Patent Application
20060047265
The present invention generally relates to medical catheters and medical apparatuses involving medical catheters. The present invention more particularly relates to Multi-Exchange catheters with improved guide members.
Cardiovascular disease, including atherosclerosis, is a leading cause of death in the U.S. The medical community has developed a number of methods and devices for treating coronary heart disease, some of which are specifically designed to treat the complications resulting from atherosclerosis and other forms of coronary arterial narrowing.
One method for treating atherosclerosis and 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 radial hydraulic expansion. The procedure is accomplished by inflating a balloon of a balloon catheter within the narrowed lumen of coronary artery.
In addition to PTCA, catheters are used for delivery of stents or grafts, therapeutic drugs (such as anti-vaso-occlusion agents or tumor treatment drugs) and radiopaque agents for radiographic viewing. Other uses for such catheters are well known in the art.
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 push the catheter into the vessel in a controlled manner from a position far away from the distalmost point of the catheter.
Catheters for PTCA and other procedures may include a proximal shaft, a transition section and a distal shaft having a flexible distal tip. In particular, the catheters have a proximal shaft, which is generally rigid for increased pushability and a more flexible distal shaft with a flexible distal tip for curving around particularly tortuous vessels. The proximal shaft may be made stiff by the insertion of a thin biocompatible tube, such as a stainless steel hypotube, into a lumen formed within the proximal shaft. The transition section is the portion of the catheter between the stiffer proximal shaft and the more flexible distal shaft, which provides a transition in flexibility between the two portions.
With some types of catheter construction, when an increase in resistance occurs during a procedure there is a tendency for portions of the catheter to collapse, buckle axially or kink, particularly in an area where flexibility of the catheter shaft shifts dramatically. Consequently, the transition section is often an area where the flexibility of the catheter gradually transitions between the stiff proximal shaft and the flexible distal shaft. It is known in the art to create a more gradual flexibility transition by spiral cutting a distal end of the hypotubing used to create stiffness in the proximal shaft. Typically, the spiral cut is longitudinally spaced farther apart at the hypotube proximal end creating an area of flexibility, and longitudinally spaced closer together at the hypotube distal end creating an area of even greater flexibility.
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 may be positioned next to, or enveloped within, an inflation shaft. Thus, 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 wire onto the proximal end of the guidewire to maintain control of the guidewire, slide the catheter off of the extended guidewire, slide the new catheter onto the guidewire and track back into position. Multiple operators are required to hold the extended guidewire in place while the original catheter is exchanged in order to maintain its sterility.
A RX catheter avoids the need for multiple operators when exchanging the catheter. With a rapid exchange catheter, the guidewire runs along the exterior of the catheter for all but the distalmost portion of the catheter. As such, the guidewire can be held in place without an extension when the catheter is removed from the body. However, one problem associated with RX catheters is the guidewire, and most of the catheter, must be removed from the body in order to exchange guidewires. Essentially the procedure must then start anew because both the guidewire and the catheter must be retracked to the treatment site. An OTW catheter, with the guidewire lumen extending the entire length of the catheter, allows for simple guidewire exchange.
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 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 catheter shaft and that extends radially from the guidewire lumen to an exterior surface of a catheter shaft. A guide member through which the shaft is slidably coupled cooperates with the longitudinal cut such that a guidewire may extend transversely into or out of the guidwire 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.
The guidewire is threaded into a guidewire lumen opening at the distal end of the catheter and out through the guide member. The guidewire lumen envelopes the guidewire as the catheter is advanced into the patient's vasculature while the guide member and guidewire are held stationary. 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.
While MX catheters provide many advantages over RX and OTW catheters, both RX and MX catheters need to be sealed effectively at the hemostasis valve. OTW catheters are readily sealed at the valve since the guidewire is within the catheter shaft which extends through the valve. RX and MX catheters have a catheter shaft and guidewire separated proximal to the hemostasis valve and thus an effective valve seal must take into consideration the catheter and guidewire separation for an RX catheter and with the guide member in the case of the MX catheter. For example, in a typical dye injection, the physician may pull a slight negative pressure to ensure no air bubbles are within the system prior to injecting the dye. If the physician pulls a very heavy negative pressure, there remains a possibility that air may enter the patient through the hemostasis valve if not sealed sufficiently around the catheter, guide wire and guide member of an MX catheter. Similarly, when a hemostasis valve has an active/passive gasket, if the valve is not properly closed down on an RX catheter shaft and guidewire, air may be drawn into the system when a very heavy vacuum is drawn.
Accordingly, it is desirable to provide an apparatus or system that improves shaft stability within the hemostasis valve and provides a secure seal for a Multi-Exchange catheter at the hemostatic valve location. It is also desirable to provide such an apparatus or system that can be implemented with a currently used catheter guide tool. In addition, it is desirable to provide such an apparatus that does not slow down guidewire insertion, contrast media injection, or other medical processes involving the catheter. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.
A system is provided for exchanging a catheter and guidewire in a patient. The system comprises a catheter and a guide member. The catheter comprises an elongate shaft having an exterior surface, a proximal end, and a distal end; a first lumen extending through the shaft from the shaft proximal end to the shaft distal end, and sized to receive a guidewire; and a longitudinal guideway extending distally from the shaft proximal end, and enabling transverse access from the shaft exterior surface to the first lumen. The guide member comprises a housing having a proximal end and a distal end; a catheter passageway extending through the housing from the proximal end to the distal end and adapted to slidably receive the catheter; a guidewire passageway extending from the housing proximal end into the catheter passageway, and comprising a tube adapted to merge the guidewire transversely through the guideway and into the first lumen; and a rigid nose cone attached to the housing distal end and having an aperture extending therethrough that is continuous with the catheter passageway and is adapted to slidably receive the catheter.
An apparatus is also provided for advancing and retracting a guidewire and a catheter having a lumen, an exterior surface, and a longitudinal guideway that enables transverse access from the catheter exterior surface to the lumen. The apparatus comprises a housing having a proximal end and a distal end; a catheter passageway extending through the housing from the proximal end to the distal end and adapted to slidably receive the catheter; a guidewire passageway extending from the housing proximal end into the catheter passageway, and comprising a tube adapted to merge the guidewire transversely through the guideway and into the first lumen; and a rigid nose cone attached to the housing distal end and having an aperture extending therethrough that is continuous with the catheter passageway and is adapted to slidably receive the catheter.
The present invention will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and
FIGS. 2A-D are cross sectional views of a catheter at points A-A, B-B, C-C, and D-D illustrated in
The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description.
The present invention is used with an MX catheter, an exemplary embodiment of which is illustrated in
The present invention includes a guide member for the MX catheter 12.
The catheter proximal shaft 22 described above can be modified to suit various needs. For example, the proximal shaft can be a tri-lumen shaft to provide passage for various drugs, fluids, wires, or other necessary compositions or equipment. Further, the proximal shaft may be oval, circular, or other suitable shape.
Returning to
Turning now to
The guide member main body 98 includes a catheter passageway 88 extending longitudinally in a generally straight line from the guide member proximal end 92 to the guide member distal end 94. A guidewire passageway 80 extends distally from the guide member proximal end 92 through an entrance port 82 into a tube 86 and then into the catheter guidewire lumen 30, although the catheter is not depicted in
The entrance port 82 is configured to mate with a conventional wire introducer tool and is tapered to aid in loading such a tool. The tube 86 may vary in its length, although in an exemplary embodiment of the invention the tube 86 extends through the catheter guidewire lumen 30 approximately thirty-five millimeters past the guide member distal end 94. The tube 86 may be formed from a flexible material such as a polyimide, and particularly the tube region that extends through the catheter guidewire lumen 30. In one embodiment of the invention the tube region that introduces the guidewire 14 into the guidewire lumen 30 may be substantially rigid to provide the necessary support for the guidewire 14.
The guide member 10 is made of blends of polyamides and polyolefins in an exemplary embodiment of the invention. Other exemplary materials include ceramics, metals such as stainless steel, and other polymers such as polyamides and liquid crystal polymers. Lubrication additives such as polyethylene micro-powders, fluoropolymers, silicone-based oils, fluoro-ether oils, molybdenum disulphide, and polyethylene oxide may be included. Reinforcing additives such as nano-clays, graphite, carbon fibers, glass fibers, polyesters, polyketones, polyimides, polysulphones, polyoxymethylenes, polyolefins, cross-linked polyolefins may also be included, along with compatibilizers based on polyolefins, such as grafted polyolefins, ceramics, and metals.
An exemplary guide member operation will now be described, although the procedures in the following description clearly set forth only one of many operations enabled by the guide member 10. The exemplary guide member operation is discussed with reference to
As the distal shaft 20 enters the patient, the guide member 10 can be brought near the hemostasis valve 40. The guide member 10 is seated adjacent to the hemostasis valve 40 and is equipped with a rigid nose cone 85 that surrounds the distal shaft and is inserted into the hemostasis valve 40. The proximal shaft 22 is then advanced through the guide member, and the keel 84 engages the catheter guideway 32. After the catheter 12 is inserted, a gasket 42 on the hemostasis valve 40 that slidably receives the nose cone 85 is tightened to form a substantially air tight seal with the nose cone 85. Although the gasket 42 is tightened around the nose cone 85 using threaded regions 43, 44 in the embodiment depicted in
Without the rigid nose cone 85 surrounding the distal shaft 20, the gasket 42 would typically clamp directly onto the distal shaft 20. Since the tube 86 extends in to the distal shaft 20, the tube 86 would typically be subjected to the valve clamping force. However, the rigid nose cone 85 prevents any clamping force from being exerted on the distal shaft 86 and allows the catheter 12 to be advanced and retracted as necessary without any frictional resistance from the hemostasis valve 40.
If a wire change is required, one simply withdraws the guidewire 14 from the guide member 10 as the guide member 10 is seated against the valve and as the proximal shaft 22 remains in the patient. A new guidewire is then inserted into the catheter through the passageway 80. If a catheter exchange is required, one simply holds the guidewire 14 in place and begins moving the proximal shaft 22 proximally through the guide member. Another catheter may then be backloaded onto the guidewire 14 and introduced into the patient as described above.
In order to maintain shaft stability and prevent air aspiration into the guidewire lumen 30 at the catheter proximal end, the guidewire passageway 80 is adapted to include airflow reduction components that prevent or minimize air movement through the passageway 80. In one exemplary embodiment of the invention, one such component is a seal 81 that forms an airtight seal with the nose cone 85 and the proximal shaft 22. As depicted in
The passageway 80 includes at least one o-ring body 83 as another passive seal, positioned in the guidewire entrance port 82 adjacent to the tube 86. The o-ring body 83 can be formed of a flexible material, although a substantially rigid material will reduce friction with the guidewire 14. The o-ring body 83 can be positioned in any suitable location in the guidewire passageway 80 to effectively prevent or substantially minimize airflow therethrough. An exemplary location for the o-ring body 83 is the entrance port 82, although the o-ring body 83 may be disposed within the tube 86 or even the keel 84. The o-ring body 83 has an outer diameter that can approximate the inner diameter of the guidewire passageway area in which the o-ring body is positioned. The o-ring body 83 also has an inner diameter that approximates the guidewire diameter in order to provide a substantially airtight seal with the guidewire 14.
In another embodiment of the invention, the tube 86 has a substantially uniform inner diameter, but includes a fixed reduced inner diameter region 87 that prevents air movement therethrough. The term “fixed” in this sense means that the reduced inner diameter region 87 is a passive, unchanging airflow reduction body. The reduced inner diameter region 87 has a smaller inner diameter than the rest of the tube 86, or at least a smaller inner diameter than the reduced inner diameter region's immediate or nearby vicinity, and consequently substantially reduces the amount of air that flows through the tube 86 without impeding guidewire movement. The reduced inner diameter region 87 is formed distally with respect to the keel 84, and consequently is disposed inside the guidewire lumen 30 during use in an exemplary embodiment. However, the reduced inner diameter region 87 may be formed elsewhere within the passageway, and is depicted in
In an exemplary embodiment depicted in
One reason that the reduced inner diameter region 87 is highly effective at restricting air passage through the tube 86 is the seal uniformity across the region 87. Aspiration prevention qualities are superior if a full seal entirely surrounds the tube 86. Aspiration prevention also is found to be positively related to the longitudinal length of the small diameter region 87. Consequently, doubling the small diameter region length has the effect of approximately doubling the resistance to air aspiration.
Although each of the above airflow reduction components are discussed as separate embodiments of the invention, they may be used in combination as depicted in
In an embodiment similar to the embodiment illustrated in
In another exemplary embodiment depicted in
In another exemplary embodiment of the invention, a gasket 91 surrounds the catheter 12 at the guide member proximal end 92, and preferably further surrounds the lubricious wire 90 as another passive seal. The gasket can be an annular body, but has an inner passageway that approximates the exterior surface of the proximal shaft 22. The gasket 91 seals any gaps between the catheter 12 and the guide member 10 at the catheter passageway proximal end, and also ensures that the proximal shaft's longitudinal cut forming the guideway 32 into the guidewire lumen 30 is closed.
While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing the exemplary embodiment or exemplary embodiments. It should be understood that various changes can be made in the function and arrangement of elements without departing from the scope of the invention as set forth in the appended claims and the legal equivalents thereof.
