Extendable guidewire for cardiovascular procedures

Abstract: An extendable guidewire system for introducing a dilatation catheter into the cardiovascular system. The guidewire has guidewire (12) and extension (13) sections with a connection (18) therebetween which permits the two sections to be joined together and separated simply by pushing the two sections together and pulling them apart. One of the sections can be used for positioning the catheter within the cardiovascular system, and the other section can be employed to extend the wire to change catheters.

Description: Background of the Invention This invention generally relates to cardiovascular procedures such as angioplasty, angiography and valvuloplasty, and more particularly to an extendable guidewire for use in such procedures. Guidewires are currently used to facilitate the placement of catheters in the arterial system of a patient for cardiovascular procedures such as angioplasty, angiography and valvuloplasty. The guidewire is typically on the order of 20-50 cm longer than the catheter to permit the guidewire and the catheter to be advanced relative to each other as they are steered into position within the patient's body. Suitable guidewires are described in the U.S. Patent No. 4,538,622 (Samson et al.) and U.S. Patent No. 4,569,347 (Frisbie) which are hereby incorporated herein in their entirety. In the usual procedure to change catheters, the guidewire is removed from the patient, and an exchange wire is inserted in its place. The in-place catheter is removed from the patient and a new catheter is inserted into the patient. The exchange wire is then removed and the guidewire is reinserted. The exchange wire is substantially longer than the guidewire, and it generally extends outside the patient's body for a distance greater than the length of the catheter. With a dilatation catheter having a length of the order of 120-140 cm, for example, a guidewire might have a length of the order of 175 cm, and an exchange wire might have a length of the order of 300 cm. The use of an exchange wire has the obvious disadvantage that it complicates the angioplasty procedure. Heretofore, there have been some attempts to eliminate the need for a separate exchange wire by attaching an extension wire to a guidewire to extend the length thereof. The two wires are joined together by a crimped connector which requires a special tool. Once the wires have been crimped, the connection therebetween is permanent, and the extension wire cannot be removed except by severing it from the guidewire. One such example is described in GB-A-2,180,454. Another guidewire system comprising means for releasably connecting a first and second guidewire is described in JP 62-116746 upon which the preamble of claim 1 is based. The means for releasably connecting the two guidewires includes a sleeve formed at an end of one of the guidewires and an insert section formed at an end of the other of the guidewires, the insert section being insertable into the sleeve to provide a press fit. However, in each of the embodiments described it is the sleeve which deforms in order to establish the press fit. SUMMARY OF THE INVENTION The present invention provides a new and improved guidewire system. According to the present invention there is provided an extendable guidewire system comprising: a main guidewire section adapted to be inserted into a patient's vascular system, said guidewire section having a first mating end; a guidewire extension section having a second mating end; and connection means for releasably connecting the first and second mating ends, said connection means comprising a tubular member fixed to a mating end of one of the guidewire sections and a male member on the mating end of the other guidewire section, the male member having a maximum radial dimension (A) slightly greater than the inner diameter (B) of the tubular member and being adapted to be inserted into the tubular member, characterised in that, upon insertion into the tubular member, only the male member deforms to thereby releasably secure the two guidewire sections together. Thus a guidewire is provided with main and extension sections which are detachably secured together by press fitting. One of the guidewire sections has a tubular portion at the connecting end thereof, and the other guidewire section has a connecting end portion which has an effective diameter in one radial dimension which is slightly larger than the inner diameter of the tubular portion. The slightly larger connecting end of one of the guidewire sections is inserted into the tubular end of the other guidewire section. The slightly larger connecting end deforms to provide an interference or friction fit between it and the tubular portion and thereby detachably secures the two guidewire sections together. The two sections can be readily separated by pulling them apart. The two sections can be reconnected and disconnected as desired. These and other advantages of the invention will become more apparent from the following detailed description thereof and the accompanying exemplary drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary, centerline sectional view of an extendable guidewire embodying features of the invention, with parts separated; FIG 2 is a fragmentary centerline view of the embodiment shown in FIG. 1 with the parts joined; and FIG. 3 is a cross-sectional view taken along lines 3-3 of FIG. 2. DETAILED DESCRIPTION OF THE INVENTION As illustrated in FIG. 1-3, the guidewire system 10 embodying features of the invention has a main section 11 which is adapted to be inserted into a patient's vascular system and an extension section 12 which can be connected and disconnected to the main section 11 to facilitate the exchange of catheters without the need for removing the main section 11 from the patient's vascular system. Main guidewire section 11 generally comprises an elongated shaft 13 with a flexible tip (not shown) at its distal end and a smaller diameter portion 14 at its proximal end which is shaped into an undulating or sinusoidal shape. Reference is made to U.S. Patent 4,538,622 (Samson et al.) and U.S. Patent 4,569,347 (Frisbie), which have been previously incorporated herein by reference, for a description of desirable guidewire tip constructions. Extension section 12 has an elongated shaft 16 with smaller diameter projection or post 17 at its distal end. The connection 18 between guidewire sections 11 and 12 generally comprise tubular member 19 which is fixed to the distal end of the extension section 12 and which receives interfitting undulating member 14 which is on the proximal end of main section 11. Tubular member 19 is mounted by suitable means such as welding, brazing, soldering, by an adhesive or the like onto the short axial extension 17 of reduced diameter at the distal end of shaft 16. Axial extension or post 17 can be formed by any suitable means such as grinding down the proximal end portion of the shaft 16 to the desired diameter so that it interfits into the end of tubular member 19. The undulating portion 14 is formed by first grinding the proximal end of main section 11 to a smaller diameter, then forming the undulations or sinusoidal shape by bending over a mandrel or other suitable means. The maximum dimension A of the undulated section should be slightly more than the inner diameter B of tubular connecting piece 19. but preferably not more than 50% greater than dimension B to provide interference or friction fit which will hold the sections together during catheter exchange but which can be readily disengaged after exchange has been made. Preferably no more than a one pound pull should be necessary for disengagement. In a guidewire having a diameter on the order of about .36 mm (.014 inch), for example, tubular member 19 might have an inner diameter of about .18 mm (.007 inch) and a wall thickness of the order of .025 mm (.001 inch) and the undulating section 14 might have a maximum radial dimension of about .23 mm (.009 inch). In this embodiment, tubular member 19 might have a length of the order of about 2.4-2.5 cm. The main guidewire section is intended for use in positioning a dilatation catheter (not shown) in the cardiovascular system of a patient, and it has a length corresponding to the length of a conventional guidewire for this purpose. Details of typical dilatation catheters and guidewires can be found in the patents cited previously and incorporated herein. Extension section 12 is sufficiently long so that when the guidewire sections 11 and 12 are connected together the guidewire system 10 has an overall length suitable for exchanging catheters without removing the main section 11 from the patient's vascular system. With a dilatation catheter having a length of the order of 120-140 cm, for example, section 11 might have a length of 140-175 cm, and section 12 might have a length of 125-160 cm. Shafts 13 and 16 and tubular member 19 can be fabricated from suitable material, such as stainless steel, Nitinol (55% Ni-Bal. Ti), and the like, and each should have a diameter to allow a dilatation catheter to pass freely over them. It is preferable that the two shafts 13 and 16 be of substantially the same diameter in order to provide a smooth transition between them. In one presently preferred embodiment for use in coronary angioplasty, shafts 13 and 16 have a diameter of the order of about .36 mm (.014 inch). Either or both of the shafts can be provided with a coating of polytetrafluoroethylene, which is sold under the trademark Teflon by the DuPont Corporation, or another suitable low-friction material to facilitate the movement of the catheter over the wire. In use, the main guidewire section 11 is introduced into the vascular system of a patient with a dilatation catheter through a guiding catheter (not shown) and an introducer (not shown). When performing coronary angioplasty, the distal end of the guiding catheter is positioned in the coronary ostium, and the dilatation catheter is advanced so that it is just proximal to the tip of the guiding catheter. The distal tip of the guidewire is advanced beyond the distal tip of the dilatation catheter while the latter is held in place. As the main guidewire section 11 is advanced, it is rotated and steered into the selected artery. The guidewire tip is preferably advanced through the lesion and beyond it, in order to permit the balloon portion of the dilatation catheter to be positioned within the lesion over a more supportive section of the guidewire. Once in position, the main guidewire section 11 is held in place and the dilatation catheter is advanced along it until the inflatable balloon thereof is within the lesion. Undulating end portion 14 remains outside the patient's body and outside any adapter which may be connected to the proximal end of the dilatation catheter. To exchange catheters, the main guidewire section 11 is extended by manually pressing the open end of tubular member 19 on the distal end of extension section 12 onto the undulating end 14. As the tubular member 19 is inserted over the undulating end 14, the undulating member 14 deforms to thereby firmly but releasably hold the two guidewire sections together. The dilatation catheter can then be withdrawn from the patient's body over the extended guidewire system. A new dilatation catheter may then be introduced over the extension section 12 and advanced along the main guidewire section 11 within the patient's body until the balloon crosses the lesion. Once the proximal end of the new balloon catheter has advanced beyond connection 18 and tubular end portion 19, section 12 can be removed by grasping the two guidewire sections 11 and 12 on opposite sides of the connection 18 and pulling them apart without disturbing the position of section 11 in the patient's body. As previously described, the interference or friction fit between the undulating member 14 and the tubular member 19 should be sufficiently strong to hold the two guidewire sections 11 and 12 together while dilatation catheters are being exchanged, but should be capable of separation by a pulling force less than one pound. The invention has a number of important features and advantages. The two sections of the guidewire can be connected together whenever a longer wire is needed, and they can be separated whenever the additional length is not required. The two sections of the guidewire may be connected and disconnected by the physician by simply pressing them together and pulling them apart. This can be done as needed, and no special tools are required either to make the connection or to separate it. Thus the catheter exchange is greatly simplified. It is apparent from the foregoing that a new and improved extended guidewire system has been provided. While the present invention has been described herein with the tubular connecting element fixed to the distal end of the guidewire extension section and the male member adapted to be inserted into the open end of the tubular member on the proximal end of the main guidewire section, it is obvious that the tubular element on the distal end of the extension section may be interchanged with the male member on the main guidewire section. Moreover, it will be apparent to those familiar with the art, that other modifications and improvements can be made without departing from the scope of the invention as defined by the following claims.

Claims: An extendable guidewire system (10) comprising: a main guidewire section (11) adapted to be inserted into a patient's vascular system, said guidewire section (11) having a first mating end; a guidewire extension section (12) having a second mating end; and connection means for releasably connecting the first and second mating ends, said connection means comprising a tubular member (19) fixed to a mating end of one of the guidewire sections (11,12) and a male member (14) on the mating end of the other guidewire section (11,12), the male member (14) having a maximum radial dimension (A) slightly greater than the inner diameter (B) of the tubular member (19) and being adapted to be inserted into the tubular member (19), characterised in that, upon insertion into the tubular member (19), only the male member (14) deforms to thereby releasably secure the two guidewire sections (11,12) together. The extendable guidewire system (10) of claim 1, wherein the tubular member (19) is fixed to the distal end of the guidewire extension section (12) and the male member (14) is on the proximal end of the mating main guidewire section (11). The extendable guidewire system (10) of claim 1, wherein the tubular member (19) is fixed to the proximal end of the main guidewire section (11) and the male member (14) is on the distal end of the guidewire extension section (12). The extendable guidewire system (10) of any preceding claim, wherein the maximum radial dimension (A) of the male member (14) is not more than 50% greater than the inside diameter (B) of the tubular member (19). The guidewire extension system (10) of any preceding claim, wherein the tubular member (19) is fixed to an end of a guidewire section (11,12) by welding, brazing soldering or by an adhesive.

Inventors: ABRAMS ROBERT M, GUTHRIE LINDA THEODORA, HUSS BEVERLY, KRAUS JEFFREY LLOYD, MAR CRAIG E, MESSNER KIRSTEN L, TAYLOR CHARLES S, ABRAMS, ROBERT M., GUTHRIE, LINDA THEODORA, HUSS, BEVERLY, KRAUS, JEFFREY LLOYD, MAR, CRAIG E., MESSNER, KIRSTEN L., TAYLOR, CHARLES S.
Applicants: ADVANCED CARDIOVASCULAR SYSTEM, ADVANCED CARDIOVASCULAR SYSTEMS, INC.
Application year: 1988
Main classification: A61M25
IPC codes: A61M25