to the ultrasound-induced friction reduction effect.

A third embodiment of the novel catheter system according to the invention is shown in FIG. 3. The system consists of an ultrasonic signal generator and amplification unit 11, an electromagnetic coil 12, at the adistal or proximal end of the catheter system, arranged to surround the control wire 9 and to create strong electromagnetic fields in the control wire 9, a catheter tube 3, surrounding the control wire 9. Within the control wire 9 is a section of magnetostrictive material 10 such as Nitinol.

The ultrasonic generator and amplifier 11, converts 50/60 Hz mains alternating current into an ultrasonic frequency oscillating electrical signal in the range 20 KHz to 10 MHz and amplifies it to a maximum power intensity of 100 Watts, creating a matching high frequency electromagnetic field in the coil 12 and exciting the section of magnetostrictive (e.g. Ni-Ti alloy such as Nitinol) material 10 within the control wire 9. The resultant mechanical vibration of the control wire 9 within the catheter tube 3 significantly reduces frictional resistance between the control wire and the catheter due to the ultrasound-induced friction reduction effect.

A forth embodiment of the novel catheter system according to the invention is shown in FIG. 4. The system consists of an ultrasonic signal generator and amplification unit 11, an electro-mechanical transducer 14, at the adistal or proximal end of the catheter system and based on the piezo-electric principle, mechanically connected to the control wire 13 by an ultrasonic horn 15. The control wire 13 is surrounded by the catheter tube 3. The ultrasonic generator and amplifier 11, converts 50/60 Hz mains alternating current into an ultrasonic frequency oscillating electrical signal in the range 20 KHz to 10 MHz and amplifies it to a maximum power intensity of 100 Watts, creating a matching high frequency mechanical vibration in the transducer 6 and exciting the vibration in the ultrasonic horn 15 such that the control wire 13 is forced into ultrasonic oscillation. The resultant mechanical vibration of the control wire 13 within the catheter tube 3 significantly reduces frictional resistance between the control wire and the catheter due to the ultrasound-induced friction reduction effect.

A fifth embodiment of the novel catheter system according to the invention is shown in FIG. 5. In this embodiment, there are two ultrasonic signal generation and amplification units; one unit 18, intended to generate high frequency ultrasound (1 to 10 MHz) and one unit intended to generate lower frequency ultrasound (20 KHz to 100 KHz). The high frequency ultrasonic signal generation and amplification unit 18, is configured to drive a coil 20, specifically designed to produce a high frequency oscillating electro-magnetic field. When this circuit is energised, the magnetostrictive element 17 (e.g. Ni-Ti alloy such as Nitinol) converts the electro-magnetic field oscillation into mechanical vibration throughout the wire 16. The high frequency oscillation is particularly suited to generate mechanical vibration in the transverse direction of the wire 16, significantly reducing frictional resistance between the wire 16 and the catheter tube 3 due to the ultrasound-induced friction reduction effect. The lower frequency ultrasonic signal generation and amplification unit 19, is configured to drive a coil 21, specifically designed to produce a lower frequency oscillating electro-magnetic field. When this circuit is energised, the magnetostrictive element 17 (e.g. Ni-Ti alloy such as Nitinol) converts the electro-magnetic field oscillation into mechanical vibration throughout the wire 16. The lower frequency oscillation is particularly suited to generate mechanical vibration in the axial direction of the wire 16, significantly reducing frictional resistance between the wire 16 and the catheter tube 3 due to the ultrasound-induced friction reduction effect and translating further along the wire than solely transverse vibration. In practice a combination of higher and lower frequency ultrasonic vibration will be used to create an optimal reduction in friction along the entire length of the wire and catheter system.

Claims

What we claim is: 1. A medical or surgical device, intended to provide remote access to internal organs for diagnostic and therapeutic purposes, comprising: a catheter and guide wire or wires to facilitate introduction of the catheter transluminally into a living being, characterised in that the guide wire or wires are caused to vibrate in either an axial direction or radial direction such that the frictional resistance to movement of the catheter relative to the guide wire or wires is reduced.
2. A medical or surgical device as described in claim 1 where the vibration in the guide wire or wires is in the frequency range 1 KHz to 10 MHz.
3. A medical or surgical device as described in claim 1 where the guide wire or wires is made, at least in part, of a magnetostrictive material and the ultrasonic vibration in the guide wire or wires is generated by means of an electromagnetic device or devices, exciting oscillation in the guide wire or wires by means of the magnetostrictive principle.
4. A medical or surgical device as described in claim 1 where the guide wire or wires is mechanically connected to an electro-mechanical device or devices, such as a piezo-electric device, exciting oscillation in the guide wire or wires.
5. A medical or surgical device, intended to provide remote access to internal organs for diagnostic and therapeutic purposes, comprising: a catheter with internal control wire or wires, translating mechanical movements at the adistal end of the catheter to instruments at the distal end of the device, and guide wire or wires, characterised in that the internal control wire or wires are caused to vibrate in either an axial or radial direction such that the frictional resistance to movement of the control wire or wires relative to the catheter is reduced.
6. A medical or surgical device as described in claim 5 where the vibration in the control wire or wires is in the frequency range 1 KHz to 10 MHz.
7. A medical or surgical device as described in claim 5 where the control wire or wires are made, at least in part, of a magnetostrictive material and the ultrasonic vibration in the control wires is generated by means of an electromagnetic device or devices, exciting oscillation in the control wire or wires by means of the magnetostrictive principle.
8. A medical or surgical device as described in claim 5 where the guide wire or wires is mechanically connected to an electro-mechanical device or devices, exciting oscillation in the control wire or wires.
9. A medical or surgical device as described in claim 5 where the guide wire or wires is mechanically connected to a piezo-electric device or devices, exciting oscillation in the control wire or wires.