Patent Application
20050209582
The present invention relates to multi-lumen catheters used with guidewires and, in particular, to a system facilitating control over the guidewire independent of the multi-lumen catheter.
Cardiovascular disease, including atherosclerosis, is a leading cause of death in the U.S. The medical community has responded by developing a number of methods and devices for treating coronary heart disease. Some of those methods and devices are specifically designed to treat the complications resulting from atherosclerosis and other forms of coronary arterial narrowing.
One method for treating atherosclerosis, in addition to other forms of coronary narrowing, is percutaneous transluminal coronary angioplasty, commonly referred to as “angioplasty” or “PTCA”. The objective in angioplasty is to enlarge the lumen of the affected coronary artery by hydraulically expanding a device placed within the affected body lumen. The procedure is commonly performed by inflating the balloon of a balloon catheter within the narrowed region of the coronary artery.
Catheters have become utilized in many procedures beyond treating coronary heart disease. For example, they are used for delivery of stents, grafts, therapeutic substances (such as anti-vaso-occlusion agents or tumor treatment drugs) and radiopaque agents for radiographic viewing.
The anatomy of coronary arteries varies widely from patient to patient. Often a patient's coronary arteries are irregularly shaped, highly tortuous and very narrow. The tortuous configuration of the arteries may present difficulties to the physician in proper placement of a guidewire, and advancement of a catheter to a treatment site. A highly tortuous coronary anatomy typically will present considerable resistance to advancement of the catheter over the guidewire.
Therefore, it is important for a catheter to be highly flexible. However, it is also important for a catheter shaft to be stiff enough to progress the catheter through the vessel in a controlled manner from a position far away from the distal end of the catheter.
Conventional catheter shafts for PTCA and other procedures typically include a proximal shaft, a transition section and a distal shaft terminating at a flexible tip. Generally, the proximal shaft is relatively rigid to allow for increased pushability and has a guidewire lumen extending throughout its length. In contrast, the distal shaft is generally a flexible polyethylene sleeve with a flexible polyethylene tube disposed concentrically within the sleeve and extending from the guidewire lumen at the distal end of the proximal shaft, through the transition section and the distal shaft. Typically, the distal shaft extends for a length on the order of 25 centimeters and allows for curving through particularly tortuous vessels. The transition section provides a gradual transition in stiffness between the relatively stiff proximal shaft and the flexible distal shaft. Including the transition section reduces the tendency of portions of the catheter, particularly where the rigid proximal shaft and the flexible distal shaft meet, to collapse, buckle or kink.
In a typical PTCA procedure, it may be necessary to perform multiple dilatations, for example, using various sized balloons. In order to accomplish the multiple dilatations, the original catheter must be removed and a second catheter tracked to the treatment site. When catheter exchange is desired, it is advantageous to leave the guidewire in place while the first catheter is removed to properly track the second catheter.
Two types of catheters commonly used in angioplasty procedures are referred to as over-the-wire (OTW) catheters and rapid exchange (RX) catheters. A third type of catheter with preferred features of both OTW and RX catheters, which is sold under the trademarks MULTI-EXCHANGE, ZIPPER MX, ZIPPER, MX and/or MXII, is discussed below. An OTW catheter's guidewire lumen runs the entire length of the catheter and the entire length of an OTW catheter is tracked over a guidewire during a PTCA procedure. A RX catheter, on the other hand, has a guidewire lumen that extends within only the distalmost portion of the catheter. Thus, during a PTCA procedure only the distalmost portion of a RX catheter is tracked over a guidewire.
If a catheter exchange is required while using a standard OTW catheter, the user must add an extension onto the proximal end of the guidewire to maintain control of the guidewire during the exchange and to maintain its sterility. Once the extension is added, the clinician can slide the catheter off of the extended guidewire, slide the new catheter onto the guidewire and track the new catheter to the original catheter position. Due to the length of the extended guidewire, multiple operators are required to hold the extended guidewire in place while the original catheter is removed.
A RX catheter avoids the need for multiple operators when changing catheters. With a rapid exchange catheter, the majority of the guidewire resides outside of the catheter. The guidewire enters the catheter only in the distalmost portion. That exposure of the guidewire allows it to be held in place when the catheter is removed from the body without necessitating the addition of a guidewire extension. Although the guidewire exposure simplifies catheter exchange, it can create a problem with entanglement between the exposed portion of the guidewire and the catheter shaft during use.
There are other instances when the guidewire must be replaced and the catheter left indwelling. An OTW catheter, with the guidewire lumen extending the entire length of the catheter, allows for simple guidewire exchange. A rapid exchange catheter, on the other hand, is not so accommodating. To replace a guidewire with a RX catheter, the guidewire and most of the catheter must be removed from the body. Essentially, the procedure must then start anew because both the guidewire and the catheter must be returned to the treatment site.
A balloon catheter capable of both fast and simple guidewire and catheter exchange is particularly advantageous. A catheter designed to address this need is sold by Medtronic Vascular, Inc. of Santa Rosa, Calif. under the trademarks MULTI-EXCHANGE, ZIPPER MX, ZIPPER, MX and/or MXII (hereinafter referred to as the “MX catheter”). An MX catheter is disclosed in U.S. Pat. No. 4,988,356 to Crittenden et al.; co-pending U.S. patent application Ser. No. 10/116,234, filed Apr. 4, 2002; co-pending U.S. patent application Ser. No. 10/251,578, filed Sep. 18, 2002; co-pending U.S. patent application Ser. No. 10/251,477, filed Sep. 20, 2002; co-pending U.S. patent application Ser. No. 10/722,191, filed Nov. 24, 2003; and co-pending U.S. patent application Ser. No. 10/720,535, filed Nov. 24, 2003, all of which are incorporated by reference in their entirety herein.
The MX catheter includes a proximal catheter shaft having a guidewire lumen positioned side-by-side with an inflation lumen. The MX catheter also includes a longitudinal cut that extends along the proximal catheter shaft and that extends radially from the guidewire lumen to an exterior surface of the proximal catheter shaft. A guide member that is slideably coupled with the proximal shaft cooperates with the longitudinal cut such that a guidewire may extend transversely into or out of the guidewire lumen at any location along the longitudinal cut's length. By moving the shaft with respect to the guide member, the effective over-the-wire length of the MX catheter is adjustable.
In the MX catheter, a guidewire is threaded into a guidewire lumen through an opening at the distal end of the catheter and out through the guide member. The proximal guidewire lumen envelops the guidewire as the catheter is advanced into the patient's vasculature. Furthermore, the indwelling catheter may be removed by withdrawing the catheter from the patient while holding the proximal end of the guidewire and the guide member in a fixed position. When the catheter has been withdrawn to the point where the distal end of the cut has reached the guide member, the distal portion of the catheter over the guidewire is of a sufficiently short length that the catheter may be drawn over the proximal end of the guidewire without releasing control of the guidewire or disturbing its position within the patient.
In order to accomodate an inflation lumen and a guidewire lumen disposed in a side-by-side relationship in the proximal catheter shaft, the catheter shaft may be made with an oblong or oval shaped cross-section. Although such a cross-section provides good pushability and trackability through a patient's vasculature, some clinicians who are accustomed to circular shafts find the feel of such shafts uncomfortable. In addition, it is easier to provide a better balance between back-bleed and interaction with a Touhy Borst fitting with a circular shaft which would lead to a reduction in friction between the catheter and the fitting. Thus, it is an object of this invention to provide the benefits of an MX catheter with a proximal catheter shaft having a side-by-side lumen relationship with an overall circular cross-section.
The present invention is a proximal catheter shaft constructed from an elongate tubular body with a generally circular cross-section that provides multiple lumens extending longitudinally throughout the length. The lumens include a central guidewire lumen and a peripheral inflation lumen that circumscribes the guidewire lumen. The inflation lumen has a generally C-shaped, or a partial annulus, cross-section. The discontinuous annulus shape of the inflation lumen defines a web and through that web extends a guidewire access cut.
The catheter shaft may rely upon an indwelling guidewire for stiffness or it may employ additional stiffening elements. When additional stiffening elements are included, they may include metal or polymer inserts extruded into the wall of the catheter shaft between the lumens. Alternatively, stiffening elements may be incorporated into a lumen. Furthermore, additional lumens may be included in the tubular body specifically designed to hold a fluid, thereby increasing the stiffness of the shaft. The stiffening members may be further customized to create a region where the shaft transitions from a relatively high stiffness to a relatively low stiffness.
The guidewire access cut extends radially through the web from the outer surface of the catheter to the guidewire lumen and provides direct access to the guidewire for a guidewire control member slideably mounted to the catheter. The guidewire control member may provide direct axial control over movement of the guidewire relative to the catheter shaft, or alternatively, may provide a means for ingress and egress of the guidewire from the guidewire lumen.
Further features and advantages of the invention, as well as the structure and operation of various embodiments of the invention, are described in detail below with reference to the accompanying drawings. It is noted that the invention is not limited to the specific embodiments described herein. Such embodiments are presented herein for illustrative purposes only. Additional embodiments will be apparent to persons skilled in the relevant art based on the teachings contained herein.
These and other features, aspects and advantages of the present invention will become better understood with reference to the following description, appended claims, and accompanying drawings where:
The present invention is now described with reference to the figures where like reference numbers indicate identical or functionally similar elements. Also in the figures, the left most digit of each reference number corresponds to the figure in which the reference number is first used. While specific configurations and arrangements are discussed, it should be understood that this is done for illustrative purposes only. A person skilled in the relevant art will recognize that other configurations and arrangements can be used without departing from the spirit and scope of the invention.
As shown in the exemplary embodiment of
In the embodiment shown in
In accordance with the invention, the inflation lumen 118 is disposed generally concentrically about a portion of guidewire lumen 116. Inflation lumen 118 partially circumscribes guidewire lumen 116 resulting in inflation lumen 118 having a generally C-shaped, or partial annulus, cross-section as shown in
The far proximal end 120 of the multi-lumen catheter 100 terminates with a hub (not shown). The hub is tailored to the type of guidewire control member 108 employed. Guidewire control member 108 may have one of many forms depending on the required utility. For example, guidewire control member 108 may be used to vary the effective OTW length of the multi-lumen catheter 100 in which case guidewire control member 108 will provide a proximal exit for guidewire 117. As a result, a single lumen hub, such as a Luer fitting, would be used. On the other hand, if the guidewire control member is used solely to assist with manipulation of guidewire 117, a bifurcated hub would be included.
Proximal shaft 102 is an elongate, flexible, tubular shaft which may be formed from polymeric materials, particularly high-density polyethylene, polyimide, polyamides, polyolefins, polyethylene block amide (PEBAX®) copolymer and various other polymeric materials suitable for use in medical devices. Preferably, proximal shaft 102 is made from high-density polyethylene due to its low friction characteristics. Proximal shaft 102 may be extruded or formed in another process known in the art for producing multi-lumen tubing used in a medical device.
The longitudinal stiffness of proximal shaft 102 may be customized. In the embodiment shown in
In a still further embodiment, multiple stiffening members 326 may be extruded into proximal shaft 102 as shown in
Where a second material is used, proximal shaft 102 may be created by a triple extrusion process wherein a triple extrusion die allows the simultaneous extrusion of two materials over stiffening member 326 integrating all three into one proximal shaft 102. Where a high density polyethylene is used for proximal shaft 102 it is preferable that the joint 328 be a polyolefin elastomer or polyolefin polymer with a lower modulus than polyethylene due to their tendency to adhere well to each other. As an alternative to the triple extrusion process, joint 328 may be constructed separately and incorporated into a void left during the manufacture of proximal shaft 102. If less compatible materials are used or if joint 328 is added as a separate unit, it may be necessary to employ an intermediate material to aid adhesion.
Stiffening members 326 may be constructed from metal or polymer and may be formed from wire, plate or rod in a flat, curved or generally cylindrical shape. If stiffening member 326 is curved, it can be pressed into its curved shape, cut from a hypotube, or extruded into a curved shape. If stiffening members 326 are manufactured from metal they may be stainless steel, titanium, tungsten, Nitinol or any other metal known in the art suitable for use in medical devices. It may be preferable, however, to use stainless steel to reduce the cost. If polymeric material is used, they may be any polymeric material having high rigidity and suitable for use in medical devices.
In alternative embodiments of proximal shaft 102, a portion of inflation lumen 118 may include longitudinal stiffness features. As shown in
Further yet, a separate stiffening lumen 332 may be incorporated into proximal shaft 102.
With reference to
Guidewire control member 108 allows direct manipulation of guidewire 117 disposed within proximal shaft 102. Direct manipulation of guidewire 117 may be achieved in multiple ways and for multiple purposes, as described below.
Guidewire control member 508 may be molded from a rigid plastic material, such as nylon or nylon based co-polymers, that is preferably lubricous. Alternatively, guidewire control member 508 may be made of a suitable metal, such as stainless steel, or guidewire control member 508 may have both metal components and plastic components. For ease in manufacturing, guidewire control member 508 may be comprised of molded parts that snap-fit together to form the final configuration.
Proximal shaft 102 and guidewire 117 both extend through guidewire control member 508, they merge at the juncture of the passageways, as shown in
In an alternative maneuver, guidewire 117 may be inserted or removed through guidewire passageway 542, while guidewire control member 508 is held stationary with respect to multi-lumen catheter 100. In this fashion, guidewire 117 can be removed from multi-lumen catheter 100 and exchanged with another wire. In yet another procedure, guidewire 117 and multi-lumen catheter 100 can be held relatively still while guidewire control member 508 is translated, thus “unzipping” and “zipping” guidewire 117 and proximal shaft 102 transversely apart or together, depending on which direction guidewire control member 508 is moved.
Two retaining arms 956 are disposed on distal end 952 of outer tubular member 844. Retaining arms 956 consist of two arcuate arms that form a portion of outer tubular member 844. Each arm 956 contains a tab 958 that extends into longitudinal bore 954 of outer tubular member 844 at its distal end 952. When guidewire control member 808 is assembled, the tabs prevent inner body 846 from slipping out of the outer tubular member 844 through its distal end 952. Retaining arms 956 are flexible in the radial direction and may be flexed radially outward to temporarily remove tabs 958 from the longitudinal bore 954 to permit insertion and removal of inner body 846 during the assembly or disassembly of guidewire control member 808. While two tabs 958 are shown positioned 180 degrees apart, a different number of tabs may be used, provided they are spaced sufficiently to prevent inner body 846 from slipping out of the outer tubular member 844. Although the stop shoulder 848 and retaining arms 956 are described as integral parts of the outer tubular member, it should be understood that those features may be created by separate elements such as threaded caps.
Inner body 846, generally functions as the guidewire control member 508, of the previously discussed embodiment. Inner body 846 has proximal and distal ends, 1060 and 1062 respectively. Catheter receiving bore 840 extends longitudinally through inner body 846 from proximal end 1060 to distal end 1062. In the present embodiment, unlike the embodiment shown in
It shall be understood that the single keel design may be substituted for the dual spreader design, shown in
In
As shown in
Clamp member 1372 extends radially inward from a clamp control member 1274. Clamp control member 1274 and clamp member 1372 extend through the guidewire control member 1208 and allow a clinician to manually engage a clamping force on the guidewire 117. In the present embodiment, a clamp spring 1368 is mounted to clamp control member 1274 and guidewire control member 1208. Clamp spring 1368 holds clamp member 1372 and clamp control member 1274 in a disengaged state when no external force is placed on clamp control member 1274. When clamp control member 1274 is pressed and clamp spring 1368 is compressed, it causes clamp member 1372 to extend further radially into the catheter receiving bore 1340, through side opening 1366 in tubular guidewire receiver 1370 and against guidewire 117. That engagement with guidewire 117 results in a frictional force that resists relative movement between guidewire 117 and guidewire control member 1208 allowing a practitioner to directly control the axial location of guidewire 117 within multi-lumen catheter 100.
Like guidewire control members 508 and 808, guidewire control member 1208 may be molded from a rigid plastic material, such as nylon or nylon based co-polymers, that is preferably lubricous. Alternatively, guidewire control member 1208 may be made of a suitable metal, such as stainless steel, or guidewire control member 1208 may have both metal components and plastic components. For ease in manufacturing, guidewire control member 1208 may be comprised of molded parts that snap-fit together to form the final configuration.
While this invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.
