Laser catheter for removal of obstructive substance from body channels

Abstract: A catheter device (10) and a method for using same to facilitate removal of obstructive material in a human body channel. The catheter comprises an elongated body (12) with a distal end portion adapted to be inserted within the channel and a proximal end portion. A lumen, extending lengthwise through said catheter body, supports a guidewire (22) having a distal end along which the catheter body can be moved within the channel. A series of parallel, closely spaced fiber members (14) extend through the catheter body from its proximal end and terminate near a distal end face of said catheter. Laser energy supplied at the catheter's proximal end is transmitted along the fiber members and is emitted forwardly therefrom at the catheter's distal end face. In one embodiment the catheter has a tapered nose portion (18) for displacing obstructive material in the body channel before the emission of laser energy. In another embodiment, the fiber members are movable longitudinally in unison to sever and trap obstructive material which is removed from the body channel.

Description: This invention relates to an apparatus for removing substances or matter which cause obstructions, blockages or occlusions in body passages, channels or ducts such as arteries or veins. Although body channel obstructions such as blocked arteries have been treated heretofore using surgical arteriotomy techniques as well as with medicines for dissolving certain obstructive substances, a substantial effort has been made to perfect so-called minimally invasive techniques using catheter-based systems. In such systems, the artery is entered at a site remote from the obstruction so that elongated devices can be guided through the arterial system to the desired site. Such devices have included a catheter with a tapered tip which was pushed through the area of obstruction using a so-called Dotter technique or a catheter with an inflatable balloon near its distal tip for using the balloon angioplasty technique. Other mechanical means of opening arteries include the use of rapidly rotating elements, for example the "Auth" technique which is an elongated device with a rotating diamond studded tip which grinds the obstructing material as it advances within the artery, or the "Fischell" technique which slices the blockage as it is withdrawn from the artery, or the "Stack" or Kensey techniques which use elongated catheters with rotating blades to chop the obstructing material, or the "Simpson" technique which is an elongated catheter that slices the obstruction at the side of the distal tip of the device. Thermal and laser energy have also been used to open obstructed arteries. The "hot tip" technique utilizes thermal energy generated by electrical, chemical or laser to heat the tip of an elongated catheter which then vaporizes or melts the area of obstruction as it is advanced through the artery. Direct laser energy can be transmitted through elongated fiberoptic catheters to the site of obstruction in order to vaporize the obstruction. To date, the mechanical means of removing obstructions from arteries are associated with formation of debris which flows downstream and blocks more distal vessels or with high frequency of closure of the artery after the procedure ranging from 25% to 50% in the case of the Auth, Simpson, balloon angioplasty, and related techniques. The cause of the reclosure is thought to be related to the mechanical damage to underlying healthy tissue and to the internal surface characteristics produced by the mechanical procedures. Attempts have been made to use laser energy or thermal energy after the mechanical techniques to improve the damaged surface characteristics and to weld any defects in the artery wall caused by the initial mechanical procedures. Attempts have also been made to combine the use of laser energy with an angioplasty catheter to remove arterial obstructions as disclosed by Leckrone in U.S. Patent Nos. 4 685 458 and 4 747 405. In these patents, a catheter having an attached inflatable balloon is provided with laser transmission filaments for ablating or dissolving obstructive material in an arterial passage. DE-A-3 406 294 discloses a catheter device which comprises a tubular body provided at its free end with an inflatable balloon and including light guiding means for projecting a light beam from the front face of the free end of the tubular body. A guiding catheter is movable within the central lumen of the tubular body and includes an inflatable balloon at its free end. EP-A-0 153 847 discloses an intravascular laser catheter comprising a bundle of solid optical fibres disposed in an annular array about the outer wall of the catheter. The distal end of the fibre bundle is bevelled at an angle so as to focus the laser energy to a single focal point. EP-A-0 163 502 discloses an atherectomy device comprising a generally cylindrical housing formed of a relatively rigid material and having rounded distal and proximal end portions. The housing is formed with a cut-out extending longitudinally on one side thereof. An atheroma cutter is disposed within the housing and is movable in the housing longitudinally of the cut-out. A flexible torque tube is secured to the housing and a torque cable secured to the cutter is disposed within the torque tube. Torque cable allows for rotation of the cutter while the cutter is moved longitudinally of the housing. One object of the present invention is to provide an improved catheter device for treating obstructions or blockages in body channels which combines the use of mechanical force thereof for displacing or compressing blockage material and manipulations with laser energy for dissolving or severing the blockage material. Another object of the invention is to provide a catheter device for removing obstructions in body channels that enables the use of a reduced amount of laser energy directed so as to sever rather than dissolve the obstructing material, thereby reducing the danger of damaging healthy body tissue. Another object of the invention is to provide a catheter device for removing obstructions in body channels that enables particles of removed obstructive material in body channels such as arteries to be trapped and retrieved, rather than allowed to fall into the fluid stream of the body channel. Yet another object of the invention is to provide a catheter device for removing obstructions in body channels that is readily controllable and maneuverable in use to provide for efficient removal of body channel obstructions without damage to healthy tissue and thus with minimum risk to the patient. In accordance with the principles of the present invention both mechanical and laser elements are combined in a catheter type device to dissolve, breakup and remove obstructive material from various body channels. Moreover, the removal process with my device may be accomplished with a minimal risk to healthy body components such as artery walls because the laser energy is directed so as to reduce the force required to remove obstructive material or to stretch the artery under treatment. Lower force requirements in expanding an opening in an arterial channel result in less damage to surrounding healthy tissues, and the laser simultaneously treats the internal arterial surface to achieve a smoother arterial lumen. In general, a catheter device according to the present invention comprises a catheter having an elongated body with a distal end portion adapted to be inserted within said human body channel and a proximal end portion, said distal end portion of said catheter body having an open compartment on one side defined by an inner end face transverse to the longitudinal catheter axis spaced from an outer end face transverse to the longitudinal catheter axis, a nose portion on said catheter body extending forwardly from said inner end face, a narrowed body portion interconnecting said inner and outer end faces, and an arcuate groove formed in said outer end face; a lumen extending lengthwise through said catheter body; a guidewire extending through said catheter lumen and having a distal end which projects beyond the distal end portion of said catheter body; a series of fiber members extending through said catheter body and terminating at spaced apart locations on said inner transverse end face; laser means connected to said fiber members near the proximal end portion of said catheter body for delivering laser energy through said fiber members and forwardly from said inner transverse end face; and means at said proximal end portion of said catheter for longitudinally moving in unison said fiber members within said catheter body from said inner end face to said outer end face as said laser means is activated ; whereby said arcuate groove formed in said outer end face receives the distal ends of said fiber members when they have been moved forwardly from said inner end face and severed obstruction material is retained within compartment. Preferably, the fiber members within the catheter body are a series of parallel, laser transmitting glass fibers. Near the distal end of the catheter body, the ends of these fibers are arranged fairly close together in an arcuate pattern. At the proximal end of the catheter body, the fibers are bunched together to interface with a laser generator in a conventional manner. Preferably, a tapered or conical nose member is provided at the distal end of the catheter body which is axially aligned therewith. In use, the nose member forces obstructive material radially toward the walls of the body channel as the catheter is moved progressively so that at a blocage site the main part of the obstruction material actually extends into the open compartiment. In one embodiment, the guidewire is provided with an expandable element such as a balloon at its distal end so that it can be moved past an obstruction and then inflated. Again, an annular array of fibers in the catheter body is moved along the guidewire until it is directly adjacent to the obstructive material. Now, as laser energy is directed from the ends of the fibers, the catheter body moves closer to the balloon and most of the dissolved or broken off particles of the obstruction are trapped by the expandable element in the hollow end of the catheter so that they can be retrieved without falling into the body channel fluid. Preferably, the nose portion on said catheter body is a tapered distal end portion directly adjacent the open side compartment formed by the inner and outer transverse faces. The inner transverse face has a series of arcuately arrayed laser transmitting fibers and these fibers are controllable at the proximal end of the catheter so as to be movable forwardly in unison from the inner transverse face to the outer transverse face of the catheter compartment. Thus, in use, a guidewire with an expandable element is first placed across the blockage and is expanded. The guidewire is then used to position the catheter directly opposite an accumulation or growth of obstructive material so that the material extends into the open catheter compartment. Now, as laser energy is directed from the ends of the fibers, the fibers are moved forwardly in unison toward the outer face of the compartment, effectively severing the main portion of the obstructive material. The moving fibers essentially serve as a gate which traps the severed material in the catheter compartment so that it can then be removed either when the catheter is withdrawn or by applying motion to an inner lumen of the catheter at its proximal end. Other objects, advantages and features of the invention will become apparent from the following detailed description of the embodiments which is presented in conjunction with the accompanying drawings. Fig. 1 is an enlarged fragmentary view in perspective showing the distal end of a catheter embodying the principles of the present invention. Fig. 1A is a view in section of the device of Fig. 1, taken along line 1A-1A of Fig. 2A. Figs. 2A-2C are a series of elevation views in section showing the device of Fig. 1 as it appears during a typical operation within a body channel. Fig. 3 is an enlarged fragmentary view in perspective showing the distal end of another form of catheter embodying the principeles of the invention. Figs. 4A-4C are a series of elevation views in section showing the catether of Fig. 3 as it appears during a typical operation within a body channel. Fig. 5 is a view in section showing the proximal end for a catheter device according to the invention. In broad terms, the present invention provides a catheter device adapted to be moved through a body channel while using a combination of mechanical force and laser energy to remove, dissolve and/or retrieve obstructive material in the channel. Such body channels may be arteries, veins, ducts or passages although the following description of embodiments will refer primarily to use of the invention in arteries for the removal of plaque deposits. With reference to the drawing, a first catheter device 10, embodying the principles of the invention is shown in Figs. 1, 1A and 2A-2C. In general, this embodiment comprises a cylindrical catheter body 12 of a suitable flexible plastic material (e.g. polyethylene) having a uniform diameter along a major portion of its length. Circumferentially spaced near its outer surface are a plurality of lumens 13 containing laser transmitting elements 14. These laser elements may be glass fibers having a diameter in the range of one to six hundred micrometers each. The catheter body 12 is preferably provided with a tapered nose portion 38 spaced from an inner arcuate transverse end face 40 of the catheter and connected by a portion 42 of the catheter body to form an open compartment 44 at its distal end. The compartment is open on one side of the cylindrical catheter body and its length is preferably somewhat larger than the diameter of the catheter. The arcuate inner transverse end face 40 of the catheter includes the exposed ends of the laser transmitting elements 14. At the other end of the compartment and parallel to the inner end face 40 is an outer transverse face 46 of the nose portion which has an arcuate indented notch 48 (see Fig. 2A). Within the catheter body is a lumen 20 for supporting a movable guidewire 22. At the inner transverse end face 40 of catheter 10, the exposed ends of the elements 14 are close together or contiguous and thus terminate at equally spaced apart intervals of less than the diameter of a fiber element around said inner transverse end face 40. Preferably, the exposed ends of the elements 14 on the inner transverse end face 40 are circumferentially spaced apart in a semi-circular pattern. At or near the proximal end of the catheter body 12 the glass fibers 14 which are separate, but closely spaced at the distal end of the catheter body, are brought together in one fiber bundle 36. A laser transmission system is then used, as shown in Fig. 5 to transmit laser energy from a suitable generator source 38 through a single transmission element 40 and a connector 42 into the bundle of fibers and thence through the separate fibers 14 within the catheter body 12. Extending beyond the proximal end of the catheter body, is the movable controllable guidewire 22. The closely spaced glass fibers 14 in the catheter body 12 are supported in said separate lumens 13 and are longitudinally movable within these lumens. In the operation of catheter 10, as shown in Figs. 2A-2C, the guidewire 22 is installed in the conventional manner within the body channel being treated. As shown in Fig. 2A, the guidewire is first moved beyond the channel obstruction that is to be removed. Thereafter, the catheter 10 is installed on the guidewire, is moved along it and through the body channel until the distal end is positioned directly opposite the obstruction. Here the guidewire is offset to one side of the catheter body 12 which helps to maneuver the catheter nose portion 38 partially through the obstruction so that the main part of the obstruction material actually extends into the open compartment 44. With the catheter so situated, as shown in Fig.2A, the fiber members 14 are simultaneously moved forward by an axial force applied to the fiber bundle at the proximal end as a laser energy source at its proximal end provides laser energy to the fibers. As the fibers 14 move forward, with pulses of laser energy being emitted from their ends, any osbtruction material in their path is dissolved and/or severed as shown in Fig. 2B. When the movable fibers reach the arcuate slot 48 in the outer face 46 of the catheter nose portion 38, the laser energy is turned off, and the severed obstruction material is retained within the compartment 44 which is now closed by the extended series of fibers 14. As shown in Fig. 2C, the catheter 10 with the severed and retained obstruction material and the guidewire 22 are now moved in the reversed direction to withdraw them from the patient's body channel. Again, the body channel obstruction has been removed with a combination of mechanical force and laser energy and a major portion of the severed obstruction material has been removed without allowing it to contaminate the blood or fluid in the body channel. A somewhat modified catheter 10A similar to the catheter 10 is shown in Fig. 3 wherein a guidewire 22A having an inflatable element such as the balloon 34 is used. Guidewire 22A is of the type having an air conduit or some suitable mechanism along its length which may be connected to either an inflatable balloon or to some mechanically expandable element near the distal end of the guidewire. As previously described, the distal end of catheter 10A includes a tapered nose portion 38 with an open compartment 44 on one side which is closable by a series of movable, laser transmitting glass fibers 14 in the catheter body 12A. The glass fibers are movable in unison from one inner transverse end face 40 of the catheter compartment to the outer transverse end face 46 of the nose portion 38 which forms the opposite end of the compartment. As shown in Figs. 4A-4C, using the catheter 10A, the guidewire 22A is first installed and positioned within a body channel 28 so that the balloon 34 on the guidewire can be inflated just beyond an obstruction 26 located on one side of the body channel, as shown in Fig. 4A. Now, the catheter is moved along the guidewire until the open compartment 44 in the distal end of the catheter is directly opposite the channel obstruction 26. The catheter can be rotated on the guidewire 22A using the known technique so that the catheter is moved laterally closer to the obstruction and the latter projects well into the compartment 44. Now, as with catheter 10, the fibers 14 are moved forwardly in unison at a slow rate as the laser source at the proximal end is energized and laser beams from the ends of the fibers dissolve and sever the obstruction material. The larger pieces of undissolved obstruction material fall into the compartment 44 and are trapped as the fibers reach the outer face of the nose portion. Thereafter, as shown in Fig. 4C, the balloon 34 is deflated and the entire catheter assembly 10A with its guidewire 22A is carefully removed from the body channel or artery. From the foregoing, it is apparent that the present invention provides a unique catheter system that uses laser energy to remove obstructions or blockages in body channels with increased efficiency and safety. The combination of mechanical force as described serves to displace the obstructive material directly into the path of the laser beams which are thus highly effective in dissolving and/or severing the obstructive material. The invention also provides for the removal of severed material in lieu of allowing it to be carried away by the channel fluid which adds a significant safety feature with respect to the prevention of future blockages in a patient.

Claims: A catheter device (10) for removing an obstruction in a human body channel, said device comprising: a catheter having an elongated body (12) with a distal end portion adapted to be inserted within said human body channel and a proximal end portion, said distal end portion of said catheter body (12B) having an open compartment (44) on one side defined by an inner end face (40) transverse to the longitudinal catheter axis spaced from an outer end face (46) transverse to the longitudinal catheter axis, a nose portion (38) on said catheter body extending forwardly from said inner end face (40), a narrowed body portion (42) interconnecting said inner and outer end faces, and an arcuate groove (48) formed in said outer end face; a lumen (20) extending lengthwise through said catheter body; a guidewire (22) extending through said catheter lumen (20) and having a distal end which projects beyond the distal end portion of said catheter body; a series of fiber members (14) extending through said catheter body and terminating at spaced apart locations on said inner transverse end face (40); laser means connected to said fiber members (14) near the proximal end portion of said catheter body for delivering laser energy through said fiber members and forwardly from said inner transverse end face (40); and means at said proximal end portion of said catheter for longitudinally moving in unison said fiber members (14) within said catheter body (12) from said inner end face (40) to said outer end face (46) as said laser means is activated ; whereby said arcuate groove (48) formed in said outer end face (46) receives the distal ends of said fiber members (14) when they have been moved forwardly from said inner end face (40) and severed obstruction material is retained within compartment (44). The catheter device of claim 1 further comprising expandable means (34) on said guidewire (22A) near its distal end and means for controlling said expandable means at said proximal end portion of said catheter body. The catheter device of claim 2, wherein said expandable means (34) is a balloon, said guidewire (22A) including an air passage for inflating said balloon. The catheter device according to anyone of claims 1 to 3 wherein said fiber members (14) are spaced apart circumferentially in a semi-circular pattern at said inner end face (40). The catheter device according to anyone of claims 1 to 4, wherein said nose portion (38) is a tapered nose portion. The catheter device according to anyone of claims 1 to 5, wherein said catheter body (12) further comprises an open central bore extending through said catheter body from said inner end face (40). A catheter device (10) as in anyone of the preceding claims, characterized in that said fiber members (14) are spaced apart by a distance no greater than one fiber diameter. A catheter device as in anyone of the preceding claims, characterized in that said fiber members (14) are of glass material having a diameter in the range of 1 to 600 µm.

Inventors: MURPHY-CHUTORIAN DOUGLAS, MURPHY-CHUTORIAN, DOUGLAS
Applicants: ECLIPSE SURGICAL TECH, ECLIPSE SURGICAL TECHNOLOGIES, INC.
Application year: 1990
Main classification: A61B17
IPC codes: A61B17, A61B18