FR2582220A1 - LASER CATHETER GUIDED BY A WIRE - Google Patents

Abstract

WIRE GUIDED LASER CATHETER. THIS CATHETER IS CHARACTERIZED IN THAT IT INCLUDES MEANS DEFINING LIGHT 34 EXTENDING THE ENTIRE LENGTH OF THE CATHETER; MEANS 28 LOCATED AT THE CLOSE END OF THIS LIGHT TO ALLOW A COMMUNICATION OF FLUID AND THE INTRODUCTION OF A GUIDE WIRE; A CERTAIN NUMBER OF FLEXIBLE OPTICAL CONDUCTORS 42 HOUSED LONGITUDINALLY OF THE CATHETER, INSIDE THE WALL OF THE CATHETER; A CAP 52 MOUNTED ON THE REMOTE END OF THE CATHETER AND COVERING THE REMOTE END OF THE FIBERS, THIS CAP INCLUDING A REMOTE EMISSION SURFACE 74 AND CREATING AN OPTICAL PATH BETWEEN THE REMOTE END OF THE FIBERS AND THIS EMISSION SURFACE; AND AN OPENING 54 SHAPED IN THE HOOD TO ENSURE COMMUNICATION WITH THE OPENING OF THE CATHETER.

Description

Laser catheter, guided by wire

  The invention relates to catheters and techniques for providing and applying laser energy at a point within the human body. More specifically, the invention relates to a laser catheter guided by a wire.

  Although the theoretical possibilities of using

  Since laser energy has long been recognized in the medical field, the practical use of this energy has been limited to only a few types of applications. Essentially, processes in which laser energy has been used for medical treatment have been implemented in well-cleared and easily accessible parts of the human body, such as the patient's skin and eyes. Although it has been envisaged that laser energy could be used for the clearance of blood vessels, no satisfactory practical system

has not been developed yet.

  - The main obstacle to the development of techniques for applying laser energy to blood vessels has been the problem of how to accurately send the laser beam to the vascular point to be treated, and then to apply it Controlling the laser beam to remove the obstructive biological material without damaging or otherwise damaging the vascular system of the patient. The difficulties encountered were further complicated by the dimensional limitations imposed on any catheter to be introduced into a blood vessel, and in particular into narrow blood vessels such as coronary arteries whose lumens

  can be of the order of 1.5 to 4.5 mm in diameter.

  Difficulties include the manner in which the distal end of the catheter is brought in and placed in such a way that the catheter is properly positioned.

  compared to the obstruction. The proposals of the prior art

  including the use of additional optical fibers

  to transmit a lumen light into the blood vessel, in combination with other fiber groups making it possible to visually observe the interior of the blood vessel, are not practical because the fibers are too large and too rigid for

  be used in narrow arteries. Another difficulty

  encountered is that we often encounter

  such as blood in the area between the obstruc-

  and the point of emission of the laser beam at the end

  fiber. These materials can obstruct the optimal path

  than. Blood can be carbonized at the distant end of the fiber's emission, which can lead to overheating

  and destruction of the optical fiber.

  Another difficulty is that such

  catheter to be advanced to small arteries

  distance, must be very flexible to make sharp turns with a small radius of curvature, so as to reach these arteries. The catheter should also have a small diameter while still being able to be pushed and manipulated by its proximal end, without becoming tight or twisted as it advances within the patient's blood vessels. Another still very desirable feature of the catheter is that it is capable of providing fluid communication between the near end and the distal end of the catheter, to allow liquid injection or to allow pressure measurements. The development of a practical catheter to achieve the above goals while avoiding all the difficulties indicated has proved to be a very important problem. Although many laser catheters have been proposed in the past, none of these catheters have

  proved sufficiently usable in practice. All of these

  pose one or more of the various problems

  above. It is therefore a general object of the invention to provide a practical and efficient catheter system for delivering laser energy at selected points in the vessels.

  patient, with good control accuracy.

  To this end, the invention relates to a catheter for removing biological materials by applying laser energy, this catheter having a near end and a remote end, catheter characterized in that it comprises means defining a light extending over the entire length of the catheter, this lumen being open at the far end of the catheter; means located at

  near the end of this light to allow

  fluid with the light and to allow the introduction of

  duction of a guidewire into the light; a number of flexible optical conductors housed in the direction

  longitudinal axis of the catheter, inside the wall of this

  this; a cap mounted on the distal end of the catheter and covering the far end of the fibers, said cap having a remote transmitting surface and creating a path

  between the far end of the fibers and this

  emission face and an opening formed in the cap

  to ensure communication with the opening of the catheter.

  This catheter is intended for use with a guidewire. A central lumen, receiving the guide wire, extends over the entire length of the catheter and opens at the far end thereof. The catheter has a very small external diameter, of the order of 1.5 mm,

  and this catheter is small enough to advance deeply

  demented in the narrowest blood vessels * of the patient. A number of optical fibers are housed inside the catheter wall. The distal end of the catheter has a cylindrical cap

  optically transparent which covers and protects the

  distant from the optical fibers. The cap presents

  a central opening forming the exit opening

  aunt of light, the distant end of the cap

  sensing an annular configuration, ring-shaped, around the opening. The remote ends of the optical fibers are mounted securely with respect to the end cap, so that the light emitted by these optical fibers passes through the annular portion remote from the cap, and is emitted from the far end face,

ring-shaped, cap.

  The proximal end of the catheter has an adaptation to several branches from which a number of tubes depart. Each of these tubes is intended to receive the near end of an optical fiber. The near end of each tube has a connector for individually connecting the optical fibers to a laser light source. Each of the optical fibers is independent of the others and can be used and controlled independently

others according to the needs.

  Another tube starting from the close adaptation

  located at the proximal end of the catheter, is in communica-

  with the proximal end of the central lumen of the catheter, and allows access of a guidewire. The guide wire may be of very small diameter and may be constituted by a dirigible wire such as that described in

  US Patent Application 421,315 filed September 22, 1982.

  The cross section and shape of the guidewire and catheter lumen are such that when the guidewire is in place, a suitable flow section remains in the lumen to allow pressure measurements to be made in the lumen. blood vessel beyond the distant end of the catheter, and to also allow

  circulation of liguide in the light.

  According to another characteristic of the invention

  The catheter is designed to be extremely flexible in order to follow trajectories with a sharp curvature and a relatively small radius of curvature.

  vascular system of the patient. The catheter uses a

  composite wall truction comprising an inner core in which the central lumen is formed, and an outer sheath. The sheath is not attached to the core and can slide

  and move longitudinally relative to the core when

  to curve the catheter. The core is formed to have a number of grooves disposed in the

  longitudinal direction along the outer surface of the core.

  These grooves receive the individual optical fibers.

  The fibers are retained in the grooves by the outer sheath which, although not secured to the core, is sized to cover these grooves and to prevent the fibers from escaping from their respective grooves. The fibers can move freely in the longitudinal direction at

inside the grooves.

  When bending the catheter, all

  longitudinal members are free to move, so as to minimize curvature resistance. In addition, the flexibility of the composite catheter is further enhanced by providing a hinged configuration to the core. The core is formed to have reduced diameter, circumferential, peripheral notches along the core axis. The notch areas are more flexible and allow the catheter to be curved on extremely small radii of curvature. The flexibility of the catheter can be varied along its length, making

  vary the longitudinal spacing of the notches.

  The main advantage of the invention is to provide a small diameter guide laser catheter which is extremely flexible and maneuverable.

very easily.

  The invention also has the advantage of

  create a laser catheter that can be placed in use

reading a guide wire.

  The invention also has the advantage of creating

  a laser catheter with a central lumen

  to receive a guide wire, this central light ensures

  also the fluid communication between the end

  near and far end of the catheter, so as to allow

  put pressure measurements and the passage of a flow of liquid when the guide wire is in place in the light. Another advantage of the invention is to create a laser catheter of the type described above, in which

  the ends of the fibers are insulated to protect the fibers.

  Another advantage of the invention is to create a laser catheter using a number of fibers

  optics to provide laser energy, individual fibers

  they are provided with separate connection adaptations,

  and the transmission of energy in a fiber that can be

  independently from other fibers.

  Another advantage finally of the invention is to create a catheter of the type described above, making it possible to implement the features of the invention in the case of a catheter with a very small external diameter,

of the order of 1.5 mm in diameter.

  The invention will be described in detail with reference to the accompanying drawings, in which:

  FIG. 1 is a representation, in particular

  sieurs pieces, a catheter according to the invention in which passes a guide wire;

  FIG. 2 is a diagrammatic representation

  tick of the distant part of the catheter, in section on a quarter of its section, and on a larger scale;

  FIG. 3 is a longitudinal sectional view;

  dinal of the distant part of the catheter;

  FIG. 4 is a longitudinal representation

  dinal part of the main core stem which one

  removed the catheter sheath to illustrate the artificial nature of

  abutment of this core rod; FIG. 5 is a view on a larger scale of the catheter, in section along the line 5-5 of FIG. 3, the position of the guide wire inside the lumen being shown in dashed lines; FIG. 6 is a view of the distant end of the catheter seen along the line 6-6 of FIG. 3; FIG. 7 is a schematic side view

  distant end of the catheter, representing the

  ration of light rays emitted by this end and,

  FIGS. 7A, 7B and 7C are representative

  Schematic diagrams of the beams emitted by a catheter with four optical fibers, when looking in the image planes identified by references 7A-7A, 7B-7B and 7C-7C

of Figure 7.

  FIG. 1 represents the catheter, generally indicated by the reference 10, in which passes

  a guide wire generally identified by the reference

  In this figure, the remote end 14 of the guidewire 12 exits the distant end of the catheter 10, while the proximal end 16 of this guidewire 12 exits the proximal end of the catheter 10. This catheter 10 comprises an elongate main portion 18 which may, for example, have a length of the order 160 cm, the guidewire may have a length of the order of

cm or more.

  As will be described in more detail below, the invention allows the catheter to have a main portion 18 whose outer diameter does not exceed about 1.5 mm. A branch fitting 20 is molded to the proximal end of the main portion 18 of the catheter 10,

  and a number of tubes 22 start from this adaptation.

  20. The tubes 22 are intended to carry optical fibers, described below, each tube 22 carrying a

  single fiber and having at its proximal end a

  24 to connect the fiber of each of the tubes

22 to a laser light source.

  The catheter 10 comprises a flexible tube

  26 of the adapter 20 and communicating with a catheter lumen through which the guide wire 12. The tube 26 comprises an adaptation 28 to

  its near end. The adaptation 28 may be of the Luer-

  Lok allowing the tube 26 to easily and quickly connect to liquid injection devices and / or pressure monitoring devices. adaptation

  28 can be connected to a conventional adaptation Y allows

  both to control the guidewire 12 and to inject

  liquid by monitoring the pressure.

  The main part 18 of the catheter 10 com-

  takes an elongated inner core 30 surrounded by an elongated outer sheath 32. As shown in more detail in FIGS. 2 to 5, the inner core 30 has a lumen 34 disposed internally in the center of the core 30. The lumen 34 may be of circular section , although in a form

  preferred embodiment, a non-circular section is used.

  such as the four lobe shown in Figure 5, with projections 36 alternating with lobes in the form of grooves 38. The lobes 38 cooperate with the guide wire 12 of circular section (shown

  in dashed lines in Figure 12) so as to leave

  Sense a larger flow section in the space between the guide wire 12 and the core section 34 defining the inner lumen. The guide wire 12 and the light 34 of the core are made to form

  between them a space or game allowing the flow of a

  quide and the pressure measurements when the guide wire 12 is in place in this light. The tube 26 is connected to the core 30 inside the fitting 20, so that the light 34 is in communication with the light of this tube 26. The core 30 is also provided with a number of longitudinal grooves 40 regularly spaced on its circumference. Each of the grooves 40 receives a waveguide device, constituted for example by an optical fiber 42 intended to transmit the radiant energy constituted for example by a laser light. The optical fibers 42 are not fixed inside the grooves 40 and can therefore move longitudinally in these grooves when the catheter is bent. The ends of the fibers 42 are fixed in the distance portion of the catheter, in a manner to be described in detail hereinafter. The

  ends close to the fibers 42 pass through the adapta-

  20 and in the flexible tubes 22, to be fixed by

  their near ends, in the optical connectors 24.

  The tubes 22 are fixed in the adapter 20, and this adaptation is performed so as to ensure a transition of the passage of the fibers 42 between the grooves 40 and the tubes 22. The outer sheath 32 covers the core 30 and the fibers 42, and serves to maintain the fibers 42 in the grooves 40. Except at its points of connection with the catheter, at the near and far ends, the sheath 32 is not

  it is fixed either to the core 30 or to the optical fibers 42.

  There is therefore no point of attachment, over the entire length of the catheter, between the core 30, the optical fibers 42 or the sheath 32, which further improves the excellent flexibility characteristics of the catheter, reducing

  at least its internal resistance to the curvature.

  The sheath 32 is preferably made of a heat-shrinkable material, such as PTFE (Teflon) and shrunk hot around the core 32, but with a degree of tightening that does not risk interfering with the freedom of movement of the sheath and core. relative to each other when bending the catheter. By way of example, the core may have a diameter of about 1.15 mm and the sheath may have an inside diameter of about 1.27 mm, the wall thickness being about 0.076 mm, which leaves

  thus a very light game between the core and the sheath.

  The flexibility of the catheter is further

  by forming the core 30 to form a series of articulated segments. FIG. 4 represents a part of the core on which it can be seen that this nucleus presents

  a number of circular notches 44 spaced Ion-

gitudinalement.

  The notches separate the core into a number of core segments 46 arranged in series and connected by segments 48 of smaller diameter and shorter length. The use of the articulated core segments 46 increases the flexibility of the core 30 thereby increasing the flexibility of the composite catheter. The link segments 48 are smaller in diameter and have a lower curvature resistance, so that the bending force

  applied to the catheter causes the curvature of the nucleus to

  These link segments 48 may be regularly spaced along the entire length of the catheter, so as to give the catheter a degree of

  uniform flexibility throughout its length.

  However, if desired, the flexibility of the catheter can be varied at any point, this being achieved by varying the spacing of the connecting segments 48. When the segments 48 are brought closer to each other, the segment obtained catheter

  has greater flexibility than when space-

  is larger and when the length of the core segments 46 is larger. For example, it may be desirable to obtain a catheter in which the remote area is more flexible than the near area, so as to allow the remote area to bend on radii.

curvature shorter.

  Variations in flexibility of the catheter can also be obtained by varying the length of the connecting segments 48 in the same way as that of the core segments 46. By way of example, in a catheter having the dimensions indicated above, the core segments 46 may have a length of between 1 and 4 mm, and the link segments may have a length

between 1 mm and 1 mm.

  The core 30 is preferably made in

  a material having a coefficient of friction relative to

  the guide wire is preferably also coated with a material having a low coefficient of friction, such as PTFE, so as to further reduce

the friction between them.

  The core 30 is preferably provided with radiation-opaque strips 35 arranged along the length of the core. The strips 35 may be constituted by radiation-opaque materials incorporated in the resin in which the core has been extruded, according to

  methods well known in the art. In the preferred form

  In this embodiment, a number of radiation-opaque strips 35 are formed between the adjacent grooves 40. The radiation-opaque strips 35 are preferably formed only on the outer surface of the core, so that the inner surface remains completely intact.

  formed by the low friction material.

  It will be noted that the radiation-opaque strips are interrupted at the location of the notches 44. However, the strip obtained has an opaque image with sufficiently continuous radiation to enable visualization.

  effective position by fluoroscopy.

  The remote ends of the optical fibers 42 are secured together by a fiber carrier 50 attached to the fibers 40 at their remote ends. The

  fiber carrier 50 is housed and fixed in an end cap.

  mité, optically transparent 52, this cap being made in an optical glass or in an equivalent cistallin material allowing the transmission of the wavelength

  of the radiant energy with which the catheter is

  b. The cap serves to isolate the fibers 42 from the surrounding vasculature, and to protect these fibers from

biological materials.

  The fiber carrier 50, also shown in FIG. 6, is preferably made of a material that is opaque to radiation, such as for example stainless steel, or in a material that is even more opaque to radiation, such as platinum. The fiber carrier 50 is cylindrical and has a central opening preferably having exactly the same size as the slot 34 of the core 30. The central opening 54 may be circular in shape or lobed in shape, although an opening may be used. circular 54 in a catheter in which the central lumen 34 is lobed as shown in Figure 5. The fiber carrier 50 is provided with a number of longitudinal holes 56 therethrough and receiving, with a Certain clearance, the ends of the optical fibers 40. The remote face 58 of the combined assembly of the fibers 40 and the fiber carrier 50, is polished

  according to a plan that abuts against an annular shoulder

  The cap 52 is cylindrical and has the same diameter as the sheath 32, so as to form therewith a smooth continuous diameter. The cap 52 has an enlarged section hole 62 formed in its near end. This hole ends with an internal shoulder 60, and a smaller diameter central opening 64 is formed in the remote end of the cap 52. The central opening 64 may have the same diameter as the opening 54 of the fiber carrier 50. , so as to form a continuous smooth passage opening at the far end

of the catheter.

  However, the central aperture 64 may be a little narrower than the lumen 34 in that sufficient clearance is provided around the guidewire to

  not interfere with fluid flow and pressure measurement.

  Some reduction of the flow section may be tolerated at the far end, since this reduction exists only over a relatively short length,

  as would be the case if openings 64 and 54 are

  were a slightly or partially reduced flow section. The cap 52 is fixed, for example by epoxy glue, to the fiber holder 50, as well as to the portions of the core 30 and fibers 42 which are inside the end near the cap 52. The end remote from the sheath 32 simply abuts against the near end of the cap 52, and does not need to be glued to

this cap 52.

  For example, the cap 52 can be made from a pair of Pyrex glass cylinders that can be fused to one another. Thus, the cap 50 may be formed by an elongated Pyrex sleeve of relatively large diameter, and a relatively short Pyrex sleeve of smaller diameter, the smaller diameter sleeve fitting and fusing into one end. of the sleeve. The end where the two sleeves meet forms the relatively thick walled remote segment 72. The faces 60, 74 can be polished so as to be optically flat. The

  provision above makes it possible to fix the position of the

  remote from the fibers 42, completely protecting and isolating these fibers 42 from being

contact with biological materials.

  To optimize the flexibility of the catheter, it is preferable to use relatively few fibers

  optics. The beam emitted by the catheter must preferably

  divergence to give, slightly beyond the extreme

  catheter, a diameter just slightly greater than that of the catheter, so that the hole formed in the biological material by the laser energy is large enough

  to allow passage of the catheter through it.

  Moreover, it is preferable to carry out this operation with a relatively small number of fibers

  optics, so as not to reduce the very large flexibility

  desirable ability of the catheter. A catheter of very small diameter, of the order of 1.5 mm, achieves these objectives by using a four optical fiber arrangement regularly distributed around the central axis of the catheter. It is obvious, however, that the advantages of the invention can be achieved by using more or possibly less than four optical fibers, although it is preferable to keep the number of optical fibers

  minimum necessary to form the required beam.

  FIG. 7 schematically represents the configuration of beams obtained by a pair of diametrically opposed fibers. The beam, defined by the radius 1 / e2, is dimit by lines 70 of Figure 7. The 1 / e, is delimited by the lines 70 of Figure 7. The beam of each individual fiber 42 is emitted by the face distant from the fiber 42, and enters the segment

  remote 72 of the cap 52, by the face defining the shoulder

  60. The beam is divergent, and in the embodiment illustrated here can have a half-angle of the order of 6 to 16, according to the numerical aperture of the fiber. The diverging beam emitted by each of the fibers 42 leaves the emission face 74 located at the end

  52. FIGS. 7A, 78 and 7C show, in cross-section, the shape of the tax system observed in the image planes 7A, 7B and 7C of FIG. 7. At the level of the emission face 74 of the cap 52, the beams are further separated in the manner shown in Fig. 7A. At the height of the plane 7B-7B, the beams have

  still diverged and begin to overlap (Figure 7B).

  At the height of the plane 7C-7C, the bundles overlap and form an envelope 73 whose outside diameter is

  slightly greater than the diameter of the catheter.

  Preferably, the bundles 70 overlap so as to emerge by filling a continuous configuration, approximately a distance equal to the outer diameter of the catheter, from the face 74, i.e., about 1.5 mm in the described embodiment. The length of the segment 72 is preferably determined so that the distance between the face 74 of the cap 52 and the plane of a completely full image,

  the one we seek to obtain.

  According to another characteristic of the invention, the optical elements located at the end of the catheter are arranged so as to minimize the re-reflection. It will be noted in this connection that a certain amount of the light emitted by the catheter can be re-reflected by the biological material located inside the blood vessel. In addition, light in the infrared portion of the spectrum may be radiated by the biological material heated by absorption of radiant energy. This re-reflection is undesirable because the reflected light and the emitted infrared radiation can be absorbed by the optical fiber and the other elements at the far end, risking

  overheat and possibly damage these elements.

  To protect the device from this

  reflection and infrared radiation emitted, the face

  Aante 58 of the fiber carrier 50 and the remote ends of the fibers 42 are perfectly polished to form a reflective surface. Light reflected or emitted by biological tissue to the catheter is re-reflected

  by the face 58 which returns to the biological material.

  In addition, it is preferable to use an anti-

  reflecting on the shoulder surface 60 facing the near side of the cap, to optimize the transmission

  remote light through the surface 60.

  The catheter may be used in a variety of ways, depending on the preferences of the physician and the anatomievascular to be treated. For example, the catheter may be pre-assembled with the guide wire 12 placed therein, the remote end of the guide wire being retractable into the remote end of the catheter. We can then move forward together

  combination of the catheter and the guide wire, by a catheter

  guideway previously set up so that its

  far end is at the entrance to a cor-

  to treat. The combination of catheter and guidewire in the coronary artery can then be advanced slightly and the guidewire can be advanced.

alone in the artery.

  The guidewire 12 can be manipulated to selectively advance it into the branch

  in which the stenosis to be treated is located.

  When the guidewire has been put in place, the catheter can be advanced on this guidewire by following it to bring the distant end of the catheter to the desired point. The introduction of the guide wire and the catheter can be followed by fluoroscopy. In addition, a radiopaque dye may be injected into the catheter lumen 34 at any desired time.

  of the operation, to visualize by fluoroscopy the

coronary tomy.

  - Liquids such as radiation dyes can be injected at any time, even when the guide wire is in place. Washings such as saline solutions may also be delivered to the device, which liquids and entrained debris are then aspirated through the catheter. In the same way, blood pressure measurements can be made at any time, even when the guidewire is in place. The catheter can easily advance over the guidewire, and this catheter is extremely flexible, so that any curvature of the guidewire needed for

  adapt to the contour of the patient's vascular system.

  When the catheter has been advanced to the desired point, the laser energy can be sent through the optical fibers and applied to the point to be treated. The laser energy can be applied simultaneously by all the optical fibers 42, or selectively applied by each

individual fiber.

  Thus, the invention provides a catheter and a remote laser energy delivery system in hard-to-reach areas of a patient's vascular system. The invention makes it possible to set up a laser catheter using a guidewire, and this catheter is made so as to be extremely flexible to be able to follow all the pronounced curvatures of very small radius. The system allows for pressure measurements, and liquid injection without removing the guide wire. Moreover, these and other advantages are obtained in a catheter of

very small diameter.

RE SELL I C A T I 0 N S

  1) A catheter for removing biological material by laser energy application, this catheter having a near end and a remote end catheter characterized in that it comprises means defining a light (34) extending over the entire

  length of the catheter, this light being open to the

  distant end of the catheter; means (28) located at the near end of this light to allow

  fluid communication with light and for

  the introduction of a guide wire into the light; a number of flexible optical conductors (42) disposed in the longitudinal direction of the catheter, within the wall thereof; a cap (52) mounted on the distant end of the catheter and covering the far end of the fibers; said cap having a remote transmitting surface (72) and creating an optical path between the far end of the fibers and said transmitting surface; and an opening (54) formed in the cap to ensure

  communication with the opening of the catheter.

  The catheter of claim 1, further characterized in that the flexible optic leads (42) are housed within the catheter wall and are not attached to said catheter except for their

ends.

  3) catheter according to claim 1, characterized in that it comprises means (44, 46, 48) for varying the flexibility of the catheter

following its length.

  4) Catheter according to claim 3, characterized in that the means for varying the flexibility of the catheter are arranged so that it is more flexible in its far end portion than in

its near end part.

  5) A catheter according to claim 2, characterized in that the catheter is constituted by an elongate core (30) having a lumen (34) extending over the entire length thereof; in that a number of notches (40) are formed longitudinally on the outside of the core, the conductors (42) being received in these grooves; in that a flexible sheath (32) surrounds the core to hold the conductors in the grooves; and in that the conductors, the core and the sheath are absolutely not attached to each other, thus allowing the core, the conductor and the sheath to move longitudinally relative to each other to allow them to be bent simultaneously without the core, the conductors or the sheath interfering with the

  curvature of any of the other elements.

  6) Catheter according to claim 5,

  characterized in that it comprises means (50) for

  to fix the conductors in relation to the core,

the far end of this core.

  The catheter of claim 6, further characterized in that the proximal end of the

  catheter has a number of optical connectors

  (24), each connector being associated with a conductor (42) to thereby allow the independent control of these conductors. The catheter of claim 6, further characterized in that the leads (42) are secured by a ring of conductors (50) having

* a central opening (54) and a number of openings

  circumferentially spaced on the ring, each

  of these circularly spaced apertures receiving the end

  distant from a conductor; and that the holder

  conductors is attached to the cap (52).

  Catheter according to claim 8, characterized in that the carrier ring (50) is

opaque to radiation.

   The catheter of claim 8, further characterized in that the remote cap (52) has a cylindrical member with a close hole (62) for receiving the lead ring (50) and the far end of the core (30); in that the cap (52) has a smaller opening (64) formed

  distance and communiqaunt with the hole (62), this opening

  smaller area opening at the far end of the

  cap; in that the junction between the hole and the

  verture defines a shoulder (60); and in that the remote face of the carrier is in contact with

this shoulder.

  11) A catheter according to claim 10, characterized in that the distant end of the sheath (32) abuts against the end near the cap (52),

  and has exactly the same diameter as this cap.

  Catheter according to claim 8, further characterized in that the remote faces of the conductor carrier (50) and the conductors (42) attached to

  this one, are located in the same plane and are perfect-

  polished to form a perfectly reflective surface

  intended to re-reflect the light reflected by the biological material, and thus prevent the entry of this

  reflected light in the optical conductor.

  The catheter of claim 3, further characterized in that the core (30) is constituted by a number of articulated segments (46), and by

  flexible joints (44); and in that the outer sheath

  upper (32) is thin and flexible, this sheath not being connected to the core so as not to hinder flexion

of the nucleus.

  14) Catheter according to claim 13,

  further characterized in that the spacing of the joints

  (44) (46) is variable along the core, thereby varying the flexibility of the catheter, which catheter has. greater flexibility in areas where

  the joints are the closest together.

   Catheter according to claim 14, characterized in that the joints (44) (46) are closer to the distal end of the catheter than at its proximal end (16). Catheter according to claim 13,

  characterized in that the articulated segments are constituted

  killed by a number of circular notches (44), spaced in the longitudinal direction of the core, these circular notches defining additional connecting segments

  small diameter between the articulated segments (46).

  The catheter of claim 13, further characterized in that a number of grooves (40) are formed longitudinally on the outside of the core (30), the leads (42) being received in these grooves; in that a flexible sheath (32) surrounds the core to hold the conductors in the grooves; and in that the conductors, the core and the sheath are absolutely not attached to each other thereby allowing the core, the conductor and the sheath to move longitudinally relative to one another to thereby allow their simultaneous curvature without that the core, the conductors or the sheath impede the curvature of

  any of the other elements.

  The catheter of claim 17, further characterized in that the leads (42) are secured by a carrier ring (50) having

  a central opening (54) and a number of openings

  tures (56) spaced circularly on the ring, each

  of these circularly spaced apertures receiving the end

  distant from a conductor; and that the holder

  conductors is attached to the cap (52).

  The catheter of claim 18, further characterized in that the remote cap (52) has a cylindrical portion (60) with a close hole for receiving the lead ring (50) and the far end core (30); in that the cap has a smaller opening (54) formed at a distance and communicating with the near hole, this small opening opening at the far end of the cap; in that the junction between the hole and the core defines a shoulder (58); and in that the remote face of the carrier comes into contact with this

shoulder.

   Catheter according to claim 5, further characterized in that the core comprises at least one strip (35) opaque to radiation, this band being

  disposed in the longitudinal direction of the core.

  210) A catheter according to claim 5, characterized in that at least the inner surface of the core, defining the lumen (34), is formed in a

  material with a low coefficient of friction.

  The catheter of claim 1, further characterized in that the remote cap (52) has an annular portion terminating at the emission surface; in that the means (50) for keeping the remote faces of the conductors (42) in optical transmission relationship with the cap, so as to direct light from the conductors in the annular portion of the cap, these conductors being made and arranged to emit light in a diverging beam, such that the beams of light emitted by each of the circularly spaced fibers,

  overlap in the distant direction

  health; and that the distance between the emitting surface

  of the cap and the distant ends of the fibers, is equal to the distance between the emission surface of the cap and the image plane in which the overlapping beams have diverged to form an envelope

14.5.86

  device having a diameter at least as large as the outside diameter of the catheter, this distance between the transmitting and the image plane not being

  larger than the diameter of the catheter.

  23) A catheter according to claim 22, characterized in that the distance does not exceed about 1.5 mm. 24) Cahtéter according to any one of the

  Claims 1, 5, 6, 13 and 30, characterized in that

  that it is combined with the guide wire.

   ) Catheter according to claim 1, characterized in that it comprises an elongate core (30) provided with a lumen (34) extending over the entire length thereof, the core being formed of a number of articulated segments (46); and in that an outer sheath

flexible (32) surrounds the core.

  The catheter of claim 25, further characterized in that the spacing (44) of the joints connecting the articulated segments is variable, so as to vary the flexibility of the composite catheter. 27) A catheter according to claim 25, characterized in that the core (30) has a number of longitudinally spaced circular notches (44), each defining a segment of

  weaker link between the articulated segments

(46).